DESIGN, SAFETY ANALYSES AND TESTS OF PACKAGINGS FOR HLW AND SPENT FUEL TRANSPORT /STORAGE

On the basis of the provisional specifications of residues generated by a reprocessing plant, a conceptual design was prepared of a large packaging (with a total weight of 95 to 124 t) for high level vitrified solid wastes. Unlike spent fuel, the contents (vitrified solid wastes) are to be stored and disposed of after transportation. It is therefore necessary to pay extra attention to vibration and impact during transportation. Accordingly, the interactions between the packaging and the contents, and between one set of contents and another were clarified. A composite drop analysis was also carried out, as a result of which a method for analysing impacts on the contents during transportation was established. As a part of integrity assessment tests using model packages, drop tests and thermal tests were carried out on the model packages. The composite behaviour of the contents and their integrity were successfully verified. It was assumed that casks similar to the transport storage casks developed and licensed in Europe and in the United States of America could be used in Japan in the future. However, the con· ceptual designs of these transport/storage casks were modified to meet specifications applicable in Japan. Safety (in particular shielding) and economic considerations influenced the conceptual designs that were evolved of structurally simple cask-storage buildings, while taking account of the strength of the cask. Seismic safety analysis is important in Japan. Since the casks already meet transport standards (for example, they pass the 9 m drop test) and have sufficient structural strength, the integrity of the casks was shown to be maintained even in the event of a total collapse of the storage building.