Geoscientific Characterization and Interpretation (Geosynthesis) within the Preliminary Safety Assessment in the German Site-Selection Procedure for a High-level Nuclear Waste Repository

After implementation of the Repository Site Selection Act (StandAG) in 2017, the Federal Company for Radioactive Waste Disposal (BGE), as the German waste management organization, started the site selection procedure for a nuclear repository for high-level radioactive waste in Germany. On the way towards the repository site with the best possible safety, the site selection procedure is required to be a participatory, transparent, learning and self-questioning process based on scientific expertise. With the Subareas Interim Report published in 2020, first results were presented outlining subareas with favourable geological conditions in preparation for defining the siting regions for surface exploration. Currently, one of the main tasks in the site selection procedure is to establish a detailed geoscientific synthesis (Geosynthesis) for each subarea. The Geosynthesis contains all geological information for the characterization of each subarea and hence serves as the foundation for the subsequent analysis within the representative preliminary safety assessments (rvSU) and the geoscientific consideration criteria. Based on this information, all areas within the subareas will be evaluated to find the siting regions for surface exploration. The Geosynthesis includes a description of the regional geology focusing on the host rock, the overburden and relevant geological processes that may affect the potential nuclear waste repository in the next 1 million years. The data for the Geosynthesis are mostly compiled from state authorities and include 3-D geologic models, regional maps and cross-sections, bore hole data (e.g. geophysical logs) and seismic data. Furthermore, it is necessary to digitize, process, interpret and evaluate the aforementioned data using the available knowledge from the scientific literature in the context of the site selection procedure.

Representing future generations in public participation procedures regarding the siting of a nuclear waste repository

State decisions regarding a repository for high-level radioactive waste have an extraordinary intergenerational significance. The academic legal discussion has increasingly strengthened the status of future generations in constitutional law. In its recent decision on the German Climate Protection Act, the Federal Constitutional Court equally emphasised that state actors have an obligation to protect future generations. Fundamental rights of future generations thus have an anticipated effect in the present. In general, the legislator is free to choose the appropriate means to protect these rights. The interests of future generations may be promoted by substantive or procedural law. The German Site Selection Act (StandAG), however, makes use of procedural protections to a significant extent. Including the interests of future generations in the existing public participation procedures and participation bodies is, therefore, crucial for the effective protection of future generations. The presentation examines to which extent the current legal framework for the site selection for a high-level radioactive waste repository in Germany enables an effective representation of the future generations' interests. Existing publications (Appel, 2005; Rose, 2018; Kloepfer, 1993) name various characteristics of effective “intergenerational institutions”. Accordingly, these institutions should be independent, exist long-term, serve future interests solely or primarily, and have strong rights vis-à-vis decision-makers; however, German constitutional law, namely the principle of democracy, limits the design of such institutions. Not all of the abovementioned characteristics can be combined. Nevertheless, the constitution enables means to include and promote the interests of future generations in decision-making procedures, which are not fully exploited by the German Site Selection Act. The participation procedure includes several groups which could promote intergenerationally just decisions, namely environmental associations, the public and representatives of the “young generation”; however, none of these stakeholders are “intergenerational institutions” in the abovementioned sense. Subsequently, the presentation proposes various reforms: improving the sustainability impact assessment during the legislative procedure, the implementation of an “intergenerational impact assessment” and an ombudsperson for future concerns, who could be affiliated with the National Citizens' Oversight Committee (Nationales Begleitgremium).

Experimental investigation on buffer/backfill materials for radioactive waste repository downward facing sorption additivity of cesium, strontium and cobalt with different concentrations

Buffer/backfill materials for radioactive waste disposal sites consist of pure bentonite or bentonite-rock mixtures. In this study, the batch test method was used to obtain the sorption characteristics of important radionuclides such as Cs, Sr and Co on buffer/backfill materials; i. e., mixing Wyoming MX-80 bentonite or local Taiwanese Zhi-Shin bentonite with possible host rock (argillite and granite) in different proportions (0∼100%). The distribution coefficients (Kd) for Cs, Sr and Co were obtained from the experiments. The distribution coefficient for the bentonite-rock mixtures were found, with more than 50% of mixing proportion of bentonite to argillite or granite, to have very similar values to that of pure bentonite. Furthermore, it was clearly found that the sorption of Cs, Sr and Co to bentonite-rock mixtures is decreased as ionic strength of the liquid phase is increased from 0.001M to 1M for NaCl solutions. According to the experimental results, in synthetic groundwater, it is quite convenient and helpful to assess the distribution coefficients (Kd) of Cs, Sr and Co for buffer/backfill materials using batch sorption experiments with bentonite-rock mixtures of fixed mixing proportions.