A long slow retreat from nuclear power in France or indecision over policy could be very risky as skilled staff retire and young people reject careers with an uncertain future, the state-funded atomic safety research institute said.
If France does decide to pull out of atomic energy it should follow Germany's example and do it quickly, or face operating with inadequate personnel, said Jacques Repussard, who heads the Institute for Radiological Protection and Nuclear Safety (IRSN).
"You can't spread the exit of nuclear over half a century. It's very dangerous," he said, adding that this consideration partly explained Germany's decision to opt for a fast exit to avoid a loss of skills.
France's state-owned utility EDF, which operates its 58 nuclear reactors, faces a wave of retirements and will have to replace half its nuclear staff by 2017-18.
While Socialist President Francois Hollande has undertaken to cut the country's reliance on atomic energy to 50 percent of electricity consumption by 2025, from 75 percent now, he has not made clear what would happen after that date.
"If, in the next 10 years, there is no clarity on what the future of nuclear energy will be, we will inevitably see a trend in our universities of young people saying: 'I don't want to do that line of work'," Repussard told Reuters in an interview at one of its research centers in the south of France.
As part of the reduction drive in France, the world's most nuclear-reliant country, the government has announced that Fessenheim in the east, its oldest nuclear plant, will shut by the end of 2016.
While the government has allowed EDF to pursue building its first next-generation nuclear reactor in Flamanville in northwestern France, it abandoned the previous government's project to build another reactor at Penly in Normandy.
Germany decided to shut all its nuclear reactors by 2022, in a policy reversal drafted in a rush after Japan's Fukushima disaster in March 2011.
CONSIDERABLE RISKS
"It was criticized and we asked ourselves how they would do it... But it's wise because doing it slowly means taking considerable risks with the last operating reactors, as finding skilled subcontractors and companies manufacturing certain parts (could become problematic)," Repussard said.
But he admitted that France, where nuclear reactors are on average 26 years old, would never consider a fast exit even though this would be the safest approach if it decided to stop building new reactors or conducting research.
Another issue for the government to consider, he said, was that generic defects would probably appear in several reactors at around the same time, leading them to stop working abruptly.
This echoed comments earlier this month by Pierre-Franck Chevet, the head of France's nuclear safety agency, who said the country needed to ensure there was enough available electricity generation capacity to cope with the sudden outage of 5 to 10 nuclear reactors.
"One day we will see wear and tear appear in the steel of core tanks... and when we see it in one, we will probably see it in all the reactors of the same generation in a short space of time," Repussard said.
Electrabel, the Belgian subsidiary of GDF Suez, has had to close two reactors in Belgium after finding possible cracks in the core tanks that house them.
_0">"To be 80 percent reliant on nuclear energy exposes us to that kind of situation," he added.
_1">(Writing by Muriel Boselli; Editing by Anthony Barker)
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