The Atlanta Journal-Constitution
Damage contained at nuclear plant
News of what Ukrainian officials said was an unprecedented attack on a nuclear power plant, the largest in Europe, sent shudders around the world. But a fire that broke out at the Zaporizhzhia site was eventually contained and the damage was unlikely to result in the kind of devastation seen in the last atomic disaster on Ukrainian soil, the 1986 meltdown at Chernobyl.
What happened?
Ukraine Foreign Minister Dmytro Kuleba wrote on Twitter early Friday that a fire had broken out at the Zaporizhzhia plant in southeastern Ukraine after Russian shelling overnight. Kuleba called on Russia’s military to halt firing immediately. The facility — near the city of Enerhodar, about 310 miles from Chernobyl — has a total capacity of 5.7 gigawatts, enough to power more than 4 million homes. Kuleba had initially warned that an explosion would be 10 times larger than Chernobyl. Emergency services said later they had extinguished the blaze and there were no casualties or any immediate risk to the reactors. Russian forces have since occupied the site, according to Ukrainian officials.
Is a disaster likely?
There’s little reason so far to think so. Ukraine told the International Atomic Energy Agency that the fire “has not affected ‘essential’ equipment,” and that there had been no change reported in radiation levels. The reactors are “being protected by robust containment structures” and are being safely shut down, U.S. Energy Secretary Jennifer Granholm said in a statement. She said the department had activated its Nuclear Incident Response Team.
How does the plant compare to Chernobyl?
Unlike Chernobyl, the six reactors at Zaporizhzhia are pressurized water reactors (950 MW VVER-320) built in the early 1980s. They have containment structures around the reactor to stop any release of radiation. “Chernobyl did not have a containment,” said Dale Klein, a former chairman of the U.S. Nuclear Regulatory Commission and a professor at the University of Texas at Austin. Unlike the damaged Fukushima plant in Japan, these VVER reactors have separate water circuits to cool the reactor and to produce steam, according to Tony Irwin, a nuclear power expert and honorary associate professor at Australian National University. They also have emergency core cooling systems and multiple injection systems to prevent a core melt, he said.
How strong are the containment structures?
The reactors are protected with thick metal-and-concrete shells — the head of Ukraine’s nuclear operator has said they are designed to withstand an aircraft crash. “Depending on what type of artillery shells they are firing, it is not likely they will break out the containment buildings,” Klein said. Nuclear plants are equipped with emergency response systems that should shut the reactors once they sense the vibrations from the attack, according to Mark Nelson, managing director of the Radiant Energy Fund. Even if those systems were damaged, the meltdown would likely be contained within the facility.
What about a meltdown?
If a nuclear fuel rod isn’t properly cooled and is exposed to air, it can quickly heat up, begin to melt and release radioactive gases, which is the phenomenon known as a meltdown. But as long as there is power — and backup diesel generators — to keep the fuel rods cool, it won’t spiral into a meltdown like the one that occurred at Fukushima in 2011, which didn’t have electricity for a prolonged period of time following an earthquake and tsunami. “Multiple backup cooling systems are available and operators have been trained to be able to withstand plausible situations that could occur under any abnormal situation,” said Lake Barrett, a former official at the U.S. NRC who was involved with the cleanup after a partial meltdown at the Three Mile Island nuclear power plant in the U.S. in 1979. “If there is no significant military damage to their multiple redundant safety systems, the reactors should remain in a safe stable state.”
What are the risks?
If Russian forces knocked out power at one of Ukraine’s 15 nuclear reactors and destroyed backup diesel generators, the plant operator may struggle to keep the fuel rods cooled. “My concern is that they hit the diesel storage for the diesel generators, and that will take out one of their backup power systems,” said Klein. If spent nuclear fuel is stored in pools on site, an attack might drain the cooling fluid and cause the fuel to melt, releasing large amounts of radioactivity, James Acton, co-director of the nuclear policy program at the Carnegie Endowment for International Peace, wrote in a note in February. And should fires that have broken out after shelling breach the containment structure surrounding pressurized water reactors, there could be a risk of radiation releasing out into the air, said Chris Gadomski, an analyst for Bloombergnef in New York. “If you damage the reactor’s core, you’ll have something that would be very unpleasant and similar in scope to Fukushima.”
Why such fear?
There’s never been a military attack on an operating nuclear plant, according to analysts. In the days before the incident, the IAEA had considered a 30-kilometer exclusion zone surrounding all of Ukraine’s reactors. Nuclear plants house incredibly dangerous radioactive material — even after 10 years of cooling, spent fuel can release 20 times the fatal dose of radiation in one hour.
In the 1986 accident at Chernobyl in Ukraine, then part of the former Soviet Union, 350,000 people had to be evacuated and dozens of workers died of radiation poisoning within weeks. It’s the only accident in the history of commercial nuclear power to cause fatalities from direct radiation exposure, and was the product of a severely flawed Soviet-era reactor design, combined with human error, Gadomski said. More than 30 years later, there are still reports of dangerously high levels of radiation there in locally produced milk, mushrooms and wild game.