IAEA: Situation in Ukraine's power system at its worst since Sept 2024
The situation in the power system is now at its worst since September 2024, when the International Atomic Energy Agency (IAEA) began monitoring substations critical to nuclear safety and security in Ukraine, IAEA Director General Rafael Grossi has said in a statement on Saturday night following an assessment of the condition of these substations.
"The strikes on Ukraine’s electrical grid appear coordinated to maximize disruption, and their frequency and scope underscore that the overall stability of the grid is deteriorating rather than improving," Grossi said.
He again called for maximum military restraint.
"No one wants, or benefits from, a nuclear accident," the IAEA Director General added.
Grossi explained that the latest mission, conducted from December 1 to 12, 2025, included visits to more than ten substations – critical to ensuring nuclear safety by providing the NPP with the electricity needed to cool the reactor and other safety systems. The mission’s objective was to assess the damage, review repair work and identify practical steps to strengthen the resilience of the country’s external power sources.
The IAEA Director General said nuclear safety at the three operating nuclear power plants in Ukrainian-controlled territory remains under pressure due to ongoing military activity and related damage to the power transmission infrastructure. Over the past weekend, power outages caused power fluctuations and temporary outages of power lines at Khmelnytsky, Rivne and South Ukraine NPPs, he noted. He said that in several instances, the units were operating at reduced capacity to maintain grid stability and prevent equipment damage.
"Persistent instability in Ukraine’s electrical grid continues to undermine nuclear safety. Although backup systems have worked as designed, repeated losses of off-site power and limited redundancy increase risk and reinforce the need for reliable external power," Grossi said.
The IAEA team also confirmed that the ongoing and deliberate attacks on critical network infrastructure have had a cumulative impact on the operation of the nuclear power plant and the working conditions of the personnel. The power outages affect the towns where the plant’s personnel live, worsening living conditions and directly affecting the personnel through disruptions to electricity, heating and water supplies.
It also noted that Russian-occupied Zaporizhia Nuclear Power Plant (NPP) in Ukraine temporarily lost external power supply for the 12th time since the start of the full-scale aggression early on the morning of December 13, as both the main 750 kV Dniprovska main power line and the 330 kV Ferosplavna-1 backup power line were disconnected. All available emergency diesel generators automatically started up, providing continuous cooling and other important safety functions. Both external power lines feeding the plant – the largest in Europe – have since been reconnected, and the diesel generators have been returned to standby mode, the agency said. It also reported that on December 15, despite the fact that Zaporizhia NPP retained access to the two remaining external power lines, another incident highlighted the fragile situation with the plant’s nuclear safety. The transmission of electricity between Zaporizhia NPP distribution point and Zaporizhia Thermal Power Plant distribution point via an autotransformer became unavailable, significantly reducing the flexibility and robustness of the facility’s electrical configuration. Following an investigation by Zaporizhia NPP, damage to the power line between the autotransformer and Zaporizhia Thermal Power Plant distribution point was discovered, reportedly caused by military activity.
Zaporizhia NPP informed the IAEA team at the plant that access to the affected area could not be provided for security reasons. As of today, Zaporizhia NPP is still studying ways to repair the line.