Thermomechanical Analysis of the Long-Term Barrier Integrity in Bedded Salt Formation

This study focuses on numerical 3D modeling to analyze the long-term barrier integrity of bedded salt under consideration of thermal loading caused by heat-generating radioactive waste disposal. As a basis for the model calculation, a literature review of appropriate constitutive models and material parameters of homogenous zones was conducted. Thermo-mechanical coupled calculations have been carried out using large-scale 3D models. Due to the thermal loading of HLW waste, the temperature of rock mass rises. Thermally induced deformation of the formation leads to uplift of the rock above the repository. Integrity is assessed against a dilatancy criterion and a fluid pressure criterion. Calculations indicate that barrier integrity of the bedded salt is locally and temporarily violated. However, a large region of the salt barrier is not affected. At any time, at least 300 m of intact salt barrier remains, and no continuous migration paths occur.