Generation of fission yield covariances to correct discrepancies in the nuclear data libraries

Luca Fiorito, Alexey Stankovskiy, Gert Van den Eynde, Carlos Javier Diez, Oscar Cabellos, Pierre-Etienne Labeau

    Research outputpeer-review


    Fission yield uncertainties and correlations should be considered in the uncertainty quantification of burnup responses — e.g. isotopic inventory, effective neutron multiplication factor keff . Although nuclear data libraries generally provide independent fission yield uncertainties along with the best estimates, currently they lack complete covariance matrices. In addition, several inconsistencies were detected amongst the current fission yield evaluated uncertainties, which could impact on uncertainty quantification (UQ) studies. As a part of this work, we introduced fission yield correlations to sort out the data
    inconsistency found in the JEFF-3.1.1 fission yield library. Such correlations are produced using an iterative generalised least square (GLS) updating technique, with conservation equations acting as fitting models. The process revises the fission yield estimates and covariances according to reliable evaluations,
    when available, or conservation criteria. We chose to work with the PWR fuel rod model of the REBUS international program to test the new covariances, since experimental uncertainties on several concentrations are available. We propagated the original and updated fission yield covariances using a sampling approach and we quantified the uncertainty of keff and nuclide densities in the chosen burnup problem. The response uncertainty for keff and nuclide densities showed a sharp drop when using the new set of fission yield covariance matrices.
    Original languageEnglish
    Pages (from-to)12-23
    Number of pages12
    JournalAnnals of nuclear energy
    StatePublished - 1 Feb 2016

    ASJC Scopus subject areas

    • General Physics and Astronomy

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