Verifications during reactor outages EDF takes advantage of nuclear reactor outages to carry out maintenance work and inspections which cannot be performed when the reactor is generating electricity. These operations more particularly correct deviations already known, but can also lead to the detection of new ones. Before each reactor restart, ASN asks EDF to list any deviations not yet remedied, to take appropriate compensatory measures and to demonstrate the acceptability of these anomalies with respect to the protection of persons and the environment for the coming production cycle. Ten-yearly verifications: conformity checks EDF carries out periodic safety reviews of the nuclear reactors every ten years, in accordance with the regulations (see point 2.9.2). EDF then carries out an in-depth review of the actual state of the facilities by comparison with the applicable safety requirements, more particularly on the basis of the in-service monitoring hitherto carried out, and lists any deviations. These verifications can be supplemented by a programme of additional investigations, the aim of which is to check the parts of the facility which are not covered by a preventive maintenance programme. The additional verifications in response to ASN requests In addition to the steps taken by EDF with regard to its operating baseline requirements, additional checks are carried out at the request of ASN, whether, for example, with regard to OEF about events which have occurred on other facilities, after inspections, or after examination of the provisions proposed by the licensee within the context of the periodic safety reviews. Information of ASN and the public When a deviation is detected, and in the same way as any BNI licensee, EDF is required to assess the impacts on nuclear safety, radiation protection and protection of the environment. If necessary, EDF then sends ASN a significant event notification report. In addition, when the most noteworthy significant events occur, EDF informs the public by publishing notices on the website of the NPPs concerned, or in its external newsletter. For its part, ASN informs the public on asn.fr of significant events of level 1 or higher on the International Nuclear and Radiological Event Scale (INES). ASN requirements concerning repairs ASN published its Guide No. 21 on 6 January 2015 regarding the handling of conformity deviations. This Guide specifies ASN’s requirements concerning the correction of nonconformities and presents the approach expected of the licensee in accordance with the principle of proportionality. This is based more specifically on an assessment of the potential or actual consequences of any deviation identified and on the licensee’s ability to guarantee the safety of the reactor in the event of an accident, by taking appropriate compensatory measures. The Guide also recalls the principle of the correction of compliance deviations as soon as possible and in any case defines the maximum times allowed. 2.4.8 Assessment of facilities compliance with the applicable requirements In the past, ASN has found that the organisational measures taken to deal with deviations were unsatisfactory and that the time taken to characterise, check and process the deviations did not always comply with the requirements of the Order of 7 February 2012. In 2019, EDF therefore revised its internal baseline requirements for management of deviations, in order to improve how they are processed and provide ASN with reactive information proportional to the safety implications. In 2021, ASN observed a notable improvement in the situation. The efforts made by EDF must be continued over the coming years. Significant events concerning several reactors were once again reported in 2021 following the detection of conformity deviations; some of these deviations date back to the construction of the reactors, while others arose when making modifications to or performing maintenance on the facilities. ASN will continue to be particularly attentive to the conformity of the facilities in 2022 and will in this respect continue its inspections of the condition of equipment and systems. Finally, ASN observes that certain systems linked to the “support”, “reactivity control” and “cooling” safety functions are subject to recurring unscheduled unavailability. This is notably the case with the reactor component cooling systems, post-accident monitoring, reactor nuclear power measurement and rod cluster control. These unavailabilities, already identified in 2020, were the subject of discussions with EDF, which will be continued in 2022, in order to verify the pertinence of the steps taken by EDF. Notification of significant events by EDF Pursuant to the rules for the notification of significant events (see chapter 3, point 3.3), ASN received 762 Significant Safety Events (ESS) reports from EDF in 2021, along with 158 Significant Radiation Protection Events (ESR) reports and 68 Significant Environmental Protection Events (ESE) reports. In 2021, the number of significant events is slightly up on the previous year, in particular the ESS (746 in 2019, 740 in 2020). It should also be noted that for the first time in 2021, the events reported by the Fessenheim site were not included in these results. Graph 1 shows the trend since 2011 in the number of significant events reported by EDF and rated on the INES scale. Graph 2 shows the trend since 2011 in the number of significant events according to the notification field: ESS, ESR and ESE. Events not rated on the INES scale are also taken into account. Significant events affecting several nuclear reactors are grouped under the term generic “significants events”. In 2021, 31 events of this type were reported in the field of nuclear safety. 2.5 Prevention and management of environmental and health impacts 2.5.1 Discharges and waste management Limiting water intake and environmental discharges NPPs discharge liquid and gaseous effluents. These effluents, which can be radioactive or chemical, are created by the actual operation of the reactor, primarily the operations designed to ensure the radiochemical quality of the MPS, the chemical conditioning of the systems, in order to contribute to their good condition, the production of demineralised water to supply certain systems, biocidal treatments and effluents from the site’s wastewater treatment plant. For each site, ASN sets the limit values for water intake and dis– charge of effluents on the basis of the best available technologies in technically and economically acceptable conditions, taking into consideration the characteristics of the installation, its location and the local environmental conditions. ASN also sets the rules concerning the management of detri– mental effects and the impact on health and the environment of the PWRs. These requirements are notably applicable to the management and monitoring of water intake and effluent discharge, to environmental monitoring and to information of the public and the authorities (see chapter 3, point 4.1). In setting these requirements, ASN uses OEF from all the reactors as the basis, while also taking account of operational changes (change in conditioning of systems, anti-scaling treatment, biocidal treatment, etc.) and changes to the general regulations. 296 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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