National Library of Energy BETA

Sample records for reactive transport models

  1. Three-Dimensional Modeling of the Reactive Transport of CO2 and...

    Office of Scientific and Technical Information (OSTI)

    ... Subject: CO2 reservoir, reactive transport, geochemistry, geomechanics, geomechanical modeling, mineral composition, homogenization, fault, hydraulic fracture, elastic modulus Word ...

  2. Uranium transport in a crushed granodiorite: Experiments and reactive transport modeling

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dittrich, T. M.; Reimus, P. W.

    2015-02-12

    The primary objective of this study was to develop and demonstrate an experimental method to refine and better parameterize process models for reactive contaminant transport in aqueous subsurface environments and to reduce conservatism in such models without attempting to fully describe the geochemical system.

  3. Maximum likelihood Bayesian model averaging and its predictive analysis for groundwater reactive transport models

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lu, Dan; Ye, Ming; Curtis, Gary P.

    2015-08-01

    While Bayesian model averaging (BMA) has been widely used in groundwater modeling, it is infrequently applied to groundwater reactive transport modeling because of multiple sources of uncertainty in the coupled hydrogeochemical processes and because of the long execution time of each model run. To resolve these problems, this study analyzed different levels of uncertainty in a hierarchical way, and used the maximum likelihood version of BMA, i.e., MLBMA, to improve the computational efficiency. Our study demonstrates the applicability of MLBMA to groundwater reactive transport modeling in a synthetic case in which twenty-seven reactive transport models were designed to predict themore » reactive transport of hexavalent uranium (U(VI)) based on observations at a former uranium mill site near Naturita, CO. Moreover, these reactive transport models contain three uncertain model components, i.e., parameterization of hydraulic conductivity, configuration of model boundary, and surface complexation reactions that simulate U(VI) adsorption. These uncertain model components were aggregated into the alternative models by integrating a hierarchical structure into MLBMA. The modeling results of the individual models and MLBMA were analyzed to investigate their predictive performance. The predictive logscore results show that MLBMA generally outperforms the best model, suggesting that using MLBMA is a sound strategy to achieve more robust model predictions relative to a single model. MLBMA works best when the alternative models are structurally distinct and have diverse model predictions. When correlation in model structure exists, two strategies were used to improve predictive performance by retaining structurally distinct models or assigning smaller prior model probabilities to correlated models. Since the synthetic models were designed using data from the Naturita site, the results of this study are expected to provide guidance for real-world modeling. Finally

  4. Maximum likelihood Bayesian model averaging and its predictive analysis for groundwater reactive transport models

    SciTech Connect (OSTI)

    Lu, Dan; Ye, Ming; Curtis, Gary P.

    2015-08-01

    While Bayesian model averaging (BMA) has been widely used in groundwater modeling, it is infrequently applied to groundwater reactive transport modeling because of multiple sources of uncertainty in the coupled hydrogeochemical processes and because of the long execution time of each model run. To resolve these problems, this study analyzed different levels of uncertainty in a hierarchical way, and used the maximum likelihood version of BMA, i.e., MLBMA, to improve the computational efficiency. Our study demonstrates the applicability of MLBMA to groundwater reactive transport modeling in a synthetic case in which twenty-seven reactive transport models were designed to predict the reactive transport of hexavalent uranium (U(VI)) based on observations at a former uranium mill site near Naturita, CO. Moreover, these reactive transport models contain three uncertain model components, i.e., parameterization of hydraulic conductivity, configuration of model boundary, and surface complexation reactions that simulate U(VI) adsorption. These uncertain model components were aggregated into the alternative models by integrating a hierarchical structure into MLBMA. The modeling results of the individual models and MLBMA were analyzed to investigate their predictive performance. The predictive logscore results show that MLBMA generally outperforms the best model, suggesting that using MLBMA is a sound strategy to achieve more robust model predictions relative to a single model. MLBMA works best when the alternative models are structurally distinct and have diverse model predictions. When correlation in model structure exists, two strategies were used to improve predictive performance by retaining structurally distinct models or assigning smaller prior model probabilities to correlated models. Since the synthetic models were designed using data from the Naturita site, the results of this study are expected to provide guidance for real-world modeling. Finally, limitations of

  5. Pore scale modeling of reactive transport involved in geologic CO2 sequestration

    SciTech Connect (OSTI)

    Kang, Qinjin; Lichtner, Peter C; Viswanathan, Hari S; Abdel-fattah, Amr I

    2009-01-01

    We apply a multi-component reactive transport lattice Boltzmann model developed in previolls studies to modeling the injection of a C02 saturated brine into various porous media structures at temperature T=25 and 80 C. The porous media are originally consisted of calcite. A chemical system consisting of Na+, Ca2+, Mg2+, H+, CO2(aq), and CI-is considered. The fluid flow, advection and diHusion of aqueous species, homogeneous reactions occurring in the bulk fluid, as weB as the dissolution of calcite and precipitation of dolomite are simulated at the pore scale. The effects of porous media structure on reactive transport are investigated. The results are compared with continuum scale modeling and the agreement and discrepancy are discussed. This work may shed some light on the fundamental physics occurring at the pore scale for reactive transport involved in geologic C02 sequestration.

  6. Reaction-based reactive transport modeling of Fe(III)

    SciTech Connect (OSTI)

    Kemner, K.M.; Kelly, S.D.; Burgos, Bill; Roden, Eric

    2006-06-01

    This research project (started Fall 2004) was funded by a grant to Argonne National Laboratory, The Pennsylvania State University, and The University of Alabama in the Integrative Studies Element of the NABIR Program (DE-FG04-ER63914/63915/63196). Dr. Eric Roden, formerly at The University of Alabama, is now at the University of Wisconsin, Madison. Our project focuses on the development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. This work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and is directly aligned with the Scheibe et al. NABIR FRC Field Project at Area 2.

  7. Coupled reactive mass transport and fluid flow: Issues in model verification

    SciTech Connect (OSTI)

    Freedman, Vicky L.; Ibaraki, Motomu

    2003-01-03

    Model verification and validation are both important steps in the development of reactive transport models. In this paper, a distinction is made between verification and validation, and the focus is on codifying the issues of verification for a numerical, reactive transport flow model. First, the conceptual basis of model verification is reviewed, which shows that verification should be understood as a first step in model development, and be followed by a protocol that assures that the model accurately represents system behavior. Second, commonly used procedures and methods of model verification are presented. In the third part of this paper, an intercomparison of models is used to demonstrate that model verification can be performed despite differences in hydrogeochemical transport code formulations. Results of an example simulation of transport are presented in which the numerical model is tested against other hydrogeochemical codes. Different kinetic formulations between solid and aqueous phases used among numerical models complicates model verification. This test problem involves uranium transport under conditions of varying pH and oxidation potential, with reversible precipitation of calcium uranate and coffinite. Results between the different hydrogeochemical transport codes show differences in oxidation potentials, but similarities in mineral assemblages and aqueous transport patterns. Because model verification can be further complicated by differences in the approach for solving redox problems, a comparison of a fugacity approach to both the external approach (based on hypothetical electron activity) and effective internal approach (based on conservation of electrons) is performed. The comparison demonstrates that the oxygen fugacity approach produces different redox potentials and mineral assemblages than both the effective internal and external approaches.

  8. Application of a data assimilation method via an ensemble Kalman filter to reactive urea hydrolysis transport modeling

    SciTech Connect (OSTI)

    Juxiu Tong; Bill X. Hu; Hai Huang; Luanjin Guo; Jinzhong Yang

    2014-03-01

    With growing importance of water resources in the world, remediations of anthropogenic contaminations due to reactive solute transport become even more important. A good understanding of reactive rate parameters such as kinetic parameters is the key to accurately predicting reactive solute transport processes and designing corresponding remediation schemes. For modeling reactive solute transport, it is very difficult to estimate chemical reaction rate parameters due to complex processes of chemical reactions and limited available data. To find a method to get the reactive rate parameters for the reactive urea hydrolysis transport modeling and obtain more accurate prediction for the chemical concentrations, we developed a data assimilation method based on an ensemble Kalman filter (EnKF) method to calibrate reactive rate parameters for modeling urea hydrolysis transport in a synthetic one-dimensional column at laboratory scale and to update modeling prediction. We applied a constrained EnKF method to pose constraints to the updated reactive rate parameters and the predicted solute concentrations based on their physical meanings after the data assimilation calibration. From the study results we concluded that we could efficiently improve the chemical reactive rate parameters with the data assimilation method via the EnKF, and at the same time we could improve solute concentration prediction. The more data we assimilated, the more accurate the reactive rate parameters and concentration prediction. The filter divergence problem was also solved in this study.

  9. Chombo-Crunch: Modeling Pore-Scale Reactive Transport in Carbon

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Sequestration | Argonne Leadership Computing Facility Transient pH on calcite grains in capillary tube experiment. 1 billion grid points computed on 48K cores. 1 micron resolution. Transient pH on calcite grains in capillary tube experiment. 1 billion grid points computed on 48K cores. 1 micron resolution. David Trebotich, Lawrence Berkeley National Laboratory Chombo-Crunch: Modeling Pore-Scale Reactive Transport in Carbon Sequestration PI Name: David Trebotich PI Email: treb@lbl.gov

  10. A Dual Regime Reactive Transport Model for Simulation of High Level Waste Tank Closure Scenarios - 13375

    SciTech Connect (OSTI)

    Sarkar, Sohini; Kosson, David S.; Brown, Kevin; Garrabrants, Andrew C.; Meeussen, Hans; Van der Sloot, Hans

    2013-07-01

    A numerical simulation framework is presented in this paper for estimating evolution of pH and release of major species from grout within high-level waste tanks after closure. This model was developed as part of the Cementitious Barriers Partnership. The reactive transport model consists of two parts - (1) transport of species, and (2) chemical reactions. The closure grout can be assumed to have varying extents of cracking and composition for performance assessment purposes. The partially or completely degraded grouted tank is idealized as a dual regime system comprising of a mobile region having solid materials with cracks and macro-pores, and an immobile/stagnant region having solid matrix with micropores. The transport profiles of the species are calculated by incorporating advection of species through the mobile region, diffusion of species through the immobile/stagnant region, and exchange of species between the mobile and immobile regions. A geochemical speciation code in conjunction with the pH dependent test data for a grout material is used to obtain a mineral set that best describes the trends in the test data of the major species. The dual regime reactive transport model predictions are compared with the release data from an up-flow column percolation test. The coupled model is then used to assess effects of crack state of the structure, rate and composition of the infiltrating water on the pH evolution at the grout-waste interface. The coupled reactive transport model developed in this work can be used as part of the performance assessment process for evaluating potential risks from leaching of a cracked tank containing elements of human health and environmental concern. (authors)

  11. A reaction-based paradigm to model reactive chemical transport in groundwater with general kinetic and equilibrium reactions

    SciTech Connect (OSTI)

    Zhang, Fan; Yeh, Gour-Tsyh; Parker, Jack C; Brooks, Scott C; Pace, Molly; Kim, Young Jin; Jardine, Philip M; Watson, David B

    2007-01-01

    This paper presents a reaction-based water quality transport model in subsurface flow systems. Transport of chemical species with a variety of chemical and physical processes is mathematically described by M partial differential equations (PDEs). Decomposition via Gauss-Jordan column reduction of the reaction network transforms M species reactive transport equations into two sets of equations: a set of thermodynamic equilibrium equations representing NE equilibrium reactions and a set of reactive transport equations of M-NE kinetic-variables involving no equilibrium reactions (a kinetic-variable is a linear combination of species). The elimination of equilibrium reactions from reactive transport equations allows robust and efficient numerical integration. The model solves the PDEs of kinetic-variables rather than individual chemical species, which reduces the number of reactive transport equations and simplifies the reaction terms in the equations. A variety of numerical methods are investigated for solving the coupled transport and reaction equations. Simulation comparisons with exact solutions were performed to verify numerical accuracy and assess the effectiveness of various numerical strategies to deal with different application circumstances. Two validation examples involving simulations of uranium transport in soil columns are presented to evaluate the ability of the model to simulate reactive transport with complex reaction networks involving both kinetic and equilibrium reactions.

  12. Coupling a Genome-Scale Metabolic Model with a Reactive Transport Model to Describe In Situ Uranium Bioremediation

    SciTech Connect (OSTI)

    Scheibe, Timothy D.; Mahadevan, Radhakrishnan; Fang, Yilin; Garg, Srinath; Long, Philip E.; Lovley, Derek R.

    2009-03-01

    Quantitative numerical simulation codes known as reactive transport models are widely used for simulating the hydrologic transport and geochemical speciation of dissolved constituents in the subsurface (Steefel et al., 2005). Because the activity of microorganisms strongly influences the fate of many constituents, both organic and inorganic, such models often include microbially-mediated reactions in their reaction networks (Hunter et al., 1998; Burgos et al., 2002; Fang et al., 2006; Scheibe et al., 2006; Yabusaki et al., 2007). However, the canonical form and stoichiometry of microbial reactions, reaction rate formulations and parameters, and biomass growth yield coefficients are prescribed a priori and applied over the entire range of simulated conditions. This approach does not account for the fact that fundamental microbial functions vary in response to local variations in environmental conditions(Stewart and Franklin, 2008). Multiple alternative reaction pathways are encoded in microbial genomes; specific pathways become active or inactive in response to, for example, nutrient limitation. Recent advances in genomic analysis allow us to define cellular metabolic networks, and accurate predictions of active pathways and reaction fluxes have been made using constraint-based metabolic models (Mahadevan et al., 2002; Price et al., 2003; Reed and Palsson, 2003; Mahadevan et al., 2006). Here, we demonstrate for the first time a methodology of coupling constraint-based metabolic models with reactive transport models. Our approach integrates advanced microbiological characterization, hydrology, and geochemistry in a powerful manner that will significantly improve subsurface reactive transport models.

  13. Multiphase flow and multicomponent reactive transport model of the ventilation experiment in Opalinus clay

    SciTech Connect (OSTI)

    Zheng, L.; Samper, J.; Montenegro, L.; Major, J.C.

    2008-10-15

    During the construction and operational phases of a high-level radioactive waste (HLW) repository constructed in a clay formation, ventilation of underground drifts will cause desaturation and oxidation of the rock. The Ventilation Experiment (VE) was performed in a 1.3 m diameter unlined horizontal microtunnel on Opalinus clay at Mont Terri underground research laboratory in Switzerland to evaluate the impact of desaturation on rock properties. A multiphase flow and reactive transport model of VE is presented here. The model accounts for liquid, vapor and air flow, evaporation/condensation and multicomponent reactive solute transport with kinetic dissolution of pyrite and siderite and local-equilibrium dissolution/precipitation of calcite, ferrihydrite, dolomite, gypsum and quartz. Model results reproduce measured vapor flow, liquid pressure and hydrochemical data and capture the trends of measured relative humidities, although such data are slightly overestimated near the rock interface due to uncertainties in the turbulence factor. Rock desaturation allows oxygen to diffuse into the rock and triggers pyrite oxidation, dissolution of calcite and siderite, precipitation of ferrihydrite, dolomite and gypsum and cation exchange. pH in the unsaturated rock varies from 7.8 to 8 and is buffered by calcite. Computed changes in the porosity and the permeability of Opalinus clay in the unsaturated zone caused by oxidation and mineral dissolution/precipitation are smaller than 5%. Therefore, rock properties are not expected to be affected significantly by ventilation of underground drifts during construction and operational phases of a HLW repository in clay.

  14. Reactive chemical transport in ground-water hydrology: Challenges to mathematical modeling

    SciTech Connect (OSTI)

    Narasimhan, T.N.; Apps, J.A.

    1990-07-01

    For a long time, earth scientists have qualitatively recognized that mineral assemblages in soils and rocks conform to established principles of chemistry. In the early 1960's geochemists began systematizing this knowledge by developing quantitative thermodynamic models based on equilibrium considerations. These models have since been coupled with advective-dispersive-diffusive transport models, already developed by ground-water hydrologists. Spurred by a need for handling difficult environmental issues related to ground-water contamination, these models are being improved, refined and applied to realistic problems of interest. There is little doubt that these models will play an important role in solving important problems of engineering as well as science over the coming years. Even as these models are being used practically, there is scope for their improvement and many challenges lie ahead. In addition to improving the conceptual basis of the governing equations, much remains to be done to incorporate kinetic processes and biological mediation into extant chemical equilibrium models. Much also remains to be learned about the limits to which model predictability can be reasonably taken. The purpose of this paper is to broadly assess the current status of knowledge in modeling reactive chemical transport and to identify the challenges that lie ahead.

  15. Geophysical monitoring and reactive transport modeling of ureolytically-driven calcium carbonate precipitation

    SciTech Connect (OSTI)

    Wu, Y.; Ajo-Franklin, J.B.; Spycher, N.; Hubbard, S.S.; Zhang, G.; Williams, K.H.; Taylor, J.; Fujita, Y.; Smith, R.

    2011-07-15

    Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH{sub 4}{sup

  16. Geophysical Monitoring and Reactive Transport Modeling of Ureolytically-Driven Calcium Carbonate Precipitation

    SciTech Connect (OSTI)

    Yuxin Wu; Jonathan B. Ajo-Franklin; Nicolas Spycher; Susan S. Hubbard; Guoxiang Zhang; Kenneth H. Williams; Joanna Taylor; Yoshiko Fujita; Robert Smith

    2011-09-01

    Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH4

  17. Subsurface Multiphase Flow and Multicomponent Reactive Transport Modeling using High-Performance Computing

    SciTech Connect (OSTI)

    Hammond, Glenn E.; Lichtner, Peter C.; Lu, Chuan

    2007-07-16

    Numerical modeling has become a critical tool to the U.S. Department of Energy for evaluating the environmental impact of alternative energy sources and remediation strategies for legacy waste sites. Unfortunately, the physical and chemical complexity of many sites overwhelms the capabilities of even most state of the art groundwater models. Of particular concern are the representation of highly-heterogeneous stratified rock/soil layers in the subsurface and the biological and geochemical interactions of chemical species within multiple fluid phases. Clearly, there is a need for higher-resolution modeling (i.e. more spatial, temporal, and chemical degrees of freedom) and increasingly mechanistic descriptions of subsurface physicochemical processes. We present SciDAC-funded research being performed in the development of PFLOTRAN, a parallel multiphase flow and multicomponent reactive transport model. Written in Fortran90, PFLOTRAN is founded upon PETSc data structures and solvers. We are employing PFLOTRAN in the simulation of uranium transport at the Hanford 300 Area, a contaminated site of major concern to the Department of Energy, the State of Washington, and other government agencies. By leveraging the billions of degrees of freedom available through high-performance computation using tens of thousands of processors, we can better characterize the release of uranium into groundwater and its subsequent transport to the Columbia River, and thereby better understand and evaluate the effectiveness of various proposed remediation strategies.

  18. Subsurface Multiphase Flow and Multicomponent Reactive Transport Modeling using High-Performance Computing

    SciTech Connect (OSTI)

    Hammond, Glenn E.; Lichtner, Peter C.; Lu, Chuan

    2007-08-01

    Numerical modeling has become a critical tool to the Department of Energy for evaluating the environmental impact of alternative energy sources and remediation strategies for legacy waste sites. Unfortunately, the physical and chemical complexity of many sites overwhelms the capabilities of even most state of the art groundwater models. Of particular concern are the representation of highly-heterogeneous stratified rock/soil layers in the subsurface and the biological and geochemical interactions of chemical species within multiple fluid phases. Clearly, there is a need for higher-resolution modeling (i.e. more spatial, temporal, and chemical degrees of freedom) and increasingly mechanistic descriptions of subsurface physicochemical processes. We present research being performed in the development of PFLOTRAN, a parallel multiphase flow and multicomponent reactive transport model. Written in Fortran90, PFLOTRAN is founded upon PETSc data structures and solvers and has exhibited impressive strong scalability on up to 4000 processors on the ORNL Cray XT3. We are employing PFLOTRAN in the simulation of uranium transport at the Hanford 300 Area, a contaminated site of major concern to the Department of Energy, the State of Washington, and other government agencies where overly-simplistic historical modeling erroneously predicted decade removal times for uranium by ambient groundwater flow. By leveraging the billions of degrees of freedom available through high-performance computation using tens of thousands of processors, we can better characterize the release of uranium into groundwater and its subsequent transport to the Columbia River, and thereby better understand and evaluate the effectiveness of various proposed remediation strategies.

  19. Reaction-Based Reactive Transport Modeling of Fe(III) and U(V) Reduction

    SciTech Connect (OSTI)

    Burgos, William D.; Roden, Eric E.; Yeh, Gour-Tsyh

    2005-06-01

    Our new research project (started Fall 2004) was funded by a grant to The Pennsylvania State University, University of Central Florida, and The University of Alabama in the Integrative Studies Element of the NABIR Program (DE-FG04-ER63914/63915/63196). Our previous NABIR project (DE-FG02-01ER63180/63181/63182, funded within the Biotransformation Element) focused on (1) microbial reduction of Fe(III) and U(VI) individually, and concomitantly in natural sediments, (2) Fe(III) oxide surface chemistry, specifically with respect to reactions with Fe(II) and U(VI), (3) the influence of humic substances on Fe(III) and U(VI) bioreduction, and on U(VI) complexation, and (4) the development of reaction-based reactive transport biogeochemical models to numerically simulate our experimental results. The new project focuses on the development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. This work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and is directly aligned with the Scheibe et al. NABIR FRC Field Project at Area 2.

  20. The Development and Application of Reactive Transport Modeling Techniques to Study Radionuclide Migration at Yucca Mountain, NV

    SciTech Connect (OSTI)

    Viswanathan, Hari Selvi

    1999-09-01

    Yucca Mountain, Nevada has been chosen as a possible site for the first high level radioactive waste repository in the United States. As part of the site investigation studies, we need to make scientifically rigorous estimations of radionuclide migration in the event of a repository breach. Performance assessment models used to make these estimations are computationally intensive. We have developed two reactive transport modeling techniques to simulate radionuclide transport at Yucca Mountain: (1) the selective coupling approach applied to the convection-dispersion-reaction (CDR) model and (2) a reactive stream tube approach (RST). These models were designed to capture the important processes that influence radionuclide migration while being computationally efficient. The conventional method of modeling reactive transport models is to solve a coupled set of multi-dimensional partial differential equations for the relevant chemical components in the system. We have developed an iterative solution technique, denoted the selective coupling method, that represents a versatile alternative to traditional uncoupled iterative techniques and the filly coupled global implicit method. We show that selective coupling results in computational and memory savings relative to these approaches. We develop RST as an alternative to the CDR method for solving large two- or three-dimensional reactive transport simulations for cases in which one is interested in predicting the flux across a specific control plane. In the RST method, the multidimensional problem is reduced to a series of one-dimensional transport simulations along streamlines. The key assumption with RST is that mixing at the control plane approximates the transverse dispersion between streamlines. We compare the CDR and RST approaches for several scenarios that are relevant to the Yucca Mountain Project. For example, we apply the CDR and RST approaches to model an ongoing field experiment called the Unsaturated Zone

  1. Development of Modeling Methods and Tools for Predicting Coupled Reactive Transport Processes in Porous Media at Multiple Scales

    SciTech Connect (OSTI)

    Clement, T Prabhakar; Barnett, Mark O; Zheng, Chunmiao; Jones, Norman L

    2010-05-05

    DE-FG02-06ER64213: Development of Modeling Methods and Tools for Predicting Coupled Reactive Transport Processes in Porous Media at Multiple Scales Investigators: T. Prabhakar Clement (PD/PI) and Mark O. Barnett (Auburn), Chunmiao Zheng (Univ. of Alabama), and Norman L. Jones (BYU). The objective of this project was to develop scalable modeling approaches for predicting the reactive transport of metal contaminants. We studied two contaminants, a radioactive cation [U(VI)] and a metal(loid) oxyanion system [As(III/V)], and investigated their interactions with two types of subsurface materials, iron and manganese oxyhydroxides. We also developed modeling methods for describing the experimental results. Overall, the project supported 25 researchers at three universities. Produced 15 journal articles, 3 book chapters, 6 PhD dissertations and 6 MS theses. Three key journal articles are: 1) Jeppu et al., A scalable surface complexation modeling framework for predicting arsenate adsorption on goethite-coated sands, Environ. Eng. Sci., 27(2): 147-158, 2010. 2) Loganathan et al., Scaling of adsorption reactions: U(VI) experiments and modeling, Applied Geochemistry, 24 (11), 2051-2060, 2009. 3) Phillippi, et al., Theoretical solid/solution ratio effects on adsorption and transport: uranium (VI) and carbonate, Soil Sci. Soci. of America, 71:329-335, 2007

  2. Reactive transport modeling of stable carbon isotope fractionation in a multi-phase multi-component system during carbon sequestration

    SciTech Connect (OSTI)

    Zhang, Shuo [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); DePaolo, Donald J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zheng, Liange [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mayer, Bernhard [Univ. of Calgary (Canada). Dept. of Geosciences

    2014-12-31

    Carbon stable isotopes can be used in characterization and monitoring of CO2 sequestration sites to track the migration of the CO2 plume and identify leakage sources, and to evaluate the chemical reactions that take place in the CO2-water-rock system. However, there are few tools available to incorporate stable isotope information into flow and transport codes used for CO2 sequestration problems. We present a numerical tool for modeling the transport of stable carbon isotopes in multiphase reactive systems relevant to geologic carbon sequestration. The code is an extension of the reactive transport code TOUGHREACT. The transport module of TOUGHREACT was modified to include separate isotopic species of CO2 gas and dissolved inorganic carbon (CO2, CO32-, HCO3-,). Any process of transport or reaction influencing a given carbon species also influences its isotopic ratio. Isotopic fractionation is thus fully integrated within the dynamic system. The chemical module and database have been expanded to include isotopic exchange and fractionation between the carbon species in both gas and aqueous phases. The performance of the code is verified by modeling ideal systems and comparing with theoretical results. Efforts are also made to fit field data from the Pembina CO2 injection project in Canada. We show that the exchange of carbon isotopes between dissolved and gaseous carbon species combined with fluid flow and transport, produce isotopic effects that are significantly different from simple two-component mixing. These effects are important for understanding the isotopic variations observed in field demonstrations.

  3. Reactive transport modeling of stable carbon isotope fractionation in a multi-phase multi-component system during carbon sequestration

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Shuo; DePaolo, Donald J.; Zheng, Liange; Mayer, Bernhard

    2014-12-31

    Carbon stable isotopes can be used in characterization and monitoring of CO2 sequestration sites to track the migration of the CO2 plume and identify leakage sources, and to evaluate the chemical reactions that take place in the CO2-water-rock system. However, there are few tools available to incorporate stable isotope information into flow and transport codes used for CO2 sequestration problems. We present a numerical tool for modeling the transport of stable carbon isotopes in multiphase reactive systems relevant to geologic carbon sequestration. The code is an extension of the reactive transport code TOUGHREACT. The transport module of TOUGHREACT was modifiedmore » to include separate isotopic species of CO2 gas and dissolved inorganic carbon (CO2, CO32-, HCO3-,…). Any process of transport or reaction influencing a given carbon species also influences its isotopic ratio. Isotopic fractionation is thus fully integrated within the dynamic system. The chemical module and database have been expanded to include isotopic exchange and fractionation between the carbon species in both gas and aqueous phases. The performance of the code is verified by modeling ideal systems and comparing with theoretical results. Efforts are also made to fit field data from the Pembina CO2 injection project in Canada. We show that the exchange of carbon isotopes between dissolved and gaseous carbon species combined with fluid flow and transport, produce isotopic effects that are significantly different from simple two-component mixing. These effects are important for understanding the isotopic variations observed in field demonstrations.« less

  4. Pore Scale Modeling of the Reactive Transport of Chromium in the Cathode of a Solid Oxide Fuel Cell

    SciTech Connect (OSTI)

    Ryan, Emily M.; Tartakovsky, Alexandre M.; Recknagle, Kurtis P.; Khaleel, Mohammad A.; Amon, Cristina

    2011-01-01

    We present a pore scale model of a solid oxide fuel cell (SOFC) cathode. Volatile chromium species are known to migrate from the current collector of the SOFC into the cathode where over time they decrease the voltage output of the fuel cell. A pore scale model is used to investigate the reactive transport of chromium species in the cathode and to study the driving forces of chromium poisoning. A multi-scale modeling approach is proposed which uses a cell level model of the cathode, air channel and current collector to determine the boundary conditions for a pore scale model of a section of the cathode. The pore scale model uses a discrete representation of the cathode to explicitly model the surface reactions of oxygen and chromium with a cathode material. The pore scale model is used to study the reaction mechanisms of chromium by considering the effects of reaction rates, diffusion coefficients, chromium vaporization, and oxygen consumption on chromiums deposition in the cathode. The study shows that chromium poisoning is most significantly affected by the chromium reaction rates in the cathode and that the reaction rates are a function of the local current density in the cathode.

  5. Building Conceptual Models of Field-Scale Uranium Reactive Transport in a Dynamic Vadose Zone-Aquifer-River System

    SciTech Connect (OSTI)

    Yabusaki, Steven B.; Fang, Yilin; Waichler, Scott R.

    2008-12-04

    Subsurface simulation is being used to build, test, and couple conceptual process models to better understand controls on a 0.4 km by 1.0 km uranium plume that has persisted above the drinking water standard in the groundwater of the Hanford 300 Area over the last 15 years. At this site, uranium-contaminated sediments in the vadose zone and aquifer are subject to significant variations in water levels and velocities driven by the diurnal, weekly, seasonal, and episodic Columbia River stage dynamics. Groundwater flow reversals typically occur twice a day with significant exchange of river water and groundwater in the near-river aquifer. Mixing of the dilute solution chemistry of the river with the groundwater complicates the uranium sorption behavior as the mobility of U(VI) has been shown experimentally to be a function of pH, carbonate, calcium, and uranium. Furthermore, uranium mass transfer between solid and aqueous phases has been observed to be rate-limited in the context of the high groundwater velocities resulting from the river stage fluctuations and the highly transmissive sediments (hydraulic conductivities ~1500 m/d). One- and two-dimensional vertical cross-sectional simulations of variably-saturated flow and reactive transport, based on laboratory-derived models of distributed rate mass transfer and equilibrium multicomponent surface complexation, are used to assess uranium transport at the dynamic vadose zone aquifer interface as well as changes to uranium mobility due to incursions of river water into the aquifer.

  6. Review of existing reactive transport software

    SciTech Connect (OSTI)

    Glassley, W., LLNL

    1998-02-03

    Simulations of thermal and hydrological evolution following the potential emplacement of a subterranean nuclear waste repository at Yucca Mountain, NV provide data that suggest the inevitability of dependent, simultaneous chemical evolution in this system. These chemical changes will modify significantly both the magnitude and structure of local porosity and permeability; hence, they will have a dynamic feedback effect on the evolving thermal and hydrological regime. Yet, despite this intimate interdependence of transport and chemical processes, a rigorous quantitative analysis of the post- emplacement environment that incorporates this critical feedback mechanism has not been completed to date. As an initial step in this direction, the present document outlines the fundamental chemical and transport processes that must be accounted for in such an analysis, and reviews the inventory of existing software that encodes these processed in explicitly coupled form. A companion report describes the prioritization of specific capabilities that are needed for modeling post-emplacement reactive transport at Yucca Mountain.

  7. quantifying and Predicting Reactive Transport

    SciTech Connect (OSTI)

    Peter C. Burns, Department of Civil Engineering and Geological Sciences, University of Notre Dame

    2009-12-04

    This project was led by Dr. Jiamin Wan at Lawrence Berkeley National Laboratory. Peter Burns provided expertise in uranium mineralogy and in identification of uranium minerals in test materials. Dr. Wan conducted column tests regarding uranium transport at LBNL, and samples of the resulting columns were sent to Dr. Burns for analysis. Samples were analyzed for uranium mineralogy by X-ray powder diffraction and by scanning electron microscopy, and results were provided to Dr. Wan for inclusion in the modeling effort. Full details of the project can be found in Dr. Wan's final reports for the associated effort at LBNL.

  8. Modeling reactive transport in deformable porous media using the theory of interacting continua.

    SciTech Connect (OSTI)

    Turner, Daniel Zack

    2012-01-01

    This report gives an overview of the work done as part of an Early Career LDRD aimed at modeling flow induced damage of materials involving chemical reactions, deformation of the porous matrix, and complex flow phenomena. The numerical formulation is motivated by a mixture theory or theory of interacting continua type approach to coupling the behavior of the fluid and the porous matrix. Results for the proposed method are presented for several engineering problems of interest including carbon dioxide sequestration, hydraulic fracturing, and energetic materials applications. This work is intended to create a general framework for flow induced damage that can be further developed in each of the particular areas addressed below. The results show both convincing proof of the methodologies potential and the need for further validation of the models developed.

  9. A Uranium Bioremediation Reactive Transport Benchmark

    SciTech Connect (OSTI)

    Yabusaki, Steven B.; Sengor, Sevinc; Fang, Yilin

    2015-06-01

    A reactive transport benchmark problem set has been developed based on in situ uranium bio-immobilization experiments that have been performed at a former uranium mill tailings site in Rifle, Colorado, USA. Acetate-amended groundwater stimulates indigenous microorganisms to catalyze the reduction of U(VI) to a sparingly soluble U(IV) mineral. The interplay between the flow, acetate loading periods and rates, microbially-mediated and geochemical reactions leads to dynamic behavior in metal- and sulfate-reducing bacteria, pH, alkalinity, and reactive mineral surfaces. The benchmark is based on an 8.5 m long one-dimensional model domain with constant saturated flow and uniform porosity. The 159-day simulation introduces acetate and bromide through the upgradient boundary in 14-day and 85-day pulses separated by a 10 day interruption. Acetate loading is tripled during the second pulse, which is followed by a 50 day recovery period. Terminal electron accepting processes for goethite, phyllosilicate Fe(III), U(VI), and sulfate are modeled using Monod-type rate laws. Major ion geochemistry modeled includes mineral reactions, as well as aqueous and surface complexation reactions for UO2++, Fe++, and H+. In addition to the dynamics imparted by the transport of the acetate pulses, U(VI) behavior involves the interplay between bioreduction, which is dependent on acetate availability, and speciation-controlled surface complexation, which is dependent on pH, alkalinity and available surface complexation sites. The general difficulty of this benchmark is the large number of reactions (74), multiple rate law formulations, a multisite uranium surface complexation model, and the strong interdependency and sensitivity of the reaction processes. Results are presented for three simulators: HYDROGEOCHEM, PHT3D, and PHREEQC.

  10. Using reactive transport codes to provide mechanistic biogeochemistry representations in global land surface models: CLM-PFLOTRAN 1.0

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tang, G.; Yuan, F.; Bisht, G.; Hammond, G. E.; Lichtner, P. C.; Kumar, J.; Mills, R. T.; Xu, X.; Andre, B.; Hoffman, F. M.; et al

    2015-12-17

    We explore coupling to a configurable subsurface reactive transport code as a flexible and extensible approach to biogeochemistry in land surface models; our goal is to facilitate testing of alternative models and incorporation of new understanding. A reaction network with the CLM-CN decomposition, nitrification, denitrification, and plant uptake is used as an example. We implement the reactions in the open-source PFLOTRAN code, coupled with the Community Land Model (CLM), and test at Arctic, temperate, and tropical sites. To make the reaction network designed for use in explicit time stepping in CLM compatible with the implicit time stepping used in PFLOTRAN,more » the Monod substrate rate-limiting function with a residual concentration is used to represent the limitation of nitrogen availability on plant uptake and immobilization. To achieve accurate, efficient, and robust numerical solutions, care needs to be taken to use scaling, clipping, or log transformation to avoid negative concentrations during the Newton iterations. With a tight relative update tolerance to avoid false convergence, an accurate solution can be achieved with about 50 % more computing time than CLM in point mode site simulations using either the scaling or clipping methods. The log transformation method takes 60–100 % more computing time than CLM. The computing time increases slightly for clipping and scaling; it increases substantially for log transformation for half saturation decrease from 10−3 to 10−9 mol m−3, which normally results in decreasing nitrogen concentrations. The frequent occurrence of very low concentrations (e.g. below nanomolar) can increase the computing time for clipping or scaling by about 20 %; computing time can be doubled for log transformation. Caution needs to be taken in choosing the appropriate scaling factor because a small value caused by a negative update to a small concentration may diminish the update and result in false convergence even with very

  11. REDUCING UNCERTAINTIES IN MODEL PREDICTIONS VIA HISTORY MATCHING OF CO2 MIGRATION AND REACTIVE TRANSPORT MODELING OF CO2 FATE AT THE SLEIPNER PROJECT

    SciTech Connect (OSTI)

    Zhu, Chen

    2015-03-31

    An important question for the Carbon Capture, Storage, and Utility program is “can we adequately predict the CO2 plume migration?” For tracking CO2 plume development, the Sleipner project in the Norwegian North Sea provides more time-lapse seismic monitoring data than any other sites, but significant uncertainties still exist for some of the reservoir parameters. In Part I, we assessed model uncertainties by applying two multi-phase compositional simulators to the Sleipner Benchmark model for the uppermost layer (Layer 9) of the Utsira Sand and calibrated our model against the time-lapsed seismic monitoring data for the site from 1999 to 2010. Approximate match with the observed plume was achieved by introducing lateral permeability anisotropy, adding CH4 into the CO2 stream, and adjusting the reservoir temperatures. Model-predicted gas saturation, CO2 accumulation thickness, and CO2 solubility in brine—none were used as calibration metrics—were all comparable with the interpretations of the seismic data in the literature. In Part II & III, we evaluated the uncertainties of predicted long-term CO2 fate up to 10,000 years, due to uncertain reaction kinetics. Under four scenarios of the kinetic rate laws, the temporal and spatial evolution of CO2 partitioning into the four trapping mechanisms (hydrodynamic/structural, solubility, residual/capillary, and mineral) was simulated with ToughReact, taking into account the CO2-brine-rock reactions and the multi-phase reactive flow and mass transport. Modeling results show that different rate laws for mineral dissolution and precipitation reactions resulted in different predicted amounts of trapped CO2 by carbonate minerals, with scenarios of the conventional linear rate law for feldspar dissolution having twice as much mineral trapping (21% of the injected CO2) as scenarios with a Burch-type or Alekseyev et al.–type rate law for feldspar dissolution (11%). So far, most reactive transport modeling (RTM) studies for

  12. Addressing numerical challenges in introducing a reactive transport code into a land surface model: a biogeochemical modeling proof-of-concept with CLM–PFLOTRAN 1.0

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tang, Guoping; Yuan, Fengming; Bisht, Gautam; Hammond, Glenn E.; Lichtner, Peter C.; Kumar, Jitendra; Mills, Richard T.; Xu, Xiaofeng; Andre, Ben; Hoffman, Forrest M.; et al

    2016-03-04

    We explore coupling to a configurable subsurface reactive transport code as a flexible and extensible approach to biogeochemistry in land surface models. A reaction network with the Community Land Model carbon–nitrogen (CLM-CN) decomposition, nitrification, denitrification, and plant uptake is used as an example. We implement the reactions in the open-source PFLOTRAN (massively parallel subsurface flow and reactive transport) code and couple it with the CLM. To make the rate formulae designed for use in explicit time stepping in CLMs compatible with the implicit time stepping used in PFLOTRAN, the Monod substrate rate-limiting function with a residual concentration is used to represent the limitation ofmore » nitrogen availability on plant uptake and immobilization. We demonstrate that CLM–PFLOTRAN predictions (without invoking PFLOTRAN transport) are consistent with CLM4.5 for Arctic, temperate, and tropical sites.Switching from explicit to implicit method increases rigor but introduces numerical challenges. Care needs to be taken to use scaling, clipping, or log transformation to avoid negative concentrations during the Newton iterations. With a tight relative update tolerance (STOL) to avoid false convergence, an accurate solution can be achieved with about 50 % more computing time than CLM in point mode site simulations using either the scaling or clipping methods. The log transformation method takes 60–100 % more computing time than CLM. The computing time increases slightly for clipping and scaling; it increases substantially for log transformation for half saturation decrease from 10−3 to 10−9 mol m−3, which normally results in decreasing nitrogen concentrations. The frequent occurrence of very low concentrations (e.g. below nanomolar) can increase the computing time for clipping or scaling by about 20 %, double for log transformation. Overall, the log transformation method is accurate and robust, and the clipping and scaling

  13. Addressing numerical challenges in introducing a reactive transport code into a land surface model: A biogeochemical modeling proof-of-concept with CLM PFLOTRAN 1.0

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tang, Guoping; Yuan, Fengming; Bisht, Gautam; Hammond, Glenn E.; Lichtner, Peter C.; Kumar, Jitendra; Mills, Richard T.; Xu, Xiaofeng; Andre, Ben; Hoffman, Forrest M.; et al

    2016-03-04

    Here, we explore coupling to a configurable subsurface reactive transport code as a flexible and extensible approach to biogeochemistry in land surface models. A reaction network with the Community Land Model carbon nitrogen (CLM-CN) decomposition, nitrification, denitrification, and plant uptake is used as an example. We implement the reactions in the open-source PFLOTRAN (massively parallel subsurface flow and reactive transport) code and couple it with the CLM. To make the rate formulae designed for use in explicit time stepping in CLMs compatible with the implicit time stepping used in PFLOTRAN, the Monod substrate rate-limiting function with a residual concentration ismore » used to represent the limitation of nitrogen availability on plant uptake and immobilization. We demonstrate that CLM PFLOTRAN predictions (without invoking PFLOTRAN transport) are consistent with CLM4.5 for Arctic, temperate, and tropical sites. Switching from explicit to implicit method increases rigor but introduces numerical challenges. Care needs to be taken to use scaling, clipping, or log transformation to avoid negative concentrations during the Newton iterations. With a tight relative update tolerance (STOL) to avoid false convergence, an accurate solution can be achieved with about 50 % more computing time than CLM in point mode site simulations using either the scaling or clipping methods. The log transformation method takes 60–100 % more computing time than CLM. The computing time increases slightly for clipping and scaling; it increases substantially for log transformation for half saturation decrease from 10–3 to 10–9 mol m–3, which normally results in decreasing nitrogen concentrations. The frequent occurrence of very low concentrations (e.g. below nanomolar) can increase the computing time for clipping or scaling by about 20 %, double for log transformation. Overall, the log transformation method is accurate and robust, and the clipping and scaling methods are

  14. Upscaling of Long-Term U9VI) Desorption from Pore Scale Kinetics to Field-Scale Reactive Transport Models

    SciTech Connect (OSTI)

    Andy Miller

    2009-01-25

    Environmental systems exhibit a range of complexities which exist at a range of length and mass scales. Within the realm of radionuclide fate and transport, much work has been focused on understanding pore scale processes where complexity can be reduced to a simplified system. In describing larger scale behavior, the results from these simplified systems must be combined to create a theory of the whole. This process can be quite complex, and lead to models which lack transparency. The underlying assumption of this approach is that complex systems will exhibit complex behavior, requiring a complex system of equations to describe behavior. This assumption has never been tested. The goal of the experiments presented is to ask the question: Do increasingly complex systems show increasingly complex behavior? Three experimental tanks at the intermediate scale (Tank 1: 2.4m x 1.2m x 7.6cm, Tank 2: 2.4m x 0.61m x 7.6cm, Tank 3: 2.4m x 0.61m x 0.61m (LxHxW)) have been completed. These tanks were packed with various physical orientations of different particle sizes of a uranium contaminated sediment from a former uranium mill near Naturita, Colorado. Steady state water flow was induced across the tanks using constant head boundaries. Pore water was removed from within the flow domain through sampling ports/wells; effluent samples were also taken. Each sample was analyzed for a variety of analytes relating to the solubility and transport of uranium. Flow fields were characterized using inert tracers and direct measurements of pressure head. The results show that although there is a wide range of chemical variability within the flow domain of the tank, the effluent uranium behavior is simple enough to be described using a variety of conceptual models. Thus, although there is a wide range in variability caused by pore scale behaviors, these behaviors appear to be smoothed out as uranium is transported through the tank. This smoothing of uranium transport behavior transcends

  15. Fluid-rock interaction: A reactive transport approach

    SciTech Connect (OSTI)

    Steefel, C.; Maher, K.

    2009-04-01

    Fluid-rock interaction (or water-rock interaction, as it was more commonly known) is a subject that has evolved considerably in its scope over the years. Initially its focus was primarily on interactions between subsurface fluids of various temperatures and mostly crystalline rocks, but the scope has broadened now to include fluid interaction with all forms of subsurface materials, whether they are unconsolidated or crystalline ('fluid-solid interaction' is perhaps less euphonious). Disciplines that previously carried their own distinct names, for example, basin diagenesis, early diagenesis, metamorphic petrology, reactive contaminant transport, chemical weathering, are now considered to fall under the broader rubric of fluid-rock interaction, although certainly some of the key research questions differ depending on the environment considered. Beyond the broadening of the environments considered in the study of fluid-rock interaction, the discipline has evolved in perhaps an even more important way. The study of water-rock interaction began by focusing on geochemical interactions in the absence of transport processes, although a few notable exceptions exist (Thompson 1959; Weare et al. 1976). Moreover, these analyses began by adopting a primarily thermodynamic approach, with the implicit or explicit assumption of equilibrium between the fluid and rock. As a result, these early models were fundamentally static rather than dynamic in nature. This all changed with the seminal papers by Helgeson and his co-workers (Helgeson 1968; Helgeson et al. 1969) wherein the concept of an irreversible reaction path was formally introduced into the geochemical literature. In addition to treating the reaction network as a dynamically evolving system, the Helgeson studies introduced an approach that allowed for the consideration of a multicomponent geochemical system, with multiple minerals and species appearing as both reactants and products, at least one of which could be

  16. Using laboratory flow experiments and reactive chemical transport modeling for designing waterflooding of the Agua Fria Reservoir, Poza Rica-Altamira Field, Mexico

    SciTech Connect (OSTI)

    Birkle, P.; Pruess, K.; Xu, T.; Figueroa, R.A. Hernandez; Lopez, M. Diaz; Lopez, E. Contreras

    2008-10-01

    Waterflooding for enhanced oil recovery requires that injected waters must be chemically compatible with connate reservoir waters, in order to avoid mineral dissolution-and-precipitation cycles that could seriously degrade formation permeability and injectivity. Formation plugging is a concern especially in reservoirs with a large content of carbonates, such as calcite and dolomite, as such minerals typically react rapidly with an aqueous phase, and have strongly temperature-dependent solubility. Clay swelling can also pose problems. During a preliminary waterflooding pilot project, the Poza Rica-Altamira oil field, bordering the Gulf coast in the eastern part of Mexico, experienced injectivity loss after five months of reinjection of formation waters into well AF-847 in 1999. Acidizing with HCl restored injectivity. We report on laboratory experiments and reactive chemistry modeling studies that were undertaken in preparation for long-term waterflooding at Agua Frma. Using analogous core plugs obtained from the same reservoir interval, laboratory coreflood experiments were conducted to examine sensitivity of mineral dissolution and precipitation effects to water composition. Native reservoir water, chemically altered waters, and distilled water were used, and temporal changes in core permeability, mineral abundances and aqueous concentrations of solutes were monitored. The experiments were simulated with the multi-phase, nonisothermal reactive transport code TOUGHREACT, and reasonable to good agreement was obtained for changes in solute concentrations. Clay swelling caused an additional impact on permeability behavior during coreflood experiments, whereas the modeled permeability depends exclusively on chemical processes. TOUGHREACT was then used for reservoir-scale simulation of injecting ambient-temperature water (30 C, 86 F) into a reservoir with initial temperature of 80 C (176 F). Untreated native reservoir water was found to cause serious porosity and

  17. System-Scale Model of Aquifer, Vadose Zone, and River Interactions for the Hanford 300 Area - Application to Uranium Reactive Transport

    SciTech Connect (OSTI)

    Rockhold, Mark L.; Bacon, Diana H.; Freedman, Vicky L.; Parker, Kyle R.; Waichler, Scott R.; Williams, Mark D.

    2013-10-01

    This report represents a synthesis and integration of basic and applied research into a system-scale model of the Hanford 300 Area groundwater uranium plume, supported by the U.S. Department of Energy’s Richland Operations (DOE-RL) office. The report integrates research findings and data from DOE Office of Science (DOE-SC), Office of Environmental Management (DOE-EM), and DOE-RL projects, and from the site remediation and closure contractor, Washington Closure Hanford, LLC (WCH). The three-dimensional, system-scale model addresses water flow and reactive transport of uranium for the coupled vadose zone, unconfined aquifer, and Columbia River shoreline of the Hanford 300 Area. The system-scale model of the 300 Area was developed to be a decision-support tool to evaluate processes of the total system affecting the groundwater uranium plume. The model can also be used to address “what if” questions regarding different remediation endpoints, and to assist in design and evaluation of field remediation efforts. For example, the proposed cleanup plan for the Hanford 300 Area includes removal, treatment, and disposal of contaminated sediments from known waste sites, enhanced attenuation of uranium hot spots in the vadose and periodically rewetted zone, and continued monitoring of groundwater with institutional controls. Illustrative simulations of polyphosphate infiltration were performed to demonstrate the ability of the system-scale model to address these types of questions. The use of this model in conjunction with continued field monitoring is expected to provide a rigorous basis for developing operational strategies for field remediation and for defining defensible remediation endpoints.

  18. Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center

    SciTech Connect (OSTI)

    Burgos, W.D.

    2009-09-02

    This report summarizes research conducted in conjunction with a project entitled “Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center”, which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2.

  19. Nonlocal reactive transport with physical and chemical heterogeneity: Localization errors

    SciTech Connect (OSTI)

    Cushman, J.H.; Hu, B.X.; Deng, F.W.

    1995-09-01

    The origin of nonlocality in {open_quotes}macroscale{close_quotes} models for subsurface chemical transport is illustrated. It is argued that media that are either nonperiodic (e.g., media with evolving heterogeneity) or periodic viewed on a scale wherein a unit cell is discernible must display some nonlocality in the mean. A metaphysical argument suggests that owing to the scarcity of information on natural scales of heterogeneity and on scales of observation associated with an instrument window, constitutive theories for the mean concentration should at the outset of any modeling effort always be considered nonlocal. The intuitive appeal to nonlocality is reinforced with an analytical derivation of the constitutive theory for a conservative tracer without appeal to any mathematical approximations. Comparisons are made between the fully nonlocal (FNL), nonlocal in time (NLT), and fully localized (FL) theories. For conservative transport, there is little difference between the first-order FL and FNL models for spatial moments up to and including the third. However, for conservative transport the first-order NLT model differs significantly from the FNL model in the third spatial moments. For reactive transport, all spatial moments differ between the FNL and FL models. The second transverse-horizontal and third longitudinal-horizontal moments for the NLT model differ from the FNL model. These results suggest that localized first-order transport models for conservative tracers are reasonable if only lower-order moments are desired. However, when the chemical reacts with its environment, the localization approximation can lead to significant error in all moments, and a FNL model will in general be required for accurate simulation. 18 refs., 9 figs., 1 tab.

  20. Reactive transport modeling to study changes in water chemistry induced by CO2 injection at the Frio-I brine pilot

    SciTech Connect (OSTI)

    Kharaka, Y.K; Doughty, C.; Freifeld, B.M.; Daley, T.M.; Xu, T.

    2009-11-01

    To demonstrate the potential for geologic storage of CO{sub 2} in saline aquifers, the Frio-I Brine Pilot was conducted, during which 1600 tons of CO{sub 2} were injected into a high-permeability sandstone and the resulting subsurface plume of CO{sub 2} was monitored using a variety of hydrogeological, geophysical, and geochemical techniques. Fluid samples were obtained before CO{sub 2} injection for baseline geochemical characterization, during the CO{sub 2} injection to track its breakthrough at a nearby observation well, and after injection to investigate changes in fluid composition and potential leakage into an overlying zone. Following CO{sub 2} breakthrough at the observation well, brine samples showed sharp drops in pH, pronounced increases in HCO{sub 3}{sup -} and aqueous Fe, and significant shifts in the isotopic compositions of H{sub 2}O and dissolved inorganic carbon. Based on a calibrated 1-D radial flow model, reactive transport modeling was performed for the Frio-I Brine Pilot. A simple kinetic model of Fe release from the solid to aqueous phase was developed, which can reproduce the observed increases in aqueous Fe concentration. Brine samples collected after half a year had lower Fe concentrations due to carbonate precipitation, and this trend can be also captured by our modeling. The paper provides a method for estimating potential mobile Fe inventory, and its bounding concentration in the storage formation from limited observation data. Long-term simulations show that the CO{sub 2} plume gradually spreads outward due to capillary forces, and the gas saturation gradually decreases due to its dissolution and precipitation of carbonates. The gas phase is predicted to disappear after 500 years. Elevated aqueous CO{sub 2} concentrations remain for a longer time, but eventually decrease due to carbonate precipitation. For the Frio-I Brine Pilot, all injected CO{sub 2} could ultimately be sequestered as carbonate minerals.

  1. End-Member Formulation of Solid Solutions and Reactive Transport

    SciTech Connect (OSTI)

    Lichtner, Peter C.

    2015-09-01

    A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed to correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.

  2. Transportation Systems Modeling

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    TRACC RESEARCH Computational Fluid Dynamics Computational Structural Mechanics Transportation Systems Modeling TRANSPORTATION SYSTEMS MODELING Overview of TSM Transportation systems modeling research at TRACC uses the TRANSIMS (Transportation Analysis SIMulation System) traffic micro simulation code developed by the U.S. Department of Transportation (USDOT). The TRANSIMS code represents the latest generation of traffic simulation codes developed jointly under multiyear programs by USDOT, the

  3. Reactive facies: An approach for parameterizing field-scale reactive...

    Office of Scientific and Technical Information (OSTI)

    transport models using geophysical methods Citation Details In-Document Search Title: Reactive facies: An approach for parameterizing field-scale reactive transport models ...

  4. Influence of calcite on uranium(VI) reactive transport in the groundwaterriver mixing zone

    SciTech Connect (OSTI)

    Ma, Rui; Liu, Chongxuan; Greskowiak, Janek; Prommer, Henning; Zachara, John M.; Zheng, Chunmiao

    2014-01-23

    Calcite is an important mineral that can affect uranyl reactive transport in subsurface sediments. This study investigated the distribution of calcite and its influence on uranyl adsorption and reactive transport in the groundwater-river mixing zone at US Hanford 300A, Washington State. Simulations using a 2D reactive transport model under field-relevant hydrogeochemical conditions revealed a complex distribution of calcite concentration as a result of dynamic groundwater-river interactions. The calcite concentration distribution in turn affected the spatial and temporal changes in aqueous carbonate, calcium, and pH, which subsequently influenced U(VI) mobility and discharge rates into the river. The results implied that calcite distribution and its concentration dynamics is an important consideration for field characterization, monitoring, and reactive transport prediction.

  5. Coupling a Reactive Transport Code with a Global Land Surface Model for Mechanistic Biogeochemistry Representation: 1. Addressing the Challenge of Nonnegativity

    SciTech Connect (OSTI)

    Tang, Guoping; Yuan, Fengming; Bisht, Gautam; Hammond, Glenn E.; Lichtner, Peter C.; Collier, Nathaniel O.; Kumar, Jitendra; Mills, Richard T.; Xu, Xiaofeng; Andre, Ben; Hoffman, Forrest M.; Painter, Scott L.; Thornton, Peter E.

    2016-01-01

    Reactive transport codes (e.g., PFLOTRAN) are increasingly used to improve the representation of biogeochemical processes in terrestrial ecosystem models (e.g., the Community Land Model, CLM). As CLM and PFLOTRAN use explicit and implicit time stepping, implementation of CLM biogeochemical reactions in PFLOTRAN can result in negative concentration, which is not physical and can cause numerical instability and errors. The objective of this work is to address the nonnegativity challenge to obtain accurate, efficient, and robust solutions. We illustrate the implementation of a reaction network with the CLM-CN decomposition, nitrification, denitrification, and plant nitrogen uptake reactions and test the implementation at arctic, temperate, and tropical sites. We examine use of scaling back the update during each iteration (SU), log transformation (LT), and downregulating the reaction rate to account for reactant availability limitation to enforce nonnegativity. Both SU and LT guarantee nonnegativity but with implications. When a very small scaling factor occurs due to either consumption or numerical overshoot, and the iterations are deemed converged because of too small an update, SU can introduce excessive numerical error. LT involves multiplication of the Jacobian matrix by the concentration vector, which increases the condition number, decreases the time step size, and increases the computational cost. Neither SU nor SE prevents zero concentration. When the concentration is close to machine precision or 0, a small positive update stops all reactions for SU, and LT can fail due to a singular Jacobian matrix. The consumption rate has to be downregulated such that the solution to the mathematical representation is positive. A first-order rate downregulates consumption and is nonnegative, and adding a residual concentration makes it positive. For zero-order rate or when the reaction rate is not a function of a reactant, representing the availability limitation of each

  6. Coupling a Reactive Transport Code with a Global Land Surface Model for Mechanistic Biogeochemistry Representation: 1. Addressing the Challenge of Nonnegativity

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tang, Guoping; Yuan, Fengming; Bisht, Gautam; Hammond, Glenn E.; Lichtner, Peter C.; Collier, Nathaniel O.; Kumar, Jitendra; Mills, Richard T.; Xu, Xiaofeng; Andre, Ben; et al

    2016-01-01

    Reactive transport codes (e.g., PFLOTRAN) are increasingly used to improve the representation of biogeochemical processes in terrestrial ecosystem models (e.g., the Community Land Model, CLM). As CLM and PFLOTRAN use explicit and implicit time stepping, implementation of CLM biogeochemical reactions in PFLOTRAN can result in negative concentration, which is not physical and can cause numerical instability and errors. The objective of this work is to address the nonnegativity challenge to obtain accurate, efficient, and robust solutions. We illustrate the implementation of a reaction network with the CLM-CN decomposition, nitrification, denitrification, and plant nitrogen uptake reactions and test the implementation atmore » arctic, temperate, and tropical sites. We examine use of scaling back the update during each iteration (SU), log transformation (LT), and downregulating the reaction rate to account for reactant availability limitation to enforce nonnegativity. Both SU and LT guarantee nonnegativity but with implications. When a very small scaling factor occurs due to either consumption or numerical overshoot, and the iterations are deemed converged because of too small an update, SU can introduce excessive numerical error. LT involves multiplication of the Jacobian matrix by the concentration vector, which increases the condition number, decreases the time step size, and increases the computational cost. Neither SU nor SE prevents zero concentration. When the concentration is close to machine precision or 0, a small positive update stops all reactions for SU, and LT can fail due to a singular Jacobian matrix. The consumption rate has to be downregulated such that the solution to the mathematical representation is positive. A first-order rate downregulates consumption and is nonnegative, and adding a residual concentration makes it positive. For zero-order rate or when the reaction rate is not a function of a reactant, representing the availability limitation

  7. Shock Desensitization Experiments and Reactive Flow Modeling...

    Office of Scientific and Technical Information (OSTI)

    Shock Desensitization Experiments and Reactive Flow Modeling on Self-Sustaining LX-17 Detonation Waves Citation Details In-Document Search Title: Shock Desensitization Experiments ...

  8. UZ Colloid Transport Model

    SciTech Connect (OSTI)

    M. McGraw

    2000-04-13

    The UZ Colloid Transport model development plan states that the objective of this Analysis/Model Report (AMR) is to document the development of a model for simulating unsaturated colloid transport. This objective includes the following: (1) use of a process level model to evaluate the potential mechanisms for colloid transport at Yucca Mountain; (2) Provide ranges of parameters for significant colloid transport processes to Performance Assessment (PA) for the unsaturated zone (UZ); (3) Provide a basis for development of an abstracted model for use in PA calculations.

  9. integrated-transportation-models

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    support a wider application of integrated transportation models, especially focusing on travel demand and network ... irrevocable worldwide license in said article to ...

  10. STOMP-ECKEChem: An Engineering Perspective on Reactive Transport in Geologic Media

    SciTech Connect (OSTI)

    White, Mark D.; Fang, Yilin

    2012-04-04

    ECKEChem (Equilibrium, Conservation, Kinetic Equation Chemistry) is a reactive transport module for the STOMP suite of multifluid subsurface flow and transport simulators that was developed from an engineering perspective. STOMP comprises a suite of operational modes that are distinguished by the solved coupled conservation equations with capabilities for a variety of subsurface applications (e.g., environmental remediation and stewardship, geologic sequestration of greenhouse gases, gas hydrate production, and oil shale production). The ECKEChem module was designed to provide integrated reactive transport capabilities across the suite of STOMP simulator operational modes. The initial application for the ECKEChem module was in the simulation of the mineralization reactions that occurred with the injection of supercritical carbon dioxide into deep Columbia River basalt formations, where it was implemented in the STOMP-CO2 simulator. The STOMP-ECKEChem solution approach to modeling reactive transport in multifluid geologic media is founded on an engineering perspective: (1) sequential non-iterative coupling between the flow and reactive transport is sufficient, (2) reactive transport can be modeled by operator splitting with local geochemistry and global transport, (3) geochemistry can be expressed as a system of coupled nonlinear equilibrium, conservation and kinetic equations, (4) a limited number of kinetic equation forms are used in geochemical practice. This chapter describes the conceptual approach to converting a geochemical reaction network into a series of equilibrium, conservation and kinetic equations, the implementation of ECKEChem in STOMP, the numerical solution approach, and a demonstration of the simulator on a complex application involving desorption of uranium from contaminated field-textured sediments.

  11. Comparison of parameter sensitivities between a laboratory and field scale model of uranium transport in a dual domain, distributed-rate reactive system

    SciTech Connect (OSTI)

    Greskowiak, Janek; Prommer, Henning; Liu, Chongxuan; Post, Vincent; Ma, Rui; Zheng, Chunmiao; Zachara, John M.

    2010-09-16

    A laboratory-derived conceptual and numerical model for U(VI) transport at the Hanford 300A site, Washington, USA, was applied to a range of field-scale scenarios of different complexity to systematically evaluate model parameter sensitivities. The model, originally developed from column experiment data, included distributed-rate surface complexation kinetics of U(VI), aqueous speciation, and physical non-equilibrium transport processes. A rigorous parameter sensitivity analysis was carried out with respect to different state variables: concentrations, mass fluxes, total mass and spatial moments of dissolved U(VI) for laboratory systems, and various simulation scenarios that represented the field-scale characteristics at the Hanford 300A site. The field-scenarios accounted for transient groundwater flow and variable geochemical conditions driven by frequent water level changes of the nearby Columbia River. Simulations indicated that the transient conditions significantly affected U(VI) plume migration at the site. The parameter sensitivities were largely similar between the laboratory and field scale systems. Where differences existed, they were shown to result from differing degrees of U(VI) adsorption disequilibrium caused by hydraulic or hydrogeochemical conditions. Adorption disequilibrium was found to differ (i) between short duration peak flow events at the field scale and much longer flow events in the laboratory, (ii) for changing groundwater chemical compositions due to river water intrusion, and (iii) for different sampling locations at the field scale. Parameter sensitivities were also found to vary with respect to the different investigated state variables. An approach is demonstrated that elucidates the most important parameters of a laboratory-scale model that must constrained in both the laboratory and field for meaningful field application.

  12. Modeling of fault reactivation and induced seismicity during...

    Office of Scientific and Technical Information (OSTI)

    Modeling of fault reactivation and induced seismicity during hydraulic fracturing of shale-gas reservoirs Citation Details In-Document Search Title: Modeling of fault reactivation ...

