Figure 14. Dry Cask storage Facility at the Decommissioned maine yankee Reactor site

to new information and lessons learned—including lessons learned from a more complete understanding of recent events at Fukushima—are clearly needed to sustain this confidence. Any realistic assessment of the time it can be expected to take to site, construct, license and begin operating consolidated storage and disposal facilities underscores the need for continued vigilance and attention to safety and security concerns at existing storage sites.

This chapter elaborates on the above points and on other recommendations developed by the Commission’s Transportation and Storage Subcommittee. We begin by discussing the role of storage as part of a comprehensive waste management strategy, before developing the rationale for consolidated storage. Subsequent sections of this chapter discuss safety and security issues at existing dispersed storage sites. Further discussion of these subjects can be found in supporting Commission materials and in the report of the Commission’s Transportation and Storage Subcommittee (available at www.brc.gov).

5.1 tHe Role oF stoRAGe

Storage in some form, for some period of time, is an inevitable part of the nuclear fuel cycle. This is simply because spent fuel, upon being removed from the reactor core, needs to be allowed to cool before it can be handled further. In the early days of the nuclear energy industry it was assumed that storage times for spent fuel would be relatively short—on the order of several years to a decade or two at most before spent fuel would be sent either for reprocessing or final disposal. The current reality, of course, is much different. Storage is not only playing a more prominent and protracted role in the nuclear fuel cycle than once expected, it is the only element of the back end of the fuel cycle that is currently being deployed on an operational scale in the United States. In fact, much larger quantities of spent fuel are being stored for much longer periods of time than policy-makers envisioned or utility companies planned for when most of the current fleet of reactors were built.

Chapter 3 of this report describes how the current situation—in which the vast majority of spent fuel is still being stored at the reactor sites where it was generated— arose by default as the U.S. government first decided not to pursue reprocessing and then fell further and further behind in developing a disposal repository. With DOE in breach of its contractual waste acceptance obligations, individual utilities have been left to cope on their own with the problem of growing spent-fuel inventories. Over the years, most of them have responded by packing spent fuel more tightly in cooling pools and, increasingly, by moving the spent fuel from wet storage to on-site dry cask storage when available space in the pools is exhausted. At plants that have implemented this form of storage, canisters containing spent fuel are typically placed on concrete pads in an open air enclosure or in horizontal concrete vaults on site where they are monitored on an ongoing basis. Other storage methods, such as dry vault storage for fuel from the St. Vrain plant and wet storage at the GE Morris facility, have also been licensed. Existing dry storage systems at nuclear facilities are robust. In the most widely used type of dry storage system, a canister containing used fuel is placed inside a concrete structure. The canister typically consists of 1/2 inch to 5/8 inches thick stainless steel; it serves as the primary boundary to confine radioactive material (see figure 4). Depending on the cask system design, the canister may be oriented FiGuRe 14. DRy CAsk stoRAGe FACility At tHe DeCommissioneD mAine yAnkee ReACtoR site

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