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Title: Temperature effects of resonance scattering for epithermal neutrons in MCNP

Abstract

Epithermal neutron elastic scattering can be significantly affected by the thermal motion of target nuclides. Since the 1950's continuous-energy Monte Carlo codes have generally accounted for the target motion using a free gas scattering model, with the assumption that the scattering cross-section is constant in energy. Recent work has shown the importance of resonance scattering, and several methods for an improved free-gas treatment have been developed. We have implemented a rejection-based sampling scheme in the MCNP free-gas treatment to account for cross-section variation. The modified MCNP code was used to investigate a number of practical concerns: results for an LWR Doppler defect benchmark; computational costs; and energy limits for the free-gas treatment. Additionally, the impact on a suite of ICSBEP criticality benchmark problems (at room temperature) was determined to be negligible, an important result since such problems are used extensively in testing and evaluating revisions to ENDF/B-VII nuclear data. (authors)

Authors:
 [1]; ;  [2];  [1]
  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:
Research Org.:
American Nuclear Society, Inc., 555 N. Kensington Avenue, La Grange Park, Illinois 60526 (United States)
OSTI Identifier:
22105628
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; 13 refs.
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; BENCHMARKS; CRITICALITY; CROSS SECTIONS; ELASTIC SCATTERING; EPITHERMAL NEUTRONS; MONTE CARLO METHOD; NUCLEAR DATA COLLECTIONS; RESONANCE SCATTERING; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0273-0400 K

Citation Formats

Sunny, E. E., Brown, F. B., Kiedrowski, B. C., and Martin, W. R. Temperature effects of resonance scattering for epithermal neutrons in MCNP. United States: N. p., 2012. Web.
Sunny, E. E., Brown, F. B., Kiedrowski, B. C., & Martin, W. R. Temperature effects of resonance scattering for epithermal neutrons in MCNP. United States.
Sunny, E. E., Brown, F. B., Kiedrowski, B. C., and Martin, W. R. Sun . "Temperature effects of resonance scattering for epithermal neutrons in MCNP". United States.
@article{osti_22105628,
title = {Temperature effects of resonance scattering for epithermal neutrons in MCNP},
author = {Sunny, E. E. and Brown, F. B. and Kiedrowski, B. C. and Martin, W. R.},
abstractNote = {Epithermal neutron elastic scattering can be significantly affected by the thermal motion of target nuclides. Since the 1950's continuous-energy Monte Carlo codes have generally accounted for the target motion using a free gas scattering model, with the assumption that the scattering cross-section is constant in energy. Recent work has shown the importance of resonance scattering, and several methods for an improved free-gas treatment have been developed. We have implemented a rejection-based sampling scheme in the MCNP free-gas treatment to account for cross-section variation. The modified MCNP code was used to investigate a number of practical concerns: results for an LWR Doppler defect benchmark; computational costs; and energy limits for the free-gas treatment. Additionally, the impact on a suite of ICSBEP criticality benchmark problems (at room temperature) was determined to be negligible, an important result since such problems are used extensively in testing and evaluating revisions to ENDF/B-VII nuclear data. (authors)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2012},
month = {7}
}

Conference:
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