Heat Waves Spotlight Nuclear Achilles Heel
August 9, 2011
Not even TVA can beat the heat.
On Wednesday, the utility had to bring a third reactor at Browns Ferry Nuclear Plant down to 50 percent power to avoid environmental sanctions because the water in the Tennessee River — where the plant’s cooling water is discharged — already was at 90 degrees.
“When the river’s ambient temperature reaches 90 degrees, we can’t add any heat to it,” said TVA’s nuclear spokesman Ray Golden.
Similar problems last summer forced the Tennessee Valley Authority to spent $50 million for replacement power, according to Golden. The extra expense translated to something between 50 cents and $1 on most electric bills several months later, officials have said.
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.
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.
Nuclear power is not alone in sucking tremendous amounts of water during operations - Power generated from thermal power plants – coal, natural gas and nuclear, withdraws more freshwater per year than the entire agricultural sector; with nuclear using the most.
Overheating occurs during the summer months, when outdoor water temperatures are already high. Environmental regulations prevent power plants from discharging the heated water back into the river when temperatures reach a certain point and could harm fish. When that happens, nuclear operators have to decrease their generating capacity.
These regulations vary from state to state. In Alabama, for instance, once the river hits 90 degrees Fahrenheit, power plants cannot discharge any water that’s warmer than the river’s ambient temperature, TVA’s Golden said.
With river water so warm, the nuclear plant couldn’t draw in as much water as usual to cool the facility’s three reactors, or else the water it pumped back into the river could be hot enough to harm the local ecosystem, says Golden. But for every day that the Browns Ferry plant ran at 50 percent of its maximum output, the TVA had to spent $1 million more than usual to purchase power from somewhere else, he says.
It’s not the first time high temperatures have affected the performance of the Browns Ferry plant, and extreme heat is a growing concern for power plant operators across the Southeast. While some nuclear plants can improve their cooling procedures to cope with the intake of warmer water, the upgrades can cost hundreds of millions of dollars and still don’t offer an indefinite defense against extreme heat. Because scientists say the Southeast (like many other parts of the world) can expect to see more frequent and intense heat waves by the end of this century, the problems for nuclear power and the people that rely on it for electricity may only be beginning.