Geoscientific Characterisation and Interpretation (Geosynthesis) within the Preliminary Safety Assessment in the German Site-Selection Procedure for a High-Level Nuclear Waste Repository

After implementation of the Repository Site Selection Act (StandAG) in 2017, the Federal Company for Radioactive Waste Disposal mbH (BGE mbH), as the German waste-management organization, started the site-selection procedure for a nuclear repository for high-level radioactive waste in Germany. On the way towards the repository site with the best possible safety, the site-selection procedure is required to be a participatory, transparent, learning and self-questioning process based on scientific expertise. With the Sub-areas Interim Report published in 2020, first results were presented, outlining sub-areas with favorable geological conditions in preparation for defining the site regions for surface exploration. The identified 90 sub-areas with favorable geological conditions cover approximately 54% of the area of Germany. Currently, one of the main tasks in the site selection procedure is to conduct the representative preliminary safety assessments for each sub-area. Apart from the technical descriptions of the repository system, the geoscientific characterization and interpretation (Geosynthesis) of the host rock, the overburden and the geological processes serve as a basis for the safety assessment. The main character of the Geosynthesis is therefore to compile all geoscientific information, relevant to the safety of a repository. Additionally, we describe how the Geosynthesis could be used to identify potentially suitable areas within large sub-areas. These areas with the most favourable geological conditions will then be evaluated in more detail during the representative preliminary safety assessments.