EDF has experienced further problems with the quality of welding at the Flamanville 3 EPR, under construction in Normandy. The inferior weld quality was caused by the ergonomics of the welder’s post, while a delay in performing radiographic inspection prevented quick detection of the defects, according to the French nuclear regulator. Areas showing faults have now been repaired and preventative measures have been put in place.

In June 2010, EDF informed the French nuclear safety authority (ASN) of an increase in the number of faults detected in a weld in the liner. The liner is a metal barrier that will assure the leak-tightness of the EPR reactor building.

After similar problems were experienced in 2008/2009, ASN asked EDF to implement an action plan to improve the quality of the liner welds and to perform radiographic testing on all welds. The action plan specified rules for welding conditions and training for welders.

ASN inspectors paid a visit to the FL3 site on 7 July in order to validate the measures implemented by EDF to improve weld quality.

“The inspectors observed that the ergonomics of the welding position of the horizontal weld in question was the primary cause of the new problems.” ASN said in its second quarter report.

“They also observed that radiographic testing was not performed as welding work advanced: the delay in performing an inspection prevented quick detection of inferior weld quality.”

On the day of the inspection, EDF had already suspended new welding activity, reminded those concerned of the 2009 action plan and begun radiographic testing of all questionable welding. Repair of the areas showing faults have now been completed.

In its report ASN said it wished to “emphasize EDF’s proactive response in implementing preventive measures following detection of the deviation in June 2010.”

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