ASN Report 2020

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 2.10.2). 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 operating experience feedback 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, EDF, in the same way as any BNI licensee, 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. As of level 1 on the INES scale, the public is informed of the events thus reported on asn.fr ASN requirements concerning repairs For the most important deviations, ASN published its Guide No. 21 on 6 January 2015 regarding the handling of con­ formity deviations. This Guide specifies ASN’s requirements concerning the correction of non-conformities 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 control of the reactor in the event of an accident, by taking appropriate compensatory measures. The Guide also recalls the principle of correction of compliance deviations as soon as possible and in any case defines the maximum times allowed. Significant events EDF is required to notify ASN of and then analyse any significant events occurring in its NPPs (see chapter 3, point 3.3). Each significant event is, whenever appropriate, rated by ASN on the INES scale. This process of notification and analysis of significant events contributes to operating experience feedback and to the continuous improvement approach for the protection of the interests mentioned in Article L. 593-1 of the Environment Code. At the local and national levels, ASN examines all significant events notified (a summary of their analysis for 2020 is given in point 2.4.8) and checks that these events have been processed by EDF. The significant events deemed noteworthy due to their severity or their recurrent or generic nature, undergo an in-depth analysis by ASN. During inspections in the NPPs and the EDF head office departments, ASN checks the licensee’s organisation and the steps taken to learn the technical and organisational lessons from operating experience feedback. 2.4.8 Assessment of facilities compliance with the applicable requirements ASN has regularly pointed out to EDF that the organisational measures adopted to deal with deviations contained shortcomings, that the traceability of the steps taken to process deviations was insufficient and that the time taken to characterise, check and process deviations and inform ASN did not always comply with the requirements of the Order of 7 February 2012. In 2019, EDF therefore revised its internal baseline requirements regarding the management of deviations, in order to improve their processing and ensure that ASN is informed reactively and in a manner proportionate to the safety issues. In 2020, ASN found that the situation was continuing to improve. More specifically, EDF further improved its ability to correct deviations rapidly, even if efforts are still needed on this point. In 2020, EDF again reported several significant events concerning the emergency diesel generators, revealing defects present since they were installed or related to in-service monitoring problems. In this respect, ASN instructed EDF to carry out complete conformity checks on the emergency diesels in a resolution of 19 February 2019 (see box). On this point, some checks will continue to be carried out until the beginning of 2022, given the scheduling of reactor outages enabling them to be performed. In addition to the emergency diesel generating sets, the most significant deviations found in 2020 concerned the seismic resistance of the reactor safeguard and cooling equipment. In 2020, ASN was also particularly vigilant with respect to controlling the conformity of the facilities during the fourth ten- yearly inspection of the Bugey NPP reactor 2. EDF’s monitoring programme was the subject of specific inspections. ASN will continue to be particularly attentive to the conformity of the facilities in 2021 and will in this respect continue its inspections of the condition of equipment and systems. Check on conformity of the electrical power sources In resolution 2019-DC-0662 of 19 February 2019, ASN instructed EDF to carry out checks on the conformity of the electrical power sources for its reactors, in particular the ultimate diesel backup generator sets. During these checks, EDF detected seismic resistance anomalies on 37 reactors. These defects concern the incorrect installation of the elastomer couplings on piping, the corrosion of certain portions of pipes or their supports, connection errors in certain electrical cabinets and electrical cabinet or cooling tower anchor defects. ASN rated this event level 1 or 2 on the International Nuclear and Radiological Event Scale (INES scale) depending on the reactor concerned, according to the nature of the defects encountered and the number of emergency diesel generating sets affected. This event had no consequences on the personnel, nor on the environment. All of the defects detected were repaired by EDF or, with regard to the incorrect installation of certain elastomer couplings, were subject to reinforced monitoring until the next reactor outage, when they will be replaced. In accordance with resolution 2019-DC-0662, the checks on the Nuclear Power Plant (NPP) electrical power sources will continue until the beginning of 2022, notably for those checks which can only be carried out during reactor refuelling outages. 302 ASN Report on the state of nuclear safety and radiation protection in France in 2020 10 – THE EDF NUCLEAR POWER PLANTS