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1

High flux compact neutron generators  

E-Print Network (OSTI)

High Flux Compact Neutron Generators ‡ J. Reijonen §,1 , T-Compact high flux neutron generators are developed at thevoltage feed through of the generator is shown in Fig. 4.

Reijonen, J.; Lou, T.-P.; Tolmachoff, B.; Leung, K.-N.; Verbeke, J.; Vujic, J.

2001-01-01T23:59:59.000Z

2

Imaging of Diesel Particulate Filters using a High-Flux Neutron...  

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

Imaging of Diesel Particulate Filters using a High-Flux Neutron Source Imaging of Diesel Particulate Filters using a High-Flux Neutron Source Detailed images of deposits identified...

3

High Flux Isotope Reactor cold neutron source reference design concept  

SciTech Connect

In February 1995, Oak Ridge National Laboratory`s (ORNL`s) deputy director formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. In May 1995, a team was formed to examine the feasibility of retrofitting a liquid hydrogen (LH{sub 2}) cold source facility into an existing HFIR beam tube. The results of this feasibility study indicated that the most practical location for such a cold source was the HB-4 beam tube. This location provides a potential flux environment higher than the Institut Laue-Langevin (ILL) vertical cold source and maximizes the space available for a future cold neutron guide hall expansion. It was determined that this cold neutron beam would be comparable, in cold neutron brightness, to the best facilities in the world, and a decision was made to complete a preconceptual design study with the intention of proceeding with an activity to install a working LH{sub 2} cold source in the HFIR HB-4 beam tube. During the development of the reference design the liquid hydrogen concept was changed to a supercritical hydrogen system for a number of reasons. This report documents the reference supercritical hydrogen design and its performance. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and testing, (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the conceptual design phase and establishes the baseline reference concept.

Selby, D.L.; Lucas, A.T.; Hyman, C.R. [and others

1998-05-01T23:59:59.000Z

4

Irradiation research capabilities at HFIR (High Flux Isotope Reactor) and ANS (Advanced Neutron Source)  

SciTech Connect

A variety of materials irradiation facilities exist in the High Flux Isotope Reactor (HFIR) and are planned for the Advanced Neutron Source (ANS) reactor. In 1986 the HFIR Irradiation Facilities Improvement (HIFI) project began modifications to the HFIR which now permit the operation of two instrumented capsules in the target region and eight capsules of 46-mm OD in the RB region. Thus, it is now possible to perform instrumented irradiation experiments in the highest continuous flux of thermal neutrons available in the western world. The new RB facilities are now large enough to permit neutron spectral tailoring of experiments and the modified method of access to these facilities permit rotation of experiments thereby reducing fluence gradients in specimens. A summary of characteristics of irradiation facilities in HFIR is presented. The ANS is being designed to provide the highest thermal neutron flux for beam facilities in the world. Additional design goals include providing materials irradiation and transplutonium isotope production facilities as good, or better than, HFIR. The reference conceptual core design consists of two annular fuel elements positioned one above the other instead of concentrically as in the HFIR. A variety of materials irradiation facilities with unprecedented fluxes are being incorporated into the design of the ANS. These will include fast neutron irradiation facilities in the central hole of the upper fuel element, epithermal facilities surrounding the lower fuel element, and thermal facilities in the reflector tank. A summary of characteristics of irradiation facilities presently planned for the ANS is presented. 2 tabs.

Thoms, K.R.

1990-01-01T23:59:59.000Z

5

Detailed studies of Minor Actinide transmutation-incineration in high-intensity neutron fluxes  

SciTech Connect

The Mini-INCA project is dedicated to the measurement of incineration-transmutation chains and potentials of minor actinides in high-intensity thermal neutron fluxes. In this context, new types of detectors and methods of analysis have been developed. The {sup 241}Am and {sup 232}Th transmutation-incineration chains have been studied and several capture and fission cross sections measured very precisely, showing some discrepancies with existing data or evaluated data. An impact study was made on different based-like GEN-IV reactors. It underlines the necessity to proceed to precise measurements for a large number of minor-actinides that contribute to these future incineration scenarios. (authors)

Bringer, O. [CEA/Saclay/DSM/DAPNIA, Gif-sur-Yvette (France); Al Mahamid, I. [Lawrence Berkeley National Laboratory, E.H. and S. Div., CA (United States); Blandin, C. [CEA/Cadarache/DEN/DER/SPEX, Saint-Paul-lez-Durances (France); Chabod, S. [CEA/Saclay/DSM/DAPNIA, Gif-sur-Yvette (France); Chartier, F. [CEA/Cadarache/DEN/DPC/SECR, Gif-sur-Yvette (France); Dupont, E.; Fioni, G. [CEA/Saclay/DSM/DAPNIA, Gif-sur-Yvette (France); Isnard, H. [CEA/Cadarache/DEN/DPC/SECR, Gif-sur-Yvette (France); Letourneau, A.; Marie, F. [CEA/Saclay/DSM/DAPNIA, Gif-sur-Yvette (France); Mutti, P. [Institut Laue-Langevin, Grenoble (France); Oriol, L. [CEA/Cadarache/DEN/DER/SPEX, Saint-Paul-lez-Durances (France); Panebianco, S.; Veyssiere, C. [CEA/Saclay/DSM/DAPNIA, Gif-sur-Yvette (France)

2006-07-01T23:59:59.000Z

6

A neutronic feasibility study for LEU conversion of the high flux isotope reactor (HFIR).  

SciTech Connect

A neutronic feasibility study was performed to determine the uranium densities that would be required to convert the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) from HEU (93%) to LEU (<20%)fuel. The LEU core that was studied is the same as the current HEU core, except for potential changes in the design of the fuel plates. The study concludes that conversion of HFIR from HEU to LEU fuel would require an advanced fuel with a uranium density of 6-7 gU/cm{sup 3} in the inner fuel element and 9-10 gU/cm{sup 3} in the outer fuel element to match the cycle length of the HEU core. LEU fuel with uranium density up to 4.8 gU/cm{sup 3} is currently qualified for research reactor use. Modifications in fuel grading and burnable poison distribution are needed to produce an acceptable power distribution.

Mo, S. C.

1998-01-14T23:59:59.000Z

7

A U.S. high-flux neutron facility for fusion materials development  

SciTech Connect

Materials for a fusion reactor first wall and blanket structure must be able to reliably function in an extreme environment that includes 10-15 MW-year/m{sup 2} neutron and heat fluences. The various materials and structural challenges are as difficult and important as achieving a burning plasma. Overcoming radiation damage degradation is the rate-controlling step in fusion materials development. Recent advances with oxide dispersion strengthened ferritic steels show promise in meeting reactor requirements, while multi-timescale atomistic simulations of defect-grain boundary interactions in model copper systems reveal surprising self-annealing phenomenon. While these results are promising, simultaneous evaluation of radiation effects displacement damage ({le} 200 dpa) and in-situ He generation ({le} 2000 appm) at prototypical reactor temperatures and chemical environments is still required. There is currently no experimental facility in the U.S. that can meet these requirements for macroscopic samples. The E.U. and U.S. fusion communities have recently concluded that a fusion-relevant, high-flux neutron source for accelerated characterization of the effects of radiation damage to materials is a top priority for the next decade. Data from this source will be needed to validate designs for the multi-$B next-generation fusion facilities such as the CTF, ETF, and DEMO, that are envisioned to follow ITER and NIF.

Rei, Donald J [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

8

Neutron Scattering Science User Office, neutronusers@ornl.gov or (865) 574-4600. Proposals for beam time at Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR)  

E-Print Network (OSTI)

Neutron Scattering Science User Office, neutronusers@ornl.gov or (865) 574-4600. Proposals for beam Wildgruber, wildgrubercu@ornl.gov. VISION CallforProposals neutrons.ornl.gov Neutron Scattering Science - Oak time at Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR) and Spallation Neutron Source

Pennycook, Steve

9

Three-dimensional calculations of neutron streaming in the beam tubes of the ORNL HFIR (High Flux Isotope Reactor) Reactor  

SciTech Connect

The streaming of neutrons through the beam tubes in High Flux Isotope Reactor at Oak Ridge National Laboratory has resulted in a reduction of the fracture toughness of the reactor vessel. As a result, an evaluation of vessel integrity was undertaken in order to determine if the reactor can be operated again. As a part of this evaluation, three-dimensional neutron transport calculations were performed to obtain fluxes at points of interest in the wall of the vessel. By comparing the calculated and measured activation of dosimetry specimens from the vessel surveillance program, it was determined that the calculated flux shape was satisfactory to transpose the surveillance data to the locations in the vessel. A bias factor was applied to correct for the average C/E ratio of 0.69. 8 refs., 7 figs., 3 tabs.

Childs, R.L.; Rhoades, W.A.; Williams, L.R.

1988-01-01T23:59:59.000Z

10

Neutronic Analysis of an Advanced Fuel Design Concept for the High Flux Isotope Reactor  

SciTech Connect

This study presents the neutronic analysis of an advanced fuel design concept for the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) that could significantly extend the current fuel cycle length under the existing design and safety criteria. A key advantage of the fuel design herein proposed is that it would not require structural changes to the present HFIR core, in other words, maintaining the same rated power and fuel geometry (i.e., fuel plate thickness and coolant channel dimensions). Of particular practical importance, as well, is the fact that the proposed change could be justified within the bounds of the existing nuclear safety basis. The simulations herein reported employed transport theory-based and exposure-dependent eigenvalue characterization to help improve the prediction of key fuel cycle parameters. These parameters were estimated by coupling a benchmarked three-dimensional MCNP5 model of the HFIR core to the depletion code ORIGEN via the MONTEBURNS interface. The design of an advanced HFIR core with an improved fuel loading is an idea that evolved from early studies by R. D. Cheverton, formerly of ORNL. This study contrasts a modified and increased core loading of 12 kg of 235U against the current core loading of 9.4 kg. The simulations performed predict a cycle length of 39 days for the proposed fuel design, which represents a 50% increase in the cycle length in response to a 25% increase in fissile loading, with an average fuel burnup increase of {approx}23%. The results suggest that the excess reactivity can be controlled with the present design and arrangement of control elements throughout the core's life. Also, the new power distribution is comparable or even improved relative to the current power distribution, displaying lower peak to average fission rate densities across the inner fuel element's centerline and bottom cells. In fact, the fission rate density in the outer fuel element also decreased at these key locations for the proposed design. Overall, it is estimated that the advanced core design could increase the availability of the HFIR facility by {approx}50% and generate {approx}33% more neutrons annually, which is expected to yield sizeable savings during the remaining life of HFIR, currently expected to operate through 2014. This study emphasizes the neutronics evaluation of a new fuel design. Although a number of other performance parameters of the proposed design check favorably against the current design, and most of the core design features remain identical to the reference, it is acknowledged that additional evaluations would be required to fully justify the thermal-hydraulic and thermal-mechanical performance of a new fuel design, including checks for cladding corrosion performance as well as for industrial and economic feasibility.

Xoubi, Ned [ORNL; Primm, Trent [ORNL; Maldonado, G. Ivan [University of Tennessee, Knoxville (UTK)

2009-01-01T23:59:59.000Z

11

Thermal neutron flux contours from criticality event  

SciTech Connect

The generation of thermal neutron flux contours from a criticality event is demonstrated for an idealized building with a criticality event in one of the rooms. The MCNP Monte Carlo computer code is used to calculate the thermal neutron flux.

Carter, L.L., Westinghouse Hanford

1996-08-01T23:59:59.000Z

12

Report of the ANS Project Feasibility Workshop for a High Flux Isotope Reactor-Center for Neutron Research Facility  

SciTech Connect

The Advanced Neutron Source (ANS) Conceptual Design Report (CDR) and its subsequent updates provided definitive design, cost, and schedule estimates for the entire ANS Project. A recent update to this estimate of the total project cost for this facility was $2.9 billion, as specified in the FY 1996 Congressional data sheet, reflecting a line-item start in FY 1995. In December 1994, ANS management decided to prepare a significantly lower-cost option for a research facility based on ANS which could be considered during FY 1997 budget deliberations if DOE or Congressional planners wished. A cost reduction for ANS of about $1 billion was desired for this new option. It was decided that such a cost reduction could be achieved only by a significant reduction in the ANS research scope and by maximum, cost-effective use of existing High Flux Isotope Reactor (HFIR) and ORNL facilities to minimize the need for new buildings. However, two central missions of the ANS -- neutron scattering research and isotope production-were to be retained. The title selected for this new option was High Flux Isotope Reactor-Center for Neutron Research (HFIR-CNR) because of the project`s maximum use of existing HFIR facilities and retention of selected, central ANS missions. Assuming this shared-facility requirement would necessitate construction work near HFIR, it was specified that HFIR-CNR construction should not disrupt normal operation of HFIR. Additional objectives of the study were that it be highly credible and that any material that might be needed for US Department of Energy (DOE) and Congressional deliberations be produced quickly using minimum project resources. This requirement made it necessary to rely heavily on the ANS design, cost, and schedule baselines. A workshop methodology was selected because assessment of each cost and/or scope-reduction idea required nearly continuous communication among project personnel to ensure that all ramifications of propsed changes.

Peretz, F.J.; Booth, R.S. [comp.

1995-07-01T23:59:59.000Z

13

Use of curium neutron flux from head-end pyroprocessing subsystems for the High Reliability Safeguards methodology  

Science Journals Connector (OSTI)

Abstract The deployment of nuclear energy systems (NESs) is expanding around the world. Nations are investing in \\{NESs\\} as a means to establish energy independence, grow national economies, and address climate change. Transitioning to the advanced nuclear fuel cycle can meet growing energy demands and ensure resource sustainability. However, nuclear facilities in all phases of the advanced fuel cycle must be ‘safeguardable,’ where safety, safeguards, and security are integrated into a practical design strategy. To this end, the High Reliability Safeguards (HRS) approach is a continually developing safeguardability methodology that applies intrinsic design features and employs a risk-informed approach for systems assessment that is safeguards-motivated. Currently, a commercial pyroprocessing facility is used as the example system. This paper presents a modeling study that investigates the neutron flux associated with processed materials. The intent of these studies is to determine if the neutron flux will affect facility design, and subsequently, safeguardability. The results presented in this paper are for the head-end subsystems in a pyroprocessing facility. The collective results from these studies will then be used to further develop the HRS methodology.

R.A. Borrelli

2014-01-01T23:59:59.000Z

14

Imaging of Diesel Particulate Filters using a High-Flux Neutron Source  

Energy.gov (U.S. Department of Energy (DOE))

Detailed images of deposits identified inside automotive DPFs using neutrons show how the deposits of soot, ash, and washcoat occurs within the filter.

15

Imaging of Diesel Particulate Filters using a High-Flux Neutron...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Science Division Hassina Z. Bilheux & Sophie Voisin Oak Ridge National Laboratory Neutron Scattering Science Division Jens Gregor University of Tennessee - Knoxville Dept....

16

Three-dimensional discrete ordinates radiation transport calculations of neutron fluxes for beginning-of-cycle at several pressure vessel surveillance positions in the high flux isotope reactor  

SciTech Connect

The objective of this research was to determine improved thermal, epithermal, and fast fluxes and several responses at mechanical test surveillance location keys 2, 4, 5, and 7 of the pressure vessel of the Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR) for the beginning of the fuel cycle. The purpose of the research was to provide essential flux data in support of radiation embrittlement studies of the pressure vessel shell and beam tubes at some of the important locations.

Pace, J.V. III; Slater, C.O.; Smith, M.S.

1993-11-01T23:59:59.000Z

17

The High Flux Isotope Reactor at Oak Ridge National Laboratory  

NLE Websites -- All DOE Office Websites

The High Flux Isotope Reactor at ORNL The High Flux Isotope Reactor at ORNL Aerial of the High Flux Isotope Reactor Site The High Flux Isotope Reactor site is located on the south side of the ORNL campus and is about a three-minute drive from her sister neutron facility, the Spallation Neutron Source. Operating at 85 MW, HFIR is the highest flux reactor-based source of neutrons for research in the United States, and it provides one of the highest steady-state neutron fluxes of any research reactor in the world. The thermal and cold neutrons produced by HFIR are used to study physics, chemistry, materials science, engineering, and biology. The intense neutron flux, constant power density, and constant-length fuel cycles are used by more than 500 researchers each year for neutron scattering research into

18

High Flux Isotope Reactor (HFIR) | U.S. DOE Office of Science...  

Office of Science (SC) Website

(SUF) Division SUF Home About User Facilities User Facilities Dev X-Ray Light Sources Neutron Scattering Facilities High Flux Isotope Reactor (HFIR) Lujan Neutron Scattering...

19

E-Print Network 3.0 - argonne high flux reactor Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

for: argonne high flux reactor Page: << < 1 2 3 4 5 > >> 1 Thirteenth National School on Neutron and X-ray Scattering Summary: Neutron Source and High Flux Isotope Reactor...

20

A study on the optimum fast neutron flux for Boron Neutron Capture Therapy of deep-seated tumors  

Science Journals Connector (OSTI)

Abstract High-energy neutrons, named fast neutrons which have a number of undesirable biological effects on tissue, are a challenging problem in beam designing for Boron Neutron Capture Therapy, BNCT. In spite of this fact, there is not a widely accepted criterion to guide the beam designer to determine the appropriate contribution of fast neutrons in the spectrum. Although a number of researchers have proposed a target value for the ratio of fast neutron flux to epithermal neutron flux, it can be shown that this criterion may not provide the optimum treatment condition. This simulation study deals with the determination of the optimum contribution of fast neutron flux in the beam for BNCT of deep-seated tumors. Since the dose due to these high-energy neutrons damages shallow tissues, delivered dose to skin is considered as a measure for determining the acceptability of the designed beam. To serve this purpose, various beam shaping assemblies that result in different contribution of fast neutron flux are designed. The performances of the neutron beams corresponding to such configurations are assessed in a simulated head phantom. It is shown that the previously used criterion, which suggests a limit value for the contribution of fast neutrons in beam, does not necessarily provide the optimum condition. Accordingly, it is important to specify other complementary limits considering the energy of fast neutrons. By analyzing various neutron spectra, two limits on fast neutron flux are proposed and their validity is investigated. The results show that considering these limits together with the widely accepted IAEA criteria makes it possible to have a more realistic assessment of sufficiency of the designed beam. Satisfying these criteria not only leads to reduction of delivered dose to skin, but also increases the advantage depth in tissue and delivered dose to tumor during the treatment time. The Monte Carlo Code, MCNP-X, is used to perform these simulations.

Fatemeh S. Rasouli; S. Farhad Masoudi

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

The determination of neutron flux in the Texas A & M triga reactor during pulse and steady-state operations  

E-Print Network (OSTI)

-state operation. Neutron flux measurement during a pulse presents an additional problem in that the flux levels vary during the rapid rise and fall in reactor power. The power level transient of the reactor was followed, using the current output of a boron-10... as a flux monitor only at low power. levels or neutron fluxes. The antimony flux monitor in the steady-state flux measurement showed the same type of increase in flux magni- tude as that of the pulse measurement. The high flux values at steady...

O'Donnell, John Joseph

2012-06-07T23:59:59.000Z

22

Measurement of Thermal Neutron Flux in Photo-Neutron Source  

Science Journals Connector (OSTI)

The Photo-Neutron Source (PNS) project is a study ... design, simulation and construction an accelerator based neutron source for Boron Neutron Capture Therapy (BNCT). The system uses ... medical linear accelerat...

A. Taheri; A. Torkamani; A. Pazirandeh…

2013-01-01T23:59:59.000Z

23

High Flux Isotope Reactor (HFIR) | Nuclear Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

High Flux Isotope Reactor High Flux Isotope Reactor May 30, 2013 The High Flux Isotope Reactor (HFIR) first achieved criticality on August 25, 1965, and achieved full power in August 1966. It is a versatile 85-MW isotope production, research, and test reactor with the capability and facilities for performing a wide variety of irradiation experiments and a world-class neutron scattering science program. HFIR is a beryllium-reflected, light water-cooled and moderated flux-trap type swimming pool reactor that uses highly enriched uranium-235 as fuel. HFIR typically operates seven 23-to-27 day cycles per year. Irradiation facility capabilities include Flux trap positions: Peak thermal flux of 2.5X1015 n/cm2/s with similar epithermal and fast fluxes (Highest thermal flux available in the

24

Thermal neutron flux perturbation due to indium foils in water  

E-Print Network (OSTI)

press) 13. Axford, R. A. , and Day, G. M. , personnel communication. 14. Ritchie, R. H. , Thermal Neutron Flux De ression, Health Physics Division Annual Prog. Rep. July, 1958, ORNL-2806, p. 133. 27 i 5, Walker, J. V. , "The Measurement of Absolute... Fluxes in Water and Graphite, " 'ORNL- 2842, 204 (f959). ...

Stinson, Ronald Calvin

1961-01-01T23:59:59.000Z

25

High flux solar energy transformation  

DOE Patents (OSTI)

Disclosed are multi-stage systems for high flux transformation of solar energy allowing for uniform solar intensification by a factor of 60,000 suns or more. Preferred systems employ a focusing mirror as a primary concentrative device and a non-imaging concentrator as a secondary concentrative device with concentrative capacities of primary and secondary stages selected to provide for net solar flux intensification of greater than 2000 over 95 percent of the concentration area. Systems of the invention are readily applied as energy sources for laser pumping and in other photothermal energy utilization processes.

Winston, Roland (Chicago, IL); Gleckman, Philip L. (Chicago, IL); O'Gallagher, Joseph J. (Flossmoor, IL)

1991-04-09T23:59:59.000Z

26

Fast neutron fluxes in pressure vessels using Monte Carlo methods  

SciTech Connect

The objective of this project is to determine the feasibility of calculating the fast neutron flux in the pressure vessel of a pressurized water reactor by Monte Carlo methods. Neutron reactions reduce the ductility of the steel and thus limit the useful life of this important reactor component. This work was performed for Virginia Power (VEPCO). VIM is a continuous-energy Monte Carlo code which provides a versatile geometrical capability and a neutron physics data base closely representing the EDNF/B-IV data from which it was derived.

Edlund, M.C.; Thomas, J.R.

1986-01-01T23:59:59.000Z

27

High energy neutron dosimeter  

DOE Patents (OSTI)

A device for measuring dose equivalents in neutron radiation fields is described. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning. 2 figures.

Rai, K.S.F.

1994-01-11T23:59:59.000Z

28

High-flux solar photon processes  

SciTech Connect

This study was commissioned by the National Renewable Energy Laboratory (NREL) for the purpose of identifying high-flux photoprocesses that would lead to beneficial national and commercial applications. The specific focus on high-flux photoprocesses is based on the recent development by NREL of solar concentrator technology capable of delivering record flux levels. We examined photolytic and photocatalytic chemical processes as well as photothermal processes in the search for processes where concentrated solar flux would offer a unique advantage. 37 refs.

Lorents, D C; Narang, S; Huestis, D C; Mooney, J L; Mill, T; Song, H K; Ventura, S [SRI International, Menlo Park, CA (United States)

1992-06-01T23:59:59.000Z

29

Lifetime Analysis of First wall Materials Exposed to High Temperature and High Energy Neutrons in a Fusion Reactor  

Science Journals Connector (OSTI)

At first wall of a fusion power reactor will be subjected to neutrons, charged particles and radiation, leading to neutron irradiation damage, decrease of thickness by physical sputtering, and high heat flux, ...

K. Miya; H. Hashizume; H. Oomura; M. Akiyama

1987-01-01T23:59:59.000Z

30

Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux  

DOE Patents (OSTI)

Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

Bowman, C.D.

1992-11-03T23:59:59.000Z

31

High Heat Flux Thermoelectric Module Using Standard Bulk Material...  

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

Heat Flux Thermoelectric Module Using Standard Bulk Material High Heat Flux Thermoelectric Module Using Standard Bulk Material Presents high heat flux thermoelectric module design...

32

Ris-M-2208 MECHANICAL VELOCITY SELECTOR, NEUTRON FLUX AND Q-RANGE  

E-Print Network (OSTI)

the geometry of the proposed small angle neutron scattering (SANS) instrument. At the end of the tube, corre APPENDIX B 23 APPENDIX C 26 #12;- 5 - I. INTRODUCTION The proposed Small Angle Neutron Scattering (SANSRisø-M-2208 MECHANICAL VELOCITY SELECTOR, NEUTRON FLUX AND Q-RANGE FOR THE SMALL ANGLE NEUTRON

33

High Flux Beam Reactor | Environmental Restoration Projects | BNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Why is the High Flux Beam Reactor Being Decommissioned? Why is the High Flux Beam Reactor Being Decommissioned? HFBR The High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory (BNL) is being decommissioned because the Department of Energy (DOE) decided in 1999 that it would be permanently closed. The reactor was shut down in 1997 after tritium from a leak in the spent-fuel pool was found in the groundwater. The HFBR, which had operated from 1965 to 1996, was used solely for scientific research, providing neutrons for materials science, chemistry, biology, and physics experiments. The reactor was shut down for routine maintenance in November of 1996. In January 1997, tritium, a radioactive form of hydrogen and a by-product of reactor operations, was found in groundwater monitoring wells immediately south of the HFBR. The tritium

34

RELAP5 model of the high flux isotope reactor with low enriched fuel thermal flux profiles  

SciTech Connect

The High Flux Isotope Reactor (HFIR) currently uses highly enriched uranium (HEU) fabricated into involute-shaped fuel plates. It is desired that HFIR be able to use low enriched uranium (LEU) fuel while preserving the current performance capability for its diverse missions in material irradiation studies, isotope production, and the use of neutron beam lines for basic research. Preliminary neutronics and depletion simulations of HFIR with LEU fuel have arrived to feasible fuel loadings that maintain the neutronics performance of the reactor. This article illustrates preliminary models developed for the analysis of the thermal-hydraulic characteristics of the LEU core to ensure safe operation of the reactor. The beginning of life (BOL) LEU thermal flux profile has been modeled in RELAP5 to facilitate steady state simulation of the core cooling, and of anticipated and unanticipated transients. Steady state results are presented to validate the new thermal power profile inputs. A power ramp, slow depressurization at the outlet, and flow coast down transients are also evaluated. (authors)

Banfield, J.; Mervin, B.; Hart, S.; Ritchie, J.; Walker, S.; Ruggles, A.; Maldonado, G. I. [Dept. of Nuclear Engineering, Univ. of Tennessee Knoxville, Knoxville, TN 37996-2300 (United States)

2012-07-01T23:59:59.000Z

35

Rhodium self-powered neutron detector as a suitable on-line thermal neutron flux monitor in BNCT treatments  

SciTech Connect

Purpose: A rhodium self-powered neutron detector (Rh SPND) has been specifically developed by the Comision Nacional de Energia Atomica (CNEA) of Argentina to measure locally and in real time thermal neutron fluxes in patients treated with boron neutron capture therapy (BNCT). In this work, the thermal and epithermal neutron response of the Rh SPND was evaluated by studying the detector response to two different reactor spectra. In addition, during clinical trials of the BNCT Project of the CNEA, on-line neutron flux measurements using the specially designed detector were assessed. Methods: The first calibration of the detector was done with the well-thermalized neutron spectrum of the CNEA RA-3 reactor thermal column. For this purpose, the reactor spectrum was approximated by a Maxwell-Boltzmann distribution in the thermal energy range. The second calibration was done at different positions along the central axis of a water-filled cylindrical phantom, placed in the mixed thermal-epithermal neutron beam of CNEA RA-6 reactor. In this latter case, the RA-6 neutron spectrum had been well characterized by both calculation and measurement, and it presented some marked differences with the ideal spectrum considered for SPND calibrations at RA-3. In addition, the RA-6 neutron spectrum varied with depth in the water phantom and thus the percentage of the epithermal contribution to the total neutron flux changed at each measurement location. Local (one point-position) and global (several points-positions) and thermal and mixed-field thermal neutron sensitivities were determined from these measurements. Thermal neutron flux was also measured during BNCT clinical trials within the irradiation fields incident on the patients. In order to achieve this, the detector was placed on patient's skin at dosimetric reference points for each one of the fields. System stability was adequate for this kind of measurement. Results: Local mixed-field thermal neutron sensitivities and global thermal and mixed-field thermal neutron sensitivities derived from measurements performed at the RA-6 were compared and no significant differences were found. Global RA-6-based thermal neutron sensitivity showed agreement with pure thermal neutron sensitivity measurements performed in the RA-3 spectrum. Additionally, the detector response proved nearly unchanged by differences in neutron spectra from real (RA-6 BNCT beam) and ideal (considered for calibration calculations at RA-3) neutron source descriptions. The results confirm that the special design of the Rh SPND can be considered as having a pure thermal response for neutron spectra with epithermal-to-thermal flux ratios up to 12%. In addition, the linear response of the detector to thermal flux allows the use of a mixed-field thermal neutron sensitivity of 1.95 {+-} 0.05 x 10{sup -21} A n{sup -1}{center_dot}cm{sup 2}{center_dot}s. This sensitivity can be used in spectra with up to 21% epithermal-to-thermal flux ratio without significant error due to epithermal neutron and gamma induced effects. The values of the measured fluxes in clinical applications had discrepancies with calculated results that were in the range of -25% to +30%, which shows the importance of a local on-line independent measurement as part of a treatment planning quality control system. Conclusions: The usefulness of the CNEA Rh SPND for the on-line local measurement of thermal neutron flux on BNCT patients has been demonstrated based on an appropriate neutron spectra calibration and clinical applications.

Miller, Marcelo E.; Sztejnberg, Manuel L.; Gonzalez, Sara J.; Thorp, Silvia I.; Longhino, Juan M.; Estryk, Guillermo [Comision Nacional de Energia Atomica, Av. del Libertador 8250, Ciudad de Buenos Aires 1429 (Argentina); Comision Nacional de Energia Atomica, Av. del Libertador 8250, Ciudad de Buenos Aires 1429, Argentina and CONICET, Av. Rivadavia 1917, Ciudad de Buenos Aires 1033 (Argentina); Comision Nacional de Energia Atomica, Av. del Libertador 8250, Ciudad de Buenos Aires 1429 (Argentina)

2011-12-15T23:59:59.000Z

36

NEUTRON FLUX DENSITY AND SECONDARY-PARTICLE ENERGY SPECTRA AT THE 184-INCH SYNCHROCYCLOTRON MEDICAL FACILITY  

E-Print Network (OSTI)

Mischke, R. E. 1973a. Neutron-nucleus total and inelasticproduction of high-energy neutrons by stripping. Phys. Rev.1975. Dose rate due to neutrons around the alpha- Health

Smith, A.R.

2010-01-01T23:59:59.000Z

37

CRAD, Fire Protection - Oak Ridge National Laboratory High Flux...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Fire Protection - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Fire Protection - Oak Ridge National Laboratory High Flux Isotope Reactor February 2006 A section of...

38

CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G...

39

CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of...

40

CRAD, Nuclear Safety - Oak Ridge National Laboratory High Flux...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Nuclear Safety - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Nuclear Safety - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of...

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

CRAD, Safety Basis - Oak Ridge National Laboratory High Flux...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR CRAD, Safety Basis - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR February 2007 A...

42

CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR...

43

CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR...

44

CRAD, Management- Oak Ridge National Laboratory High Flux Isotope...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Management- Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Management- Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C...

45

A High Count Rate Neutron Beam Monitor for Neutron Scattering Facilities  

SciTech Connect

Abstract Beam monitors are an important diagnostic tool in neutron science facilities. Present beam monitors use either ionization chambers in integration mode, which are slow and have no timing information, or pulse counters which can easily be saturated by high beam intensities. At high flux neutron scattering facilities, neutron beam monitors with very low intrinsic efficiency (10-5) are presently selected to keep the counting rate within a feasible range, even when a higher efficiency would improve the counting statistics and yield a better measurement of the incident beam. In this work, we report on a high count rate neutron beam monitor. This beam monitor offers good timing with an intrinsic efficiency of 10-3 and a counting rate capability of over 1,000,000 cps without saturation.

Barnett, Amanda [University of Tennessee, Knoxville (UTK); Crow, Lowell [ORNL; Diawara, Yacouba [ORNL; Hayward, J P [University of Tennessee, Knoxville (UTK); Hayward, Jason P [ORNL; Menhard, Kocsis [European Synchrotron Radiation Facility (ESRF); Sedov, Vladislav N [ORNL; Funk, Loren L [ORNL

2013-01-01T23:59:59.000Z

46

High Flux Isotope Reactor | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

How to Work with HFIR How to Work with HFIR HFIR Workflow Please contact the experiment interface or coordinator for additional information and guidance. There are many...

47

Neutron flux and energy characterization of a plutonium-beryllium isotopic neutron source by Monte Carlo simulation with verification by neutron activation analysis.  

E-Print Network (OSTI)

??The purpose of this research was to characterize the neutron energy distribution and flux emitted from the UNLV plutonium-beryllium source, serial number MRC-N-W PuBe 453.… (more)

Harvey, Zachary R

2010-01-01T23:59:59.000Z

48

Comparison of the high temperature heat flux sensor to traditional heat flux gages under high heat flux conditions.  

SciTech Connect

Four types of heat flux gages (Gardon, Schmidt-Boelter, Directional Flame Temperature, and High Temperature Heat Flux Sensor) were assessed and compared under flux conditions ranging between 100-1000 kW/m2, such as those seen in hydrocarbon fire or propellant fire conditions. Short duration step and pulse boundary conditions were imposed using a six-panel cylindrical array of high-temperature tungsten lamps. Overall, agreement between all gages was acceptable for the pulse tests and also for the step tests. However, repeated tests with the HTHFS with relatively long durations at temperatures approaching 1000%C2%B0C showed a substantial decrease (10-25%) in heat flux subsequent to the initial test, likely due to the mounting technique. New HTHFS gages have been ordered to allow additional tests to determine the cause of the flux reduction.

Blanchat, Thomas K.; Hanks, Charles R.

2013-04-01T23:59:59.000Z

49

Project of Rotating Carbon High-Power Neutron Target. Research of Graphite Properties for Production of High Intensity Neutron Source  

E-Print Network (OSTI)

Project of Rotating Carbon High-Power Neutron Target. Research of Graphite Properties for Production of High Intensity Neutron Source

Gubin, K V; Bak, P A; Kot, N K; Logatchev, P V

2001-01-01T23:59:59.000Z

50

A NOVEL MICROMEGAS DETECTOR FOR IN-CORE NUCLEAR REACTOR NEUTRON FLUX MEASUREMENTS  

E-Print Network (OSTI)

1 A NOVEL MICROMEGAS DETECTOR FOR IN-CORE NUCLEAR REACTOR NEUTRON FLUX MEASUREMENTS S. ANDRIAMONJE Talence Cedex, France Future fast nuclear reactors designed for energy production and transmutation to neutron detection inside nuclear reactor is given. The advantage of this detector over conventional

Paris-Sud XI, Université de

51

A high-fluence fusion neutron source  

SciTech Connect

A conceptual design of a D-T fusion facility for continuous production of 14-MeV neutron wall loading from 5 to 10 MW/m/sup 2/ at the plasma surface is presented. In this design, D-T neutrons are produced in a linear, two-component plasma formed by neutral beam irradiation of a fully ionized warm plasma target. The beam energy, which is deposited in the center, is transferred to the warm plasma mainly by electron drag and is conducted along the target plasma column to end regions where it is absorbed in neutral gas at high pressure. The target plasma is operated in a regime where electron thermal conduction along the column is the controlling energy-loss process. The loss rate is minimized by adjusting the diameter and length of the plasma column. A substantial gradient in T/sub e/ along the column results in recombination of the plasma to gas in the end-regions before impact on the end walls. The resultant hot gas is cooled by contact with large-area heat exchangers. In this way, the large steady-state heat load from the injected neutral beams is diffused and removed at tolerable heat flux levels. The reacting plasma is essentially an extrapolation of the 2XIIB high-..beta.. plasma to higher magnetic field, ion energy, and density. 12 refs., 4 figs.

Coensgen, F.H.; Casper, T.A.; Correll, D.L.; Damm, C.C.; Futch, A.H.; Logan, B.G.; Molvik, A.W.; Bulmer, R.H.

1988-02-17T23:59:59.000Z

52

Flux noise in high-temperature superconductors  

Science Journals Connector (OSTI)

Spontaneously created vortex-antivortex pairs are the predominant source of flux noise in high-temperature superconductors. In principle, flux noise measurements allow to check theoretical predictions for both the distribution of vortex-pair sizes and for the vortex diffusivity. In this paper the flux-noise power spectrum is calculated for the highly anisotropic high-temperature superconductor Bi2Sr2CaCu2O8+?, both for bulk crystals and for ultrathin films. The spectrum is basically given by the Fourier transform of the temporal magnetic-field correlation function. We start from a Berezinskii-Kosterlitz-Thouless-type theory and incorporate vortex diffusion, intrapair vortex interaction, and annihilation of pairs by means of a Fokker-Planck equation to determine the noise spectrum below and above the superconducting transition temperature. We find white noise at low frequencies ? and a spectrum proportional to 1/?3/2 at high frequencies. The crossover frequency between these regimes strongly depends on temperature. The results are compared with earlier results of computer simulations.

Carsten Timm

1997-02-01T23:59:59.000Z

53

High Flux Isotope Reactor power upgrade status  

SciTech Connect

A return to 100-MW operation is being planned for the High Flux Isotope Reactor (HFIR). Recent improvements in fuel element manufacturing procedures and inspection equipment will be exploited to reduce hot spot and hot streak factors sufficiently to permit the power upgrade without an increase in primary coolant pressure. Fresh fuel elements already fabricated for future use are being evaluated individually for power upgrade potential based on their measured coolant channel dimensions.

Rothrock, R.B.; Hale, R.E. [Oak Ridge National Lab., TN (United States); Cheverton, R.D. [Delta-21 Resources Inc., Oak Ridge, TN (United States)

1997-03-01T23:59:59.000Z

54

Joint Institute for Neutron Sciences | ornl.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Facilities and Capabilities High Flux Isotope Reactor Spallation Neutron Source Joint Institute for Neutron Sciences Scientific Labs Neutron Science Home | Science & Discovery |...

55

Bayesian statistics applied to neutron activation data for reactor flux spectrum analysis  

Science Journals Connector (OSTI)

Abstract In this paper, we present a statistical method, based on Bayesian statistics, to analyze the neutron flux spectrum from the activation data of different isotopes. The experimental data were acquired during a neutron activation experiment performed at the TRIGA Mark II reactor of Pavia University (Italy) in four irradiation positions characterized by different neutron spectra. In order to evaluate the neutron flux spectrum, subdivided in energy groups, a system of linear equations, containing the group effective cross sections and the activation rate data, has to be solved. However, since the system’s coefficients are experimental data affected by uncertainties, a rigorous statistical approach is fundamental for an accurate evaluation of the neutron flux groups. For this purpose, we applied the Bayesian statistical analysis, that allows to include the uncertainties of the coefficients and the a priori information about the neutron flux. A program for the analysis of Bayesian hierarchical models, based on Markov Chain Monte Carlo (MCMC) simulations, was used to define the problem statistical model and solve it. The first analysis involved the determination of the thermal, resonance-intermediate and fast flux components and the dependence of the results on the Prior distribution choice was investigated to confirm the reliability of the Bayesian analysis. After that, the main resonances of the activation cross sections were analyzed to implement multi-group models with finer energy subdivisions that would allow to determine the neutron flux groups, their uncertainties and correlations with good accuracy. The results were then compared with the ones obtained from the Monte Carlo simulations of the reactor fluxes performed with the MCNP code, finding in general a good agreement.

Davide Chiesa; Ezio Previtali; Monica Sisti

2014-01-01T23:59:59.000Z

56

A neutron multiplicity meter for deep underground muon-induced high-energy neutron measurements  

Science Journals Connector (OSTI)

We present, for the first time, the design of an instrument capable of measuring the high energy ( > 60 MeV ) muon-induced neutron flux deep underground. The instrument is based on applying the Gd-loaded liquid-scintillator technique to measure the rate of multiple low-energy neutron events produced in a Pb target and from this measurement to infer the rate of high energy neutron events. This unique signature allows both for efficient tagging of neutron multiplicity events as well as rejection of random gamma backgrounds so effectively that typical low-background techniques are not required. We present design studies based on Monte Carlo simulations that show that an apparatus consisting of a Pb target of 200 cm by 200 cm area by 60 cm thickness covered by a 60 cm thick Gd-loaded liquid scintillator (0.5% Gd content) detector could measure, at a depth of 2000 meters of water equivalent (m.w.e), a rate of 70 ± 8 (stat) events/year with a background of less than 10 events/year. We discuss the relevance of this technique to measuring the muon-induced neutron background in searches for dark matter in the form of Weakly Interacting Massive Particles (WIMP). Based on these studies, we also discuss the benefits of using a neutron multiplicity meter as a component of active shielding in such experiments.

R. Hennings-Yeomans; D.S. Akerib

2007-01-01T23:59:59.000Z

57

CRAD, Safety Basis - Oak Ridge National Laboratory High Flux...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Safety Basis - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G...

58

Energetic ion diagnostics using neutron flux measurements during pellet injection  

SciTech Connect

Neutron measurements during injection of deuterium pellets into deuterium plasmas on the Tokamak Fusion Test Reactor (TFTR) indicate that the fractional increase in neutron emission about 0.5 msec after pellet injection is proportional to the fraction of beam-plasma reactions to total fusion reactions in the unperturbed plasma. These observations suggest three diagnostic applications of neutron measurements during pellet injection: (1) measurement of the beam-plasma reaction rate in deuterium plasmas for use in determining the fusion Q in an equivalent deuterium-tritium plasma, (2) measurement of the radial profile of energetic beam ions by varying the pellet size and velocity, and (3) measurement of the ''temperature'' of ions accelerated during wave heating. 18 refs., 3 figs.

Heidbrink, W.W.

1986-01-01T23:59:59.000Z

59

The prototype of a detector for monitoring the cosmic radiation neutron flux on ground  

SciTech Connect

This work presents a comparison between the results of experimental tests and Monte Carlo simulations of the efficiency of a detector prototype for on-ground monitoring the cosmic radiation neutron flux. The experimental tests were made using one conventional {sup 241}Am-Be neutron source in several incidence angles and the results were compared to that ones obtained with a Monte Carlo simulation made with MCNPX Code.

Lelis Goncalez, Odair; Federico, Claudio Antonio; Mendes Prado, Adriane Cristina; Galhardo Vaz, Rafael; Tizziani Pazzianotto, Mauricio [Instituto de Estudos Avancados - IEAv/DCTA - Sao Jose dos Campos, SP (Brazil); Semmler, Renato [Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP - Sao Paulo, SP (Brazil)

2013-05-06T23:59:59.000Z

60

Altitude and latitude variations in avionics SEU and atmospheric neutron flux  

SciTech Connect

The direct cause of single event upsets in SRAMs at aircraft altitudes by the atmospheric neutrons has previously been documented. The variation of the in-flight SEU rate with latitude is demonstrated by new data over a wide range of geographical locations. New measurements and models of the atmospheric neutron flux are also evaluated to characterize its variation with altitude, latitude and solar activity.

Normand, E.; Baker, T.J. (Boeing Defense and Space Group, Seattle, WA (United States))

1993-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

The measurement of absolute thermal neutron flux using liquid scintillation counting techniques  

E-Print Network (OSTI)

was computed as the square root of the sum of the squares of the individual errors . The flux at the same location in the core and at the same reactor power level was measured by the conventional technique of gold foil 34 activation. This measurement... back to 1932 when the neutron was discovered by Chadwick. With the advent of the nuclear reactor in 1942 the problem of absolute neutron flux determination became increasingly important. Since the operating power of a thermal reactor is directly...

Walker, Jack Vernon

2012-06-07T23:59:59.000Z

62

Sandia Neutron Detector Is Based on Polyacetylene  

Science Journals Connector (OSTI)

Sandia Neutron Detector Is Based on Polyacetylene ... It also might form the basis of an electrically readable dosimeter that records neutron flux (measured as neutrons per square centimeter) as well as a detector that could provide a cross-sectional image of neutron flux with high spatial resolution. ... Hence, most neutron detectors use a converter material that converts the neutrons to charged particles. ...

RUDY BAUM

1987-02-09T23:59:59.000Z

63

High Heat Flux Thermoelectric Module Using Standard Bulk Material  

Energy.gov (U.S. Department of Energy (DOE))

Presents high heat flux thermoelectric module design for cooling using a novel V-shaped shunt configuration with bulk TE elements achieving high area packing fractions

64

High flux isotope reactor cold source preconceptual design study report  

SciTech Connect

In February 1995, the deputy director of Oak Ridge National Laboratory (ORNL) formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced Neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. The anticipated cold source will consist of a cryogenic LH{sub 2} moderator plug, a cryogenic pump system, a refrigerator that uses helium gas as a refrigerant, a heat exchanger to interface the refrigerant with the hydrogen loop, liquid hydrogen transfer lines, a gas handling system that includes vacuum lines, and an instrumentation and control system to provide constant system status monitoring and to maintain system stability. The scope of this project includes the development, design, safety analysis, procurement/fabrication, testing, and installation of all of the components necessary to produce a working cold source within an existing HFIR beam tube. This project will also include those activities necessary to transport the cold neutron beam to the front face of the present HFIR beam room. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and research and development (R and D), (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the preconceptual phase and establishes the concept feasibility. The information presented includes the project scope, the preliminary design requirements, the preliminary cost and schedule, the preliminary performance data, and an outline of the various plans for completing the project.

Selby, D.L.; Bucholz, J.A.; Burnette, S.E. [and others

1995-12-01T23:59:59.000Z

65

Achieving high flux amplification in a gun-driven, flux-core spheromak  

Science Journals Connector (OSTI)

A new means of operating flux-core spheromaks with possibly increased stability, confinement and pulse length is analysed by a resistive magnetohydrodynamic (MHD) model. High amplification of the bias poloidal flux, required to minimize ohmic losses, is achieved by reducing the bias rapidly in a plasma formed at a lower amplification. The plasma separatrix is predicted to expand and incorporate the removed bias flux maintaining the total poloidal flux within the spheromak's flux-conserving wall. MHD energy on open magnetic field lines is reduced, reducing magnetic fluctuation levels. A means of experimental verification is suggested that may point the way to fusion-relevant spheromaks.

E.B. Hooper; D.N. Hill; H.S. McLean; C.A. Romero-Talamás; R.D. Wood

2007-01-01T23:59:59.000Z

66

CRAD, Management- Oak Ridge National Laboratory High Flux Isotope Reactor |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Management- Oak Ridge National Laboratory High Flux Isotope Management- Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Management- Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Management in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Management- Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications CRAD, Nuclear Safety - Oak Ridge National Laboratory High Flux Isotope

67

CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Engineering - Oak Ridge National Laboratory High Flux Isotope Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Engineering Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor

68

CRAD, Nuclear Safety - Oak Ridge National Laboratory High Flux Isotope  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

CRAD, Nuclear Safety - Oak Ridge National Laboratory High Flux CRAD, Nuclear Safety - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Nuclear Safety - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Nuclear Safety Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Nuclear Safety - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor

69

Neutron scattering at high pressure  

Science Journals Connector (OSTI)

Neutron scattering spectra at pressures up to 30 kilobar in the temperature range 300–4 K have been obtained with a compact clamped type apparatus. The pressure cell geometry by allowing the detection of neutronsscattered in a plane makes it compatible with operation on crystal spectrometers both for elastic and inelastic scattering. The instrument is light (4.5 kg) and easy to move. An external diameter of 68 mm makes the pressure cell adaptable to standard cryostats or furnaces.