  13. Developing a robust geochemical and reactive transport model to evaluate possible sources of arsenic at the CO[subscript 2] sequestration natural analog site in Chimayo, New Mexico

    SciTech Connect (OSTI)

    Viswanathan, Hari; Dai, Zhenxue; Lopano, Christina; Keating, Elizabeth; Hakala, J. Alexandra; Scheckel, Kirk G.; Zheng, Liange; Gutherie, George D.; Pawar, Rajesh

    2012-10-24

    simulating the drop in As concentration as a function of time in the batch experiments. Based on modeling, kaolinite precipitation is anticipated to occur during the experiment, which allows for additional sorption sites to form with time resulting in the slow decrease in As concentration. This mechanism can be viewed as trace metal 'scavenging' due to sorption caused secondary mineral precipitation. Since deep geologic transport of these trace metals to the shallow subsurface by brine or CO{sub 2} intrusion is critical to assessing environmental impacts, the effective retardation of trace metal transport is an important parameter to estimate and it is dependent on multiple coupled reactions. At the field scale, As mobility is retarded due to the influence of sorption reactions, which can affect environmental performance assessment studies of a sequestration site.

  14. Reactive transport modeling of the enhancement of density-driven CO2 convective mixing in carbonate aquifers and its potential implication on geological carbon sequestration

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Islam, Akand; Sun, Alexander Y.; Yang, Changbing

    2016-04-20

    We study the convection and mixing of CO2 in a brine aquifer, where the spread of dissolved CO2 is enhanced because of geochemical reactions with the host formations (calcite and dolomite), in addition to the extensively studied, buoyancy-driven mixing. The nonlinear convection is investigated under the assumptions of instantaneous chemical equilibrium, and that the dissipation of carbonate rocks solely depends on flow and transport and chemical speciation depends only on the equilibrium thermodynamics of the chemical system. The extent of convection is quantified in term of the CO2 saturation volume of the storage formation. Our results suggest that the densitymore » increase of resident species causes significant enhancement in CO2 dissolution, although no significant porosity and permeability alterations are observed. Furthermore, early saturation of the reservoir can have negative impact on CO2 sequestration.« less

  15. Final Report Coupled In Silico Microbial and Geochemical Reactive Transport Models: Extension to Multi-Organism Communities, Upscaling, and Experimental Validation

    SciTech Connect (OSTI)

    Lovley, Derek R.

    2014-03-05

    The project was highly successful in improving the understanding of physiological and ecological factors controlling the growth and interaction of subsurface microorganisms and in developing better strategies for in silico modeling of the interactions of subsurface microorganisms with other species and their environment.

  16. Chemically Reactive Working Fluids for the Capture and Transport...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Planar Optical Waveguide Coupler Transformers for High-Power Solar Enegy Collection and Transmission Chemically Reactive Working Fluids Low-Cost Light Weigh Thin Film Solar ...

  17. Assessment of Controlling Processes for Field-Scale Uranium Reactive Transport under Highly Transient Flow Conditions

    SciTech Connect (OSTI)

    Ma, Rui; Zheng, Chunmiao; Liu, Chongxuan; Greskowiak, Janek; Prommer, Henning; Zachara, John M.

    2014-02-13

    This paper presents the results of a comprehensive model-based analysis of a uranium tracer test conducted at the U.S Department of Energy Hanford 300 Area (300A) IFRC site. A three-dimensional multi-component reactive transport model was employed to assess the key factors and processes that control the field-scale uranium reactive transport. Taking into consideration of relevant physical and chemical processes, the selected conceptual/numerical model replicates the spatial and temporal variations of the observed U(VI) concentrations reasonably well in spite of the highly complex field conditions. A sensitivity analysis was performed to interrogate the relative importance of various processes and factors for reactive transport of U(VI) at the field-scale. The results indicate that multi-rate U(VI) sorption/desorption, U(VI) surface complexation reactions, and initial U(VI) concentrations were the most important processes and factors controlling U(VI) migration. On the other hand, cation exchange reactions, the choice of the surface complexation model, and dual-domain mass transfer processes, which were previously identified to be important in laboratory experiments, played less important roles under the field-scale experimental condition at the 300A site. However, the model simulations also revealed that the groundwater chemistry was relatively stable during the uranium tracer experiment and therefore presumably not dynamic enough to appropriately assess the effects of ion exchange reaction and the choice of surface complexation models on U(VI) sorption and desorption. Furthermore, it also showed that the field experimental duration (16 days) was not sufficiently long to precisely assess the role of a majority of the sorption sites that were accessed by slow kinetic processes within the dual domain model. The sensitivity analysis revealed the crucial role of the intraborehole flow that occurred within the long-screened monitoring wells and thus significantly

  18. A sequential partly iterative approach for multicomponent reactive transport with CORE2D

    SciTech Connect (OSTI)

    Samper, J.; Xu, T.; Yang, C.

    2008-11-01

    CORE{sup 2D} V4 is a finite element code for modeling partly or fully saturated water flow, heat transport and multicomponent reactive solute transport under both local chemical equilibrium and kinetic conditions. It can handle coupled microbial processes and geochemical reactions such as acid-base, aqueous complexation, redox, mineral dissolution/precipitation, gas dissolution/exsolution, ion exchange, sorption via linear and nonlinear isotherms, sorption via surface complexation. Hydraulic parameters may change due to mineral precipitation/dissolution reactions. Coupled transport and chemical equations are solved by using sequential iterative approaches. A sequential partly-iterative approach (SPIA) is presented which improves the accuracy of the traditional sequential noniterative approach (SNIA) and is more efficient than the general sequential iterative approach (SIA). While SNIA leads to a substantial saving of computing time, it introduces numerical errors which are especially large for cation exchange reactions. SPIA improves the efficiency of SIA because the iteration between transport and chemical equations is only performed in nodes with a large mass transfer between solid and liquid phases. The efficiency and accuracy of SPIA are compared to those of SIA and SNIA using synthetic examples and a case study of reactive transport through the Llobregat Delta aquitard in Spain. SPIA is found to be as accurate as SIA while requiring significantly less CPU time. In addition, SPIA is much more accurate than SNIA with only a minor increase in computing time. A further enhancement of the efficiency of SPIA is achieved by improving the efficiency of the Newton-Raphson method used for solving chemical equations. Such an improvement is obtained by working with increments of log-concentrations and ignoring the terms of the Jacobian matrix containing derivatives of activity coefficients. A proof is given for the symmetry and non-singularity of the Jacobian matrix

  19. Nitrate Biogeochemistry and Reactive Transport in California Groundwater: LDRD Final Report

    SciTech Connect (OSTI)

    Esser, B K; Beller, H; Carle, S; Cey, B; Hudson, G B; Leif, R; LeTain, T; Moody-Bartel, C; Moore, K; McNab, W; Moran, J; Tompson, A

    2006-02-24

    Nitrate is the number one drinking water contaminant in the United States. It is pervasive in surface and groundwater systems,and its principal anthropogenic sources have increased dramatically in the last 50 years. In California alone, one third of the public drinking-water wells has been lost since 1988 and nitrate contamination is the most common reason for abandonment. Effective nitrate management in groundwater is complicated by uncertainties related to multiple point and non-point sources, hydrogeologic complexity, geochemical reactivity, and quantification of denitrification processes. In this paper, we review an integrated experimental and simulation-based framework being developed to study the fate of nitrate in a 25 km-long groundwater subbasin south of San Jose, California, a historically agricultural area now undergoing rapid urbanization with increasing demands for groundwater. The modeling approach is driven by a need to integrate new and archival data that support the hypothesis that nitrate fate and transport at the basin scale is intricately related to hydrostratigraphic complexity, variability of flow paths and groundwater residence times, microbial activity, and multiple geochemical reaction mechanisms. This study synthesizes these disparate and multi-scale data into a three-dimensional and highly resolved reactive transport modeling framework.

  20. Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS)

    SciTech Connect (OSTI)

    Steefel, Carl; Rutqvist, Jonny; Tsang, Chin-Fu; Liu, Hui-Hai; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-08-31

    Geological repositories for disposal of high-level nuclear wastes generally rely on a multi-barrier system to isolate radioactive wastes from the biosphere. The multi-barrier system typically consists of a natural barrier system, including repository host rock and its surrounding subsurface environment, and an engineering barrier system (EBS). EBS represents the man-made, engineered materials placed within a repository, including the waste form, waste canisters, buffer materials, backfill and seals (OECD, 2003). EBS plays a significant role in the containment and long-term retardation of radionuclide release. EBS is involved in complex thermal, hydrogeological, mechanical, chemical and biological processes, such as heat release due to radionuclide decay, multiphase flow (including gas release due to canister corrosion), swelling of buffer materials, radionuclide diffusive transport, waste dissolution and chemical reactions. All these processes are related to each other. An in-depth understanding of these coupled processes is critical for the performance assessment (PA) for EBS and the entire repository. Within the EBS group of Used Fuel Disposition (UFD) Campaign, LBNL is currently focused on (1) thermal-hydraulic-mechanical-chemical (THMC) processes in buffer materials (bentonite) and (2) diffusive transport in EBS associated with clay host rock, with a long-term goal to develop a full understanding of (and needed modeling capabilities to simulate) impacts of coupled processes on radionuclide transport in different components of EBS, as well as the interaction between near-field host rock (e.g., clay) and EBS and how they effect radionuclide release. This final report documents the progress that LBNL has made in its focus areas. Specifically, Section 2 summarizes progress on literature review for THMC processes and reactive-diffusive radionuclide transport in bentonite. The literature review provides a picture of the state-of-the-art of the relevant research areas

  1. Double Shock Experiments and Reactive Flow Modeling of High Pressure...

    Office of Scientific and Technical Information (OSTI)

    Double Shock Experiments and Reactive Flow Modeling of High Pressure LX-17 Detonation Reaction Product States Citation Details In-Document Search Title: Double Shock Experiments ...

  2. Minority Transportation Expenditure Allocation Model

    Energy Science and Technology Software Center (OSTI)

    1993-04-12

    MITRAM (Minority TRansportation expenditure Allocation Model) can project various transportation related attributes of minority (Black and Hispanic) and majority (white) populations. The model projects vehicle ownership, vehicle miles of travel, workers, new car and on-road fleet fuel economy, amount and share of household income spent on gasoline, and household expenditures on public transportation and taxis. MITRAM predicts reactions to sustained fuel price changes for up to 10 years after the change.

  3. Reactive Transport and Coupled THM Processes in Engineering Barrier...

    Office of Scientific and Technical Information (OSTI)

    This may be important for identifying future modeling activities within the EBS group with ... Section 4 presents the results of geomechanical modeling using the Barcelona Basic Model ...

  4. Addressing numerical challenges in introducing a reactive transport code into a land surface model: A biogeochemical modeling proof-of-concept with CLM-PFLOTRAN 1.0: Modeling Archive

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    R. T. Mills; G. Bisht; G. E. Hammond; J. Kumar; P. C. Lichtner; F. M. Hoffman; X. Xu; F. Yuan; S. L. Painter; G. Tang; and P.E. Thornton; B. Andre

    2016-04-19

    This Modeling Archive is in support of an NGEE Arctic discussion paper under review and available at doi:10.5194/gmd-9-927-2016. The purpose is to document the simulations to allow verification, reproducibility, and follow-up studies. This dataset contains shell scripts to create the CLM-PFLOTRAN cases, specific input files for PFLOTRAN and CLM, outputs, and python scripts to make the figures using the outputs in the publication. Through these results, we demonstrate that CLM-PFLOTRAN can approximately reproduce CLM results in selected cases for the Arctic, temperate and tropic sites. In addition, the new framework facilitates mechanistic representations of soil biogeochemistry processes in the land surface model.

  5. Uranium Transport Modeling

    SciTech Connect (OSTI)

    Bostick, William D.

    2008-01-15

    Uranium contamination is prevalent at many of the U.S. DOE facilities and at several civilian sites that have supported the nuclear fuel cycle. The potential off-site mobility of uranium depends on the partitioning of uranium between aqueous and solid (soil and sediment) phases. Hexavalent U (as uranyl, UO{sub 2}{sup 2+}) is relatively mobile, forming strong complexes with ubiquitous carbonate ion which renders it appreciably soluble even under mild reducing conditions. In the presence of carbonate, partition of uranyl to ferri-hydrate and select other mineral phases is usually maximum in the near-neutral pH range {approx} 5-8. The surface complexation reaction of uranyl with iron-containing minerals has been used as one means to model subsurface migration, used in conjunction with information on the site water chemistry and hydrology. Partitioning of uranium is often studied by short-term batch 'equilibrium' or long-term soil column testing ; MCLinc has performed both of these methodologies, with selection of method depending upon the requirements of the client or regulatory authority. Speciation of uranium in soil may be determined directly by instrumental techniques (e.g., x-ray photoelectron spectroscopy, XPS; x-ray diffraction, XRD; etc.) or by inference drawn from operational estimates. Often, the technique of choice for evaluating low-level radionuclide partitioning in soils and sediments is the sequential extraction approach. This methodology applies operationally-defined chemical treatments to selectively dissolve specific classes of macro-scale soil or sediment components. These methods recognize that total soil metal inventory is of limited use in understanding bioavailability or metal mobility, and that it is useful to estimate the amount of metal present in different solid-phase forms. Despite some drawbacks, the sequential extraction method can provide a valuable tool to distinguish among trace element fractions of different solubility related to

  6. Air Transport Optimization Model | NISAC

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    NISACAir Transport Optimization Model content top Network Optimization Models (RNAS and ATOM) Posted by Admin on Mar 1, 2012 in | Comments 0 comments Many critical infrastructures can be represented by a network of interconnected nodes and links. Mathematically sound nonlinear optimization techniques can then be applied to these networks to understand their behavior under normal and disrupted situations. Network optimization models are particularly useful for evaluating transportation system

  7. transportation-system-modeling-webinar

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Webinar Announcement Webinar for the Intelligent Transportation Society of the Midwest (ITS Midwest) May 16, 2011 1:00 PM(CST) Hubert Ley Director, TRACC Argonne National Laboratory Argonne, Illinois High Performance Computing in Transportation Research - High Fidelity Transportation Models and More The Role of High-Performance Computing Because ITS relies on a very diverse collection of technologies, including communication and control technologies, advanced computing, information management

  8. Transport Modeling Working Group Meeting Reports | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Modeling Working Group Meeting Reports Transport Modeling Working Group Meeting Reports View reports from meetings of the Transport Modeling Working Group, which meets twice per ...

  9. Release of aged contaminants from weathered sediments: Effects of sorbate speciation on scaling of reactive transport

    SciTech Connect (OSTI)

    Chorover, Jon; Perdrial, Nico; Mueller, Karl; Strepka, Caleb; O???¢????????Day, Peggy; Rivera, Nelson; Um, Wooyong; Chang, Hyun-Shik; Steefel, Carl; Thompson, Aaron

    2012-11-05

    Hanford sediments impacted by hyperalkaline high level radioactive waste have undergone incongruent silicate mineral weathering concurrent with contaminant uptake. In this project, we studied the impact of background pore water (BPW) on strontium, cesium and iodine desorption and transport in Hanford sediments that were experimentally weathered by contact with simulated hyperalkaline tank waste leachate (STWL) solutions. Using those lab-weathered Hanford sediments (HS) and model precipitates formed during nucleation from homogeneous STWL solutions (HN), we (i) provided thorough characterization of reaction products over a matrix of field-relevant gradients in contaminant concentration, partial pressure of carbon dioxide, and reaction time; (ii) improved molecular-scale understanding of how sorbate speciation controls contaminant desorption from weathered sediments upon removal of caustic sources; and (iii) developed a mechanistic, predictive model of meso- to field-scale contaminant reactive transport under these conditions. In this final report, we provide detailed descriptions of our results from this three-year study, completed in 2012 following a one-year no cost extension.

  10. A Reactive Transport Simulator for Biogeochemical Processes in Subsurface System

    Energy Science and Technology Software Center (OSTI)

    2003-04-01

    BIOGEOCHEM is a Fortran code that mumerically simulates the coupled processes of solute transport, microbial population dynamics, microbial metabolism, and geochemical reactions. The potential applications of the code include, but not limited to, (a) sensitivity and uncertainty analyses for assessing the impact of microbial activity on subsurface geochemical systems; (b) extraction of biogeochemical parameter values from field observations or laboratory measurements, (c) helping to design and optimize laboratory biogeochemical experiments, and (d) data integration. Methodmore » of Solution: A finite difference method and a Newton-Raphson technique are used to solve a set of coupled nonlinear partial differential equations and algebraic equations. Practical Application: Environmental analysis, bioremediation performance assessments of radioactive or non-radioactive wase disposal, and academic research.« less

  11. COMBINED MODELING OF ACCELERATION, TRANSPORT, AND HYDRODYNAMIC...

    Office of Scientific and Technical Information (OSTI)

    Title: COMBINED MODELING OF ACCELERATION, TRANSPORT, AND HYDRODYNAMIC RESPONSE IN SOLAR FLARES. I. THE NUMERICAL MODEL Acceleration and transport of high-energy particles and fluid ...

  12. Reactive transport of uranium in fractured crystalline rock: Upscaling in time and distance

    SciTech Connect (OSTI)

    Dittrich, Timothy M.; Reimus, Paul W.

    2015-09-29

    In this study, batch adsorption and breakthrough column experiments were conducted to evaluate uranium transport through altered material that fills fractures in a granite rock system at the Grimsel Test Site in Switzerland at pH 6.9 and 7.9. The role of adsorption and desorption kinetics was evaluated with reactive transport modeling by comparing one-, two-, and three-site models. Emphasis was placed on describing long desorption tails that are important for upscaling in time and distance. The effect of increasing pH in injection solutions was also evaluated. For pH 6.9, a three-site model with forward rate constants between 0.07 and 0.8 ml g–1 h–1, reverse rate constants between 0.001 and 0.06 h–1, and site densities of 1.3, 0.104, and 0.026 μmol g–1 for ‘weak/fast’, ‘strong/slow’, and ‘very strong/very slow’ sites provided the best fits. For pH 7.9, a three-site model with forward rate constants between 0.05 and 0.8 mL g–1 h–1, reverse rate constants between 0.001 and 0.6 h–1, and site densities of 1.3, 0.039, and 0.013 μmol g–1 for a ‘weak/fast’, ‘strong/slow’, and ‘very strong/very slow’ sites provided the best fits. Column retardation coefficients (Rd) were 80 for pH 6.9 and 10.3 for pH 7.9. Model parameters determined from the batch and column experiments were used in 50 year large-scale simulations for continuous and pulse injections and indicated that a three-site model is necessary at pH 6.9, although a Kd-type equilibrium partition model with one-site was adequate for large scale predictions at pH 7.9. Batch experiments were useful for predicting early breakthrough times in the columns while column experiments helped differentiate the relative importance of sorption sites and desorption rate constants on transport.

  13. Reactive transport of uranium in fractured crystalline rock: Upscaling in time and distance

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dittrich, Timothy M.; Reimus, Paul W.

    2015-09-29

    In this study, batch adsorption and breakthrough column experiments were conducted to evaluate uranium transport through altered material that fills fractures in a granite rock system at the Grimsel Test Site in Switzerland at pH 6.9 and 7.9. The role of adsorption and desorption kinetics was evaluated with reactive transport modeling by comparing one-, two-, and three-site models. Emphasis was placed on describing long desorption tails that are important for upscaling in time and distance. The effect of increasing pH in injection solutions was also evaluated. For pH 6.9, a three-site model with forward rate constants between 0.07 and 0.8more » ml g–1 h–1, reverse rate constants between 0.001 and 0.06 h–1, and site densities of 1.3, 0.104, and 0.026 μmol g–1 for ‘weak/fast’, ‘strong/slow’, and ‘very strong/very slow’ sites provided the best fits. For pH 7.9, a three-site model with forward rate constants between 0.05 and 0.8 mL g–1 h–1, reverse rate constants between 0.001 and 0.6 h–1, and site densities of 1.3, 0.039, and 0.013 μmol g–1 for a ‘weak/fast’, ‘strong/slow’, and ‘very strong/very slow’ sites provided the best fits. Column retardation coefficients (Rd) were 80 for pH 6.9 and 10.3 for pH 7.9. Model parameters determined from the batch and column experiments were used in 50 year large-scale simulations for continuous and pulse injections and indicated that a three-site model is necessary at pH 6.9, although a Kd-type equilibrium partition model with one-site was adequate for large scale predictions at pH 7.9. Batch experiments were useful for predicting early breakthrough times in the columns while column experiments helped differentiate the relative importance of sorption sites and desorption rate constants on transport.« less

  14. transportation-systems-modeling-training

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Training Table of Contents Date Location Integrated Transportation Models Workshop at ITM 2012 April 29, 2012 Hyatt Regency Tampa, FL TRANSIMS Training Course April 14-15, 2011 James E. Clyburn University Transportation Center Orangeburg, SC TRANSIMS RTSTEP Guest Lecturer March 29, 2011 Argonne TRACC Argonne, IL TRANSIMS Training Course January 19-21 2011 Argonne TRACC Argonne, IL TRANSIMS Training Course September 7-8, 2010 Turner Fairbank Highway Research Center Washington D.C. Network

  15. Predictive modeling of reactive wetting and metal joining.

    SciTech Connect (OSTI)

    van Swol, Frank B.

    2013-09-01

    The performance, reproducibility and reliability of metal joints are complex functions of the detailed history of physical processes involved in their creation. Prediction and control of these processes constitutes an intrinsically challenging multi-physics problem involving heating and melting a metal alloy and reactive wetting. Understanding this process requires coupling strong molecularscale chemistry at the interface with microscopic (diffusion) and macroscopic mass transport (flow) inside the liquid followed by subsequent cooling and solidification of the new metal mixture. The final joint displays compositional heterogeneity and its resulting microstructure largely determines the success or failure of the entire component. At present there exists no computational tool at Sandia that can predict the formation and success of a braze joint, as current capabilities lack the ability to capture surface/interface reactions and their effect on interface properties. This situation precludes us from implementing a proactive strategy to deal with joining problems. Here, we describe what is needed to arrive at a predictive modeling and simulation capability for multicomponent metals with complicated phase diagrams for melting and solidification, incorporating dissolutive and composition-dependent wetting.

  16. Final Project Report: Release of aged contaminants from weathered sediments: Effects of sorbate speciation on scaling of reactive transport

    SciTech Connect (OSTI)

    Jon Chorover, University of Arizona; Peggy O'????Day, University of California, Merced; Karl Mueller, Penn State University; Wooyong Um, Pacific Northwest National Laboratory; Carl Steefel, Lawrence Berkeley National Laboratory

    2012-10-01

    Hanford sediments impacted by hyperalkaline high level radioactive waste have undergone incongruent silicate mineral weathering concurrent with contaminant uptake. In this project, we studied the impact of background pore water (BPW) on strontium, cesium and iodine desorption and transport in Hanford sediments that were experimentally weathered by contact with simulated hyperalkaline tank waste leachate (STWL) solutions. Using those lab-weathered Hanford sediments (HS) and model precipitates formed during nucleation from homogeneous STWL solutions (HN), we (i) provided detailed characterization of reaction products over a matrix of field-relevant gradients in contaminant concentration, PCO2, and reaction time; (ii) improved molecular-scale understanding of how sorbate speciation controls contaminant desorption from weathered sediments upon removal of caustic sources; and (iii) developed a mechanistic, predictive model of meso- to field-scale contaminant reactive transport under these conditions.

  17. Semianalytical Solutions of Radioactive or Reactive Tracer Transport in Layered Fractured Media

    SciTech Connect (OSTI)

    G.J. Moridis; G. S. Bodvarsson

    2001-10-01

    In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive tracers (solutes or colloids) through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the matrix account for (a) diffusion, (b) surface diffusion (for solutes only), (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first order chemical reactions. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Additionally, the colloid transport equations account for straining and velocity adjustments related to the colloidal size. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of {sup 3}H, {sup 237}Np and {sup 239}Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity. {sup 239}Pu colloid transport problems in multilayered systems indicate significant colloid accumulations at straining interfaces but much faster transport of the colloid than the corresponding strongly sorbing solute species.

  18. A Computer Program for the Calculation of Reactivity and Kinetic Parameters by Two-Dimensional Neutron Transport Perturbation Theory.

    Energy Science and Technology Software Center (OSTI)

    1985-02-01

    Version 00 TP2 is a transport theory code, developed to determine reactivity effects and kinetic parameters such as effective delayed neutron fractions and mean generation time by applying the usual perturbation formalism for two-dimensional geometry.

  19. A Computer Code System for the Calculation of Reactivity and Kinetic Parameters by One-Dimensional Neutron Transport Perturbation Theory.

    Energy Science and Technology Software Center (OSTI)

    1985-02-01

    Version 00 TP1 is a transport theory code, developed to determine reactivity effects and kinetic parameters such as effective delayed neutron fractions and mean generation time by applying the usual perturbation formalism for one-dimensional geometry.

  20. Model Recovery Procedure for Response to a Radiological Transportation...

    Office of Environmental Management (EM)

    for Response to a Radiological Transportation Incident Model Recovery Procedure for Response to a Radiological Transportation Incident This Transportation Emergency...

  1. A Computer Program for the Reactivity and Kinetic Parameters for Two-Dimensional Triangular Geometry by Transport Perturbation Theory.

    Energy Science and Technology Software Center (OSTI)

    1990-04-25

    Version 00 TPTRIA calculates reactivity, effective delayed neutron fractions and mean generation time for two-dimensional triangular geometry on the basis of neutron transport perturbation theory. DIAMANT2 (also designated as CCC-414), is a multigroup two-dimensional discrete ordinates transport code system for triangular and hexagonal geometry which calculates direct and adjoint angular fluxes.

  2. RADIONUCLIDE TRANSPORT MODELS UNDER AMBIENT CONDITIONS

    SciTech Connect (OSTI)

    S. Magnuson

    2004-11-01

    The purpose of this model report is to document the unsaturated zone (UZ) radionuclide transport model, which evaluates, by means of three-dimensional numerical models, the transport of radioactive solutes and colloids in the UZ, under ambient conditions, from the repository horizon to the water table at Yucca Mountain, Nevada.

  3. New NIR Calibration Models Speed Biomass Composition and Reactivity Characterization

    SciTech Connect (OSTI)

    2015-09-01

    Obtaining accurate chemical composition and reactivity (measures of carbohydrate release and yield) information for biomass feedstocks in a timely manner is necessary for the commercialization of biofuels. This highlight describes NREL's work to use near-infrared (NIR) spectroscopy and partial least squares multivariate analysis to develop calibration models to predict the feedstock composition and the release and yield of soluble carbohydrates generated by a bench-scale dilute acid pretreatment and enzymatic hydrolysis assay. This highlight is being developed for the September 2015 Alliance S&T Board meeting.

  4. Technical Basis for Peak Reactivity Burnup Credit for BWR Spent Nuclear Fuel in Storage and Transportation Systems

    SciTech Connect (OSTI)

    Marshall, William BJ J; Ade, Brian J; Bowman, Stephen M; Gauld, Ian C; Ilas, Germina; Mertyurek, Ugur; Radulescu, Georgeta

    2015-01-01

    Oak Ridge National Laboratory and the United States Nuclear Regulatory Commission have initiated a multiyear project to investigate application of burnup credit for boiling-water reactor (BWR) fuel in storage and transportation casks. This project includes two phases. The first phase (1) investigates applicability of peak reactivity methods currently used in spent fuel pools (SFPs) to storage and transportation systems and (2) evaluates validation of both reactivity (keff) calculations and burnup credit nuclide concentrations within these methods. The second phase will focus on extending burnup credit beyond peak reactivity. This paper documents the first phase, including an analysis of lattice design parameters and depletion effects, as well as both validation components. Initial efforts related to extended burnup credit are discussed in a companion paper. Peak reactivity analyses have been used in criticality analyses for licensing of BWR fuel in SFPs over the last 20 years. These analyses typically combine credit for the gadolinium burnable absorber present in the fuel with a modest amount of burnup credit. Gadolinium burnable absorbers are used in BWR assemblies to control core reactivity. The burnable absorber significantly reduces assembly reactivity at beginning of life, potentially leading to significant increases in assembly reactivity for burnups less than 15–20 GWd/MTU. The reactivity of each fuel lattice is dependent on gadolinium loading. The number of gadolinium-bearing fuel pins lowers initial lattice reactivity, but it has a small impact on the burnup and reactivity of the peak. The gadolinium concentration in each pin has a small impact on initial lattice reactivity but a significant effect on the reactivity of the peak and the burnup at which the peak occurs. The importance of the lattice parameters and depletion conditions are primarily determined by their impact on the gadolinium depletion. Criticality code validation for BWR burnup

  5. Air pollution transport modeling. Master's thesis

    SciTech Connect (OSTI)

    Paal, D.M.

    1993-12-01

    This research effort addresses modeling of the transportation of air pollution in the atmosphere and the numerical analysis of the partial differential equations used in such modeling. Three Gaussian models are examined and compared using example problems. Several finite difference schemes are developed to solve the partial differential equations used in air pollution transport modeling. This study examines three Gaussian models: SCREEN, AFTOX, and the program GAUSPLUM. The model GAUSPLUM is developed in this study and uses the Ada programming language and the analytic solution to the advection-diffusion equation. Numerical analysis of the partial differential equations (PDE) used in air pollution modeling is also examined. The equations are generally parabolic or hyperbolic PDE's. The following are examined in this research: the advection equation; the one-, two-, and three-dimensional advection-diffusion equations; and the two-dimensional steady-state equation. Air Pollution Transport, Modeling, Finite Difference Scheme, Stability, Consistency, Convergence, Advection-Diffusion Equations.

  6. Developing a robust geochemical and reactive transport model...

    Office of Scientific and Technical Information (OSTI)

    Migration of carbon dioxide (COsub 2) from deep storage formations into shallow drinking ... LEAKS; LEVELS; MATERIALS; METALS; MIGRATION; MINERALS; MOBILITY; OXIDES; ...

  7. Modeling of coupled heat transfer and reactive transport processesin...

    Office of Scientific and Technical Information (OSTI)

    heating and boiling, and through local convection. In cooler regions, the vapor condenses on fracture walls, where it drains through the fracture network. Slow imbibition of water ...

  8. Modeling of coupled heat transfer and reactive transport processesin...

    Office of Scientific and Technical Information (OSTI)

    Subsequently, vapor migrates out of the matrix pore space, moving away from the tunnel through the permeable fracture network. This migration is propelled by buoyancy, by the ...

  9. Vertical transport and sources in flux models

    SciTech Connect (OSTI)

    Canavan, G.H.

    1997-01-01

    Vertical transport in flux models in examined and shown to reproduce expected limits for densities and fluxes. Disparities with catalog distributions are derived and inverted to find the sources required to rectify them.

  10. The Transportation Sector Model of the National Energy Modeling...

    Gasoline and Diesel Fuel Update (EIA)

    Information Administration NEMS Transportation Demand Model Documentation Report 2005 25 manufacturing, and design advances. Manufacturing advances can generally be thought of as...

  11. Pore-scale simulation of coupled reactive transport and dissolution in fractures and porous media using the level set interface tracking method

    SciTech Connect (OSTI)

    Hai Huang; Xiaoyi Li

    2011-01-01

    A level set simulation methodology developed for modeling coupled reactive transport and structure evolution has been applied to dissolution in fracture apertures and porous media. The coupled processes such as fluid flow, reactant transport and dissolution at the solid-liquid interfaces are handled simultaneously. The reaction-induced evolution of solid-liquid interfaces is captured using the level set method, with the advantage of representing the interface with sub-grid scale resolution. The coupled processes are simulated for several geometric models of fractures and porous media under various flow conditions and reaction rates. Quantitative relationships between permeability and porosity are obtained from some of the simulation results and compared with analytical constitutive relations (i.e., the conventional cubic law and the Carman-Kozeny law) based on simplified pore space geometries and reaction induced geometric evolutions. The drastic deviation of the simulation results from these analytical theories is explained by the development of large local concentration gradients of reactants within fracture apertures and individual pores observed in the simulation results and consequently the complex geometric evolution patterns of fracture apertures and pores due to mineral dissolution. The simulation results support the argument that traditional constitutive relations based on simplified geometries and conditions have limited applicability in predicting field scale reactive transport and that incorporation of micro-scale physics is necessary.

  12. Reactive sputter deposition of pyrite structure transition metal disulfide thin films: Microstructure, transport, and magnetism

    SciTech Connect (OSTI)

    Baruth, A.; Manno, M.; Narasimhan, D.; Shankar, A.; Zhang, X.; Johnson, M.; Aydil, E. S.; Leighton, C. [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2012-09-01

    Transition metal disulfides crystallizing in the pyrite structure (e.g., TMS{sub 2}, with TM = Fe, Co, Ni, and Cu) are a class of materials that display a remarkably diverse array of functional properties. These properties include highly spin-polarized ferromagnetism (in Co{sub 1-x}Fe{sub x}S{sub 2}), superconductivity (in CuS{sub 2}), an antiferromagnetic Mott insulating ground state (in NiS{sub 2}), and semiconduction with close to optimal parameters for solar absorber applications (in FeS{sub 2}). Exploitation of these properties in heterostructured devices requires the development of reliable and reproducible methods for the deposition of high quality pyrite structure thin films. In this manuscript, we report on the suitability of reactive sputter deposition from metallic targets in an Ar/H{sub 2}S environment as a method to achieve exactly this. Optimization of deposition temperature, Ar/H{sub 2}S pressure ratio, and total working gas pressure, assisted by plasma optical emission spectroscopy, reveals significant windows over which deposition of single-phase, polycrystalline, low roughness pyrite films can be achieved. This is illustrated for the test cases of the ferromagnetic metal CoS{sub 2} and the diamagnetic semiconductor FeS{sub 2}, for which detailed magnetic and transport characterization are provided. The results indicate significant improvements over alternative deposition techniques such as ex situ sulfidation of metal films, opening up exciting possibilities for all-sulfide heterostructured devices. In particular, in the FeS{sub 2} case it is suggested that fine-tuning of the sputtering conditions provides a potential means to manipulate doping levels and conduction mechanisms, critical issues in solar cell applications. Parenthetically, we note that conditions for synthesis of phase-pure monosulfides and thiospinels are also identified.

  13. World Energy Projection System Plus Model Documentation: Transportation Model

    Reports and Publications (EIA)

    2011-01-01

    This report documents the objectives, analytical approach and development of the World Energy Projection System Plus (WEPS ) International Transportation model. It also catalogues and describes critical assumptions, computational methodology, parameter estimation techniques, and model source code.

  14. Radionuclide Transport Models Under Ambient Conditions

    SciTech Connect (OSTI)

    G. Moridis; Q. Hu

    2001-12-20

    The purpose of Revision 00 of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada.

  15. Radionuclide Transport Models Under Ambient Conditions

    SciTech Connect (OSTI)

    G. Moridis; Q. Hu

    2000-03-12

    The purpose of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada. This is in accordance with the ''AMR Development Plan U0060, Radionuclide Transport Models Under Ambient Conditions'' (CRWMS M and O 1999a). This AMR supports the UZ Flow and Transport Process Model Report (PMR). This AMR documents the UZ Radionuclide Transport Model (RTM). This model considers: the transport of radionuclides through fractured tuffs; the effects of changes in the intensity and configuration of fracturing from hydrogeologic unit to unit; colloid transport; physical and retardation processes and the effects of perched water. In this AMR they document the capabilities of the UZ RTM, which can describe flow (saturated and/or unsaturated) and transport, and accounts for (a) advection, (b) molecular diffusion, (c) hydrodynamic dispersion (with full 3-D tensorial representation), (d) kinetic or equilibrium physical and/or chemical sorption (linear, Langmuir, Freundlich or combined), (e) first-order linear chemical reaction, (f) radioactive decay and tracking of daughters, (g) colloid filtration (equilibrium, kinetic or combined), and (h) colloid-assisted solute transport. Simulations of transport of radioactive solutes and colloids (incorporating the processes described above) from the repository horizon to the water table are performed to support model development and support studies for Performance Assessment (PA). The input files for these simulations include transport parameters obtained from other AMRs (i.e., CRWMS M and O 1999d, e, f, g, h; 2000a, b, c, d). When not available, the parameter values used are obtained from the literature. The results of the simulations are used to evaluate the transport of radioactive solutes and colloids, and

  16. PFLOTRAN User Manual: A Massively Parallel Reactive Flow and...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: PFLOTRAN User Manual: A Massively Parallel Reactive Flow and Transport Model for Describing Surface and Subsurface Processes Citation Details In-Document Search...

  17. PFLOTRAN User Manual: A Massively Parallel Reactive Flow and...

    Office of Scientific and Technical Information (OSTI)

    PFLOTRAN User Manual: A Massively Parallel Reactive Flow and Transport Model for Describing Surface and Subsurface Processes Lichtner, Peter OFM Research; Karra, Satish Los...

  18. Current Transportation Models Used in the Vehicle Technologies Program

    SciTech Connect (OSTI)

    2009-04-06

    A summary of various transportation models (VISION, TRUCK, GREET, Oil Peaking Model, Feebate Model, Oil Security Metrics Model, ORNL PHEV Choice Model: Version 1, PSAT, PSAT-PRO,

  19. Performance Assessment Transport Modeling of Uranium at the Area 5 Radioactive Waste Management Site at the Nevada National Security Site

    SciTech Connect (OSTI)

    NSTec Radioactive Waste

    2010-10-12

    Following is a brief summary of the assumptions that are pertinent to the radioactive isotope transport in the GoldSim Performance Assessment model of the Area 5 Radioactive Waste Management Site, with special emphasis on the water-phase reactive transport of uranium, which includes depleted uranium products.

  20. A Many-Task Parallel Approach for Multiscale Simulations of Subsurface Flow and Reactive Transport

    SciTech Connect (OSTI)

    Scheibe, Timothy D.; Yang, Xiaofan; Schuchardt, Karen L.; Agarwal, Khushbu; Chase, Jared M.; Palmer, Bruce J.; Tartakovsky, Alexandre M.

    2014-12-16

    Continuum-scale models have long been used to study subsurface flow, transport, and reactions but lack the ability to resolve processes that are governed by pore-scale mixing. Recently, pore-scale models, which explicitly resolve individual pores and soil grains, have been developed to more accurately model pore-scale phenomena, particularly reaction processes that are controlled by local mixing. However, pore-scale models are prohibitively expensive for modeling application-scale domains. This motivates the use of a hybrid multiscale approach in which continuum- and pore-scale codes are coupled either hierarchically or concurrently within an overall simulation domain (time and space). This approach is naturally suited to an adaptive, loosely-coupled many-task methodology with three potential levels of concurrency. Each individual code (pore- and continuum-scale) can be implemented in parallel; multiple semi-independent instances of the pore-scale code are required at each time step providing a second level of concurrency; and Monte Carlo simulations of the overall system to represent uncertainty in material property distributions provide a third level of concurrency. We have developed a hybrid multiscale model of a mixing-controlled reaction in a porous medium wherein the reaction occurs only over a limited portion of the domain. Loose, minimally-invasive coupling of pre-existing parallel continuum- and pore-scale codes has been accomplished by an adaptive script-based workflow implemented in the Swift workflow system. We describe here the methods used to create the model system, adaptively control multiple coupled instances of pore- and continuum-scale simulations, and maximize the scalability of the overall system. We present results of numerical experiments conducted on NERSC supercomputing systems; our results demonstrate that loose many-task coupling provides a scalable solution for multiscale subsurface simulations with minimal overhead.

  1. Climate Impact of Transportation A Model Comparison

    SciTech Connect (OSTI)

    Girod, Bastien; Van Vuuren, Detlef; Grahn, Maria; Kitous, Alban; Kim, Son H.; Kyle, G. Page

    2013-06-01

    Transportation contributes to a significant and rising share of global energy use and GHG emissions. Therefore modeling future travel demand, its fuel use, and resulting CO2 emission is highly relevant for climate change mitigation. In this study we compare the baseline projections for global service demand (passenger-kilometers, ton-kilometers), fuel use, and CO2 emissions of five different global transport models using harmonized input assumptions on income and population. For four models we also evaluate the impact of a carbon tax. All models project a steep increase in service demand over the century. Technology is important for limiting energy consumption and CO2 emissions, but quite radical changes in the technology mix are required to stabilize or reverse the trend. While all models project liquid fossil fuels dominating up to 2050, they differ regarding the use of alternative fuels (natural gas, hydrogen, biofuels, and electricity), because of different fuel price projections. The carbon tax of US$200/tCO2 in 2050 stabilizes or reverses global emission growth in all models. Besides common findings many differences in the model assumptions and projections indicate room for improvement in modeling and empirical description of the transport system.

  2. Model for assessing bronchial mucus transport

    SciTech Connect (OSTI)

    Agnew, J.E.; Bateman, J.R.M.; Pavia, D.; Clarke, S.W.

    1984-02-01

    The authors propose a scheme for the assessment of regional mucus transport using inhaled Tc-99m aerosol particles and quantitative analysis of serial gamma-camera images. The model treats input to inner and intermediate lung regions as the total of initial deposition there plus subsequent transport into these regions from more peripheral airways. It allows for interregional differences in the proportion of particles deposited on the mucus-bearing conducting airways, and does not require a gamma image 24 hr after particle inhalation. Instead, distribution of particles reaching the respiratory bronchioles or alveoli is determined from a Kr-81m ventilation image, while the total amount of such deposition is obtained from 24-hr Tc-99m retention measured with a sensitive counter system. The model is applicable to transport by mucociliary action or by cough, and has been tested in ten normal and ten asthmatic subjects.

  3. Modeling heat conduction and radiation transport with the diffusion...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    heat conduction and radiation transport with the diffusion equation in NIF ALE-AMR This ... IOPscience Modeling Heat Conduction and Radiation Transport with the Diffusion Equation in ...

  4. Model Recovery Procedure for Response to a Radiological Transportation Incident

    Broader source: Energy.gov [DOE]

    This Transportation Emergency Preparedness Program (TEPP) Model Recovery Procedure contains the recommended elements for developing and conducting recovery planning at transportation incident scene...

  5. Fire and materials modeling for transportation systems

    SciTech Connect (OSTI)

    Skocypec, R.D.; Gritzo, L.A.; Moya, J.L.; Nicolette, V.F.; Tieszen, S.R.; Thomas, R.

    1994-10-01

    Fire is an important threat to the safety of transportation systems. Therefore, understanding the effects of fire (and its interaction with materials) on transportation systems is crucial to quantifying and mitigating the impact of fire on the safety of those systems. Research and development directed toward improving the fire safety of transportation systems must address a broad range of phenomena and technologies, including: crash dynamics, fuel dispersion, fire environment characterization, material characterization, and system/cargo thermal response modeling. In addition, if the goal of the work is an assessment and/or reduction of risk due to fires, probabilistic risk assessment technology is also required. The research currently underway at Sandia National Laboratories in each of these areas is summarized in this paper.

  6. Final Scientific/Technical Report – DE-FG02-06ER64172 – Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center – Subproject to Co-PI Eric E. Roden

    SciTech Connect (OSTI)

    Eric E. Roden

    2009-03-17

    This report summarizes research conducted in conjunction with a project entitled “Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center”, which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2. Area 2 is a shallow pathway for migration of contaminated groundwater to seeps in the upper reach of Bear Creek at ORNL, mainly through a ca. 1 m thick layer of gravel located 4-5 m below the ground surface. The gravel layer is sandwiched between an overlying layer of disturbed fill material, and 2-3 m of undisturbed shale saprolite derived from the underlying Nolichucky Shale bedrock. The fill was put in place when contaminated soils were excavated and replaced by native saprolite from an uncontaminated area within Bear Creek Valley; the gravel layer was presumably installed prior to addition of the fill in order to provide a stable surface for the operation of heavy machinery. The undisturbed saprolite is highly weathered bedrock that has unconsolidated character but retains much of the bedding and fracture structure of the parent rock (shale with interbedded limestone). Hydrological tracer studies conducted during the Scheibe et al. field

  7. Modeling uranium transport in acidic contaminated groundwater with base addition

    SciTech Connect (OSTI)

    Zhang, Fan; Luo, Wensui; Parker, Jack C.; Brooks, Scott C; Watson, David B; Jardine, Philip; Gu, Baohua

    2011-01-01

    This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO{sub 3}{sup -}, SO{sub 4}{sup 2-}, U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.

  8. ENVIRONMENTAL REACTIVITY OF SOLID STATE HYDRIDE MATERIALS: MODELING AND TESTING FOR AIR AND WATER EXPOSURE

    SciTech Connect (OSTI)

    Anton, D.; James, C.; Cortes-Concepcion, J.; Tamburello, D.; Brinkman, K.; Gray, J.

    2010-05-18

    To make commercially acceptable condensed phase hydrogen storage systems, it is important to understand quantitatively the risks involved in using these materials. A rigorous set of environmental reactivity tests have been developed based on modified testing procedures codified by the United Nations for the transportation of dangerous goods. Potential hydrogen storage material, 2LiBH4{center_dot}MgH2 and NH3BH3, have been tested using these modified procedures to evaluate the relative risks of these materials coming in contact with the environment in hypothetical accident scenarios. It is apparent that an ignition event will only occur if both a flammable concentration of hydrogen and sufficient thermal energy were available to ignite the hydrogen gas mixture. In order to predict hydride behavior for hypothesized accident scenarios, an idealized finite element model was developed for dispersed hydride from a breached system. Empirical thermodynamic calculations based on precise calorimetric experiments were performed in order to quantify the energy and hydrogen release rates and to quantify the reaction products resulting from water and air exposure. Both thermal and compositional predictions were made with identification of potential ignition event scenarios.

  9. Modelling of multi-ion-beam reactive cosputtering for metal oxide thin films

    SciTech Connect (OSTI)

    Xiao, D.Q.; Zhu, J.G.; Qian, Z.H.; Peng, W.B.; Wei, L.F.; Li, Z.S.

    1995-12-31

    Very recently a new technique named multi-ion-beam reactive cosputtering (MIBRECS) was developed for preparing multi-component metal oxide thin films. Epitaxial or highly oriented (Pb, La) TiO{sub 3} thin films sputtered from pure metals of lead, titanium and lathanium were deposited by using this technique. In order to consummate the technique and to study the mechanism of reactive cosputtering, a general model of multi-ion-beam reactive cosputtering was proposed for the first time based on the well-known gas kinetics under stable sputtering circumstances, and a computer numerical simulation of the model was carried out with the parameters adopted in the experiments. The relationships among the sputtering ratios of the targets, and the coverage ratios of simple substances and oxides of the target metals on substrate surface with the total reactive gas flux and the densities of the sputtering ion beam were obtained respectively, and the hysteresis effect of the characteristic of reactive sputtering and the interactions during multi-ion-beam reactive cosputtering processes were also obtained. The numerical simulation results are at least qualitatively in agreement with the experiments.

  10. Documentation of TRU biological transport model (BIOTRAN)

    SciTech Connect (OSTI)

    Gallegos, A.F.; Garcia, B.J.; Sutton, C.M.

    1980-01-01

    Inclusive of Appendices, this document describes the purpose, rationale, construction, and operation of a biological transport model (BIOTRAN). This model is used to predict the flow of transuranic elements (TRU) through specified plant and animal environments using biomass as a vector. The appendices are: (A) Flows of moisture, biomass, and TRU; (B) Intermediate variables affecting flows; (C) Mnemonic equivalents (code) for variables; (D) Variable library (code); (E) BIOTRAN code (Fortran); (F) Plants simulated; (G) BIOTRAN code documentation; (H) Operating instructions for BIOTRAN code. The main text is presented with a specific format which uses a minimum of space, yet is adequate for tracking most relationships from their first appearance to their formulation in the code. Because relationships are treated individually in this manner, and rely heavily on Appendix material for understanding, it is advised that the reader familiarize himself with these materials before proceeding with the main text.

  11. Neutral gas transport modeling with DEGAS 2

    SciTech Connect (OSTI)

    Stotler, D.; Karney, C.

    1993-10-01

    We are currently rewriting the neutral gas transport code, DEGAS with a view to not only making it faster, but also easing the process of including new physics. The goal is to make adding new species and reactions relatively simple so that the code can be rapidly adapted to new divertor physics regimes. DEGAS 2 will also be optimized for coupling to fluid plasma codes, incorporating many of the techniques utilized in B2-EIRENE. Finally, it is our intention that DEGAS 2, like DEGAS, be well-documented and easy to use. We ill present model calculations including ionization and charge exchange which will illustrate the way reactions are included into DEGAS 2 and will demonstrate operation of the code on a distributed network of workstations.

  12. Diffusion Dominant Solute Transport Modelling in Fractured Media Under Deep Geological Environment - 12211

    SciTech Connect (OSTI)

    Kwong, S.; Jivkov, A.P.

    2012-07-01

    Deep geologic disposal of high activity and long-lived radioactive waste is gaining increasing support in many countries, where suitable low permeability geological formation in combination with engineered barriers are used to provide long term waste contaminant and minimise the impacts to the environment and risk to the biosphere. This modelling study examines the solute transport in fractured media under low flow velocities that are relevant to a deep geological environment. In particular, reactive solute transport through fractured media is studied using a 2-D model, that considers advection and diffusion, to explore the coupled effects of kinetic and equilibrium chemical processes. The effects of water velocity in the fracture, matrix porosity and diffusion on solute transport are investigated and discussed. Some illustrative modelled results are presented to demonstrate the use of the model to examine the effects of media degradation on solute transport, under the influences of hydrogeological (diffusion dominant) and microbially mediated chemical processes. The challenges facing the prediction of long term degradation such as cracks evolution, interaction and coalescence are highlighted. The potential of a novel microstructure informed modelling approach to account for these effects is discussed, particularly with respect to investigating multiple phenomena impact on material performance. The GRM code is used to examine the effects of media degradation for a geological waste disposal package, under the combined hydrogeological (diffusion dominant) and chemical effects in low groundwater flow conditions that are typical of deep geological disposal systems. An illustrative reactive transport modelling application demonstrates the use of the code to examine the interplay of kinetic controlled biogeochemical reactive processes with advective and diffusive transport, under the influence of media degradation. The initial model results are encouraging which show the

  13. On Numerical Considerations for Modeling Reactive Astrophysical Shocks

    SciTech Connect (OSTI)

    Papatheodore, Thomas L; Messer, Bronson

    2014-01-01

    Simulating detonations in astrophysical environments is often complicated by numerical approximations to shock structure. A common prescription to ensure correct detonation speeds (and associated quantities) is to prohibit burning inside the numerically broadened shock (Fryxell et al. 1989). We have performed a series of simulations to verify the efficacy of this approximation and to understand how resolution and dimensionality might affect its use. Our results show that, in one dimension, prohibiting burning in the shock is important wherever the carbon burning length is not resolved, in keeping with the results of Fryxell et al. (1989). In two dimensions, we find that the prohibition of shock burning effectively inhibits the development of cellular structure for all but the most highly-resolved cases. We discuss the possible impacts this outcome may have on sub-grid models and detonation propagation in Type Ia supernovae.

  14. An Updated Site Scale Saturated Zone Ground Water Transport Model...

    Office of Scientific and Technical Information (OSTI)

    An Updated Site Scale Saturated Zone Ground Water Transport Model for Yucca Mountain. Citation Details In-Document Search Title: An Updated Site Scale Saturated Zone Ground Water ...

  15. STOMP Subsurface Transport Over Multiple Phases Version 1.0 Addendum: ECKEChem Equilibrium-Conservation-Kinetic Equation Chemistry and Reactive Transport

    SciTech Connect (OSTI)

    White, Mark D.; McGrail, B. Peter

    2005-12-01

    flow and transport simulator, STOMP (Subsurface Transport Over Multiple Phases). Prior to these code development activities, the STOMP simulator included sequential and scalable implementations for numerically simulating the injection of supercritical CO2 into deep saline aquifers. Additionally, the sequential implementations included operational modes that considered nonisothermal conditions and kinetic dissolution of CO2 into the saline aqueous phase. This addendum documents the advancement of these numerical simulation capabilities to include reactive transport in the STOMP simulator through the inclusion of the recently PNNL developed batch geochemistry solution module ECKEChem (Equilibrium-Conservation-Kinetic Equation Chemistry). Potential geologic reservoirs for sequestering CO2 include deep saline aquifers, hydrate-bearing formations, depleted or partially depleted natural gas and petroleum reservoirs, and coal beds. The mechanisms for sequestering carbon dioxide in geologic reservoirs include physical trapping, dissolution in the reservoir fluids, hydraulic trapping (hysteretic entrapment of nonwetting fluids), and chemical reaction. This document and the associated code development and verification work are concerned with the chemistry of injecting CO2 into geologic reservoirs. As geologic sequestration of CO2 via chemical reaction, namely precipitation reactions, are most dominate in deep saline aquifers, the principal focus of this document is the numerical simulation of CO2 injection, migration, and geochemical reaction in deep saline aquifers. The ECKEChem batch chemistry module was developed in a fashion that would allow its implementation into all operational modes of the STOMP simulator, making it a more versatile chemistry component. Additionally, this approach allows for verification of the ECKEChem module against more classical reactive transport problems involving aqueous systems.

  16. Transport Modeling Working Group | Department of Energy

    Energy Savers [EERE]

    for and understanding of transport phenomena in polymer electrolyte fuel cell stacks. ... to the efficient and cost-effective operation of polymer electrolyte fuel cells. ...

  17. Understanding the Subsurface Reactive Transport of Transuranic Contaminants at DOE Sites

    SciTech Connect (OSTI)

    Barnett, Mark O.; Albrecht-Schmitt, Thomas E.; Saiers, James E.; Shuh, David K.

    2013-12-20

    Our primary hypothesis is that actinides can interact with surfaces in fundamentally different ways than other metals, metalloids, and oxyanions and that this fundamental difference requires new approaches to studying and modeling transuranic sorption to minerals and geomedia. This project supports a key mission of the SBR program to develop sufficient scientific understanding such that DOE sites will be able to incorporate coupled physical, chemical, and biological processes into decision making for environmental management and long-term stewardship, while also supporting DOE’s commitment to education, training, and collaboration with DOE user facilities.

  18. AEO2017 Modeling updates in the transportation sector

    U.S. Energy Information Administration (EIA) Indexed Site

    7 For AEO2017 Transportation Working Group August 31, 2016 | Washington, DC By Melissa Lynes, John Maples, Mark Schipper, and David Stone Office of Energy Consumption and Efficiency Analysis Modeling updates in the transportation sector Updates to the Annual Energy Outlook 2017 * Transportation demand model highlights - 10-year extension of last-year projection, AEO2016 is 2040 and AEO2017 is 2050 - Battery costs for electric vehicles - Phase 2 greenhouse gas and fuel efficiency standards for

  19. Transportation and Vehicle Energy Modeling | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Transportation and Vehicle Energy Modeling Transportation and Vehicle Energy Modeling For the past 15 years, Argonne has been at the forefront of research in energy-efficient transportation. In recent years, the vehicle technologies have become increasingly complex with the introduction of new powertrain configurations (such as electrified vehicles), new component technologies (such as advanced transmissions and engines) and control strategies (such eco-routing). In addition, with increased

  20. A quantum energy transport model for semiconductor device simulation

    SciTech Connect (OSTI)

    Sho, Shohiro; Odanaka, Shinji

    2013-02-15

    This paper describes numerical methods for a quantum energy transport (QET) model in semiconductors, which is derived by using a diffusion scaling in the quantum hydrodynamic (QHD) model. We newly drive a four-moments QET model similar with a classical ET model. Space discretization is performed by a new set of unknown variables. Numerical stability and convergence are obtained by developing numerical schemes and an iterative solution method with a relaxation method. Numerical simulations of electron transport in a scaled MOSFET device are discussed. The QET model allows simulations of quantum confinement transport, and nonlocal and hot-carrier effects in scaled MOSFETs.

  1. Water Transport in PEM Fuel Cells: Advanced Modeling, Material Selection,

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Testing and Design Optimization | Department of Energy in PEM Fuel Cells: Advanced Modeling, Material Selection, Testing and Design Optimization Water Transport in PEM Fuel Cells: Advanced Modeling, Material Selection, Testing and Design Optimization Part of a $100 million fuel cell award announced by DOE Secretary Bodman on Oct. 25, 2006. 2_cfd.pdf (21.58 KB) More Documents & Publications Fuel Cell Kickoff Meeting Agenda Water Transport in PEM Fuel Cells: Advanced Modeling, Material

  2. Large-Scale Transport Model Uncertainty and Sensitivity Analysis: Distributed Sources in Complex Hydrogeologic Systems

    SciTech Connect (OSTI)

    Sig Drellack, Lance Prothro

    2007-12-01

    The Underground Test Area (UGTA) Project of the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office is in the process of assessing and developing regulatory decision options based on modeling predictions of contaminant transport from underground testing of nuclear weapons at the Nevada Test Site (NTS). The UGTA Project is attempting to develop an effective modeling strategy that addresses and quantifies multiple components of uncertainty including natural variability, parameter uncertainty, conceptual/model uncertainty, and decision uncertainty in translating model results into regulatory requirements. The modeling task presents multiple unique challenges to the hydrological sciences as a result of the complex fractured and faulted hydrostratigraphy, the distributed locations of sources, the suite of reactive and non-reactive radionuclides, and uncertainty in conceptual models. Characterization of the hydrogeologic system is difficult and expensive because of deep groundwater in the arid desert setting and the large spatial setting of the NTS. Therefore, conceptual model uncertainty is partially addressed through the development of multiple alternative conceptual models of the hydrostratigraphic framework and multiple alternative models of recharge and discharge. Uncertainty in boundary conditions is assessed through development of alternative groundwater fluxes through multiple simulations using the regional groundwater flow model. Calibration of alternative models to heads and measured or inferred fluxes has not proven to provide clear measures of model quality. Therefore, model screening by comparison to independently-derived natural geochemical mixing targets through cluster analysis has also been invoked to evaluate differences between alternative conceptual models. Advancing multiple alternative flow models, sensitivity of transport predictions to parameter uncertainty is assessed through Monte Carlo simulations. The

  3. Simple Model Representations of Transport in a Complex Fracture...

    Office of Scientific and Technical Information (OSTI)

    Effects on Long-Term Predictions Citation Details In-Document Search Title: Simple Model Representations of Transport in a Complex Fracture and Their Effects on Long-Term ...

  4. CO2 leakage impacts on shallow groundwater. Field-scale reactive-transport simulations informed by observations at a natural analog site

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Keating, Elizabeth H.; Hakala, J. Alexandra; Viswanathan, Hari; Carey, J. William; Pawar, Rajesh; Guthrie, George D.; Fessenden-Rahn, Julianna

    2013-03-01

    It is challenging to predict the degree to which shallow groundwater might be affected by leaks from a CO2 sequestration reservoir, particularly over long time scales and large spatial scales. In this study observations at a CO2 enriched shallow aquifer natural analog were used to develop a predictive model which is then used to simulate leakage scenarios. This natural analog provides the opportunity to make direct field observations of groundwater chemistry in the presence of elevated CO2, to collect aquifer samples and expose them to CO2 under controlled conditions in the laboratory, and to test the ability of multiphase reactivemore » transport models to reproduce measured geochemical trends at the field-scale. The field observations suggest that brackish water entrained with the upwelling CO2 are a more significant source of trace metals than in situ mobilization of metals due to exposure to CO2. The study focuses on a single trace metal of concern at this site: U. Experimental results indicate that cation exchange/adsorption and dissolution/precipitation of calcite containing trace amounts of U are important reactions controlling U in groundwater at this site, and that the amount of U associated with calcite is fairly well constrained. Simulations incorporating these results into a 3-D multi-phase reactive transport model are able to reproduce the measured ranges and trends between pH, pCO2, Ca, total C, U and Cl-at the field site. Although the true fluxes at the natural analog site are unknown, the cumulative CO2 flux inferred from these simulations are approximately equivalent to 37.8E-3 MT, approximately corresponding to a .001% leak rate for injection at a large (750 MW) power plant. The leakage scenario simulations suggest that if the leak only persists for a short time the volume of aquifer contaminated by CO2-induced mobilization of U will be relatively small, yet persistent over 100 a.« less

  5. Elucidating reactivity regimes in cyclopentane oxidation: Jet stirred reactor experiments, computational chemistry, and kinetic modeling

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Al Rashidi, Mariam J.; Thion, Sebastien; Togbe, Casimir; Dayma, Guillaume; Mehl, Marco; Dagaut, Philippe; Pitz, William J.; Zador, Judit; Sarathy, S. Mani

    2016-06-22

    This study is concerned with the identification and quantification of species generated during the combustion of cyclopentane in a jet stirred reactor (JSR). Experiments were carried out for temperatures between 740 and 1250 K, equivalence ratios from 0.5 to 3.0, and at an operating pressure of 10 atm. The fuel concentration was kept at 0.1% and the residence time of the fuel/O2/N2 mixture was maintained at 0.7 s. The reactant, product, and intermediate species concentration profiles were measured using gas chromatography and Fourier transform infrared spectroscopy. The concentration profiles of cyclopentane indicate inhibition of reactivity between 850-1000 K for φ=2.0more » and φ=3.0. This behavior is interesting, as it has not been observed previously for other fuel molecules, cyclic or non-cyclic. A kinetic model including both low- and high-temperature reaction pathways was developed and used to simulate the JSR experiments. The pressure-dependent rate coefficients of all relevant reactions lying on the PES of cyclopentyl + O2, as well as the C-C and C-H scission reactions of the cyclopentyl radical were calculated at the UCCSD(T)-F12b/cc-pVTZ-F12//M06-2X/6-311++G(d,p) level of theory. The simulations reproduced the unique reactivity trend of cyclopentane and the measured concentration profiles of intermediate and product species. Furthermore, sensitivity and reaction path analyses indicate that this reactivity trend may be attributed to differences in the reactivity of allyl radical at different conditions, and it is highly sensitive to the C-C/C-H scission branching ratio of the cyclopentyl radical decomposition.« less

  6. Chemical Kinetic Modeling of Advanced Transportation Fuels

    SciTech Connect (OSTI)

    PItz, W J; Westbrook, C K; Herbinet, O

    2009-01-20

    Development of detailed chemical kinetic models for advanced petroleum-based and nonpetroleum based fuels is a difficult challenge because of the hundreds to thousands of different components in these fuels and because some of these fuels contain components that have not been considered in the past. It is important to develop detailed chemical kinetic models for these fuels since the models can be put into engine simulation codes used for optimizing engine design for maximum efficiency and minimal pollutant emissions. For example, these chemistry-enabled engine codes can be used to optimize combustion chamber shape and fuel injection timing. They also allow insight into how the composition of advanced petroleum-based and non-petroleum based fuels affect engine performance characteristics. Additionally, chemical kinetic models can be used separately to interpret important in-cylinder experimental data and gain insight into advanced engine combustion processes such as HCCI and lean burn engines. The objectives are: (1) Develop detailed chemical kinetic reaction models for components of advanced petroleum-based and non-petroleum based fuels. These fuels models include components from vegetable-oil-derived biodiesel, oil-sand derived fuel, alcohol fuels and other advanced bio-based and alternative fuels. (2) Develop detailed chemical kinetic reaction models for mixtures of non-petroleum and petroleum-based components to represent real fuels and lead to efficient reduced combustion models needed for engine modeling codes. (3) Characterize the role of fuel composition on efficiency and pollutant emissions from practical automotive engines.

