UPDATE 1-France to close its oldest nuclear plant by April 2020

(Adds Energy Minister comments, unions say will appeal)

PARIS, April 9 (Reuters) - France’s oldest nuclear power reactor will stop electricity production by April 2020, once a new generation EPR reactor in Flamanville is operational, according to a government decree issued on Sunday.

The closure of Fessenheim, in northeastern France, was a 2012 electoral promise by French President Francois Hollande, who promised to curb French dependency on nuclear power and develop other renewable energy sources.

But this was opposed by workers and executives at plant operator EDF as well as opposition parties and some candidates in the upcoming French presidential election.

Board members of state-controlled EDF authorised its chief executive to seek a decree from the government to keep Fessenheim open at least until six months before the start-up of the new reactor at the company’s Flamanville site.

“The decree repeals, at the request of the operator, the authorisation to operate the Fessenheim nuclear power plant owned by EDF, from date of entry into service of the Flamanville 3 EPR reactor,” the decree said.

It said the 1,650 megawatt (MW) capacity Flamanville 3 was expected to start production by April 2020 at the latest, and so to respect France’s legal ceiling of 63.2 gigawatts of power from nuclear sources, the 1,800 MW Fessenheim would have to halt production.

“As promised, the decree which repeals the license to operate the Fessenheim nuclear power plant is published. It was promised, it has been done,” Energy Minister Segolene Royal said in a separate statement.

The closure is part of France’s obligation to diversify its energy sources as set by the Energy Transition Law, which provides for 40 percent of renewable energy in electricity production by 2030, Royal said.

France currently depends on nuclear power for over 75 percent of its electricity needs.

Workers’ unions in the energy sector, who are against the shutdown of Fessenheim, condemned the publication of the decree saying it was a face-saving measure by the government for electoral gains. The unions said they would appeal it.

“This decree is illegitimate and devoid of any economic and industrial rationality,” one of the unions, CFE Energies, said.

The union said it would appeal to the State Council, France’s highest administrative body, to have the decree overruled.

The decree to shut down the Fessenheim plant came a few days after the company’s board decided not to vote to immediately halt production. (Reporting by Bate Felix. Editing by Jane Merriman and Susan Fenton)