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2014 International Conference on Physics of Reactors, PHYSOR 2014

作者： Yi, Ce Sjoden, Glenn Edgar, Chris Nuclear and Radiological Engineering Program George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology AtlantaGA United States

Multi-group cross section library generation plays an important role in deterministic transport simulations. In this paper, a new fine-group to broad-group cross section collapsing method is introduced. Rather than a traditional flux weighting, the new method uses a hybrid weighing scheme to collapse the scattering cross section matrix. Based upon a matrix analysis approach, we generalize different weighting schemes and derive the new hybrid weighting scheme, which mathematically shows that it is rational for the scattering cross section to be weighted by the (i) forward fluxes of the incoming/in-bound neutron groups and (ii) the adjoint functions of the outgoing/out-bound neutron energy groups. This approach also makes physical sense, since it conserves the "importance flow" of particles through scattering while collapsing cross sections. To conserve the reaction rates at the same time, we re-normalize the hybrid weighted scattering cross section to the original library total scattering reaction rate. We demonstrate that the hybrid weighting scheme is more accurate, especially for the detector response simulation problem in a Dual-Range Coincidence Counter (DRCC) 3-D SN transport model. © 2014 Westinghouse Electric Company LLC. All Rights Reserved.

关键词： Reaction rates

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Application of the TITAN hybrid deterministic transport code to medical physics 18

Application of the TITAN hybrid deterministic transport code...

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18th Topical Meeting of the Radiation Protection and Shielding Division of ANS, RPSD 2014

作者： Haghighat, Alireza Royston, Katherine Yi, Ce Nuclear Engineering Program Department of Mechanical Engineering Virginia Tech: 900N Glebe Rd. ArlingtonVA United States Nuclear and Radiological Engineering and Medical Physics Program Georgia Tech: 770 State Street AtlantaGA United States

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Federal Guidance Report 15: External exposure to radionuclides in soil, air, and water

Federal Guidance Report 15: External exposure to radionuclid...

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2015 Transactions of the American nuclear Society, ANS 2015

作者： Hertel, N.E. Eckerman, K.F. Bellamy, M.B. Easterly, C.E. Leggett, R.W. Ryman, J.C. Stewart, D.J. Boyd, M. Center for Radiation Protection Knowledge Oak Ridge National Laboratory PO Box 2008 MS6335 Oak Ridge TN37831-6335 United States Nuclear and Radiological Engineering Program Georgia Institute of Technology AtlantaGA20221-0745 United States Easterly Scientific Inc. 6412 Westminster Road KnoxvilleTN37919 United States Private Consultant United States U.S. Environmental Protection Agency 1200 Pennsylvania Ave. NW WashingtonDC20460 United States

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Application of the efficient consistent spatial homogenization method in neutron transport theory to a gas cooled thermal reactor problem

Application of the efficient consistent spatial homogenizati...

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2014 International Conference on Physics of Reactors, PHYSOR 2014

作者： Yasseri, Saam Rahnema, Farzad Nuclear and Radiological Engineering/Medical Physics Program George W. Woodruff School Georgia Institute of Technology AtlantaGA30332-0405 United States

In this paper, the accuracy and computational efficiency of the efficient consistent spatial homogenization method (ECSH) in neutron transport theory is assessed in a 1D benchmark problem characteristic of gas cooled thermal systems that are extremely challenging for conventional homogenization methods because of their longer neutron mean free path than water-based thermal reactors . The ECSH method is an extension of the consistent spatial homogenization method by using: (1) B-spline instead of Fourier series for the expansion of the spatial domain in the auxiliary cross section term and (2) a source iteration scheme instead of local fixed-source calculations in the re-homogenization procedure. Furthermore, the effect of the angular expansion order in the definition of the auxiliary cross section is studied. This method can be viewed as a significant improvement in accuracy of standard homogenization methods used for VHTR whole core analysis in which core environment effects are pronounced. It is shown that the ECSH method can reproduce the heterogeneous transport solution with up to 4 times faster computational speed, depending on the configuration of the control rods while maintaining reasonable accuracy and robust re-homogenization procedure. © Proceedings of the International Conference on Physics of Reactors, PHYSOR 2014. All right reserved.

关键词： Homogenization method

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Implementation and verification of the SDM in the titan 3-D SN transport code

Implementation and verification of the SDM in the titan 3-D ...