D. Bloch; J. Paureau; J. Voiron; G. Parisot

1976-01-01T23:59:59.000Z

70

Fully portable, highly flexible dilution refrigerator systems for neutron scattering  

E-Print Network (OSTI)

775 Fully portable, highly flexible dilution refrigerator systems for neutron scattering P. A systems developed specifically for neutron scattering environ- ments. The refrigerators are completely relatively recently however, the lowest temperatures available in almost all neutron scattering laboratories

Boyer, Edmond

71

Measurement of Neutron and Muon Fluxes 100~m Underground with the SciBath Detector  

SciTech Connect

The SciBath detector is an 80 liter liquid scintillator detector read out by a three dimensional grid of 768 wavelength-shifting fibers. Initially conceived as a fine-grained charged particle detector for neutrino studies that could image charged particle tracks in all directions, it is also sensitive to fast neutrons (15-200 MeV). In fall of 2011 the apparatus performed a three month run to measure cosmic-induced muons and neutrons 100~meters underground in the FNAL MINOS near-detector area. Data from this run has been analyzed and resulted in measurements of the cosmic muon flux as \

Garrison, Lance

2014-01-01T23:59:59.000Z

72

CRAD, Emergency Management - Oak Ridge National Laboratory High Flux  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge National Laboratory High Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Emergency Management - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Emergency Management Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Emergency Management - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications CRAD, Emergency Management - Oak Ridge National Laboratory High Flux

73

CRAD, Radiological Controls - Oak Ridge National Laboratory High Flux  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

High High Flux Isotope Reactor CRAD, Radiological Controls - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Radiation Protection Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Radiological Controls - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor

74

CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge National Laboratory High Flux Isotope Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Engineering Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory, High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR More Documents & Publications

75

CRAD, Management - Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge National Laboratory High Flux Isotope Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR CRAD, Management - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Management portion of an Operational Readiness Review of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Management - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR More Documents & Publications

76

CRAD, Training - Oak Ridge National Laboratory High Flux Isotope Reactor |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Reactor Reactor CRAD, Training - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Training Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor. RADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Training - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications CRAD, Nuclear Safety - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Training - Oak Ridge National Laboratory High Flux Isotope Reactor

77

CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Reactor Reactor CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Maintenance Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications CRAD, Safety Basis - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor

78

CRAD, DOE Oversight - Oak Ridge National Laboratory High Flux Isotope  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge National Laboratory High Flux Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, DOE Oversight - Oak Ridge National Laboratory High Flux Isotope Reactor A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a DOE independent oversight assessment of the Oak Ridge National Laboratory programs for oversight of its contractors. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, DOE Oversight - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications CRAD, Nuclear Safety - Oak Ridge National Laboratory High Flux Isotope Reactor

79

High Flux Beam Reactor | Environmental Restoration Projects | BNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Environmental Protection Division Environmental Protection Division Home Reactor Projects Celebrating DOE's Cleanup Accomplishments (PDF) Brookhaven Graphite Research Reactor(BGRR) BGRR Overview BGRR Complex Description Decommissioning Decision BGRR Complex Cleanup Actions BGRR Documents BGRR Science & Accomplishments High Flux Beam Reactor (HFBR) HFBR Overview HFBR Complex Description Decommissioning Decision HFBR Complex Cleanup Actions HFBR Documents HFBR Science & Accomplishments Groundwater Protection Group Environmental Protection Division Contact > See also: HFBR Science & Accomplishments High Flux Beam Reactor Under the U.S. Department of Energy (DOE), the High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory (BNL) underwent stabilization and partial decommissioning to prepare the HFBR confinement for long-term safe

80

CRAD, Environmental Protection - Oak Ridge National Laboratory High Flux  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Environmental Protection - Oak Ridge National Laboratory High Environmental Protection - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Environmental Protection - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Environmental Compliance Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Environmental Protection - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

CRAD, Configuration Management - Oak Ridge National Laboratory High Flux  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge National Laboratory High Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR CRAD, Configuration Management - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR February 2007, A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Configuration Managment Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory, High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Configuration Management - Oak Ridge National Laboratory High Flux

82

CRAD, Configuration Management - Oak Ridge National Laboratory High Flux  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Configuration Management - Oak Ridge National Laboratory High Configuration Management - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Configuration Management - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Configuration Management Program in preparation for restart of the Oak Ridge National Laboratory, High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Configuration Management - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications

83

CRAD, Emergency Management - Oak Ridge National Laboratory High Flux  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Oak Ridge National Laboratory High Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR CRAD, Emergency Management - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Emergency Management Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Emergency Management - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR

84

CRAD, Fire Protection - Oak Ridge National Laboratory High Flux Isotope  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Fire Protection - Oak Ridge National Laboratory High Flux Fire Protection - Oak Ridge National Laboratory High Flux Isotope Reactor CRAD, Fire Protection - Oak Ridge National Laboratory High Flux Isotope Reactor February 2006 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2006 Commencement of Operations assessment of the Fire Protection program at the Idaho National Laboratory, Idaho Accelerated Retrieval Project Phase II. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Fire Protection - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications

85

CRAD, Safety Basis - Oak Ridge National Laboratory High Flux Isotope  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Reactor Contractor ORR Reactor Contractor ORR CRAD, Safety Basis - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Safety Basis portion of an Operational Readiness Review of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Safety Basis - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR More Documents & Publications CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor

86

CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Reactor Contractor ORR Reactor Contractor ORR CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Maintenance Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Maintenance - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR More Documents & Publications CRAD, Engineering - Oak Ridge National Laboratory High Flux Isotope Reactor

87

CRAD, Training - Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Reactor Contractor ORR Reactor Contractor ORR CRAD, Training - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Training Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Training - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR More Documents & Publications CRAD, Conduct of Operations - Oak Ridge National Laboratory High Flux

88

CRAD, Conduct of Operations - Oak Ridge National Laboratory High Flux  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Reactor Reactor CRAD, Conduct of Operations - Oak Ridge National Laboratory High Flux Isotope Reactor February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February, 2007 assessment of the Conduct of Operations Program in preparation for restart of the Oak Ridge National Laboratory, High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Conduct of Operations - Oak Ridge National Laboratory High Flux Isotope Reactor More Documents & Publications CRAD, Fire Protection - Oak Ridge National Laboratory High Flux Isotope

89

Temperature variations in the flux of high-energy muons  

Science Journals Connector (OSTI)

The flux of high-energy muons (threshold energy, 220 GeV) as a function of ... the correlation coefficient between the counting rate of muons and the temperature of the atmosphere at...

M. G. Kostyuk; V. B. Petkov…

2011-06-01T23:59:59.000Z

90

Measurements of neutrons produced by high-energy muons at the Boulby Underground Laboratory  

Science Journals Connector (OSTI)

We present the first measurements of the muon-induced neutron flux at the Boulby Underground Laboratory. The experiment was carried out with an 0.73 tonne liquid scintillator that also served as an anticoincidence system for the ZEPLIN-II direct dark matter search. The experimental method exploited the delayed coincidences between high-energy muon signals and gamma-rays from radiative neutron capture on hydrogen or other elements. The muon-induced neutron rate, defined as the average number of detected neutrons per detected muon, was measured as 0.079 ± 0.003 (stat.) neutrons/muon using neutron-capture signals above 0.55 MeV in a time window of 40–190 ?s after the muon trigger. Accurate Monte Carlo simulations of the neutron production, transport and detection in a precisely modeled laboratory and experimental setup using the GEANT4 toolkit gave a result 1.8 times higher than the measured value. The difference greatly exceeds all statistical and systematic uncertainties. As the vast majority of neutrons detected in the current setup were produced in lead we evaluated from our measurements the neutron yield in lead as ( 1.31 ± 0.06 ) × 10 - 3 neutrons/muon/(g/cm2) for a mean muon energy of about 260 GeV.

H.M. Araújo; J. Blockley; C. Bungau; M.J. Carson; H. Chagani; E. Daw; B. Edwards; C. Ghag; E.V. Korolkova; V.A. Kudryavtsev; P.K. Lightfoot; A. Lindote; I. Liubarsky; R. Lüscher; P. Majewski; K. Mavrokoridis; J.E. McMillan; A.St.J. Murphy; S.M. Paling; J. Pinto da Cunha; R.M. Preece; M. Robinson; N.J.T. Smith; P.F. Smith; N.J.C. Spooner; T.J. Sumner; R.J. Walker; H. Wang; J. White

2008-01-01T23:59:59.000Z

91

Measurements of neutrons produced by high-energy muons at the Boulby Underground Laboratory  

E-Print Network (OSTI)

We present the first measurements of the muon-induced neutron flux at the Boulby Underground Laboratory. The experiment was carried out with an 0.73 tonne liquid scintillator that also served as an anticoincidence system for the ZEPLIN-II direct dark matter search. The experimental method exploited the delayed coincidences between high-energy muon signals and gamma-rays from radiative neutron capture on hydrogen or other elements. The muon-induced neutron rate, defined as the average number of detected neutrons per detected muon, was measured as $0.079 \\pm 0.003$ (stat.) neutrons/muon using neutron-capture signals above 0.55 MeV in a time window of 40-190 $\\mu$s after the muon trigger. Accurate Monte Carlo simulations of the neutron production, transport and detection in a precisely modeled laboratory and experimental setup using the GEANT4 toolkit gave a result 1.8 times higher than the measured value. The difference greatly exceeds all statistical and systematic uncertainties. As the vast majority of neutrons detected in the current setup were produced in lead we evaluated from our measurements the neutron yield in lead as $(1.31 \\pm 0.06) \\times 10^{-3}$ neutrons/muon/(g/cm$^2$) for a mean muon energy of about 260 GeV.

H. M. Araujo; J. Blockley; C. Bungau; M. J. Carson; H. Chagani; E. Daw; B. Edwards; C. Ghag; E. V. Korolkova; V. A. Kudryavtsev; P. K. Lightfoot; A. Lindote; I. Liubarsky; R. Luscher; P. Majewski; K. Mavrokoridis; J. E. McMillan; A. St. J. Murphy; S. M. Paling; J. Pinto da Cunha; R. M. Preece; M. Robinson; N. J. T. Smith; P. F. Smith; N. J. C. Spooner; T. J. Sumner; R. J. Walker; H. Wang; J. White

2008-05-20T23:59:59.000Z

92

An investigation of the elimination of detector perturbations in pure thermal neutron fluxes  

E-Print Network (OSTI)

of the requirements for the degree of MASTER OF SCIENCE August 1963 Major Subject Nuclear Engineering AN INVESTIGATION OF THE ELIMINATION OF DETECTOR PERTURBATIONS IN PURE THERMAL NEUTRON FLUXES A Thesis By Donald E~rerett Fettz Approx~ed as to style.... Randall and Jack V. Walker for their invaluable guidance and assistance during the course of this research, and to Dr. Robert G. Cochran for his suggestions and encouragement. Thanks is also extended to Mr, Floy W. Smith and the staff of the Nuclear...

Feltz, Donald Everett

2012-06-07T23:59:59.000Z

93

Numerical studies of the flux-to-current ratio method in the KIPT neutron source facility  

SciTech Connect

The reactivity of a subcritical assembly has to be monitored continuously in order to assure its safe operation. In this paper, the flux-to-current ratio method has been studied as an approach to provide the on-line reactivity measurement of the subcritical system. Monte Carlo numerical simulations have been performed using the KIPT neutron source facility model. It is found that the reactivity obtained from the flux-to-current ratio method is sensitive to the detector position in the subcritical assembly. However, if multiple detectors are located about 12 cm above the graphite reflector and 54 cm radially, the technique is shown to be very accurate in determining the k{sub eff} this facility in the range of 0.75 to 0.975. (authors)

Cao, Y.; Gohar, Y.; Zhong, Z. [Nuclear Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

2013-07-01T23:59:59.000Z

94

PRACTICAL NEUTRON DOSIMETRY AT HIGH ENERGIES  

E-Print Network (OSTI)

and Chupp, E. L. "Cosmic Ray Neutron Energy Spectrum." Phys.Study of Cosmic-Ray Neutrons." National Aero­ nautics andStudy of Cosmic-Ray Neutrons: Mid-Latitude Flights." Health

McCaslin, J.B.

2010-01-01T23:59:59.000Z

95

Thin, Free-Standing Films For High Resolution Neutron Imaging.  

E-Print Network (OSTI)

??Thin, free-standing boro-phosphosilicate glass (BPSG) films were fabricated at PSU Nanofab to serve as prototype neutron converters for a proposed high resolution neutron imaging system… (more)

Trivelpiece, Cory

2010-01-01T23:59:59.000Z

96

High energy neutron Computed Tomography developed  

NLE Websites -- All DOE Office Websites (Extended Search)

objects. May 9, 2014 Neutron tomography horizontal "slice" of a tungsten and polyethylene test object containing tungsten carbide BBs. Neutron tomography horizontal "slice"...

97

Potential application of curium neutron detection in the high reliability safeguards approach for remotely handled nuclear facilities  

SciTech Connect

The study presented in this paper is part of a series of quantitative modeling efforts to characterize the neutron flux for the major subsystems in a pyroprocessing facility. An MCNPX model has established the electroreduction process, in which uranium oxide is converted into a metal product by electrochemical methods. This process is important because the electroreduction stage is the earliest point in the system where a diversion attempt could occur. This paper will present neutron flux for a commercial batch size. The intent of this study is to determine if the magnitude of the flux is sufficiently high as to affect facility design. (author)

Borrelli, R.A.

2013-07-01T23:59:59.000Z

98

High flux heat transfer in a target environment  

E-Print Network (OSTI)

High flux heat transfer in a target environment T. Davenne High Power Targets Group Rutherford Valid for: Consider turbulent heat transfer in a 1.5mm diameter pipe ­ Dittus Boelter correlation Achenbach correlation for heat transfer in a packed bed of spheres Max power density for a sphere

McDonald, Kirk

99

CRAD, Conduct of Operations - Oak Ridge National Laboratory High Flux  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Reactor Contractor ORR Reactor Contractor ORR CRAD, Conduct of Operations - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR February 2007 A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February, 2007 assessment of the Conduct of Operations Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory, High Flux Isotope Reactor. CRADs provide a recommended approach and the types of information to gather to assess elements of a DOE contractor's programs. CRAD, Conduct of Operations - Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR More Documents & Publications

100

Neutron Microscope  

Science Journals Connector (OSTI)

We report successful operation of a neutron microscope using ultracold neutrons at the high-flux reactor at Grenoble. A sharp, achromatic image of an object slit was obtained at a magnification of 50. The measured resolution of 0.1 mm was limited mainly by the available beam intensity, not by aberrations.

P. Herrmann; K. -A. Steinhauser; R. Gähler; A. Steyerl; W. Mampe

1985-05-06T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Neutron scattering at high pressure D. B. McWhan  

E-Print Network (OSTI)

715 Neutron scattering at high pressure D. B. McWhan Room 1D-234, Murray Hill, New Jersey 07974, U scattering at steady-state and pulsed sources are reviewed. The pressure cells available at most neutron 10 GPa have been made. For elastic scattering, a comparison is made between neutron scattering and X

Paris-Sud XI, Université de

102

PoGOLite: Neutron Background Studies for High Latitudes  

E-Print Network (OSTI)

PoGOLite: Neutron Background Studies for High Latitudes Maria Fernanda Muñoz Salinas SH2006. The measurements showed a neutron background ten times higher than expected. Because of this, new simulations of the PoGOLite flight which will take place in the summer of 2012. The neutron background was simulated

Haviland, David

103

E-Print Network 3.0 - achieve high flux Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

(SAA) and in the polar regions. The flux of energetic protons is known to be highly anisotropic... the flux is highly anisotropic. Rough comparisons of the fluxes from some...

104

An investigation of the neutron flux in bone-fluorine phantoms comparing accelerator based in vivo neutron activation analysis and FLUKA simulation data  

Science Journals Connector (OSTI)

Abstract We have tested the Monte Carlo code FLUKA for its ability to assist in the development of a better system for the in vivo measurement of fluorine. We used it to create a neutron flux map of the inside of the in vivo neutron activation analysis irradiation cavity at the McMaster Accelerator Laboratory. The cavity is used in a system that has been developed for assessment of fluorine levels in the human hand. This study was undertaken to (i) assess the FLUKA code, (ii) find the optimal hand position inside the cavity and assess the effects on precision of a hand being in a non-optimal position and (iii) to determine the best location for our ?-ray detection system within the accelerator beam hall. Simulation estimates were performed using FLUKA. Experimental measurements of the neutron flux were performed using Mn wires. The activation of the wires was measured inside (1) an empty bottle, (2) a bottle containing water, (3) a bottle covered with cadmium and (4) a dry powder-based fluorine phantom. FLUKA was used to simulate the irradiation cavity, and used to estimate the neutron flux in different positions both inside, and external to, the cavity. The experimental results were found to be consistent with the Monte Carlo simulated neutron flux. Both experiment and simulation showed that there is an optimal position in the cavity, but that the effect on the thermal flux of a hand being in a non-optimal position is less than 20%, which will result in a less than 10% effect on the measurement precision. FLUKA appears to be a code that can be useful for modeling of this type of experimental system.

F. Mostafaei; F.E. McNeill; D.R. Chettle; W. Matysiak; C. Bhatia; W.V. Prestwich

2015-01-01T23:59:59.000Z

105

Neutron Matter from Low to High Density  

E-Print Network (OSTI)

Neutron matter is an intriguing nuclear system with multiple connections to other areas of physics. Considerable progress has been made over the last two decades in exploring the properties of pure neutron fluids. Here we begin by reviewing work done to explore the behavior of very low density neutron matter, which forms a strongly paired superfluid and is thus similar to cold Fermi atoms, though at energy scales differing by many orders of magnitude. We then increase the density, discussing work that ties the study of neutron matter with the determination of the properties of neutron-rich nuclei and neutron-star crusts. After this, we review the impact neutron matter at even higher densities has on the mass-radius relation of neutron stars, thereby making contact with astrophysical observations.

Gandolfi, Stefano; Carlson, J

2015-01-01T23:59:59.000Z

106

A High-Efficiency Neutron Detector  

Science Journals Connector (OSTI)

... for neutrons with energies lying between 100 and 100,000 eV. A practicable thickness of boron-10 (2-2J cm.) is effectively 'black' to neutrons of up to 10, ...

J. C. DUCKWORTH; A. W. MERRISON; A. WHITTAKER

1950-01-14T23:59:59.000Z

107

CRAD, Engineering- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Engineering Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor.

108

CRAD, Management- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Management in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor.

109

CRAD, Training- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Training Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor.

110

Spallation Neutron Source (SNS) | U.S. DOE Office of Science...  

Office of Science (SC) Website

(SUF) Division SUF Home About User Facilities User Facilities Dev X-Ray Light Sources Neutron Scattering Facilities High Flux Isotope Reactor (HFIR) Lujan Neutron Scattering...

111

Remote high-temperature insulatorless heat-flux gauge  

DOE Patents (OSTI)

A remote optical heat-flux gauge for use in extremely high temperature environments is described. This application is possible because of the use of thermographic phosphors as the sensing media, and the omission of the need for an intervening layer of insulator between phosphor layers. The gauge has no electrical leads, but is interrogated with ultraviolet or laser light. The luminescence emitted by the two phosphor layers, which is indicative of the temperature of the layers, is collected and analyzed in order to determine the heat flux incident on the surface being investigated. The two layers of thermographic phosphor must be of different materials to assure that the spectral lines collected will be distinguishable. Spatial heat-flux measurements can be made by scanning the light across the surface of the gauge. 3 figures.

Noel, B.W.

1993-12-28T23:59:59.000Z

112

Remote high-temperature insulatorless heat-flux gauge  

DOE Patents (OSTI)

A remote optical heat-flux gauge for use in extremely high temperature environments is described. This application is possible because of the use of thermographic phosphors as the sensing media, and the omission of the need for an intervening layer of insulator between phosphor layers. The gauge has no electrical leads, but is interrogated with ultraviolet or laser light. The luminescence emitted by the two phosphor layers, which is indicative of the temperature of the layers, is collected and analyzed in order to determine the heat flux incident on the surface being investigated. The two layers of thermographic phosphor must be of different materials to assure that the spectral lines collected will be distinguishable. Spatial heat-flux measurements can be made by scanning the light across the surface of the gauge.

Noel, Bruce W. (Espanola, NM)

1993-01-01T23:59:59.000Z

113

The Dynamics of Flux Tubes in a High Beta Plasma  

E-Print Network (OSTI)

We suggest a new model for the structure of a magnetic field embedded high $\\beta$ turbulent plasma, based on the popular notion that the magnetic field will tend to separate into individual flux tubes. We point out that interactions between the flux tubes will be dominated by coherent effects stemming from the turbulent wakes created as the fluid streams by the flux tubes. Balancing the attraction caused by shielding effects with turbulent diffusion we find that flux tubes have typical radii comparable to the local Mach number squared times the large scale eddy length, are arranged in a one dimensional fractal pattern, have a radius of curvature comparable to the largest scale eddies in the turbulence, and have an internal magnetic pressure comparable to the ambient pressure. When the average magnetic energy density is much less than the turbulent energy density the radius, internal magnetic field and curvature scale of the flux tubes will be smaller than these estimates. Realistic resistivity does not alter the macroscopic properties of the fluid or the large scale magnetic field. In either case we show that the Sweet-Parker reconnection rate is much faster than an eddy turnover time. Realistic stellar plasmas are expected to either be in the ideal limit (e.g. the solar photosphere) or the resistive limit (most of the solar convection zone). All current numerical simulations of three dimensional MHD turbulence are in the viscous regime and are inapplicable to stars or accretion disks.

E. T. Vishniac

1994-07-21T23:59:59.000Z

114

High efficiency proportional neutron detector with solid liner internal structures  

DOE Patents (OSTI)

A tube-style neutron detector, a panel-style neutron detector incorporating a plurality of tube-style neutron detectors, and a panel-style neutron detector including a plurality of anode wires are provided. A plurality of channels is provided in a neutron detector such that each channel has an inner surface of a coating layer including a neutron-absorbing material. A wire anode is provided at end of each channel so that electrons generated by a charged daughter particle generated by a neutron are collected to detect a neutron-matter interaction. Moderator units can be incorporated into a neutron detector to provide improved detection efficiencies and/or to determine neutron energy spectrum. Gas-based proportional response from the neutron detectors can be employed for special nuclear material (SNM) detection. This neutron detector can provide similar performance to .sup.3He-based detectors without requiring .sup.3He and without containing toxic, flammable, or high-pressure materials.

Kisner, Roger Allen; Holcomb, David Eugene; Brown, Gilbert M.

2014-08-05T23:59:59.000Z

115

Operation of the ORNL High Particle Flux Helicon Plasma Source  

SciTech Connect

A high power, high particle flux rf-based helicon plasma source has been constructed at ORNL and operated at power levels up to 30 kW. High-density hydrogen and helium plasmas have been produced. The source has been designed as the basis for a linear plasma materials interaction (PMI) test facility that will generate particle fluxes {Gamma}{sub p}10{sup 23} m{sup -3} s{sup -1}, and utilize additional ion and electron cyclotron heating to produce high parallel (to the magnetic field) heat fluxes of {approx}10 MW/m{sup 2}. An rf-based source for PMI research is of interest because high plasma densities are generated with no internal electrodes, allowing true steady state operation with minimal impurity generation. The ORNL helicon source has a diameter of 15 cm and to-date has operated at a frequency f = 13.56 MHz, with magnetic field strength |B| in the antenna region up to {approx}0.15 T. Maximum densities of 3x10{sup 19} m{sup -3} in He and 2.5x10{sup 19} m{sup -3} in H have been achieved. Radial density profiles have been seen to be dependent on the axial |B| profile.

Goulding, R. H.; Biewer, T. M.; Caughman, J. B. O.; Chen, G. C.; Owen, L. W.; Sparks, D. O. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6169 (United States)

2011-12-23T23:59:59.000Z

116

Operation of the ORNL High Particle Flux Helicon Plasma Source  

SciTech Connect

A high power, high particle flux rf-based helicon plasma source has been constructed at ORNL and operated at power levels up to 30 kW. High-density hydrogen and helium plasmas have been produced. The source has been designed as the basis for a linear plasma materials interaction (PMI) test facility that will generate particle fluxes Gamma(p) > 10(23) M-3 s(-1), and utilize additional ion and electron cyclotron heating to produce high parallel (to the magnetic field) heat fluxes of similar to 10 MW/m(2). An rf-based source for PMI research is of interest because high plasma densities are generated with no internal electrodes, allowing true steady state operation with minimal impurity generation. The ORNL helicon source has a diameter of 15 cm and to-date has operated at a frequency f = 13.56 MHz, with magnetic field strength vertical bar B vertical bar in the antenna region up to similar to 0.15 T. Maximum densities of 3 x 10(19) M-3 in He and 2.5 x 10(19) m(-3) in H have been achieved. Radial density profiles have been seen to be dependent on the axial vertical bar B vertical bar profile.

Goulding, Richard Howell [ORNL; Biewer, Theodore M [ORNL; Caughman, John B [ORNL; Chen, Guangye [ORNL; Owen, Larry W [ORNL; Sparks, Dennis O [ORNL

2011-01-01T23:59:59.000Z

117

High-temperature Embrittlement of Stainless Steel irradiated in Fast Fluxes  

Science Journals Connector (OSTI)

... , much lower than in thermal fluxes, so that the production rate of helium from boron-10 is very much slower (the fast reactor rate is about 1 per cent of ... thermal flux is critically dependent on the boron content and virtually ceases when all the boron-10 has been burnt up, that is, after a thermal dose of about 1021 neutrons ...

A. S. FRASER; I. R. BIRSS; C. CAWTHORNE

1966-07-16T23:59:59.000Z

118

Nuclear Test Gives New High in Neutron Flux  

Science Journals Connector (OSTI)

Scientists have disclosed a major advance in the use of thermonuclear explosions to make transuranium elements. ...

1964-12-14T23:59:59.000Z

119

Epithermal Neutron Source for Neutron Resonance Spectroscopy (NRS) using High Intensity, Short Pulse Lasers  

SciTech Connect

A neutron source for neutron resonance spectroscopy (NRS) has been developed using high intensity, short pulse lasers. This measurement technique will allow for robust measurements of interior ion temperature of laser-shocked materials and provide insight into equation of state (EOS) measurements. The neutron generation technique uses protons accelerated by lasers off of Cu foils to create neutrons in LiF, through (p,n) reactions with {sup 7}Li and {sup 19}F. The distribution of the incident proton beam has been diagnosed using radiochromic film (RCF). This distribution is used as the input for a (p,n) neturon prediction code which is compared to experimentally measured neutron yields. From this calculation, a total fluence of 1.8 x 10{sup 9} neutrons is infered, which is shown to be a reasonable amount for NRS temperature measurement.

Higginson, D P; McNaney, J M; Swift, D C; Bartal, T; Hey, D S; Pape, S L; Mackinnon, A; Mariscal, D; Nakamura, H; Nakanii, N; Beg, F N

2010-04-22T23:59:59.000Z

120

Simulation of neutrons produced by high-energy muons underground  

Science Journals Connector (OSTI)

This article describes the Monte Carlo simulation used to interpret the measurement of the muon-induced neutron flux in the Boulby Underground Laboratory (North Yorkshire, UK), recently performed using a large scintillator veto deployed around the ZEPLIN-II WIMP detector. Version 8.2 of the GEANT4 toolkit was used after relevant benchmarking and validation of neutron production models. In the direct comparison between Monte Carlo and experimental data, we find that the simulation produces a 1.8 times higher neutron rate, which we interpret as over-production in lead by GEANT4. The dominance of this material in neutron production allows us to estimate the absolute neutron yield in lead as (1.31 ± 0.06)×10?3 neutrons/muon/(g/cm2) for a mean muon energy of 260 GeV. Simulated nuclear recoils due to muon-induced neutrons in the ZEPLIN-II target volume (?1-year exposure) showed that, although a small rate of events is expected from this source of background in the energy range of interest for dark matter searches, no event survives an anti-coincidence cut with the veto.

A. Lindote; H.M. Araújo; V.A. Kudryavtsev; M. Robinson

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Modeling high-energy cosmic ray induced terrestrial muon flux: A lookup table  

Science Journals Connector (OSTI)

On geological timescales, the Earth is likely to be exposed to an increased flux of high-energy cosmic rays (HECRs) from astrophysical sources such as nearby supernovae, gamma-ray bursts or by galactic shocks. Typical cosmic ray energies may be much higher than the ? 1 GeV flux which normally dominates. These high-energy particles strike the Earth's atmosphere initiating an extensive air shower. As the air shower propagates deeper, it ionizes the atmosphere by producing charged secondary particles. Secondary particles such as muons and thermal neutrons produced as a result of nuclear interactions are able to reach the ground, enhancing the radiation dose. Muons contribute 85% to the radiation dose from cosmic rays. This enhanced dose could be potentially harmful to the biosphere. This mechanism has been discussed extensively in literature but has never been quantified. Here, we have developed a lookup table that can be used to quantify this effect by modeling terrestrial muon flux from any arbitrary cosmic ray spectra with 10 GeV to 1 PeV primaries. This will enable us to compute the radiation dose on terrestrial planetary surfaces from a number of astrophysical sources.

Dimitra Atri; Adrian L. Melott

2011-01-01T23:59:59.000Z

122

STATUS OF HIGH FLUX ISOTOPE REACTOR IRRADIATION OF SILICON CARBIDE/SILICON CARBIDE JOINTS  

SciTech Connect

Development of silicon carbide (SiC) joints that retain adequate structural and functional properties in the anticipated service conditions is a critical milestone toward establishment of advanced SiC composite technology for the accident-tolerant light water reactor (LWR) fuels and core structures. Neutron irradiation is among the most critical factors that define the harsh service condition of LWR fuel during the normal operation. The overarching goal of the present joining and irradiation studies is to establish technologies for joining SiC-based materials for use as the LWR fuel cladding. The purpose of this work is to fabricate SiC joint specimens, characterize those joints in an unirradiated condition, and prepare rabbit capsules for neutron irradiation study on the fabricated specimens in the High Flux Isotope Reactor (HFIR). Torsional shear test specimens of chemically vapor-deposited SiC were prepared by seven different joining methods either at Oak Ridge National Laboratory or by industrial partners. The joint test specimens were characterized for shear strength and microstructures in an unirradiated condition. Rabbit irradiation capsules were designed and fabricated for neutron irradiation of these joint specimens at an LWR-relevant temperature. These rabbit capsules, already started irradiation in HFIR, are scheduled to complete irradiation to an LWR-relevant dose level in early 2015.

Katoh, Yutai [ORNL; Koyanagi, Takaaki [ORNL; Kiggans, Jim [ORNL; Cetiner, Nesrin [ORNL; McDuffee, Joel [ORNL

2014-09-01T23:59:59.000Z

123

Polarized neutron reflectometry in high magnetic fields  

SciTech Connect

A simple method is described to maintain the polarization of a neutron beam on its way through the large magnetic stray fields produced by a vertical field of a cryomagnet with a split-coil geometry. The two key issues are the proper shielding of the neutron spin flippers and an additional radial field component in order to guide the neutron spin through the region of the null point (i.e., point of reversal for the vertical field component). Calculations of the neutron's spin rotation as well as polarized neutron reflectometry experiments on an ErFe{sub 2}/DyFe{sub 2} multilayer show the perfect performance of the used setup. The recently commissioned cryomagnet M5 with a maximum vertical field of up to 7.2 T in asymmetric mode for polarized neutrons and 9 T in symmetric mode for unpolarized neutrons was used on the C5 spectrometer in reflectometry mode, at the NRU reactor in Chalk River, Canada.

Fritzsche, H. [National Research Council Canada, Canadian Neutron Beam Centre, Chalk River Laboratories, Chalk River, Ontario K0J 1J0 (Canada)

2005-11-15T23:59:59.000Z

124

Solid state neutron detector array  

DOE Patents (OSTI)

A neutron detector array is capable of measuring a wide range of neutron fluxes. The array includes multiple semiconductor neutron detectors. Each detector has a semiconductor active region that is resistant to radiation damage. In one embodiment, the array preferably has a relatively small size, making it possible to place the array in confined locations. The ability of the array to detect a wide range of neutron fluxes is highly advantageous for many applications such as detecting neutron flux during start up, ramp up and full power of nuclear reactors.

Seidel, John G. (Pittsburgh, PA); Ruddy, Frank H. (Monroeville, PA); Brandt, Charles D. (Mount Lebanon, PA); Dulloo, Abdul R. (Pittsburgh, PA); Lott, Randy G. (Pittsburgh, PA); Sirianni, Ernest (Monroeville, PA); Wilson, Randall O. (Greensburg, PA)

1999-01-01T23:59:59.000Z

125

Neutron-Proton and Neutron-Neutron Scattering at High Energies  

Science Journals Connector (OSTI)

The phase method and the Born approximation is used to calculate the cross sections of high energy neutrons scattered by protons and neutrons. Various exchange theories are considered for both, central and tensor forces of rectangular and Yukawa well shape.For the tensor case the phase method leads to general formulas for the differential and total cross sections in terms of real phase shifts. The reality of the phase shifts is a direct consequence of the use of the asymptotic form of the eigenfunctions of the tensor force Hamiltonian. The differential cross section in this case also contains the "amounts of admixture" which measure the coupling of states of different orbital angular momentum which have the same total angular momentum and the same parity. The real phase shifts and the amounts of admixture are derived from a variational principle. The total cross sections thus obtained are within a few percent of the exact values. The Born approximation is not satisfactory at 100 Mev.At this energy, tensor forces of a rectangular well shape with Rarita-Schwinger constants yield 0.2113, 0.1497, and 0.1271 barns for the n-p cross section, and 0.2566, 0.1381, and 0.0359 barns for the n-n cross section, in the neutral, charged, and symmetrical exchange theory, respectively. The observed n-p cross section at 90 Mev, 0.083±0.004 barns, agrees best with the theoretical value of ?0.080 barns at 100 Mev, derived from a tensor interaction potential of equal amounts of neutral and charged exchange. It is concluded, however, that a Yukawa tensor potential of the symmetrical exchange type can be in agreement with the experiments, if relativistic corrections of the n-p cross section at 100 Mev are negative and of the order of 5-10 percent. The differential cross section needs considerably larger corrections unless a different tensor force range is used.

F. Rohrlich and J. Eisenstein

1949-03-01T23:59:59.000Z

126

Multi-Group Transport Methods for High-Resolution Neutron Activation Analysis  

SciTech Connect

The accurate and efficient simulation of coupled neutron-photon problems is necessary for several important radiation detection applications. Examples include the detection of nuclear threats concealed in cargo containers and prompt gamma neutron activation analysis for nondestructive determination of elemental composition of unknown samples. In these applications, high-resolution gamma-ray spectrometers are used to measure the spectrum of the emitted photon flux, which consists of both continuum and characteristic gamma rays with discrete energies. Monte Carlo transport is the most commonly used simulation tool for this type of problem, but computational times for many problems can be prohibitively long. This work explores the use of multi-group deterministic methods for the simulation of coupled neutron-photon problems.

Burns, Kimberly A.; Smith, Leon E.; Gesh, Christopher J.; Shaver, Mark W.

2009-09-24T23:59:59.000Z

127

Facilities and Capabilities | Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

SHARE Facilities and Capabilities ORNL operates two of the world's most powerful neutron scattering user facilities: the High Flux Isotope Reactor and the Spallation...

128

High-flux solar photon processes: Opportunities for applications  

SciTech Connect

The overall goal of this study was to identify new high-flux solar photon (HFSP) processes that show promise of being feasible and in the national interest. Electric power generation and hazardous waste destruction were excluded from this study at sponsor request. Our overall conclusion is that there is promise for new applications of concentrated solar photons, especially in certain aspects of materials processing and premium materials synthesis. Evaluation of the full potential of these and other possible applications, including opportunities for commercialization, requires further research and testing. 100 refs.

Steinfeld, J.I.; Coy, S.L.; Herzog, H.; Shorter, J.A.; Schlamp, M.; Tester, J.W.; Peters, W.A. (Massachusetts Inst. of Tech., Cambridge, MA (United States))

1992-06-01T23:59:59.000Z

129

Neutron scattering studies and modeling of high mobility group 14 core nucleosome complex  

Science Journals Connector (OSTI)

Neutron scattering studies and modeling of high mobility...were studied by use of small-angle neutron scattering techniques. By varying the H2O...occurring in active nucleosomes. Neutron scattering studies and modeling of high mobility...

E C Uberbacher; J K Mardian; R M Rossi; D E Olins; G J Bunick

1982-01-01T23:59:59.000Z

130

High-temperature neutron diffraction study of deuterated brucite  

Science Journals Connector (OSTI)

To study the structural behavior of brucite at high temperature, we conducted in situ neutron diffraction experiments of a deuterated brucite powder sample, Mg(OD)2, in the temperature range 313–583 K. The sample...

Hongwu Xu; Yusheng Zhao; Donald D. Hickmott…

2013-11-01T23:59:59.000Z

131

Reactor physics input to the safety analysis report for the High Flux Isotope Reactor  

SciTech Connect

HFIR specific, few group neutron and coupled neutron-gamma libraries have been prepared. These are based on data from ENDF/B-V and beginning-of-life (BOL) conditions. The neutron library includes actinide data for curium target rods. Six critical experiments, collectively designated HFIR critical experiment 4, were analyzed. Calculated k-effective was 2% high at BOL-typical conditions but was 1.0 at end-of-life-typical conditions. The local power density distributions were calculated for each of the critical experiments. The axially averaged values at a given radius were frequently within experimental error. However at individual points, the calculated local power densities were significantly different from the experimentally derived values (several times greater than experimental uncertainty). A reassessment of the foil activation data with transport theory techniques seems desirable. Using the results of the critical experiments study, a model of current HFIR configuration was prepared. As with the critical experiments, BOL k-effective was high (3%). However, end-of-life k-effective was high (2%). The end-of-life concentrations of fission products were compared to those generated using the ORIGEN code. Agreement was generally good through differences in the inventories of some important nuclides, Xe and I, need to be understood. End-of-cycle curium target isotopics based on measured, discharged target rods were compared to calculated values and agreement was good. Axial flux plots at various irradiation positions were generated. Time-dependent power distributions based on two-dimensional calculations were provided.

Primm, R.T. III.

1992-03-01T23:59:59.000Z

132

Flux  

NLE Websites -- All DOE Office Websites (Extended Search)

5000 5000 6000 7000 8000 Wavelength (Angstroms) Flux (in arbitrary units) SN 1990N SN 1989B SN 1993O SN 1981B SN 1994D SN 1997ap Iron Peak Blends Ca II Si II & Co II Fe II & III Day -7 Day -5 Day -4 Day -2 ± 2 Day 0 Day +2 * -50 0 50 100 150 Observed days from peak Observed I magnitude 27 26 25 24 23 Observed R magnitude 27 26 25 24 Observed I magnitude 27 26 25 24 23 R band Ground-based I band HST I band (b) (c) (a) Pre-SN observation 3.5 4.0 4.5 5.0 5.5 log(cz) 14 16 18 20 22 24 26 effective m B 0.02 0.05 0.1 0.2 0.5 1.0 redshift z Hamuy et al (A.J. 1996) Supernova Cosmology Project 6 8 % 9 0 % 0.5 1.0 1.5 2.0 2.5 3.0 ! M Age < 9.6 Gyr (H = 50 km s -1 Mpc -1 ) No Big Bang 0.0 0.5 1.0 1.5 2.0 2.5 3.0 -3 -2 -1 0 1 2 3 -3 -2 -1 0 1 2 3 ! " z ~ 0 . 4 z = 0 . 8 3 6 8 % 9 0 % 0.5 1.0 1.5 2.0 2.5 3.0 ! M Age < 9.6 Gyr (H=50 km/s/Mpc)

133

Performance and safety parameters for the high flux isotope reactor  

SciTech Connect

A Monte Carlo depletion model for the High Flux Isotope Reactor (HFIR) Cycle 400 and its use in calculating parameters of relevance to the reactor performance and safety during the reactor cycle are presented in this paper. This depletion model was developed to serve as a reference for the design of a low-enriched uranium (LEU) fuel for an ongoing study to convert HFIR from high-enriched uranium (HEU) to LEU fuel; both HEU and LEU depletion models use the same methodology and ENDF/B-VII nuclear data as discussed in this paper. The calculated HFIR Cycle 400 parameters, which are compared with measurement data from critical experiments performed at HFIR, data included in the HFIR Safety Analysis Report (SAR), or data reported by previous calculations, provide a basis for verification or updating of the corresponding SAR data. (authors)

Ilas, G. [Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831-6172 (United States); Primm III, T. [Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831-6172 (United States); Primm Consulting, LLC, 945 Laurel Hill Road, Knoxville, TN 37923 (United States)

2012-07-01T23:59:59.000Z

134

Flux pinning and flux creep in neutron irradiated (Y,Gd)Ba sub 2 Cu sub 3 O sub x  

SciTech Connect

Powder samples of Y{sub 0.9}Gd{sub 0.1}Ba{sub 2}Cu{sub 3}O{sub x} were irradiated with mixed spectrum ({approximately}50% E<0.5eV, 50% E>0.5eV) neutrons with most interactions expected to occur at the Gd site. As a function of fluence the samples showed increased ({approximately}X3-X8) magnetically measured critical current densities J{sub c} at low fluences, falling off at the highest values. An analysis of magnetic relaxation data, which allows for a nonlinear pinning potential U vs J relationship, revealed substantial increases in U at constant J, indicating that the irradiation introduced more effective pinning centers than those originally present. 13 refs., 3 figs., 1 tab.

Willis, J.O. (Los Alamos Scientific Lab., NM (United States) Superconductivity Research Lab., Tokyo (Japan)); Sickafus, K.E.; Peterson, D.E. (Los Alamos National Lab., NM (United States))

1991-01-01T23:59:59.000Z

135

Fuel Grading Study on a Low-Enriched Uranium Fuel Design for the High Flux Isotope Reactor  

SciTech Connect

An engineering design study that would enable the conversion of the High Flux Isotope Reactor (HFIR) from high-enriched uranium to low-enriched uranium fuel is ongoing at Oak Ridge National Laboratory. The computational models used to search for a low-enriched uranium (LEU) fuel design that would meet the requirements for the conversion study, and the recent results obtained with these models during FY 2009, are documented and discussed in this report. Estimates of relevant reactor performance parameters for the LEU fuel core are presented and compared with the corresponding data for the currently operating high-enriched uranium fuel core. These studies indicate that the LEU fuel design would maintain the current performance of the HFIR with respect to the neutron flux to the central target region, reflector, and beam tube locations.

Ilas, Germina [ORNL; Primm, Trent [ORNL

2009-11-01T23:59:59.000Z

136

A high-flux BEC source for mobile atom interferometers  

E-Print Network (OSTI)

Quantum sensors based on coherent matter-waves are precise measurement devices whose ultimate accuracy is achieved with Bose-Einstein condensates (BEC) in extended free fall. This is ideally realized in microgravity environments such as drop towers, ballistic rockets and space platforms. However, the transition from lab-based BEC machines to robust and mobile sources with comparable performance is a technological challenge. Here we report on the realization of a miniaturized setup, generating a flux of $4 \\times 10^5$ quantum degenerate $^{87}$Rb atoms every 1.6 s. Ensembles of $1 \\times 10^5$ atoms can be produced at a 1 Hz rate. This is achieved by loading a cold atomic beam directly into a multi-layer atom chip that is designed for efficient transfer from laser-cooled to magnetically trapped clouds. The attained flux of degenerate atoms is on par with current lab-based experiments while offering significantly higher repetition rates. The compact and robust design allows for mobile operation in a variety of demanding environments and paves the way for portable high-precision quantum sensors.

Jan Rudolph; Waldemar Herr; Christoph Grzeschik; Tammo Sternke; Alexander Grote; Manuel Popp; Dennis Becker; Hauke Müntinga; Holger Ahlers; Achim Peters; Claus Lämmerzahl; Klaus Sengstock; Naceur Gaaloul; Wolfgang Ertmer; Ernst M. Rasel

2015-01-02T23:59:59.000Z

137

Observable Neutron-Anti-Neutron Oscillation, Baryogenesis and High Scale Seesaw  

E-Print Network (OSTI)

Seesaw mechanism has been a dominant paradigm in the discussion of neutrino masses. I discuss how this idea can be tested via a baryon number violating process such as $N-\\bar{N}$ oscillation. Since the expected seesaw scale is high and the $N-\\bar{N}$ amplitude goes like $M^{-5}_{R}$, one might think that this process is not observable in realistic seesaw models for neutrino masses. In this talk I show that in supersymmetric models, the above conclusion is circumvented leading to an enhanced and observable rate for $N-\\bar{N}$ oscillation. I also discuss a new mechanism for baryogenesis in generic models for neutron-anti-neutron oscillation and show how the requirement of adequate baryogenesis can put an upper limit on the neutron-anti-neutron oscillation time.

R. N. Mohapatra

2006-05-26T23:59:59.000Z

138

High resolution neutron crystallographic studies of the hydration of coenzyme cob(II)alamin  

SciTech Connect

The hydration of coenzyme cob(II)alamin has been studied using high resolution monochromatic neutron crystallographic data collected at room temperature to a resolution of surrounded by flexible side chains with terminal functional groups may be significant for 0.92 on the original diffractometer D19 with a prototype 4o x 64o detector at the high-flux reactor neutron source run by the Institute Laue Langevin. The resulting structure provides H bonding parameters for the hydration of biomacromolecules to unprecedented accuracy. These experimental parameters will be used to define more accurate force-fields for biomacromolecular structure refinement. The presence of a hydrophobic bowl motif efficient scavenging of ligands. The feasibility of extending the resolution of this structure to ultra high resolution was investigated by collecting time-of-flight neutron crystallographic data on diffractometer TOPAZ with a prototype array of 14 modular 21o x 21o detectors at the Spallation Neutron Source run by Oak Ridge National Laboratory.

Jogl, Gerwald [Brown University; Wang, Xiaoping [ORNL; Mason, Sax [Institut Laue-Langevin (ILL); Kovalevsky, Andrey [Los Alamos National Laboratory (LANL); Mustyakimov, Marat [Los Alamos National Laboratory (LANL); Fisher, Zoe [Los Alamos National Laboratory (LANL); Hoffmann, Christina [ORNL; Kratky, Christoph [Institute of Biosciences, University of Graz; Langan, Paul [ORNL

2011-01-01T23:59:59.000Z

139

Low-Enriched Uranium Fuel Design with Two-Dimensional Grading for the High Flux Isotope Reactor  

SciTech Connect

An engineering design study of the conversion of the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel is ongoing at Oak Ridge National Laboratory. The computational models developed during fiscal year 2010 to search for an LEU fuel design that would meet the requirements for the conversion and the results obtained with these models are documented and discussed in this report. Estimates of relevant reactor performance parameters for the LEU fuel core are presented and compared with the corresponding data for the currently operating HEU fuel core. The results obtained indicate that the LEU fuel design would maintain the current performance of the HFIR with respect to the neutron flux to the central target region, reflector, and beam tube locations under the assumption that the operating power for the reactor fueled with LEU can be increased from the current value of 85 MW to 100 MW.

