Assimilation of integral experiments on high-energy nuclear parameters

Abstract

Current assimilation of integral experiments often consists in adjusting multi-group cross sections with feedbacks from critical reference benchmarks. In order to maintain the constraints coming from nuclear models, we present here a method to achieve assimilation of integral experiment on nuclear parameters, from which nuclear data are evaluated. This method, based on Bayesian inference, uses continuous energy reactivity sensitivities to nuclear parameters, throughout all the nuclear data types (cross section, angular distribution, energy distribution, fission multiplicity and spectrum). This improvement was made possible by coupling a stochastic transport code and a nuclear data evaluation code. The study of a test case – the assimilation of Jezebel ICSBEP benchmark on a plutonium-239 toy evaluation – shows that angular and energy distributions have a non-negligible impact on the assimilation process and results.