Nuclear reactors generate used nuclear fuel, which needs to be safely managed. After discharge from operating nuclear reactors, the used nuclear fuel stored during a certain period of time in reactor pool is removed for reprocessing, disposal, or storage elsewhere.
A need for additional storage exists because of delays in used nuclear fuel disposition decisions and the continually increasing volume of used nuclear fuel discharged from reactors. Interim storage of used nuclear fuel is an essential part of the Nuclear Fuel Cycle providing nuclear safety and ensuring protection to the public.
Interim storage of used nuclear fuel currently used includes:
• Dry storage in vaults, casks and containers
• Wet storage, in silos, pools, outside reactor operating areas
Interim dry storage systems were originally designed for limited periods, generally 40–60 years. Interim dry storage is safe as shown by important industrial feedback and the operational records, even from severe accidents.
With extended interim dry storage, technical and safety investigations are presently being carried out concerning used nuclear fuel behavior, and the storage structures and their system components to demonstrate and justify the ability of the systems to store safely and securely the used nuclear fuel for a much longer period of time.
These investigations are part of the ageing management program for the storage system which should address a description of the ageing that could adversely affect structures and components important to safety.
This paper provides highlights of issues related to managing effects on dry cask storage systems for long-term interim storage and transportation of used nuclear fuel.