In the German safety analysis for a high-level waste repository, the behaviour of the repository system in its entirety is investigated over the assessment period of 1 million years regarding the safe containment of radioactive waste. In this period, which starts after the planned closure of the repository, ten glacial-interglacial cycles are possible. In particular, the effects associated with this cyclicity, such as glaciations and the formation of permafrost followed by thawing, can have an impact on the geological barrier of the repository, and thus, a possible negative influence on the long-term safety of the repository.

The project presented here, which is embedded in the CatchNet group (see https://skb.de/Catchnet/), aims to address these research questions. The focus lies on the investigation on effects associated with volume changes due to thawing/freezing processes in permafrost regions, which particularly may affect the overburden of the rock containment zone. The project comprises the experimental and numerical analysis of thermo-mechanical coupled processes resulting from the expansion of freezing and thawing, respectively. In a second step, the relevance of this thermos-mechanical process with respect to the regional groundwater flow regime is evaluated by an integrated hydrogeological model.