Key Points
- The IAEA said military activity damaged electrical substations in Ukraine, cutting off-site power to the Chornobyl Nuclear Power Plant and affecting power lines serving other nuclear facilities.
- The agency is monitoring nuclear safety risks as repeated attacks on Ukraine’s energy infrastructure increase reliance on backup systems at nuclear sites.
The International Atomic Energy Agency said on Tuesday that several Ukrainian electrical substations critical for nuclear safety were affected by widespread military activity, leading to a temporary loss of external power at the Chornobyl Nuclear Power Plant and disruptions to power lines serving other nuclear facilities.
IAEA Director General Rafael Grossi said that Chornobyl Nuclear Power Plant lost all off-site power earlier in the day, while transmission lines connected to other nuclear power plants across Ukraine were also impacted. He added that the agency is monitoring the situation to assess potential risks to nuclear safety.
“The IAEA is actively following developments in order to assess impact on nuclear safety,” Grossi said in a statement released by the agency.
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Ukrainian nuclear facilities rely on stable external power to maintain cooling systems, radiation monitoring, and other safety functions, even at sites that are no longer generating electricity. Chornobyl, which ceased power production in 2000, still requires constant electricity to operate safety systems for spent nuclear fuel storage and radiation control infrastructure.
According to Ukrainian officials, backup diesel generators were activated at Chornobyl after the power loss, ensuring that critical systems remained operational. No increase in radiation levels was reported following the outage, and the site’s safety systems continued functioning as designed.
The latest power disruptions come amid continued Russian military operations across Ukraine’s energy infrastructure, which has repeatedly been targeted since the start of the full-scale invasion. Electrical substations, transmission lines, and power generation facilities have been damaged in previous attacks, complicating efforts to maintain stable electricity supplies during winter conditions.
The IAEA has maintained a permanent presence in Ukraine since 2022, with inspectors deployed at all operating nuclear power plants and at the Chornobyl site. The agency has repeatedly warned that sustained pressure on the power grid increases the risk of safety incidents, particularly if backup systems are forced to operate for extended periods.
The situation at Chornobyl carries additional sensitivity due to the site’s history and remaining hazards. In February 2025, Russian forces carried out a drone attack on the Chornobyl Nuclear Power Plant in the Kyiv region, striking the New Safe Confinement structure that covers Reactor Unit 4, which was destroyed in the 1986 accident. Ukrainian authorities later confirmed that the impact damaged parts of the protective structure.
Following technical inspections, Ukrainian specialists concluded that the confinement could no longer fully perform its primary function of isolating radioactive material from the environment. The structure, built with international funding and completed in 2016, was designed to prevent the release of radioactive dust and to allow the eventual dismantling of the destroyed reactor. Since the attack, the site has remained under enhanced monitoring by Ukrainian regulators and international partners.
The IAEA has previously described any military activity near nuclear facilities as unacceptable and incompatible with nuclear safety principles. Grossi has repeatedly called for restraint and for the protection of nuclear installations, warning that damage to power supplies or safety systems could lead to serious consequences even without direct hits to reactors.
Ukraine currently operates three nuclear power plants—Rivne, Khmelnytskyi, and South Ukraine—while the Zaporizhzhia Nuclear Power Plant remains under Russian occupation and is not producing electricity. All Ukrainian nuclear facilities depend on a network of high-voltage transmission lines to maintain safe operations, making them vulnerable to disruptions far from the plant sites themselves.
In recent months, Ukrainian energy operators have worked to reinforce grid resilience and expand backup generation at nuclear facilities, but officials say repeated attacks continue to test those measures. The IAEA has stated that it remains in close contact with Ukrainian authorities and grid operators to verify the status of safety systems and power restoration efforts.
