A systematic approach to develop recommendations for surface exploration of siting regions for a radioactive waste repository in Germany

The site selection procedure for a high-level radioactive waste repository in Germany is based on the Repository Site Selection Act (StandAG, 2017) and comprises three phases. Commissioned by the Bundesgesellschaft für Endlagerung mbH (BGE), the BGR contributes to this procedure with the projects „GeoMePS“ and „ZuBeMErk“, which aim to develop recommendations for phase 2 of the site selection procedure – the surface exploration of siting regions. For this purpose, the BGR has developed a systematic approach that includes (1) deducing exploration targets, (2) compilation of geoscientific and geophysical exploration methods in a database structure, and (3) evaluation of case studies of national and international exploration programs. The deduction of exploration targets was based on the criteria and requirements as defined by the StandAG. Subsequently, the identified exploration targets together with a large number of geoscientific (e.g., geological mapping) and geophysical exploration methods (e.g., reflection seismics) were integrated and linked within the database – the so-called “GeM-DB”. All methods were evaluated according to their suitability and applicability for (a) the three defined host rocks (crystalline rock, claystone, rock salt) and (b) the previously defined exploration targets. In step (3) the BGR evaluates national and international exploration programs, for example the site selection processes for deep geological repositories in Switzerland or Sweden, to infer additional exploration directives.The entire systematic approach aims to develop recommendations for a non-destructive and minimal invasive surface exploration program of siting regions in Germany, regarding the lithological, structural, mechanical, and hydrogeological characterization of the different host rock formations.