WASHINGTON -- A year after a 30-foot tsunami ravaged the Fukushima Daiichi nuclear power plant in Japan, some scientists say regulators underestimate the threat that climate change poses to nuclear power plants in the U.S.
"There are clear lessons learned from the Fukushima disaster, yet our government allows the risks to remain," said Jordan Weaver, a scientist with the Natural Resources Defense Council.
"It doesn't have to take an earthquake and a tsunami to trigger a severe nuclear meltdown. In addition to human error and hostile acts, more common occurrences like hurricanes, tornadoes and flooding -- all of which took place around the country last year -- could cause the same type of power failure in U.S. plants."
Nuclear reactor facilities, which need a reliable source of water for cooling purposes, are usually located near the ocean or alongside a large lake or river. There are 104 nuclear reactors at 65 sites across the U.S., nine of them located within 2 miles of the coast. That's a somewhat fraught positioning from the lens of climate science, particularly since the Intergovernmental Panel on Climate Change report from 2007 found that ocean levels are rising roughly 1.2 inches each decade, with some scientists predicting that water levels could rise by as much as a meter by the end of the century.
That may not sound like much, with most nuclear power plants a full 20 to 30 feet above sea level, but each additional inch of water increases the risk of flooding and heightens storm surges, two of the more significant threats of a warmer planet.
What's more, recent reports show accelerated glacial melt, indicating sea levels will rise more dramatically than previously predicted. The Arctic ice study by the International Arctic Monitoring and Assessment Program found that sea levels could rise 35 to 63 inches by 2100, far more than the 7 to 23 inches predicted by the IPCC in 2007.
"When the sea level slowly creeps up, what you get are storm surges, and it's the storm surges that are going to be the first signal that you've got a problem," says environmental historian John Perkins of Evergreen State College in Olympia, Wash., who has studied the effects of climate change on nuclear plants in the U.S.
Even without a significant rise in sea levels, U.S. coastal plants have already had some uncomfortably close calls. In August 1992, a Category 5 storm hit Florida's eastern coast just eight miles from the Turkey Point nuclear facility. With its 16-foot surge of water and 175 mph winds, Hurricane Andrew was one of the worst in recent history.
The hurricane destroyed Turkey Point's entire suppression system, stripping bare much of the cabling on the outside of the reactor and spilling roughly 100,000 gallons of coolant. Perhaps most troubling was the loss of external power for a full five days, with engineers relying on on-site diesel generators to cool the reactors' cores. That backup system, which kept the plant running safely in the days after the storm, was completely wiped out at the Fukushima plant in Japan's tsunami last year.
South Florida is more prone to hurricanes than any other part of the country, and storm intensity as well as surge-related flooding are expected to increase significantly by the turn of the century, with an estimated 28 percent increase in damage potential for storms coming from the Atlantic Basin -- where tropical storms or hurricanes usually occur in the Atlantic -- according to research from National Oceanic and Atmospheric Administration climate scientist Thomas Knutson and his team.
It's not just reactors along the coast that are vulnerable to the effects of global warming. In Nebraska, near Blair, where the Missouri River overflowed its banks last summer, floodwaters breached the defenses of the Fort Calhoun plant, with aerial photos depicting the nuclear reactor surrounded by a lake of water. Yet the NRC was quick to assure the public that the situation was under control.
"The pictures from the helicopter tour over the Fort Calhoun plant look worse than the situation really is. The plant is surrounded by water, but protected by flood gates, waterproof bunkers and other systems, many put in place by owner Omaha Public Power District as the result of an NRC inspection two years ago that found the plant's flood protection systems lacking," the NRC wrote in a statement.
"Now, all the vital safety equipment is safe and dry, despite the fact workers wearing hip-high waders pulling boats laden with equipment walk through three-plus feet of water around the plant's perimeter."
Yet, for as bad as the photos appeared, the Missouri River reached water levels 1,004 feet above sea level, with key facilities at Calhoun protected for a flood level of up to 1,014 feet -- only a 10-foot safety margin. And flooding on major rivers is expected to increase with rising sea levels, according to research from the Environmental Protection Agency.
The NRC similarly holds up the incident at Turkey Point as a triumph.
"U.S. nuclear power plants are already designed and built to keep the public safe in the face of the most extreme weather conditions possible at a given site, including flooding scenarios that far outweigh any impact from projected tidal level changes," NRC spokesman Scott Burnell told The Huffington Post in an email. "For example, Turkey Point in Florida safely withstood a direct hit from Hurricane Andrew, and several U.S. plants have safely withstood tornado damage to their sites and transmission lines, including during last year's severe outbreak."
The units at Browns Ferry are among 23 U.S. nuclear reactors similar in design to those knocked out during the tsunami at Fukushima nuclear power plant, where backup generators were swept away. While the tornado-stricken plants in Virginia and Alabama were able to rely on backup power, if both primary and backup systems fail for even a matter of hours, it can result in a meltdown and an airborne radioactive plume.
Burnell also cited the incidents in Nebraska, adding, "Two plants in the Great Plains also safely withstood last year's historic flooding on the Missouri River. Given that a plant can withstand the most severe events at its site, it can also withstand multiple 'most severe' events."
Jeff Masters, a meteorologist with the forecasting service Weather Underground, doesn't see it that way.
"On the one hand, that should make us feel a little more comfortable," he said, noting there was no release of radioactive material at Turkey Point following Hurricane Andrew. "But on the other hand, there were some scary things that happened there."
"One thing we learned from the Fukushima disaster," Masters explained, "is that when you get an extreme natural disaster event, unexpected things can happen to your power plant because you're subjecting it to things that are extreme. You can't always prepare for every contingency. Unanticipated things are bound to happen."
Most of the nuclear power plants in the United States were designed in the 1960s and 1970s, Perkins notes, before climate change was on most scientists' radar.
"There were a few scientists who were worried about climate change," said Perkins, "but there was very little work that had been done, and the people who were building and designing and regulating the power plants were worried about a whole host of other things."
The NRC has vowed to implement recommendations from the agency's Japan Lessons-Learned Task Force, which will evaluate U.S. plants for their resistance to seismic and flooding events. There's significant disagreement, however, about what constitutes a thorough review, or even what needs to be reviewed.
Redesigning nuclear plants to address newer threats from climate change may also be too expensive at many locations.
"It's always a matter of cost against the benefit," said Kennette Benedict, executive director of the Bulletin of Atomic Scientists. "So far we've done pretty well, but there have been enough accidents that you have to ask yourself whether we want to put more money in, because the consequences of an accident are so grave."
Vulnerability assessments are rooted in a chain of uncertainties: greenhouse gas emissions, weather predictions, regulatory funding -- and Benedict questions whether energy yielded is worth the risk of another meltdown.
She explains the issue in terms of "normal accidents," a term first coined by Yale sociology professor Charles Perrow.
"When you have very complex technologies that are in the keeping of complex bureaucracies populated by fallible human beings, you'll have what are called 'normal accidents.' They're waiting to happen," she said. "The problem is that when you couple the idea of normal accidents with a technology as dangerous and powerful as nuclear technology, then you've got some real problems."
She adds, "I think we have to -- as a society, as members of a society -- examine carefully what the trade-offs are, and if the trade-offs are huge accidents every 30 years, is that worth the power that we're getting from these electricity-generating power plants?"