Eskom has confirmed that Kusile Power Station’s Unit 6 has officially entered commercial operation. This marks the successful completion of Eskom’s Build Programme and a further milestone in progress on the utility’s Generation Recovery Plan. It ends the construction of South Africa’s two ‘supercritical’ coal-fired power stations, Medupi and Kusile.
Together, these stations contribute to the country’s baseload electricity supply. With Unit 6 now online, Kusile and Medupi can deliver a combined 9 600 MW when operating at full capacity, significantly strengthening South Africa’s electricity supply.
Commercial operation signals that the unit has passed all required testing and optimisation phases and is now fully integrated into Eskom’s operational fleet. Although the unit has been supplying electricity to the grid since its synchronisation on 23 March 2025, its contribution has not been reflected in official reporting until now. Going forward, Unit 6’s output will be included in the Energy Availability Factor (EAF) calculations, one of Eskom’s overall performance metrics.
Bringing Kusile Unit 6 to commercial operation also represents a major step in completing one of South Africa’s largest infrastructure projects.
“The successful commissioning of Unit 6 adds 800 MW to the grid and completes our twelve-unit megaprojects fleet. We extend our gratitude to employees and contractors for their commitment and perseverance in delivering this project. Despite the many challenges along the way, the successful handover of Unit 6 reflects the team’s resilience and dedication. We look forward to the added stability these megawatts will bring,” said Bheki Nxumalo, Eskom Group Executive for Generation.
“Achieving commercial operation of Unit 6 within the planned timeframe of the Generation Operational Recovery Plan is a testament to Eskom’s disciplined execution. The completion of the Kusile build programme also reinforces Eskom’s commitment to restoring energy security, enhancing grid stability, and investing in infrastructure that supports South Africa’s long-term economic growth. Since its synchronisation in March, Unit 6 has consistently met performance benchmarks, contributed to grid reliability, and helped meet electricity demand,” said Eskom Group Chief Executive, Dan Marokane.
“Medupi and Kusile will remain central to South Africa’s electricity supply for many years to come. Both stations are designed for an operational lifespan of around 50 years. As we celebrate this milestone, we are also accelerating efforts to expand our renewable energy portfolio to complement our baseload infrastructure. This is part of our broader strategy to repower the grid and reduce overall emissions,” Marokane added.
Sustaining stable electricity supply
In a separate statement Eskom reiterated that its Generation Recovery Plan continues to deliver dividends: ensuring a more stable and consistent electricity supply, stronger plant reliability, and a month-to-date (at 26 September 2025) EAF surpassing the 70% target. It noted that the Energy Availability Factor (EAF) has fluctuated between 65% and 71%, with the month-to-date average holding above 70% at 71.15%. The last time it trended this high was in 2021.
The utility also noted that after successfully completing the refuelling process, Unit 1 at Koeberg Nuclear Power Station has begun its start-up sequence and is currently undergoing hot commissioning. This is an essential stage in preparing the unit for full operation. Once back online, it will deliver 930 MW to the national grid, bolstering the country’s electricity supply further.
Safety at Koeberg
This follows Eskom’s rebuttal of public commentary suggesting that it was ‘flying blind’ at Koeberg Nuclear Power Station. Citing that as inaccurate and misleading, Eskom confirmed that all safety-critical systems at Koeberg are fully functional, carefully monitored, and continuously improved in line with strict nuclear safety standards.
It confirmed that Koeberg’s containment buildings, the massive concrete domes designed to prevent any release of radiation in the event of an incident, have undergone rigorous structural assessments to ensure they are safe.
A modification to install new monitoring instruments to enhance monitoring of the containment building is planned for the medium- to long-term, aimed at continuous improvement and aligned with global best practices.
Eskom emphasises that it operates Koeberg with a safety-first mindset, under the strict oversight of the National Nuclear Regulator and in full alignment with international nuclear safety conventions. “Assertions that safety tests have been skipped or that Eskom is operating ‘blind’ are inaccurate, and they undermine the rigorous engineering and regulatory processes that govern nuclear operations.”
It highlights that the Integrated Leak Rate Test (ILRT) is a cornerstone of nuclear safety. This pressurises the containment to accident condition pressure to verify that the containment building is leak-tight and capable of containing radioactive release in the unlikely event of an accident. The ILRT for Unit 1 was successfully completed during Outage 127 in 2025, and the ILRT for Unit 2 is scheduled for Outage 227, in line with the 10-year testing cycle required by international standards.
The utility states that it will continue to invest in its safety systems, infrastructure, and personnel to ensure that Koeberg remains a reliable, secure, and compliant source of energy for South Africa. Eskom assures the public that the containment buildings of both Unit 1 and Unit 2 at Koeberg Nuclear Power Station are safe and fully capable of performing their intended design function.
For more information visit: www.eskom.co.za