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2014 International Conference on Physics of Reactors, PHYSOR 2014

作者： Roskoff, Nathan Walters, William Haghighat, Alireza Yi, Ce Sjoden, Glenn Nuclear Engineering Program Department of Mechanical Engineering Virgina Tech 900 N. Glebe Road ArlingtonVA22203 United States Nuclear and Radiological Engineering Medical Physics Programs George W. Woodruff School Georgia Tech AtlantaGA United States

The subgroup decomposition method (SDM) has recently been developed as an improvement over the consistent generalized energy condensation theory for treatment of the energy variable in deterministic particle transport problems. By explicitly preserving reaction rates of the fine-group energy structure, the SDM directly couples a consistent coarse-group transport calculation with a set of fixed-source "decomposition sweeps" to provide a fine-group flux spectrum. This paper will outline the implementation of the SDM into a three-dimensional, SN deterministic transport code such as TITAN. The new version of TITAN, TITAN-SDM, is tested using a 1-D benchmark problem based on the High Temperature engineering Test Reactor (HTTR) in Japan. In addition to accuracy, this study examines the efficiency of the SDM algorithm in a 3-D SN transport code. © 2014 Westinghouse Electric Company LLC. All Rights Reserved.

关键词： Condensation

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Abstracts from Hydrocephalus 2016 Abstracts

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FLUIDS AND BARRIERS OF THE CNS 2017年第SUPPL 1期14卷 1-21页

作者： [Anonymous] Johns Hopkins University Baltimore MD USA. Department of Neurosurgery Johns Hopkins University Baltimore MD USA. Johns Hopkins Biostatistics Center Johns Hopkins Bloomberg School of Public Health Baltimore MD USA. Johns Hopkins Bloomberg School of Public Health Baltimore MD USA. Department of Neurosurgery Johns Hopkins University School of Medicine Baltimore MD USA. Johns Hopkins Aramco Healthcare Dhahran Saudi Arabia. Johns Hopkins Hopkins Aramco Healthcare Dhahran Saudi Arabia. Johns Hopkins Aramco Healthcare Ras Tanura Saudi Arabia. Primary Care Johns Hopkins Aramco Healthcare Ras Tanura Saudi Arabia. Bloomberg School of Public Health Johns Hopkins University Baltimore MD USA. Department of Neurosurgery Rhode Island Hospital Providence RI USA. Department of Epidemiology Johns Hopkins Bloomberg School of Public Health Baltimore MD USA. The Interface Group Institute of PhysiologyUniversity of Zurich Zurich Switzerland. Institute of Physiology University of Zurich Zurich Switzerland. Neuroscience Center Zurich and the Zurich Center for Integrative Human Physiology University of Zurich Zurich Switzerland. BioFlowImage Laboratory University of Picardie Jules Verne Amiens France. Reims Mathematics Laboratory University of Reims Champagne-Ardenne Reims France. Image Processing Laboratory University Hospital of Amiens-Picardie Amiens France. BioFlowImage Laboratory Department of Medical Image Processing University Hospital of Picardie Jules Verne Amiens France. Department of Geriatric University Hospital of Toulouse Toulouse France. Departments of Geriatric University Hospital of Toulouse Toulouse France. Department of Geriatry University Hospital Toulouse Toulouse France. Neurosciences department University of Cambridge Cambridge UK. Brain Physics Lab Academic Neurosurgery University of Cambridge Cambridge UK. Department of Nuclear Medicine University Hospital of Toulouse Toulouse France. Department of Nuclear Medicine University Hospit

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Neutron background variation with altitude

Neutron background variation with altitude

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2013 Winter Meeting on Transactions and Embedded Topical Meetings: Risk Management for Complex Socio-Technical Systems, 2nd ANS SMR 2013 Conference, nuclear Nonproliferation - 1st Fission to the Future

作者： Gunning, John E. Enders, Alexander L. Chapman, Jeffrey A. Croft, Stephen Sjoden, Glenn E. Oak Ridge National Laboratory United States Nuclear and Radiological Engineering Program Georgia Institute of Technology United States

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SNM neutron detection using a time-gated synthetic aperture hybrid approach

SNM neutron detection using a time-gated synthetic aperture ...

