For long-lived intermediate-level radioactive waste, the useof concrete as engineering barrier and Callovian-Oxfordian clay asgeological barrier at a depth of 500 m is considered in the Frenchdisposal concept (ANDRA, 2005). Upon emplacement, initially unsaturatedconcrete is expected to experience coupled processes involving heating,re-saturation with groundwater from the clay formation, gas exchanges andgeochemical reactions. After an early period of re-saturation, solutetransport is supposed to be diffusion-controlled because of the extremelylow permeability of the two media. These coupled processes may lead tochanges in the porosity of the concrete or clay barriers. In the presentpaper, a fully coupled Thermo-Hydro-Chemical (THC) response of atwo-phase (gas and solution) mass-transfer model was evaluated and testedby a sensitivity analysis. This study is an extension of a previous modelapplied to an isothermal and fully saturated concrete/clay interface(Burnol et al., 2005); it investigated the coupled effect of temperatureand unsaturated conditions assuming no production of H2(g). The systemwas simulated for a 2000-year period, which covers the most predominantthermal perturbation
