Powerful explosions shook windows at the site of Ukraine’s Zaporizhzhya Nuclear power plant during the week of 19 February, underlining the urgent need for maximum military restraint to reduce the danger of a nuclear accident as the conflict enters its third year, director general Rafael Grossi of the International Atomic Energy Agency said in the IAEA’s Update 213 on 23 February.

IAEA experts stationed at the ZNPP reported hearing explosions every day during that week, including one on 23 February that appeared to occur close to the plant itself. There were also several explosions on the 22nd. One of them was unusually loud, indicating very close proximity to the site.

It was not possible to conclusively determine the origin or direction of the blasts, with the exception of the large explosion on the 22nd, which according to the ZNPP was part of ‘field training’ with no shelling of the plant nor any damage to it. There were no physical injuries or casualties reported.

The ZNPP separately informed the IAEA team that a mine exploded outside the site perimeter earlier on the 22nd, also without causing damage or injury.  

“I remain deeply concerned about the nuclear safety and security situation at Europe’s largest nuclear power plant, located on the frontline of the war. The reports of our experts indicate possible combat action not far away from the site. Once again, I call on all parties to strictly observe the five concrete principles for the protection of the plant and avoid any attack or military activity that could threaten nuclear safety and security there,” director general Grossi said.

In another indication of persistent nuclear safety and security risks facing the ZNPP, the site remains without back-up power, three days after the connection to its last 330 kV line was cut due to a problem that occurred on the other bank of the Dnipro river.

The ZNPP is still receiving the electricity it needs for reactor cooling and other nuclear safety and security functions from its only remaining 750 kV line, but it currently has no back-up options available for off-site power. The ZNPP said it had been informed by the Ukrainian grid operator that the 330 kV line was not expected to be reconnected to the site before 1 March.

“This situation leaves the plant very vulnerable to further disruptions in the supply of off-site power. It is essential that the back-up power line becomes available again as soon as possible,” said Mr Grossi.

The IAEA team has been to the site’s 750 kV electrical switchyard and observed that its status was unchanged since a previous visit in January. In addition to the single line that remains connected, the team saw spare parts for the repair of a second line, out of four 750 kV lines before the conflict. However, the site has no plans to start the repair work due to the conflict.

The experts have met with the ZNPP’s electrical department to discuss the maintenance plans for the year and also visited the electrical control room where they could observe the status of the on-site and off-site power systems. They were informed that all ageing cabling and equipment related to the safety systems, including switchboards and batteries, have been replaced.

The team performed a walkdown of all six main control rooms in the reactors on 19 February. The team was able to collect safety parameters in reactor units 2, 3 and 4 and had the opportunity to view the regulatory authorisations of personnel. The team was informed that many of the operating staff present were in the process of transitioning from their Ukrainian licences to “authorisations” issued by Rosteckhnadzor, the nuclear regulator of the Russian Federation.