  7. Transportation Sector Model of the National Energy Modeling System. Volume 2 -- Appendices: Part 1

    SciTech Connect (OSTI)

    1998-01-01

    This volume contains input data and parameters used in the model of the transportation sector of the National Energy Modeling System. The list of Transportation Sector Model variables includes parameters for the following: Light duty vehicle modules (fuel economy, regional sales, alternative fuel vehicles); Light duty vehicle stock modules; Light duty vehicle fleet module; Air travel module (demand model and fleet efficiency model); Freight transport module; Miscellaneous energy demand module; and Transportation emissions module. Also included in these appendices are: Light duty vehicle market classes; Maximum light duty vehicle market penetration parameters; Aircraft fleet efficiency model adjustment factors; and List of expected aircraft technology improvements.

  8. A model for radionuclide transport in the Cooling Water System

    SciTech Connect (OSTI)

    Kahook, S.D.

    1992-08-01

    A radionuclide transport model developed to assess radiological levels in the K-reactor Cooling Water System (CWS) in the event of an inadvertent process water (PW) leakage to the cooling water (CW) in the heat exchangers (HX) is described. During and following a process water leak, the radionuclide transport model determines the time-dependent release rates of radionuclide from the cooling water system to the environment via evaporation to the atmosphere and blow-down to the Savannah River. The developed model allows for delay times associated with the transport of the cooling water radioactivity through cooling water system components. Additionally, this model simulates the time-dependent behavior of radionuclides levels in various CWS components. The developed model is incorporated into the K-reactor Cooling Tower Activity (KCTA) code. KCTA allows the accident (heat exchanger leak rate) and the cooling tower blow-down and evaporation rates to be described as time-dependent functions. Thus, the postulated leak and the consequence of the assumed leak can be modelled realistically. This model is the first of three models to be ultimately assembled to form a comprehensive Liquid Pathway Activity System (LPAS). LPAS will offer integrated formation, transport, deposition, and release estimates for radionuclides formed in a SRS facility. Process water and river water modules are forthcoming as input and downstream components, respectively, for KCTA.

  9. Modeling carbon nanotube growth on the catalyst-substrate surface subjected to reactive plasma [

    SciTech Connect (OSTI)

    Tewari, Aarti; Sharma, Suresh C.

    2014-06-15

    The paper presents a theoretical model to study the growth of the carbon nanotube (CNT) on the catalyst substrate surface subjected to reactive plasma. The charging rate of the CNT, kinetics of electron, ions and neutral atoms, the growth rate of the CNT because of diffusion and accretion of ions on the catalyst nanoparticle inclusion of the issue of the plasma sheath is undertaken in the present model. Numerical calculations on the effect of ion density and temperature and the substrate bias on the growth of the CNT have been carried out for typical glow discharge plasma parameters. It is found that the height of CNT increases with the ion density of carbon ions and radius of CNT decreases with hydrogen ion density. The substrate bias also affects the growth rate of the CNT. The field emission characteristics from the CNTs can be analyzed from the results obtained.

  10. Multiscale modeling for fluid transport in nanosystems.

    SciTech Connect (OSTI)

    Lee, Jonathan W.; Jones, Reese E.; Mandadapu, Kranthi Kiran; Templeton, Jeremy Alan; Zimmerman, Jonathan A.

    2013-09-01

    Atomistic-scale behavior drives performance in many micro- and nano-fluidic systems, such as mircrofludic mixers and electrical energy storage devices. Bringing this information into the traditionally continuum models used for engineering analysis has proved challenging. This work describes one such approach to address this issue by developing atomistic-to-continuum multi scale and multi physics methods to enable molecular dynamics (MD) representations of atoms to incorporated into continuum simulations. Coupling is achieved by imposing constraints based on fluxes of conserved quantities between the two regions described by one of these models. The impact of electric fields and surface charges are also critical, hence, methodologies to extend finite-element (FE) MD electric field solvers have been derived to account for these effects. Finally, the continuum description can have inconsistencies with the coarse-grained MD dynamics, so FE equations based on MD statistics were derived to facilitate the multi scale coupling. Examples are shown relevant to nanofluidic systems, such as pore flow, Couette flow, and electric double layer.

  11. Lessons Learned from Alternative Transportation Fuels: Modeling Transition Dynamics

    Alternative Fuels and Advanced Vehicles Data Center [Office of Energy Efficiency and Renewable Energy (EERE)]

    Lessons Learned from Alternative Transportation Fuels: Modeling Transition Dynamics C. Welch Technical Report NREL/TP-540-39446 February 2006 Lessons Learned from Alternative Transportation Fuels: Modeling Transition Dynamics C. Welch Prepared under Task Nos. HS04.2000 and HS06.1002 Technical Report NREL/TP-540-39446 February 2006 National Renewable Energy Laboratory 1617 Cole Boulevard, Golden, Colorado 80401-3393 303-275-3000 * www.nrel.gov Operated for the U.S. Department of Energy Office of

  12. Upscaling of U(VI) Desorption and Transport from Decimeter-Scale Heterogeneity to Plume-Scale Modeling

    SciTech Connect (OSTI)

    Curtis, Gary P; Kohler, Matthias; Kannappan, Ramakrishnan; Briggs, Martin; Day-Lewis, Fred

    2015-02-24

    Reactive solute transport in aquifers is commonly affected by rate limited mass transfer. This slow mass transfer can exhibit significant control on the times required to restore contaminated aquifers to near-pristine conditions under both ambient and forced-gradient flow systems and is therefore important to understand. Both nonreactive and reactive tracer experiments provide valuable insight into the exchange of solute between mobile and immobile porosity. At the grain scale and column scale, mass transfer limitations were manifested as a concentration rebound when contaminated sediments were contacted with pristine groundwater. This behavior was successfully modeled using the multirate mass transfer model. Mass transfer observed in a 2 m long intermediate laboratory scale experiment showed significant concentration rebound in the first half meter along a flowpath through the tank and negligible rebound near the exit of the tank. Experimental observations and model simulations show that although concentration rebound was small at the end of the tank, the overall elution of uranium from of the tank was still controlled by mass transfer which was manifested by a long tail. At the field scale, mass transfer parameters inferred from geo-electrical measurements of bulk conductivity and traditional conductivity measurements of fluid samples showed significant spatial variability. Overall the improved understanding of mass transfer across multiple scales should lead to more robust reactive transport simulations and site management.

  13. Unsaturated Groundwater and Heat Transport Model

    Energy Science and Technology Software Center (OSTI)

    2008-05-15

    TOUGH2-MP is a massive parallel version of the TOUGH2 Code, designed for computationally efficient parallel simulation of isothermal and nonisothermal flows of multicomponent, multiphase fluids in one, two, and three-dimensional porous and fractured media. The code runs on computers with parallel architecture or clusters and can be used for applications, such as radioactive waste disposal, CO2 geological sequestration, environmental assessment and remediation, reservoir engineering, and groundwater hydrology. The parallel simulator has achieved orders-of-the-magnitude improvement inmore » computational time and/or modeling problem size. The parallel simulator uses fully implicit time differencing and solves large, sparse linear systems arising from discretization of the partial differential equations for mass and energy balance. A domain decomposition approach is adopted for multiphase flow simulations with coarse- granularity parallel computation. Current version of TOUGH2-MP includes following modules: EOS1, EOS2, EOS3, EOS4, EOS5, EOS7, EOS7R, E0S8, EOS9, ECO2N, EWASG, and T2R3D.« less

  14. Methods for modeling impact-induced reactivity changes in small reactors.

    SciTech Connect (OSTI)

    Tallman, Tyler N.; Radel, Tracy E.; Smith, Jeffrey A.; Villa, Daniel L.; Smith, Brandon M.; Radel, Ross F.; Lipinski, Ronald J.; Wilson, Paul Philip Hood

    2010-10-01

    This paper describes techniques for determining impact deformation and the subsequent reactivity change for a space reactor impacting the ground following a potential launch accident or for large fuel bundles in a shipping container following an accident. This technique could be used to determine the margin of subcriticality for such potential accidents. Specifically, the approach couples a finite element continuum mechanics model (Pronto3D or Presto) with a neutronics code (MCNP). DAGMC, developed at the University of Wisconsin-Madison, is used to enable MCNP geometric queries to be performed using Pronto3D output. This paper summarizes what has been done historically for reactor launch analysis, describes the impact criticality analysis methodology, and presents preliminary results using representative reactor designs.

  15. Model documentation report: Transportation sector model of the National Energy Modeling System

    SciTech Connect (OSTI)

    Not Available

    1994-03-01

    This report documents the objectives, analytical approach and development of the National Energy Modeling System (NEMS) Transportation Model (TRAN). The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated by the model. This document serves three purposes. First, it is a reference document providing a detailed description of TRAN for model analysts, users, and the public. Second, this report meets the legal requirements of the Energy Information Administration (EIA) to provide adequate documentation in support of its statistical and forecast reports (Public Law 93-275, 57(b)(1)). Third, it permits continuity in model development by providing documentation from which energy analysts can undertake model enhancements, data updates, and parameter refinements.

  16. Test of models for electron transport in laser produced plasmas

    SciTech Connect (OSTI)

    Colombant, D.G.; Manheimer, W.M.; Busquet, M.

    2005-07-15

    This paper examines five different models of electron thermal transport in laser produced spherical implosions. These are classical, classical with a flux limit f, delocalization, beam deposition model, and Fokker-Planck solutions. In small targets, the results are strongly dependent on f for flux limit models, with small f's generating very steep temperature gradients. Delocalization models are characterized by large preheat in the center of the target. The beam deposition model agrees reasonably well with the Fokker-Planck simulation results. For large, high gain fusion targets, the delocalization model shows the gain substantially reduced by the preheat. However, flux limitation models show gain largely independent of f, with the beam deposition model also showing the same high gain.

  17. Edge turbulence and transport: Text and ATF modeling

    SciTech Connect (OSTI)

    Ritz, C.P.; Rhodes, T.L.; Lin, H.; Rowan, W.L.; Bengtson, R.; Wootton, A.J. . Fusion Research Center); Carreras, B.A.; Leboeuf, J.N.; Lee, D.K.; Harris, J.; Hidalgo, C.; Bell, J.D.; Holmes, J.A.; Isler, R.; Lynch, V.E.; Uckan, T. ); Diamond, P.H.; Ware, A.S. ); Thayer, D.R. (Science Applications Inter

    1990-01-01

    We present experimental results on edge turbulence and transport from the tokamak TEXT and the torsatron ATF. The measured electrostatic fluctuations can explain the edge transport of particles and energy. Certain drive (radiation) and stabilizing (velocity shear) terms are suggested by the results. The experimental fluctuation levels and spectral widths can be reproduced by considering the nonlinear evolution of the reduced MHD equations, incorporating a thermal drive from line radiation. In the tokamak limit (with toroidal electric field) the model corresponds to the resistivity gradient mode, while in the currentless torsatron or stellarator limit it corresponds to a thermally driven drift wave.

  18. Modelling On Photogeneration Of Hydroxyl Radical In Surface Waters And Its Reactivity Towards Pharmaceutical Wastes

    SciTech Connect (OSTI)

    Das, Radha; Vione, Davide; Rubertelli, Francesca; Maurino, Valter; Minero, Claudio; Barbati, Stephane; Chiron, Serge

    2010-10-26

    This paper reports a simple model to describe the formation and reactivity of hydroxyl radicals in the whole column of freshwater lakes. It is based on empirical irradiation data and is a function of the water chemical composition (the photochemically significant parameters NPOC, nitrate, nitrite, carbonate and bicarbonate), the lake conformation best expressed as the average depth, and the water absorption spectrum in a simplified Lambert-Beer approach. The purpose is to derive the lifetime of dissolved molecules, due to reaction with OH, on the basis of their second-order rate constants with the hydroxyl radical. The model was applied to two compounds of pharmaceutical wastes ibuprofen and carbamazepine, for which the second-order rate constants for reaction with the hydroxyl radical were measured by means of the competition kinetics with 2-propanol. The measured values of the rate constants are 1.0x10{sup 10} and 1.6x10{sup 10} M{sup -1} s{sup -1} for ibuprofen and carbamazepine, respectively. The model suggests that the lifetime of a given compound can be very variable in different lakes, even more than the lifetime of different compounds in the same lake. It can be concluded that as far as the reaction with OH, is concerned the concepts of photolability and photostability, traditionally attached to definite compounds, are ecosystem-dependent at least as much as they depend on the molecule under consideration.

  19. Sediment and radionuclide transport in rivers: radionuclide transport modeling for Cattaraugus and Buttermilk Creeks, New York

    SciTech Connect (OSTI)

    Onishi, Y.; Yabusaki, S.B.; Kincaid, C.T.; Skaggs, R.L.; Walters, W.H.

    1982-12-01

    SERATRA, a transient, two-dimensional (laterally-averaged) computer model of sediment-contaminant transport in rivers, satisfactorily resolved the distribution of sediment and radionuclide concentrations in the Cattaraugus Creek stream system in New York. By modeling the physical processes of advection, diffusion, erosion, deposition, and bed armoring, SERATRA routed three sediment size fractions, including cohesive soils, to simulate three dynamic flow events. In conjunction with the sediment transport, SERATRA computed radionuclide levels in dissolved, suspended sediment, and bed sediment forms for four radionuclides (/sup 137/Cs, /sup 90/Sr, /sup 239/ /sup 240/Pu, and /sup 3/H). By accounting for time-dependent sediment-radionuclide interaction in the water column and bed, SERATA is a physically explicit model of radionuclide fate and migration. Sediment and radionuclide concentrations calculated by SERATA in the Cattaraugus Creek stream system are in reasonable agreement with measured values. SERATRA is in the field performance phase of an extensive testing program designed to establish the utility of the model as a site assessment tool. The model handles not only radionuclides but other contaminants such as pesticides, heavy metals and other toxic chemicals. Now that the model has been applied to four field sites, including the latest study of the Cattaraugus Creek stream system, it is recommended that a final model be validated through comparison of predicted results with field data from a carefully controlled tracer test at a field site. It is also recommended that a detailed laboratory flume be tested to study cohesive sediment transport, deposition, and erosion characteristics. The lack of current understanding of these characteristics is one of the weakest areas hindering the accurate assessment of the migration of radionuclides sorbed by fine sediments of silt and clay.

  20. Comparison of a radial fractional transport model with tokamak experiments

    SciTech Connect (OSTI)

    Kullberg, A. Morales, G. J.; Maggs, J. E.

    2014-03-15

    A radial fractional transport model [Kullberg et al., Phys. Rev. E 87, 052115 (2013)], that correctly incorporates the geometric effects of the domain near the origin and removes the singular behavior at the outer boundary, is compared to results of off-axis heating experiments performed in the Rijnhuizen Tokamak Project (RTP), ASDEX Upgrade, JET, and DIII-D tokamak devices. This comparative study provides an initial assessment of the presence of fractional transport phenomena in magnetic confinement experiments. It is found that the nonlocal radial model is robust in describing the steady-state temperature profiles from RTP, but for the propagation of heat waves in ASDEX Upgrade, JET, and DIII-D the model is not clearly superior to predictions based on Fick's law. However, this comparative study does indicate that the order of the fractional derivative, ?, is likely a function of radial position in the devices surveyed.

  1. Anisotropic Elastic Resonance Scattering model for the Neutron Transport equation

    SciTech Connect (OSTI)

    Mohamed Ouisloumen; Abderrafi M. Ougouag; Shadi Z. Ghrayeb

    2014-11-24

    The resonance scattering transfer cross-section has been reformulated to account for anisotropic scattering in the center-of-mass of the neutron-nucleus system. The main innovation over previous implementations is the relaxation of the ubiquitous assumption of isotropic scattering in the center-of-mass and the actual effective use of scattering angle distributions from evaluated nuclear data files in the computation of the angular moments of the resonant scattering kernels. The formulas for the high order anisotropic moments in the laboratory system are also derived. A multi-group numerical formulation is derived and implemented into a module incorporated within the NJOY nuclear data processing code. An ultra-fine energy mesh cross section library was generated using these new theoretical models and then was used for fuel assembly calculations with the PARAGON lattice physics code. The results obtained indicate a strong effect of this new model on reactivity, multi-group fluxes and isotopic inventory during depletion.

  2. Understanding composite explosive energetics: 3, Reactive flow modeling of aluminum reaction kinetics in PETN and TNT

    SciTech Connect (OSTI)

    Tao, W.C.; Tarver, C.M.; Ornellas, D.L.

    1991-12-06

    Using Fabry-Perot interferometry techniques, we have determined that early time rate of energy release from detonating PETN and TNT explosives filled with 5 and 10 wt % of either 5 {mu}m of 18 {mu}m spherical aluminum (Al) particles. From the measured particle velocity data, we are able to infer the reaction rate of aluminum with the detonation products, and calculate the extent of reaction 1--3 {mu}s after the detonation. We observed that a substantional portion of the aluminum metal in all of the PETN and TNE formulations reacted within the timeframe of the one-dimensional experiment. In the PETN formulation filed with 5 wt % of 5 {mu}m aluminum, all of the metal reacted within 1.5 {mu}s, resulting in an increase of 22% in energy compared to pure PETN. A reactive-flow hydrodynamic model based on the Zeldovich-von Neumann-Doring (ZND) description of the reaction zone and subsequent reaction produce expansion (Taylor wave) is used to interpret the reaction rate of the aluminum particles with detonation product gases. The diffusion-controlled reaction mechanism for aluminum and the global kinetic parameters used in the model have been found to be consistent for all the PETN and TNT formulations.

  3. Data Assimilation in the ADAPT Photospheric Flux Transport Model

    SciTech Connect (OSTI)

    Hickmann, Kyle S.; Godinez, Humberto C.; Henney, Carl J.; Arge, C. Nick

    2015-03-17

    Global maps of the solar photospheric magnetic flux are fundamental drivers for simulations of the corona and solar wind and therefore are important predictors of geoeffective events. However, observations of the solar photosphere are only made intermittently over approximately half of the solar surface. The Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model uses localized ensemble Kalman filtering techniques to adjust a set of photospheric simulations to agree with the available observations. At the same time, this information is propagated to areas of the simulation that have not been observed. ADAPT implements a local ensemble transform Kalman filter (LETKF) to accomplish data assimilation, allowing the covariance structure of the flux-transport model to influence assimilation of photosphere observations while eliminating spurious correlations between ensemble members arising from a limited ensemble size. We give a detailed account of the implementation of the LETKF into ADAPT. Advantages of the LETKF scheme over previously implemented assimilation methods are highlighted.

  4. Modeling of transport phenomena in tokamak plasmas with neural networks

    SciTech Connect (OSTI)

    Meneghini, O.; Luna, C. J.; Smith, S. P.; Lao, L. L.

    2014-06-15

    A new transport model that uses neural networks (NNs) to yield electron and ion heat flux profiles has been developed. Given a set of local dimensionless plasma parameters similar to the ones that the highest fidelity models use, the NN model is able to efficiently and accurately predict the ion and electron heat transport profiles. As a benchmark, a NN was built, trained, and tested on data from the 2012 and 2013 DIII-D experimental campaigns. It is found that NN can capture the experimental behavior over the majority of the plasma radius and across a broad range of plasma regimes. Although each radial location is calculated independently from the others, the heat flux profiles are smooth, suggesting that the solution found by the NN is a smooth function of the local input parameters. This result supports the evidence of a well-defined, non-stochastic relationship between the input parameters and the experimentally measured transport fluxes. The numerical efficiency of this method, requiring only a few CPU-?s per data point, makes it ideal for scenario development simulations and real-time plasma control.

  5. Engineered Barrier System Degradation, Flow, and Transport Process Model Report

    SciTech Connect (OSTI)

    E.L. Hardin

    2000-07-17

    The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II).

  6. Transport Studies and Modeling in PEM Fuel Cells

    SciTech Connect (OSTI)

    Mittelsteadt, Cortney K.; Xu, Hui; Brawn, Shelly

    2014-07-30

    This project’s aim was to develop fuel cell components (i.e. membranes, gas-diffusion media (GDM), bipolar plates and flow fields) that possess specific properties (i.e. water transport and conductivity). A computational fluid dynamics model was developed to elucidate the effect of certain parameters on these specific properties. Ultimately, the model will be used to determine sensitivity of fuel cell performance to component properties to determine limiting components and to guide research. We have successfully reached our objectives and achieved most of the milestones of this project. We have designed and synthesized a variety of hydrocarbon block polymer membranes with lower equivalent weight, structure, chemistry, phase separation and process conditions. These membranes provide a broad selection with optimized water transport properties. We have also designed and constructed a variety of devices that are capable of accurately measuring the water transport properties (water uptake, water diffusivity and electro-osmatic drag) of these membranes. These transport properties are correlated to the membranes’ structures derived from X-ray and microscopy techniques to determine the structure-property relationship. We successfully integrated hydrocarbon membrane MEAs with a current distribution board (CBD) to study the impact of hydrocarbon membrane on water transport in fuel cells. We have designed and fabricated various GDM with varying substrate, diffusivity and micro-porous layers (MPL) and characterized their pore structure, tortuosity and hydrophobicity. We have derived a universal chart (MacMullin number as function of wet proofing and porosity) that can be used to characterize various GDM. The abovementioned GDMs have been evaluated in operating fuel cells; their performance is correlated to various pore structure, tortuosity and hydrophobicity of the GDM. Unfortunately, determining a universal relationship between the MacMullin number and these properties

  7. Building 235-F Goldsim Fate And Transport Model

    SciTech Connect (OSTI)

    Taylor, G. A.; Phifer, M. A.

    2012-09-14

    Savannah River National Laboratory (SRNL) personnel, at the request of Area Completion Projects (ACP), evaluated In-Situ Disposal (ISD) alternatives that are under consideration for deactivation and decommissioning (D&D) of Building 235-F and the Building 294-2F Sand Filter. SRNL personnel developed and used a GoldSim fate and transport model, which is consistent with Musall 2012, to evaluate relative to groundwater protection, ISD alternatives that involve either source removal and/or the grouting of portions or all of 235-F. This evaluation was conducted through the development and use of a Building 235-F GoldSim fate and transport model. The model simulates contaminant release from four 235-F process areas and the 294-2F Sand Filter. In addition, it simulates the fate and transport through the vadose zone, the Upper Three Runs (UTR) aquifer, and the Upper Three Runs (UTR) creek. The model is designed as a stochastic model, and as such it can provide both deterministic and stochastic (probabilistic) results. The results show that the median radium activity concentrations exceed the 5 ?Ci/L radium MCL at the edge of the building for all ISD alternatives after 10,000 years, except those with a sufficient amount of inventory removed. A very interesting result was that grouting was shown to basically have minimal effect on the radium activity concentration. During the first 1,000 years grouting may have some small positive benefit relative to radium, however after that it may have a slightly deleterious effect. The Pb-210 results, relative to its 0.06 ?Ci/L PRG, are essentially identical to the radium results, but the Pb-210 results exhibit a lesser degree of exceedance. In summary, some level of inventory removal will be required to ensure that groundwater standards are met.

  8. Compendium of Material Composition Data for Radiation Transport Modeling

    SciTech Connect (OSTI)

    Williams, Ralph G.; Gesh, Christopher J.; Pagh, Richard T.

    2006-10-31

    Computational modeling of radiation transport problems including homeland security, radiation shielding and protection, and criticality safety all depend upon material definitions. This document has been created to serve two purposes: 1) to provide a quick reference of material compositions for analysts and 2) a standardized reference to reduce the differences between results from two independent analysts. Analysts are always encountering a variety of materials for which elemental definitions are not readily available or densities are not defined. This document provides a location where unique or hard to define materials will be located to reduce duplication in research for modeling purposes. Additionally, having a common set of material definitions helps to standardize modeling across PNNL and provide two separate researchers the ability to compare different modeling results from a common materials basis.

  9. Model documentation report: Transportation sector model of the National Energy Modeling System

    SciTech Connect (OSTI)

    1997-02-01

    Over the past year, several modifications have been made to the NEMS Transportation Model, incorporating greater levels of detail and analysis in modules previously represented in the aggregate or under a profusion of simplifying assumptions. This document is intended to amend those sections of the Model Documentation Report (MDR) which describe these superseded modules. Significant changes have been implemented in the LDV Fuel Economy Model, the Alternative Fuel Vehicle Model, the LDV Fleet Module, and the Highway Freight Model. The relevant sections of the MDR have been extracted from the original document, amended, and are presented in the following pages. A brief summary of the modifications follows: In the Fuel Economy Model, modifications have been made which permit the user to employ more optimistic assumptions about the commercial viability and impact of selected technological improvements. This model also explicitly calculates the fuel economy of an array of alternative fuel vehicles (AFV`s) which are subsequently used in the estimation of vehicle sales. In the Alternative Fuel Vehicle Model, the results of the Fuel Economy Model have been incorporated, and the program flows have been modified to reflect that fact. In the Light Duty Vehicle Fleet Module, the sales of vehicles to fleets of various size are endogenously calculated in order to provide a more detailed estimate of the impacts of EPACT legislation on the sales of AFV`s to fleets. In the Highway Freight Model, the previous aggregate estimation has been replaced by a detailed Freight Truck Stock Model, where travel patterns, efficiencies, and energy intensities are estimated by industrial grouping. Several appendices are provided at the end of this document, containing data tables and supplementary descriptions of the model development process which are not integral to an understanding of the overall model structure.

  10. Turbulence transport modeling of the temporal outer heliosphere

    SciTech Connect (OSTI)

    Adhikari, L.; Zank, G. P.; Hu, Q.; Dosch, A.

    2014-09-20

    The solar wind can be regarded as a turbulent magnetofluid, evolving in an expanding solar wind and subject to turbulent driving by a variety of in situ sources. Furthermore, the solar wind and the drivers of turbulence are highly time-dependent and change with solar cycle. Turbulence transport models describing low-frequency magnetic and velocity fluctuations in the solar wind have so far neglected solar cycle effects. Here we consider the effects of solar cycle variability on a turbulence transport model developed by Zank et al. This model is appropriate for the solar wind beyond about 1 AU, and extensions have described the steady-state dependence of the magnetic energy density fluctuations, correlation length, and solar wind temperature throughout the outer heliosphere. We find that the temporal solar wind introduces a periodic variability, particularly beyond ?10 AU, in the magnetic energy density fluctuations, correlation length, and solar wind temperature. The variability is insufficient to account for the full observed variability in these quantities, but we find that the time-dependent solutions trace the steady-state solutions quite well, suggesting that the steady-state models are reasonable first approximations.

  11. Transportation Sector Model of the National Energy Modeling System. Volume 1

    SciTech Connect (OSTI)

    1998-01-01

    This report documents the objectives, analytical approach and development of the National Energy Modeling System (NEMS) Transportation Model (TRAN). The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated by the model. The NEMS Transportation Model comprises a series of semi-independent models which address different aspects of the transportation sector. The primary purpose of this model is to provide mid-term forecasts of transportation energy demand by fuel type including, but not limited to, motor gasoline, distillate, jet fuel, and alternative fuels (such as CNG) not commonly associated with transportation. The current NEMS forecast horizon extends to the year 2010 and uses 1990 as the base year. Forecasts are generated through the separate consideration of energy consumption within the various modes of transport, including: private and fleet light-duty vehicles; aircraft; marine, rail, and truck freight; and various modes with minor overall impacts, such as mass transit and recreational boating. This approach is useful in assessing the impacts of policy initiatives, legislative mandates which affect individual modes of travel, and technological developments. The model also provides forecasts of selected intermediate values which are generated in order to determine energy consumption. These elements include estimates of passenger travel demand by automobile, air, or mass transit; estimates of the efficiency with which that demand is met; projections of vehicle stocks and the penetration of new technologies; and estimates of the demand for freight transport which are linked to forecasts of industrial output. Following the estimation of energy demand, TRAN produces forecasts of vehicular emissions of the following pollutants by source: oxides of sulfur, oxides of nitrogen, total carbon, carbon dioxide, carbon monoxide, and volatile organic compounds.

  12. MODELING TRITIUM TRANSPORT, DEPOSITION AND RE-EMISSION

    SciTech Connect (OSTI)

    Viner, B.

    2012-04-03

    The atmospheric release of tritium oxide (HTO) potentially impacts human health, typically through inhalation or absorption. Due to HTO's similarity to water, vegetation will absorb HTO by solution in the leaf water and then re-emit it, creating a number of secondary sources of HTO. Currently, models used for emergency response at Savannah River Site incorporate the transport and deposition of HTO but do not provide estimates for its potential re-emission from vegetation or soil surface though re-emission could result in prolonged exposure and greater than predicted dose for an individual downwind. A simple model of HTO transport, deposition and re-emission has been developed to examine the potential increase in exposure and dose. The model simulates an initial release of HTO that moves with a mean wind and expands through diffusion as a Gaussian puff. Deposition is modeled using previous estimates of deposition velocity for HTO and re-emission is modeled using a time constant that describes how quickly HTO is transferred between the surface and atmosphere. Additional puffs are created to simulate re-emission of HTO as well as horizontal diffusion across model grid cells. An evaluation of field data indicates that the use of a re-emission module tends to improve model predictions through improved prediction of peak concentration magnitude and location. When considering dose, nearly all of the released material is included in the dose calculation when re-emission is included. Although exposure to HTO through re-emission occurs over a few hours, the incremental increase in dose is relatively small because the atmospheric concentration of re-emitted HTO is much lower than the initial release.

  13. THE LOS ALAMOS NATIONAL LABORATORY ATMOSPHERIC TRANSPORT AND DIFFUSION MODELS

    SciTech Connect (OSTI)

    M. WILLIAMS

    1999-08-01

    The LANL atmospheric transport and diffusion models are composed of two state-of-the-art computer codes. The first is an atmospheric wind model called HOThlAC, Higher Order Turbulence Model for Atmospheric circulations. HOTMAC generates wind and turbulence fields by solving a set of atmospheric dynamic equations. The second is an atmospheric diffusion model called RAPTAD, Random Particle Transport And Diffusion. RAPTAD uses the wind and turbulence output from HOTMAC to compute particle trajectories and concentration at any location downwind from a source. Both of these models, originally developed as research codes on supercomputers, have been modified to run on microcomputers. Because the capability of microcomputers is advancing so rapidly, the expectation is that they will eventually become as good as today's supercomputers. Now both models are run on desktop or deskside computers, such as an IBM PC/AT with an Opus Pm 350-32 bit coprocessor board and a SUN workstation. Codes have also been modified so that high level graphics, NCAR Graphics, of the output from both models are displayed on the desktop computer monitors and plotted on a laser printer. Two programs, HOTPLT and RAPLOT, produce wind vector plots of the output from HOTMAC and particle trajectory plots of the output from RAPTAD, respectively. A third CONPLT provides concentration contour plots. Section II describes step-by-step operational procedures, specifically for a SUN-4 desk side computer, on how to run main programs HOTMAC and RAPTAD, and graphics programs to display the results. Governing equations, boundary conditions and initial values of HOTMAC and RAPTAD are discussed in Section III. Finite-difference representations of the governing equations, numerical solution procedures, and a grid system are given in Section IV.

  14. Effect of a detailed radial core expansion reactivity feedback model on ATWS calculations using SASSYS/SAS4A

    SciTech Connect (OSTI)

    Wigeland, R.A.

    1986-01-01

    The present emphasis on inherent safety and inherently safe designs for liquid-metal reactors has resulted in a need to represent the various reactivity feedback mechanisms as accurately as possible. In particular, the reactivity feedback from radial core expansion has been found to provide the dominant negative feedback contribution in postulated anticipated transient without scram (ATWS) events. Review of the existing modeling in the SASSYS/SAS4A computer code system revealed that while the modeling may be adequate for the early phases of various unprotected transients, the accuracy would be less than desirable for the extended transients which typically occur for inherently safe designs. The existing model for calculating the reactivity feedback from radial core expansion uses a feedback from radial core expansion uses a feedback coefficient in conjunction with changes in the temperatures of the grid support plate and the above-core load pad. The accuracy of this approach is determined partly by the conditions used in deriving the feedback coefficient, and their relevance to the transient being investigated. Accuracy is also affected by the need to include effects other than those that could be directly related to changes in the grid plate and above-core load pad temperatures, such as subassembly bowing and the potential for clearances to occur between subassemblies in the above-core load pad region. As a result, a detailed model was developed in an attempt to account for these and other effects in a more mechanistic form.

  15. Modeling interfacial area transport in multi-fluid systems

    SciTech Connect (OSTI)

    Yarbro, S.L.

    1996-11-01

    Many typical chemical engineering operations are multi-fluid systems. They are carried out in distillation columns (vapor/liquid), liquid-liquid contactors (liquid/liquid) and other similar devices. An important parameter is interfacial area concentration, which determines the rate of interfluid heat, mass and momentum transfer and ultimately, the overall performance of the equipment. In many cases, the models for determining interfacial area concentration are empirical and can only describe the cases for which there is experimental data. In an effort to understand multiphase reactors and the mixing process better, a multi-fluid model has been developed as part of a research effort to calculate interfacial area transport in several different types of in-line static mixers. For this work, the ensemble-averaged property conservation equations have been derived for each fluid and for the mixture. These equations were then combined to derive a transport equation for the interfacial area concentration. The final, one-dimensional model was compared to interfacial area concentration data from two sizes of Kenics in-line mixer, two sizes of concurrent jet and a Tee mixer. In all cases, the calculated and experimental data compared well with the highest scatter being with the Tee mixer comparison.

  16. A computerized coal-water slurry transportation model

    SciTech Connect (OSTI)

    Ljubicic, B.R.; Trostad, B.; Bukurov, Z.; Cvijanovic, P.

    1995-12-01

    Coal-water fuel (CWF) technology has been developed to the point where full-scale commercialization is just a matter of gaining sufficient market confidence in the price stability of alternate fossil fuels. In order to generalize alternative fuel cost estimates for the desired combinations of processing and/or transportation, a great deal of flexibility is required owing to the understood lack of precision in many of the newly emerging coal technologies. Previously, decisions regarding the sequential and spatial arrangement of the various process steps were made strictly on the basis of experience, simplified analysis, and intuition. Over the last decade, computer modeling has progressed from empirically based correlation to that of intricate mechanistic analysis. Nomograms, charts, tables, and many simple rules of thumb have been made obsolete by the availability of complex computer models. Given the ability to view results graphically in real or near real time, the engineer can immediately verify, from a practical standpoint, whether the initial assumptions and inputs were indeed valid. If the feasibility of a project is being determined in the context of a lack of specific data, the ability to provide a dynamic software-based solution is crucial. Furthermore, the resulting model can be used to establish preliminary operating procedures, test control logic, and train plant/process operators. Presented in this paper is a computerized model capable of estimating the delivered cost of CWF. The model uses coal-specific values, process and transport requirements, terrain factors, and input costs to determine the final operating configuration, bill of materials, and, ultimately, the capital, operating, and unit costs.

  17. Modeling two-fluid-phase flow and species transport in porous...

    Office of Scientific and Technical Information (OSTI)

    Publisher's Accepted Manuscript: Modeling two-fluid-phase flow and species transport in porous media This content will become publicly available on March 3, 2017 Title: Modeling ...

  18. Dynamic modeling of injection-induced fault reactivation and ground motion and impact on surface structures and human perception

    SciTech Connect (OSTI)

    Rutqvist, Jonny; Cappa, Frederic; Rinaldi, Antonio P.; Godano, Maxime

    2014-12-31

    We summarize recent modeling studies of injection-induced fault reactivation, seismicity, and its potential impact on surface structures and nuisance to the local human population. We used coupled multiphase fluid flow and geomechanical numerical modeling, dynamic wave propagation modeling, seismology theories, and empirical vibration criteria from mining and construction industries. We first simulated injection-induced fault reactivation, including dynamic fault slip, seismic source, wave propagation, and ground vibrations. From co-seismic average shear displacement and rupture area, we determined the moment magnitude to about Mw = 3 for an injection-induced fault reactivation at a depth of about 1000 m. We then analyzed the ground vibration results in terms of peak ground acceleration (PGA), peak ground velocity (PGV), and frequency content, with comparison to the U.S. Bureau of Mines vibration criteria for cosmetic damage to buildings, as well as human-perception vibration limits. For the considered synthetic Mw = 3 event, our analysis showed that the short duration, high frequency ground motion may not cause any significant damage to surface structures, and would not cause, in this particular case, upward CO2 leakage, but would certainly be felt by the local population.

  19. Dynamic modeling of injection-induced fault reactivation and ground motion and impact on surface structures and human perception

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rutqvist, Jonny; Cappa, Frederic; Rinaldi, Antonio P.; Godano, Maxime

    2014-12-31

    We summarize recent modeling studies of injection-induced fault reactivation, seismicity, and its potential impact on surface structures and nuisance to the local human population. We used coupled multiphase fluid flow and geomechanical numerical modeling, dynamic wave propagation modeling, seismology theories, and empirical vibration criteria from mining and construction industries. We first simulated injection-induced fault reactivation, including dynamic fault slip, seismic source, wave propagation, and ground vibrations. From co-seismic average shear displacement and rupture area, we determined the moment magnitude to about Mw = 3 for an injection-induced fault reactivation at a depth of about 1000 m. We then analyzed themore » ground vibration results in terms of peak ground acceleration (PGA), peak ground velocity (PGV), and frequency content, with comparison to the U.S. Bureau of Mines’ vibration criteria for cosmetic damage to buildings, as well as human-perception vibration limits. For the considered synthetic Mw = 3 event, our analysis showed that the short duration, high frequency ground motion may not cause any significant damage to surface structures, and would not cause, in this particular case, upward CO2 leakage, but would certainly be felt by the local population.« less

  20. Data Assimilation in the ADAPT Photospheric Flux Transport Model

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hickmann, Kyle S.; Godinez, Humberto C.; Henney, Carl J.; Arge, C. Nick

    2015-03-17

    Global maps of the solar photospheric magnetic flux are fundamental drivers for simulations of the corona and solar wind and therefore are important predictors of geoeffective events. However, observations of the solar photosphere are only made intermittently over approximately half of the solar surface. The Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model uses localized ensemble Kalman filtering techniques to adjust a set of photospheric simulations to agree with the available observations. At the same time, this information is propagated to areas of the simulation that have not been observed. ADAPT implements a local ensemble transform Kalman filter (LETKF)more » to accomplish data assimilation, allowing the covariance structure of the flux-transport model to influence assimilation of photosphere observations while eliminating spurious correlations between ensemble members arising from a limited ensemble size. We give a detailed account of the implementation of the LETKF into ADAPT. Advantages of the LETKF scheme over previously implemented assimilation methods are highlighted.« less

  1. Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

    SciTech Connect (OSTI)

    Zheng, L.; Spycher, N.; Xu, T.; Apps, J.; Kharaka, Y.; Birkholzer, J.T.

    2010-11-05

    In this study, reactive transport simulations were used to assess the mobilization and transport of organics with supercritical CO{sub 2} (SCC), and the co-injection and transport of H{sub 2}S with SCC. These processes were evaluated at conditions of typical storage reservoirs, and for cases of hypothetical leakage from a reservoir to an overlying shallower fresh water aquifer. Modeling capabilities were developed to allow the simulation of multiphase flow and transport of H{sub 2}O, CO{sub 2}, H{sub 2}S, as well as specific organic compounds (benzene), coupled with multicomponent geochemical reaction and transport. This included the development of a new simulator, TMVOC-REACT, starting from existing modules of the TOUGH2 family of codes. This work also included an extensive literature review, calculation, and testing of phase-partitioning properties for mixtures of the phases considered. The reactive transport simulations presented in this report are primarily intended to illustrate the capabilities of the new simulator. They are also intended to help evaluate and understand various processes at play, in a more qualitative than quantitative manner, and only for hypothetical scenarios. Therefore, model results are not intended as realistic assessments of groundwater quality changes for specific locations, and they certainly do not provide an exhaustive evaluation of all possible site conditions, especially given the large variability and uncertainty in hydrogeologic and geochemical parameter input into simulations. The first step in evaluating the potential mobilization and transport of organics was the identification of compounds likely to be present in deep storage formations, and likely to negatively impact freshwater aquifers if mobilized by SCC. On the basis of a literature review related to the occurrence of these organic compounds, their solubility in water and SCC, and their toxicity (as reflected by their maximum contaminant levels MCL), benzene was

  2. Modelling transport phenomena in a multi-physics context

    SciTech Connect (OSTI)

    Marra, Francesco

    2015-01-22

    Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.

  3. TOUGH2. Unsaturated Groundwater and Heat Transport Model

    SciTech Connect (OSTI)

    Pruess, K.

    1991-05-01

    TOUGH2 is a new and improved version of TOUGH. TOUGH2 offers added capabilities and user features, including the flexibility to handle different fluid mixtures (water, water with tracer; water, CO2; water, air; water, air, with vapor pressure lowering and water, hydrogen), facilities for processing of geometric data (computational grids), and an internal version control system to ensure referenceability of code applications. TOUGH2 is a multi-dimensional numerical model for simulating the coupled transport of water, vapor, air, and heat in porous and fractured media. The program provides options for specifying injection or withdrawal of heat and fluids. Although primarily designed for studies of high-level nuclear waste isolation in partially saturated geological media, it should also be useful for a wider range of problems in heat and moisture transfer, and in the drying of porous materials. For example, geothermal reservoir simulation problems can be handled simply by setting the air mass function equal to zero on input. The TOUGH2 simulator was developed for problems involving strongly heat-driven flow. To describe these phenomena a multi-phase approach to fluid and heat flow is used, which fully accounts for the movement of gaseous and liquid phases, their transport of latent and sensible heat, and phase transitions between liquid and vapor. TOUGH2 takes account of fluid flow in both liquid and gaseous phases occurring under pressure, viscous, and gravity forces according to Darcy`s law. Interference between the phases is represented by means of relative permeability functions. The code handles binary, but not Knudsen, diffusion in the gas phase and capillary and phase adsorption effects for the liquid phase. Heat transport occurs by means of conduction with thermal conductivity dependent on water saturation, convection, and binary diffusion, which includes both sensible and latent heat.

  4. transportation

    National Nuclear Security Administration (NNSA)

    security missions undertaken by the U.S. government.

    Pantex Plant's Calvin Nelson honored as Analyst of the Year for Transportation Security http:nnsa.energy.gov...

  5. Compendium of Material Composition Data for Radiation Transport Modeling

    SciTech Connect (OSTI)

    McConn, Ronald J.; Gesh, Christopher J.; Pagh, Richard T.; Rucker, Robert A.; Williams III, Robert

    2011-03-04

    Introduction Meaningful simulations of radiation transport applications require realistic definitions of material composition and densities. When seeking that information for applications in fields such as homeland security, radiation shielding and protection, and criticality safety, researchers usually encounter a variety of materials for which elemental compositions are not readily available or densities are not defined. Publication of the Compendium of Material Composition Data for Radiation Transport Modeling, Revision 0, in 2006 was the first step toward mitigating this problem. Revision 0 of this document listed 121 materials, selected mostly from the combined personal libraries of staff at the Pacific Northwest National Laboratory (PNNL), and thus had a scope that was recognized at the time to be limited. Nevertheless, its creation did provide a well-referenced source of some unique or hard-to-define material data in a format that could be used directly in radiation transport calculations being performed at PNNL. Moreover, having a single common set of material definitions also helped to standardize at least one aspect of the various modeling efforts across the laboratory by providing separate researchers the ability to compare different model results using a common basis of materials. The authors of the 2006 compendium understood that, depending on its use and feedback, the compendium would need to be revised to correct errors or inconsistencies in the data for the original 121 materials, as well as to increase (per users suggestions) the number of materials listed. This 2010 revision of the compendium has accomplished both of those objectives. The most obvious change is the increased number of materials from 121 to 372. The not-so-obvious change is the mechanism used to produce the data listed here. The data listed in the 2006 document were compiled, evaluated, entered, and error-checked by a group of individuals essentially by hand, providing no library

  6. Active patterning and asymmetric transport in a model actomyosin network

    SciTech Connect (OSTI)

    Wang, Shenshen; Wolynes, Peter G.

    2013-12-21

    Cytoskeletal networks, which are essentially motor-filament assemblies, play a major role in many developmental processes involving structural remodeling and shape changes. These are achieved by nonequilibrium self-organization processes that generate functional patterns and drive intracellular transport. We construct a minimal physical model that incorporates the coupling between nonlinear elastic responses of individual filaments and force-dependent motor action. By performing stochastic simulations we show that the interplay of motor processes, described as driving anti-correlated motion of the network vertices, and the network connectivity, which determines the percolation character of the structure, can indeed capture the dynamical and structural cooperativity which gives rise to diverse patterns observed experimentally. The buckling instability of individual filaments is found to play a key role in localizing collapse events due to local force imbalance. Motor-driven buckling-induced node aggregation provides a dynamic mechanism that stabilizes the two-dimensional patterns below the apparent static percolation limit. Coordinated motor action is also shown to suppress random thermal noise on large time scales, the two-dimensional configuration that the system starts with thus remaining planar during the structural development. By carrying out similar simulations on a three-dimensional anchored network, we find that the myosin-driven isotropic contraction of a well-connected actin network, when combined with mechanical anchoring that confers directionality to the collective motion, may represent a novel mechanism of intracellular transport, as revealed by chromosome translocation in the starfish oocyte.

  7. A Two-Dimensional Model for the Analysis of Contaminant Transport in a Fractured Porous Medium.

    Energy Science and Technology Software Center (OSTI)

    1991-03-05

    CHAINT-MC is a two-dimensional finite element model applicable to the transport of a dissolved radionuclide in a fractured porous medium along with radioactive chain decay and subsequent transport of the dissolved daughters.

  8. Reduced Lorenz models for anomalous transport and profile resilience

    SciTech Connect (OSTI)

    Rypdal, K.; Garcia, O. E.

    2007-02-15

    The physical basis for the Lorenz equations for convective cells in stratified fluids, and for magnetized plasmas imbedded in curved magnetic fields, are reexamined with emphasis on anomalous transport. It is shown that the Galerkin truncation leading to the Lorenz equations for the closed boundary problem is incompatible with finite fluxes through the system in the limit of vanishing diffusion. An alternative formulation leading to the Lorenz equations is proposed, invoking open boundaries and the notion of convective streamers and their back-reaction on the profile gradient, giving rise to resilience of the profile. Particular emphasis is put on the diffusionless limit, where these equations reduce to a simple dynamical system depending only on one single forcing parameter. This model is studied numerically, stressing experimentally observable signatures, and some of the perils of dimension-reducing approximations are discussed.

  9. A generalized Fokker-Planck model applied to beam transport

    SciTech Connect (OSTI)

    Prinja, A.K.; Pomraning, G.C.

    1998-12-31

    In this paper the authors consider a generalized Fokker-Planck (GFP) model for the transport of charged-particle beams, when scattering is not sufficiently forward peaked for the well-known Fokker-Planck (FP) approximation to hold. This approximation is strictly valid in the limit that the total scattering cross section {sigma}{sub s} {r_arrow} {infinity} and the mean cosine of scattering {bar {mu}} {r_arrow} 1. When scattering is not sufficiently forward peaked, higher order Fokker-Planck expansions, restricted to differential cross sections that fall off sufficiently rapidly, can be developed. For instance, the Henyey-Greenstein differential cross section does not possess an FP limit at all, while the screened Rutherford cross section satisfies the FP limit only marginally, and its higher order FP limits do not exist. For cross sections that fall off faster than screened Rutherford, including the exponential phase function, higher order truncations exist.

  10. Critical review: Radionuclide transport, sediment transport, and water quality mathematical modeling; and radionuclide adsorption/desorption mechanisms

    SciTech Connect (OSTI)

    Onishi, Y.; Serne, R.J.; Arnold, E.M.; Cowan, C.E.; Thompson, F.L.

    1981-01-01

    This report describes the results of a detailed literature review of radionuclide transport models applicable to rivers, estuaries, coastal waters, the Great Lakes, and impoundments. Some representatives sediment transport and water quality models were also reviewed to evaluate if they can be readily adapted to radionuclide transport modeling. The review showed that most available transport models were developed for dissolved radionuclide in rivers. These models include the mechanisms of advection, dispersion, and radionuclide decay. Since the models do not include sediment and radionuclide interactions, they are best suited for simulating short-term radionuclide migration where: (1) radionuclides have small distribution coefficients; (2) sediment concentrations in receiving water bodies are very low. Only 5 of the reviewed models include full sediment and radionuclide interactions: CHMSED developed by Fields; FETRA SERATRA, and TODAM developed by Onishi et al, and a model developed by Shull and Gloyna. The 5 models are applicable to cases where: (1) the distribution coefficient is large; (2) sediment concentrations are high; or (3) long-term migration and accumulation are under consideration. The report also discusses radionuclide absorption/desorption distribution ratios and addresses adsorption/desorption mechanisms and their controlling processes for 25 elements under surface water conditions. These elements are: Am, Sb, C, Ce, Cm, Co, Cr, Cs, Eu, I, Fe, Mn, Np, P, Pu, Pm, Ra, Ru, Sr, Tc, Th, {sup 3}H, U, Zn and Zr.

  11. Modeling the Energy Use of a Connected and Automated Transportation...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... from policies, including legality, insurance, liability, incentives, and treatment ... on Transportation: Energy Use, Greenhouse Gas Emissions, and Other Factors: http:...

  12. Reaction-based Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center

    SciTech Connect (OSTI)

    Tsyh Yeh, Gour

    2007-12-21

    This research sought to examine biogeochemical processes likely to take place in the less conductive materials above and below the gravel during the in situ ethanol biostimulation experiment conducted at Area 2 during 2005-2006. The in situ experiment in turn examined the hypothesis that injection of electron donor into this layer would induce formation of a redox barrier in the less conductive materials, resulting in decreased mass transfer of uranium out these materials and attendant declines in groundwater U(VI) concentration. Our project focuses on the development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. This report summarizes research activities conducted at The University of Central Florida (2004-2007), the development of biogeochemical and reactive transport models and the conduction of numerical simulations at laboratory, column, and field scales.

  13. Transportation Sector Model of the National Energy Modeling System. Volume 2 -- Appendices: Part 2

    SciTech Connect (OSTI)

    1998-01-01

    The attachments contained within this appendix provide additional details about the model development and estimation process which do not easily lend themselves to incorporation in the main body of the model documentation report. The information provided in these attachments is not integral to the understanding of the model`s operation, but provides the reader with opportunity to gain a deeper understanding of some of the model`s underlying assumptions. There will be a slight degree of replication of materials found elsewhere in the documentation, made unavoidable by the dictates of internal consistency. Each attachment is associated with a specific component of the transportation model; the presentation follows the same sequence of modules employed in Volume 1. The following attachments are contained in Appendix F: Fuel Economy Model (FEM)--provides a discussion of the FEM vehicle demand and performance by size class models; Alternative Fuel Vehicle (AFV) Model--describes data input sources and extrapolation methodologies; Light-Duty Vehicle (LDV) Stock Model--discusses the fuel economy gap estimation methodology; Light Duty Vehicle Fleet Model--presents the data development for business, utility, and government fleet vehicles; Light Commercial Truck Model--describes the stratification methodology and data sources employed in estimating the stock and performance of LCT`s; Air Travel Demand Model--presents the derivation of the demographic index, used to modify estimates of personal travel demand; and Airborne Emissions Model--describes the derivation of emissions factors used to associate transportation measures to levels of airborne emissions of several pollutants.

  14. A generic model for transport in turbulent shear flows

    SciTech Connect (OSTI)

    Newton, Andrew P. L.; Kim, Eun-Jin [Department of Applied Mathematics, University of Sheffield, Sheffield, S3 7RH (United Kingdom)

    2011-05-15

    Turbulence regulation by large-scale shear flows is crucial for a predictive modeling of transport in plasma. In this paper the suppression of turbulent transport by large-scale flows is studied numerically by measuring the turbulent diffusion D{sub t} and scalar amplitude of decaying passive scalar fields n{sup '} advected by various turbulent flows. Both uniform flows and shear flows are shown to suppress turbulence causing the quenching in transport and turbulence amplitude. The uniform flows U{sub 0}={Lambda}y with the advection rate {Lambda} in the case of a finite correlated forcing with {tau}{sub F}=1 gives rise to the advection/sweeping effect which suppresses D{sub t}, and as {proportional_to}{Lambda}{sup -2} for {Lambda}>>{tau}{sub F}{sup -1}. In contrast, no influence of the uniform flow is found in the case of a short correlated forcing {tau}{sub F}{yields}0 due to Galilean invariance. For the shear flow U{sub 0}={Omega}sinxy ({Omega}= constant shearing rate) with the appropriate choice of the forcing ({tau}{sub F}{yields}0) the nature of transport suppression is shown to crucially depend on the properties of the turbulence. Specifically, for prescribed turbulence with a short correlation time {tau}{sub c}={tau}{sub F}<<{Omega}{sup -1}, the turbulence statistics scale as D{sub t{proportional_to}{Omega}}{sup -0.02}, {proportional_to}{Omega}{sup -0.62} and cross-phase cos{theta}{proportional_to}{Omega}{sup 0.29}. For consistently evolved turbulence with a finite correlation time {tau}{sub c{>=}{Omega}}{sup -1}, turbulence statistics are suppressed more strongly as D{sub t{proportional_to}{Omega}}{sup -1.75}, {proportional_to}{Omega}{sup -2.41}, {proportional_to}{Omega}{sup -0.65} and <{omega}{sup '2}>{proportional_to}{Omega}{sup -0.50}. A novel renormalization scheme is then introduced to rescale our results into the regime within which the kinetic energy and enstrophy are unchanged by

  15. Interfacial Structure and Reactivity | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    a robust, molecular-scale understanding of its structure and reactivity? Research Context The transport of ions across the electrodeelectrolyte interface can lead to kinetic...

  16. RADTRAD: A simplified model for RADionuclide Transport and Removal...

    Office of Scientific and Technical Information (OSTI)

    radioactive material due to containment sprays, natural deposition, filters, and other ... FILTERS; QUALITY ASSURANCE; SOURCE TERMS; SPRAYS; TRANSPORT; RADIATION DOSES; R CODES; ...

  17. Predicting tropospheric ozone and hydroxyl radical in a global, three-dimensional, chemistry, transport, and deposition model

    SciTech Connect (OSTI)

    Atherton, C.S.

    1995-01-05

    Two of the most important chemically reactive tropospheric gases are ozone (O{sub 3}) and the hydroxyl radical (OH). Although ozone in the stratosphere is a necessary protector against the sun`s radiation, tropospheric ozone is actually a pollutant which damages materials and vegetation, acts as a respiratory irritant, and is a greenhouse gas. One of the two main sources of ozone in the troposphere is photochemical production. The photochemistry is initiated when hydrocarbons and carbon monoxide (CO) react with nitrogen oxides (NO{sub x} = NO + NO{sub 2}) in the presence of sunlight. Reaction with the hydroxyl radical, OH, is the main sink for many tropospheric gases. The hydroxyl radical is highly reactive and has a lifetime on the order of seconds. Its formation is initiated by the photolysis of tropospheric ozone. Tropospheric chemistry involves a complex, non-linear set of chemical reactions between atmospheric species that vary substantially in time and space. To model these and other species on a global scale requires the use of a global, three-dimensional chemistry, transport, and deposition (CTD) model. In this work, I developed two such three dimensional CTD models. The first model incorporated the chemistry necessary to model tropospheric ozone production from the reactions of nitrogen oxides with carbon monoxide (CO) and methane (CH{sub 4}). The second also included longer-lived alkane species and the biogenic hydrocarbon isoprene, which is emitted by growing plants and trees. The models` ability to predict a number of key variables (including the concentration of O{sub 3}, OH, and other species) were evaluated. Then, several scenarios were simulated to understand the change in the chemistry of the troposphere since preindustrial times and the role of anthropogenic NO{sub x} on present day conditions.

  18. 2D numerical simulation of the MEP energy-transport model with a finite difference scheme

    SciTech Connect (OSTI)

    Romano, V. . E-mail: romano@dmi.unict.it

    2007-02-10

    A finite difference scheme of Scharfetter-Gummel type is used to simulate a consistent energy-transport model for electron transport in semiconductors devices, free of any fitting parameters, formulated on the basis of the maximum entropy principle. Simulations of silicon n{sup +}-n-n{sup +} diodes, 2D-MESFET and 2D-MOSFET and comparisons with the results obtained by a direct simulation of the Boltzmann transport equation and with other energy-transport models, known in the literature, show the validity of the model and the robustness of the numerical scheme.

  19. WIPP Documents - Transportation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Transportation

  20. Modeling two-fluid-phase flow and species transport in porous...

    Office of Scientific and Technical Information (OSTI)

    Modeling two-fluid-phase flow and species transport in porous media Citation Details In-Document Search This content will become publicly available on March 3, 2017 Title: Modeling ...

  1. Modeling of Diesel Exhaust Systems: A methodology to better simulate soot reactivity

    Broader source: Energy.gov [DOE]

    Discussed development of a methodology for creating accurate soot models for soot samples from various origins with minimal characterization

  2. Model Annex for Preparedness and Response to Radiological Transportation Incidents

    Broader source: Energy.gov [DOE]

    This part should contain a general statement of the intent of this Annex. To provide for the planning, preparedness and coordination of emergency service efforts to respond to a transportation...

  3. Water Transport in PEM Fuel Cells: Advanced Modeling, Material...

    Broader source: Energy.gov (indexed) [DOE]

    in PEM fuel cells, was given by CFDRC's J. Vernon Cole at a DOE fuel cell meeting in February 2007. newfccolecfd.pdf (976.38 KB) More Documents & Publications Water Transport in ...

  4. Boundary layer modeling of reactive flow over a porous surface with angled injection

    SciTech Connect (OSTI)

    Liu, Shiling; Fotache, Catalin G.; Hautman, Donald J.; Ochs, Stuart S. [United Technologies Research Center, MS 129-29, 411 Silver Lane, East Hartford, CT 06108 (United States); Chao, Beei-Huan [Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

    2008-08-15

    An analytical model was developed to investigate the dynamics of nonpremixed flames in a shear layer established between a mainstream flow of fuel-rich combustion products and a porous surface with an angled injection of air. In the model, a one-step overall chemical reaction was employed, together with boundary layer conservation equations solved using similarity solutions. Parametric studies were performed to understand the effects of equivalence ratio, temperature, and mass flow rate of the fuel and air streams on the flame standoff distance, surface temperature, and heat flux at the surface. The analytical model predictions were compared with computational fluid dynamics results obtained using the FLUENT commercial code for both the laminar and the turbulent flow models. Qualitative agreement in surface temperature was observed. Finally, the flame stability limits predicted by the model were compared with available experimental data and found to agree qualitatively, as well. (author)

  5. A mixture model for shock compression of porous multi-component reactive materials

    SciTech Connect (OSTI)

    Baer, M.R.

    1993-07-01

    A multiphase mixture model is presented to describe shock compression of highly porous, multi-component powders. Volume fractions are represented as independent kinematic variables and thermodynamically-admissible phase interaction constitutive models are formulated in the context of a three phase system. Numerical solutions of the multiphase flow equations simulated impact on a porous layer of mixed powders of Al and Fe{sub 2}O{sub 3}. The multiphase model predicts dispersive compaction waves which have features similar to observed time-resolved pressure measurements.

  6. A turbulent transport network model in MULTIFLUX coupled with TOUGH2

    SciTech Connect (OSTI)

    Danko, G.; Bahrami, D.; Birkholzer, J.T.

    2011-02-15

    A new numerical method is described for the fully iterated, conjugate solution of two discrete submodels, involving (a) a transport network model for heat, moisture, and airflows in a high-permeability, air-filled cavity; and (b) a variably saturated fractured porous medium. The transport network submodel is an integrated-parameter, computational fluid dynamics solver, describing the thermal-hydrologic transport processes in the flow channel system of the cavity with laminar or turbulent flow and convective heat and mass transport, using MULTIFLUX. The porous medium submodel, using TOUGH2, is a solver for the heat and mass transport in the fractured rock mass. The new model solution extends the application fields of TOUGH2 by integrating it with turbulent flow and transport in a discrete flow network system. We present demonstrational results for a nuclear waste repository application at Yucca Mountain with the most realistic model assumptions and input parameters including the geometrical layout of the nuclear spent fuel and waste with variable heat load for the individual containers. The MULTIFLUX and TOUGH2 model elements are fully iterated, applying a programmed reprocessing of the Numerical Transport Code Functionalization model-element in an automated Outside Balance Iteration loop. The natural, convective airflow field and the heat and mass transport in a representative emplacement drift during postclosure are explicitly solved in the new model. The results demonstrate that the direction and magnitude of the air circulation patterns and all transport modes are strongly affected by the heat and moisture transport processes in the surrounding rock, justifying the need for a coupled, fully iterated model solution such as the one presented in the paper.

  7. dfnWorks: A discrete fracture network framework for modeling subsurface flow and transport

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hyman, Jeffrey D.; Karra, Satish; Makedonska, Nataliia; Gable, Carl W.; Painter, Scott L.; Viswanathan, Hari S.

    2015-11-01

    DFNWORKS is a parallelized computational suite to generate three-dimensional discrete fracture networks (DFN) and simulate flow and transport. Developed at Los Alamos National Laboratory over the past five years, it has been used to study flow and transport in fractured media at scales ranging from millimeters to kilometers. The networks are created and meshed using DFNGEN, which combines FRAM (the feature rejection algorithm for meshing) methodology to stochastically generate three-dimensional DFNs with the LaGriT meshing toolbox to create a high-quality computational mesh representation. The representation produces a conforming Delaunay triangulation suitable for high performance computing finite volume solvers in anmore » intrinsically parallel fashion. Flow through the network is simulated in dfnFlow, which utilizes the massively parallel subsurface flow and reactive transport finite volume code PFLOTRAN. A Lagrangian approach to simulating transport through the DFN is adopted within DFNTRANS to determine pathlines and solute transport through the DFN. Example applications of this suite in the areas of nuclear waste repository science, hydraulic fracturing and CO2 sequestration are also included.« less

  8. dfnWorks: A discrete fracture network framework for modeling subsurface flow and transport

    SciTech Connect (OSTI)

    Hyman, Jeffrey D.; Karra, Satish; Makedonska, Nataliia; Gable, Carl W.; Painter, Scott L.; Viswanathan, Hari S.

    2015-11-01

    DFNWORKS is a parallelized computational suite to generate three-dimensional discrete fracture networks (DFN) and simulate flow and transport. Developed at Los Alamos National Laboratory over the past five years, it has been used to study flow and transport in fractured media at scales ranging from millimeters to kilometers. The networks are created and meshed using DFNGEN, which combines FRAM (the feature rejection algorithm for meshing) methodology to stochastically generate three-dimensional DFNs with the LaGriT meshing toolbox to create a high-quality computational mesh representation. The representation produces a conforming Delaunay triangulation suitable for high performance computing finite volume solvers in an intrinsically parallel fashion. Flow through the network is simulated in dfnFlow, which utilizes the massively parallel subsurface flow and reactive transport finite volume code PFLOTRAN. A Lagrangian approach to simulating transport through the DFN is adopted within DFNTRANS to determine pathlines and solute transport through the DFN. Example applications of this suite in the areas of nuclear waste repository science, hydraulic fracturing and CO2 sequestration are also included.

