Eskom Koeberg City of Cape Town

Koeberg Nuclear Power Station in Cape Town. Image: Creative Commons/Philipp P. Egli

Eskom shuts down Unit 1 of Koeberg Nuclear Power Station – here’s what you need to know

Unit 1 at Koeberg Nuclear Power Station will be offline until June 2023 and SA’s power grid will lose about 920MW of capacity as a result.

Eskom Koeberg City of Cape Town

Koeberg Nuclear Power Station in Cape Town. Image: Creative Commons/Philipp P. Egli

Eskom said the long-term operation project of Unit 1 at the Koeberg Nuclear Power Station in Cape Town started on Wednesday night, 7 December. The operation is part of the utility’s plans to extend the operating life of the continent’s only nuclear power station.

UPDATE: Koeberg Unit 1 outage delayed to ‘stabilise the system’



Eskom announced that the maintenance shutdown at Koeberg was delayed, on Thursday morning. It will now be taken offline on Saturday morning.

The decision to delay was taken over fears that the loss of Koeberg’s generating capacity could push load shedding to unprecedented levels.

Energy expert Ted Blom accused the power utility of misleading the public by failing to declare that they had delayed the Koeberg switch-off.

In January 2022, Unit 2 at Koeberg was taken offline after 450 days of uninterrupted operation for “regular refuelling and maintenance.” That outage was scheduled for five months.

“This will be the 25th refuelling outage on Unit 2 since commissioning and will also see the replacement of the unit’s three steam generators.

“During this outage, the reactor pressure vessel head, which houses the nuclear fuel while the station is in operation, will also be replaced,” said Eskom.

The December operations will see Unit 1 shut down for regular maintenance and refuelling. Three steam generators (SGR) will also be replaced. Eskom said Unit 1’s reactor pressure vessel head was replaced years ago.

Eskom COO, Jan Oberholzer, said the Unit 1 outage is expected to last until June 2023. This means 920MWe of capacity will be unavailable in the coming months.

Each unit at the nuclear power station delivers about 920MWe to the national power grid, which is dominated by coal. When it is running at full steam, Koeberg provides approximately 5% of South Africa’s electricity.

Image: Eskom.

Eskom initially estimated that the work could be completed in 120 to 150 days. This was increased to 180 to 200 days after consultation with nuclear power company Framatome, which pulled off a similar steam generator replacement in the United States earlier this year.

“They’ve done it many times before so I asked them what is a realistic period to replace steam generators and they asked me what was in our plan … and they said there’s no way you can do it [in that time frame],” said Oberholzer at Eskom’s State of the System briefing on 15 November.

The work done at Koeberg is part of Eskom’s plan to extend the plant’s lifespan for another 20 years. The current operating licence expires in 2024-2025.

According to Nuclear News, Eskom submitted its formal application to extend the operating licence to South Africa’s National Nuclear Regulator in 2021 and submitted its safety case for long-term operation in support of the application earlier in 2022.

The nuclear regulator has two years to consider the application and provide an outcome. No safety concerns have been identified, and it is likely that the licence to operate beyond 2024 will be provided.

The power utility announced that Stage 6 load shedding would be implemented until Friday, 9 December and suggested that power cuts will be part of daily life for the foreseeable future due to a number of factors, including the Koeberg project.

READ: Confirmed: Stage 6 load shedding until Friday, Stage 5 after that

“The refuelling and maintenance outage starting tonight, as well as the long-term operation project of Unit 1 of the Koeberg Nuclear Power Station, together with the October chimney failure that has forced three generation units offline at Kusile Power Station, will further reduce available generation capacity and exacerbate the occurrence of load shedding over the next 6 -12 months,” said the utility on Wednesday.