Eskom’s Koeberg headache 

Eskom is adamant that Koeberg’s units will not be offline simultaneously for maintenance. However, there have been multiple delays in replacing the steam generators of the nuclear plant’s units, with an expert estimating units will be offline simultaneously for four months.  

Business Day reported that Eskom’s chief nuclear officer Keith Featherstone assured the media there would be no overlap between the outages of Koeberg’s two units. 

Koeberg has two generating units capable of producing 920 MW each, roughly equivalent to one stage of load-shedding per generating unit.

The nuclear power plant is being refurbished to extend its operating life, with the steam generators in both units set to be replaced. 

The steam generator replacement on Unit 1 was initially supposed to occur between February and June 2021, while the replacement on Unit 2 was set to occur between January and May 2022. However, both projects were delayed to 2023.

The refurbishment was set to begin in January 2022, but numerous delays meant it only started in mid-December 2022. 

Unit 1 has been out of service since then, and its refurbishment was set to be completed by July, with Unit 2 going out in September. 

Electricity Minister Kgosientsho Ramokgopa said he is “very, very worried” that the refurbishment is behind schedule at a recent media briefing. 

“It is something that requires urgent attention. Once we have an overlap of Unit 1 not coming onstream and Unit 2 had to be taken out, the net result will be that we will have lost another 920 MW.”

Koeberg’s operating licence expires in July 2024, after which it must close unless the plant has been refurbished and relicensed. 

The National Nuclear Regulator  (NNR) will determine whether it is safe to extend the life of Koeberg by another 20 years after the refurbishment has been completed or the licence expires. 

Unit 2 will have to be taken offline in October as its steam generator will take six months to replace. 

However, although the steam generator replacement at Unit 1 is complete, it will only be commercially available in early November. 

Unit 2’s replacement process has been delayed to 7 November. Featherstone admitted that Eskom had been too optimistic about installing the steam generators at Unit 1. 

“We overestimated how well we could perform. It has taken us a lot longer than we wanted,” he said. 

Energy analyst Chris Yelland

According to energy analyst Chris Yelland, Eskom’s projections for the return to commercial operation of Koeberg Unit 1 are overly optimistic. 

He is concerned that Eskom may run into problems as it brings Unit 1 back online and that there could be an overlap between the outages of Unit 1 and Unit 2.

Yelland noted that the shutdown of Unit 1, which started in December 2022, has already taken 10-and-a-half months, compared with the initially planned five months. 

It is realistic to assume that the shutdown of Unit 2 will take a similar amount of time, meaning both units could be down simultaneously for about four months in late 2024.

This would be a significant problem for South Africa’s power grid, as Koeberg is a major source of electricity. 

Yelland called on Eskom to be more realistic about its projections and to take steps to mitigate the risk of overlap between the outages.

Koeberg’s operating licence is set to expire at the end of July next year, and the replacement of Unit 2’s steam generators is unlikely to be completed by then. 

Thus, Eskom has applied to the NNR to have separate operating licences for Koeberg Unit 1 and Unit 2 and to extend the operating licence of Unit 2 for 18 months. 

Should this be granted, a simultaneous shutdown of both units could be reduced to two months, down from the anticipated four, said Yelland.


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