  9. Report of the 7th Meeting of the Transport Modeling Working Group

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    7 th Meeting of the Transport Modeling Working Group May 22 and 23, 2014 The Transport Modeling Working Group (TMWG) met over 1.5 days at the end of May at Lawrence Berkeley National Laboratory. The chosen topics were to discuss multiphase flow with a focus on the diffusion media and the nexus between durability and transport modeling. The format was similar to previous meetings with ample time for discussion led off by a few presentations pertinent to the topic at hand. Both core TMWG

  10. NREL: Transportation Research - Vehicle Thermal Management Models and Tools

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Models and Tools image of three models of semi truck cabs. Truck cab models drawn from CAD geometry using CoolCalc (left and center), and a model with overlay of computational fluid dynamics flow (right) indicate areas of heat absorption and loss. Illustrations by Jason Lustbader, Matt Jeffers, and Larry Chaney, NREL The National Renewable Energy Laboratory's (NREL's) vehicle thermal management modeling tools allow researchers to assess the trade-offs and calculate the potential benefits of

  11. Underground Test Area Subproject Phase I Data Analysis Task. Volume VII - Tritium Transport Model Documentation Package

    SciTech Connect (OSTI)

    1996-12-01

    Volume VII of the documentation for the Phase I Data Analysis Task performed in support of the current Regional Flow Model, Transport Model, and Risk Assessment for the Nevada Test Site Underground Test Area Subproject contains the tritium transport model documentation. Because of the size and complexity of the model area, a considerable quantity of data was collected and analyzed in support of the modeling efforts. The data analysis task was consequently broken into eight subtasks, and descriptions of each subtask's activities are contained in one of the eight volumes that comprise the Phase I Data Analysis Documentation.

  12. Simple Model Representations of Transport in a Complex Fracture...

    Office of Scientific and Technical Information (OSTI)

    It is common, however, to represent the complex fracture by much simpler models consisting ... Simple-model properties are often inferred from the analysis of short-term (one to a few ...

  13. Remarks on a model of thermal transport in nanofluids (Journal...

    Office of Scientific and Technical Information (OSTI)

    of Publication: United States Language: English Subject: 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; HEAT TRANSFER; FLOW MODELS; FLUIDS; NANOSTRUCTURES...

  14. Modeling of the electronic transport in multijunction solar cells

    SciTech Connect (OSTI)

    Rau, U.; Goldbach, M.

    1994-12-31

    Simulations of the electrical transport in multijunction thin-film solar cells made from polycrystalline silicon are presented. The authors investigate the effect of the grain size on the efficiency of the multijunction solar cell. Here, they concentrate on micro crystalline material with a high recombination velocity at the grain boundaries of 10{sup 4}cm/s. Typical results of their calculations demonstrate that based on the multijunction design structure consisting of 8 or more layers efficiencies of 14% may be obtained from 12--20 {micro}m thick solar cells.

  15. Streamtube Fate and Transport Modeling of the Source Term for the Old Radioactive Waste

    SciTech Connect (OSTI)

    Brewer, K.

    2000-11-16

    The modeling described in this report is an extension of previous fate and transport modeling for the Old Radioactive Waste Burial Ground Corrective Measures Study/Feasibility Study. The purpose of this and the previous modeling is to provide quantitative input to the screening of remedial alternatives for the CMS/FS for this site.

  16. DFNWorks. A discrete fracture network framework for modeling subsurface flow and transport

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hyman, Jeffrey D.; Karra, Satish; Makedonska, Nataliia; Gable, Carl W.; Painter, Scott L.; Viswanathan, Hari S.

    2015-08-10

    DFNWorks is a parallalized computational suite to generate three-dimensional discrete fracture networks (DFN) and simulate flow and transport. Developed at Los Alamos National Laboratory over the past five years, it has been used to study flow and transport in fractured media at scales ranging from millimeters to kilometers. The networks are created and meshed using dfnGen, which combines fram (the feature rejection algorithm for meshing) methodology to stochastically generate three-dimensional DFNs on the basis of site specific data with the LaGriT meshing toolbox to create a high-quality computational mesh representation, specifically a conforming Delaunay triangulation suitable for high performance computingmore » finite volume solvers, of the DFN in an intrinsically parallel fashion. Flow through the network is simulated in dfnFlow, which utilizes the massively parallel subsurface flow and reactive transport finite volume code pflotran. A Lagrangian approach to simulating transport through the DFN is adopted within dfnTrans, which is an extension of the walkabout particle tracking method to determine pathlines through the DFN. Example applications of this suite in the areas of nuclear waste repository science, hydraulic fracturing and CO2 sequestration are also included.« less

  17. DFNWorks. A discrete fracture network framework for modeling subsurface flow and transport

    SciTech Connect (OSTI)

    Hyman, Jeffrey D.; Karra, Satish; Makedonska, Nataliia; Gable, Carl W.; Painter, Scott L.; Viswanathan, Hari S.

    2015-08-10

    DFNWorks is a parallalized computational suite to generate three-dimensional discrete fracture networks (DFN) and simulate flow and transport. Developed at Los Alamos National Laboratory over the past five years, it has been used to study flow and transport in fractured media at scales ranging from millimeters to kilometers. The networks are created and meshed using dfnGen, which combines fram (the feature rejection algorithm for meshing) methodology to stochastically generate three-dimensional DFNs on the basis of site specific data with the LaGriT meshing toolbox to create a high-quality computational mesh representation, specifically a conforming Delaunay triangulation suitable for high performance computing finite volume solvers, of the DFN in an intrinsically parallel fashion. Flow through the network is simulated in dfnFlow, which utilizes the massively parallel subsurface flow and reactive transport finite volume code pflotran. A Lagrangian approach to simulating transport through the DFN is adopted within dfnTrans, which is an extension of the walkabout particle tracking method to determine pathlines through the DFN. Example applications of this suite in the areas of nuclear waste repository science, hydraulic fracturing and CO2 sequestration are also included.

  18. A review of wind field models for atmospheric transport

    SciTech Connect (OSTI)

    Ramsdell, J.V. Jr.; Skyllingstad, E.D.

    1993-06-01

    The primary objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation dose that individuals could have received as a result of emissions since 1944 from the US Department of Energy`s (DOE) Hanford Site near Richland, Washington. The HEDR Project is developing a computer code to estimate these doses and their uncertainties. The code, known as the HEDR integrated Code (HEDRIC), consists of four separate component codes. One of the component codes, called the Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET) combines meteorological and release data to estimate time-integrated air concentrations and surface contamination at specific locations in the vicinity of the Hanford Site. The RATCHET domain covers approximately 75,000 square miles, extending from the crest of the Cascade Mountains on the west to the eastern edge of the Idaho panhandle and from central Oregon on the south to the Canadian border. This letter report explains the procedures in RATCHET that transform observed wind data into the wind fields used in atmospheric transport calculations. It also describes and evaluates alternative procedures not selected for use in RATCHET.

  19. Centrifuge modeling of LNAPL transport in partially saturated sand

    SciTech Connect (OSTI)

    Esposito, G.; Allersma, H.G.B.; Selvadurai, A.P.S.

    1999-12-01

    Model tests were performed at the Geotechnical Centrifuge Facility of Delft University of Technology, The Netherlands, to examine the mechanics of light nonaqueous phase liquid (LNAPL) movement in a partially saturated porous granular medium. The experiment simulated a 2D spill of LNAPL in an unsaturated sand prepared at two values of porosity. The duration of the centrifuge model tests corresponded to a prototype equivalent of 110 days. The choice of modeling a 2D flow together with the use of a transparent container enabled direct visual observation of the experiments. Scaling laws developed in connection with other centrifuge modeling studies were used to support the test results. Tests were conducted at two different centrifuge accelerations to verify, by means of the modeling of models technique, the similitude between the different experiments. The paper presents details of the experimental methodologies and the measuring techniques used to evaluate the final distribution of water and LNAPL content in the soils.

  20. Lessons Learned from Alternative Transportation Fuels: Modeling Transition Dynamics

    SciTech Connect (OSTI)

    Welch, C.

    2006-02-01

    Report focuses on understanding how analytical system modeling and data from AFV experiences could improve our understanding of the dynamic forces governing the transition to a hydrogen future.

  1. Water Transport in PEM Fuel Cells: Advanced Modeling, Material...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    in PEM Fuel Cells: Advanced Modeling, Material Selection, Testing and Design Optimization ... Optimization Part of a 100 million fuel cell award announced by DOE Secretary Bodman on ...

  2. Mass-transport models to predict toxicity of inhaled gases in the upper respiratory tract

    SciTech Connect (OSTI)

    Hubal, E.A.C.; Fedkiw, P.S.; Kimbell, J.S. [North Carolina State Univ., Raleigh, NC (United States)

    1996-04-01

    Mass-transport (the movement of a chemical species) plays an important role in determining toxic responses of the upper respiratory tract (URT) to inhaled chemicals. Mathematical dosimetry models incorporate physical characteristics of mass transport and are used to predict quantitative uptake (absorption rate) and distribution of inhaled gases and vapors in the respiratory tract. Because knowledge of dose is an essential component of quantitative risk assessment, dosimetry modeling plays an important role in extrapolation of animal study results to humans. A survey of existing mathematical dosimetry models for the URT is presented, limitations of current models are discussed, and adaptations of existing models to produce a generally applicable model are suggested. Reviewed URT dosimetry models are categorized as early, lumped-parameter, and distributed-parameter models. Specific examples of other relevant modeling work are also presented. 35 refs., 11 figs., 1 tab.

  3. Transportation Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    transportation-research TRACC RESEARCH Computational Fluid Dynamics Computational Structural Mechanics Transportation Systems Modeling Transportation Research Current Research Overview The U.S. Department of Transportation (USDOT) has established its only high-performance computing and engineering analysis research facility at Argonne National Laboratory to provide applications support in key areas of applied research and development for the USDOT community. The Transportation Research and

  4. Modeling the effect of gas transport on the formation of defects during thermolysis of powder moldings

    SciTech Connect (OSTI)

    Song, J.H.; Edirisinghe, M.J.; Evans, J.R.; Twizell, E.H.

    1996-04-01

    The removal of binder from ceramic or metal moldings by thermolysis involves the transport of degradation products through the parent organic phase and the vacated porous body. A numerical model has been developed to combine an equation which takes into account different gas-flow regimes with an equation for the transport of organic molecules in molten polymers. Computer modeling reveals the critical heating rate above which defects occur due to boiling of the polymer-monomer solution at the center of the molding. The situation in which a porous outer layer of the molding develops, offering resistance to flow of the evolved monomer gas, is then treated. This gives rise to a moving boundary with a variable concentration of diffusant which is dependent on the surface flux, gas transport coefficient and thickness of the porous layer. The contributions of diffusion and viscous flow to gas transport are considered. {copyright} {ital 1996 Materials Research Society.}

  5. A SCOPING STUDY: Development of Probabilistic Risk Assessment Models for Reactivity Insertion Accidents During Shutdown In U.S. Commercial Light Water Reactors

    SciTech Connect (OSTI)

    S. Khericha

    2011-06-01

    This report documents the scoping study of developing generic simplified fuel damage risk models for quantitative analysis from inadvertent reactivity insertion events during shutdown (SD) in light water pressurized and boiling water reactors. In the past, nuclear fuel reactivity accidents have been analyzed both mainly deterministically and probabilistically for at-power and SD operations of nuclear power plants (NPPs). Since then, many NPPs had power up-rates and longer refueling intervals, which resulted in fuel configurations that may potentially respond differently (in an undesirable way) to reactivity accidents. Also, as shown in a recent event, several inadvertent operator actions caused potential nuclear fuel reactivity insertion accident during SD operations. The set inadvertent operator actions are likely to be plant- and operation-state specific and could lead to accident sequences. This study is an outcome of the concern which arose after the inadvertent withdrawal of control rods at Dresden Unit 3 in 2008 due to operator actions in the plant inadvertently three control rods were withdrawn from the reactor without knowledge of the main control room operator. The purpose of this Standardized Plant Analysis Risk (SPAR) Model development project is to develop simplified SPAR Models that can be used by staff analysts to perform risk analyses of operating events and/or conditions occurring during SD operation. These types of accident scenarios are dominated by the operator actions, (e.g., misalignment of valves, failure to follow procedures and errors of commissions). Human error probabilities specific to this model were assessed using the methodology developed for SPAR model human error evaluations. The event trees, fault trees, basic event data and data sources for the model are provided in the report. The end state is defined as the reactor becomes critical. The scoping study includes a brief literature search/review of historical events, developments of

  6. Modeling electron transport in the presence of electric and magnetic fields.

    SciTech Connect (OSTI)

    Fan, Wesley C.; Drumm, Clifton Russell; Pautz, Shawn D.; Turner, C. David

    2013-09-01

    This report describes the theoretical background on modeling electron transport in the presence of electric and magnetic fields by incorporating the effects of the Lorentz force on electron motion into the Boltzmann transport equation. Electromagnetic fields alter the electron energy and trajectory continuously, and these effects can be characterized mathematically by differential operators in terms of electron energy and direction. Numerical solution techniques, based on the discrete-ordinates and finite-element methods, are developed and implemented in an existing radiation transport code, SCEPTRE.

  7. Semiclassical matrix model for quantum chaotic transport with time-reversal symmetry

    SciTech Connect (OSTI)

    Novaes, Marcel

    2015-10-15

    We show that the semiclassical approach to chaotic quantum transport in the presence of time-reversal symmetry can be described by a matrix model. In other words, we construct a matrix integral whose perturbative expansion satisfies the semiclassical diagrammatic rules for the calculation of transport statistics. One of the virtues of this approach is that it leads very naturally to the semiclassical derivation of universal predictions from random matrix theory.

  8. Simulation model for oil slick transport in lakes

    SciTech Connect (OSTI)

    Shen, H.T.; Yapa, P.D.; Petroski, M.E.

    1987-10-01

    A computer model for simulating oil slick movement in lakes by a Lagrangian discrete parcel algorithm is presented. In this model the transformation of an oil slick due to advection, spreading, evaporation, and dissolution is considered. For open water conditions the movement of the oil slick by water current and wind is considered using the drifting factor formulation. For ice-covered conditions the drift velocity is determined according to the ice roughness and current velocity. The current distribution in the lake is determined by a rigid lid circulation model. In the spreading process the mechanical spreading of the oil slick due to the balance in inertia, gravity, viscous, and surface tension forces is considered, in addition to the dispersion of the surface oil layer. Boundary conditions along the shore are formulated according to the storage capacity of the shoreline. The model can be used for simulating either instantaneous or continuous oil spills. Sample simulations for oil spills in Lake St. Clair are presented.

  9. Temperature, humidity and air flow in the emplacement drifts using convection and dispersion transport models

    SciTech Connect (OSTI)

    Danko, G.; Birkholzer, J.T.; Bahrami, D.; Halecky, N.

    2009-10-01

    A coupled thermal-hydrologic-airflow model is developed, solving for the transport processes within a waste emplacement drift and the surrounding rockmass together at the proposed nuclear waste repository at Yucca Mountain. Natural, convective air flow as well as heat and mass transport in a representative emplacement drift during post-closure are explicitly simulated, using the MULTIFLUX model. The conjugate, thermal-hydrologic transport processes in the rockmass are solved with the TOUGH2 porous-media simulator in a coupled way to the in-drift processes. The new simulation results show that large-eddy turbulent flow, as opposed to small-eddy flow, dominate the drift air space for at least 5000 years following waste emplacement. The size of the largest, longitudinal eddy is equal to half of the drift length, providing a strong axial heat and moisture transport mechanism from the hot to the cold drift sections. The in-drift results are compared to those from simplified models using a surrogate, dispersive model with an equivalent dispersion coefficient for heat and moisture transport. Results from the explicit, convective velocity simulation model provide higher axial heat and moisture fluxes than those estimated from the previously published, simpler, equivalent-dispersion models, in addition to showing differences in temperature, humidity and condensation rate distributions along the drift length. A new dispersive model is also formulated, giving a time- and location-variable function that runs generally about ten times higher in value than the highest dispersion coefficient currently used in the Yucca Mountain Project as an estimate for the equivalent dispersion coefficient in the emplacement drift. The new dispersion coefficient variation, back-calculated from the convective model, can adequately describe the heat and mass transport processes in the emplacement drift example.

  10. Baseline requirements of the proposed action for the Transportation Management Division routing models

    SciTech Connect (OSTI)

    Johnson, P.E.; Joy, D.S.

    1995-02-01

    The potential impacts associated with the transportation of hazardous materials are important to shippers, carriers, and the general public. This is particularly true for shipments of radioactive material. The shippers are primarily concerned with safety, security, efficiency, and equipment requirements. The carriers are concerned with the potential impact that radioactive shipments may have on their operations--particularly if such materials are involved in an accident. The general public has also expressed concerns regarding the safety of transporting radioactive and other hazardous materials through their communities. Because transportation routes are a central concern in hazardous material transport, the prediction of likely routes is the first step toward resolution of these issues. In response to these routing needs, several models have been developed over the past fifteen years at Oak Ridge National Laboratory (ORNL). The HIGHWAY routing model is used to predict routes for truck transportation, the INTERLINE routing model is used to predict both rail and barge routes, and the AIRPORT locator model is used to determine airports with specified criteria near a specific location. As part of the ongoing improvement of the US Department of Energy`s (DOE) Environmental Management Transportation Management Division`s (EM-261) computer systems and development efforts, a Baseline Requirements Assessment Session on the HIGHWAY, INTERLINE, and AIRPORT models was held at ORNL on April 27, 1994. The purpose of this meeting was to discuss the existing capabilities of the models and data bases and to review enhancements of the models and data bases to expand their usefulness. The results of the Baseline Requirements Assessment Section will be discussed in this report. The discussions pertaining to the different models are contained in separate sections.

  11. Phase II Contaminant Transport Parameters for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 98: Frenchman Flat, Nye County, Nevada, Rev. No.: 0

    SciTech Connect (OSTI)

    DeNovio, Nicole M.; Bryant, Nathan; King, Chrissi B.; Bhark, Eric; Drellack, Sigmund L.; Pickens, John F.; Farnham, Irene; Brooks, Keely M.; Reimus, Paul; Aly, Alaa

    2005-04-01

    This report documents pertinent transport data and data analyses as part of the Phase II Corrective Action Investigation (CAI) for Frenchman Flat (FF) Corrective Action Unit (CAU) 98. The purpose of this data compilation and related analyses is to provide the primary reference to support parameterization of the Phase II FF CAU transport model.

  12. NREL: Transportation Research - NREL's Battery Life Predictive Model Helps

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Companies Take Charge NREL's Battery Life Predictive Model Helps Companies Take Charge October 26, 2015 A series of batteries hooked together next to a monitor. An example of a stationary, grid-connected battery is the NREL project from Erigo/EaglePicher Technologies, LLC Technologies. Inverters and nickel cadmium batteries inside of a utility scale 300 kW battery storage system will support Department of Defense micro-grids. Photo by Dennis Schroeder / NREL 32696 Companies that rely on

  13. BLT-EC (Breach, Leach and Transport-Equilibrium Chemistry) data input guide. A computer model for simulating release and coupled geochemical transport of contaminants from a subsurface disposal facility

    SciTech Connect (OSTI)

    MacKinnon, R.J.; Sullivan, T.M.; Kinsey, R.R.

    1997-05-01

    The BLT-EC computer code has been developed, implemented, and tested. BLT-EC is a two-dimensional finite element computer code capable of simulating the time-dependent release and reactive transport of aqueous phase species in a subsurface soil system. BLT-EC contains models to simulate the processes (container degradation, waste-form performance, transport, chemical reactions, and radioactive production and decay) most relevant to estimating the release and transport of contaminants from a subsurface disposal system. Water flow is provided through tabular input or auxiliary files. Container degradation considers localized failure due to pitting corrosion and general failure due to uniform surface degradation processes. Waste-form performance considers release to be limited by one of four mechanisms: rinse with partitioning, diffusion, uniform surface degradation, and solubility. Transport considers the processes of advection, dispersion, diffusion, chemical reaction, radioactive production and decay, and sources (waste form releases). Chemical reactions accounted for include complexation, sorption, dissolution-precipitation, oxidation-reduction, and ion exchange. Radioactive production and decay in the waste form is simulated. To improve the usefulness of BLT-EC, a pre-processor, ECIN, which assists in the creation of chemistry input files, and a post-processor, BLTPLOT, which provides a visual display of the data have been developed. BLT-EC also includes an extensive database of thermodynamic data that is also accessible to ECIN. This document reviews the models implemented in BLT-EC and serves as a guide to creating input files and applying BLT-EC.

  14. Conceptual model for regional radionuclide transport from a salt dome repository: a technical memorandum

    SciTech Connect (OSTI)

    Kier, R.S.; Showalter, P.A.; Dettinger, M.D.

    1980-05-30

    Disposal of high-level radioactive wastes is a major environmental problem influencing further development of nuclear energy in this country. Salt domes in the Gulf Coast Basin are being investigated as repository sites. A major concern is geologic and hydrologic stability of candidate domes and potential transport of radionuclides by groundwater to the biosphere prior to their degradation to harmless levels of activity. This report conceptualizes a regional geohydrologic model for transport of radionuclides from a salt dome repository. The model considers transport pathways and the physical and chemical changes that would occur through time prior to the radionuclides reaching the biosphere. Necessary, but unknown inputs to the regional model involve entry and movement of fluids through the repository dome and across the dome-country rock interface and the effect on the dome and surrounding strata of heat generated by the radioactive wastes.

  15. Collisional particle-in-cell modeling for energy transport accompanied by atomic processes in dense plasmas

    SciTech Connect (OSTI)

    Mishra, R.; Beg, F. N.; Leblanc, P.; Sentoku, Y.; Wei, M. S.

    2013-07-15

    Fully relativistic collisional Particle-in-Cell (PIC) code, PICLS, has been developed to study extreme energy density conditions produced in intense laser-solid interaction. Recent extensions to PICLS, such as the implementation of dynamic ionization, binary collisions in a partially ionized plasma, and radiative losses, enhance the efficacy of simulating intense laser plasma interaction and subsequent energy transport in resistive media. Different ionization models are introduced and benchmarked against each other to check the suitability of the model. The atomic physics models are critical to determine the energy deposition and transport in dense plasmas, especially when they consist of high Z (atomic number) materials. Finally we demonstrate the electron transport simulations to show the importance of target material on fast electron dynamics.

  16. Contaminant Transport Parameters for the Groundwater Flow and Contaminant Transport Model of Corrective Action Units 101 and 102: Central and Western Pahute Mesa, Nye County, Nevada, Revision 0

    SciTech Connect (OSTI)

    Drici, Warda

    2003-08-01

    This report documents the analysis of the available transport parameter data conducted in support of the development of a Corrective Action Unit (CAU) groundwater flow model for Central and Western Pahute Mesa: CAUs 101 and 102.

  17. Carlsbad Area Office unveils full-scale model of new WIPP waste transportation cask

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Carlsbad Area Office Unveils Full-Scale Model Of New WIPP Waste Transportation Cask CARLSBAD, N.M., February 23, 2000 - The U.S. Department of Energy's (DOE) Carlsbad Area Office today unveiled a full-scale model of its newest waste transportation cask, the RH-72B, during a ceremony at the local DOE offices. "This is another milestone for the Department of Energy," said Dr. Inés Triay, Manager of the Carlsbad Area Office, describing the importance of the new container for those

  18. Transported PDF Modeling of Nonpremixed Turbulent CO/H-2/N-2 Jet Flames

    SciTech Connect (OSTI)

    Zhao, xinyu; Haworth, D. C.; Huckaby, E. David

    2012-01-01

    Turbulent CO/H{sub 2}/N{sub 2} (syngas) flames are simulated using a transported composition probability density function (PDF) method. A consistent hybrid Lagrangian particle/Eulerian mesh algorithm is used to solve the modeled PDF transport equation. The model includes standard k? turbulence, gradient transport for scalars, and Euclidean minimum spanning tree (EMST) mixing. Sensitivities of model results to variations in the turbulence model, the treatment of radiation heat transfer, the choice of chemical mechanism, and the PDF mixing model are explored. A baseline model reproduces the measured mean and rms temperature, major species, and minor species profiles reasonably well, and captures the scaling that is observed in the experiments. Both our results and the literature suggest that further improvements can be realized with adjustments in the turbulence model, the radiation heat transfer model, and the chemical mechanism. Although radiation effects are relatively small in these flames, consideration of radiation is important for accurate NO prediction. Chemical mechanisms that have been developed specifically for fuels with high concentrations of CO and H{sub 2} perform better than a methane mechanism that was not designed for this purpose. It is important to account explicitly for turbulencechemistry interactions, although the details of the mixing model do not make a large difference in the results, within reasonable limits.

  19. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model

    SciTech Connect (OSTI)

    P. Tucci

    2001-12-20

    This Analysis/Model Report (AMR) documents an updated analysis of water-level data performed to provide the saturated-zone, site-scale flow and transport model (CRWMS M&O 2000) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for model calibration. The previous analysis was presented in ANL-NBS-HS-000034, Rev 00 ICN 01, Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model (USGS 2001). This analysis is designed to use updated water-level data as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain. The objectives of this revision are to develop computer files containing (1) water-level data within the model area (DTN: GS010908312332.002), (2) a table of known vertical head differences (DTN: GS0109083 12332.003), and (3) a potentiometric-surface map (DTN: GS010608312332.001) using an alternate concept from that presented in ANL-NBS-HS-000034, Rev 00 ICN 01 for the area north of Yucca Mountain. The updated water-level data include data obtained from the Nye County Early Warning Drilling Program (EWDP) and data from borehole USW WT-24. In addition to being utilized by the SZ site-scale flow and transport model, the water-level data and potentiometric-surface map contained within this report will be available to other government agencies and water users for ground-water management purposes. The potentiometric surface defines an upper boundary of the site-scale flow model, as well as provides information useful to estimation of the magnitude and direction of lateral ground-water flow within the flow system. Therefore, the analysis documented in this revision is important to SZ flow and transport calculations in support of total system performance assessment.

  20. Gray and multigroup radiation transport models for two-dimensional binary stochastic media using effective opacities

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Olson, Gordon L.

    2015-09-24

    One-dimensional models for the transport of radiation through binary stochastic media do not work in multi-dimensions. In addition, authors have attempted to modify or extend the 1D models to work in multidimensions without success. Analytic one-dimensional models are successful in 1D only when assuming greatly simplified physics. State of the art theories for stochastic media radiation transport do not address multi-dimensions and temperature-dependent physics coefficients. Here, the concept of effective opacities and effective heat capacities is found to well represent the ensemble averaged transport solutions in cases with gray or multigroup temperature-dependent opacities and constant or temperature-dependent heat capacities. Inmore » every case analyzed here, effective physics coefficients fit the transport solutions over a useful range of parameter space. The transport equation is solved with the spherical harmonics method with angle orders of n=1 and 5. Although the details depend on what order of solution is used, the general results are similar, independent of angular order.« less

  1. Gray and multigroup radiation transport models for two-dimensional binary stochastic media using effective opacities

    SciTech Connect (OSTI)

    Olson, Gordon L.

    2015-09-24

    One-dimensional models for the transport of radiation through binary stochastic media do not work in multi-dimensions. In addition, authors have attempted to modify or extend the 1D models to work in multidimensions without success. Analytic one-dimensional models are successful in 1D only when assuming greatly simplified physics. State of the art theories for stochastic media radiation transport do not address multi-dimensions and temperature-dependent physics coefficients. Here, the concept of effective opacities and effective heat capacities is found to well represent the ensemble averaged transport solutions in cases with gray or multigroup temperature-dependent opacities and constant or temperature-dependent heat capacities. In every case analyzed here, effective physics coefficients fit the transport solutions over a useful range of parameter space. The transport equation is solved with the spherical harmonics method with angle orders of n=1 and 5. Although the details depend on what order of solution is used, the general results are similar, independent of angular order.

  2. Nondestructive determination of plutonium mass in spent fuel: prelliminary modeling results using the passive neutron Albedo reactivity technique

    SciTech Connect (OSTI)

    Evans, Louise G; Tobin, Stephen J; Schear, Melissa A; Menlove, Howard O; Lee, Sang Y; Swinhoe, Martyn T

    2009-01-01

    There are a variety of motivations for quantifying plutonium (Pu) in spent fuel assemblies by means of nondestructive assay (NDA) including the following: strengthening the capability of the International Atomic Energy Agency (LAEA) to safeguard nuclear facilities, quantifying shipper/receiver difference, determining the input accountability value at pyrochemical processing facilities, providing quantitative input to burnup credit and final safeguards measurements at a long-term repository. In order to determine Pu mass in spent fuel assemblies, thirteen NDA techniques were identified that provide information about the composition of an assembly. A key motivation of the present research is the realization that none of these techniques, in isolation, is capable of both (1) quantifying the Pu mass of an assembly and (2) detecting the diversion of a significant number of rods. It is therefore anticipated that a combination of techniques will be required. A 5 year effort funded by the Next Generation Safeguards Initiative (NGSI) of the U.S. DOE was recently started in pursuit of these goals. The first two years involves researching all thirteen techniques using Monte Carlo modeling while the final three years involves fabricating hardware and measuring spent fuel. Here, we present the work in two main parts: (1) an overview of this NGSI effort describing the motivations and approach being taken; (2) The preliminary results for one of the NDA techniques - Passive Neutron Albedo Reactivity (PNAR). The PNAR technique functions by using the intrinsic neutron emission of the fuel (primarily from the spontaneous fission of curium) to self-interrogate any fissile material present. Two separate measurements of the spent fuel are made, both with and without cadmium (Cd) present. The ratios of the Singles, Doubles and Triples count rates obtained in each case are analyzed; known as the Cd ratio. The primary differences between the two measurements are the neutron energy spectrum

  3. A POD reduced order model for resolving angular direction in neutron/photon transport problems

    SciTech Connect (OSTI)

    Buchan, A.G.; Calloo, A.A.; Goffin, M.G.; Dargaville, S.; Fang, F.; Pain, C.C.; Navon, I.M.

    2015-09-01

    This article presents the first Reduced Order Model (ROM) that efficiently resolves the angular dimension of the time independent, mono-energetic Boltzmann Transport Equation (BTE). It is based on Proper Orthogonal Decomposition (POD) and uses the method of snapshots to form optimal basis functions for resolving the direction of particle travel in neutron/photon transport problems. A unique element of this work is that the snapshots are formed from the vector of angular coefficients relating to a high resolution expansion of the BTE's angular dimension. In addition, the individual snapshots are not recorded through time, as in standard POD, but instead they are recorded through space. In essence this work swaps the roles of the dimensions space and time in standard POD methods, with angle and space respectively. It is shown here how the POD model can be formed from the POD basis functions in a highly efficient manner. The model is then applied to two radiation problems; one involving the transport of radiation through a shield and the other through an infinite array of pins. Both problems are selected for their complex angular flux solutions in order to provide an appropriate demonstration of the model's capabilities. It is shown that the POD model can resolve these fluxes efficiently and accurately. In comparison to high resolution models this POD model can reduce the size of a problem by up to two orders of magnitude without compromising accuracy. Solving times are also reduced by similar factors.

  4. User's manual for the Sandia Waste-Isolation Flow and Transport model (SWIFT).

    SciTech Connect (OSTI)

    Reeves, Mark; Cranwell, Robert M.

    1981-11-01

    This report describes a three-dimensional finite-difference model (SWIFT) which is used to simulate flow and transport processes in geologic media. The model was developed for use by the Nuclear Regulatory Commission in the analysis of deep geologic nuclear waste-disposal facilities. This document, as indicated by the title, is a user's manual and is intended to facilitate the use of the SWIFT simulator. Mathematical equations, submodels, application notes, and a description of the program itself are given herein. In addition, a complete input data guide is given along with several appendices which are helpful in setting up a data-input deck. Computer code SWIFT (Sandia Waste Isolation, Flow and Transport Model) is a fully transient, three-dimensional model which solves the coupled equations for transport in geologic media. The processes considered are: (1) fluid flow; (2) heat transport; (3) dominant-species miscible displacement; and (4) trace-species miscible displacement. The first three processes are coupled via fluid density and viscosity. Together they provide the velocity field on which the fourth process depends.

  5. Uncertainty Analysis Framework - Hanford Site-Wide Groundwater Flow and Transport Model

    SciTech Connect (OSTI)

    Cole, Charles R.; Bergeron, Marcel P.; Murray, Christopher J.; Thorne, Paul D.; Wurstner, Signe K.; Rogers, Phillip M.

    2001-11-09

    Pacific Northwest National Laboratory (PNNL) embarked on a new initiative to strengthen the technical defensibility of the predictions being made with a site-wide groundwater flow and transport model at the U.S. Department of Energy Hanford Site in southeastern Washington State. In FY 2000, the focus of the initiative was on the characterization of major uncertainties in the current conceptual model that would affect model predictions. The long-term goals of the initiative are the development and implementation of an uncertainty estimation methodology in future assessments and analyses using the site-wide model. This report focuses on the development and implementation of an uncertainty analysis framework.

  6. A DOUBLE-RING ALGORITHM FOR MODELING SOLAR ACTIVE REGIONS: UNIFYING KINEMATIC DYNAMO MODELS AND SURFACE FLUX-TRANSPORT SIMULATIONS

    SciTech Connect (OSTI)

    Munoz-Jaramillo, Andres; Martens, Petrus C. H.; Nandy, Dibyendu; Yeates, Anthony R. E-mail: dnandi@iiserkol.ac.i E-mail: anthony@maths.dundee.ac.u

    2010-09-01

    The emergence of tilted bipolar active regions (ARs) and the dispersal of their flux, mediated via processes such as diffusion, differential rotation, and meridional circulation, is believed to be responsible for the reversal of the Sun's polar field. This process (commonly known as the Babcock-Leighton mechanism) is usually modeled as a near-surface, spatially distributed {alpha}-effect in kinematic mean-field dynamo models. However, this formulation leads to a relationship between polar field strength and meridional flow speed which is opposite to that suggested by physical insight and predicted by surface flux-transport simulations. With this in mind, we present an improved double-ring algorithm for modeling the Babcock-Leighton mechanism based on AR eruption, within the framework of an axisymmetric dynamo model. Using surface flux-transport simulations, we first show that an axisymmetric formulation-which is usually invoked in kinematic dynamo models-can reasonably approximate the surface flux dynamics. Finally, we demonstrate that our treatment of the Babcock-Leighton mechanism through double-ring eruption leads to an inverse relationship between polar field strength and meridional flow speed as expected, reconciling the discrepancy between surface flux-transport simulations and kinematic dynamo models.

  7. GREET 1.0 -- Transportation fuel cycles model: Methodology and use

    SciTech Connect (OSTI)

    Wang, M.Q.

    1996-06-01

    This report documents the development and use of the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model. The model, developed in a spreadsheet format, estimates the full fuel-cycle emissions and energy use associated with various transportation fuels for light-duty vehicles. The model calculates fuel-cycle emissions of five criteria pollutants (volatile organic compounds, Co, NOx, SOx, and particulate matter measuring 10 microns or less) and three greenhouse gases (carbon dioxide, methane, and nitrous oxide). The model also calculates the total fuel-cycle energy consumption, fossil fuel consumption, and petroleum consumption using various transportation fuels. The GREET model includes 17 fuel cycles: petroleum to conventional gasoline, reformulated gasoline, clean diesel, liquefied petroleum gas, and electricity via residual oil; natural gas to compressed natural gas, liquefied petroleum gas, methanol, hydrogen, and electricity; coal to electricity; uranium to electricity; renewable energy (hydropower, solar energy, and wind) to electricity; corn, woody biomass, and herbaceous biomass to ethanol; and landfill gases to methanol. This report presents fuel-cycle energy use and emissions for a 2000 model-year car powered by each of the fuels that are produced from the primary energy sources considered in the study.

  8. Basic knowledge on radiative and transport properties to begin in thermal plasmas modelling

    SciTech Connect (OSTI)

    Cressault, Y.

    2015-05-15

    This paper has for objectives to present the radiative and the transport properties for people beginning in thermal plasmas. The first section will briefly recall the equations defined in numerical models applied to thermal plasmas; the second section will particularly deal with the estimation of radiative losses; the third part will quickly present the thermodynamics properties; and the last part will concern the transport coefficients (thermal conductivity, viscosity and electrical conductivity of the gas or mixtures of gases). We shall conclude the paper with a discussion about the validity of these results the lack of data for some specific applications, and some perspectives concerning these properties for non-equilibrium thermal plasmas.

  9. Conditional stochastic modeling of transport of contaminant in the vadose zone. Final project report

    SciTech Connect (OSTI)

    Yeh, T.C.J.; Harter, T.

    1995-06-01

    Spatial heterogeneity media leads to uncertainty in predicting both flow and transport in the vadose zone. In this work an efficient and flexible, combined analytical-numerical Monte Carlo approach is developed for the analysis of steady-state flow and transient transport processes in highly heterogeneous, variably saturated porous media. The approach is also used for the investigation of the validity of linear, first order analytical stochastic models. A combined analytical-numerical conditional simulation algorithm is developed to estimate the impact of in-situ soil hydraulic measurements on reducing the uncertainty of concentration and solute flux predictions.

  10. Link between hopping models and percolation scaling laws for charge transport in mixtures of small molecules

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ha, Dong -Gwang; Kim, Jang -Joo; Baldo, Marc A.

    2016-04-29

    Mixed host compositions that combine charge transport materials with luminescent dyes offer superior control over exciton formation and charge transport in organic light emitting devices (OLEDs). Two approaches are typically used to optimize the fraction of charge transport materials in a mixed host composition: either an empirical percolative model, or a hopping transport model. We show that these two commonly-employed models are linked by an analytic expression which relates the localization length to the percolation threshold and critical exponent. The relation is confirmed both numerically and experimentally through measurements of the relative conductivity of Tris(4-carbazoyl-9-ylphenyl) amine (TCTA) :1,3-bis(3,5-dipyrid-3-yl-phenyl) benzene (BmPyPb)more » mixtures with different concentrations, where the TCTA plays a role as hole conductor and the BmPyPb as hole insulator. Furthermore, the analytic relation may allow the rational design of mixed layers of small molecules for high-performance OLEDs.« less

  11. Surface chemical reactivity of ultrathin Pd(111) films on Ru(0001): Importance of orbital symmetry in the application of the d-band model

    SciTech Connect (OSTI)

    Yin, Xiangshi; Cooper, Valentino R.; Weitering, Hanno H.; Snijders, Paul C.

    2015-09-22

    The chemical bonding of adsorbate molecules on transition-metal surfaces is strongly influenced by the hybridization between the molecular orbitals and the metal d-band. The strength of this interaction is often correlated with the location of the metal d-band center relative to the Fermi level. Here, we exploit finite size effects in the electronic structure of ultrathin Pd(111) films grown on Ru(0001) to tune their reactivity by changing the film thickness one atom layer at a time, while keeping all other variables unchanged. Interestingly, while bulk Pd(111) is reactive toward oxygen, Pd(111) films below five monolayers are surprisingly inert. This observation is fully in line with the d-band model prediction when applied to the orbitals involved in the bonding. The shift of the d-band center with film thickness is primarily attributed to shifts in the partial density of states associated with the 4dxz and 4dyz orbitals. This study provides an in-depth look into the orbital specific contributions to the surface chemical reactivity, providing new insights that could be useful in surface catalysis.

  12. Surface chemical reactivity of ultrathin Pd(111) films on Ru(0001): Importance of orbital symmetry in the application of the d-band model

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yin, Xiangshi; Cooper, Valentino R.; Weitering, Hanno H.; Snijders, Paul C.

    2015-09-22

    The chemical bonding of adsorbate molecules on transition-metal surfaces is strongly influenced by the hybridization between the molecular orbitals and the metal d-band. The strength of this interaction is often correlated with the location of the metal d-band center relative to the Fermi level. Here, we exploit finite size effects in the electronic structure of ultrathin Pd(111) films grown on Ru(0001) to tune their reactivity by changing the film thickness one atom layer at a time, while keeping all other variables unchanged. Interestingly, while bulk Pd(111) is reactive toward oxygen, Pd(111) films below five monolayers are surprisingly inert. This observationmore » is fully in line with the d-band model prediction when applied to the orbitals involved in the bonding. The shift of the d-band center with film thickness is primarily attributed to shifts in the partial density of states associated with the 4dxz and 4dyz orbitals. This study provides an in-depth look into the orbital specific contributions to the surface chemical reactivity, providing new insights that could be useful in surface catalysis.« less

  13. The Role of Electron Transport and Trapping in MOS Total-Dose Modeling

    SciTech Connect (OSTI)

    Fleetwood, D.M.; Winokur, P.S.; Riewe, L.C.; Flament, O.; Paillet, P.; Leray, J.L.

    1999-07-19

    Radiation-induced hole and electron transport and trapping are fundamental to MOS total-dose models. Here we separate the effects of electron-hole annihilation and electron trapping on the neutralization of radiation-induced charge during switched-bias irradiation for hard and soft oxides, via combined thermally stimulated current (TSC) and capacitance-voltage measurements. We also show that present total-dose models cannot account for the thermal stability of deeply trapped electrons near the Si/SiO{sub 2} interface, or the inability of electrons in deep or shallow traps to contribute to TSC at positive bias following (1) room-temperature, (2) high-temperature, or (3) switched-bias irradiation. These results require revisions of modeling parameters and boundary conditions for hole and electron transport in SiO{sub 2}. The nature of deep and shallow electron traps in the near-interfacial SiO{sub 2} is discussed.

  14. Characterizing Indoor Airflow and Pollutant Transport using Simulation Modeling for Prototypical Buildings. I. Office Buildings

    SciTech Connect (OSTI)

    Sohn, M.D.; Daisey, J.M.; Feustel, H.E.

    1999-06-01

    This paper describes the first efforts at developing a set of prototypical buildings defined to capture the key features affecting airflow and pollutant transport in buildings. These buildings will be used to model airflow and pollutant transport for emergency response scenarios when limited site-specific information is available and immediate decisions must be made, and to better understand key features of buildings controlling occupant exposures to indoor pollutant sources. This paper presents an example of this approach for a prototypical intermediate-sized, open style, commercial building. Interzonal transport due to a short-term source release, e.g., accidental chemical spill, in the bottom and the upper floors is predicted and corresponding HVAC system operation effects and potential responses are considered. Three-hour average exposure estimates are used to compare effects of source location and HVAC operation.

  15. FINAL REPORT:Observation and Simulations of Transport of Molecules and Ions Across Model Membranes

    SciTech Connect (OSTI)

    MURAD, SOHAIL; JAMESON, CYNTHIA J

    2013-10-22

    During the this new grant we developed a robust methodology for investigating a wide range of properties of phospho-lipid bilayers. The approach developed is unique because despite using periodic boundary conditions, we can simulate an entire experiment or process in detail. For example, we can follow the entire permeation process in a lipid-membrane. This includes transport from the bulk aqueous phase to the lipid surface; permeation into the lipid; transport inside the lipid; and transport out of the lipid to the bulk aqueous phase again. We studied the transport of small gases in both the lipid itself and in model protein channels. In addition, we have examined the transport of nanocrystals through the lipid membrane, with the main goal of understanding the mechanical behavior of lipids under stress including water and ion leakage and lipid flip flop. Finally we have also examined in detail the deformation of lipids when under the influence of external fields, both mechanical and electrostatic (currently in progress). The important observations and conclusions from our studies are described in the main text of the report

  16. MODELING OF THE GROUNDWATER TRANSPORT AROUND A DEEP BOREHOLE NUCLEAR WASTE REPOSITORY

    SciTech Connect (OSTI)

    N. Lubchenko; M. Rodríguez-Buño; E.A. Bates; R. Podgorney; E. Baglietto; J. Buongiorno; M.J. Driscoll

    2015-04-01

    The concept of disposal of high-level nuclear waste in deep boreholes drilled into crystalline bedrock is gaining renewed interest and consideration as a viable mined repository alternative. A large amount of work on conceptual borehole design and preliminary performance assessment has been performed by researchers at MIT, Sandia National Laboratories, SKB (Sweden), and others. Much of this work relied on analytical derivations or, in a few cases, on weakly coupled models of heat, water, and radionuclide transport in the rock. Detailed numerical models are necessary to account for the large heterogeneity of properties (e.g., permeability and salinity vs. depth, diffusion coefficients, etc.) that would be observed at potential borehole disposal sites. A derivation of the FALCON code (Fracturing And Liquid CONvection) was used for the thermal-hydrologic modeling. This code solves the transport equations in porous media in a fully coupled way. The application leverages the flexibility and strengths of the MOOSE framework, developed by Idaho National Laboratory. The current version simulates heat, fluid, and chemical species transport in a fully coupled way allowing the rigorous evaluation of candidate repository site performance. This paper mostly focuses on the modeling of a deep borehole repository under realistic conditions, including modeling of a finite array of boreholes surrounded by undisturbed rock. The decay heat generated by the canisters diffuses into the host rock. Water heating can potentially lead to convection on the scale of thousands of years after the emplacement of the fuel. This convection is tightly coupled to the transport of the dissolved salt, which can suppress convection and reduce the release of the radioactive materials to the aquifer. The purpose of this work has been to evaluate the importance of the borehole array spacing and find the conditions under which convective transport can be ruled out as a radionuclide transport mechanism

  17. A charge carrier transport model for donor-acceptor blend layers

    SciTech Connect (OSTI)

    Fischer, Janine Widmer, Johannes; Koerner, Christian; Vandewal, Koen; Leo, Karl; Kleemann, Hans; Tress, Wolfgang; Riede, Moritz

    2015-01-28

    Highly efficient organic solar cells typically comprise donor-acceptor blend layers facilitating effective splitting of excitons. However, the charge carrier mobility in the blends can be substantially smaller than in neat materials, hampering the device performance. Currently, available mobility models do not describe the transport in blend layers entirely. Here, we investigate hole transport in a model blend system consisting of the small molecule donor zinc phthalocyanine (ZnPc) and the acceptor fullerene C{sub 60} in different mixing ratios. The blend layer is sandwiched between p-doped organic injection layers, which prevent minority charge carrier injection and enable exploiting diffusion currents for the characterization of exponential tail states from a thickness variation of the blend layer using numerical drift-diffusion simulations. Trap-assisted recombination must be considered to correctly model the conductivity behavior of the devices, which are influenced by local electron currents in the active layer, even though the active layer is sandwiched in between p-doped contacts. We find that the density of deep tail states is largest in the devices with 1:1 mixing ratio (E{sub t} = 0.14 eV, N{sub t} = 1.2 × 10{sup 18 }cm{sup −3}) directing towards lattice disorder as the transport limiting process. A combined field and charge carrier density dependent mobility model are developed for this blend layer.

  18. PLUVIUS: a generalized one-dimensional model of reactive pollutant behavior, including dry deposition, precipitation formation, and wet removal. Second edition

    SciTech Connect (OSTI)

    Easter, R.C.; Hales, J.M.

    1984-11-01

    This report is a second-edition user's manual for the PLUVIUS reactive-storm model. The PLUVIUS code simulates the formation of storm systems of a variety of types, and characterizes the behavior of air pollutants as they flow through, react within, and are scavenged by the storms. The computer code supplied with this report is known as PLUVIUS MOD 5.0, and is a substantial improvement over the MOD 3.1 version given in the original user's manual. Example applications of MOD 5.0 are given in the report to facilitate rapid application of the code for a variety of specific uses. 22 references, 7 figures, 48 tables.

  19. COMIS -- an international multizone air-flow and contaminant transport model

    SciTech Connect (OSTI)

    Feustel, H.E.

    1998-08-01

    A number of interzonal models have been developed to calculate air flows and pollutant transport mechanisms in both single and multizone buildings. A recent development in multizone air-flow modeling, the COMIS model, has a number of capabilities that go beyond previous models, much as COMIS can be used as either a stand-alone air-flow model with input and output features or as an infiltration module for thermal building simulation programs. COMIS was designed during a 12 month workshop at Lawrence Berkeley National Laboratory (LBNL) in 1988-89. In 1990, the Executive Committee of the International Energy Agency`s Energy Conservation in Buildings and Community Systems program created a working group on multizone air-flow modeling, which continued work on COMIS. The group`s objectives were to study physical phenomena causing air flow and pollutant (e.g., moisture) transport in multizone buildings, develop numerical modules to be integrated in the previously designed multizone air flow modeling system, and evaluate the computer code. The working group supported by nine nations, officially finished in late 1997 with the release of IISiBat/COMIS 3.0, which contains the documented simulation program COMIS, the user interface IISiBat, and reports describing the evaluation exercise.

  20. cDF Theory Software for mesoscopic modeling of equilibrium and transport phenomena

    Energy Science and Technology Software Center (OSTI)

    2015-12-01

    The approach is based on classical Density Functional Theory ((cDFT) coupled with the Poisson-Nernst-Planck (PNP) transport kinetics model and quantum mechanical description of short-range interaction and elementary transport processes. The model we proposed and implemented is fully atomistic, taking into account pairwise short-range and manybody long-range interactions. But in contrast to standard molecular dynamics (MD) simulations, where long-range manybody interactions are evaluated as a sum of pair-wise atom-atom contributions, we include them analytically based onmore » wellestablished theories of electrostatic and excluded volume interactions in multicomponent systems. This feature of the PNP/cDFT approach allows us to reach well beyond the length-scales accessible to MD simulations, while retaining the essential physics of interatomic interactions from first principles and in a parameter-free fashion.« less

  1. Flow and Containment Transport Code for Modeling Variably Saturated Porous Media

    Energy Science and Technology Software Center (OSTI)

    1998-05-14

    FACT is a finite element based code designed to model subsurface flow and contaminant transport. It was designed to perform transient three-dimensional calculations that simulate isothermal groundwater flow, moisture movement, and solute transport in variably saturated and fully saturated subsurface porous media. The code is designed specifically to handle complex multi-layer and/or heterogenous aquifer systems in an efficient manner and accommodates a wide range of boundary conditions. Additionally 1-D and 2-D (in Cartesian coordinates) problemsmore »are handled in FACT by simply limiting the number of elements in a particular direction(s) to one. The governing equations in FACT are formulated only in Cartesian coordinates. FACT writes out both ascii and graphical binary files that are TECPLOT-ready. Special features are also available within FACT for handling the typical groundwater modeling needs for remediation efforts at the Savannah River Site.« less

  2. cDF Theory Software for mesoscopic modeling of equilibrium and transport phenomena

    SciTech Connect (OSTI)

    2015-12-01

    The approach is based on classical Density Functional Theory ((cDFT) coupled with the Poisson-Nernst-Planck (PNP) transport kinetics model and quantum mechanical description of short-range interaction and elementary transport processes. The model we proposed and implemented is fully atomistic, taking into account pairwise short-range and manybody long-range interactions. But in contrast to standard molecular dynamics (MD) simulations, where long-range manybody interactions are evaluated as a sum of pair-wise atom-atom contributions, we include them analytically based on wellestablished theories of electrostatic and excluded volume interactions in multicomponent systems. This feature of the PNP/cDFT approach allows us to reach well beyond the length-scales accessible to MD simulations, while retaining the essential physics of interatomic interactions from first principles and in a parameter-free fashion.

  3. Flow and Containment Transport Code for Modeling Variably Saturated Porous Media

    Energy Science and Technology Software Center (OSTI)

    1998-05-14

    FACT is a finite element based code designed to model subsurface flow and contaminant transport. It was designed to perform transient three-dimensional calculations that simulate isothermal groundwater flow, moisture movement, and solute transport in variably saturated and fully saturated subsurface porous media. The code is designed specifically to handle complex multi-layer and/or heterogenous aquifer systems in an efficient manner and accommodates a wide range of boundary conditions. Additionally 1-D and 2-D (in Cartesian coordinates) problemsmore » are handled in FACT by simply limiting the number of elements in a particular direction(s) to one. The governing equations in FACT are formulated only in Cartesian coordinates. FACT writes out both ascii and graphical binary files that are TECPLOT-ready. Special features are also available within FACT for handling the typical groundwater modeling needs for remediation efforts at the Savannah River Site.« less

  4. A multi-model assessment of pollution transport to the Arctic

    SciTech Connect (OSTI)

    Shindell, D T; Chin, M; Dentener, F; Doherty, R M; Faluvegi, G; Fiore, A M; Hess, P; Koch, D M; MacKenzie, I A; Sanderson, M G; Schultz, M G; Schulz, M; Stevenson, D S; Teich, H; Textor, C; Wild, O; Bergmann, D J; Bey, I; Bian, H; Cuvelier, C; Duncan, B N; Folberth, G; Horowitz, L W; Jonson, J; Kaminski, J W; Marmer, E; Park, R; Pringle, K J; Schroeder, S; Szopa, S; Takemura, T; Zeng, G; Keating, T J; Zuber, A

    2008-03-13

    We examine the response of Arctic gas and aerosol concentrations to perturbations in pollutant emissions from Europe, East and South Asia, and North America using results from a coordinated model intercomparison. These sensitivities to regional emissions (mixing ratio change per unit emission) vary widely across models and species. Intermodel differences are systematic, however, so that the relative importance of different regions is robust. North America contributes the most to Arctic ozone pollution. For aerosols and CO, European emissions dominate at the Arctic surface but East Asian emissions become progressively more important with altitude, and are dominant in the upper troposphere. Sensitivities show strong seasonality: surface sensitivities typically maximize during boreal winter for European and during spring for East Asian and North American emissions. Mid-tropospheric sensitivities, however, nearly always maximize during spring or summer for all regions. Deposition of black carbon (BC) onto Greenland is most sensitive to North American emissions. North America and Europe each contribute {approx}40% of total BC deposition to Greenland, with {approx}20% from East Asia. Elsewhere in the Arctic, both sensitivity and total BC deposition are dominated by European emissions. Model diversity for aerosols is especially large, resulting primarily from differences in aerosol physical and chemical processing (including removal). Comparison of modeled aerosol concentrations with observations indicates problems in the models, and perhaps, interpretation of the measurements. For gas phase pollutants such as CO and O{sub 3}, which are relatively well-simulated, the processes contributing most to uncertainties depend on the source region and altitude examined. Uncertainties in the Arctic surface CO response to emissions perturbations are dominated by emissions for East Asian sources, while uncertainties in transport, emissions, and oxidation are comparable for European

  5. Mathematical model for oil slick transport and mixing in rivers. Special report

    SciTech Connect (OSTI)

    Shen, H.T.; Yapa, P.D.; Wang, D.S.; Yang, X.Q.

    1993-08-01

    The growing concern over the impacts of oil spills on aquatic environments has led to the development of many computer models for simulating the transport and spreading of oil slicks in surface waters. Almost all of these models were developed for coastal environments. A few river models exist. These models only considered the movement of surface oil slicks. In this study a two-layer model, ROSS2, is developed for simulating oil spills in rivers. This model considers the oil in the river to consist of a surface slick and suspended oil droplets entrained over the depth of the flow. The oil transformation processes considered in the model include advection, mechanical spreading, turbulent diffusion and mixing, evaporation, dissolution, emulsification, shoreline deposition and sinking. The model can be used for simulating instantaneous or continuous spills either on or under the water surface in rivers with or without an ice cover. The model has been implemented for the Ohio-Monongahela-Allegheny river system and the upper St. Lawrence River. This report describes the model formulation and implementation. A case study is presented along with detailed explanations of the program structure and its input and output. Although it is developed for simulating oil spills, the model can be applied to spills of other hazardous materials. Computer models, Oil spills, Oil slicks, Rivers.

  6. Modeling Gas-Phase Transport in Polymer-Electrolyte FuelCells

    SciTech Connect (OSTI)

    Weber, A.Z.; Newman, J.

    2006-08-17

    In this transaction, the equations and methodology for modeling convection and ordinary, Knudsen, and pressure diffusion of gases in a fuel-cell gas-diffusion layer are described. Some results examining the magnitudes of the various terms are also made. This derivation results in a self-consistent description of the various transport mechanisms and is robust for numerical solutions, especially for conditions involving different flow regimes or where the regime is not known a priori.

  7. A model for thermally driven heat and air transport in passive solar buildings

    SciTech Connect (OSTI)

    Jones, G.F.; Balcomb, J.D.; Otis, D.R.

    1985-01-01

    A model for transient interzone heat and air flow transport in passive solar buildings is presented incorporating wall boundary layers in stratified zones, and with interzone transport via apertures (doors and windows). The model includes features that have been observed in measurements taken in more than a dozen passive solar buildings. The model includes integral formulations of the laminar and turbulent boundary layer equations for the vertical walls which are then coupled to a one-dimensional core model for each zone. The cores in each zone exchange mass and energy through apertures that are modeled by an orifice type equation. The procedure is transient in that time dependence is retained only in the core equations which are solved by an explicit method. The model predicts room stratification of about 2/sup 0/C/m (1.1/sup 0/F/ft) for a room-to-room temperature difference of 0.56/sup 0/C(1/sup 0/F) which is in general agreement with the data.

  8. Model for thermally driven heat and air transport in passive solar buildings

    SciTech Connect (OSTI)

    Jones, G.F.; Balcomb, J.D.; Otis, D.R.

    1985-01-01

    A model for transient interzone heat and air flow transport in passive solar buildings is presented incorporating wall boundary layers in stratified zones, and with interzone transport via apertures (doors and windows). The model includes features that have been observed in measurements taken in more than a dozen passive solar buildings. The model includes integral formulations of the laminar and turbulent boundary layer equations for the vertical walls which are then coupled to a one-dimensional core model for each zone. The cores in each zone exchange mass and energy through apertures that are modeled by an orifice type equation. The procedure is transient in that time dependence is retained only in the core equations which are solved by an explicit method. The model predicts room stratification of about 2/sup 0/C/m (1.1/sup 0/F/ft) for a room-to-room temperature difference of 0.56/sup 0/C(1/sup 0/F) which is in general agreement with the data. 38 references, 10 figures, 1 table.

  9. Mark 22 Reactivity

    SciTech Connect (OSTI)

    Buckner, M.R.

    2001-07-02

    Calculations for reactivity held in control rods have underpredicted the observed Mark 22 reactivity. Reactivity predictions by charge designers have accounted for this by including large biases which change with exposure and reactor region. The purpose of this study was to thoroughly investigate the methods and data used in the reactivity calculations. The goal was to identify errors and improvements and make necessary corrections.

  10. Development and applications of GREET 2.7 -- The Transportation Vehicle-CycleModel.

    SciTech Connect (OSTI)

    Burnham, A.; Wang, M. Q.; Wu, Y.

    2006-12-20

    Argonne National Laboratory has developed a vehicle-cycle module for the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model. The fuel-cycle GREET model has been cited extensively and contains data on fuel cycles and vehicle operations. The vehicle-cycle model evaluates the energy and emission effects associated with vehicle material recovery and production, vehicle component fabrication, vehicle assembly, and vehicle disposal/recycling. With the addition of the vehicle-cycle module, the GREET model now provides a comprehensive, lifecycle-based approach to compare the energy use and emissions of conventional and advanced vehicle technologies (e.g., hybrid electric vehicles and fuel cell vehicles). This report details the development and application of the GREET 2.7 model. The current model includes six vehicles--a conventional material and a lightweight material version of a mid-size passenger car with the following powertrain systems: internal combustion engine, internal combustion engine with hybrid configuration, and fuel cell with hybrid configuration. The model calculates the energy use and emissions that are required for vehicle component production; battery production; fluid production and use; and vehicle assembly, disposal, and recycling. This report also presents vehicle-cycle modeling results. In order to put these results in a broad perspective, the fuel-cycle model (GREET 1.7) was used in conjunction with the vehicle-cycle model (GREET 2.7) to estimate total energy-cycle results.

  11. Estimating Bacteria Emissions from Inversion of Atmospheric Transport: Sensitivity to Modelled Particle Characteristics

    SciTech Connect (OSTI)

    Burrows, Susannah M.; Rayner, Perter; Butler, T.; Lawrence, M.

    2013-06-04

    Model-simulated transport of atmospheric trace components can be combined with observed concentrations to obtain estimates of ground-based sources using various inversion techniques. These approaches have been applied in the past primarily to obtain source estimates for long-lived trace gases such as CO2. We consider the application of similar techniques to source estimation for atmospheric aerosols, by using as a case study the estimation of bacteria emissions from different ecosystem regions in the global atmospheric chemistry and climate model ECHAM5/MESSy-Atmospheric Chemistry (EMAC). Simulated particle concentrations in the tropopause region and at high latitudes, as well as transport of particles to tundra and land ice regions are shown to be highly sensitive to scavenging in mixed-phase clouds, which is poorly characterized in most global climate models. This may be a critical uncertainty in correctly simulating the transport of aerosol particles to the Arctic. Source estimation via Monte Carlo Markov Chain is applied to a suite of sensitivity simulations and the global mean emissions are estimated. We present an analysis of the partitioning of uncertainties in the global mean emissions that are attributable to particle size, CCN activity, the ice nucleation scavenging ratios for mixed-phase and cold clouds, and measurement error. Uncertainty due to CCN activity or to a 1 um error in particle size is typically between 10% and 40% of the uncertainty due to data uncertainty, as measured by the 5%-ile to 95%-ile range of the Monte Carlo ensemble. Uncertainty attributable to the ice nucleation scavenging ratio in mized-phase clouds is as high as 10% to 20% of the data uncertainty. Taken together, the four model 20 parameters examined contribute about half as much to the uncertainty in the estimated emissions as do the measurements. This was a surprisingly large contribution from model uncertainty in light of the substantial data uncertainty, which ranges from 81

  12. Constraining Data Mining with Physical Models: Voltage- and Oxygen Pressure-Dependent Transport in Multiferroic Nanostructures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Strelcov, Evgheni; Belianinov, Alexei; Hsieh, Ying-Hui; Chu, Ying-Hao; Kalinin, Sergei V.

    2015-08-27

    Development of new generation electronic devices requires understanding and controlling the electronic transport in ferroic, magnetic, and optical materials, which is hampered by two factors. First, the complications of working at the nanoscale, where interfaces, grain boundaries, defects, and so forth, dictate the macroscopic characteristics. Second, the convolution of the response signals stemming from the fact that several physical processes may be activated simultaneously. Here, we present a method of solving these challenges via a combination of atomic force microscopy and data mining analysis techniques. Rational selection of the latter allows application of physical constraints and enables direct interpretation ofmore » the statistically significant behaviors in the framework of the chosen physical model, thus distilling physical meaning out of raw data. We demonstrate our approach with an example of deconvolution of complex transport behavior in a bismuth ferrite–cobalt ferrite nanocomposite in ambient and ultrahigh vacuum environments. Measured signal is apportioned into four electronic transport patterns, showing different dependence on partial oxygen and water vapor pressure. These patterns are described in terms of Ohmic conductance and Schottky emission models in the light of surface electrochemistry. Finally and furthermore, deep data analysis allows extraction of local dopant concentrations and barrier heights empowering our understanding of the underlying dynamic mechanisms of resistive switching.« less

  13. An integrated computer modeling environment for regional land use, air quality, and transportation planning

    SciTech Connect (OSTI)

    Hanley, C.J.; Marshall, N.L.

    1997-04-01

    The Land Use, Air Quality, and Transportation Integrated Modeling Environment (LATIME) represents an integrated approach to computer modeling and simulation of land use allocation, travel demand, and mobile source emissions for the Albuquerque, New Mexico, area. This environment provides predictive capability combined with a graphical and geographical interface. The graphical interface shows the causal relationships between data and policy scenarios and supports alternative model formulations. Scenarios are launched from within a Geographic Information System (GIS), and data produced by each model component at each time step within a simulation is stored in the GIS. A menu-driven query system is utilized to review link-based results and regional and area-wide results. These results can also be compared across time or between alternative land use scenarios. Using this environment, policies can be developed and implemented based on comparative analysis, rather than on single-step future projections. 16 refs., 3 figs., 2 tabs.

  14. Modeling the Energy Use of a Connected and Automated Transportation System (Poster)

    SciTech Connect (OSTI)

    Gonder, J.; Brown, A.

