Further Koeberg delay worsens South Africa’s power outlook

Eskom is planning a further 200-day shutdown of the reactor at its Koeberg nuclear power station, which is currently offline for maintenance, refuelling and refurbishment in preparation for a 20-year life extension.

This latest shutdown of Unit 1 at Koeberg is due to begin on 24 July 2024 – just three days after the current 40-year operating licence for the power station expires on 21 July 2024.

Each of the two units at Koeberg – Unit 1 and Unit 2 – has a rated capacity of 970 MW. The further outage of Unit 1 will, therefore, remove about 900 MW from the grid for another 200 days.

This is equivalent to nearly one stage of load-shedding at a time when the electricity supply in South Africa is already severely constrained.

Eskom is in a race against time to meet the stringent requirements for extending Koeberg’s operating licence before the deadline of 21 July 2024, when the independent National Nuclear Regulator (NNR) will have to decide whether Koeberg is able to safely operate for another twenty years.

The latest planned shutdown means that Unit 1 will not be operating from 24 July 2024 until mid-February 2025 and suggests that the continued operation of Unit 1 after the deadline will be delayed.

This shutdown of Unit 1, referred to in Eskom parlance as “Outage 127” – the 27th major outage of Unit 1 since its commissioning some 39 years ago in 1984 – was revealed in a briefing by Eskom to the Parliamentary Portfolio Committee on Mineral Resources & Energy on 9 May 2023, where Eskom stated in a slide that:

“The Unit 1 outage 127 has been scheduled to start on 24 July 2024, which provides some additional time for the NNR to complete their reviews, as the issuing of the LTO (long-term operation) licence for Unit 1 is technically needed to allow fuel to be re-introduced into the reactor.”

Eskom further indicated to EE Business Intelligence on 12 March 2023 that:

“The current licence for operating Koeberg expires on 21 July 2024 unless varied, suspended or revoked by the National Nuclear Regulator (NNR). Although the licence application and safety case in support of long-term operation (LTO) has been submitted to the regulator within the prescribed time-frames, Eskom has opted to commence the start of the outage for Unit 1 in line with the expiry date of the licence (this is not related to refuelling). The licence has to be extended for LTO before we can start up the plant after outage 127. The outage is planned to be of a 200-day duration as per the currently approved production plan.”

From the above, it would appear that Koeberg Unit 1 will only resume operation after its licence is extended by the NNR, and after a further 200-day outage of Koeberg Unit 1 starting on 24 July 2024 and ending mid-February 2025.

Extension of Koeberg’s licence for long-term operation (LTO)

The outage currently underway on Unit 1, known as outage 126, began on 10 December 2022 and included maintenance, refuelling, replacement of three steam generators and other life-extension work.

Although it is running some 45 days late, Unit 1 is expected back online again in August 2023 and can continue operating while Unit 2 is taken offline to replace its steam generators. If all goes well on Unit 1, the outage on Unit 2 will begin in October 2023, for completion by about April 2024.

To manage the risk in the event of delays in the steam generator replacement on Unit 2, Eskom has, in the meantime, applied to the NNR to have two separate operating licences for Koeberg – one for Unit 1, where the licence would expire on 21 July 2024, and the other for Unit 2 where the licence would expire on 21 July 2025.

This may be possible because Units 1 and 2 were commissioned and commenced operation a year apart, in 1984 and 1985, respectively. Eskom says it is confident that the NNR will agree to the two separate licences as above, but the decision by the regulator is still awaited.

It is not immediately clear why Eskom and/or the NNR would require yet another 200-day shutdown. However, Eskom has indicated to EE Business Intelligence that:

“Outage 127 is a planned long-duration maintenance outage (in accordance with our production plan) which will be of 200 days duration, wherein we are planning to perform identified maintenance and inspection activities including, for example, the routine 10-yearly containment integrated leak rate test”.

It has been previously indicated to EE Business Intelligence that corrosion of steel reinforcing (rebar) under coastal conditions is resulting in cracks in the concrete of the nuclear reactor containment silos, and that this requires ongoing maintenance and repair work.

Perhaps it is this work, and the associated inspections and testing, that is required during the further outages 127 and 227 on Units 1 and 2 before the reactors can resume long-term operation for a further 20 years.

The details and timing of a similar further outage 227 for Koeberg Unit 2 have not been clarified by Eskom yet.


The initial budget for the life-extension project at Koeberg, approved by the Eskom board in 2010, is said to have been about R20-billion at the time. Eskom now insists that the actual capital cost in today’s money some 13 years later and after all the project delays is only about R22-billion.

However, the total capital cost of the Koeberg life-extension project is particularly murky, and will likely never be known publicly.

This is because many of the capital costs, such as the replacement of the reactor head on Unit 1, and several other plant replacements and refurbishments (such as switchgear, transformers, control systems, and more) have been treated by Eskom as normal routine maintenance, and expensed.

But these costs all pale to insignificance when considering the cost to the South African economy of 900 MW from Koeberg being out of service and unavailable for duty for a total of about 28 months during the life-extension works, at a time of severe stage 4 to stage 6 load shedding in South Africa.

Based on an estimated cost of unserved energy of R30 per kWh, the cost of not having 900 MW of continuous power from Koeberg when needed by the productive economy for 28 months is conservatively estimated at some R500-billion.


The life-extension initiative for Koeberg has also been bedevilled by mismanagement and delays since first conceived by Eskom in 2008, and after formal approval of the strategy by the Eskom board in 2010.

Eskom identified three major life-limiting components – steam generators, refuelling water storage tanks and reactor pressure vessel heads – that needed to be replaced.

In 2012, the steam generator replacement project contract was stopped, and the whole process restarted. A new contract was signed in 2014 with French nuclear contractor Areva, subsequently renamed Framatome, and now controlled by the French national utility, Électricité de France (EDF).

Following a long legal battle around allegations of corruption and maladministration, the steam generator replacement contract with Areva was finally confirmed after the dispute with the losing bidder, Westinghouse, proceeded to the Constitutional Court.

As a result of the legal action, the replacement of the steam generators was rescheduled for planned outages in 2018. The steam generator replacement was then subsequently further delayed to outages in 2021 due to steam generator manufacturing defects experienced by Areva/Framatome in France.

After Areva/Framatome was unable to continue with the manufacturing of the steam generators in France, the uncompleted forgings were then flown to China, only to be scrapped after further inspection, in what was described by a former chief nuclear officer of Eskom as “the most expensive transport of scrap metal in the history of humankind”.

The manufacture of the steam generators, therefore, had to start again from scratch in China, and the installation on-site at Koeberg was subsequently again deferred to outages 126 and 226 in 2023 and 2024 due to several challenges on the part of Eskom and the contractor alike.

The refuelling water storage tanks and the reactor pressure vessel heads at Koeberg have now been replaced, and the steam generators on Unit 1 are currently being replaced.

The replacement of the steam generators on Unit 2 will begin in the latter part of 2023 during the upcoming outage 226 scheduled start in October for completion in about April 2024.

By Chris Yelland, EE Business Intelligence


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