South Africa’s power utility, Eskom, said on 4 January that unit 1 at the Koeberg NPP had been taken offline after an increasing leak rate was observed on one of three steam generators. This was confirmed by other plant measurement readings.
“Although the leak rate was well within the safety limits, a conservative decision was made to take Koeberg Unit 1 offline for repairs,” Eskom said. “During this period the unit will also undergo its routine maintenance and refuelling, which was originally scheduled to start during February. The unit is expected to return to service during May 2021.”
"There is no risk to plant, personnel, or the environment. Unit 2 continues to safely operate and generate at full power,” Eskom added. Koeberg 2 completed it last outage in October 2020.
Koeberg nuclear power plant, which comprises two 970MWe pressurised water reactors supplied by Framatome, began operation in 1985. Eskom said in September it was on schedule to install six new steam generators at Koeberg in 2021. The steam generators, each weighing around 366 tonnes, are being assembled in China before being shipped to South Africa and transported to the reactor site on flat-bed trucks.
Impact of Koeberg's early outage
The closure of Koeberg 1 caused serious power supply problems for Eskom, which from 6-8 January was obliged to implement loadshedding “in order to recover and preserve the emergency generation reserves that have been utilised to support the system during the week following the earlier than planned shutdown of Koeberg unit 1 and other units whose return to service has been delayed”.
Eskom said it had 6672MWe on planned maintenance, with another 12,073MWe of capacity unavailable due to unplanned maintenance. Eskom urged the public to reduce electricity consumption noting that “the system remains vulnerable and unpredictable” and that “loadshedding is implemented as a last resort in order to protect the integrity of the system”.Eskom has had to impose intermittent power outages across major cities since 2008 and 2020 was the worst year on record for power cuts.
Koeberg nuclear power plant (Credit: Pipodesign, Philipp P Egli)