Coupled THMC analysis of a clay-based engineered barrier for nuclear waste disposal

A fully coupled thermo-hydro-mechanical and chemical (THMC) is summarily described in the paper. Special attention is paid to phenomena likely to be encountered in clay barriers used as engineered barriers in the disposal of nuclear waste. The types of processes considered in the chemical formulation include hydrolysis, complex formation, oxidation/reduction reactions, acid/base reactions, precipitation/dissolution of minerals and cation exchange. Both kinetically controlled and equilibrium-controlled reactions have been incorporated. The formulation has been implemented in a numerical code. An application is presented concerning the performance of a large scale in situ heating test simulating high-level nuclear waste repository conditions.