PARIS For decades, the elite engineers turned out by Paris's grand Corps des Mines academy were faithful followers of the pro-atomic creed that transformed their country into the most nuclear-reliant nation in the world.
But a new generation of Mines graduates is starting to question that policy. It is a change of mindset that could aid efforts by President Francois Hollande to cut reliance on nuclear power from 75 percent to 50 percent of the electricity mix by 2025.
"Noone at the Corps des Mines questions the need for nuclear power in the energy mix, however the younger generation is more concerned about the environment and leaving room for other energy sources," said Francois Bordes, a 40-year old Corps des Mines graduate who advises businesses on energy efficiency.
Bordes is part of a generation of Mines engineers who believe atomic energy has a role to play - but not the dominant one given it by elders who helped build the world's second-largest nuclear program after the United States.
"There is a generation gap between Mines members who had key jobs during the three booming post-war decades and those who started out in the past 15 years," Bordes added.
The Corps des Mines was founded in 1794 to turn France's now-exhausted coal mines to the advantage of Europe's industrial revolution. But after World War Two it won a new raison d'être when Corps des Mines engineer Pierre Guillaumat worked with De Gaulle to create the state-funded CEA nuclear research body.
It became an example of French post-war "dirigisme" - the policy under which the state seeks to direct the economy - determining how nuclear energy was used for civilian and military purposes, with the development of France's atomic bomb.
"A RISKIER WORLD"
The construction of 58 nuclear reactors prompted successive French governments to invest massively in electric heating to absorb the supplies. France became the world's top electricity exporter.
Now some Mines graduates say the heavy dependence on one energy form means France struggles to cope with seasonal demand spikes.
"We believed for too long that nuclear energy was cheap and that we could, for example, massively develop electric heating as a result. This is nonsensical," said Vincent Le Biez, a 27- year-old Mines graduate.
Alumni include Anne Lauvergeon, ex-head of nuclear giant Areva, current head of France's nuclear energy watchdog ASN, Pierre-Franck Chevet, his predecessor Andre-Claude Lacoste, and Jacques Repussard of the IRSN nuclear safety institute.
The nuclear industry's image was tainted in the eyes of the French public after the 1986 Chernobyl nuclear disaster, when the nuclear watchdog insisted radioactive contamination from the accident had not spread to French territory.
In fact it released vast quantities of radioactive material over the whole of Europe and France was no exception. For many French, the episode created the perception of an invisible pro-nuclear lobby pushing its interests against those of the nation.
France's nuclear lobby is hard to pin down because it is intricate. Its critics tend to be anti-nuclear NGOs or green politicians with no ministerial experience. A rare exception is Corinne Lepage, former ecology minister under Alain Juppe's government between 1995 and 1997.
Lepage said the lobby had strong leverage in parliament.
"There is at the parliament a powerful group of parliamentarians and senators who are pro-nuclear, with some formerly from EDF," she said, referring to the state utility that is Europe's biggest electricity producer. "They are so close to the (nuclear) lobby that they are called 'EDF allies'."
Chernobyl was for many a wake-up call to the dangers of nuclear energy, an alarm which sounded again with Japan's Fukushima nuclear disaster last year.
"Graduates who started out working in the 1990s are more worried about a riskier world where no technology is perfect," said Bordes.
Hollande's government is due to shut France's oldest reactor by the end of 2016 and launched on Thursday a national debate on energy that will for the first time include discussion of the role of atomic power.
That debate will help shape a framework energy law in 2013 that will define how to cut France's nuclear capacity, boost renewable energy and lift energy efficiency. With France currently shunning shale gas for ecological reasons, nuclear advocates will argue that French industry simply cannot do without cheap nuclear power.
France is slowly embracing heavily-subsidized renewable energies, such as wind and sun power, but they only make up 13 percent of the energy mix, far behind Germany and Spain and well below the 23-percent target set by former President Nicolas Sarkozy for 2020.
The change in mindset is reflected at the ASN. In contrast to its handling of Chernobyl, it was the first agency worldwide to classify the Fukushima accident at the top end of the international nuclear and radiological event scale (INES).
ASN activated an unprecedented communication plan designed to provide France and the world with an up-to-the-minute independent view of the unfolding event.
"There was in the mind of a number of people at the French nuclear safety authority, including myself, the idea that we had to purge Chernobyl," said Lacoste, who retired this month after 20 years as ASN chief.
Yet any move away from nuclear is likely to be a subtle shift rather than a sharp jolt. While the oldest nuclear reactor is due to be shut, there are no plans to halt construction of Areva's next-generation reactor in northwestern France.
"The shift announced by the French President will not affect the technical expertise of French operators EDF and Areva," Jean-Paul Tran Thiet, an energy lawyer for White & Case said.
But the cooling of France's ardour for nuclear could give pause for thought to others such as South Africa, still hesitating to build new reactors.
"This decision can also be perceived as a weakening in confidence of the nuclear power sector, which could have a negative impact on foreign buyers," Tran Thiet added.
(Additional reporting by Axelle Du Crest; editing by Mark John, Anna Willard and Janet McBride)