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 continuousenergy Monte Carlo codes have generally accounted for the target motion using a free gas scattering model, with the assumption that the scattering crosssection is constant in energy. Recent work has shown the importance of resonance scattering, and several methods for an improved freegas treatment have been developed. We have implemented a rejectionbased sampling scheme in the MCNP freegas treatment to account for crosssection 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 freegas 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/BVII nuclear data. (authors)
 Authors:

 Univ. of Michigan, Dept. of Nuclear Engineering and Radiological Sciences, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States)
 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), 1520 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 02730400 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 continuousenergy Monte Carlo codes have generally accounted for the target motion using a free gas scattering model, with the assumption that the scattering crosssection is constant in energy. Recent work has shown the importance of resonance scattering, and several methods for an improved freegas treatment have been developed. We have implemented a rejectionbased sampling scheme in the MCNP freegas treatment to account for crosssection 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 freegas 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/BVII nuclear data. (authors)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2012},
month = {7}
}