Implications of Coupled Thermo-Hydro-Mechanical Processes on the Safety of a Hypothetical Nuclear Fuel Waste Repository

Abstract

In Bench Mark Test no. 1 (BMT1) of the DECOVALEX III international project, we looked at the implications of coupled thermo-hydro-mechanical (THM) processes on the safety of a hypothetical nuclear waste repository. The research teams first calibrated their models with the results of an in-situ heater experiments to obtain confidence in the capability of the models to simulate the main physical processes. Then the models were used to perform scoping calculations for the near-field of the hypothetical repository, with varying degrees of THM coupling complexity. The general conclusion from the BMT1 exercise is that it would be prudent to perform full THM coupling analyses for two main reasons. First, several safety features might be overlooked with lesser degrees of coupling. Second, the ability to predict and interpret several physical processes, during the post-closure monitoring period, is important for confidence building and public acceptance. Such ability is attainable only with fully coupled THM models.