Ilas, Germina [ORNL; Primm, Trent [ORNL

2011-05-01T23:59:59.000Z

140

Fast Neutron - Mirror Neutron Oscillation and Ultra High Energy Cosmic Rays  

E-Print Network (OSTI)

If there exists the mirror world, a parallel hidden sector of particles with exactly the same microphysics as that of the observable particles, then the primordial nucleosynthesis constraints require that the temperature of the cosmic background of mirror relic photons should be smaller than that of the ordinary relic photons, T'/T neutron - mirror neutron oscillation in vacuum, with an oscillation time $\\tau \\sim 1$ s, much smaller than the neutron lifetime. We show that this could provide a very efficient mechanism for transporting ultra high energy protons at large cosmological distances. The mechanism operates as follows: a super-GZK energy proton scatters a relic photon producing a neutron that oscillates into a mirror neutron which then decays into a mirror proton. The latter undergoes a symmetric process, scattering a mirror relic photon and producing back an ordinary nucleon, but only after traveling a distance $(T/T')^{3}$ times larger than ordinary protons. This may relax or completely remove the GZK-cutoff in the cosmic ray spectrum and also explain the correlation between the observed ultra high energy protons and far distant sources as are the BL Lacs.

Zurab Berezhiani; Luis Bento

2006-02-24T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

HFIR In-Vessel Irradiation Facilities | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

the permanent beryllium reflector. Please refer to the accompanying graph showing the neutron flux values for these regions. Radio neutron flux graph Neutron flux distributions at...

142

PRACTICAL NEUTRON DOSIMETRY AT HIGH ENERGIES  

E-Print Network (OSTI)

of High-Energy Accelerators, New York, April, 1957. USAECShielding of High-Energy Accelerators, New York, April 1957.Shielding of High-Energy Accelerators, New York, April 1957.

McCaslin, J.B.

2010-01-01T23:59:59.000Z

143

High Flux Isotope Reactor system RELAP5 input model  

SciTech Connect

A thermal-hydraulic computational model of the High Flux Isotope Reactor (HFIR) has been developed using the RELAP5 program. The purpose of the model is to provide a state-of-the art thermal-hydraulic simulation tool for analyzing selected hypothetical accident scenarios for a revised HFIR Safety Analysis Report (SAR). The model includes (1) a detailed representation of the reactor core and other vessel components, (2) three heat exchanger/pump cells, (3) pressurizing pumps and letdown valves, and (4) secondary coolant system (with less detail than the primary system). Data from HFIR operation, component tests, tests in facility mockups and the HFIR, HFIR specific experiments, and other pertinent experiments performed independent of HFIR were used to construct the model and validate it to the extent permitted by the data. The detailed version of the model has been used to simulate loss-of-coolant accidents (LOCAs), while the abbreviated version has been developed for the operational transients that allow use of a less detailed nodalization. Analysis of station blackout with core long-term decay heat removal via natural convection has been performed using the core and vessel portions of the detailed model.

Morris, D.G.; Wendel, M.W.

1993-01-01T23:59:59.000Z

144

Fabrication of control rods for the High Flux Isotope Reactor  

SciTech Connect

The High Flux Isotope Reactor (HFIR) is a research-type nuclear reactor that was designed and built in the early 1960s and has been in continuous operation since its initial criticality in 1965. Under current plans, the HFIR is expected to continue in operation until 2035. This report updates ORNL/TM-9365, Fabrication Procedure for HFIR Control Plates, which was mainly prepared in the early 1970's but was not issued until 1984, and reflects process changes, lessons learned in the latest control rod fabrication campaign, and suggested process improvements to be considered in future campaigns. Most of the personnel involved with the initial development of the processes and in part campaigns have retired or will retire soon. Because their unlikely availability in future campaigns, emphasis has been placed on providing some explanation of why the processes were selected and some discussions about the importance of controlling critical process parameters. Contained in this report is a description of the function of control rods in the reactor, the brief history of the development of control rod fabrication processes, and a description of procedures used in the fabrication of control rods. A listing of the controlled documents and procedures used in the last fabrication campaigns is referenced in Appendix A.

Sease, J.D.

1998-03-01T23:59:59.000Z

145

Neutron calibration facilities  

Science Journals Connector (OSTI)

......shut down. A recent development for a thermal neutron calibration field is a neutron guide used at the research reactor GKSS Geesthacht(35). The result is a high-intensity thermal beam providing a flux of up to 106 s1 with a field size of about 2.5 2......

H. Schuhmacher

2004-08-01T23:59:59.000Z

146

Investigating the influence of a Forbush decrease on the detected flux of high-energy muons  

Science Journals Connector (OSTI)

The effect of Forbush decreases was studied for a flux of high-energy muons with a threshold of 220 GeV detected...

M. G. Kostyuk; V. B. Petkov; A. V. Belov…

2011-06-01T23:59:59.000Z

147

Seismic, high wind, tornado, and probabilistic risk assessments of the High Flux Isotope Reactor  

SciTech Connect

Natural phenomena analyses were performed on the High Flux Isotope Reactor (HFIR) Deterministic and probabilistic evaluations were made to determine the risks resulting from earthquakes, high winds, and tornadoes. Analytic methods in conjunction with field evaluations and an earthquake experience data base evaluation methods were used to provide more realistic results in a shorter amount of time. Plant modifications completed in preparation for HFIR restart and potential future enhancements are discussed. 5 figs.

Harris, S.P.; Stover, R.L.; Hashimoto, P.S.; Dizon, J.O. (EQE, Inc., San Francisco, CA (USA); Oak Ridge National Lab., TN (USA); EQE, Inc., San Francisco, CA (USA))

1989-01-01T23:59:59.000Z

148

High energy neutron Computed Tomography developed  

E-Print Network (OSTI)

be observed behind high-density materials, such as depleted uranium or tungsten. Comparison of the high (bottom half) and foam (center teeth) phantom could be viewed through 76 mm of depleted uranium. Some ~ 3

149

External event Probabilistic Risk Assessment for the High Flux Isotope Reactor (HFIR)  

SciTech Connect

The High Flux Isotope Reactor (HFIR) is a high performance isotope production and research reactor which has been in operation at Oak Ridge National Laboratory (ORNL) since 1965. In late 1986 the reactor was shut down as a result of discovery of unexpected neutron embrittlement of the reactor vessel. In January of 1988 a level 1 Probabilistic Risk Assessment (PRA) (excluding external events) was published as part of the response to the many reviews that followed the shutdown and for use by ORNL to prioritize action items intended to upgrade the safety of the reactor. A conservative estimate of the core damage frequency initiated by internal events for HFIR was 3.11 {times} 10{sup {minus}4}. In June 1989 a draft external events initiated PRA was published. The dominant contributions from external events came from seismic, wind, and fires. The overall external event contribution to core damage frequency is about 50% of the internal event initiated contribution and is dominated by seismic events.

Flanagan, G.F.; Johnson, D.H.; Buttemer, D.; Perla, H.F.; Chien, S.H. (Oak Ridge National Lab., TN (USA))

1989-01-01T23:59:59.000Z

150

Electron Scattering From High-Momentum Neutrons in Deuterium  

E-Print Network (OSTI)

We report results from an experiment measuring the semi-inclusive reaction $d(e,e'p_s)$ where the proton $p_s$ is moving at a large angle relative to the momentum transfer. If we assume that the proton was a spectator to the reaction taking place on the neutron in deuterium, the initial state of that neutron can be inferred. This method, known as spectator tagging, can be used to study electron scattering from high-momentum (off-shell) neutrons in deuterium. The data were taken with a 5.765 GeV electron beam on a deuterium target in Jefferson Laboratory's Hall B, using the CLAS detector. A reduced cross section was extracted for different values of final-state missing mass $W^{*}$, backward proton momentum $\\vec{p}_{s}$ and momentum transfer $Q^{2}$. The data are compared to a simple PWIA spectator model. A strong enhancement in the data observed at transverse kinematics is not reproduced by the PWIA model. This enhancement can likely be associated with the contribution of final state interactions (FSI) that were not incorporated into the model. A ``bound neutron structure function'' $F_{2n}^{eff}$ was extracted as a function of $W^{*}$ and the scaling variable $x^{*}$ at extreme backward kinematics, where effects of FSI appear to be smaller. For $p_{s}>400$ MeV/c, where the neutron is far off-shell, the model overestimates the value of $F_{2n}^{eff}$ in the region of $x^{*}$ between 0.25 and 0.6. A modification of the bound neutron structure function is one of possible effects that can cause the observed deviation.

A. V. Klimenko; S. E. Kuhn; for the CLAS collaboration

2005-10-11T23:59:59.000Z

151

Countercurrent flow limited (CCFL) heat flux in the high flux isotope reactor (HFIR) fuel element  

SciTech Connect

The countercurrent flow (CCF) performance in the fuel element region of the HFIR is examined experimentally and theoretically. The fuel element consists of two concentric annuli filled with aluminum clad fuel plates of 1.27 mm thickness separated by 1.27 mm flow channels. The plates are curved as they go radially outward to accomplish constant flow channel width and constant metal-to-coolant ratio. A full-scale HFIR fuel element mock-up is studied in an adiabatic air-water CCF experiment. A review of CCF models for narrow channels is presented along with the treatment of CCFs in system of parallel channels. The experimental results are related to the existing models and a mechanistic model for the annular'' CCF in a narrow channel is developed that captures the data trends well. The results of the experiment are used to calculate the CCFL heat flux of the HFIR fuel assembly. It was determined that the HFIR fuel assembly can reject 0.62 Mw of thermal power in the CCFL situation. 31 refs., 17 figs.

Ruggles, A.E.

1990-10-12T23:59:59.000Z

152

High-performance beam-plasma neutron sources for fusion materials development  

SciTech Connect

The design and performance of a relatively low-cost, plasma-based, 14-MeV deuterium-tritium neutron source for accelerated end-of-life testing of fusion reactor materials are described. An intense flux (up to 5 [times] 10[sup 18] n/m[sup 2][center dot]s) of 14-MeV neutrons is produced in a fully ionized high-density tritium target (n[sub e] [approx] 3 [times] 10[sup 21] m[sup [minus]3]) by injecting a current of 150-keV deuterium atoms. The tritium plasma target and the energetic D[sup +] density produced by D[sup 0] injection are confined in a [<=] 0.16-m-diam column by a linear magnet set, which provides magnetic fields up to 12 T. Energy deposited by transverse injection of neutral beams at the midpoint of the column is transported along the plasma column to the end regions. Three variations of the neutron source design are discussed, differing in the method of control of the energy transport. Emphasis is on the design in which the target plasma density is maintained in a region where electron thermal conduction along the column is the controlling energy-loss process.

Coensgen, F.H.; Casper, T.A.; Correll, D.L.; Damm, C.C.; Futch, A.H.; Logan, B.G.; Molvik, A.W. (Lawrence Livermore National Lab., CA (United States))

1990-10-01T23:59:59.000Z

153

Discontinuous representation of the magnitude of the vector flux in monoenergetic neutron transport theory  

E-Print Network (OSTI)

, the functions are the first n Legendre polynomials such that in the n order approximation T(x, Q) e (x)P (cosQ) + el(x)P1(cosQ) + 0 0 (1 ~ 1) e2 (x)P2(cosQ) + . ~ . + e (x)P (cosQ). The Boltsmann equation for V(x, Q), the magnitude of the vector flux..., is thus reduced to a simpler system of n differential equations in the spatial coordinate only. For the above P n approximation a system of n ordinary differential equations involving the e. (x) with i=0, 1, 2, . . . , n is obtained. i If the initial...

Poulsen, Niel Bowman

2012-06-07T23:59:59.000Z

154

High efficiency neutron sensitive amorphous silicon pixel detectors  

SciTech Connect

A multi-layer a-Si:H based thermal neutron detector was designed, fabricated and simulated by Monte Carlo method. The detector consists of two PECVD deposited a-Si:H pin detectors interfaced with coated layers of Gd, as a thermal neutron converter. Simulation results indicate that a detector consisting of 2 Gd films with thicknesses of 2 and 4 {mu}m, sandwiched properly with two layers of sufficiently thick ({approximately}30{mu}m) amorphous silicon diodes, has the optimum parameters. The detectors have an intrinsic efficiency of about 42% at a threshold setting of 7000 electrons, with an expected average signal size of {approximately}12000 electrons which is well above the noise. This efficiency will be further increased to nearly 63%, if we use Gd with 50% enrichment in {sup 157}Gd. We can fabricate position sensitive detectors with spatial resolution of 300 {mu}m with gamma sensitivity of {approximately}1 {times} 10{sup {minus}5}. These detectors are highly radiation resistant and are good candidates for use in various application, where high efficiency, high resolution, gamma insensitive position sensitive neutron detectors are needed.

Mireshghi, A.; Cho, G.; Drewery, J.S.; Hong, W.S.; Jing, T.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V.

1993-11-01T23:59:59.000Z

155

A high-flux BEC source for mobile atom interferometers  

E-Print Network (OSTI)

Quantum sensors based on coherent matter-waves are precise measurement devices whose ultimate accuracy is achieved with Bose-Einstein condensates (BEC) in extended free fall. This is ideally realized in microgravity environments such as drop towers, ballistic rockets and space platforms. However, the transition from lab-based BEC machines to robust and mobile sources with comparable performance is a technological challenge. Here we report on the realization of a miniaturized setup, generating a flux of $4 \\times 10^5$ quantum degenerate $^{87}$Rb atoms every 1.6 s. Ensembles of $1 \\times 10^5$ atoms can be produced at a 1 Hz rate. This is achieved by loading a cold atomic beam directly into a multi-layer atom chip that is designed for efficient transfer from laser-cooled to magnetically trapped clouds. The attained flux of degenerate atoms is on par with current lab-based experiments while offering significantly higher repetition rates. The compact and robust design allows for mobile operation in a variety of...

Rudolph, Jan; Grzeschik, Christoph; Sternke, Tammo; Grote, Alexander; Popp, Manuel; Becker, Dennis; Müntinga, Hauke; Ahlers, Holger; Peters, Achim; Lämmerzahl, Claus; Sengstock, Klaus; Gaaloul, Naceur; Ertmer, Wolfgang; Rasel, Ernst M

2015-01-01T23:59:59.000Z

156

A semi Monte Carlo calculation of the flux of high-energy muons in air showers  

Science Journals Connector (OSTI)

A semi Monte Carlo method has been used to calculate the flux of muons of energy ?180 GeV associated with air showers at ... of nucleon and pion interactions at ultra-high energies. Various aspects of these muons

Siddheshwar Lal

1967-03-21T23:59:59.000Z

157

Design and optimization of a high thermal flux research reactor via Kriging-based algorithm  

E-Print Network (OSTI)

In response to increasing demands for the services of research reactors, a 5 MW LEU-fueled research reactor core is developed and optimized to provide high thermal flux within specified limits upon thermal hydraulic ...

Kempf, Stephanie Anne

2011-01-01T23:59:59.000Z

158

Cation disorder in high dose neutron irradiated spinel  

SciTech Connect

The crystal structures of MgAl{sub 2}O{sub 4} spinel single crystals irradiated to high neutron fluences (>5{center_dot}10{sup 26} n/m{sup 2} (E{sub n}>0.1 MeV)), were examined by neutron diffraction. Crystal structure refinement of the highest dose sample indicated that the average scattering strength of the tetrahedral crystal sites decreased by {approximately}20% while increasing by {approximately}8% on octahedral sites. Since the neutron scattering length for Mg is considerably larger than for Al, this result is consistent with site exchange between Mg{sup 2+} ions on tetrahedral sites and Al{sup 3+} ions on octahedral sites. Least squares refinements also indicated that in all irradiated samples, at least 35% of Mg{sup 2+} and Al{sup 3+} ions in the crystal experienced disordering replacements. This retained dpa on the cation sublattices is the largest retained damage ever measured in an irradiated spinel material.

Sickafus, K.E.; Larson, A.C.; Yu, N.; Nastasi, M. [Los Alamos National Lab., NM (United States); Hollenberg, G.W.; Garner, F.A. [Pacific Northwest Lab., Richland, WA (United States); Bradt, R.C. [Univ. of Nevada, Reno, NV (United States)

1994-06-01T23:59:59.000Z

159

Cation disorder in high-dose, neutron-irradiated spinel  

SciTech Connect

The objective of this effort is to determine whether MgAl{sub 2}O{sub 4} spinel is a suitable ceramic for fusion applications. Here, the crystal structures of MgAl{sub 2}O{sub 4} spinel single crystals irradiated to high neutron fluences [>5{center_dot}10{sup 26} n/m{sup 2} (E{sub n} > 0.1 MeV)] were examined by neutron diffraction. Crystal structure refinement of the highest dose sample indicated that the average scattering strength of the tetrahedral crystal sites decreased by {approximately} 20% while increasing by {approximately} 8% on octahedral sites. Since the neutron scattering length for Mg is considerably larger than for Al, this results is consistent with site exchange between Mg{sup 2+} ions on tetrahedral sites and Al{sup 3+} ions on octahedral sites. Least-squares refinements also indicated that, in all irradiated samples, at least 35% of Mg{sup 2+} and Al{sup 3+} ions in the crystal experienced disordering replacements. This retained dpa on the cation sublattices is the largest retained damage ever measured in an irradiated spinel material.

Sickafus, K.E.; Larson, A.C.; Yu, N.; Nastasi, M. [Los Alamos National Lab., NM (United States); Hollenberg, G.W.; Garner, F.A. [Pacific Northwest Lab., Richland, WA (United States); Bradt, R.C. [Univ. of Nevada, Reno, NV (United States)

1994-08-01T23:59:59.000Z

160

Project Profile: High-Flux Microchannel Solar Receiver | Department...  

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

of a rectangle shape. The research team seeks to reduce the size, weight, and thermal loss from high-temperature solar receivers by applying microchannel heat-transfer...

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Structural and dynamical studies of superacids and superacidic solutions using neutron and high energy X-ray scattering.  

E-Print Network (OSTI)

?? The diffusive motions of the Brønsted superacid, hydrogen fluoride, have been studied using quasielastic neutron scattering. Neutron and high energy X-ray diffraction measurements on… (more)

Molaison, Jamie John

2006-01-01T23:59:59.000Z

162

Neutron and X-ray experiments at high temperature P. Aldebert (*)  

E-Print Network (OSTI)

649 Neutron and X-ray experiments at high temperature P. Aldebert (*) LA 302, E.N.S.C.P., 11, rue récemment celle des neutrons sont devenues des sondes puissantes propres à fournir des infor- mations'échantillon avec son environnement, en fait l'atmosphère ambiante et le support de l'échantillon. Les neutrons

Boyer, Edmond

163

High temperature furnaces for small and large angle neutron scattering of disordered materials  

E-Print Network (OSTI)

725 High temperature furnaces for small and large angle neutron scattering of disordered materials and small angle neutron scattering (SANS) experiments respectively. They are vacuum furnaces with a thin maintained in a tantalum box. In a neutron beam, the furnaces produce a very low scattering level (without

Boyer, Edmond

164

Systematic Uncertainties in the Spectroscopic Measurements of Neutron-Star Masses and Radii from Thermonuclear X-ray Bursts. III. Absolute Flux Calibration  

E-Print Network (OSTI)

Many techniques for measuring neutron star radii rely on absolute flux measurements in the X-rays. As a result, one of the fundamental uncertainties in these spectroscopic measurements arises from the absolute flux calibrations of the detectors being used. Using the stable X-ray burster, GS 1826-238, and its simultaneous observations by Chandra HETG/ACIS-S and RXTE/PCA as well as by XMM-Newton EPIC-pn and RXTE/PCA, we quantify the degree of uncertainty in the flux calibration by assessing the differences between the measured fluxes during bursts. We find that the RXTE/PCA and the Chandra gratings measurements agree with each other within their formal uncertainties, increasing our confidence in these flux measurements. In contrast, XMM-Newton EPIC-pn measures 14.0$\\pm$0.3% less flux than the RXTE/PCA. This is consistent with the previously reported discrepancy with the flux measurements of EPIC-pn, compared to EPIC-MOS1, MOS2 and ACIS-S detectors. We also address the calibration uncertainty in the RXTE/PCA int...

Guver, Tolga; Marshall, Herman; Psaltis, Dimitrios; Guainazzi, Matteo; Diaz-Trigo, Maria

2015-01-01T23:59:59.000Z

165

Oxidation and Volatilization from Tungsten Brush High Heat Flux Armor During High Temperature Steam Exposure  

SciTech Connect

Tungsten brush accommodates thermal stresses and high heat flux in fusion reactor components such as plasma facing surfaces or armor. However, inherently higher surface areas are introduced with the brush design. We have tested a specific design of tungsten brush in steam between 500 and 1100°C. Hydrogen generation and tungsten volatilization rates were determined to address fusion safety issues. The brush prepared from 3.2-mm diameter welding rods had a packing density of 85 percent. We found that both hydrogen generation and tungsten volatilization from brush, fixtured to represent a unit within a larger component, were less than projections based upon the total integrated surface area (TSA). Steam access and the escape of hydrogen and volatile oxide from void spaces within the brush are restricted compared to specimens with more direct diffusion pathways to the test environment. Hydrogen generation rates from restrained specimens based on normal surface area (NSA) remain about five times higher than rates based on total surface areas from specimens with direct steam access. Volatilization rates from restrained specimens based upon normal surface area (NSA) were only 50 percent higher than our historic cumulative maximum flux plot (CMFP) for tungsten. This study has shown that hydrogen generation and tungsten volatilization from brush do not scale according to predictions with previously determined rates, but in fact, with higher packing density could approach those from flat surfaces.

Smolik, Galen Richard; Pawelko, Robert James; Anderl, Robert Andrew; Petti, David Andrew

2000-05-01T23:59:59.000Z

166

Workplace characterisation in mixed neutron-gamma fields, specific requirements and available methods at high-energy accelerators  

Science Journals Connector (OSTI)

......High-energy neutrons are converted by a depleted uranium shell producing fission neutrons...c1 per nucleon lead ion beams. Health Phys. (1998) 75:619-629...multisphere neutron spectrometer data. Health Phys. (1999) 77:579-583......

Marco Silari

2007-04-01T23:59:59.000Z

167

National High Magnetic Field Laboratory - Flux: Volume 3, Issue...  

NLE Websites -- All DOE Office Websites (Extended Search)

not Stephanie Law, who was practially an old-timer when she arrived at the Mag Lab. gauss lines Pregnancy to pacemakers: safety around high magnetic fields First things first......

168

Growth of high-temperature superconductor crystals from flux  

Science Journals Connector (OSTI)

Crystallization of high-temperature superconductors was studied in La-Sr-Cu-O,...2Cu3O6.5+x were obtained by spontaneous crystallization from homogeneous nonstoichiometric melts enriched in bariu...

L N Demianets; A B Bykov; O K Melnikov; S M Stishov

1991-04-01T23:59:59.000Z

169

Small break LOCA analysis of the ONRL high flux isotope reactor  

SciTech Connect

A digital simulation program, HFIRSYS, was developed using MMS to analyze small break loss of coolant events in the ORNL High Flux Isotope Reactor. The code evaluates the response of the primary reactor system including automatic controls actions resulting from breaks in auxiliary piping connected to the primary. The primary output of the code is the margin to the onset of nucleate boiling expressed as a ratio of heat flux which would cause boiling to the current hot channel heat flux. A description of the model, validation results and a sample transient are presented.

Wilson, T.L. Jr.; Cook, D.H.; Sozer, A.

1988-01-01T23:59:59.000Z

170

Instrumentation development for neutron scattering at high pressure   

E-Print Network (OSTI)

Neutron scattering at extremes of pressure is a powerful tool for studying the response of structural and magnetic properties of materials on microscopic level to applied stresses. However, experimental neutron studies ...

Fang, Junwei

2012-11-29T23:59:59.000Z

171

SHARP Neutronics Expanded | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

SHARP Neutronics Expanded SHARP Neutronics Expanded SHARP Neutronics Expanded January 29, 2013 - 1:28pm Addthis Fully heterogeneous predictions of thermal neutron flux in a hypothetical metal-oxide-fueled PWR Fully heterogeneous predictions of thermal neutron flux in a hypothetical metal-oxide-fueled PWR SHARP neutronics Module Development The SHARP neutronics module, PROTEUS, includes neutron and gamma transport solvers and cross-section processing tools as well as the capability for depletion and fuel cycle analysis. The existing high-fidelity solver package was extended to be independent of reactor technology and demonstrated with 2-D MOC and Sn method simulations of LWR core configurations. Efforts to support verification and validation of the DeCART code, used as one reference solution method by the SHARP code

172

Neutron Halo Isomers in Stable Nuclei and their Possible Application for the Production of Low Energy, Pulsed, Polarized Neutron Beams of High Intensity and High Brilliance  

E-Print Network (OSTI)

We propose to search for neutron halo isomers populated via $\\gamma$-capture in stable nuclei with mass numbers of about A=140-180 or A=40-60, where the $4s_{1/2}$ or $3s_{1/2}$ neutron shell model state reaches zero binding energy. These halo nuclei can be produced for the first time with new $\\gamma$-beams of high intensity and small band width ($\\le$ 0.1%) achievable via Compton back-scattering off brilliant electron beams thus offering a promising perspective to selectively populate these isomers with small separation energies of 1 eV to a few keV. Similar to single-neutron halo states for very light, extremely neutron-rich, radioactive nuclei \\cite{hansen95,tanihata96,aumann00}, the low neutron separation energy and short-range nuclear force allows the neutron to tunnel far out into free space much beyond the nuclear core radius. This results in prolonged half lives of the isomers for the $\\gamma$-decay back to the ground state in the 100 ps-$\\mu$s range. Similar to the treatment of photodisintegration of the deuteron, the neutron release from the neutron halo isomer via a second, low-energy, intense photon beam has a known much larger cross section with a typical energy threshold behavior. In the second step, the neutrons can be released as a low-energy, pulsed, polarized neutron beam of high intensity and high brilliance, possibly being much superior to presently existing beams from reactors or spallation neutron sources.

D. Habs; M. Gross; P. G. Thirolf; P. Böni

2010-09-30T23:59:59.000Z

173

Possible explanation for the low flux of high energy astrophysical muon neutrinos  

SciTech Connect

I consider the possibility that some exotic neutrino property is responsible for reducing the muon neutrino flux at high energies from distant sources; specifically, (i) neutrino decay and (ii) neutrinos being pseudo-Dirac particles. This would provide a mechanism for the lack of high energy muon events in the Icecube detector.

Pakvasa, Sandip [Department of Physics and Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)

2013-05-23T23:59:59.000Z

174

Density of Gadolinium Nitrate Solutions for the High Flux Isotope Reactor  

SciTech Connect

In late 1992, the High Flux Isotope Reactor (HFIR) was planning to switch the solution contained in the poison injection tank from cadmium nitrate to gadolinium nitrate. The poison injection system is an emergency system used to shut down the reactor by adding a neutron poison to the cooling water. This system must be able to supply a minimum of 69 pounds of gadolinium to the reactor coolant system in order to guarantee that the reactor would become subcritical. A graph of the density of gadolinium nitrate solutions over a concentration range of 5 to 30 wt% and a temperature range of 15 to 40{sup o}C was prepared. Routine density measurements of the solution in the poison injection tank are made by HFIR personnel, and an adaptation of the original graph is used to determine the gadolinium nitrate concentration. In late 2008, HFIR personnel decided that the heat tracing that was present on the piping for the poison injection system could be removed without any danger of freezing the solution; however, the gadolinium nitrate solution might get as cold as 5{sup o}C. This was outside the range of the current density-concentration correlation, so the range needed to be expanded. This report supplies a new density-concentration correlation that covers the extended temperature range. The correlation is given in new units, which greatly simplifies the calculation that is required to determine the pounds of gadolinium in the tank solution. The procedure for calculating the amount of gadolinium in the HFIR poison injection system is as follows: (1) Calculate the usable volume in the system; (2) Measure the density of the solution; (3) Calculate the gadolinium concentration using the following equation: Gd(lb/ft{sup 3}) = measured density (g/mL) x 34.681 - 34.785; (4) Calculate the amount of gadolinium in the system using the following equation: Amount of Gd(lb) = Gd concentration (lb/ft{sup 3}) x usable volume (ft{sup 3}). The equation in step 3 is exact for a temperature of 5{sup o}C, and overestimates the gadolinium concentration at all higher temperatures. This guarantees that the calculation is conservative, in that the actual concentration will be at least as high as that calculated. If an additional safety factor is desired, it is recommended that an administrative control limit be set that is higher than the required minimum amount of gadolinium.

Taylor, Paul Allen [ORNL; Lee, Denise L [ORNL

2009-05-01T23:59:59.000Z

175

Design Study for a Low-enriched Uranium Core for the High Flux Isotope Reactor, Annual Report for FY 2007  

SciTech Connect

This report documents progress made during fiscal year 2007 in studies of converting the High Flux Isotope Reactor (HFIR) from highly enriched uranium (HEU) fuel to low enriched uranium fuel (LEU). Conversion from HEU to LEU will require a change in fuel form from uranium oxide to a uranium-molybdenum alloy. A high volume fraction U/Mo-in-Al fuel could attain the same neutron flux performance as with the current, HEU fuel but materials considerations appear to preclude production and irradiation of such a fuel. A diffusion barrier would be required if Al is to be retained as the interstitial medium and the additional volume required for this barrier would degrade performance. Attaining the high volume fraction (55 wt. %) of U/Mo assumed in the computational study while maintaining the current fuel plate acceptance level at the fuel manufacturer is unlikely, i.e. no increase in the percentage of plates rejected for non-compliance with the fuel specification. Substitution of a zirconium alloy for Al would significantly increase the weight of the fuel element, the cost of the fuel element, and introduce an as-yet untried manufacturing process. A monolithic U-10Mo foil is the choice of LEU fuel for HFIR. Preliminary calculations indicate that with a modest increase in reactor power, the flux performance of the reactor can be maintained at the current level. A linearly-graded, radial fuel thickness profile is preferred to the arched profile currently used in HEU fuel because the LEU fuel media is a metal alloy foil rather than a powder. Developments in analysis capability and nuclear data processing techniques are underway with the goal of verifying the preliminary calculations of LEU flux performance. A conceptual study of the operational cost of an LEU fuel fabrication facility yielded the conclusion that the annual fuel cost to the HFIR would increase significantly from the current, HEU fuel cycle. Though manufacturing can be accomplished with existing technology, several engineering proof-of-principle tests would be required. The RERTR program is currently conducting a series of generic fuel qualification tests at the Advanced Test Reactor. A review of these tests and a review of the safety basis for the current, HEU fuel cycle led to the identification of a set of HFIR-specific fuel qualification tests. Much additional study is required to formulate a HFIR-specific fuel qualification plan from this set. However, one such test - creating a graded fuel profile across a flat foil - has been initiated with promising results.

Primm, Trent [ORNL; Ellis, Ronald James [ORNL; Gehin, Jess C [ORNL; Ilas, Germina [ORNL; Miller, James Henry [ORNL; Sease, John D [ORNL

2007-11-01T23:59:59.000Z

176

High heat flux testing capabilities at Sandia National Laboratories - New Mexico  

SciTech Connect

High heat flux testing for the United States fusion power program is the primary mission of the Plasma Materials Test Facility (PMTF) located at Sandia National Laboratories - New Mexico. This facility, which is owned by the United States Department of Energy, has been in operation for over 17 years and has provided much of the high heat flux data used in the design and evaluation of plasma facing components for many of the world`s magnetic fusion, tokamak experiments. In addition to domestic tokamaks such as Tokamak Fusion Test Reactor (TFTR) at Princeton and the DIII-D tokamak at General Atomics, components for international experiments like TEXTOR, Tore-Supra, and JET also have been tested at the PMTF. High heat flux testing spans a wide spectrum including thermal shock tests on passively cooled materials, thermal response and thermal fatigue tests on actively cooled components, critical heat flux-burnout tests, braze reliability tests and safety related tests. The objective of this article is to provide a brief overview of the high heat flux testing capabilities at the PMTF and describe a few of the experiments performed over the last year.

Youchison, D.L.; McDonald, J.M.; Wold, L.S.

1994-12-31T23:59:59.000Z

177

A semi-experimental nodal synthesis method for the on-line reconstruction of three-dimensional neutron flux-shapes and reactivity  

SciTech Connect

The safety and optimal performance of large, commercial, light-water reactors require the knowledge at all time of the neutron-flux distribution in the core. In principle, this information can be obtained by solving the time-dependent neutron diffusion equations. However, this approach is complicated and very expensive. Sufficiently accurate, real-time calculations (time scale of approximately one second) are not yet possible on desktop computers, even with fast-running, nodal kinetics codes. A semi-experimental, nodal synthesis method which avoids the solution of the time-dependent, neutron diffusion equations is described. The essential idea of this method is to approximate instantaneous nodal group-fluxes by a linear combination of K, precomputed, three-dimensional, static expansion-functions. The time-dependent coefficients of the combination are found from the requirement that the reconstructed flux-distribution agree in a least-squares sense with the readings of J ({ge}K) fixed, prompt-responding neutron-detectors. Possible numerical difficulties with the least-squares solution of the ill-conditioned, J-by-K system of equations are brought under complete control by the use of a singular-value-decomposition technique. This procedure amounts to the rearrangement of the original, linear combination of K expansion functions into an equivalent more convenient, linear combination of R ({le}K) orthogonalized modes'' of decreasing magnitude. Exceedingly small modes are zeroed to eliminate any risk of roundoff-error amplification, and to assure consistency with the limited accuracy of the data. Additional modes are zeroed when it is desirable to limit the sensitivity of the results to measurement noise.

Jacqmin, R.P.

1991-12-10T23:59:59.000Z

178

A semi-experimental nodal synthesis method for the on-line reconstruction of three-dimensional neutron flux-shapes and reactivity. Final report  

SciTech Connect

The safety and optimal performance of large, commercial, light-water reactors require the knowledge at all time of the neutron-flux distribution in the core. In principle, this information can be obtained by solving the time-dependent neutron diffusion equations. However, this approach is complicated and very expensive. Sufficiently accurate, real-time calculations (time scale of approximately one second) are not yet possible on desktop computers, even with fast-running, nodal kinetics codes. A semi-experimental, nodal synthesis method which avoids the solution of the time-dependent, neutron diffusion equations is described. The essential idea of this method is to approximate instantaneous nodal group-fluxes by a linear combination of K, precomputed, three-dimensional, static expansion-functions. The time-dependent coefficients of the combination are found from the requirement that the reconstructed flux-distribution agree in a least-squares sense with the readings of J ({ge}K) fixed, prompt-responding neutron-detectors. Possible numerical difficulties with the least-squares solution of the ill-conditioned, J-by-K system of equations are brought under complete control by the use of a singular-value-decomposition technique. This procedure amounts to the rearrangement of the original, linear combination of K expansion functions into an equivalent more convenient, linear combination of R ({le}K) orthogonalized ``modes`` of decreasing magnitude. Exceedingly small modes are zeroed to eliminate any risk of roundoff-error amplification, and to assure consistency with the limited accuracy of the data. Additional modes are zeroed when it is desirable to limit the sensitivity of the results to measurement noise.

Jacqmin, R.P.

1991-12-10T23:59:59.000Z

179

Impact of high-energy nuclear data on radioprotection in spallation sources  

Science Journals Connector (OSTI)

......the neutron spectrum, which is...spallation neutron sources and...problems induced by high-energy reactions...low-energy neutron fluxes...tail in the spectrum of neutrons...evaporation-fission models...leading to a thermal flux of 3......

S. Leray; A. Boudard; J. C. David; L. Donadille; C. Villagrasa; C. Volant

2005-12-20T23:59:59.000Z

180

Measurements of neutron-induced reactions in inverse kinematics  

E-Print Network (OSTI)

Neutron capture cross sections of unstable isotopes are important for neutron induced nucleosynthesis as well as for technological applications. A combination of a radioactive beam facility, an ion storage ring and a high flux reactor would allow a direct measurement of neutron induced reactions over a wide energy range on isotopes with half lives down to minutes.

René Reifarth; Yuri A. Litvinov

2013-12-13T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Inelastic neutron scattering from single crystal Zn under high pressure  

Science Journals Connector (OSTI)

Inelastic neutron-scattering experiments have been performed for single crystals of Zn under pressures up to 8.8 GPa at 300 K. The phonon modes q/qmax=?=0.075 and ?=0.10 were measured in the transverse acoustic branch ?3, where q=0 corresponds with the elastic constant C44. The phonon energy showed a substantial hardening with increasing pressure. The experimental data below 6.8 GPa for ?=0.075 yield a constant Grüneisen mode ?i=-ln?i/lnV of 2.25 in good agreement with a previous calculation [H. Ledbetter, Phys. Status Solidi B 181, 81 (1994)]. Above 6.8 GPa, there is a very rapid increase of ?i which is indicative of the presence of a giant Kohn anomaly. This rapid divergence at high pressure indicates that a phonon softening may occur at pressures higher than 8.8 GPa caused by the collapse of the giant Kohn anomaly via an electronic topological transition (ETT). In an earlier Mössbauer Zn study at 4 K [W. Potzel et al., Phys. Rev. Lett. 74, 1139 (1994)], a drastic drop of the Lamb-Mössbauer factor was observed at 6.6 GPa, which was interpreted as being due to phonon softening, indicating this ETT had occurred. This paper also compares the compressibility data for single crystal Zn and Zn powder using neutron scattering. The results were found to be similar to an earlier x-ray Zn powder experiment [O. Schulte et al., High Pressure Res. 6, 169 (1991)]. © 1996 The American Physical Society.

J. G. Morgan; R. B. Von Dreele; P. Wochner; S. M. Shapiro

1996-07-01T23:59:59.000Z

182

High-Resolution Fast-Neutron Spectrometry for Arms Control and Treaty Verification  

SciTech Connect

Many nondestructive nuclear analysis techniques have been developed to support the measurement needs of arms control and treaty verification, including gross photon and neutron counting, low- and high-resolution gamma spectrometry, time-correlated neutron measurements, and photon and neutron imaging. One notable measurement technique that has not been extensively studied to date for these applications is high-resolution fast-neutron spectrometry (HRFNS). Applied for arms control and treaty verification, HRFNS has the potential to serve as a complimentary measurement approach to these other techniques by providing a means to either qualitatively or quantitatively determine the composition and thickness of non-nuclear materials surrounding neutron-emitting materials. The technique uses the normally-occurring neutrons present in arms control and treaty verification objects of interest as an internal source of neutrons for performing active-interrogation transmission measurements. Most low-Z nuclei of interest for arms control and treaty verification, including 9Be, 12C, 14N, and 16O, possess fast-neutron resonance features in their absorption cross sections in the 0.5- to 5-MeV energy range. Measuring the selective removal of source neutrons over this energy range, assuming for example a fission-spectrum starting distribution, may be used to estimate the stoichiometric composition of intervening materials between the neutron source and detector. At a simpler level, determination of the emitted fast-neutron spectrum may be used for fingerprinting 'known' assemblies for later use in template-matching tests. As with photon spectrometry, automated analysis of fast-neutron spectra may be performed to support decision making and reporting systems protected behind information barriers. This paper will report recent work at Idaho National Laboratory to explore the feasibility of using HRFNS for arms control and treaty verification applications, including simulations and experiments, using fission-spectrum neutron sources to assess neutron transmission through composite low-Z attenuators.

David L. Chichester; James T. Johnson; Edward H. Seabury

2012-07-01T23:59:59.000Z

183

Instrumentation development for neutron scattering at high pressure.  

E-Print Network (OSTI)

??Neutron scattering at extremes of pressure is a powerful tool for studying the response of structural and magnetic properties of materials on microscopic level to… (more)

Fang, Junwei

2012-01-01T23:59:59.000Z

184

CRAD, Management- Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Management portion of an Operational Readiness Review of the Oak Ridge National Laboratory High Flux Isotope Reactor.

185

CRAD, Environmental Protection- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Environmental Compliance Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor.

186

CRAD, Configuration Management- Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Configuration Management Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory, High Flux Isotope Reactor.

187

Be7(p,gamma)B8 and the high-energy solar neutrino flux  

E-Print Network (OSTI)

The importance of the Be7(p,gamma)B8 reaction in predicting the high-energy solar neutrino flux is discussed. I present a microscopic eight-body model and a potential model for the calculation of the Be7(p,gamma)B8 cross section.

Attila Csoto

1997-04-23T23:59:59.000Z

188

CRAD, Occupational Safety & Health- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Industrial Safety and Hygiene Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor.

189

CRAD, Configuration Management- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Configuration Management Program in preparation for restart of the Oak Ridge National Laboratory, High Flux Isotope Reactor.

190

Application of High-Order Energy Stable Flux Reconstruction Schemes to the Euler Equations  

E-Print Network (OSTI)

and Astronautics 49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 4, Stanford, CA, 94305 The authors recently identified an infinite range of high-order energy stable flux method). Identification of such schemes represents a significant advance in terms of understanding why

Jameson, Antony

191

CRAD, Emergency Management- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Emergency Management Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor.

192

MERLOT: a model for flow and heat transfer through porous media for high heat flux applications  

E-Print Network (OSTI)

MERLOT: a model for flow and heat transfer through porous media for high heat flux applications A Abstract Fusion power plant studies have found helium to be an attractive coolant based on its safety tend to provide modest heat transfer performance due to their inherently low heat capacity and heat

Raffray, A. René

193

CRAD, Conduct of Operations- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February, 2007 assessment of the Conduct of Operations Program in preparation for restart of the Oak Ridge National Laboratory, High Flux Isotope Reactor.

194

CRAD, Conduct of Operations- Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February, 2007 assessment of the Conduct of Operations Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory, High Flux Isotope Reactor.

195

CRAD, Training- Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Training Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory High Flux Isotope Reactor.

196

CRAD, Radiological Controls- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Radiation Protection Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor.

197

CRAD, Safety Basis- Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Safety Basis portion of an Operational Readiness Review of the Oak Ridge National Laboratory High Flux Isotope Reactor.

198

CRAD, Safety Basis- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Safety Basis in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor.

199

CRAD, Maintenance- Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Maintenance Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory High Flux Isotope Reactor.

200

CRAD, Occupational Safety & Health- Oak Ridge National Laboratory High Flux Isotope Reactor Contractor ORR  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Occupational Safety and Health Program portion of an Operational Readiness Review of the Oak Ridge National Laboratory High Flux Isotope Reactor.

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

CRAD, Nuclear Safety- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Nuclear Safety Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor.

202

CRAD, Quality Assurance- Oak Ridge National Laboratory High Flux Isotope Reactor  

Energy.gov (U.S. Department of Energy (DOE))

A section of Appendix C to DOE G 226.1-2 "Federal Line Management Oversight of Department of Energy Nuclear Facilities." Consists of Criteria Review and Approach Documents (CRADs) used for a February 2007 assessment of the Quality Assurance Program in preparation for restart of the Oak Ridge National Laboratory High Flux Isotope Reactor.

203

EIS-0291: High Flux Beam Reactor (HFBR) Transition Project at the Brookhaven National Laboratory, Upton, New York  

Energy.gov (U.S. Department of Energy (DOE))

The EIS evaluates the range of reasonable alternatives and their impacts regarding the future management of the High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory (BNL).

204

INDEPENDENT VERIFICATION SURVEY OF THE HIGH FLUX BEAM REACTOR DECOMMISSIONING PROJECT OUTSIDE AREAS BROOKHAVEN NATIONAL LABORATORY UPTON, NEW YORK  

SciTech Connect

5098-SR-03-0 FINAL REPORT- INDEPENDENT VERIFICATION SURVEY OF THE HIGH FLUX BEAM REACTOR DECOMMISSIONING PROJECT OUTSIDE AREAS, BROOKHAVEN NATIONAL LABORATORY

P.C. Weaver

2010-12-15T23:59:59.000Z

205

LETTER REPORT INDEPENDENT VERIFICATION OF THE HIGH FLUX BEAM REACTOR DECOMMISSIONING PROJECT FAN HOUSE, BUILDING 704 BNL  

SciTech Connect

5098-LR-01-0 -LETTER REPORT INDEPENDENT VERIFICATION OF THE HIGH FLUX BEAM REACTOR DECOMMISSIONING PROJECT FAN HOUSE, BUILDING 704 BROOKHAVEN NATIONAL LABORATORY

P.C. Weaver

2010-10-22T23:59:59.000Z

206

Design Study for a Low-Enriched Uranium Core for the High Flux Isotope Reactor, Annual Report for FY 2006  

SciTech Connect

Neutronics and thermal-hydraulics studies show that, for equivalent operating power [85 MW(t)], a low-enriched uranium (LEU) fuel cycle based on uranium-10 wt % molybdenum (U-10Mo) metal foil with radially, “continuously graded” fuel meat thickness results in a 15% reduction in peak thermal flux in the beryllium reflector of the High Flux Isotope Reactor (HFIR) as compared to the current highly enriched uranium (HEU) cycle. The uranium-235 content of the LEU core is almost twice the amount of the HEU core when the length of the fuel cycle is kept the same for both fuels. Because the uranium-238 content of an LEU core is a factor of 4 greater than the uranium-235 content, the LEU HFIR core would weigh 30% more than the HEU core. A minimum U-10Mo foil thickness of 84 ?m is required to compensate for power peaking in the LEU core although this value could be increased significantly without much penalty. The maximum U-10Mo foil thickness is 457?m. Annual plutonium production from fueling the HFIR with LEU is predicted to be 2 kg. For dispersion fuels, the operating power for HFIR would be reduced considerably below 85 MW due to thermal considerations and due to the requirement of a 26-d fuel cycle. If an acceptable fuel can be developed, it is estimated that $140 M would be required to implement the conversion of the HFIR site at Oak Ridge National Laboratory from an HEU fuel cycle to an LEU fuel cycle. To complete the conversion by fiscal year 2014 would require that all fuel development and qualification be completed by the end of fiscal year 2009. Technological development areas that could increase the operating power of HFIR are identified as areas for study in the future.

Primm, R. T. [ORNL] [ORNL; Ellis, R. J. [ORNL] [ORNL; Gehin, J. C. [ORNL] [ORNL; Clarno, K. T. [ORNL] [ORNL; Williams, K. A. [ORNL] [ORNL; Moses, D. L. [ORNL] [ORNL

2006-11-01T23:59:59.000Z

207

PEAK FLUX DISTRIBUTIONS OF SOLAR RADIO TYPE-I BURSTS FROM HIGHLY RESOLVED SPECTRAL OBSERVATIONS  

SciTech Connect

Solar radio type-I bursts were observed on 2011 January 26 by high resolution observations with the radio telescope AMATERAS in order to derive their peak flux distributions. We have developed a two-dimensional auto burst detection algorithm that can distinguish each type-I burst element from complex noise storm spectra that include numerous instances of radio frequency interference (RFI). This algorithm removes RFI from the observed radio spectra by applying a moving median filter along the frequency axis. Burst and continuum components are distinguished by a two-dimensional maximum and minimum search of the radio dynamic spectra. The analysis result shows that each type-I burst element has one peak flux without double counts or missed counts. The peak flux distribution of type-I bursts derived using this algorithm follows a power law with a spectral index between 4 and 5.

