(GRS 545) Sealing Capacity of a Seal System in Rock Salt – Hydraulic Impact of the EDZ Long-term Evolution

O. Czaikowski, J. Dittrich, L. Friedenberg, U. Hertes, K. Jantschik, M. Komischke, K. Wieczorek, B. Zehle

GRS is investigating sealing and backfilling materials planned to be utilized in a nuclear repository in a salt formation. The program aims at providing experimental data needed for the theoretical analysis of the long-term sealing capacity of the seal system, including the closing of the contact seam and the recovery of the excavation damaged zone (EDZ) under load and dry or wet conditions. The interaction with sealing materials is simulated in laboratory tests by using hollow cylinders of salt equipped with a central concrete seal in isostatic cells. Experimental investigations on the long-term re-compaction behavior of the sealing system, under partial or near-full brine saturation, are performed. First results showed that the method is able to fulfil the expectations of providing useful data for long-term predictive calculations. In addition, some first numerical calculations have been performed, based on former calibration work and focusing on the simulation of the contact zone evolution. This report resumes the discussion on reduction of permeability resulting from mechanical closure by creeping of salt, which is accelerated in the presence of solution, or by chemical reactions.