PILOT STUDY ON THE RETURN OF REPROCESSED WASTES FROM GERMAN RESEARCH REACTOR FUEL ASSEMBLIES FROM THE REPROCESSING PLANT IN DOUNREAY, SCOTLAND

The German Federal Ministry of Education and Research (BMBF) assigned DBE TECHNOLOGY GmbH with a project to review the prerequisites and contractual boundary conditions for the return of cemented residues from the reprocessing plant at Dounreay to Germany. For this purpose, the bilateral contracts between the German research facilities and the operator of the reprocessing plant at Dounreay, the UK Atomic Energy Authority (UKAEA), were examined. Possible interim storage sites in Germany were sought for, flasks suitable for transport and casks suitable for interim storage and final disposal were researched, and transportation options were explored. Based on the results of theses investigations, strategies for the return of the drums containing cemented residues were developed, including time and effort estimates. The waste drums are 560-litre drums with NIREX specification. The drums containing the cemented residues may be provided at Dounreay starting in 2008. Their return to Germany has to be finished between 2018 and 2022 at the latest. The Federal Office for Radiation Protection (BfS) stated that the cemented waste is classified as intermediate radioactive waste which, according to the German nuclear energy act (AtG), is ‘other radioactive materials’. Before the delivery of the drums to a final disposal, an interim storage in Germany may be necessary. Thus, possibilities for interim storage at German facilities were investigated. The Jülich Research Centre (FZJ) and the Central Decontamination Department (HDB) of the Karlsruhe Research Centre (FZK) are recommended as potential locations for the interim storage. For the transport of the drums, a package with a type B(U)-license is necessary. For the final disposal, a category-II cask (accident resistant package) is required. As no suitable flasks and/or storage casks are available at present, concepts and proposals for the modification of existing casks were compiled. At this moment, various cask concepts are being considered. Schedules and cost estimations for various return concepts were compared. It was shown that the return of the residues from Dounreay directly to a final disposal would be more favourable from a technical, licensing and economic point of view than the interim storage in Germany and final disposal afterwards.