The Development of the TS-69B Cask for Transport and Storage of Spent Nuclear Fuel

In Japan, spent nuclear fuel is stored on an interim basis until it is being reprocessed. Toshiba Energy Systems & Solutions Corp. (ESS) has developed TS-69B, a dry metal cask, designed to be used for the dual purposes of transporting and storing spent fuel assembly (i.e. transfer vessels) from the nuclear power plant site to outside. One of the key features of TS-69B is its capability of loading sixty-nine (69) spent fuel assemblies, which capacity is currently the highest in Japan. Furthermore, high burn-up (i.e. 48,000 MWD/MTU for maximum) spent fuel assemblies can be stored in TS-69B. The maximum volume of decay heat to be loaded is 16 kW. Due to its high heat removal capabilities, TS-69B could be the most effective cask type with regard to storing high burnup, 9 x 9 BWR fuel in Japan. In addition to the criticality prevention function, and shielding and heat removal capabilities, other features of TS-69B include its structural strength and a capability of maintaining long term integrity. In particular, in consideration of optimal fuel placement by 8 x 8 BWR fuel, the cask’s heat removal capability was analyzed. The evaluation results indicated that the temperatures of constituting materials do not impact the integrity of the cask, resulting in both the temperature of the metal gasket and the fuel cladding tubes being lower than the reference design values. Toshiba ESS has already filed the application for the TS-69B type certification with Japan’s Nuclear Regulation Authority (NRA). The interviews with the NRA have already finished; the type certification is likely to be obtained as all courses of the NRA reviews are complete.