ABSTRACT
A fully coupled formulation combining reactive transport and an existing thermo-hydro-mechanical (THM) code is presented. Special attention has been given to phenomena likely to be encountered in clay barriers used as part of containment systems. The types of processes considered include complex formation, oxidation/reduction reactions, acid/base reactions, precipitation/dissolution of minerals, cation exchange, sorption, and radioactive decay. Both kinetically-controlled and equilibrium-controlled reactions have been incorporated. The total analytical concentrations are adopted as basic transport variables and chemical equilibrium is achieved by minimizing Gibbs Free Energy. The formulation presented results in an efficient numerical implementation able to tackle quite complex problems. An example of application involving a clay barrier subjected to simultaneous heating and hydration is also presented.
