The scramble to cool the Fukushima Daiichi nuclear complex with seawater in the aftermath of Japan's disastrous accident put a spotlight on just how much cold water an atomic reactor needs to function — and not just in a crisis.
All existing nuclear plants use vast amounts of water as a coolant. But in recent years — often far from the public eye — hot river and lake temperatures have forced power plants worldwide to decrease generating capacity.
Experts say the problem is only getting worse as climate change triggers prolonged heat waves, prompting calls for changes in siting processes.
"As a long-range strategy, [the industry] might change where we site new plants to have better use of water resources," Gary Vine, an independent consultant, told SolveClimate News. Vine has worked in the nuclear industry for decades and is a former employee of Electric Power Research Institute, a utility group.
There is also hope that new technologies will help mitigate the problem.
The U.S. Department of Energy is part of an international team working to design the next generation of nuclear plants — some of which will use less water than traditional plants. But the project faces numerous challenges such as cost and implementation barriers, and the DOE anticipates that the generation IV reactors will not be commercially available for at least two decades.
In the meantime, the scope of the problem is still not precisely known.
Preliminary data from the Union of Concerned Scientists (UCS), an environmental and nuclear watchdog group based in Cambridge, Mass., shows that seven nuclear units at five facilities had to reduce generating capacity due to warm waters on at least 15 occasions between May and September 2010. The plants were in New Jersey, Pennsylvania, Illinois and Georgia. While such incidents didn't affect plant safety, they posed economic risk and decreased power availability.
In one case, which did not appear in the UCS database, the Tennessee Valley Authority's Browns Ferry station near Athens, Ala., lost over $50 million dollars when it was forced to run at half capacity for eight weeks last summer, passing the price surge to customers.
During a blistering heat wave in Europe in 2003, France cut 4,000 megawatts of nuclear power — the equivalent of shutting down four power plants — at a time when demand for air conditioning was at its highest.
Figuring Climate Impacts Into Siting
Of the 104 nuclear plants in the U.S., over 30, or about one-third, are located in the Southeast where they are especially vulnerable to heat waves. In part because the region's wind energy resource lags behind much of the nation, nuclear is seen as an attractive emissions-free alternative.
Nuclear accounts for about a quarter of the region's electrical generation, compared with 20 percent for the nation as a whole. As of March, the Nuclear Regulatory Commission had received 16 license applications for building new nuclear units in the Southeast. The projects closest to construction are units 3 and 4 of Southern Company's Vogtle plant in Burke County, Georgia.
Sara Barczak, a program director for the Knoxville, Tenn.-based Southern Alliance for Clean Energy, said climate effects must figure into utilities' decisions to build new nuclear facilities, especially since it can cost up to $10 billion per reactor and each is designed to last for 60 years.
Climate change studies published in research journals such as Science and the Journal of Climate project longer and more intense heat waves over the next century worldwide, adding constraints to water-intensive power systems.
According to the U.S. Geological Survey, thermoelectric generation in the U.S. from coal, natural gas and nuclear withdraws more freshwater per year than the entire agricultural sector. Overall, nuclear plants consume up to 25 percent more water than fossil fuel plants.
David Lochbaum, director of the Nuclear Safety Project at UCS, said regulators should be more forward-thinking in siting decisions.
When deciding where to build new reactors, officials "look backwards for [records of] earthquakes and rainfall patterns but never look forward," he said. "It's always struck me as ironic that the industry touts nuclear as part of the solution for climate change but they don't consider climate change" in their planning.
Ray Golden, a spokesperson for TVA, said the last time the utility licensed a nuclear plant was in the 1980s, at a time when climate science was "less" available.
TVA has no plans to expand its nuclear fleet beyond its three existing plants. But if it did, Golden said, it would "be looking at all scientific evidence as part of the environmental review, including the potential that global warming might impact river temperatures in the future."