Iwai, K. [Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Nobeyama, Nagano 384-1305 (Japan); Masuda, S.; Miyoshi, Y. [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Aichi 464-8601 (Japan); Tsuchiya, F.; Morioka, A.; Misawa, H., E-mail: kazumasa.iwai@nao.ac.jp [Planetary Plasma and Atmospheric Research Center, Tohoku University, Sendai, Miyagi 980-8578 (Japan)

2013-05-01T23:59:59.000Z

208

Workplace characterisation in mixed neutron-gamma fields, specific requirements and available methods at high-energy accelerators  

Science Journals Connector (OSTI)

......activation is only induced with quite large fast neutron fluence rates...materials for neutron activation...respectively. The thermal and epithermal...components of the neutron spectrum are discriminated...the high-energy hadron component...registration of fission fragments...neutron-induced lighter secondary......

Marco Silari

2007-04-01T23:59:59.000Z

209

Design of a High Flux Vacuum-Ultraviolet Beamline for Circular Dichroism Experiments  

SciTech Connect

A vacuum-ultraviolet bending-magnet beamline for circular dichroism (CD) experiments has been designed. To maximize the photon flux and minimize the focused beam size, a cylindrical mirror and a cylindrical grating with independent optical functions are utilized. The beamline can collect a 30 mrad horizontal by 7 mrad vertical solid angle of synchrotron radiation. By using a 600 grooves/mm grating, the calculated photon flux is greater than 1x10{sup 13} photons/sec and the focused beam size is 0.4 mmx0.65 mm for the spectral range from 130 nm to 330 nm with the energy resolving power set at 1000. The linear polarization degree is better than 75% and can be increased to 90% by reducing the vertical acceptance angle down to 2 mrad. In addition to the high flux mode described above, this beamline can also be operated in a high resolution mode. By using a 1200 grooves/mm grating, a resolving power greater than 10,000 can be achieved for the spectral range from 180 to 330 nm. This beamline can provide photon flux as high as the best synchrotron CD beamlines in the world while offers simultaneously a smaller focused beam size.

Fu, H. W.; Fung, H. S.; Chung, S. C.; Huang, L. J.; Chen, C. T. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China)

2010-06-23T23:59:59.000Z

210

The Role and Detectability of the Charm Contribution to Ultra High Energy Neutrino Fluxes  

E-Print Network (OSTI)

It is widely believed that charm meson production and decay may play an important role in high energy astrophysical sources of neutrinos, especially those that are baryon-rich, providing an environment conducive to pp interactions. Using slow-jet supernovae (SJS) as an example of such a source, we study the detectability of high-energy neutrinos, paying particular attention to those produced from charmed-mesons. We highlight important distinguishing features in the ultra-high energy neutrino flux which would act as markers for the role of charm in the source. In particular, charm leads to significant event rates at higher energies, after the conventional (pi, K) neutrino fluxes fall off. We calculate event rates both for a nearby single source and for diffuse SJS fluxes for an IceCube-like detector. By comparing muon event rates for the conventional and prompt fluxes in different energy bins, we demonstrate the striking energy dependence in the rates induced by the presence of charm. We also show that it lead...

Gandhi, Raj; Watanabe, Atsushi

2009-01-01T23:59:59.000Z

211

Direct ion flux measurements at high-pressure-depletion conditions for microcrystalline silicon deposition  

SciTech Connect

The contribution of ions to the growth of microcrystalline silicon thin films has been investigated in the well-known high-pressure-depletion (HPD) regime by coupling thin-film analysis with plasma studies. The ion flux, measured by means of a capacitive probe, has been studied in two regimes, i.e., the amorphous-to-microcrystalline transition regime and a low-to-high power regime; the latter regime had been investigated to evaluate the impact of the plasma power on the ion flux in collisional plasmas. The ion flux was found not to change considerably under the conditions where the deposited material undergoes a transition from the amorphous to the microcrystalline silicon phase; for solar-grade material, an ion-to-Si deposition flux of ?0.30 has been determined. As an upper-estimation of the ion energy, a mean ion energy of ?19 eV has been measured under low-pressure conditions (<1 mbar) by means of a retarding field energy analyzer. Combining this upper-estimate with an ion per deposited Si atom ratio of ?0.30, it is concluded that less than 6 eV is available per deposited Si atom. The addition of a small amount of SiH{sub 4} to an H{sub 2} plasma resulted in an increase of the ion flux by about 30% for higher power values, whereas the electron density, deduced from optical emission spectroscopy analysis, decreased. The electron temperature, also deduced from optical emission spectroscopy analysis, reveals a slight decrease with power. Although the dominant ion in the HPD regime is SiH{sub 3}{sup +}, i.e., a change from H{sub 3}{sup +} in pure hydrogen HPD conditions, the measured larger ion loss can be explained by assuming steeper electron density profiles. These results, therefore, confirm the results reported so far: the ion-to-Si deposition flux is relatively large but has neither influence on the microcrystalline silicon film properties nor on the phase transition. Possible explanations are the reported high atomic hydrogen to deposition flux ratio, mitigating the detrimental effects of an excessive ion flux.

Bronneberg, A. C.; Kang, X.; Palmans, J.; Janssen, P. H. J.; Lorne, T. [Applied Physics Department, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven (Netherlands)] [Applied Physics Department, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven (Netherlands); Creatore, M. [Applied Physics Department, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven (Netherlands) [Applied Physics Department, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven (Netherlands); Solliance Solar Research, High Tech Campus 5, 5656AE Eindhoven (Netherlands); Sanden, M. C. M. van de [Applied Physics Department, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven (Netherlands); Dutch Institute for Fundamental Energy Research (DIFFER), P.O. Box 1207, 3430BE Nieuwegein (Netherlands)

2013-08-14T23:59:59.000Z

212

The use of PRA (Probabilistic Risk Assessment) in the management of safety issues at the High Flux Isotope Reactor  

SciTech Connect

The High Flux Isotope reactor (HFIR) is a high performance isotope production and research reactor which has been in operation at Oak Ridge National Laboratory (ORNL) since 1965. In late 1986 the reactor was shut down as a result of discovery of unexpected neutron embrittlement of the reactor vessel. In January of 1988, a level 1 Probabilistic Risk Assessment (PRA) (excluding external events) was published as part of the response to the many reviews that followed the shutdown and for use by ORNL to prioritize action items intended to upgrade the safety of the reactor. A conservative estimate of the core damage frequency initiated by internal events for HFIR was 3.11 {times} 10{sup {minus}4}. In June 1989 a draft external events initiated PRA was published. The dominant contributions from external events came from seismic, wind, and fires. The overall external event contribution to core damage frequency is about 138% of the internal event initiated contribution and is dominated by wind initiators. The PRA has provided a basis for the management of a wide range of safety and operation issues at the HFIR. 3 refs., 4 figs., 2 tabs.

Flanagan, G.F.

1990-01-01T23:59:59.000Z

213

Development of multicathode high flux metal ion plasma sources in Korea  

SciTech Connect

Multicathode high flux metal plasma ion sources were self-developed and its performance was proved to be appropriate for the high-purity ion implantation and thin-film deposition. As key results of self-design, a bipolar pulse power supply with a peak voltage of 250 V, a repetition rate of 20 Hz, and a pulse width of 100 {mu}s showed an output current of 2 kA and an average power of 2 kW and the operational plasma flux of multicathode ion source was well sustained even at an ion current of about 5 A. A high-voltage pulse generator was employed as a trigger power supply producing a peak voltage of 12 kV, peak current of 50 A, and stable repetition rate of 20 Hz.

Kim, Do-Yun; Lee, Eui-Wan; Lee, Myoung-Bok [Department of Physics, Kyungpook National University, Taegu 702-701 (Korea, Republic of); School of Electrical and Electronics Engineering, Kyungpook National University, Taegu 702-701 (Korea, Republic of)

2004-09-01T23:59:59.000Z

214

High Density Neutron Star Equation of State from 4U 1636-53 Observations  

E-Print Network (OSTI)

A bound on the compactness of the neutron star in the low mass x-ray binary 4U 1636-53 is used to estimate the equation of state of neutron star matter at high density. Observations of 580 Hz oscillations during the rising phase of x-ray bursts from this system appear to be due to two antipodal hot spots on the surface of an accreting neutron star rotating at 290 Hz, implying the compactness of the neutron star is less than 0.163 at the 90% confidence level. The equation of state of high density neutron star matter estimated from this compactness limit is significantly stiffer than extrapolations to high density of equations of state determined by fits of experimental nucleon-nucleon scattering data and properties of light nuclei to two- and three-body interaction potentials.

T. S. Olson

2002-01-07T23:59:59.000Z

215

Quasielastic Neutron Scattering in the High-Field Phase of a Haldane Antiferromagnet  

Science Journals Connector (OSTI)

Inelastic neutron scattering experiments on the Haldane-gap quantum antiferromagnet Ni(C5D14N2)2-N3(PF6) are performed in magnetic fields below and above the critical field Hc at which the gap closes. Quasielastic neutron scattering is found for H>Hc, indicating topological excitations in the high-field phase.

A. Zheludev; Z. Honda; Y. Chen; C. L. Broholm; K. Katsumata; S. M. Shapiro

2002-02-05T23:59:59.000Z

216

Optimizing Neutron Thermal Scattering Effects in very High Temperature Reactors  

SciTech Connect

This project aims to develop a holistic understanding of the phenomenon of neutron thermalization in the VHTR. Neutron thermaliation is dependent on the type and structure of the moderating material. The fact that the moderator (and reflector) in the VHTR is a solid material will introduce new and interesting considerations that do not apply in other (e.g. light water) reactors. The moderator structure is expected to undergo radiation induced changes as the irradiation (or burnup) history progresses. In this case, the induced changes in structure will have a direct impact on many properties including the neutronic behavior. This can be easily anticipated if one recognizes the dependence of neutron thermalization on the scattering law of the moderator. For the pebble bed reactor, it is anticipated that the moderating behavior can be tailored, e.g. using moderators that consist of composite materials, which could allow improved optimization of the moderator-to-fuel ratio.

Hawari, Ayman; Ougouag, Abderrafi

2014-07-08T23:59:59.000Z

217

High-power electron beam tests of a liquid-lithium target and characterization study of 7Li(p,n) near-threshold neutrons for accelerator-based boron neutron capture therapy  

Science Journals Connector (OSTI)

Abstract A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center (SNRC). The target is intended to demonstrate liquid-lithium target capabilities to constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals. The lithium target will produce neutrons through the 7Li(p,n)7Be reaction and it will overcome the major problem of removing the thermal power >5 kW generated by high-intensity proton beams, necessary for sufficient therapeutic neutron flux. In preliminary experiments liquid lithium was flown through the target loop and generated a stable jet on the concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power densities of more than 4 kW/cm2 and volumetric power density around 2 MW/cm3 at a lithium flow of ~4 m/s, while maintaining stable temperature and vacuum conditions. These power densities correspond to a narrow (?=~2 mm) 1.91 MeV, 3 mA proton beam. A high-intensity proton beam irradiation (1.91–2.5 MeV, 2 mA) is being commissioned at the SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator. In order to determine the conditions of LiLiT proton irradiation for BNCT and to tailor the neutron energy spectrum, a characterization of near threshold (~1.91 MeV) 7Li(p,n) neutrons is in progress based on Monte-Carlo (MCNP and Geant4) simulation and on low-intensity experiments with solid LiF targets. In-phantom dosimetry measurements are performed using special designed dosimeters based on CR-39 track detectors.

S. Halfon; M. Paul; A. Arenshtam; D. Berkovits; D. Cohen; I. Eliyahu; D. Kijel; I. Mardor; I. Silverman

2014-01-01T23:59:59.000Z

218

Review of the Oak Ridge National Laboratory High Flux Isotope Reactor Implementation Verification Review Processes  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Independent Oversight Review of the Independent Oversight Review of the Oak Ridge National Laboratory High Flux Isotope Reactor Implementation Verification Review Processes May 2011 January 2013 Office of Safety and Emergency Management Evaluations Office of Enforcement and Oversight Office of Health, Safety and Security U. S. Department of Energy Table of Contents 1.0 Purpose ................................................................................................................................................. 1 2.0 Background........................................................................................................................................... 1 3.0 Scope..................................................................................................................................................... 2

219

Review of the Oak Ridge National Laboratory High Flux Isotope Reactor Implementation Verification Review Processes  

NLE Websites -- All DOE Office Websites (Extended Search)

Independent Oversight Review of the Independent Oversight Review of the Oak Ridge National Laboratory High Flux Isotope Reactor Implementation Verification Review Processes May 2011 January 2013 Office of Safety and Emergency Management Evaluations Office of Enforcement and Oversight Office of Health, Safety and Security U. S. Department of Energy Table of Contents 1.0 Purpose ................................................................................................................................................. 1 2.0 Background........................................................................................................................................... 1 3.0 Scope..................................................................................................................................................... 2

220

Portable Neutron Sensors for Emergency Response Operations  

SciTech Connect

This article presents the experimental work performed in the area of neutron detector development at the Remote Sensing Laboratory–Andrews Operations (RSL-AO) sponsored by the U.S. Department of Energy, National Nuclear Security Administration (NNSA) in the last four years. During the 1950s neutron detectors were developed mostly to characterize nuclear reactors where the neutron flux is high. Due to the indirect nature of neutron detection via interaction with other particles, neutron counting and neutron energy measurements have never been as precise as gamma-ray counting measurements and gamma-ray spectroscopy. This indirect nature is intrinsic to all neutron measurement endeavors (except perhaps for neutron spin-related experiments, viz. neutron spin-echo measurements where one obtains ?eV energy resolution). In emergency response situations generally the count rates are low, and neutrons may be scattered around in inhomogeneous intervening materials. It is also true that neutron sensors are most efficient for the lowest energy neutrons, so it is not as easy to detect and count energetic neutrons. Most of the emergency response neutron detectors are offshoots of nuclear device diagnostics tools and special nuclear materials characterization equipment, because that is what is available commercially. These instruments mostly are laboratory equipment, and not field-deployable gear suited for mobile teams. Our goal is to design and prototype field-deployable, ruggedized, lightweight, efficient neutron detectors.

,

2012-06-24T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Fast neutron emission from a deuterated polystyrene solid target irradiated by a high-intensity laser pulse  

Science Journals Connector (OSTI)

Fast neutrons were generated from a deuterated polystyrene (C8D8) solid-target irradiated by a high-intensity laser. A TOF neutron signal is analyzed in detail. A...

Lee, Sungman; Kwon, Sungok; Lee, Kitae; Cha, Yong-Ho; Yea, Kwon-hae; Lee, Yong Woo; Lee, Ji Young; Jeong, Young Uk; Rhee, Yong Joo; Cha, Hyungki

222

Fast neutron emission from a deuterated polystyrene solid target irradiated by a high-intensity laser pulse  

Science Journals Connector (OSTI)

Fast neutrons were generated from a deuterated polystyrene (C8D8) solid-target irradiated by a high-intensity laser. A TOF neutron signal is analyzed in detail....

Lee, Sungman; Kwon, Sungok; Lee, Kitae; Cha, Yong-Ho; Yea, Kwon-hae; Lee, Yong Woo; Lee, Ji Young; Jeong, Young Uk; Rhee, Yong Joo; Cha, Hyungki

223

Workplace characterisation in mixed neutron-gamma fields, specific requirements and available methods at high-energy accelerators  

Science Journals Connector (OSTI)

......for routine radiation therapy of cancer, to medium-energy cyclotrons...for applied research and advanced cancer therapy with protons and light...High-energy neutrons are converted by a depleted uranium shell producing fission neutrons......

Marco Silari

2007-04-01T23:59:59.000Z

224

A six-axis robotic sample changer for high-throughput neutron powder diffraction and texture measurements  

Science Journals Connector (OSTI)

A new six-axis robotic sample changer for neutron powder diffraction experiments, including texture measurements, has enabled a novel set of experiments to be performed at the High-Pressure Preferred Orientation diffractometer at the Lujan Neutron Scattering Center.

Losko, A.S.

2014-11-18T23:59:59.000Z

225

Optical design of a high radiative flux solar furnace for Mexico  

Science Journals Connector (OSTI)

In the present work, the optical design of a new high radiative flux solar furnace is described. Several optical configurations for the concentrator of the system have been considered. Ray tracing simulations were carried out in order to determine the concentrated radiative flux distributions in the focal zone of the system, for comparing the different proposals. The best configuration was chosen in terms of maximum peak concentration, but also in terms of economical and other practical considerations. It consists of an arrangement of 409 first surface spherical facets with hexagonal shape, mounted on a spherical frame. The individual orientation of the facets is corrected in order to compensate for aberrations. The design considers an intercepted power of 30 kW and a target peak concentration above 10,000 suns. The effect of optical errors was also considered in the simulations.

D. Riveros-Rosas; J. Herrera-Vázquez; C.A. Pérez-Rábago; C.A. Arancibia-Bulnes; S. Vázquez-Montiel; M. Sánchez-González; F. Granados-Agustín; O.A. Jaramillo; C.A. Estrada

2010-01-01T23:59:59.000Z

226

A high flux of ultra-cold chromium atoms in a magnetic guide  

Science Journals Connector (OSTI)

We report the observation of a very high flux of ultra-cold bosonic chromium atoms in a magnetic guide. The beam is created by operating a magneto-optical trap/moving optical molasses within the magnetic field of the guide. A relative detuning between two pairs of the cooling lasers cools the atoms into a frame moving along the axes of the guide. When the atoms are cooled into a moving frame with a velocity of 6 m s?1 we observe a maximum of the flux of 6 ? 109 atoms s?1. For these parameters the transversal temperature of the atoms after a 25 fold increase of the confining magnetic potential is about 1.2 mK. The longitudinal temperature is 400 µK.

Axel Griesmaier; Anoush Aghajani-Talesh; Markus Falkenau; Jimmy Sebastian; Alexander Greiner; Tilman Pfau

2009-01-01T23:59:59.000Z

227

Determination of the theoretical feasibility for the transmutation of europium isotopes from high flux isotope reactor control cylinders  

SciTech Connect

The High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) is a 100 MWth light-water research reactor designed and built in the 1960s primarily for the production of transuranic isotopes. The HFIR is equipped with two concentric cylindrical blade assemblies, known as control cylinders, that are used to control reactor power. These control cylinders, which become highly radioactive from neutron exposure, are periodically replaced as part of the normal operation of the reactor. The highly radioactive region of the control cylinders is composed of europium oxide in an aluminum matrix. The spent HFIR control cylinders have historically been emplaced in the ORNL Waste Area Grouping (WAG) 6. The control cylinders pose a potential radiological hazard due to the long lived radiotoxic europium isotopes {sup 152}Eu, {sup 154}Eu, and {sup 155}Eu. In a 1991 health evaluation of WAG 6 (ERD 1991) it was shown that these cylinders were a major component of the total radioactivity in WAG 6 and posed a potential exposure hazard to the public in some of the postulated assessment scenarios. These health evaluations, though preliminary and conservative in nature, illustrate the incentive to investigate methods for permanent destruction of the europium radionuclides. When the cost of removing the control cylinders from WAG 6, performing chemical separations and irradiating the material in HFIR are factored in, the option of leaving the control cylinders in place for decay must be considered. Other options, such as construction of an engineered barrier around the disposal silos to reduce the chance of migration, should also be analyzed.

Elam, K.R.; Reich, W.J.

1995-09-01T23:59:59.000Z

228

High conduction neutron absorber to simulate fast reactor environment in an existing test reactor  

SciTech Connect

A new metal matrix composite material has been developed to serve as a thermal neutron absorber for testing fast reactor fuels and materials in an existing pressurized water reactor. The performance of this material was evaluated by placing neutron fluence monitors within shrouded and unshrouded holders and irradiating for up to four cycles. The monitor wires were analyzed by gamma and X-ray spectrometry to determine the activities of the activation products. Adjusted neutron fluences were calculated and grouped into three bins—thermal, epithermal, and fast—to evaluate the spectral shift created by the new material. A comparison of shrouded and unshrouded fluence monitors shows a thermal fluence decrease of ~11 % for the shielded monitors. Radioisotope activity and mass for each of the major activation products is given to provide insight into the evolution of thermal absorption cross-section during irradiation. The thermal neutron absorption capability of the composite material appears to diminish at total neutron fluence levels of ~8 × 1025 n/m2. Calculated values for dpa in excess of 2.0 were obtained for two common structural materials (iron and nickel) of interest for future fast flux experiments.

Donna Post Guillen; Larry R. Greenwood; James R. Parry

2014-10-01T23:59:59.000Z

229

Computation of neutron fluxes in clusters of fuel pins arranged in hexagonal assemblies (2D and 3D)  

SciTech Connect

For computations of fluxes, we have used Carvik's method of collision probabilities. This method requires tracking algorithms. An algorithm to compute tracks (in 2D and 3D) has been developed for seven hexagonal geometries with cluster of fuel pins. This has been implemented in the NXT module of the code DRAGON. The flux distribution in cluster of pins has been computed by using this code. For testing the results, they are compared when possible with the EXCELT module of the code DRAGON. Tracks are plotted in the NXT module by using MATLAB, these plots are also presented here. Results are presented with increasing number of lines to show the convergence of these results. We have numerically computed volumes, surface areas and the percentage errors in these computations. These results show that 2D results converge faster than 3D results. The accuracy on the computation of fluxes up to second decimal is achieved with fewer lines. (authors)

Prabha, H.; Marleau, G. [Institut de Genie Nucleaire, Ecole Polytechnique de Montreal, Stn. CV, P.O. Box 6079, Montreal, QC H3C 3A7 (Canada)

2012-07-01T23:59:59.000Z

230

Analysis and Design of a High Power Density Axial Flux Permanent Magnet Linear Synchronous Machine Used for Stirling System  

Science Journals Connector (OSTI)

a high power density axial flux permanent magnet linear synchronous machine and the stirling system will be introduced. This machine is a tubular axial flux permanent magnet machine. It comprises two parts: stator and mover. With the 2D finite-element ... Keywords: permanent magnet, stirling engine, linear motor

Ping Zheng; Xuhui Gan; Lin Li

2010-09-01T23:59:59.000Z

231

High-Latitude Ocean and Sea Ice Surface Fluxes: Challenges for Climate Research Mark A. Bourassa1  

E-Print Network (OSTI)

, the Wilkins Ice Shelf collapsed equally quickly (Scambos et al. 2009). Ocean heat content is rising rapidlyHigh-Latitude Ocean and Sea Ice Surface Fluxes: Challenges for Climate Research Mark A. Bourassa1 conditions for the measurement and estimation of air­sea and ice fluxes, limiting understanding of related

Gille, Sarah T.

232

High-Latitude Ocean and Sea Ice Surface Fluxes: Challenges for Climate Research1 Mark A. Bourassa1  

E-Print Network (OSTI)

), and in 2008, the Wilkins Ice Shelf51 collapsed equally quickly (Scambos et al. 2009). Ocean heat content1 High-Latitude Ocean and Sea Ice Surface Fluxes: Challenges for Climate Research1 2 Mark A conditions for the measurement and estimation of air­27 sea and ice fluxes, limiting understanding of related

Gille, Sarah T.

233

High-Latitude Ocean and Sea Ice Surface Fluxes: Challenges for Climate Research1 Mark A. Bourassa1  

E-Print Network (OSTI)

), and in 2008, the Wilkins Ice Shelf51 collapsed equally quickly (Scambos et al. 2009). Ocean heat content1 High-Latitude Ocean and Sea Ice Surface Fluxes: Challenges for Climate Research1 2 Mark A-latitude surface fluxes will require close collaboration among meteorologists,33 oceanographers, ice physicists

Gille, Sarah T.

234

A new compact, high sensitivity neutron imaging system  

SciTech Connect

We have developed a new small neutron imaging system (SNIS) diagnostic for the OMEGA laser facility. The SNIS uses a penumbral coded aperture and has been designed to record images from low yield (10{sup 9}-10{sup 10} neutrons) implosions such as those using deuterium as the fuel. This camera was tested at OMEGA in 2009 on a rugby hohlraum energetics experiment where it recorded an image at a yield of 1.4 Multiplication-Sign 10{sup 10}. The resolution of this image was 54 {mu}m and the camera was located only 4 meters from target chamber centre. We recently improved the instrument by adding a cooled CCD camera. The sensitivity of the new camera has been fully characterized using a linear accelerator and a {sup 60}Co {gamma}-ray source. The calibration showed that the signal-to-noise ratio could be improved by using raw binning detection.

Caillaud, T.; Landoas, O.; Briat, M.; Rosse, B.; Thfoin, I.; Philippe, F.; Casner, A.; Bourgade, J. L.; Disdier, L. [CEA, DAM, DIF,F-91297 Arpajon (France); Glebov, V. Yu.; Marshall, F. J.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Park, H. S.; Robey, H. F.; Amendt, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2012-10-15T23:59:59.000Z

235

Self-powered micro-structured solid state neutron detector with very low leakage current and high efficiency  

E-Print Network (OSTI)

Self-powered micro-structured solid state neutron detector with very low leakage current and high helps to reduce the gammas sensitivity. The neutron detec- tion efficiency of such detectors mainly, fabrication, and performance of solid-state neutron detector based on three-dimensional honeycomb-like silicon

Danon, Yaron

236

Education | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Education banner Education banner Sunil Sinha A Chat with Sunil Sinha, Distinguished Professor of Physics at the University of California-San Diego and speaker at the recent CNMS-SNS Research Forum more... The purpose of the Spallation Neutron Source and the High Flux Isotope Reactor is to facilitate neutron scattering as an integral tool for scientific research and technological development across many scientific and engineering domains within the scientific, academic,and industrial communities. Coupled with this role is a recognized need to inspire, educate, and facilitate the next generation of users and hence foster enhanced use of the unique neutron scattering facilities at ORNL. This is the central theme of the education activities within the Neutron Sciences Directorate (NScD).

237

Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection.  

SciTech Connect

An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making these neutron measurements in the high bremsstrahlung and electrical noise environments found in High Energy Density Physics experiments and especially on the very high noise environment generated on the fast pulsed power experiments performed here at Sandia. This same system may dramatically improve active WMD and contraband detection as well when employed with ultrafast (10-50 ns) pulsed neutron sources.

Martin, Shawn Bryan; Derzon, Mark Steven; Renzi, Ronald F.; Chandler, Gordon Andrew

2007-12-01T23:59:59.000Z

238

Commissioning of the Korean High Heat Flux Test Facility by Using Electron Beam System for Plasma Facing Components  

Science Journals Connector (OSTI)

Divertor and High-Heat-Flux Components / Proceedings of the Twentieth Topical Meeting on the Technology of Fusion Energy (TOFE-2012) (Part 1), Nashville, Tennessee, August 27-31, 2012

Suk-Kwon Kim; Eo Hwak Lee; Jae-Sung Yoon; Dong Won Lee; Duck-Hoi Kim; Seungyon Cho

239

OPTIMIZATION AND DESIGN GUIDELINES FOR HIGH FLUX MICRO-CHANNEL HEAT SINKS FOR LIQUID AND GASEOUS SINGLE-PHASE FLOW  

E-Print Network (OSTI)

orders of magnitude, especially for high heat flux devices. Using water and air as coolants, designs with the optimization tool are generalized and optimum configurations are illustrated on design charts. Physical trends

Müller, Norbert

240

TYPE A VERIFICATION FOR THE HIGH FLUX BEAM REACTOR UNDERGROUND UTILITIES REMOVAL PHASE 2 DF WASTE LINE REMOVAL, BNL  

SciTech Connect

5098-SR-02-0 PROJECT-SPECIFIC TYPE A VERIFICATION FOR THE HIGH FLUX BEAM REACTOR UNDERGROUND UTILITIES REMOVAL PHASE 2 DF WASTE LINE REMOVAL, BROOKHAVEN NATIONAL LABORATORY

P.C. Weaver

2010-07-09T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

High energy electron fluxes in dc-augmented capacitively coupled plasmas I. Fundamental characteristics  

SciTech Connect

Power deposition from electrons in capacitively coupled plasmas (CCPs) has components from stochastic heating, Joule heating, and from the acceleration of secondary electrons through sheaths produced by ion, electron, or photon bombardment of electrodes. The sheath accelerated electrons can produce high energy beams which, in addition to producing excitation and ionization in the gas can penetrate through the plasma and be incident on the opposite electrode. In the use of CCPs for microelectronics fabrication, there may be an advantage to having these high energy electrons interact with the wafer. To control the energy and increase the flux of the high energy electrons, a dc bias can be externally imposed on the electrode opposite the wafer, thereby producing a dc-augmented CCP (dc-CCP). In this paper, the characteristics of dc-CCPs will be discussed using results from a computational study. We found that for a given rf bias power, beams of high energy electrons having a narrow angular spread (<1 deg. ) can be produced incident on the wafer. The maximum energy in the high energy electron flux scales as {epsilon}{sub max}=-V{sub dc}+V{sub rf}+V{sub rf0}, for a voltage on the dc electrode of V{sub dc}, rf voltage of V{sub rf}, and dc bias on the rf electrode of V{sub rf0}. The dc current from the biased electrode must return to ground through surfaces other than the rf electrode and so seeks out a ground plane, typically the side walls. If the side wall is coated with a poorly conducting polymer, the surface will charge to drive the dc current through.

Wang Mingmei [Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa 50010 (United States); Kushner, Mark J. [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States)

2010-01-15T23:59:59.000Z

242

High-pressure cell for neutron reflectometry of supercritical and subcritical fluids at solid interfaces  

SciTech Connect

A new high-pressure cell design for use in neutron reflectometry (NR) for pressures up to 50 MPa and a temperature range of 300 473 K is described. The cell design guides the neutron beam through the working crystal without passing through additional windows or the bulk fluid, which provides for a high neutron transmission, low scattering background, and low beam distortion. The o-ring seal is suitable for a wide range of subcritical and supercritical fluids and ensures high chemical and pressure stability. Wafers with a diameter of 5.08 cm (2 in.) and 5 mm or 10 mm thickness can be used with the cells, depending on the required pressure and momentum transfer range. The fluid volume in the sample cell is very small at about 0.1 ml, which minimizes scattering background and stored energy. The cell design and pressure setup for measurements with supercritical fluids are described. NR data are shown for silicon/silicon oxide and quartz wafers measured against air and subsequently within the high-pressure cell to demonstrate the neutron characteristics of the high-pressure cell. Neutron reflectivity data for supercritical CO2 in contact with quartz and Si/SiO2 wafers are also shown.

Carmichael, Justin R [ORNL; Rother, Gernot [ORNL; Browning, Jim [ORNL; Ankner, John Francis [ORNL; Banuelos, Jose Leo [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Wesolowski, David J [ORNL; Cole, David [Ohio State University

2012-01-01T23:59:59.000Z

243

Establishing Specifications for Low Enriched Uranium Fuel Operations Conducted Outside the High Flux Isotope Reactor Site  

SciTech Connect

The National Nuclear Security Administration (NNSA) has funded staff at Oak Ridge National Laboratory (ORNL) to study the conversion of the High Flux Isotope Reactor (HFIR) from the current, high enriched uranium fuel to low enriched uranium fuel. The LEU fuel form is a metal alloy that has never been used in HFIR or any HFIR-like reactor. This report provides documentation of a process for the creation of a fuel specification that will meet all applicable regulations and guidelines to which UT-Battelle, LLC (UTB) the operating contractor for ORNL - must adhere. This process will allow UTB to purchase LEU fuel for HFIR and be assured of the quality of the fuel being procured.

Pinkston, Daniel [ORNL; Primm, Trent [ORNL; Renfro, David G [ORNL; Sease, John D [ORNL

2010-10-01T23:59:59.000Z

244

High-Efficiency Resonant RF Spin Rotator with Broad Phase Space Acceptance for Pulsed Polarized Cold Neutron Beams  

E-Print Network (OSTI)

We have developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5 cm x 9.5 cm pulsed cold neutron beam with high efficiency over a broad cold neutron energy range. The effect of the spin reversal by the rotator on the neutron beam phase space is compared qualitatively to RF neutron spin flippers based on adiabatic fast passage. The spin rotator does not change the kinetic energy of the neutrons and leaves the neutron beam phase space unchanged to high precision. We discuss the design of the spin rotator and describe two types of transmission-based neutron spin-flip efficiency measurements where the neutron beam was both polarized and analyzed by optically-polarized 3He neutron spin filters. The efficiency of the spin rotator was measured to be 98.0+/-0.8% on resonance for neutron energies from 3.3 to 18.4 meV over the full phase space of the beam. As an example of the application of this device to an experiment we describe the integration of the RF spin rotator into an apparatus to search for the small parity-violating asymmetry A_gamma in polarized cold neutron capture on para-hydrogen by the NPDGamma collaboration at LANSCE.

P. -N. Seo; L. Barron-Palos; J. D. Bowman; T. E. Chupp; C. Crawford; M. Dabaghyan; M. Dawkins; S. J. Freedman; T. Gentile; M. T. Gericke; R. C. Gillis; G. L. Greene; F. W. Hersman; G. L. Jones; M. Kandes; S. Lamoreaux; B. Lauss; M. B. Leuschner; R. Mahurin; M. Mason; J. Mei; G. S. Mitchell; H. Nann; S. A. Page; S. I. Penttila; W. D. Ramsay; A. Salas Bacci; S. Santra; M. Sharma; T. B. Smith; W. M. Snow; W. S. Wilburn; H. Zhu

2007-10-15T23:59:59.000Z

245

Neutrons - 88-Inch Cyclotron  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutrons Neutron beams are available at the 88-Inch Cyclotron. Available energies range of from 8 to 30 MeV, with fluxes of up to 1E8 neutronscm2sec. For more information,...

246

Constraints on the flux of Ultra-High Energy neutrinos from WSRT observations  

SciTech Connect

Context. Ultra-high energy (UHE) neutrinos and cosmic rays initiate particle cascades underneath theMoon?s surface. These cascades have a negative charge excess and radiate Cherenkov radio emission in a process known as the Askaryan effect. The optimal frequencywindow for observation of these pulses with radio telescopes on the Earth is around 150 MHz. Aims. By observing the Moon with the Westerbork Synthesis Radio Telescope array we are able to set a new limit on the UHEneutrino flux. Methods. The PuMa II backend is used to monitor the Moon in 4 frequency bands between 113 and 175 MHz with a samplingfrequency of 40 MHz. The narrowband radio interference is digitally filtered out and the dispersive effect of the Earth?s ionosphere is compensated for. A trigger system is implemented to search for short pulses. By inserting simulated pulses in the raw data, thedetection efficiency for pulses of various strength is calculated. Results. With 47.6 hours of observation time, we are able to set a limit onthe UHE neutrino flux. This new limit is an order of magnitude lower than existing limits. In the near future, the digital radio array LOFAR will be used to achieve an even lower limit.

Scholten, O.; Bacelar, J.; Braun, R.; de Bruyn, A.G.; Falcke, H.; Singh, K.; Stappers, B.; Strom, R.G.; al Yahyaoui, R.

2010-04-02T23:59:59.000Z

247

Divertor Heat Flux Mitigation in High-Performance H-mode Plasmas in the National Spherical Torus Experiment.  

SciTech Connect

Experiments conducted in high-performance 1.0-1.2 MA 6 MW NBI-heated H-mode plasmas with a high flux expansion radiative divertor in NSTX demonstrate that significant divertor peak heat flux reduction and access to detachment may be facilitated naturally in a highly-shaped spherical torus (ST) configuration. Improved plasma performance with high {beta}{sub p} = 15-25%, a high bootstrap current fraction f{sub BS} = 45-50%, longer plasma pulses, and an H-mode regime with smaller ELMs has been achieved in the lower single null configuration with higher-end elongation 2.2-2.4 and triangularity 0.6-0.8. Divertor peak heat fluxes were reduced from 6-12 MW/m{sup 2} to 0.5-2 MW/m{sup 2} in ELMy H-mode discharges using high magnetic flux expansion and partial detachment of the outer strike point at several D{sub 2} injection rates, while good core confinement and pedestal characteristics were maintained. The partially detached divertor regime was characterized by a 30-60% increase in divertor plasma radiation, a peak heat flux reduction by up to 70%, measured in a 10 cm radial zone, a five-fold increase in divertor neutral pressure, and a significant volume recombination rate increase.

Soukhanovskii, V A; Maingi, R; Gates, D; Menard, J; Paul, S F; Raman, R; Roquemore, A L; Bell, R E; Bush, C; Kaita, R

2008-09-22T23:59:59.000Z

248

Research Highlights | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

phase behavior in carbon pores phase behavior in carbon pores Neutrons measure phase behavior in pores at angstrom size Compelling new methods for assessing carbon pores for hydrogen storage in fuel cells Research Contact: Yuri Melnichenko Jan. 2012, Written by Agatha Bardoel Yuri Melnichenko and Lilin He GP-SANS instrument scientist Yuri Melnichenko (left) and postdoctoral associate Lilin He. Researchers have measured the phase behavior of green house gases in pores at the angstrom level, using small-angle neutron scattering (SANS) at the Oak Ridge National Laboratory's High Flux Isotope Reactor. Yuri Melnichenko, an instrument scientist on the General-Purpose Small-Angle Neutron Scattering (GP-SANS) Diffractometer at ORNL's High Flux Isotope Reactor, his postdoctoral associate Lilin He and collaborators

249

Preliminary Notice of Violation - High Flux Isotope Reactor, November 18, 2003  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Department of Energy Department of Energy Washington, DC 20585 November 18, 2003 Dr. Jeffrey Wadsworth [ ] UT-Battelle P.O. Box 2008 Oak Ridge, TN 37831-6255 EA 2003-10 Subject: Preliminary Notice of Violation and Proposed Imposition of Civil Penalty $151,250 Dear Dr. Wadsworth: This letter refers to the Department of Energy's Office of Price-Anderson Enforcement (OE) investigation of the facts and circumstances surrounding nuclear safety work control issues at the High Flux Isotope Reactor (HFIR) and the Radiochemical Engineering Development Center (REDC). Our office initiated this investigation in response to a manual reactor shutdown due to a control cylinder maintenance safety deficiency and operation of a radiological [ ] without required containment, as

250

Investigating the use of nanofluids to improve high heat flux cooling systems  

E-Print Network (OSTI)

The thermal performance of high heat flux components in a fusion reactor could be enhanced significantly by the use of nanofluid coolants, suspensions of a liquid with low concentrations of solid nanoparticles. However, before they are considered viable for fusion, the long-term behaviour of nanofluids must be investigated. This paper reports an experiment which is being prepared to provide data on nanofluid stability, settling and erosion in a HyperVapotron device. Procedures are demonstrated for nanofluid synthesis and quality assessment, and the fluid sample analysis methods are described. The end results from this long-running experiment are expected to allow an initial assessment of the suitability of nanofluids as coolants in a fusion reactor.

Barrett, T R; Flinders, K; Sergis, A; Hardalupas, Y

2013-01-01T23:59:59.000Z

251

Large break loss-of-coolant accident analyses for the high flux isotope reactor  

SciTech Connect

The US Department of Energy's High Flux Isotope Reactor (HFIR) was analyzed to evaluate it's response to a spectrum of loss-of-coolant accidents (LOCAs) with potential for leading to core damage. The MELCOR severe accident analysis code (version 1.7.1) was used to evaluate the overall dynamic response of HFIR. Before conducting LOCA analyses, the steady-state thermal-hydraulic parameters evaluated by MELCOR for various loop sections were verified against steady-state operating data. Thereafter, HFIR depressurization tests were simulated to evaluate the system pressure change for a given depletion in coolant inventory. Interesting and important safety-related phenomena were observed. The current analyses (which should be considered preliminary) that occur over a period from 1 to 3 seconds do not lead to core wide fuel melting. Core fluid flashing during the initial rapid depressurization does cause fuel temperature excursions due to adiabatic-like heatup. 3 refs., 4 figs.

Taleyarkhan, R.P. (Oak Ridge National Lab., TN (USA))

1989-01-01T23:59:59.000Z

252

High-resolution spectroscopy used to measure inertial confinement fusion neutron spectra on Omega (invited)  

SciTech Connect

The areal density ({rho}R) of cryogenic DT implosions on Omega is inferred by measuring the spectrum of neutrons that elastically scatter off the dense deuterium (D) and tritium (T) fuel. Neutron time-of-flight (nTOF) techniques are used to measure the energy spectrum with high resolution. High signal-to-background data has been recorded on cryogenic DT implosions using a well-collimated 13.4-m line of sight and an nTOF detector with an advanced liquid scintillator compound. An innovative method to analyze the elastically scattered neutron spectra was developed using well-known cross sections of the DT nuclear reactions. The estimated areal densities are consistent with alternative {rho}R measurements and 1-D simulations.

Forrest, C. J.; Radha, P. B.; Glebov, V. Yu.; Goncharov, V. N.; Knauer, J. P.; Pruyne, A.; Romanofsky, M.; Sangster, T. C.; Shoup, M. J. III; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States); Casey, D. T.; Gatu-Johnson, M. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States); Gardner, S. [Constellation Energy Nuclear Group, Ontario, New York 14519 (United States)

2012-10-15T23:59:59.000Z

253

New High Field Magnet for Neutron Scattering at Hahn-Meitner Institute  

E-Print Network (OSTI)

Abstract. The Berlin Neutron Scattering Center BENSC at the Hahn-Meitner-Institute (HMI) is a user facility for the study of structure and dynamics of condensed matter with neutrons and synchrotron radiation with special emphasis on experiments under extreme conditions. Neutron scattering is uniquely suited to study magnetic properties on a microscopic length scale, because neutrons have comparable wavelengths and, due to their magnetic moment, they interact with the atomic magnetic moments. Magnetic interactions and magnetic phenomena depend on thermodynamic parameters like magnetic field, temperature and pressure. At HMI special efforts are being made to offer outstanding sample environments such as very low temperatures or high magnetic fields or combination of both. For the future a dedicated instrument for neutron scattering at extreme fields is under construction, the Extreme Environment Diffractometer ExED. For this instrument the existing superconducting magnets as well as a future hybrid system can be used. The highest fields, above 30 T will be produced by the planned series-connected hybrid magnet system, designed and constructed in collaboration with the National High Magnetic Field Laboratory, Tallahassee, FL. 1.

M Steiner; D A Tennant; P Smeibidl

254

Measurement of the Flux of Ultrahigh Energy Cosmic Rays from Monocular Observations by the High Resolution Fly's Eye  

E-Print Network (OSTI)

of Physics and Nevis Laboratory, New York, New York, USA 6) University of New Mexico, Department of PhysicsMeasurement of the Flux of Ultrahigh Energy Cosmic Rays from Monocular Observations by the High of Utah, Department of Physics and High Energy Astrophysics Institute, Salt Lake City, Utah, USA 2

255

Positron emission tomography-based boron neutron capture therapy using boronophenylalanine for high-grade gliomas: part I.  

Science Journals Connector (OSTI)

...for high-grade gliomas: part I Determination of tumor boron-10 (10B) levels is required for accurate neutron dosimetry...high-grade gliomas: part I. | Determination of tumor boron-10 (10B) levels is required for accurate neutron dosimetry...

Y Imahori; S Ueda; Y Ohmori; K Sakae; T Kusuki; T Kobayashi; M Takagaki; K Ono; T Ido; R Fujii

1998-08-01T23:59:59.000Z

256

Prospects For High Frequency Burst Searches Following Binary Neutron Star Coalescence With Advanced Gravitational Wave Detectors  

E-Print Network (OSTI)

The equation of state plays a critical role in the physics of the merger of two neutron stars. Recent numerical simulations with microphysical equation of state suggest the outcome of such events depends on the mass of the neutron stars. For less massive systems, simulations favor the formation of a hypermassive, quasi-stable neutron star, whose oscillations produce a short, high frequency burst of gravitational radiation. Its dominant frequency content is tightly correlated with the radius of the neutron star, and its measurement can be used to constrain the supranuclear equation of state. In contrast, the merger of higher mass systems results in prompt gravitational collapse to a black hole. We have developed an algorithm which combines waveform reconstruction from a morphology-independent search for gravitational wave transients with Bayesian model selection, to discriminate between post-merger scenarios and accurately measure the dominant oscillation frequency. We demonstrate the efficacy of the method using a catalogue of simulated binary merger signals in data from LIGO and Virgo, and we discuss the prospects for this analysis in advanced ground-based gravitational wave detectors. From the waveforms considered in this work and assuming an optimally oriented source, we find that the post-merger neutron star signal may be detectable by this technique to $\\sim 10\\text{--}25$\\,Mpc. We also find that we successfully discriminate between the post-merger scenarios with $\\sim 95\\%$ accuracy and determine the dominant oscillation frequency of surviving post-merger neutron stars to within $\\sim 10$\\,Hz, averaged over all detected signals. This leads to an uncertainty in the estimated radius of a non-rotating 1.6\\,M$_{\\odot}$ reference neutron star of $\\sim 100\\,$m.

J. Clark; A. Bauswein; L. Cadonati; H. -T. Janka; C. Pankow; N. Stergioulas

2014-06-20T23:59:59.000Z

257

Mammary Neoplasia in the Rat following High-Energy Neutron Irradiation  

Science Journals Connector (OSTI)

...traversed by more than 1 secondary par tide, generally a proton. At the doses of...constant over a wide range of neutron energies. The value of b would vary depending upon the relative proportion of high linear-energy-transfer radiation pen unit of dose...

James L. Montour; Richard C. Hard, Jr.; and Roger E. Flora

1977-08-01T23:59:59.000Z

258

Embrittlement of Stainless Steels and Nickel-Based Alloys at High Temperature Induced by Neutron Radiation  

Science Journals Connector (OSTI)

... not recovered15. Thus, the precipitation effects are not the prime cause of the embrittlement.Boron-10 appeared the most likely isotope because of its high thermal neutron cross-section. Rather ... metallurgical changes induced) a constant amount of boron was added in the form of either boron-10 or boron-11. Irradiation of these chemically and metallurgically similar steels clearly showed that ...

R. S. BARNES

1965-06-26T23:59:59.000Z

259

Fast neutron thermionic-converters for high-power space nuclear power systems. [Na; K  

SciTech Connect

The results of tests with a thermionic reactor-converter utilizing fast neutrons and a high temperature cooling system are described. The reactor can be useful for a wide range of applications with a specific mass of about 20 kg/kW and power level of 2500 kW. (AIP)

Pupko, V.Y.; Vizgalov, A.V.; Raskach, F.P.; Shestjorkin, A.G.; Almambetov, A.K. (Obninsk, Kaluga region, USSR (SU)); Bystrov, P.I.; Yuditsky, V.D.; Sobolev, Y.A.; Sinyavsky, V.V.; Bakanov, Y.A.; Lipovy, N.M. (SIA Energiya'', Kaliningrad, Moscow (USSR)); Gryaznov, G.M.; Serbin, V.I.; Trykhanov, Y.L. (SIA Krasnaya Zvezda'', Moscow (USSR))

1991-01-05T23:59:59.000Z

260

High-voltage supply for neutron tubes in well-logging applications  

DOE Patents (OSTI)

A high voltage supply is provided for a neutron tube used in well logging. The biased pulse supply of the invention combines DC and full pulse techniques and produces a target voltage comprising a substantial negative DC bias component on which is superimposed a pulse whose negative peak provides the desired negative voltage level for the neutron tube. The target voltage is preferably generated using voltage doubling techniques and employing a voltage source which generates bipolar pulse pairs having an amplitude corresponding to the DC bias level.

