Fundamental R&D Work on Methods for State Monitoring of Transport and Storage Containers for Spent Fuel and Heat-Generating High-Level Radioactive Waste on Prolonged Intermediate Storage

Abstract

The continuing search for a long-term storage for highly-active nuclear waste in Germany requires a prolonged intermediate storage period of spent fuel in dry storage casks at the power plant sites. Currently, it is not sufficiently clear if there might be a loss of integrity of the fuel rods within such long periods, e.g. due to rising pressure from gaseous products of nuclear decay. Regarding a final evaluation, extrapolative modelling of the radiochemical and thermomechanical material behavior is challenging and not suitable for predictions on the condition of storage container inventory after the intermediate storage period. Therefore, it is of public interest to find measurement principles or methods which can provide information about the condition of the storage container inventory. In line with a cooperative project (project partners: Technical University Dresden, Zittau/Görlitz University of Applied Sciences) different measurement principles and methods (radiation emission, muon transmission, thermography, acoustical spectrometry) for non-invasive condition monitoring of the storage container inventory in case of prolonged intermediate storage are going to be investigated and evaluated. The results shall help to determine suitable methods for the identification of both changes of the spent fuel and inner container structure over long periods without opening the container and would be a significant contribution for the long-term safety of intermediately stored highly radioactive waste. Furthermore, suitable methods would provide information about the transport and conditioning ability of the waste before transfer to the repository. This paper deals with the content of the subproject of Zittau/Görlitz University of Applied Sciences as well as with the approach for project realization. A further main part of this paper is the development of experimental infrastructure to support the investigations.