UPDATE 3-French strike cuts 11,235 MW in nuclear capacity-CGT

(Updates production capacity outage)

PARIS, Jan 15 (Reuters) - The French CGT union said on Thursday a 24-hour strike in the nuclear sector had cut 11,235 megawatts (MW), or 17 percent of the nuclear capacity, by 1530 GMT, pushing intraday power prices higher.

The union warned that if the management of state-backed nuclear energy operator EDF EDF.PA did not listen to the demands of the workers, who are striking over pay and working conditions, those actions would be repeated.

The strike was taking place in 17 of France’s 19 nuclear power plants, the official said.

Workers at the Golfech (southwest) and Penly (northwest) plants had voted not to take part in the protest, he added.

“Workers had cut 11,235 MW of nuclear power capacity by 1530 GMT,” the official said, adding a union meeting on Friday morning would determine whether similar actions would be repeated before a planned public sector strike on Jan. 29.

EDF declined to comment on the drop in power capacity but insisted supplies to customers would not be affected.

“With such a strong turnout, EDF’s management has to react to the demands made by the staff,” the CGT said.

The strike had pushed French intraday power prices higher, one London-based trader said, adding the Genscape tool, which estimates real-time power production, confirmed a high outage rate in French reactors.

“This is one of the highest outage rates we have seen in the last couple of years,” the trader said.

The strike coincided with cold weather in France, with national weather forecaster Meteo France showing temperatures at between one and five degrees Celsius.

The union official said EDF would start asking strikers to stop cutting capacity at nuclear plants, as French power grid RTE predicted a peak demand of 86,240 MW at 1800 GMT. (Editing by James Jukwey and Sue Thomas)