LES ACTIVITÉS NUCLÉAIRES : RAYONNEMENTS IONISANTS ET RISQUES POUR LA SANTÉ ET L’ENVIRONNEMENT In 2025, EDF carried out tests on the double-walled containments of two reactors, with satisfactory results. ASNR remains particularly attentive to changes in the double-wall containment leak rates and to the steps taken by EDF to control them. Finally, as part of the fourth periodic safety review of the 1,300 MWe reactors, ASNR considered that the justification of containment performance in an accident with core meltdown should be completed, particularly with regard to the leak-tightness of the seals of the equipment access hatch in the reactor building. 2.4 Organisation for reactor operations 2.4.1 – Reactor operations The Order of 7 February 2012 stipulates that the licensee must have the technical skills needed to manage the activities involved in operation. Furthermore, this Order requires that the licensee define and implement an Integrated Management System (IMS) to ensure that the requirements concerning nuclear safety and protection of the environment are systematically considered in any decision concerning the facility. This IMS must specify the steps taken with regard to organisation and to resources of all kinds, in particular those adopted to control the activities important for the protection of persons and the environment. Normal operation The EDF NPPs are permanently monitored from a control room by an operating team which is also in charge of controlling the installations. The operating limits within which the teams must keep the installation are defined in the RGEs. The licensee ensures that this is done using normal operating documentation, in particular the operating instructions and alarm data sheets. The licensee is regularly required to modify the installation’s configuration to allow intervention by the maintenance crews, to test the availability of a system or to change the status of the reactor. Tests are regularly performed to check the correct working of the systems which could be required in an incident or accident situation and to check the correct behaviour of the reactor’s core. Some tests are performed with the reactor operating, while others can only be carried out during reactor outages. The control teams perform some of these tests themselves, while others require intervention by specialised teams. Operation in the event of an incident or accident The operating strategies and procedures to be implemented in an incident or accident situation are developed in various documents (operating rules and instructions) placed at the disposal of the operating teams. They prescribe the actions to be taken. To manage these situations, the organisation of the control team changes and each person has a specific role. The control teams are regularly trained in the implementation of these control strategies. In addition to the control strategies, an On-site Emergency Plan (PUI), implemented by the emergency crews, is activated to help the control teams in incident or accident situations with a risk of consequences for outside the site. In the event of an accident likely, as a result of a succession of failures, to develop into a severe accident with severe damage to the fuel, the facility’s control strategies give priority to preserving the integrity of the containment in order to limit releases into the environment as far as possible. The implementation of these strategies mobilises the expertise of the local and national emergency teams. 2.4.2 – Assessment of reactor operations ASNR reviews the content of the RGEs before they are implemented and checks that they are correctly applied by means of inspections. More broadly, it ensures that the measures taken by EDF for operation of the reactors are appropriate to the risks created by this operation (see Highlight No. 2). ASNR focuses on the conditions which are favourable or prejudicial to the contribution to NPP safety by the licensees and worker groups. It defines Human and Organisational Factors (HOFs) as being all the aspects of working situations and the organisation which have an influence on the work done by the operators. The general organisation The organisation put into place by EDF to manage risks is on the whole satisfactory. The various programmes, in particular “Start 2025”, have enabled the deployment of robust organisational and technical measures to ensure the reliability of our activities. However, ASNR has identified areas for improvement in certain NPPs in terms of preparation of activities and coordination between maintenance, operation and projects. Weaknesses in the consistency between workload plans, resources allocated and the monitoring of industrial programmes have also been identified. The difficulties observed are often linked to complex organisations and working environments, with interfaces between entities that are not defined or formalised, or with a large number of contacts. Normal operation During its NPP inspections, ASNR notably verifies that the licensee complies with the RGEs and, if applicable, the compensatory messures associated with any temporary modifications. It also checks the consistency between the control documentation and any modifications that have been made to the installations. It also ensures that the procedures used to configure the systems or lock out equipment do actually take account of the requirements arising from the RGEs. 290 ASNR Report on the state of nuclear safety and radiation protection in France in 2025 HIGHLIGHT No. 2 General Operating Rules The General Operating Rules (RGEs) present the provisions the licensee intends to implement to operate its installation in compliance with the safety case. They notably specify the rules to be followed in normal operation, the periodic tests to be carried out and the control operations required in an incident or accident situation. They are one of the items making up the creation authorisation application for commissioning a nuclear reactor. The operating technical specifications included in the RGEs define the parameters required in normal operation. They also identify the systems essential to maintaining the safety functions and specify what to do in the event of momentary unavailability of a required system or if a limit is exceeded. With regard to periodic tests, the RGEs detail the checks to be carried out, their frequency, and the criteria for acceptance of the results. There are in particular tests to check that the reactor core complies with the design baseline safety requirements and the safety case and to calibrate the control and protection systems. The incident or accident situation control procedures, which are also included in the RGEs, detail the steps to be taken by the control teams in these situations in order to restore normal operation or, in the event of an accident, to return the installation to a safe state and limit its consequences. EDF regularly updates these documents in order to incorporate OEF and take account of the modifications made to the reactors. Temporary amendments can also be made. They require justification and the definition of compensatory measures to control any associated risks. Depending on their significance, RGEs noteworthy modifications that could affect the safety of the installation or protection of the environment, require either submission of an authorisation application to ASNR or notification to ASNR before they are implemented.
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