Analysis on the Effects of Thermal Migration Phenomena to the Fuel Performance in the Fast Reactor

Thermal migration phenomena in the fast reactor can affect the temperature distribution and in-pile behaviors heavily through changing the local properties of nuclear fuels. In this research, the classical thermal diffusion equations for the oxygen diffusion, plutonium migration, Joint Oxide Gain (JOG) formation, and porosity migration are solved and integrated into the fuel rod performance analysis code KMC-Fueltra as thermal migration analysis module. Validations of these models have been performed by comparing with the experimental data or simulation results. Comparisons have proved the correctness of the thermal migration module in KMC-Fueltra. Effects of these phenomena to the fuel rod performance are analyzed and discussed under the steady-state operating conditions in the 1000MWth Medium-size Modular Lead-cooled Fast Reactor (M2LFR-1000) using multi-physics simulation of coupled thermal analysis, thermal migration analysis, fission gas release analysis and mechanical analysis. Simulation results show that the influence of thermal migration mainly reflects in the fuel pellet other than the cladding. It can result in large changes in some parameters during the evaluation of the fuel rod performance, compared with simulations that do not account for thermal migration phenomena.