Advanced interpretation of the SPHERE irradiation experiment with neutronics and fuel performance codes

The SPHERE experiment aimed at studying the behaviour of Minor Actinide-bearing Driver Fuel (U,Pu,Am)O$_{2-x}$ by comparing sphere-packed and pelletized fuels. The irradiation experiment was performed in the High Flux Reactor at Petten from August 2013 to April 2015, and was followed by post-irradiation examinations up to mid-2017. The present work consists in a new analysis of the SPHERE experiment, focusing on the pelletized fuel, by the means of both neutronics and fuel performance codes. This study is performed in the frame of the European Project PATRICIA. The adopted methodology and the main results achieved, assessed in particular against inert gas-related experimental data, are presented in the paper.