Due to the long half-lives of the radionuclides contained in waste, a repository for high-level radioactive waste must safely contain them for long timescales, which include geological and climatic changes. For this reason, numerical groundwater models are developed in this work considering various climate processes and influences in relation to repository safety. Glaciers, permafrost, erosion, and sea level fluctuations will be considered and related to the geological situation in Germany.

In the research project presented here, the use of multiple-criterion decision analysis (MCDA) in the German site-selection procedure is discussed. The aim is to explore the applicability for the decision problem to the emplacement concept of high-level radioactive waste (HLW) packages regarding German safety investigations. The expected outcome is a basic decision model that can provide decision support and increase transparency, understanding, and acceptance in the site-selection procedure.

Based on the German site selection process for a deep geological repository for high-level radioactive waste, we propose a site-prioritization method based on a multi-criteria decision-making approach and risk estimates for each sub-region. The method takes into account the geological factors as well as the uncertainty associated with the heterogeneous nature of subsurface data quality and quantity, in order to enable stakeholders to make informed decisions during the site selection process.

Since the requirement of the proof of safety to up to 100 years arises, integrity of the spent fuel elements in prolonged interim storage and long-term repository is getting more critical issue. In response to this safety matter, we developed and applied a multiscale simulation methodology to assess the impact of the radiation induced microstructures on mechanical properties of the spent fuel elements to provide reliable structural performance limits and safety margin respectively.