The Ukrainian electrical grid was again the target of military activity, leading to significant impacts to several regions of Ukraine and NPP operations, International Atomic Energy Agency (IAEA) Director General Rafael Mariano Grossi noted. Power lines linking Ukraine with neighbouring countries were disconnected, triggering a cascade of power lines being disconnected within Ukraine. As a result, a unit at one NPP disconnected from the grid due to fluctuations and automatically shutdown. Other units at other NPPs were forced to reduce power. The Chornobyl site experienced a complete loss of off‑site power and relied on its emergency diesel generators for approximately one hour.
“This latest grid event in Ukraine is a stark reminder of the ever-present risks to nuclear safety and security arising from deteriorating grid conditions. Extensive repairs are needed to improve the reliability of power supply to Ukrainian NPPs and to strengthen their resilience to further grid events,” Grossi said. “Once again, I call for maximum military restraint, as well as full observance of the Seven Indispensable Pillars to enable these essential repairs to take place.”
Amid increased military activity impacting the Ukrainian electrical grid, three IAEA teams are visiting 10 substations critical to nuclear safety and security in Ukraine. The objective of this two-week IAEA mission is to assess the continuing damage to the grid, review repair efforts and identify practical steps to strengthen the resilience of off-site power supplies to the country’s NPPs. One of the teams has also visited Kyiv, where they discussed further IAEA support to NPP operations under deteriorating grid conditions.
This is the second such mission in recent months. The previous mission took place in December 2025, which confirmed the effects of cumulative impacts on NPP operations and staff conditions.
IAEA said further evidence of decreasing grid stability within Ukraine was apparent at the Chornobyl NPP in late-January. The IAEA team was informed that the diesel generators for the site’s New Safe Confinement and the Interim Spent Nuclear Fuel Dry Storage Facility had unexpectedly started due to grid fluctuations. The diesel generators for both facilities were manually put in standby mode within minutes. “This further highlights the impact that military activity on the grid can have on safety systems,” Grossi said.
Over the past two weeks, IAEA teams at the Khmelnitsky and South Ukraine NPPs safely rotated.
Ukraine’s Energy Ministry said nuclear power output remains partly reduced. Work has continued to deal with the aftermath of two large-scale Russian attacks on Ukraine’s energy system over the past week. “Energy workers are doing everything possible to bring equipment damaged back into operation. Repair work is ongoing both at power plants and at high-voltage substations that ensure the output from nuclear power plants,” the Ministry noted.
Ukraine’s national grid operator Ukrenergo said that a large-scale Russian missile and drone attack on energy infrastructure in eight regions had forced all NPPs in Kyiv-controlled areas to sharply reduce their output. “As a result of missile strikes on key high-voltage substations that ensured the output of nuclear power units, all NPPs in the controlled territory were forced to be unloaded,” Ukrenergo said in a statement. The damage caused a significant power deficit in the national grid, prompting emergency blackouts and longer durations for scheduled hourly outages.
Repair work has begun in areas where security conditions allow, prioritising the restoration of electricity to critical infrastructure. Ukrenergo urged citizens to minimise use of energy-intensive appliances once power is restored to prevent overloading the weakened system.
