// Long-term Safety Studies

RANGERS

Development of a guideline for the design and verification of geotechnical barriers for a high-level radioactive waste repository in salt formations

Geotechnical barriers for a repository in salt formations have been addressed in numerous research projects. Within the framework of the Preliminary Safety Analysis for the Gorleben site (VSG), a verification procedure for the integrity of closure elements in a high-level radioactive waste repository in steeply dipping salt formations was developed. In the ELSA project, shaft closures for high-level radioactive waste repositories were extensively studied. Initial recommendations for the planning and execution of geotechnical barriers were formulated by the Salt Mechanics Working Group of the DGGT. The BGE and BGE TECHNOLOGY have been developing and constructing flow barriers in the Asse repository for over ten years. So far, 32 flow barriers have been built and are in routine operation. A prototype sealing structure was built by BGE on a real scale at the Morsleben repository and is currently being scientifically investigated. Despite extensive knowledge and experience with geotechnical barriers in salt formations, there is a lack of regulations for quality-assured design of such structures for a high-level radioactive waste repository.

In collaboration with SANDIA National Laboratories, BGE TECHNOLOGY aims to develop a methodology in the RANGERS project that incorporates existing knowledge and accumulated experience about geotechnical barriers in salt in Germany and the USA. Recommendations for the design and verification of geotechnical barriers based on the state of science and technology are to be formulated, and an overview of innovative concepts, materials, and technologies that will shape tomorrow's state of the art will be provided.

The RANGERS project is divided into the following work packages:

WP 0: Organization of collaboration between BGE TEC and SANDIA – Literature review on geotechnical structures in salt
WP 1: Compilation of the state of science and technology in the planning and construction of geotechnical barriers for repositories in salt
WP 2: Derivation and compilation of boundary conditions and requirements
WP 3: Development of the methodology for the design and verification of geotechnical barriers for a high-level radioactive waste repository in salt formations
WP 4: Utilization of the methodology for the design and verification of geotechnical barriers for one of the generic repository concepts developed in the R&D project KOSINA.
WP 5: Evaluation of the results and comparison with findings from previous projects
WP 6: Documentation and final report