An Experimentally Validated Mesoscale Model of Thermal Conductivity of a UO2 and BeO Composite Nuclear Fuel

An experimentally validated mesoscale model was developed to simulate the effective thermal conductivity of UO2-BeO nuclear fuel with different microstructural features. The effects of the second phase (BeO) fraction and morphology, temperature, and interface thermal resistance were investigated. The model predicts that the continuous second phase configuration has a higher effective thermal conductivity than the dispersed second phase configuration for the same volume fraction and temperature. Companion experiments were conducted to validate the model predictions. It was demonstrated that accounting for the interface (Kapitza) thermal resistance is necessary to improve the model predictions. The largest difference between the model calculations and experimental results was about 5%, which is within the precision of the experimental measurements.