How metal casks fit spent fuel interim storage strategies

In the 1980's the first needs for additional spent fuel storage capacity appeared in the US and various programs were implemented to increase existing storage capacities. Among a number of storage systems available, three main families emerged for which an extensive experience has been gained, all of them relying upon the principle of dry storage: concrete modules, concrete vaults, and metallic casks. Each system decidedly has its own merits in light of specific customer requirements, fuel quantities and utility strategies. Each technology meets the overall objective of allowing the interim storage of spent fuel, but the services provided vary widely. A large variety of technical and practical considerations can influence the choice of the utilities and economic aspects are complex because they are not limited to the investment cost of the system. In the 1990's, the needs for additional spent fuel storage are not only related to the American scene, but encompass several other countries. Such large diversity of applications prompted designers to offer metal casks in a variety of configurations, each tailored to meet specific utility requirements. This paper reviews the determining factors considered in the selection of an interim storage system: long term safety; ease of operations; and overall economics