10.08.13.A sunset shot of the Koeberg nuclear power plant next to Melkbosstrand near table View. Picture Ian Landsberg


Cape Town - Fresh from recent countrywide blackouts, Koeberg has announced that its unit 2 is going offline on Sunday for the next six weeks.

And although Eskom has said the shutdown is part of an ongoing maintenance plan, it has also urged users to keep electricity usage low to limit strain on the system.

Taking Koeberg 2 offline means losing a sizeable chunk of power: 900MW. Eskom spokesman Andrew Etzinger said this was part of the planned 4 000 to 5 000MW that is usually offline at any given time because of maintenance across the system.

“The grid is tight, but it won’t be any more tight than usual,” he said.

Eskom keeps 1 000 to 2 000MW on reserve for the peak evening period – though what it would prefer is closer to 3 000MW. But when unexpected loss of capacity strikes, that reserve margin erodes quickly.

“Really, what we’re continuing to urge is for South Africans to keep using electricity sparingly,” said Etzinger. “These issues are on a bigger scale at power station level, but it all adds up.”

Two weeks ago Eskom enforced a day of rolling blackouts across South Africa after weeks of heavy rain left coal stockpiles wet and slushy, causing a string of units at three different power stations to go down. With an unplanned 3 320MW suddenly off the grid, the reserve margin was overwhelmed. It was the third energy emergency in less than six months.

In November and February, industrial users were asked to cut their consumption by 10 percent, though national load shedding wasn’t implemented.

Earlier this month, Eskom chief executive, Brian Dames, warned that the ongoing maintenance of Eskom’s ageing infrastructure meant the energy supply was going to be on a knife-edge for a while to come.

The country’s coal-fired power stations are getting on in years – 30 years old, on average – and suffer frequent breakdowns.

And while our only nuclear power station is still performing excellently, it must be refuelled at some point.

Eskom’s nuclear spokesman, Tony Stott, said each of Koeberg’s units underwent refuelling and inspection every 16 to 18 months.

“We try to stagger this so that it never happens at the same time, and also try to avoid doing it in winter,” he said.

For refuelling, all 157 of Koeberg 2’s uranium fuel elements need to be removed and inspected. About two thirds of these will be put back, and the other third completely replaced.

Stott said the six weeks would also be used to do maintenance on the station’s safety system and inspect the steam generators.

The unit should be back online just before the weather turned at the end of May.

Etzinger said scaling back on electricity use was especially important given South Africa’s current expensive reliance on diesel.

“At the moment, we’re using diesel very extensively in the Western Cape,” he said. In the current financial year, ending this month, he said Eskom would have used a combined R10 billion worth of diesel at the open-cycle gas turbines in Mossel Bay and Atlantis.

“These were designed for emergency use,” said Etzinger.

“They were designed to be used infrequently. But we’ve actually been using them on a regular basis, for prolonged periods, in some cases right through the day. Cutting back on our electricity usage will enable Eskom to reduce its diesel consumption.”

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Weekend Argus