Three-dimensional thermal analysis of the repository for high-level radioactive nuclear waste

One of the key issues of the dimensioning design and safety assessment of the repository for deposing the high-level radioactive nuclear waste is the temperature distribution. A three-dimensional layered model was established for analyzing the heat conduction near single waste canister. Applying the Laplace transform and finite Fourier Sine transform upon the governing equations of heat conduction, the solutions in the Laplace domain were obtained. The solutions in the Laplace domain were numerically inverted into semi-analytical solutions in the time domain by the Crump method, and the temperature distribution was obtained near the canister at the center of one disposal panel. The initially estimated value of the canister spacing was determined according to the temperature distribution and design criterion. Finally, the obtained temperature distribution was used to investigate the influence of relevant parameters on the canister surface temperature. The results show that the present model is reliable by comparing with the existing analytical model. The peak canister surface temperature is significantly affected by the tunnel spacing, canister spacing, thickness of buffer layer, and thermal conductivities of buffer material and surrounding rock.