CONFIRMATION OF MAINTENANCE OF FUNCTION FOR TRANSPORT AFTER LONG-TERM STORAGE USING DRY METAL DUAL PURPOSE CASKS

Japanese first off-site interim spent fuel storage facility away from any reactor site is now under construction. Dry metal dual-purpose casks will be used on the project for the long term storage of spent fuels. Since the interim storage facility does not have any equipment for opening lids of these casks, safety of both casks and fuels during the post-storage transport is planned to be confirmed without opening lids of casks. In order to increase the reliability of the safety for the post-storage transportation, Nuclear Safety Commission of Japan, NSC, has been demanding operators to accumulate data about integrity of spent fuels which have been stored in dry conditions. Also, NSC has requested the Japanese authority NISA to establish reasonable rules for inspections at the time of post-storage transport. In order to meet this demand, Japanese utilities are trying to accumulate technical basis through the investigation of spent fuels which have been stored in on-site dry cask facilities at nuclear power plants (NPP). In addition, Japanese regulator has been building a reasonable regulatory system applied for the interim storage using dual purpose casks. This paper describes both the methodology and procedure for confirming the safety of dry metal dual purpose cask after long-term storage.