Heterogeneous fuels for minor actinides transmutation: Fuel performance codes predictions in the EFIT case study

The integrated Project EUROTRANS (EUROpean research programme for the TRANSmutation of high level nuclear waste in ADS) undertook some research on fuels dedicated to MA transmutation. One of its main objectives is the conceptual design of a small sub-critical nuclear system loaded with uranium-free fuel to provide high MA transmutation efficiency. The domain AFTRA (Advanced Fuels for TRAnsmutation system) of IP EUROTRANS identified two composite fuel systems: a ceramic–ceramic (CERCER) where fuel particles are dispersed in a magnesia matrix, and a ceramic–metallic (CERMET) with a molybdenum matrix in the place of MgO matrix to host a ceramic fissile phase. This paper is focused on the thermomechanical state of the hottest fuel pins of two EFIT cores of 400MW(th) loaded with either CERCER or CERMET fuels. For calculations three fuel performance codes were used: FEMALE, TRAFIC and TRANSURANUS. The analysis was performed at the beginning of fuel life. Presented results were used for testing newly-developed models installed in the TRANSURANUS code to deal with such innovative fuels and T91 steel cladding. Agreement among codes predictions was satisfactory for fuel and cladding temperatures, pellet-cladding gap and mechanical stresses.