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Title: Comparison of discrete and continuous thermal neutron scattering treatments in MCNP5

The standard discrete thermal neutron S({alpha},{beta}) scattering treatment in MCNP5 is compared with a continuous S({alpha},{beta}) scattering treatment using a criticality suite of 119 benchmark cases and ENDF/B-VII.0 nuclear data. In the analysis, six bound isotopes are considered: beryllium metal, graphite, hydrogen in water, hydrogen in polyethylene, beryllium in beryllium oxide and oxygen in beryllium oxide. Overall, there are only small changes in the eigenvalue (k{sub eff}) between discrete and continuous treatments. In the comparison of 64 cases that utilize S({alpha},{beta}) scattering, 62 agreed at the 95% confidence level, and the 2 cases with differences larger than 3 {sigma} agreed within 1 {sigma} when more neutrons were run in the calculations. The results indicate that the changes in eigenvalue between continuous and discrete treatments are random, small, and well within the uncertainty of measured data for reactor criticality experiments. (authors)
Authors:
 [1] ;  [2] ;  [1] ;  [2]
  1. Univ. of Michigan, Dept. of Nuclear Engineering and Radiological Sciences, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States)
  2. Los Alamos National Laboratory, Monte Carlo Codes Group, MS A143, PO Box 1663, Los Alamos, NM 87545 (United States)
Publication Date:
OSTI Identifier:
22105627
Resource Type:
Conference
Resource Relation:
Conference: PHYSOR 2012: Conference on Advances in Reactor Physics - Linking Research, Industry, and Education, Knoxville, TN (United States), 15-20 Apr 2012; Other Information: Country of input: France; 12 refs.
Publisher:
American Nuclear Society - ANS; La Grange Park, IL (United States)
Research Org:
American Nuclear Society, Inc., 555 N. Kensington Avenue, La Grange Park, Illinois 60526 (United States)
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; BENCHMARKS; BERYLLIUM; BERYLLIUM OXIDES; COMPARATIVE EVALUATIONS; CRITICALITY; EIGENVALUES; FISSION; GRAPHITE; HYDROGEN; HYDROGEN ISOTOPES; NEUTRON DIFFRACTION; NUCLEAR DATA COLLECTIONS; POLYETHYLENES; REACTOR SAFETY; THERMAL NEUTRONS