Eskom plans to start synchronising one of the Koeberg nuclear power station’s generating units to the grid on Friday evening, more than six times after it first went offline.
The utility has suffered numerous delays in bringing back the unit after initially taking it down for major maintenance and refuelling in mid-January 2022.
That was supposed to include the installation of three new heat exchanges, part of a steam generator replacement programme to extend the power station’s life by 20 years.
However, when the contractors for the refurbishment arrived at the site, they discovered personnel had failed to build the necessary containment structure needed to house the old radioactive steam generators.
To avoid the unit being offline throughout winter, when demand is typically much higher, Eskom cancelled the replacement and postponed it to another date.
It then intended to complete the refuelling and other maintenance work to bring the unit back by the end of June 2022.
But the utility encountered several issues with the startup phase of the unit.
Initially, the return to service was delayed to mid-July due to several defects picked up during commissioning.
It then pushed the date to the end of July 2022 due to unexpected issues with the unit’s polar crane.
Eskom has now told MyBroadband it resolved the last known issue with the unit’s planned startup in the early hours of Wednesday morning.
“Unfortunately, the schedule remains susceptible to future emergent issues, but the current optimistic plan indicates the unit should be ready for synchronisation during Friday night,” the utility said.
“The unit will then require about 10 days to reach full power.”
The unit’s unavailability has cut 920MW of reliable capacity from the grid, equal to almost one stage of load-shedding.
Eskom has blamed the repeated delays on the compounding effect of detecting a defect during the startup process.
“Once in this phase, any emergent issue has a direct impact on the critical path, hence the planned startup window has been delayed,” the utility said.
“This is having a direct impact on the return to service date of the unit. Thus, the startup phase is taking longer than anticipated in the original outage plan.”
The utility also explained that reworking the unit’s maintenance schedule only started a month into its outage, contributing to the overall delay.
Eskom had to accommodate several factors in the new plan, including:
- Reversing all the non-intrusive work that had already been done in preparation for the steam generator replacement.
- Rescheduling and resourcing of all the scheduled maintenance and inspection activities, which were originally scheduled to occur only after the steam generator replacement work scope.
- Contracting and inclusion of the additional work scope needed to inspect and maintain the original steam generators to allow them to operate safely for an 18-month additional cycle.
It said intrusive activities — maintenance, inspections, and plant upgrades — were essentially completed as scheduled.
This included the refuelling of the reactor, the line-up of all the plant systems and the testing and verification that all equipment is operable as per operating procedures and technical specifications, which are a licence requirement.
Eskom reiterated its top priority was to ensure the continued safe operation of the nuclear power station.