In Germany, rock salt is a possible host rock for a repository for heat-emitting radioactive waste. The safety concept for this repository type is based on a multi-barrier system consisting of the geological barrier, the waste canisters and engineered barriers. For backfilling and sealing measures of drifts and shafts crushed salt will be used due to its favorable properties as mined-off material.
Due to the paradigm change in the safety case and the necessity of a qualified prognosis of its long-term behavior, the requirements on the process understanding and numerical simulation of the crushed salt compaction behavior were extended. In the current state, some uncertainties with respect to the existing database and process understanding of crushed salt compaction still remain.
The objective of the mobility mission was aimed to support the improvement of knowledge and numerical skills by a strong scientific exchange contributing to the progress in the PhD which deals with the improvement of the numerical simulation of crushed salt compaction with the FEM code CODE_BRIGHT. This internship was important, since CODE_BRIGHT is developed at the Polytechnical University of Catalunya and a direct discussion and knowledge transfer with the code developer was possible.
During the four weeks of internship several meetings between the PhD and the host supervisor took place. It was started with a presentation of the numerical work done by the PhD student and a following discussion of general questions related to numerical modelling with CODE_BRIGHT and improvement potential in the field of the crushed salt constitutive models.
Improvement potential for crushed salt simulation was seen in formulation of the creep equations. During the internship an approach for the modification of the creep equations was carved out and it was started to investigate this idea.
Since four weeks are quite short for this amount of discussion potential, the work will be followed up by regularly online meetings.