Paris — France, a world leader in nuclear technology, is having second thoughts about its strong commitment to nuclear power.
According to its official goal, France plans to become the world's second largest producer of nuclear power by 1985 - behind the US, but ahead of West Germany, Britain, Japan, and the Soviet Union.
High costs and stagnating demand for electricity, however, have begun to force the scaling down of the nuclear program.
And France may abandon its plans to build four to six breeder reactor plants, even though it is expected to complete the world's only commercial breeder reactor, the Super-Phenix, in about 18 months. The reason: This special type of nuclear plant, designed to be self-sufficient in fuel, is proving to be too expensive.
Weak economic growth means there will have to be ''a certain reduction in the rhythm of the nuclear program,'' Marcel Boiteux, president of the state-owned company Electricite de France (EDF), said this month.
Mr. Boiteux was talking about nuclear construction in 1984 and beyond. Energy Ministry officials say the government will decide in early spring whether to continue building nuclear power plants at the rate of three per year, or to cut back.
The government is reportedly split on the issue. Finance Minister Jacques Delors and Planning Minister Michel Rocard are apparently arguing that economic constraints mean France can only afford three new nuclear plants in 1984 and 1985 against the planned six - especially since the electricity demand to support them does not seem to be forthcoming.
Against this argument, Industry Minister Jean-Pierre Chevenement supposedly wants the nuclear program to continue full-speed ahead. He warns that a third oil price shock could catch France with too little nuclear capacity and that in any case France cannot afford to slow down an industry that employs 150,000 people.
Observers say the Delors-Rocard faction seems to have an edge on Mr. Chevenement at this point. But they say nothing is certain.
''Everything will depend on President (Francois) Mitterrand's humor when the decision comes before him,'' said Pierre Samuel, nuclear affairs specialist for the main ecologist party, Friends of the Land.
Ecologists do not have much confidence in Mr. Mitterrand's good humor. During the 1981 presidential campaign, Mr. Mitterrand responded to pressure from ecologists and the public fallout from the Three Mile Island accident by pledging to hold a referendum on continuing France's nuclear development.
But after the Socialist victory no referendum was held. Instead, Mr. Mitterrand adopted the previous government's position that, with few energy resources of its own, France must rely on nuclear power. He argued that nuclear energy is cheaper than imported oil and not subject to the political whims of France's Arab suppliers.
Nevertheless, Mr. Mitterrand did slow down nuclear development, if only marginally. Instead of building a planned nine reactors in 1982 and 1983, six have been ordered.
EDF statistics show that France now has 20 reactors under construction. After they are completed, France's nuclear capacity will shoot up from 14,000 megawatts in 1980 to 37,000 megawatts. By then about two-thirds of France's electricity will be supplied by nuclear power.
Along with increasing nuclear power production, the French have become leaders in nuclear technology. The Super-Phenix breeder reactor represents this achievement.
It is the world's first nuclear plant to use plutonium (the radioactive substance also used in nuclear weapons) and produces more nuclear fuel than it consumes in generating electricity.
Technical uncertainties and safety worries forced the US to abandon its breeder reactor program. The Socialists, though, appear to have few qualms about Super-Phenix's technology or safety.
''We will have to see how it works, of course,'' said Marie Jose Bernardot of the Energy Ministry. ''But we have good guarantees about its safety.''
Even so, the breeder program is in trouble. A world uranium glut has reduced Super-Phenix's ability to ''breed'' fuel for ordinary nuclear plants. And most critically, Super-Phenix is proving to be too expensive: EDF figures show that it will cost about 15 billion francs ($2.2 billion) or about three times as much as an ordinary reactor producing the same amount of electricity.
As a result, original hopes of building four to six Super-Phenix reactors after the one at Creys-Malville near Lyon is completed have been whittled down to one more at best. Whether the government will even approve constructing it is an open question.
Government spokesmen refuse to comment, saying no decision has to be made before 1986. According to ecologist Samuel, the military is lobbying to continue the breeder program to assure itself access to weapon-grade plutonium.
But EDF argues that the economics against more breeders are too strong. ''We just don't see any need for more Super-Phenix's in the foreseeable future,'' said EDF spokesman Henri Hunthaas.
This attitude could change, though. Oil prices might surge and uranium might become scarce again. For despite some recent problems with hairline cracks inside reactor vessels, the French believe nuclear power is a safe and cheap source of electricity.
Except for the ecologists, almost no political group questions the necessity of nuclear power. And the ecologists are small and splintered compared to their northern European counterparts.
''I think nuclear power elicits much less reaction and worry than before,'' EDF President Boiteux said recently. Ecologist Samuel agreed and so did Energy Ministry official Bernardot.
''Before the election, we were split philosophically on nuclear power,'' she said. ''The debate is completely different now. Nuclear power is accepted here. The only question is how much we need.''