Spent Fuel Storage: A Decommissioning Perspective

On June 6, 1989, the public voted to recommend that the Sacramento Municipal Utility District (District) no longer operate Rancho Seco Nuclear Generating Station as a nuclear power plant (although the vote did not prohibit sale to or operation by a qualified operator). Plant operators shutdown the plant on June 7,1989. Reactor defueling was subsequently completed on Dec. 8,1989. A total of 493 fuel assemblies are now stored in the Spent Fuel Pool (in the Fuel Storage Building). The original 10 CFR 50 operating license for Rancho Seco expires in the year 2008. Although the premature decommissioning of Rancho Seco presents some unique problems regarding the management of spent fuel, the District's decisions and lessons learned may benefit all facilities eventually facing decommissioning. The results of a review of this perspective well before decommissioning begins can be integrated into the decision-making process while still operating. To close and ultimately decommission Rancho Seco as safely and economically as possible, the District developed objectives to support the related disposition of the spent fuel. The objectives are: 1) Minimize occupational and public radiation exposure, 2) Minimize decommissioning costs, including the need to maintain the spent fuel pool and 3) Prepare the fuel for Department of Energy (DOE) acceptance. The District plans to use dual-purpose (combined storage/ transport) casks to meet these objectives. This plan is contingent upon a successful DOE demonstration program that will resolve any outstanding NRC issues and provide sufficient evaluation to permit licensing of existing large DOE-compatible shipping casks as dual-purpose casks.