IAEA Director General Rafael Mariano Grossi said today that he is discussing detailed proposals with the Russian Federation and Ukraine on how to restore off-site power to the Zaporizhzhya Nuclear Power Plant (ZNPP), which has relied on emergency back-up electricity for the past ten days.
“Both sides say they stand ready to conduct the necessary repairs on their respective sides of the frontline. But for this to happen, the security situation on the ground must improve so that the technicians can carry out their vital work without endangering their lives. I’m in continuous contact with senior Russian and Ukrainian officials to achieve this important objective as soon as possible,” Director General Grossi said.
“For now, the site’s emergency diesel generators are functioning without problems, and there is also plenty of fuel in reserve. However, this is an unprecedented situation that must be resolved without further delay. It is a nuclear safety issue and it is in everybody’s interest to fix it,” he said.
Until a few months ago, two off-site power lines were still available to supply the electricity that the ZNPP requires to cool its six shutdown reactors and its spent fuel. However, it lost one of them – a 330 kilovolt (kV) line – in early May due to damage sustained on the Ukrainian side of the frontline. On 23 September, the sole remaining 750 kV line was disconnected as a result of damage on the other side of the frontline.
The resulting loss of off-site power (LOOP) is by far the longest lasting of the ten such events that the ZNPP has suffered during more than three and a half years of military conflict.
As the ZNPP’s reactors have been shut down since 2022, the nuclear safety risks are not as great or urgent as they would be for an operating nuclear power plant. However, if the emergency diesel generators (EDGs) stopped functioning for any reason, it could lead to a complete blackout and possibly causing an accident with the fuel melting and a potential radiation release into the environment, if power could not be restored in time. The site also has mobile diesel generators available in case the EDGs are not able to supply the necessary power.
“For nuclear safety, this is still a very serious situation. I’m calling on both sides to do what is necessary to prevent a further deterioration. It is a question of political will, not whether it is technically possible, which it is,” Director General Grossi said.
As of this morning, eight EDGs were operating at the plant, generating a total power output of 20-22 megawatts, sufficient to cover its nuclear safety needs. Another 12 EDGs were available and on standby. Two of the EDGs that were under planned maintenance prior to the power loss were put back into service yesterday. The plant rotates the operating EDGs and carries out technical servicing, as needed.
The EDGs each have their own fuel tanks, which the ZNPP says can provide fuel for at least 10 days of operation, in the current operating configuration. Additional fuel supplies are delivered daily to the on-site EDG fuel tanks from the off-site diesel fuel storage facility, which houses three large tanks.
The IAEA team at the site is receiving frequent updates of all important nuclear safety parameters, showing that the EDGs are continuing to reliably provide the power needed for cooling as there has been no increase in the coolant temperatures of both the reactor cores and spent fuel pools.
The IAEA team conducted a walkdown yesterday to monitor the operating EDGs while also observing that a diesel fuel truck was on-site, bringing fuel from the outside storage facility – also known as the diesel fuel farm. The ZNPP informed the IAEA team that the most recent delivery of diesel fuel to the outside storage facility occurred on Wednesday and that another delivery was expected today.
The team has also conducted radiation monitoring, showing no increase in radiation levels.
The ZNPP has informed the IAEA team that planned maintenance activities on one pair of backup power transformers was stopped after the LOOP, and the transformers were returned to standby mode.
Challenges related to off-site power were also in evidence at the Chornobyl site this week, where its New Safe Confinement (NSC) facility experienced a loss of power on Wednesday evening. The IAEA team based at the site was informed that the Slavutych 330 kV switchyard located around 40km away was damaged because of military activity in the area, causing the disconnection of this power line at 4:10pm local time.
Off-site power to the NSC – a large structure built to prevent any radioactive release from the reactor destroyed in 1986 and to protect it from any external hazard – was only restored some 16 hours later. During this time, the facility – which was severely damaged by a drone in February – had no access to back-up EDG electricity for some three hours on Wednesday evening, resulting in a partial blackout to the NSC.
The IAEA team was informed that radiation monitoring and ventilation of the NSC remained operational throughout the blackout, via an interconnection to the systems of reactor units 3 and 4, which remained connected to the main electrical grid. The team was also informed that radiation levels remained normal during the entire event, which was confirmed by the IAEA’s own measurements.
All other nuclear facilities at the Chornobyl site continued to receive off-site power from other power lines without interruption. However, the plant reported fluctuations in off-site power affecting the other facilities at the site during the event and continues to assess the situation.
The Slavutych 330 kV power line remains disconnected, and the town with the same name – where most plant staff live – has no electricity, relying instead on diesel generators.
The IAEA team at the Chornobyl site was also informed that temporary repairs on the outside of the NSC arch are expected to be completed today following the February attack, meaning it will be fully covered from the outside.
In the 158th delivery of equipment to Ukraine since the start of the armed conflict, the South Ukraine NPP has received two mobile portal monitors aimed at enhancing nuclear security measures at the site. The equipment was funded with contributions made by Norway.
