Eskom says there are no nuclear safety concerns following the automatic shutdown of Koeberg Nuclear Power Station’s Unit 1 after an electrical protection system operated during testing linked to maintenance on Unit 2.

Koeberg Nuclear Power Station’s Unit 1 was safely taken offline on Friday 16 October, after an electrical protection system operated in response to a disturbance outside its tolerance limits.

According to Eskom, the incident occurred during testing activities associated with the planned maintenance outage of Unit 2.

The electrical protection system associated with Unit 1 operated as designed, resulting in the automatic tripping of the unit’s 400 kV and 24 kV breakers.

The system safely disconnected Unit 1 from the electricity grid, and the unit was taken offline.

Eskom said engineering teams are conducting detailed investigations and fault-finding activities to determine the cause of the protection system’s operation and identify any corrective actions that may be required.

No nuclear safety concerns

Eskom has assured the public that the incident has not raised any nuclear safety concerns.

“All nuclear safety systems remain fully operational, and Koeberg Nuclear Power Station remains in a safe and stable condition,” the utility said in a statement.

Eskom also confirmed that sufficient electricity generation capacity is available within the power system to accommodate the temporary loss of Unit 1’s output.

As a result, the incident is not expected to affect Eskom’s ability to meet electricity demand. The utility said further updates would be provided as the investigation progresses.

Previous maintenance delays

The latest development follows earlier maintenance delays at Koeberg reported by TygerBurger in July. At the time, Eskom confirmed that Unit 1, which was offline for long-term maintenance, would return to service later than initially planned.

The unit had originally been scheduled to return to service in July, but the target was moved to the end of August.

According to Eskom, the delay was caused by additional maintenance required on the unit’s new steam generators.

During routine inspections using a method known as eddy current testing, defects were identified in four tubes out of thousands. Eskom said the defects were addressed immediately through an advanced automated repair process carried out by international specialists and local teams.

“Our top priority is always the safety of our employees, the public and the environment,” Bheki Nxumalo, Eskom’s Group Executive for Generation, said at the time.

“Carrying out these additional inspections and repairs to world-class standards, we are investing in the long-term reliability of Koeberg and South Africa’s energy future.”

The latest incident involves an electrical protection system operating during testing activities linked to Unit 2’s planned maintenance outage. Eskom has not yet indicated whether the investigation will result in further maintenance or affect Unit 1’s operating schedule.

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