,- Federal Office for the Safety of Nuclear Waste Management, Research/International, Cologne, Germany (guido.bracke@base.bund.de)
In 2022, Germany will have a total of about 1,750 transport and storage casks with high-level radioactive waste, spent fuel and vitrified waste. The search for a repository for high-level radioactive waste is separate from storage. However, storage licences will expire before a repository is available. The aim of this research project was to investigate possible interactions between extended storage and final disposal [1], [2].
The research project 'KombiLyse' [2] was carried out by GRS gGmbH. GRS investigated ageing effects and damage mechanisms on the waste, including the transport and storage casks. This included international test and investigation programmes on material and component behaviour. The analyses did not give any indication of inadmissible temperature-related effects during dry storage. The effect of ionising radiation during storage was also found to be low. According to the results of the study, no systematic failure of cladding tubes, casings or barriers is expected during extended storage of up to 100 years.
Hypothetical scenarios were analysed, leading to hypothetical measures that could counteract the degradation of cladding tubes, enclosures or barriers. For example, if undesirable radiation-related effects were to occur, they could be mitigated by early removal to a buffer storage facility at a site where conditioning into the final waste form would be possible.
The study used reference disposal concepts to assess the impact of the hypothetical measures. These included the former German concept for rock salt, the Swiss concept for claystone and the Swedish concept for crystalline rock. The temperature, composition and availability of a fluid are important factors influencing corrosion and radionuclide mobility in a repository. Estimated containment times for radionuclides in canisters are still in the range of several thousand to hundreds of thousands of years (based on in-situ experiments, which show significantly lower corrosion rates than laboratory tests), considering hypothetical measures.
In Germany, waste acceptance criteria for high-level radioactive waste are still to be developed, which have a strong influence on conditioning and repackaging measures. A key finding is the highly significant influence of the future repository site and concept on the preceding disposal measures. Once a specific repository site, concept and waste acceptance criteria have been derived, it is recommended that hypothetical measures for extended storage and their interrelationships with disposal be reassessed. This would allow re-analysis of whether measures for extended storage could become realistic in relation to disposal and, if so, what the consequences for final disposal might be. At present, the study has not identified any hypothetical measures that appear to be necessary.
[1] G. Bracke, C. Borkel, F.-N. Sentuc, O. Bartos, F. Rowold, J. Krüger, K. Hummelsheim, M. Tzivaki, J. Nicol, Analysis of Safety-relevant Aspects regarding Dry Interim Storage and Final Disposal of High-Level Radioactive Waste: Evaluation of Hypothetical Measure and Their Implications, in: International Conference on the Management of Spent Fuel from Nuclear Power Reactors: Meeting the Moment (SFM24), Wien, International Atomic Energy Agency (IAEA), 10. - 14. Juni 2024.
[2] O. Bartos, K. Hummelsheim, J. Krüger, J. Nicol, F. Rowold, F.-N. Sentuc, M. Tzivaki, Vorhaben 4719F10701 (KombiLyse), Abschlussbericht, 2024.
How to cite: Bracke, G., Borkel, C., Maerten, L., and Kandemir, T.: Interim Storage and Final Disposal: Overview on hypothetical measures from a Study on Interrelationships, Third interdisciplinary research symposium on the safety of nuclear disposal practices, Berlin, Germany, 17–19 Sep 2025, safeND2025-141, https://doi.org/10.5194/safend2025-141, 2025.
