Repairs at the Koeberg nuclear power station could take — in “a worst-case scenario” — nine months to carry out, says Eskom’s acting chief executive, Jacob Maroga.
Cape Town has been hit by four outages in the past three months and is dependent on Koeberg, especially during peak demand times.
Maroga said South Africa is still looking for the required parts to repair the unit-one generator at Koeberg, and while the intention is to return the generator to service in the shortest possible time to meet electricity demand, it will take a minimum of three months to repair.
However, he acknowledged that the repairs “could take longer”, or as long as nine months. Eskom will inform the media and the public “in case it takes longer than the current plan”, he told MPs serving on the National Assembly minerals and energy portfolio committee on Monday.
Sketching recent outages in Cape Town, Maroga said damage to unit one was caused by a foreign object — a bolt — found in the generator after it had been returned to service following a planned maintenance shutdown.
“Based on available information, this is the cause of the fault,” he said, noting that this occurred on December 25.
Cooling systems of the stator and rotor of the generator were affected and more than half of the bars in the generator were damaged, and these will have to be replaced. There are, however, no problems in the reactor and the turbine at the plant.
He reported that on November 11 — when the Cape Town area suffered its first electricity outage — there was a mechanical failure on a 400kV switch-gear during switching operations in the transmission substation at Koeberg.
Automatic protection measures occurred when Koeberg tripped, resulting in a 90-minute transmission shutdown. However, the power outage took “much longer” in parts of Cape Town.
The outage on November 16 was caused by a fire under the Muldersvlei-Droëriver 400kV power line. This led to a short circuit and the line tripped. This time, the “unit two” generator at Koeberg was affected, and the power outage lasted 60 minutes on the Cape network.
Currently supply to the Cape is being handled by Koeberg’s unit-two generator and transmission transfers from the rest of the country.
Another power outage occurred on November 23 as a result of a controlled shutdown of Koeberg’s unit-two generator.
Indicating that power outages may not be a thing of the past, Maroga said that emergencies in the Cape could include unplanned shutdowns of a Koeberg unit and loss of one of the transmission lines.
In the event of such emergencies, power could be brought in from various sources, including from Eskom gas turbines at Acacia in Cape Town and at Port Rex in East London as well as from the Orange River Hydro scheme.
Democratic Alliance MP Hendrik Schmidt said he is alarmed that there are not back-up plans in place to avoid outages, while Inkatha Freedom Party MP Eric Lucas expressed concern that it had not been a condition that the original supplier of the Koeberg parts — now being sought — should provide replacement parts.
Maroga said about R5,5-billion is being spent on Eskom’s maintenance of and investment in transmission lines, grid strengthening and gas turbines in the period from 2002 to June 2007. — I-Net Bridge