    2014-07-01

    Early research points to large potential impacts of connected and automated vehicles (CAVs) on transportation energy use - dramatic savings, increased use, or anything in between. Due to a lack of suitable data and integrated modeling tools to explore these complex future systems, analyses to date have relied on simple combinations of isolated effects. This poster proposes a framework for modeling the potential energy implications from increasing penetration of CAV technologies and for assessing technology and policy options to steer them toward favorable energy outcomes. Current CAV modeling challenges include estimating behavior change, understanding potential vehicle-to-vehicle interactions, and assessing traffic flow and vehicle use under different automation scenarios. To bridge these gaps and develop a picture of potential future automated systems, NREL is integrating existing modeling capabilities with additional tools and data inputs to create a more fully integrated CAV assessment toolkit.

  15. A Generalized Fokker-Planck Model for Transport of Collimated Beams

    SciTech Connect (OSTI)

    Prinja, Anil K.; Pomraning, G.C.

    2001-03-15

    A generalized Fokker-Planck (GFP) model is introduced for application to the problem of the angular spreading of a broad beam of charged particles. This approach extends the classic Fokker-Planck (FP) approximation of the scattering operator to instances when the differential scattering cross section is not sufficiently forward peaked for the strict FP representation to be valid. Our previously developed (1 - {mu}){sup n}-moments method is used to construct a truncated hierarchy of moment equations from the GFP and transport equations. For slab thicknesses that are small compared to the transport mean-free-path, the scalar flux is explicitly represented as a Taylor expansion in the depth variable for different truncation orders and for different orders of the generalized Fokker-Planck expansion. Numerical results indicate that the GFP method is a viable method for dealing with larger scattering angles than are possible with the classic FP approximation.

  16. Multi-fluid transport code modeling of time-dependent recycling in ELMy H-mode

    SciTech Connect (OSTI)

    Pigarov, A. Yu.; Krasheninnikov, S. I.; Rognlien, T. D.; Hollmann, E. M.; Lasnier, C. J.; Unterberg, Ezekial A

    2014-01-01

    Simulations of a high-confinement-mode (H-mode) tokamak discharge with infrequent giant type-I ELMs are performed by the multi-fluid, multi-species, two-dimensional transport code UEDGE-MB, which incorporates the Macro-Blob approach for intermittent non-diffusive transport due to filamentary coherent structures observed during the Edge Localized Modes (ELMs) and simple time-dependent multi-parametric models for cross-field plasma transport coefficients and working gas inventory in material surfaces. Temporal evolutions of pedestal plasma profiles, divertor recycling, and wall inventory in a sequence of ELMs are studied and compared to the experimental time-dependent data. Short- and long-time-scale variations of the pedestal and divertor plasmas where the ELM is described as a sequence of macro-blobs are discussed. It is shown that the ELM recovery includes the phase of relatively dense and cold post-ELM divertor plasma evolving on a several ms scale, which is set by the transport properties of H-mode barrier. The global gas balance in the discharge is also analyzed. The calculated rates of working gas deposition during each ELM and wall outgassing between ELMs are compared to the ELM particle losses from the pedestal and neutral-beam-injection fueling rate, correspondingly. A sensitivity study of the pedestal and divertor plasmas to model assumptions for gas deposition and release on material surfaces is presented. The performed simulations show that the dynamics of pedestal particle inventory is dominated by the transient intense gas deposition into the wall during each ELM followed by continuous gas release between ELMs at roughly a constant rate.

  17. Multi-fluid transport code modeling of time-dependent recycling in ELMy H-mode

    SciTech Connect (OSTI)

    Pigarov, A. Yu.; Krasheninnikov, S. I.; Hollmann, E. M.; Rognlien, T. D.; Lasnier, C. J.; Unterberg, E.

    2014-06-15

    Simulations of a high-confinement-mode (H-mode) tokamak discharge with infrequent giant type-I ELMs are performed by the multi-fluid, multi-species, two-dimensional transport code UEDGE-MB, which incorporates the Macro-Blob approach for intermittent non-diffusive transport due to filamentary coherent structures observed during the Edge Localized Modes (ELMs) and simple time-dependent multi-parametric models for cross-field plasma transport coefficients and working gas inventory in material surfaces. Temporal evolutions of pedestal plasma profiles, divertor recycling, and wall inventory in a sequence of ELMs are studied and compared to the experimental time-dependent data. Short- and long-time-scale variations of the pedestal and divertor plasmas where the ELM is described as a sequence of macro-blobs are discussed. It is shown that the ELM recovery includes the phase of relatively dense and cold post-ELM divertor plasma evolving on a several ms scale, which is set by the transport properties of H-mode barrier. The global gas balance in the discharge is also analyzed. The calculated rates of working gas deposition during each ELM and wall outgassing between ELMs are compared to the ELM particle losses from the pedestal and neutral-beam-injection fueling rate, correspondingly. A sensitivity study of the pedestal and divertor plasmas to model assumptions for gas deposition and release on material surfaces is presented. The performed simulations show that the dynamics of pedestal particle inventory is dominated by the transient intense gas deposition into the wall during each ELM followed by continuous gas release between ELMs at roughly a constant rate.

  18. A hybrid transport-diffusion model for radiative transfer in absorbing and scattering media

    SciTech Connect (OSTI)

    Roger, M.; Caliot, C.; Crouseilles, N.; Coelho, P.J.

    2014-10-15

    A new multi-scale hybrid transport-diffusion model for radiative transfer is proposed in order to improve the efficiency of the calculations close to the diffusive regime, in absorbing and strongly scattering media. In this model, the radiative intensity is decomposed into a macroscopic component calculated by the diffusion equation, and a mesoscopic component. The transport equation for the mesoscopic component allows to correct the estimation of the diffusion equation, and then to obtain the solution of the linear radiative transfer equation. In this work, results are presented for stationary and transient radiative transfer cases, in examples which concern solar concentrated and optical tomography applications. The Monte Carlo and the discrete-ordinate methods are used to solve the mesoscopic equation. It is shown that the multi-scale model allows to improve the efficiency of the calculations when the medium is close to the diffusive regime. The proposed model is a good alternative for radiative transfer at the intermediate regime where the macroscopic diffusion equation is not accurate enough and the radiative transfer equation requires too much computational effort.

  19. Monte Carlo modeling of transport in PbSe nanocrystal films

    SciTech Connect (OSTI)

    Carbone, I. Carter, S. A.; Zimanyi, G. T.

    2013-11-21

    A Monte Carlo hopping model was developed to simulate electron and hole transport in nanocrystalline PbSe films. Transport is carried out as a series of thermally activated hopping events between neighboring sites on a cubic lattice. Each site, representing an individual nanocrystal, is assigned a size-dependent electronic structure, and the effects of particle size, charging, interparticle coupling, and energetic disorder on electron and hole mobilities were investigated. Results of simulated field-effect measurements confirm that electron mobilities and conductivities at constant carrier densities increase with particle diameter by an order of magnitude up to 5?nm and begin to decrease above 6?nm. We find that as particle size increases, fewer hops are required to traverse the same distance and that site energy disorder significantly inhibits transport in films composed of smaller nanoparticles. The dip in mobilities and conductivities at larger particle sizes can be explained by a decrease in tunneling amplitudes and by charging penalties that are incurred more frequently when carriers are confined to fewer, larger nanoparticles. Using a nearly identical set of parameter values as the electron simulations, hole mobility simulations confirm measurements that increase monotonically with particle size over two orders of magnitude.

  20. An approximate framework for quantum transport calculation with model order reduction

    SciTech Connect (OSTI)

    Chen, Quan; Li, Jun; Yam, Chiyung; Zhang, Yu; Wong, Ngai; Chen, Guanhua

    2015-04-01

    A new approximate computational framework is proposed for computing the non-equilibrium charge density in the context of the non-equilibrium Green's function (NEGF) method for quantum mechanical transport problems. The framework consists of a new formulation, called the X-formulation, for single-energy density calculation based on the solution of sparse linear systems, and a projection-based nonlinear model order reduction (MOR) approach to address the large number of energy points required for large applied biases. The advantages of the new methods are confirmed by numerical experiments.

  1. Mesoscopic modeling of multi-physicochemical transport phenomena in porous media

    SciTech Connect (OSTI)

    Kang, Qinjin; Wang, Moran; Mukherjee, Partha P; Lichtner, Peter C

    2009-01-01

    We present our recent progress on mesoscopic modeling of multi-physicochemical transport phenomena in porous media based on the lattice Boltzmann method. Simulation examples include injection of CO{sub 2} saturated brine into a limestone rock, two-phase behavior and flooding phenomena in polymer electrolyte fuel cells, and electroosmosis in homogeneously charged porous media. It is shown that the lattice Boltzmann method can account for multiple, coupled physicochemical processes in these systems and can shed some light on the underlying physics occuning at the fundamental scale. Therefore, it can be a potential powerful numerical tool to analyze multi-physicochemical processes in various energy, earth, and environmental systems.

  2. A New Correlation ECE Diagnostic for C-Mod and Progress on Transport Model

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Validation | Princeton Plasma Physics Lab August 5, 2013, 2:00pm to 3:30pm Colloquia MBG Auditorium A New Correlation ECE Diagnostic for C-Mod and Progress on Transport Model Validation Professor Anne White Massachusetts Institute of Technology Presentation: PDF icon COLL.08.05.13A.pdf CMOD Update Professor Anne White *** PLEASE NOTE SPECIAL DATE AND TIME *** Monday, August 5, 2013, 2:00pm to 3:30pm Colloquium Committee: The Princeton Plasma Physics Laboratory 2016-2017 Colloquium Committee

  3. Constraint-Based Routing Models for the Transport of Radioactive Materials

    SciTech Connect (OSTI)

    Peterson, Steven K

    2015-01-01

    The Department of Energy (DOE) has a historic programmatic interest in the safe and secure routing, tracking, and transportation risk analysis of radiological materials in the United States. In order to address these program goals, DOE has funded the development of several tools and related systems designed to provide insight to planners and other professionals handling radioactive materials shipments. These systems include the WebTRAGIS (Transportation Routing Analysis Geographic Information System) platform. WebTRAGIS is a browser-based routing application developed at Oak Ridge National Laboratory (ORNL) focused primarily on the safe transport of spent nuclear fuel from US nuclear reactors via railway, highway, or waterway. It is also used for the transport planning of low-level radiological waste to depositories such as the Waste Isolation Pilot Plant (WIPP) facility. One particular feature of WebTRAGIS is its coupling with high-resolution population data from ORNL s LandScan project. This allows users to obtain highly accurate population count and density information for use in route planning and risk analysis. To perform the routing and risk analysis WebTRAGIS incorporates a basic routing model methodology, with the additional application of various constraints designed to mimic US Department of Transportation (DOT), DOE, and Nuclear Regulatory Commission (NRC) regulations. Aside from the routing models available in WebTRAGIS, the system relies on detailed or specialized modal networks for the route solutions. These include a highly detailed network model of the US railroad system, the inland and coastal waterways, and a specialized highway network that focuses on the US interstate system and the designated hazardous materials and Highway Route Controlled Quantity (HRCQ) -designated roadways. The route constraints in WebTRAGIS rely upon a series of attributes assigned to the various components of the different modal networks. Routes are determined via a

  4. Modeling

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Though adequate for modeling mean transport, this approach does not address ... Microphysics such as diffusive transport and chemical kinetics are represented by ...

  5. Applying GIS characterizing and modeling contaminant transport in surface water at Los Alamos National Laboratory

    SciTech Connect (OSTI)

    Becker, N.M.; Van Eeckhout, E.; David, N.A.; Irvine, J.M.

    1995-10-01

    During World War II, Los Alamos, New Mexico was chosen as the site for the secret development of the first atomic bomb. The remote location in the southwestern United States was ideal for such a project. After the war, research activities continued at the Los Alamos installation, focusing on new nuclear weapons models as well as greater effectiveness and reliability of existing weapons. Due to the emphasis on nuclear and non-nuclear weapons development as well as associated nuclear research, a large inventory of radionuclides and heavy metals have been tested, expended, and disposed of in the local environment, a high plateau of tuffaceous volcanic rocks incised by deep canyons in a semi-arid climate. In recent years an intensive evaluation of the environmental, impact of weapons testing at Los Alamos and elsewhere has been undertaken. GIS system utilization and image processing of past and current data has been an important part of this evaluation. Important problems can be more easily displayed and understood using this methodology. The main objective in this paper is to illustrate how transport of depleted uranium and associated heavy metals (copper in this case) used in dynamic testing of weapons components at open air firing sites can be evaluated and visualized. In our studies, surface water has been found to be the predominant transport mechanism. We have sampled soils, sediments, fallout, runoff water and snowmelt over a number of years in order to understand contaminant transport on- and offsite. Statistical analyses of these data have assisted in our characterization of issues such as contaminant variability, spatially and temporally, as well as in development of transport rates.

  6. Evaluation of the accuracy of an offline seasonally-varying matrix transport model for simulating ideal age

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bardin, Ann; Primeau, Francois; Lindsay, Keith; Bradley, Andrew

    2016-07-21

    Newton-Krylov solvers for ocean tracers have the potential to greatly decrease the computational costs of spinning up deep-ocean tracers, which can take several thousand model years to reach equilibrium with surface processes. One version of the algorithm uses offline tracer transport matrices to simulate an annual cycle of tracer concentrations and applies Newton’s method to find concentrations that are periodic in time. Here we present the impact of time-averaging the transport matrices on the equilibrium values of an ideal-age tracer. We compared annually-averaged, monthly-averaged, and 5-day-averaged transport matrices to an online simulation using the ocean component of the Community Earthmore » System Model (CESM) with a nominal horizontal resolution of 1° × 1° and 60 vertical levels. We found that increasing the time resolution of the offline transport model reduced a low age bias from 12% for the annually-averaged transport matrices, to 4% for the monthly-averaged transport matrices, and to less than 2% for the transport matrices constructed from 5-day averages. The largest differences were in areas with strong seasonal changes in the circulation, such as the Northern Indian Ocean. As a result, for many applications the relatively small bias obtained using the offline model makes the offline approach attractive because it uses significantly less computer resources and is simpler to set up and run.« less

  7. Development of a Hydrodynamic and Transport model of Bellingham Bay in Support of Nearshore Habitat Restoration

    SciTech Connect (OSTI)

    Wang, Taiping; Yang, Zhaoqing; Khangaonkar, Tarang

    2010-04-22

    In this study, a hydrodynamic model based on the unstructured-grid finite volume coastal ocean model (FVCOM) was developed for Bellingham Bay, Washington. The model simulates water surface elevation, velocity, temperature, and salinity in a three-dimensional domain that covers the entire Bellingham Bay and adjacent water bodies, including Lummi Bay, Samish Bay, Padilla Bay, and Rosario Strait. The model was developed using Pacific Northwest National Laboratorys high-resolution Puget Sound and Northwest Straits circulation and transport model. A sub-model grid for Bellingham Bay and adjacent coastal waters was extracted from the Puget Sound model and refined in Bellingham Bay using bathymetric light detection and ranging (LIDAR) and river channel cross-section data. The model uses tides, river inflows, and meteorological inputs to predict water surface elevations, currents, salinity, and temperature. A tidal open boundary condition was specified using standard National Oceanic and Atmospheric Administration (NOAA) predictions. Temperature and salinity open boundary conditions were specified based on observed data. Meteorological forcing (wind, solar radiation, and net surface heat flux) was obtained from NOAA real observations and National Center for Environmental Prediction North American Regional Analysis outputs. The model was run in parallel with 48 cores using a time step of 2.5 seconds. It took 18 hours of cpu time to complete 26 days of simulation. The model was calibrated with oceanographic field data for the period of 6/1/2009 to 6/26/2009. These data were collected specifically for the purpose of model development and calibration. They include time series of water-surface elevation, currents, temperature, and salinity as well as temperature and salinity profiles during instrument deployment and retrieval. Comparisons between model predictions and field observations show an overall reasonable agreement in both temporal and spatial scales. Comparisons of

  8. Evaluating temperature and fuel stratification for heat-release rate control in a reactivity-controlled compression-ignition engine using optical diagnostics and chemical kinetics modeling

    SciTech Connect (OSTI)

    Musculus, Mark P. B.; Kokjohn, Sage L.; Reitz, Rolf D.

    2015-04-23

    We investigated the combustion process in a dual-fuel, reactivity-controlled compression-ignition (RCCI) engine using a combination of optical diagnostics and chemical kinetics modeling to explain the role of equivalence ratio, temperature, and fuel reactivity stratification for heat-release rate control. An optically accessible engine is operated in the RCCI combustion mode using gasoline primary reference fuels (PRF). A well-mixed charge of iso-octane (PRF = 100) is created by injecting fuel into the engine cylinder during the intake stroke using a gasoline-type direct injector. Later in the cycle, n-heptane (PRF = 0) is delivered through a centrally mounted diesel-type common-rail injector. This injection strategy generates stratification in equivalence ratio, fuel blend, and temperature. The first part of this study uses a high-speed camera to image the injection events and record high-temperature combustion chemiluminescence. Moreover, the chemiluminescence imaging showed that, at the operating condition studied in the present work, mixtures in the squish region ignite first, and the reaction zone proceeds inward toward the center of the combustion chamber. The second part of this study investigates the charge preparation of the RCCI strategy using planar laser-induced fluorescence (PLIF) of a fuel tracer under non-reacting conditions to quantify fuel concentration distributions prior to ignition. The fuel-tracer PLIF data show that the combustion event proceeds down gradients in the n-heptane distribution. The third part of the study uses chemical kinetics modeling over a range of mixtures spanning the distributions observed from the fuel-tracer fluorescence imaging to isolate the roles of temperature, equivalence ratio, and PRF number stratification. The simulations predict that PRF number stratification is the dominant factor controlling the ignition location and growth rate of the reaction zone. Equivalence ratio has a smaller, but still significant

  9. System for reactivating catalysts

    DOE Patents [OSTI]

    Ginosar, Daniel M.; Thompson, David N.; Anderson, Raymond P.

    2010-03-02

    A method of reactivating a catalyst, such as a solid catalyst or a liquid catalyst is provided. The method comprises providing a catalyst that is at least partially deactivated by fouling agents. The catalyst is contacted with a fluid reactivating agent that is at or above a critical point of the fluid reactivating agent and is of sufficient density to dissolve impurities. The fluid reactivating agent reacts with at least one fouling agent, releasing the at least one fouling agent from the catalyst. The at least one fouling agent becomes dissolved in the fluid reactivating agent and is subsequently separated or removed from the fluid reactivating agent so that the fluid reactivating agent may be reused. A system for reactivating a catalyst is also disclosed.

  10. Permeable Reactive Barriers

    Broader source: Energy.gov [DOE]

    A permeable reactive barrier (PRB) is a zone of reactive material placed underground to intercept and react with a contaminant plume in ground water. Typically, PRBs are emplaced by replacing soils...

  11. A simple stochastic quadrant model for the transport and deposition of particles in turbulent boundary layers

    SciTech Connect (OSTI)

    Jin, C.; Potts, I.; Reeks, M. W.

    2015-05-15

    We present a simple stochastic quadrant model for calculating the transport and deposition of heavy particles in a fully developed turbulent boundary layer based on the statistics of wall-normal fluid velocity fluctuations obtained from a fully developed channel flow. Individual particles are tracked through the boundary layer via their interactions with a succession of random eddies found in each of the quadrants of the fluid Reynolds shear stress domain in a homogeneous Markov chain process. In this way, we are able to account directly for the influence of ejection and sweeping events as others have done but without resorting to the use of adjustable parameters. Deposition rate predictions for a wide range of heavy particles predicted by the model compare well with benchmark experimental measurements. In addition, deposition rates are compared with those obtained from continuous random walk models and Langevin equation based ejection and sweep models which noticeably give significantly lower deposition rates. Various statistics related to the particle near wall behavior are also presented. Finally, we consider the model limitations in using the model to calculate deposition in more complex flows where the near wall turbulence may be significantly different.

  12. Transportation Sector Model of the National Energy Modeling System. Volume 2 -- Appendices: Part 3

    SciTech Connect (OSTI)

    1998-01-01

    This Appendix consists of two unpublished reports produced by Energy and Environmental Analysis, Inc., under contract to Oak Ridge National Laboratory. These two reports formed the basis for the subsequent development of the Fuel Economy Model described in Volume 1. They are included in order to document more completely the efforts undertaken to construct a comprehensive model of automobile fuel economy. The supplemental reports are as follows: Supplement 1--Documentation Attributes of Technologies to Improve Automotive Fuel Economy; Supplement 2--Analysis of the Fuel Economy Boundary for 2010 and Comparison to Prototypes.

  13. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model

    SciTech Connect (OSTI)

    K. Rehfeldt

    2004-10-08

    This report is an updated analysis of water-level data performed to provide the ''Saturated Zone Site-Scale Flow Model'' (BSC 2004 [DIRS 170037]) (referred to as the saturated zone (SZ) site-scale flow model or site-scale SZ flow model in this report) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for calibration of groundwater flow models. This report also contains an expanded discussion of uncertainty in the potentiometric-surface map. The analysis of the potentiometric data presented in Revision 00 of this report (USGS 2001 [DIRS 154625]) provides the configuration of the potentiometric surface, target heads, and hydraulic gradients for the calibration of the SZ site-scale flow model (BSC 2004 [DIRS 170037]). Revision 01 of this report (USGS 2004 [DIRS 168473]) used updated water-level data for selected wells through the year 2000 as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain based on an alternative interpretation of perched water conditions. That revision developed computer files containing: Water-level data within the model area (DTN: GS010908312332.002); A table of known vertical head differences (DTN: GS010908312332.003); and A potentiometric-surface map (DTN: GS010608312332.001) using an alternative concept from that presented by USGS (2001 [DIRS 154625]) for the area north of Yucca Mountain. The updated water-level data presented in USGS (2004 [DIRS 168473]) include data obtained from the Nye County Early Warning Drilling Program (EWDP) Phases I and II and data from Borehole USW WT-24. This document is based on Revision 01 (USGS 2004 [DIRS 168473]) and expands the discussion of uncertainty in the potentiometric-surface map. This uncertainty assessment includes an analysis of the impact of more recent water-level data and the impact of adding data from the EWDP Phases III and IV wells. In addition to being utilized

  14. Uranium Fate and Transport Modeling, Guterl Specialty Steel Site, New York - 13545

    SciTech Connect (OSTI)

    Frederick, Bill; Tandon, Vikas

    2013-07-01

    The Former Guterl Specialty Steel Corporation Site (Guterl Site) is located 32 kilometers (20 miles) northeast of Buffalo, New York, in Lockport, Niagara County, New York. Between 1948 and 1952, up to 15,875 metric tons (35 million pounds) of natural uranium metal (U) were processed at the former Guterl Specialty Steel Corporation site in Lockport, New York. The resulting dust, thermal scale, mill shavings and associated land disposal contaminated both the facility and on-site soils. Uranium subsequently impacted groundwater and a fully developed plume exists below the site. Uranium transport from the site involves legacy on-site pickling fluid handling, the leaching of uranium from soil to groundwater, and the groundwater transport of dissolved uranium to the Erie Canal. Groundwater fate and transport modeling was performed to assess the transfer of dissolved uranium from the contaminated soils and buildings to groundwater and subsequently to the nearby Erie Canal. The modeling provides a tool to determine if the uranium contamination could potentially affect human receptors in the vicinity of the site. Groundwater underlying the site and in the surrounding area generally flows southeasterly towards the Erie Canal; locally, groundwater is not used as a drinking water resource. The risk to human health was evaluated outside the Guterl Site boundary from the possibility of impacted groundwater discharging to and mixing with the Erie Canal waters. This condition was evaluated because canal water is infrequently used as an emergency water supply for the City of Lockport via an intake located approximately 122 meters (m) (400 feet [ft]) southeast of the Guterl Site. Modeling was performed to assess whether mixing of groundwater with surface water in the Erie Canal could result in levels of uranium exceeding the U.S. Environmental Protection Agency (USEPA) established drinking water standard for total uranium; the Maximum Concentration Limit (MCL). Geotechnical test

  15. Urban airshed modeling of air quality impacts of alternative transportation fuel use in Los Angeles and Atlanta

    SciTech Connect (OSTI)

    NONE

    1997-12-01

    The main objective of NREL in supporting this study is to determine the relative air quality impact of the use of compressed natural gas (CNG) as an alternative transportation fuel when compared to low Reid vapor pressure (RVP) gasoline and reformulated gasoline (RFG). A table lists the criteria, air toxic, and greenhouse gas pollutants for which emissions were estimated for the alternative fuel scenarios. Air quality impacts were then estimated by performing photochemical modeling of the alternative fuel scenarios using the Urban Airshed Model Version 6.21 and the Carbon Bond Mechanism Version IV (CBM-IV) (Geary et al., 1988) Using this model, the authors examined the formation and transport of ozone under alternative fuel strategies for motor vehicle transportation sources for the year 2007. Photochemical modeling was performed for modeling domains in Los Angeles, California, and Atlanta, Georgia.

  16. Mesoscale Phase-Field Modeling of Charge Transport in Nanocomposite Electrodes for Lithium-ion Batteries

    SciTech Connect (OSTI)

    Hu, Shenyang Y.; Li, Yulan; Rosso, Kevin M.; Sushko, Maria L.

    2013-01-10

    A phase-field model is developed to investigate the influence of microstructure, thermodynamic and kinetic properties, and charging conditions on charged particle transport in nanocomposite electrodes. Two sets of field variables are used to describe the microstructure. One is comprised of the order parameters describing size, orientation and spatial distributions of nanoparticles, and the other is comprised of the concentrations of mobile species. A porous nanoparticle microstructure filled with electrolyte is taken as a model system to test the phase-field model. Inhomogeneous and anisotropic dielectric constants and mobilities of charged particles, and stresses associated with lattice deformation due to Li-ion insertion/extraction are considered in the model. Iteration methods are used to find the elastic and electric fields in an elastically and electrically inhomogeneous medium. The results demonstrate that the model is capable of predicting charge separation associated with the formation of a double layer at the electrochemical interface between solid and electrolyte, and the effect of microstructure, inhomogeneous and anisotropic thermodynamic and kinetic properties, charge rates, and stresses on voltage versus current density and capacity during charging and discharging.

  17. Transport-reaction model for defect and carrier behavior within displacement cascades in gallium arsenide

    SciTech Connect (OSTI)

    Wampler, William R.; Myers, Samuel M.

    2014-02-01

    A model is presented for recombination of charge carriers at displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers and defects within a representative spherically symmetric cluster. The initial radial defect profiles within the cluster were chosen through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Charging of the defects can produce high electric fields within the cluster which may influence transport and reaction of carriers and defects, and which may enhance carrier recombination through band-to-trap tunneling. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to pulsed neutron irradiation.

  18. Final report on LDRD project: A phenomenological model for multicomponent transport with simultaneous electrochemical reactions in concentrated solutions

    SciTech Connect (OSTI)

    CHEN,KEN S.; EVANS,GREGORY H.; LARSON,RICHARD S.; NOBLE,DAVID R.; HOUF,WILLIAM G.

    2000-01-01

    A phenomenological model was developed for multicomponent transport of charged species with simultaneous electrochemical reactions in concentrated solutions, and was applied to model processes in a thermal battery cell. A new general framework was formulated and implemented in GOMA (a multidimensional, multiphysics, finite-element computer code developed and being enhanced at Sandia) for modeling multidimensional, multicomponent transport of neutral and charged species in concentrated solutions. The new framework utilizes the Stefan-Maxwell equations that describe multicomponent diffusion of interacting species using composition-insensitive binary diffusion coefficients. The new GOMA capability for modeling multicomponent transport of neutral species was verified and validated using the model problem of ternary gaseous diffusion in a Stefan tube. The new GOMA-based thermal battery computer model was verified using an idealized battery cell in which concentration gradients are absent; the full model was verified by comparing with that of Bernardi and Newman (1987) and validated using limited thermal battery discharge-performance data from the open literature (Dunning 1981) and from Sandia (Guidotti 1996). Moreover, a new Liquid Chemkin Software Package was developed, which allows the user to handle manly aspects of liquid-phase kinetics, thermodynamics, and transport (particularly in terms of computing properties). Lastly, a Lattice-Boltzmann-based capability was developed for modeling pore- or micro-scale phenomena involving convection, diffusion, and simplified chemistry; this capability was demonstrated by modeling phenomena in the cathode region of a thermal battery cell.

  19. Three-dimensional transport and concentration of SF{sub 6} - a model intercomparison study (transcom 2)

    SciTech Connect (OSTI)

    Denning, A.S.; Holzer, M.; Burney, K.R.; Heimann, M.; Law, R.M.; Rayner, P.J.; Fund, I.Y.; Fan, S.M.; Taguchi, S.; Friedlingstein, P.; Balkanski, Y.; Taylor, J.; Maiss, M.; Levin, I.

    1999-01-02

    Sulfur hexafluoride (SF6) is an excellent tracer of large-scale atmospheric transport, because it has slowly increasing sources mostly confined to northern midlatitudes, and has a lifetime of thousands of years. We have simulated the emissions, transport, and concentration of SF, for a 5-year period, and compared the results with atmospheric observations. In addition, we have performed an intercomparison of interhemispheric transport among 11 models to investigate the reasons for the differences among the simulations. Most of the models are reasonably successful at simulating the observed meridional gradient of SF6 in the remote marine boundary layer, though there is less agreement at continental sites. Models that compare well to observations in the remote marine boundary layer tend to systematically overestimate SF6 at continental locations in source regions, suggesting that vertical trapping rather than meridional transport may be a dominant control on the simulated meridional gradient. The vertical structure of simulated SF6 in the models supports this interpretation. Some of the models perform quite well in terms of the simulated seasonal cycle at remote locations, while others do not. Interhemispheric exchange time varies by a factor of 2 when estimated from 1-dimensional meridional profiles at the surface, as has been done for observations. The agreement among models is better when the global surface mean mole fraction is used, and better still when the full 3-dimensional mean mixing ratio is used. The ranking of the interhemispheric exchange time among the models is not sensitive to the change From station values to surface means, but is very sensitive to the change from surface means to the full 3-dimensional tracer fields. This strengthens the argument that vertical redistribution dominates over interhemispheric transport in determining the meridional gradient at the surface. Vertically integrated meridional transport in the models is divided roughly

  20. Non-equilibrium STLS approach to transport properties of single impurity Anderson model

    SciTech Connect (OSTI)

    Rezai, Raheleh Ebrahimi, Farshad

    2014-04-15

    In this work, using the non-equilibrium Keldysh formalism, we study the effects of the electronelectron interaction and the electron-spin correlation on the non-equilibrium Kondo effect and the transport properties of the symmetric single impurity Anderson model (SIAM) at zero temperature by generalizing the self-consistent method of Singwi, Tosi, Land, and Sjolander (STLS) for a single-band tight-binding model with Hubbard type interaction to out of equilibrium steady-states. We at first determine in a self-consistent manner the non-equilibrium spin correlation function, the effective Hubbard interaction, and the double-occupancy at the impurity site. Then, using the non-equilibrium STLS spin polarization function in the non-equilibrium formalism of the iterative perturbation theory (IPT) of Yosida and Yamada, and Horvatic and Zlatic, we compute the spectral density, the currentvoltage characteristics and the differential conductance as functions of the applied bias and the strength of on-site Hubbard interaction. We compare our spectral densities at zero bias with the results of numerical renormalization group (NRG) and depict the effects of the electronelectron interaction and electron-spin correlation at the impurity site on the aforementioned properties by comparing our numerical result with the order U{sup 2} IPT. Finally, we show that the obtained numerical results on the differential conductance have a quadratic universal scaling behavior and the resulting Kondo temperature shows an exponential behavior. -- Highlights: We introduce for the first time the non-equilibrium method of STLS for Hubbard type models. We determine the transport properties of SIAM using the non-equilibrium STLS method. We compare our results with order-U2 IPT and NRG. We show that non-equilibrium STLS, contrary to the GW and self-consistent RPA, produces the two Hubbard peaks in DOS. We show that the method keeps the universal scaling behavior and correct exponential behavior

  1. ACCELERATION OF LOW-ENERGY IONS AT PARALLEL SHOCKS WITH A FOCUSED TRANSPORT MODEL

    SciTech Connect (OSTI)

    Zuo, Pingbing; Zhang, Ming; Rassoul, Hamid K.

    2013-04-10

    We present a test particle simulation on the injection and acceleration of low-energy suprathermal particles by parallel shocks with a focused transport model. The focused transport equation contains all necessary physics of shock acceleration, but avoids the limitation of diffusive shock acceleration (DSA) that requires a small pitch angle anisotropy. This simulation verifies that the particles with speeds of a fraction of to a few times the shock speed can indeed be directly injected and accelerated into the DSA regime by parallel shocks. At higher energies starting from a few times the shock speed, the energy spectrum of accelerated particles is a power law with the same spectral index as the solution of standard DSA theory, although the particles are highly anisotropic in the upstream region. The intensity, however, is different from that predicted by DSA theory, indicating a different level of injection efficiency. It is found that the shock strength, the injection speed, and the intensity of an electric cross-shock potential (CSP) jump can affect the injection efficiency of the low-energy particles. A stronger shock has a higher injection efficiency. In addition, if the speed of injected particles is above a few times the shock speed, the produced power-law spectrum is consistent with the prediction of standard DSA theory in both its intensity and spectrum index with an injection efficiency of 1. CSP can increase the injection efficiency through direct particle reflection back upstream, but it has little effect on the energetic particle acceleration once the speed of injected particles is beyond a few times the shock speed. This test particle simulation proves that the focused transport theory is an extension of DSA theory with the capability of predicting the efficiency of particle injection.

  2. Biomass particle models with realistic morphology and resolved microstructure for simulations of intraparticle transport phenomena

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ciesielski, Peter N.; Crowley, Michael F.; Nimlos, Mark R.; Sanders, Aric W.; Wiggins, Gavin M.; Robichaud, David; Donohoe, Bryon S.; Foust, Thomas D.

    2014-12-09

    Biomass exhibits a complex microstructure of directional pores that impact how heat and mass are transferred within biomass particles during conversion processes. However, models of biomass particles used in simulations of conversion processes typically employ oversimplified geometries such as spheres and cylinders and neglect intraparticle microstructure. In this study, we develop 3D models of biomass particles with size, morphology, and microstructure based on parameters obtained from quantitative image analysis. We obtain measurements of particle size and morphology by analyzing large ensembles of particles that result from typical size reduction methods, and we delineate several representative size classes. Microstructural parameters, includingmore » cell wall thickness and cell lumen dimensions, are measured directly from micrographs of sectioned biomass. A general constructive solid geometry algorithm is presented that produces models of biomass particles based on these measurements. Next, we employ the parameters obtained from image analysis to construct models of three different particle size classes from two different feedstocks representing a hardwood poplar species (Populus tremuloides, quaking aspen) and a softwood pine (Pinus taeda, loblolly pine). Finally, we demonstrate the utility of the models and the effects explicit microstructure by performing finite-element simulations of intraparticle heat and mass transfer, and the results are compared to similar simulations using traditional simplified geometries. In conclusion, we show how the behavior of particle models with more realistic morphology and explicit microstructure departs from that of spherical models in simulations of transport phenomena and that species-dependent differences in microstructure impact simulation results in some cases.« less

  3. Re-evaluation of a subsurface injection experiment for testing flow and transport models

    SciTech Connect (OSTI)

    Fayer, M.J.; Lewis, R.E.; Engelman, R.E.; Pearson, A.L.; Murray, C.J.; Smoot, J.L. Lu, A.H.; Randall, P.R.; Wegener, W.H.

    1995-12-01

    The current preferred method for disposal of low-level radioactive waste (LLW) at the Hanford Site is to vitrify the wastes so they can be stored in a near-surface, shallow-land burial facility (Shord 1995). Pacific Northwest Laboratory (PNL) managed the PNL Vitrification Technology Development (PVTD) Project to assist Westinghouse Hanford Company (WHC) in designing and assessing the performance of a disposal facility for the vitrified LLW. Vadose zone flow and transport models are recognized as necessary tools for baseline risk assessments of stored waste forms. The objective of the Controlled Field Testing task of the PVTD Project is to perform and analyze field experiments to demonstrate the appropriateness of conceptual models for the performance assessment. The most convincing way to demonstrate appropriateness is to show that the model can reproduce the movement of water and contaminants in the field. Before expensive new experiments are initiated, an injection experiment conducted at the Hanford Site in 1980 (designated the ``Sisson and the Lu experiment``) should be completely analyzed and understood. Briefly, in that test, a solution containing multiple tracers was injected at a single point into the subsurface sediments. The resulting spread of the water and tracers was monitored in wells surrounding the injection point. Given the advances in knowledge, computational capabilities, and models over the last 15 years, it is important to re-analyze the data before proceeding to other experiments and history-matching exercises.

  4. GRIZZLY Model of Multi-Reactive Species Diffusion, Moisture/Heat Transfer and Alkali-Silica Reaction for Simulating Concrete Aging and Degradation

    SciTech Connect (OSTI)

    Huang, Hai; Spencer, Benjamin W.; Cai, Guowei

    2015-09-01

    Concrete is widely used in the construction of nuclear facilities because of its structural strength and its ability to shield radiation. The use of concrete in nuclear power plants for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. As such, when life extension is considered for nuclear power plants, it is critical to have accurate and reliable predictive tools to address concerns related to various aging processes of concrete structures and the capacity of structures subjected to age-related degradation. The goal of this report is to document the progress of the development and implementation of a fully coupled thermo-hydro-mechanical-chemical model in GRIZZLY code with the ultimate goal to reliably simulate and predict long-term performance and response of aged NPP concrete structures subjected to a number of aging mechanisms including external chemical attacks and volume-changing chemical reactions within concrete structures induced by alkali-silica reactions and long-term exposure to irradiation. Based on a number of survey reports of concrete aging mechanisms relevant to nuclear power plants and recommendations from researchers in concrete community, we’ve implemented three modules during FY15 in GRIZZLY code, (1) multi-species reactive diffusion model within cement materials; (2) coupled moisture and heat transfer model in concrete; and (3) anisotropic, stress-dependent, alkali-silica reaction induced swelling model. The multi-species reactive diffusion model was implemented with the objective to model aging of concrete structures subjected to aggressive external chemical attacks (e.g., chloride attack, sulfate attack, etc.). It considers multiple processes relevant to external chemical attacks such as diffusion of ions in aqueous phase within pore spaces, equilibrium chemical speciation reactions and kinetic mineral dissolution/precipitation. The moisture

  5. Object Modeling for Transport of Physical Objects or Substances Across a Geograc

    Energy Science and Technology Software Center (OSTI)

    1997-02-12

    TRANSPORTNET, a suite of object classes, addresses the general problem of simulating transport of objects or substances across a geographically distributed network. This highly abstract concept supports subclassed networks of many types, including road, rail, air, and navigation transportation networks, drainage (hydrological) networks, and utility networks of various sorts, such as pipelines, transmission lines, etc. In TRANSPORTNET, transport occurs along transport links which are connected by transport nodes. The concepts of link and node aremore » also highly abstracted and subject to several topological variants (subclasses), subject to the constraint that all transport takes place along links, and links are connected at the nodes.« less

  6. GEOCENTRIFUGE STUDIES OF FLOW AND TRANSPORT IN POROUS MEDIA, FINAL REPORT FOR GRANT NUMBER DE-FG02-03ER63567 TO THE UNIVERSITY OF IDAHO (RW SMITH), ENVIRONMENTAL MANAGEMENT SCIENCE PROGRAM PROJECT NUMBER 86598, COUPLED FLOW AND REACTIVITY IN VARIABLY SATURATED POROUS MEDIA

    SciTech Connect (OSTI)

    Robert W. Smith; Carl D. Palmer; Earl D. Mattson

    2007-06-15

    Improved models of contaminant migration in heterogeneous, variably saturated porous media are required to better define the long-term stewardship requirements for U.S. Department of Energy (DOE) lands and to assist in the design of effective vadose-zone barriers to contaminant migrations. The development of these improved models requires field and laboratory results to evaluate their efficacy. However, controlled laboratory experiments simulating vadose conditions can require extensive period of time, and often are conducted at condition near saturation rather than the much drier conditions common in many contaminated arid vadose zone sites. Collaborative research undertaken by the Idaho National Laboratory (INL) and the University of Idaho as part of this Environmental Management Science Program project focused on the development and evaluation of geocentrifuge techniques and equipment that allows vadose zone experiments to be conducted for relevant conditions in time frames not possible in conventional bench top experiments. A key and novel aspect of the research was the use of the 2-meter radius geocentrifuge capabilities at the Idaho National Laboratory to conduct unsaturated transport experiments. Specifically, the following activities were conducted ** Reviewing of the theory of unsaturated flow in the geocentrifuge to establish the range of centrifuge accelerations/experimental conditions and the translation of centrifuge results to 1 gravity applications. ** Designing, constructing, and testing of in-flight experimental apparatus allowing the replication of traditional bench top unsaturated transport experiments on the geocentrifuge. ** Performing unsaturated 1-dimenstional column geocentrifuge experiments using conservative tracers to evaluate the effects of increased centrifugal acceleration on derived transport properties and assessing the scaling relationships for these properties. Because the application of geocentrifuge techniques to vadose transport

  7. Heavy-quark production in ultrarelativistic heavy-ion collisions within a partonic transport model

    SciTech Connect (OSTI)

    Uphoff, Jan; Fochler, Oliver; Greiner, Carsten; Xu Zhe

    2010-10-15

    The production and space-time evolution of charm and bottom quarks in nucleus-nucleus collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) are investigated with the partonic transport model BAMPS (Boltzmann approach of multiparton scatterings). Heavy quarks, produced in primary hard parton scatterings during nucleon-nucleon collisions, are sampled using the Monte Carlo event generator pythia or the leading-order minijet model in conjunction with the Glauber model, revealing a strong sensitivity on the parton distribution functions, scales, and heavy-quark mass. In a comprehensive study exploring different charm masses, K factors, and possible initial gluon conditions, secondary production and the evolution of heavy quarks are examined within a fully dynamic BAMPS simulation for central heavy-ion collisions at RHIC and LHC. Although charm production in the quark-gluon plasma can be neglected at RHIC, it is significant at LHC but very sensitive to the initial conditions and the charm mass. Bottom production in the quark-gluon plasma, however, is negligible both at RHIC and LHC.

  8. Laboratory And Lysimeter Experimentation And Transport Modeling Of Neptunium And Strontium In Savannah River Site Sediments

    SciTech Connect (OSTI)

    Kaplan, Daniel I.; Powell, B. A.; Miller, Todd J.

    2012-09-24

    existing data sets. The first data set used laboratory generated Np sorption data as a function of concentration (three orders of magnitude) and as a function of pH (four orders of magnitude of proton concentration). In this modeling exercise, a very simple solution was identified by assuming that all sorption occurred only to the iron oxides in the sediment and that all the added NpO{sub 4}{sup -} remained in the oxidized state and was not reduced to the Np(IV) state (as occurs rapidly with Pu(V)). With rather limited input data, very good agreement between experimental and modeling results was observed. This modeling approach would be easy to add to the PA with little additional data requirements. This model would be useful in a system where pH is expected to change greatly, such as directly beneath a grout or concrete structure. The second model discussed in the report was to derive strontium K{sub d} values from data collected in an 11-year-old field transport study. In this controlled lysimeter study, a sensitivity analysis was conducted of hydrological and chemical processes that influence contaminant transport, including diffusion coefficients, seepage velocity, and K{sub d} value. The best overall K{sub d} derived from the model fit to the data was 32 L kg{sup -1}, which was the same value that was previously measured in traditional laboratory batch sorption studies. This was an unexpected result given the differences in experimental conditions between the batch test and the lysimeter flow through test, in particular the differences between strontium adsorption and desorption processes occurring in the latter test and not in the former. There were some trends in the lysimeter strontium data that were not predicted by the K{sub d} model, which suggest that other geochemical processes are likely also controlling strontium transport. Strontium release and cation exchange are being evaluated. These results suggest that future modeling efforts (e.g., PAs) could be

  9. Evaluating temperature and fuel stratification for heat-release rate control in a reactivity-controlled compression-ignition engine using optical diagnostics and chemical kinetics modeling

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Musculus, Mark P. B.; Kokjohn, Sage L.; Reitz, Rolf D.

    2015-04-23

    We investigated the combustion process in a dual-fuel, reactivity-controlled compression-ignition (RCCI) engine using a combination of optical diagnostics and chemical kinetics modeling to explain the role of equivalence ratio, temperature, and fuel reactivity stratification for heat-release rate control. An optically accessible engine is operated in the RCCI combustion mode using gasoline primary reference fuels (PRF). A well-mixed charge of iso-octane (PRF = 100) is created by injecting fuel into the engine cylinder during the intake stroke using a gasoline-type direct injector. Later in the cycle, n-heptane (PRF = 0) is delivered through a centrally mounted diesel-type common-rail injector. This injectionmore » strategy generates stratification in equivalence ratio, fuel blend, and temperature. The first part of this study uses a high-speed camera to image the injection events and record high-temperature combustion chemiluminescence. Moreover, the chemiluminescence imaging showed that, at the operating condition studied in the present work, mixtures in the squish region ignite first, and the reaction zone proceeds inward toward the center of the combustion chamber. The second part of this study investigates the charge preparation of the RCCI strategy using planar laser-induced fluorescence (PLIF) of a fuel tracer under non-reacting conditions to quantify fuel concentration distributions prior to ignition. The fuel-tracer PLIF data show that the combustion event proceeds down gradients in the n-heptane distribution. The third part of the study uses chemical kinetics modeling over a range of mixtures spanning the distributions observed from the fuel-tracer fluorescence imaging to isolate the roles of temperature, equivalence ratio, and PRF number stratification. The simulations predict that PRF number stratification is the dominant factor controlling the ignition location and growth rate of the reaction zone. Equivalence ratio has a smaller, but still

  10. Transportation Secure Data Center: Real-world Data for Planning, Modeling, and Analysis (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2015-01-01

    The Transportation Secure Data Center (TSDC) at www.nrel.gov/tsdc provides free, web-based access to detailed transportation data from a variety of travel surveys conducted across the nation. While preserving the privacy of survey participants, this online repository makes vital transportation data broadly available to users from the comfort of their own desks via a secure online connection.

  11. Application of Maximum Likelihood Bayesian Model Averaging to Groundwater Flow and Transport at the Hanford Site 300 Area

    SciTech Connect (OSTI)

    Meyer, Philip D.; Ye, Ming; Neuman, Shlomo P.; Rockhold, Mark L.

    2008-06-01

    A methodology to systematically and quantitatively assess model predictive uncertainty was applied to saturated zone uranium transport at the 300 Area of the U.S. Department of Energy Hanford Site in Washington State, USA. The methodology extends Maximum Likelihood Bayesian Model Averaging (MLBMA) to account jointly for uncertainties due to the conceptual-mathematical basis of models, model parameters, and the scenarios to which the models are applied. Conceptual uncertainty was represented by postulating four alternative models of hydrogeology and uranium adsorption. Parameter uncertainties were represented by estimation covariances resulting from the joint calibration of each model to observed heads and uranium concentration. Posterior model probability was dominated by one model. Results demonstrated the role of model complexity and fidelity to observed system behavior in determining model probabilities, as well as the impact of prior information. Two scenarios representing alternative future behavior of the Columbia River adjacent to the site were considered. Predictive simulations carried out with the calibrated models illustrated the computation of model- and scenario-averaged predictions and how results can be displayed to clearly indicate the individual contributions to predictive uncertainty of the model, parameter, and scenario uncertainties. The application demonstrated the practicability of applying a comprehensive uncertainty assessment to large-scale, detailed groundwater flow and transport modelling.

  12. Understanding composite explosive energetics: 4. Reactive flow modeling of aluminum reaction kinetics in PETN and TNT using normalized product equation of state

    SciTech Connect (OSTI)

    Tao, W.C.; Tarver, C.M.; Kury, J.W.; Lee, C.G.; Ornellas, D.L.

    1993-07-01

    Using Fabry-Perot interferometry techniques, we have determined the early time rate of energy release from detonating PETN and TNT explosives filled with 5 to 20 wt % of either 5 {mu}m or 18 {mu}m spherical aluminum with the detonation products, and calculate the extent of reaction at 1--3 {mu}s after the detonation. All of the metal in PETN formulations filled with 5 wt % and 10 wt % of either 5 {mu}m or 18 {mu}m aluminum reacted within 1.5 {mu}s, resulting in an increase of 18--22% in energy compared to pure PETN. For TNT formulations, between 5 to 10 wt % aluminum reacts completely with the same timeframe. A reactive flow hydrodynamic code model based on the Zeldovich-von Neumann-Doring (ZND) description of the reaction zone and subsequent reaction product expansion (Taylor wave) is used to address the reaction rate of the aluminum particles with detonation product gases. The detonation product JWL equation of state is derived from that of pure PETN using a parametric normalization methodology.

  13. CHEMICAL TRANSPORT IN A FISSURED BOCK: VERIFICATION OF A NUMERICAL MODEL

    SciTech Connect (OSTI)

    Rasmuson, A.; Narasimhan, T.N.; Neretnieks, I.

    1982-04-01

    Numerical models for simulating chemical transport in fissured rocks constitute powerful tools for evaluating the acceptability of geological nuclear waste repositories. Due to the very long-term, high toxicity of some nuclear waste products, the models are required to predict, in certain cases, the spatial and temporal distribution of chemical concentration less than 0.001% of the concentration released from the repository. Whether numerical models can provide such accuracies is a major question addressed in the present work. To this end, we have verified a numerical model, TRUMP, which solves the advective diffusion equation in general three dimensions with or without decay and source terms. The method is based on an integrated finite-difference approach. The model was verified against known analytic solution of the one-dimensional advection-diffusion problem as well as the problem of advection-diffusion in a system of parallel fractures separated by spherical particles. The studies show that as long as the magnitude of advectance is equal to or less than that of conductance for the closed surface bounding any volume element in the region (that is, numerical Peclet number <2), the numerical method can indeed match the analytic solution within errors of ±10{sup -3} % or less. The realistic input parameters used in the sample calculations suggest that such a range of Peclet numbers is indeed likely to characterize deep groundwater systems in granitic and ancient argillaceous systems. Thus TRUMP in its present form does provide a viable tool for use in nuclear waste evaluation studies. A sensitivity analysis based on the analytic solution suggests that the errors in prediction introduced due to uncertainties in input parameters is likely to be larger than the computational inaccuracies introduced by the numerical model. Currently, a disadvantage in the TRUMP model is that the iterative method of solving the set of simultaneous equations is rather slow when time

  14. Vehicle Technologies Office Merit Review 2015: Transportation Energy Transition Modeling and Analysis: the LAVE-Trans Model

    Broader source: Energy.gov [DOE]

    Presentation given by Oak Ridge National Laboratory at 2015 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about transportation...

  15. Water Transport in PEM Fuel Cells: Advanced Modeling, Material Selection, Testing, and Design Optimization

    Broader source: Energy.gov [DOE]

    This presentation, which focuses on water transport in PEM fuel cells, was given by CFDRC's J. Vernon Cole at a DOE fuel cell meeting in February 2007.

  16. Time-dependent behavior in a transport-barrier model for the...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the dynamics of the L-H transition 11, internal transport barriers 12, internal heating from cold pulse propagation 13, and other problems. The reduction is designed to...

  17. NUMERICAL MODELING OF CONTAMINANT TRANSPORT IN FRACTURED POROUS MEDIA USING MIXED FINITE ELEMENT AND FINITE VOLUME METHODS

    SciTech Connect (OSTI)

    Taylor, G.; Dong, C.; Sun, S.

    2010-03-18

    A mathematical model for contaminant species passing through fractured porous media is presented. In the numerical model, we combine two locally conservative methods, i.e. mixed finite element (MFE) and the finite volume methods. Adaptive triangle mesh is used for effective treatment of the fractures. A hybrid MFE method is employed to provide an accurate approximation of velocities field for both the fractures and matrix which are crucial to the convection part of the transport equation. The finite volume method and the standard MFE method are used to approximate the convection and dispersion terms respectively. The model is used to investigate the interaction of adsorption with transport and to extract information on effective adsorption distribution coefficients. Numerical examples in different fractured media illustrate the robustness and efficiency of the proposed numerical model.

  18. From Sequential Extraction to Transport Modeling: Monitored Natural Attenuation as a Remediation Approach for Inorganic Contaminants

    SciTech Connect (OSTI)

    Crapse, Kimberly P.; Serkiz, Steven M.; Pishko, Adrian L.; Kaplan, Daniel L.; Lee, Cindy M.; Schank, Anja

    2005-08-18

    To quantify metal natural attenuation processes in terms of environmental availability, sequential extraction experiments were carried out on subsurface soil samples impacted by a low pH, high sulfate, metals (Be, Ni, U, As) plume associated with the long-term operation of a coal plant at the Savannah River Site in South Carolina. Despite significant heterogeneity resulting both from natural and anthropogenic factors, sequential extraction results demonstrate that pH is a controlling factor in the prediction of the distribution of metal contaminants within the solid phases in soils at the site as well as the contaminant partitioning between the soil and the soil solution. Results for beryllium, the most mobile metal evaluated, exhibit increasing attenuation along the plume flow path which corresponds to an increasing plume pH. These laboratory- and field-scale studies provide mechanistic information regarding partitioning of metals to soils at the site (one of the major attenuation mechanisms for the metals at the field site). Subsequently, these data have been used in the definition of the contaminant source terms and contaminant transport factors in risk modeling for the site.

  19. Mathematical modeling of positron emission tomography (PET) data to assess radiofluoride transport in living plants following petiolar administration

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Converse, Alexander K.; Ahlers, Elizabeth O.; Bryan, Tom W.; Hetue, Jackson D.; Lake, Katherine A.; Ellison, Paul A.; Engle, Jonathan W.; Barnhart, Todd E.; Nickles, Robert J.; Williams, Paul H.; et al

    2015-03-15

    Background: Ion transport is a fundamental physiological process that can be studied non-invasively in living plants with radiotracer imaging methods. Fluoride is a known phytotoxic pollutant and understanding its transport in plants after leaf absorption is of interest to those in agricultural areas near industrial sources of airborne fluoride. Here we report the novel use of a commercial, high-resolution, animal positron emission tomography (PET) scanner to trace a bolus of [¹⁸F]fluoride administered via bisected petioles of Brassica oleracea, an established model species, to simulate whole plant uptake of atmospheric fluoride. This methodology allows for the first time mathematical compartmental modelingmore » of fluoride transport in the living plant. Radiotracer kinetics in the stem were described with a single-parameter free- and trapped-compartment model and mean arrival times at different stem positions were calculated from the free-compartment time-activity curves. Results: After initiation of administration at the bisected leaf stalk, [¹⁸F] radioactivity climbed for approximately 10 minutes followed by rapid washout from the stem and equilibration within leaves. Kinetic modeling of transport in the stem yielded a trapping rate of 1.5 +/- 0.3%/min (mean +/- s.d., n = 3), velocity of 2.2 +/- 1.1 cm/min, and trapping fraction of 0.8 +/- 0.5%/cm. Conclusion: Quantitative assessment of physiologically meaningful transport parameters of fluoride in living plants is possible using standard positron emission tomography in combination with petiolar radiotracer administration. Movement of free fluoride was observed to be consistent with bulk flow in xylem, namely a rapid and linear change in position with respect to time. Trapping, likely in the apoplast, was observed. Future applications of the methods described here include studies of transport of other ions and molecules of interest in plant physiology.« less

  20. Phase I Contaminant Transport Parameters for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 99: Rainier Mesa/Shoshone Mountain, Nevada Test Site, Nye County, Nevada, Revision 1

    SciTech Connect (OSTI)

    Nathan Bryant

    2008-05-01

    This document presents a summary and framework of available transport data and other information directly relevant to the development of the Rainier Mesa/Shoshone Mountain (RMSM) Corrective Action Unit (CAU) 99 groundwater transport model. Where appropriate, data and information documented elsewhere are briefly summarized with reference to the complete documentation.

  1. Modeling and Simulation of Used Nuclear Fuel During Transportation with Consideration of Hydride Effects and Cyclic Fatigue

    SciTech Connect (OSTI)

    Chakraborty, Pritam; Sabharwall, Piyush; Spears, Robert Edward; Coleman, Justin Leigh; Sener, Kadir; Varma, Amit H.

    2015-09-30

    The objective of this work is to understand the integrity of Used Nuclear Fuel (UNF) during transportation. Previous analysis work has been performed to look at the integrity of UNF during transportation but these analyses have neglected to analyze the effect of hydrides and flaws (fracture mechanics models to capture radial cracking in the cladding). In this study, the clad regions of interest are near the pellet-pellet interfaces. These regions can experience more complex stress-states than the rest of the clad during cooling and have a greater possibility to develop radially reoriented hydrides during vacuum drying.

  2. Transportation Secure Data Center: Real-World Data for Planning, Modeling and Analysis (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2013-01-01

    The National Renewable Energy Laboratory (NREL) and the U.S. Department of Transportation (DOT) have launched the free, web-based Transportation Secure Data Center (TSDC). The TSDC (www.nrel.gov/tsdc) preserves respondent anonymity while making vital transportation data available to a broad group of users through secure, online access. The TSDC database gives, metropolitan planning organizations, universities, national laboratories, air quality management districts, disaster planning agencies and auto manufacturers free-of-charge web-based access to valuable transportation data. The TSDC's two levels of access make composite data available with simple online registration, and allow researchers to use detailed spatial data after completing a straight forward application process.

  3. Transportation Secure Data Center: Real-World Data for Planning, Modeling, and Analysis (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2014-01-01

    This fact sheet describes the Transportation Secure Data Center (TSDC) - an NREL-operated resource that provides secure access to detailed GPS travel data for valuable research purposes in a way that protects original participant privacy.

  4. A technical review of urban land use - transportation models as tools for evaluating vehicle travel reduction strategies

    SciTech Connect (OSTI)

    Southworth, F.

    1995-07-01

    The continued growth of highway traffic in the United States has led to unwanted urban traffic congestion as well as to noticeable urban air quality problems. These problems include emissions covered by the 1990 Clean Air Act Amendments (CAAA) and 1991 Intermodal Surface Transportation Efficiency Act (ISTEA), as well as carbon dioxide and related {open_quotes}greenhouse gas{close_quotes} emissions. Urban travel also creates a major demand for imported oil. Therefore, for economic as well as environmental reasons, transportation planning agencies at both the state and metropolitan area level are focussing a good deal of attention on urban travel reduction policies. Much discussed policy instruments include those that encourage fewer trip starts, shorter trip distances, shifts to higher-occupancy vehicles or to nonvehicular modes, and shifts in the timing of trips from the more to the less congested periods of the day or week. Some analysts have concluded that in order to bring about sustainable reductions in urban traffic volumes, significant changes will be necessary in the way our households and businesses engage in daily travel. Such changes are likely to involve changes in the ways we organize and use traffic-generating and-attracting land within our urban areas. The purpose of this review is to evaluate the ability of current analytic methods and models to support both the evaluation and possibly the design of such vehicle travel reduction strategies, including those strategies involving the reorganization and use of urban land. The review is organized into three sections. Section 1 describes the nature of the problem we are trying to model, Section 2 reviews the state of the art in operational urban land use-transportation simulation models, and Section 3 provides a critical assessment of such models as useful urban transportation planning tools. A number of areas are identified where further model development or testing is required.

  5. Cosmic ray transport in heliospheric magnetic structures. I. Modeling background solar wind using the CRONOS magnetohydrodynamic code

    SciTech Connect (OSTI)

    Wiengarten, T.; Kleimann, J.; Fichtner, H.; Kühl, P.; Kopp, A.; Heber, B.; Kissmann, R.

    2014-06-10

    The transport of energetic particles such as cosmic rays is governed by the properties of the plasma being traversed. While these properties are rather poorly known for galactic and interstellar plasmas due to the lack of in situ measurements, the heliospheric plasma environment has been probed by spacecraft for decades and provides a unique opportunity for testing transport theories. Of particular interest for the three-dimensional (3D) heliospheric transport of energetic particles are structures such as corotating interaction regions, which, due to strongly enhanced magnetic field strengths, turbulence, and associated shocks, can act as diffusion barriers on the one hand, but also as accelerators of low energy CRs on the other hand as well. In a two-fold series of papers, we investigate these effects by modeling inner-heliospheric solar wind conditions with a numerical magnetohydrodynamic (MHD) setup (this paper), which will serve as an input to a transport code employing a stochastic differential equation approach (second paper). In this first paper, we present results from 3D MHD simulations with our code CRONOS: for validation purposes we use analytic boundary conditions and compare with similar work by Pizzo. For a more realistic modeling of solar wind conditions, boundary conditions derived from synoptic magnetograms via the Wang-Sheeley-Arge (WSA) model are utilized, where the potential field modeling is performed with a finite-difference approach in contrast to the traditional spherical harmonics expansion often utilized in the WSA model. Our results are validated by comparing with multi-spacecraft data for ecliptical (STEREO-A/B) and out-of-ecliptic (Ulysses) regions.

  6. New NIR Calibration Models Speed Biomass Composition and Reactivity Characterization (Fact Sheet), Highlights in Research & Development, NREL (National Renewable Energy Laboratory)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Using near-infrared (NIR) spectroscopy, NREL researchers have developed powerful tools to rapidly estimate biomass feedstock characteristics. Obtaining precise chemical composition and reactivity information (measures of carbohydrate release and yield) for biomass feedstocks in a timely manner is necessary for the commercialization of biofuels. Accurate measurement of biomass carbohydrate content and carbohydrate accessibility are of prime importance because they are directly proportional to

  7. Reactive power compensator

    DOE Patents [OSTI]

    El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.; Chen, Mingliang; Andexler, George; Huang, Tony

    1992-01-01

    A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

  8. Reactive Power Compensator.

    DOE Patents [OSTI]

    El-Sharkawi, M.A.; Venkata, S.S.; Chen, M.; Andexler, G.; Huang, T.

    1992-07-28

    A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation. 26 figs.

  9. Numerical modeling of the groundwater contaminant transport for the Lake Karachai Area: The methodological approach and the basic two- dimensional regional model

    SciTech Connect (OSTI)

    Petrov, A.V.; Samsonova, L.M.; Vasil`kova, N.A.; Zinin, A.I.; Zinina, G.A. |

    1994-06-01

    Methodological aspects of the numerical modeling of the groundwater contaminant transport for the Lake Karachay area are discussed. Main features of conditions of the task are the high grade of non-uniformity of the aquifer in the fractured rock massif and the high density of the waste solutions, and also the high volume of the input data: both on the part of parameters of the aquifer (number of pump tests) and on the part of observations of functions of processes (long-time observations by the monitoring well grid). The modeling process for constructing the two dimensional regional model is described, and this model is presented as the basic model for subsequent full three-dimensional modeling in sub-areas of interest. Original powerful mathematical apparatus and computer codes for finite-difference numerical modeling are used.

