PARIS, Dec 16 (Reuters) - EDF's (EDF.PA) new nuclear reactor in Flamanville will be delayed by at least six more months and costs will increase by another 500 million euros ($531 million), the company said on Friday.
The new delay is the latest blow to the group's efforts to show it can keep to its schedules and step up the output of its fleet.
The Flamanville EPR reactor, which is already a decade behind schedule and has been dogged by repeated cost overruns, is now expected to start operations in the first quarter of 2024 and cost 13.2 billion euros, EDF said.
It blamed the move on the need for further works that were proving more complicated than expected following repairs on welds.
The group in January had forecast construction costs of 12.7 billion euros and said the reactor would start loading fuel - one of the final stages before the start up of a plant - in the second quarter of 2023.
EDF will also comply with a request by France's nuclear watchdog to replace the reactor's vessel closure head by the end of 2024, which would entail a first mandatory stoppage only some months after its start, the director of the project, Alain Morvan, told journalists on a call.
Morvan said that the Flamanville EPR reactor would only be connected to the national network three months after the loading of fuel.
"The first electrons produced will be delayed by around six months," he said.
The works causing the latest delay and higher costs are linked to 150 thermal treatments needed for some welds so they are resistant enough when the reactor produces power.
Those works, which follow repairs on some faulty welds, were interrupted last summer and will start again in early 2023.
When the Flamanville reactor project was first announced in 2004, it was estimated it would cost 3 billion euros and would start operations in 2012.
EDF, which is in the process of being fully nationalised, has faced a record number of outages at its existing 56 reactors due partly to corrosion problems which first emerged a year ago. As a result, France's nuclear output has hit a 30-year low this year.
The group said on Thursday its Penly 1 reactor would come back online more than a month later than expected. It also delayed the restart of its Flamanville 1 reactor, initially expected for Dec. 25, by almost two months due to the need to replace some steam generators, according to a spokesperson.
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