Powerful explosions shook the area of Ukraine’s Zaporizhzhia Nuclear Power Plant (ZNPP) on the evening of 19 November and the following morning, abruptly ending a period of relative calm at the facility and further underlining the urgent need for measures to help prevent a nuclear accident there, International Atomic Energy Agency (IAEA) Director General Rafael Mariano Grossi said on 20 November.

In what appeared to be renewed shelling both close to and at the site of Europe’s largest nuclear power plant, IAEA experts at the ZNPP reported to Agency headquarters that more than a dozen blasts were heard within a short period of time in the morning local time. The IAEA team could also see some of the explosions from their windows.

Citing information provided by plant management, the IAEA team said there had been damage to some buildings, systems and equipment at the ZNPP site, but none of them so far critical for nuclear safety and security. There were no reports of casualties. The IAEA experts are in close contact with site management and will continue to assess and report on the situation.

“The news from our team yesterday and this morning is extremely disturbing. Explosions occurred at the site of this major nuclear power plant, which is completely unacceptable. Whoever is behind this, it must stop immediately. As I have said many times before, you’re playing with fire!” Grossi said.

He renewed his urgent appeal to both sides in the conflict to agree and implement a nuclear safety and security zone around the ZNPP as soon as possible. In recent months, he has engaged in intense consultations with Ukraine and Russia about establishing such a zone, but so far without an agreement. “I’m not giving up until this zone has become a reality. As the ongoing apparent shelling demonstrates, it is needed more than ever,” he said.  

ZNPP provided about a fifth of Ukraine’s electricity before the start of Russia’s special military operation and has been forced to operate on back-up generators a number of times after shelling damaged key transmission lines. It has six Soviet-designed VVER-1000 V-320 water-cooled and water-moderated reactors which used to use Russian supplied fuel that was then taken back and reprocessed in Russia. However Ukraine changed to Westinghouse supplied fuel and that used fuel is now stored at a dry storage facility on site. Although the reactors are now shut down they still required power to operate their cooling systems.

The Russian Defence Ministry said on 20 November said the previous day “Ukrainian artillery fired 11 large-calibre artillery shells at the nuclear power plant” and had fired again twice the next day. “From 9.15 to 9.45, 12 large-calibre artillery shells were fired. Eight of them exploded between the fifth power unit and special building No 2, three hit between the fourth and fifth power units, and one hit the roof of special building No 2. From 10 o'clock to 10.10 minutes, two more projectiles were recorded, fired along the power transmission line that feeds the power plant," the Ministry noted. The shooting was conducted from the area of the settlement of Marganets in the Dnipropetrovsk region, controlled by the Ukrainian military, and the firepower was suppressed by the return fire from Russian artillery units, the Ministry added.

Renat Karchaa, adviser at Russian nuclear utility Rosenergoatom, confirmed the shelling. Rosenergoatom formally took control of ZNPP following the September referendum in which the majority of the Zaporozhye population reportedly voted for integration with Russia. A number of Rosenergoatom specialists are now permanently working at the plant, although the majority of the staff are Ukrainian. Ukrainian nuclear utility Energoatom still insists it owns the plant. Karchaa said six projectiles had hit the cooling system of one of the reactors and two struck the radioactive waste storage. He added that the employees were unharmed. “We are talking about the perimeter of the station itself, and not about the wider industrial zone. There were six flights to the splash pool, which is a cooling system. Two arrivals were in the area of a dry nuclear waste storage facility. And there were three more arrivals in the area of checkpoint-2, " he told Rossiya–24.  

Scientific Secretary of the All-Russian Research Institute for the Operation of Nuclear Power Plants (VNIIAES) Alexander Prosvirnov, told Ria Novosti that the reactor units themselves are well protected — their containment is able to withstand the fall of a light aircraft weighing up to 20 tons, he said. At the same time, the storage of nuclear waste is a more accessible target. "This is a more vulnerable object, and it can pose a radiation hazard when hit by projectiles. This is a kind of analogue of the ‘dirty bomb’, " he said.

According to Ukraine’s Energoatom, which blamed the shelling on Russia, “overpasses linking the facility to special buildings, storage tanks of demineralised water, steam generator blowdown system, auxiliary systems of one of the two plantwide diesel engines, and other equipment of the power plant infrastructure were damaged”. Three hits were also recorded in the area of the Raiduha substation. The damage and destruction there are still being assessed.”

Meanwhile, the IAEA Board of Governors adopted a draft resolution calling on the Russian Federation to leave ZNPP. "The Board of Governors expresses regret and does not recognise the attempts of the Russian Federation to take over the Ukrainian Zaporizhzhia NPP and calls on the Russian Federation to immediately abandon its unfounded claims to ownership of this plant," the resolution said. Finland and Canada initiated the vote. The draft resolution was approved by 24 of 35 Board members. Russia and China voted against while India, Pakistan, Saudi Arabia, Vietnam, South Africa, Kenya and Namibia abstained. Two other states did not participate in the voting.

Earlier, on 16 November, an update from IAEA noted that Ukraine's Khmelnytskyy Nuclear Power Plant (KhNPP) had lost all access to the electricity grid the day before due to military attacks, forcing it to temporarily rely on diesel generators for back-up power, citing information Grossi had received from Ukrainian authorities.

The KhNPP’s grid connection was completely lost at 18:35 local time on 15 November, after the site’s four operating power lines were progressively lost over a two-and-a-half-hour period because of missile attacks on the country’s energy infrastructure, Ukraine told the IAEA. During this period, the plant’s two reactors were shut down, halting their delivery of electricity to households, factories and others.

More than nine hours later – at 03:45 this morning – the plant regained off-site electricity through two 330 kilovolt (kV) back-up power lines, and the diesel generators were stopped. One of those lines was again lost about an hour later and only restored at 11:25. The two reactor units remain in shutdown mode.

Another nuclear power plant also located in western Ukraine – Rivne – lost the connection to one of its 750 kV power lines on 15 November. As a result, the plant reduced its power output, and one of its four units was automatically disconnected. At 04:00 today, the plant increased the power of one of its other units to continue supplying electricity to the Ukrainian network.

“This was a very concerning development. It shows the potential nuclear safety and security risks facing all of Ukraine’s nuclear facilities during this terrible war, not just the ZNPP. While off-site power is now back at the Khmelnytskyy Nuclear Power Plant, the power loss clearly demonstrates that the nuclear safety and security situation in Ukraine can suddenly take a turn for the worse, increasing the risk of a nuclear emergency,” Grossi said.

The power loss at the KhNPP came just a day after the IAEA announced it would in the coming weeks send nuclear safety and security missions to this plant, Rivne and the South Ukraine NPP as well as to Chornobyl. The missions are being organised at the request of Ukraine. “We will be at these nuclear power plants in the near future as part of our steadfast assistance to Ukraine in its efforts to maintain nuclear safety and security and prevent a nuclear accident during the conflict,” Grossi said. The IAEA has had a permanent team of experts at ZNPP since September.