Eskom has reconnected Unit 1 at the Koeberg Nuclear Power Station to the national grid. This was confirmed on 29 October 2025, returning 930 MW to the grid and marking a further milestone in enhancing the security of South Africa’s electricity supply. The return to service of Unit 1 follows the unit’s first scheduled major maintenance outage since the installation of the 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 ramping up and Unit 2 generating 941 MW. Once Unit 1 reaches full output, the two units will jointly provide over 1 860 MW of capacity to the national grid. This is about 5% of Eskom’s total electricity output. Koeberg houses the largest nuclear generating units on the African continent.
To maintain grid stability, Koeberg’s maintenance outages are staggered every 16 to 18 months, so 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. Eskom is awaiting the National Nuclear Regulator’s (NNR’s) decision on the 20-year Long-Term Operation licence for Unit 2, expected on 9 November 2025.
The successful maintenance and return to service of both units 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 programme, which included comprehensive inspections, safety checks, and the statutory 10-year Integrated Leak Rate Test (ILRT), has ensured that Unit 1 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 930 MW of 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 to service 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 supporting its long-term sustainability objectives.
For more information visit: www.eskom.co.za
