In the coming years, 90 sub-areas are to become a small number of siting regions. These siting regions are to be explored above ground in the search for a final repository site for high-level radioactive waste in Germany. In order to be able to propose siting regions, the BGE is developing methods for identifying those siting regions that are favourable for final disposal. First of all, it is a matter of implementing the requirements and framework conditions for the representative preliminary safety analyses (rvSU) for all 90 sub-areas specified by the legislator. The methods for this are being developed using data from several sub-areas in different host rocks. As in the case of the sub-areas interim report, the experts of the BGE will develop methods for applying their containment and assessment tools with a practical orientation from the very beginning and will, of course, work with real data. These sub-areas, or even individual areas within sub-areas, are referred to as method development areasby the BGE.
Method development areas
A method development area is a sub-area that the BGE experts are looking at in order to be able to answer specific questions on the assessment of the safety of a repository system. It entails practical questions such as: How many boreholes have been drilled in this sub-area? And what can be deduced from the data obtained for the comprehensive geological description of the area with a view to the safe containment of the nuclear waste?
Steffen Kanitz, Managing Director of the BGE for the Site Selection section, emphasises: “One area for method development is not better or worse than other areas. At this stage of the process, they merely allow us to develop methods for further delineating the areas of all 90 sub-areas”. The BGE aims to use the data from the method development areas in order to present a preliminary concept for the application of the rvSU for public discussion in spring 2022. All 90 sub-areas remain in the process and will eventually be assessed with these new methods.
Four very different areas for method development across Germany
The BGE aims to develop its methods using data from the following sub-areas: Sub-area 001_00 (Opalinus Clay) in Baden-Württemberg and Bavaria, parts of the Sub-area 009_00 crystalline (Saxothuringian), which extends from Baden-Württemberg and Bavaria to Saxony, Sub-area 035_00 (Bahlburg salt dome) near Hamburg, and Sub-area 078_02 (shallow salt structure in the Thuringian Basin). The transferability of the method development to other sub-areas (also tertiary clay) is being considered.
These sub-areas vary considerably and cover all the host rocks considered for final disposal: salt, clay and crystalline. For the large-scale sub-areas, the challenge is to identify the particularly favourable areas within the sub-areas. In addition to the evaluation of geological properties based on existing geodata, some of which are currently being additionally queried, preliminary safety and repository concepts must be developed; these play a role in the evaluation of the respective repository systems. In addition to natural processes such as future ice ages, the basic possibility of safe operation must also be presented here. Just because an area plays a role in method development does not mean that it is particularly suitable or unsuitable. As work progresses in the coming months and years, other areas for method development may be added.
A method development area is far from being a siting region
A method development area should not be confused with a siting region, which is determined by the Federal Parliament only at the end of Phase I of the site selection procedure. Drilling or seismic measurements or other exploration methods will be used only once Parliament has approved the proposal of the BGE for siting regions after a review by the Federal Office for the Safety of Nuclear Waste Management (BASE). The BGE will provide information on the status of the work.