Eskom gets green light for Koeberg unit 1 — what it means for load-shedding

Myles Illidge

Eskom has received permission to run Koeberg Power Station’s unit 1 reactor, but according to University of Pretoria professor David Walwyn, it won’t do much to address South Africa’s energy crisis.

While the unit’s return is a significant milestone for Eskom, it will only add 920MW to the grid at full capacity, which Walwyn says will temporarily reduce load-shedding by approximately one stage.

“Unit 1 has an output of about 1GW, and we need altogether about 30GW in the system. For every gigawatt that we are missing, that’s one stage of load-shedding,” Walwyn said in an interview with Newzroom Afrika.

“So when we get unit 1 back, that will be one stage of load-shedding less. At the moment, we have [stages] 2 to 3, we would be at [stages] 1 to 2 if unit 1 was fully operational.”

Moreover, this benefit will only be in effect temporarily until Unit 2 is taken offline to have its steam generators replaced.

“The capacity that we’ve been relying on from Koeberg Unit 2 will now be replaced by Unit 1, and Unit 2 will be taken offline,” said Walwyn.

Eskom recently told MyBroadband that the replaced steam generators were operating correctly. However, Walwyn believes there is another critical check that should take place before its synchronisation.

“There’s also another very important check that needs to be made at Koeberg — and that is the check of the integrity of the concrete shell that encases the building, which is there to protect us from the worst of a nuclear accident,” said Walwyn.

“God forbid that there would be a nuclear accident, but that concrete shell around Koeberg is a first line of defence against anything that might happen.”

“There are reports that the casing has cracks in it and may need to be significantly reconstructed,” he added.

Walwyn said Eskom could technically apply for the extension of Koeberg unit 1’s operating licence once it has synchronised to the grid rather than waiting for the refurbishment of unit 2 to be completed.

“Eskom is hoping to be able to separate the licence for unit 1 from unit 2, do the refurbishment of unit 2, and then apply for the renewal of unit 2’s licence,” he said.

While Eskom has been given the green light to take the reactor critical, its technicians found emergent issues on the turbine side of the plant.

On Tuesday, 14 November 2023, energy expert Chris Yelland said Eskom’s chief nuclear officer Keith Featherstone had indicated that the National Nuclear Regulator (NNR) gave it the go-ahead “to take the reactor critical.”

“A reactor achieves criticality (and is said to be critical) when each fission event releases a sufficient number of neutrons to sustain an ongoing series of fission events,” said Yelland.

“Featherstone says that Eskom is attending to the problems on the turbine side of the nuclear plant, but did not give any indication as to when Koeberg Unit 1 would be re-synchronised to the grid or deliver full power.”

In early November 2023, Eskom told MyBroadband that the replaced steam generators in unit 1 had been tested and were working correctly.

“The new steam generators are already successfully performing their role,” it said.

“The delays currently being experienced are associated with the normal start-up of the Unit and not the steam generators.”

MyBroadband also asked Eskom if it was confident that both units would be up and running in time to renew Koeberg Power Station’s operating licence.

It responded with an emphatic “yes”.