4th periodic safety review of the 900 MWe reactors: ASN publishes its initial analysis of EDF's planned measures to meet the review objectives

As part of the ongoing consultation concerning the 4th periodic safety review of the 900 MWe reactors, ASN gives its initial analysis of the response notice to the objectives transmitted by EDF. This notice details the inspections and modifications EDF plans to implement on its reactors to meet the safety review objectives.

The last ASN Chairman, Pierre-Franck Chevet, communicated his first observations to EDF on 28 September 2018. He underlines that the EDF notice "addresses all the subjects provided for in the safety review guidance file and takes into account, at this stage, the majority of the requests made by ASN". He also notes that "the work undertaken and the planned measures will bring significant improvements in the safety of the facilities and will help to achieve the safety review objectives".

ASN is nevertheless still waiting for additional demonstrations regarding certain subjects. This is the case in particular with the "current conformity verification programme [which] must be clarified so that ASN can verify that if fully satisfies the safety review objectives". ASN considers that managing reactors conformity with their initial technical baseline represents a major issue of this safety review, as demonstrated by several generic deviations detected over the last few years.

ASN also draws EDF's attention to the fact that "at this stage of the examination, it appears that certain subjects are liable to lead to requests for significant additional measures" and draws up the list. This is particularly the case regarding seismic resistance, the effectiveness of the systems recirculating the water in the bottom of the reactor building sumps and the need or otherwise to increase the thickness of the basemat of certain containments.

ASN, assisted by IRSN, is currently examining the studies undertaken by EDF for this safety review which serve as the basis on which it determines the verifications and modifications it plans to implement on its reactors. ASN will issue a position statement on the achievement of the safety review objectives at the end of 2020.