State-owned power utility Eskom plans to restart Koeberg Unit 1 on Sunday, which should help to stabilise the grid.
On March 10, Eskom’s operators had to manually trip the unit, owing to increasing temperature on the secondary side of the plant. This put further strain on the grid, forcing Eskom to increase its schedule power cuts to Stage 4.
The overheating problem stemmed from a degraded heat exchanger.
Additionally, a circulating cooling water system pump was clogged by an acute ingress of fish and jellyfish, which has since been resolved.
Eskom explained that, normally, Koeberg units are able to survive a trip of one circulating cooling water system pump. The operators would then reduce power to below 60% to ensure that temperatures of various components on the secondary side stabilises.
However, in this case, the temperature did not stabilise, as a result of the damaged heat exchanger.
The utility has done the necessary maintenance and obtained the required technical assessments to restart the unit.
Load-shedding was expected to continue throughout the weekend, but at reduced stages, the power utility has said.