Computer simulations are used to understand processes in nuclear waste disposal. The results are used to judge the safety of waste repository. Not all the information needed for such analyses, e.g. rock properties, is precisely known, contributing to uncertainty in the analysis results. We are interested in understanding the effect of the uncertainty of input quantities and of certain simplifications made during model creation on the outcome of computer simulations.

As part of BARIK, a laboratory programme is used to generate a dataset for anisotropic material to verify and validate the developed constitutive model. Based on Freiberger gneis, basic tests and multi-stage triaxial compression tests were conducted, the latter to investigate a post-failure region. Hydromechanical coupled triaxial compression tests to observe micromechanical damage processes are in progress. This contribution provides an overview of the laboratory programme and first results.

Crystalline rocks are being considered as potential host rocks in the ongoing search for a suitable site for a nuclear waste repository in Germany, where there is no existing experience in terms of excavating a repository in crystalline rocks. The planned underground laboratory GeoLaB addressing crystalline geothermal reservoirs offers unique opportunities for synergies with nuclear waste disposal research and development, especially in the exploration and building phases.

The SW-A experiment is a large-scale in situ test at the Mont Terri rock laboratory that implements a vertical hydraulic shaft-sealing system in argillaceous host rock. The response of the system and the surrounding rock to hydration is examined. The experiment objectives are to demonstrate the feasibility of installation, to investigate the saturation process, to qualify measurement and monitoring techniques, and to assess the sealing effectiveness. Recent data and experience are presented.

Understanding complex systems such as radioactive waste repositories involves the study of cross-scale coupled processes. We discuss some important concepts and their mutual interactions for interpreting such systems based on complementary model-based analyses at various scales. One goal statement is to explain the formation of drying cracks. Near-field understanding can be used to determine how detailed repository far-field models must be and can lead to more robust analysis results.