With the goal of assessing safety-relevant consequences on the barrier system of a high-level radioactive waste repository, the interactions that may occur in a co-disposal site for high-level waste as well as low- and intermediate-level waste have been investigated in the GemEnd research project. Without referring to a specific site, various generic scenarios for different possible host rocks according to the German Site Selection Act have been considered. These scenarios include generic configurations with the repositories located at the same depth in each of the candidate host rocks (clay rock, rock salt, and crystalline rock). After specifying the generic geological conditions and the expected inventory to be disposed of, in terms of both volume and content, we numerically evaluated selected potentially relevant processes for each scenario.

The results of this study are of a general nature, and the methodology provided can act as a template for similar studies performed for specific locations. The results can be applied to actual site candidates, provided that the analyzed repository configurations are sufficiently similar to those assumed in this study.