ASN issues a position statement on the conditions for continued operation of the 900 MWe reactors beyond 40 years

Published on 25/02/2021 • 09:00 am

Information notice

On 23 February 2021, ASN ruled on the conditions for the continued operation of the 900 MWe reactors beyond their fourth periodic safety review. ASN considers that the measures planned by EDF combined with those prescribed by ASN open the prospect of continued operation of these reactors for a further ten years following their fourth periodic safety review.

In France, the authorisation to create a nuclear facility is issued by the Government, after consulting ASN. This authorisation is issued for an unlimited duration, and the facility undergoes an in-depth "periodic safety review" every ten years to assess the conditions for continued operation of the facility for the following ten years.

EDF's thirty-two 900 MWe reactors are the oldest reactors in operation in France. Their fourth periodic safety review is of particular importance because the service life hypothesis adopted at the design stage was 40 years. Continuing operation beyond 40 years necessitates the updating of the design studies or equipment replacements. In its resolution 2021-DC-0706, ASN prescribed the implementation of the major safety improvements planned by EDF, along with additional measures it considers necessary to achieve the objectives of the safety review. This resolution closes the "generic" phase of the safety review, which concerns the studies and modifications of the installations common to all the 900 MWe reactors, as they are all have a similar design model.

These improvements and measures shall then be applied to each reactor individually during their fourth periodic safety reviews, scheduled to run until 2031. These reviews shall take the particularities of each facility into account. The measures planned by EDF for each reactor shall be subject to a public inquiry.

A public consultation on the measures planned by EDF for the generic phase of the fourth periodic safety review of the 900 MWe reactors was held between September 2018 and March 2019 under the auspices of the HCTISN (French High Committee for Transparency and Information on Nuclear Security). ASN also posted its draft resolution on its website for public consultation between 3 December 2020 and 22 January 2021. This consultation led ASN to change or clarify some of the requirements of its resolution. This is the case, for example, with certain studies prescribed by ASN, for which the completion deadlines have been brought forward. ASN has also pushed back some deadlines on account of specific industrial and operating constraints when this was acceptable from the safety aspect. ASN also explained its position regarding the deployment schedule for the modifications resulting from the periodic safety review and its expectations with regard to deviations detected during the 10-yearly outage.

ASN requires EDF to report annually on the actions implemented to meet the requirements and their deadlines, and also on the industrial capacity of both EDF and its outside contractors to complete the modifications of the facilities within the set time frames. ASN requires that this information be made public.


For further information, refer to (in French only):

Publié le 25/02/2021

Décisions de l'ASN

Décision n° 2021-DC-0706 de l'ASN du 23 février 2021

Décision n° 2021-DC-0706 de l’Autorité de sûreté nucléaire du 23 février 2021 fixant à la société Électricité de France (EDF) les prescriptions applicables aux réacteurs des centrales nucléaires du Blayais (INB n° 86 et n° 110), du Bugey (INB n° 78 et n° 89), de Chinon (INB n° 107 et n° 132), de Cruas (INB n° 111 et n° 112), de Dampierre-en-Burly (INB n° 84 et n° 85), de Gravelines (INB n° 96, n° 97 et n° 122), de Saint-Laurent-des-Eaux (INB n° 100) et du Tricastin (INB n° 87 et n° 88) au vu des conclusions de la phase générique de leur quatrième réexamen périodique.

Date of last update : 25/02/2021