Methods for safety-related weighting and comparative assessment in the site selection process (MABeSt)

Abstract. The Federal Office for the Safety of Nuclear Waste Management (BASE) supervises the site selection process in Germany and in particular has the task to review the proposals made by the implementer (Federal Company for Radioactive Waste Disposal, BGE) for determining the siting regions and sites in accordance with §§ 14, 16 and 18 of the German Repository Site Selection Act (StandAG). To determine the siting regions from the sub-areas and the sites from the siting regions, it is likely that safety-related weighting of the results from the application of the geoscientific weighting criteria (§ 24 StandAG) and the application of the preliminary safety investigations (§ 27 StandAG) are necessary. In order to be able to assess and evaluate the proposals of the BGE with respect to the methodological procedure for determining the siting regions and sites, the research project “Methods for safety-related weighting and comparative assessment in the site selection process” (MABeSt) was initiated by BASE. The objective of the research project was to research and explain the state of the art in science and technology (S&T) with respect to safety-oriented weighting and comparative assessment methods and their potential applicability for the selection of siting regions and sites in the site selection process. The status of S&T for safety-oriented weighting and comparative assessment methods was examined and evaluated with respect to site selection procedures for repositories in Germany and abroad (e.g. Switzerland) and also to methodological approaches from other topics (e.g. landfill site selection). The site selection process represents a multicriteria decision problem, which means that methods from the research field of decision theory appear to be suitable. In particular, methods from the multiattribute decision making/aid (MADM) category were identified as suitable and their potential applicability was examined and evaluated. Specific challenges (e.g. data uncertainties, different scales of evaluation criteria) for the relevant procedural steps of the site selection process were taken into account. We present the results and conclusions of the project MABeSt (funding
code/4718F13001) carried out by GRS gGmbH and initiated and funded by BASE.


Literature search on German and international publications with regard to weighting and comparative assessment methods that were applied to a site selection of a repository and other disciplines.Description and summary of the identified methods.

Decision model
Seite 6 Problem formulation (specification of the goals)
Gerd Frieling,SafeND,10.11.21 Final assessment and Outlook MADM helps to achieve comprehensible and transparent decision-making.It should be understood as a decision "support" tool, not decision make.
The applicability and suitability of the methods mentioned should be tested on a specific decision problem.
A combination of MADM methods and the verbal argumentative method should be investigated.
A certain amount of "Aggregation" of the data is always necessary, also in the verbal argumentative method.A compensation of information cannot completely be avoided.

Aggregation of information -Decision matrix
§19 -Final site comparison and site recommendation (BASE, BMU) §20 -Site decision by the German Federal Parliament and the Federal Council 1 StandAG -Law on the search and selection of a site for a repository for high-level radioactive waste /STA 17/ 2 BGE -Federal Company for Radioactive Waste Disposal 3 BASE -Federal Office for the Safety of Nuclear Waste Management 4 BMU -Federal Ministry for the Environment, Nature Conservation and Nuclear Safety

21 The MABeST project BASE research agenda 2020 1 :
"The StandAG does not specify how these comparisons and evaluations are to be carried out methodically, how uncertainties due to different data availability, quality and comparability are to be dealt with, how different data may be weighted and how host rock-specific and host rock-independent data are to be considered.""For the aforementioned evaluations and comparisons, existing methods must be checked and, if necessary, further developed.
GerdFrieling, SafeND, 10.11."Research project MABeST:Duration 02.2019  -31.10.2019(byGRS)(by GRS), Funded by BASE (FKZ 4718F1300) AP 1:Identification of work steps in the StandAG in which safety-related weighting and comparative assessment must be carried out and which related challenges arise in the work steps.AP 2:

Evaluation of the applicability of the methods for the identified work steps in the StandAG.
1 https://www.base.bund.de/SharedDocs/Downloads/BASE/DE/broschueren/bfe/forschungsagenda_final.Gerd Frieling, SafeND, 10.11.21Literature research to identify suitable methodsSeite 5 1. /BOL 11/ (EUGENIA) emphasizes that: "... the transfer of the concepts and procedures for a repository site selection developed in other countries to Germany is only possible to a limited extent."2.Methods from the decision theory, especially Multi-Criteria Decision Making/Aid (MCDM) tools are applicable for (all) types of decision-making problems, also for a repository site selection.MCDM deals with structuring and solving decision and planning problems based on several criteria.GerdFrieling, SafeND, 10.11.21