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Koeberg nuclear plant as seen from Melkbosstrand. Picture: SHELLY CHRISTIANS
Koeberg nuclear plant as seen from Melkbosstrand. Picture: SHELLY CHRISTIANS

Embattled power utility Eskom announced on Monday that its former COO Jan Oberholzer had resigned.

His last day with Eskom will be at the end of July.

Oberholzer, who is leaving Eskom “by mutual agreement”, returned recently to the utility after his retirement in April to oversee some of its crucial projects, including getting all units at Medupi, Kusile and Koeberg online.

He was on contract to manage the steam generator replacement project at Koeberg, which has been plagued by several delays, as well as the return to service and commissioning of Kusile and Medupi’s outstanding generation units. Oberholzer’s abrupt departure from Eskom came just hours after electricity minister Kgosientsho Ramokgopa raised alarm that unit 1 at Koeberg nuclear power station in Cape Town, which is on a maintenance outage for a steam generator replacement, will not be returned to service by mid-September as previously communicated by Eskom.

This could result in a situation where both of Koeberg’s generation units are out on maintenance outages at the same time, leaving the Western Cape vulnerable to blackouts, one energy expert said.

Koeberg’s unit 2 is expected to be shut in October for about six months for its steam generator replacement.

If unit 1 is not returned on time, this could mean that both generating units are out of service at the same time, depriving SA of an additional 920MW of much-needed generation capacity. (Units 1 and 2 each have generation capacity of 920MW — almost one stage of load-shedding of 1,000MW.)

“I have asked for a more detailed report [on Koeberg], and the more we get an indication of what the issues are the more we are getting very, very, very worried,” Ramokgopa told journalists at a press conference in Pretoria on Monday.

“Once we have an overlap of unit 1 not coming on stream and unit 2 having to be taken off [for maintenance] the net picture is that we would have lost 920MW from where we are now...

“That is a huge dent on our generating capacity.

“That is something we want to avert at all costs.”

There have been several delays in maintenance work on Koeberg. The steam generator replacement on unit 1 was originally scheduled to take place between February and June 2021, while unit 2 was scheduled for January to May 2022, but both projects were delayed until 2023.

This work is part of the critical maintenance that has to be completed for the national nuclear regulator to determine whether it will be safe to extend Koeberg’s lifespan by another 20 years when its existing operating licence expires in July 2024.

Eskom could not immediately respond to detailed questions from Business Day, but said that it would soon release a statement on the present Koeberg outage.

“However, we can confirm that all three steam generators of unit 1 have been successfully replaced and welding ... has commenced,” said Eskom.

“We would also like to assure the public that it is our commitment to ensure that we prioritise safe working standards on this project.”

Gino Moonsamy, the national nuclear regulator’s head of communications, said the internal technical review of the safety case and commitments documentation for the extension of the plant’s licence for long-term operation was in progress.

“Our board is meeting at the end of July ... after that [we] can provide more information on the next steps of [the] process,” said Moonsamy. Business Day reported in May that Eskom awaited the regulator’s decision, and the utility had begun preparing for another long-term outage at one of the units starting at the end of July.

This planned 200-day outage at unit 1 will last until February 2025, and the plant’s licence for long-term operation will have to be extended before the unit can be started up again after the outage.

Unit 2 will have to be taken offline for a similar outage, which would mean that at least one of Koeberg’s two generation units will be offline for most of the time at least until mid-February 2025 for maintenance, regardless of the regulator’s decision.

Chris Yelland, energy analyst and MD of EE Business Intelligence, said he had received information suggesting the return to service for unit 1 had been extended to mid-October.

“Normally, Eskom would want to bring unit 1 up and operate it for a period of time with unit 1 and unit 2 running to ensure unit 1 is operating in a stable manner.”

Having both units running at the same time after the maintenance outage provides a “safety buffer”, but this was likely to then lead to a delay in the unit 2 maintenance outage.

Eskom is now pinning its hopes, Yelland said, on the national nuclear regulator granting its request to separate the licences for both units, which would provide an extension for unit 2.

“Unit 2 was commissioned one year later than unit 1. Eskom is asking for separate licences, so that the licence for unit 2 will only expire in 2025,” he said.

Eskom confirmed that it has applied to the national nuclear regulator to have two separate operating licences for Koeberg, which would see the licence for unit 2 expire in November 2025, instead of July 2024.

“Eskom has not received the response as yet, but [we are] working very close with the regulator and responding to their questions,” the utility said.

If the regulator grants this request it would prevent a scenario in which both units — with a combined generation capacity of about 1,800MW — have to be taken offline at the same time for an extended period.

Should both units be offline, the Western Cape would be “quite vulnerable” because it then has to rely on a lot of power flow from the north of the country down to the south, said Yelland.

“When Koeberg is running it means that the transmission lines from the north to the south don’t have to carry as much load. But when Koeberg is down it means the whole of the Western Cape relies on imported power from the north of SA,” said Yelland.

There is some generation capacity in the Western Cape. Both Eskom’s diesel-powered open cycle gas turbines, for example, are located in the province, but these plants are expensive to operate.

“You can run the Western Cape without Koeberg, but it makes the system much more vulnerable as it leaves no redundancy to serve as a buffer if a fault occurs on an overhead transmission line,” Yelland said.

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