Koeberg Unit 1 returns to service, boosting national grid with 930MW

Eskom has successfully reconnected Unit 1 at the Koeberg Nuclear Power Station to the national grid on Wednesday, marking a major milestone in strengthening South Africa’s baseload power supply, improving the Energy Availability Factor (EAF), and enhancing energy security. According to the power utility, the unit’s return adds 930 MW of electricity to the grid following its first scheduled major maintenance outage since the installation of new steam generators. Fuel loading began in early September, followed by commissioning activities leading up to the unit’s successful synchronisation. Both Koeberg Unit 1 and Unit 2 are now online with Unit 1 ramping up output and Unit 2 currently generating 941 MW. Once Unit 1 reaches full capacity, the two units will jointly supply more than 1 860 MW, representing about 5% of Eskom’s total electricity output. Koeberg remains the largest nuclear power station on the African continent. “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. Eskom said Koeberg’s maintenance outages are carefully staggered every 16 to 18 months to ensure that both units are never offline at the same time. Unit 2 has been operating at full capacity for 234 days with a 99.88% year-to-date EAF, and is awaiting the National Nuclear Regulator’s (NNR) decision on its 20-year long-term operation licence, expected on 9 November 2025. “The maintenance programme for Unit 1 included comprehensive inspections, safety checks, and the statutory 10-year Integrated Leak Rate Test (ILRT), which confirmed the containment building’s structural integrity and compliance with international nuclear safety standards,” said Eskom. Eskom said the successful completion of the maintenance programme reaffirms its commitment to the safe, reliable, and efficient operation of the country’s only nuclear power station, which supplies clean, cost-effective 24/7 baseload electricity. In July 2024, following the completion of the Steam Generator Replacement Programme in November 2023, the NNR extended Eskom’s licence to operate Unit 1 until July 2044, allowing it to continue generating over 930 MW of dependable, low-carbon power for the next two decades.