Eskom quietly shuts down 980MW Koeberg unit

Eskom has confirmed that it shut down Koeberg’s Unit 1 generator on Wednesday, 11 September 2024, with the power utility taking it offline while Unit 2 is offline.

This is according to energy expert Chris Yelland, who slammed the power utility and the country’s nuclear regulator for a lack of transparency over the shutdown.

“Five days after Koeberg Unit 1 has been shut down due to a fault on Wednesday last week, at the same time that Koeberg Unit 2 was also offline, Eskom finally admits the shutdown after this was being exposed in the media and public domain,” said Yelland.

“Coming five days after Unit 1 went offline while Unit 2 is offline too, shows a complete lack of transparency and a level of contempt for the interests and concerns of the public by Eskom and the National Nuclear Regulator.”

He shared feedback from Eskom, explaining that Unit 1 was conservatively and safely shut down on Wednesday after one of its block valves failed its three-monthly routine test.

“The unit was shut down in order to restore redundancy of the steam pressure relief system in line with the operating technical specifications,” the power utility said.

“The intervention has been completed, and the unit is in the process of being safely returned to service. All stakeholders who were required to notify were informed as per the stringent protocols.”

Eskom said the shutdown has not impacted its load-shedding suspension, adding that its summer outlook remains in force.

Koeberg’s Unit 1 generator returned to service in November 2023 following an extensive maintenance outage to replace its steam generators and conduct long-term refuelling. The original plan was for the unit to return to service by June 2023.

Although unintended, the outage lasted nearly a year due to several delays experienced throughout the process.

Eskom successfully completed Koeberg’s final test — the full load rejection test — on 30 December 2023.

The replacement of Koeberg’s generation units’ steam generators is critical for extending the life of the nuclear power station, which contributes nearly 2,000MW of capacity to the national power grid.

Following Eskom’s recent maintenance to Unit 1, the National Nuclear Regulator granted it a 20-year operating licence extension in July 2024.

The second generator is currently offline for a similar scope of work. It was taken offline in December 2023.

After completing Unit 1’s full load rejection test, Eskom said the results are encouraging, considering that the same work must be done on Unit 2.

“The successful completion of the test serves as an encouragement as Eskom plans to undertake similar steam generator replacement activities on Unit 2,” the utility said.

In December 2023, South Africa’s Electricity and Energy Minister, Kgosientsho Ramokgopa, said Eskom had learnt from the mistakes it made with Unit 1’s maintenance that caused several delays.

“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,” said Ramokgopa.

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

Koeberg Nuclear Power Station’s generating units will each face a further 200-day outage following the replacement of Unit 2’s steam generators.

The National Nuclear Regulator confirmed the need for further outages in early December 2023.

The two separate 200-day outages will allow Eskom to test the reactors’ concrete containment structures, which some claim are starting to show cracks.

“For the next foreseeable years, there will be seldom both units operating at the same time,” said Peter Bester, programme manager for nuclear power stations at the NNR.