LES ACTIVITÉS NUCLÉAIRES : RAYONNEMENTS IONISANTS ET RISQUES POUR LA SANTÉ ET L’ENVIRONNEMENT 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 installations and the management of equipment ageing therefore need to be reviewed to take account of the degradation mechanisms 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 incorporate those linked to deployment of the “hardened safety core”. ASNR’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, notably the level of safety to be achieved for continued operation of the reactors. After examining the objectives proposed by EDF, with the support of IRSN, and following consultation of its GPEs, ASN released a position statement on these objectives and issued additional requests in April 2016. EDF supplemented its programme of work and in 2018 presented ASN with the measures it envisages taking in response to these requests. In 2020, with the support of IRSN, ASN finalised its examination of the generic studies linked to this review. At the beginning of 2021, ASN issued a position statement on the conditions for continued operation of the reactors. ASN considered that the measures planned by EDF combined with those prescribed by itself open up the prospect of continued operation of these reactors for the ten years following their fourth periodic safety review. In October 2023, EDF asked ASN for postponement of the deadlines for some of the requirements in the resolution adopted in February 2021. Unexpected technical issues during implementation of some of the requirements, changes in the refuelling outages schedule, notably linked to the discovery of stress corrosion on the auxiliary lines, unexpected long-duration unscheduled outages or the needs of the electricity grid during the winter period, as well as a logjam with other periodic safety reviews, creating pressure on its engineering capacity, led EDF to revise its ability to carry out the activities needed to comply with the requirements, on time. ASN considered EDF’s request to be acceptable in the light of the explanations provided. Deployment of the periodic safety review on the site EDF carried out the first of the fourth ten-yearly outages in 2019 (Tricastin NPP reactor 1). At the end of 2025, EDF had carried out or initiated 25 of these ten-yearly outages. These outages are a major step in the fourth periodic safety reviews. During these outages, EDF carries out the required inspections and deploys most of the safety improvements associated with the review. The fourth ten-yearly outages for the 900 MWe reactors will run until 2031. HIGHLIGHT No. 11 The ageing of Nuclear Power Plant 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 2.2.4). EDF’s ageing management process is based on three main principles: 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, safety-important equipment more particularly undergoes a qualification process to ensure its ability to perform its functions in conditions corresponding to the situations in which it will be needed, accident situations in particular. This qualification, which takes account of ageing phenomena, defines a limited lifespan for the equipment. Where this may be exceeded, the licensee must either check that the equipment remains fit for purpose for a further period, or replace it. 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. In particular, they help to ensure that reactors remain compliant with the applicable safety requirements over time. The provisions adopted or planned by EDF are examined and inspected by ASNR, to ensure that the risks associated with ageing and obsolescence are controlled satisfactorily. ASNR considers that the approach implemented by EDF provides satisfactory control of these risks. HIGHLIGHT No. 12 Adapting nuclear power plants to climate change In a context where the effects of climate change are becoming increasingly marked, EDF must adapt its facilities and their operation to take account of the expected changes in terms of accident risk management (heat waves, rising sea levels, etc.) and environmental impact (water withdrawal and consumption, thermal discharges, etc.). The levels of natural hazards that NPPs must be able to withstand are reassessed every ten years as part of the periodic safety reviews. These reassessments are leading EDF to strengthen the protection of its NPPs. In particular, climate change is altering the meteorological hazards likely to affect the operation of NPPs equipment: this is taken into account as part of the periodic safety reviews based on the assessments of the Intergovernmental Panel on Climate Change (IPCC). Climate change is also having an impact on the environment around NPPs. It makes the issues of surface and groundwater abstraction and the dilution of radioactive, chemical and thermal effluent discharges into the natural environment more critical. In order to control the impact on the environment, the conditions for water intakes and effluent release from the facilities are governed by ASNR decisions specific to each NPP. Climate change calls for the development of a forward-looking approach, a deepening of scientific knowledge, and a reflection on the technological evolution of installations, as part of a global and long-term approach, both with regard to the future EPR 2 reactors and the reactors currently in operation. This is why the fifth periodic safety review of reactors will focus on taking greater account of the effects of climate change on NPPs. This will involve, for example, an assessment of the effects of climate change on water resources, which will provide a forward-looking vision of the challenges presented by each NPP. In addition, ASNR has drawn up a dedicated roadmap for its expert assessment and research work, with the aim of furthering knowledge of climate change and its effects. ASNR is involved in research in this field, taking part in thesis work on local and regional estimates of extreme rainfall events, on extreme temperatures in 2100 and on the impact of climate change on the frequency and intensity of extreme weather events. ASNR has also set up a working group bringing together licensees of nuclear installations and experts from a variety of backgrounds to draw up a state of the art report on how to take account of hazards linked to water and air temperatures in the safety case of nuclear installations. This report could be used as a basis for drafting a guide for licensees of nuclear facilities. ASNR Report on the state of nuclear safety and radiation protection in France in 2025 305 01 05 02 06 03 07 04 08 09 10 11 13 12 A / Z
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