(Bloomberg) -- Electricite de France SA got regulatory approval to start up its new nuclear reactor 12 years behind schedule after the utility faced construction problems ranging from concrete weakness to faulty pipe welds.

The green light for commissioning of the Flamanville 3 nuclear plant located in Northwestern France allows EDF to load the fuel in the reactor, proceed with trials, then begin operations, the Autorite de Surete Nucleaire said in a statement on Tuesday. Further approvals will be required when reaching key milestones during the trial phase, the regulator added said.

Once connected to the grid, the 1.6-gigawatt plant called a European Pressurized Reactor will join EDF’s fleet of 56 reactors in France, which accounted for about two-thirds of the country’s power production last year. 

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The plant’s startup follows a series of blunders that have undermined the flagship project and hurt the finances of the utility, which came back under full government ownership last year. Since construction started in 2007, the project’s budget — excluding finance costs — has quadrupled to €13.2 billion ($14.2 billion).

The utility will still have to replace the reactor-vessel cap during its first refueling outage, and the safety authority will also set deadlines for the replacement of other equipment and components. 

The years-long saga has created lasting doubts about the French nuclear industry’s ability to build reactors on time and on schedule — a crucial issue as it prepares to launch the construction of a fleet of six plants in France.

EDF’s construction of two similar reactors in the UK also suffered repeated delays and cost overruns, complicating the British government’s effort to raise funds for the construction of another pair of EPRs.

Two similar units have been built in China by EDF and its local partner in the past decade with limited delays. A first-of-a-kind EPR started up in Finland last year, 14 years later than initially planned. 

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