monitoring overly focused on quality assurance and safety rules, to the detriment of actual technical operations, contractors lacking certain required skills, etc.). EDF also initiated a process to bring certain skills back in-house to ensure better monitoring. The situation varies among the sites. 2.5.3 Regulation of the conformity of facilities with the applicable requirements Maintaining the conformity of the facilities with their design, construction and operating requirements is a major issue insofar as this conformity is essential for ensuring compliance with the safety case. The processes employed by the licensee, notably during reactor outages, contribute to maintaining the conformity of the facilities. The identification and processing of deviations The checks initiated by EDF within the framework of its operating baseline requirements and the additional verifications requested by ASN, on the basis more particularly of operating experience feedback, can lead to the detection of deviations from the defined requirements, which must then be processed. These deviations can have a variety of origins: design problems, construction errors, insufficient expertise in maintenance work, deterioration through ageing, organisational shortcomings, etc. The steps taken to detect and correct deviations, specified in the Order of 7 February 2012, play an essential role in maintaining the level of safety of the facilities. “Real-time” checks Carrying out periodic test and preventive maintenance programmes on the equipment and systems contributes to identifying deviations. Routine visits in the field and technical inspection and verification of activities considered to be important for the protection of people and the environment are also effective means of detecting deviations. 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 already known deviations, 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 deviations with respect to the protection of people and the environment for the coming production cycle. Ten-yearly verifications: conformity checks EDF carries out periodic safety reviews of its nuclear reactors every ten years, in accordance with the regulations (see point 3.2). 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 are supplemented by a programme of additional investigations, the aim of which is to check parts of the facility for degradation modes which are not covered by the inspections involved in the 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, further 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. ASN requirements concerning repairs ASN published its Guide No. 21 in 2015 regarding the handling of conformity 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 proportionality principle. 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. 2.5.4 Assessment of oversight of facilities compliance with the applicable requirements Condition of equipment and conformity In the past, ASN has found that the organisational measures taken by EDF to deal with deviations comprised shortcomings 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 proportionate to the safety implications. Since these new internal baseline requirements have been applied, ASN finds that in most situations, EDF corrects the deviations within the required time. These efforts will need to be continued in the coming years, notably on the occasion of the ten yearly outages. Significant events concerning several reactors were once again reported in 2024 following the detection of conformity deviations; some of these deviations date back to Thermal discharges from the NPPs during periods of heatwave or drought To help cool its reactors, an NPP takes water from a watercourse or from the sea. The water returned to the watercourse is at a higher temperature, which warms up the watercourse downstream of the plant. This represents a few degrees for NPPs without cooling towers and a few tenths of a degree for those with them. These warm water discharges, known as thermal discharges, are liable to have an impact on the aquatic environment. They are thus regulated by ASN resolutions specific to each NPP. These set limits for heating of the watercourse between upstream and downstream of the plant and the maximum temperature downstream of it. When these limits are liable to be exceeded, the licensee reduces the power of the reactors and may even shut them down completely. These power reductions notably take place during periods of heatwave or drought. ASN defined a second, higher, limit level, applicable when the manager of the Réseau de Transport d’Électricité (RTE) expresses the need to maintain a minimum power to ensure the security of the grid. This applies with no intervention on the part of ASN, which is informed, as are the other administrations concerned and the Local Information Committee (CLI). It is associated with a reinforced environmental monitoring programme. In the event of an exceptional situation and public necessity, ASN may also temporarily modify the limits it has defined. This was the case in the summer of 2022. Faced with the continuing increase in the effects of climate change, ASNR considers that a medium and long-term vision is required to address the thermal discharges in a heat wave period, given their implications for each region and the potential combined effects linked to the presence of several NPPs in the same catchment area. ASN Report on the state of nuclear safety and radiation protection in France in 2024 313 01 The EDF Nuclear Power Plants 10 02 03 04 05 06 07 08 09 11 12 13 14 15 AP
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