Modelling and assessment of thermophysical properties of Am-bearing fuels for transmutation purposes in fast reactors

Minor Actinides (MAs) are produced inside nuclear reactor fuels under irradiation and are responsible of large part of the waste radiotoxicity. Partitioning and Transmutation (P&T) is identified as the strategy that can relax constraints on geological disposal, since transmutation of MAs via critical or subcritical fast spectrum irradiation facilities like MYRRHA is a valid path to reduce the waste hazard. One of the focuses of the PATRICIA Project is the development of fuel performance codes towards Am-bearing fuels and the computational study of their behaviour under irradiation, supporting the licencing and development of advanced designs of the MYRRHA reactor. This work focuses on the modelling of thermophysical properties of transmutation-type fuel concepts for fast reactor application, specifically of melting temperature, specific heat capacity and thermal conductivity of (U,Pu,Am)O2−x and (U,Am)O2−x . The modelling activity involves the latest atomic-scale/CALPHAD data on Am-bearing fuels achieved in the framework of PATRICIA. Developed models are verified and validated against separate-effect data, and implemented in the TRANSURANUS fuel performance code to simulate a past irradiation experiment (HEDL P-19 power-to-melt transient test) for the evaluation of the impact of new models on the pin performance and their integral validation.