Host: The Japan Society of Mechanical Engineers
Name : The 30th International Conference on Nuclear Engineering (ICONE30)
Date : May 21, 2023 - May 26, 2023
Due to its outstanding performance, uranium zirconium (U-Zr) metallic fuel has been considered as a candidate fuel in fast reactor. However, the serious swelling and decrease in thermal conductivity caused by fission gas bubble is a severe challenge for its application. In the present work, a phase-field model considering the resolution of gas atom was proposed to investigate the distribution of bubble size and the decrease of effective thermal conductivity due to irradiation-induced bubble in U-Zr metallic fuel. The evolution of microstructures of U-Zr fuel with intragranular gas bubbles was obtained by solving a set of modified Cahn-Hilliard and Allen-Cahn equations in this model. The bubble evolution in U-Zr during irradiation was simulated. The distribution of bubble size is bimodal and agree well with the experimental data when the spatial distributed resolution rate is used. The resolution of gas atom is deduced to be the primary reason for bimodal bubble distribution in nuclear fuel. Furthermore, the variation in effective thermal conductivity of U-Zr under different bubble distributions was calculated quantitatively based on the microstructures provided by the phase-field model. Results showed that the effect of bubble distribution on the effective thermal conductivity was not significant at the same porosity. Overall, this research is helpful in understanding the decrease in thermal conductivity caused by fission gas bubble in U-Zr metallic fuel.
