Ukraine’s Zaphorizhzhia nuclear plant loses connection to last backup power line

Ukraine’s Zaporizhzhia nuclear power plant has lost connection to its last external power backup line, UN’s nuclear agency chief Rafael Grossi said on Wednesday.

The loss of the last power backup to keep the nuclear facility running is “once again underlining the fragile nuclear safety and security situation at the site”, the International Atomic Energy Agency director general said.

He said IAEA officials present at the Zaporizhzhia nuclear power plant, which sits in Russia-occupied territory, were informed that the 330 kilovolt (kV) power line was disconnected at 2.04pm local time on Tuesday.

A team of experts present at the site were told the disconnection occurred “due to a problem which occurred on the other side of the Dnipro river, some 13.5km away from the 330 kV switchyard, which supplies back-up power to the site”.

“The cause of the disconnection was not immediately known, the ZNPP said, adding it had been informed by the Ukrainian grid operator that work on the line was under way,” the statement said.

Before Russia invaded Ukraine in February 2024, the plant had four 750kV lines and six 330kV lines available to keep the nuclear facility running.

There are no longer backup options for off-site power.

Any disconnection of power or damage to the electricity lines to Zaporizhzhia can threaten the highly reactive reactors and its other essential functions which need electricity to cool them down, even when all reactor units have been shut down.

“The ZNPP is still receiving the electricity it needs from its only 750 kV line, but the loss of the 330 kV line means the plant currently has no back-up options available for off-site power,” the IAEA said.

Mr Grossi said the “extremely vulnerable off-site power situation continues to pose significant safety and security challenges for this major nuclear facility”.

“Even though the main power line remains in operation, the lack of back-up power demonstrates that the nuclear safety and security situation at the plant remains precarious,” he said.

The ZNPP has suffered complete loss of off-site power since August 2022 on at least eight events, relying temporarily on emergency diesel generators.

Fears over the “fragile” security situation at one of the world’s biggest atomic power plants has been a feature throughout Vladimir Putin’s invasion of Ukraine.

The IAEA has expressed alarm about the facility amid fears of a potential nuclear catastrophe. The plant has repeatedly been caught in the crossfire since Russia launched its full-scale invasion of Ukraine on 24 February in 2022, and seized the facility within days of their military offensive.

Of particular concern is the Russian decision to block access for Ukrainian staff employed by Kyiv’s national operator, who refused to sign contracts with the Russian operator at the site.

The staff working at the plant now are former Energoatom workers who adopted Russian citizenship and signed new contracts with Russia’s operator at the site.