By Benjamin Mallet
SAINT-PAUL-TROIS-CHÂTEAUX, France, June 28 (Reuters) - F rench state-controlled utility EDF has started a 250 million euro ($284.65 million) maintenance and upgrade works at its 900 megawatt Tricastin 1 nuclear reactor that could enable it operate for another ten years.
Commissioned in 1980, Tricastin 1 is the first in France's fleet of 58 reactors to undergo a fourth 10-yearly overhaul, a thorough review to ensure its integrity beyond 40 years of operation, and the ability to function for another 10 years.
EDF would have to demonstrate to nuclear safety authority ASN, that it is properly managing the aging reactor, while improving safety and environmental levels, taking into account new measures place since the 2011 Fukushima accident in Japan.
ASN has said it would make a generic ruling on the extension of the lifespan of 32 of EDF's 900-megawatt capacity reactors at the end of 2020, this would be followed by a reactor by reactor in depth, starting with Tricastin 1.
"This is of paramount importance for the company because we (Tricastin 1) are the pioneers and our experience will be used for other plants," said Cedrick Hausseguy, the site director.
Including a detailed inspection of the reactor vessel, EDF would also have to control and make sure the circuits of the reactor and the containment building are properly sealed.
The upgrade works, involving some 5,000 workers and touching on 80 different sectors, will last until November.
It comes at a time when EDF faces increased scrutiny and stringent requirements from the nuclear watchdog to comply with safety measures at its reactors.
ASN last week ASN said EDF would have to repair eight faulty weldings at the containment building in the Flamanville 3 EPR nuclear reactor it is building in northern France.
Etienne Dutheil, EDF's head of nuclear production said the company was working closely with the regulator on the lifespan extension works of its nuclear fleet.
"There is a very high level of requirement from the ASN but we have tried to anticipate it as much as possible and get approvals for our technical options in our exchanges with them," Dutheil told Reuters during a visit at the plant on Thursday.
The overhaul of the reactors that included renovations and improved safety, is expected to cost around 45 billion euros ($51.24 billion) between 2014 and 2025.
Dutheil said the upgrades were expected to be a profitable operation that would allow France to continue to benefit from cheap low-carbon nuclear power and would not lead to an increase in consumer electricity bills.
Tricastin's four nuclear reactors produce an average of 25 terawatt hours (TWh) of electricity per year, or 6% of French nuclear power generation. The remaining three reactors will undergo similar upgrades between 2021 and 2024. ($1 = 0.8783 euros) (Writing by Bate Felix, editing by Louise Heavens)