In the ultimate storage of high level wastes in rock salt thermomechanical phenomena caused by the temperature rises play an important role for elaborating the storage concept. Important factors are both large space effects concerning the repository and the geological formation and small space phenomena influencing to a considerable extent the interaction between waste blocks and the host rock. While the large space aspects are largely inaccessible to an experimental investigation, the small space effects, especially the convergence behavior of individual heated boreholes, are eligible for a systematic experimental and computational study allowing verification of available computational methods and thermomechanical material laws for rock salt.