Under German law, the crack damage stress must not be reached at any time during the operation or post-closure phase of a nuclear waste repository. This legal requirement can only be fulfilled if the parameter can be measured precisely. We have thus developed a new measurement technique, which overcomes the limitations of the conventional method. In combination, old and new method offer an easy procedure to detect the crack damage stress in fully saturated rocks in a fast and robust manner.

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.

The Federal Institute for Geosciences and Natural Resources (BGR) performs experiments in the Swiss Mont Terri rock laboratory to obtain a comprehensive understanding of the evolution of a repository. Activities and results by BGR from actual and still ongoing experiments are presented exemplarily focusing on main aspects regarding the behaviour of underground facilities. BGR's focus lies mainly on aspects of the construction, post-closure transient, and partly post-closure equilibrium phases.