Abstract: The evolution of the temperature field in the nuclear waste repository is an essential basis for the design and safety assessment of the repository. The layered heat transfer model of a single nuclear waste container was established, according to the conceptual design of the disposal repository. The Laplace transform was applied upon the equations of heat conduction in the bentonite and surrounding regions, and the semi-analytical solutions of the temperature field were derived in the Laplace domain under different combinations of internal and external boundary conditions. The temperature distribution in the near-field time-space domain of the waste container was obtained by numerical inversion of the semi-analytical solution using the Crump’s method. Finally, the evolution of the surface temperature of single waste container under different parameter conditions was analyzed. The results show that the higher the burn-up value of nuclear waste is and the shorter the cooling time of nuclear waste is, the higher the surface temperature of the waste container is. The surface temperature of the waste container calculated by the finite external boundary condition was higher than that calculated by the infinite external boundary condition, the higher the thermal conductivity of bentonite is, the lower the surface temperature of the waste container is. The thicker the bentonite soil layer is, the worse the internal temperature diffusion is. The results provide references for evaluating the evolution of the near-field temperature of waste container under different conditions.

Key words: nuclear waste, waste container, layered heat conduction, temperature field