Les cahiers de l’ASN #02 - Conditions for the continued operation of EDF’s 900MWe reactors

The 4 th periodic safety review provides the opportunity to re- examine the conformity of certain items of equipment or systems, such as the electrical power sources. EDF has planned to implement a reactor conformity review programme that will, among other things, allow the application of the existing preventive maintenance programmes to be verified. EDF has moreover supplemented its actions by having multidisciplinary teams conduct field visits in certain premises containing systems that are necessary in accident situations. What measures are planned by EDF? For the management of equipment ageing and obsolescence , EDF has put in place: • a generic analysis of ageing and its consequences; • a local analysis specific to each reactor conducted during its 10-yearly outage. EDF has substantiated the ability of the reactor vessels that display no defects to function for the 10 years following their 4 th ten- yearly outage, taking into account the development of material characteristics. Inspections to check there are no prejudicial defects in the steel shall be carried out during the 10-yearly outage of each reactor. Certain reactor vessels whose past inspections have revealed manufacturing defects shall undergo specific studies prior to the 10-yearly outage of each reactor concerned. Lastly, EDF has undertaken to remedy previously identified deviations impacting safety by the 4 th ten-yearly outage of each reactor at the latest. The deviations detected during the ten-yearly outage will be corrected as soon as possible, taking account of their significance for safety . THE ASN RESOLUTION The EDF programme to manage ageing and verify the conformity of its reactors, supplemented by measures demanded by ASN, is satisfactory. It will enable the objectives targeted for the safety review to be achieved. ASN nevertheless asks EDF, in addition to the measures planned initially: • to perform additional tests to check the operation of certain systems necessary in accident situations, such as the steam generator auxiliary feedwater system; • to speed up deployment of the facility modifications in order to ensure that the planned means for recirculating the borated water in the event of an accident will be able to fulfil their functions. These points are set out as requirements in ASN resolution 2021-DC-0706 of 23 February 2021. EDF must be particularly attentive to application of the programme for verifying reactor conformity. ASN plans to carry out specific inspections on each reactor on this account, particularly during the 10-yearly outage.