Abstract
The (U-Pu)O2 nuclear fuel is manufactured by means of the ceramic process, which includes thegrinding, pressing and sintering steps. All these steps are strongly dependent on the mechanicalbehaviour of (U-Pu)O2 agglomerates, reflecting the quasi-static or dynamic mechanical loading andinteractions between aggregates (intra-agglomerate interactions IAAI) of which they are composed.The quasi-static mechanical behavior of agglomerates has been studied by means of in-situ micro-compression tests at the Fuel characterisation laboratory of CEA-Marcoule Atalante facility. Thesetests allow us to extract the elasto-plastic parameters of agglomerates. To obtain clear insights on thephysical origins of the deformation and failure of agglomerates, we use a Discrete Element method(DEM) to build numerical spherical agglomerates composed of aggregates with different shapes bymeans of radial compaction. We investigate the influence of aggregate shapes and friction coefficientbetween aggregates on the microstructure and properties of the agglomerates such as packingfraction, connectivity, and bulk elastic modulus. After adding an adhesion force law betweenaggregates, the agglomerates are allowed to relax and then subjected to diametral compressionbetween two plates. We determine the fracture modes and breakage threshold as a function ofcohesion parameters and aggregate shapes. The simulation parameters are partially adjusted toexperimental measurements and the results are compared with micro-compression tests