Koeberg Unit 1 successfully reconnected to the national grid following major maintenance strengthening baseload power, Energy Availability Factor (EAF) and energy security
Wednesday, 29 October 2025: Eskom has reconnected Unit 1 at the Koeberg Nuclear Power Station to the national grid at 01:36 on 29 October 2025, marking an important milestone in further enhancing the security of South Africa’s electricity supply and returning 930MW. This follows the unit’s first scheduled major maintenance outage, since the installation of new steam generators. Loading the fuel began in early September 2025, followed by commissioning activities before the unit’s successful synchronisation.
Both Koeberg Unit 1 and Unit 2 are currently online, with Unit 1 in the process of ramping up and Unit 2 generating 941MW. Once Unit 1 reaches full output, the two units will jointly provide over 1 860MW of capacity to the national grid. This is about 5% of Eskom’s total electricity output and the station houses the largest nuclear generating units on the African continent.
To maintain grid stability, Koeberg’s maintenance outages are strategically staggered every 16 to 18 months, ensuring the two units are never offline at the same time. Unit 2 has been running at full capacity for 234 days at 99.88% year-to-date Energy Availability Factor and is awaiting the National Nuclear Regulator’s (NNR) decision on its 20-year Long-Term Operation licence on 9 November 2025.
The achievement reflects Eskom’s commitment to the safe, reliable, and efficient operation of South Africa’s only nuclear power plant, which provides clean, cost-effective 24/7 baseload electricity to the national grid.
The maintenance, which included comprehensive inspections, safety checks, and the statutory 10-year Integrated Leak Rate Test (ILRT), has ensured the unit is ready to operate safely and efficiently until its next major maintenance cycle. The ILRT confirmed the containment building’s structural integrity and leak-tightness in line with international nuclear safety standards.
“Our teams have demonstrated exceptional technical expertise and commitment. Koeberg remains a cornerstone of South Africa’s energy mix, and this achievement underscores Eskom’s continued focus on nuclear safety and operational excellence,” said Bheki Nxumalo, Eskom’s Group Executive for Generation.
In July 2024, following the successful completion of the Steam Generator Replacement Programme in November 2023, the National Nuclear Regulator (NNR) extended Eskom’s licence to operate Unit 1 until July 2044, enabling the unit to continue supplying over 930MW of dependable, clean and cost-effective 24/7 baseload capacity to the national grid for the next two decades.
In line with the Integrated Resource Plan (IRP 2025), Eskom continues to support nuclear power as a clean, reliable, and cost-effective part of South Africa’s long-term energy strategy.
The successful return of Unit 1 underscores Eskom’s dedication to nuclear safety, operational reliability, and the continuous supply of electricity, reinforcing South Africa’s energy security and long-term sustainability objectives.
ENDS
