Monte Carlo analysis of high moderation 100% MOX BWR cores using JEF2 and JENDL3 nuclear data

This paper presents a Monte Carlo analysis of the BASALA neutron physics programme implemented in the EOLE facility at CEA Cadarache. This programme comprised two types of cores simulating hot (BASALA-H) and cold (BASALA-C) conditions. Reference and 'poisoned' configurations were investigated in both cases. The BASALA-H core included a configuration with extra water rods in order to simulate over moderated conditions and a configuration with fuel pin thick over-clads in order to simulate 70% void conditions while the BASALA-C core included configurations with cross shaped control blades. Different kinds of physical parameters were measured and calculated as the effective multiplication factor, reactivity worth of control blades, gadolinium pins and fission rate distributions. The experiment and calculation comparisons are satisfactory and demonstrate the ability of French and Japanese reference calculation tools to predict the main neutronic parameters of 100% MOX BWRs. (authors)