Humphreys, D.R.

1982-09-15T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Note: Versatile sample stick for neutron scattering experiments in high electric fields  

SciTech Connect

We present a versatile high voltage sample stick that fits into all cryomagnets and standard cryostats at the Swiss Spallation Neutron Source, Paul Scherrer Institut, and which provides a low effort route to neutron scattering experiments that combine electric field with low temperature and magnetic field. The stick allows for voltages up to 5 kV and can be easily adapted for different scattering geometries. We discuss the design consideration and thermal behavior of the stick, and give one example to showcase the abilities of the device.

Bartkowiak, M., E-mail: marek.bartkowiak@psi.ch [Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); White, J. S. [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen (Switzerland) [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Laboratory for Quantum Magnetism, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Rønnow, H. M.; Prša, K. [Laboratory for Quantum Magnetism, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)] [Laboratory for Quantum Magnetism, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

2014-02-15T23:59:59.000Z

262

Probing spin frustration in high-symmetry magnetic nanomolecules by inelastic neutron scattering  

Science Journals Connector (OSTI)

Low temperature inelastic neutron scattering studies have been performed to characterize the low energy magnetic excitation spectrum of the magnetic nanomolecule {Mo72Fe30}. This unique highly symmetric cluster features spin frustration and is one of the largest discrete magnetic molecules studied to date by inelastic neutron scattering. The 30s=5?2 FeIII ions, embedded in a spherical polyoxomolybdate molecule, occupy the vertices of an icosidodecahedron and are coupled via nearest-neighbor antiferromagnetic interactions. The overall energy scale of the excitation and the gross features of the temperature dependence of the observed neutron scattering are explained by a quantum model of the frustrated spin cluster. However, no satisfactory theoretical explanation is yet available for the observed magnetic field dependence.

V. O. Garlea; S. E. Nagler; J. L. Zarestky; C. Stassis; D. Vaknin; P. Kögerler; D. F. McMorrow; C. Niedermayer; D. A. Tennant; B. Lake; Y. Qiu; M. Exler; J. Schnack; M. Luban

2006-01-23T23:59:59.000Z

263

Extraction of gadolinium from high flux isotope reactor control plates. [Alternative method  

SciTech Connect

Gadolinium-153 is an important radioisotope used in the diagnosis of various bone disorders. Recent medical and technical developments in the detection and cure of osteoporosis, a bone disease affecting an estimated 50 million people, have greatly increased the demand for this isotope. The Oak Ridge National Laboratory (ORNL) has produced /sup 153/Gd since 1980 primarily through the irradiation of a natural europium-oxide powder followed by the chemical separation of the gadolinium fraction from the europium material. Due to the higher demand for /sup 153/Gd, an alternative production method to supplement this process has been investigated. This process involves the extraction of gadolinium from the europium-bearing region of highly radioactive, spent control plates used at the High Flux Isotope Reactor (HFIR) with a subsequent re-irradiation of the extracted material for the production of the /sup 153/Gd. Based on the results of experimental and calculational analyses, up to 25 grams of valuable gadolinium (greater than or equal to60% enriched in /sup 152/Gd) resides in the europium-bearing region of the HFIR control components of which 70% is recoverable. At a specific activity yield of 40 curies of /sup 153/Gd for each gram of gadolinium re-irradiated, 700 one-curie sources can be produced from each control plate assayed.

Kohring, M.W.

1987-04-01T23:59:59.000Z

264

Optimizing Laser-accelerated Ion Beams for a Collimated Neutron Source  

SciTech Connect

High-flux neutrons for imaging and materials analysis applications have typically been provided by accelerator- and reactor-based neutron sources. A novel approach is to use ultraintense (>1018W/cm2) lasers to generate picosecond, collimated neutrons from a dual target configuration. In this article, the production capabilities of present and upcoming laser facilities are estimated while independently maximizing neutron yields and minimizing beam divergence. A Monte-Carlo code calculates angular and energy distributions of neutrons generated by D-D fusion events occurring within a deuterated target for a given incident beam of D+ ions. Tailoring of the incident distribution via laser parameters and microlens focusing modifies the emerging neutrons. Projected neutron yields and distributions are compared to conventional sources, yielding comparable on-target fluxes per discharge, shorter time resolution, larger neutron energies and greater collimation.

C.L. Ellison and J. Fuchs

2010-09-23T23:59:59.000Z

265

Properties of a Cold-Neutron Irradiation Facility for In Vitro Research on Boron Neutron Capture Therapy at the Geesthacht Neutron Facility  

SciTech Connect

A new irradiation facility, GBET (basic research on boron neutron capture therapy), especially designed for in vitro experiments on boron neutron capture therapy was put into operation at the Geesthacht Neutron Facility of the GKSS Research Center. Its location at a cold-neutron guide without direct view of the reactor core has two advantages: First, contamination of the primary beam with fast neutrons or photons is negligible. Second, GBET yields a high cold-neutron flux of 1.4 x 10{sup 8}/(cm{sup 2}.s) over an area of 3 x 4 cm. As a result of the energy dependence of the neutron absorption cross section of boron, this corresponds to a higher effective thermal flux of 4.7 x 10{sup 8}/(cm{sup 2}.s). This effect is used to reduce the irradiation times by a factor of 3.32.The effective flux is sufficient for irradiation of thin samples like cell monolayers in conventional culture flasks. For such in vitro irradiations, a survival fraction of 1% is achieved at a homogeneous boron concentration of 100 ppm {sup 10}B within {approx}20 min. Furthermore, the beam can be used for boron radiography. The respective experimental conditions are discussed, especially the neutron flux distribution, available for these different types of samples.

Luedemann, L. [Institut fur Werkstofforschung, GKSS-Forschungszentrum Geesthacht (Germany); Kampmann, R. [Institut fur Werkstofforschung, GKSS-Forschungszentrum Geesthacht (Germany); Sosaat, W. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Staron, P. [Institut fur Werkstofforschung, GKSS-Forschungszentrum Geesthacht (Germany); Wille, P. [Institut fur Werkstofforschung, GKSS-Forschungszentrum Geesthacht (Germany)

2000-05-15T23:59:59.000Z

266

Facility for high heat flux testing of irradiated fusion materials and components using infrared plasma arc lamps  

SciTech Connect

A new high-heat flux testing facility using water-wall stabilized high-power high-pressure argon Plasma Arc Lamps (PALs) has been developed for fusion applications. It can handle irradiated plasma facing component materials and mock-up divertor components. Two PALs currently available at ORNL can provide maximum incident heat fluxes of 4.2 and 27 MW/m2 over a heated area of 9x12 and 1x10 cm2, respectively, which are fusion-prototypical steady state heat flux conditions. The facility will be described and the main differences between the photon-based high-heat flux testing facilities, such as PALs, and the e-beam and particle beam facilities more commonly used for fusion HHF testing are discussed. The components of the test chamber were designed to accommodate radiation safety and materials compatibility requirements posed by high-temperature exposure of low levels irradiated tungsten articles. Issues related to the operation and temperature measurements during testing are presented and discussed.

Sabau, Adrian S [ORNL] [ORNL; Ohriner, Evan Keith [ORNL] [ORNL; Kiggans, Jim [ORNL] [ORNL; Harper, David C [ORNL] [ORNL; Snead, Lance Lewis [ORNL] [ORNL; Schaich, Charles Ross [ORNL] [ORNL

2014-01-01T23:59:59.000Z

267

Redirecting carbon flux through exogenous pyruvate kinase to achieve high ethanol yields in Clostridium thermocellum  

NLE Websites -- All DOE Office Websites (Extended Search)

Redirecting Redirecting carbon flux through exogenous pyruvate kinase to achieve high ethanol yields in Clostridium thermocellum Yu Deng a,c , Daniel G. Olson a,c , Jilai Zhou a,c , Christopher D. Herring a,b,c , A. Joe Shaw d , Lee R. Lynd a,b,c,n a Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA b Mascoma Corporation, Lebanon, NH 03766, USA c BioEnergy Science Center, Oak Ridge, TN 37830, USA d Novogy, Inc. Cambridge, MA 02138, USA a r t i c l e i n f o Article history: Received 24 August 2012 Received in revised form 6 November 2012 Accepted 16 November 2012 Available online 29 November 2012 Keywords: Clostridium thermocellum Ethanol yield Pyruvate kinase Malate shunt a b s t r a c t In Clostridium thermocellum, a thermophilic anaerobic bacterium able to rapidly ferment cellulose to ethanol, pyruvate kinase (EC 2.7.1.40) is absent based on both the genome sequence and enzymatic

268

Tritium trapping in silicon carbide in contact with solid breeder under high flux isotope reactor irradiation  

SciTech Connect

The trapping of tritium in silicon carbide (SiC) injected from ceramic breeding materials was examined via tritium measurements using imaging plate (IP) techniques. Monolithic SiC in contact with ternary lithium oxide (lithium titanate and lithium aluminate) as a ceramic breeder was irradiated in the High Flux Isotope Reactor (HFIR) in Oak Ridge, Tennessee, USA. The distribution of photo-stimulated luminescence (PSL) of tritium in SiC was successfully obtained, which separated the contribution of 14C ß-rays to the PSL. The tritium incident from ceramic breeders was retained in the vicinity of the SiC surface even after irradiation at 1073 K over the duration of ~3000 h, while trapping of tritium was not observed in the bulk region. The PSL intensity near the SiC surface in contact with lithium titanate was higher than that obtained with lithium aluminate. The amount of the incident tritium and/or the formation of a Li2SiO3 phase on SiC due to the reaction with lithium aluminate under irradiation likely were responsible for this observation.

H. Katsui; Y. Katoh; A. Hasegawa; M. Shimada; Y. Hatano; T. Hinoki; S. Nogami; T. Tanaka; S. Nagata; T. Shikama

2013-11-01T23:59:59.000Z

269

On RELAP5-simulated High Flux Isotope Reactor reactivity transients: Code change and application  

SciTech Connect

This paper presents a new and innovative application for the RELAP5 code (hereafter referred to as the code''). The code has been used to simulate several transients associated with the (presently) draft version of the High-Flux Isotope Reactor (HFIR) updated safety analysis report (SAR). This paper investigates those thermal-hydraulic transients induced by nuclear reactivity changes. A major goal of the work was to use an existing RELAP5 HFIR model for consistency with other thermal-hydraulic transient analyses of the SAR. To achieve this goal, it was necessary to incorporate a new self-contained point kinetics solver into the code because of a deficiency in the point-kinetics reactivity model of the Mod 2.5 version of the code. The model was benchmarked against previously analyzed (known) transients. Given this new code, four event categories defined by the HFIR probabilistic risk assessment (PRA) were analyzed: (in ascending order of severity) a cold-loop pump start; run-away shim-regulating control cylinder and safety plate withdrawal; control cylinder ejection; and generation of an optimum void in the target region. All transients are discussed. Results of the bounding incredible event transient, the target region optimum void, are shown. Future plans for RELAP5 HFIR applications and recommendations for code improvements are also discussed.

Freels, J.D.

1993-01-01T23:59:59.000Z

270

On RELAP5-simulated High Flux Isotope Reactor reactivity transients: Code change and application  

SciTech Connect

This paper presents a new and innovative application for the RELAP5 code (hereafter referred to as ``the code``). The code has been used to simulate several transients associated with the (presently) draft version of the High-Flux Isotope Reactor (HFIR) updated safety analysis report (SAR). This paper investigates those thermal-hydraulic transients induced by nuclear reactivity changes. A major goal of the work was to use an existing RELAP5 HFIR model for consistency with other thermal-hydraulic transient analyses of the SAR. To achieve this goal, it was necessary to incorporate a new self-contained point kinetics solver into the code because of a deficiency in the point-kinetics reactivity model of the Mod 2.5 version of the code. The model was benchmarked against previously analyzed (known) transients. Given this new code, four event categories defined by the HFIR probabilistic risk assessment (PRA) were analyzed: (in ascending order of severity) a cold-loop pump start; run-away shim-regulating control cylinder and safety plate withdrawal; control cylinder ejection; and generation of an optimum void in the target region. All transients are discussed. Results of the bounding incredible event transient, the target region optimum void, are shown. Future plans for RELAP5 HFIR applications and recommendations for code improvements are also discussed.

Freels, J.D.

1993-07-01T23:59:59.000Z

271

Facility for high-heat flux testing of irradiated fusion materials and components using infrared plasma arc lamps  

Science Journals Connector (OSTI)

A new high-heat flux testing (HHFT) facility using water-wall stabilized high-power high-pressure argon plasma arc lamps (PALs) has been developed for fusion applications. It can accommodate irradiated plasma facing component materials and sub-size mock-up divertor components. Two PALs currently available at Oak Ridge National Laboratory can provide maximum incident heat fluxes of 4.2 and 27 MW m?2, which are prototypic of fusion steady state heat flux conditions, over a heated area of 9 ? 12 and 1 ? 10 cm2, respectively. The use of PAL permits the heat source to be environmentally separated from the components of the test chamber, simplifying the design to accommodate safe testing of low-level irradiated articles and materials under high-heat flux. Issues related to the operation and temperature measurements during testing of tungsten samples are presented and discussed. The relative advantages and disadvantages of this photon-based HHFT facility are compared to existing e-beam and particle beam facilities used for similar purposes.

Adrian S Sabau; Evan K Ohriner; Jim Kiggans; David C Harper; Lance L Snead; Charles R Schaich

2014-01-01T23:59:59.000Z

272

High-Latitude Ocean and Sea Ice Surface Fluxes: Requirements and Challenges for Climate Mark Bourassa1  

E-Print Network (OSTI)

temperatures, seasonal sea ice, and the remoteness of the regions all conspire to make observations difficult latitudes - the vertical exchanges of heat, momentum and material between the ocean, atmosphere and ice1 High-Latitude Ocean and Sea Ice Surface Fluxes: Requirements and Challenges for Climate Research

Gille, Sarah T.

273

Effect to the High Flux Isotope Reactor by the nearby heavy load drop  

SciTech Connect

In this calculation, GE-2000 cask of 25,000 lbs is assumed to drop from a height of 20-ft above the bottom of the High Flux Isotope Reactor (HFIR) pool slab with end velocity of 430 in/sec at the loading station. The consequences of the dynamic impact to the bottom slab of the pool and to the nearby HFIR reactor vessel are analyzed by applying ABAQUS computer code. The results show that both HFIR vessel structure and its supporting legs are subjected to elastic disturbances only and will not be damaged. The bottom slab of the pool will be damaged. The plastic strain that will cause failure to the concrete slab at the point of impact extends a distance approximately half of the slab thickness of 36 inches. The plastic strain of failure for concrete is assumed to be 0.45%. The velocity response spectrum at the concrete slab next to HFIR vessel as a result of the impact is also obtained. The maximum spectral velocity is approximately 10 in/sec. It is approximately equal to the maximum magnitude of the Oak Ridge velocity spectrum formulated recently with 0.26g peak ground acceleration and 5% damping. However, the peak ground acceleration that is associated with the impact generated response spectrum curve can be as much as 20g. The high frequency acceleration waves are generated in impact problems. It is concluded that the damage caused by heavy load drop at loading station is controlled by the slab damage. The damage of slab will not be severe enough to cause the leakage of pool water.

Chang, S.J. [Oak Ridge National Lab., TN (United States). Research Reactors Div.

1996-06-01T23:59:59.000Z

274

PROJECT-SPECIFIC TYPE A VERIFICATION FOR THE HIGH FLUX BEAM REACTOR UNDERGROUND UTILITIES REMOVAL PHASE 3 TRENCH 5, BROOKHAVEN NATIONAL LABORATORY UPTON, NEW YORK  

SciTech Connect

5098-SR-04-0 PROJECT-SPECIFIC TYPE A VERIFICATION FOR THE HIGH FLUX BEAM REACTOR UNDERGROUND UTILITIES REMOVAL PHASE 3 TRENCH 5, BROOKHAVEN NATIONAL LABORATORY

P.C. Weaver

2010-11-03T23:59:59.000Z

275

PROJECT-SPECIFIC TYPE A VERIFICATION FOR THE HIGH FLUX BEAM REACTOR UNDERGROUND UTILITIES REMOVAL PHASE 3 TRENCH 1, BROOKHAVEN NATIONAL LABORATORY UPTON, NEW YORK  

SciTech Connect

5098-SR-05-0 PROJECT-SPECIFIC TYPE A VERIFICATION FOR THE HIGH FLUX BEAM REACTOR UNDERGROUND UTILITIES REMOVAL PHASE 3 TRENCH 1 BROOKHAVEN NATIONAL LABORATORY

E.M. Harpenau

2010-12-15T23:59:59.000Z

276

A high-speed data acquisition system to measure low-level current from self-powered flux detectors in CANDU nuclear reactors  

E-Print Network (OSTI)

A high-speed data acquisition system to measure low-level current from self-powered flux detectors in CANDU nuclear reactors

Lawrence, C B

1982-01-01T23:59:59.000Z

277

Temperature effect of the integral flux of cosmic-ray muons at high energies  

Science Journals Connector (OSTI)

The temperature coefficients of the integral fluxes of cosmic-ray muons arriving at sea level vertically and horizontally with energies of 102, 104, and 3 × 106...GeV are calculated. Decays of pions, kaons, and c...

L. V. Volkova

2013-11-01T23:59:59.000Z

278

Two-dimensional position-sensitive gaseous detectors for high-resolution neutron and X-ray diffraction  

Science Journals Connector (OSTI)

Two-dimensional position-sensitive gaseous detectors have been developed at the Geesthacht Neutron Facility (GeNF) for high-resolution...2, 3He/CF4 and Xe/CO2, respectively. One neutron detector is used at the AR...

M. Marmotti; M. Haese-Seiller; R. Kampmann

2002-12-01T23:59:59.000Z

279

Neutron reflecting supermirror structure  

DOE Patents (OSTI)

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.

Wood, J.L.

1992-12-01T23:59:59.000Z

280

Neutron reflecting supermirror structure  

DOE Patents (OSTI)

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.

Wood, James L. (Drayton Plains, MI)

1992-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Relativistic electron flux comparisons at low and high altitudes with fast time resolution and broad spatial coverage  

SciTech Connect

Analyses are presented for the first high-time resolution multisatellite study of the spatial and temporal characteristics of a relativistic electron enhancement event with a rapid onset. Measurements of MeV electrons were made from two low-altitude polar orbiting satellites and three spacecraft at synchronous altitude. The electron fluxes observed by the low-altitude satellites include precipitating electrons in both the bounce and drift loss cones as well as electrons that are stably trapped, whereas the observations at geosynchronous altitude are dominated by the trapped population. The fluxes of >1 MeV electrons at low-satellite altitude over a wide range of L shells tracked very well the fluxes >0.93 MeV at synchronous altitude. 10 refs., 5 figs., 1 tab.

Imhof, W.L.; Gaines, E.E.; McGlennon, J.P. [Lockheed Palo Alto Research Lab., CA (United States)] [and others] [Lockheed Palo Alto Research Lab., CA (United States); and others

1994-09-01T23:59:59.000Z

282

Phonon characteristics of high {Tc} superconductors from neutron Doppler broadening measurements  

SciTech Connect

Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La{sub 2{minus}x}Ba{sub x}CuO{sub 4}. Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phonons carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra.

Trela, W.J.; Kwei, G.H.; Lynn, J.E. [Los Alamos National Lab., NM (United States); Meggers, K. [Univ. of Kiel (Germany)

1994-12-01T23:59:59.000Z

283

Superconducting gamma and fast-neutron spectrometers with high energy resolution  

DOE Patents (OSTI)

Superconducting Gamma-ray and fast-neutron spectrometers with very high energy resolution operated at very low temperatures are provided. The sensor consists of a bulk absorber and a superconducting thermometer weakly coupled to a cold reservoir, and determines the energy of the incident particle from the rise in temperature upon absorption. A superconducting film operated at the transition between its superconducting and its normal state is used as the thermometer, and sensor operation at reservoir temperatures around 0.1 K reduces thermal fluctuations and thus enables very high energy resolution. Depending on the choice of absorber material, the spectrometer can be configured either as a Gamma-spectrometer or as a fast-neutron spectrometer.

Friedrich, Stephan (San Jose, CA); , Niedermayr, Thomas R. (Oakland, CA); Labov, Simon E. (Berkeley, CA)

2008-11-04T23:59:59.000Z

284

Reactivity Accountability Attributed to Reflector Poisons in the High Flux Isotope Reactor  

SciTech Connect

The objective of this study is to develop a methodology to predict the reactivity impact as a function of outage time between cycles of 3He, 6Li, and other poisons in the High Flux Isotope Reactor s (HFIR) beryllium reflector. The reactivity worth at startup of the HFIR has been incorrectly predicted in the past after the reactor has been shut-down for long periods of time. The incorrect prediction was postulated to be due to the erroneous calculation of 3He buildup in the beryllium reflector. It is necessary to develop a better estimate of the start-of-cycle symmetric critical control element positions since if the estimated and actual symmetrical critical control element positions differ by more than $1.55 in reactivity (approximately one-half inch in control element startup position), HFIR is to be shutdown and a technical evaluation is performed to resolve the discrepancy prior to restart. 3He is generated and depleted during operation, but during an outage, the depletion of 3He ceases because it is a stable isotope. 3He is born from the radioactive decay of tritium, and thus the concentration of 3He increases during shutdown. SCALE, specifically the TRITON and CSAS5 control modules including the KENO V.A, COUPLE, and ORIGEN functional modules were utilized in this study. An equation relating the down time (td) to the change in symmetric control element position was generated and validated against measurements for approximately 40 HFIR operating cycles. The newly-derived correlation was shown to improve accuracy of predictions for long periods of down time.

Chandler, David [ORNL; Maldonado, G Ivan [ORNL; Primm, Trent [ORNL

2009-12-01T23:59:59.000Z

285

High resolution neutron imaging of water in the polymer electrolyte fuel cell membrane  

SciTech Connect

Water transport in the ionomeric membrane, typically Nafion{reg_sign}, has profound influence on the performance of the polymer electrolyte fuel cell, in terms of internal resistance and overall water balance. In this work, high resolution neutron imaging of the Nafion{reg_sign} membrane is presented in order to measure water content and through-plane gradients in situ under disparate temperature and humidification conditions.

Mukherjee, Partha P [Los Alamos National Laboratory; Makundan, Rangachary [Los Alamos National Laboratory; Spendelow, Jacob S [Los Alamos National Laboratory; Borup, Rodney L [Los Alamos National Laboratory; Hussey, D S [NIST; Jacobson, D L [NIST; Arif, M [NIST

2009-01-01T23:59:59.000Z

286

Identification of high energy solar particle signals on the Mexico City neutron monitor database  

Science Journals Connector (OSTI)

We performed a search for ground level solar cosmic ray enhancements on the full five minute database of the Mexico City neutron monitor using wavelet filters and two different statistical tests. We present a detailed analysis of the time series of November 2, 1992, where we found a previously unreported increment matching the onset time of the impulsive phase of GLE 54, thus providing evidence of an effective detection of high energy solar cosmic rays.

Bernardo Vargas Cárdenas; José F. Valdés-Galicia

2012-01-01T23:59:59.000Z

287

Crystal structure of highly concentrated, ionic microgel suspensions studied by neutron scattering  

Science Journals Connector (OSTI)

We present a neutron-scattering investigation of the crystal structure formed by pH-sensitive poly(2-vinylpyridine) microgel particles with 5?wt?% of cross-linker. We focus on highly swollen particles and explore concentrations ranging from below close packing to well above close packing, where the particles are forced to shrink and/or interpenetrate. The crystal structure is found to be random hexagonal close packed, similar to the structure typically found in hard-sphere systems.

U. Gasser; B. Sierra-Martin; A. Fernandez-Nieves

2009-05-12T23:59:59.000Z

288

Direct Measurement of Neutron?Neutron Scattering  

Science Journals Connector (OSTI)

In order to resolve long?standing discrepancies in indirect measurements of the neutron?neutron scattering length ann and contribute to solving the problem of the charge symmetry of the nuclear force the collaboration DIANNA (Direct Investigation of ann Association) plans to measure the neutron?neutron scattering cross section ? nn . The key issue of our approach is the use of the through?channel in the Russia reactor YAGUAR with a peak neutron flux of 1018 /cm2/s. The proposed experimental setup is described. Results of calculations are presented to connect ? nn with the nn?collision detector count rate and the neutron flux density in the reactor channel. Measurements of the thermal neutron fields inside polyethylene converters show excellent prospects for the realization of the direct nn?experiment.

E. I. Sharapov; C. D. Bowman; B. E. Crawford; W. I. Furman; C. R. Howell; B. G. Levakov; V. I. Litvin; W. I. Lychagin; A. E. Lyzhin; E. P. Magda; G. E. Mitchell; G. V. Muzichka; G. V. Nekhaev; Yu. V. Safronov; V. N. Shvetsov; S. L. Stephenson; A. V. Strelkov; W. Tornow

2003-01-01T23:59:59.000Z

289

Neutron production from 7Li(d,xn) nuclear fusion reactions driven by high-intensity laser–target interactions  

Science Journals Connector (OSTI)

Numerical simulations of neutron production from deuterium–lithium nuclear fusion reactions have been performed. A set of differential cross sections for the 7Li(d,xn) reaction for incident deuteron energies of up to 50?MeV is assembled. The angular distribution of neutrons from a thick lithium target is simulated and benchmarked against experimental data. Two-stage neutron production from laser–target experiments has been studied as a function of laser intensity and energy. During the first stage a well collimated deuteron beam is generated using a high-intensity ultrashort pulse laser. During the second stage it is transported through a lithium target using a 3D Monte-Carlo ion beam–target deposition model. The neutron yield is estimated to be ~108?neutrons?J?1 laser energy. Some 1010 neutrons can be expected from a ~100?J petawatt-class laser. For incident deuteron energies above 1?MeV the proposed scheme for neutron production from d–Li reactions is superior to that from d–d reactions, producing a collimated beam of neutrons with higher neutron yield.

J Davis; G M Petrov; Tz Petrova; L Willingale; A Maksimchuk; K Krushelnick

2010-01-01T23:59:59.000Z

290

Kaon condensation in neutron stars and high density behaviour of nuclear symmetry energy  

E-Print Network (OSTI)

We study the influence of a high density behaviour of the nuclear symmetry energy on a kaon condensation in neutron stars. We find that the symmetry energy typical for several realistic nuclear potentials, which decreases at high densities, inhibits kaon condensation for weaker kaon-nucleon couplings. There exists a threshold coupling above which the kaon condensate forms at densities exceeding some critical value. This is in contrast to the case of rising symmetry energy, as e.g. for relativistic mean field models, when the kaon condensate can form for any coupling at a sufficiently high density. Properties of the condensate are also different in both cases.

S. Kubis; M. Kutschera

1999-07-24T23:59:59.000Z

291

High Resolution Quantitative Auto-Radiography to determine microscopic distributions of B-10 in neutron capture therapy  

E-Print Network (OSTI)

The success of Boron Neutron Capture Therapy (BNCT) is heavily dependent on the microscopic distribution of B-10 in tissue. High Resolution Quantitative Auto-Radiography (HRQAR) is a potentially valuable analytical tool ...

Harris, Thomas C. (Thomas Cameron)

2006-01-01T23:59:59.000Z

292

EIS-0247: Construction and Operation of the Spallation Neutron Source |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

247: Construction and Operation of the Spallation Neutron 247: Construction and Operation of the Spallation Neutron Source EIS-0247: Construction and Operation of the Spallation Neutron Source SUMMARY The United States needs a high-flux, short- pulsed neutron source to provide its scientific and industrial research communities with a much more intense source of pulsed neutrons for neutron scattering research than is currently available. This source would assure the availability of a state-of-the-art neutron research facility in the United States in the decades ahead. This facility would be used to conduct research in areas such as materials science, condensed matter physics, the molecular structure of biological materials, properties of polymers and complex fluids, and magnetism. In addition to creating new scientific and

293

Proceedings of US/Japan workshop, Q219 on high heat flux components and plasma surface interactions for next fusion devices  

SciTech Connect

This report contains the viewgraphs from the proceedings of US/Japan Workshop on High Heat Flux Components and Plasma Surface Interactions for Next Fusion Devices. Some of the general topics covered by this report are: PFC/PSI in tokamak and helical devices; development of high heat flux components; PSIS and plasma facing materials;tritium; and material damage.

Ulrickson, M.A.; Stevens, P.L.; Hino, T.; Hirohata, Y. [eds.] [eds.

1996-12-01T23:59:59.000Z

294

Fluxes of high- and ultrahigh-energy cosmic-ray muons  

Science Journals Connector (OSTI)

The positive excess of cosmic-ray muons at energies higher than 1 TeV is estimated taking ... particle and antiparticles in proton-proton interactions at energies of ?20 TeV. The fluxes of cosmic-ray muons at energies

L. V. Volkova

2007-04-01T23:59:59.000Z

295

A Model of the Cosmic Ray Induced Atmospheric Neutron Environment  

E-Print Network (OSTI)

In order to optimise the design of space instruments making use of detection materials with low atomic numbers, an understanding of the atmospheric neutron environment and its dependencies on time and position is needed. To produce a simple equation based model, Monte Carlo simulations were performed to obtain the atmospheric neutron fluxes produced by charged galactic cosmic ray interactions with the atmosphere. Based on the simulation results the omnidirectional neutron environment was parametrised including dependencies on altitude, magnetic latitude and solar activity. The upward- and downward-moving component of the atmospheric neutron flux are considered separately. The energy spectra calculated using these equations were found to be in good agreement with data from a purpose built balloon-borne neutron detector, high altitude aircraft data and previously published simulation based spectra.

Kole, Merlin; Salinas, Maria Muñoz

2014-01-01T23:59:59.000Z

296

Enhanced visibility of hydrogen atoms by neutron crystallography on fully deuterated myoglobin  

Science Journals Connector (OSTI)

...the H3A station at the High Flux Beam Reactor at Brookhaven National Laboratory...neutron refinement. The initial x-ray analysis was carried out on a perdeuterated met-Mb crystal at 1.5-a resolution...This situation is changing. Both the reliability of sources as well as advances in neutron...

Fong Shu; Venki Ramakrishnan; Benno P. Schoenborn

2000-01-01T23:59:59.000Z

297

Measurement of Neutron Background at the Pyhasalmi mine for CUPP Project, Finland  

E-Print Network (OSTI)

A natural neutron flux is one of significant kind of background in high-sensitive underground experiments. Therefore, when scheduling a delicate underground measurements one needs to measure neutron background. Deep underground the most significant source of neutrons are the U-Th natural radioactive chains giving a fission spectrum with the temperature of 2-3 MeV. Another source is the U-Th alpha-reactions on light nuclei of mine rock giving neutrons with different spectra in the 1-15 MeV energy region. Normal basalt mine rocks contain 1 ppm g/g of U-238 and less. Deep underground those rocks produce natural neutron fluxes of 10^{-7} - 10^{-6} cm^{-2}s^{-1} above 1 MeV. To measure such a background one needs a special techniques. In the Institute for Nuclear Research, Moscow, the neutron spectrometer was developed and built which is sensitive to such a low neutron fluxes. At the end of 2001 the collection of neutron data at the Pyhasalmi mine was started for the CUPP project. During 2002 the background and rough energy spectra of neutron at underground levels 410, 660, 990 and 1410 m were measured. The result of the measurement of the neutron background at different levels of the Pyhasalmi mine is presented and discussed. Data analysis is performed in different energy ranges from thermal neutrons up to 25 MeV and above.

J. N. Abdurashitov; V. N. Gavrin; V. L. Matushko; A. A. Shikhin; V. E. Yants; J. Peltoniemi; T. Keranen

2006-07-20T23:59:59.000Z

298

Optimal control for fast and high-fidelity quantum gates in coupled superconducting flux qubits  

E-Print Network (OSTI)

We apply the quantum optimal control theory based on the Krotov method to implement single-qubit $X$ and $Z$ gates and two-qubit CNOT gates for inductively coupled superconducting flux qubits with fixed qubit transition frequencies and fixed off-diagonal qubit-qubit coupling. Our scheme that shares the same advantage of other directly coupling schemes requires no additional coupler subcircuit and control lines. The control lines needed are only for the manipulation of individual qubits (e.g., a time-dependent magnetic flux or field applied on each qubit). The qubits are operated at the optimal coherence points and the gate operation times (single-qubit gates $magnetic-field-induced single-qubit interactions and two-qubit couplings. The effect of leakage to higher energy-level states and the effect of qubit decoherence on the quantum gate operations are also discussed.

Shang-Yu Huang; Hsi-Sheng Goan

2014-06-30T23:59:59.000Z

299

The 12B Counter: an active dosemeter for high-energy neutrons  

Science Journals Connector (OSTI)

......measures its own induced radioactivity...reaction Product Energy threshold...taken at a neutron energy of...the time spectra of the 12B...for neutron energy spectra, for instance...with other neutron dosemeters...cylinder 15 Th fission radiator...single-shot time spectrum of the 12B...right): Thermal neutrons (T12 0......

A. Leuschner

2005-12-20T23:59:59.000Z

300

Influence of the topology on the power flux of the Italian high-voltage electrical network  

E-Print Network (OSTI)

A model of the Italian 380 kV electrical transmission network has been analyzed under the topological and the functional viewpoints. The DC power flow model used to evaluate the power flux has been solved on the basis of input conditions (injected power - extracted power, line's reactances and the maximum flux capacity of each line) taken from real data. The vulnerability of the network under load conditions has been estimated by evaluating the power flux redistribution along the lines subsequent to line's removal. When the perturbed network cannot sustain a given input--output demand, the maximum power sustainable by the network has been evaluated to optimize the \\texttt{Quality of Service}, defined as the difference between the expected and the effective dispatched power. The functional relevance of the different lines of the network has been classified according to the amount of power that the network must reduce, to keep alive, upon their removal. Results show that topological and functional relevances ar...

Rosato, V; Gianese, G; Bologna, S

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
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to obtain the most current and comprehensive results.


301

HFIR Technical Parameters | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Reactor Technical Parameters Reactor Technical Parameters Overview HFIR Pool Layout HFIR pool layout. HFIR is a beryllium-reflected, light-water-cooled and -moderated, flux-trap type reactor that uses highly enriched uranium-235 as the fuel. The image on the right is a cutaway of the reactor which shows the pressure vessel, its location in the reactor pool, and some of the experiment facilities. The preliminary conceptual design of the reactor was based on the "flux trap" principle, in which the reactor core consists of four annular regions of fuel surrounding an unfueled moderating region or "island" (see cross section view). Such a configuration permits fast neutrons leaking from the fuel to be moderated in the island and thus produces a region of very high thermal-neutron flux at the center of the island. This reservoir of

302

Neutron skins and neutron stars  

Science Journals Connector (OSTI)

Background: The neutron skin of a heavy nucleus as well as many neutron-star properties are highly sensitive to the poorly constrained density dependence of the symmetry energy.Purpose: To provide for the first time meaningful theoretical errors and to assess the degree of correlation between the neutron-skin thickness of 208Pb and several neutron-star properties.Methods: A proper covariance analysis based on the predictions of an accurately calibrated relativistic functional “FSUGold” is used to quantify theoretical errors and correlation coefficients.Results: We find correlation coefficients of nearly 1 (or ?1) between the neutron-skin thickness of 208Pb and a host of observables of relevance to the structure, dynamics, and composition of neutron stars.Conclusions: We suggest that a follow-up Lead Radius Experiment (PREX) measurement, ideally with a 0.5% accuracy, could significantly constrain the equation of state of neutron-star matter.

F. J. Fattoyev and J. Piekarewicz

2012-07-05T23:59:59.000Z

303

A limit on the ultra-high-energy neutrino flux from lunar observations with the Parkes radio telescope  

E-Print Network (OSTI)

We report a limit on the ultra-high-energy neutrino flux based on a non-detection of radio pulses from neutrino-initiated particle cascades in the Moon, in observations with the Parkes radio telescope undertaken as part of the LUNASKA project. Due to the improved sensitivity of these observations, which had an effective duration of 127 hours and a frequency range of 1.2-1.5 GHz, this limit extends to lower neutrino energies than those from previous lunar radio experiments, with a detection threshold below 10^20 eV. The calculation of our limit allows for the possibility of lunar-origin pulses being misidentified as local radio interference, and includes the effect of small-scale lunar surface roughness. The targeting strategy of the observations also allows us to place a directional limit on the neutrino flux from the nearby radio galaxy Centaurus A.

Bray, J D; Roberts, P; Reynolds, J E; James, C W; Phillips, C J; Protheroe, R J; McFadden, R A; Aartsen, M G

2015-01-01T23:59:59.000Z

304

Small-angle neutron scattering study of high-pressure sintered detonation nanodiamonds  

SciTech Connect

The structure of detonation diamonds sintered at a high pressure (7 GPa) and temperatures of 1200-1700 Degree-Sign C has been investigated by small-angle neutron scattering. It is shown that sintering leads to an increase in the particle size from 6 to 30 nm and established that this increase is due to the chainlike oriented attachment of particles. This study supplements the oriented-attachment model, which was suggested based on the X-ray diffraction spectra of detonation nanodiamonds (DNDs) sintered under the same conditions.

Kidalov, S. V.; Shakhov, F. M., E-mail: fedor.shakhov@mail.ioffe.ru [Ioffe Physical-Technical Institute of the Russian Academy of Sciences (Russian Federation); Lebedev, V. T.; Orlova, D. N.; Grushko, Yu. S. [Russian Academy of Sciences, Konstantinov St. Petersburg Nuclear Physics Institute (Russian Federation)

2011-12-15T23:59:59.000Z

305

Large volume high-pressure cell for inelastic neutron scattering W. Wang, D. A. Sokolov, A. D. Huxley, and K. V. Kamenev  

E-Print Network (OSTI)

Large volume high-pressure cell for inelastic neutron scattering W. Wang, D. A. Sokolov, A. D for inelastic neutron scattering measurements of quantum fluids and solids Rev. Sci. Instrum. 84, 015101 (2013) TOF-SEMSANS--Time-of-flight spin-echo modulated small-angle neutron scattering J. Appl. Phys. 112

Hall, Christopher

306

A Permanent-Magnet Microwave Ion Source for a Compact High-Yield Neutron Generator  

SciTech Connect

We present recent work on the development of a microwave ion source that will be used in a high-yield compact neutron generator for active interrogation applications. The sealed tube generator will be capable of producing high neutron yields, 5x1011 n/s for D-T and ~;;1x1010 n/s for D-D reactions, while remaining transportable. We constructed a microwave ion source (2.45 GHz) with permanent magnets to provide the magnetic field strength of 87.5 mT necessary for satisfying the electron cyclotron resonance (ECR) condition. Microwave ion sources can produce high extracted beam currents at the low gas pressures required for sealed tube operation and at lower power levels than previously used RF-driven ion sources. A 100 mA deuterium/tritium beam will be extracted through a large slit (60x6 mm2) to spread the beam power over a larger target area. This paper describes the design of the permanent-magnet microwave ion source and discusses the impact of the magnetic field design on the source performance. The required equivalent proton beam current density of 40 mA/cm2 was extracted at a moderate microwave power of 400 W with an optimized magnetic field.

Waldmann, Ole; Ludewigt, Bernhard

2010-10-11T23:59:59.000Z

307

Non-streaming high-efficiency perforated semiconductor neutron detectors, methods of making same and measuring wand and detector modules utilizing same  

DOE Patents (OSTI)

Non-streaming high-efficiency perforated semiconductor neutron detectors, method of making same and measuring wands and detector modules utilizing same are disclosed. The detectors have improved mechanical structure, flattened angular detector responses, and reduced leakage current. A plurality of such detectors can be assembled into imaging arrays, and can be used for neutron radiography, remote neutron sensing, cold neutron imaging, SNM monitoring, and various other applications.

McGregor, Douglas S. (Riley, KS); Shultis, John K. (Manhattan, KS); Rice, Blake B. (Manhattan, KS); McNeil, Walter J. (Winnfield, KS); Solomon, Clell J. (Wichita, KS); Patterson, Eric L. (Manhattan, KS); Bellinger, Steven L. (Manhattan, KS)

2010-12-21T23:59:59.000Z

308

Preliminary Neutronic Study of D2O-cooled High Conversion PWRs  

SciTech Connect

This paper presents a preliminary neutronics analysis of tight-pitch D2O-cooled high-conversion PWRs loaded with MOX fuel aiming at high Pu conversion and negative void coefficient. SCALE6.1 has been exclusively utilized for this study. The analyses are performed in two separate parts. The first part of this paper investigates the performance of axial and internal blankets and seeks break-even or near-breeder core even without the presence of radial blankets. The second part of this paper performs sensitivity and uncertainty analyses of integral parameters (keff and void coefficient) for selected systems in order to analyze the characters of this high-conversion PWR from different aspects.

Hikaru Hiruta; Gilles Youinou

2013-10-01T23:59:59.000Z

309

Competition in rotation-alignment between high-j neutrons and protons in transfermium nuclei  

SciTech Connect

The study of rotation-alignment of quasiparticles probes sensitively the properties of high-j intruder orbits. The distribution of very-high-j orbits, which are consequences of the fundamental spin-orbit interaction, links with the important question of single-particle levels in superheavy nuclei. With the deformed single-particle states generated by the standard Nilsson potential, we perform Projected Shell Model calculations for transfermium nuclei where detailed spectroscopy experiments are currently possible. Specifically, we study the systematical behavior of rotation-alignment and associated band-crossing phenomenon in Cf, Fm, and No isotopes. Neutrons and protons from the high-j orbits are found to compete strongly in rotation-alignment, which gives rise to testable effects. Observation of these effects will provide direct information on the single-particle states in the heaviest nuclear mass region.

Al-Khudair, Falih [Department of Physics, Tsinghua University, Beijing 100084 (China); Center of Nuclear Theory, Lanzhou National Laboratory of Heavy Ion Accelerator, Lanzhou 730000 (China); Department of Physics, College of Education, Basrah University, Basrah (Iraq); Long Guilu [Department of Physics, Tsinghua University, Beijing 100084 (China); Center of Nuclear Theory, Lanzhou National Laboratory of Heavy Ion Accelerator, Lanzhou 730000 (China); Sun Yang [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2009-03-15T23:59:59.000Z

310

High energy electron fluxes in dc-augmented capacitively coupled plasmas. II. Effects on twisting in high aspect ratio etching of dielectrics  

SciTech Connect

In high aspect ratio (HAR) plasma etching of holes and trenches in dielectrics, sporadic twisting is often observed. Twisting is the randomly occurring divergence of a hole or trench from the vertical. Many causes have been proposed for twisting, one of which is stochastic charging. As feature sizes shrink, the fluxes of plasma particles, and ions in particular, into the feature become statistical. Randomly deposited charge by ions on the inside of a feature may be sufficient to produce lateral electric fields which divert incoming ions and initiate nonvertical etching or twisting. This is particularly problematic when etching with fluorocarbon gas mixtures where deposition of polymer in the feature may trap charge. dc-augmented capacitively coupled plasmas (dc-CCPs) have been investigated as a remedy for twisting. In these devices, high energy electron (HEE) beams having narrow angular spreads can be generated. HEEs incident onto the wafer which penetrate into HAR features can neutralize the positive charge and so reduce the incidence of twisting. In this paper, we report on results from a computational investigation of plasma etching of SiO{sub 2} in a dc-CCP using Ar/C{sub 4}F{sub 8}/O{sub 2} gas mixtures. We found that HEE beams incident onto the wafer are capable of penetrating into features and partially neutralizing positive charge buildup due to sporadic ion charging, thereby reducing the incidence of twisting. Increasing the rf bias power increases the HEE beam energy and flux with some indication of improvement of twisting, but there are also changes in the ion energy and fluxes, so this is not an unambiguous improvement. Increasing the dc bias voltage while keeping the rf bias voltage constant increases the maximum energy of the HEE and its flux while the ion characteristics remain nearly constant. For these conditions, the occurrence of twisting decreases with increasing HEE energy and flux.

Wang Mingmei [Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa 50010 (United States); Kushner, Mark J. [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States)

2010-01-15T23:59:59.000Z

311

A new technique for beta attenuation studies in neutron activation foils using 4?- coincidence system  

Science Journals Connector (OSTI)

......low flux neutron measurements...low flux neutron measurements...Characteristics of the neutron activation...Resonance energy (eV) Resonance...46 barn (fission spectrum averaged...dose, the induced activity...irradiated in the thermal column of......

Deepa Sathian; M. P. Chougaonkar; Y. S. Mayya

2010-12-01T23:59:59.000Z

312

Fast-Neutron Activation of Long-Lived Nuclides in Natural Pb  

E-Print Network (OSTI)

We measured the production of the long-lived nuclides Bi-207, Pb-202, and Hg-194 in a sample of natural Pb due to high-energy neutron interactions using a neutron beam at the Los Alamos Neutron Science Center. The activated sample was counted by a HPGe detector to measure the amount of radioactive nuclides present. These nuclides are critical in understanding potential backgrounds in low background experiments utilizing large amounts of Pb shielding due to cosmogenic neutron interactions in the Pb while residing on the Earth's surface. By scaling the LANSCE neutron flux to a cosmic neutron flux, we measure the sea level cosmic ray production rates of 8.0 +/- 1.3 atoms/kg/day of Hg-194, 120 +/- 25 atoms/kg/day Pb-202, and 0.17 +/- 0.04 atoms/kg/day Bi-207.

V. E. Guiseppe; S. R. Elliott; N. E. Fields; D. Hixon

2012-09-20T23:59:59.000Z

313

Neutron detector  

DOE Patents (OSTI)

A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

Stephan, Andrew C. (Knoxville, TN); Jardret; Vincent D. (Powell, TN)

2011-04-05T23:59:59.000Z

314

New Limits on the Ultra-High Energy Cosmic Neutrino Flux from the ANITA Experiment  

SciTech Connect

We report initial results of the first flight of the Antarctic Impulsive Transient Antenna (ANITA-1) 2006-2007 Long Duration Balloon flight, which searched for evidence of a diffuse flux of cosmic neutrinos above energies of E{sub v} = 3 x 10{sup 18} eV. ANITA-1 flew for 35 days looking for radio impulses due to the Askaryan effect in neutrino-induced electromagnetic showers within the Antarctic ice sheets. We report here on our initial analysis, which was performed as a blind search of the data. No neutrino candidates are seen, with no detected physics background. We set model-independent limits based on this result. Upper limits derived from our analysis rule out the highest cosmogenic neutrino models. In a background horizontal-polarization channel, we also detect six events consistent with radio impulses from ultrahigh energy extensive air showers.

