Comparative analysis of swelling and porosity evolution in UO2 fuel via two approaches

A correlation for the volume porosity of irradiated UO2 fuel as a sum of the individual contributions of the pore and swelling porosity in terms of the local density and fractional matrix swelling is developed. By using the existing low temperature low burnup model of swelling, evolution of the matrix swelling and porosity terms are calculated for UO2 fuel in the low burnup but in the high burnup two various models are applied, the one with considering grain recrystallization and another without it but with the method of Xe depletion measurement. The purpose of the paper is comparison of fuel swelling behavior between two models at high burnups. The bulk swelling and porosity evolution in both methods are also validated by experimental data. Finally, one conclusion from this comparison is obtained, as the method which considering grain recrystallization has more rational behavior in the fuel swelling and porosity.