The International Atomic Energy Agency has concluded a mission to 19 electrical substations essential to Ukraine’s nuclear safety, days before it was informed of an attack on one of the substations assessed by the team, Director General Grossi said today. 

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On 27 October, the IAEA was informed of an attack on the Slavutych substation that reportedly resulted in the loss of all its 330 kV lines. The substation was among those assessed during the Agency’s ninth such mission since September 2024, although the security situation on ground prevented the team from visiting it. 

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The mission, conducted from 10 to 24 October, examined damage, restoration work and the resilience of off-site electricity supplies to Ukraine’s nuclear power plants (NPPs). 

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“Military activity around nuclear sites and attacks on the electrical substations that support them pose a serious risk to nuclear safety and security,” Director General Grossi said. “Despite the robust safety systems in place at nuclear facilities, a reliable electricity grid is essential, and it must be protected.” 

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Zaporizhzhya Nuclear Power Plant 

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At the Zaporizhzhya NPP (ZNPP), concerns over the site’s fragile off-site power supplies also persist. The IAEA continues to engage with the Russian Federation and Ukraine on arrangements for a ninth localized ceasefire to enable repairs to the ZNPP damaged main 750 kV Dniprovska power line and the Dniprovska substation.

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Before the military conflict, the ZNPP – Europe’s largest NPP - had ten off-site power lines. Today, it relies on a single 330 kV line, Ferosplavna-1, to maintain essential nuclear safety functions, leaving the plant vulnerable to further losses of off-site power. Last week, repairs to a backup transformer near the Zaporizhzhya Thermal Power Plant were completed under the eighth localized ceasefire facilitated by the IAEA. 

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That vulnerability was highlighted this past weekend when one of the lines connecting the Ferosplavna-1 to the ZNPP was briefly lost. This did not result in a loss of off-site power thanks to a back-up line, which was reconnected during the sixth Agency negotiated ceasefire in June.

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Meanwhile, the ZNPP’s 750 kV Dniprovska power line has remained unavailable since March, despite repairs also completed during the sixth ceasefire. The line could not be re-energized after extensive additional damage was identified at the Dniprovska substation and to the line itself near and above the Dnipro River. Repairing the section crossing the Dnipro River is expected to be technically complex. One phase of the line is completely severed, requiring work in difficult conditions over the river and the largely drained Kakhovka reservoir.

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The IAEA continues to work constructively with both sides to agree on security arrangements that would allow the necessary repairs to proceed.

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“The ZNPP’s continued reliance on a single off-site power line remains a serious concern for nuclear safety,” said Director General Grossi. “Every effort must now be made to enable the repair and restoration of a second line. Redundancy is fundamental to nuclear safety, and I urge both sides to cooperate constructively with the IAEA to help achieve this.” 

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Diesel fuel at the ZNPP

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This week, the IAEA team at the ZNPP conducted a walkdown to check diesel fuel levels of all emergency diesel generators (EDGs) used to power vital safety functions during off-site power losses. The plant reported that the daily diesel fuel tanks of all EDGs were fully filled. 

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However, diesel fuel reserves at the ZNPP remain low after nearly three weeks of EDG use following the extended loss of off-site power in August and September. The IAEA has not been informed of any diesel fuel deliveries to the site since March 2026, and military activity in the area has hampered efforts to replenish stocks. Regular EDG testing continues to consume diesel fuel despite measures to minimize consumption.

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This is of particular importance as winter approaches. Temperatures at the ZNPP are currently relatively mild but are expected to fall significantly in the coming months. Colder weather will increase demand for diesel fuel at the site, including for heating needed both for personnel and for the reliable operation of safety-related equipment.

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“Increasing diesel fuel stocks at the ZNPP is essential for nuclear safety, even more so before winter. We are working to facilitate a transfer of diesel fuel to the site to replenish its reserves. Adequate reserves will help the plant withstand further losses of off-site power and maintain suitable conditions for personnel and equipment,” Director General Grossi said.

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Military activity 

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The IAEA was informed yesterday that an employee of the ZNPP was killed by a drone attack. The victim was reportedly a welder at the plant’s centralized repair workshop. 

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Director General Grossi called for maximum military restraint to help prevent the risk of a nuclear accident during the conflict. “Any attack on nuclear plant staff is completely unacceptable and violates the Seven Indispensable Pillars for Nuclear Safety and Security during an armed conflict,” he said. 

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The IAEA team continues to hear military activity on a daily basis in the vicinity of the ZNPP. This week, the team also observed additional net coverings being installed above mobile pumps and mobile diesel generators as protection against drones.

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The volatile security situation also affected communications with the IAEA team. The Agency lost direct contact with its staff at the site for almost 24 hours following a regional internet disruption that was reported to have been caused by military activity.

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Military activity continued to be reported around Ukraine’s other nuclear sites this week, with IAEA teams reporting repeated air raid alarms. In total, 146 air raid alarms were reported, while numerous drones were detected in the vicinity of NPPs, including 13 near the Khmelnytskyy site, 12 near the South Ukraine site and 115 near the Chornobyl site.

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IAEA assistance to Ukraine

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The IAEA also continued delivering equipment to Ukraine this week as part of its comprehensive programme of assistance to the country.

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Under the Agency’s medical assistance programme, two decontamination cabins were delivered, one to South Ukraine Hospital and another to Varash Hospital. The deliveries were made possible with funding from Japan.

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“The IAEA remains committed to supporting nuclear safety and security in Ukraine through the delivery of technical assistance and equipment.”  Director General Grossi said. “What began as an emergency response has become one of the most comprehensive nuclear safety and security assistance efforts the IAEA has ever undertaken.”

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Text Courtesy, IAEA