Eskom’s Koeberg shutdown possible

The return of Eskom’s only nuclear power plant to service has been hit by further delays as the already delayed re-synchronisation of Koeberg Unit 1 did not happen on 30 October as planned, increasing the likelihood the plant may have to shut down completely.  

Energy analyst Chris Yelland revealed this in a social media post, explaining that this is not the first delay Eskom has experienced in returning Koeberg to service after the replacement of its steam generators. 

Koeberg has two generating units capable of producing 920 MW each, roughly equivalent to one stage of load-shedding per generating unit.

The nuclear power plant is being refurbished to extend its operating life, with the steam generators in both units set to be replaced. 

The steam generator replacement on Unit 1 was initially supposed to occur between February and June 2021, while the replacement on Unit 2 was set to occur between January and May 2022. However, both projects were delayed to 2023.

The refurbishment was set to begin in January 2022, but numerous delays meant it only started in mid-December 2022. 

Keith Featherstone, Eskom’s chief nuclear officer, confirmed on 19 October 2023 that there would be a further approximately 10-day delay in the return to commercial operation of the 970 MW Unit 1 at Koeberg.

Eskom has previously extended the expected date for the return to service of Unit 1 several times from the initial indicated completion date of mid-June 2023. 

Unit 1 was expected to be synchronised to the grid by 30 October 2023 and to return to commercial operation at full output by 13 November 2023.

However, Yelland said that the re-synchronisation of Unit 1 did not occur as expected on October 30. He said that there is a chance it will happen next week instead. 

Importantly, this will have the knock-on effect of delaying the refurbishment of Koeberg’s Unit 2, as Eskom does not want to have both Units offline simultaneously. This would mean a complete shutdown of Koeberg. 

Due to the delay in returning Unit 1, Yelland said Unit 2 shutdown may happen by 24 November and not by 15 November as expected.

Yelland has said previously that this will increase the risk of Koeberg’s operating licence, which expires on 21 July 2024, not being renewed by the National Nuclear Regulator (NNR). 

Eskom has indicated that even after the 9-month outage of Unit 1 in 2023, it still needs to conduct a series of overpressure tests on the concrete containment building. 

The containment building is an essential safety structure intended to contain nuclear radiation in the event of an accident or melt-down of the nuclear reactor.

It has previously been reported that in the past 40 years of operation, significant cracks have appeared in the concrete of the containment buildings at Koeberg.

The buildings now need to be properly overpressure tested to ensure that radiation cannot leak out in the event of an accident.

Eskom has applied to the NNR for separate expiry dates for Unit 1 and Unit 2 based on the rationale that Unit 2 was commissioned about 18 months after Unit 1. Eskom is still awaiting a decision from the NNR in this regard.

If the NNR decision in respect of a separate extended expiry date is not granted, then it is possible that both Unit 1 and Unit 2 may have to shut down on 21 July 2024.