State-owned electricity utility Eskom has confirmed that Unit 2 at the Koeberg nuclear power station was returned to service at 20:24 on Sunday, August 7.

“The unit is currently loading and will require about ten days to reach full output,” spokesperson Sikonathi Mantshantsha confirmed in an emailed response to an Engineering News enquiry.

The 920-MW unit was shut for refuelling and extended maintenance on January 18 and was initially scheduled to return to service in June.

The extended maintenance was also meant to have included the replacement of three steam generators, but the replacement was deferred to August 2023 following an assessment, conducted together with Framatome, which concluded that Eskom was not ready to implement the project.

The deferral did not lead to any shortening in the duration of the outage, despite the fact that it accounted for one stage of load-shedding every time the utility has resorted to rotational power cuts since January.

The outage coincided with the most intensive period yet for load-shedding, with Eskom having even resorted to Stage 6 cuts during a wildcat strike in late June and early July, which affected a number of its coal stations.

Despite the smaller scope of the shutdown, the date for returning Unit 2 to service was initially shifted to mid-July, then the end of July and finally into August.

The steam generator replacement (SGR) programme is also key to Eskom securing a Long-Term Operations licence from the National Nuclear Regulator (NNR) to extend the life of the plant by a further 20 years. The licence is currently due to expire in July 2024.

The application to extend the operational life was submitted by Eskom on May 10, 2021, and accepted by the NNR for further processing on August 17, 2021. On July 26 this year, the NNR confirmed that Eskom had submitted the safety case in support of its application to extend Koeberg’s operational life.

The replacement of the Unit 1 steam generators, meanwhile, is still planned to take place during the unit’s upcoming extended maintenance, scheduled for December. However, concerns have already been raised about Eskom’s readiness for that outage.

These concerns coincide with major changes to the leadership at Koeberg, with Eskom announcing in early July that Mahesh Valaitham would act as Koeberg power station GM, owing to the fact that the current acting GM, Nomawethu Mtwebana, had been selected to join the World Association of Nuclear Operators, which is based in the US, as a reverse loanee for the next year.

In addition, Eskom chief nuclear officer Riedewaan Barkadien departed the organisation at the end of July, with Keith Featherstone acting in the position while a recruitment process was undertaken.

COO Jan Oberholzer has stated previously that the deferral of the Unit 2 SGR programme was “not ideal”, as it would not take place close to the expiry of the unit’s licence.

“[The delays have] unfortunately created a situation that we are cramping what needs to happen for the long-term operation of Koeberg right until the end, and that means that the risk obviously is increased.”