A Russian serviceman guards in an area of the Zaporizhzhia...

A Russian serviceman guards in an area of the Zaporizhzhia Nuclear Power Station in territory under Russian military control, southeastern Ukraine on May 1. Credit: AP

KYIV, Ukraine — Fears mounted Tuesday over Europe's largest nuclear plant as shelling around it continued, a day after it was again knocked off Ukraine's electrical grid and put in the precarious position of relying on its own power to run its safety systems.

Repeated warnings from world leaders that the fighting around the Zaporizhzhia plant could lead to a nuclear catastrophe have done little to stem the hostilities. Russian-installed officials accused Ukrainian forces of shelling Enerhodar, the city where the plant is situated, hours after the Ukrainians said Kremlin forces attacked a city across the river.

The Ukrainian mayor of Enerhodar, Dmytro Orlov, reported a powerful blast in the city around midday. The explosion left the city of 53,000 cut off from its power and water supplies. It wasn’t immediately clear what caused the blast.

Both sides have traded accusations of attacks on the plant since Russian troops seized it early in the war. With the danger rising, a team from the U.N.'s International Atomic Energy Agency finally traveled to the plant last week, and on Tuesday, inspectors were expected to report what they found to the U.N. Security Council.

Two inspectors remained at the plant, which is run by Ukrainian workers, and Ukrainian presidential adviser Mykhailo Podolyak applauded that decision.

“There are Russian troops now who don’t understand what’s happening, don’t assess the risks correctly,” Podolyak said. “There is a number of our workers there, who need some kind of protection, people from the international community standing by their side and telling (Russian troops): ‘Don’t touch these people, let them work.’”

But the IAEA visit appeared to have done little to lessen the risks. On Monday, the IAEA said Ukrainian authorities reported that the plant’s last transmission line was disconnected to allow workers to put out a fire caused by shelling.

Ukrainian Energy Minister Herman Halushchenko told Ukrainian television: “Any repairs are impossible at this point — there are ongoing hostilities around the plant.”

In the meantime, the plant’s only remaining operational reactor will “generate the power the plant needs for its safety and other functions,” the IAEA said. The plant needs power to run the cooling systems for its reactors and spent fuel and avoid a meltdown.

Mycle Schneider, an independent analyst in Canada on nuclear energy, said that means the plant was probably functioning in “island mode,” or producing electricity just for its own operations.

“Island mode is a very shaky, unstable and unreliable way to provide continuous power supply to a nuclear plant,” Schneider said.

It was just the latest incident to fuel fears of a nuclear disaster in a country still haunted by the world's worst nuclear accident, at Chernobyl in 1986. Experts say the reactors at Zaporizhzhia are designed to withstand natural disasters and even plane crashes, but the unpredictable fighting has repeatedly threatened to disrupt critical cooling systems, raising the risk of a meltdown.

Ukrainian intelligence reported that residents of Enerhodar were fleeing the city out of fear. Ukraine’s Deputy Prime Minister Iryna Vereshchuk said Russia should organize safe corridors for women and children living nearby.

"People en masse are reaching out to us for help. They are trying to leave to the dangerous territory, but there are no corridors,” Vereshchuk told Ukrainian TV.

Russian-installed officials in the Zaporizhzhia region on Tuesday accused Ukrainian forces of shelling Enerhodar and damaging a power line close to the plant.

Meanwhile, Ukraine’s presidential office said Russian forces shelled residential buildings in Nikopol, a city across the Dnieper River from the plant. Two people were wounded and a school, a kindergarten and some 30 buildings were damaged, the office said.

Russian shelling elsewhere killed at least three civilians, the statement said.

In the southern Kherson region, occupied by the Russians since early on in the war, Ukrainian forces continued their counteroffensive. A pontoon bridge was blown up overnight and a command center was hit, as well as two checkpoints, Ukrainian authorities said.

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