Design flaw on three nozzles on the Flamanville EPR reactor: in principle, ASN has no objection to the solution proposed by EDF

In a letter dated 8 October 2021, ASN issued a position statement on the solution envisaged by EDF to deal with the design flaw concerning three nozzles on the main primary system of the Flamanville EPR reactor.

This flaw concerns the set-in welds for these nozzles, the failure of which is not covered by the reactor's safety case, because their diameter is too great.

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The solution proposed by EDF is to install a retaining collar around each nozzle concerned. In the event of breakage of the set-in nozzle weld, this collar would limit the size of the resulting break. The consequences of this break would then be covered by the reactor’s existing safety studies.

ASN considers that the solution proposed by EDF is in principle acceptable. ASN will issue a final ruling once EDF has provided the required data concerning the demonstration of the effectiveness of the arrangement, the design, manufacturing and operating requirements applicable to the collars and the quality of the set-in welds around which these collars would be installed.

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Published on 18/03/2021 at 11:14

Flamanville EPR reactor: design anomaly on three main primary system nozzles

On 3 March 2021, EDF notified ASN of a significant event concerning a design anomaly on three nozzles of the main primary system of the EPR reactor under construction on the Flamanville site.