Koeberg Nuclear Power Station’s Unit 1 was taken off the electricity grid shortly before 1am on Friday after a turbine trip, Eskom has confirmed.
The power utility said the shutdown was carried out safely and in accordance with established operating procedures.
The cause of the turbine trip is now being investigated.
Eskom stressed that the incident did not result in any threat to nuclear safety and that the station remained under stable operating conditions throughout the event.
Nuclear Protection Systems Operated as Designed
According to Eskom, monitoring systems at Koeberg confirmed that the plant remained stable after Unit 1 was removed from service.
The utility said the station’s safety, protection and monitoring systems responded as intended, ensuring that the unit remained in a safe condition.
Eskom also sought to reassure employees, nearby communities and the wider public that there was no danger associated with the incident.
The utility said nuclear safety was not compromised and that there was no risk to workers, members of the public or the environment.
Power Grid Remains Stable
The loss of Unit 1’s generation capacity is not expected to threaten South Africa’s electricity supply, Eskom said.
The utility maintained that sufficient generation capacity is available elsewhere and that the national grid remains stable and secure.
The assurance comes as Eskom continues to manage the country’s electricity system while maintaining critical generation assets at its power stations.
Unit 1 Had Recently Completed Major Maintenance
Koeberg Unit 1 last underwent major maintenance before returning to service in October 2025.
Eskom said the unit subsequently operated reliably before its generation was temporarily reduced in August 2026 as a precautionary measure.
That earlier reduction was connected to difficulties involving seawater intake at the station’s cooling water system.
Sardine Influx Complicated Seawater Intake
The precautionary reduction in Koeberg’s output came amid an influx of sardines in the waters near the power station.
The large concentration of fish created challenges for the seawater intake system used as part of the plant’s cooling infrastructure.
At around the same time, increased sardine mortality was reported along parts of South Africa’s southwestern and West coasts.
However, Eskom said there is currently no evidence demonstrating that the sardine deaths were caused by Koeberg’s operations.
Government Investigation Into Sardine Deaths Continues
The circumstances surrounding the reported sardine mortality remain under investigation by several government agencies.
The Department of Forestry, Fisheries and the Environment is leading an inter-agency investigation into the matter.
Eskom emphasized that the investigation into the turbine trip is separate from the ongoing inquiry into the sardine incidents, while noting the recent challenges involving the station’s seawater intake.
The utility said it would continue cooperating with relevant authorities and provide additional information as more facts become available.
Eskom Promises Updates on Turbine Investigation
The immediate focus at Koeberg is now determining why Unit 1 experienced the turbine trip.
Eskom said the investigation remains underway and committed itself to providing updates as information is confirmed.
The utility’s emphasis on transparency comes as the incident draws attention because Koeberg is South Africa’s only nuclear power station and a key component of the country’s electricity generation system.
No Immediate Threat to Electricity Supply
Despite Unit 1 being offline, Eskom said South Africa’s electricity system remains secure.
The utility’s assessment is that the available generation fleet can absorb the temporary loss of the unit without putting the national grid at risk.
The situation will nevertheless be monitored as investigators determine how long Unit 1 will remain unavailable and what corrective measures may be required.
What’s Next?
Investigators will work to establish the precise cause of the turbine trip before the unit can return to normal operation.
Eskom is expected to continue monitoring the station and assess the condition of Unit 1 while maintaining its commitment to nuclear safety and operational procedures.
Meanwhile, the separate government-led investigation into sardine deaths along the southwestern and West coasts will continue, with authorities yet to establish any connection between those incidents and Koeberg’s operations.
Impact and Consequences
The immediate impact of the shutdown is the temporary removal of Unit 1’s generation capacity from the national grid.
Eskom, however, has indicated that other available generation is sufficient to maintain grid stability.
More broadly, the incident highlights the importance of strict monitoring and safety systems at nuclear facilities, particularly when unexpected equipment events occur.
Koeberg’s ability to safely take Unit 1 offline without compromising nuclear safety demonstrates the role of its protection and monitoring systems in managing operational disruptions.
Summary
Koeberg Nuclear Power Station’s Unit 1 was safely taken offline shortly before 1am following a turbine trip, with Eskom launching an investigation into the cause.
The utility said plant conditions remained stable, nuclear safety was never compromised and there was no danger to workers, the public or the environment.
Eskom also confirmed that the unit’s temporary absence from the grid does not pose a threat to South Africa’s electricity supply.
The development follows earlier precautionary reductions in Koeberg’s generation linked to seawater intake challenges caused by a sardine influx.
The turbine incident remains under investigation, while a separate government inquiry continues into reported sardine deaths along South Africa’s southwestern and West coasts.
