The IAEA today secured the agreement of both the Russian Federation and Ukraine to implement a localized ceasefire enabling repairs to begin on the last remaining backup power line to Ukraine's Zaporizhzhya Nuclear Power Plant (ZNPP), IAEA Director General Rafeal Mariano Grossi confirmed.

Technicians from Ukraine's electrical grid operator are expected to begin repair work on the 330 kV line - damaged and disconnected as a result of military activity on 2 January - in the coming days. The disconnection has left Europe's largest NPP dependent on its sole functioning 750 kV main power line.

An IAEA team has departed Vienna to travel to the frontline in order to observe the repair works.

"The IAEA continues to work closely with both sides to ensure nuclear safety at the ZNPP and to prevent a nuclear accident during the conflict. This temporary ceasefire, the fourth we have negotiated, demonstrates the indispensable role that we continue to play", IAEA Director General Rafael Mariano Grossi said today.

The IAEA team based at the ZNPP this week assessed the actions taken by the plant to ensure nuclear safety during adverse weather conditions. During walkdowns, the team confirmed that winter protection measures are in place to prevent freezing of water in the groundwater wells, which supply cooling water for safety systems that cool the reactors and spent fuel pools. The ZNPP informed the team that the pumps operating in the unit pumping stations of the six shutdown reactors, would continue to work even if ice was to form on the surface of the inlet channel, and that currently no ice had been observed in that area.

Additional efforts against the freezing temperatures include temperature controls for local heating to ensure that the emergency diesel generators are ready to start and operate properly in case of another loss of off-site power event. The team continues to monitor the measures taken.

At Ukraine's Chornobyl Nuclear Power Plant (NPP) site, one power line was disconnected in the past week after military activity damaged an electrical substation critical to its power supply, a development that once again underscores the importance of reliable electrical grid infrastructure for nuclear safety, IAEA Director General Rafael Mariano Grossi said today.

Following damage to the substation, the Chornobyl NPP site continued to receive off-site power from other lines, with the disruption illustrating the essential role substations play in ensuring the continuous supply of electricity required to operate key safety systems.

The disconnection was one of several incidents this week in which military activity affected nuclear safety at Ukraine's nuclear facilities. Last weekend, one of Ukraine's three operating NPPs was also forced to temporarily reduce its power output after reported damage to the electrical infrastructure.

"A deterioration of Ukraine's power grid from persistent military activity has direct implications on the nuclear safety of its nuclear facilities," said Director General Grossi. "The IAEA will, as a priority, continue to assess the functionality of these critical substations."

Director General Grossi announced last week that the IAEA is preparing another expert mission to Ukraine's electrical substations amid ongoing strikes on the country's power infrastructure. These substations are essential for supplying electricity needed for reactor cooling systems and other key nuclear safety functions. The mission will assess 10 substations critical to nuclear safety, following up on some of those visited in December 2025 and examining additional sites not previously assessed.

IAEA teams reported military activities or air raid alarms at all five nuclear sites in Ukraine over the past week. The teams at the Chornobyl site and at the Khmelnitsky NPP were informed that military objects flying within five kilometers of the sites had been observed on 11 and 15 January, respectively. At ZNPP, the team continues to hear a large number of explosions, including some within the vicinity of the site. The team at the South Ukraine NPP has reported multiple air raid alarms each day over the past week and were informed that a military flying object had been observed approximately 10km from the site.

Related Resources

• Nuclear Safety, Security and Safeguards in Ukraine