Ukraine’s Zaporizhzhya Nuclear Power Plant (ZNPP) lost all external power for several hours this morning, underlining the extremely precarious nuclear safety and security situation at the facility and the urgent need to protect it and prevent an accident, Director General Rafael Mariano Grossi of the International Atomic Energy Agency (IAEA) said today, writes iaaea.org.
It was the seventh time Europe’s largest nuclear power plant (NPP) was completely disconnected from the national electricity grid since the military conflict in Ukraine began 15 months ago, once again forcing it to rely on emergency diesel generators for the power it needs for reactor cooling and other essential nuclear safety and security functions, Director General Grossi said.
The ZNPP’s only remaining external 750 kilovolt (kV) power line was cut around 05:30am 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 Zaporizhzhya 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.
“I’m continuing to engage in intense negotiations with all the involved parties to secure the protection of the Zaporizhzhya Nuclear Power Plant. I will not stop until this has been achieved,” he said.
The Director General said he aimed to secure agreement on a set of principles to protect the ZNPP during the armed conflict, covering also the availability and security of external power supplies at all times.
The seven indispensable pillars for nuclear safety and security outlined by the Director General early during the conflict also stress the need for secure off-site power supplies from the grid for nuclear sites.
The ZNPP does not have any operational back-up power lines since the last functioning 330 kV power line was damaged on the right bank of the Dnipro River on 1 March. This back-up 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, Director General 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 back-up power lines and reiterated the need for the IAEA team at the site to gain access to the nearby Zaporizhzhya Thermal Power Plant (ZTPP), which has yet to be granted despite assurances by Russian state nuclear company Rosatom. The ZTPP operates its 330 kV open switchyard, through which back-up power has in the past been provided to the ZNPP.
Initially after this morning’s off-site power cut, all the ZNPP’s 20 diesel generators started operating, but 12 of them were later switched off. This left eight running, which is sufficient to operate all systems safely. 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 ZNPP’s six reactors were already in a cold shutdown state before today’s power outage, and preparations were under way 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.
Elsewhere in the country today, a team of IAEA experts at the South Ukraine NPP said an emergency shutdown had occurred at one of its three reactor units. Plant management informed the IAEA team that the automatic shutdown took place due to grid disturbance or instability. The SUNPP still has off-site power available.
