Safety assessment methodology for a German high-level waste repository in clay formations

Abstract In the ANSICHT project that was jointly carried out by DBE TECHNOLOGY GmbH, BGR, and GRS gGmbH, two generic geological site models were used to develop a first draft of a methodology to demonstrate the safety of a high-level waste (HLW) repository in argillaceous formations in Germany, taking into account the regulatory requirements. The main results of the project are characterised by the developed repository concepts adapted to the geological conditions. The specific quantifications of the integrity criteria and their exemplary application with calculational proofs were used to demonstrate the integrity of the host rocks. The development of site-specific FEP (features, events, and processes) cataloges provided a complete system description for evaluation of the repository evolution. The developed work flow of the demonstration concept illustrated the complete sequence of the safety proof in a transparent way. It shows that various steps have to be performed, possibly iteratively, to provide a successful safety proof. The results form a useful tool in the pending search for a HLW repository site, especially when providing a basis for comparing safety analyses of different sites in Germany.