IAEA confirms backup onsite power sufficient for 20 days
Ukraine’s Russia-occupied Zaporizhzhia nuclear power station lost all off-site power yesterday, the tenth such incident since the start of the conflict in February 2022, the International Atomic Energy Agency (IAEA) said.
The plant, Europe’s largest, was disconnected from its last remaining 750 kV external power line at 16:56 local time on 23 September. The disconnection was confirmed by both the Zaporizhzhia plant operators and Ukraine’s regulatory authority.
The IAEA said emergency diesel generators started automatically to supply power, and the plant later confirmed that all available generator units had been activated.
The agency said Zaporizhzhia has been dependent on a single external line for nearly five months after losing its last 330 kV back-up. The plant last suffered a complete loss of off-site power on 4 July 2025, when it ran on diesel for almost four hours.
IAEA director-general Rafael Grossi described the situation as “deeply concerning,” warning that repeated power losses “pose a real risk to nuclear safety and increase the likelihood of a nuclear accident.”
The IAEA said fuel tanks for the generators had recently been replenished with supplies sufficient for about 20 days of operation in case of further losses. The agency’s onsite team is assessing the cause of the latest outage.
The six-unit Zaporizhzhia station fell under Russian military occupation in March 2022, days after the start of Russia’s incursion into Ukraine on 24 February.
All six units have been in cold shutdown mode since September 2022, but they still require a constant supply of electricity to cool residual reactor core activity and spent fuel pools.
The IAEA has repeatedly warned that the loss of off-site power lines remains one of the most serious risks to nuclear safety at the station.
Grossi has visited the facility several times and established a permanent IAEA support and assistance mission at the site in September 2022.
The agency continues to call for the establishment of a nuclear safety and security protection zone around the facility, warning that repeated shelling, loss of external power, and restrictions on staff access increase the risk of a nuclear accident.
