Retrievability of finally disposed spent fuel

According to the currently valid version of the German Atomic Energy Act, two approaches to close the back end of the fuel cycle are allowed in Germany: reprocessing and direct disposal. In both cases and because of their fissile material content, fuel elements are subject to continuous safeguards monitoring by Euratom and the International Atomic Energy Agency to prevent any undue diversion. In this context, the question arises of whether retrievability of fissile material during the postoperational phase of a repository is possible, despite the high temperatures and thermomechanical stresses in the mine cavities, and by which means access to the disposed-of-fissile materials can be regained. An answer was given by a detailed study of the technical feasibility of retrieving spent fuel from a closed and abandoned repository in a salt dome, assuming that a later retrieval was originally not considered in design and construction of the repository.