More details needed on Blayais steam generators

Friday, 28 November 2014

Areva has not submitted all the safety justifications required for the installation and commissioning of new steam generators at Blayais unit 3, according to the French nuclear regulator.

The Blayais nuclear power plant (Image: Marc Didier/EDF)

Unit 3 of the Blayais nuclear power plant near Bordeaux has been offline since late July for planned inspections. EDF plans to replace the unit's three steam generators during the current outage due to wear in their tube bundles. Areva has already supplied the replacement steam generators.

However, France's nuclear safety regulator, the Autorité de Sûreté Nucléaire (ASN), said that after reviewing the design and manufacture of the new steam generators, Areva has failed to provide all safety justifications required for their installation and commissioning.

The justifications required by the ASN mainly concern mechanical stress for sizing of equipment, conducting additional tests to prove the mechanical properties of certain materials, the methodology behind the calculations used to check the mechanical equipment, and the adequacy of control methods for the detection of potential defects.

ASN president Pierre-Franck Chevet wrote to Areva and EDF on 24 November asking them to provide the outstanding safety justifications.

The ASN noted that a December 2005 decree on nuclear pressure equipment increased the amount of justification and supervision required for the design and manufacture of such equipment. It added that it has found justifications and demonstrations provided by nuclear pressure equipment manufacturers are still "regularly unsatisfactory."

ASN stressed that these safety justifications "are prerequisites for installation and the commissioning of new steam generators."

Researched and written
by World Nuclear News