A model for rim porosity that takes into account the effect of overpressurization on rim pores is proposed for high-burnup UO2 fuel. It is based on the assumption that all the fission gases produced are retained in rim pores, and the threshold pellet average burnup required for the formation of the rim region is 40 MWd/kg U. In addition, a thermal conductivity correlation is proposed that uses the rim porosity model developed. This correlation for the rim region considers both degradation of thermal conductivity with burnup across the fuel pellet and additional degradation at the pellet rim due to very high porosity. To calculate the temperature profile across the fuel pellet where the rim region is formed, the present correlation for the rim region is combined with the HALDEN, MATPRO, and SIMFUEL correlations for thermal conductivity for the fuel interior region where the rim feature does not exist. Application of the present correlation to the measured HALDEN fuel centerline temperature (Nuclear Energy Agency public database IFA-562) shows that good agreement between the calculated and measured fuel centerline temperature is obtained when the present correlation is combined with HALDEN thermal conductivity. On the other hand, when it is combined with SIMFUEL thermal conductivity, which does not consider the effect on thermal conductivity of fission gases and other volatile fission products, lower centerline temperature is obtained due to the characteristics of the SIMFUEL.