Evaluation of the feasibility of the powder injection moulding process for the fabrication of nuclear fuel and comparison of several formulations

Abstract Six forming aid formulations were used to assess the nuclear fuel elaboration by means of the powder injection moulding (PIM) process. These formulations were especially designed for actinide powders (UO 2 and MOX) by taking into account the specificities of these powders, in particular any solutions to prevent radiolysis. Once the feedstocks with the UO 2 powder had been prepared, the thermal studies showed no significant endothermic or exothermic reaction, which demonstrates the quasi-independent behaviour of the polymer system with respect to the uranium dioxide powder. The mass of the carbon residues – a key criterion in selecting a formulation – was below 150 ppm for all six formulations, which is still sufficient for obtaining net-shaped pellets following the sintering process. The formulations to be recommended for the nuclear fuel application are those containing polystyrene as they achieve satisfactory deagglomeration combined with an adequate level of injectability (low shear viscosity of the system). Moreover, they are theoretically resistant to radiolysis phenomena due to the benzene rings of the polystyrene.