review. EDF more particularly carries out a large part of the checks and modifications related to the periodic safety reviews during the ten-yearly inspections of its reactors. In accordance with the provisions of Article L. 593-19 of the Environment Code, following this periodic safety review, the licensee sends ASN a periodic safety review concluding report. In this report, the licensee states its position on the conformity of its facility and details the modifications made to remedy deviations observed or to improve the safety of the facility and, as necessary, specifies the additional improvements that it will be making. ASN analysis ASN examines the periodic safety reviews in several stages. It first of all issues a position statement on the objectives of the review and the guidelines of the generic verification programmes on the state of the facility and the safety reassessment proposed by EDF, after obtaining the opinion of the Advisory Committees of Experts (GPE). On this basis, EDF carries out safety reassessment studies and defines the modifications to be made. ASN then issues a position statement on the results of these studies and on these modifications, after again consulting the GPE. This position statement closes the generic phase of the periodic safety review, common to all the reactors. This generic assessment does not take account of any specific individual aspects and ASN gives a ruling on the suitability for continued operation of each nuclear power reactor, notably on the basis of the results of the conformity checks and the assessment made in the periodic safety review concluding report for the reactor submitted by EDF. Following examination of the periodic safety review concluding report for each reactor, ASN communicates its analysis to the Ministry responsible for nuclear safety. It can issue new requirements governing its continued operation. The Energy Transition for Green Growth Act 2015-992 of 17 August 2015 supplemented the framework applicable to the periodic safety reviews on nuclear power reactors. It more specifically requires ASN authorisation, following a public inquiry, of the provisions proposed by the licensee during the periodic safety reviews beyond the 35th year of operation of a nuclear power reactor. Five years after submitting the periodic safety review report, the licensee also submits an interim report on the condition of these equipment items, in the light of which ASN may supplement its prescriptions. 2.9.3 Ongoing periodic safety reviews in the Nuclear Power Plants The 900 MWe reactors The third periodic safety review In July 2009, ASN issued a position statement on the generic aspects of continued operation of the 900 MWe reactors beyond their third periodic safety review. ASN did not identify any generic elements compromising EDF’s ability to ensure the safety of the 900MWe reactors up until the next periodic safety review. It considers that the new baseline safety requirements presented in the generic safety report for the 900MWe reactors and the modifications to the installation envisaged by EDF are such as to maintain and improve the overall level of safety of its nuclear power reactors. In 2021, EDF completed the third ten-yearly outages and sub– mitted the periodic safety review concluding reports for all its 900 MWe reactors. The fourth periodic safety review (see “Notable events” in the introduction to this report) A high-stakes review EDF’s 32 reactors of 900 MWe in operation were commissioned between 1978 and 1987. The first ones have reached the milestone of their fourth periodic safety review. This fourth periodic safety review comprises particular challenges: ∙ Some items of equipment are reaching their design-basis lifetime. The studies concerning the conformity of the instal– lations and the management of equipment ageing therefore need to be reviewed to take account of the degradation mech– anisms actually observed and the maintenance and replacement strategies implemented by EDF. ∙ The safety reassessment of these reactors and the resulting improvements must be carried out in the light of the safety objectives of the new-generation reactors, such as the EPR, the design of which meets significantly reinforced safety requirements. The modifications associated with this periodic safety review will incorporate those linked to deployment of the “hardened safety core” (see box next page). ASN’s position statement on the generic phase of the periodic safety review In 2013, EDF sent ASN its proposed objectives for this periodic safety review, in other words, the level of safety to be achieved for continued operation of the reactors. THE AGEING OF NUCLEAR POWER PLANTS EQUIPMENT As in any industrial installation, the equipment in NPPs experiences ageing. This ageing is the result of physical phenomena (corrosion of metals, hardening of polymers, hardening of certain steels under the effect of irradiation or temperature, swelling of certain concretes, etc.) which can degrade their characteristics according to their age or their operating conditions. This degradation obliges the licensee to repair or replace the equipment or to limit the lifetime of non-replaceable equipment, such as the reactor pressure vessel (see point 2.2.3). The ageing management process implemented by EDF is based on three main points: anticipating the effects of ageing as of the design stage, monitoring the actual condition of the facility and repairing or replacing equipment degraded by the effects of ageing. Before being installed, equipment important for safety more particularly undergoes a qualification processes to ensure its ability to perform its functions in conditions corresponding to the situations in which it will be needed, accident situations in particular. The management of equipment ageing, and of the risk of obsolescence –which refers to difficulties linked to guaranteeing the procurement of spares over time– are essential to maintaining a satisfactory level of safety. They also contribute to reactor conformity being maintained over time. For the continued operation of the 900 MWe reactors beyond their fourth periodic safety review, management of ageing was given particularly close attention by ASN. The provisions implemented or planned by EDF to ensure the management of ageing and obsolescence are satisfactory. However, ASN asked that, without delaying their decommissioning, the final shutdown of the Fessenheim NPP reactors should be used as an opportunity to check the absence of any unexpected degradation or ageing phenomena, in particular on those parts of the installation that are hard to access. 304 ASN Report on the state of nuclear safety and radiation protection in France in 2021 10 – THE EDF NUCLEAR POWER PLANTS
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