The safe disposal of high-level radioactive waste is a central challenge of our time. The TRANSFER graduate school (TRANSFER - Training and Research Academy for Nuclear Safety and Future Expertise on Geological Repository Systems) is dedicated to this task, offering ten PhD students the opportunity to investigate issues related to geological disposal in claystones through mutually complementary projects. It integrates various disciplines and qualifies the next generation of scientists for roles in academia, industry, regulatory authorities, and policymaking within the field of radioactive waste disposal and beyond.

The core focus of this research is evaluating the suitability of claystone formations as host rocks for geological disposal of nuclear waste. Particular attention is given to analyzing spatial and temporal heterogeneities and their impact on radionuclide retention. Initially, Opalinus Clay serves as a reference material to transfer findings from previous studies – especially those from Switzerland – to occurrences of the formation in southern Germany and to contextualize them within a broader geological framework. Subsequently, the acquired insights will be applied to other clay formations in the North German Basin.

A central objective is the development of simulation methods capable of representing heterogeneities within repository systems. Data obtained from laboratory tests and in situ experiments at underground research sites provide the foundation for this work. Based on our process-oriented research, a more precise selection protocol for claystones is being developed, benefiting both the German and international scientific communities. Ultimately, a structured workflow will be presented to serve as a foundation for site investigations and future site selection processes.