  10. Phase II Transport Model of Corrective Action Unit 98: Frenchman Flat, Nevada Test Site, Nye County, Nevada, Revision 1

    SciTech Connect (OSTI)

    Gregg Ruskuaff

    2010-01-01

    This document, the Phase II Frenchman Flat transport report, presents the results of radionuclide transport simulations that incorporate groundwater radionuclide transport model statistical and structural uncertainty, and lead to forecasts of the contaminant boundary (CB) for a set of representative models from an ensemble of possible models. This work, as described in the Federal Facility Agreement and Consent Order (FFACO) Underground Test Area (UGTA) strategy (FFACO, 1996; amended 2010), forms an essential part of the technical basis for subsequent negotiation of the compliance boundary of the Frenchman Flat corrective action unit (CAU) by Nevada Division of Environmental Protection (NDEP) and National Nuclear Security Administration Nevada Site Office (NNSA/NSO). Underground nuclear testing via deep vertical shafts was conducted at the Nevada Test Site (NTS) from 1951 until 1992. The Frenchman Flat area, the subject of this report, was used for seven years, with 10 underground nuclear tests being conducted. The U.S. Department of Energy (DOE), NNSA/NSO initiated the UGTA Project to assess and evaluate the effects of underground nuclear tests on groundwater at the NTS and vicinity through the FFACO (1996, amended 2010). The processes that will be used to complete UGTA corrective actions are described in the “Corrective Action Strategy” in the FFACO Appendix VI, Revision No. 2 (February 20, 2008).

  11. BETR-world: A geographically explicit model of chemical fate: Application to transport of a-HCH to the arctic

    SciTech Connect (OSTI)

    Toose, Liisa; Woodfine, David G.; MacLeod, Matthew; Mackay, Don; Gouin, Jenn

    2003-12-01

    The Berkeley Trent (BETR)-World model, a 25 compartment, geographically explicit fugacity-based model is described and applied to evaluate the transport of chemicals from temperate source regions to receptor regions (such as the Arctic). The model was parameterized using GIS and an array of digital data on weather, oceans, freshwater, vegetation and geo-political boundaries. This version of the BETR model framework includes modification of atmospheric degradation rates by seasonally variable hydroxyl radical concentrations and temperature. Degradation rates in all other compartments vary with seasonally changing temperature. Deposition to the deep ocean has been included as a loss mechanism. A case study was undertaken for a-HCH. Dynamic emission scenarios were estimated for each of the 25 regions. Predicted environmental concentrations showed good agreement with measured values for the northern regions in air , and fresh and oceanic water and with the results from a previous model of global chemical fate. Potential for long-range transport and deposition to the Arctic region was assessed using a Transfer Efficiency combined with estimated emissions. European regions and the Orient including China have a high potential to contribute a-HCH contamination in the Arctic due to high rates of emission in these regions despite low Transfer Efficiencies. Sensitivity analyses reveal that the performance and reliability of the model is strongly in sequenced by parameters controlling degradation rates.

  12. CLEAR (Calculates Logical Evacuation And Response): A Generic Transportation Network Model for the Calculation of Evacuation Time Estimates

    SciTech Connect (OSTI)

    Moeller, M. P.; Urbanik, II, T.; Desrosiers, A. E.

    1982-03-01

    This paper describes the methodology and application of the computer model CLEAR (Calculates Logical Evacuation And Response) which estimates the time required for a specific population density and distribution to evacuate an area using a specific transportation network. The CLEAR model simulates vehicle departure and movement on a transportation network according to the conditions and consequences of traffic flow. These include handling vehicles at intersecting road segments, calculating the velocity of travel on a road segment as a function of its vehicle density, and accounting for the delay of vehicles in traffic queues. The program also models the distribution of times required by individuals to prepare for an evacuation. In order to test its accuracy, the CLEAR model was used to estimate evacuatlon tlmes for the emergency planning zone surrounding the Beaver Valley Nuclear Power Plant. The Beaver Valley site was selected because evacuation time estimates had previously been prepared by the licensee, Duquesne Light, as well as by the Federal Emergency Management Agency and the Pennsylvania Emergency Management Agency. A lack of documentation prevented a detailed comparison of the estimates based on the CLEAR model and those obtained by Duquesne Light. However, the CLEAR model results compared favorably with the estimates prepared by the other two agencies.

  13. Simulation of oil-slick transport in Great Lakes connecting channels. Volume 1. Theory and model formulation. Final report

    SciTech Connect (OSTI)

    Shen, H.T.; Yapa, P.D.; Petroski, M.E.

    1986-03-01

    In this study, two computer models named as ROSS and LROSS are developed for simulating oil-slick transport in rivers and lakes, respectively. The oil slick transformation processes considered in these models include advection, spreading, evaporation, and dissolution. These models can be used for slicks of any shape originated from instantaneous or continuous spills in rivers and lakes with or without ice covers. Although developed for the need of the connecting channels in the upper Great Lakes, including the Detroit River, Lake St. Clair, St. Clair River, and St. Marys River, these models are site independent and can be used to other rivers and lakes. The programs are written in FORTRAN programming language to be compatible with FORTRAN77 compiler. The models are designed to be used on both mainframe and microcomputers.

  14. Grand challenge problems in environmental modeling and remediation: Groundwater contaminant transport. Final project report 1998

    SciTech Connect (OSTI)

    1998-04-01

    The over-reaching goal of the Groundwater Grand Challenge component of the Partnership in Computational Science (PICS) was to develop and establish the massively parallel approach for the description of groundwater flow and transport and to address the problem of uncertainties in the data and its interpretation. This necessitated the development of innovative algorithms and the implementation of massively parallel computational tools to provide a suite of simulators for groundwater flow and transport in heterogeneous media. This report summarizes the activities and deliverables of the Groundwater Grand Challenge project funded through the High Performance Computing grand challenge program of the Department of Energy from 1995 through 1997.

  15. Phase I Contaminant Transport Parameters for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 97: Yucca Flat/Climax Mine, Nevada Test Site, Nye County, Nevada, Revision 0

    SciTech Connect (OSTI)

    John McCord

    2007-09-01

    This report documents transport data and data analyses for Yucca Flat/Climax Mine CAU 97. The purpose of the data compilation and related analyses is to provide the primary reference to support parameterization of the Yucca Flat/Climax Mine CAU transport model. Specific task objectives were as follows: • Identify and compile currently available transport parameter data and supporting information that may be relevant to the Yucca Flat/Climax Mine CAU. • Assess the level of quality of the data and associated documentation. • Analyze the data to derive expected values and estimates of the associated uncertainty and variability. The scope of this document includes the compilation and assessment of data and information relevant to transport parameters for the Yucca Flat/Climax Mine CAU subsurface within the context of unclassified source-term contamination. Data types of interest include mineralogy, aqueous chemistry, matrix and effective porosity, dispersivity, matrix diffusion, matrix and fracture sorption, and colloid-facilitated transport parameters.

  16. Porous Anode Model for Coal Syngas Fuelled SOFC: Combined Mass and Energy Transport Normal to Cell Plane

    SciTech Connect (OSTI)

    Gerdes, K.R.; Gemmen, R.S.

    2008-06-01

    Solid oxide fuel cells are being developed for integrated gasification combined cycle hybrid power systems. It is therefore necessary to evaluate the coupled temperature and concentration profiles for SOFC anodes exposed to coal syngas. In this work the SOFC anode was treated as a porous composite of 50/50 (volume) Ni / YSZ. Porous transport was modeled using the dusty gas model (DGM) and included two pore reactions, namely water gas shift and steam reforming of methane. The thermal transport model considered heat exchange by radiation between the interconnect and SOFC surface, convective transfer from bulk gas flow over the anode, heat generation terms due to pore reactions, and heat generation terms at the electrolyte boundary due to electrochemical reactions, ohmic heating, and concentration polarization. Composition profiles throughout the porous anode were considered for the DGM alone and were compared to the DGM including energy (DGME). The cases examined were for current densities ranging from 0.000-0.750 A/cm2 and for pressures from 1-19 atm absolute. Simulation results predict that the average cell operating temperature will increase 10 to 60°C relative to the furnace wall with inclusion of the energy equations. However, the thermal gradients within the anode are small due to the good thermal conductivity of the Ni-based anode. The effect of inclusion of energy transport on the hydrogen concentration profile is mixed depending on the independent parameter considered, with relative insensitivity to changes in the current density, but modest sensitivity to changes in operating pressure. Consideration of the thermal transport is important for determination of the interaction of coal syngas trace species with the anode, but is less critical for material stability.

  17. Validation, Proof-of-Concept, and Postaudit of the Groundwater Flow and Transport Model of the Project Shoal Area

    SciTech Connect (OSTI)

    Ahmed Hassan

    2004-09-01

    The groundwater flow and radionuclide transport model characterizing the Shoal underground nuclear test has been accepted by the State of Nevada Division of Environmental Protection. According to the Federal Facility Agreement and Consent Order (FFACO) between DOE and the State of Nevada, the next steps in the closure process for the site are then model validation (or postaudit), the proof-of-concept, and the long-term monitoring stage. This report addresses the development of the validation strategy for the Shoal model, needed for preparing the subsurface Corrective Action Decision Document-Corrective Action Plan and the development of the proof-of-concept tools needed during the five-year monitoring/validation period. The approach builds on a previous model, but is adapted and modified to the site-specific conditions and challenges of the Shoal site.

  18. Variational reactivity estimates: new analyses and new results

    SciTech Connect (OSTI)

    Favorite, Jeffrey A

    2009-01-01

    A modified form of the variational estimate of the reactivity worth ofa perturbation was previously developed to extend the range of applicability of variational perturbation theory for perturbations leading to negative reactivity worths. Recent numerical results challenged the assumptions behind the modified form. In this paper, more results are obtained, leading to the conclusion that sometimes the modified form extends the range ofapplicability of variational perturbation theory for positive reactivity worths as well, and sometimes the standard variational form is more accurate for negative-reactivity perturbations. In addition, this paper proves that using the exact generalized adjoint function would lead to an inaccurate variational reactivity estimate when the error in the first-order estimate is large; the standard generalized adjoint function, an approximation to the exact one, leads to Lore accurate results. This conclusion is also demonstrated numerically. Transport calculations use the PARTISN multi group discrete ordinates code

  19. Reactive Power Compensating System.

    DOE Patents [OSTI]

    Williams, Timothy J.; El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.

    1985-01-04

    The circuit was designed for the specific application of wind-driven induction generators. It has great potential for application in any situation where a varying reactive power load is present, such as with induction motors or generators, or for transmission network compensation.

  20. Reactive power compensating system

    DOE Patents [OSTI]

    Williams, Timothy J.; El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.

    1987-01-01

    The reactive power of an induction machine is compensated by providing fixed capacitors on each phase line for the minimum compensation required, sensing the current on one line at the time its voltage crosses zero to determine the actual compensation required for each phase, and selecting switched capacitors on each line to provide the balance of the compensation required.

  1. Validation of the thermal transport model used for ITER startup scenario predictions with DIII-D experimental data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Casper, T. A.; Meyer, W. H.; Jackson, G. L.; Luce, T. C.; Hyatt, A. W.; Humphreys, D. A.; Turco, F.

    2010-12-08

    We are exploring characteristics of ITER startup scenarios in similarity experiments conducted on the DIII-D Tokamak. In these experiments, we have validated scenarios for the ITER current ramp up to full current and developed methods to control the plasma parameters to achieve stability. Predictive simulations of ITER startup using 2D free-boundary equilibrium and 1D transport codes rely on accurate estimates of the electron and ion temperature profiles that determine the electrical conductivity and pressure profiles during the current rise. Here we present results of validation studies that apply the transport model used by the ITER team to DIII-D discharge evolutionmore » and comparisons with data from our similarity experiments.« less

  2. Modeling most likely pathways for smuggling radioactive and special nuclear materials on a worldwide multi-modal transportation network

    SciTech Connect (OSTI)

    Saeger, Kevin J; Cuellar, Leticia

    2010-10-28

    Nuclear weapons proliferation is an existing and growing worldwide problem. To help with devising strategies and supporting decisions to interdict the transport of nuclear material, we developed the Pathway Analysis, Threat Response and Interdiction Options Tool (PATRIOT) that provides an analytical approach for evaluating the probability that an adversary smuggling radioactive or special nuclear material will be detected during transit. We incorporate a global, multi-modal transportation network, explicit representation of designed and serendipitous detection opportunities, and multiple threat devices, material types, and shielding levels. This paper presents the general structure of PATRIOT, all focuses on the theoretical framework used to model the reliabilities of all network components that are used to predict the most likely pathways to the target.

  3. Modeling most likely pathways for smuggling radioactive and special nuclear materials on a worldwide multimodal transportation network

    SciTech Connect (OSTI)

    Saeger, Kevin J; Cuellar, Leticia

    2010-01-01

    Nuclear weapons proliferation is an existing and growing worldwide problem. To help with devising strategies and supporting decisions to interdict the transport of nuclear material, we developed the Pathway Analysis, Threat Response and Interdiction Options Tool (PATRIOT) that provides an analytical approach for evaluating the probability that an adversary smuggling radioactive or special nuclear material will be detected during transit. We incorporate a global, multi-modal transportation network, explicit representation of designed and serendipitous detection opportunities, and multiple threat devices, material types, and shielding levels. This paper presents the general structure of PATRIOT, and focuses on the theoretical framework used to model the reliabilities of all network components that are used to predict the most likely pathways to the target.

  4. Colloid-Facilitated Transport of 137Cs in Fracture-Fill Material. Experiments and Modeling

    SciTech Connect (OSTI)

    Dittrich, Timothy M.; Reimus, Paul William

    2015-10-29

    In this study, we demonstrate how a combination of batch sorption/desorption experiments and column transport experiments were used to effectively parameterize a model describing the colloid-facilitated transport of Cs in the Grimsel granodiorite/FFM system. Cs partition coefficient estimates onto both the colloids and the stationary media obtained from the batch experiments were used as initial estimates of partition coefficients in the column experiments, and then the column experiment results were used to obtain refined estimates of the number of different sorption sites and the adsorption and desorption rate constants of the sites. The desorption portion of the column breakthrough curves highlighted the importance of accounting for adsorption-desorption hysteresis (or a very nonlinear adsorption isotherm) of the Cs on the FFM in the model, and this portion of the breakthrough curves also dictated that there be at least two different types of sorption sites on the FFM. In the end, the two-site model parameters estimated from the column experiments provided excellent matches to the batch adsorption/desorption data, which provided a measure of assurance in the validity of the model.

  5. co2-transport | netl.doe.gov

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Transport Cost Model FENETL CO2 Transport Cost Model About the model: This model was developed to estimate the cost of transporting a user-specified mass rate of CO2 by pipeline...

  6. Comparison of Conventional Diesel and Reactivity Controlled Compression

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Ignition (RCCI) Combustion in a Light-Duty Engine | Department of Energy Conventional Diesel and Reactivity Controlled Compression Ignition (RCCI) Combustion in a Light-Duty Engine Comparison of Conventional Diesel and Reactivity Controlled Compression Ignition (RCCI) Combustion in a Light-Duty Engine CFD modeling was used to compare conventional diesel and dual-fuel Reactivity Controlled Compression Ignition combustion at US Tier 2 Bin 5 NOx levels, while accounting for Diesel Exhaust Fluid

  7. Three-dimensional fully-coupled electrical and thermal transport model of dynamic switching in oxide memristors

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gao, Xujiao; Mamaluy, Denis; Mickel, Patrick R.; Marinella, Matthew

    2015-09-08

    In this paper, we present a fully-coupled electrical and thermal transport model for oxide memristors that solves simultaneously the time-dependent continuity equations for all relevant carriers, together with the time-dependent heat equation including Joule heating sources. The model captures all the important processes that drive memristive switching and is applicable to simulate switching behavior in a wide range of oxide memristors. The model is applied to simulate the ON switching in a 3D filamentary TaOx memristor. Simulation results show that, for uniform vacancy density in the OFF state, vacancies fill in the conduction filament till saturation, and then fill outmore » a gap formed in the Ta electrode during ON switching; furthermore, ON-switching time strongly depends on applied voltage and the ON-to-OFF current ratio is sensitive to the filament vacancy density in the OFF state.« less

  8. Three-dimensional fully-coupled electrical and thermal transport model of dynamic switching in oxide memristors

    SciTech Connect (OSTI)

    Gao, Xujiao; Mamaluy, Denis; Mickel, Patrick R.; Marinella, Matthew

    2015-09-08

    In this paper, we present a fully-coupled electrical and thermal transport model for oxide memristors that solves simultaneously the time-dependent continuity equations for all relevant carriers, together with the time-dependent heat equation including Joule heating sources. The model captures all the important processes that drive memristive switching and is applicable to simulate switching behavior in a wide range of oxide memristors. The model is applied to simulate the ON switching in a 3D filamentary TaOx memristor. Simulation results show that, for uniform vacancy density in the OFF state, vacancies fill in the conduction filament till saturation, and then fill out a gap formed in the Ta electrode during ON switching; furthermore, ON-switching time strongly depends on applied voltage and the ON-to-OFF current ratio is sensitive to the filament vacancy density in the OFF state.

  9. Communication: Ro-vibrational control of chemical reactivity in H+CH{sub 4}→ H{sub 2}+CH{sub 3} : Full-dimensional quantum dynamics calculations and a sudden model

    SciTech Connect (OSTI)

    Welsch, Ralph Manthe, Uwe

    2014-08-07

    The mode-selective chemistry of the title reaction is studied by full-dimensional quantum dynamics simulation on an accurate ab initio potential energy surface for vanishing total angular momentum. Using a rigorous transition state based approach and multi-configurational time-dependent Hartree wave packet propagation, initial state-selected reaction probabilities for many ro-vibrational states of methane are calculated. The theoretical results are compared with experimental trends seen in reactions of methane. An intuitive interpretation of the ro-vibrational control of the chemical reactivity provided by a sudden model based on the quantum transition state concept is discussed.

  10. Subsurface Uranium Fate and Transport: Integrated Experiments and Modeling of Coupled Biogeochemical Mechanisms of Nanocrystalline Uraninite Oxidation by Fe(III)-(hydr)oxides - Project Final Report

    SciTech Connect (OSTI)

    Peyton, Brent M. [Montana State University; Timothy, Ginn R. [University of California Davis; Sani, Rajesh K. [South Dakota School of Mines and Technology

    2013-08-14

    have measured elevated U concentrations in oxic iron-rich sediments. To translate experimental results into numerical analysis of U fate and transport, a reaction network was developed based on Sani et al. (2004) to simulate U(VI) bioreduction with concomitant UO2 reoxidation in the presence of hematite or ferrihydrite. The reduction phase considers SRB reduction (using lactate) with the reductive dissolution of Fe(III) solids, which is set to be microbially mediated as well as abiotically driven by sulfide. Model results show the oxidation of HS by Fe(III) directly competes with UO2 reoxidation as Fe(III) oxidizes HS preferentially over UO2. The majority of Fe reduction is predicted to be abiotic, with ferrihydrite becoming fully consumed by reaction with sulfide. Predicted total dissolved carbonate concentrations from the degradation of lactate are elevated (log(pCO2) ~ 1) and, in the hematite system, yield close to two orders-of-magnitude higher U(VI) concentrations than under initial carbonate concentrations of 3 mM. Modeling of U(VI) bioreduction with concomitant reoxidation of UO2 in the presence of ferrihydrite was also extended to a two-dimensional field-scale groundwater flow and biogeochemically reactive transport model for the South Oyster site in eastern Virginia. This model was developed to simulate the field-scale immobilization and subsequent reoxidation of U by a biologically mediated reaction network.

  11. Reactive power pricing and management

    SciTech Connect (OSTI)

    Hao, S.; Papalexopoulos, A.

    1997-02-01

    This paper explores the technical and economic issues of determining reactive power pricing structures in an open-access environment. It is believed that reactive power pricing and management under open-access will depend upon two important developments: (1) the functional unbundling of facilities that support the reactive power and voltage control service, and (2) grid rules to facilitate the coordination between generation and transmission systems for reliable system operation. The paper discusses the characteristics of reactive power that must be considered in order to develop a framework for reactive power pricing and management. Several cost allocation methods for valuing reactive power are presented. Two workable reactive power pricing structures are also proposed. The first is based on performance standards and the second is based on the local reactive power market concept.

  12. CASCADER: An M-chain gas-phase radionuclide transport and fate model. Volume 4 -- Users guide to CASCADR9

    SciTech Connect (OSTI)

    Cawlfield, D.E.; Emer, D.F.; Lindstrom, F.T.; Shott, G.J.

    1993-09-01

    Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and/or dispersion. Additionally during the transport of parent and daughter radionuclides in soil, radionuclide decay may occur. This version of CASCADER called CASCADR9 starts with the concepts presented in volumes one and three of this series. For a proper understanding of how the model works, the reader should read volume one first. Also presented in this volume is a set of realistic scenarios for buried sources of radon gas, and the input and output file structure for CASCADER9.

  13. Reactive Air Aluminization

    SciTech Connect (OSTI)

    Choi, Jung-Pyung; Chou, Y. S.; Stevenson, Jeffry W.

    2011-10-28

    Ferritic stainless steels and other alloys are of great interest to SOFC developers for applications such as interconnects, cell frames, and balance of plant components. While these alloys offer significant advantages (e.g., low material and manufacturing cost, high thermal conductivity, and high temperature oxidation resistance), there are challenges which can hinder their utilization in SOFC systems; these challenges include Cr volatility and reactivity with glass seals. To overcome these challenges, protective coatings and surface treatments for the alloys are under development. In particular, aluminization of alloy surfaces offers the potential for mitigating both evaporation of Cr from the alloy surface and reaction of alloy constituents with glass seals. Commercial aluminization processes are available to SOFC developers, but they tend to be costly due to their use of exotic raw materials and/or processing conditions. As an alternative, PNNL has developed Reactive Air Aluminization (RAA), which offers a low-cost, simpler alternative to conventional aluminization methods.

  14. A Geographic Information System approach to modeling nutrient and sediment transport

    SciTech Connect (OSTI)

    Levine, D.A.; Hunsaker, C.T.; Beauchamp, J.J.; Timmins, S.P.

    1993-02-01

    The objective of this study was to develop a water quality model to quantify nonpoint-source (NPS) pollution that uses a geographic information system (GIS) to link statistical modeling of nutrient and sediment delivery with the spatial arrangement of the parameters that drive the model. The model predicts annual nutrient and sediment loading and was developed, calibrated, and tested on 12 watersheds within the Lake Ray Roberts drainage basin in north Texas. Three physiographic regions are represented by these watersheds, and model success, as measured by the accuracy of load estimates, was compared within and across these regions.

  15. Transportation Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Energy admin 2015-05-14T22:34:50+00:00 Transportation Energy The national-level objective for the future is to create a carbon-neutral fleet that is powered by low-carbon US sources. Sandia delivers advanced technologies and design tools to the broad transportation sector in the following areas: Predictive Simulation of Engines Fuel sprays and their transition from the liquid to gas phase and computationally tractable models that capture the physics of combustion. Convergence of Biofuels and

  16. Vadose Zone Transport Field Study: Summary Report

    SciTech Connect (OSTI)

    Ward, Andy L.; Conrad, Mark E.; Daily, William D.; Fink, James B.; Freedman, Vicky L.; Gee, Glendon W.; Hoversten, Gary M.; Keller, Jason M.; Majer, Ernest L.; Murray, Christopher J.; White, Mark D.; Yabusaki, Steven B.; Zhang, Z. F.

    2006-07-31

    (e.g. BC Cribs and Trenches). The improved models have been also coupled with inverse models and newly-developed parameter scaling techniques to allow estimation of field-scale and effective transport parameters for the vadose zone. The development and utility of pedotransfer functions for describing fine-scale hydrogeochemical heterogeneity and for incorporating this heterogeneity into reactive transport models was explored. An approach based on grain-size statistics appears feasible and has been used to describe heterogeneity in hydraulic properties and sorption properties, such as the cation exchange capacity and the specific surface area of Hanford sediments. This work has also led to the development of inverse modeling capabilities for time-dependent, subsurface, reactive transport with transient flow fields using an automated optimization algorithm. In addition, a number of geophysical techniques investigated for their potential to provide detailed information on the subtle changes in lithology and bedding surfaces; plume delineation, leak detection. High-resolution resistivity is now being used for detecting saline plumes at several waste sites at Hanford, including tank farms. Results from the field studies and associated analysis have appeared in more than 46 publications generated over the past 4 years. These publications include test plans and status reports, in addition to numerous technical notes and peer reviewed papers.

  17. Permeable Reactive Barriers | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Permeable Reactive Barriers Permeable Reactive Barriers Permeable Reactive Barrier Field Projects Durango, Colorado Durango, Colorado DOE installed a PRB in October 1995 to treat ...

  18. Core design of long life-cycle fast reactors operating without reactivity margin

    SciTech Connect (OSTI)

    Aristova, E. N.; Baydin, D. F.; Gol'din, V. Y.; Pestryakova, G. A.; Stoynov, M. I.

    2012-07-01

    In this paper we consider a possibility of designing a fast reactor core that operates without reactivity margin for a long time. This study is based on the physical principle of fast reactor operating in a self-adjustable neutron-nuclear regime (SANNR-1) introduced by L.P. Feoktistov (1988-1993) and improved by V. Ya. Gol'din SANNR-2 (1995). The mathematical modeling of active zones of fast reactors in SANNR modes is held by authors since 1992. The numerical simulation is based on solving the neutron transport equation coupled with quasi-diffusion equations. The calculations have been performed using standard 26 energy groups. We use a hierarchy of spatial models of 1D, 1.5D, 2D, and 3D geometries. The spatial models of higher dimensionality are used for verification of results. The calculations showed that operation of the reactor in this mode increases its efficiency, safety and simplifies management. It is possible to achieve continuous work of the reactor in SANNR-2 during 7-10 years without fuel overloads by means of further optimization of the mode. Small reactivity margin is used only for the reactor start up. After first 10-15 days the reactor in SANNR-2 operates without reactivity margin. (authors)

  19. A groundwater flow and transport model of long-term radionuclide migration in central Frenchman flat, Nevada test site

    SciTech Connect (OSTI)

    Kwicklis, Edward Michael [Los Alamos National Laboratory; Becker, Naomi M [Los Alamos National Laboratory; Ruskauff, Gregory [NAVARRO-INTERA, LLC.; De Novio, Nicole [GOLDER AND ASSOC.; Wilborn, Bill [US DOE NNSA NSO

    2010-11-10

    A set of groundwater flow and transport models were created for the Central Testing Area of Frenchman Flat at the former Nevada Test Site to investigate the long-term consequences of a radionuclide migration experiment that was done between 1975 and 1990. In this experiment, radionuclide migration was induced from a small nuclear test conducted below the water table by pumping a well 91 m away. After radionuclides arrived at the pumping well, the contaminated effluent was discharged to an unlined ditch leading to a playa where it was expected to evaporate. However, recent data from a well near the ditch and results from detailed models of the experiment by LLNL personnel have convincingly demonstrated that radionuclides from the ditch eventually reached the water table some 220 m below land surface. The models presented in this paper combine aspects of these detailed models with concepts of basin-scale flow to estimate the likely extent of contamination resulting from this experiment over the next 1,000 years. The models demonstrate that because regulatory limits for radionuclide concentrations are exceeded only by tritium and the half-life of tritium is relatively short (12.3 years), the maximum extent of contaminated groundwater has or will soon be reached, after which time the contaminated plume will begin to shrink because of radioactive decay. The models also show that past and future groundwater pumping from water supply wells within Frenchman Flat basin will have negligible effects on the extent of the plume.

  20. Modeling of Groundwater Flow and Radionuclide Transport at the Climax Mine sub-CAU, Nevada Test Site

    SciTech Connect (OSTI)

    K. Pohlmann; M. Ye; D. Reeves; M. Zavarin; D. Decker; J. Chapman

    2007-09-28

    The Yucca Flat-Climax Mine Corrective Action Unit (CAU) on the Nevada Test Site comprises 747 underground nuclear detonations, all but three of which were conducted in alluvial, volcanic, and carbonate rocks in Yucca Flat. The remaining three tests were conducted in the very different hydrogeologic setting of the Climax Mine granite stock located in Area 15 at the northern end of Yucca Flat. As part of the Corrective Action Investigation (CAI) for the Yucca Flat-Climax Mine CAU, models of groundwater flow and radionuclide transport will be developed for Yucca Flat. However, two aspects of these CAU-scale models require focused modeling at the northern end of Yucca Flat beyond the capability of these large models. First, boundary conditions and boundary flows along the northern reaches of the Yucca Flat-Climax Mine CAU require evaluation to a higher level of detail than the CAU-scale Yucca Flat model can efficiently provide. Second, radionuclide fluxes from the Climax tests require analysis of flow and transport in fractured granite, a unique hydrologic environment as compared to Yucca Flat proper. This report describes the Climax Mine sub-CAU modeling studies conducted to address these issues, with the results providing a direct feed into the CAI for the Yucca Flat-Climax Mine CAU. Three underground nuclear detonations were conducted for weapons effects testing in the Climax stock between 1962 and 1966: Hard Hat, Pile Driver, and Tiny Tot. Though there is uncertainty regarding the position of the water table in the stock, it is likely that all three tests were conducted in the unsaturated zone. In the early 1980s, the Spent Fuel Test-Climax (SFT-C) was constructed to evaluate the feasibility of retrievable, deep geologic storage of commercial nuclear reactor wastes. Detailed mapping of fractures and faults carried out for the SFT-C studies greatly expanded earlier data sets collected in association with the nuclear tests and provided invaluable information for

  1. A 3-D Model of Signaling and Transport Pathways in Epithelial Cells

    SciTech Connect (OSTI)

    Quong, A A; Westbrook, C K

    2005-04-01

    A 3-dimensional computer model was developed to simulate the spatial and chemical evolution of calcium ions inside an array of human epithelial kidney cells. This is a prototype model, intended to develop a methodology to incorporate much more complex interactions of metabolic and other processes within many types of cells and lead to increased ability to predict cellular responses to disease as well as to chemical and biological warfare situations. Preliminary tests of the model are described.

  2. Fast-ignition transport studies: Realistic electron source, integrated particle-in-cell and hydrodynamic modeling, imposed magnetic fields

    SciTech Connect (OSTI)

    Strozzi, D. J.; Tabak, M.; Larson, D. J.; Divol, L.; Kemp, A. J.; Bellei, C.; Marinak, M. M.; Key, M. H.

    2012-07-15

    Transport modeling of idealized, cone-guided fast ignition targets indicates the severe challenge posed by fast-electron source divergence. The hybrid particle-in-cell (PIC) code Zuma is run in tandem with the radiation-hydrodynamics code Hydra to model fast-electron propagation, fuel heating, and thermonuclear burn. The fast electron source is based on a 3D explicit-PIC laser-plasma simulation with the PSC code. This shows a quasi two-temperature energy spectrum and a divergent angle spectrum (average velocity-space polar angle of 52 Degree-Sign ). Transport simulations with the PIC-based divergence do not ignite for >1 MJ of fast-electron energy, for a modest (70 {mu}m) standoff distance from fast-electron injection to the dense fuel. However, artificially collimating the source gives an ignition energy of 132 kJ. To mitigate the divergence, we consider imposed axial magnetic fields. Uniform fields {approx}50 MG are sufficient to recover the artificially collimated ignition energy. Experiments at the Omega laser facility have generated fields of this magnitude by imploding a capsule in seed fields of 50-100 kG. Such imploded fields will likely be more compressed in the transport region than in the laser absorption region. When fast electrons encounter increasing field strength, magnetic mirroring can reflect a substantial fraction of them and reduce coupling to the fuel. A hollow magnetic pipe, which peaks at a finite radius, is presented as one field configuration which circumvents mirroring.

  3. Emergency evacuation/transportation plan update: Traffic model development and evaluation of early closure procedures. Final report

    SciTech Connect (OSTI)

    1993-10-28

    Prolonged delays in traffic experienced by Laboratory personnel during a recent early dismissal in inclement weather, coupled with reconstruction efforts along NM 502 east of the White Rock Wye for the next 1 to 2 years, has prompted Los Alamos National Laboratory (LANL) to re-evaluate and improve the present transportation plan and its integration with contingency plans maintained in other organizations. Facilities planners and emergency operations staff need to evaluate the transportation system`s capability to inefficiently and safely evacuate LANL under different low-level emergency conditions. A variety of potential procedures governing the release of employees from the different technical areas (TAs) requires evaluation, perhaps with regard to multiple emergency-condition scenarios, with one or more optimal procedures ultimately presented for adoption by Lab Management. The work undertaken in this project will hopefully lay a foundation for an on-going, progressive transportation system analysis capability. It utilizes microscale simulation techniques to affirm, reassess and validate the Laboratory`s Early Dismissal/Closure/Delayed Opening Plan. The Laboratory is required by Federal guidelines, and compelled by prudent practice and conscientious regard for the welfare of employees and nearby residents, to maintain plans and operating procedures for evacuation if the need arises. The tools developed during this process can be used outside of contingency planning. It is anticipated that the traffic models developed will allow site planners to evaluate changes to the traffic network which could better serve the normal traffic levels. Changes in roadway configuration, control strategies (signalization and signing), response strategies to traffic accidents, and patterns of demand can be modelled using the analysis tools developed during this project. Such scenarios typically are important considerations in master planning and facilities programming.

  4. Model Development and Analysis of the Fate and Transport of Water...

    Broader source: Energy.gov (indexed) [DOE]

    summarizes the initial work on numerical modeling, simulations, and experimental results related to nuclear waste storage in a salt repository. The study reflects the project's...

  5. The Reactivity of Energetic Materials At Extreme Conditions

    SciTech Connect (OSTI)

    Fried, L E

    2006-10-23

    Energetic materials are unique for having a strong exothermic reactivity, which has made them desirable for both military and commercial applications. Energetic materials are commonly divided into high explosives, propellants, and pyrotechnics. We will focus on high explosive (HE) materials here, although there is a great deal of commonality between the classes of energetic materials. Although the history of HE materials is long, their condensed-phase properties are poorly understood. Understanding the condensed-phase properties of HE materials is important for determining stability and performance. Information regarding HE material properties (for example, the physical, chemical, and mechanical behaviors of the constituents in plastic-bonded explosive, or PBX, formulations) is necessary for efficiently building the next generation of explosives as the quest for more powerful energetic materials (in terms of energy per volume) moves forward. In modeling HE materials there is a need to better understand the physical, chemical, and mechanical behaviors from fundamental theoretical principles. Among the quantities of interest in plastic-bonded explosives (PBXs), for example, are thermodynamic stabilities, reaction kinetics, equilibrium transport coefficients, mechanical moduli, and interfacial properties between HE materials and the polymeric binders. These properties are needed (as functions of stress state and temperature) for the development of improved micro-mechanical models, which represent the composite at the level of grains and binder. Improved micro-mechanical models are needed to describe the responses of PBXs to dynamic stress or thermal loading, thus yielding information for use in developing continuum models. Detailed descriptions of the chemical reaction mechanisms of condensed energetic materials at high densities and temperatures are essential for understanding events that occur at the reactive front under combustion or detonation conditions. Under

  6. Heat Transfer and Fluid Transport of Supercritical CO2 in Enhanced Geothermal System with Local Thermal Non-equilibrium Model

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Le; Luo, Feng; Xu, Ruina; Jiang, Peixue; Liu, Huihai

    2014-12-31

    The heat transfer and fluid transport of supercritical CO2 in enhanced geothermal system (EGS) is studied numerically with local thermal non-equilibrium model, which accounts for the temperature difference between solid matrix and fluid components in porous media and uses two energy equations to describe heat transfer in the solid matrix and in the fluid, respectively. As compared with the previous results of our research group, the effect of local thermal non-equilibrium mainly depends on the volumetric heat transfer coefficient ah, which has a significant effect on the production temperature at reservoir outlet and thermal breakthrough time. The uniformity of volumetricmore » heat transfer coefficient ah has little influence on the thermal breakthrough time, but the temperature difference become more obvious with time after thermal breakthrough with this simulation model. The thermal breakthrough time reduces and the effect of local thermal non-equilibrium becomes significant with decreasing ah.« less

  7. PAT-2 (Plutonium Air-Transportable Model 2) safety analysis report

    SciTech Connect (OSTI)

    Andersen, J.A.; Davis, E.J.; Duffey, T.A.; Dupree, S.A.; George, O.L. Jr.; Ortiz, Z.

    1981-07-01

    The PAT-2 package is designed for the safe transport of plutonium and/or uranium in small quantities. The PAT-2 package is resistant to severe accidents, including that of a high-speed jet aircraft crash, and is designed to withstand such environments as extreme impact, crushing, puncturing and slashing loads, severe hydrocarbon-fueled fires, and deep underwater immersion, with no escape of contents. The package meets the requirements of 10 CFR 71 for Fissile Class I packages with a cargo of 15 grams of Pu-239, or other isotopic forms described herein, not to exceed 2 watts of thermal activity. This SAR presents design and oprational information including evaluations and analyses, test results, operating procedures, maintenance, and quality assurance information.

  8. Internal Domains of Natural Porous Media Revealed: Critical Locations for Transport, Storage, and Chemical Reaction

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zachara, John; Brantley, Sue; Chorover, Jon; Ewing, Robert; Kerisit, Sebastien; Liu, Chongxuan; Perfect, Edmund; Rother, Gernot; Stack, Andrew G.

    2016-02-05

    Internal pore domains exist within rocks, lithic fragments, subsurface sediments, and soil aggregates. These domains, termed internal domains in porous media (IDPM), represent a subset of a material’s porosity, contain a significant fraction of their porosity as nanopores, dominate the reactive surface area of diverse media types, and are important locations for chemical reactivity and fluid storage. IDPM are key features controlling hydrocarbon release from shales in hydraulic fracture systems, organic matter decomposition in soil, weathering and soil formation, and contaminant behavior in the vadose zone and groundwater. It is traditionally difficult to interrogate, advances in instrumentation and imaging methodsmore » are providing new insights on the physical structures and chemical attributes of IDPM, and their contributions to system behaviors. We discuss analytical methods to characterize IDPM, evaluate information on their size distributions, connectivity, and extended structures; determine whether they exhibit unique chemical reactivity; and assess the potential for their inclusion in reactive transport models. Moreover, ongoing developments in measurement technologies and sensitivity, and computer-assisted interpretation will improve understanding of these critical features in the future. Finally, impactful research opportunities exist to advance understanding of IDPM, and to incorporate their effects in reactive transport models for improved environmental simulation and prediction.« less

  9. Macro-System Model for Hydrogen Energy Systems Analysis in Transportation: Preprint

    SciTech Connect (OSTI)

    Diakov, V.; Ruth, M.; Sa, T. J.; Goldsby, M. E.

    2012-06-01

    The Hydrogen Macro System Model (MSM) is a simulation tool that links existing and emerging hydrogen-related models to perform rapid, cross-cutting analysis. It allows analysis of the economics, primary energy-source requirements, and emissions of hydrogen production and delivery pathways.

  10. Simulation of oil-slick transport in Great Lakes connecting channels. Theory and model formulation

    SciTech Connect (OSTI)

    Shen, H.T.; Yapa, P.D.; Petroski, M.E.

    1990-02-01

    Two-dimensional computer models for simulating oil slick movement in rivers and lakes were developed and then applied to the connecting channels of the upper Great Lakes. In these models the oil slick is considered to be a collection of discrete oil patches. The transformation of an oil slick due to advection, spreading, evaporation and dissolution are considered. In open-water regions the advection of oil patches in the slick are determined by the water current and wind using the drifting factor formulation. Formulas consider the balance of inertia, gravity, viscous and surface tension forces. The oil slick transformation model developed in this study contains as many processes as can be effectively and analytically modeled. The model has several special features, including the ability to model instantaneous and continuous spills, the ability to realistically describe the irregular shapes of an oil slick and the ability to account for the time-dependent variation of the flow conditions. The computer programs are designed so that it will be easy to refine the model elements and expand the model to include additional slick transformation processes.

  11. Recent Advances in Detailed Chemical Kinetic Models for Large Hydrocarbon and Biodiesel Transportation Fuels

    SciTech Connect (OSTI)

    Westbrook, C K; Pitz, W J; Curran, H J; Herbinet, O; Mehl, M

    2009-03-30

    n-Hexadecane and 2,2,4,4,6,8,8-heptamethylnonane represent the primary reference fuels for diesel that are used to determine cetane number, a measure of the ignition property of diesel fuel. With the development of chemical kinetics models for these two primary reference fuels for diesel, a new capability is now available to model diesel fuel ignition. Also, we have developed chemical kinetic models for a whole series of large n-alkanes and a large iso-alkane to represent these chemical classes in fuel surrogates for conventional and future fuels. Methyl decanoate and methyl stearate are large methyl esters that are closely related to biodiesel fuels, and kinetic models for these molecules have also been developed. These chemical kinetic models are used to predict the effect of the fuel molecule size and structure on ignition characteristics under conditions found in internal combustion engines.

  12. Canyon Disposal Initiative - Numerical Modeling of Contaminant Transport from Grouted Residual Waste in the 221-U Facility (U Plant)

    SciTech Connect (OSTI)

    Rockhold, Mark L.; White, Mark D.; Freeman, Eugene J.

    2004-10-12

    This letter report documents initial numerical analyses conducted by PNNL to provide support for a feasibility study on decommissioning of the canyon buildings at Hanford. The 221-U facility is the first of the major canyon buildings to be decommissioned. The specific objective of this modeling effort was to provide estimates of potential rates of migration of residual contaminants out of the 221-U facility during the first 40 years after decommissioning. If minimal contaminant migration is predicted to occur from the facility during this time period, then the structure may be deemed to provide a level of groundwater protection that is essentially equivalent to the liner and leachate collection systems that are required at conventional landfills. The STOMP code was used to simulate transport of selected radionuclides out of a canyon building, representative of the 221-U facility after decommissioning, for a period of 40 years. Simulation results indicate that none of the selected radionuclides that were modeled migrated beyond the concrete structure of the facility during the 40-year period of interest. Jacques (2001) identified other potential contaminants in the 221-U facility that were not modeled, however, including kerosene, phenol, and various metals. Modeling of these contaminants was beyond the scope of this preliminary effort due to increased complexity. Simulation results indicate that contaminant release from the canyon buildings will be diffusion controlled at early times. Advection is expected to become much more important at later times, after contaminants have diffused out of the facility and into the surrounding soil environment. After contaminants have diffused out of the facility, surface infiltration covers will become very important for mitigating further transport of contaminants in the underlying vadose zone and groundwater.

  13. Development of Alternate Soil Clean-Up Goals for Hanford Waste Sites Using Fate and Transport Modeling

    SciTech Connect (OSTI)

    Hoover, J.D. [Fluor Hanford, Inc. (United States); McMahon, W.J. [CH2M Hill Hanford Group (United States); Leary, K.D. [DOE/RL (United States)

    2008-07-01

    Remedial Action Goals (RAGs) for soil contaminant levels that are protective of groundwater have been determined for the Removal/Treatment/Disposal (RTD) sites at the 200-UW-1 Operable Unit on the Hanford Site. The RAG values were determined using a methodology involving the back-calculation of soil contaminant levels protective of groundwater (i.e., resulting groundwater concentrations are {<=} MCLs) in conjunction with the fate and transport modeling as a risk-based alternative to the currently prescribed use of background or detection limit default values. This methodology is important for waste management activities at the Hanford Site because it provides risk-based metrics and a technical basis for determining the levels of contamination 'left in place' in the Hanford Site vadose zone that are protective of human health and the environment. The methodology and the use of fate and transport modeling described here comply with federal guidelines for the use of environmental models. This approach is also consistent with one of several allowable methods identified in State guidelines for deriving soil concentrations for ground water protection. Federal and state guidelines recommend the use of site-specific information and data in risk-based assessments of risk and/or protectiveness. The site-specific characteristics of the Hanford Site, which include consideration of the semi-arid climate, an unsaturated zone thickness of over 80 m (262 feet), and associated/other site features and processes, are integral for the risk-based assessments associated with the protection of groundwater pathway. This methodology yields soil cleanup values (RAGs) for the 200-UW-1 OU waste sites selected for the removal/treatment/disposal (RTD) remedy. These proposed RAGs for uranium, nitrate, and technetium-99 are derived from soil concentrations calculated not to cause contamination of groundwater at levels that exceed the ground water MCLs, and are 40 to 200 times greater than

  14. Electron collisions in the trapped gyro-Landau fluid transport model

    SciTech Connect (OSTI)

    Staebler, G. M.; Kinsey, J. E.

    2010-12-15

    Accurately modeling electron collisions in the trapped gyro-Landau fluid (TGLF) equations has been a major challenge. Insights gained from numerically solving the gyrokinetic equation have lead to a significant improvement of the low order TGLF model. The theoretical motivation and verification of this model with the velocity-space gyrokinetic code GYRO[J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] will be presented. The improvement in the fidelity of TGLF to GYRO is shown to also lead to better prediction of experimental temperature profiles by TGLF for a dedicated collision frequency scan.

  15. A Preliminary Analysis of the Economics of Using Distributed Energy as a Source of Reactive Power Supply

    SciTech Connect (OSTI)

    Li, Fangxing; Kueck, John D; Rizy, D Tom; King, Thomas F

    2006-04-01

    the best way to allocate the benefit among customers, utilities, transmission companies or RTOs. With the hidden benefits discovered, it will be easier for the policy maker to re-assess the value of reactive power and to form a sound competitive market for this service. Along with the capability of DE to provide local reactive power, a market needs to exist to promote the operation of DE to regulate voltage and net power factor. There are a number of potential benefits that have been identified including capacity relief, loss reduction, improved system reliability, extended equipment life, reduced transport of reactive power from the G&T, and improved local voltage regulation and power factor. An attempt has been made using very simple data and cases to quantify these benefits. Only the model of a larger and more detailed distribution system with DE can truly give a full picture of the benefits that reactive power from local DE can provide.

  16. MELCOR 1.8.5 modeling aspects of fission product release, transport and deposition an assessment with recommendations.

    SciTech Connect (OSTI)

    Gauntt, Randall O.

    2010-04-01

    The Phebus and VERCORS data have played an important role in contemporary understanding and modeling of fission product release and transport from damaged light water reactor fuel. The data from these test programs have allowed improvement of MELCOR modeling of release and transport processes for both low enrichment uranium fuel as well as high burnup and mixed oxide (MOX) fuels. This paper discusses the synthesis of these findings in the MELCOR severe accident code. Based on recent assessments of MELCOR 1.8.5 fission product release modeling against the Phebus FPT-1 test and on observations from the ISP-46 exercise, modifications to the default MELCOR 1.8.5 release models are recommended. The assessments identified an alternative set of Booth diffusion parameters recommended by ORNL (ORNL-Booth), which produced significantly improved release predictions for cesium and other fission product groups. Some adjustments to the scaling factors in the ORNL-Booth model were made for selected fission product groups, including UO{sub 2}, Mo and Ru in order to obtain better comparisons with the FPT-1 data. The adjusted model, referred to as 'Modified ORNL-Booth,' was subsequently compared to original ORNL VI fission product release experiments and to more recently performed French VERCORS tests, and the comparisons was as favorable or better than the original CORSOR-M MELCOR default release model. These modified ORNL-Booth parameters, input to MELCOR 1.8.5 as 'sensitivity coefficients' (i.e. user input that over-rides the code defaults) are recommended for the interim period until improved release models can be implemented into MELCOR. For the case of ruthenium release in air-oxidizing conditions, some additional modifications to the Ru class vapor pressure are recommended based on estimates of the RuO{sub 2} vapor pressure over mildly hyperstoichiometric UO{sub 2}. The increased vapor pressure for this class significantly increases the net transport of Ru from the fuel to

  17. Model Development and Analysis of the Fate and Transport of Water in a Salt Based Repository

    Broader source: Energy.gov [DOE]

    The study summarizes the initial work on numerical modeling, simulations, and experimental results related to nuclear waste storage in a salt repository.  The study reflects the project's...

  18. Modeling transport and dilution of produced water and the resulting uptake and biomagnification in marine biota

    SciTech Connect (OSTI)

    Rye, H.; Reed, M.; Slagstad, D.

    1996-12-31

    The paper explains the numerical modelling efforts undertaken in order to study possible marine biological impacts caused by releases of produced water from the Haltenbanken area outside the western coast of Norway. Acute effects on marine life from releases of produced water appear to be relatively small and confined to areas rather lose to the release site. Biomagnification may however be experienced for relatively low concentrations at larger distances from the release point. Such effects can he modeled by performing a step-wise approach which includes: The use of 3-D hydrodynamic models to determine the ocean current fields; The use of 3-D multi-source numerical models to determine the concentration fields from the produced water releases, given the current field; and The use of biologic models to simulate the behavior of and larvae (passive marine biota) and fish (active marine biota) and their interaction with the concentration field. The paper explains the experiences gained by using this approach for the calculation of possible influences on marine life below the EC{sub 50} or LC{sub 50} concentration levels. The models are used for simulating concentration fields from 5 simultaneous sources at the Haltenbank area and simulation of magnification in some marine species from 2 simultaneous sources in the same area. Naphthalenes and phenols, which are both present in the produced water, were used as the chemical substances in the simulations.

  19. Modeling the global emission, transport and deposition of trace elements associated with mineral dust

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Y.; Mahowald, N.; Scanza, R.; Journet, E.; Desboeufs, K.; Albani, S.; Kok, J.; Zhuang, G.; Chen, Y.; Cohen, D. D.; et al

    2014-12-17

    Trace element deposition from desert dust has important impacts on ocean primary productivity. In this study, emission inventories for 8 elements, which are primarily of soil origin, Mg, P, Ca, Mn, Fe, K, Al, and Si were determined based on a global mineral dataset and a soils dataset. Datasets of elemental fractions were used to drive the desert dust model in the Community Earth System Model (CESM) in order to simulate the elemental concentrations of atmospheric dust. Spatial variability of mineral dust elemental fractions was evident on a global scale, particularly for Ca. Simulations of global variations in the Camore » / Al ratio, which typically ranged from around 0.1 to 5.0 in soil sources, were consistent with observations, suggesting this ratio to be a good signature for dust source regions. The simulated variable fractions of chemical elements are sufficiently different that estimates of deposition should include elemental variations, especially for Ca, Al and Fe. The model results have been evaluated with observational elemental aerosol concentration data from desert regions and dust events in non-dust regions, providing insights into uncertainties in the modeling approach. The ratios between modeled and observed elemental fractions ranged from 0.7 to 1.6 except for 3.4 and 3.5 for Mg and Mn, respectivly. Using the soil data base improved the correspondence of the spatial hetereogeneity in the modeling of several elements (Ca, Al and Fe) compared to observations. Total and soluble dust associated element fluxes into different ocean basins and ice sheets regions have been estimated, based on the model results. Annual inputs of soluble Mg, P, Ca, Mn, Fe and K associated with dust using mineral dataset were 0.28 Tg, 16.89 Gg, 1.32 Tg, 22.84 Gg, 0.068 Tg, and 0.15 Tg to global oceans and ice sheets.« less

  20. Computational Nanophotonics: modeling optical interactions and transport in tailored nanosystem architectures

    SciTech Connect (OSTI)

    Schatz, George; Ratner, Mark

    2014-02-27

    This report describes research by George Schatz and Mark Ratner that was done over the period 10/03-5/09 at Northwestern University. This research project was part of a larger research project with the same title led by Stephen Gray at Argonne. A significant amount of our work involved collaborations with Gray, and there were many joint publications as summarized later. In addition, a lot of this work involved collaborations with experimental groups at Northwestern, Argonne, and elsewhere. The research was primarily concerned with developing theory and computational methods that can be used to describe the interaction of light with noble metal nanoparticles (especially silver) that are capable of plasmon excitation. Classical electrodynamics provides a powerful approach for performing these studies, so much of this research project involved the development of methods for solving Maxwell’s equations, including both linear and nonlinear effects, and examining a wide range of nanostructures, including particles, particle arrays, metal films, films with holes, and combinations of metal nanostructures with polymers and other dielectrics. In addition, our work broke new ground in the development of quantum mechanical methods to describe plasmonic effects based on the use of time dependent density functional theory, and we developed new theory concerned with the coupling of plasmons to electrical transport in molecular wire structures. Applications of our technology were aimed at the development of plasmonic devices as components of optoelectronic circuits, plasmons for spectroscopy applications, and plasmons for energy-related applications.

  1. Modelling radionuclide transport in fractured media with a dynamic update of Kd values

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Trinchero, Paolo; Painter, Scott L.; Ebrahimi, Hedieh; Koskinen, Lasse; Molinero, Jorge; Selroos, Jan -Olof

    2015-10-13

    Radionuclide transport in fractured crystalline rocks is a process of interest in evaluating long term safety of potential disposal systems for radioactive wastes. Given their numerical efficiency and the absence of numerical dispersion, Lagrangian methods (e.g. particle tracking algorithms) are appealing approaches that are often used in safety assessment (SA) analyses. In these approaches, many complex geochemical retention processes are typically lumped into a single parameter: the distribution coefficient (Kd). Usually, the distribution coefficient is assumed to be constant over the time frame of interest. However, this assumption could be critical under long-term geochemical changes as it is demonstrated thatmore » the distribution coefficient depends on the background chemical conditions (e.g. pH, Eh, and major chemistry). In this study, we provide a computational framework that combines the efficiency of Lagrangian methods with a sound and explicit description of the geochemical changes of the site and their influence on the radionuclide retention properties.« less

  2. EBS Radionuclide Transport Abstraction

    SciTech Connect (OSTI)

    J. Prouty

    2006-07-14

    The purpose of this report is to develop and analyze the engineered barrier system (EBS) radionuclide transport abstraction model, consistent with Level I and Level II model validation, as identified in Technical Work Plan for: Near-Field Environment and Transport: Engineered Barrier System: Radionuclide Transport Abstraction Model Report Integration (BSC 2005 [DIRS 173617]). The EBS radionuclide transport abstraction (or EBS RT Abstraction) is the conceptual model used in the total system performance assessment (TSPA) to determine the rate of radionuclide releases from the EBS to the unsaturated zone (UZ). The EBS RT Abstraction conceptual model consists of two main components: a flow model and a transport model. Both models are developed mathematically from first principles in order to show explicitly what assumptions, simplifications, and approximations are incorporated into the models used in the TSPA. The flow model defines the pathways for water flow in the EBS and specifies how the flow rate is computed in each pathway. Input to this model includes the seepage flux into a drift. The seepage flux is potentially split by the drip shield, with some (or all) of the flux being diverted by the drip shield and some passing through breaches in the drip shield that might result from corrosion or seismic damage. The flux through drip shield breaches is potentially split by the waste package, with some (or all) of the flux being diverted by the waste package and some passing through waste package breaches that might result from corrosion or seismic damage. Neither the drip shield nor the waste package survives an igneous intrusion, so the flux splitting submodel is not used in the igneous scenario class. The flow model is validated in an independent model validation technical review. The drip shield and waste package flux splitting algorithms are developed and validated using experimental data. The transport model considers advective transport and diffusive transport

  3. Comparison of bifurcation dynamics of turbulent transport models for the L-H transition

    SciTech Connect (OSTI)

    Weymiens, W. Blank, H. J. de; Hogeweij, G. M. D.; Paquay, S.

    2014-05-15

    In more than three decades, a large amount of models and mechanisms have been proposed to describe a very beneficial feature of magnetically confined fusion plasmas: the L-H transition. Bifurcation theory can be used to compare these different models based on their dynamical transition structure. In this paper, we employ bifurcation theory to distinguish two fundamentally different descriptions of the interaction between turbulence levels and sheared flows. The analytic bifurcation analysis characterises the parameter space structure of the transition dynamics. Herewith, in these models three dynamically different types of transitions are characterised, sharp transitions, oscillatory transitions, and smooth transitions. One of the two models has a very robust transition structure and is therefore likely to be more accurate for such a robust phenomenon as the L-H transition. The other model needs more fine-tuning to get non-oscillatory transitions. These conclusions from the analytic bifurcation analysis are confirmed by dedicated numerical simulations, with the newly developed code Bifurcator.

  4. A Reduced-Order Model of Transport Phenomena for Power Plant Simulation

    SciTech Connect (OSTI)

    Paul Cizmas; Brian Richardson; Thomas Brenner; Raymond Fontenot

    2009-09-30

    A reduced-order model based on proper orthogonal decomposition (POD) has been developed to simulate transient two- and three-dimensional isothermal and non-isothermal flows in a fluidized bed. Reduced-order models of void fraction, gas and solids temperatures, granular energy, and z-direction gas and solids velocity have been added to the previous version of the code. These algorithms are presented and their implementation is discussed. Verification studies are presented for each algorithm. A number of methods to accelerate the computations performed by the reduced-order model are presented. The errors associated with each acceleration method are computed and discussed. Using a combination of acceleration methods, a two-dimensional isothermal simulation using the reduced-order model is shown to be 114 times faster than using the full-order model. In the pursue of achieving the objectives of the project and completing the tasks planned for this program, several unplanned and unforeseen results, methods and studies have been generated. These additional accomplishments are also presented and they include: (1) a study of the effect of snapshot sampling time on the computation of the POD basis functions, (2) an investigation of different strategies for generating the autocorrelation matrix used to find the POD basis functions, (3) the development and implementation of a bubble detection and tracking algorithm based on mathematical morphology, (4) a method for augmenting the proper orthogonal decomposition to better capture flows with discontinuities, such as bubbles, and (5) a mixed reduced-order/full-order model, called point-mode proper orthogonal decomposition, designed to avoid unphysical due to approximation errors. The limitations of the proper orthogonal decomposition method in simulating transient flows with moving discontinuities, such as bubbling flows, are discussed and several methods are proposed to adapt the method for future use.

  5. Lattice Boltzmann simulation of solute transport in heterogeneous porous media with conduits to estimate macroscopic continuous time random walk model parameters

    SciTech Connect (OSTI)

    Anwar, S.; Cortis, A.; Sukop, M.

    2008-10-20

    Lattice Boltzmann models simulate solute transport in porous media traversed by conduits. Resulting solute breakthrough curves are fitted with Continuous Time Random Walk models. Porous media are simulated by damping flow inertia and, when the damping is large enough, a Darcy's Law solution instead of the Navier-Stokes solution normally provided by the lattice Boltzmann model is obtained. Anisotropic dispersion is incorporated using a direction-dependent relaxation time. Our particular interest is to simulate transport processes outside the applicability of the standard Advection-Dispersion Equation (ADE) including eddy mixing in conduits. The ADE fails to adequately fit any of these breakthrough curves.

  6. Modeling the global emission, transport and deposition of trace elements associated with mineral dust

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Y.; Mahowald, N.; Scanza, R. A.; Journet, E.; Desboeufs, K.; Albani, S.; Kok, J. F.; Zhuang, G.; Chen, Y.; Cohen, D. D.; et al

    2015-10-12

    Trace element deposition from desert dust has important impacts on ocean primary productivity, the quantification of which could be useful in determining the magnitude and sign of the biogeochemical feedback on radiative forcing. However, the impact of elemental deposition to remote ocean regions is not well understood and is not currently included in global climate models. In this study, emission inventories for eight elements primarily of soil origin, Mg, P, Ca, Mn, Fe, K, Al, and Si are determined based on a global mineral data set and a soil data set. The resulting elemental fractions are used to drive themore » desert dust model in the Community Earth System Model (CESM) in order to simulate the elemental concentrations of atmospheric dust. Spatial variability of mineral dust elemental fractions is evident on a global scale, particularly for Ca. Simulations of global variations in the Ca / Al ratio, which typically range from around 0.1 to 5.0 in soils, are consistent with observations, suggesting that this ratio is a good signature for dust source regions. The simulated variable fractions of chemical elements are sufficiently different; estimates of deposition should include elemental variations, especially for Ca, Al and Fe. The model results have been evaluated with observations of elemental aerosol concentrations from desert regions and dust events in non-dust regions, providing insights into uncertainties in the modeling approach. The ratios between modeled and observed elemental fractions range from 0.7 to 1.6, except for Mg and Mn (3.4 and 3.5, respectively). Using the soil database improves the correspondence of the spatial heterogeneity in the modeling of several elements (Ca, Al and Fe) compared to observations. Total and soluble dust element fluxes to different ocean basins and ice sheet regions have been estimated, based on the model results. The annual inputs of soluble Mg, P, Ca, Mn, Fe and K associated with dust using the mineral data set are

  7. Combined Estimation of Hydrogeologic Conceptual Model, Parameter, and Scenario Uncertainty with Application to Uranium Transport at the Hanford Site 300 Area

    SciTech Connect (OSTI)

    Meyer, Philip D.; Ye, Ming; Rockhold, Mark L.; Neuman, Shlomo P.; Cantrell, Kirk J.

    2007-07-30

    This report to the Nuclear Regulatory Commission (NRC) describes the development and application of a methodology to systematically and quantitatively assess predictive uncertainty in groundwater flow and transport modeling that considers the combined impact of hydrogeologic uncertainties associated with the conceptual-mathematical basis of a model, model parameters, and the scenario to which the model is applied. The methodology is based on a n extension of a Maximum Likelihood implementation of Bayesian Model Averaging. Model uncertainty is represented by postulating a discrete set of alternative conceptual models for a site with associated prior model probabilities that reflect a belief about the relative plausibility of each model based on its apparent consistency with available knowledge and data. Posterior model probabilities are computed and parameter uncertainty is estimated by calibrating each model to observed system behavior; prior parameter estimates are optionally included. Scenario uncertainty is represented as a discrete set of alternative future conditions affecting boundary conditions, source/sink terms, or other aspects of the models, with associated prior scenario probabilities. A joint assessment of uncertainty results from combining model predictions computed under each scenario using as weight the posterior model and prior scenario probabilities. The uncertainty methodology was applied to modeling of groundwater flow and uranium transport at the Hanford Site 300 Area. Eight alternative models representing uncertainty in the hydrogeologic and geochemical properties as well as the temporal variability were considered. Two scenarios represent alternative future behavior of the Columbia River adjacent to the site were considered. The scenario alternatives were implemented in the models through the boundary conditions. Results demonstrate the feasibility of applying a comprehensive uncertainty assessment to large-scale, detailed groundwater flow

  8. Low Cost Non-Reactive

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Prepared: 10/28/09 Low Cost Non-Reactive Coating for Refractory Metals A non-reactive coating for refractory metals has been developed at The Ames Laboratory. Contamination of rare earth and reactive metals and their alloys has been a chronic problem that results from their interaction with the crucibles or other vessels used in high temperature processing or during other applications. As a consequence, processing and other costs are high due to the need to replace equipment or containers, or

  9. A CFD-based wind solver for a fast response transport and dispersion model

    SciTech Connect (OSTI)

    Gowardhan, Akshay A; Brown, Michael J; Pardyjak, Eric R; Senocak, Inanc

    2010-01-01

    In many cities, ambient air quality is deteriorating leading to concerns about the health of city inhabitants. In urban areas with narrow streets surrounded by clusters of tall buildings, called street canyons, air pollution from traffic emissions and other sources is difficult to disperse and may accumulate resulting in high pollutant concentrations. For various situations, including the evacuation of populated areas in the event of an accidental or deliberate release of chemical, biological and radiological agents, it is important that models should be developed that produce urban flow fields quickly. For these reasons it has become important to predict the flow field in urban street canyons. Various computational techniques have been used to calculate these flow fields, but these techniques are often computationally intensive. Most fast response models currently in use are at a disadvantage in these cases as they are unable to correlate highly heterogeneous urban structures with the diagnostic parameterizations on which they are based. In this paper, a fast and reasonably accurate computational fluid dynamics (CFD) technique that solves the Navier-Stokes equations for complex urban areas has been developed called QUIC-CFD (Q-CFD). This technique represents an intermediate balance between fast (on the order of minutes for a several block problem) and reasonably accurate solutions. The paper details the solution procedure and validates this model for various simple and complex urban geometries.

