Cask Operation and Maintenance for Spent Fuel Storage

Steady arising of spent fuel from nuclear power production, against the current backdrop of delays in disposal and limited reprocessing, has entailed rising inventory of spent fuel to be stored for extended period of time possibly a hundred years or even beyond. At the end of 2003, about 178 000 t HM of spent fuel were stored in storage facilities around the world (the balance 86 000 t HM from global arising 264 000 t HM having been reprocessed). With an assumption that roughly one-third of the global inventory would be removed by reprocessing, about 8 000 tHM/year on average will need to be added annually to the global inventory. The current trend toward extended storage is likely to continue in the foreseeable future [1]. In fact, interim storage is an essential platform for any option to be chosen later as an endpoint for spent fuel management. In view of such a circumstance, the most imminent service required for the spent fuel management worldwide is to provide adequate storage for the future spent fuel inventory arising either from the continued operation of nuclear power plants or from the removal of spent fuel in preparation for plant decommissioning. While the bulk of the global inventory of spent fuel are still stored in AR pools, dry storage has become a prominent alternative especially for newly built AFR facilities, with more than 17,000 t HM already stored in dry storage facilities worldwide. Storage in cask under inert conditions has become the preferred option, given the advantages including passive cooling features and modular mode of capacity increase. In terms of economics, dry storage is particularly propitious for long-term storage in that operational costs are minimized by the passive cooling features. The trend toward dry storage, especially in cask type, is likely to continue with an implication that and the supply will closely follow the increasing demand for storage by incremental additions of casks to the effect of minimizing cost penalty of the idle capacities typical of pool facilities.