In addition to the control strategies, an On-site Emergency Plan (PUI), implemented by the emergency crews, is triggered 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 Organisational and Human Factors (OHFs) 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 set up by EDF to control risks is on the whole satisfactory but could still be improved in a few NPPs. In particular, ASN regularly observes that OEF is insufficiently taken into account and that the risk assessments prior to the activities need to be improved. Changes are thus required in terms of preparation of activities. The managerial echelons need to be involved on this subject if concrete, satisfactory results are to be obtained. The shortcomings identified in recent years regarding coordination between disciplines and projects or within the maintenance departments, continued in 2023. The faults observed are often linked to complex organisations, to the large number of parties involved, to undefined or informal interfaces between the entities (shift changes, relations between the shift crews or between the licensee and the contractors), geographical remoteness and failure to plan ahead for concomitant activities. 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 anomalies. To do this, it holds interviews with the control teams and attends operations needed for the NPPs to function. Failures to comply with the RGEs constitute significant events which are to be reported to ASN. ASN 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. In terms of reactor operations and control, ASN considers that performance improved in 2023. The action plans covering operational rigour initiated in recent years by the NPPs appear to be effective. The number of situations for which the reactors were operated outside the prescribed limits remained stable in 2023, even though industrial activity was denser than in 2022 (which was reduced owing to management of SC on many reactors). ASN however finds that the quality of monitoring in the control room once again deteriorated in 2023. ASN reinforced its inspections on the topics of systems configuration management (see box page 301). Even if it observed a fall in the number of Significant Safety Events (ESS) in 2023, linked to systems configuration errors, ASN considers that the management of systems configurations needs to be improved. The RGEs are one of the items making up the commissioning authorisation application for a nuclear reactor. They 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. The operating technical specifications included in the RGEs define the parameters required in normal operation. They 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. Tests are notably required to verify that the reactor core is in conformity with the design baseline requirements and the safety case, as well as to calibrate the automatic control and protection systems. The incident or accident situation control procedures, which are 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 require either submission of an authorisation application to ASN or notification to ASN before they are implemented. GENERAL OPERATING RULES ASN Report on the state of nuclear safety and radiation protection in France in 2023 299 • 10 • The EDF Nuclear Power Plants 10 05 15 08 11 04 14 06 07 13 AP 03 02 09 12 01
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