As the world reflects a year after the Fukushima Daiichi nuclear disaster in Japan, nuclear energy experts are reevaluating safety issues in the United States.
A lengthy report released Thursday for the American Nuclear Society details lessons from Fukushima. The earthquake and tsunami that hit the facility in March of last year lead to the widespread release of radioactive contamination, forcing more than 100,000 people from their homes.
The report recommends a more "risk-informed approach" to emergency planning so that evacuation zone distances wouldn't be preassigned, says Michael Corradini, professor of nuclear engineering at the University of Wisconsin.
This would involve "doing analysis on possible accidents, possible scenarios and making the emergency planning zones more site-specific," he told CNN. The existing planning zones are secure, however, he said.
The question of what is the appropriate size for these emergency planning zones is a long-term issue into which the U.S. Nuclear Regulatory Commission is looking, said Scott Burnell, spokesman for the agency, told CNN. Burnell was not part of the American Nuclear Society committee.
There's a 10-mile zone around every reactor in which the public would be expected to take some sort of action if radioactive material were released from a plant, Burnell said.
Corradini and other committee members also recommended that the regulatory process be more informed by risk, considering how adequate the design bases are for withstanding such disasters as earthquakes, fires and floods.
But based work that the U.S. Nuclear Regulatory Commission has done researching potential accidents at one plant in Pennsylvania and another in Virginia, the conclusion is that "these events occur slowly enough that there’s ample time for people in the vicinity of the plant to either move away or take other protective actions, to the point that there would be no health effects from these incidents," Burnell said.
Mapping potential fallout
So what would a Fukushima-like disaster look like in the United States?
The National Resources Defense Council put out a mapping tool so that anyone can get a sense of where the U.S. nuclear power plants are and what the potential evacuation zones would look like.
Matthew McKinzie, senior scientist in NRDC’s nuclear program, put this map together. It shows 10-mile and 50-mile zones around existing plants. After the Fukushima disaster, the Nuclear Regulatory Commission issued a warning to U.S. citizens within 50 miles of the site.
For example, the Limerick Generating Station is within 50 miles of Philadelphia. "If there was a severe accident on the scale of Fukushima, you couldn’t rule out contamination in downtown Philadelphia," McKinzie said.
McKinzie and colleagues looked at the weather patterns from March 11 and 12, 2011, to determine what the radioactive plumes would have looked like at individual U.S. reactors if a disaster had occurred during that time.
But Burnell said the Nuclear Regulatory Commission feels this tool is not a realistic representation of the potential consequences of potential nuclear accidents in the U.S., given that such events would progress slowly, and that the agency's research has found that less radioactive material would be released into the air than previously thought.
How economics plays in
On a global scale, nuclear power took a hit in several countries after the Fukushima disaster.
Of Japan's 54 reactors, only two are still operating, and it's unknown whether the others will come back online, writes Peter Bradford, an adjunct professor at Vermont Law School, in the journal Nature.
Germany, Belgium and Switzerland have said they will close all of the reactors that they have and not build new ones. Italy closed its reactors after the world's worst nuclear disaster at Ukraine's Chernobyl facility in 1986. And depending on how elections go in France this year, it too may shut down some of its reactors.
Bradford says reactor construction in the U.S. has declined because of economic realities, not in response to safety concerns and overregulation after the 1979 accident at Three Mile Island in Pennsylvania. Construction in the U.S. and Western Europe dropped as "a result of the cost of building new plants and the refusal of investors to bear the risks of cancellations, cost overruns and the emergence of cheaper alternatives."
But Burnell points out that, of the 104 reactors operating today, slightly fewer than half of them were brought into use since Three Mile Island occurred.
New nuclear plants will generate electricity at 12 cents per kilowatt hour, compared with 3 to 11 cents per kilowatt hour for other low-carbon alternatives, according to Exelon, a large U.S. nuclear operator.
"If Exelon's predictions are correct, and if gas prices remain low, carbon prices would have to more than triple to make new nuclear look economical," Bradford writes.
Still, Corradini believes that in some areas of the country, nuclear power will continue to grow. He points to Georgia, where the Nuclear Regulatory Commission approved two new reactors at the Vogtle nuclear plant.
A need for more science
Helicopters dropped tons of seawater on Fukushima Daiichi to try to help cool the earthquake-stricken reactors.
But, at the end of the day, we don't actually know what happens, chemically speaking, when seawater mixes with damaged nuclear fuel, notes Notre Dame professor Peter Burns and his co-authors in an article in this week's journal Science.
It's difficult to model nuclear reactor core-melt accidents, and adding massive amounts of seawater only muddies such predictions. There has been study of the short-term effects of the damaged fuel - there's gaseous and other short-lived chemicals released - but there's still a lot to explore.
Over time, damaged nuclear fuel interacting with water and air may pose significant environmental risk, since radioactive chemicals may be released that have very long half-lives (meaning they will be around a long time before they decay).
"Fukushima Daiichi itself would provide a very instructive experiment if and when it becomes possible to retrieve and study the fuel," Burns and colleagues write.