NUMERICAL SIMULATION OF LEAK TIGHTNESS UNDER DROP ACCIDENT CONDITIONS

During the handling of transport and storage casks in the interim storage facility in Gorleben (Germany) different drop accident scenarios are possible. In the storage configuration the containment system consists of the thick walled forged steel cask body with welded forged bottom and the tightness barriers with metallic gaskets. To guarantee the safe confinement of the radioactive inventory under hypothetical accident conditions the integrity of the cask body as well as the leak tightness of the gaskets can be demonstrated by using a numerical simulation. A finite element analysis of the mechanical behaviour of the closure system under hypothetical accident conditions in the storage facility in Gorleben has been carried out exemplarily for a storage and transportation cask for vitrified high active waste. Different possible accident scenarios and the equivalent finite element models are introduced. The material models used for the cask and the ground as well as the boundary conditions are described. Finally suitable assessment criteria for integrity and leak tightness are discussed.