Sensitivity of MCNP5 calculations for a spherical numerical benchmark problem to the angular scattering distributions for deuterium

Conference · Sat Jul 01 00:00:00 EDT 2006

OSTI ID:22039591

Kozier, K S ^[1]

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1. Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ont. K0J 1J0 (Canada)

This paper examines the sensitivity of MCNP5 k{sub eff} results to various deuterium data files for a simple benchmark problem consisting of an 8.4-cm radius sphere of uranium surrounded by an annulus of deuterium at the nuclide number density corresponding to heavy water. This study was performed to help clarify why {Delta}k{sub eff} values of about 10 mk are obtained when different ENDF/B deuterium data files are used in simulations of critical experiments involving solutions of high-enrichment uranyl fluoride in heavy water, while simulations of low-leakage, heterogeneous critical lattices of natural-uranium fuel rods in heavy water show differences of <1 mk. The benchmark calculations were performed as a function of deuterium reflector thickness for several uranium compositions using deuterium ACE files derived from ENDF/B-VII.b1 (release beta 1), ENDF/B-VI.4 and JENDL-3.3, which differ primarily in the energy/angle distributions for elastic scattering <3.2 MeV. Calculations were also performed using modified ACE files having equiprobable cosine bin values in the centre-of-mass reference frame in a progressive manner with increasing energy. It was found that the {Delta}k{sub eff} values increased with deuterium reflector thickness and uranium enrichment. The studies using modified ACE files indicate that most of the reactivity differences arise at energies <1 MeV; hence, this energy range should be given priority if new scattering distribution measurements are undertaken. (authors)

• Research Organization: American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 22039591
• Resource Relation: Conference: PHYSOR-2006: American Nuclear Society's Topical Meeting on Reactor Physics - Advances in Nuclear Analysis and Simulation, Vancouver, BC (Canada), 10-14 Sep 2006; Other Information: Country of input: France; 12 refs.
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
22 GENERAL STUDIES OF NUCLEAR REACTORS
ANGULAR DISTRIBUTION
BENCHMARKS
CENTER-OF-MASS SYSTEM
DEUTERIUM
ELASTIC SCATTERING
ENERGY SPECTRA
FUEL RODS
HEAVY WATER
HETEROGENEOUS REACTOR CORES
HIGHLY ENRICHED URANIUM
MATHEMATICAL SOLUTIONS
MEV RANGE
MULTIPLICATION FACTORS
NATURAL URANIUM
NEUTRON DIFFRACTION
NUCLEAR DATA COLLECTIONS
REACTIVITY
SPHERICAL CONFIGURATION
URANYL FLUORIDES