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Title: Role of Biosorption and Biocolloid Enhancement Factor Parameters in Radionuclide Transport Modeling

Authors:
 [1];  [1];  [1];  [1]
  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Environmental Management (EM)
OSTI Identifier:
1351246
Report Number(s):
LA-UR-17-22516
DOE Contract Number:
AC52-06NA25396
Resource Type:
Conference
Resource Relation:
Conference: ABC Salt V ; 2017-03-26 - 2017-03-26 ; Ruidoso, New Mexico, United States
Country of Publication:
United States
Language:
English
Subject:
Earth Sciences; biosorption, dolomite, actinides, WIPP

Citation Formats

Dittrich, Timothy M., Swanson, Juliet S., Richmann, Michael K., and Reed, Donald T. Role of Biosorption and Biocolloid Enhancement Factor Parameters in Radionuclide Transport Modeling. United States: N. p., 2017. Web.
Dittrich, Timothy M., Swanson, Juliet S., Richmann, Michael K., & Reed, Donald T. Role of Biosorption and Biocolloid Enhancement Factor Parameters in Radionuclide Transport Modeling. United States.
Dittrich, Timothy M., Swanson, Juliet S., Richmann, Michael K., and Reed, Donald T. Tue . "Role of Biosorption and Biocolloid Enhancement Factor Parameters in Radionuclide Transport Modeling". United States. doi:. https://www.osti.gov/servlets/purl/1351246.
@article{osti_1351246,
title = {Role of Biosorption and Biocolloid Enhancement Factor Parameters in Radionuclide Transport Modeling},
author = {Dittrich, Timothy M. and Swanson, Juliet S. and Richmann, Michael K. and Reed, Donald T.},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Mar 28 00:00:00 EDT 2017},
month = {Tue Mar 28 00:00:00 EDT 2017}
}

Conference:
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  • Several total system PA analyses have been completed to investigate the performance of light water reactor (LWR) SNF or alternative waste forms in a geologic repository. These analyses contained either no modeling or simple modeling of fracture flow and transport; and none considered radio-colloid facilitated transport. This paper summarizes the work completed to develop a transport model which considers fracture, matrix, and radio-colloid transport; this model is used to evaluate the transport of SNF radionuclides at the Yucca Mountain site.
  • Colloids may be important as a geochemical transport mechanism for radionuclides at geological repositories if they are (1) present in the groundwater, (2) stable with respect to both colloidal and chemical stabilities, (3) capable of adsorbing radionuclides, especially if the sorption is irreversible, and (4) mobile in the subsurface. The available evidence from natural analogue and other field studies relevant to these issues is reviewed, as is the potential role of mobile microorganisms ({open_quotes}biocolloids{close_quotes}) on radionuclide migration. Studies have demonstrated that colloids are ubiquitous in groundwater, although colloid concentrations in deep, geochemically stable systems may be too low to affectmore » radionuclide transport. However, even low colloid populations cannot be dismissed as a potential concern because colloids appear to be stable, and many radionuclides that adsorb to colloids are not readily desorbed over long periods. Field studies offer somewhat equivocal evidence concerning colloid mobility and cannot prove or disprove the significance of colloid transport in the far-field environment. Additional research is needed at new sites to properly represent a repository far-field. Performance assessment would benefit from natural analogue studies to examine colloid behavior at sites encompassing a suite of probable groundwater chemistries and that mimic the types of formations selected for radioactive waste repositories.« less
  • The parameters necessary to model radionuclide transport in salt beds are identified and described. A proposed plan for disposal of the radioactive wastes generated by nuclear power plants is to store waste canisters in repository sites contained in stable salt formations approximately 600 meters below the ground surface. Among the principal radioactive wastes contained in these canisters will be radioactive isotopes of neptunium, americium, uranium, and plutonium along with many highly radioactive fission products. A concern with this form of waste disposal is the possibility of ground-water flow occurring in the salt beds and endangering water supplies and the publicmore » health. Specifically, the research investigated the processes involved in the movement of radioactive wastes from the repository site by groundwater flow. Since the radioactive waste canisters also generate heat, temperature is an important factor. Among the processes affecting movement of radioactive wastes from a repository site in a salt bed are thermal conduction, groundwater movement, ion exchange, radioactive decay, dissolution and precipitation of salt, dispersion and diffusion, adsorption, and thermomigration. In addition, structural changes in the salt beds as a result of temperature changes are important. Based upon the half-lives of the radioactive wastes, he period of concern is on the order of a million years. As a result, major geologic phenomena that could affect both the salt bed and groundwater flow in the salt beds was considered. These phenomena include items such as volcanism, faulting, erosion, glaciation, and the impact of meteorites. CDM reviewed all of the critical processes involved in regional groundwater movement of radioactive wastes and identified and described the parameters that must be included to mathematically model their behavior. In addition, CDM briefly reviewed available echniques to measure these parameters.« less
  • Computer model simulation is required to evaluate the performance of proposed or future high-level radioactive waste geological repositories. However, the accuracy of a model in predicting the real situation depends on how well the values of the transport properties are prescribed as input parameters. Knowledge of transport parameters is therefore essential. We have modeled ANL's Experiment Analog Program which was designed to simulate long-term radwaste migration process by groundwater flowing through a high-level radioactive waste repository. Using this model and experimental measurements, we have evaluated neptunium (actinide) deposition velocity and analyzed the complex phenomena of simultaneous deposition, erosion, and reentrainmentmore » of bentonite when groundwater is flowing through a narrow crack in a basalt rock. The present modeling demonstrates that we can obtain the values of transport parameters, as added information without any additional cost, from the available measurements of laboratory analog experiments. 8 figures, 3 tables.« less
  • Radionuclides escaping from a repository for high level nuclear waste in crystalline rock may eventually be carried by the flowing water in fissure zones. In such zones the rock is broken in blocks of varying sizes and shapes. Also, the water velocity may vary very much along the flow path. The integrated finite difference method (IFDM) is proposed for numerical calculations of radionuclide transport in such zones. A method for lumping blocks of various sizes and shapes into a single PSEUDOBODY is tested by comparing it with an exact analytical solution which can account for the diffusion into blocks ofmore » any size distribution. The errors obtained in using the PSEUDOBODY-approach are found to be small. Furthermore, a method for determining an average Peclet number in a strongly varying velocity field is tested and found to give comparatively small errors. Recent investigations give strong indications that water flows in largely isolated channels in fissured rock. The second part of the paper sets out to investigate the radionuclide transport in channels including matrix diffusion. It is shown that a cylindrical hole in a matrix is much more effective, per unit contact area, than a flat surface. Comparison of diffusion from cylindrical and slit-formed channels shows that the differences in interfacial flux are minor. A slit-formed channel may, therefore, be approximated by a cylindrical one. Using the integrated finite difference method a number of radionuclide transport calculations are performed for the case of flow and dispersion in a cylindrical channel coupled to diffusion and sorption in the matrix.« less