According to the Repository Site Selection Act (StandAG), a repository site has to be found that provides the optimal level of safety for at least one million years. This approach requires a comparison of different alternative repository systems in different host rocks. From the very beginning in the early 1960s, rock salt has been considered to be the best option because of the favorable salt features and because of more than 100 years of experience in salt mining. Thus, repository designs and safety and verification concepts were developed for salt domes. For more than 15 years, generic conceptual designs and safety investigations have been prepared for repositories in clay and crystalline rock in the course of R&D work funded by BMWi (Federal Ministry for Economic Affairs and Energy). Very recently, BMWi decided to start safety investigations on repository systems in bedded salt as well, in order to complete the set of repository designs in potential host rock formations in Germany. In this context, BMWi entrusted DBE TECHNOLOGY in July 2015 to lead an R&D project called KOSINA.
The objective of the R&D project KOSINA is to develop a technical concept for a repository for heat-generating waste and spent fuel on the basis of generic geologic models for bedded salt that is independent of the site. This should include a safety and safety verification concept as well. The expected project results should provide a technical-scientific basis for the safety-oriented evaluation of repository systems in different host rocks in accordance with the Site Selection Act.
To achieve these objectives, BGR (Federal Institute for Geosciences and Natural Resources), GRS (Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH, IfG (Institute for Rock Mechanics), and DBE TECHNOLOGY GmbH combined their scientific and engineering competences, and a suitable working programme was set up. The work programme consists of elaborating and compiling the basic data (types and amounts of waste, design requirements), description of a generic but suitable geologic situation, review of existing safety and safety demonstration concepts. The next steps are the development of generic geologic models, including derivation of model parameters, development of a safety and safety demonstration concept and analysis of the geomechanical integrity. DBE TECHNOLOGY is entrusted with the development of technical repository concepts, which includes the consideration of four different variants (drift disposal of POLLUX® casks, vertical and horizontal borehole disposal, and direct disposal of CASTOR® casks). The evaluation of the long-term radiological consequences as well as investigations on operational safety will complete the work programme. Eventually, a synthesis report will be prepared and published. The KOSINA project was launched in July 2015 and will be finished by the end of February 2018.