EDF 'aims to prove' Flamanville 3 reactor cap can stay

EDF has "taken note" of the French nuclear regulator's position indicating that the Flamanville 3 reactor pressure vessel (RPV) is fit for service, but aims to prove that regular maintenance would avoid the need to change the closure head of the RPV in 2024.

Autorité de Sûreté Nucléaire (ASN) said yesterday it had provisionally ruled the unit can start up safely, at the end of 2018 as planned, but that the RPV head would need to be replaced once a new one has been produced.

Areva NP revealed its discovery of an anomaly in the composition of the steel in certain zones of the RPV's closure head and bottom head of the Flamanville EPR in April 2015. The engineering group initiated a test program to demonstrate that the mechanical strength of the steel is sufficient in all operating situations, including accident situations. Its conclusions were sent to ASN in December 2016.

ASN said yesterday that, although additional periodic inspections to ensure that no flaws appear subsequently can be performed on the vessel bottom head, the technical feasibility of similar inspections on the closure head had not been established.

EDF has developed an in-service monitoring system that will ensure [the vessel bottom's] operation over the long term.

In response, EDF said: "Construction at the site is progressing according to the schedule announced in September 2015: the system performance tests have started, with a view to the fuel loading and the reactor start-up, scheduled for the end of 2018. Regarding the vessel bottom, EDF has developed an in-service monitoring system that will ensure its operation over the long term. With regard to the vessel cap, EDF takes note of the ASN's request to plan for its replacement by the end of 2024."

It added: "The direct cost of replacing a vessel cap amounts to approximately €100 million ($114 million). At the same time, EDF's teams are mobilised to develop an in-service monitoring method that would allow it to demonstrate that the lid maintains its qualities over the long term.

"EDF is committed to providing a progress report to the ASN within two years on this work. If this work is conclusive, EDF will submit a new application to the ASN in order to be able to use the vessel cap beyond 2024."

ASN has made the "examination report" available on its website for public consultation, along with the opinion of its advisory committee for nuclear pressure equipment. It will finalise its opinion in October.

Researched and written
by World Nuclear News