Terrorists targeting the high-density storage systems used at nuclear power plants throughout the nation could cause contamination problems "significantly worse than those from Chernobyl," the study found.
The study authors, a multi-institutional team of researchers led by Frank von Hippel of Princeton, called on the U.S. Congress to mandate the construction of new facilities to house spent fuel in less risky configurations and estimated a cost of $3.5 billion to $7 billion for the project.
The paper is scheduled to be published in the spring in the journal Science and Global Security.
Strapped for long-term storage options, the nation's 103 nuclear power plants routinely pack four to five times the number of spent fuel rods into water-cooled tanks than the tanks were designed to hold, the authors reported. This high-density configuration is safe when cooled by water, but would likely cause a fire -- with catastrophic results -- if the cooling water leaked. The tanks could be ruptured by a hijacked jet or sabotage, the study contends.
The consequences of such a fire would be the release of a radiation plume that would contaminate eight to 70 times more land than the area affected by the 1986 accident in Chernobyl. The cost of such a disaster would run into the hundreds of billions of dollars, the researchers reported.
The study builds in large part on analyses already done by the Nuclear Regulatory Commission, pulling together disparate sources and adding new calculations to put the issues in sharper focus, said von Hippel.
"The NRC has been chewing on this for 20 years," said von Hippel. "That's one of the reasons why we did this paper -- because they never seem to do anything about it."
Von Hippel, who co-directs the Program on Science and Global Security in the Woodrow Wilson School of Public and International Affairs, said the direct impetus for the study came from an investigation conducted by undergraduate students last year. Five students focused on the New Jersey Salem Nuclear Generating Station and issued a report calling for the distribution of protective potassium iodide pills to people within 50 miles of nuclear plants, improvement of mock attack drills and reconfiguration of spent fuel storage.
"It was a very good group of students and an excellent report," said von Hippel, who enlisted colleagues to conduct a more detailed analysis of the spent fuel issue.
Among the co-authors of the new study are analysts from the Institute for Policy Studies and the Nuclear Control Institute in Washington, D.C., the Institute for Resource and Security Studies in Cambridge, Mass., and the Security Studies Program at the Massachusetts Institute of Technology.
At issue in the study is how nuclear power plant operators deal with the narrow, 12-foot-long rods of uranium that, after three or four years of use, no longer contain enough chain-reacting material to sustain a nuclear reaction. For the first few years after they are taken from the reactor, the fuel rods continue to generate a lot of heat due to their intense radioactivity. Without cooling, the rods would burst and ignite the zirconium alloy sheaths in which they are encased.
The water-filled cooling tanks were originally designed to keep only about 100 metric tons of the hottest rods, while the cooler ones would be moved to a nuclear fuel recycling plant, which was never built. The United States also has not yet built a long-term storage facility for nuclear waste, so the pools have been packed with 400 tons or more. In its low-density configuration, a cooling tank could be adequately cooled by air in the event of a loss of water, while the high-density system could not.
The authors recommended returning the water tanks to their low-density configurations and building onsite storage facilities, which would use air-cooling, for the older fuel. Some of the cost of this work already is budgeted as part of a plan to build a national storage facility at Yucca Mountain, Nevada, the authors noted. That project, however, is not scheduled to be built for another 10 years and would then take another 20 or 30 years to take enough waste to relieve the water tank density.
The decision whether to reconfigure the spent fuel storage systems comes down to a cost-benefit analysis, von Hippel said. Even without the possibility of terrorism, the opportunity to reduce the risk of more conventional mishaps would justify the expense under most circumstances, he said. The chances of a successful terrorist attack are hard to quantify, he acknowledged, but if the odds were at least 1 percent over 30 years, then the expense would be justified.
"The Congress really needs to make a political judgment and needs to provide the Nuclear Regulatory Commission some guidance," he said. The report authors briefed congressional staff members on Jan. 30.
"We've made the issue much more visible," said von Hippel. "It will take some time for any of this discussion to turn into concrete action."