Regulator says Areva nuclear reactor problems could be costly

PARIS, April 17 (Reuters) - Weak spots found in nuclear reactors designed by France’s Areva are “very serious” and could prove costly to rectify, the head of France’s nuclear regulator told a French newspaper.

Anomalies have been found in the bottom and lid of the reactor vessel which could reduce the resistance of the metal, Pierre-Franck Chevet, head of the ASN regulator, told daily Le Parisien.

“This is a serious, even very serious anomaly as it affects an absolutely crucial reactor component on which no risk of rupture can be taken,” Chevet was quoted as saying.

The ASN said last week that Areva had found weak spots in the steel of the European Pressurised Reactor (EPR) it is building for utility EDF in Flamanville, France.

Chevet said that a similar Areva forging technique had been used for five other EPRs either planned or being built.

Two of these are in Taishan, China and another two set for Hinkley Point in England. Components have also been manufactured for one planned for Calvert Cliffs in the U.S. state of Maryland.

Areva was not immediately available to confirm whether the vessels for the Hinkley Point project -- for which a final investment decision has not yet been taken -- had already been manufactured.

Chevet said the installation of the reactor vessel in Flamanville is already largely completed. The vessel has been placed in its concrete base and welded to cooling circuits.

New tests on the vessel will be held in coming months and results are due in October.

Asked what would happen if these were negative, Chevet said: “Either EDF abandons the project or it takes out the vessel and starts building a new one ... this would be a very heavy operation in terms of cost and delay.”

The Flamanville reactor is already years behind schedule and billions of euros over budget.

The EPR 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.

Chevet said the EPR under construction in Olkiluoto, Finland, was not affected because the vessel had not been forged by Areva but by a Japanese firm.

China has said it will not load fuel at the Taishan reactors until the reactor vessel issue has been fully resolved. (Reporting by Geert De Clercq; Editing by Keith Weir)