PARIS, June 23 (Reuters) - A long-awaited report by the IRSN, the technical arm of French nuclear regulator ASN, advises that the vessel of the nuclear reactor EDF is building in Flamanville is fit for purpose, two sources with direct knowledge of the report told Reuters.
A negative view from the IRSN would have been disastrous for EDF, as it would cost billions of euros and years of delay to take the vessel out of the reactor building again after it was welded in place and the reactor dome sealed in 2013.
Since then, it has been covered by thousands of tonnes of concrete at the site in northwest France.
Despite excessive carbon concentrations - which can weaken the steel - in the lid and cover of the reactor vessel, the reactor will be able to operate safely although it will need monitoring over its lifetime, the report says.
A group of independent experts, who received the report last week, will discuss the document on Monday and Tuesday to formulate an opinion, after which the ASN after the summer will rule on whether Flamanville can start up in 2018.
A favourable ASN ruling is also a European Commission precondition for its approval of EDF's planned takeover of struggling state-owned reactor builder Areva's reactor unit.
Reporting by Geert De Clercq; Editing by Dale Hudson