Sequential Thermo-Hydraulic Modeling of Variably Saturated Flow in High-Level Radioactive Waste Repository

Abstract : The most long-lived radioactive wastes must be managed in a safe way for human health and for the environment. That is the raison why the French agency for the management of radioactive waste (ANDRA) is engaged to study the feasibility of a deep geological repository in the low permeable Callovo-Oxfordian clay . The long-term safety performance of such a repository is indirectly related to the evolution of heat and water saturation in the repository and in the host rock. For instance, the corrosion of metals and gas generation, which can affect repository safety are dependent on water saturation (or vapor) and temperature within the repository system. In the perspective of taking into account the gas generation in the system, we developed a sequential model to predict the coupled thermo-hydraulic processes at a cell-scale radioactive waste repository for different operating phases.The results show a significant impact of the radiation heat transfer on the temperature profiles. The proposed model that captures quite well the transition between different operating stages can be then used to predict the gas generation in the waste repository.