Preliminary safety assessments in the high-level radioactive waste site selection procedure in Germany

Abstract

Abstract. The Federal Company for Radioactive Waste Disposal (BGE) is a German waste management organization 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. This contribution provides an overview of the methodology of the forthcoming preliminary safety assessments as a major part of the next steps in the site selection procedure. This procedure overall consists of three phases with increasing levels of detail for identification of the best site. The first phase consists of two steps. The objective of the first step was to determine sub-areas in the three considered host rocks, salt (halite), claystone and crystalline host rock, by applying legally defined exclusion criteria, minimum requirements and geoscientific weighing criteria. A total of 90 sub-areas that cover approximately 54 % of the area of Germany were identified due to their general suitable geological conditions. The results were published in September 2020. The second step of phase one is currently in progress and includes representative preliminary safety assessments that aim to assess the extent to which the safe containment of the radioactive waste can be expected in the investigated sub-area. The requirements for conducting preliminary safety assessments in the site selection procedure are defined by a governmental directive released in October 2020. Representative preliminary safety assessments have to be performed for each sub-area and consist of the compilation of all geoscientific information relevant to the safety of a repository, the development of preliminary safety and repository concepts and the analysis of the disposal system. In addition, a systematic identification and characterization of uncertainties has to be undertaken and the need for exploration, research and development must be determined. The application of the representative preliminary safety assessments as well as the following renewed application of geoscientific weighting criteria will lead to the identification of siting regions within the larger sub-areas identified in step one. These regions will be considered, first for surface-based geoscientific and geophysical exploration, including e.g. seismic exploration and drilling of boreholes. Subsequently, the last phase of the site selection will proceed with subsurface exploration. Finally, all suitable sites will be proposed and the German government and parliament will decide the actual site. This process is expected to be finalized in 2031.