Developing a radiation field-based monitoring system for the transport and storage cask inventory during extended interim storage

Abstract. High-level radioactive waste must be stored safely for a very long time but a suitable site for long-term storage is yet to be found. Additionally, in Germany the licence for transport and storage of casks is limited to 40 years, beginning at the time of emplacement and begins to expire for the first containers in the 2030s. To resolve the conflict between not having a final repository in time and the licence expiring, the licence must be extended while ensuring uninterrupted safe storage and safe transport. The DCS-Monitor II research project supports this process by investigating approaches to noninvasive, radiation field-based diagnostics that enable the observation of potential geometric changes of the cask inventory. Previous feasibility studies in the predecessor project DCS-Monitor I showed that cask monitoring using gamma radiation, neutron fields and cosmic muons is promising. In the ongoing research project presented here, the investigations on the qualification of radiation field-based diagnostics are extended via simulations. For muon imaging, a suitable procedure which solves the inverse problem to monitor the cask inventory is implemented. In addition, a partially automated gamma and neutron measurement system is being constructed and a muon detector is being developed and built. Both systems will be tested in field studies on large scale geometries and real containers.