Operation in the event of an incident or accident The operating strategies and practices to be implemented in an incident or accident situation are developed in various documents (operating rules and instructions) placed at their disposal. They specify what action is to be taken by the control team. 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. Following an accident, if the safety functions (control of reactivity, cooling and containment) are not guaranteed owing to a series of failures, the situation is liable to develop into a severe accident with severe fuel damage. When faced with such situations, the installation control strategies place emphasis on preserving the integrity of the containment in order to minimise releases into the environment. The implementation of these strategies mobilises the expertise of the local and national emergency teams. 2.4.2 Assessment of reactor operations and operational documentation ASN 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. ASN focuses on the conditions which are favourable or prejudicial to the contribution to NPP safety by the operators 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. However, ASN has identified areas of improvement for certain NPPs regarding coordination between the professions and the projects, within maintenance departments and operating teams, and with respect to consistency between workload plans, the resources allocated and monitoring of the industrial programmes. The difficulties observed are often linked to increasingly complex working organisations and environments, the large number of parties involved, the interfaces between entities that are not defined or formalised (shift changes, relations between the shift crews and the crews not on shift, or between the licensee and the contractors), geographical distance, poor anticipation of concomitant activity situations, lack of resources (human and material) and documentation densification (see box page 308). Normal operation During its NPP inspections, ASN notably verifies that the licensee complies with the RGEs and, if applicable, the compensatory measures 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. 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 Inspection campaign on the control of system configurations Ensuring the correct configuration of the hydraulic and electrical systems of nuclear reactors contributes to the safety of the installations. The configuration of the systems covers line connection activities (configuration of a set of devices enabling a system to function in the way it was designed), lock-out (configuration of a set of devices in defined and locked positions in order to guarantee the required safety conditions for maintenance work) and administrative lock-out (physical immobilisation of a set of devices, which must be kept in this position for the safety of the installation). After observing a rise in the number of line connection and lock-out errors at the end of 2022, compromising the safety of the installations or leading to a risk of personnel accidents, ASN began a campaign of inspections in 2023 dedicated to checking the steps taken by EDF to control the configuration of the systems in the installations. In 2024, ASN completed this campaign, which allowed inspection of all the NPPs. The inspectors examined the oversight of all the processes contributing to control of systems configuration. They also carried out checks on the conformity of the configurations of the installations and observed the performance of certain activities. Finally, they conducted clarification interviews with the personnel in charge of these activities. This inspection campaign revealed the quality of monitoring of the processes linked to this topic, but also shortcomings in the preparation and performance of these activities. In 2024, ASN reminded EDF of the need to give greater importance to the administrative lockout activity and to clarify the immobilisation practices for the locked-out devices. It also asked EDF to check the pertinence of the system for immobilising valves under administrative lock-out and involved in fire-fighting. Finally, it alerted EDF to the need for long-term continuity of the position indicators installed on the devices subject to administrative lock-out. At the end of this campaign, ASN positively notes the efforts made by EDF to improve the performance of the tools designed to take account of the actual configuration of the systems when programming maintenance work. In 2024, EDF also set up periodic skills currency courses for the staff directly involved in systems configuration. The EDF head office departments reinforced their coordination of the administrative lock-out process with the site licensees. These various actions are such as to improve the performance of systems configuration in the coming years. 306 ASN Report on the state of nuclear safety and radiation protection in France in 2024 The EDF Nuclear Power Plants
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