Thermo-Hydro-Mechanical-Chemical Modelling of the Bentonite Barriers in Final Disposal of High Level Nuclear Waste

M. Olin, M. Tanhua-Tyrkkö, V. Pulkkanen, A. Itälä, K. Rasilainen, A. Seppälä, and M. Liukkonen
VTT Technical Research Centre of Finland, Nuclear Energy, Finland

The bentonite barrier is an essential part of safe nuclear waste repository in granite bedrock. In this work COMSOL Multiphysics® is applied to modeling Thermo-Hydro-Mechanical-Chemical (THMC) processes taking place in a bentonite buffer.

The system is studied in different geometries, which consists of an overall 3D layout and a 2D cross-section of bentonite buffer and open fracture. Altogether, three main periods have been identified in the modeling: 1) emplacement of canister, 2) saturation, and 3) long term safety.

The main interest has been on diffusion transport of different species into and out of the bentonite buffer.