UPDATE 1-Eskom shuts down second unit at nuclear plant

(Recasts with Eskom comment, details)

By Paul Simao

JOHANNESBURG, July 26 (Reuters) - South African state power utility Eskom [ESCJ.UL] said on Saturday it had shut down a second unit at its Koeberg nuclear plant but did not anticipate the move would lead to electricity cuts.

Eskom, which provides 95 percent of the country's power, took Koeberg's Unit 1 generating station offline Friday after workers detected a suspected fault in the cooling system, Eskom spokesman Tony Stott said.

"We expect by the end of the weekend it will be at full power again," Stott said. He added that the problem had occurred on the non-nuclear side of the plant, which is located in the Western Cape province.

The shutdown of Unit 1 came several days after Eskom announced that Unit 2 at the plant had been shut down due to a technical problem. Stott said it was expected that Unit 2 would remain out of operation for a few weeks.

The shutdowns at Koeberg reduced power supply on the national grid by about 1,800 megawatts.

Stott said electricity supply in the Western Cape remained vulnerable but added that the utility did not expect there to be power cuts over the weekend as a result of the problems at Koeberg, which is South Africa's only nuclear power station.

Eskom has been rationing electricity through a process known as load-shedding for the past six months in an effort to keep the national power supply system from collapsing.

The crisis has led to frequent power cuts, plunging millions into darkness and forcing industry to reduce its consumption. Mines, a cornerstone of the South African economy, are operating at between 90 and 95 percent of their normal power supply.

Eskom said on Thursday it saw an increased risk of load-shedding in the coming weeks as it conducted repairs at Koeberg. Further technical problems were reported at Eskom's Majuba and Duvha power stations earlier this week. (Editing by David Christian-Edwards)