THM-modelling benchmark initiative on the effects of temperature on the disposal of heat-generating radioactive waste in clay formations

Abstract Understanding the thermo-hydro-mechanical (THM) behaviour of clay formations, which are being considered as potential hosts for the disposal of radioactive waste in Europe, is important for the feasibility and the safe disposal of heat-generating radioactive waste in deep geological clayey formations. To ensure the reliability of numerical models and tools used to predict the THM evolution of such systems over long periods of time, it is necessary to verify and validate these tools through benchmarking initiatives. As part of the joint European Programme on Radioactive Waste Management (EURAD), the Influence of Temperature on Clay-based Material Behaviour (HITEC) work package invited seven teams from across Europe to participate in a benchmark initiative to assess the expertise and capabilities of these teams and their numerical tools to predict THM evolution in different clay materials. The results of this benchmark showed that all teams involved were able to adequately model the THM behaviour of heat-generating repository systems in clay formations, and the tools they used can be considered verified for the solution of coupled THM equations under variable boundary conditions relevant for nuclear waste disposal.