The Ukrainian Zaporizhzhia Nuclear Power Plant (NPP) lost all external power for several hours on Monday morning (22 May), Director General Rafael Mariano Grossi of the International Atomic Energy Agency (IAEA) confirmed yesterday.
This was the seventh time that the nuclear power plant was completely disconnected from the national power grid since the start of the Russian invasion military of Ukraine, IAEA said. Emergency diesel generators were used to power the reactor cooling process and other essential nuclear safety and security functions, IAEA’s Director General said.
The ZNPP’s only remaining external 750 kilovolts (kV) power line was cut around 05:30 am local time and re-connected after more than five hours, according to IAEA experts present at the plant.
“This morning’s loss of all off-site power demonstrates the highly vulnerable nuclear safety and security situation at the Zaporizhzhia Nuclear Power Plant. As I’ve said repeatedly, this simply can’t go on. We’re playing with fire. We must act now to avoid the very real danger of a nuclear accident in Europe, with its associated consequences for the public and the environment,” Director General Grossi said.
Previously, Director General Grossi aimed to secure an agreement on a set of principles to protect the ZNPP during the ongoing armed hostilities. Securing off-site power supplies from the grid for nuclear sites is included in the “seven indispensable pillars for nuclear safety and security” outlined by Director General Grossi in the earlier stages of the war.
“I’m continuing to engage in intense negotiations with all the involved parties to secure the protection of the Zaporizhzhia Nuclear Power Plant. I will not stop until this has been achieved,” he said.
The ZNPP does not have any operational backup power lines since the last functioning 330 kV power line was damaged on the right bank of the Dnipro River on 1 March. This backup power line has still not been repaired, meaning that when the 750 kV line is lost the plant immediately depends on its diesel generators which are its last line of defence for electricity supplies, Mr Grossi said.
“For more than two and a half months, this major nuclear power plant has only had one functioning external power line. This is an unprecedented and uniquely risky situation. Defence-in-depth – which is fundamental to nuclear safety – has been severely undermined at the ZNPP,” he said.
Director General Grossi called for stepped-up efforts to restore the ZNPP’s backup power lines and reiterated the need for the IAEA team at the site to gain access to the nearby Zaporizhzhia Thermal Power Plant (ZTPP), which has yet to be granted despite assurances by Russian state-owned nuclear company, Rosatom. The ZTPP operates its 330 kV open switchyard, through which backup power has in the past been provided to the ZNPP.
Following yesterday’s off-site power cut, all the ZNPP’s 20 diesel generators initially started operating, but 12 of them were later switched off. This left eight generators running, which is sufficient to operate all systems safely, the IAEA said.
The IAEA experts at the site were informed that there is enough diesel fuel for 23 days. After the 750 kV line was restored, the diesel generators were gradually turned off.
Five of the site’s six reactors were already in a cold shutdown state before yesterday’s power outage, and preparations were underway to transfer also Unit 5 from hot to cold shutdown. Following the restoration of off-site power, Unit 5 is being returned to hot shutdown, the IAEA added.