Qualification of the neutronic efficiency of erbium at zero burnup

Abstract The main asset of erbium as an alternative burnable poison to gadolinium is that it has a much lower thermal absorption efficient cross section that contributes to giving it much slower consumption kinetics than gadolinium, and also helps to generate much lower perturbation in the power distribution. The calculations performed with the APOLLO code and its associated library must be qualified and validated with an experiment in order to obtain a sufficient degree of confidence to envisage an industrial application of this poison. For this purpose the MIRTE UOX and MOX experiments were performed in the critical reactor EOLE at Cadarache within the framework of the EROINE programme. These experiments concern the neutronic assessment of a (U,Er)O 2 rod in a representative core of a pressurised water reactor lattice with an enhanced moderation ratio. The purpose of this paper is to show that the APOLLO2 code associated with its APOLLIB CEA 93 library is perfectly qualified at time zero to calculate erbium reactivity worth.