The NEA Expert Group on Innovative Fuel Elements (EGIFE), operating under the auspices of the Working Party on Scientific Issues of Advanced Fuel Cycles (WPFC), launched an activity to write a set of recommendations on properties of advanced fuels for fuel performance codes in 2018. 

This resulting report details a comprehensive set of recommendations concerning the thermophysical properties of oxide and metal nuclear fuels, crucial for assessing fuel performance and ensuring reactor safety. Formulated by experts using selected data, these recommendations aim to enhance the understanding of nuclear fuel properties, focusing on (U, Pu)O₂ and (U, Pu)Zr fuels, through international collaboration and expert insights.

The initiative focused on analysing experimental data to establish the thermophysical properties of fuels for Generation IV reactors. By targeting input parameters for fuel performance codes and sharing measurement data from the past two decades, experts conducted thorough assessments and formulated recommendations. These recommendations delineate application domains and associated uncertainties, providing a clearer understanding of the properties in question. 

The properties selected for recommendation include:

• Lattice parameter;
• Solidus temperature;
• Thermal expansion;
• Thermal conductivity;
• Specific heat;
• Elastic properties;
• Oxygen potential (specific to oxide fuels);
• Phase transitions (specific to metal fuels).

This report marks the first international effort to harmonise the thermal and mechanical properties of Generation IV reactor fuels, specifically mixed oxide and metal fuels. 

The participants of this activity include the official members, invited experts and observers of the Expert Group on Innovative Fuel Elements (EGIFE).