  10. WaterTransport in PEM Fuel Cells: Advanced Modeling, Material Selection, Testing and Design Optimization

    SciTech Connect (OSTI)

    J. Vernon Cole; Abhra Roy; Ashok Damle; Hari Dahr; Sanjiv Kumar; Kunal Jain; Ned Djilai

    2012-10-02

    Water management in Proton Exchange Membrane, PEM, Fuel Cells is challenging because of the inherent conflicts between the requirements for efficient low and high power operation. Particularly at low powers, adequate water must be supplied to sufficiently humidify the membrane or protons will not move through it adequately and resistance losses will decrease the cell efficiency. At high power density operation, more water is produced at the cathode than is necessary for membrane hydration. This excess water must be removed effectively or it will accumulate in the Gas Diffusion Layers, GDLs, between the gas channels and catalysts, blocking diffusion paths for reactants to reach the catalysts and potentially flooding the electrode. As power density of the cells is increased, the challenges arising from water management are expected to become more difficult to overcome simply due to the increased rate of liquid water generation relative to fuel cell volume. Thus, effectively addressing water management based issues is a key challenge in successful application of PEMFC systems. In this project, CFDRC and our partners used a combination of experimental characterization, controlled experimental studies of important processes governing how water moves through the fuel cell materials, and detailed models and simulations to improve understanding of water management in operating hydrogen PEM fuel cells. The characterization studies provided key data that is used as inputs to all state-of-the-art models for commercially important GDL materials. Experimental studies and microscopic scale models of how water moves through the GDLs showed that the water follows preferential paths, not branching like a river, as it moves toward the surface of the material. Experimental studies and detailed models of water and airflow in fuel cells channels demonstrated that such models can be used as an effective design tool to reduce operating pressure drop in the channels and the associated

  11. Comparing three vegetation monoterpene emission models to measured gas concentrations with a model of meteorology, air chemistry and chemical transport

    SciTech Connect (OSTI)

    Smolander, S.; He, Q.; Mogensen, Ditte; Zhou, L.; Back, J.; Ruuskanen, T.; Noe, S.; Guenther, Alex B.; Aaltonen, H.; Kulmala, M.; Boy, Michael

    2014-10-07

    Biogenic volatile organic compounds (BVOCs) are essential in atmospheric chemistry because of their chemical reactions that produce and destroy tropospheric ozone, their effects on aerosol formation and growth, and their potential influence on global warming. As one of the important BVOC groups, monoterpenes have been a focus of scientific attention in atmospheric research. Detailed regional measurements and model estimates are needed to study emission potential and the monoterpene budget on a global scale. Since the use of empirical measurements for upscaling is limited by many physical and biological factors such as genetic variation, temperature and light, water availability, seasonal changes, and environmental stresses, comprehensive inventories over larger areas are difficult to obtain.

  12. Lipid-Based Nanodiscs as Models for Studying Mesoscale Coalescence A Transport Limited Case

    SciTech Connect (OSTI)

    Hu, Andrew; Fan, Tai-Hsi; Katsaras, John; Xia, Yan; Li, Ming; Nieh, Mu-Ping

    2014-01-01

    Lipid-based nanodiscs (bicelles) are able to form in mixtures of long- and short-chain lipids. Initially, they are of uniform size but grow upon dilution. Previously, nanodisc growth kinetics have been studied using time-resolved small angle neutron scattering (SANS), a technique which is not well suited for probing their change in size immediately after dilution. To address this, we have used dynamic light scattering (DLS), a technique which permits the collection of useful data in a short span of time after dilution of the system. The DLS data indicate that the negatively charged lipids in nanodiscs play a significant role in disc stability and growth. Specifically, the charged lipids are most likely drawn out from the nanodiscs into solution, thereby reducing interparticle repulsion and enabling the discs to grow. We describe a population balance model, which takes into account Coulombic interactions and adequately predicts the initial growth of nanodiscs with a single parameter i.e., surface potential. The results presented here strongly support the notion that the disc coalescence rate strongly depends on nanoparticle charge density. The present system containing low-polydispersity lipid nanodiscs serves as a good model for understanding how charged discoidal micelles coalesce.

  13. Survey and discussion of models applicable to the transport and fate thrust area of the Department of Energy Chemical and Biological Nonproliferation Program

    SciTech Connect (OSTI)

    1997-09-01

    The availability and easy production of toxic chemical and biological agents by domestic and international terrorists pose a serious threat to US national security, especially to civilian populations in and around urban areas. To address this threat, the Department of Energy (DOE) has established the Chemical and Biological Nonproliferation Program (CBNP) with the goal of focusing the DOE`s technical resources and expertise on capabilities to deny, deter, mitigate and respond to clandestine releases of chemical and biological agents. With the intent to build on DOE core competencies, the DOE has established six technology thrust areas within the CBNP Program: Biological Information Resources; Point Sensor Systems; Stand-off Detection; Transport and Fate; Decontamination; and Systems Analysis and Integration. The purpose of the Transport and Fate Thrust is to accurately predict the dispersion, concentration and ultimate fate of chemical and biological agents released into the urban and suburban environments and has two major goals: (1) to develop an integrated and validated state-of-the-art atmospheric transport and fate modeling capability for chemical and biological agent releases within the complex urban environment from the regional scale down to building and subway interiors, and (2) to apply this modeling capability in a broad range of simulation case studies of chemical and biological agent release scenarios in suburban, urban and confined (buildings and subways) environments and provide analysis for the incident response user community. Sections of this report discuss subway transport and fate models; buildings interior transport and fate modeling; models for flow and transport around buildings; and local-regional meteorology and dispersion models.

  14. A coupled transport and solid mechanics formulation with improved reaction kinetics parameters for modeling oxidation and decomposition in a uranium hydride bed.

    SciTech Connect (OSTI)

    Salloum, Maher N.; Shugard, Andrew D.; Kanouff, Michael P.; Gharagozloo, Patricia E.

    2013-03-01

    Modeling of reacting flows in porous media has become particularly important with the increased interest in hydrogen solid-storage beds. An advanced type of storage bed has been proposed that utilizes oxidation of uranium hydride to heat and decompose the hydride, releasing the hydrogen. To reduce the cost and time required to develop these systems experimentally, a valid computational model is required that simulates the reaction of uranium hydride and oxygen gas in a hydrogen storage bed using multiphysics finite element modeling. This SAND report discusses the advancements made in FY12 (since our last SAND report SAND2011-6939) to the model developed as a part of an ASC-P&EM project to address the shortcomings of the previous model. The model considers chemical reactions, heat transport, and mass transport within a hydride bed. Previously, the time-varying permeability and porosity were considered uniform. This led to discrepancies between the simulated results and experimental measurements. In this work, the effects of non-uniform changes in permeability and porosity due to phase and thermal expansion are accounted for. These expansions result in mechanical stresses that lead to bed deformation. To describe this, a simplified solid mechanics model for the local variation of permeability and porosity as a function of the local bed deformation is developed. By using this solid mechanics model, the agreement between our reacting bed model and the experimental data is improved. Additionally, more accurate uranium hydride oxidation kinetics parameters are obtained by fitting the experimental results from a pure uranium hydride oxidation measurement to the ones obtained from the coupled transport-solid mechanics model. Finally, the coupled transport-solid mechanics model governing equations and boundary conditions are summarized and recommendations are made for further development of ARIA and other Sandia codes in order for them to sufficiently implement the model.

  15. Bayesian data assimilation for stochastic multiscale models of transport in porous media.

    SciTech Connect (OSTI)

    Marzouk, Youssef M.; van Bloemen Waanders, Bart Gustaaf; Parno, Matthew; Ray, Jaideep; Lefantzi, Sophia; Salazar, Luke; McKenna, Sean Andrew; Klise, Katherine A.

    2011-10-01

    We investigate Bayesian techniques that can be used to reconstruct field variables from partial observations. In particular, we target fields that exhibit spatial structures with a large spectrum of lengthscales. Contemporary methods typically describe the field on a grid and estimate structures which can be resolved by it. In contrast, we address the reconstruction of grid-resolved structures as well as estimation of statistical summaries of subgrid structures, which are smaller than the grid resolution. We perform this in two different ways (a) via a physical (phenomenological), parameterized subgrid model that summarizes the impact of the unresolved scales at the coarse level and (b) via multiscale finite elements, where specially designed prolongation and restriction operators establish the interscale link between the same problem defined on a coarse and fine mesh. The estimation problem is posed as a Bayesian inverse problem. Dimensionality reduction is performed by projecting the field to be inferred on a suitable orthogonal basis set, viz. the Karhunen-Loeve expansion of a multiGaussian. We first demonstrate our techniques on the reconstruction of a binary medium consisting of a matrix with embedded inclusions, which are too small to be grid-resolved. The reconstruction is performed using an adaptive Markov chain Monte Carlo method. We find that the posterior distributions of the inferred parameters are approximately Gaussian. We exploit this finding to reconstruct a permeability field with long, but narrow embedded fractures (which are too fine to be grid-resolved) using scalable ensemble Kalman filters; this also allows us to address larger grids. Ensemble Kalman filtering is then used to estimate the values of hydraulic conductivity and specific yield in a model of the High Plains Aquifer in Kansas. Strong conditioning of the spatial structure of the parameters and the non-linear aspects of the water table aquifer create difficulty for the ensemble Kalman

  16. A Radiative Transport Model for Heating Paints using High Density Plasma Arc Lamps

    SciTech Connect (OSTI)

    Sabau, Adrian S; Duty, Chad E; Dinwiddie, Ralph Barton; Nichols, Mark; Blue, Craig A; Ott, Ronald D

    2009-01-01

    The energy distribution and ensuing temperature evolution within paint-like systems under the influence of infrared radiation was studied. Thermal radiation effects as well as those due to heat conduction were considered. A complete set of material properties was derived and discussed. Infrared measurements were conducted to obtain experimental data for the temperature in the paint film. The heat flux of the incident radiation from the plasma arc lamp was measured using a heat flux sensor with a very short response time. The comparison between the computed and experimental results for temperature show that the models that are based on spectral four-flux RTE and accurate optical properties yield accurate results for the black paint systems.

  17. Neutron Radiography Reactor Reactivity -- Focused Lessons Learned

    SciTech Connect (OSTI)

    Eric Woolstenhulme; Randal Damiana; Kenneth Schreck; Ann Marie Phillips; Dana Hewit

    2010-11-01

    As part of the Global Threat Reduction Initiative, the Neutron Radiography Reactor (NRAD) at the Idaho National Laboratory (INL) was converted from using highly enriched uranium (HEU) to low enriched uranium (LEU) fuel. After the conversion, NRAD resumed operations and is meeting operational requirements. Radiography image quality and the number of images that can be produced in a given time frame match pre-conversion capabilities. However, following the conversion, NRADs excess reactivity with the LEU fuel was less than it had been with the HEU fuel. Although some differences between model predictions and actual performance are to be expected, the lack of flexibility in NRADs safety documentation prevented adjusting the reactivity by adding more fuel, until the safety documentation could be modified. To aid future reactor conversions, a reactivity-focused Lessons Learned meeting was held. This report summarizes the findings of the lessons learned meeting and addresses specific questions posed by DOE regarding NRADs conversion and reactivity.

  18. Regional respiratory tract absorption of inhaled reactive gases

    SciTech Connect (OSTI)

    Miller, F.J.; Overton, J.H.; Kimbell, J.S.; Russell, M.L.

    1992-06-29

    Highly reactive gases present unique problems due to the number of factors which must be taken into account to determine regional respiratory tract uptake. The authors reviewed some of the physical, chemical, and biological factors that affect dose and that must be understood to interpret toxicological data, to evaluate experimental dosimetry studies, and to develop dosimetry models. Selected dosimetry experiments involving laboratory animals and humans were discussed, showing the variability and uptake according to animal species and respiratory tract region for various reactive gases. New experimental dosimetry approaches, such as those involving isotope ratio mass spectroscopy and cyclotron generation reactive gases, were discussed that offer great promise for improving the ability to study regional respiratory tract absorption of reactive gases. Various dosimetry modeling applications were discussed which demonstrate: the importance of airflow patterns for site-specific dosimetry in the upper respiratory tract, the influence of the anatomical model used to make inter- and intraspecies dosimetric comparisons, the influence of tracheobronchial path length on predicted dose curves, and the implications of ventilatory unit structure and volume on dosimetry and response. Collectively, these examples illustrate important aspects of regional respiratory tract absorption of inhaled reactive gases. Given the complex nature of extent and pattern of injury in the respiratory tract from exposure to reactive gases, understanding interspecies differences in the absorption of reactive gases will continue to be an important area for study.

  19. A Tariff for Reactive Power

    SciTech Connect (OSTI)

    Kueck, John D; Kirby, Brendan J; Li, Fangxing; Tufon, Christopher; Isemonger, Alan

    2008-07-01

    Two kinds of power are required to operate an electric power system: real power, measured in watts, and reactive power, measured in volt-amperes reactive or VARs. Reactive power supply is one of a class of power system reliability services collectively known as ancillary services, and is essential for the reliable operation of the bulk power system. Reactive power flows when current leads or lags behind voltage. Typically, the current in a distribution system lags behind voltage because of inductive loads such as motors. Reactive power flow wastes energy and capacity and causes voltage droop. To correct lagging power flow, leading reactive power (current leading voltage) is supplied to bring the current into phase with voltage. When the current is in phase with voltage, there is a reduction in system losses, an increase in system capacity, and a rise in voltage. Reactive power can be supplied from either static or dynamic VAR sources. Static sources are typically transmission and distribution equipment, such as capacitors at substations, and their cost has historically been included in the revenue requirement of the transmission operator (TO), and recovered through cost-of-service rates. By contrast, dynamic sources are typically generators capable of producing variable levels of reactive power by automatically controlling the generator to regulate voltage. Transmission system devices such as synchronous condensers can also provide dynamic reactive power. A class of solid state devices (called flexible AC transmission system devices or FACTs) can provide dynamic reactive power. One specific device has the unfortunate name of static VAR compensator (SVC), where 'static' refers to the solid state nature of the device (it does not include rotating equipment) and not to the production of static reactive power. Dynamic sources at the distribution level, while more costly would be very useful in helping to regulate local voltage. Local voltage regulation would reduce

  20. Transportation Sector Module - NEMS Documentation

    Reports and Publications (EIA)

    2014-01-01

    Documents the objectives, analytical approach and development of the National Energy Modeling System (NEMS) Transportation Model (TRAN). The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated by the model.

  1. Transportation Infrastructure

    Office of Environmental Management (EM)

    09 Archive Transportation Fact of the Week - 2009 Archive #603 Where Does Lithium Come From? December 28, 2009 #602 Freight Statistics by Mode, 2007 Commodity Flow Survey December 21, 2009 #601 World Motor Vehicle Production December 14, 2009 #600 China Produced More Vehicles than the U.S. in 2008 December 7, 2009 #599 Historical Trend for Light Vehicle Sales November 30, 2009 #598 Hybrid Vehicle Sales by Model November 23, 2009 #597 Median Age of Cars and Trucks Rising in 2008 November 16, 2009

  2. Radiation Transport

    SciTech Connect (OSTI)

    Urbatsch, Todd James

    2015-06-15

    We present an overview of radiation transport, covering terminology, blackbody raditation, opacities, Boltzmann transport theory, approximations to the transport equation. Next we introduce several transport methods. We present a section on Caseology, observing transport boundary layers. We briefly broach topics of software development, including verification and validation, and we close with a section on high energy-density experiments that highlight and support radiation transport.

  3. Anion Exchange Membranes - Transport/Conductivity

    Broader source: Energy.gov (indexed) [DOE]

    transport * Computational Modeling * MORPHOLOGYCHEMISTRY * Vibrational Spectroscopy: FTIR, Raman * Scattering: SANS, SAXS * Crystallinity WAXSXRD * Microscopy * ...

  4. BEST (Battery Economics for more Sustainable Transportation)

    Energy Science and Technology Software Center (OSTI)

    2009-12-31

    Computer software for the simulation of battery economics based on various transportation business models.

  5. Estimates of Radioxenon Released from Southern Hemisphere Medical isotope Production Facilities Using Measured Air Concentrations and Atmospheric Transport Modeling

    SciTech Connect (OSTI)

    Eslinger, Paul W.; Friese, Judah I.; Lowrey, Justin D.; McIntyre, Justin I.; Miley, Harry S.; Schrom, Brian T.

    2014-09-01

    Abstract The International Monitoring System (IMS) of the Comprehensive-Nuclear-Test-Ban-Treaty monitors the atmosphere for radioactive xenon leaking from underground nuclear explosions. Emissions from medical isotope production represent a challenging background signal when determining whether measured radioxenon in the atmosphere is associated with a nuclear explosion prohibited by the treaty. The Australian Nuclear Science and Technology Organisation (ANSTO) operates a reactor and medical isotope production facility in Lucas Heights, Australia. This study uses two years of release data from the ANSTO medical isotope production facility and Xe-133 data from three IMS sampling locations to estimate the annual releases of Xe-133 from medical isotope production facilities in Argentina, South Africa, and Indonesia. Atmospheric dilution factors derived from a global atmospheric transport model were used in an optimization scheme to estimate annual release values by facility. The annual releases of about 6.8×1014 Bq from the ANSTO medical isotope production facility are in good agreement with the sampled concentrations at these three IMS sampling locations. Annual release estimates for the facility in South Africa vary from 1.2×1016 to 2.5×1016 Bq and estimates for the facility in Indonesia vary from 6.1×1013 to 3.6×1014 Bq. Although some releases from the facility in Argentina may reach these IMS sampling locations, the solution to the objective function is insensitive to the magnitude of those releases.

  6. Chamber transport

    SciTech Connect (OSTI)

    OLSON,CRAIG L.

    2000-05-17

    Heavy ion beam transport through the containment chamber plays a crucial role in all heavy ion fusion (HIF) scenarios. Here, several parameters are used to characterize the operating space for HIF beams; transport modes are assessed in relation to evolving target/accelerator requirements; results of recent relevant experiments and simulations of HIF transport are summarized; and relevant instabilities are reviewed. All transport options still exist, including (1) vacuum ballistic transport, (2) neutralized ballistic transport, and (3) channel-like transport. Presently, the European HIF program favors vacuum ballistic transport, while the US HIF program favors neutralized ballistic transport with channel-like transport as an alternate approach. Further transport research is needed to clearly guide selection of the most attractive, integrated HIF system.

  7. Reactive geochemical transport simulation to study mineral trapping...

    Office of Scientific and Technical Information (OSTI)

    ... Authors: Xu, Tianfu ; Apps, John A. ; Pruess, Karsten Publication Date: 2002-04-01 OSTI Identifier: 801952 Report Number(s): LBNL--50089 R&D Project: 468111; B& R KC0403010; TRN: ...

  8. Fuel Temperature Coefficient of Reactivity

    SciTech Connect (OSTI)

    Loewe, W.E.

    2001-07-31

    A method for measuring the fuel temperature coefficient of reactivity in a heterogeneous nuclear reactor is presented. The method, which is used during normal operation, requires that calibrated control rods be oscillated in a special way at a high reactor power level. The value of the fuel temperature coefficient of reactivity is found from the measured flux responses to these oscillations. Application of the method in a Savannah River reactor charged with natural uranium is discussed.

  9. Stochastic Analysis of Advection-diffusion-Reactive Systems with Applications to Reactive Transport in Porous Media

    SciTech Connect (OSTI)

    Tartakovsky, Daniel

    2013-08-30

    We developed new CDF and PDF methods for solving non-linear stochastic hyperbolic equations that does not rely on linearization approximations and allows for rigorous formulation of the boundary conditions.

  10. Feed gas contaminant removal in ion transport membrane systems

    DOE Patents [OSTI]

    Underwood, Richard Paul; Makitka, III, Alexander; Carolan, Michael Francis

    2012-04-03

    An oxygen ion transport membrane process wherein a heated oxygen-containing gas having one or more contaminants is contacted with a reactive solid material to remove the one or more contaminants. The reactive solid material is provided as a deposit on a support. The one or more contaminant compounds in the heated oxygen-containing gas react with the reactive solid material. The contaminant-depleted oxygen-containing gas is contacted with a membrane, and oxygen is transported through the membrane to provide transported oxygen.

  11. The diffusion approximation versus the telegraph equation for modeling solar energetic particle transport with adiabatic focusing. I. Isotropic pitch-angle scattering

    SciTech Connect (OSTI)

    Effenberger, Frederic; Litvinenko, Yuri E.

    2014-03-01

    The diffusion approximation to the Fokker-Planck equation is commonly used to model the transport of solar energetic particles in interplanetary space. In this study, we present exact analytical predictions of a higher order telegraph approximation for particle transport and compare them with the corresponding predictions of the diffusion approximation and numerical solutions of the full Fokker-Planck equation. We specifically investigate the role of the adiabatic focusing effect of a spatially varying magnetic field on an evolving particle distribution. Comparison of the analytical and numerical results shows that the telegraph approximation reproduces the particle intensity profiles much more accurately than does the diffusion approximation, especially when the focusing is strong. However, the telegraph approximation appears to offer no significant advantage over the diffusion approximation for calculating the particle anisotropy. The telegraph approximation can be a useful tool for describing both diffusive and wave-like aspects of the cosmic-ray transport.

  12. Full-f Neoclassical Simulations toward a Predictive Model for H-mode Pedestal Ion Energy, Particle and Momentum Transport

    SciTech Connect (OSTI)

    Battaglia, D. J.; Boedo, J. A.; Burrell, K. H.; Chang, C. S.; Canik, J. M.; deGrassie, J. S.; Gerhardt, S. P.; Grierson, B. A.; Groebner, R. J.; Maingi, Rajesh; Smith, S. P.

    2014-09-01

    Energy and particle transport rates are decoupled in the H-mode edge since the ion thermal transport rate is primarily set by the neoclassical transport of the deuterium ions in the tail of the thermal energy distribution, while the net particle transport rate is set by anomalous transport of the colder bulk ions. Ion orbit loss drives the energy distributions away from Maxwellian, and describes the anisotropy, poloidal asymmetry and local minimum near the separatrix observed in the Ti profile. Non-Maxwellian distributions also drive large intrinsic edge flows, and the interaction of turbulence at the top of the pedestal with the intrinsic edge flow can generate an intrinsic core torque. The primary driver of the radial electric field (Er) in the pedestal and scrapeoff layer (SOL) are kinetic neoclassical effects, such as ion orbit loss of tail ions and parallel electron loss to the divertor. This paper describes the first multi-species kinetic neoclassical transport calculations for ELM-free H-mode pedestal and scrape-off layer on DIII-D using XGC0, a 5D full-f particle-in-cell drift-kinetic solver with self-consistent neutral recycling and sheath potentials. Quantitative agreement between the flux-driven simulation and the experimental electron density, impurity density and orthogonal measurements of impurity temperature and flow profiles is achieved by adding random-walk particle diffusion to the guiding-center drift motion. This interpretative technique quantifies the role of neoclassical, anomalous and neutral transport to the overall pedestal structure, and consequently illustrates the importance of including kinetic effects self-consistently in transport calculations around transport barriers.

  13. Hydrogen transport in composite inorganic membranes (Journal...

    Office of Scientific and Technical Information (OSTI)

    Hydrogen transport in composite inorganic membranes Citation Details In-Document Search Title: Hydrogen transport in composite inorganic membranes A theoretical model simulating ...

  14. EBS Radionuclide Transport Abstraction

    SciTech Connect (OSTI)

    J.D. Schreiber

    2005-08-25

    The purpose of this report is to develop and analyze the engineered barrier system (EBS) radionuclide transport abstraction model, consistent with Level I and Level II model validation, as identified in ''Technical Work Plan for: Near-Field Environment and Transport: Engineered Barrier System: Radionuclide Transport Abstraction Model Report Integration'' (BSC 2005 [DIRS 173617]). The EBS radionuclide transport abstraction (or EBS RT Abstraction) is the conceptual model used in the total system performance assessment for the license application (TSPA-LA) to determine the rate of radionuclide releases from the EBS to the unsaturated zone (UZ). The EBS RT Abstraction conceptual model consists of two main components: a flow model and a transport model. Both models are developed mathematically from first principles in order to show explicitly what assumptions, simplifications, and approximations are incorporated into the models used in the TSPA-LA. The flow model defines the pathways for water flow in the EBS and specifies how the flow rate is computed in each pathway. Input to this model includes the seepage flux into a drift. The seepage flux is potentially split by the drip shield, with some (or all) of the flux being diverted by the drip shield and some passing through breaches in the drip shield that might result from corrosion or seismic damage. The flux through drip shield breaches is potentially split by the waste package, with some (or all) of the flux being diverted by the waste package and some passing through waste package breaches that might result from corrosion or seismic damage. Neither the drip shield nor the waste package survives an igneous intrusion, so the flux splitting submodel is not used in the igneous scenario class. The flow model is validated in an independent model validation technical review. The drip shield and waste package flux splitting algorithms are developed and validated using experimental data. The transport model considers

  15. Evaluation of atmospheric transport models for use in Phase II of the historical public exposures studies at the Rocky Flats Plant

    SciTech Connect (OSTI)

    Rood, A.S.; Killough, G.G.; Till, J.E.

    1999-08-01

    Five atmospheric transport models were evaluated for use in Phase II of the Historical Public Exposures Studies at the Rocky Flats Plant. Models included a simple straight-line Gaussian plume model (ISCST2), several integrated puff models (RATCHET, TRIAD, and INPUFF2), and a complex terrain model (TRAC). Evaluations were based on how well model predictions compared with sulfur hexafluoride tracer measurements taken in the vicinity of Rocky Flats in February 1991. Twelve separate tracer experiments were conducted, each lasting 9 hr and measured at 140 samplers in arcs 8 and 16 km from the release point at Rocky Flats. Four modeling objectives were defined based on the endpoints of the overall study: (1) the unpaired maximum hourly average concentration, (2) paired time-averaged concentration, (3) unpaired time-averaged concentration, and (4) arc-integrated concentration. Performance measures were used to evaluate models and focused on the geometric mean and standard deviation of the predicted-to-observed ratio and the correlation coefficient between predicted and observed concentrations. No one model consistently outperformed the others in all modeling objectives and performance measures. The overall performance of the RATCHET model was somewhat better than the other models.

  16. DETERMINATION OF SPECIFIC NEUTRONIC REACTIVITY

    DOE Patents [OSTI]

    Dessauer, G.

    1960-05-10

    A method is given for production-line determination of the specific neutronic reactivity of such objects as individual nuclear fuel or neutron absorber elements and is notable for rapidity and apparatus simplicity. The object is incorporated in a slightly sub-critical chain fission reactive assembly having a discrete neutron source, thereby establishing a K/sub eff/ within the crucial range of 0.95 to 0.995. The range was found to afford, uniquely, flux- transient damped response in a niatter of seconds simultaneously with acceptable analytical sensitivity. The resulting neutron flux measured at a situs spaced from both object and source within the assembly serves as a calibrable indication of said reactivity.

  17. Integration of Nontraditional Isotopic Systems Into Reaction-Transport Models of EGS For Exploration, Evaluation of Water-Rock Interaction, and Impacts of Water Chemistry on Reservoir Sustainability

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Nontraditional Isotopic Systems Into Reaction-Transport Models of EGS For Exploration, Evaluation of Water-Rock Interaction, and Impacts of Water Chemistry on Reservoir Sustainability Eric Sonnenthal Lawrence Berkeley National Lab Track 3 Project Officer: Eric Hass Total Project Funding: $512K April 23, 2013 This presentation does not contain any proprietary confidential, or otherwise restricted information. 2 | US DOE Geothermal Office eere.energy.gov Relevance/Impact of Research Challenges,

  18. Beam Transport

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Beam Transport A simplified drawing of the beam transport system from the linac to Target-1 (Lujan Center), Target-2 (Blue Room) and Target-4 is shown below. In usual operation ...

  19. Simulation of oil-slick transport in Great Lakes connecting channels. Volume 3. User's manual for the lake-river oil-spill simulation model. Final report

    SciTech Connect (OSTI)

    Shen, H.T.; Yapa, P.D.; Petroski, M.E.

    1986-03-01

    In this study, two computer models named as ROSS and LROSS are developed for simulating oil-slick transport in rivers and lakes, respectively. The oil-slick transformation processes considered in these models include advection, spreading, evaporation, and dissolution. These models can be used for slicks of any shape originated from instantaneous or continuous spills in rivers and lakes with or without ice covers. Although developed for the need of the connecting channels in the upper Great Lakes, including the Detroit RIver, Lake St. Clair, St. Clair River, and St. Marys River, these models are site independent and can be used for others rivers and lakes. The programs are written in FORTRAN language to be compatible with FORTRAN77 compiler. The models are designed to be used on both mainframe and microcomputers.

  20. Simulation of oil-slick transport in Great Lakes connecting channels. User's manual for the River Spill Simulation Model (ROSS). Special report

    SciTech Connect (OSTI)

    Shen, H.T.; Yapa, P.D.; Petroski, M.E.

    1991-12-01

    Two computer models, named ROSS and LROSS, have been developed for simulating oil slick transport in rivers and lakes, respectively. The oil slick transformation processes considered in these models include advection, spreading, evaporation and dissolution. These models can be used for slicks of any shape originating from instantaneous or continuous spills in rivers and lakes with or without ice covers. Although developed for the connecting channels in the upper Great Lakes, including the Detroit River, Lake St. Clair, the St. Clair River and the St. Marys River, these models are site independent and can be used for other rivers and lakes. The programs are written in FORTRAN programming language to be compatible with the FORTRAN77 compiler. In addition, a user-friendly, menu-driven program with graphics capability was developed for the IBM-PC AT computer, so that these models can be easily used to assist the cleanup action in the connecting channels should an oil spill occur.

  1. Simulation of oil-slick transport in Great Lakes connecting channels. Volume 2. User's manual for the river oil-spill simulation model. Final report

    SciTech Connect (OSTI)

    Shen, H.T.; Yapa, P.D.; Petroski, M.E.

    1986-03-01

    In this study, two computer models named as ROSS and LROSS are developed for simulating oil-slick transport in rivers and lakes, respectively. The oil slick transformation processes considered in these models include advection, spreading, evaporation, and dissolution. These models can be used for slicks of any shape originated from instantaneous or continuous spills in rivers and lakes with or without ice covers. Although developed for the need of the connecting channels in the upper Great Lakes, including the Detroit River, Lake St. Clair, St. Clair River, and St. Marys River, these models are site independent and can be used for other rivers and lakes. The programs are written in FORTRAN programing language to be compatible with FORTRAN77 compiler. The models are designed to be used on both mainframe and microcomputers.

  2. WIPP Transportation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Transuranic Waste Transportation Container Documents Documents related to transuranic waste containers and packages. CBFO Tribal Program Information about WIPP shipments across tribal lands. Transportation Centralized Procurement Program - The Centralized Procurement Program provides a common method to procure standard items used in the packaging and handling of transuranic wasted destined for WIPP. Transuranic Waste Transportation Routes - A map showing transuranic waste generator sites and

  3. Shock Desensitization Experiments and Reactive Flow Modeling...

    Office of Scientific and Technical Information (OSTI)

    Information Service, Springfield, VA at www.ntis.gov. Authors: Vandersall, K S ; Garcia, F ; Tarver, C M ; Fried, L E Publication Date: 2014-06-24 OSTI Identifier: 1169869 ...

  4. Quantifying sources and sinks of reactive gases in the lower atmosphere using airborne flux observations

    SciTech Connect (OSTI)

    Wolfe, Glenn; Hanisco, T. F.; Atkinson, H. L.; Bui, Thaopaul; Crounse, J. D.; Dean-Day, J.; Goldstein, Allen H.; Guenther, Alex B.; Hall, S. R.; Huey, L. G.; Jacob, D.; Karl, T.; Kim, P. S.; Liu, X.; Marvin, M. R.; Mikoviny, Tomas; Misztal, Pawel K.; Nguyen, Tran B.; Peischl, Jeff; Pollack, Ilana; Ryerson, T. B.; St Clair, J. M.; Teng, A. P.; Travis, Katherine; Ullmann, K.; Wennberg, P. O.; Wisthaler, Armin

    2015-10-16

    Atmospheric composition is governed by the interplay of emissions, chemistry, deposition, and transport. Substantial questions surround each of these processes, especially in forested environments with strong biogenic emissions. Utilizing aircraft observations acquired over a forest in the southeast U.S., we calculate eddy covariance fluxes for a suite of reactive gases and apply the synergistic information derived from this analysis to quantify emission and deposition fluxes, oxidant concentrations, aerosol uptake coefficients, and other key parameters. Evaluation of results against state-of-the-science models and parameterizations provides insight into our current understanding of this system and frames future observational priorities. As a near-direct measurement of fundamental process rates, airborne fluxes offer a new tool to improve biogenic and anthropogenic emissions inventories, photochemical mechanisms, and deposition parameterizations.

  5. Desulfurization Sorbents for Transport-Bed Applications

    SciTech Connect (OSTI)

    Gupta, Raghubir P.; Turk, Brian S.; Vierheilig, Albert A.

    1997-07-01

    This project extends the prior work on the development of fluidizable zinc titanate particles using a spray-drying technique to impart high reactivity and attrition resistance. The specific objectives are: (1) To develop highly reactive and attrition-resistant zinc titanate sorbents in 40- to 150-{micro}m particle size range for transport reactor applications; (2) To transfer sorbent production technology to private sector; and (3) To provide technical support to Sierra Pacific Clean Coal Technology Demonstration plant and FETC's Hot-Gas Desulfurization Process Development Unit (PDU), both employing a transport reactor system.

  6. Used Nuclear Fuel Loading and Structural Performance Under Normal Conditions of Transport - Modeling, Simulation and Experimental Integration RD&D Plan

    SciTech Connect (OSTI)

    Adkins, Harold E.

    2013-04-01

    Under current U.S. Nuclear Regulatory Commission regulation, it is not sufficient for used nuclear fuel (UNF) to simply maintain its integrity during the storage period, it must maintain its integrity in such a way that it can withstand the physical forces of handling and transportation associated with restaging the fuel and moving it to treatment or recycling facilities, or a geologic repository. Hence it is necessary to understand the performance characteristics of aged UNF cladding and ancillary components under loadings stemming from transport initiatives. Researchers would like to demonstrate that enough information, including experimental support and modeling and simulation capabilities, exists to establish a preliminary determination of UNF structural performance under normal conditions of transport (NCT). This research, development and demonstration (RD&D) plan describes a methodology, including development and use of analytical models, to evaluate loading and associated mechanical responses of UNF rods and key structural components. This methodology will be used to provide a preliminary assessment of the performance characteristics of UNF cladding and ancillary components under rail-related NCT loading. The methodology couples modeling and simulation and experimental efforts currently under way within the Used Fuel Disposition Campaign (UFDC). The methodology will involve limited uncertainty quantification in the form of sensitivity evaluations focused around available fuel and ancillary fuel structure properties exclusively. The work includes collecting information via literature review, soliciting input/guidance from subject matter experts, performing computational analyses, planning experimental measurement and possible execution (depending on timing), and preparing a variety of supporting documents that will feed into and provide the basis for future initiatives. The methodology demonstration will focus on structural performance evaluation of

  7. Modeling Aeolian Transport of Contaminated Sediments at Los Alamos National Laboratory, Technical Area 54, Area G: Sensitivities to Succession, Disturbance, and Future Climate

    SciTech Connect (OSTI)

    Whicker, Jeffrey J.; Kirchner, Thomas B.; Breshears, David D.; Field, Jason P.

    2012-03-27

    The Technical Area 54 (TA-54) Area G disposal facility is used for the disposal of radioactive waste at Los Alamos National Laboratory (LANL). U.S. Department of Energy (DOE) Order 435.1 (DOE, 2001) requires that radioactive waste be managed in a manner that protects public health and safety and the environment. In compliance with that requirement, DOE field sites must prepare and maintain site-specific radiological performance assessments for facilities that receive waste after September 26, 1988. Sites are also required to conduct composite analyses for facilities that receive waste after this date; these analyses account for the cumulative impacts of all waste that has been (and will be) disposed of at the facilities and other sources of radioactive material that may interact with these facilities. LANL issued Revision 4 of the Area G performance assessment and composite analysis in 2008. In support of those analyses, vertical and horizontal sediment flux data were collected at two analog sites, each with different dominant vegetation characteristics, and used to estimate rates of vertical resuspension and wind erosion for Area G. The results of that investigation indicated that there was no net loss of soil at the disposal site due to wind erosion, and suggested minimal impacts of wind on the long-term performance of the facility. However, that study did not evaluate the potential for contaminant transport caused by the horizontal movement of soil particles over long time frames. Since that time, additional field data have been collected to estimate wind threshold velocities for initiating sediment transport due to saltation and rates of sediment transport once those thresholds are reached. Data such as these have been used in the development of the Vegetation Modified Transport (VMTran) model. This model is designed to estimate patterns and long-term rates of contaminant redistribution caused by winds at the site, taking into account the impacts of plant

  8. Validation of in vitro cell models used in drug metabolism and transport studies; genotyping of cytochrome P450, phase II enzymes and drug transporter polymorphisms in the human hepatoma (HepG2), ovarian carcinoma (IGROV-1) and colon carcinoma (CaCo-2, LS180) cell lines

    SciTech Connect (OSTI)

    Brandon, Esther F.A.; Bosch, Tessa M.; Deenen, Maarten J.; Levink, Rianne; Wal, Everdina van der; Meerveld, Joyce B.M. van; Bijl, Monique; Beijnen, Jos H. |; Schellens, Jan H.M. |; Meijerman, Irma . E-mail: I.Meijerman@pharm.uu.nl

    2006-02-15

    Human cell lines are often used for in vitro biotransformation and transport studies of drugs. In vivo, genetic polymorphisms have been identified in drug-metabolizing enzymes and ABC-drug transporters leading to altered enzyme activity, or a change in the inducibility of these enzymes. These genetic polymorphisms could also influence the outcome of studies using human cell lines. Therefore, the aim of our study was to pharmacogenotype four cell lines frequently used in drug metabolism and transport studies, HepG2, IGROV-1, CaCo-2 and LS180, for genetic polymorphisms in biotransformation enzymes and drug transporters. The results indicate that, despite the presence of some genetic polymorphisms, no real effects influencing the activity of metabolizing enzymes or drug transporters in the investigated cell lines are expected. However, this characterization will be an aid in the interpretation of the results of biotransformation and transport studies using these in vitro cell models.

  9. Aerosol transport and wet scavenging in deep convective clouds: a case study and model evaluation using a multiple passive tracer analysis approach

    SciTech Connect (OSTI)

    Yang, Qing; Easter, Richard C.; Campuzano-Jost, Pedro; Jimenez, Jose L.; Fast, Jerome D.; Ghan, Steven J.; Wang, Hailong; Berg, Larry K.; Barth, Mary; Liu, Ying; Shrivastava, ManishKumar B.; Singh, Balwinder; Morrison, H.; Fan, Jiwen; Ziegler, Conrad L.; Bela, Megan; Apel, Eric; Diskin, G. S.; Mikoviny, Tomas; Wisthaler, Armin

    2015-08-20

    The effect of wet scavenging on ambient aerosols in deep, continental convective clouds in the mid-latitudes is studied for a severe storm case in Oklahoma during the Deep Convective Clouds and Chemistry (DC3) field campaign. A new passive-tracer based transport analysis framework is developed to characterize the convective transport based on the vertical distribution of several slowly reacting and nearly insoluble trace gases. The passive gas concentration in the upper troposphere convective outflow results from a mixture of 47% from the lower level (0-3 km), 21% entrained from the upper troposphere, and 32% from mid-atmosphere based on observations. The transport analysis framework is applied to aerosols to estimate aerosol transport and wet-scavenging efficiency. Observations yield high overall scavenging efficiencies of 81% and 68% for aerosol mass (Dp < 1μm) and aerosol number (0.03< Dp < 2.5μm), respectively. Little chemical selectivity to wet scavenging is seen among observed submicron sulfate (84%), organic (82%), and ammonium (80%) aerosols, while nitrate has a much lower scavenging efficiency of 57% likely due to the uptake of nitric acid. Observed larger size particles (0.15 - 2.5μm) are scavenged more efficiently (84%) than smaller particles (64%; 0.03 - 0.15μm). The storm is simulated using the chemistry version of the WRF model. Compared to the observation based analysis, the standard model underestimates the wet scavenging efficiency for both mass and number concentrations with low biases of 31% and 40%, respectively. Adding a new treatment of secondary activation significantly improves simulation results, so that the bias in scavenging efficiency in mass and number concentrations is reduced to <10%. This supports the hypothesis that secondary activation is an important process for wet removal of aerosols in deep convective storms.

  10. Modeling of ground water aquifer remediation by pulsed pumping when contaminant transport is affected by physical, non-equilibrium sorption and desorption. Master's thesis

    SciTech Connect (OSTI)

    Caspers, J.L.

    1994-08-12

    This research postulates and demonstrates incorporating rate-limited sorption effects in the USGS SUTRA code for cleanup of a hypothetical sandy aquifer by pump-and-treat remediation methods. Contaminant transport is assumed to be affected by advection, dispersion, and rate-limited sorption/desorption. Sorption is assumed to be either equilibrium or rate-limited, with the rate-limitation described by either a first-order law, or by Fickian diffusion of contaminant through a spherical immobile pore region. Solutions are arrived at by split operator methods for the transport and one-dimensional Galerkin solutions for the solute concentration equations. The resulting model is tested against an analytical Laplace transform model for both first-order and Fickian diffusion methods in a radial pumping simulation. Model simulations are used to evaluate equilibrium, first-order and Fickian diffusion effects for pulsed and continuous pumping solutions within a hypothetical sandy aquifer. These show that equilibrium methods under-predicted rebound while first-order methods may both under and over predict rebound within the matrix for certain regions and may be equivalent to Fickian diffusion in equilibrium regimes for cleanup time prediction. Model simulations are then used to show the efficiency of pulsed pumping methods in cleanup mass extraction per pumped volume for a contaminated aquifer pump-and-treat remediation activity versus more conventional, continuous pumping methods.

  11. Model-Based Analysis of the Role of Biological, Hydrological and Geochemical Factors Affecting Uranium Bioremediation

    SciTech Connect (OSTI)

    Zhao, Jiao; Scheibe, Timothy D.; Mahadevan, Radhakrishnan

    2011-01-24

    Uranium contamination is a serious concern at several sites motivating the development of novel treatment strategies such as the Geobacter-mediated reductive immobilization of uranium. However, this bioremediation strategy has not yet been optimized for the sustained uranium removal. While several reactive-transport models have been developed to represent Geobacter-mediated bioremediation of uranium, these models often lack the detailed quantitative description of the microbial process (e.g., biomass build-up in both groundwater and sediments, electron transport system, etc.) and the interaction between biogeochemical and hydrological process. In this study, a novel multi-scale model was developed by integrating our recent model on electron capacitance of Geobacter (Zhao et al., 2010) with a comprehensive simulator of coupled fluid flow, hydrologic transport, heat transfer, and biogeochemical reactions. This mechanistic reactive-transport model accurately reproduces the experimental data for the bioremediation of uranium with acetate amendment. We subsequently performed global sensitivity analysis with the reactive-transport model in order to identify the main sources of prediction uncertainty caused by synergistic effects of biological, geochemical, and hydrological processes. The proposed approach successfully captured significant contributing factors across time and space, thereby improving the structure and parameterization of the comprehensive reactive-transport model. The global sensitivity analysis also provides a potentially useful tool to evaluate uranium bioremediation strategy. The simulations suggest that under difficult environments (e.g., highly contaminated with U(VI) at a high migration rate of solutes), the efficiency of uranium removal can be improved by adding Geobacter species to the contaminated site (bioaugmentation) in conjunction with the addition of electron donor (biostimulation). The simulations also highlight the interactive effect of

  12. Diagnostic Mass-Consistent Wind Field Monte Carlo Dispersion Model

    Energy Science and Technology Software Center (OSTI)

    1991-01-01

    MATHEW generates a diagnostic mass-consistent, three-dimensional wind field based on point measurements of wind speed and direction. It accounts for changes in topography within its calculational domain. The modeled wind field is used by the Langrangian ADPIC dispersion model. This code is designed to predict the atmospheric boundary layer transport and diffusion of neutrally bouyant, non-reactive species as well as first-order chemical reactions and radioactive decay (including daughter products).

  13. ACCELERATING FUSION REACTOR NEUTRONICS MODELING BY AUTOMATIC COUPLING OF HYBRID MONTE CARLO/DETERMINISTIC TRANSPORT ON CAD GEOMETRY

    SciTech Connect (OSTI)

    Biondo, Elliott D; Ibrahim, Ahmad M; Mosher, Scott W; Grove, Robert E

    2015-01-01

    Detailed radiation transport calculations are necessary for many aspects of the design of fusion energy systems (FES) such as ensuring occupational safety, assessing the activation of system components for waste disposal, and maintaining cryogenic temperatures within superconducting magnets. Hybrid Monte Carlo (MC)/deterministic techniques are necessary for this analysis because FES are large, heavily shielded, and contain streaming paths that can only be resolved with MC. The tremendous complexity of FES necessitates the use of CAD geometry for design and analysis. Previous ITER analysis has required the translation of CAD geometry to MCNP5 form in order to use the AutomateD VAriaNce reducTion Generator (ADVANTG) for hybrid MC/deterministic transport. In this work, ADVANTG was modified to support CAD geometry, allowing hybrid (MC)/deterministic transport to be done automatically and eliminating the need for this translation step. This was done by adding a new ray tracing routine to ADVANTG for CAD geometries using the Direct Accelerated Geometry Monte Carlo (DAGMC) software library. This new capability is demonstrated with a prompt dose rate calculation for an ITER computational benchmark problem using both the Consistent Adjoint Driven Importance Sampling (CADIS) method an the Forward Weighted (FW)-CADIS method. The variance reduction parameters produced by ADVANTG are shown to be the same using CAD geometry and standard MCNP5 geometry. Significant speedups were observed for both neutrons (as high as a factor of 7.1) and photons (as high as a factor of 59.6).

  14. Greening Transportation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Transportation Goal 2: Greening Transportation LANL supports and encourages employees to reduce their personal greenhouse gas emissions by offering various commuting and work schedule options. Our goal is to reduce emissions related to employee travel and commuting to and from work by 13 percent. Energy Conservation» Efficient Water Use & Management» High Performance Sustainable Buildings» Greening Transportation» Green Purchasing & Green Technology» Pollution Prevention» Science

  15. Effect of burst and recombination models for Monte Carlo transport of interacting carriers in a-Se x-ray detectors on Swank noise

    SciTech Connect (OSTI)

    Fang, Yuan; Karim, Karim S.; Badano, Aldo

    2014-01-15

    Purpose: The authors describe the modification to a previously developed Monte Carlo model of semiconductor direct x-ray detector required for studying the effect of burst and recombination algorithms on detector performance. This work provides insight into the effect of different charge generation models for a-Se detectors on Swank noise and recombination fraction. Methods: The proposed burst and recombination models are implemented in the Monte Carlo simulation package, ARTEMIS, developed byFang et al. [Spatiotemporal Monte Carlo transport methods in x-ray semiconductor detectors: Application to pulse-height spectroscopy in a-Se, Med. Phys. 39(1), 308319 (2012)]. The burst model generates a cloud of electron-hole pairs based on electron velocity, energy deposition, and material parameters distributed within a spherical uniform volume (SUV) or on a spherical surface area (SSA). A simple first-hit (FH) and a more detailed but computationally expensive nearest-neighbor (NN) recombination algorithms are also described and compared. Results: Simulated recombination fractions for a single electron-hole pair show good agreement with Onsager model for a wide range of electric field, thermalization distance, and temperature. The recombination fraction and Swank noise exhibit a dependence on the burst model for generation of many electron-hole pairs from a single x ray. The Swank noise decreased for the SSA compared to the SUV model at 4 V/?m, while the recombination fraction decreased for SSA compared to the SUV model at 30 V/?m. The NN and FH recombination results were comparable. Conclusions: Results obtained with the ARTEMIS Monte Carlo transport model incorporating drift and diffusion are validated with the Onsager model for a single electron-hole pair as a function of electric field, thermalization distance, and temperature. For x-ray interactions, the authors demonstrate that the choice of burst model can affect the simulation results for the generation of many

  16. Effect of burst and recombination models for Monte Carlo transport of interacting carriers in a-Se x-ray detectors on Swank noise

    SciTech Connect (OSTI)

    Fang, Yuan; Karim, Karim S.; Badano, Aldo

    2014-01-15

    Purpose: The authors describe the modification to a previously developed Monte Carlo model of semiconductor direct x-ray detector required for studying the effect of burst and recombination algorithms on detector performance. This work provides insight into the effect of different charge generation models for a-Se detectors on Swank noise and recombination fraction. Methods: The proposed burst and recombination models are implemented in the Monte Carlo simulation package, ARTEMIS, developed byFang et al. [“Spatiotemporal Monte Carlo transport methods in x-ray semiconductor detectors: Application to pulse-height spectroscopy in a-Se,” Med. Phys. 39(1), 308–319 (2012)]. The burst model generates a cloud of electron-hole pairs based on electron velocity, energy deposition, and material parameters distributed within a spherical uniform volume (SUV) or on a spherical surface area (SSA). A simple first-hit (FH) and a more detailed but computationally expensive nearest-neighbor (NN) recombination algorithms are also described and compared. Results: Simulated recombination fractions for a single electron-hole pair show good agreement with Onsager model for a wide range of electric field, thermalization distance, and temperature. The recombination fraction and Swank noise exhibit a dependence on the burst model for generation of many electron-hole pairs from a single x ray. The Swank noise decreased for the SSA compared to the SUV model at 4 V/μm, while the recombination fraction decreased for SSA compared to the SUV model at 30 V/μm. The NN and FH recombination results were comparable. Conclusions: Results obtained with the ARTEMIS Monte Carlo transport model incorporating drift and diffusion are validated with the Onsager model for a single electron-hole pair as a function of electric field, thermalization distance, and temperature. For x-ray interactions, the authors demonstrate that the choice of burst model can affect the simulation results for the generation

  17. Assessment of the Economic Benefits from Reactive Power Compensation

    SciTech Connect (OSTI)

    Li, Fangxing; Kueck, John D; Rizy, D Tom; Tolbert, Leon M; Zhang, Wenjuan

    2006-01-01

    The U.S. power industry is under great pressure to provide reactive power or Var support. Although it is generally known that there are technical benefits for utilities and industrial customers to provide local reactive power support, a thorough quantitative investigation of the economic benefit is greatly needed. This paper seeks to provide a quantitative approach to evaluate the benefits from local reactive power compensation. This paper investigates the benefits including reduced losses, shifting reactive power flow to real power flow, and increased transfer capability. These benefits are illustrated with a simple two-bus model and then presented with a more complicated model using Optimal Power Flow. Tests are conducted on a system with seven buses in two areas. These simulations show that the economic benefits can be significant, if compared with capacity payment to central generators or power factor penalties applied to utilities. This economic value may give utilities a better understanding of the Var benefits to assist their cost-benefit analysis for Var compensation. In addition, since the economic benefits are significant, this paper suggests that the future reactive power market should consider local Var providers.

  18. Flash pyrolysis of biomass with reactive and non-reactive gases

    SciTech Connect (OSTI)

    Steinberg, M.; Fallon, P.T.; Sundaram, M.S.

    1984-03-01

    The process chemistry of the flash pyrolysis of biomass (wood) with the reactive gases, H/sub 2/ and CH/sub 4/ and with the non-reactive gases He and N/sub 2/ is being determined in an 1'' downflow tubular reactor at pressures from 20 to 1000 psi and temperatures from 600 to 1000/sup 0/C. With hydrogen, flash hydropyrolysis leads to high yields of ethylene, benzene and CO which can be used for the production of valuable chemical feedstocks and methanol transportation fuel. At reactor conditions of 50 psi and 1000/sup 0/C and approximately 1 sec residence time, the ethylene yield based on pine wood carbon conversion is 27%, for benzene it is 25% and for CO the yield is 39%, indicating that over 90% of the carbon in pine is converted to valuable products. Pine wood produces higher yields of hydrocarbon products than Douglas fir wood. The yield of ethylene is 2.3 times higher with methane than with helium or nitrogen, thus indicating a free radical reaction between CH/sub 4/ and the pyrolyzed wood. There appears to be no net production or consumption of methane. A preliminary process design and analysis indicate an economically competitive system for the production of ethylene, benzene and methanol based on the methanolysis of wood. 7 references, 13 figures, 1 table.

  19. Sustainable Transportation

    SciTech Connect (OSTI)

    2012-09-01

    This document highlights DOE's Office of Energy Efficiency and Renewable Energy's advancements in transportation technologies, alternative fuels, and fuel cell technologies.

  20. Engine combustion control via fuel reactivity stratification

    DOE Patents [OSTI]

    Reitz, Rolf Deneys; Hanson, Reed M.; Splitter, Derek A.; Kokjohn, Sage L.

    2015-07-14

    A compression ignition engine uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. In a preferred implementation, a lower-reactivity fuel charge is injected or otherwise introduced into the combustion chamber, preferably sufficiently early that it becomes at least substantially homogeneously dispersed within the chamber before a subsequent injection is made. One or more subsequent injections of higher-reactivity fuel charges are then made, and these preferably distribute the higher-reactivity matter within the lower-reactivity chamber space such that combustion begins in the higher-reactivity regions, and with the lower-reactivity regions following thereafter. By appropriately choosing the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot).

  1. Engine combustion control via fuel reactivity stratification

    DOE Patents [OSTI]

    Reitz, Rolf Deneys; Hanson, Reed M; Splitter, Derek A; Kokjohn, Sage L

    2013-12-31

    A compression ignition engine uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. In a preferred implementation, a lower-reactivity fuel charge is injected or otherwise introduced into the combustion chamber, preferably sufficiently early that it becomes at least substantially homogeneously dispersed within the chamber before a subsequent injection is made. One or more subsequent injections of higher-reactivity fuel charges are then made, and these preferably distribute the higher-reactivity matter within the lower-reactivity chamber space such that combustion begins in the higher-reactivity regions, and with the lower-reactivity regions following thereafter. By appropriately choose the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot).

  2. A high-fidelity multiphysics model for the new solid oxide iron-air redox battery part I: Bridging mass transport and charge transfer with redox cycle kinetics

    SciTech Connect (OSTI)

    Jin, XF; Zhao, X; Huang, K

    2015-04-15

    A high-fidelity two-dimensional axial symmetrical multi-physics model is described in this paper as an effort to simulate the cycle performance of a recently discovered solid oxide metal-air redox battery (SOMARB). The model collectively considers mass transport, charge transfer and chemical redox cycle kinetics occurring across the components of the battery, and is validated by experimental data obtained from independent research. In particular, the redox kinetics at the energy storage unit is well represented by Johnson-Mehl-Avrami-Kolmogorov (JIVIAK) and Shrinking Core models. The results explicitly show that the reduction of Fe3O4 during the charging cycle limits the overall performance. Distributions of electrode potential, overpotential, Nernst potential, and H-2/H2O-concentration across various components of the battery are also systematically investigated. (C) 2015 Elsevier B.V. All rights reserved.

  3. Mechanism of Proton Transport in Proton Exchange Membranes: Insights from Computer Simulation

    SciTech Connect (OSTI)

    Gregory A. Voth

    2010-11-30

    The solvation and transport of hydrated protons in proton exchange membranes (PEMs) such as NafionTM will be described using a novel multi-state reactive molecular dynamics (MD) approach, combined with large scale MD simulation to help probe various PEM morphological models. The multi-state MD methodology allows for the treatment of explicit (Grotthuss) proton shuttling and charge defect delocalization which, in turn, can strongly influence the properties of the hydrated protons in various aqueous and complex environments. A significant extension of the methodology to treat highly acidic (low pH) environments such as the hydrophilic domains of a PEM will be presented. Recent results for proton solvation and transport in NafionTM will be described which reveal the significant role of Grotthuss shuttling and charge defect delocalization on the excess proton solvation structures and transport properties. The role of PEM hydration level and morphology on these properties will also be described.

  4. Modeling non-steady state radioisotope transport in the vadose zone--A case study using uranium isotopes at Pena Blanca, Mexico

    SciTech Connect (OSTI)

    Ku, T. L.; Luo, S.; Goldstein, S. J.; Murrell, M. T.; Chu, W. L.; Dobson, P. F.

    2009-06-01

    Current models using U- and Th-series disequilibria to study radioisotope transport in groundwater systems mostly consider a steady-state situation. These models have limited applicability to the vadose zone (UZ) where the concentration and migratory behavior of radioisotopes in fluid are often transitory. We present here, as a first attempt of its kind, a model simulating the non-steady state, intermittent fluid transport in vadose layers. It provides quantitative constraints on in-situ migration of dissolved and colloidal radioisotopes in terms of retardation factor and rock-water interaction (or water transit) time. For uranium, the simulation predicts that intermittent flushing in the UZ leads to a linear relationship between reciprocal U concentration and {sup 234}U/{sup 238}U ratio in percolating waters, with the intercept and slope bearing information on the rates of dissolution and {alpha}-recoil of U isotopes, respectively. The general validity of the model appears to be borne out by the measurement of uranium isotopes in UZ waters collected at various times over a period during 1995-2006 from a site in the Pena Blanca mining district, Mexico, where the Nopal I uranium deposit is located. Enhanced {sup 234}U/{sup 238}U ratios in vadose-zone waters resulting from lengthened non-flushing time as prescribed by the model provide an interpretative basis for using {sup 234}U/{sup 238}U in cave calcites to reconstruct the regional changes in hydrology and climate. We also provide a theoretical account of the model's potential applications using radium isotopes.

  5. Gamma Survey of a Permeable Reactive Barrier at Monticello, Utah...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Gamma Survey of a Permeable Reactive Barrier at Monticello, Utah Gamma Survey of a Permeable Reactive Barrier at Monticello, Utah Gamma Survey of a Permeable Reactive Barrier at...

  6. INEEL Subregional Conceptual Model Report Volume 2: Summary of Existing Knowledge of Geochemical Influences on the Fate and Transport of Contaminants in the Subsurface at the INEEL

    SciTech Connect (OSTI)

    Paul L. Wichlacz; Robert C. Starr; Brennon Orr

    2003-09-01

    This document summarizes previous descriptions of geochemical system conceptual models for the vadose zone and groundwater zone (aquifer) beneath the Idaho National Engineering and Environmental Laboratory (INEEL). The primary focus is on groundwater because contaminants derived from wastes disposed at INEEL are present in groundwater, groundwater provides a pathway for potential migration to receptors, and because geochemical characteristics in and processes in the aquifer can substantially affect the movement, attenuation, and toxicity of contaminants. The secondary emphasis is perched water bodies in the vadose zone. Perched water eventually reaches the regional groundwater system, and thus processes that affect contaminants in the perched water bodies are important relative to the migration of contaminants into groundwater. Similarly, processes that affect solutes during transport from nearsurface disposal facilities downward through the vadose zone to the aquifer are relevant. Sediments in the vadose zone can affect both water and solute transport by restricting the downward migration of water sufficiently that a perched water body forms, and by retarding solute migration via ion exchange. Geochemical conceptual models have been prepared by a variety of researchers for different purposes. They have been published in documents prepared by INEEL contractors, the United States Geological Survey (USGS), academic researchers, and others. The documents themselves are INEEL and USGS reports, and articles in technical journals. The documents reviewed were selected from citation lists generated by searching the INEEL Technical Library, the INEEL Environmental Restoration Optical Imaging System, and the ISI Web of Science databases. The citation lists were generated using the keywords ground water, groundwater, chemistry, geochemistry, contaminant, INEL, INEEL, and Idaho. In addition, a list of USGS documents that pertain to the INEEL was obtained and manually searched

  7. Transportation Data Archiving

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Transportation Data Archiving This email address is being protected from spambots. You need JavaScript enabled to view it. - TRACC Director Background Urban and regional transportation planning and operations applications, (e.g. traffic modeling) require a large volume of accurate traffic-related data for a wide range of conditions. Significant real-time data on traffic volumes, highway construction, accidents, weather, airline flights, commuter and rail schedules, etc., are recorded each day by

  8. CASCADER: An m-chain gas-phase radionuclide transport and fate model. Volume 2, User`s manual for CASCADR8

    SciTech Connect (OSTI)

    Cawlfield, D.E.; Been, K.B.; Emer, D.F.; Lindstrom, F.T.; Shott, G.J.

    1993-06-01

    Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and/or diffusion. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. This is volume two to the CASCADER series, titled CASCADR8. It embodies the concepts presented in volume one of this series. To properly understand how the CASCADR8 model works, the reader should read volume one first. This volume presents the input and output file structure for CASCADR8, and a set of realistic scenarios for buried sources of radon gas.

  9. Transportation Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Energy Home/Transportation Energy CRF_climatechange Permalink Gallery Understanding Hazardous Combustion Byproducts Reduces Factors Impacting Climate Change CRF, Global Climate & Energy, News, News & Events, Transportation Energy Understanding Hazardous Combustion Byproducts Reduces Factors Impacting Climate Change By Micheal Padilla Researchers at Sandia's Combustion Research Facility are developing the understanding necessary to build cleaner combustion technologies that will in turn

  10. Predictive two-dimensional scrape-off layer plasma transport modeling of phase-I operations of tokamak SST-1 using SOLPS5

    SciTech Connect (OSTI)

    Himabindu, M.; Tyagi, Anil; Sharma, Devendra; Deshpande, Shishir P. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)] [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Bonnin, Xavier [Laboratoire des Sciences des Procds et des Matriaux, CNRS, Universit Paris13, Sorbonne Paris Cit, Villetaneuse 93430 (France)] [Laboratoire des Sciences des Procds et des Matriaux, CNRS, Universit Paris13, Sorbonne Paris Cit, Villetaneuse 93430 (France)

    2014-02-15

    Computational analysis of coupled plasma and neutral transport in the Scrape-Off Layer (SOL) region of the Steady-State Superconducting Tokamak (SST-1) is done using SOLPS for Phase-I of double-null divertor plasma operations. An optimum set of plasma parameters is explored computationally for the first phase operations with the central objective of achieving an effective control over particle and power exhaust. While the transport of plasma species is treated using a fluid model in the B2.5 code, a full kinetic description is provided by the EIRENE code for the neutral particle transport in a realistic geometry. Cases with and without external gas puffing are analyzed for finding regimes where an effective control of plasma operations can be exercised by controlling the SOL plasma conditions over a range of heating powers. In the desired parameter range, a reasonable neutral penetration across the SOL is observed, capable of causing a variation of up to 15% of the total input power, in the power deposited on the divertors. Our computational characterization of the SOL plasma with input power 1 MW and lower hybrid current drive, for the separatrix density up to 10{sup 19}?m{sup ?3}, indicates that there will be access to high recycling operations producing reduction in the temperature and the peak heat flux at the divertor targets. This indicates that a control of the core plasma density and temperature would be achievable. A power balance analysis done using the kinetic neutral transport code EIRENE indicates about 60%-75% of the total power diverted to the targets, providing quantitative estimates for the relative power loading of the targets and the rest of the plasma facing components.

