Ukraine’s Zaporizhzhya Nuclear Power Plant lost all off-site power overnight Dec. 3 and temporarily relied on emergency diesel generators for the electricity needed to cool its reactors, according to the International Atomic Energy Agency.
The main power line – the only remaining main power line at the ZNPP compared to the four it had before the war – was re-connected shortly after 8 a.m. the following day. After the re-connection, the eight diesel generators that were operating were gradually shut down with external power now coming from the 750 kV line with no external backup, IAEA Director General Rafael Mariano Grossi said.
It was the ZNPP’s first complete external power outage since May, Grossi said.
The ZNPP lost the connection to both of its external power lines – the eighth time that Europe’s largest nuclear power plant suffered a complete off-site power outage since Russia’s all-out invasion in February 2022.
“The most recent external power outage is yet another reminder about the precarious nuclear safety and security situation at the plant, which can be affected by events far away from the site itself,” Grossi said. “The IAEA continues to do everything it can to help prevent a nuclear accident. I also call on all parties not to take any action that could further endanger the plant.”
The operation of the four main coolant pumps of one of the plant’s six reactors was interrupted by the power outage. That unit is being brought from semi-hot shutdown back to hot shutdown to produce heating and steam for the site and the nearby town of Enerhodar, where most plant staff live, the IAEA said. The other five reactors are in cold shutdown.
IAEA personnel at the site reported that the plant’s connection to its sole backup 330-kilovolt power line was cut around 10:30 p.m. local time on Dec. 2 due to an external grid fault. About five hours later the plant lost its main 750-kilovolt line, the agency said. The cause appeared in the external power grid, away from the nuclear plant.
When the power was cut, the site’s 20 diesel generators automatically kicked on. Plant staff, which are independent of the IAEA team on the ground, were eventually able to run just eight diesel generators, to enough power for the plant’s six reactors – all of which are shut down – for essential cooling.
