Thoughts on Sensitivity Analysis and Uncertainty Propagation Methods with Respect to the Prompt Fission Neutron Spectrum Impact on Critical Assemblies

The prompt fission neutron spectrum (PFNS) uncertainties in the n+239Pu fission reaction are used to study the impact on several fast critical assemblies modeled in the MCNP6.1 code. The newly developed sensitivity capability in MCNP6.1 is used to compute the keff sensitivity coefficients with respe...

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Bibliographic Details
Published inNuclear data sheets Vol. 123; pp. 109 - 114
Main Author Rising, M.E.
Format Journal Article
LanguageEnglish
Published United States Elsevier Inc 01.01.2015
Subjects
COMPARATIVE EVALUATIONS
DATA COVARIANCES
FISSION
FISSION NEUTRONS
NUCLEAR DATA COLLECTIONS
NUCLEAR PHYSICS AND RADIATION PHYSICS
PLUTONIUM 239
SENSITIVITY ANALYSIS
ZERO POWER REACTORS
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Summary:The prompt fission neutron spectrum (PFNS) uncertainties in the n+239Pu fission reaction are used to study the impact on several fast critical assemblies modeled in the MCNP6.1 code. The newly developed sensitivity capability in MCNP6.1 is used to compute the keff sensitivity coefficients with respect to the PFNS. In comparison, the covariance matrix given in the ENDF/B-VII.1 library is decomposed and randomly sampled realizations of the PFNS are propagated through the criticality calculation, preserving the PFNS covariance matrix. The information gathered from both approaches, including the overall keff uncertainty, is statistically analyzed. Overall, the forward and backward approaches agree as expected. The results from a new method appear to be limited by the process used to evaluate the PFNS and is not necessarily a flaw of the method itself. Final thoughts and directions for future work are suggested.
ISSN:0090-3752
1095-9904
DOI:10.1016/j.nds.2014.12.019