Six-unit facility once again receiving external electricity to cool reactors and spent fuel
The Zaporizhzhia nuclear power station was successfully re-connected to Ukraine’s electrical grid on Thursday (23 October) after a month-long outage, following repairs carried out under the protection of a local ceasefire negotiated by the International Atomic Energy Agency (IAEA).
The agency said the restoration of offsite power to Europe’s largest nuclear power plant – on the frontline of the military conflict in southeast Ukraine – marks a significant positive step. Last month’s loss of all external electricity supplies had further stoked concerns about the fragile nuclear safety and security situation at the site.
The agency’s director-general Rafael Grossi said in a statement: “Today is a rare, good day for nuclear safety and security in Ukraine and beyond, although the overall situation of course remains highly precarious.
“After exactly one month without any offsite power, the Zaporizhzhia Nuclear Power Plant is once again receiving the external electricity it needs to cool its six reactors and spent fuel.”
Grossi said that since the plant was disconnected from its last offsite power line on 23 September, the IAEA has been working intensively with Russia and Ukraine to create the security conditions needed for repairs to be carried out on both sides of the frontline.
“Despite the war, they both agreed that it was vital to restore offsite power and cooperated constructively with us to make that happen,” Grossi said.
In the reconnection process, which was followed by an IAEA team on the ground and from Zaporizhzhia’s electrical control room, the newly repaired 750 kilovolt (kV) Dniprovska power line was energised by the Ukrainian grid operator at 09:30 local time and Zaporizhzhia’s 750kV switchyard was fully powered two minutes later.
Zaporizhzhia technicians then began gradually restoring power to its six reactor units and the remainder of the site.
At 13:00 local time offsite power was restored to the whole Zaporizhzhia site and the last of the emergency diesel generators that had supplied backup power for the past 30 days was turned off, ending the tenth and by far the longest complete loss of offsite power suffered by the plant during the conflict.
“What was once virtually unimaginable – a nuclear power plant regularly losing offsite power – has unfortunately become a common occurrence during this devastating war,” Grossi said.
“However, this was the most challenging loss of power event we have experienced so far.”
Under IAEA monitoring, work to repair the Dniprovska and another damaged power line – Ferosplavna-1 – got underway last weekend after the establishment of temporary ceasefire zones on opposite sides of the Dnipro River.
Extensive Clearance Work Before Repairs Could Begin
As both zones are in an active combat area, de-mining specialists conducted extensive clearance work before the actual repairs could begin.
The IAEA team based at Zaporizhzhia monitored the work at the damaged section of the Dniprovska line, where technicians replaced several broken cables before re-attaching them to the transmission towers. A damaged metal support arm of one transmission tower was also replaced, and new insulators were installed in several towers.
The IAEA is continuing to coordinate with both sides to pave the way for further repairs of the 330 kV Ferosplavna-1 line, where additional damage outside the ceasefire zone was identified this week. The IAEA was informed that two broken transmission cables were found 1.8km from the electrical switchyard of the Zaporizhzhia Thermal Power Plant, near the nuclear plant.
Before the conflict, the Zaporizhzhia nuclear plant had access to 10 power lines. In recent years, that was reduced to two, of which Ferosplavna-1 was lost on 7 May while the Dniprovska line was disconnected late last month. Both sides blamed the damage on military activity.
The plant’s six reactors have not produced electricity for more than three years and have been shut down, but they still require power to run their cooling pumps and for other nuclear safety and security equipment. Over the past month, the plant has relied on emergency diesel generators for the electricity it needs.
The Zaporizhzhia nuclear plant and the nearby city of Enerhodar came under Russian military occupation soon after Russia’s February 2022 invasion of Ukraine.
A control room at the Zaporizhzhia nuclear power station in Ukraine. Courtesy IAEA.
