Cape Town - The Koeberg Nuclear Power Station’s Unit 1 has been taken off-line for repairs, routine maintenance and refuelling.
In a statement, Eskom said on Sunday afternoon that an increasing leak rate was observed on one of three steam generators in Unit 1.
“This was confirmed by other plant measurement readings,” the utility said.
“Although the leak rate was well within the safety limits, a conservative decision was made to take Koeberg Unit 1 off-line for repairs. 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 in May, and there is no risk to plant, personnel, or the environment, Eskom said.
“The steam generator is a tubular heat exchanger which mechanically dries the steam produced during the nuclear power generation process. Shutting down the plant takes several hours, and the process is still under way. 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 said.
Unit 2 continues to operate at full power.
In October last year, Unit 2 successfully completed its 24th outage.
While many maintenance activities can be performed without switching off the station, there are some more intrusive activities that can only be performed when the unit is shut down, Eskom said.
Koeberg staff performed the refuelling and maintenance, with the assistance of 32 international specialists required to safely perform some specialist and very focused maintenance tasks. These crews arrived in South Africa on July 31 last year and followed all the Covid-19 protocols.
“This will give Eskom a reliable electricity output of approximately 900MW for close on 400 days, helping ease the supply constraints on the rest of the power station fleet.
“This was a planned and regular refuelling outage, where the nuclear fuel in the reactor core was replaced with new fuel. All the nuclear fuel is removed from the core during a refuelling outage, the reactor cavity drained, and cleaned, then refilled before the fuel is placed into the core,” Eskom said.