Towards best possible safety – current regulatory research for the German site selection process for high-level radioactive waste disposal

摘要

Abstract. The Federal Office for the Safety of Nuclear WasteManagement (BASE – Bundesamt für die Sicherheit der nuklearenEntsorgung) is the German federal regulatory authority for radioactive wastedisposal. It supervises the German site selection process and is responsiblefor the accompanying public participation. Task related research is anintegral part of BASE's activities. The projects MessEr andübErStand compiled the state-of-the-art science and technology regarding surfacebased exploration methods suitable for addressing the criteria andrequirements specified in the German Site Selection Act. The results supportBASE to review and define the surface-based exploration programs to beexecuted by the national implementer BGE (Bundesgesellschaft fürEndlagerung mbH). To support BASE in reviewing the application of theexclusion criteria “active fault zones” according to the Site Selection Act,the project KaSt?r reviewed the current knowledge on active faults and fault zonesin Germany and recommends methodological approaches to date and identify theactivity of faulting. For the time being, the Site Selection Act defines100 ~(°) C as a draft limit on the temperature at the outer surfaceof a repository container for all host rocks. The project Grenztemperatur studied thetemperature dependency of the differentthermal-hydraulic-mechanical-chemical/biological (THMC/B) processesaccording to available features-events-processes (FEP) catalogues for rocksalt, clay stone, and crystalline rock and describes ways to defining hostrock specific maximum temperatures based on specific disposal and safetyconcepts. Safety oriented weighting of different criteria and comparison ofdifferent potential regions and sites are key challenges during the sitingprocess. The project MABeSt studied and reviewed methodological approaches to thisweighting and comparison problem with special emphasis on multi criteriaanalysis (MCA) and multi criteria decision analysis (MCDA). A keyrequirement for safe geological disposal of nuclear waste is barrierintegrity. The project PeTroS performed the first triaxial flow-throughexperiments on natural rock salt samples at disposal relevant p ?T conditionsand studied potential percolation mechanisms of fluids within rock salt. Thedata substantiate that the minimum stress criterion and/or the dilatancycriterion are the prime “percolation thresholds” in rock salt. The researchresults support BASE in fulfilling its tasks as national regulator accordingto state-of-the-art science and technology and are also relevant to otherstakeholders of the siting process.