LES ACTIVITÉS NUCLÉAIRES : RAYONNEMENTS IONISANTS ET RISQUES POUR LA SANTÉ ET L’ENVIRONNEMENT Finally, it is attentive to the good understanding and correct application of these various documents by the control teams and the correct management of sensitive activities, which are regularly the cause of anomalies. To do this, it holds interviews with the operating teams and attends operations. Failures to comply with the RGEs constitute significant events which are to be reported to ASNR. ASNR analyses the origin and consequences of these events and, during its inspections, checks that measures have been taken by the licensee to correct the deviations and prevent them from happening again. ASNR considers that reactor control performance has improved in 2025. This is particularly the case for reactor operating events outside the planned limits, the number of which fell sharply in 2025. On the other hand, ASNR has again noted shortcomings in the control of the facility’s system configurations, after a slight improvement in 2024. In 2025, ASNR launched an inspection campaign focusing on reactivity control during reactor operation (see Highlight No. 3). It notes positively that the action plan set up by EDF to improve the reliability and safety of activities that could be the cause of a reactivity control fault has been implemented effectively by the sites. This action plan focuses mainly on getting reactor operators to assimilate the new reactivity control guide, raising managers’ awareness and positioning teams on the expectations of reactor management practices. The number of significant events involving poor reactivity control was significantly reduced in 2025. ASNR also notes that reactors declared as “manoeuvring”, i.e. capable of modulating their power to meet electricity consumption demand (load following), are more in demand from the national electricity network licensee. ASNR inspections show that a large number of power modulations may be requested during the same shift. Even if load control remains a routine activity for control room operators, a change of programme may mean that these operators have to go back to preparing activities that require core power to be stabilised. When they are repeated a significant number of times per shift, these changes can lead to a drop in vigilance, jeopardise the smooth running of other planned activities, such as maintenance or periodic tests, and are likely to lead to human and organisational failures. EDF could usefully analyse the impact of frequent changes in production planning to identify ways of limiting the negative effects. ASNR checks that the periodic tests of safety-important equipment items do effectively check their operation and level of performance. It carries out this verification during the review of RGE modification authorisation applications. During inspections, it also verifies that these periodic tests are carried out in accordance with the test programmes stipulated in the RGEs. Like previous years, the main causes of these significant events relating to periodic tests are incorrect specification of the test rules in the operating documents, errors in application of the test procedure, inconsistencies between documents, or periodic test programming errors. Further to OEF from these events, EDF is adapting its organisations to ensure better sharing of information between the various actors responsible for defining, programming and carrying out tests. To this end, EDF launched an action plan in October 2023, with the aim of implementing more structured support tailored to the sites. In 2024, ASN started a programme of specific inspections on the organisation of the sites for management of periodic tests. These inspections continued in 2025. This campaign highlighted recurring observations such as the lack of formality and clarity in the organisational documentation, training for those involved that does not place sufficient emphasis on periodic testing, shortcomings in the monitoring and supervision of subcontracted tests, a lack of awareness among operators of the controls that take the place of periodic testing, and weaknesses in the management and compliance with deadlines during transfers between shutdown and production periods for the reactors. Nevertheless, the actions undertaken by EDF’s central services in this area since 2023 are beginning to bear fruit, as can be seen in the extent to which the teams concerned are taking the issues in this area on board. Skills management Since the ASN’s inspection campaign in 2023 on skills management for plant operation teams, ASNR notes that the actions taken by EDF have revitalised skills management as a whole. EDF has developed a roadmap at national level, which has been rolled out at site level, setting out a series of measures for managing individual and collective skills. In 2025, the use of a skills management tool was generalised in order to facilitate the mapping of skills and the monitoring of succession planning, particularly for rare and sensitive skills. EDF has also deployed an operational control simulator as close as possible to the control rooms for training in sensitive transients. HIGHLIGHT No. 3 Inspection campaign on reactivity control in operation Nuclear safety is based on the ongoing control of safety functions, including the reactivity of the reactor core. Controlling reactivity means being able to control the nuclear reaction in all planned operating situations and having sufficient shutdown resources available at all times to deal with an incident or accident situation. Recent Operating Experience Feedback has shown that a significant proportion of events linked to a failure to control core reactivity are due to faults in reactor control, control room monitoring or management of the boron concentration in the primary system. In 2025, ASNR launched a specific two-year inspection campaign focusing on those involved in reactivity control. For the nine NPPs inspected in 2025, ASNR examined the management of the reactivity control process and its coordination within the various disciplines, the training of the staff involved in this process, and the operational implementation of the new reactivity control guide by the operating teams. The inspectors also checked compliance with reactor control instructions, in particular as regards management of the boron concentration in the primary system and the manual resumption of control of the rod cluster control assemblies. The inspectors supplemented their observations with in-depth interviews with the staff in charge of these activities and with situational exercises in the control room. During these inspections, ASNR noted the effective national coordination of the network of operators for this process at NPPs, the systematisation of second-level checks on activities related to reactivity control in the control room, and improvements in reactor control practices. These measures help return activities directly linked to reactivity to the centre of control room operational priorities. However, ASNR noted delays at certain NPPs in implementing the planned measures. These notably concerned shortcomings in identifying activities likely to lead to inadequate reactivity control in daily activity schedules, insufficient operability of certain reactor operating support tools, and delays in installing a visual device for situations involving manual control rod operation. ASNR has made a number of requests in response to these observations. Each of the inspections led ASNR to make requests for improvement to EDF. This campaign will be continued in 2026 to cover all NPPs. ASNR Report on the state of nuclear safety and radiation protection in France in 2025 291 01 05 02 06 03 07 04 08 09 10 11 13 12 A / Z
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