France must invest billions of euros to improve the safety systems of its nuclear facilities so they can withstand the kind of extreme shocks that triggered in Fukushima the worst nuclear accident in 25 years, the nuclear watchdog ASN said on Tuesday.

French nuclear power operator EDF will need to install flood-proof diesel generators and bunkered remote back-up control rooms at its 19 plants across the country or else face having to shut down some of its 58 reactors, the ASN added.

State-controlled EDF will also have to set up, before the end of 2012, an emergency nuclear task force to intervene on the site of an accident within less than 24 hours.

"We believe that facilities can only continue to operate if investments are made in the timeframe we're setting, otherwise we may have to suspend some operations," ASN President Andre-Claude Lacoste told a news conference.

"If EDF estimates that what we are asking for is so expensive that it does no longer make it worth to operate one facility, it can decide to shut that facility," Lacoste added, giving no detailled financial estimate of the works needed.

The ASN on Tuesday handed the French government the conclusions of a safety assessment of nuclear facilities nearly 10 months after an earthquake and tsunami crippled Japan's Fukushima Daiichi nuclear plant, triggering the world's worst nuclear crisis since Chernobyl. 

France has carried out "stress tests" on its nuclear facilities as part of a European Union-wide move to assess the resistance of European nuclear power plants to extreme cases of natural catastrophe or bad weather.

The EU is due to publish its conclusions in June. The ASN concluded that the facilities it assessed in France, the world's most nuclear-dependent country, presented a "sufficient" safety level but that action needed to be taken to beef up the operational management of accidents and ensure facilities could resist extreme cases like flooding or quakes.

French Energy Minister Eric Besson said in a statement he would meet up with EDF, nuclear reactor maker Areva  and the CEA nuclear scientific research body on Jan 9 to elaborate an agenda for the implementation of these measures.
     
France is in the midst of a heated debate over its dependence on nuclear energy ahead of the 2012 presidential elections. 

The ruling UMP party is in favour of maintaining the status quo, while the opposition Socialist party has said it wants to close the oldest 24 reactors by 2025. Financing these new safety measures may prove a thorny issue for the budget-conscious government.

EDF, which is more than 80 percent owned by the state, will need to dig into its pockets to finance the work and the investment will likely increase the group's production costs, which in turn may put some pressure on the government to increase state-set electricity tariffs.

"I cannot see how investments of several billions of euros would have no impact on production costs," Lacoste said. This investments however may prove to be a boon for groups such as Areva, which manufacture the services and products nuclear power operators need to improve safety systems.

Lacoste estimated on Tuesday that each of France's 58 nuclear reactors will need to be equipped with a back-up diesel generator at a cost of 30 to 50 million euros apiece.-Reuters