ABSTRACT
The thermal conductivity of irradiated UO2 fuel is discussed considering the effects of burnup (dissolved and precipitated solid fission products), porosity and fission-gas bubbles, deviation from stoichiometry and radiation damage. Model parameters are selected based on previously published results from SIMFUEL (simulated high burnup UO2 fuel). A model developed to describe the thermal conductivity of irradiated UO2 accounts for the above effects; it reflects the knowledge available today, and is recommended for use in fuel performance codes. The model is validated against available published data on thermal conductivity of irradiated fuel. This model can be incorporated into fuel performance codes to improve calculations of operating temperatures and predictions of behaviour of irradiated fuel under normal and accident conditions, including the extended burnup.
