// Repository Design, Long-term Safety Studies

KOSINA

Concept developments for a generic repository for heat-generating waste in bedded salt formations in Germany

For many decades, the development of repository concepts and safety analyses for a repository in a salt dome was prioritized in Germany while repository concepts for claystone and crystalline rock have been taken into account for the past two decades only. So far, bedded salt formations have not been the subject of comparative investigations. Thus, in summer 2015, the Federal Ministry for Economic Affairs and Energy (BMWi) launched the R&D project KOSINA to develop repository designs and carry out safety analyses for different disposal options in a generic bedded salt formation and a generic salt pillow. KOSINA is a German acronym for "Concept development for a generic repository for heat-generating waste in bedded salt formations in Germany as well as development and testing of a safety and demonstration concept". Together with its partners BGR, GRS, and IfG, BGE TECHNOLOGY GmbH has carried out an almost three years lasting scientific programme. The core areas of the programme are the development of generic geological models, including derivation of model parameters, the development of a safety and demonstration concept, the development of technical repository designs for four different disposal options, the analysis of geomechanical integrity, the evaluation of operational safety as well as the analysis of radiological consequences. An interim report, which compiles the basic data of the waste inventory, the repository design requirements, the data basis for geological model developments, and the outline of a safety and demonstration concept, was already published in February 2016. The main achievements of R&D project KOSINA are the development of four different disposal options, two per each generic geological model (flat-bedded salt, salt pillow) based on thermo-mechanical calculations. This includes the implementation of a safety concept that provides containment of the radioactive materials with regard to the technical designs of waste packages, transport and emplacement technologies, as well as backfilling and sealing concepts. Furthermore, the integrity of the geological barriers could be demonstrated for all four disposal options, and the long-term predictions showed no radiological releases during the demonstration period of one million years.