RESUS. Fundamentals for the evaluation of a repository system in shallow salt formations

According to the Site Selection Act (StandAG), the site with the best possible safety for the repository for high-level radioactive waste has to be identified in a site selection procedure. To this end, the project sponsor Bundesgesellschaft für Endlagerung mbH must first identify sub-regions, then identify potential siting regions for surface exploration, identify potential sites for underground exploration and finally, in the final site comparison, assess on the basis of geoscientific assessment criteria whether a favourable overall geological situation exists in an area after a safety-oriented consideration of the results for all geoscientific assessment criteria specified in the StandAG. The prerequisite for such a safety-oriented consideration of different features and different overall geological situations is a sufficient understanding of the significance of the individual geoscientific consideration criteria and their possible characteristics for an assessment of repository safety in the repository systems to be considered in Germany. In order to be able to carry out such a significance assessment of the geoscientific consideration criteria, generic safety studies are carried out in the project 'Basic development for representative preliminary safety studies and for the safety-oriented consideration of subareas with particularly favourable geological conditions for the safe final disposal of high-level radioactive waste' (RESUS). In the present report, the basic principles for the evaluation of a repository system in a clay rock formation of lower thickness are documented. This includes qualitative considerations on the significance of the evaluation-relevant properties of the consideration criteria for long-term safety in such a repository system, in which the confinement of radionuclides must essentially be ensured by the geological barrier. The containment effectiveness of this barrier (integrity) is of central importance for the permanent, post-closure containment of the radionuclides. Therefore, results of quantitative analyses on the integrity of the barrier rock and on the confinement of the radionuclides were taken into account.