* Weak spots found in steel of nuclear reactor vessel
* No comment about possible new delays to Flamanville
* Regulator has warned other countries where EPRs are built (Adds EDF, Areva comment, background)
By Geert De Clercq
PARIS, April 7 (Reuters) - Areva has found weak spots in the steel of the EPR nuclear reactor it is building for utility EDF in Flamanville, France, French nuclear regulator ASN said on Tuesday.
Areva and EDF said in a joint statement that while they start a series of new tests on the EPR, construction work would continue on the reactor, which is already years behind schedule and billions of euros over budget.
ASN said Areva had informed it that tests at end-2014 had shown that in certain zones of the reactor vessel and cover of the EPR there was a significant concentration of carbon, which weakens the mechanical resilience of the steel and its ability to resist the spreading of cracks.
Areva declined to comment on whether the tests would lead to new delays for Flamanville and impact three other EPRs under construction, one in Olkiluoto, Finland, two in Taishan, China.
“The ASN has informed nuclear regulators in other countries where EPRs are being built,” the regulator said.
EDF also plans to build two EPR reactors in Hinkley Point, Britain.
The EPR, or European Pressurised Reactor, is a new-generation pressurised water reactor, built to resist the impact of a commercial airline crash. It has been widely criticised as too big and too expensive and Areva has been forced to book billions of euros in provisions due to cost overruns.
French Energy Minister Segolene Royal said in a statement that results of the new tests are expected in October.
First estimated to cost 3 billion euros, the EPR projects in France and Finland have been plagued by problems and delays, and costs have ballooned to nearly 9 billion euros ($9.8 billion).
In November, EDF announced a new one-year delay for the Flamanville reactor which it now expects to be connected to the grid in 2017, a decade after construction started. It had initially been scheduled to start in 2012.
Construction on the Olkiluoto reactor began in 2005 and it is not expected to be connected to the grid before 2018, nearly a decade later than scheduled.
Areva and Finnish consortium Teollisuuden Voima (TVO)
have started legal proceedings against one another, with Areva and its partner Siemens claiming 3.5 billion euros in damages from TVO and TVO 2.3 billion from Areva-Siemens.
Shares of Areva and EDF, up 2.1 and 1.4 percent respectively, were slightly off morning highs after the announcement of the anomalies.
$1 = 0.9221 euros Reporting by Geert De Clercq, Editing by Dominique Vidalon, Jane Merriman and David Evans