Ukraine plant temporarily loses main power supply

May 28, 2024, 7:00AMNuclear News

Ukraine’s Zaporizhzhia nuclear power plant temporarily lost the connection to its sole remaining 750 kilovolt (kV) off-site power line last week due to a reported short circuit, leaving it reliant on a single backup line for more than three hours.

That was the report from International Atomic Energy Agency director general Rafael Mariano Grossi last week as the agency continues to monitor and share safety concerns regarding the nuclear plant that has been under Russian control since March 2022, shortly after Russia’s invasion of Ukraine.

“For Europe’s largest nuclear power plant to depend on one or two power lines is a deep source of concern and clearly not sustainable. Our concerns also extend to the operating [nuclear power plants] across Ukraine, where a disruption to off-site power supplies could have very serious implications for nuclear safety,” Grossi said.

“For the outside world, the situation at the Zaporizhzhia nuclear power plant may have appeared relatively calm in recent weeks, since the drone attacks on the site confirmed by our experts in mid-April. But this is not the way we see the situation on the ground. The stark reality is one of constant danger. The nuclear safety and security situation at the site remains extremely vulnerable,” he added.

The incident: Zaporizhzhia’s sole remaining 750kV Dniprovska line occurred at 1:31 p.m. local time on May 23, about 6 kilometers away from the plant’s 750 kV open switchyard, in Russian-controlled territory. Plant workers informed the IAEA experts stationed at the site that it was caused by a short circuit but did not provide further details. The line was reconnected at 4:49 p.m. local time.

During the time the 750 kV line was disconnected, Zaporizhzhia received external electricity from its only 330 kV backup line. Previously the plant had four 750 kV lines and six 330 kV lines available.

Earlier last week, plant officials also informed the IAEA of a drone attack on a transport workshop in the nearby industrial area, reportedly causing some damage but no casualties, Grossi said. The IAEA team stationed at the site also have reported hearing continued explosions at various distances from the plant during the past week.

Background: The plant stopped producing electricity in September 2022. All six units are now in cold shutdown—therefore not generating heat or steam—which required the site to start using two of the nine mobile diesel boilers to generate hot water for its own needs.

The IAEA team continue to monitor maintenance activities at the site and training drills. Maintenance on parts of the safety systems of Unit 1 resumed this past week after being postponed in March. There is also maintenance work being performed on the Unit 2 main transformer.

The team also observed successful performance of routine testing of an emergency diesel generator for Unit 1, which is a critical piece of equipment as off-site power access continues to be an area of concern.

Security concerns elsewhere: This loss of power event at Zaporizhzhia amplifies concerns around attacks on the electrical power infrastructure elsewhere in Ukraine. At the Rivne plant in western Ukraine, an IAEA team reported that Russian attacks on the power infrastructure elsewhere in the country resulted in instability for that plant’s backup power lines.

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