by Chris Yelland, managing director, EE Business Intelligence

The risk of both nuclear reactors at Eskom’s Koeberg nuclear power station in the Western Cape Province of South Africa being shut down simultaneously for life extension continues to increase.

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

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. The last scheduled date for the return to service of Unit 1 was 3 November 2023.

Unit 1 at Koeberg is now expected to be synchronised to the grid by 30 October 2023, and to return to commercial operation at full output by 13 November 2023, after increasing the output through different power levels and performing the associated commissioning tests.

The shut-down of the 970 MW Unit 2 at Koeberg will therefore also be delayed, if necessary, until after the commissioning of Unit 1 is complete, and stable commercial operation is achieved. This is to avoid a situation where both Units 1 and 2 are down at the same time.

Unit 2 will be shut down for refuelling, maintenance and replacement of its three steam generators, in a similar operation to that of the 11-month outage of Unit 1 that commenced in mid-December 2022. Eskom hopes the lessons learned on Unit 1 will result in a shorter outage for Unit 2.

After the return to service on 13 November 2023, Unit 1 is scheduled for a further 200-day shutdown commencing on 21 July 2024, the same day that the current operating licence of the Koeberg nuclear power station expires.

This would appear to indicate that the National Nuclear Regulator (NNR) may not be in a position to grant an extension of the Koeberg operating licence when the current Koeberg operating licence expires on 21 July 2024.

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 that covers the nuclear reactor. 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 and that any such cracks and leakages are identified and repaired.

In the meantime, Eskom has applied to the NNR for separate expiry dates in the Koeberg licence 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 in the Koeberg operating licence for Unit 2 is not granted, then it is possible that both Unit 1 and Unit 2 may have to shut down on 21 July 2024.