The head of the United Nations nuclear watchdog agency has condemned drone strikes at the Zaporizhzhia Nuclear Power Plant, saying “such reckless attacks significantly increase the risk of a major nuclear accident and must be stopped immediately.”
At least three drones detonated at the plant on Sunday, according to inspectors from the U.N. International Atomic Energy Agency who are stationed at the facility. One strike left scorch marks on the roof of the containment building housing one of the plant’s six nuclear reactors, the agency said. Another hit outside a laboratory building. The location of the third drone strike was not included in the agency’s statement.
The facility, Europe’s largest nuclear power plant, is precariously perched on the eastern banks of the Dnipro river near the frontline dividing the warring armies, and has been a source of concern almost since the start of the war. It is the first time that a nuclear facility has been occupied by an invading army and repeated crises at the plant have prompted global alarm over the rising risks of a radiological disaster.
“The experts reported hearing explosions and rifle fire on the site throughout the day,” the agency said in a statement Sunday night. “Additionally, the I.A.E.A. team heard several rounds of outgoing artillery fire from near the plant.”
The U.N. agency did not speculate on who was responsible for the attacks. Ukraine and Russia each blamed the other for the strikes.
Rafael Mariano Grossi, the director general of the U.N. International Atomic Energy Agency, said in a statement that there were “no indications of damage to critical nuclear safety or security systems,” but international inspectors at the facility observed “minor superficial scorching to the top of the reactor dome roof” of one unit.
Mr. Grossi said it was the first time the facility “was directly targeted in military action” since November 2022 and the episode represented a “major escalation of the nuclear safety and security dangers.”
The U.N. agency said that its inspectors were on the roof of one unit at the plant when they witnessed Russian troops engaging “what appeared to be an approaching drone” without specifying what that meant.
“This was followed by an explosion near the reactor building,” the agency said in a statement. The inspectors were “able to confirm the physical impact of the drone detonations” at three locations and it appeared that they were aimed at “surveillance and communication equipment” at the facility.
Mikhail Ulyanov, Moscow’s envoy to the I.A.E.A in Vienna, blamed Ukrainian forces for the attack and said at least three people were injured.
Ukraine denied the Russian claims. In a statement to Ukrainian news outlet Ukrainska Pravda, the spokesman for the Defense Intelligence of Ukraine, Andriy Yusov, accused Moscow of staging a “false-flag” attack at the plant to undermine international support for Ukraine.
It was not possible to independently verify the claims of Russia, Ukraine or the I.A.E.A. inspectors at the plant, which has been under Russian military occupation for more than two years.
The New York Times and other independent media outlets have documented a campaign of abuse and intimidation directed at the plant’s Ukrainian employees since Russian forces stormed the facility shortly after the start of the war.
United Nations inspectors have found mines installed on the perimeter of the plant, and Ukrainian civilians living nearby have said the Russians use the facility as cover to launch attacks, knowing Ukraine will be limited in its ability to respond without risking nuclear safety.
All six reactors at the nuclear power plant have been shut down — meaning they no longer generate electricity — but they still require energy to power critical safety systems and water to circulate in their cores to dissipate residual heat from nuclear reactions to prevent a meltdown.
Edwin Lyman, a physicist and the director of nuclear power safety with the Union of Concerned Scientists, a nonprofit agency based in the United States, said in an email message that regardless of who was responsible, he was concerned that “more capable drones out there could do significant damage to the plant’s infrastructure.”
Petro Kotin, the head of Energoatom, Ukraine’s state nuclear power company, recently wrote that engineers have documented at least 150 concerning incidents at the plant since Russians soldiers took over the facility.
Equipment continues to deteriorate, he wrote, and there is also an increasing risk of human error “due to the lack of a sufficient number of qualified personnel, the use of unqualified staff from Russian nuclear power plants, as well as the tense state of personnel related to the occupation of the plant and the town of Energodar,” which is home to the plant.
Perhaps the most pressing concern has been the plant’s tenuous connection to the Ukrainian power grid. The plant has already experienced eight full blackouts, forcing engineers to rely on hulking diesel generators to keep critical safety equipment functioning each time.