Koeberg Nuclear Power Station’s Unit 1 has returned to service following an unexpected shutdown triggered by an electrical disturbance during testing activities linked to maintenance on Unit 2.
Eskom confirmed in a statement on Tuesday 20 October that Unit 1 was successfully synchronised to the national electricity grid at 12:02 following the completion of recovery activities.
The unit was taken offline on Friday 16 October after an electrical disturbance during testing associated with Unit 2’s planned maintenance outage caused Unit 1’s protection system to trip.
Eskom said the disturbance exceeded the predefined tolerance limits of a protection system associated with Unit 1, resulting in the automatic opening of the unit’s 400 kV and 24 kV breakers.
Protection system operated as designed
An investigation found that a conservative protection relay setting contributed to the system’s response.
According to Eskom, the protection system operated as designed, safely shutting down the unit and ensuring the continued safe operation of the plant.
“There was no impact on nuclear safety,” Eskom said in its latest statement.
The utility confirmed that Unit 1 is stable, with its electricity output being progressively increased in line with normal operating procedures.
Unit 2 remains under maintenance
The return of Unit 1 follows recovery and restoration work carried out by Koeberg teams after the shutdown. Eskom credited the teams involved for their coordinated efforts in bringing the unit back online.
Unit 2 remains in planned maintenance, with Eskom yet to provide further details on its return-to-service schedule in the latest update.
The latest development follows TygerBurger’s previous report that Unit 1 had been taken offline after the protection system operated during testing activities linked to Unit 2’s maintenance outage.
At the time, Eskom confirmed that engineering teams were investigating the incident and conducting fault-finding activities to determine the cause and identify any necessary corrective measures.
The utility has now confirmed that the recovery activities have been completed and Unit 1 has been reconnected to the national grid.
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