Three Dimensional Analyses of Combined Gas, Heat and Nuclide Transport in a Repository Considering Thermo-Hydro-Geo- Mechanical Processes

To study the coupled thermo-hydrologic-geomechanical processes and their influence on gas and nuclide transport in a two phase flow through the porous medium, a coupling of the thermo-hydrodynamic code TOUGH2 and the thermo-mechanic code FLAC3D is described and applied to analyze three dimensional gas, heat and nuclide transport in a repository for disposal of heat generating nuclear waste in a host rock such as rock salt. If the hydrological properties, like, porosity, permeability and capillary pressure depend on stress or strain, the influence of coupled processes on the two phase flow can be relevant. The present procedure can be applied to quantify safety margin related to hydro-fracturing and dilatancy due to fluid pressure build-up and to define bounding analyses, if the hydrological properties, porosity, permeability, and capillary pressure, depending on mean effective normal stress, minimum compressive stress or volumetric strain are considered.