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The risks of the Zaporizhzhia power plant for Ukraine, explained

The best and largest nuclear power plant in Europe is also one of its most vulnerable.



There is a standoff between Russian and Ukrainian forces at the Zaporizhzhia nuclear power plant, which has sent chills down spines across Europe and brought back memories of the Chernobyl disaster. Families are fleeing the area in fear of a nuclear catastrophe as a result of shelling near the strategically located plant, which both sides blame on the other.

The Zaporizhzhia Nuclear Power Plant is the largest in Europe and supplies power to Ukraine and other European countries. Due to its strategic location on the Dnipro River, the plant has been under Russian control since March. Its Ukrainian operators continue to ensure the plant’s security and day-to-day operations, despite being under intense pressure from Russian forces, who have allegedly converted the plant into a military installation.

The potential for a serious and widespread nuclear disaster has led to calls for the immediate demilitarization of the plant from multiple parties, including UN Secretary General Antonio Guterres. The deputy director of the information and press department at the Russian foreign ministry, Ivan Nechayev, argued that a reduction in tensions “will make the plant even more vulnerable.” According to the TASS state news agency, Russian officials wrote to the United Nations on Thursday claiming that Ukraine was planning a “provocation” there on Friday. Ukraine reportedly responded by saying that Russia planned to disconnect the plant from the Ukrainian grid and connect it to Russia’s power grid. Both of these things have yet to happen.

Considering the lingering effects of the Chernobyl nuclear disaster from 1986, it is not surprising that Zaporizhzhia’s security is a source of concern around the world. And that worry isn’t unwarranted, as problems at the plant are a real possibility, ranging from alarming to catastrophic.

The loss of electricity poses the greatest threat to Zaporizhzhia.

However, “the likelihood of an intentional attack on the [plant] that leads to a major nuclear disaster is low,” Ivanka Barzashka, founder and co-director of the King’s Wargaming Network at King’s College London, told Vox via email. Given the proximity of Russian forces and population to the reactor, “Moscow would have a lot to lose and nothing to gain from such an outcome.” The plant’s reinforced concrete construction means it can withstand armed assault.

Matthew Bunn, James R. Schlesinger professor of the practice of energy, national security, and foreign policy at Harvard’s Kennedy School of Government, says that the real risks to the facility are more likely to be due to human error, accidental shelling, or a lack of electricity to cool the nuclear material.

According to Bunn, “the cooling of a nuclear power plant” is the biggest issue. The reactor core, spent fuel, and spent fuel pool should all be submerged in water and kept at a constant temperature in order to prevent any sort of meltdown at a nuclear power plant. Electricity for this cooling procedure is currently supplied by Ukraine’s external power grid. For instance, even though the reactor at the Fukushima nuclear plant in Japan had undergone emergency shutdown, the disaster that ensued because of a tsunami that cut off-site electricity to the plant and destroyed the generators rendered cooling the facility impossible.

Bunn told Vox that several of these lines have been severed, increasing the likelihood that Zaporizhzhia will have to rely on diesel-powered generators to support the cooling process. Given that Russian forces have allegedly been siphoning off the fuel for their own purposes, Bunn claims it is unknown how much fuel is left in those generators. Diesel, he explained, is “extremely valuable” in conflict zones. They say there’s diesel for days at the site, but we have no idea if that’s still the case. Reuters cites a report from the Ukrainian nuclear agency Energoatom from Friday, in which it was stated that Russian forces were looking for diesel to fuel the generators in the event of a power outage.

At worst, the plant’s power would go out and the pumps that keep water circulating through the reactor core and spent fuel pool would stop working. In Bunn’s estimation, “within hours,” the reactor core would be exposed due to the heat generated by the core and the spent fuel, which would boil the surrounding water until it evaporated. When that happens, the fuel will begin to melt. The fuel still generates a lot of heat from the radioactive decay of the split atoms, what are called the fission products in the fuel, even after the reactor has been shut down, earning the nickname “the fire that doesn’t go out.”

Despite this, Bunn’s “very very worst case” of a spent fuel fire is not likely to occur in Zaporizhzhia because there is not as much spent fuel there as there is at other sites; Zaporizhzhia used to ship spent fuel to Russia for storage and reprocessing there. That, he explained, is rare and requires “pretty closely packed” and “really hot” fuel that has been recently removed from the reactor.

Regardless of whether or not the power goes out, shelling could still disrupt the cooling process by causing water to leak out of the plant. Unfortunately, the plant has been damaged by the ongoing shelling, especially in the area around a substation, which led to the shutdown of one of the only two operational power lines on August 5.

