A novel method has been developed to calculate sensitivity coefficients in coupled Boltzmann/Bateman problem for nuclear data (ND) uncertainties propagation on the reactivity and is here extended to power factors. Different uncertainty propagation methodologies, such as One-Ata-Time and hybrid Monte-Carlo / deterministic methods have been tested and are discussed on an actual example of ND uncertainty problem on a MTR-type reactor benchmark. Those methods, unlike total Monte Carlo sampling for uncertainty propagation and quantification (UQ), allow obtaining sensitivity coefficients, as well as correlations values between nuclear data, during the depletion calculation for global neutronics parameters such as reaction rates. The methodologies are compared to a pure MC sampling method, usually considered as the "reference" method. The present paper extends the development to power factor by introducing a new methodology enabling to decorrelate direct and transmutation terms for local factors. The total uncertainty can be decomposed in two effects: a direct effect coming from the perturbation and an effect coming from transmutation. The most impacting ND are the scattering reactions, principally coming from 27 Al and H 2 O. The overall effect is a reduction of the propagated uncertainties throughout the cycle thanks to negatively correlated terms.
Bayesian methods are known for treating the so-called data re-assimilation. The Bayesian inference applied to core physics allows to get a new adjustment of nuclear data using the results of integral experiments. This theory leading to reassimliation encompasses a broader approach. In previous papers, new methods have been developed to calculate the impact of nuclear and manufacturing data uncertainties on neutronics parameters. Usually, adjustment is performed step by step with one parameter and one experiment by batch. In this document, we rewrite Orlov theory to extend to multiple experimental values and parameters adjustment. We found that the multidimensional system expression looks like can be written as the monodimensional system in a matrix form. In this extension, correlation terms appears between experimental processes (manufacturing and measurements) and we discuss how to fix them. Then formula are applied to the extension to the Boltzmann/Bateman coupled problem, where each term could be evaluated by computing depletion uncertainties, studied in previous papers.
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