A mechanistic approach for the modelling of MOX fuel pellet sintering

Within the framework of their common R and D MOX fuel fabrication program, the CEA and the COGEMA have undertaken an important project to model the different stages of MOX fuel fabrication process. The objectives of this work are a better understanding of the complicated physico-chemical mechanisms which occur simultaneously during the reactive sintering of MOX fuel pellets; the modelling of this stage should ultimately allow the accurate prediction of the influences of fabrication parameters on the characteristics of the fabricated MOX fuel, thus reducing the number of research laboratory fabrication tests together with an optimisation of the process. A code is under construction, taking into account the physical mechanisms at the grain size scale (Pu concentration, grain size, shape of grains and motion of the grain boundaries); once validated by experimental and parametric tests, this code will describe the Pu distribution and local density of the pellets as functions of the sintering conditions, helping further developments of the fabrication process such as the obtention of advanced microstructures of improved MOX fuels. (author)