Bunn told Vox that people are the most important factor in ensuring the plant’s security. Bunn claimed that the Ukrainian operators had been forced to continue their work for several months while under Russian gunpoint. “[They are] under tremendous emotional strain; many have relocated their families, and they are physically and emotionally spent. It’s always possible for mistakes to be made in the plant’s operation with people around. They have been performing heroically, but mistakes are inevitable when people are under pressure.

Just how significant is Zaporizhzhia?

The president of Ukraine, Volodymyr Zalenskyy, has referred to this tactic as “blackmail with radiation,” accusing Russia of using the threat of a nuclear disaster to stop Ukrainian forces from retaking the surrounding territory. Russian military vehicles were spotted in the turbine hall of the plant on Friday, and Energoatom chief Petro Kotin estimated that there are about 500 Russian soldiers present. Russia is launching attacks from the reactor, Bunn said, “possibly in violation of international law,” because the Russians know that the Ukrainians won’t fire at the reactor due to the extreme danger it poses to civilians. That’s outrageous, against the law, and completely irresponsible.

Russia has thus far ignored calls to demilitarize the plant and establish a safety zone around it, claiming that the presence of Russian troops there is sufficient protection against nuclear disaster.

It has been argued by Bunn and Nikolai Steinberg, a former chief engineer at Chernobyl, that the reactor should have been shut down months ago. Steinberg has even gone so far as to call the plant’s continued operation a “crime.” Yet, as Bunn put it, “they have remained operating because they are very, very important to the Ukrainian grid, and the Ukrainian government has been making money selling electricity from these reactors into the European market.”

It would have been difficult for energy security in Ukraine and Europe, but shutting down the plant at the start of the invasion would have allowed the reactors to cool, decreasing the likelihood of a nuclear disaster. Russian officials were hesitant to shut down the plant for fear of being unable to restart it if the war were to escalate, but the country reportedly has trouble finding operators who are both technically competent and willing to work in a conflict zone.

As Bunn put it, “I fear that Russia is not going to agree to the sensible UN proposal for a demilitarized zone at this site,” due to the site’s significance.

Is there anything we can do right now to prepare for potential disasters?

In the event of an accident at Zaporizhzhia, experts in Ukraine have warned of potentially catastrophic consequences, including radioactive leakage that could kill thousands, displace two million people, and pollute an area three times the size of Ukraine with radiation. According to Olena Pareniuk, a senior nuclear safety expert at the Ukrainian National Academy of Sciences, a nuclear accident in Zaporizhzhia could be the first magnitude-8 nuclear accident; for reference, the meltdowns at Chernobyl and Fukushima were rated magnitude-7 on the International Nuclear and Radiological Event Scale.

Bunn stated that the most urgent action is to stop the shelling, as turning off the reactors does not appear to be an option at this time. He said, “It’s not a good idea to run reactors in a war zone.” To proceed, the plant must be opened to a team of inspectors from the International Atomic Energy Agency (IAEA). Guterres and French President Emmanuel Macron are among those urging Russia to do so; Macron announced on Friday that Russian President Vladimir Putin agreed to let a team in, but he gave no further details.

Since combatants are unlikely to risk harming civilians on such a high-profile mission, the sending of the IAEA monitoring team is likely to halt hostilities and give the experts time to collect objective data on the plant’s and workers’ conditions.

However, Bunn argues that this is not a long-term solution because “the IAEA just isn’t set up for sending teams that just stay for months at a time.” Sending in monitoring teams once a month is “the most plausible scenario there is,” he said. This would involve the International Atomic Energy Agency (IAEA) making arrangements for people and equipment to come in and out more frequently.

The status of nuclear facilities during wartime requires improved international treaties and agreements. For instance, in 2019, the Russians withdrew from a 1977 amendment to the Geneva protocol that forbade attacks on civilian nuclear power plants and other infrastructure.

Optimally, Bunn said, the treaty between India and Pakistan would be adopted more widely. In it, the two countries vowed not to attack each other’s nuclear facilities and now specify which facilities are off-limits once a year.

One major reason why we don’t have more agreements prohibiting attacks on nuclear power plants is because… Politics in the USA. Partly for nuclear nonproliferation reasons, the United States has wanted to keep the option of attacking nuclear reactors. Bunn stated that “it is not unusual for a state launching a nuclear weapons program to claim… that it is a civilian reactor,” when in reality it is a military reactor. The United States, for instance, considered attacking a North Korean reactor in 1994, knowing that doing so would contribute to weapons proliferation, but ultimately decided against it.

According to Bunn, the United States should at the very least agree with the stance that operational reactors under international monitoring should be shielded from attack. Current conditions “make it very difficult for the United States to get up on a high horse about this situation,” as one analyst put it.