Update 333 – IAEA Director General Statement on Situation in Ukraine

Ukraine's Zaporizhzhya Nuclear Power Plant (ZNPP) temporarily lost all off-site power for the 12th time since the start of the military conflict, following widespread military activity that disrupted the country's electrical grid on 13 December. This incident once again underscores the continued fragility of nuclear safety conditions amid the conflict, IAEA Director General Rafael Mariano Grossi said today.

In the early hours of 13 December, both the 750 kV Dniprovska main power line and the 330 kV Ferosplavna-1 backup power line were disconnected, resulting in a complete loss of off-site power for more than two hours. All available emergency diesel generators automatically started, ensuring continued cooling and other essential safety functions. Both external power lines supplying the plant - Europe's largest Nuclear Power Plant (NPP) - have since been reconnected and the diesel generators were returned to standby mode.

On 15 December, despite the ZNPP maintaining access to its two remaining external power lines, another incident highlighted the plant's fragile nuclear safety situation. Power transmission between the ZNPP switchyard and the Zaporizhzhya Thermal Power Plant (ZTPP) switchyard through the autotransformer became unavailable, significantly reducing flexibility and resilience of the site's electrical configuration. Following an investigation conducted by the ZNPP, damage to the transmission line was detected between the autotransformer and the ZTPP switchyard, reportedly due to military activity.

The ZNPP reported to the IAEA team at the plant that access to the affected area cannot be granted for security reasons. As of today, the ZNPP is still investigating ways to repair the line.

Separately, nuclear safety at Ukraine's three operating NPPs remains under pressure due to ongoing military activity and related damage to transmission infrastructure. Over the weekend, grid disruptions caused fluctuating power outputs and temporary disconnections of power lines at the Khmelnitsky, Rivne, and South Ukraine NPPs. In several instances, units operated at reduced capacity to maintain grid stability and prevent equipment damage. IAEA teams on site continue to monitor conditions closely and maintain regular communication with plant operators.

"Persistent instability in Ukraine's electrical grid continues to undermine nuclear safety," Director General Grossi said. "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."

Over the past two weeks, an IAEA team assessing the status of electrical substations critical for nuclear safety and security in Ukraine confirmed that the grid situation is now in its worst condition since the Agency began monitoring substations in September 2024.

The latest mission, conducted from 1 to 12 December 2025, involved visits to more than ten substations - critical for ensuring nuclear safety and security by providing the electricity all NPPs need for reactor cooling and other safety systems. The objective of the mission was to assess damage, review repair efforts, and identify practical steps to strengthen the resilience of off-site power supplies to the country's NPPs.

Assessing conditions against the Seven Indispensable Pillars for ensuring nuclear safety and security during an armed conflict, the team confirmed that continued and deliberate attacks on critical grid infrastructure have caused cumulative impacts on NPP operations and staff conditions. Power cuts are affecting cities where plant personnel live, undermining living conditions and directly impacting staff through disruptions to electricity, heating, and water supply.

"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," said Director General Grossi. "I repeat my call for maximum military restraint. No one wants, or benefits from, a nuclear accident" Director General Grossi added.

The IAEA has continued to deliver on its comprehensive programme of assistance to help Ukraine maintain nuclear safety and security. Five new deliveries have been made, bringing the total to 194 since the start of the conflict.

Under the medical assistance programme, the medical unit at Khmelnitsky NPP received essential medications, while the Kherson Regional Infectious Diseases Hospital was provided with a digital colour Doppler ultrasound system within the framework of the IAEA Support and Assistance Mission to the Kherson Oblast (ISAMKO). Additionally, equipment and spare parts intended to support the safe operation of the South Ukraine NPP by maintaining a reliable power supply were delivered to the Joint Stock Company "Mykolaivoblenergo." The Chornobyl NPP also received equipment to enhance its physical protection measures at the site.

The deliveries were supported with funding from Austria, the European Union, France, Italy, Japan, and the United Kingdom.