Gorham, P.W.; Allison, P.; /Hawaii U.; Barwick, S.W.; /UC, Irvine; Beatty, J.J.; /Ohio State U.; Besson, D.Z.; /Kansas U.; Binns, W.R.; /Washington U., St. Louis; Chen, C.; /Taiwan, Natl. Taiwan U.; Chen, P.; /SLAC; Clem, J.M.; /Delaware U.; Connolly, A.; /University Coll. London; Dowkontt, P.F.; /Washington U., St. Louis; DuVernois, M.A.; /Minnesota U.; Field, R.C.; /SLAC; Goldstein, D.; /UC, Irvine; Goodhue, A.; /UCLA; Hast, C.; /SLAC; Hebert, C.L.; /Hawaii U.; Hoover, S.; /UCLA; Israel, M.H.; /Washington U., St. Louis; Kowalski, J.; Learned, J.G.; /Hawaii U. /Caltech, JPL /Hawaii U. /Minnesota U. /Hawaii U. /Ohio State U. /Hawaii U. /UC, Irvine /Taiwan, Natl. Taiwan U. /Caltech, JPL /SLAC /University Coll. London /Ohio State U. /SLAC /Hawaii U. /UCLA /Delaware U. /Hawaii U. /SLAC /Taiwan, Natl. Taiwan U.

2011-12-01T23:59:59.000Z

315

NXS 2010 - Neutron Scattering School  

NLE Websites -- All DOE Office Websites (Extended Search)

2-26, 2010 2-26, 2010 Argonne National Laboratory, Argonne, IL Oak Ridge National Laboratory, Oak Ridge, TN NXS2010 Travel Airport Shuttles Departure Flights Schedule Participants Lectures Lecturers Lecture Notes/Videos Experiments Schedule, Desc, Groups Student Presentations ANL Facilities APS Facility ANL Map ANL Visitor's Guide ORNL Facilities HFIR Facility SNS Facility HFIR/SNS Map Access Requirements ANL ORNL Rad Worker Training Study Guide Wireless Networks ANL ORNL Safety & Security Rules ANL ORNL NSSA New Initiatives NSSA Weblink Contacts ANL ORNL 12th National School on Neutron & X-ray Scattering 2009 Neutron Scattering School participants 2010 National School Participants Students share their thoughts about NXS 2010. Purpose: The main purpose of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major neutron and x-ray facilities. Lectures, presented by researchers from academia, industry, and national laboratories, will include basic tutorials on the principles of scattering theory and the characteristics of the sources, as well as seminars on the application of scattering methods to a variety of scientific subjects. Students will conduct four short experiments at Argonne's Advanced Photon Source and Oak Ridge's Spallation Neutron Source and High Flux Isotope Reactor facilities to provide hands-on experience for using neutron and synchrotron sources.

316

Final evaluation of characterizing pipe-over-pack containers using high efficiency neutron counters  

SciTech Connect

Nondestructive assay (NDA) measurements of Transuranic (TRU) waste at Los Alamos National Laboratory (LANL) packed in Pipe-over-Pack Containers (POC) contain a number of complexities. The POC is highly attenuating to both gamma rays and neutrons which presents a difficult waste matrix for correct quantification of material in the container. Currently there are a number ofPOC containers at LANL that require evaluation for shipment to the Waste Isolation Pilot Plant (WIPP) in Carlsbad, NM. Updated data has been evaluated that finalizes the evaluation of characterizing Pipe-Over-Pack Containers. Currently at LANL, a single instrument has been used to explore the appropriateness of both passive neutron and quantitative gamma ray methods for measuring POC's. The passive neutron approach uses the Reals coincidence count rate to establish plutonium mass and other parameters of interest for TRU waste. The quantitative gamma ray method assumes a homogeneous distribution of radioactive source material with the surrounding material throughout the drum volume. Drums are assayed with a calibration based on the known density of the matrix. Both methods are supplemented by a simultaneous isotopic measurement using Multi-Group Analysis (MGA) to determine the plutonium isotopic composition. If MGA fails to provide a viable isotopic result Fixed Energy Response function Analysis with Multiple efficiencies (FRAM) has been used to replace the MGA results. Acceptable Knowledge (AK) may also be used in certain instances. This report will discuss the two methods in detail. Included in the discussion will be descriptions of the setup parameters and calibration techniques for the instrument. A number of test measurements have been performed to compare HENC data with certified historical data. Empty POCs loaded with known sources have also been measured to determine the viability of the technique. A comparison between calorimetry data, historical measurements and HENC data will also be performed. The conclusion will show that the current calibration on the HENC units is viable for analysis of POCs.

Carson, Pete [Los Alamos National Laboratory; Stanfield, Sean B [AFS; Wachter, Joe [CANBERRA; Cramer, Doug [CANBERRA; Harvill, Joe [WTS

2009-01-01T23:59:59.000Z

317

Natural convection in high heat flux tanks at the Hanford Waste Site / [by] Mark van der Helm and Mujid S. Kazimi  

E-Print Network (OSTI)

A study was carried out on the potential for natural convection and the effect of natural convection in a High Heat Flux Tank, Tank 241-C-106, at the Hanford Reservation. To determine the existence of natural convection, ...

Van der Helm, Mark Johan, 1972-

1996-01-01T23:59:59.000Z

318

Time-series analysis of high-resolution ebullition fluxes from a stratified, freshwater lake  

E-Print Network (OSTI)

[1] Freshwater lakes can emit significant quantities of methane to the atmosphere by bubbling. The high spatial and temporal heterogeneity of ebullition, combined with a lack of high-resolution field measurements, has made ...

Varadharajan, Charuleka

319

High-spin structure and multiphonon {gamma} vibrations in very neutron-rich {sup 114}Ru  

SciTech Connect

High-spin levels of the neutron-rich {sup 114}Ru have been investigated by measuring the prompt {gamma} rays in the spontaneous fission of {sup 252}Cf. The ground-state band and one-phonon {gamma}-vibrational band have been extended up to 14{sup +} and 9{sup +}, respectively. Two levels are proposed as the members of a two-phonon {gamma}-vibrational band. A back bending (band crossing) has been observed in the ground-state band at ({h_bar}/2{pi}){omega}{approx_equal} 0.40 MeV. Using the triaxial deformation parameters, the cranked shell model calculations indicate that this back bending in {sup 114}Ru should originate from the alignment of a pair of h{sub 11/2} neutrons. Triaxial projected shell model calculations for the {gamma}-vibrational band structures of {sup 114}Ru are in good agreement with the experimental data. However, when using the oblate deformation parameters, both of the above-calculated results are not in agreement with the experimental data.

Yeoh, E. Y.; Wang, J. G.; Ding, H. B.; Gu, L.; Xu, Q.; Xiao, Z. G. [Department of Physics, Tsinghua University, Beijing 100084 (China); Zhu, S. J. [Department of Physics, Tsinghua University, Beijing 100084 (China); Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); Hamilton, J. H.; Li, K.; Ramayya, A. V.; Hwang, J. K. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); Liu, Y. X. [School of Science, Huzhou Teachers College, Huzhou 313000 (China); Liu, S. H. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); UNIRIB/Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831 (United States); Sun, Y. [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Sheikh, J. A.; Bhat, G. H. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Luo, Y. X. [Department of Physics, Vanderbilt University, Nashville, Tennessee 37235 (United States); Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Rasmussen, J. O.; Lee, I. Y. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ma, W. C. [Department of Physics, Mississippi State University, Mississippi State, Mississippi 39762 (United States)

2011-05-15T23:59:59.000Z

320

Calculations of neutron spectra after neutron–neutron scattering  

Science Journals Connector (OSTI)

A direct neutron–neutron scattering length, ann, measurement with the goal of 3% accuracy (0.5 fm) is under preparation at the aperiodic pulsed reactor YAGUAR. A direct measurement of ann will not only help resolve conflicting results of ann by indirect means, but also in comparison to the proton–proton scattering length, app, shed light on the charge-symmetry of the nuclear force. We discuss in detail the analysis of the nn-scattering data in terms of a simple analytical expression. We also discuss calibration measurements using the time-of-flight spectra of neutrons scattered on He and Ar gases and the neutron activation technique. In particular, we calculate the neutron velocity and time-of-flight spectra after scattering neutrons on neutrons and after scattering neutrons on He and Ar atoms for the proposed experimental geometry, using a realistic neutron flux spectrum—Maxwellian plus epithermal tail. The shape of the neutron spectrum after scattering is appreciably different from the initial spectrum, due to collisions between thermal–thermal and thermal–epithermal neutrons. At the same time, the integral over the Maxwellian part of the realistic scattering spectrum differs by only about 6 per cent from that of a pure Maxwellian nn-scattering spectrum.

B E Crawford; S L Stephenson; C R Howell; G E Mitchell; W Tornow; W I Furman; E V Lychagin; A Yu Muzichka; G V Nekhaev; A V Strelkov; E I Sharapov; V N Shvetsov

2004-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Model Atmospheres for Low Field Neutron Stars  

E-Print Network (OSTI)

We compute model atmospheres and emergent spectra for low field (Bsolar abundance and iron atmospheres. We compare our results to high field magnetic atmospheres, available only for hydrogen. An application to apparently thermal flux from the low field millisecond pulsar PSR J0437--4715 shows that H atmospheres fit substantially better than Fe models. We comment on extension to high fields and the implication of these results for neutron star luminosities and radii.

Mohan Rajagopal; Roger Romani

1995-10-19T23:59:59.000Z

322

Design Study for a Low-Enriched Uranium Core for the High Flux Isotope Reactor, Annual Report for FY 2008  

SciTech Connect

This report documents progress made during FY 2008 in studies of converting the High Flux Isotope Reactor (HFIR) from highly enriched uranium (HEU) fuel to low-enriched uranium (LEU) fuel. Conversion from HEU to LEU will require a change in fuel form from uranium oxide to a uranium-molybdenum alloy. With axial and radial grading of the fuel foil and an increase in reactor power to 100 MW, calculations indicate that the HFIR can be operated with LEU fuel with no degradation in reactor performance from the current level. Results of selected benchmark studies imply that calculations of LEU performance are accurate. Scoping experiments with various manufacturing methods for forming the LEU alloy profile are presented.

Primm, Trent [ORNL; Chandler, David [ORNL; Ilas, Germina [ORNL; Miller, James Henry [ORNL; Sease, John D [ORNL; Jolly, Brian C [ORNL

2009-03-01T23:59:59.000Z

323

Radiation tolerance survey of selected silicon photomultipliers to high energy neutron irradiation  

SciTech Connect

A key feature of silicon photomultipliers (SiPMs) that can hinder their wider use in medium and high energy physics applications is their relatively high sensitivity to high energy background radiation, with particular regard to high energy neutrons. Dosages of 1010 neq/cm2 can damage them severely. In this study, some standard versions along with some new formulations are irradiated with a high intensity 241AmBe source up to a total dose of 5 × 109 neq/cm2. Key parameters monitored include dark noise, photon detection efficiency (PDE), gain, and voltage breakdown. Only dark noise was found to change significantly for this range of dosage. Analysis of the data indicates that within each vendor's product line, the change in dark noise is very similar as a function of increasing dose. At present, the best strategy for alleviating the effects of radiation damage is to cool the devices to minimize the effects of increased dark noise with accumulated dose.

Barbosa, Fernando J. [JLAB; McKisson, John E. [JLAB; Qiang, Yi [JLAB; Steinberger, William [JLAB; Xi, Wenze [JLAB; Zorn, Carl J. [JLAB

2012-11-01T23:59:59.000Z

324

Neutrons from high?energy x?ray medical accelerators: An estimate of risk to the radiotherapy patient  

Science Journals Connector (OSTI)

The problem of neutrons produced by many of the high?energy x?ray therapy machines (10 MV and above) is reviewed and the possible risk their presence poses to radiotherapy patients is estimated. A review of the regulatory background containing a summary of the recommendations of the U. S. Council of State Governments (USCSG) and of the International Electro?Technical Commission (IEC) as well as an indication that recommendations will be forthcoming from the National Council on Radiation Protection (NCRP) and the International Commission of Radiological Protection (ICRP) is presented. The neutrons in question are produced by high?energy photons(x rays) incident on the various materials of the target flattening filter collimators and other essential components of the equipment. The neutron yield (per treatmentdose) increases rapidly as the megavoltage is increased from 10 to 20 MV but remains approximately constant above this. Measurements and calculations of the quantity quality and spatial distribution of these neutrons and their concomitant dose are summarized. Values of the neutrondose are presented as entrance dose midline dose (10?cm depth) and integral dose both within and outside of the treatment volume. These values are much less than the unavoidable photondoses which are largely responsible for treatment side effects. For typical equipment the average neutron integral dose from accelerator?produced neutrons is about 4–7 g?cGy (per treatment cGy) depending on the treatment plan. This translates into an average dose of neutrons [averaged over the body of a typical 70?kg (154 1b) patient] of 0.06–0.10 cGy for a treatment of 1000 cGy. Using these neutrondoses and the best available neutron risk coefficients it is estimated that 50×10? 6 fatal malignancies per year due to the neutrons may follow a typical treatment course of 5000 rads of 25?MV x rays. This is only about 1/60th of the average incidence of malignancies for the general population. Thus the cancer risk to the radiotherapy patient from accelerator?produced neutrons poses an additional risk to the patient that is negligible in comparison.

Ravinder Nath; Edward R. Epp; John S. Laughlin; William P. Swanson; Victor P. Bond

1984-01-01T23:59:59.000Z

325

Biology and Soft Matter | Neutron Sciences | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Biology and Soft Matter Biology and Soft Matter SHARE Biology and Soft Matter This is a time of unprecedented opportunity for using neutrons in biological and soft matter research. The US Department of Energy (DOE) has invested in two forefront neutron user facilities, the accelerator-based Spallation Neutron Source (SNS) and the reactor-based High Flux Isotope Reactor (HFIR), at Oak Ridge National Laboratory (ORNL). Researchers have access to new instrumentation on some of the world's most intense neutron beam lines for studying the structure, function, and dynamics of complex systems. We anticipate that soft matter and biological sciences of tomorrow will require understanding, predicting, and manipulating complex systems to produce the new materials and products required to meet our nation's

326

Cryogenic hydrogen circulation system of neutron source  

SciTech Connect

Cold neutron sources of reactors and spallation neutron sources are classic high flux neutron sources in operation all over the world. Cryogenic fluids such as supercritical or supercooled hydrogen are commonly selected as a moderator to absorb the nuclear heating from proton beams. By comparing supercritical hydrogen circulation systems and supercooled hydrogen circulation systems, the merits and drawbacks in both systems are summarized. When supercritical hydrogen circulates as the moderator, severe pressure fluctuations caused by temperature changes will occur. The pressure control system used to balance the system pressure, which consists of a heater as an active controller for thermal compensation and an accumulator as a passive volume controller, is preliminarily studied. The results may provide guidelines for design and operation of other cryogenic hydrogen system for neutron sources under construction.

Qiu, Y. N. [Institute of Physics and Chemistry, Chinese Academy of Sciences, BJ100190 China and University of Chinese Academy of Sciences, Chinese Academy of Sciences, BJ100049 (China); Hu, Z. J.; Wu, J. H.; Li, Q.; Zhang, Y. [Institute of Physics and Chemistry, Chinese Academy of Sciences, BJ100190 (China); Zhang, P. [School of Energy and Power Engineering, HuaZhong University of Science and Technology, WH430074 (China); Wang, G. P. [Institute of High Energy Physics, Chinese Academy of Sciences, BJ100049 (China)

2014-01-29T23:59:59.000Z

327

Ectomycorrhizal fungi and past high CO2 atmospheres enhance mineral weathering through increased below-ground carbon-energy fluxes  

Science Journals Connector (OSTI)

...experimental support for the carbon-energy flux hypothesis and a unifying...increased below-ground carbon-energy fluxes, which accelerated silicate...10.1139/b04-060 ) 3 Key World Energy Statistics. 2011 International Energy Agency...

2014-01-01T23:59:59.000Z

328

Neutrinos from Decaying Muons, Pions, Kaons and Neutrons in Gamma Ray Bursts  

E-Print Network (OSTI)

In the internal shock model of gamma ray bursts ultrahigh energy muons, pions, neutrons and kaons are likely to be produced in the interactions of shock accelerated relativistic protons with low energy photons (KeV-MeV). These particles subsequently decay to high energy neutrinos/antineutrinos and other secondaries. In the high internal magnetic fields of gamma ray bursts, the ultrahigh energy charged particles ($\\mu^+$, $\\pi^+$, $K^+$) lose energy significantly due to synchrotron radiations before decaying into secondary high energy neutrinos and antineutrinos. The relativistic neutrons decay to high energy antineutrinos, protons and electrons. We have calculated the total neutrino flux (neutrino and antineutrino) considering the decay channels of ultrahigh energy muons, pions, neutrons and kaons. We have shown that the total neutrino flux generated in neutron decay can be higher than that produced in $\\mu^+$ and $\\pi^+$ decay. The charged kaons being heavier than pions, lose energy slowly and their secondary total neutrino flux is more than that from muons and pions at very high energy. Our detailed calculations on secondary particle production in $p\\gamma$ interactions give the total neutrino fluxes and their flavour ratios expected on earth. Depending on the values of the parameters (luminosity, Lorentz factor, variability time, spectral indices and break energy in the photon spectrum) of a gamma ray burst the contributions to the total neutrino flux from the decay of different particles (muon, pion, neutron and kaon) may vary and they would also be reflected on the neutrino flavour ratios.

Reetanjali Moharana; Nayantara Gupta

2012-05-27T23:59:59.000Z

329

An evaluation of multigroup flux predictions in the EBR-II core  

SciTech Connect

The unique physics characteristics of EBR-II which are difficult to model with conventional neutronic methodologies are identified; the high neutron leakage fraction and importance of neutron reflection cause errors when conventional calculational approximations are utilized. In this paper, various conventional and higher-order group constant evaluations and flux computation methods are compared for a simplified R-Z model of the EBR-II system. Although conventional methods do provide adequate predictions of the flux in the core region, significant mispredictions are observed in the reflector and radial blanket regions. Calculational comparisons indicate that a fine energy group structure is required for accurate predictions of the eigenvalue and flux distribution; greater detail is needed in the iron resonance scattering treatment. Calculational comparisons also indicate that transport theory with detailed anisotropic scattering treatment is required.

Hill, R.N.; Fanning, T.H.; Finck, P.J.

1991-12-31T23:59:59.000Z

330

An evaluation of multigroup flux predictions in the EBR-II core  

SciTech Connect

The unique physics characteristics of EBR-II which are difficult to model with conventional neutronic methodologies are identified; the high neutron leakage fraction and importance of neutron reflection cause errors when conventional calculational approximations are utilized. In this paper, various conventional and higher-order group constant evaluations and flux computation methods are compared for a simplified R-Z model of the EBR-II system. Although conventional methods do provide adequate predictions of the flux in the core region, significant mispredictions are observed in the reflector and radial blanket regions. Calculational comparisons indicate that a fine energy group structure is required for accurate predictions of the eigenvalue and flux distribution; greater detail is needed in the iron resonance scattering treatment. Calculational comparisons also indicate that transport theory with detailed anisotropic scattering treatment is required.

Hill, R.N.; Fanning, T.H.; Finck, P.J.

1991-01-01T23:59:59.000Z

331

Neutron reflecting supermirror structure  

DOE Patents (OSTI)

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. One layer of each set of bilayers consist of titanium, and the second layer of each set of bilayers consist of an alloy of nickel with carbon interstitially present in the nickel alloy.

Wood, James L. (Drayton Plains, MI)

1992-01-01T23:59:59.000Z

332

Consistency between the Lorentz-Force Independence of the Resistive Transition in the High-T-C Superconductors and the Standard Theory of Flux-Flow  

E-Print Network (OSTI)

PHYSICAL REVIEW B VOLUME 51, NUMBER 14 1 APRIL 1995-II Consistency between the Lorentz-force independence of the resistive transition in the high-T, superconductors and the standard theory of flux flow Zhidong Hao Tezas Center.... S. Ting Tezas Center for Superconductivity, University of Houston, Houston, Texas 77P04 (Received 6 October 1994) In a uniform flux-flow state of a type-II superconductor, (i) the resistivity tensor p,~ is independent of the dissipative transport...

HAO, ZD; Hu, Chia-Ren; TING, CS.

1995-01-01T23:59:59.000Z

333

Organic vapor separation: Process design with regards to high-flux membranes and the dependence on real gas behavior at high pressure applications  

SciTech Connect

High-flux membranes are well-suited for separating organic vapor from air. There are many applications for organic vapor recovery at tank farms. Here, the membrane technology is already considered as state of the art. However, new applications operating at higher pressures, e.g., water and hydrocarbon dewpointing of natural gas, real gas behavior, and the so-called concentration polarization effect have to be taken into account. Experimental investigations have been carried out and the results are presented. The performance of a membrane module is calculated considering real gas behavior.

Alpers, A.; Keil, B.; Luedtke, O.; Ohlrogge, K.

1999-10-01T23:59:59.000Z

334

FLUX-GRADIENT AND SOURCE TERM BALANCING FOR CERTAIN HIGH RESOLUTION SHOCK-CAPTURING SCHEMES  

E-Print Network (OSTI)

generation. Key Words: shallow water equations, high resolution shock capturing schemes, conservation Introduction Many practical problems involving shallow water flow in oceanography and atmospheric sciences in [8], for the shallow water system. We show that the use of two different Jacobians at cell interfaces

335

In Situ Electrochemical X-ray Absorption Spectroscopy of Oxygen Reduction Electrocatalysis with High Oxygen Flux  

E-Print Network (OSTI)

to the widespread application of fuel cells and air-cathode batteries in automotive and stationary power a progressive evolution of the electronic structure of the metal clusters that is both potential) and the large overpotential (300 mV) in fuel cell cathodes necessitate the use of high loadings of precious-metal

Frenkel, Anatoly

336

High Neutron Fluence Survivability Testing of Advanced Fiber Bragg Grating Sensors  

SciTech Connect

The motivation for the reported research was to support NASA space nuclear power initiatives through the development of advanced fiber optic sensors for space-based nuclear power applications. The purpose of the high-neutron fluence testing was to demonstrate the survivability of fiber Bragg grating (FBG) sensors in a fission reactor environment. 520 FBGs were installed in the Ford reactor at the University of Michigan. The reactor was operated for 1012 effective full power hours resulting in a maximum neutron fluence of approximately 5x1019 n/cm2, and a maximum gamma dose of 2x103 MGy gamma. This work is significant in that, to the knowledge of the authors, the exposure levels obtained are approximately 1000 times higher than for any previously published experiment. Four different fiber compositions were evaluated. An 87% survival rate was observed for fiber Bragg gratings located at the fuel centerline. Optical Frequency Domain Reflectometry (OFDR), originally developed at the NASA Langley Research Center, can be used to interrogate several thousand low-reflectivity FBG strain and/or temperature sensors along a single optical fiber. A key advantage of the OFDR sensor technology for space nuclear power is the extremely low mass of the sensor, which consists of only a silica fiber 125{mu}m in diameter. The sensors produced using this technology will fill applications in nuclear power for current reactor plants, emerging Generation-IV reactors, and for space nuclear power. The reported research was conducted by Luna Innovations and was funded through a Small Business Innovative Research (SBIR) contract with the NASA Glenn Research Center.

Fielder, Robert S.; Klemer, Daniel; Stinson-Bagby, Kelly L. [Luna Innovations, Inc., 2851 Commerce Street, Blacksburg, VA 24060 (United States)

2004-02-04T23:59:59.000Z

337

Temperature dependence of a high- T c single-flux-quantum logic gate up to 50 K  

Science Journals Connector (OSTI)

Basic characteristics of a simple single-flux-quantum (SFQ) logic gate using high- T c material and Josephson junction ( NdBa 2 Cu 3 O 7?? and focused ion beamjunction) have been investigated. The logic gate consists of an rf-superconducting quantum interference device (rf-SQUID) and a dc-SQUID. In the logic gate elementary SFQ logic operations such as generating SFQ (dc/SFQ) and providing simultaneous readout (SFQ/dc) have been confirmed up to 50 K. The temperature dependencies of the output voltage level and the critical current-normal resistance (I c R n ) product were compared and the decreasing tendency of the output voltage level for increasing temperature was found to be more rapid than that of the I c R n product.

Kazuo Saitoh; Tadashi Utagawa; Youichi Enomoto

1998-01-01T23:59:59.000Z

338

SEARCHES FOR HIGH-FREQUENCY VARIATIONS IN THE {sup 8}B SOLAR NEUTRINO FLUX AT THE SUDBURY NEUTRINO OBSERVATORY  

SciTech Connect

We have performed three searches for high-frequency signals in the solar neutrino flux measured by the Sudbury Neutrino Observatory, motivated by the possibility that solar g-mode oscillations could affect the production or propagation of solar {sup 8}B neutrinos. The first search looked for any significant peak in the frequency range 1-144 day{sup -1}, with a sensitivity to sinusoidal signals with amplitudes of 12% or greater. The second search focused on regions in which g-mode signals have been claimed by experiments aboard the Solar and Heliospheric Observatory satellite, and was sensitive to signals with amplitudes of 10% or greater. The third search looked for extra power across the entire frequency band. No statistically significant signal was detected in any of the three searches.

Aharmim, B.; Chauhan, D. [Department of Physics and Astronomy, Laurentian University, Sudbury, ON P3E 2C6 (Canada); Ahmed, S. N.; Boulay, M. G.; Cai, B.; Chen, M.; Dai, X. [Department of Physics, Queen's University, Kingston, ON K7L 3N6 (Canada); Anthony, A. E. [Department of Physics, University of Texas at Austin, Austin, TX 78712-0264 (United States); Barros, N. [Laboratorio de Instrumentacao e Fisica Experimental de PartIculas, Av. Elias Garcia 14, 1, 1000-149 Lisboa (Portugal); Beier, E. W.; Deng, H. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104-6396 (United States); Bellerive, A.; Boudjemline, K. [Ottawa-Carleton Institute for Physics, Department of Physics, Carleton University, Ottawa, ON K1S 5B6 (Canada); Beltran, B. [Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2R3 (Canada); Bergevin, M.; Chan, Y. D. [Institute for Nuclear and Particle Astrophysics and Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Biller, S. D.; Cleveland, B. T. [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Burritt, T. H.; Cox, G. A. [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States)

2010-02-10T23:59:59.000Z

339

Constraints on the extremely-high energy cosmic neutrino flux with the IceCube 2008-2009 data  

Science Journals Connector (OSTI)

We report on a search for extremely-high energy neutrinos with energies greater than 106??GeV using the data taken with the IceCube detector at the South Pole. The data was collected between April 2008 and May 2009 with the half-completed IceCube array. The absence of signal candidate events in the sample of 333.5 days of live time significantly improves model-independent limits from previous searches and allows to place a limit on the diffuse flux of cosmic neutrinos with an E-2 spectrum in the energy range 2.0×106-6.3×109??GeV to a level of E2??3.6×10-8??GeV?cm-2?sec-1?sr-1.

R. Abbasi et al. (IceCube Collaboration)

2011-05-24T23:59:59.000Z

340

Neutron Science In the News - 2014 | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Neutron Science In the News - 2014 Neutron Science In the News - 2014 Because some media sources archive past articles and require a subscription for access, some of the links below might not be active. If a citation listed here is no longer available, please contact the newspaper or your library directly. January Multiphysics Simulations Transmuting Designs for Safer Nuclear Power Engineering.com 1/7 Like the rest of the US's nuclear research reactors, Oak Ridge National Lab's (ORNL) high flux isotope reactor (HFIR) is moving from high-enriched uranium (HEU) fuel to low-enriched uranium (LEU). As such, the safety of the system must be assessed to incorporate the changes in fuel properties and the subsequently modified fuel plate. Due to the recent growth in multiphysics, fluid-structure dynamics

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

The AGASA/SUGAR Anisotropies and TeV Gamma Rays from the Galactic Center: A Possible Signature of Extremely High-energy Neutrons  

E-Print Network (OSTI)

Recent analysis of data sets from two extensive air shower cosmic ray detectors shows tantalizing evidence of an anisotropic overabundance of cosmic rays towards the Galactic Center (GC) that ``turns on'' around $10^{18}$ eV. We demonstrate that the anisotropy could be due to neutrons created at the Galactic Center through charge-exchange in proton-proton collisions, where the incident, high energy protons obey an $\\sim E^{-2}$ power law associated with acceleration at a strong shock. We show that the normalization supplied by the gamma-ray signal from EGRET GC source 3EG J1746-2851 -- ascribed to pp induced neutral pion decay at GeV energies -- together with a very reasonable spectral index of 2.2, predicts a neutron flux at $\\sim 10^{18}$ eV fully consistent with the extremely high energy cosmic ray data. Likewise, the normalization supplied by the very recent GC data from the HESS air-Cerenkov telescope at \\~TeV energies is almost equally-well compatible with the $\\sim 10^{18}$ eV cosmic ray data. Interestingly, however, the EGRET and HESS data appear to be themselves incompatible. We consider the implications of this discrepancy. We discuss why the Galactic Center environment can allow diffusive shock acceleration at strong shocks up to energies approaching the ankle in the cosmic ray spectrum. Finally, we argue that the shock acceleration may be occuring in the shell of Sagittarius A East, an unusual supernova remnant located very close to the Galactic Center. If this connection between the anisotropy and Sagittarius A East could be firmly established it would be the first direct evidence for a particular Galactic source of cosmic rays up to energies near the ankle.

Roland M. Crocker; Marco Fatuzzo; Randy Jokipii; Fulvio Melia; Raymond R. Volkas

2004-08-10T23:59:59.000Z

342

HYSPEC : A CRYSTAL TIME OF FLIGHT HYBRID SPECTROMETER FOR THE SPALLATION NEUTRON SOURCE.  

SciTech Connect

This document lays out a proposal by the Instrument Development Team (IDT) composed of scientists from leading Universities and National Laboratories to design and build a conceptually new high-flux inelastic neutron spectrometer at the pulsed Spallation Neutron Source (SNS) at Oak Ridge. This instrument is intended to supply users of the SNS and scientific community, of which the IDT is an integral part, with a platform for ground-breaking investigations of the low-energy atomic-scale dynamical properties of crystalline solids. It is also planned that the proposed instrument will be equipped with a polarization analysis capability, therefore becoming the first polarized beam inelastic spectrometer in the SNS instrument suite, and the first successful polarized beam inelastic instrument at a pulsed spallation source worldwide. The proposed instrument is designed primarily for inelastic and elastic neutron spectroscopy of single crystals. In fact, the most informative neutron scattering studies of the dynamical properties of solids nearly always require single crystal samples, and they are almost invariably flux-limited. In addition, in measurements with polarization analysis the available flux is reduced through selection of the particular neutron polarization, which puts even more stringent limits on the feasibility of a particular experiment. To date, these investigations have mostly been carried out on crystal spectrometers at high-flux reactors, which usually employ focusing Bragg optics to concentrate the neutron beam on a typically small sample. Construction at Oak Ridge of the high-luminosity spallation neutron source, which will provide intense pulsed neutron beams with time-averaged fluxes equal to those at medium-flux reactors, opens entirely new opportunities for single crystal neutron spectroscopy. Drawing upon experience acquired during decades of studies with both crystal and time-of-flight (TOF) spectrometers, the IDT has developed a conceptual design for a focused-beam, hybrid time-of-flight instrument with a crystal monochromator for the SNS called HYSPEC (an acronym for hybrid spectrometer). The proposed instrument has a potential to collect data more than an order of magnitude faster than existing steady-source spectrometers over a wide range of energy transfer ({h_bar}{omega}) and momentum transfer (Q) space, and will transform the way that data in elastic and inelastic single-crystal spectroscopy are collected. HYSPEC is optimized to provide the highest neutron flux on sample in the thermal and epithermal neutron energy ranges at a good-to-moderate energy resolution. By providing a flux on sample several times higher than other inelastic instruments currently planned for the SNS, the proposed instrument will indeed allow unique ground-breaking measurements, and will ultimately make polarized beam studies at a pulsed spallation source a realistic possibility.

SHAPIRO,S.M.; ZALIZNYAK,I.A.

2002-12-30T23:59:59.000Z

343

ORNL - Restart of the High Flux Isotope Reactor 2-07  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Management Management OBJECTIVE MG-1: Line management has established programs to ensure safe accomplishment of work. Personnel exhibit awareness of public and worker safety, health, and environmental protection requirements, and through their actions, they demonstrate a high-priority commitment to comply with these requirements. (Core Requirements 1 and 2) Criteria * Line management has integrated programs within its existing ISMS and implementing mechanisms that appropriately address the major changes implemented during this outage, notably the CS, in order to continue to assure safe accomplishment of work. * Senior management and RRD management exhibit awareness of the applicable requirements pertaining to reactor operation, with emphasis on the

344

ORNL - Restart of the High Flux Isotope Reactor 2-07  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

QUALITY ASSURANCE (QA) QUALITY ASSURANCE (QA) OBJECTIVE QA-1: The RRD QA program has been appropriately modified to reflect the CS modification and its reactor interface, and sufficient numbers of qualified QA personnel are provided to ensure services are adequate to support reactor operation. The QA functions, assignments, responsibilities, and reporting relationships are clearly defined, understood, and effectively implemented with line management control of safety. QA personnel exhibit awareness of the applicable requirements pertaining to reactor operation with the CS and the associated hazards. Through their actions, they have demonstrated a high-priority commitment to comply with these requirements. The level of knowledge of QA personnel related to reactor

345

ORNL - Restart of the High Flux Isotope Reactor 2-07  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

ENGINEERING (ENG) ENGINEERING (ENG) OBJECTIVE ENG-1: The engineering program has been appropriately modified to reflect the CS modification and its reactor interface, sufficient numbers of qualified engineering personnel are provided, and adequate facilities and equipment are available to ensure engineering services are adequate to support reactor and CS operations. The engineering functions, assignments, responsibilities, and reporting relationships are clearly defined, understood, and effectively implemented with line management control of safety. Engineering personnel exhibit awareness of the applicable requirements pertaining to reactor operation with the CS and with CS operations and hazards. Through their actions, they have demonstrated a high-priority commitment

346

ORNL - Restart of the High Flux Isotope Reactor 2-07  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

ENVIRONMENTAL PROTECTION AND WASTE MANAGEMENT (EW) ENVIRONMENTAL PROTECTION AND WASTE MANAGEMENT (EW) OBJECTIVE EW-1: UT-Battelle line management has established environmental protection and waste management programs to ensure safe accomplishment of work (or is adequately applying an existing, approved program). Personnel exhibit an awareness of environmental protection and waste management requirements, and through their actions, they demonstrate a high-priority commitment to comply with these requirements. (Core Requirements 1 and 14) Criteria * All environment compliance and waste management matrix support functions are identified for HFIR's operations. * Appropriate environmental protection/waste management plans and procedures for HFIR have been issued. * Adequate staffing is available to support the environmental protection and

347

Radiochemical Transformation of High Pressure Methane under Gamma, Electron, and Neutron Irradiation  

E-Print Network (OSTI)

) at an activity of 400 Ci. The electron source was a 10 MeV, 15 kW, linear accelerator at the National Center for Electron Beam Research. The neutron source was the NSC reactor running at 1 MWth. The in-core positions were used for the neutron irradiations had...

Clemens, Jeffrey Tyler

2014-05-01T23:59:59.000Z

348

High-Energy Neutrons Produced by 740-MeV Protons on Uranium  

Science Journals Connector (OSTI)

Neutron spectra from 740-MeV proton bombardment of a 30-cm-thick depleted U238 target were measured from 20 to 500 MeV at 50° and from 5 to 140 MeV at 130° with respect to the proton beam. Measurements were made at the Lawrence Berkeley Laboratory (LBL) 184-in. cyclotron with a self-contained neutron time-of-flight spectrometer. The results are compared with a Monte Carlo calculation of the neutron cascade-evaporation spectrum. While the shapes of the measured and calculated spectra are in general agreement, this comparison shows that the intranuclear cascade model underestimates the production of cascade neutrons at wide angles; furthermore, this comparison shows that this discrepancy increases with increasing angle of emission. At 50°, the yield of neutrons above 25 MeV is 1.4 times that calculated; at 130°, this factor increases to 1.6. For neutrons above 25 MeV, the measured yield at 50° is 5 times greater than that at 130°. From the measurements at 50 and 130°, it is estimated that the total integrated yield above 25 MeV is 0.95 neutrons per incident proton; the Monte Carlo calculation predicts 0.67 neutrons per incident proton. Below 20 MeV, the results are in agreement with the calculation.

Richard Madey and Frank M. Waterman

1973-12-01T23:59:59.000Z

349

Neutron interrogation system using high gamma ray signature to detect contraband special nuclear materials in cargo  

DOE Patents (OSTI)

A system for inspecting cargo for the presence of special nuclear material. The cargo is irradiated with neutrons. The neutrons produce fission products in the special nuclear material which generate gamma rays. The gamma rays are detecting indicating the presence of the special nuclear material.

Slaughter, Dennis R. (Oakland, CA); Pohl, Bertram A. (Berkeley, CA); Dougan, Arden D. (San Ramon, CA); Bernstein, Adam (Palo Alto, CA); Prussin, Stanley G. (Kensington, CA); Norman, Eric B. (Oakland, CA)

2008-04-15T23:59:59.000Z

350

Solar Neutron Events of October-November 2003  

E-Print Network (OSTI)

During the period when the Sun was intensely active on October-November 2003, two remarkable solar neutron events were observed by the ground-based neutron monitors. On October 28, 2003, in association with an X17.2 large flare, solar neutrons were detected with high statistical significance (6.4 sigma) by the neutron monitor at Tsumeb, Namibia. On November 4, 2003, in association with an X28 class flare, relativistic solar neutrons were observed by the neutron monitors at Haleakala in Hawaii and Mexico City, and by the solar neutron telescope at Mauna Kea in Hawaii simultaneously. Clear excesses were observed at the same time by these detectors, with the significance calculated as 7.5 sigma for Haleakala, and 5.2 sigma for Mexico City. The detector onboard the INTEGRAL satellite observed a high flux of hard X-rays and gamma-rays at the same time in these events. By using the time profiles of the gamma-ray lines, we can explain the time profile of the neutron monitor. It appears that neutrons were produced at the same time as the gamma-ray emission.

K. Watanabe; M. Gros; P. H. Stoker; K. Kudela; C. Lopate; J. F. Valdes-Galicia; A. Hurtado; O. Musalem; R. Ogasawara; Y. Mizumoto; M. Nakagiri; A. Miyashita; Y. Matsubara; T. Sako; Y. Muraki; T. Sakai; S. Shibata

2005-09-19T23:59:59.000Z

351

Design and Implementation of a Detector for High Flux Mixed Radiation Fields  

E-Print Network (OSTI)

The main purpose of the LHC Beam Loss Monitoring (BLM) system is the active protection of the LHC accelerators' elements against the quench of superconducting magnets and the damage of equipment caused by the loss of circulating protons. The lost protons initiate a shower of secondary particles, which deposit their energy in the equipment and partly in a radiation detector. If thresholds in the BLM system are exceeded, the circulating LHC beam is directed towards a dump to stop the energy deposition in the fragile equipment. The LHC BLM system will use ionization chambers as standard detectors, and in the areas with very high dose rates Secondary Emission Monitor (SEM) chambers will be employed to increase the dynamic range. The SEM is characterized by a high linearity and accuracy, low sensitivity, fast response and a good radiation tolerance. The emission of electrons from the surface layer of metals by the passage of charged particles is only measurable in a vacuum environment. This requirement leads toget...

Kramer, Daniel; Sulc, Miroslav

2008-01-01T23:59:59.000Z

352

PERFORMING DIAGNOSTICS ON THE SPALLATION NEUTRON SOURCE VISION BEAM LINE TO ELIMINATE HIGH VIBRATION LEVELS AND PROVIDE A SUSTAINABLE OPERATION  

SciTech Connect

The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) provides variable energy neutrons for a variety of experiments. The neutrons proceed down beam lines to the experiment hall, which houses a variety of experiments and test articles. Each beam line has one or more neutron choppers which filter the neutron beam based on the neutron energy by using a rotating neutron absorbing material passing through the neutron beam. Excessive vibration of the Vision beam line, believed to be caused by the T0 chopper, prevented the Vision beam line from operating at full capacity. This problem had been addressed several times by rebalancing/reworking the T0 beam chopper but the problem stubbornly persisted. To determine the cause of the high vibration, dynamic testing was performed. Twenty-seven accelerometer and motor current channels of data were collected during drive up, drive down, coast down, and steady-state conditions; resonance testing and motor current signature analysis were also performed. The data was analyzed for traditional mechanical/machinery issues such as misalignment and imbalance using time series analysis, frequency domain analysis, and operating deflection shape analysis. The analysis showed that the chopper base plate was experiencing an amplified response to the excitation provided by the T0 beam chopper. The amplified response was diagnosed to be caused by higher than expected base plate flexibility, possibly due to improper grouting or loose floor anchors. Based on this diagnosis, a decision was made to dismantle the beam line chopper and remount the base plate. Neutron activation of the beam line components make modifications to the beam line especially expensive and time consuming due to the radiation handling requirements, so this decision had significant financial and schedule implications. It was found that the base plate was indeed loose because of improper grouting during its initial installation. The base plate was modified by splitting it into multiple sections, isolating the T0 chopper from the rest of the beam line, and each section was then reinstalled and re-grouted. After these modifications, the vibration levels were reduced by a factor of 30. The reduction in vibration level was sufficient to allow the Vision beam line to operate at full capacity for the first time since its completed construction date.

Van Hoy, Blake W [ORNL

2014-01-01T23:59:59.000Z

353

High-flux ptychographic imaging using the new 55 ?m-pixel detector `Lambda' based on the Medipix3 readout chip  

Science Journals Connector (OSTI)

The Large Area Medipix-Based Detector Array (Lambda) has been used in a ptychographic imaging experiment on solar-cell nanowires. By using a semi-transparent central stop, the high flux density provided by nano-focusing Kirkpatrick-Baez mirrors can be fully exploited for high-resolution phase reconstructions.

Wilke, R.N.

2014-09-12T23:59:59.000Z

354

ORNL - Restart of the High Flux Isotope Reactor 2-07  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

INDUSTRIAL SAFETY AND HYGIENE (IS&H) INDUSTRIAL SAFETY AND HYGIENE (IS&H) OBJECTIVE IS&H-1: The RRD industrial safety and hygiene (IS&H) program has been appropriately modified to reflect the CS modification and its reactor interface, sufficient numbers of qualified IS&H staff and management are provided, and adequate IS&H facilities and equipment are available to ensure services are adequate to support reactor operation with the CS. The IS&H functions, assignments, responsibilities, and reporting relationships are clearly defined, understood, and effectively implemented with line management control of safety. IS&H staff and management exhibit awareness of applicable requirements pertaining to reactor operation with the CS and the associated hazards. Through their actions, they have demonstrated a high-

355

ORNL - Restart of the High Flux Isotope Reactor 2-07  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

OPERATIONS OPERATIONS OBJECTIVE OP-1: Operations staff and management exhibit awareness of applicable requirements pertaining to CS operation, hazards, and reactor operations with the hydrogen-moderated CS. Through their actions, they have demonstrated a high-priority commitment to comply with these requirements. The level of knowledge of reactor operations and CS system operations managers and staff related to CS operations, hazards, and reactor operations with the hydrogen-moderated CS is adequate based on interviews. Sufficient numbers of qualified reactor operations and CS system operations staff and management are available to conduct and support safe operations with the hydrogen-moderated CS. (CR - 1, CR - 4, CR - 6) Criteria * Minimum staffing requirements have been established for operations and support

356

ORNL - Restart of the High Flux Isotope Reactor 2-07  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Occupational Safety & Health Occupational Safety & Health OBJECTIVE ESH-1: Personnel exhibit an awareness of public and worker safety and health requirements and, through their actions, demonstrate a high-priority commitment to comply with these requirements. (Should also be coordinated with OP-1, MT-1, AB-2, EP-1, and ES-2) (CR-1) Criteria Personnel understand their right and responsibility to identify safety issues and invoke work suspension and stop work authority when necessary. Personnel anticipate, recognize, evaluate, and appropriately respond to hazards that may be present in the work place. Approach Record Review: Review the site policies and procedures which promote the identification and promulgation of safety concerns and work suspension and stop work

357

Geek-Up[1.28.2011]: Neutron Scattering and Full-Spectrum Solar Cells |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

.28.2011]: Neutron Scattering and Full-Spectrum Solar .28.2011]: Neutron Scattering and Full-Spectrum Solar Cells Geek-Up[1.28.2011]: Neutron Scattering and Full-Spectrum Solar Cells January 28, 2011 - 5:11pm Addthis Detector tanks for the new SANS instruments at the High Flux Isotope Reactor. The Bio-SANS detector is on the right. Source: ORNL Detector tanks for the new SANS instruments at the High Flux Isotope Reactor. The Bio-SANS detector is on the right. Source: ORNL Niketa Kumar Niketa Kumar Public Affairs Specialist, Office of Public Affairs Oak Ridge National Lab and North Carolina State University scientists are helping to develop medicines that will block the spread of viruses. Using the Bio-SANS instrument at ORNL's High Flux Isotope Reactor, these researchers are studying how viruses change their structure as they move

358

Device for Writing the Time Tail from Spallation Neutron Pulses  

SciTech Connect

Recent work at Los Alamos Neutron Science Center (LANSCE), has shown that there are large gains in neutron beam intensity to be made by using coupled moderators at spallation neutron sources. Most of these gains result from broadening the pulse-width in time. However the accompanying longer exponential tail at large emission times can be a problem in that it introduces relatively large beam-related backgrounds at high resolutions. We have designed a device that can reshape the moderated neutron beam by cutting the time-tail so that a sharp time resolution can be re-established without a significant loss in intensity. In this work the basic principles behind the tail-cutter and some initial results of Monte Carlo simulations are described. Unwanted neutrons in the long time-tail are diffracted out of the transmitted neutron beam by a nested stack of aperiodic multi-layers, rocking at the same frequency as the source. Nested aperiodic multi-layers have recently been used at X-ray sources and as band-pass filters in quasi-Laue neutron experiments at reactor neutron sources. Optical devices that rock in synchronization with a pulsed neutron beam are relatively new but are already under construction at LANSCE. The tail-cutter described here is a novel concept that uses existing multi-layer technology in a new way for spallation neutrons. Coupled moderators in combination with beam shaping devices offer the means of increasing flux whilst maintaining a sharp time distribution. A prototype device is being constructed for the protein crystallography station at LANSCE. The protein crystallography station incorporates a water moderator that has been judiciously coupled in order to increase the flux over neutron energies that are important to structural biology (3-80meV). This development in moderator design is particularly important because protein crystallography is flux limited and because conventional ambient water and cold hydrogen moderators do not provide relatively large neutron fluxes over this neutron energy range.

Langan, P. (Paul); Schoenborn, Benno P.; Langan, P. (Paul); Schoenborn, Benno P.; Daemen, L. L. (Luc L.)

