Heat Waves and Nuclear Power — Part Two

Next week will mark the two month anniversary of the Japanese tsunami and the beginning of the Fukushima Daiichi nuclear emergency. Since then, there’s been considerable interest in U.S. nuclear power plants and whether nuclear is a safe and reasonable clean energy source for the future. The media's interest in nuclear energy stories has been further buoyed by the recent anniversary of the Chernobyl nuclear disaster (if you haven’t already seen it, you should take a look at our Chernobyl feature). 

Here at Climate Central, we’re interested in investigating ways in which climate change might affect both the safety and reliability of American power plants.

An image captured by NASA's Aqua satellite on May 3 shows the extent of flooding around Cairo, Ill., just south of where the Mississippi and Ohio Rivers merge. Credit: NASA

For example, in light of the immense flooding along the Ohio and Mississippi Rivers in the past few days, several coal-fired power plants were forced to shut down. Floods aren’t exactly a new kind of disaster, and even in the absence of long-term climate change, power plants located near river banks are inevitably threatened by high water at some point. But in the Upper Midwest, where the intensity of extreme rainfall events has been increasing for several decades, floods could become even more common, and some power plants will be at risk of being inundated more frequently.

None of the plants that that were forced to shut down this past week due to flooding were nuclear plants, but the Nuclear Regulatory Commission is currently reviewing applications for several new power plants that would be located on the banks of the Mississippi River.

In other news on the link between climate change and nuclear power, SolveClimate published a story today about how an increasing number of heat waves predicted for the U.S. (and the South, in particular) could decrease nuclear energy generation. This is similar to a story I wrote a few weeks ago, with a special focus on last summer’s shutdowns at the Tennessee Valley Authority’s (TVA) Browns Ferry nuclear power plant; nearly two months of above average hot weather forced the TVA to cut power generation in half at the plant, which cost customers millions of dollars.

Today’s new story, written by Lisa Song, illustrates how broad the heat wave problem could be for nuclear power plants in other parts of the country. She reports that, beyond the troubles at Browns Ferry, several nuclear plants in New Jersey, Pennsylvania, Illinois and Georgia all had to reduce generating capacity due to warm temperatures during 2010. And just as we reported, Song points out that the problem is only expected to become more common in the future because scientists expect that the number of heat waves and the length of the summer season will both increase in the coming decades.

Heat waves and warming river and lake water pose problems for nuclear plants because many of them use water from nearby sources to cool the plant. As the water cycles through the power plant, it gains heat, before being sent back into the body of water it came from. During heat waves, river and lake water can get very warm, and power plants begin discharging water that is above temperature thresholds set by environmental regulators (meant to keep very warm water from harming marine life).

Heat waves aren’t just a problem for nuclear power plants, by the way; they can also influence any power plant or industrial facility that draws in water for cooling purposes. But the problem is particularly germane to nuclear power, which typically requires more water for cooling per each unit of electricity generated than coal-fired power does.

So how is climate change being considered in the planning for current and future nuclear power plants in the U.S.? Song captures a quote from nuclear energy analyst David Lochbaum, of the Union of Concerned Scientists, that says it pretty well:

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.

I should also mention that last week the Browns Ferry nuclear power plant faced a much scarier incident when nearby powerlines were struck by tornadoes and severe storms. Tens of thousands of customers lost power, but there was no major safety threat to the nuclear reactors at the plant, according to the TVA. Nuclear power plants are reportedly built to withstand these kinds of sever storms, and scientists are unsure how tornado risk might be affected by climate change.

It's a different story for hurricanes, however, and nuclear power plants built along the coast. As sea level rises with warming global temperatures, hurricane storm surges are expected to increase, an issue that utilities may not be fully taking into consideration in safety assessements of nuclear plants.