In July 2016, the ASN took the decision to suspend the test certificate for this component as a precautionary measure subsequent to a deviation found in the internal manufacturing records for one of the parts used in the assembly of this component. This deviation was identified by Framatome as part of the review of the manufacturing records at the Le Creusot site. This deviation concerned the cropping rate of the steel ingot used to manufacture the part, known as a shell.
A program mobilizing Framatome's testing and production capacities and expertise
Technical analyses conducted by experts from Framatome since 2016 have concluded that the deviation detected did not compromise the integrity of the component in operation. However, in order to substantiate matters, two shells with identical characteristics (steel grade, ingot weight, dimensions of the part) were cast and forged at Le Creusot site. Chemical analyses and mechanical tests (tensile and impact-strength tests) were carried out on these parts.
The complete proposed test program to substantiate the serviceability of this part was the subject of discussions with the ASN on an ongoing basis in order to obtain agreement from the authority on the methodology used. The ASN was kept informed by Framatome of the actions taken and the results of the analyses carried out.
On the basis of its analyses, and in coordination with EDF, Framatome put together a file enabling the suspension of the test certificate to be lifted by the ASN. This file was analyzed by a cross-disciplinary standing group of experts on February 27, 2018. On March 9, 2018, the ASN published its decision confirming the lifting of the suspension of the certificate for the steam generator.