2001-01-01T23:59:59.000Z

359

Floating Refrigerant Loop Based on R-134a Refrigerant Cooling of High-Heat Flux Electronics  

SciTech Connect

The Oak Ridge National Laboratory (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) have been developing technologies to address the thermal issues associated with hybrid vehicles. Removal of the heat generated from electrical losses in traction motors and their associated power electronics is essential for the reliable operation of motors and power electronics. As part of a larger thermal control project, which includes shrinking inverter size and direct cooling of electronics, ORNL has developed U.S. Patent No. 6,772,603 B2, ''Methods and Apparatus for Thermal Management of Vehicle Systems and Components'' [1], and patent pending, ''Floating Loop System for Cooling Integrated Motors and Inverters Using Hot Liquid Refrigerant'' [2]. The floating-loop system provides a large coefficient of performance (COP) for hybrid-drive component cooling. This loop (based on R-134a) is integrated with a vehicle's existing air-conditioning (AC) condenser, which dissipates waste heat to the ambient air. Because the temperature requirements for cooling of power electronics and electric machines are not as low as that required for passenger compartment air, this adjoining loop can operate on the high-pressure side of the existing AC system. This arrangement also allows the floating loop to run without the need for the compressor and only needs a small pump to move the liquid refrigerant. For the design to be viable, the loop must not adversely affect the existing system. The loop should also provide a high COP, a flat-temperature profile, and low-pressure drop. To date, the floating-loop test prototype has successfully removed 2 kW of heat load in a 9 kW automobile passenger AC system with and without the automotive AC system running. The COP for the tested floating-loop system ranges from 40-45, as compared to a typical AC system COP of about 2-4. The estimated required waste-heat load for future hybrid applications is 5.5 kW and the existing system could be easily scaleable for this larger load.

Lowe, K.T.

2005-10-07T23:59:59.000Z

360

Large break loss of coolant severe accident sequences at the HFIR (High Flux Isotope Reactor)  

SciTech Connect

An assessment of many potential HFIR severe accident phenomena was conducted during the HFIR design effort, and many severe accident mitigating features were designed into the plant. These evaluation typically incorporated a bounding'' or highly conservative analysis approach and employed tools and techniques representative of the state of knowledge in the mid-1960s. Recently, programs to address severe accident issues were initiated at the Oak Ridge National Laboratory (ORNL) to support the HFIR probabilistic risk assessment (PRA) and equipment qualification and accident management studies. This paper presents the results of environment condition calculations conducted to evaluate a response of HFIR's heat exchanger cell environment to a double-ended rupture of a 0.25 m diameter coolant loop downstream of the circulating pump and check valve. The confinement calculations were performed using an atmospheric fission product source for the heat exchanger cell consistent with, but more conservative than that stipulated in Regulatory Guide 1.89. The results of the calculations indicate that the heat exchanger cell atmospheric temperature peaks at 377 K 225 seconds into the transient and then begins decreasing at approximately 1.7 K per minute. 8 refs., 5 figs.

Simpson, D.B.; Greene, S.R.

1990-01-01T23:59:59.000Z

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361

Dense plasma heating and Gbar shock formation by a high intensity flux of energetic electrons  

SciTech Connect

Process of shock ignition in inertial confinement fusion implies creation of a high pressure shock with a laser spike having intensity of the order of a few PW/cm{sup 2}. However, the collisional (Bremsstrahlung) absorption at these intensities is inefficient and a significant part of laser energy is converted in a stream of energetic electrons. The process of shock formation in a dense plasma by an intense electron beam is studied in this paper in a planar geometry. The energy deposition takes place in a fixed mass target layer with the areal density determined by the electron range. A self-similar isothermal rarefaction wave of a fixed mass describes the expanding plasma. Formation of a shock wave in the target under the pressure of expanding plasma is described. The efficiency of electron beam energy conversion into the shock wave energy depends on the fast electron energy and the pulse duration. The model is applied to the laser produced fast electrons. The fast electron energy transport could be the dominant mechanism of ablation pressure creation under the conditions of shock ignition. The shock wave pressure exceeding 1 Gbar during 200–300 ps can be generated with the electron pulse intensity in the range of 5–10 PW/cm{sup 2}. The conclusions of theoretical model are confirmed in numerical simulations with a radiation hydrodynamic code coupled with a fast electron transport module.

Ribeyre, X.; Feugeas, J.-L.; Nicolaï, Ph.; Tikhonchuk, V. T. [University Bordeaux-CNRS-CEA, CELIA, UMR 5107, 33405 Talence (France)] [University Bordeaux-CNRS-CEA, CELIA, UMR 5107, 33405 Talence (France); Gus'kov, S. [University Bordeaux-CNRS-CEA, CELIA, UMR 5107, 33405 Talence (France) [University Bordeaux-CNRS-CEA, CELIA, UMR 5107, 33405 Talence (France); P. N. Lebedev Physical Institute RAS, 53, Leninskii Prospect, Moscow 119991 (Russian Federation)

2013-06-15T23:59:59.000Z

362

Development of CFD models to support LEU Conversion of ORNL s High Flux Isotope Reactor  

SciTech Connect

The US Department of Energy s National Nuclear Security Administration (NNSA) is participating in the Global Threat Reduction Initiative to reduce and protect vulnerable nuclear and radiological materials located at civilian sites worldwide. As an integral part of one of NNSA s subprograms, Reduced Enrichment for Research and Test Reactors, HFIR is being converted from the present HEU core to a low enriched uranium (LEU) core with less than 20% of U-235 by weight. Because of HFIR s importance for condensed matter research in the United States, its conversion to a high-density, U-Mo-based, LEU fuel should not significantly impact its existing performance. Furthermore, cost and availability considerations suggest making only minimal changes to the overall HFIR facility. Therefore, the goal of this conversion program is only to substitute LEU for the fuel type in the existing fuel plate design, retaining the same number of fuel plates, with the same physical dimensions, as in the current HFIR HEU core. Because LEU-specific testing and experiments will be limited, COMSOL Multiphysics was chosen to provide the needed simulation capability to validate against the HEU design data and previous calculations, and predict the performance of the proposed LEU fuel for design and safety analyses. To achieve it, advanced COMSOL-based multiphysics simulations, including computational fluid dynamics (CFD), are being developed to capture the turbulent flows and associated heat transfer in fine detail and to improve predictive accuracy [2].

Khane, Vaibhav B [ORNL] [ORNL; Jain, Prashant K [ORNL] [ORNL; Freels, James D [ORNL] [ORNL

2012-01-01T23:59:59.000Z

363

Neutron Damage in Mechanically-Cooled High-Purity Germanium Detectors for Field-Portable Prompt Gamma Neutron Activation Analysis (PGNAA) Systems  

SciTech Connect

Prompt Gamma Neutron Activation (PGNAA) systems require the use of a gamma-ray spectrometer to record the gamma-ray spectrum of an object under test and allow the determination of the object’s composition. Field-portable systems, such as Idaho National Laboratory’s PINS system, have used standard liquid-nitrogen-cooled high-purity germanium (HPGe) detectors to perform this function. These detectors have performed very well in the past, but the requirement of liquid-nitrogen cooling limits their use to areas where liquid nitrogen is readily available or produced on-site. Also, having a relatively large volume of liquid nitrogen close to the detector can impact some assessments, possibly leading to a false detection of explosives or other nitrogen-containing chemical. Use of a mechanically-cooled HPGe detector is therefore very attractive for PGNAA applications where nitrogen detection is critical or where liquid-nitrogen logistics are problematic. Mechanically-cooled HPGe detectors constructed from p-type germanium, such as Ortec’s trans-SPEC, have been commercially available for several years. In order to assess whether these detectors would be suitable for use in a fielded PGNAA system, Idaho National Laboratory (INL) has been performing a number of tests of the resistance of mechanically-cooled HPGe detectors to neutron damage. These detectors have been standard commercially-available p-type HPGe detectors as well as prototype n-type HPGe detectors. These tests compare the performance of these different detector types as a function of crystal temperature and incident neutron fluence on the crystal.

E.H. Seabury; C.J. Wharton; A.J. Caffrey; J.B. McCabe; C. DeW. Van Siclen

2013-10-01T23:59:59.000Z

364

Advanced Thomson scattering system for high-flux linear plasma generator  

SciTech Connect

An advanced Thomson scattering system has been built for a linear plasma generator for plasma surface interaction studies. The Thomson scattering system is based on a Nd:YAG laser operating at the second harmonic and a detection branch featuring a high etendue (f /3) transmission grating spectrometer equipped with an intensified charged coupled device camera. The system is able to measure electron density (n{sub e}) and temperature (T{sub e}) profiles close to the output of the plasma source and, at a distance of 1.25 m, just in front of a target. The detection system enables to measure 50 spatial channels of about 2 mm each, along a laser chord of 95 mm. By summing a total of 30 laser pulses (0.6 J, 10 Hz), an observational error of 3% in n{sub e} and 6% in T{sub e} (at n{sub e}= 9.4 Multiplication-Sign 10{sup 18} m{sup -3}) can be obtained. Single pulse Thomson scattering measurements can be performed with the same accuracy for n{sub e} > 2.8 Multiplication-Sign 10{sup 20} m{sup -3}. The minimum measurable density and temperature are n{sub e} < 1 Multiplication-Sign 10{sup 17} m{sup -3} and T{sub e} < 0.07 eV, respectively. In addition, using the Rayleigh peak, superimposed on the Thomson scattered spectrum, the neutral density (n{sub 0}) of the plasma can be measured with an accuracy of 25% (at n{sub 0}= 1 Multiplication-Sign 10{sup 20} m{sup -3}). In this report, the performance of the Thomson scattering system will be shown along with unprecedented accurate Thomson-Rayleigh scattering measurements on a low-temperature argon plasma expansion into a low-pressure background.

Meiden, H. J. van der; Lof, A. R.; Berg, M. A. van den; Brons, S.; Eck, H. J. N. van; Koelman, P. M. J.; Koppers, W. R.; Kruijt, O. G.; Oyevaar, T.; Prins, P. R.; Rapp, J.; Scholten, J.; Smeets, P. H. M.; Star, G. van der; Zeijlmans van Emmichoven, P. A. [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Donne, A. J. H.; Schram, D. C. [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Eindhoven University of Technology, Eindhoven (Netherlands); Naumenko, N. N. [IPh NASB, Minsk (Belarus); Tugarinov, S. N. [SRC TRINITI, Troitsk, Moscow Reg. (Russian Federation)

2012-12-15T23:59:59.000Z

365

High resolution fossil fuel combustion CO2 emission fluxes for the United States  

SciTech Connect

Quantification of fossil fuel CO{sub 2} emissions at fine space and time resolution is emerging as a critical need in carbon cycle and climate change research. As atmospheric CO{sub 2} measurements expand with the advent of a dedicated remote sensing platform and denser in situ measurements, the ability to close the carbon budget at spatial scales of {approx}100 km{sup 2} and daily time scales requires fossil fuel CO{sub 2} inventories at commensurate resolution. Additionally, the growing interest in U.S. climate change policy measures are best served by emissions that are tied to the driving processes in space and time. Here we introduce a high resolution data product (the 'Vulcan' inventory: www.purdue.edu/eas/carbon/vulcan/) that has quantified fossil fuel CO{sub 2} emissions for the contiguous U.S. at spatial scales less than 100 km{sup 2} and temporal scales as small as hours. This data product, completed for the year 2002, includes detail on combustion technology and 48 fuel types through all sectors of the U.S. economy. The Vulcan inventory is built from the decades of local/regional air pollution monitoring and complements these data with census, traffic, and digital road data sets. The Vulcan inventory shows excellent agreement with national-level Department of Energy inventories, despite the different approach taken by the DOE to quantify U.S. fossil fuel CO{sub 2} emissions. Comparison to the global 1{sup o} x 1{sup o} fossil fuel CO{sub 2} inventory, used widely by the carbon cycle and climate change community prior to the construction of the Vulcan inventory, highlights the space/time biases inherent in the population-based approach.

Gurney, Kevin R.; Mendoza, Daniel L.; Zhou, Yuyu; Fischer, Marc L.; Miller, Chris C.; Geethakumar, Sarath; de la Rue du Can, Stephane

2009-03-19T23:59:59.000Z

366

Validation of a Monte Carlo based depletion methodology via High Flux Isotope Reactor HEU post-irradiation examination measurements  

SciTech Connect

The purpose of this study is to validate a Monte Carlo based depletion methodology by comparing calculated post-irradiation uranium isotopic compositions in the fuel elements of the High Flux Isotope Reactor (HFIR) core to values measured using uranium mass-spectrographic analysis. Three fuel plates were analyzed: two from the outer fuel element (OFE) and one from the inner fuel element (IFE). Fuel plates O-111-8, O-350-1, and I-417-24 from outer fuel elements 5-O and 21-O and inner fuel element 49-I, respectively, were selected for examination. Fuel elements 5-O, 21-O, and 49-1 were loaded into HFIR during cycles 4, 16, and 35, respectively (mid to late 1960s). Approximately one year after each of these elements were irradiated, they were transferred to the High Radiation Level Examination Laboratory (HRLEL) where samples from these fuel plates were sectioned and examined via uranium mass-spectrographic analysis. The isotopic composition of each of the samples was used to determine the atomic percent of the uranium isotopes. A Monte Carlo based depletion computer program, ALEPH, which couples the MCNP and ORIGEN codes, was utilized to calculate the nuclide inventory at the end-of-cycle (EOC). A current ALEPH/MCNP input for HFIR fuel cycle 400 was modified to replicate cycles 4, 16, and 35. The control element withdrawal curves and flux trap loadings were revised, as well as the radial zone boundaries and nuclide concentrations in the MCNP model. The calculated EOC uranium isotopic compositions for the analyzed plates were found to be in good agreement with measurements, which reveals that ALEPH/MCNP can accurately calculate burn-up dependent uranium isotopic concentrations for the HFIR core. The spatial power distribution in HFIR changes significantly as irradiation time increases due to control element movement. Accurate calculation of the end-of-life uranium isotopic inventory is a good indicator that the power distribution variation as a function of space and time is accurately calculated, i.e. an integral check. Hence, the time dependent heat generation source terms needed for reactor core thermal hydraulic analysis, if derived from this methodology, have been shown to be accurate for highly enriched uranium (HEU) fuel.

Chandler, David [ORNL; Maldonado, G Ivan [ORNL; Primm, Trent [ORNL

2010-01-01T23:59:59.000Z

367

Design of a high particle flux hydrogen helicon plasma source for used in plasma materials interaction studies  

SciTech Connect

Existing linear plasma materials interaction (PMI) facilities all use plasma sources with internal electrodes. An rf-based helicon source is of interest because high plasma densities can be generated with no internal electrodes, allowing true steady state operation with minimal impurity generation. Work has begun at Oak Ridge National Laboratory (ORNL) to develop a large (15 cm) diameter helicon source producing hydrogen plasmas with parameters suitable for use in a linear PMI device: n{sub e}{>=}10{sup 19} m{sup -3}, T{sub e} = 4-10 eV, particle flux {gamma}{sub p}>10{sup 23}m{sup -3} s{sup -1}, and magnetic field strength |B| up to 1 T in the source region. The device, whose design is based on a previous hydrogen helicon source operated at ORNL[1], will operate at rf frequencies in the range 10-26 MHz, and power levels up to {approx}100 kW. Limitations in cooling will prevent operation for pulses longer than several seconds, but a major goal will be the measurement of power deposition on device structures so that a later steady state version can be designed. The device design, the diagnostics to be used, and results of rf modeling of the device will be discussed. These include calculations of plasma loading, resulting currents and voltages in antenna structures and the matching network, power deposition profiles, and the effect of high |B| operation on power absorption.

Goulding, R. H.; Chen, G.; Meitner, S.; Baity, F. W.; Caughman, J. B. O.; Owen, L. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6169 (United States)

2009-11-26T23:59:59.000Z

368

A balloon borne detector to determine high energy neutrons in energy and direction  

Science Journals Connector (OSTI)

A balloon borne experiment for the measurement of solar and atmospheric neutrons in energy and direction above 50 MeV is described. The principle of measurement is the double elastic scattering process of the incoming neutrons with hydrogen atoms. For the registration of the recoil protons spark chambers are used. The hydrogen is contained in thin plastic scintillator and polyethylene plates, which are inserted between the spark chambers. The sparks are recorded photographically from two sides. A detailed description of the design of the experiment is given. The properties of the apparatus were determined by atmospheric neutron measurements at ground level.

E. Heidbreder; K. Pinkau; C. Reppin; V. Schönfelder

1970-01-01T23:59:59.000Z

369

Neutron diffraction measurements of residual stresses in welds fabricated from highly anisotropic materials  

NLE Websites -- All DOE Office Websites (Extended Search)

neutron diffraction to neutron diffraction to engineering problems T.M. Holden Northern Stress Technologies Deep River, Ontario, Canada Oak Ridge National Laboratory, 13 nd June 2011 Reference material * "Introduction to the characterization of residual stress by neutron diffraction". M.T. Hutchings, P.J. Withers, T.M. Holden and T. Lorentzen, (Taylor and Francis: Boca Raton) 2005 * "Introduction to diffraction in Materials Science and Engineering", A.D. Krawitz (John Wiley and Sons ,Inc.: New York) 2001 * "Non-destructive testing-Standard Test Method for

370

Neutron scattering investigation of high-frequency dynamics in glassy glucose  

Science Journals Connector (OSTI)

The vibrational dynamics of vitreous glucose has been investigated by means of inelastic neutron scattering experiments, exploiting the coherent scattering cross section of deuterium in a fully deuterated sample and the high incoherent scattering cross section of hydrogen in a hydrogenated sample. The first part of the experiment allowed a rather detailed investigation of the collective dynamics in the THz range. The second part of the experiment was used to derive some information on the vibrational density of states of the system. The experiment confirms the presence of a propagating vibrational mode which is the natural extension at THz frequencies of the lower frequencies longitudinal sound mode. In addition, a second mode is also observed at a lower and almost constant frequency, showing an increasing intensity on reducing the wavelength. By comparing the dispersion relations of these collective modes to the experimental density of states, a possible relation between the low frequency mode and the well known excess of low frequency modes, that is, the boson peak, is identified.

N. Violini; A. Orecchini; A. Paciaroni; C. Petrillo; F. Sacchetti

2012-04-17T23:59:59.000Z

371

Flux, Volume 1, Issue 1  

NLE Websites -- All DOE Office Websites (Extended Search)

&24; Table of Contents flux a publication of the national high magnetic field laboratory PG. 3 ... What is Flux? An introduction to our new publication. PG. 4 ... How Magnet...

372

High-pressure neutron diffraction study on H–D isotope effects in brucite  

Science Journals Connector (OSTI)

A neutron powder diffraction study of hydrogenated and deuterated brucite was conducted at ambient temperature and at...a axis, parallel to the sheets of Mg–O octahedra, decrease only slightly with pressure with ...

Juske Horita; António M. dos Santos…

2010-12-01T23:59:59.000Z

373

Ultrafast neutron detector  

DOE Patents (OSTI)

A neutron detector of very high temporal resolution is described. It may be used to measure distributions of neutrons produced by fusion reactions that persist for times as short as about 50 picoseconds.

Wang, C.L.

1985-06-19T23:59:59.000Z

374

RELATIVE ATTENUATION CHARACTERISTICS OF SOME SHIELDING MATERIALS FOR PuB NEUTRONS  

E-Print Network (OSTI)

for the Neutron Conversion Factors," Health Physics Flux-to~to dose-equivalent conversion factors are those taken fromsion factors " The conversion factors for neutrons

Bringham, P.S.

2010-01-01T23:59:59.000Z

375

Calculation of sensitivity coefficients for a neutron well logging tool  

E-Print Network (OSTI)

(Lsmsrsh, 1966; Bartine et al. , 1974; Duderstadt et al. , 1976). The straightforward (direct) calculation requires knowledge of the forward neutron flux, neutron cross section data, and detector responses (such as reaction rates) for each situation, i.... e. , the detector's responses are repeatedly com- puted for each change in the formation's composition. The perturbation (indirect) method requires knowledge of the forward neutron flux, detector response, and sd- joint neutron flux for a base...

Chen, Chien-Hsiang

2012-06-07T23:59:59.000Z

376

A Review of Proposed Upgrades to the High Flux Isotope Reactor and Potential Impacts to Reactor Vessel Integrity  

SciTech Connect

The High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) was scheduled in October 2000 to implement design upgrades that include the enlargement of the HB-2 and HB-4 beam tubes. Higher dose rates and higher radiation embrittlement rates were predicted for the two beam-tube nozzles and surrounding vessel areas. ORNL had performed calculations for the upgraded design to show that vessel integrity would be maintained at acceptable levels. Pacific Northwest National Laboratory (PNNL) was requested by the U.S. Department of Energy Headquarters (DOE/HQ) to perform an independent peer review of the ORNL evaluations. PNNL concluded that the calculated probabilities of failure for the HFIR vessel during hydrostatic tests and for operational conditions as estimated by ORNL are an acceptable basis for selecting pressures and test intervals for hydrostatic tests and for justifying continued operation of the vessel. While there were some uncertainties in the embrittlement predictions, the ongoing efforts at ORNL to measure fluence levels at critical locations of the vessel wall and to test materials from surveillance capsules should be effective in dealing with embrittlement uncertainties. It was recommended that ORNL continue to update their fracture mechanics calculations to reflect methods and data from ongoing research for commercial nuclear power plants. Such programs should provide improved data for vessel fracture mechanics calculations.

Simonen, Fredric A.

2001-05-31T23:59:59.000Z

377

Experimental results with cryogenically cooled, thin, silicon crystal x-ray monochromators on high-heat-flux beamlines  

SciTech Connect

A novel, silicon crystal monochromator has been designed and tested for use on undulator and focused wiggler beamlines at third-generation synchrotron sources. The crystal utilizes a thin, partially transmitting diffracting element fabricated within a liquid-nitrogen cooled, monolithic block of silicon. This report summarizes the results from performance tests conducted at the European Synchrotron Radiation Facility (ESRF) using a focused wiggler beam and at the Advanced Photon Source (APS) on an undulator beamline. These experiments indicate that a cryogenic crystal can handle the very high power and power density x-ray beams of modem synchrotrons with sub-arcsec thermal broadening of the rocking curve. The peak power density absorbed on the surface of the crystal at the ESRF exceeded go W/mm{sup 2} with an absorbed power of 166 W, this takes into account the spreading of the beam due to the Bragg angle of 11.4{degrees}. At the APS, the peak heat flux incident on the crystal was 1.5 W/mA/mm{sup 2} with a power of 6.1 W/mA for a 2.0 H x 2.5 V mm{sup 2} beam at an undulator gap of 11.1 mm and stored current up to 96 mA.

Rogers, C.S.; Mills, D.M.; Lee, W.K.; Fernandez, P.B.; Graber, T.

1996-08-01T23:59:59.000Z

378

HEXOS—Humidity Exchange Over the Sea A Program for Research on Water-Vapor and Droplet Fluxes from Sea of Air at Moderate to High Wind Speeds  

Science Journals Connector (OSTI)

HEXOS is an international program for the study of evaporation and spray-droplet flux from sea to air. The program includes measurements in the field at moderate-to-high wind speeds, wind-tunnel studies, instrument development, boundary-layer ...

Kristina B. Katsaros; Stuart D. Smith; Wiebe A. Oost

1987-05-01T23:59:59.000Z

379

Capabilities of the ARCS Instrument - ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Capabilities of the ARCS Instrument Capabilities of the ARCS Instrument ARCS Overview The wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source (SNS) is optimized to provide a high neutron flux at the sample position with a large solid angle of detector coverage. The instrument incorporates modern neutron instrumentation, such as an elliptically focused neutron guide, high speed magnetic bearing choppers, and a massive array of 3He linear position sensitive detectors. Novel features of the spectrometer include the use of a large gate valve between the sample and detector vacuum chambers and the placement of the detectors within the vacuum, both of which provide a window-free final flight path to minimize background scattering while allowing rapid changing of the sample and

380

High resolution neutron imaging of water in the polymer electrolyte membrane  

SciTech Connect

To achieve a deeper understanding of water transport and performance issues associated with water management, we have conducted in situ water examinations to help understand the effects of components and operation. High Frequency Resistance (HFR), AC Impedance and neutron radiography were used to measure water content in operating fuel cells under various operating conditions. Variables examined include: sub-freezing conditions, inlet relative humidities, cell temperature, current density and response transients, different flow field orientations and different component materials (membranes, GDLs and MEAs). Quantification of the water within the membrane was made by neutron radiography after equilibration to different humidified gases, during fuel cell operation and in hydrogen pump mode. The water content was evaluated in bare Nafion{reg_sign} membranes as well as in MEAs operated in both fuel cell and H{sub 2} pump mode. These in situ imaging results allow measurement of the water content and gradients in the PEFC membrane and relate the membrane water transport characteristics to the fuel cell operation and performance under disparate materials and operational combinations. Flow geometry makes a large impact on MEA water content. Higher membrane water with counter flow was measured compared with co-flow for sub-saturated inlet RH's. This correlates to lower HFR and higher performance compared with co-flow. Higher anode stoichiometry helps remove water which accumulates in the anode channels and GDL material. Cell orientation was measured to affect both the water content and cell performance. While membrane water content was measured to be similar regardless of orientation, cells with the cathode on top show flooding and loss of performance compared with similarly operated cells with the anode on top. Transient fuel cell current measurements show a large degree of hysteresis in terms of membrane hydration as measured by HFR. Current step transients from 0.01 A cm{sup -2} to 0.68 A cm{sup -2} consistently show PEM wetting occurring within 5 to 20 sec. Whereas the PEM drying response to the reverse step transient of 0.68 A cm{sup -2} to 0.01 A cm{sup -2}, takes several minutes. The observed faster wetting response is due to reaction water being produced in the cathode and back diffusing into the membrane. The slower PEM drying is due to the water slowly being removed out of the wetted GDLs. This rate of removal of water and hence the PEM hydration level was found to be influenced strongly by the PTFE loadings in the GDL substrate and Microporous layer (MPL). The drying of the membrane is influenced by both the anode and cathode GDL PTFE loadings. Lower PTFE loading in the anode GDL leads to better membrane hydration probably due to the easier incorporation of water from the anode GDL into the membrane. Similarly a lower PTFE loading in the cathode GDL also results in better membrane hydration probably due to the better water retention properties (less hydrophobic) of this GDL. Fuel cells operated isothermal at sub-freezing temperatures show gradual cell performance decay over time and eventually drops to zero. AC impedance analysis indicates that losses are initially due to increasing charge transfer resistance. After time, the rate of decay accelerates rapidly due to mass transport limitations. High frequency resistance also increases over time and is a function of the initial membrane water content. These results indicate that catalyst layer ice formation is influenced strongly by the MEA and is responsible for the long-term degradation of fuel cells operated at sub-freezing temperatures. Water distribution measurements indicate that ice may be fonning mainly in the GDLs at -10 C but are concentrated in the catalyst layer at -20 C.

Spernjak, Dusan [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory; Borup, Rodney L [Los Alamos National Laboratory; Spendelow, Jacob S [Los Alamos National Laboratory; Davey, John [Los Alamos National Laboratory; Fairweather, Joseph [Los Alamos National Laboratory; Mukherjee, Partha [ORNL

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
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381

News & Events | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

8 News 8 News Neutron Science In the News - 2008 November October September August July June May March February January Because some media sources archive past articles and require a subscription for access, some of the links below might not be active. If a citation listed here is no longer available, please contact the newspaper or your library directly. October Research Visits Just Budding at Spallation Neutron Source Knoxville News Sentinel 10/29 When the Spallation Neutron Source was in the proposal stage and under construction, its supporters said the $1.4 billion research complex would eventually attract about 2,000 scientists a year to Oak Ridge to perform experiments and otherwise do their thing. That number, as I recall, was lumped together with researchers at the recently upgraded High Flux Isotope

382

Biotechnology & Energy Highlights | Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Biotechnology & Energy Biotechnology & Energy SHARE Biotechnology and Energy Highlights 1-10 of 10 Results Neutron Imaging Reveals Lithium Distribution in Lithium-Air Electrodes January 01, 2013 - Using neutron-computed tomography, researchers at the CG-1D neutron imaging instrument at Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR) have successfully mapped the three-dimensional spatial distribution of lithium products in electrochemically discharged lithium-air cathodes. Theory meets experiment: structure-property relationships in an electrode material for solid-oxide fuel cells December 01, 2012 - Fuel cell technology is one potentially very efficient and environmentally friendly way to convert the chemical energy of fuels into electricity. Solid-oxide fuel cells (SOFCs) can convert a

383

Deuterium Depth Profile in Neutron-Irradiated Tungsten Exposed to Plasma  

SciTech Connect

The effect of radiation damage has been mainly simulated using high-energy ion bombardment. The ions, however, are limited in range to only a few microns into the surface. Hence, some uncertainty remains about the increase of trapping at radiation damage produced by 14 MeV fusion neutrons, which penetrate much farther into the bulk material. With the Japan-US joint research project: Tritium, Irradiations, and Thermofluids for America and Nippon (TITAN), the tungsten samples (99.99 % pure from A.L.M.T., 6mm in diameter, 0.2mm in thickness) were irradiated to high flux neutrons at 50 C and to 0.025 dpa in the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL). Subsequently, the neutron-irradiated tungsten samples were exposed to a high-flux deuterium plasma (ion flux: 1021-1022 m-2s-1, ion fluence: 1025-1026 m-2) in the Tritium Plasma Experiment (TPE) at the Idaho National Laboratory (INL). First results of deuterium retention in neutron-irradiated tungsten exposed in TPE have been reported previously. This paper presents the latest results in our on-going work of deuterium depth profiling in neutron-irradiated tungsten via nuclear reaction analysis. The experimental data is compared with the result from non neutron-irradiated tungsten, and is analyzed with the Tritium Migration Analysis Program (TMAP) to elucidate the hydrogen isotope behavior such as retention and depth distribution in neutron-irradiated and non neutron-irradiated tungsten.

Masashi Shimada; G. Cao; Y. Hatano; T. Oda; Y. Oya; M. Hara; P. Calderoni

2011-05-01T23:59:59.000Z

384

A Neutron Based Scanner to Detect Explosives in Small, Sealed Containers  

SciTech Connect

A scanning system has been designed for portal protection applications, with the capability of detecting explosive materials after an initial scan of 30 seconds. The scanner operates using the principle of neutron induced return gamma-ray spectrometry. This system utilizes high purity germanium detectors, a neutron generator based on deuterium-tritium fusion and a unique neutron reflector and guide design. The neutron reflector amplifies the flux and alters the energy spectrum of neutrons produced by the generator. A depleted uranium reflector is shown to perform 7.3 times better than no reflector, and is found to perform 1.5 times better than a tungsten reflector using MCNP simulation. This improvement is due to neutron knockout and induced fission occurring in depleted uranium. The system is capable of detecting 300 g of explosives with 90% detection probability, which includes a 15% rescan rate after a 30 second initial scan.

Koltick, D.; Sword, E. [Physics Department, Purdue University 525 Northwestern Avenue, West Lafayette, IN 47907 (United States)

2009-03-10T23:59:59.000Z

385

DENSE OPTICAL AND NEAR-INFRARED MONITORING OF CTA 102 DURING HIGH STATE IN 2012 WITH OISTER: DETECTION OF INTRA-NIGHT ''ORPHAN POLARIZED FLUX FLARE''  

SciTech Connect

CTA 102, classified as a flat spectrum radio quasar at z = 1.037, produced an exceptionally bright optical flare in 2012 September. Following the Fermi Large Area Telescope detection of enhanced {gamma}-ray activity, we closely monitored this source in the optical and near-infrared bands for the 10 subsequent nights using 12 telescopes in Japan and South Africa. On MJD 56197 (2012 September 27, four to five days after the peak of bright {gamma}-ray flare), polarized flux showed a transient increase, while total flux and polarization angle (PA) remained almost constant during the ''orphan polarized-flux flare.'' We also detected an intra-night and prominent flare on MJD 56202. The total and polarized fluxes showed quite similar temporal variations, but the PA again remained constant during the flare. Interestingly, the PAs during the two flares were significantly different from the jet direction. The emergence of a new emission component with a high polarization degree (PD) up to 40% would be responsible for the observed two flares, and such a high PD indicates the presence of a highly ordered magnetic field at the emission site. We argue that the well-ordered magnetic field and even the observed directions of the PA, which is grossly perpendicular to the jet, are reasonably accounted for by transverse shock(s) propagating down the jet.

Itoh, Ryosuke; Fukazawa, Yasushi; Tanaka, Yasuyuki T. [Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Abe, Yuhei [Department of Cosmosciences, Graduate School of Science, Hokkaido University, Kita-ku, Sapporo 060-0810 (Japan); Akitaya, Hiroshi; Kawabata, Koji S.; Moritani, Yuki [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Arai, Akira [Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2 Nishigaichi, Sayo-cho, Sayo, Hyogo 679-5313 (Japan); Hayashi, Masahiko [National Astronomical Observatory of Japan, Osawa 2-21-2, Mitaka, Tokyo 181-8588 (Japan); Hori, Takafumi; Nakata, Chikako [Department of Astronomy, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Isogai, Mizuki [Koyama Astronomical Observatory, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto-City 603-8555 (Japan); Izumiura, Hideyuki; Kuroda, Daisuke [Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Honjo 3037-5, Kamogata, Asakuchi, Okayama 719-0232 (Japan); Kawai, Nobuyuki [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Miyanoshita, Ryo [Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065 (Japan); Morokuma, Tomoki [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Nagayama, Takahiro [Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Nakamoto, Jumpei [Department of Earth and Planetary Sciences, School of Science, Hokkaido University, Kita-ku, Sapporo 060-0810 (Japan); Oasa, Yumiko, E-mail: itoh@hep01.hepl.hiroshima-u.ac.jp [Faculty of Education, Saitama University, 255 Shimo-Okubo, Sakura, Saitama, 338-8570 (Japan); and others

2013-05-10T23:59:59.000Z

386

Fusion neutron irradiation of Ni(Si) alloys at high temperature  

SciTech Connect

Two Ni-4% Si alloys, with different cold work levels, are irradiated with 14 MeV fusion neutrons at 623 K, and their Curie temperatures are monitored during irradiation. The results are compared to those of an identical alloy irradiated by 2 MeV electrons. The results show that increasing dislocation density increases the Curie temperature change rate. At the same damage rate, the Curie temperature change rate for the alloy irradiated by 14 MeV fusion neutrons is only 6 to 7% of that for an identical alloy irradiated by 2 MeV electrons. It is well known that the migration of radiation induced defects contributes to segregation of silicon atoms at sinks in this alloy, causing the Curie temperature changes. The current results imply that the relative free defect production efficiency decreases from one for the electron irradiated sample to 6 to 7% for the fusion neutron irradiated sample. 17 refs., 4 figs., 1 tab.

Huang, J.S.; Guinan, M.W.; Hahn, P.A.

1987-09-01T23:59:59.000Z

387

Neutron scattering in Mineral Sciences:  

Science Journals Connector (OSTI)

...de WWW page: http://www.kfa-juelich.de FRG-1 Geesthacht (D) Type: Swimming Pool Cold Neutron Source. Flux: 8...Div. Wfn-Neutronscattering, GKSS Research Centre, 21502 Geesthacht, Germany Telephone: 49 (0) 4152 87 1316 / 2503 Fax: 49...

Romano RINALDI

388

Neutron imaging of alkali metal heat pipes  

SciTech Connect

High-temperature heat pipes are two-phase, capillary driven heat transfer devices capable of passively providing high thermal fluxes. Such a device using a liquid-metal coolant can be used as a solution for successful thermal management on hypersonic flight vehicles. Imaging of the liquid-metal coolant inside will provide valuable information in characterizing the detailed heat and mass transport. Neutron imaging possesses an inherent advantage from the fact that neutrons penetrate the heat pipe metal walls with very little attenuation, but are significantly attenuated by the liquid metal contained inside. Using the BT-2 beam line at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, preliminary efforts have been conducted on a nickel-sodium heat pipe. The contrast between the attenuated beam and the background is calculated to be approximately 3%. This low contrast requires sacrifice in spatial or temporal resolution so efforts have since been concentrated on lithium (Li) which has a substantially larger neutron attenuation cross section. Using the CG-1D beam line at the High Flux Isotope Reactor (HFIR) of Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, the first neutron images of high-temperature molybdenum (Mo)-Li heat pipes have been achieved. The relatively high neutron cross section of Li allows for the visualization of the Li working fluid inside the heat pipes. The evaporator region of a gravity assisted cylindrical heat pipe prototype 25 cm long was imaged from start-up to steady state operation up to approximately 900 C. In each corner of the square bore inside, the capillary action raises the Li meniscus above the bulk Li pool in the evaporator region. As the operational temperature changes, the meniscus shapes and the bulk meniscus height also changes. Furthermore, a three-dimensional tomographic image is also reconstructed from the total of 128 projection images taken 1.4o apart in which the Li had already cooled and solidified.

Kihm, Ken [University of Tennessee, Knoxville (UTK); Kirchoff, Eric [University of Tennessee, Knoxville (UTK); Golden, Matt [University of Tennessee, Knoxville (UTK); Rosenfeld, J. [Thermacore Inc.; Rawal, S. [Lockheed Martin Space Systems Company; Pratt, D. [United States Air Force Research Laboratory, Wright-Patterson Air Force Base; Bilheux, Hassina Z [ORNL; Walker, Lakeisha MH [ORNL; Voisin, Sophie [ORNL; Hussey, Dan [NIST Center for Neutron Research (NCRN), Gaithersburg, MD

2013-01-01T23:59:59.000Z

389

UA/ORNL Collaboration: Neutron Scattering Studies of Antiferromagnetic Films, Final Report  

SciTech Connect

The work reported here was a collaborative project between the research groups of Dr. J.L. Robertson at Oak Ridge National Laboratory and Dr. G.J. Mankey at the University of Alabama. The main thrust is developing neutron optical devices and materials for the study of magnetic thin films and interfaces. The project is particularly timely, since facility upgrades are currently underway at the High Flux Isotope Reactor. A new neutron optical device, a multicrystal analyzer, was designed and built to take maximum advantage of the increased flux that the upgraded beamlines at HFIR will provide. This will make possible detailed studies of the magnetic structure of thin films, multilayers, and interfaces that are not feasible at present. We performed studies of the antiferromagnetic order in thin films and crystals using neutron scattering, determined magnetic structures at interfaces with neutron reflectometry and measured order in magnetic dispersions using small angle neutron scattering. The collaboration has proved fruitful: generating eleven publications, contributing to the training of a postdoc who is now on staff at the High Flux Isotope Reactor and providing the primary support for two recent Ph.D. recipients. The collaboration is still vibrant, with anticipated implementation of the multicrystal analyzer on one of the new cold source beamlines at the High Flux Isotope Reactor.

Mankey, Gary J.

2006-07-26T23:59:59.000Z

390

Thermal Neutron Imaging in an Active Interrogation Environment  

SciTech Connect

We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of excitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutron-emitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

Vanier, Peter E. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Forman, Leon [Ion Focus Technology, Inc., Miller Place, NY 11764 (United States); Norman, Daren R. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States)

2009-03-10T23:59:59.000Z

391

High-accuracy mass measurements of neutron-rich Kr isotopes  

Science Journals Connector (OSTI)

The atomic masses of the neutron-rich krypton isotopes Kr84,86-95 have been determined with the tandem Penning trap mass spectrometer ISOLTRAP with uncertainties ranging from 20 to 220 ppb. The masses of the short-lived isotopes Kr94 and Kr95 were measured for the first time. The masses of the radioactive nuclides Kr89 and Kr91 disagree by 4 and 6 standard deviations, respectively, from the present Atomic-Mass Evaluation database. The resulting modification of the mass surface with respect to the two-neutron separation energies as well as implications for mass models and stellar nucleosynthesis are discussed.

P. Delahaye; G. Audi; K. Blaum; F. Carrel; S. George; F. Herfurth; A. Herlert; A. Kellerbauer; H.-J. Kluge; D. Lunney; L. Schweikhard; C. Yazidjian

2006-09-28T23:59:59.000Z

392

The DOS 1 neutron dosimetry experiment at the HB-4-A key 7 surveillance site on the HFIR pressure vessel  

SciTech Connect

A comprehensive neutron dosimetry experiment was made at one of the prime surveillance sites at the High Flux Isotope Reactor (HFIR) pressure vessel to aid radiation embrittlement studies of the vessel and to benchmark neutron transport calculations. The thermal neutron flux at the key 7, position 5 site was found, from measurements of radioactivation of four cobalt wires and four silver wires, to be 2.4 {times} 10{sup 12} n{center_dot}m{sup {minus}2}{center_dot}s{sup {minus}1}. The thermal flux derived from two helium accumulation monitors was 2.3 {times} 10{sup 12} n{center_dot}m{sup {minus}2}{center_dot}{sup {minus}1}. The thermal flux estimated by neutron transport calculations was 3.7 {times} 10{sup 12} n{center_dot}m{sup {minus}2}s{sup {minus}1}. The fast flux, >1 MeV, determined from two nickel activation wires, was 1.5 {times} 10{sup 12} n{center_dot}m{sup {minus}2}{center_dot}s{sup {minus}1}, in keeping with values obtained earlier from stainless steel surveillance monitors and with a computed value of 1.2 {times} 10{sup 13} n{center_dot}m{sup {minus}2}{center_dot}{sup {minus}1}. The fast fluxes given by two reaction-product-type monitors, neptunium-237 and beryllium, were 2.6 {times} 10{sup 13} n{center_dot}m{sup {minus}2}{center_dot}s {sup {minus}1} and 2.2 {times} 10{sup 13} n{center_dot}m{sup {minus}2}s{sup {minus}1}, respectively. Follow-up experiments indicate that these latter high values of fast flux are reproducible but are false; they are due to the creation of greater levels of reaction products by photonuclear events induced by an exceptionally high ratio of gamma flux to fast neutron flux at the vessel.

Farrell, K.; Kam, F.B.; Baldwin, C.A. [and others

1994-01-01T23:59:59.000Z

393

Method and apparatus for determining the content and distribution of a thermal neutron absorbing material in an object  

DOE Patents (OSTI)

The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The object is placed between the neutron generator and the neutron detector. The reduction in the neutron flux corresponds to the amount of thermal neutron absorbing material in the object. The object is advanced past the neutron generator and neutron detector to obtain neutron flux data for each segment of the object. The object may comprise a space reactor heat pipe and the thermal neutron absorbing material may comprise lithium.

Crane, T.W.

1983-12-21T23:59:59.000Z

394

Method and apparatus for determining the content and distribution of a thermal neutron absorbing material in an object  

DOE Patents (OSTI)

The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The object is placed between the neutron generator and the neutron detector. The reduction in the neutron flux corresponds to the amount of thermal neutron absorbing material in the object. The object is advanced past the neutron generator and neutron detector to obtain neutron flux data for each segment of the object. The object may comprise a space reactor heat pipe and the thermal neutron absorbing material may comprise lithium.

Crane, Thomas W. (Los Alamos, NM)

1986-01-01T23:59:59.000Z

395

The Transmutation of Nuclear Waste in the Two-Zone Subcritical System Driven by High- Intensity Neutron Generator - 12098  

SciTech Connect

The main problems of transmutation of high-level radioactive waste (minor actinides and long-lived fission products) are considered in our work. The range of radioactive waste of nuclear power is analyzed. The conditions under which the transmutation of radioactive waste will be most effective are analyzed too. The modeling results of a transmutation of the main radioactive isotopes are presented and discussed. The transmutation of minor actinides and long-lived fission products are modeled in our work (minor actinides - Np-237, Am-241, Am-242, Am-243, Cm-244, Cm-245; long-lived fission products - I-129, Tc-99). The two-zone subcritical system is calculated with help of different neutron-physical codes (MCNP, Scale, Montebarn, Origen). The ENDF/B-VI nuclear data library used in above calculations. Thus, radioactive wastes can be divided into two main groups that need to be transmuted. The minor actinides form the first group and the long-lived fission products form the second one. For the purpose of effective transmutation these isotopes must be extracted from the spent nuclear fuel with the help of either PUREX technology or pyrometallurgical technology. The two-zone reactor system with fast and thermal regions is more effective for nuclear waste transmutation than the one-zone reactor. Modeling results show that nearly all radioactive wastes can be transmuted in the two-zone subcritical system driven by a high-intensity neutron generator with the external neutron source strength of 1.10{sup 13} n/sec. Obviously, transmutation rate will increase with a rise of the external neutron source strength. From the results above we can also see that the initial loading of radioactive isotopes into the reactor system should exceed by mass those isotopes that are finally produced. (authors)

Babenko, V.O. [Bogolyubov Institute for Theoretical Physics, Metrolohichna str. 14-b, Kiev, 03680 (Ukraine); Gulik, V.I.; Pavlovych, V.M. [Institute for Nuclear Research, pr. Nauky 47, Kyiv, 03680 (Ukraine)

2012-07-01T23:59:59.000Z

396

Reactor Physics Studies of Reduced-Tantaulum-Content Control and Safety Elements for the High Flux Isotope Reactor  

SciTech Connect

Some of the unirradiated High Flux Isotope Reactor (HFIR) control elements discharged during the late 1990s were observed to have cladding damage--local swelling or blistering. The cladding damage was limited to the tantalum/europium interface of the element and is thought to result from interaction of hydrogen and europium to form a compound of lower density than europium oxide, thus leading to a ''blistering'' of the control plate cladding. Reducing the tantalum loading in the control plates should help preclude this phenomena. The impact of the change to the control plates on the operation of the reactor was assessed. Regarding nominal, steady-state reactor operation, the impact of the change in the power distribution in the core due to reduced tantalum content was calculated and found to be insignificant. The magnitude and impact of the change in differential control element worth was calculated, and the differential worths of reduced tantalum elements vs the current elements from equivalent-burnup critical configurations were determined to be unchanged within the accuracy of the computational method and relevant experimental measurements. The location of the critical control elements symmetric positions for reduced tantalum elements was found to be 1/3 in. less withdrawn relative to existing control elements regardless of the value of fuel cycle burnup (time in the fuel cycle). The magnitude and impact of the change in the shutdown margin (integral rod worth) was assessed and found to be unchanged. Differential safety element worth values for the reduced-tantalum-content elements were calculated for postulated accident conditions and were found to be greater than values currently assumed in HFIR safety analyses.

Primm, R.T., III

2003-11-01T23:59:59.000Z

397

Pulsed-neutron monochromator  

DOE Patents (OSTI)

In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

Mook, H.A. Jr.

1984-01-01T23:59:59.000Z

398

Pulsed-neutron monochromator  

DOE Patents (OSTI)

In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The wave are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

Mook, Jr., Herbert A. (Oak Ridge, TN)

1985-01-01T23:59:59.000Z

399

Hardening neutron spectrum for advanced actinide transmutation experiments in the ATR  

Science Journals Connector (OSTI)

......constant neutron-flux field, the fission power is...over the neutron energy range 0...the neutron spectrum such that all the thermal neutrons...Nuclear Energy-Engineering...fraction of neutron induced gamma-heat...Hardening neutron spectrum for advanced...shorter-lived fission products...performed in a thermal test reactor......

