Assessment and Communication of Uncertainties in the Site Selection Procedure (BewUSt)

Assessment and Communication of Uncertainties in the Site Selection Procedure (BewUSt)

Gerd Frieling¹, Thomas Beuth¹, Esther Kähler¹

¹Federal Office for the Safety of Nuclear Waste Management (BASE), Wegelystr. 8, 10623 Berlin, Germany

Correspondence to: G. Frieling (gerd.frieling@base.bund.de)

Abstract. The German site selection procedure (StandAV) examines whether a safe containment of high-level radioactive waste can be expected in the respective repository concept for one million years [1]. This requirement is assessed in particular with the help of preliminary safety investigations (vSU) [2]. In the first two phases of the StandAV in particular, the vSU is associated with uncertainties due to the process-related increasing data availability. Due to the complexity of the phenomena and processes considered and the temporal and spatial scale, uncertainties are unavoidable. Both the ordinance of safety requirements for the final disposal of high-level radioactive waste (EndlSiAnfV) [3] and the ordinance of preliminary safety investigations in the site selection procedure (EndlSiUntV) [2] require the investigation of the uncertainties but do not specify how the uncertainties should be dealt with methodically. An evaluation based on methodological approaches helps to make the process transparent and comprehensible.

The BewUSt research project with a focus on uncertainties is carried out at BASE since November 2023. The main objectives of the project are, on the one hand, to create an overview of possible uncertainties for all host rocks to be considered in Germany and, on the other hand, to determine which qualitative and quantitative methodological approaches have been used to deal with uncertainties in recent relevant projects. In addition, the BewUSt research project will prepare the results in a way that they are appropriate to communicating uncertainties for specific target groups.

As part of the project tasks, the uncertainties are therefore characterized and existing methodological approaches are identified. In addition, it is examined whether approaches from other areas can be used. Furthermore, the current status of common methodological approaches (e.g. sensitivity analysis) as well as unconventional probabilistic methods from the field of final disposal and other geoscientific fields (e.g. hydrogeology or reservoir modelling) are determined and their application to the uncertainties relevant to vSU are examined. The poster shows exemplary work results e.g. for potential uncertainties and their methodical treatment. The results will help BASE to independently examine and evaluate the proposals of the implementer.

 

[1] Deutscher Bundestag (BT) (2020): Law on the Search and Selection of a Site for a Final Repository for High-Level Radioactive Waste, Site Selection Act - StandAG. (07.12.2020) (BGBl. I, 26).

[2] EndlSiUntV (2020): Ordinance on requirements for the implementation of preliminary safety investigations in the site selection procedure for the final disposal of high-level radioactive waste (Endlagersicherheitsuntersuchungsverordnung - EndlSiUntV) (6. 10. 2020) (BGBl. I S. 2094, 2103) last modified 2020 (Bundesgesetzblatt (BGBl))

[3] EndlSiAnfV (2020): Ordinance on Safety Requirements for the Final Disposal of Highly Radioactive Waste (Endlagersicherheitsanforderungsverordnung - EndlSiAnfV) (6. 10. 2020) (BGBl. I S. 2094), last modified 2020 (Bundesgesetzblatt (BGBl))