New generation of CASTORR casks - Status of development and licensing

Within the German return programme for vitrified high level waste (HLW) from reprocessing at COGEMA and BNFL there will be an increasing number of containers of which the heat capacity and radioactive inventory will exceed the technical limits of the CASTORR HAW 20/28 CG, which has been used up to now. Therefore, GNS has developed a new cask, named CASTORR HAW28M, meeting these future requirements. The challenge for the development results from higher requirements of the technical specification, particularly related to fuel which is reprocessed. As a consequence of the reprocessing of fuel with increased enrichment and burn up, higher heat capacity and sophisticated shielding measures have to be considered. Requirements for new cask designs for transport and long-term dry storage of spent fuel assemblies (FA) from LWR-reactors are based on both increased source terms of the LWR FA including MOX FA, as well as the demand for economical optimization by increased cask capacities. For this, cask development is the challenge to create and establish cask designs that can accommodate more FA with higher source terms, each under fixed boundary conditions, i.e. transport requirements and limitations of the power plants boundary conditions as crane loads and/or fixed maximum dimensions. CASTORR Va/21 for PWR FA is another new cask which copes with the above mentioned requirements and which creates along with CASTORR HAW28M a new cask generation. New materials and new design methodologies have been developed and applied. The main tasks were focused on material qualification, component tests, detailed design analysis and design verification up to extended drop test programmes under supervision of the Federal Institute of Material Research and Testing (BAM). The licensing procedure for the new cask generation has been carried out. The license for the first cask of the new generation is expected in 2006