The planned use of crushed salt as the backfill and sealing material for the final disposal of radioactive waste in rock salt is justified by the favorable crushed salt material properties. A prognostic long-term safety assessment requires sufficiently proved physical modeling that can only be met on the basis of suitable laboratory and field investigations. To reduce the currently existing uncertainties, triaxial long-term compaction tests TUC-V2 and TUC-V4 (KOMPASS II) were carried out.

For the deep geological disposal of high-level nuclear waste in rock salt formations, the safety concept includes the backfilling of open cavities with crushed salt. For the prognosis of the sealing function of the backfill for the safe containment of the nuclear waste, it is crucial to have a comprehensive process understanding of the crushed-salt compaction behavior. The KOMPASS projects were initiated to improve the scientific knowledge of using crushed salt as backfill material.

Within the scope of the presentation, a methodical approach for the systematic and structured development and validation of multiphysical material models, which has been successfully tested several times in the meantime, will be introduced and subsequently the concrete application of this methodology will be presented using the example of a material model taking into account the triaxial stress-strain behavior of crushed salt.