Zelenskyy warns Russian drones endanger safety at Chernobyl and at Europe’s biggest nuclear plant

A view of the Zaporizhzhia Nuclear Power Station, in Enerhodar, Zaporizhzhia region, in territory under Russian military control, southeastern Ukraine, on May 1, 2022. (AP Photo)

KYIV, Ukraine -- Russia’s sustained bombardment of Ukraine’s power grid is deepening concerns about the safety of the country’s nuclear facilities after a drone knocked out power for more than three hours to the site of the 1986 Chernobyl nuclear disaster in northern Ukraine, officials said Thursday.

The drone strike adds to concerns raised more than a week ago when the Russian-occupied Zaporizhzhia nuclear power plant in southeastern Ukraine became disconnected from the power grid following attacks that each side has blamed on the other.

Both Chernobyl and Zaporizhzhia are not currently operational, but they require a constant power supply to run crucial cooling systems for spent fuel rods in order to avoid a potential nuclear incident.

A blackout also could blind radiation monitoring systems installed to boost security at Chernobyl and operated by the UN’s International Atomic Energy Agency.

“Russia is deliberately creating the threat of radiation incidents,” Ukraine President Volodymyr Zelenskyy said late Wednesday, criticizing the UN nuclear watchdog and its chief Rafael Mariano Grossi for what he described as weak responses to the danger.

“Every day of Russia’s war, every strike on our energy facilities, including those connected to nuclear safety, is a global threat,” he said. “Weak and half-measures will not work. Strong action is needed.”

Russian President Vladimir Putin rejected Ukrainian claims that Russia has been shelling the power lines around the Zaporizhzhia plant as “nonsense” and blamed Ukraine for attacking the Moscow-controlled plant, warning that Russia could respond in kind.

The war that followed Russia’s all-out invasion of its neighbour more than three years ago appears no closer to ending, despite months of U.S.-led peace efforts.

Drones overwhelm air defences

Zelenskyy said in his nightly video address that Russia launched over 20 Shahed drones against energy infrastructure in Slavutych, the city whose power supply services Chernobyl, the site of the world’s worst nuclear accident.

A wave of drones overwhelmed defences and caused a blackout Wednesday, he said, affecting the sarcophagus that prevents radioactive dust from escaping the destroyed fourth reactor and storage housing more than 3,000 tons of spent fuel. He did not provide details of how it was affected.

“The Russians could not have been unaware that a strike on Slavutych would have such consequences for Chernobyl,” Zelenskyy said.

Last February, a drone armed with a warhead hit Chernobyl’s protective outer shell, briefly starting a fire. Radiation levels there did not increase, officials said.

Europe’s biggest nuclear plant using diesel generators

The Zaporizhzhia plant, which is Europe’s biggest and one of the 10 biggest nuclear facilities in the world, has been disconnected from the grid for over a week.

It has repeatedly been caught in the crossfire during the war. Zelenskyy blamed Russian artillery for cutting the power line to the plant, but Putin mocked the claim, saying: “are we striking ourselves?”

He accused Ukraine of “playing a dangerous game” by attacking the plant, adding ominously: “People on the other side must understand that if they continue this dangerous game, they also have functioning nuclear power plants.”

“What would prevent us from responding in kind?” he added. “Let them think about it.”

The facility is using emergency diesel generators to run cooling systems for its six shutdown reactors and spent fuel.

The IAEA says the plant is not in immediate danger but wants it swiftly reconnected to the grid.

Ukraine’s Energy Ministry said the situation is unprecedented. “No nuclear power plant in the world has ever operated under such conditions, and it is impossible to make any reliable forecasts,” it said in a statement to The Associated Press.

Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists, an American nonprofit organization, said no nuclear plant was designed to be able to function safely for an extended period without access to stable off-site power.

“The situation at Zaporizhzhia is indeed extremely fragile and increasingly dire,” he told AP.

If power for cooling were disrupted to one or more of the units, it would be “several days or longer” before the reactor cores or spent fuel pools might start to release significant quantities of radioactive material, he said.

The U.S.-based Institute for the Study of War said Russia’s occupation of Zaporizhzhia has “significantly degraded” the security of the plant.

It claimed Wednesday that Moscow wants to integrate the plant into the Russian grid -- a move that will “exacerbate security risks, degrade Ukraine’s future power generation capacity, and serve as a tool that Russia can use to legitimize its occupation of Ukraine.”

Prisoner exchange

Russia and Ukraine exchanged hundreds of prisoners of war Thursday.

Zelenskyy said 185 military personal, most of whom had been in Russian captivity since 2022, and 20 civilians were returned home.

Since the war began, more than 7,000 Ukrainians have returned, Zelenskyy said on Telegram.

Russia’s Defence Ministry said 185 of its soldiers and 20 civilians returned.

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By Hanna Arhirova And Barry Hatton

Illia Novikov in Kyiv, Ukraine and Stephanie Liechtenstein in Vienna contributed to this story. Hatton reported from Lisbon, Portugal.

The Associated Press receives support for nuclear security coverage from the Carnegie Corporation of New York and Outrider Foundation. The AP is solely responsible for all content.