* EDF hopes to convince regulator ASN that no repair needed
* ASN says at least one of the eight weldings has a flaw
* ASN to rule in May; negative ruling would mean more delay (Adds detail on weldings)
By Geert De Clercq
PARIS, Jan 29 (Reuters) - French state-controlled utility EDF’s nuclear reactor under construction in Flamanville, northern France, could suffer further delays if certain weldings need to be redone, the country’s nuclear regulator ASN said on Tuesday.
At ASN’s annual nuclear safety review, its chief regulator said there were questions about the quality of eight weldings on pipes between the Flamanville 3 reactor and the turbine building, and that there was a problem with one of the weldings.
“If the ASN were to rule that those ... weldings need to be redone, it is possible that EDF’s start-up calendar may not be respected,” Bernard Doroszczuk, who took up his post two months ago, told reporters.
EDF said last week it would make further tests next month on faulty weldings at Flamanville 3 but added it still targeted loading nuclear fuel at the plant in the fourth quarter of 2019.
EDF first reported problems with Flamanville 3 weldings in February 2018, when it said that more than half of the 66 weldings on the reactor’s secondary circuit were not in line with standards aimed at making them rupture-proof.
In April, EDF said additional controls on 150 weldings had shown that some were not in line with ASN requirements.
At the end of July, it said the welding problems had forced it to delay start-up of the reactor to the second quarter of 2020, with first fuel loading set for the end of 2019.
It then said 53 weldings would have to be redone, while for another 10 it was confident that it could convince the ASN they were fit for service.
Doroszczuk - a welding engineer by training (“a happy coincidence”, he said) - raised doubts about that on Tuesday.
“The flaws in the weldings are a serious issue,” he said.
He said there were questions about the quality of eight weldings, which are in places hard to access.
He added that EDF’s strategy was not to repair these eight weldings, but to prove to the regulator with technical calculations that the weldings are safe.
“We are awaiting these calculations and will rule on the weldings early May. We may ask EDF to redo them,” he said.
Doroszczuk said the overall safety of EDF’s reactors was satisfactory but urged the industry to maintain appropriate safety margins and not cut corners for financial reasons.
He said the nuclear industry needed to improve its skills base to prevent technical problems. (Reporting by Geert De Clercq; Editing by Sudip Kar-Gupta and Dale Hudson)