Thermal conductivity calculation of ZrC–ZrO2 pellet from powder metallurgy as the surrogate of UCO kernel fuel

The very high-temperature reactor is one of the conceptual generation IV reactor design, which is an advanced type of high-temperature reactor concept with enhanced safety and increased helium coolant outlet temperature for process heat of the industrial field. This reactor employed UCO (UO2-UCx) fuel kernel providing resistance against fuel kernel migration and internal pressure buildup. Recently, only a few reported literature about the thermal conductivity calculation of UCO fuel. The UO2 has phonon contribution domination, while UC has electrical contribution domination to the thermal conductivity. This combination behavior is important to be studied by measurement and calculation of thermal conductivity. The present work deals with the estimation of thermal conductivity considering the contacting particle inside the pellet. The ZrC–ZrO2 pellet was used as the surrogate of UCO composite. The calculation of thermal conductivity was performed by the Agari model and percolation theory showed a good agreement to the experimental value.