U.S. nuclear power plants are storing thousands of tons of spent atomic fuel that pose risks like those triggered in the Japan earthquake that has crews battling a potential meltdown of stored fuel, nuclear safety experts said.
U.S. nuclear plants had an estimated 63,000 metric tons (138.9 million pounds) of spent fuel stored on site as of January 2010, according to a report from the U.S. Nuclear Regulatory Commission. About 2,000 metric tons a year is expected to be added to that total, the NRC said.
The fuel, which contains uranium and radioactive byproducts, is taken from reactors and stored at least five years in water-filled cooling pools, then sometimes sealed in steel-and-concrete casks for longer-term storage.
“In the U.S., we are worse off, said David Lochbaum, a nuclear engineer for the Union of Concerned Scientists who is a former safety instructor for the NRC. ‘‘Our spent-fuel pools are more full than in Japan.’’
Nuclear fuel storage has been a key sticking point in the expansion of nuclear power in the U.S. as landowners and environmental groups oppose plans for nuclear fuel dumps. A storage site at Yucca Mountain in Nevada was canceled by the Obama administration in 2009 after 20 years of planning and a cost of $9 billion.
Tokyo Electric Power Co. is working to contain damage at its six-reactor Fukushima plant following this month’s earthquake and tsunami that shut down power to its cooling systems. The company is trying to keep the spent fuel stored in cooling pools covered with water to prevent them from being exposed to air. If exposed to air, the fuel would overheat and melt down, releasing radiation.
Crisis in Japan
The crisis in Japan underscores why the U.S. must alter the way it stores spent fuel at its power plants, said Robert Alvarez, a senior scholar at the Washington-based Institute for Policy Studies who has studied the risks of spent-fuel storage.
Thirty-five states have facilities storing spent nuclear fuel, including 31 with operating reactors, the NRC said in its 2010-2011 Information Digest. Illinois had the most fuel in storage through 2009, followed by Pennsylvania, South Carolina, New York and North Carolina, according to the NRC’s ranking.
‘‘Unlike the Japanese reactors, in the United States, the spent-fuel pools are currently holding, on the average, four times more than their designs intended,” Alvarez said. “They are densely compacted.”
Radioactive material generates heat, so spent fuel rods need to be cooled or their temperature will continue to rise until they break or catch fire, releasing radiation into the air, said Paul Padley, a physics professor at Rice University in Houston.
Cooling the Fuel
Spent fuel removed from reactor cores must remain in a cooling pool for at least five years, and generally stay there longer in the U.S., said David McIntyre, a spokesman for the NRC. Then, the fuel can be taken out and sealed in a solid cask, although that is more expensive and labor intensive, he said.
Bryant Kinney, a spokesman for the Nuclear Energy Institute, said a little less than a quarter of the spent fuel stored at U.S. nuclear power plants is in dry casks. Nuclear plants weren’t designed with the intention of storing their spent fuel permanently, said Bozidar Stojadinovic, a professor in the department of civil and environmental engineering at the University of California, Berkeley.
“The plants have always been designed with the idea that the fuel will be taken care of,” Stojadinovic said. “The government promised to do that.”
Most spent-fuel pools have only one system to circulate coolant, even though they accumulate far more fuel than a reactor core, Lochbaum said. Reactors, by comparison, are required to have multiple backup systems such as diesel pumps and batteries to keep their fuel cool in case of a shutdown.
There is typically more fuel stored in pools in the U.S. compared with Japan, in part because Japanese plants reprocess some of their spent fuel, Lochbaum said. U.S. operators originally expected to ship spent fuel to a recycling plant or store it at a collective site away from the plant -- plans that never materialized.
U.S. President Jimmy Carter banned reprocessing of spent commercial nuclear fuel in 1977 over concerns related to nuclear weapons proliferation. Though President Ronald Reagan in 1981 lifted the ban on commercial reprocessing, there was little investment in recycling capacity so most plants still store their spent fuel on site.
Environmentalists and other opponents said the Yucca Mountain site might be subject to earthquakes, and that transporting the radioactive material to the site would be hazardous. Washington state, home of a World War II-era plant that built one of the first nuclear bombs, is suing along with other states to force the federal government to reverse its decision and allow storage to be built at Yucca.
The possible dangers of spent-fuel pools were discussed in a report from the National Academies Press in 2006 that looked at potential terrorist attacks. One of the scenarios considered was similar to the crisis spawned by the earthquake in Japan, Padley, the Rice University professor, said.
Nuclear plants likely will face new requirements related to spent fuel in order to obtain future license extensions, said Kevin Book, a managing director at ClearView Energy Partners, a Washington policy group. If those regulations prove too expensive, some operators may consider shutting plants, he said.
Lochbaum said some safety improvements, such as better fire-fighting systems, have been added to spent-fuel pools since the terrorist attacks of September 2001. The U.S. still hasn’t acted to fix the situation, by either finding a permanent home for spent fuel or requiring that more of it be stored in casks, he said.
“We know the hazard, we know what the fix is,” Lochbaum said.