LONG TERM STORAGE OF USED NUCLEAR FUEL IN THE U.S.

The U.S. has made the decision to cease further development of the Yucca Mountain Repository and pursue alternate advanced nuclear fuel cycles and disposal technologies. This will extend the current U.S. policy to store used fuel in-place (e.g., at the reactor sites) for decades to come. While the U.S. regulatory framework for storage is stable and U.S. utilities are experienced in both wet and dry storage, technical issues need to be addressed when considering long term storage of fuel that may extend well past 100 years. In the U.S., storage licenses are issued for an initial period of 20 years, with the option to extend the storage term 2 times at 20 years each time. Therefore, the total allowable storage time for used fuel is 60 years. In theory, fuel could be stored in the pool for 60 years and then transferred to dry storage for an additional 60 years for a total of 120 years of out-of-reactor storage. In practice, utilities move used fuel out of pool storage earlier to dry storage to allow for continuous discharge of reactor fuel. The exception in the U.S. for this practice is the centralized pool storage facility in Morris, Illinois. This paper, therefore, will focus on long term dry storage of used fuel. Past 60 years, there is no technical basis for license extension. In addition to licensing storage systems past 60 years, there are associated regulatory issues with fuel retrievability and subsequent transportation after storage. The U.S. Department of Energy (DOE) initiated a program in FY2009 to address the issues associated with long term storage of used fuel. The program is designed to work closely with industry and international organizations to develop a technical consensus of defining material degradation mechanisms, identifying the data needs, planning for the development of a demonstration facility to gather necessary data, and developing the technical basis documents that will be used to demonstrate the viability of very long term storage. This paper will discuss the DOE program in the context of the larger national and international efforts currently being pursued.