Development of a database for the analysis of the disposal system in the representative preliminary safety analysis

Abstract. The Federal Company for Radioactive Waste Disposal (BGE) is the German waste management organisation responsible for implementing the search for a site with the best possible safety for the disposal of high-level radioactive waste for at least 1 million years, following the amendments of the Repository Site Selection Act in 2017. The selection procedure is meant to be a participatory, transparent, learning and self-questioning process based on scientific expertise. It consists of three phases with an increasing level of detail. The first step of the first phase of the site selection procedure was completed in September 2020 and resulted in the identification of 90 subareas that give reason to expect favourable geological conditions for the safe disposal. The potentially suitable subareas cover approximately 54 % of Germany and are located in three different host rocks: rock salt (halite), claystone and crystalline rock. The second step of phase one is currently in progress and includes the so-called representative preliminary safety analyses that aim to assess the extent to which the safe containment of the radioactive waste can be expected. Representative preliminary safety analyses are one of the foundations for deciding whether an area will be considered for surface-based exploration in the next phase of the site selection procedure. Within the preliminary safety analyses, the behaviour of the disposal system is analysed in its entirety, across all operational phases of the repository and under consideration of possible future evolution of the disposal system with respect to the safe containment of the radioactive waste. The development of a database is described, which aims to systematically document and provide the framework needed for the analyses of the disposal systems in the subareas regarding the safe containment of the radionuclides over the assessment period of 1 million years. This database includes the vast amount of information about the different components of the disposal system. This includes also the geological setting, the technical conception of the repository and compilations of values for the physical, geoscientific, and technical parameters characterising the various barriers of the disposal system. Furthermore, a self-contained derivation of expected and deviating future evolution of the disposal system and its geological setting is included; following the so-called features, events and processes (FEP) strategy.