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dc.contributor.authorBrown, Forrest B.
dc.contributor.authorWalsh, Jonathan Alan
dc.contributor.authorForget, Benoit Robert Yves
dc.contributor.authorSmith, Kord S.
dc.date.accessioned2018-01-26T14:44:21Z
dc.date.available2018-01-26T14:44:21Z
dc.date.issued2016-03
dc.identifier.issn2100-014X
dc.identifier.urihttp://hdl.handle.net/1721.1/113297
dc.description.abstractIn this work we describe the development and application of computational methods for processing neutron cross section data in the unresolved resonance region (URR). These methods are integrated with a continuous-energy Monte Carlo neutron transport code, thereby enabling their use in high-fidelity analyses. Enhanced understanding of the effects of URR evaluation representations on calculated results is then obtained through utilization of the methods in Monte Carlo integral benchmark simulations of fast spectrum critical assemblies. First, we present a so-called on-the-fly (OTF) method for calculating and Doppler broadening URR cross sections. This method proceeds directly from ENDF-6 average unresolved resonance parameters and, thus, eliminates any need for a probability table generation pre-processing step in which tables are constructed at several energies for all desired temperatures. Significant memory reduction may be realized with the OTF method relative to a probability table treatment if many temperatures are needed. Next, we examine the effects of using a multi-level resonance formalism for resonance reconstruction in the URR. A comparison of results obtained by using the same stochastically-generated realization of resonance parameters in both the single-level Breit-Wigner (SLBW) and multi-level Breit-Wigner (MLBW) formalisms allows for the quantification of level-level interference effects on integrated tallies such as k eff and energy group reaction rates. Though, as is well-known, cross section values at any given incident energy may differ significantly between single-level and multi-level formulations, the observed effects on integral results are minimal in this investigation. Finally, we demonstrate the calculation of true expected values, and the statistical spread of those values, through independent Monte Carlo simulations, each using an independent realization of URR cross section structure throughout. It is observed that both probability table and OTF treatments reproduce the true expected values, calculated by averaging the results of many independent simulations, quite well. However, the spread of independent calculation results is shown to be relatively significant. The k eff eigenvalues for fast spectrum systems can differ by more than 250 pcm from one simulation to the next.en_US
dc.publisherEDP Sciencesen_US
dc.relation.isversionofhttp://dx.doi.org/10.1051/EPJCONF/201611106001en_US
dc.rightsCreative Commons Attribution 4.0 International Licenseen_US
dc.rights.urihttp://creativecommons.org/licenses/by/4.0en_US
dc.sourceEPJ Web of Conferencesen_US
dc.titleNeutron Cross Section Processing Methods for Improved Integral Benchmarking of Unresolved Resonance Region Evaluationsen_US
dc.typeArticleen_US
dc.identifier.citationWalsh, Jonathan A. et al. “Neutron Cross Section Processing Methods for Improved Integral Benchmarking of Unresolved Resonance Region Evaluations.” Edited by O. Serot. EPJ Web of Conferences 111 (2016): 06001.© 2016 Owned by the authors, published by EDP Sciencesen_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Nuclear Science and Engineeringen_US
dc.contributor.mitauthorWalsh, Jonathan Alan
dc.contributor.mitauthorForget, Benoit Robert Yves
dc.contributor.mitauthorSmith, Kord S.
dc.relation.journalEPJ Web of Conferencesen_US
dc.eprint.versionFinal published versionen_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dc.date.updated2018-01-19T20:17:26Z
dspace.orderedauthorsWalsh, Jonathan A.; Forget, Benoit; Smith, Kord S.; Brown, Forrest B.en_US
dspace.embargo.termsNen_US
dc.identifier.orcidhttps://orcid.org/0000-0002-2542-1149
dc.identifier.orcidhttps://orcid.org/0000-0003-1459-7672
dc.identifier.orcidhttps://orcid.org/0000-0003-2497-4312
mit.licensePUBLISHER_CCen_US


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