Three-Dimensional Thermal Modeling of In Situ Heating Tests for High-Level Radioactive Nuclear Waste Repository

This study aims to model the temperature evolution near the heater of an in situ heating test for a nuclear waste repository. Based on the governing equation of heat conduction, a mathematical model is established to obtain temporal and spatial temperature distributions in the in situ heating test. Then, semi-analytical solutions are derived using the Laplace and Fourier transforms and their inverse transforms. The corresponding results in the time domain are obtained by conducting the Crump method. The semi-analytical solution is applied to predict temperature change near the heater in two in situ heating tests. Finally, a parametric study is conducted to explore the impacts of some parameters on the temperature evolution of the buffer layer for one prototype repository in situ heating test. The results show that the semi-analytical solution of the proposed model can well predict the temperature change near the heater in the two in situ heating tests. The thermal conductivities of the buffer layer and the rock layer and the thickness of the buffer layer have significant effects on the temperature evolution of the buffer layer in the prototype repository in situ heating test.