On the nuclear oxide fuel densification, swelling and thermal re-sintering

A method of calculating the fuel densification and swelling as a result of only the initial fuel porosity has been developed. Well-characterized UO2 fuel pellets, from the Romanian CANDU type fuel fabrication route, were used to fit the specific pore volume distribution resulted from the sintering process to a lognormal distribution function and thermal re-sintering tests up to 280 h at 1700 °C were done to fit the coefficients of vacancies diffusion and the self-diffusion of uranium, required by the model. Careful analyses proved that the irradiation-induced resolution is strongly dependent of the hydrostatic pressure and a corrected formula has been proposed. Analyses of the time evolution of the pore size distribution during re-sintering tests and annealing tests similar with some as described in the open literature were also done.