Hybrid technique in scale for fission source convergence applied to used nuclear fuel analysis

A. M. Ibrahim, D. E. Peplow, K. B. Bekar, C. Celik, J. M. Scaglione, D. Ilas, J. C. Wagner

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

5 Scopus citations

Abstract

For some criticality safety applications, reliably achieving convergence in the Monte Carlo eigenvalue simulations can be challenging. Inadequate source convergence typically corresponds to an underestimation of the effective neutron multiplication factor (keff) - a very troublesome possibility in the field of criticality safety. To reduce the likelihood of this possibility, a new automated source convergence sequence (Sourcerer) has been developed in SCALE to deterministically compute the fission distribution and to use it as the starting source in the Monte Carlo eigenvalue calculation. In addition to decreasing the probability of underpredicting keff due to inadequate source convergence, the sequence eliminates the guesswork associated with defining an appropriate, problem-dependent starting source. Furthermore, Sourcerer can increase the efficiency of the overall simulation by decreasing the number of generations (cycles) that must be skipped prior to keff accumulation. To evaluate its effectiveness, Sourcerer was applied to an actual used nuclear fuel canister that had previously demonstrated source convergence difficulties due to significant variation in loaded assembly burnup values and significant neutronic decoupling between assemblies. Compared to the common use of a starting source distributed uniformly in all fissionable regions, the use of Sourcerer increased the reliability of the keff calculation for all cases in which the number of skipped cycles was below ∼350; for cases with higher numbers of skipped cycles the reliability was essentially equivalent. Additionally, for a fixed uncertainty objective, the use of Sourcerer increased the efficiency of the keff calculation by 71% compared to a Monte Carlo calculation with a uniform starting source.

Original languageEnglish
Title of host publicationTopical Meeting Held by the ANS Nuclear Criticality Safety Division, NCSD 2013 - Criticality Safety in the Modern Era
Subtitle of host publicationRaising the Bar
PublisherAmerican Nuclear Society
Pages87-98
Number of pages12
ISBN (Print)9781629938165
StatePublished - 2013
EventTopical Meeting Held by the ANS Nuclear Criticality Safety Division - Criticality Safety in the Modern Era: Raising the Bar, NCSD 2013 - Wilmington, NC, United States
Duration: Sep 29 2013Oct 3 2013

Publication series

NameTopical Meeting Held by the ANS Nuclear Criticality Safety Division, NCSD 2013 - Criticality Safety in the Modern Era: Raising the Bar

Conference

ConferenceTopical Meeting Held by the ANS Nuclear Criticality Safety Division - Criticality Safety in the Modern Era: Raising the Bar, NCSD 2013
Country/TerritoryUnited States
CityWilmington, NC
Period09/29/1310/3/13

Keywords

  • Canister-specific analysis
  • Fission source convergence
  • Hybrid Monte Carlo/deterministic
  • Monte Carlo eigenvalue
  • Used nuclear fuel

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