Including high burnup structure effect in the UO2 fuel thermal conductivity model

Abstract This paper aims to modify the Lucuta et al. thermal conductivity model of irradiated UO2 fuel to include the high burnup structure effect. The porosity factor of Lucuta et al. model is modified to account for the porosity evolution with increasing burnup. The radiation damage factor of Lucuta et al. model is modified to take account of the removal of defects from the fuel matrix of the rim region. The dissolved fission products factor of Lucuta et al. model is modified to account for the depletion of fission gas atoms from the fuel matrix in the rim region. The effect of grain boundaries thermal resistance on the thermal conductivity is also accounted for as a new multiplier to the Lucuta et al. correlation. The reasonable agreement is seen from the comparison of predicted thermal conductivity with the measured data at high burnup. The conducted parametric study shows the impact of the key parameters on the calculated thermal conductivity.