MCNPX analysis of delayed neutron fraction in berylliumreflected cores

Silva Kalcheva, Edgar Koonen

Research outputpeer-review

1 Scopus citations


The behavior of the effective delayed neutron and effective delayed photo neutron frac-tions in beryllium reflected cores is investigated. An MCNPX analysis of the dependence of the effective beta fractions on the fuel depletion is performed for different fuel types. An alternative method for estimation of the delayed neutron fraction during the reactor operation, avoiding double criticality simulation on prompt neutrons only (), is compared to the standard MCNP approach (1-+/).The methodology is based on MCNP tally calculations of fission integrals and actual delayed neutron fraction, for each fissile isotope m(235U, 239Pu, 241Pu) in a given reactor configuration and fuel type. The methodologyis verified on a generic infinite lattice and after that applied forthe MCNP whole core model of the BR2 reactor at different depletion stepsduring the reac-tor operation. The influence of the poisoning of the beryllium reflector on the effective beta fraction is also studied. Criticality and spectra calculations taking into accountdelayed neutronsand delayed photo neutronsare performed using MCNPX 2.7.0.

Original languageEnglish
Title of host publicationProceedings of the International Conference on Physics of Reactors, PHYSOR 2014
StatePublished - Aug 2014
Event2014 - PHYSOR : The Role of Reactor Physics toward a Sustainable Future - The Westin Miyako, Kyoto
Duration: 28 Sep 20143 Oct 2014


Conference2014 - PHYSOR
Internet address

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering

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