Nuclear experts are keen to defuse some of the more alarmist warnings, explaining that the main threat is closer to the plant and does not warrant alerts across Europe. Experts are particularly wary of any comparison to the Chernobyl disaster, which is incredibly unlikely to happen again, they said.
“This plant is not very likely to be damaged,” Leon Cizelj, president of the European Nuclear Society, told CNN. “In the very unlikely event that it is, the radioactive problem would mainly affect the Ukrainians who live nearby,” rather than spreading throughout eastern Europe as was the case with Chernobyl, he said.
Here’s what you need to know about the clashes at the Zaporizhzhia nuclear plant and what its implications might be.
What is happening at the Zaporizhzhia plant?
On August 5, several explosions near the electrical panel caused a power outage and a reactor was disconnected from the power grid, the head of the United Nations International Atomic Energy Agency (IAEA) said.
Kyiv has repeatedly accused Russian forces of storing heavy weapons inside the complex and using it as cover to launch attacks, knowing Ukraine cannot return fire without risking hitting one of the plant’s six reactors. Meanwhile, Moscow has claimed that Ukrainian troops are attacking the site. Both sides have tried to point fingers at the other for threatening nuclear terrorism.
Calls are mounting for an IAEA mission to visit the complex. But the fight has continued despite the concern.
On Tuesday, Ukrainian authorities said the city of Nikopol, across the Dnipro River from the plant, had come under rocket fire again.
“The shelling has threatened the safety of operators working on the site, and there have been reports that one worker was hit by shrapnel and taken to hospital,” Henry Preston, communications manager for the World Nuclear Association, told CNN. based in London.
He called the professionalism of the workers under the occupation “remarkable” and the use of an operational power plant for military activities “inconceivable.”
Could Russia close the plant?
Ukraine’s state nuclear power operator Energoatom claimed on Friday that Russian forces at the Zaporizhzhia nuclear plant are “planning to stop operating power units in the near future and disconnect them from communication lines supplying power to the system.” ukrainian electrical
“The plant is designed to shut down and go cold” if its operators decide to do so, Bob Kelley, a former IAEA deputy director, told CNN. The Russians could alternatively “keep one unit running at partial power to supply the plant itself.”
Shutting down the plant would intensify pressure on parts of southern Ukraine, which could run out of power heading into winter.
But Kelley said Russia would be unlikely to abandon the plant entirely. “This was a prize of war they wanted. It’s very valuable,” she said.
Instead, Moscow is expected to divert electricity produced in Zaporizhzhia to Russian-occupied parts of Ukraine, which Russian officials have openly said they intend to do, though no timetable for such action has been announced.
United Nations Secretary-General António Guterres said on Friday that the electricity generated at the plant belongs to Ukraine.
“Obviously, electricity from Zaporizhzhia is Ukrainian electricity and it is necessary, especially during winter, for the Ukrainian people. And this principle must be fully respected,” Guterres said during a visit to the Ukrainian port of Odessa.
How safe are the plant’s nuclear reactors?
Modern nuclear power plants are extremely well-hardened to prevent damage from all kinds of attacks, such as earthquakes, and Zaporizhzhia is no exception.
“Like all nuclear power plants, Zaporizhzhia contains several redundant safety systems, which under normal circumstances are highly effective,” James Acton, co-director of the Nuclear Policy Program at the Carnegie Endowment for International Peace, told CNN.
“The problem is that nuclear power plants are not designed for war zones and under plausible circumstances all of these systems could fail,” he added.
The plant’s six reactors, of which only two are currently operational, are protected by a steel and concrete casing several meters thick. “Random bombing can’t really destroy this, it would be really unlikely,” Cizelj said.
If the reactors were attacked by deliberate and targeted bombing, the risk would increase, but even that would require a “very, very skillful” operation, he said.
Although Ukraine is not a member of the European Union, Cizelj told CNN he hoped Zaporizhzhia’s precautions would be “comparable” to those in EU countries, where plants must meet strict nuclear safety standards.
What is the worst case?
Nuclear power plants use a number of auxiliary safety systems, such as diesel generators and external grid connections, to keep the reactors cool. Zaporizhzhia also uses a sprinkler pond – a reservoir in which hot water from inside the plant is cooled. If those systems failed, the nuclear reactor would quickly heat up and cause a nuclear meltdown.
That would be the worst case scenario, experts said. But while it would be disastrous locally, they explained it wouldn’t have much of an impact on Europe more broadly.
“The main danger here is damage to the systems needed to keep the fuel in the reactor cold: external power lines, emergency diesel generators, equipment to dissipate heat from the reactor core,” Acton said.
“In a war, repairing this equipment or implementing countermeasures could be impossible. In the worst case, the fuel could melt and spread large amounts of radioactivity into the environment.”
An attack on structures used to store spent nuclear fuel (fuel that is removed after use in a reactor) also poses a risk, with the potential to release radioactive material into the surrounding area. But, experts said, it wouldn’t travel very far.
Energoatom boss Petro Kotin said a strike in early August was near the processed fuel storage area. “This is very dangerous, because the rockets fall at a distance of 10 to 20 meters from the storage, but if they had hit the containers with the processed fuel, it would be a radiation accident,” Kotin said on Ukrainian television.
If a container is hit, “it will be a local accident in the territory of the plant and nearby territory. If there are two or three containers, the affected area will increase,” he added.
How is Zaporizhzhia different from Chernobyl?
But there are numerous differences between the two Ukrainian power plants, and experts insist that a repeat of the 1986 cataclysm is essentially impossible.
The Chernobyl plant used Soviet-era graphite-moderated RBMK reactors, which lacked a modern containment structure: a concrete and steel dome designed to prevent any radiation release.
By contrast, each of the six reactors at the Zaporizhzhia facility are pressurized water reactors enclosed in a huge steel vessel, housed in a concrete containment building. The design is called VVER, the Russian acronym for water-water-energy reactor.
“The brakes on these types of reactors are much better,” Cizelj said. “If there was damage to these reactors, it would be much easier to shut them down.”
Instead, experts suggest that the worst case scenario would look more like another, more recent disaster.
“Fukushima is a better analogy than Chernobyl,” Acton said. “In this case, evacuations tens of kilometers around the plant may be required, especially downwind. In the middle of a war, they would be exceptionally dangerous.”
Any radioactive fallout would extend to within 10 to 20 kilometers of Zaporizhzhia before it ceased to pose serious health risks, experts suggest.
“If someone could cause the reactors to melt down, (the gases) could escape into the atmosphere and travel with the wind until they were removed from the atmosphere,” Cizelj said. “With distance, dilution happens, so very soon, the dilution becomes enough that the impact is not very serious for the environment and people’s health.”
But for people living in war-torn southern Ukraine, a nuclear disaster is not the most immediate danger. “If you compare it to the other risks they face, this risk is not very big,” he added.
CNN’s Eliza Mackintosh contributed reporting.