Temperature Effects of Resonance Scattering for Epithermal Neutrons in MCNP
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- University of Michigan, Ann Arbor, MI (United States)
Epithermal neutron elastic scattering can be significantly affected by the thermal motion of target nuclides. Since the 1950s 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 ENDFIB-VII nuclear data.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
- DOE Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1121992
- Report Number(s):
- LA-UR-11-06503; LA-UR-11-6503
- Resource Relation:
- Conference: PHYSOR-2012, ans Reactor Physics Conference, Knoxville, TN (United States), 15 Apr 2012
- Country of Publication:
- United States
- Language:
- English
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