ASN Report 2017

344 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 12  - EDF Nuclear Power Plants Operation in a severe accident situation Following an incident or 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 following severe fuel damage. When faced with such unlikely situations, the installation control strategies place emphasis on preserving the containment in order to minimise the consequences of the accident (see chapter 5, point 1.3.1). The implementation of these strategies requires the participation of the local and national emergency teams. These teams use the On-site Emergency Plan (PUI) plus the severe accident operation guide and the emergency team action guides in particular. ASN periodically examines the strategies presented by EDF in these documents, in particular for the reactor periodic safety reviews. 2.4.2 Assessment of reactor operations Normal and degraded operation The technical anomalies with serious potential consequences observed in 2017 and described in this chapter, as well as the difficulties experienced by EDF in managing activities during reactor outages, lead ASN to consider that the quality of operation of the NPPs is less satisfactory than in 2016. Certain recurring operations, such as the performance of periodic tests and of hardware modifications, were the cause of deviations during their preparation, which could not be prevented by EDF’s error-reduction practices. As in 2016, non-compliance with the operating technical specifications is the cause of a considerable number of significant events. This is frequently owing to the incompatibility between the available resources and the workload, or the inappropriate nature of some of the resources made available to the personnel. ASN also observes breaches of basic safety culture, that is a rigorous and prudent approach with a questioning attitude, in particular when designing and applying periodic test rules and technical operating specifications. In the light of these observations, ASN reinforced its checks on the application of the user-centred design approach when examining changes to the general operating rules. ASN observes that in 2017 the degree of compliance with the opinions of the Independent Safety Organisation (FIS), deployed within each EDF entity, is down in some NPPs. This trend demands an in-depth analysis. At this stage, ASN considers this to be a warning sign with regard to the working of the EDF decision-making process in situations in which the required actions must give priority to the protection of interests over expected economic or industrial advantages. This warning sign leads ASN to reinforce its oversight of the FIS actions and how its opinions are taken on-board. ASN considers that the periodic test performance methods to ensure correct operation of the equipment could be improved. Errors in drafting and implementing periodic test rules are observed and lead to a relatively high number of significant safety events. These errors reveal specific organisational failures at EDF which ultimately weaken the level of safety in the facilities. ASN also observed that the organisation implemented by EDF in its NPPs did not allow correct assimilation of the defined requirements associated with the In-core Instrumentation System (RIC) during operation. The sharing of responsibilities between the mechanical and electrical departments, along with the use of outside contractors for maintenance of this system, led to management errors by the licensee, leading to the numerous malfunctions observed in 2017. Operating rules in the event of an incident or accident Conduct in an incident, accident or emergency situation In 2017, ASN carried out twenty-one inspections on EDF’s organisational and technical provisions in the event of an incident, accident, severe accident and emergency situation. Two reactive inspections, further to events, were carried out following activation of the PUI on the Bugey NPP. The inspections on the organisation and emergency resources revealed that the organisation, preparedness and management principles for emergency situations covered by a PUI have been correctly assimilated. The teams in charge of implementing this organisation would appear to be correctly sized with respect to the requirements specified in the licensee’s baseline requirements. Although operating experience feedback from exercises and actual situations is correctly identified by EDF, it does not fully assimilate it, given that certain points requiring improvement are identified time and time again. However, this operating experience feedback shows that the relations between each NPP and the third-parties involved in the management of an emergency situation (hospitals, emergency services) are satisfactory and enhance the interest of such exercises. FUNDAMENTALS The Independent Safety Organisation (FIS) EDF’s in-house Independent Safety Organisation (FIS) verifies the actions and decisions taken by the departments in charge of operating the installations, from the viewpoint of safety. On each NPP, the FIS comprises safety engineers and auditors, who conduct a daily check on the safety of the reactors. The working of each FIS is checked and evaluated at a national level by the FIS at EDF’s Nuclear Production Division. Finally, the EDF nuclear inspectorate, in particular the general inspector reporting to the Chairman of the EDF group, assisted by a team of inspectors, represents the highest level of independent verification of nuclear safety within the EDF group.