Both Koeberg units offline after unexpected shutdown and planned maintenance

16 Sep 2024

The Koeberg Nuclear Power Station went offline last week when Unit 1 failed a routine test and maintenance continued on Unit 2. It was still offline on Monday, when Eskom finally explained the outage — five days later.

Koeberg Nuclear Power Station’s Unit 1 has suffered an unexpected shutdown since Wednesday, 11 September. This followed a year-long refurbishment process to get the unit up to scratch for Eskom’s application to extend the power station’s lifespan by 20 years.

With Unit 2 already on a planned outage as teams continued to deal with the steam generator replacement and welding work needed for its lifespan extension application, the Unit 1 outage meant Koeberg was fully offline — a potentially dangerous situation for grid stability in the Western Cape.

Eskom had planned to take Unit 1 offline in January 2025 for refuelling and maintenance. The current outage was unplanned and before Daily Maverick’s enquiry on Monday, Eskom had not publicly addressed it.

On Monday night, five days after the outage and with mounting public criticism over Eskom’s lack of transparency, the power utility reported that Koeberg’s Unit 1 was “conservatively and safely” shut down on 11 September after one of the isolation/block valves failed its routine three-monthly test.

Eskom spokesperson Daphne Mokwena said: “The unit was shut down in order to restore redundancy of the steam pressure relief system in line with the operating technical specifications. At no point was the safety of the plant, staff, public or environment at risk.”

She said the unit was being safely returned to service and that the issue had no impact on the suspension of load shedding.

Mokwena said Eskom had notified all the relevant stakeholders “as per the stringent protocols” and had sufficient emergency reserves to handle any sudden changes in demand during peak periods.

Concerns raised

Civil society groups opposed to the extension of Koeberg voiced concern at the lack of communication from Eskom.

During a parliamentary briefing this month, Eskom announced that the long-term operation (LTO) project for Unit 1 at Koeberg had been completed.

Read more: Safety concerns, rising costs, inadequate socioeconomic studies mar Koeberg life extension plans

This was after a year of shutdowns and delays in the plant’s upgrades for the LTO.

At the parliamentary briefing, Eskom said the unit had been operating continuously since it returned to service in December.

On 15 July, the National Nuclear Regulator (NNR) granted Eskom a licence to continue operating Koeberg Unit 1 until 21 July 2044.

Eskom also announced that it was preparing to apply for Unit 2’s extension, with the NNR set to make its decision by 9 November 2025 when the licence for the unit expired.

The NNR renewed Eskom’s operating licence for Unit 1 for a further 20 years despite a flood of submissions from civil society groups and community members concerned about the secrecy surrounding the process, the rush caused by Eskom missing deadlines for submitting information about the life extension application and the ability of Eskom to operate the plant safely and to evacuate residents in case of a severe incident.

The recent outage has rekindled the debate about the life extension plans for Koeberg and opposition to the licence renewal of Unit 1. The NNR responded that anyone opposed to the decision could follow the legal process of appealing.

Karel Beukes, a resident of Tweerivier — which is 55km from the Vaalputs nuclear waste disposal site — appealed, with other residents, to Electricity and Energy Minister Dr Kgosientsho Ramokgopa to reverse the 20-year extension.

“The NNR decision increases the perception of the public that they are solely looking after their interests. The public in the Kamiesberg areas are sick and tired of the clandestine manner in which Eskom and the NNR operate, and we demand transparency when it comes to decisions that affect us,” Beukes said in a statement shared by the Koeberg Alert Alliance (KAA).

Read more: Koeberg Unit 1 can operate until 2044 despite concerns, says nuclear regulator

System vulnerable

Chris Yelland, the managing director of EE Business Intelligence, said that Unit 1 being shut down while Unit 2 was also offline was not a good situation.

“Not only because it puts pressure on outages, but also because the power system needs a certain amount of generation in the Western Cape for system stability. They really do not like running with both units off because it makes the system vulnerable.

“If they had an overhead line fault at this sort of time, on one of the major overhead lines feeding Cape Town, if that were to trip out now, you would probably have a blackout in the Western Cape,” he said.

“You have to organise contractors and people; it’s a major deal when you have to induce an outage on a nuclear reactor and it has to be very carefully planned.”

Yelland said the fact that the unit had been offline since Wednesday meant this was probably not a trivial matter.

He said Eskom’s explanation, “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”.

The outage comes less than a week after a “nuclear seminar”, hosted by Ramokgopa on 12 September, where nuclear energy was heralded as a pivotal component of South Africa’s energy mix, “offering a low-carbon, reliable source of electricity that can contribute significantly to the country’s energy security and climate goals”.

KAA spokesperson Lydia Petersen said, “If Ramokgopa’s advice is to be followed, this latest outage indicates what we should expect from nuclear power in South Africa: repeated unexpected outages in addition to constantly shifting completion dates and ongoing deception of the public of the actual costs involved.”

Petersen said the outage raised questions about whether the necessary upgrades and safety improvements for long-term operation at Koeberg had been fully addressed.

Maia Nangle, the campaign coordinator for the Southern African Faith Communities Environmental Institute, said the absence of communication from Eskom about the outage was concerning, and indicative of the lack of transparency and accountability on nuclear energy from the government. DM

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Concerns raised

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