Rosatom, Zaporizhia NPP, Russian media and the International Atomic Energy Agency (IAEA) have all reported drone strikes against the Zaporizhia NPP (ZNPP). Drone strikes hit the ZNPP site on 7 April “in a serious incident that endangered nuclear safety and security, IAEA Director General Rafael Mariano Grossi said. For the first time since November 2022, the plant was directly targeted in military action that also represents a clear violation of the five basic principles for protecting the facility established by Grossi at the United Nations Security Council in May 2023, IAEA noted.

“This is a major escalation of the nuclear safety and security dangers facing the ZNPP. Such reckless attacks significantly increase the risk of a major nuclear accident and must cease immediately,” Grossi said. At this point, there are no indications of damage to critical nuclear safety or security systems at the site. However, the military strikes were another stark reminder of persistent threats to the ZNPP and other nuclear facilities during the armed conflict, despite the IAEA’s efforts to reduce the risk of a severe accident that could harm people and the environment in Ukraine and beyond.

“As I have repeatedly stated – including at the Security Council and the IAEA Board of Governors – no one can conceivably benefit or get any military or political advantage from attacks against nuclear facilities. Attacking a nuclear power plant is an absolute no go,” Grossi said. “I firmly appeal to military decision makers to abstain from any action violating the basic principles that protect nuclear facilities.”

After receiving information from ZNPP about the drone attacks, the IAEA experts stationed at the site went to three affected locations. They were able to confirm the physical impact of the drone detonations, including at one of the site’s six reactor buildings where surveillance and communication equipment appeared to have been targeted. While they were at the roof of the reactor, Unit 6, Russian troops engaged what appeared to be an approaching drone. This was followed by an explosion near the reactor building.

The IAEA team reported that they observed remnants of drones at this and two other impact locations at the site. At one of them, outside a laboratory, they saw blood stains next to a damaged military logistics vehicle, indicating at least one casualty. The experts reported hearing explosions and rifle fire on the site throughout the day. Additionally, the IAEA team heard several rounds of outgoing artillery fire from near the plant.

While the team so far has not observed any structural damage to systems, structures, and components important to nuclear safety or security of the plant, they reported observing minor superficial scorching to the top of the reactor dome roof of Unit 6 and scoring of a concrete slab supporting the primary make-up water storage tanks. “Although the damage at Unit 6 has not compromised nuclear safety, this was a serious incident that had the potential to undermine the integrity of the reactor’s containment system,” Grossi said.

Tass and other Russian media reported that Ukrainian Armed Forces had launched an unprecedented series of attacks on the plant. According to ZNPP, territory adjacent to the dining room was hit and a truck delivering food was damaged. As a result, three plant employees were injured, one of them seriously. Half an hour later, another drone attacked the cargo port area. Shortly after, Unit 6 was attacked by a drone which struck the dome of the reactor building. 

Two days before, on 5 April, ZNPP had reported on its Telegram channel that Ukrainian drones had been recorded in the area of a cargo port and a nitrogen-oxygen station No 2. Although operation of the station was not disrupted, and critical infrastructure facilities were not damaged, ZNPP said: "We once again declare that it is unacceptable to conduct shelling of both the station itself and its infrastructure facilities."

ZNPP reported on 8 April that another Ukrainian kamikaze drone had been shot down over the plant and had fallen on the roof of Unit 6. There were no threats to violate the safety limits of the nuclear power plant, the press service of the station said. "The radiation background at the plant and the adjacent territory has not changed and is at the level corresponding to the normal operation of power units, and does not exceed the natural background values," ZNPP noted.

However, the plant stressed that ongoing attacks could affect the safe operation of the facility. ZNPP Director Yuri Chernichuk said this was a strong provocation by Ukraine. “This attack had more of a psychological effect… but potentially any attack can lead to sad consequences." 

Rosatom called on the leadership of the IAEA and the EU countries to respond to the direct threat to the safety of the NPP and to categorically condemn Ukraine’s attempt to escalate the situation. The Permanent Representative of the Russian Federation to international organisations in Vienna, Mikhail Ulyanov, said the attack of Ukrainian drones on ZNPP was a violation of the five principles for protecting the plant.

He told Rossiya 24: "This is a very serious escalation, a really very serious threat to nuclear security. In the event of a nuclear catastrophe, Ukraine itself and the surrounding territories will also suffer." He noted that IAEA Director General Grossi, “understands everything, but there is a big omission in his statements – he does not dare to say directly that the attacks were carried out by the Ukrainian Armed Forces.”

In an angry post on her Telegram channel, Russian Foreign Ministry spokeswoman Maria Zakharova said: "The international community must understand and respond to the Kiev regime's act of nuclear terrorism. How many more times must the Ukrainian armed forces fire at the NPP before the West and the monster Zelensky supported by it stops repeating this deadly act in their bloody circus? Do Biden, Macron, Scholz and other wildlife defenders not realise that their subordinates on Bankovaya Street may destroy everything?" 

Alexander Uvarov, Director of the Autonomous Non-Profit Organisation Atominfo-Centre, explained that the walls and dome of the reactor are more than a metre thick and can withstand the fall of aircraft, “but, like any other such station, it is not designed to be exposed to full-fledged fire”, he said. Other parts of the plant, such as the used fuel store, were more vulnerable and loss of external power could also prove dangerous.

On 4 April, it was reported that the plant’s 330 kV back-up line had been disconnected amid renewed indications of military activity in the area leaving the plant entirely dependent on its sole remaining 750 kV line for off-site power. Since August 2022, the ZNPP has suffered eight events with a complete loss of off-site power, most recently in December last year. The 330 kV line was also disconnected for three weeks earlier this year, but the main 750 kV line remained available at that time.

An earlier IAEA update on the plant, before the drone attacks, said the IAEA team at ZNPP had been informed that the plant was assessing the future operational status of its only heat-generating unit after the nearby town of Enerhodar – where most plant staff live – officially ended the winter heating season. ZNPP stopped producing electricity for the national grid in September 2022, but kept at least one of its six units in hot shutdown to provide district heating as well as process steam for liquid waste treatment at the site – currently Unit 4.

“A decision to move Unit 4 to cold shutdown would be more favourable for nuclear safety and security, but it should not detract from the fact that the situation at ZNPP remains highly precarious, as this morning’s power loss once again demonstrated,” Grossi said. Meanwhile, the IAEA team had continued to conduct walkdowns at the site, including to some of the reactor units as well as the ZNPP inlet and discharge channels, where they also observed the cooling towers and their pumping station.

At the waterworks facilities, the team was informed that the ZNPP cooling pond currently receives approximately 400 m3/h of water from the sprinkler ponds as well as from the discharge channel of the nearby Zaporizhia Thermal Power Plant. The water supplied from the eleven underground wells is providing enough cooling water for the six units in shutdown, but still not enough to maintain the water inventory in the ZNPP cooling pond.

During a visit to the Unit 4 reactor building the team observed the chemical analysis laboratory and the safety system rooms. No leaks or traces of boric acid were seen. But the experts noted what appeared to be some crystallised boric acid in one of the sump intakes during a visit to Unit 1 sumps for the ECCS (Emergency Core Cooling System). Borated water is used in the primary coolant to help maintain nuclear safety functions. Although leaks may occur, prompt investigation, repair, and clean-up are crucial to prevent potential damage to any system important to nuclear safety.

Image: The domed roof of Unit 6 of the Zaporizhia nuclear power plant has been scorched following a recent drone attack (courtesy of Rosatom)