- Eskom has reconnected Unit 1 at the Koeberg Nuclear Power Station to the national grid, returning 930MW capacity to the grid
- This follows a major repair outage after a forced shutdown after isolation/block valves failed – three months after commissioning following steam generator replacement. Read more
- Loading the fuel began in early September 2025, followed by commissioning activities before the unit’s successful synchronisation.
Unit 1 has been down since September last year after one of the isolation/block valves failed its three-monthly routine test. Eskom recently submitted a license change request application to the national nuclear regulator for the construction of a spent fuel cask storage area on the Koeberg nuclear power plant site. Concerns have been raised over the ageing containment buildings which have degraded over the last 40 years. Read more
Both Koeberg Unit 1 and Unit 2 are now 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.
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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 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.
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“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.
Related news: Eskom assures that safety structural steps have not been skipped at Koeberg
Author: Bryan Groenendaal