G. S. Chang; R. G. Ambrosek

2005-12-20T23:59:59.000Z

400

RisR1084(EN) Small Angle Neutron Scat-  

E-Print Network (OSTI)

#12;Abstract This thesis describes small angle neutron scattering studies of the flux line latticeRisø­R­1084(EN) Small Angle Neutron Scat- tering Studies of the Flux Line Lattices in the Boro. As the field is increased the magnetic structure is modified, signalled by the appearence of additional neutron

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Neutron Generators for Spent Fuel Assay  

E-Print Network (OSTI)

13, 2010. [11] D-D Neutron Generator Development at LBNL, J.12] High-yield DT Neutron Generator, B.A. Ludewigt et al. ,a Compact High-Yield Neutron Generator, O. Waldmann and B.

Ludewigt, Bernhard A

2011-01-01T23:59:59.000Z

402

Neutron Generators for Spent Fuel Assay  

E-Print Network (OSTI)

of a High Fluence Neutron Source for NondestructiveAugust 8-13, 2010. [11] D-D Neutron Generator Development at2005. [12] High-yield DT Neutron Generator, B.A. Ludewigt et

Ludewigt, Bernhard A

2011-01-01T23:59:59.000Z

403

Neutron reflectometry  

Science Journals Connector (OSTI)

Neutron reflectivity is a powerful tool for the ... chapter include: the theory of elastic specular neutron diffraction; polarized neutron reflectivity; surface roughness; experimental methodology; resolution in ...

G. S. Smith; C. F. Majkrzak

2004-01-01T23:59:59.000Z

404

Gas Flux Sampling | Open Energy Information  

Open Energy Info (EERE)

Gas Flux Sampling Gas Flux Sampling Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Gas Flux Sampling Details Activities (26) Areas (20) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Field Techniques Exploration Sub Group: Field Sampling Parent Exploration Technique: Gas Sampling Information Provided by Technique Lithology: Stratigraphic/Structural: High flux can be indicative of conduits for fluid flow. Hydrological: Thermal: Anomalous flux is associated with active hydrothermal activity. Dictionary.png Gas Flux Sampling: Gas flux sampling measures the flow of volatile gas emissions from a specific location and compares it to average background emissions. Anomalously high gas flux can be an indication of hydrothermal activity.

405

An aerogel Cherenkov detector for multi-GeV photon detection with low sensitivity to neutrons  

E-Print Network (OSTI)

We describe a novel photon detector which operates under an intense flux of neutrons. It is composed of lead-aerogel sandwich counter modules. Its salient features are high photon detection efficiency and blindness to neutrons. As a result of Monte Carlo (MC) simulations, the efficiency for photons with the energy larger than 1 GeV is expected to be higher than 99.5% and that for 2 GeV/$c$ neutrons less than 1%. The performance on the photon detection under such a large flux of neutrons was measured for a part of the detector. It was confirmed that the efficiency to photons with the energy $>$1 GeV was consistent with the MC expectation within 8.2% uncertainty.

Y. Maeda; N. Kawasaki; T. Masuda; H. Morii; D. Naito; Y. Nakajima; H. Nanjo; T. Nomura; N. Sasao; S. Seki; K. Shiomi; T. Sumida; Y. Tajima

2014-12-22T23:59:59.000Z

406

An aerogel Cherenkov detector for multi-GeV photon detection with low sensitivity to neutrons  

E-Print Network (OSTI)

We describe a novel photon detector which operates under an intense flux of neutrons. It is composed of lead-aerogel sandwich counter modules. Its salient features are high photon detection efficiency and blindness to neutrons. As a result of Monte Carlo (MC) simulations, the efficiency for photons with the energy larger than 1 GeV is expected to be higher than 99.5% and that for 2 GeV/$c$ neutrons less than 1%. The performance on the photon detection under such a large flux of neutrons was measured for a part of the detector. It was confirmed that the efficiency to photons with the energy $>$1 GeV was consistent with the MC expectation within 8.2% uncertainty.

Maeda, Y; Masuda, T; Morii, H; Naito, D; Nakajima, Y; Nanjo, H; Nomura, T; Sasao, N; Seki, S; Shiomi, K; Sumida, T; Tajima, Y

2014-01-01T23:59:59.000Z

407

Neutron-Neutron Interaction  

Science Journals Connector (OSTI)

The present status of the problem of charge dependence is discussed. The information about the neutron-neutron interaction derived from the two-neutron system, three-nucleon systems, final-state interactions in multiparticle reactions, and peripheral processes is critically evaluated. The experimental data indicate the breakdown of charge independence by about 3-5%. Evidence concerning the violation of charge symmetry is inconclusive, but it seems that most of the data are consistent with the assumption that charge symmetry is satisfied within 0.5-1%. The most suitable studies which might improve the knowledge of the neutron-neutron forces are indicated.

IVO ŠLAUS

1967-07-01T23:59:59.000Z

408

Neutron Irradiation of Hydrided Cladding Material in HFIR Summary of  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Neutron Irradiation of Hydrided Cladding Material in HFIR Summary Neutron Irradiation of Hydrided Cladding Material in HFIR Summary of Initial Activities Neutron Irradiation of Hydrided Cladding Material in HFIR Summary of Initial Activities Irradiation is known to have a significant impact on the properties and performance of Zircaloy cladding and structural materials (material degradation processes, e.g., effects of hydriding). This UFD study examines the behavior and performance of unirradiated cladding and actual irradiated cladding through testing and simulation. Three capsules containing hydrogen-charged Zircaloy-4 cladding material have been placed in the High Flux Isotope Reactor (HFIR). Irradiation of the capsules was conducted for post-irradiation examination (PIE) metallography. Neutron Irradiation of Hydrided Cladding Material in HFIR Summary of

409

Meson cascade in the atmosphere, uncertainties in calculating the fluxes of high-energy muons, and data of direct measurements  

Science Journals Connector (OSTI)

A new calculation of the atmospheric fluxes of cosmic-ray hadrons and muons in the energy range 10–104...GeV is performed on the basis of the method for solving nuclear-cascade equations with allowance for a nons...

A. A. Kochanov; T. S. Sinegovskaya; S. I. Sinegovsky

2007-11-01T23:59:59.000Z

410

Neutronic analysis of a fusion hybrid reactor  

SciTech Connect

In a PHYSOR 2010 paper(1) we introduced a fusion hybrid reactor whose fusion component is the gasdynamic mirror (GDM), and whose blanket was made of thorium - 232. The thrust of that study was to demonstrate the performance of such a reactor by establishing the breeding of uranium - 233 in the blanket, and the burning thereof to produce power. In that analysis, we utilized the diffusion equation for one-energy neutron group, namely, those produced by the fusion reactions, to establish the power distribution and density in the system. Those results should be viewed as a first approximation since the high energy neutrons are not effective in inducing fission, but contribute primarily to the production of actinides. In the presence of a coolant, however, such as water, these neutrons tend to thermalize rather quickly, hence a better assessment of the reactor performance would require at least a two group analysis, namely the fast and thermal groups. We follow that approach and write an approximate set of equations for the fluxes of these groups. From these relations we deduce the all-important quantity, k{sub eff}, which we utilize to compute the multiplication factor, and subsequently, the power density in the reactor. We show that k{sub eff} can be made to have a value of 0.99, thus indicating that 100 thermal neutrons are generated per fusion neutron, while allowing the system to function as 'subcritical.' Moreover, we show that such a hybrid reactor can generate hundreds of megawatts of thermal power per cm of length depending on the flux of the fusion neutrons impinging on the blanket. (authors)

Kammash, T. [Univ. of Michigan, NERS, 2355 Bonisteel Blvd., Ann Arbor, MI 48109 (United States)

2012-07-01T23:59:59.000Z

411

Limits on the High-Energy Gamma and Neutrino Fluxes from the SGR 1806-20 Giant Flare of 27 December 2004 with the AMANDA-II Detector  

Science Journals Connector (OSTI)

On 27 December 2004, a giant ? flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5)??TeV-1?m-2?s-1 for ?=-1.47 (-2) in the gamma flux and 0.4(6.1)??TeV-1?m-2?s-1 for ?=-1.47 (-2) in the high-energy neutrino flux.

A. Achterberg et al. (IceCube Collaboration)

2006-11-28T23:59:59.000Z

412

High-pressure cell for neutron diffraction with in situ pressure control at cryogenic temperatures  

SciTech Connect

Pressure generation at cryogenic temperatures presents a problem for a wide array of experimental techniques, particularly neutron studies due to the volume of sample required. We present a novel, compact pressure cell with a large sample volume in which load is generated by a bellow. Using a supply of helium gas up to a pressure of 350 bar, a load of up to 78 kN is generated with leak-free operation. In addition, special fiber ports added to the cryogenic center stick allow for in situ pressure determination using the ruby pressure standard. Mechanical stability was assessed using finite element analysis and the dimensions of the cell have been optimized for use with standard cryogenic equipment. Load testing and on-line experiments using NaCl and BiNiO{sub 3} have been done at the WISH instrument of the ISIS pulsed neutron source to verify performance.

Jacobsen, Matthew K.; Ridley, Christopher J.; Bocian, Artur; Kamenev, Konstantin V., E-mail: k.kamenev@ed.ac.uk [School of Engineering and CSEC, University of Edinburgh, Edinburgh (United Kingdom); Kirichek, Oleg; Manuel, Pascal; Khalyavin, Dmitry [ISIS, Rutherford Appleton Laboratory, Harwell Oxford (United Kingdom)] [ISIS, Rutherford Appleton Laboratory, Harwell Oxford (United Kingdom); Azuma, Masaki [Materials and Structures Laboratory, Tokyo Institute of Technology, Tokyo (Japan)] [Materials and Structures Laboratory, Tokyo Institute of Technology, Tokyo (Japan); Attfield, J. Paul [School of Chemistry and CSEC, University of Edinburgh, Edinburgh (United Kingdom)] [School of Chemistry and CSEC, University of Edinburgh, Edinburgh (United Kingdom)

2014-04-15T23:59:59.000Z

413

NSE: the Neutron Spin Echo Spectrometer at SNS | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Spin Echo Spectrometer at SNS Spin Echo Spectrometer at SNS NSE NSE is funded and operated by the Jülich Centre for Neutron Science. The SNS NSE instrument provides ultrahigh resolution spectroscopy with a Fourier time range that covers τ = 1 ps to a nominal 350 ns with a high effective neutron flux, aiming to be the best of its class in both resolution and dynamic range (please refer to the instrument fact sheet for a detailed current status). Researchers use this instrument to investigate soft condensed matter and complex fluids applications in a variety of fields. The planned optional ferromagnetic and intensity-modulated modes will allow for detailed investigation of magnetic samples and phenomena. The design of the NSE spectrometer takes full advantage of recent progress in neutron optics and polarizing supermirror microbenders,1,2 resulting in

414

Thermal neutron imaging in an active interrogation environment  

SciTech Connect

We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of xcitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

Vanier,P.E.; Forman, L., and Norman, D.R.

2009-03-10T23:59:59.000Z

415

High latitudes present extreme conditions for the measurement and estimation of airsea and ice fluxes, limiting understanding of related physical processes and  

E-Print Network (OSTI)

High latitudes present extreme conditions for the measurement and estimation of air­sea and ice of the Earth's climate. HigH-LatitudE OcEan and SEa icE SurfacE fLuxES: cHaLLEngES fOr cLimatE rESEarcH by Mark change can manifest itself in astonishing ways. Arctic sea ice extent at the end of the melt season

Renfrew, Ian

416

Instrument and Source Design Division | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Ron Crone, RRD Director Ron Crone, RRD Director ISDD Director Ron Crone. Instrument and Source Design Division The Instrument and Source Design Division (ISDD) supports the engineering and development of scientific instruments at the High Flux Isotope Reactor and the Spallation Neutron Source. ISDD continuously develops facilities and capabilities associated with neutron science through research and development. Organization Chart A PDF version of the ISDD Organization Chart is available. Key Division Contacts Director Ron Crone Administrative Assistant Wendy Brooks HFIR Instrument Engineering Doug Selby SNS Instrument Engineering David Vandergriff Instrumentation Projects and Development Ken Herwig Project Management/Operations and Analysis Barbara Thibadeau Source Development and Engineering Analysis Phil Ferguson

417

Nanosecond molecular relaxations in lipid bilayers studied by high energy resolution neutron scattering and in-situ diffraction  

E-Print Network (OSTI)

We report a high energy-resolution neutron backscattering study to investigate slow motions on nanosecond time scales in highly oriented solid supported phospholipid bilayers of the model system DMPC -d54 (deuterated 1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine), hydrated with heavy water. Wave vector resolved quasi-elastic neutron scattering (QENS) is used to determine relaxation times $\\tau$, which can be associated with different molecular components, i.e., the lipid acyl chains and the interstitial water molecules in the different phases of the model membrane system. The inelastic data are complemented both by energy resolved and energy integrated in-situ diffraction. From a combined analysis of the inelastic data in the energy and time domain, the respective character of the relaxation, i.e., the exponent of the exponential decay is also determined. From this analysis we quantify two relaxation processes. We associate the fast relaxation with translational diffusion of lipid and water molecules while the slow process likely stems from collective dynamics.

Maikel C. Rheinstädter; Tilo Seydel; Tim Salditt

2006-07-20T23:59:59.000Z

418

Coupling highly excited nuclei to the atomic shell in dense astrophysical plasmas  

E-Print Network (OSTI)

In dense astrophysical plasmas, neutron capture populates highly excited nuclear states close to the neutron threshold. The impact of additional low-energy nuclear excitations via coupling to the atomic shell on the ability of the so-formed compound nucleus to retain the captured neutron is investigated. We focus on the mechanism of nuclear excitation by electron capture in plasmas characterized by electron fluxes typical for the slow neutron capture process of stellar nucleosynthesis. The small effect of this further excitation on the neutron capture and gamma decay sequence relevant for nucleosynthesis is quantified and compared to the corresponding effect of an additional low-energy photoexcitation step.

Stephan Helmrich; Katja Spenneberg; Adriana Pálffy

2014-04-25T23:59:59.000Z

419

Coupling highly excited nuclei to the atomic shell in dense astrophysical plasmas  

E-Print Network (OSTI)

In dense astrophysical plasmas, neutron capture populates highly excited nuclear states close to the neutron threshold. The impact of additional low-energy nuclear excitations via coupling to the atomic shell on the ability of the so-formed compound nucleus to retain the captured neutron is investigated. We focus on the mechanism of nuclear excitation by electron capture in plasmas characterized by electron fluxes typical for the slow neutron capture process of stellar nucleosynthesis. The small effect of this further excitation on the neutron capture and gamma decay sequence relevant for nucleosynthesis is quantified and compared to the corresponding effect of an additional low-energy photoexcitation step.

Helmrich, Stephan; Pálffy, Adriana

2014-01-01T23:59:59.000Z

420

Development of Real-Time Measurement of Effective Dose for High Dose Rate Neutron Fields  

SciTech Connect

Studies of the effects of low doses of ionizing radiation require sources of radiation which are well characterized in terms of the dose and the quality of the radiation. One of the best measures of the quality of neutron irradiation is the dose mean lineal energy. At very low dose rates this can be determined by measuring individual energy deposition events, and calculating the dose mean of the event size. However, at the dose rates that are normally required for biology experiments, the individual events can not be separated by radiation detectors. However, the total energy deposited in a specified time interval can be measured. This total energy has a random variation which depends on the size of the individual events, so the dose mean lineal energy can be calculated from the variance of repeated measurements of the energy deposited in a fixed time. We have developed a specialized charge integration circuit for the measurement of the charge produced in a small ion chamber in typical neutron irradiation experiments. We have also developed 4.3 mm diameter ion chambers with both tissue equivalent and carbon walls for the purpose of measuring dose mean lineal energy due to all radiations and due to all radiations except neutrons, respectively. By adjusting the gas pressure in the ion chamber, it can be made to simulate tissue volumes from a few nanometers to a few millimeters in diameter. The charge is integrated for 0.1 seconds, and the resulting pulse height is recorded by a multi channel analyzer. The system has been used in a variety of photon and neutron radiation fields, and measured values of dose and dose mean lineal energy are consistent with values extrapolated from measurements made by other techniques at much lower dose rates. It is expected that this technique will prove to be much more reliable than extrapolations from measurements made at low dose rates because these low dose rate exposures generally do not accurately reproduce the attenuation and scattering environment of the actual radiation exposure.

L. A. Braby; W. D. Reece; W. H. Hsu

2003-08-29T23:59:59.000Z

Note: This page contains sample records for the topic "high neutron flux" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Boosted Fast Flux Loop Final Report  

SciTech Connect

The Boosted Fast Flux Loop (BFFL) project was initiated to determine basic feasibility of designing, constructing, and installing in a host irradiation facility, an experimental vehicle that can replicate with reasonable fidelity the fast-flux test environment needed for fuels and materials irradiation testing for advanced reactor concepts. Originally called the Gas Test Loop (GTL) project, the activity included (1) determination of requirements that must be met for the GTL to be responsive to potential users, (2) a survey of nuclear facilities that may successfully host the GTL, (3) conceptualizing designs for hardware that can support the needed environments for neutron flux intensity and energy spectrum, atmosphere, flow, etc. needed by the experimenters, and (4) examining other aspects of such a system, such as waste generation and disposal, environmental concerns, needs for additional infrastructure, and requirements for interfacing with the host facility. A revised project plan included requesting an interim decision, termed CD-1A, that had objectives of' establishing the site for the project at the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL), deferring the CD 1 application, and authorizing a research program that would resolve the most pressing technical questions regarding GTL feasibility, including issues relating to the use of booster fuel in the ATR. Major research tasks were (1) hydraulic testing to establish flow conditions through the booster fuel, (2) mini-plate irradiation tests and post-irradiation examination to alleviate concerns over corrosion at the high heat fluxes planned, (3) development and demonstration of booster fuel fabrication techniques, and (4) a review of the impact of the GTL on the ATR safety basis. A revised cooling concept for the apparatus was conceptualized, which resulted in renaming the project to the BFFL. Before the subsequent CD-1 approval request could be made, a decision was made in April 2006 that further funding for the project would be suspended. Remaining funds have been used to prepare and irradiate mini-plates of the proposed booster fuel. The current baseline design is for a set of three test positions inside an in-pile tube with a thermal neutron absorber and heat sink made of aluminum mixed with hafnium. Operating the ATR at power levels needed to achieve the required fast flux will result in an estimated increase in ATR fuel consumption between 15 and 20% above present rates and a reduction in the time between fuel replacements. Preliminary safety analyses conducted have indicted safe operation of the ATR with the GTL under normal, abnormal, and postulated accident conditions. More comprehensive analyses are needed.

Boosted Fast Flux Loop Project Staff

2009-09-01T23:59:59.000Z

422

Heat Flux Calculation and Problem of Flaking of Boron Carbide Coatings on the Faraday Screen of the ICRH Antennas During Tore Supra High Power, Long Pulse Operation  

SciTech Connect

Reliable and repetitive high power and long pulse tokamak operation is strongly dependant of the ability to secure the Plasma Facing Components (PFCs). In Tore Supra, a network of 7 infrared (IR) video cameras is routinely used to prevent PFCs overheating and damage in selected regions. Real time feedback control and offline analysis are essential for basic protection and understanding of abnormal thermal events. One important limitation detected by the IR real time feed-back loop during high power RF operation (injected power of 9.5 MW over 26 s and 12 MW over 10 s have been achieved respectively in 2006 and 2008) is due to the interaction between fast ions which increase the power flux density and flaking of the boron carbide coatings on the Faraday screen box of the ICRH antennas. An IR-based experimental procedure is proposed in order to detect new flakes during plasma operation. The thermal response of the B4C coating is studied with and without flaking during plasma operation. The experimental heat flux deposited by fast ion losses on the Faraday screen is calculated for high (3.8 T) and low magnetic field (2 T) during high RF power operation (with fundamental hydrogen minority and second harmonic ICRH heating schemes respectively). The paper addresses both thermal science issues applied to machine protection and limitation due to fast ions issues during high RF power, long pulse operation. Safety margin to critical heat flux and number of fatigue cycles under heat load are presented in the paper.

Corre, Y. [French Atomic Energy Commission (CEA), Cadarache, St. Paul lez Durance] [French Atomic Energy Commission (CEA), Cadarache, St. Paul lez Durance; Lipa, M. [CEA IRFM, St. Paul-lez-Durance, France] [CEA IRFM, St. Paul-lez-Durance, France; Agarici, G. [Fusion for Energy (F4E), Barcelona, Spain] [Fusion for Energy (F4E), Barcelona, Spain; Basiuk, V. [CEA IRFM, St. Paul-lez-Durance, France] [CEA IRFM, St. Paul-lez-Durance, France; Colas, L. [French Atomic Energy Commission (CEA)] [French Atomic Energy Commission (CEA); Courtois, X. [CEA, St. Paul Les Durance, France] [CEA, St. Paul Les Durance, France; Dumont, R. J. [French Atomic Energy Commission (CEA), Cadarache, St. Paul lez Durance] [French Atomic Energy Commission (CEA), Cadarache, St. Paul lez Durance; Ekedahl, A. [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM)] [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM); Gardarein, J. L. [University of Aix, Marseille, France] [University of Aix, Marseille, France; Klepper, C Christopher [ORNL] [ORNL; Martin, V. [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM)] [French Atomic Energy Commission (CEA), Institute for Magnetic Fusion Research (IRFM); Moncada, V. [CEA, St. Paul Les Durance, France] [CEA, St. Paul Les Durance, France; Portafaix, C. [CEA, St. Paul Les Durance, France] [CEA, St. Paul Les Durance, France; Rigollet, F. [University of Aix, Marseille, France] [University of Aix, Marseille, France; Tawizgant, R. [CEA, St. Paul Les Durance, France] [CEA, St. Paul Les Durance, France; Travere, J. M. [CEA, St. Paul Les Durance, France] [CEA, St. Paul Les Durance, France; Valliez, K. [CEA, St. Paul Les Durance, France] [CEA, St. Paul Les Durance, France

2011-01-01T23:59:59.000Z

423

Prompt Neutron Decay for Delayed Critical Bare and Natural-Uranium-Reflected Metal Spheres of Plutonium and Highly Enriched Uranium  

SciTech Connect

Prompt neutron decay at delayed criticality was measured by Oak Ridge National Laboratory for uranium-reflected highly enriched uranium (HEU) and Pu metal spheres (FLATTOP), for an unreflected Pu metal (4.5% {sup 240}Pu) sphere (JEZEBEL) at Los Alamos National Laboratory (LANL) and for an unreflected HEU metal sphere at Oak Ridge Critical Experiments Facility. The average prompt neutron decay constants from hundreds of Rossi-{alpha} and randomly pulsed neutron measurements with {sup 252}Cf at delayed criticality are as follows: 3.8458 {+-} 0.0016 x 10{sup 5} s{sup -1}, 2.2139 {+-} 0.0022 x 10{sup 5} s{sup -1}, 6.3126 {+-} 0.0100 x 10{sup 5} s{sup -1}, and 1.1061 {+-} 0.0009 x 10{sup 6} s{sup -1}, respectively. These values agree with previous measurements by LANL for FLATTOP, JEZEBEL, and GODIVA I as follows: 3.82 {+-} 0.02 x 10{sup 5} s{sup -1} for a uranium core; 2.14 {+-} 0.05 x 10{sup 5} s{sup -1} and 2.29 x 10{sup 5} s{sup -1} (uncertainty not reported) for a plutonium core; 6.4 {+-} 0.1 x 10{sup 5} s{sup -1}, and 1.1 {+-} 0.1 x 10{sup 6} s{sup -1}, respectively, but have smaller uncertainties because of the larger number of measurements. For the FLATTOP and JEZEBEL assemblies, the measurements agree with calculations. Traditionally, the calculated decay constants for the bare uranium metal sphere GODIVA I and the Oak Ridge Uranium Metal Sphere were higher than experimental by {approx}10%. Other energy-dependent quantities for the bare uranium sphere agree within 1%.

Mihalczo, John T [ORNL

2011-01-01T23:59:59.000Z

424

Characterization of a Thermo Scientific D711 D-T Neutron Generator Located in a Low-Scatter Facility  

SciTech Connect

A dosimetry experiment used to measure the neutron flux and spectrum of a D-T neutron generator is presented. The D-T generator at Pacific Northwest National Laboratory is installed in the middle of a large room to minimize scatter of neutrons back to the sample. The efficacy of maintaining a pure fast neutron field for the sample is investigated. Twenty-one positions within 13 cm of the neutron source contained foils or wires of Fe, Ni, Al with additional Au, and In monitors at some locations. Spectral adjustment of the neutron flux at each position based on measured reaction rates and theoretical Monte Carlo calculations show that at least 99.1% of the spectrum lies above 110 keV for all measured positions, and neutrons above 14 MeV can account for as much as 91% at locations along the axis of the generator and close to the source. The 14 MeV component drops to 77% in radial positions far from the source. The largest total flux observed was 8.29E+08 n/cm2-s (±1.4%) in the center of the cooling cap, although additional experiments have shown this value could be as high as 1.20E+09 n/cm2-s.

Hayes, John W.; Finn, Erin C.; Greenwood, Lawrence R.; Wittman, Richard S.

2014-03-21T23:59:59.000Z

425

Neutron-induced dpa, transmutations, gas production, and helium embrittlement of fusion materials  

E-Print Network (OSTI)

In a fusion reactor materials will be subjected to significant fluxes of high-energy neutrons. As well as causing radiation damage, the neutrons also initiate nuclear reactions leading to changes in the chemical composition of materials (transmutation). Many of these reactions produce gases, particularly helium, which cause additional swelling and embrittlement of materials. This paper investigates, using a combination of neutron-transport and inventory calculations, the variation in displacements per atom (dpa) and helium production levels as a function of position within the high flux regions of a recent conceptual model for the "next-step" fusion device DEMO. Subsequently, the gas production rates are used to provide revised estimates, based on new density-functional-theory results, for the critical component lifetimes associated with the helium-induced grain-boundary embrittlement of materials. The revised estimates give more optimistic projections for the lifetimes of materials in a fusion power plant co...

Gilbert, M R; Nguyen-Manh, D; Zheng, S; Packer, L W; Sublet, J -Ch

2013-01-01T23:59:59.000Z

426

Type A verification report for the high flux beam reactor stack and grounds, Brookhaven National Laboratory, Upton, New York  

SciTech Connect

The U.S. Department of Energy (DOE) Order 458.1 requires independent verification (IV) of DOE cleanup projects (DOE 2011). The Oak Ridge Institute for Science and Education (ORISE) has been designated as the responsible organization for IV of the High Flux Beam Reactor (HFBR) Stack and Grounds area at Brookhaven National Laboratory (BNL) in Upton, New York. The IV evaluation may consist of an in-process inspection with document and data reviews (Type A Verification) or a confirmatory survey of the site (Type B Verification). DOE and ORISE determined that a Type A verification of the documents and data for the HFBR Stack and Grounds: Survey Units (SU) 6, 7, and 8 was appropriate based on the initial survey unit classification, the walkover surveys, and the final analytical results provided by the Brookhaven Science Associates (BSA). The HFBR Stack and Grounds surveys began in June 2011 and were completed in September 2011. Survey activities by BSA included gamma walkover scans and sampling of the as-left soils in accordance with the BSA Work Procedure (BNL 2010a). The Field Sampling Plan - Stack and Remaining HFBR Outside Areas (FSP) stated that gamma walk-over surveys would be conducted with a bare sodium iodide (NaI) detector, and a collimated detector would be used to check areas with elevated count rates to locate the source of the high readings (BNL 2010b). BSA used the Mult- Agency Radiation Survey and Site Investigation Manual (MARSSIM) principles for determining the classifications of each survey unit. Therefore, SUs 6 and 7 were identified as Class 1 and SU 8 was deemed Class 2 (BNL 2010b). Gamma walkover surveys of SUs 6, 7, and 8 were completed using a 2?2 NaI detector coupled to a data-logger with a global positioning system (GPS). The 100% scan surveys conducted prior to the final status survey (FSS) sampling identified two general soil areas and two isolated soil locations with elevated radioactivity. The general areas of elevated activity identified were investigated further with a collimated NaI detector. The uncollimated average gamma count rate was less than 15,000 counts per minute (cpm) for the SU 6, 7, and 8 composite area (BNL 2011a). Elevated count rates were observed in portions of each survey unit. The general areas of elevated counts near the Building 801 ventilation and operations and the entry to the Stack were determined to be directly related to the radioactive processes in those structures. To compensate for this radioactive shine, a collimated or shielded detector was used to lower the background count rate (BNL 2011b and c). This allowed the surveyor(s) to distinguish between background and actual radioactive contamination. Collimated gamma survey count rates in these shine affected areas were below 9,000 cpm (BNL 2011a). The average background count rate of 7,500 cpm was reported by BSA for uncollimated NaI detectors (BNL 2011d). The average collimated background ranged from 4,500-6,500 cpm in the westernmost part of SU 8 and from 2,000-3,500 cpm in all other areas (BNL 2011e). Based on these data, no further investigations were necessary for these general areas. SU 8 was the only survey unit that exhibited verified elevated radioactivity levels. The first of two isolated locations of elevated radioactivity had an uncollimated direct measurement of 50,000 cpm with an area background of 7,500 cpm (BNL 2011f). The second small area exhibiting elevated radiation levels was identified at a depth of 6 inches from the surface. The maximum reported count rate of 28,000 cpm was observed during scanning (BNL 2011g). The affected areas were remediated, and the contaminated soils were placed in an intermodal container for disposal. BSA's post-remediation walkover surveys were expanded to include a 10-foot radius around the excavated locations, and it was determined that further investigation was not required for these areas (BNL 2011 f and g). The post-remediation soil samples were collected and analyzed with onsite gamma spectroscopy equipment. These samples were also included with the FSS s

Harpenau, Evan M.

2012-01-13T23:59:59.000Z

427

Detection system for high-resolution gamma radiation spectroscopy with neutron time-of-flight filtering  

DOE Patents (OSTI)

A .gamma.-radiation detection system that includes at least one semiconductor detector such as HPGe-Detector, a position-sensitive .alpha.-Detector, a TOF Controller, and a Digitizer/Integrator. The Digitizer/Integrator starts to process the energy signals of a .gamma.-radiation sent from the HPGe-Detector instantly when the HPGe-Detector detects the .gamma.-radiation. Subsequently, it is determined whether a coincidence exists between the .alpha.-particles and .gamma.-radiation signal, based on a determination of the time-of-flight of neutrons obtained from the .alpha.-Detector and the HPGe-Detector. If it is determined that the time-of-flight falls within a predetermined coincidence window, the Digitizer/Integrator is allowed to continue and complete the energy signal processing. If, however, there is no coincidence, the Digitizer/Integrator is instructed to be clear and reset its operation instantly.

Dioszegi, Istvan; Salwen, Cynthia; Vanier, Peter

2014-12-30T23:59:59.000Z

428

Overview of the US-Japan collaborative investigation on hydrogen isotope retention in neutron-irradiated and ion-damaged tungsten  

SciTech Connect

Plasma-facing components (PFCs) will be exposed to 14 MeV neutrons from deuterium-tritium (D-T) fusion reactions, and tungsten, a candidate PFC for the divertor in ITER, is expected to receive a neutron dose of 0.7 displacement per atom (dpa) by the end of operation in ITER. The effect of neutron-irradiation damage has been mainly simulated using high-energy ion bombardment. While this prior database of results is quite valuable for understanding the behavior of hydrogen isotopes in PFCs, it does not encompass the full range of effects that must be considered in a practical fusion environment due to short penetration depth, damage gradient, high damage rate, and high PKA energy spectrum of the ion bombardment. In addition, neutrons change the elemental composition via transmutations, and create a high radiation environment inside PFCs, which influence the behavior of hydrogen isotope in PFCs, suggesting the utilization of fission reactors is necessary for neutron irradiation. Therefore, the effort to correlate among high-energy ions, fission neutrons, and fusion neutrons is crucial for accurately estimating tritium retention under a neutron-irradiation environment. Under the framework of the US-Japan TITAN program, tungsten samples (99.99 at. % purity from A.L.M.T. Co.) were irradiated by neutron in the High Flux Isotope Reactor (HFIR), ORNL, at 50 and 300C to 0.025, 0.3, and 1.2 dpa, and the investigation of deuterium retention in neutron-irradiation was performed in the INL Tritium Plasma Experiment (TPE), the unique high-flux linear plasma facility that can handle tritium, beryllium and activated materials. This paper reports the recent results from the comparison of ion-damaged tungsten via various ion species (2.8 MeV Fe2+, 20 MeV W2+, and 700 keV H-) with that from neutron-irradiated tungsten to identify the similarities and differences among them.

Masashi Shimada; Y. Hatano; Y. Oya; T. Oda; M. Hara; G. Cao; M. Kobayashi; M. Sokolov; H. Watanabe; B. Tyburska; Y. Ueda; P. Calderoni

2011-09-01T23:59:59.000Z

429

Measurement of the fluence response of the GSI neutron ball in high-energy neutron fields produced by 500 AMeV and 800 AMeV deuterons  

Science Journals Connector (OSTI)

......investigations by means of Monte Carlo methods(1,2)-was carried out for thermal energies at the GeNF facility at GKSS (Geesthacht, Germany) and in the quasi-monoenergetic neutron fields at the PTB accelerator facility (Braunschweig, Germany) for......

G. Fehrenbacher; F. Gutermuth; E. Kozlova; T. Radon; T. Aumann; S. Beceiro; T. Le Bleis; K. Boretzky; H. Emling; H. Johansson; O. Kiselev; H. Simon; S. Typel

2007-08-01T23:59:59.000Z

430

Neutron Polarimetry  

Science Journals Connector (OSTI)

8 July 1993 research-article Neutron Polarimetry P. Jane Brown J. Bruce Forsyth Francis Tasset Zero-field neutron polarimetry is a technique which has...polarization analysis to be carried out in a neutron scattering experiment. The incident...

1993-01-01T23:59:59.000Z

431

Apparent Neutron Emissions from Polyethylene Capsules during Neutron Activation and Delayed Neutron Counting  

Science Journals Connector (OSTI)

At Imperial College uranium is determined at very low levels in environmental samples by delayed neutron counting. High density polyethylene capsules are used ... transfer system, from the reactor, to the neutron

R. Benzing; N. M. Baghini; B. A. Bennett…

2000-05-01T23:59:59.000Z

432

HFIR Instrument Systems | ORNL Neutron Sciences  

NLE Websites -- All DOE Office Websites (Extended Search)

Click for more information about the HFIR beamline Experiment Hall Click for more information about the HFIR beamline Experiment Hall HFIR instrument layout. Click for details. Instruments at the High Flux Isotope Reactor The instrument suite at HFIR is supported by a variety of sample environments and on-site laboratories for user convenience. If you're unsure which instrument(s) would most benefit your research, or if you would like to request capabilities that you don't see here, please contact our user office. All HFIR Instrument fact sheets are also available in this single PDF document. Available to Users Beam Line Fact Sheet Instrument Name Contact CG-1 Development Beam Line Lee Robertson CG-1D PDF IMAGING - Neutron Imaging Prototype Facility Hassina Bilheux CG-2 PDF GP-SANS - General-Purpose Small-Angle Neutron Scattering Diffractometer Ken Littrell

433

Thermal radiation from magnetic neutron star surfaces  

E-Print Network (OSTI)

We investigate the thermal emission from magnetic neutron star surfaces in which the cohesive effects of the magnetic field have produced the condensation of the atmosphere and the external layers. This may happen for sufficiently cool atmospheres with moderately intense magnetic fields. The thermal emission from an isothermal bare surface of a neutron star shows no remarkable spectral features, but it is significantly depressed at energies below some threshold energy. However, since the thermal conductivity is very different in the normal and parallel directions to the magnetic field lines, the presence of the magnetic field is expected to produce a highly anisotropic temperature distribution, depending on the magnetic field geometry. In this case, the observed flux of such an object looks very similar to a BB spectrum, but depressed in a nearly constant factor at all energies. This results in a systematic underestimation of the area of the emitter (and therefore its size) by a factor 5-10 (2-3).

J. F. Perez--Azorin; J. A. Miralles; J. A. Pons

2004-10-27T23:59:59.000Z

434

Solar Magnetic Flux Ropes  

E-Print Network (OSTI)

The most probable initial magnetic configuration of a CME is a flux rope consisting of twisted field lines which fill the whole volume of a dark coronal cavity. The flux ropes can be in stable equilibrium in the coronal magnetic field for weeks and even months, but suddenly they loose their stability and erupt with high speed. Their transition to the unstable phase depends on the parameters of the flux rope (i.e., total electric current, twist, mass loading etc.), as well as on the properties of the ambient coronal magnetic field. One of the major governing factors is the vertical gradient of the coronal magnetic field which is estimated as decay index (n). Cold dense prominence material can be collected in the lower parts of the helical flux tubes. Filaments are therefore good tracers of the flux ropes in the corona, which become visible long before the beginning of the eruption. The perspectives of the filament eruptions and following CMEs can be estimated by the comparison of observed filament heights with...

Filippov, Boris; Srivastava, Abhishek K; Uddin, Wahab

2015-01-01T23:59:59.000Z

435

Study of Neutron-Induced Fission Cross Sections of U, Am, and Cm at n{sub T}OF  

SciTech Connect

Neutron induced fission cross sections of several isotopes have been measured at the CERN n{sub T}OF spallation neutron facility. Between them some measurements involve isotopes ({sup 233}U, {sup 241}Am, {sup 243}Am, {sup 245}Cm) relevant for applications to nuclear technologies. The n{sub T}OF facility delivers neutrons with high instantaneous flux and in a wide energy range, from thermal up to 250 MeV. The experimental apparatus consists of an ionization chamber that discriminates fission fragments and {alpha} particles coming from natural radioactivity of the samples. All the measurements were performed referring to the standard cross section of {sup 235}U.

Milazzo, P. M.; Abbondanno, U.; Belloni, F.; Fujii, K. [INFN, Trieste (Italy); Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Dridi, W.; Ferrant, L.; Gunsing, F.; Pancin, J.; Perrot, L.; Plukis, A.; Stephan, C.; Tassan-Got, L. [CNRS/IN2P3-IPN, Orsay (France); Alvarez, H.; Duran, I.; Paradela, C. [Universidade de Santiago de Compostela (Spain); Alvarez-Velarde, F.; Cano-Ott, D. [CIEMAT, Madrid (Spain)

2010-08-04T23:59:59.000Z

436

EQ-SANS: the Extended Q-Range Small-Angle Neutron Scattering Diffractometer  

NLE Websites -- All DOE Office Websites (Extended Search)

The Extended Q-Range Small-Angle Neutron Scattering Diffractometer at SNS The Extended Q-Range Small-Angle Neutron Scattering Diffractometer at SNS Extended Q-Range Small Angle Diffractometer EQ-SANS detector array The EQ-SANS Diffractometer is designed to study non-crystalline, nano-sized materials in solid, liquid, or gas forms such as polymers, micelles, proteins, and other large biological molecular complexes in solution. It offers high neutron flux, high wavelength resolution (precision), and wide Q-coverage. EQSANS is located on beam line 6, viewing the top-downstream, coupled supercritical hydrogen moderator. It has a curved multichannel beam bender to avoid the direct line of sight of the moderator, which cleans out the background from the prompt neutron pulse quite effectively. The cutoff wavelength of the optics is ~1.5 Ã…. Above this minimum wavelength, the

437

Multi-Channel Auto-Dilution System for Remote Continuous Monitoring of High Soil-CO2 Fluxes  

SciTech Connect

Geological sequestration has the potential capacity and longevity to significantly decrease the amount of anthropogenic CO2 introduced into the atmosphere by combustion of fossil fuels such as coal. Effective sequestration, however, requires the ability to verify the integrity of the reservoir and ensure that potential leakage rates are kept to a minimum. Moreover, understanding the pathways by which CO2 migrates to the surface is critical to assessing the risks and developing remediation approaches. Field experiments, such as those conducted at the Zero Emissions Research and Technology (ZERT) project test site in Bozeman, Montana, require a flexible CO2 monitoring system that can accurately and continuously measure soil-surface CO2 fluxes for multiple sampling points at concentrations ranging from background levels to several tens of percent. To meet this need, PNNL is developing a multi-port battery-operated system capable of both spatial and temporal monitoring of CO2 at concentrations from ambient to at least 150,000 ppmv. This report describes the system components (sampling chambers, measurement and control system, and power supply) and the results of a field test at the ZERT site during the late summer and fall of 2008. While the system performed well overall during the field test, several improvements to the system are suggested for implementation in FY2009.

Amonette, James E.; Barr, Jonathan L.

2009-04-23T23:59:59.000Z

438

Neutron capture therapy with deep tissue penetration using capillary neutron focusing  

DOE Patents (OSTI)

An improved method for delivering thermal neutrons to a subsurface cancer or tumor which has been first doped with a dopant having a high cross section for neutron capture. The improvement is the use of a guide tube in cooperation with a capillary neutron focusing apparatus, or neutron focusing lens, for directing neutrons to the tumor, and thereby avoiding damage to surrounding tissue.

Peurrung, Anthony J. (Richland, WA)

1997-01-01T23:59:59.000Z

439

The World Neutron Monitor Network as a tool for the study of solar neutrons  

E-Print Network (OSTI)

The World Neutron Monitor Network as a tool for the study of solar neutrons I. G. Usoskin1 , G. A Neutron Monitor Network to detect high-energy solar neutrons is dis- cussed in detail. It is shown that the existing network can be used for the routine detection of intense sporadic solar-neutron events whenever

Paris-Sud XI, Université de

440

FAST FLUX TEST FACILITY (FFTF) A HISTORY OF SAFETY & OPERATIONAL EXCELLENCE  

SciTech Connect

The Fast Flux Test Facility (FFTF) is a 400-megawatt (thermal) sodium-cooled, high temperature, fast neutron flux, loop-type test reactor. The facility was constructed to support development and testing of fuels, materials and equipment for the Liquid Metal Fast Breeder Reactor program. FFTF began operation in 1980 and over the next 10 years demonstrated its versatility to perform experiments and missions far beyond the original intent of its designers. The reactor had several distinctive features including its size, flux, core design, extensive instrumentation, and test features that enabled it to simultaneously carry out a significant array of missions while demonstrating its features that contributed to a high level of plant safety and availability. FFTF is currently being deactivated for final closure.

NIELSEN, D L

2004-02-26T23:59:59.000Z

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441

Assumptions and Criteria for Performing a Feasability Study of the Conversion of the High Flux Isotope Reactor Core to Use Low-Enriched Uranium Fuel  

SciTech Connect

A computational study will be initiated during fiscal year 2006 to examine the feasibility of converting the High Flux Isotope Reactor from highly enriched uranium fuel to low-enriched uranium. The study will be limited to steady-state, nominal operation, reactor physics and thermal-hydraulic analyses of a uranium-molybdenum alloy that would be substituted for the current fuel powder--U{sub 3}O{sub 8} mixed with aluminum. The purposes of this document are to (1) define the scope of studies to be conducted, (2) define the methodologies to be used to conduct the studies, (3) define the assumptions that serve as input to the methodologies, (4) provide an efficient means for communication with the Department of Energy and American research reactor operators, and (5) expedite review and commentary by those parties.

Primm, R.T., III; Ellis, R.J.; Gehin, J.C.; Moses, D.L.; Binder, J.L.; Xoubi, N. (U. of Cincinnati)

2006-02-01T23:59:59.000Z

442

Neutron scattering above 25 MeV with monoenergetic neutrons  

Science Journals Connector (OSTI)

Technical problems encountered in measuring elastic and inelastic neutron scattering at kinetic energies well above 25 MeV are considered by extrapolating from experience with lower energy neutrons. It is concluded that all of the techniques required for a high?quality systematic study of neutron scattering—with the notable exception of a suitable accelerator facility—are at hand.

Roger W. Finlay

1985-01-01T23:59:59.000Z

443

Neutron Production, Neutron Facilities and Neutron Instrumentation  

Science Journals Connector (OSTI)

...Mexico, 87545, U.S.A, e-mail: sven@lanl.gov Hans-Georg Priesmeyer Geesthacht Neutron Scattering Facility, GKSS Research Center, 21502 Geesthacht, Germany, e-mail: hans-georg.priesmeyer@gkss.de NEUTRON GENERATION The...

Sven C. Vogel; Hans-Georg Priesmeyer

444

Neutron Capture Therapy  

Science Journals Connector (OSTI)

... . Only those elements which have a high thermal-neutron capture cross-section, such as boron-10, lithium-6, and uranium-235, are useful. This suggestion was first put forward ... was first put forward in 1936 by Locher. The utilization of thermal neutron capture by boron-10 for the treatment of human-brain tumours, chiefly glioblastoma multiforme, has been under investigation ...

1961-09-23T23:59:59.000Z

445

Neutron degeneracy and plasma physics effects on radiative neutron captures in neutron star crust  

Science Journals Connector (OSTI)

We consider the astrophysical reaction rates for radiative neutron capture reactions (n,?) in the crust of a neutron star. The presence of degenerate neutrons at high densities (mainly in the inner crust) can drastically affect the reaction rates. Standard rates assuming a Maxwell-Boltzmann distribution for neutrons can underestimate the rates by several orders of magnitude. We derive simple analytical expressions for reaction rates at a variety of conditions with account for neutron degeneracy. We also discuss the plasma effects on the outgoing radiative transition channel in neutron radiative capture reactions and show that these effects can also increase the reaction rates by a few orders of magnitude. In addition, using detailed balance, we analyze the effects of neutron degeneracy and plasma physics on reverse (?,n) photodisintegration. We discuss the dependence of the reaction rates on temperature and neutron chemical potential and outline the efficiency of these reactions in the neutron star crust.

P. S. Shternin; M. Beard; M. Wiescher; D. G. Yakovlev

2012-07-24T23:59:59.000Z

446

Neutron Reflectivity  

Science Journals Connector (OSTI)

Neutron Reflectivity ... This article is part of the Neutron Reflectivity special issue. ... The articles in this special issue on neutron reflectivity cover a broad range of the applications of this technique and the related X-ray and neutron scattering experiments of SAXS, SANS, GISAXS, and GISANS. ...

Jeffrey Penfold

2009-03-31T23:59:59.000Z

447

COUPLED MULTI-GROUP NEUTRON PHOTON TRANSPORT FOR THE SIMULATION OF HIGH-RESOLUTION GAMMA-RAY SPECTROSCOPY APPLICATIONS  

SciTech Connect

The accurate and efficient simulation of coupled neutron-photon problems is necessary for several important radiation detection applications. Examples include the detection of nuclear threats concealed in cargo containers and prompt gamma neutron activation analysis for nondestructive determination of elemental composition of unknown samples.

Burns, Kimberly A.

2009-08-01T23:59:59.000Z

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About Neutrons  

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Neutron Basics Neutron Basics A neutron is one of the fundamental particles that make up matter. This uncharged particle exists in the nucleus of a typical atom, along with its positively charged counterpart, the proton. Protons and neutrons each have about the same mass, and both can exist as free particles away from the nucleus. In the universe, neutrons are abundant, making up more than half of all visible matter. Find Out What a Neutron Is Youtube icon Properties of Neutrons How Can Neutrons Be Used for Research? Image of glucose movement in plants Neutron imaging techniques have been able to determine the precise movement of glucose in plants. This knowledge can help scientists better understand how biomass can be efficiently converted into fuel. Neutrons have many properties that make them ideal for certain types of