Sate-owned utility EDF, the world's largest nuclear producer, aims to extend the life of its reactors to 60 years, arguing similar plants in the United Sates have been allowed to do so.
But first it must satisfy the ASN they are safe to run for the 40 years most nuclear power plants were designed for.
"The ASN has indicated to EDF... that it had not identified any generic problems questioning EDF's capacity to manage the safety of the 900-megawatt reactors for a 40-year life span," the ASN said.
There is no official limit setting the maximum life span of EDF's 34 nuclear reactors that have a capacity of 900 megawatts, other than the usually accepted 40 years.
Growing concern over emissions of climate warming carbon from coal and gas fired power plants has sparked renewed interest in nuclear power in Europe.
This has provided added incentive to run existing nuclear facilities for longer in those countries that remain wary of building new ones.
France's own commitment to nuclear power has not wavered since it built the first reactors in response to soaring oil prices in the 1970s.
Allowing EDF to run its reactors for as long as the ASN deems safe makes economic sense because new plants are expensive to build but relatively inexpensive to run.
Such a decision allows more time for France to build new plants at a time when EDF is intent on international expansion.
Greenpeace France, which opposes nuclear energy, said it was preferable to authorize France's reactors to run for another 10 years than to embark on a large scale renewal of its atomic sector.
France plans to build two new reactors but more could be announced. The first 1,650-MW European Pressurized Reactor (EPR) is being built at the northwestern nuclear site of Flamanville and is expected to start running in 2012.
The French government has also announced this year that a second EPR would be built at Penly, also in northwestern France.
The ASN said it will gave final approval, reactor by reactor, 12 months after each one undergoes its third once-a-decade inspection. These inspections began in May and are expected to take place until 2019.
The 900-megawatt reactor 1 at Tricastin in southeastern France was the first to undergo its third such inspection but the process has been delayed by strikes and an incident that damaged the lid of the reactor's tank.
Spain recently gave the go-ahead for its oldest nuclear power station to stay open for another four years but has no plans to build new plants.