Russian president Vladimir Putin has told the United Nations atomic energy watchdog that Russia plans to restart Ukraine’s embattled Zaporizhzhia nuclear plant, currently occupied by Russian troops and technicians, fueling worries about a serious nuclear accident on the front lines of a grinding military conflict.

Тhe six-reactor plant, which is Europe’s largest, was absorbed into the war in March of 2022. The plant is now under Moscow’s control, guarded by Russian troops and surrounded by mines, artillery often whizzing overhead — and it has had several close brushes with possible catastrophe.

“Restarting the Zaporizhzhia plant in the current circumstances is a serious nuclear hazard and plans to do so cannot fail to worry the public as well as nuclear specialists, including those in the international community,” said Alexander Nikitin, a nuclear expert with Bellona.

Earlier this month, drones struck the reactor building of one of the plant’s nuclear power units, as well as the roof of a training center. Ukraine and Russia have traded blame over that incident, and it sparked an emergency meeting of the IAEA Board of Governors earlier this month.

Operations of the plant were taken over by Rosatom, Russia’s powerful state nuclear corporation, in October of 2022, to international condemnation. Russian security forces patrolling the complex have detained and, in many cases, tortured of workers, to quash staff dissent. 

The plans to restart the plant’s reactors were confirmed by Putin during a meeting he held in Sochi last month with Rafael Grossi, director general of the UN’s International Atomic Energy Agency, according to The Wall Street Journal and other outlets.

Russian officials have not yet publicized a timeline of how a restart of the plant would be achieved. Five of the plant’s six reactors are currently offline — a so-called cold shutdown. A sixth, in a hot shutdown, runs just warm enough to produce the steam the plant needs for basic safety processes. 

The IAEA has posted small rotating teams of experts at the plant, and European diplomats familiar with their observations told the Wall Street Journal that Russia intends to bring the plant back online this year. The goal, the diplomats said, would be to restart at least one reactor by December — the 40^th anniversary of the Zaporizhzhia plant’s connection to the Soviet grid in 1984.

Any reactor restart at the Zaporizhzhia plant — which, prior to its seizure by Russian forces provided a fifth of Ukraine’s electricity — would present huge technical challenges, said Dmitry Gorchakov, another of Bellona’s nuclear experts.

For one, the massive outflow of Ukrainian technicians since the Russian seizure has slashed staff numbers from 11,000 before the war to a skeleton crew of about 3,000. Rosatom has attempted to make up for these reductions by importing its own nuclear workers from Russian plants.

But since 1991, when the Soviet collapse left Ukraine as an independent country, the enormous Soviet-built complex has undergone a profound westernization and now runs on European Union-funded computer systems as well as — more recently — reactor fuel from the US-based Westinghouse Corporation.

These conversions baffle Russian staff who are used to Soviet designs, making any reactor restarts an unsafe proposition, many Ukrainians who have worked at the plant have told Western media.

To bring any reactors back online, their core temperatures would have to be raised hundreds of degrees and a scare supply of technicians would have to check a maze of pipes and pumps for leaks. So dwindled are the personnel numbers that as few as a single technician might oversee an entire reactor control room, a report by the US Department of Energy said.

The report added that Russian staff at the plant are underqualified to operate Ukrainian variants of the Russian-designed VVER-type reactors that make up the Zaporizhzhia plant.

“Learning to operate such different reactors requires lengthy study with qualified instructors and representative simulators, which Russia has not been able to meaningfully provide,” said the report.

Bellona’s Nikitin added that water supplies from the Dnipro River could be challenging to come by following last year’s Russian attack on the Khakhovka Dam complex, which feeds some of the reservoirs that cool the Zaporizhzhia plant.

Another major question, says Bellona’s Gorchakov, is where any electricity produced by a restarted Zaporizhzhia plant would go.

“They won’t be launching reactors just to send electricity to Ukraine,’ he said. Instead, Russian technicians would reroute the plant’s power production to the Russian grid — a tedious and technically demanding process in the midst of a full-blown military conflagration.

And this, he added, would further fan the flames of Russian propaganda.

“The reconnection to the Russian grid may be an important moment — if not the goal itself for Russia at this stage — because if Ukraine attempts to obstruct this process by attacking substations and networks in the occupied territory, which is not difficult in military terms, Russia will accuse Ukraine of threatening the security of plant because they are trying to disrupt energy supply,” he said.

“The launch of reactors may then simply worsen the situation and fix it in a more dangerous and less advantageous state for Ukraine,” he added.