South Africa’s nuclear power plant lands 20-year extension — but expect more outages

The National Nuclear Regulator (NNR) recently granted Koeberg’s Unit 1 generator a licence to continue operating for the next 20 years, but the power station’s two units will seldom run together for the foreseeable future.

Eskom is currently conducting the same maintenance on Koeberg’s Unit 2 generator for a similar operating licence extension, the major component of which is the replacement of its steam generator.

However, the NNR previously said they will each face further, separate 200-day outages once this work is complete.

The extension of Koeberg Unit 1’s operating licence means the nuclear generator, which can produce up to 970MW of energy, will remain in operation until 21 July 2044.

In its announcement, Eskom alluded to a further outage, saying it will run the unit until January 2025, before taking it offline for refuelling and further maintenance.

Eskom chief nuclear officer Keith Featherstone said the power station had implemented safety improvements identified through both French and US nuclear experiences.

This helped Eskom reduce risk to levels normally only achieved by modern nuclear power plants.

During a media briefing in April 2023, programme manager for nuclear power stations at the NNR, Peter Bester, said the further outages will take place for containment pressure testing.

“For the next foreseeable years, there will be seldom both units operating at the same time,” said Bester.

“The next outage starting on unit 2 is the steam generator replacement outage, which is the same that has been completed on unit 1.”

“It will also be followed by a 200-day outage, which will happen at the end of next year,” he added.

The work on Koeberg Unit 1 faced several delays. It was taken offline for its steam generator replacement in December 2022, with an estimated return date of July 2023.

However, it was only synchronised to the grid again in December 2023.

At the time, energy and electricity minister Kogsientsho Ramokgopa said Eskom had learnt from the delays and challenges experienced with Koeberg Unit 1, which would allow the work on Unit 2 to be completed on time.

“We are taking out 980MW by tomorrow, and of course, unit 1 is almost at full load,” said Ramokgopa.

“Now we are taking out unit 2 for the same purpose. I spoke to the team and said we have learnt from the mistakes and shortcomings relating to unit 1.”

“We asked them to keep to the timelines of returning unit 2,” he added.

In February 2024, Eskom told MyBroadband that the work on Keoberg’s Unit 2 generator was progressing well and that it expects the reactor to return to service by the end of September 2024.

If this projection proves accurate, Koeberg Unit 2’s steam generator replacement will have been completed in under ten months, or about a month quicker than Unit 1.

While there are concerns over the safety risks associated with running the ageing reactors, Eskom has dismissed these.

Neil Overy, a Research Associate in Environmental Humanities at the University of Cape Town, said Eskom is bankrupt and accused it of cutting corners by foregoing critical updates at the power station.

He said Eskom had avoided certain “non-negotiable” upgrades, including installing a core catcher, during its maintenance work on Koeberg’s reactors.

While Eskom didn’t directly deny his claims, it listed a range of safety improvements it had implemented.

Modifications included replacing refuelling water storage tanks, reactor vessel beds, the turbine protection and control system, and the reactivity control rod system.

Eskom also upgraded Koeberg’s radioactivity monitoring system and the spent fuel cooling system.

“Koeberg has committed to further safety improvements by investing in additional seismically robust cooling water supplies and improved reactor cooling pump seals, to name a few,” it said.

Eskom added that defects in the containment structures have been repaired, and it was determined that the crack in the dome of the containment building doesn’t impact its structural integrity.

It added that the crack had been sealed and painted over.