Eskom’s Koeberg power station, the only nuclear power plant in Africa, which the power utility has often said is its most dependable power station and generates its cheapest electricity, is down to half-power. Again. According to the utility’s website, the Koeberg plant’s Unit 1 (of only 2 units) has been taken out of service for repairs, routine maintenance and refueling. Unit 2 was shut down for months last year for maintenance and refueling and only started to supply power to the grid again in October. Now, just two months later, Unit 1 is out is service.
This follows the discovery of a leak in one of the Unit’s three steam generators. Although the leak is said to be “well within safety limits”, and that there is no risk to plant, personnel, or the environment, the decision was taken to take Unit 1 out of service. This means that 900 MW of the 1800 MW which Koeberg usually supplies the grid will be unavailable until at least May this year.
This is significant in and of itself, since Eskom’s overall power output is already very low, with, according to a statement by Eskom’s spokesperson, 7641 MW of capacity out of service for planned maintenance, and and additional 11 381 MW out of service due to “unplanned maintenance” i.e. breakdowns.
We should therefore expect loadshedding – or “load rotation” as Eskom likes to call it – to be implemented again soon.
Eskom says that while Koeberg Unit 1 is offline, it will also undergo its routine maintenance and refuelling, which was originally scheduled to start during February. Its unclear whether the leaking steam generator will be replaced with the new one at this time.
Koeberg’s steam generators are, like the rest of the power plant, ageing. The power station started producing electricity in April 1984 (Unit 1), and July 1985 (Unit 2).
The significant delays and cost over-runs associated with Eskom’s new coal-fired power stations, Medupi and Kusile, mean that Koeberg needs to be kept operating beyond its initial end-of-life date.
To extend the life of the plant, six new steam generators (three for each unit) were ordered, and the first was delivered in late September 2020. Installation of this first steam generator is scheduled for Unit 1 between February and June 2021.
A steam generator is a tubular heat exchanger which mechanically dries the steam produced during the nuclear power generation process. Each steam generator weighs approximately 380 t and is about 20 m long.
Shutting down the plant takes several hours, the power utility says, and the process is still underway – once shut down, fuel will be unloaded from the reactor core to enable maintenance activities to be conducted, and the cause of the increased leak rate to be addressed.
Eskom says that Unit 2 continues to operate safely and generate electricity at full power.