Assessment of the 153Eu and 154Eu neutron capture cross sections from the integral data assimilation of used nuclear fuel experiments

Abstract

The purpose of this paper is to make the most of a large set of used nuclear fuel experiments for determining integral trends on the 153Eu(n,γ) and 154Eu(n,γ) reactions cross sections. The assimilation of the integral trends is based on a linear least-square fitting procedure relying on the Bayes’ theorem. Realistic uncertainties are obtained thanks to a marginalization technique. The method is applied to the 153Eu and 154Eu capture cross sections recommended in the evaluated nuclear data library JEFF-3.1.1. Our results indicate an underestimation of both capture cross-sections of approximately 4.9% and 7.1%, respectively. For 153Eu, our study suggests to increase the capture resonance integral from I0 = 1409 barns to I0 = 1502 ± 68 barns. This trend is consistent with the capture resonance integral I0 = 1560 ± 4 barns obtained from recent time-of-flight measurements carried out at the Renssealer Polytechnic Institute. The trend obtained in this work on 154Eu capture cross section is also consistent with a recent analysis that confirms its underestimation.