Ukraine’s Zaporizhzhya Nuclear Power Plant (ZNPP) was reconnected to its last remaining backup power line on Monday after successful repairs were completed under a temporary ceasefire negotiated by the International Atomic Energy Agency (IAEA), Director General Rafael Mariano Grossi said today.

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The backup 330-kilovolt (kV) line was damaged and has been disconnected since 2 January, reportedly because of military activity. Since then, ZNPP relied on its last remaining 750-kV main power line to provide the off-site power needed to operate safety systems to cool the ZNPP’s six shutdown reactors and spent fuel pools.

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After the repair site was cleared of any unexploded ordinance on Saturday, a specially deployed IAEA team monitored the repairs conducted on the frontline by Ukrainian technicians on Sunday and Monday. 

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“The IAEA continues to play a vital role to maintain nuclear safety and security at the ZNPP. This was the fourth temporary ceasefire agreement that we have negotiated between both sides, for five separate repairs of power lines connected to the ZNPP,” Director General Grossi said. “Now that the site has regained connection to both off-site power lines, I once again call on both sides to abide by the Five Concrete Principles to avoid a nuclear accident at the ZNPP by making all efforts to avoid any future damage to these lines.”

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The team continues to monitor nuclear safety and security at the site, especially in consideration of winter conditions. Under normal operations, residual heat from the operating reactor units keeps the water temperature in the cooling pond and sprinkler ponds warm. With the reactors shut down, less heat is generated, potentially increasing the risk of the water freezing.

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During a walkdown on Sunday, the IAEA team observed large ice formations on fountain pipes in some sprinkler ponds. A follow‑up walkdown today confirmed that the ice formations were no longer present. The team also confirmed that all 11 groundwater wells remain operational and continue supplying water to the sprinkler ponds, despite the sub-zero conditions. The IAEA team will continue to monitor this issue.

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The IAEA team also conducted walkdowns of the Unit 4 reactor building and its safety system rooms, the turbine halls of Units 3 and 4—where the team could not gain access to the western part of the building—and the Unit 6 electrical, instrumentation and control rooms. They also observed routine testing of an emergency diesel generator (EDG) of Unit 3.

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Elsewhere in Ukraine, IAEA teams reported military activities in proximity of nuclear power plants (NPPs). Last Friday, one drone was reported approximately 10 kilometres (km) from the South Ukraine NPP. On Tuesday morning, three drones were reported about 5 km from the Chornobyl NPP site, and military activities on Tuesday damaged a critical substation, resulting in the disconnection of power lines to the Chornobyl NPP site and one of the operating NPPs.

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At the Chornobyl NPP, one 750-kV power line and two 330-kV lines were lost on Tuesday morning. Though the site received power from other off‑site power lines, the EDGs for the New Safe Confinement operated three times during the day, and the EDGs for the Interim Spent Fuel Storage Facility‑2 operated once during the day either as a result of the line disconnection or due to power fluctuations. A 110-kV line was also disconnected on Tuesday and again on Wednesday.

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An IAEA mission will deploy on Monday to assess the condition of Ukraine’s critical substations and their implications for nuclear safety at Ukraine’s nuclear facilities. “These critical substations are essential for ensuring reliable off‑site power, a key requirement under Pillar 4 of the Seven Indispensable Pillars of nuclear safety,” Director General Grossi said. “Any damage to this infrastructure undermines nuclear safety and must be avoided.”

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This week, IAEA teams at the Chornobyl NPP site and the Rivne NPP safely rotated. 

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The Agency continued with deliveries under the comprehensive programme of assistance to help Ukraine maintain nuclear safety and security amid the on-going conflict. This week, five electric all-terrain vehicles were delivered to the State Specialized Enterprise “Association Radon” to support the needs of its physical protection department. Within the scope of the medical programme, the medical unit of the Chornobyl NPP received medications for the needs of their staff.

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The deliveries, which brought the total number of shipments to Ukraine to 198 and totalling €21.9 million worth of equipment since the start of the conflict, were made possible with funds from the United Kingdom and the European Union.

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Text Courtesy, IAEA