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International Conference on Mathematics and Computational Methods Applied to nuclear Science and engineering, M and C 2013

作者： Molinar, M. Yi, C. Edgar, C.A. Manalo, K. Chin, M. Sjoden, G. Nuclear and Radiological Engineering Program George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology 770 State Street Atlanta GA 30332-0745 United States

ISBN: (纸本)9781627486439

This work focuses on using forward and adjoint transport in a hybrid application of 3-D deterministic (PENTRAN) and Monte Carlo (MCNP5) codes to model a series of neutron detector blocks. These blocks, or "channels, " contain a unique set of moderators with 4 atm He-3 detectors tuned to detect and profile a gross energy spectrum of a passing neutron (SNM) source. Ganging the units together as a large area system enables one to apply time gating the source-detector response to maximize signal to noise responses from a passing source with minimal background;multiple units may be positioned as a collective synthetic aperture detector array to be used as a way of performing real time neutron spectroscopy for detecting special nuclear materials in moving vehicles. The initial design, detector response coupling, confirmation of initial design functionality using adjoint transport calculations, and realistic simulation using PENTRAN and MCNP5 are presented. Future work will include optimization and application to realistic scenarios and additional sources.

关键词： Signal to noise ratio

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Development and application of a hybrid transport methodology for active interrogation systems

Development and application of a hybrid transport methodolog...

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International Conference on Mathematics and Computational Methods Applied to nuclear Science and engineering, M and C 2013

作者： Royston, Katherine Walters, William Haghighat, Alireza Yi, Ce Sjoden, Glenn Nuclear Engineering Program Department of Mechanical Engineering Virginia Tech. 900 N Glebe Rd. Arlington VA 22203 United States Nuclear and Radiological Engineering Georgia Tech 801 Ferst Drive Atlanta GA 30332 United States

ISBN: (纸本)9781627486439

A hybrid Monte Carlo and deterministic methodology has been developed for application to active interrogation systems. The methodology consists of four steps: i) neutron flux distribution due to neutron source transport and subcritical multiplication;ii) generation of gamma source distribution from (n, 7) interactions;iii) determination of gamma current at a detector window;iv) detection of gammas by the detector. This paper discusses the theory and results of the first three steps for the case of a cargo container with a sphere of HEU in third-density water cargo. To complete the first step, a response-function formulation has been developed to calculate the subcritical multiplication and neutron flux distribution. Response coefficients are pre-calculated using the MCNP5 Monte Carlo code. The second step uses the calculated neutron flux distribution and Bugle-96 (n, 7) cross sections to find the resulting gamma source distribution. In the third step the gamma source distribution is coupled with a pre-calculated adjoint function to determine the gamma current at a detector window. The AIMS (Active Interrogation for Monitoring Special-nuclear-Materials) software has been written to output the gamma current for a source-detector assembly scanning across a cargo container using the pre-calculated values and taking significantly less time than a reference MCNP5 calculation.

关键词： Neutron sources

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Mobile Pit verification system design based on passive special nuclear material verification in weapons storage facilities

Mobile Pit verification system design based on passive speci...

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International Conference on Mathematics and Computational Methods Applied to nuclear Science and engineering, M and C 2013

作者： Paul, Jessica N. Chin, Michael R. Sjoden, Glenn E. Nuclear and Radiological Engineering Program George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology 770 State St Atlanta GA 30332-0745 United States

ISBN: (纸本)9781627486439

A mobile "drive by" passive radiation detection system to be applied in special nuclear materials (SNM) storage facilities for validation and compliance purposes has been designed through the use of computational modeling and new radiation detection methods. This project was the result of work over a 1 year period to create optimal design specifications to include creation of 3D models using both Monte Carlo and deterministic codes to characterize the gamma and neutron leakage out each surface of SNM-bearing canisters. Results were compared and agreement was demonstrated between both models. Container leakages were then used to determine the expected reaction rates using transport theory in the detectors when placed at varying distances from the can. A "typical" background signature was incorporated to determine the minimum signatures versus the probability of detection to evaluate moving source protocols with collimation. This established the criteria for verification of source presence and time gating at a given vehicle speed. New methods for the passive detection of SNM were employed and shown to give reliable identification of age and material for highly enriched uranium (HEU) and weapons grade plutonium (WGPu). The finalized "Mobile Pit Verification System" (MPVS) design demonstrated that a "drive-by" detection system, collimated and operating at nominally 2 mph, is capable of rapidly verifying each and every weapon pit stored in regularly spaced, shelved storage containers, using completely passive gamma and neutron signatures for HEU and WGPu. This system is ready for real evaluation to demonstrate passive total material accountability in storage facilities.

关键词： Containers

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