Advances in Technology for Storing Light Water Reactor Spent Fuel

By 2003, the year the U.S. Department of Energy (DOE) currently predicts that a repository will be available, 58 U.S. commercial nuclear power plant units are expected to run out of wet storage space for light water reactor (LWR) spent fuel. To alleviate this problem, utilities have implemented advanced storage methods that have increased storage capacity as well as reduced the rate of spent-fuel generation. These methods include (a) transshipping spent-fuel assemblies between pools within the same utility system, (b) reracking pools to accommodate additional spent-fuel assemblies, (c) taking credit for fuel burnup in pool storage rack designs, (d) extending fuel burnup, (e) rod consolidation, and (f) dry storage, Wet storage continues to be the predominant U.S. spent-fuel management technology, but as a measure to enhance at-reactor storage capacity, the Nuclear Waste Policy Act of 1982 authorized DOE to assist utilities with licensing at-reactor dry storage. Information exchanges with other nations, laboratory testing and modeling, and cask tests cooperatively funded by U.S. utilities and DOE produced a strong technical basis for confidence that LWR spent fuel can be stored safely for several decades in both wet and dry storage. Licensed dry storage of spent fuel in an inert atmosphere was first achieved in the United States in 1986. Studies are under way in several countries to determine acceptable conditions for storing LWR spent fuel in air. Rod consolidation technology is being developed and demonstrated to enhance the storage capacity for both wet and dry storage. Large-scale commercial implementation is awaiting optimization of practical and economical mechanical systems.