Thermo-Hydro-Mechanical Numerical Modelling: Application to a Geological Nuclear Waste Disposal

The production of nuclear energy is facing at the present time to the issue of the management of radioactive waste. A great deal of attention is focused on the feasibility of deep geological underground disposal. Consequently, deep knowledge of thermal, hydraulic and mechanical processes is necessary. Indeed, excavation of the underground works involves development of cracks and fractures in the rock. That will modify the hydraulic properties of the soil creating preferred zones for water flows. It appears essential to evaluate accurately the area of the excavation damaged zones (EDZ) and their evolution in order to forecast the migration pathway for radio nucleides in porous media. In this goal and to describe the coupling and the transfer phenomena in these geological repositories, thermo-hydro-mechanical models are developed. In a first part we will present the disposal concept proposed at the moment and we will describe phenomena to take into account in the simulations : desaturation and resaturation of the geological medium, thermal evolution owing by the packages, gas pressure induced by steel containers corrosion. Then we will talk about numerical difficulties linked to thermo-hydraulic unsaturated problem and brittle mechanical laws.