Zaporizhzhia: Ukraine’s largest nuclear power plant is under threat. But experts say a Chernobyl-sized disaster is unlikely

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Nuclear experts are keen to defuse some of the most alarmist warnings, explaining that the main threat is closest to the plant itself and does not warrant Europe-wide alerts. Experts are particularly wary of any comparison to the Chernobyl disaster, a repeat of which is incredibly unlikely, they said.

“It is unlikely that this plant will be damaged,” Leon Cizelj, president of the European Nuclear Society, told CNN. “In the very unlikely event that this happens, the radioactive problem will primarily affect Ukrainians who live nearby,” rather than spreading across Eastern Europe as was the case with Chernobyl, he said. he declares.

“If we were to use past experience, Fukushima might be a worst-case scenario comparison,” Cizelj added, referring to the severe but more localized Japanese factory collapse in 2011. The most urgent dangers would be faced by Ukrainians living near the plant, which is on the banks of the Dnipro river, south of the city of Zaporizhzhia, and by Ukrainian personnel still working there.

Here’s what you need to know about the clashes at the Zaporizhzhia nuclear power plant and what their implications might be.

What’s going on at the Zaporizhzhia plant?

The fire at the Zaporizhzhia plant in recent weeks has damaged a dry storage facility – where spent nuclear fuel drums are kept at the plant – as well as radiation monitoring detectors, according to Energoatom, Ukraine’s nuclear power company.

On August 5, several explosions near the electrical panel caused a power outage and a reactor was disconnected from the power grid, said the head of the United Nations’ International Atomic Energy Agency (IAEA).

Rafael Mariano Grossi told the UN Security Council that the situation had deteriorated “to the point of being very alarming”.

Kyiv has repeatedly accused Russian forces of stockpiling heavy weapons inside the complex and using them as cover to launch attacks, knowing that Ukraine cannot retaliate without risking hitting one of the six reactors of the central. Moscow, meanwhile, claimed Ukrainian troops were targeting the site. Both sides attempted to point fingers at the other for threatening nuclear terrorism.

Calls are mounting for an IAEA mission to be allowed to visit the complex. But the fighting continued despite the concern.

On Tuesday, Ukrainian authorities said the town of Nikopol, across the Dnipro River from the plant, had again come under rocket fire.

“The shelling threatened the safety of operators working at the site, and it was reported that one worker was hit by shrapnel and taken to hospital,” communications manager Henry Preston told CNN. at the London-based World Nuclear Association.

He called the professionalism of the workers under the occupation “remarkable” and the use of an operational power plant for military activities “inadmissible”.

Could Russia shut down the factory?

Ukraine’s state-owned nuclear power operator, Energoatom, claimed on Friday that Russian forces at the Zaporizhzhia nuclear power plant “plan to shut down working power units in the near future and disconnect them from communication lines. supplying the Ukrainian electricity system”.

“The plant is designed to be shut down and put in a cold state” if its operators decide to do so, former IAEA deputy director Bob Kelley told CNN. The Russians could alternatively “keep a unit running at partial power to power the plant itself.”

Shutting down the plant would increase pressure on parts of southern Ukraine, which could be left without power before winter.

But Kelley said Russia would be unlikely to completely abandon the plant. “It was a war prize they wanted. It’s very valuable,” he said.

Instead, Moscow would be expected to divert power generated in Zaporizhzhia to Russian-occupied parts of Ukraine, which Russian officials have openly said they intend to do, although no timetable for such action has been announced.

On Friday, UN Secretary-General António Guterres said the electricity produced at the plant belonged to Ukraine.

“Obviously, Zaporizhzhia’s electricity is Ukrainian electricity and it is necessary – especially during winter – for the Ukrainian people. And this principle must be fully respected,” António Guterres said during a visit. at the Ukrainian port of Odessa.

How secure are the plant’s nuclear reactors?

Modern nuclear power plants are extremely well reinforced to prevent damage from all kinds of attacks, such as earthquakes, and Zaporizhzhia is no exception.

“Like all nuclear power plants, Zaporizhzhia contains various redundant safety systems that under normal circumstances are very 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, only two of which are currently in operation, are protected by steel and concrete caissons several meters thick. “Random bombing can’t really destroy that, it would be really unlikely,” Cizelj said.

If the reactors were attacked with deliberate and targeted bombing, the risk would increase – but even that would require a “very, very skilled” operation, he said.

Although Ukraine is not a member of the European Union, Cizelj told CNN he expects Zaporizhzhia’s precautions to be “comparable” to those in EU countries, where power plants must comply with strict nuclear security rules.

The factory has been under Russian control since the early days of the war.

What’s the worst case scenario?

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 spray basin, a tank in which hot water from inside the plant is cooled. If these systems failed, the nuclear reactor would heat up rapidly, triggering nuclear meltdown.

That would be the worst-case scenario, experts said. But, while it would be disastrous locally, they explained it would not have a major impact on Europe more broadly.

“The main danger here is damage to the systems needed to cool the fuel in the reactor – the external power lines, the emergency diesel generators, the equipment to dissipate the heat from the reactor core,” Acton said.

“In times of war, repairing this equipment or implementing countermeasures could be impossible. In the worst case, the fuel could melt and release large amounts of radioactivity into the environment.”

The Ukrainian nuclear power plant facing

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, according to experts, he would not go far.

Energoatom chief Petro Kotin said a strike in early August was close to the treated fuel storage area. “It’s very dangerous, because the rockets hit 10-20 meters from the storage, but if they hit the containers with the treated fuel, it would be a radiological accident,” Kotin told Ukrainian television.

If one container is affected, “it will be a local accident in the territory of the factory and the neighboring territory. If it is two to three containers, the affected area will increase,” he said. -he adds.

How is Zaporizhzhia different from Chernobyl?

Shelling around Zaporizhzhia triggered warnings from another “Chernobyl” — the world’s worst nuclear disaster.

But there are many 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.

In 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 of this type of jet engines are much better,” Cizelj said. “If there was damage to these reactors, it would be much easier to shut them down.”

The scale of a hypothetical nuclear meltdown would also be much smaller than that of Chernobyl, experts have said. After the 1986 meltdown, radioactive fallout spread across much of the northern hemisphere, while some 150,000 square kilometers in Belarus, Russia and Ukraine were contaminated, according to the IAEA. This contamination has spread up to 500 kilometers north of the site.
Signs warn against entering the Red Forest around Chernobyl, which is one of the most contaminated nuclear sites on the planet.

Instead, experts suggest that the feasible worst-case scenario would be more like another, more recent disaster.

“Fukushima is a better analogy than Chernobyl,” Acton said. “In this case, evacuations might be necessary for tens of kilometers around the plant, especially downwind. In the midst of a war, these would be exceptionally dangerous.”

Any radioactive fallout would spread about 10 or 20 kilometers from Zaporizhzhia before ceasing to pose serious health risks, experts suggest.

“If someone was able to cause the reactors to melt down, (gases) could escape into the atmosphere and would travel with the wind until they were blown out of the atmosphere,” Cizelj said. . “With distance, dilution occurs – so very quickly the dilution becomes sufficient that the impact does not become very serious for the environment and for people’s health.”

But for residents of war-torn southern Ukraine, a nuclear disaster is not the most immediate danger. “If you compare it to the other risks they face, that risk is not very big,” he added.

CNN’s Eliza Mackintosh contributed reporting.

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