An improved target velocity sampling algorithm for free gas elastic scattering
Abstract
We present an improved algorithm for sampling the target velocity when simulating elastic scattering in a Monte Carlo neutron transport code that correctly accounts for the energy dependence of the scattering cross section. The algorithm samples the relative velocity directly, thereby avoiding a potentially inefficient rejection step based on the ratio of cross sections. Here, we have shown that this algorithm requires only one rejection step, whereas other methods of similar accuracy require two rejection steps. The method was verified against stochastic and deterministic reference results for upscattering percentages in ^{238}U. Simulations of a light water reactor pin cell problem demonstrate that using this algorithm results in a 3% or less penalty in performance when compared with an approximate method that is used in most production Monte Carlo codes
 Authors:
 Argonne National Lab. (ANL), Argonne, IL (United States)
 Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
 Publication Date:
 Research Org.:
 Argonne National Lab. (ANL), Argonne, IL (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
 Sponsoring Org.:
 USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC21)
 OSTI Identifier:
 1425283
 Alternate Identifier(s):
 OSTI ID: 1426092
 Report Number(s):
 LLNLJRNL745886
Journal ID: ISSN 03064549; 138571
 Grant/Contract Number:
 AC0206CH11357; AC5207NA27344
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Annals of Nuclear Energy (Oxford)
 Additional Journal Information:
 Journal Name: Annals of Nuclear Energy (Oxford); Journal Volume: 114; Journal Issue: C; Journal ID: ISSN 03064549
 Publisher:
 Elsevier
 Country of Publication:
 United States
 Language:
 English
 Subject:
 97 MATHEMATICS AND COMPUTING; Monte Carlo; algorithm; rejection; target velocity sampling; 22 GENERAL STUDIES OF NUCLEAR REACTORS
Citation Formats
Romano, Paul K., and Walsh, Jonathan A. An improved target velocity sampling algorithm for free gas elastic scattering. United States: N. p., 2018.
Web. doi:10.1016/j.anucene.2017.12.044.
Romano, Paul K., & Walsh, Jonathan A. An improved target velocity sampling algorithm for free gas elastic scattering. United States. doi:10.1016/j.anucene.2017.12.044.
Romano, Paul K., and Walsh, Jonathan A. 2018.
"An improved target velocity sampling algorithm for free gas elastic scattering". United States.
doi:10.1016/j.anucene.2017.12.044.
@article{osti_1425283,
title = {An improved target velocity sampling algorithm for free gas elastic scattering},
author = {Romano, Paul K. and Walsh, Jonathan A.},
abstractNote = {We present an improved algorithm for sampling the target velocity when simulating elastic scattering in a Monte Carlo neutron transport code that correctly accounts for the energy dependence of the scattering cross section. The algorithm samples the relative velocity directly, thereby avoiding a potentially inefficient rejection step based on the ratio of cross sections. Here, we have shown that this algorithm requires only one rejection step, whereas other methods of similar accuracy require two rejection steps. The method was verified against stochastic and deterministic reference results for upscattering percentages in 238U. Simulations of a light water reactor pin cell problem demonstrate that using this algorithm results in a 3% or less penalty in performance when compared with an approximate method that is used in most production Monte Carlo codes},
doi = {10.1016/j.anucene.2017.12.044},
journal = {Annals of Nuclear Energy (Oxford)},
number = C,
volume = 114,
place = {United States},
year = 2018,
month = 2
}

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