  11. Measuring and monitoring KIPT Neutron Source Facility Reactivity

    SciTech Connect (OSTI)

    Cao, Yan; Gohar, Yousry; Zhong, Zhaopeng

    2015-08-01

    Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on developing and constructing a neutron source facility at Kharkov, Ukraine. The facility consists of an accelerator-driven subcritical system. The accelerator has a 100 kW electron beam using 100 MeV electrons. The subcritical assembly has keff less than 0.98. To ensure the safe operation of this neutron source facility, the reactivity of the subcritical core has to be accurately determined and continuously monitored. A technique which combines the area-ratio method and the flux-to-current ratio method is purposed to determine the reactivity of the KIPT subcritical assembly at various conditions. In particular, the area-ratio method can determine the absolute reactivity of the subcritical assembly in units of dollars by performing pulsed-neutron experiments. It provides reference reactivities for the flux-to-current ratio method to track and monitor the reactivity deviations from the reference state while the facility is at other operation modes. Monte Carlo simulations are performed to simulate both methods using the numerical model of the KIPT subcritical assembly. It is found that the reactivities obtained from both the area-ratio method and the flux-to-current ratio method are spatially dependent on the neutron detector locations and types. Numerical simulations also suggest optimal neutron detector locations to minimize the spatial effects in the flux-to-current ratio method. The spatial correction factors are calculated using Monte Carlo methods for both measuring methods at the selected neutron detector locations. Monte Carlo simulations are also performed to verify the accuracy of the flux-to-current ratio method in monitoring the reactivity swing during a fuel burnup cycle.

  12. Approximate photochemical dynamics of azobenzene with reactive force fields

    SciTech Connect (OSTI)

    Li, Yan; Hartke, Bernd

    2013-12-14

    We have fitted reactive force fields of the ReaxFF type to the ground and first excited electronic states of azobenzene, using global parameter optimization by genetic algorithms. Upon coupling with a simple energy-gap transition probability model, this setup allows for completely force-field-based simulations of photochemical cis?trans- and trans?cis-isomerizations of azobenzene, with qualitatively acceptable quantum yields. This paves the way towards large-scale dynamics simulations of molecular machines, including bond breaking and formation (via the reactive force field) as well as photochemical engines (presented in this work)

  13. Reactive composite compositions and mat barriers

    SciTech Connect (OSTI)

    Langton, Christine A.; Narasimhan, Rajendran; Karraker, David G.

    2001-01-01

    A hazardous material storage area has a reactive multi-layer composite mat which lines an opening into which a reactive backfill and hazardous material are placed. A water-inhibiting cap may cover the hazardous material storage area. The reactive multi-layer composite mat has a backing onto which is placed an active layer which will neutralize or stabilize hazardous waste and a fronting layer so that the active layer is between the fronting and backing layers. The reactive backfill has a reactive agent which can stabilize or neutralize hazardous material and inhibit the movement of the hazardous material through the hazardous material storage area.

  14. Numerical Modeling of 90Sr and 137Cs Transport from a Spill in the B-Cell of the 324 Building, Hanford Site 300 Area

    SciTech Connect (OSTI)

    Rockhold, Mark L.; Bacon, Diana H.; Freedman, Vicky L.; Lindberg, Michael J.; Clayton, Ray E.

    2012-03-19

    To characterize the extent of contamination under the 324 Building, a pit was excavated on the north side of the building in 2010 by Washington Closure Hanford LLC (WCH). Horizontal closed-end steel access pipes were installed under the foundation of the building from this pit and were used for measuring temperatures and exposure rates under the B-Cell. The deployed sensors measured elevated temperatures of up to 61 C (142 F) and exposure rates of up to 8,900 R/hr. WCH suspended deactivation of the facility because it recognized that building safety systems and additional characterization data might be needed for remediation of the contaminated material. The characterization work included additional field sampling, laboratory measurements, and numerical flow and transport modeling. Laboratory measurements of sediment physical, hydraulic, and geochemical properties were performed by Pacific Northwest National Laboratory (PNNL) and others. Geochemical modeling and subsurface flow and transport modeling also were performed by PNNL to evaluate the possible extent of contamination in the unsaturated sand and gravel sediments underlying the building. Historical records suggest that the concentrated 137Cs- and 90Sr-bearing liquid wastes that were spilled in B-Cell were likely from a glass-waste repository testing program associated with the Federal Republic of Germany (FRG). Incomplete estimates of the aqueous chemical composition (no anion data provided) of the FRG waste solutions were entered into a geochemical speciation model and were charge balanced with nitrate to estimate waste composition. Additional geochemical modeling was performed to evaluate reactions of the waste stream with the concrete foundation of the building prior to the stream entering the subsurface.

  15. Fate and Transport of Uranium (VI) in Weathered Saprolite

    SciTech Connect (OSTI)

    Kim, Young-Jin; Brooks, Scott C; Zhang, Fan; Parker, Jack C.; Moon, Ji Won; Roh, Yul

    2015-01-01

    Batch and column experiments were conducted to investigate sorption and transport of uranium (U) in the presence of saprolite derived from interbedded shale, limestone, and sandstone sequences. Sorption kinetics were measured at two initial concentrations (C0; 1, 10 mM) and three soil:solution ratios (Rs/w; 0.005, 0.25, 2 kg/L) at pH 4.5 (pH of the saprolite). The rate of U loss from solution (mmole/L/h) increased with increasing Rs/w. Uranium sorption exhibited a fast phase with 80% sorption in the first eight hours for all C0 and Rs/w values and a slow phase during which the reaction slowly approached (pseudo) equilibrium over the next seven days. The pH-dependency of U sorption was apparent in pH sorption edges. U(VI) sorption increased over the pH range 4e6, then decreased sharply at pH > 7.5. U(VI) sorption edges were well described by a surface complexation model using calibrated parameters and the reaction network proposed by Waite et al. (1994). Sorption isotherms measured using the same Rs/w and pH values showed a solids concentration effect where U(VI) sorption capacity and affinity decreased with increasing solids concentration. This effect may have been due to either particle aggregation or competition between U(VI) and exchangeable cations for sorption sites. The surface complexation model with calibrated parameters was able to predict the general sorption behavior relatively well, but failed to reproduce solid concentration effects, implying the importance of appropriate design if batch experiments are to be utilized for dynamic systems. Transport of U(VI) through the packed column was significantly retarded. Transport simulations were conducted using the reactive transport model HydroGeoChem (HGC) v5.0 that incorporated the surface complexation reaction network used to model the batch data. Model parameters reported by Waite et al. (1994) provided a better prediction of U transport than optimized parameters derived from our sorption edges. The

  16. Fate and transport of uranium (VI) in weathered saprolite

    SciTech Connect (OSTI)

    Kim, Young-Jin; Brooks, Scott C.; Zhang, Fan; Parker, Jack C.; Moon, Ji-Won; Roh, Yul

    2015-01-01

    We conducted batch and column experiments to investigate sorption and transport of uranium (U) in the presence of saprolite derived from interbedded shale, limestone, and sandstone sequences. Sorption kinetics were measured at two initial concentrations (C0; 1, 10 mM) and three soil:solution ratios (Rs/w; 0.005, 0.25, 2 kg/L) at pH 4.5 (pH of the saprolite). The rate of U loss from solution (mmole/L/h) increased with increasing Rs/w. Uranium sorption exhibited a fast phase with 80% sorption in the first eight hours for all C0 and Rs/w values and a slow phase during which the reaction slowly approached (pseudo) equilibrium over the next seven days. The pH-dependency of U sorption was apparent in pH sorption edges. U(VI) sorption increased over the pH range 4e6, then decreased sharply at pH > 7.5. U(VI) sorption edges were well described by a surface complexation model using calibrated parameters and the reaction network proposed by Waite et al. (1994). Sorption isotherms measured using the same Rs/w and pH values showed a solids concentration effect where U(VI) sorption capacity and affinity decreased with increasing solids concentration. Moreover, this effect may have been due to either particle aggregation or competition between U(VI) and exchangeable cations for sorption sites. The surface complexation model with calibrated parameters was able to predict the general sorption behavior relatively well, but failed to reproduce solid concentration effects, implying the importance of appropriate design if batch experiments are to be utilized for dynamic systems. Transport of U(VI) through the packed column was significantly retarded. We also conducted transport simulations using the reactive transport model HydroGeoChem (HGC) v5.0 that incorporated the surface complexation reaction network used to model the batch data. Model parameters reported by Waite et al. (1994) provided a better prediction of U transport than optimized parameters derived from our sorption edges

  17. Fate and transport of uranium (VI) in weathered saprolite

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kim, Young-Jin; Brooks, Scott C.; Zhang, Fan; Parker, Jack C.; Moon, Ji-Won; Roh, Yul

    2015-01-01

    We conducted batch and column experiments to investigate sorption and transport of uranium (U) in the presence of saprolite derived from interbedded shale, limestone, and sandstone sequences. Sorption kinetics were measured at two initial concentrations (C0; 1, 10 mM) and three soil:solution ratios (Rs/w; 0.005, 0.25, 2 kg/L) at pH 4.5 (pH of the saprolite). The rate of U loss from solution (mmole/L/h) increased with increasing Rs/w. Uranium sorption exhibited a fast phase with 80% sorption in the first eight hours for all C0 and Rs/w values and a slow phase during which the reaction slowly approached (pseudo) equilibrium overmore » the next seven days. The pH-dependency of U sorption was apparent in pH sorption edges. U(VI) sorption increased over the pH range 4e6, then decreased sharply at pH > 7.5. U(VI) sorption edges were well described by a surface complexation model using calibrated parameters and the reaction network proposed by Waite et al. (1994). Sorption isotherms measured using the same Rs/w and pH values showed a solids concentration effect where U(VI) sorption capacity and affinity decreased with increasing solids concentration. Moreover, this effect may have been due to either particle aggregation or competition between U(VI) and exchangeable cations for sorption sites. The surface complexation model with calibrated parameters was able to predict the general sorption behavior relatively well, but failed to reproduce solid concentration effects, implying the importance of appropriate design if batch experiments are to be utilized for dynamic systems. Transport of U(VI) through the packed column was significantly retarded. We also conducted transport simulations using the reactive transport model HydroGeoChem (HGC) v5.0 that incorporated the surface complexation reaction network used to model the batch data. Model parameters reported by Waite et al. (1994) provided a better prediction of U transport than optimized parameters derived from our

  18. Validation testing a contaminant transport and natural attenuation simulation model using field data. Master`s thesis

    SciTech Connect (OSTI)

    Flier, S.J.

    1995-12-01

    This research extends the work begun by Enyeart (1994) which evaluated the process of intrinsic bioremediation, and which developed a model for predicting the velocity of an aerobic degradation front, as it traverses the length of a JP-4 contaminant plume. In the present work, Enyeart`s model was validity tested by comparing its output prediction with field measured values. A methodology was developed to compare the model output with field measured data. The results were analyzed, and the results of this first stage of validity testing show a reasonable basis for accepting the model.

  19. Heat Transfer and Fluid Transport of Supercritical CO2 in Enhanced Geothermal System with Local Thermal Non-equilibrium Model

    SciTech Connect (OSTI)

    Zhang, Le; Luo, Feng; Xu, Ruina; Jiang, Peixue; Liu, Huihai

    2014-12-31

    The heat transfer and fluid transport of supercritical CO2 in enhanced geothermal system (EGS) is studied numerically with local thermal non-equilibrium model, which accounts for the temperature difference between solid matrix and fluid components in porous media and uses two energy equations to describe heat transfer in the solid matrix and in the fluid, respectively. As compared with the previous results of our research group, the effect of local thermal non-equilibrium mainly depends on the volumetric heat transfer coefficient ah, which has a significant effect on the production temperature at reservoir outlet and thermal breakthrough time. The uniformity of volumetric heat transfer coefficient ah has little influence on the thermal breakthrough time, but the temperature difference become more obvious with time after thermal breakthrough with this simulation model. The thermal breakthrough time reduces and the effect of local thermal non-equilibrium becomes significant with decreasing ah.

  20. Modelling radionuclide transport in fractured media with a dynamic update of Kd values

    SciTech Connect (OSTI)

    Trinchero, Paolo; Painter, Scott L.; Ebrahimi, Hedieh; Koskinen, Lasse; Molinero, Jorge; Selroos, Jan -Olof

    2015-10-13

    Radionuclide transport in fractured crystalline rocks is a process of interest in evaluating long term safety of potential disposal systems for radioactive wastes. Given their numerical efficiency and the absence of numerical dispersion, Lagrangian methods (e.g. particle tracking algorithms) are appealing approaches that are often used in safety assessment (SA) analyses. In these approaches, many complex geochemical retention processes are typically lumped into a single parameter: the distribution coefficient (Kd). Usually, the distribution coefficient is assumed to be constant over the time frame of interest. However, this assumption could be critical under long-term geochemical changes as it is demonstrated that the distribution coefficient depends on the background chemical conditions (e.g. pH, Eh, and major chemistry). In this study, we provide a computational framework that combines the efficiency of Lagrangian methods with a sound and explicit description of the geochemical changes of the site and their influence on the radionuclide retention properties.

  1. Fuel temperature reactivity coefficient calculation by Monte Carlo perturbation techniques

    SciTech Connect (OSTI)

    Shim, H. J.; Kim, C. H.

    2013-07-01

    We present an efficient method to estimate the fuel temperature reactivity coefficient (FTC) by the Monte Carlo adjoint-weighted correlated sampling method. In this method, a fuel temperature change is regarded as variations of the microscopic cross sections and the temperature in the free gas model which is adopted to correct the asymptotic double differential scattering kernel. The effectiveness of the new method is examined through the continuous energy MC neutronics calculations for PWR pin cell problems. The isotope-wise and reaction-type-wise contributions to the FTCs are investigated for two free gas models - the constant scattering cross section model and the exact model. It is shown that the proposed method can efficiently predict the reactivity change due to the fuel temperature variation. (authors)

  2. Dynamic Evolution of Cement Composition and Transport Properties under Conditions Relevant to Geological Carbon Sequestration

    SciTech Connect (OSTI)

    Brunet, Jean-Patrick Leopold; Li, Li; Karpyn, Zuleima T.; Strazisar, Brian; Bromhal Grant

    2013-08-01

    Assessing the possibility of CO{sub 2} leakage is one of the major challenges for geological carbon sequestration. Injected CO{sub 2} can react with wellbore cement, which can potentially change cement composition and transport properties. In this work, we develop a reactive transport model based on experimental observations to understand and predict the property evolution of cement in direct contact with CO{sub 2}-saturated brine under diffusion-controlled conditions. The model reproduced the observed zones of portlandite depletion and calcite formation. Cement alteration is initially fast and slows down at later times. This work also quantified the role of initial cement properties, in particular the ratio of the initial portlandite content to porosity (defined here as ?), in determining the evolution of cement properties. Portlandite-rich cement with large ? values results in a localized sharp reactive diffusive front characterized by calcite precipitation, leading to significant porosity reduction, which eventually clogs the pore space and prevents further acid penetration. Severe degradation occurs at the cementbrine interface with large ? values. This alteration increases effective permeability by orders of magnitude for fluids that preferentially flow through the degraded zone. The significant porosity decrease in the calcite zone also leads to orders of magnitude decrease in effective permeability, where fluids flow through the low-permeability calcite zone. The developed reactive transport model provides a valuable tool to link cementCO{sub 2} reactions with the evolution of porosity and permeability. It can be used to quantify and predict long-term wellbore cement behavior and can facilitate the risk assessment associated with geological CO{sub 2} sequestration.

  3. ESTIMATING FATE AND TRANSPORT OF MULTIPLE CONTAMINANTS IN THE VADOSE ZONE USING A MULTI-LAYERED SOIL COLUMN AND THREE-PHASE EQUILIBRIUM PARTITIONING MODEL

    SciTech Connect (OSTI)

    Rucker, G

    2007-05-01

    Soils at waste sites must be evaluated for the potential of residual soil contamination to leach and migrate to the groundwater beneath the disposal area. If migration to the aquifer occurs, contaminants can travel vast distances and contaminate drinking water wells, thus exposing human receptors to harmful levels of toxins and carcinogens. To prevent groundwater contamination, a contaminant fate and transport analysis is necessary to assess the migration potential of residual soil contaminates. This type of migration analysis is usually performed using a vadose zone model to account for complex geotechnical and chemical variables including: contaminant decay, infiltration rate, soil properties, vadose zone thickness, and chemical behavior. The distinct advantage of using a complex model is that less restrictive, but still protective, soil threshold levels may be determined avoiding the unnecessary and costly remediation of marginally contaminated soils. However, the disadvantage of such modeling is the additional cost for data collection and labor required to apply these models. In order to allay these higher costs and to achieve a less restrictive but still protective clean-up level, a multiple contaminant and multi layered soil column equilibrium partitioning model was developed which is faster, simpler and less expensive to use.

  4. Estimating fate and transport of multiple contaminants in the vadose zone using a multi-layered soil column and three-phase equilibrium partitioning model

    SciTech Connect (OSTI)

    Rucker, Gregory G.

    2007-07-01

    Soils at waste sites must be evaluated for the potential of residual soil contamination to leach and migrate to the groundwater beneath the disposal area. If migration to the aquifer occurs, contaminants can travel vast distances and pollute drinking water wells, thus exposing human receptors to harmful levels of toxins and carcinogens. To prevent groundwater contamination, a contaminant fate and transport analysis is necessary to assess the migration potential of residual soil contaminants. This type of migration analysis is usually performed using a vadose zone model to account for complex geotechnical and chemical variables including: decay processes, infiltration rate, soil properties, vadose zone thickness, and chemical behavior. The distinct advantage of using a complex model is that less restrictive, but still protective, soil threshold levels may be determined avoiding the unnecessary and costly remediation of marginally contaminated soils. However, the disadvantage of such modeling is the additional cost for data collection and labor required to apply these models. In order to allay these higher costs and to achieve a less restrictive but still protective clean-up level, a multiple contaminant and multi layered soil column equilibrium partitioning model was developed which is faster, simpler and less expensive to use. (authors)

  5. MELTER: A model of the thermal response of cargos transported in the Safe-Secure Trailer subject to fire environments for risk assessment applications

    SciTech Connect (OSTI)

    Larsen, M.E.

    1994-08-01

    MELTER is an analysis of cargo responses inside a fire-threatened Safe-Secure Trailer (SST) developed for the Defense Program Transportation Risk Assessment (DPTRA). Many simplifying assumptions are required to make the subject problem tractable. MELTER incorporates modeling which balances the competing requirements of execution speed, generality, completeness of essential physics, and robustness. Input parameters affecting the analysis include those defining the fire scenario, those defining the cargo loaded in the SST, and those defining properties of the SST. For a specified fire, SST, and cargo geometry MELTER predicts the critical fire duration that will lead to a failure. The principal features of the analysis include: (a) Geometric considerations to interpret fire-scenario descriptors in terms of a thermal radiation boundary condition, (b) a simple model of the SST`s wall combining the diffusion model for radiation through optically-thick media with an endothermic reaction front to describe the charring of dimensional, rigid foam in the SST wall, (c) a transient radiation enclosure model, (d) a one-dimensional, spherical idealization of the shipped cargos providing modularity so that cargos of interest can be inserted into the model, and (e) associated numerical methods to integrate coupled, differential equations and find roots.

  6. Transportation | NREL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Transportation NREL's transportation infrastructure and programs are designed to significantly reduce petroleum use campus-wide. This infographic shows NREL's FY2015 fleet performance and fleet vehicle history compared to baseline FY 2005 and FY 2014. Petroleum fuel use decreased 28% from 2014 and increased 17% from baseline 2005. Alternative fuel use increased 53% from 2014 and increased 127% from baseline 2005. In baseline 2005, the fleet used 6,521 gasoline gallon equivalent (GGE) of E-85, in

  7. TRANSPORTATION OPTIONS

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    TRANSPORTATION OPTIONS The Pittsburgh Airport Marriott provides complimentary shuttle service. The hotel asks all guests arriving at the Pittsburgh International Airport to collect luggage in the baggage claim area of the airport and then call for the shuttle at 412-788- 8800. Let the Hotel Operator know that you have collected your luggage and have a reservation at the Marriott and need transportation from the airport. The Hotel Operator will instruct the guest which door to exit, which curb to

  8. Description and preliminary validation of a model for natural convection heat and air transport in passive solar buildings

    SciTech Connect (OSTI)

    Jones, G.F.; Balcomb, J.D.

    1985-01-01

    We have proposed a transient, quasi-two-dimensional, numerical model for interzone heat flow and airflow in passive solar buildings. The paths for heat flow and airflow are through connecting apertures such as doorways, hallways, and stairways. The model includes the major features that influence interzone convection as determined from the results of our flow visualization tests and temperature and airflow measurements taken in more than a dozen passive solar buildings. The model includes laminar and turbulent quasi-steady boundary-layer equations at vertical heated or cooled walls which are coupled to a one-dimensional core model for each zone. The cores in each zone exchange air and energy through the aperture which is modelled by a Bernoulli equation. Preliminary results from the model are in general agreement with data obtained in full-scale buildings and laboratory experiments. The model predicts room-core temperature stratification of about 2/sup 0/C/m (1.1/sup 0/ F/ft) and maximum aperture velocities of 0.08 m/s (15 ft/min.) for a room-to-room temperature difference of 1/sup 0/F.

  9. A Hydrostrat Model and Alternatives for Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 99: Rainer Mesa-Shoshone Mountain, Nye County, Nevada

    SciTech Connect (OSTI)

    NSTec Geotechnical Sciences Group

    2007-03-01

    The three-dimensional hydrostratigraphic framework model for the Rainier Mesa-Shoshone Mountain Corrective Action Unit was completed in Fiscal Year 2006. The model extends from eastern Pahute Mesa in the north to Mid Valley in the south and centers on the former nuclear testing areas at Rainier Mesa, Aqueduct Mesa, and Shoshone Mountain. The model area also includes an overlap with the existing Underground Test Area Corrective Action Unit models for Yucca Flat and Pahute Mesa. The model area is geologically diverse and includes un-extended yet highly deformed Paleozoic terrain and high volcanic mesas between the Yucca Flat extensional basin on the east and caldera complexes of the Southwestern Nevada Volcanic Field on the west. The area also includes a hydrologic divide between two groundwater sub-basins of the Death Valley regional flow system. A diverse set of geological and geophysical data collected over the past 50 years was used to develop a structural model and hydrostratigraphic system for the model area. Three deep characterization wells, a magnetotelluric survey, and reprocessed gravity data were acquired specifically for this modeling initiative. These data and associated interpretive products were integrated using EarthVision{reg_sign} software to develop the three-dimensional hydrostratigraphic framework model. Crucial steps in the model building process included establishing a fault model, developing a hydrostratigraphic scheme, compiling a drill-hole database, and constructing detailed geologic and hydrostratigraphic cross sections and subsurface maps. The more than 100 stratigraphic units in the model area were grouped into 43 hydrostratigraphic units based on each unit's propensity toward aquifer or aquitard characteristics. The authors organized the volcanic units in the model area into 35 hydrostratigraphic units that include 16 aquifers, 12 confining units, 2 composite units (a mixture of aquifer and confining units), and 5 intrusive confining

  10. Comparison of Average Transport and Dispersion Among a Gaussian, a Two-Dimensional, and a Three-Dimensional Model

    Broader source: Energy.gov [DOE]

    The Nuclear Regulatory Commission’s (NRC’s) code for predicting off-siteconsequences, MACCS2 (Chanin, et al. 1998) (MELCOR Accident Consequence CodeSystem, Version 2), uses a simplified model for...

  11. Resolving the mystery of transport within internal transport barriers

    SciTech Connect (OSTI)

    Staebler, G. M.; Belli, E. A.; Candy, J.; Waltz, R. E.; Greenfield, C. M.; Lao, L. L.; Smith, S. P.; Kinsey, J. E.; Grierson, B. A.; Chrystal, C.

    2014-05-15

    The Trapped Gyro-Landau Fluid (TGLF) quasi-linear model [G. M. Staebler, et al., Phys. Plasmas 12, 102508 (2005)], which is calibrated to nonlinear gyrokinetic turbulence simulations, is now able to predict the electron density, electron and ion temperatures, and ion toroidal rotation simultaneously for internal transport barrier (ITB) discharges. This is a strong validation of gyrokinetic theory of ITBs, requiring multiple instabilities responsible for transport in different channels at different scales. The mystery of transport inside the ITB is that momentum and particle transport is far above the predicted neoclassical levels in apparent contradiction with the expectation from the theory of suppression of turbulence by EB velocity shear. The success of TGLF in predicting ITB transport is due to the inclusion of ion gyro-radius scale modes that become dominant at high EB velocity shear and to improvements to TGLF that allow momentum transport from gyrokinetic turbulence to be faithfully modeled.

  12. Modeling the Transport and Radiative Forcing of Taklimakan Dust over the Tibetan Plateau: A case study in the summer of 2006

    SciTech Connect (OSTI)

    Chen, Siyu; Huang, J.; Zhao, Chun; Qian, Yun; Leung, Lai-Yung R.; Yang, Ben

    2013-01-30

    The Weather Research and Forecasting model with chemistry (WRF-Chem) is used to investigate an intense dust storm event during 26 to 30 July 2006 that originated over the Taklimakan Desert (TD) and transported to the northern slope of Tibetan Plateau (TP). The dust storm is initiated by the approach of a strong cold frontal system over the TD. In summer, the meridional transport of TD dust to the TP is favored by the thermal effect of the TP and the weakening of the East Asian westerly winds. During this dust storm, the transport of TD dust over the TP is further enhanced by the passage of the cold front. As a result, TD dust breaks through the planetary boundary layer and extends to the upper troposphere over the northern TP. TD dust flux arrived at the TP with a value of 6.6 Gg/day in this 5 day event but decays quickly during the southward migration over the TP due to dry deposition. The simulations show that TD dust cools the atmosphere near the surface and heats the atmosphere above with a maximum heating rate of 0.11 K day-1 at ~7 km over the TP. The event-averaged net radiative forcings of TD dust over the TP are -3.97, 1.61, and -5.58 Wm-2 at the top of the atmosphere (TOA), in the atmosphere, and at the surface, respectively. The promising performance of WRF-Chem in simulating dust and its radiative forcing provides confidence for use in further investigation of climatic impact of TD dust over the TP.

  13. Layered reactive particles with controlled geometries, energies, and reactivities, and methods for making the same

    DOE Patents [OSTI]

    Fritz, Gregory M.; Weihs, Timothy P.; Grzyb, Justin A.

    2016-07-05

    An energetic composite having a plurality of reactive particles each having a reactive multilayer construction formed by successively depositing reactive layers on a rod-shaped substrate having a longitudinal axis, dividing the reactive-layer-deposited rod-shaped substrate into a plurality of substantially uniform longitudinal segments, and removing the rod-shaped substrate from the longitudinal segments, so that the reactive particles have a controlled, substantially uniform, cylindrically curved or otherwise rod-contoured geometry which facilitates handling and improves its packing fraction, while the reactant multilayer construction controls the stability, reactivity and energy density of the energetic composite.

  14. Layered reactive particles with controlled geometries, energies, and reactivities, and methods for making the same

    DOE Patents [OSTI]

    Fritz, Gregory M; Knepper, Robert Allen; Weihs, Timothy P; Gash, Alexander E; Sze, John S

    2013-04-30

    An energetic composite having a plurality of reactive particles each having a reactive multilayer construction formed by successively depositing reactive layers on a rod-shaped substrate having a longitudinal axis, dividing the reactive-layer-deposited rod-shaped substrate into a plurality of substantially uniform longitudinal segments, and removing the rod-shaped substrate from the longitudinal segments, so that the reactive particles have a controlled, substantially uniform, cylindrically curved or otherwise rod-contoured geometry which facilitates handling and improves its packing fraction, while the reactant multilayer construction controls the stability, reactivity and energy density of the energetic composite.

  15. NREL: Transportation Research - Transportation News

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Transportation News The following news stories highlight transportation research at NREL. August 25, 2016 NREL and NASA Receive Regional FLC Award for Notable Technology NASA Johnson Space Center (JSC) and the National Renewable Energy Laboratory (NREL) were selected as 2016 recipients of a Federal Laboratory Consortium (FLC) Mid-Continent Regional Award, for their notable technology development of the patented Battery Internal Short-Circuit (ISC) Device. August 25, 2016 NREL Helps the National

  16. Lessons learned from bacterial transport research at the South Oyster Site

    SciTech Connect (OSTI)

    Scheibe, T.; Hubbard, S.S.; Onstott, T.C.; DeFlaun, M.F.

    2011-04-01

    This paper provides a review of bacterial transport experiments conducted by a multi-investigator, multi-institution, multi-disciplinary team of researchers under the auspices of the U. S. Department of Energy (DOE). The experiments were conducted during the time period 1999-2001 at a field site near the town of Oyster, Virginia known as the South Oyster Site, and included four major experimental campaigns aimed at understanding and quantifying bacterial transport in the subsurface environment. Several key elements of the research are discussed here: (1) quantification of bacterial transport in physically, chemically and biologically heterogeneous aquifers, (2) evaluation of the efficacy of conventional colloid filtration theory, (3) scale effects in bacterial transport, (4) development of new methods for microbial enumeration and screening for low adhesion strains, (5) application of novel hydrogeophysical techniques for aquifer characterization, and (6) experiences regarding management of a large field research effort. Lessons learned are summarized in each of these areas. The body of literature resulting from South Oyster Site research has been widely cited and continues to influence research into the controls exerted by aquifer heterogeneity on reactive transport (including microbial transport). It also served as a model (and provided valuable experience) for subsequent and ongoing highly-instrumented field research efforts conducted by DOE-sponsored investigators.

  17. Flash pyrolysis of biomass with reactive and non-reactive gases

    SciTech Connect (OSTI)

    Steinberg, M.; Fallon, P.T.; Sundaram, M.S.

    1985-03-01

    The process chemistry of the flash pyrolysis of biomass (wood) with the reactive gases, H/sub 2/ and CH/sub 4/ and with the non-reactive gases He and N/sub 2/ is being determined in a 1'' downflow tubular reactor at pressures from 20 to 1000 psi and temperatures from 600 to 1000/sup 0/C. With hydrogen, flash hydropyrolysis leads to high yields of methane and CO which can be used for SNG and methanol fuel production. With methane, flash methanolysis leads to high yields of ethylene, benzene and CO which can be used for the production of valuable chemical feedstocks and methanol transportation fuel. At reactor conditions of 50 psi and 1000/sup 0/C and approximately 1 sec residence time, the yields based on pine wood carbon conversion are up to 30% for ethylene, 25% for benzene, and 45% for CO, indicating that over 90% of the carbon in pine is converted to valuable products. Pine wood produces higher yields of hydrocarbon products than Douglas fir wood; the yield of ethylene is 2.3 times higher with methane than with helium or nitrogen, and for pine, the ratio is 7.5 times higher. The mechanism appears to be a free radical reaction between CH/sub 4/ and the pyrolyzed wood. There appears to be no net production or consumption of methane. A preliminary process design and analysis indicates an economically competitive system for the production of ethylene, benzene and methanol based on the methanolysis of wood. 8 refs., 18 figs., 1 tab.

  18. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect (OSTI)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  19. A Hydrostratigraphic Model and Alternatives for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 97: Yucca Flat-Climax Mine, Lincoln and Nye Counties, Nevada

    SciTech Connect (OSTI)

    Geotechnical Sciences Group Bechtel Nevada

    2006-01-01

    A new three-dimensional hydrostratigraphic framework model for the Yucca Flat-Climax Mine Corrective Action Unit was completed in 2005. The model area includes Yucca Flat and Climax Mine, former nuclear testing areas at the Nevada Test Site, and proximal areas. The model area is approximately 1,250 square kilometers in size and is geologically complex. Yucca Flat is a topographically closed basin typical of many valleys in the Basin and Range province. Faulted and tilted blocks of Tertiary-age volcanic rocks and underlying Proterozoic and Paleozoic sedimentary rocks form low ranges around the structural basin. During the Cretaceous Period a granitic intrusive was emplaced at the north end of Yucca Flat. A diverse set of geological and geophysical data collected over the past 50 years was used to develop a structural model and hydrostratigraphic system for the basin. These were integrated using EarthVision? software to develop the 3-dimensional hydrostratigraphic framework model. Fifty-six stratigraphic units in the model area were grouped into 25 hydrostratigraphic units based on each unit's propensity toward aquifer or aquitard characteristics. The authors organized the alluvial section into 3 hydrostratigraphic units including 2 aquifers and 1 confining unit. The volcanic units in the model area are organized into 13 hydrostratigraphic units that include 8 aquifers and 5 confining units. The underlying pre-Tertiary rocks are divided into 7 hydrostratigraphic units, including 3 aquifers and 4 confining units. Other units include 1 Tertiary-age sedimentary confining unit and 1 Mesozoic-age granitic confining unit. The model depicts the thickness, extent, and geometric relationships of these hydrostratigraphic units (''layers'' in the model) along with the major structural features (i.e., faults). The model incorporates 178 high-angle normal faults of Tertiary age and 2 low-angle thrust faults of Mesozoic age. The complexity of the model area and the non

  20. Rejuvenating Permeable Reactive Barriers by Chemical Flushing

    Broader source: Energy.gov [DOE]

    Final Report:Rejuvenating Permeable Reactive Barriers by Chemical Flushing,U.S. Environmental Protection Agency, Region 8 Support.August 2004

  1. Directional Reactive Power Ground Plane Transmission - Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Marketing SummaryORNL researchers have developed a pioneering power alternative to batteries using directional reactive power. Batteries are currently the primary option for...

  2. Technical Note: Improvements in GEANT4 energy-loss model and the effect on low-energy electron transport in liquid water

    SciTech Connect (OSTI)

    Kyriakou, I.; Incerti, S.

    2015-07-15

    Purpose: The GEANT4-DNA physics models are upgraded by a more accurate set of electron cross sections for ionization and excitation in liquid water. The impact of the new developments on low-energy electron transport simulations by the GEANT4 Monte Carlo toolkit is examined for improving its performance in dosimetry applications at the subcellular and nanometer level. Methods: The authors provide an algorithm for an improved implementation of the Emfietzoglou model dielectric response function of liquid water used in the GEANT4-DNA existing model. The algorithm redistributes the imaginary part of the dielectric function to ensure a physically motivated behavior at the binding energies, while retaining all the advantages of the original formulation, e.g., the analytic properties and the fulfillment of the f-sum-rule. In addition, refinements in the exchange and perturbation corrections to the Born approximation used in the GEANT4-DNA existing model are also made. Results: The new ionization and excitation cross sections are significantly different from those of the GEANT4-DNA existing model. In particular, excitations are strongly enhanced relative to ionizations, resulting in higher W-values and less diffusive dose-point-kernels at sub-keV electron energies. Conclusions: An improved energy-loss model for the excitation and ionization of liquid water by low-energy electrons has been implemented in GEANT4-DNA. The suspiciously low W-values and the unphysical long tail in the dose-point-kernel have been corrected owing to a different partitioning of the dielectric function.

  3. Modeling of Diesel Exhaust Systems: A methodology to better simulate...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    of Diesel Exhaust Systems: A methodology to better simulate soot reactivity Modeling of Diesel Exhaust Systems: A methodology to better simulate soot reactivity Discussed ...

  4. Finite Volume schemes on unstructured grids for non-local models: Application to the simulation of heat transport in plasmas

    SciTech Connect (OSTI)

    Goudon, Thierry; Labo. J.A. Dieudonne CNRS and Univ. Nice-Sophia Antipolis , Parc Valrose, 06108 Nice cedex 02 ; Parisot, Martin

    2012-10-15

    In the so-called Spitzer-Haerm regime, equations of plasma physics reduce to a nonlinear parabolic equation for the electronic temperature. Coming back to the derivation of this limiting equation through hydrodynamic regime arguments, one is led to construct a hierarchy of models where the heat fluxes are defined through a non-local relation which can be reinterpreted as well by introducing coupled diffusion equations. We address the question of designing numerical methods to simulate these equations. The basic requirement for the scheme is to be asymptotically consistent with the Spitzer-Haerm regime. Furthermore, the constraints of physically realistic simulations make the use of unstructured meshes unavoidable. We develop a Finite Volume scheme, based on Vertex-Based discretization, which reaches these objectives. We discuss on numerical grounds the efficiency of the method, and the ability of the generalized models in capturing relevant phenomena missed by the asymptotic problem.

  5. Method for reactivating catalysts and a method for recycling supercritical fluids used to reactivate the catalysts

    DOE Patents [OSTI]

    Ginosar, Daniel M.; Thompson, David N.; Anderson, Raymond P.

    2008-08-05

    A method of reactivating a catalyst, such as a solid catalyst or a liquid catalyst. The method comprises providing a catalyst that is at least partially deactivated by fouling agents. The catalyst is contacted with a fluid reactivating agent that is at or above a critical point of the fluid reactivating agent and is of sufficient density to dissolve impurities. The fluid reactivating agent reacts with at least one fouling agent, releasing the at least one fouling agent from the catalyst. The at least one fouling agent becomes dissolved in the fluid reactivating agent and is subsequently separated or removed from the fluid reactivating agent so that the fluid reactivating agent may be reused. A system for reactivating a catalyst is also disclosed.

  6. Source Term Estimation of Radioxenon Released from the Fukushima Dai-ichi Nuclear Reactors Using Measured Air Concentrations and Atmospheric Transport Modeling

    SciTech Connect (OSTI)

    Eslinger, Paul W.; Biegalski, S.; Bowyer, Ted W.; Cooper, Matthew W.; Haas, Derek A.; Hayes, James C.; Hoffman, Ian; Korpach, E.; Yi, Jing; Miley, Harry S.; Rishel, Jeremy P.; Ungar, R. Kurt; White, Brian; Woods, Vincent T.

    2014-01-01

    Systems designed to monitor airborne radionuclides released from underground nuclear explosions detected radioactive fallout from the Fukushima Daiichi nuclear accident in March 2011. Atmospheric transport modeling (ATM) of plumes of noble gases and particulates were performed soon after the accident to determine plausible detection locations of any radioactive releases to the atmosphere. We combine sampling data from multiple International Modeling System (IMS) locations in a new way to estimate the magnitude and time sequence of the releases. Dilution factors from the modeled plume at five different detection locations were combined with 57 atmospheric concentration measurements of 133-Xe taken from March 18 to March 23 to estimate the source term. This approach estimates that 59% of the 1.24×1019 Bq of 133-Xe present in the reactors at the time of the earthquake was released to the atmosphere over a three day period. Source term estimates from combinations of detection sites have lower spread than estimates based on measurements at single detection sites. Sensitivity cases based on data from four or more detection locations bound the source term between 35% and 255% of available xenon inventory.

  7. A Hydrostratigraphic Framework Model and Alternatives for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 98: Frenchman Flat, Clark, Lincoln and Nye Counties, Nevada

    SciTech Connect (OSTI)

    Bechtel Nevada

    2005-09-01

    A new, revised three-dimensional (3-D) hydrostratigraphic framework model for Frenchman Flat was completed in 2004. The area of interest includes Frenchman Flat, a former nuclear testing area at the Nevada Test Site, and proximal areas. Internal and external reviews of an earlier (Phase I) Frenchman Flat model recommended additional data collection to address uncertainties. Subsequently, additional data were collected for this Phase II initiative, including five new drill holes and a 3-D seismic survey.

  8. Non-equilibrium STLS approach to transport properties of single...

    Office of Scientific and Technical Information (OSTI)

    Non-equilibrium STLS approach to transport properties of single impurity Anderson model Citation Details In-Document Search Title: Non-equilibrium STLS approach to transport ...

  9. Visualization of Fuel Cell Water Transport and Characterization...

    Broader source: Energy.gov (indexed) [DOE]

    presentation, which focuses on fuel cell water transport, was given by Satish Kandlikar at a ... Startup and Operation Water Transport in PEM Fuel Cells: Advanced Modeling, Material ...

  10. Transportation Anslysis Simulation System

    Energy Science and Technology Software Center (OSTI)

    2004-08-23

    TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the region’s individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at themore » level of households and individual travelers. Trips a planned to satisfy the population’s activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not

  11. Determination of filter-cake thicknesses from on-line flow measurements and gas/particle transport modeling

    SciTech Connect (OSTI)

    Smith, D.H.; Powell, V.; Ibrahim, E.; Ferer, M.; Ahmadi, G.

    1996-12-31

    The use of cylindrical candle filters to remove fine ({approx}0.005 mm) particles from hot ({approx}500- 900{degrees}C) gas streams currently is being developed for applications in advanced pressurized fluidized bed combustion (PFBC) and integrated gasification combined cycle (IGCC) technologies. Successfully deployed with hot-gas filtration, PFBC and IGCC technologies will allow the conversion of coal to electrical energy by direct passage of the filtered gases into non-ruggedized turbines and thus provide substantially greater conversion efficiencies with reduced environmental impacts. In the usual approach, one or more clusters of candle filters are suspended from a tubesheet in a pressurized (P {approx_lt}1 MPa) vessel into which hot gases and suspended particles enter, the gases pass through the walls of the cylindrical filters, and the filtered particles form a cake on the outside of each filter. The cake is then removed periodically by a backpulse of compressed air from inside the filter, which passes through the filter wall and filter cake. In various development or demonstration systems the thickness of the filter cake has proved to be an important, but unknown, process parameter. This paper describes a physical model for cake and pressure buildups between cleaning backpulses, and for longer term buildups of the ``baseline`` pressure drop, as caused by incomplete filter cleaning and/or re-entrainment. When combined with operating data and laboratory measurements of the cake porosity, the model may be used to calculate the (average) filter permeability, the filter-cake thickness and permeability, and the fraction of filter-cake left on the filter by the cleaning backpulse or re-entrained after the backpulse. When used for a variety of operating conditions (e.g., different coals, sorbents, temperatures, etc.), the model eventually may provide useful information on how the filter-cake properties depend on the various operating parameters.

  12. Reaction-Based Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center

    SciTech Connect (OSTI)

    Yeh, Gour-Tsyh

    2006-06-01

    This research project (started Fall 2004) was funded by a grant to The Pennsylvania State University, University of Central Florida, and The University of Alabama in the Integrative Studies Element of the NABIR Program (DE-FG04-ER63914/63915/63196). Dr. Eric Roden, formerly at The University of Alabama, is now at the University of Wisconsin - Madison. Our project focuses on the development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. This work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and is directly aligned with the Scheibe et al. NABIR FRC Field Project at Area 2.

  13. Point kinetics calculations with fully coupled thermal fluids reactivity feedback

    SciTech Connect (OSTI)

    Zhang, H.; Zou, L.; Andrs, D.; Zhao, H.; Martineau, R.

    2013-07-01

    The point kinetics model has been widely used in the analysis of the transient behavior of a nuclear reactor. In the traditional nuclear reactor system safety analysis codes such as RELAP5, the reactivity feedback effects are calculated in a loosely coupled fashion through operator splitting approach. This paper discusses the point kinetics calculations with the fully coupled thermal fluids and fuel temperature feedback implemented into the RELAP-7 code currently being developed with the MOOSE framework. (authors)

  14. General Reactive Atomistic Simulation Program

    Energy Science and Technology Software Center (OSTI)

    2004-09-22

    GRASP (General Reactive Atomistic Simulation Program) is primarily intended as a molecular dynamics package for complex force fields, The code is designed to provide good performance for large systems, either in parallel or serial execution mode, The primary purpose of the code is to realistically represent the structural and dynamic properties of large number of atoms on timescales ranging from picoseconds up to a microsecond. Typically the atoms form a representative sample of some material,more » such as an interface between polycrystalline silicon and amorphous silica. GRASP differs from other parallel molecular dynamics codes primarily due to it’s ability to handle relatively complicated interaction potentials and it’s ability to use more than one interaction potential in a single simulation. Most of the computational effort goes into the calculation of interatomic forces, which depend in a complicated way on the positions of all the atoms. The forces are used to integrate the equations of motion forward in time using the so-called velocity Verlet integration scheme. Alternatively, the forces can be used to find a minimum energy configuration, in which case a modified steepest descent algorithm is used.« less

  15. Transportation Fuels

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Fuels DOE would invest $52 million to fund a major fleet transformation at Idaho National Laboratory, along with the installation of nine fuel management systems, purchase of additional flex fuel cars and one E85 ethanol fueling station. Transportation projects, such as the acquisition of highly efficient and alternative-fuel vehicles, are not authorized by ESPC legislation. DOE has twice proportion of medium vehicles and three times as many heavy vehicles as compared to the Federal agency

  16. Phase I Transport Model of Corrective Action Units 101 and 102: Central and Western Pahute Mesa, Nevada Test Site, Nye County, Nevada with Errata Sheet 1, 2, 3, Revision 1

    SciTech Connect (OSTI)

    Greg Ruskauff

    2009-02-01

    As prescribed in the Pahute Mesa Corrective Action Investigation Plan (CAIP) (DOE/NV, 1999) and Appendix VI of the Federal Facility Agreement and Consent Order (FFACO) (1996, as amended February 2008), the ultimate goal of transport analysis is to develop stochastic predictions of a contaminant boundary at a specified level of uncertainty. However, because of the significant uncertainty of the model results, the primary goal of this report was modified through mutual agreement between the DOE and the State of Nevada to assess the primary model components that contribute to this uncertainty and to postpone defining the contaminant boundary until additional model refinement is completed. Therefore, the role of this analysis has been to understand the behavior of radionuclide migration in the Pahute Mesa (PM) Corrective Action Unit (CAU) model and to define, both qualitatively and quantitatively, the sensitivity of such behavior to (flow) model conceptualization and (flow and transport) parameterization.

  17. EFFECTS OF PORE STRUCTURE CHANGE AND MULTI-SCALE HETEROGENEITY ON CONTAMINANT TRANSPORT AND REACTION RATE UPSCALING

    SciTech Connect (OSTI)

    Lindquist, W. Brent; Jones, Keith W.; Um, Wooyong; Rockhold, mark; Peters, Catherine A.; Celia, Michael A.

    2013-02-15

    secondary mineral precipitates (cancrinite), conducting experiments under conditions with and without Al allowed us to experimentally separate the conditions that lead to quartz dissolution from the conditions that lead to quartz dissolution plus cancrinite precipitation. Consistent with our expectations, in the experiments without Al, there was a substantial reduction in volume of the solid matrix. With Al there was a net increase in the volume of the solid matrix. The rate and extent of reaction was found to increase with temperature. These results demonstrate a successful effort to identify conditions that lead to increases and conditions that lead to decreases in solid matrix volume due to reactions of caustic tank wastes with quartz sands. In addition, we have begun to work with slightly larger, intermediate-scale columns packed with Hanford natural sediments and quartz. Similar dissolution and precipitation were observed in these colums. The measurements are being interpreted with reactive transport modeling using STOMP; preliminary observations are reported here. 2) Multi-Scale Imaging and Analysis. Mineral dissolution and precipitation rates within a porous medium will be different in different pores due to natural heterogeneity and the heterogeneity that is created from the reactions themselves. We used a combination of X-ray computed microtomography, backscattered electron and energy dispersive X-ray spectroscopy combined with computational image analysis to quantify pore structure, mineral distribution, structure changes and fluid-air and fluid-grain interfaces. ? Results and Key Findings: Three of the columns from the reactive flow experiments at PNNL (S1, S3, S4) were imaged using 3D X-ray computed microtomography (XCMT) at BNL and analyzed using 3DMA-rock at SUNY Stony Brook. The imaging results support the mass balance findings reported by Dr. Ums group, regarding the substantial dissolution of quartz in column S1. An important observation is that of grain

  18. Internal neutronics-temperature coupling in Serpent 2 - Reactivity differences resulting from choice of material property correlations

    SciTech Connect (OSTI)

    Valtavirta, V. [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT (Finland)

    2013-07-01

    This paper describes the unique way of simultaneously solving the power and temperature distributions of a nuclear system with the Monte Carlo neutron transport code Serpent 2. The coupled solution is achieved through the implementation of an internal temperature solver and material property correlations in the code. The program structure is reviewed concerning the temperature solver and the internal correlations as well as the internal coupling between these two and the neutron transport part. To estimate the reactivity differences resulting from correlation choices a simple pin-cell case has been calculated. It is established, that some correlation choices may result in difference in reactivity of approximately 100 pcm. (authors)

  19. Reactive multilayers fabricated by vapor deposition. A critical review

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adams, D. P.

    2014-10-02

    The reactive multilayer thin films are a class of energetic materials that continue to attract attention for use in joining applications and as igniters. Generally composed of two reactants, these heterogeneous solids can be stimulated by an external source to promptly release stored chemical energy in a sudden emission of light and heat. In our critical review article, results from recent investigations of these materials are discussed. Discussion begins with a brief description of the vapor deposition techniques that provide accurate control of layer thickness and film composition. More than 50 reactive film compositions have been reported to date, withmore » most multilayers fabricated by magnetron sputter deposition or electron-beam evaporation. In later sections, we review how multilayer ignition threshold, reaction rate, and total heat are tailored via thin film design. For example, planar multilayers with nanometer-scale periodicity exhibit rapid, self-sustained reactions with wavefront velocities up to 100 m/s. Numeric and analytical models have elucidated many of the fundamental processes that underlie propagating exothermic reactions while demonstrating how reaction rates vary with multilayer design. Recent, time-resolved diffraction and imaging studies have further revealed the phase transformations and the wavefront dynamics associated with propagating chemical reactions. Many reactive multilayers (e.g., Co/Al) form product phases that are consistent with published equilibrium phase diagrams, yet a few systems, such as Pt/Al, develop metastable products. The final section highlights current and emerging applications of reactive multilayers. Examples include reactive Ni(V)/Al and Pd/Al multilayers which have been developed for localized soldering of heat-sensitive components.« less

  20. Reactive multilayers fabricated by vapor deposition. A critical review

    SciTech Connect (OSTI)

    Adams, D. P.

    2014-10-02

    The reactive multilayer thin films are a class of energetic materials that continue to attract attention for use in joining applications and as igniters. Generally composed of two reactants, these heterogeneous solids can be stimulated by an external source to promptly release stored chemical energy in a sudden emission of light and heat. In our critical review article, results from recent investigations of these materials are discussed. Discussion begins with a brief description of the vapor deposition techniques that provide accurate control of layer thickness and film composition. More than 50 reactive film compositions have been reported to date, with most multilayers fabricated by magnetron sputter deposition or electron-beam evaporation. In later sections, we review how multilayer ignition threshold, reaction rate, and total heat are tailored via thin film design. For example, planar multilayers with nanometer-scale periodicity exhibit rapid, self-sustained reactions with wavefront velocities up to 100 m/s. Numeric and analytical models have elucidated many of the fundamental processes that underlie propagating exothermic reactions while demonstrating how reaction rates vary with multilayer design. Recent, time-resolved diffraction and imaging studies have further revealed the phase transformations and the wavefront dynamics associated with propagating chemical reactions. Many reactive multilayers (e.g., Co/Al) form product phases that are consistent with published equilibrium phase diagrams, yet a few systems, such as Pt/Al, develop metastable products. The final section highlights current and emerging applications of reactive multilayers. Examples include reactive Ni(V)/Al and Pd/Al multilayers which have been developed for localized soldering of heat-sensitive components.

  1. Evaluation of conceptual, mathematical and physical-and-chemical models for describing subsurface radionuclide transport at the Lake Karachai Waste Disposal Site

    SciTech Connect (OSTI)

    Rumynin, V.G.; Mironenko, V.A.; Sindalovsky, L.N.; Boronina, A.V.; Konosavsky, P.K.; Pozdniakov, S.P.

    1998-06-01

    The goal of this work was to develop the methodology and to improve understanding of subsurface radionuclide transport for application to the Lake Karachai Site and to identify the influence of the processes and interactions involved into transport and fate of the radionuclides. The report is focused on two sets of problems, which have to do both with, hydrodynamic and hydrogeochemical aspects of the contaminant transport.

  2. Transportation Safety

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable ... Arctic Climate Measurements Global Climate Models Software Sustainable Subsurface ...

  3. Reactive Membrane Barriers for Containment of Subsurface Contamination

    SciTech Connect (OSTI)

    William A. Arnold; Edward L. Cussler

    2007-02-26

    The overall goal of this project was to develop reactive membrane barriers--a new and flexible technique to contain and stabilize subsurface contaminants. Polymer membranes will leak once a contaminant is able to diffuse through the membrane. By incorporating a reactive material in the polymer, however, the contaminant is degraded or immobilized within the membrane. These processes increase the time for contaminants to breakthrough the barrier (i.e. the lag time) and can dramatically extend barrier lifetimes. In this work, reactive barrier membranes containing zero-valent iron (Fe{sup 0}) or crystalline silicotitanate (CST) were developed to prevent the migration of chlorinated solvents and cesium-137, respectively. These studies were complemented by the development of models quantifying the leakage/kill time of reactive membranes and describing the behavior of products produced via the reactions within the membranes. First, poly(vinyl alcohol) (PVA) membranes containing Fe{sup 0} and CST were prepared and tested. Although PVA is not useful in practical applications, it allows experiments to be performed rapidly and the results to be compared to theory. For copper ions (Cu{sup 2+}) and carbon tetrachloride, the barrier was effective, increasing the time to breakthrough over 300 times. Even better performance was expected, and the percentage of the iron used in the reaction with the contaminants was determined. For cesium, the CST laden membranes increased lag times more than 30 times, and performed better than theoretical predictions. A modified theory was developed for ion exchangers in reactive membranes to explain this result. With the PVA membranes, the effect of a groundwater matrix on barrier performance was tested. Using Hanford groundwater, the performance of Fe{sup 0} barriers decreased compared to solutions containing a pH buffer and high levels of chloride (both of which promote iron reactivity). For the CST bearing membrane, performance improved by a

  4. Vehicle Technologies Office: Transportation System Analytical Tools |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Modeling, Testing, Data & Results » Vehicle Technologies Office: Transportation System Analytical Tools Vehicle Technologies Office: Transportation System Analytical Tools The Vehicle Technologies Office (VTO) has supported the development of a number of software packages and online tools to model individual vehicles and the overall transportation system. Most of these tools are available for free or a nominal charge. Modeling tools that simulate entire vehicles and

  5. Reactivity of perovskites with water: Role of hydroxylation in...

    Office of Scientific and Technical Information (OSTI)

    Reactivity of perovskites with water: Role of hydroxylation in wetting and implications ... Title: Reactivity of perovskites with water: Role of hydroxylation in wetting and ...

  6. Experimental Evidence for Self-Limiting Reactive Flow through...

    Office of Scientific and Technical Information (OSTI)

    Experimental Evidence for Self-Limiting Reactive Flow through a Fractured Cement Core: ... Title: Experimental Evidence for Self-Limiting Reactive Flow through a Fractured Cement ...

  7. The Reactivity of Energetic Materials Under High Pressure and...

    Office of Scientific and Technical Information (OSTI)

    The Reactivity of Energetic Materials Under High Pressure and Temperature Citation Details In-Document Search Title: The Reactivity of Energetic Materials Under High Pressure and ...

  8. Inducing and Quantifying Forbidden Reactivity with Single Molecule...

    Office of Scientific and Technical Information (OSTI)

    Inducing and Quantifying Forbidden Reactivity with Single Molecule Polymer Mechanochemistry Citation Details In-Document Search Title: Inducing and Quantifying Forbidden Reactivity ...

  9. Chemical Imaging and Dynamical Studies of Reactivity and Emergent...

    Office of Scientific and Technical Information (OSTI)

    Chemical Imaging and Dynamical Studies of Reactivity and Emergent Behavior in Complex ... Title: Chemical Imaging and Dynamical Studies of Reactivity and Emergent Behavior in ...

  10. Reactivity of Ozone with Solid Potassium Iodide Investigated...

    Office of Scientific and Technical Information (OSTI)

    Reactivity of Ozone with Solid Potassium Iodide Investigated by Atomic Force Microscopy Citation Details In-Document Search Title: Reactivity of Ozone with Solid Potassium...

  11. Investigation of long term reactive stability of ceria for use...

    Office of Scientific and Technical Information (OSTI)

    reactive stability of ceria for use in solar thermochemical cycles This content will ... reactive stability of ceria for use in solar thermochemical cycles Authors: Rhodes, ...

  12. Groundwater well with reactive filter pack

    DOE Patents [OSTI]

    Gilmore, Tyler J.; Holdren, Jr., George R.; Kaplan, Daniel I.

    1998-01-01

    A method and apparatus for the remediation of contaminated soil and ground water wherein a reactive pack material is added to the annular fill material utilized in standard well construction techniques.

  13. Groundwater well with reactive filter pack

    DOE Patents [OSTI]

    Gilmore, T.J.; Holdren, G.R. Jr.; Kaplan, D.I.

    1998-09-08

    A method and apparatus are disclosed for the remediation of contaminated soil and ground water wherein a reactive pack material is added to the annular fill material utilized in standard well construction techniques. 3 figs.

  14. Reactivity control assembly for nuclear reactor

    DOE Patents [OSTI]

    Bollinger, Lawrence R.

    1984-01-01

    Reactivity control assembly for nuclear reactor comprises supports stacked above reactor core for holding control rods. Couplers associated with the supports and a vertically movable drive shaft have lugs at their lower ends for engagement with the supports.

  15. Mild coal pretreatment to improve liquefaction reactivity

    SciTech Connect (OSTI)

    Miller, R.L.

    1991-01-01

    This report describes work completed during the fourth quarter of a three year project to study the effects of mild chemical pretreatment on coal dissolution reactivity during low severity liquefaction or coal/oil coprocessing. The overall objective of this research is to elucidate changes in the chemical and physical structure of coal by pretreating with methanol or other simple organic solvent and a trace amount of hydrochloric acid and measure the influence of these changes on coal dissolution reactivity. This work is part of a larger effort to develop a new coal liquefaction or coal/oil coprocessing scheme consisting of three main process steps: (1) mile pretreatment of the feed coal to enhance dissolution reactivity and dry the coal, (2) low severity thermal dissolution of the pretreated coal to obtain a very reactive coal-derived residual material amenable to upgrading, and (3) catalytic upgrading of the residual products to distillate liquids.

  16. A Tariff for Reactive Power - IEEE

    SciTech Connect (OSTI)

    Kueck, John D; Tufon, Christopher; Isemonger, Alan; Kirby, Brendan J

    2008-11-01

    This paper describes a suggested tariff or payment for the local supply of reactive power from distributed energy resources. The authors consider four sample customers, and estimate the cost of supply of reactive power for each customer. The power system savings from the local supply of reactive power are also estimated for a hypothetical circuit. It is found that reactive power for local voltage regulation could be supplied to the distribution system economically by customers when new inverters are installed. The inverter would be supplied with a power factor of 0.8, and would be capable of local voltage regulation to a schedule supplied by the utility. Inverters are now installed with photovoltaic systems, fuel cells and microturbines, and adjustable-speed motor drives.

  17. On Perturbation Components Correspondence between Diffusion and Transport

    SciTech Connect (OSTI)

    G. Palmiotti

    2012-11-01

    We have established a correspondence between perturbation components in diffusion and transport theory. In particular we have established the correspondence between the leakage perturbation component of the diffusion theory to that of the group self scattering in transport theory. This has been confirmed by practical applications on sodium void reactivity calculations of fast reactors. Why this is important for current investigations? Recently, there has been a renewed interest in designing fast reactors where the sodium void reactivity coefficient is minimized. In particular the ASTRID8,9 reactor concept has been optimized with this goal in mind. The correspondence on the leakage term that has been established here has a twofold implication for the design of this kind of reactors. First, this type of reactor has a radial reflector; therefore, as shown before, the sodium void reactivity coefficient calculation requires the use of transport theory. The minimization of the sodium reactivity coefficient is normally done by increasing the leakage component that has a negative sign. The correspondence established in this paper allows to directly look at this component in transport theory. The second implication is related to the uncertainty evaluation on sodium void reactivity. As it has shown before, the total sodium void reactivity effect is the result of a large compensation (opposite sign) between the scattering (called often spectral) component and the leakage one. Consequently, one has to evaluate separately the uncertainty on each separate component and then combine them statistically. If one wants to compute the cross section sensitivity coefficients of the two different components, the formulation established in this paper allows to achieve this goal by playing on the contribution to the sodium void reactivity coming from the group self scattering of the sodium cross section.

  18. Variations in Reactivity on Different Crystallographic Orientations of Cerium Oxide

    SciTech Connect (OSTI)

    Mullins, David R; Albrecht, Peter M; Calaza, Florencia C

    2013-01-01

    Cerium oxide is a principal component in many heterogeneous catalytic processes. One of its key characteristics is the ability to provide or remove oxygen in chemical reactions. The different crystallographic faces of ceria present significantly different surface structures and compositions that may alter the catalytic reactivity. The structure and composition determine the number of coordination vacancies surrounding surface atoms, the availability of adsorption sites, the spacing between adsorption sites and the ability to remove O from the surface. To investigate the role of surface orientation on reactivity, CeO2 films were grown with two different orientations. CeO2(100) films were grown ex situ by pulsed laser deposition on Nb-doped SrTiO3(100). CeO2(111) films were grown in situ by thermal deposition of Ce metal onto Ru(0001) in an oxygen atmosphere. The chemical reactivity was characterized by the adsorption and decomposition of various molecules such as alcohols, aldehydes and organic acids. In general the CeO2(100) surface was found to be more active, i.e. molecules adsorbed more readily and reacted to form new products, especially on a fully oxidized substrate. However the CeO2(100) surface was less selective with a greater propensity to produce CO, CO2 and water as products. The differences in chemical reactivity are discussed in light of possible structural terminations of the two surfaces. Recently nanocubes and nano-octahedra have been synthesized that display CeO2(100) and CeO2(111) faces, respectively. These nanoparticles enable us to correlate reactions on high surface area model catalysts at atmospheric pressure with model single crystal films in a UHV environment.

  19. Mapping pan-Arctic methane emissions at high spatial resolution using an adjoint atmospheric transport and inversion method and process-based wetland and lake biogeochemical models

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tan, Z.; Zhuang, Q.; Henze, D. K.; Frankenberg, C.; Dlugokencky, E.; Sweeney, C.; Turner, A. J.

    2015-11-18

    Understanding methane emissions from the Arctic, a fast warming carbon reservoir, is important for projecting changes in the global methane cycle under future climate scenarios. Here we optimize Arctic methane emissions with a nested-grid high-resolution inverse model by assimilating both high-precision surface measurements and column-average SCIAMACHY satellite retrievals of methane mole fraction. For the first time, methane emissions from lakes are integrated into an atmospheric transport and inversion estimate, together with prior wetland emissions estimated by six different biogeochemical models. We find that, the global methane emissions during July 2004June 2005 ranged from 496.4 to 511.5 Tg yr?1, with wetlandmoremethane emissions ranging from 130.0 to 203.3 Tg yr?1. The Arctic methane emissions during July 2004June 2005 were in the range of 14.630.4 Tg yr?1, with wetland and lake emissions ranging from 8.8 to 20.4 Tg yr?1 and from 5.4 to 7.9 Tg yr?1 respectively. Canadian and Siberian lakes contributed most of the estimated lake emissions. Due to insufficient measurements in the region, Arctic methane emissions are less constrained in northern Russia than in Alaska, northern Canada and Scandinavia. Comparison of different inversions indicates that the distribution of global and Arctic methane emissions is sensitive to prior wetland emissions. Evaluation with independent datasets shows that the global and Arctic inversions improve estimates of methane mixing ratios in boundary layer and free troposphere. The high-resolution inversions provide more details about the spatial distribution of methane emissions in the Arctic.less

  20. Used Nuclear Fuel Loading and Structural Performance Under Normal Conditions of Transport- Modeling, Simulation and Experimental Integration RD&D Plan

    Office of Energy Efficiency and Renewable Energy (EERE)

    Used nuclear fuel (UNF) must maintain its integrity during the storage period in such a way that it can withstand the physical forces of handling and transportation associated with restaging the fuel and transporting it to treatment or recycling facilities, or to a geologic repository.