IAEA Brokers Ceasefire to Restore Backup Power at Zaporizhzhya Nuclear Plant

The 330-kilovolt backup line, damaged by military activity and offline since 2 January, was restored after Ukrainian technicians completed repairs on the frontline under IAEA supervision.

Ukraine’s Zaporizhzhya Nuclear Power Plant (ZNPP) has been reconnected to its last remaining backup power line following emergency repairs carried out under a temporary ceasefire negotiated by the International Atomic Energy Agency (IAEA), Director General Rafael Mariano Grossi announced.

The 330-kilovolt backup line, damaged by military activity and offline since 2 January, was restored after Ukrainian technicians completed repairs on the frontline under IAEA supervision. During the outage, Europe’s largest nuclear power plant relied solely on its 750-kV main power line to supply the off-site electricity required to run safety systems for cooling its six shut-down reactors and spent fuel pools.

“This was the fourth temporary ceasefire agreement we have negotiated between both sides, enabling five separate power-line repairs,” Grossi said. “Now that the site has regained connection to both off-site power lines, I once again call on all parties to adhere to the Five Concrete Principles to prevent a nuclear accident at the ZNPP.”

Repairs under fire, monitored by IAEA

The repair operation followed the clearance of unexploded ordnance at the site on Saturday. A specially deployed IAEA team monitored the work carried out on Sunday and Monday, underscoring the agency’s growing role as a de facto nuclear safety mediator amid active hostilities.

The IAEA team remains stationed at ZNPP and continues to assess risks heightened by winter conditions. With reactors shut down, residual heat generation is reduced, raising concerns that cooling water could freeze.

During inspections, IAEA experts initially observed ice formations in sprinkler ponds, but follow-up checks confirmed these had melted. All 11 groundwater wells supplying water to the cooling systems remain operational despite sub-zero temperatures.

Inspections and testing continue

IAEA specialists also conducted walkdowns of:

• Unit 4 reactor building and safety systems

• Turbine halls of Units 3 and 4 (with restricted access in some areas)

• Unit 6 electrical, instrumentation and control rooms

The team observed routine testing of an emergency diesel generator at Unit 3, a key backup safety system should off-site power be lost again.

Rising risks at other nuclear sites

Elsewhere in Ukraine, IAEA teams reported renewed military activity near nuclear facilities. Drones were observed near the South Ukraine NPP and the Chornobyl site, while attacks on critical infrastructure damaged a major substation, disrupting power lines supplying Chornobyl and one operating nuclear power plant.

At Chornobyl, multiple 750-kV and 330-kV lines were disconnected, forcing emergency diesel generators to activate several times to protect the New Safe Confinement and Interim Spent Fuel Storage Facility-2. Further power disruptions occurred on subsequent days.

An IAEA mission is set to deploy next week to assess the condition of Ukraine’s critical substations, which Grossi described as essential for nuclear safety.

“Reliable off-site power is a fundamental safety requirement,” he said. “Any damage to this infrastructure undermines nuclear safety and must be avoided.”

Ongoing international support

IAEA teams at the Chornobyl and Rivne nuclear plants completed safe staff rotations this week. The Agency also continued deliveries under its emergency assistance programme, supplying electric all-terrain vehicles for radiation protection teams and medical supplies for Chornobyl NPP staff.

These latest shipments bring the total IAEA support to 198 deliveries worth €21.9 million, funded by the United Kingdom and the European Union since the start of the conflict.