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Correlation n¯¯p − s − x in the fast neutron range via integral information

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This paper presents a Bayesian approach based on integral experiments to create correlations which do not appear with differential data. Some quantities such as the fission cross section (s), neutron multiplicity (n¯p), neutron spectra (x), etc. are usually neither modeled together nor measured in coincidence, thus there is no correlation matrices in evaluated nuclear data libraries. | Correlation n p s x in the fast neutron range via integral information EPJ Nuclear Sci. Technol. 3 14 2017 Nuclear Sciences D. Rochman et al. published by EDP Sciences 2017 amp Technologies DOI 10.1051 epjn 2017009 Available online at http www.epj-n.org REGULAR ARTICLE Correlation n p s x in the fast neutron range via integral information Dimitri Rochman1 Eric Bauge2 Alexander Vasiliev1 and Hakim Ferroukhi1 1 Laboratory for Reactor Physics Systems Behaviour Paul Scherrer Institut Villigen Switzerland 2 CEA DAM DIF 91297 Arpajon cedex France Received 18 January 2017 Received in final form 20 March 2017 Accepted 20 March 2017 Abstract. This paper presents a Bayesian approach based on integral experiments to create correlations which do not appear with differential data. Some quantities such as the fission cross section s neutron multiplicity n p neutron spectra x etc. are usually neither modeled together nor measured in coincidence thus there is no correlation matrices in evaluated nuclear data libraries. One can nevertheless use the information from integral experiments such as fast criticality-safety benchmarks to correlate such quantities for possible inclusion in nuclear data libraries. A simple Bayesian set of equations is presented with random nuclear data similarly to the usual methods applied with differential data. An example for 239Pu is proposed. 1 Introduction unique theoretical model. For instance there is currently no measurements providing in coincidence a fission rate Covariance information for basic nuclear data quantities is related to the fission cross section s n f and the number nowadays necessary for various types of nuclear applica- of emitted prompt neutron per fission so-called nubar or tions. Many simulation tools are capable of using such n p . It can nevertheless be noted that some efforts are spent matrices to propagate nuclear data uncertainties on final to obtain such data as presented in reference 21 . In the quantities with either .