Future requirements to be observed in the conditioning of spent nuclear fuel assemblies

The amendment of para. 9 of the Atomic Energy Act (AtG) has been the reason for commissioning the study presented in this report for the purpose of assessing and explaining the modifications relating to the disposal of spent fuel. The study assesses the enhanced quantity of spent fuel assemblies from German nuclear power plant possibly to be disposed of in future by direct ultimate disposal, and assesses the resulting consequences relating to the capacities and safety engineering measures to be considered for the relevant sites and processes of conditioning plant, interim storage facility, and repository. The report presents 4 different scenarios based on assumptions relating to the future uses of nuclear energy in Germany and the resulting waste management strategies, describing the relevant time frame of increase of spent fuels from nuclear power plant and their disposal by the 2 options of reprocessing or direct ultimate disposal. The increase in demand for conditioning capacity and the linked technical and safety requirements are assessed referring to the pilot conditioning plant as a comparative reference plant. This approach is justified by the fact that no essential modifications are expected to become necessary when switching from pilot plant scale to industrial scale of conditioning activities with a throughput of up to 580 Mg/a of heavy metals. Considering the permissible heat input to the repository, decay times spanning from reactor defuelling until ultimate disposal are calculated to be between 30 and 34 yrs. This has an effect on the demand for interim storage capacities, which is calculated separately for the 4 scenarios. Assuming the industrial scale conditioning activities to be commissioned in 2005, and a continuance of nuclear energy uses at a steady level together with the existing ultimate storage strategy, the future demand for interim storage capacity is estimated to amount to approx. 8 interim storage facilities of the type of the Ahaus/Gorleben sites. (orig./HP)