State-owned Eskom reconnected Unit 1 at the Koeberg nuclear power station to the national grid at 01:36 on October 29, which it says marks an important milestone in further enhancing the security of South Africa’s electricity supply and returning 930 MW to service.

This follows the unit’s first scheduled major maintenance outage since the installation of new steam generators. Loading of the fuel began in early September, followed by commissioning activities before the unit’s successful synchronisation.

Eskom says both Koeberg Unit 1 and Unit 2 are currently online, with Unit 1 in the process of 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.

To maintain grid stability, Eskom notes that 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 a 99.88% year-to-date energy availability factor and is awaiting the National Nuclear Regulator’s (NNR’s) decision on its 20-year long-term operation licence on November 9.

The utility says this 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 baseload electricity to the national grid.

The maintenance, which included comprehensive inspections, safety checks and the statutory ten-year integrated leak rate test (ILRT), has ensured the unit is ready to operate safely and efficiently until its next major maintenance cycle.

Eskom says 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,” says Eskom group executive for generation Bheki Nxumalo.

In July 2024, following the successful completion of the Steam Generator Replacement Programme in November 2023, the NNR extended Eskom’s licence to operate Unit 1 until July 2044.