ASN Report 2017

345 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 12  - EDF Nuclear Power Plants 2017 was marked on the one hand by the activation of the PUI on two occasions by the same NPP – Bugey – and, on the other, by demonstrators breaking into two other NPPs, Cattenom and Cruas-Meysse. These events led to activation of the national emergency organisation by the public authorities and by EDF, as stipulated by the procedures. In 2017, ASN also checked the procedures for updating, assimilating and improving the documents necessary for controlling a degraded situation. This oversight is extended to the procedures for managing and implementing the mobile resources required in an accident or severe accident situation. The inspections carried out in 2017 led ASN to ask EDF to reinforce: ཛྷ ཛྷ the clarity and usability of the documents concerning the use of the mobile equipment in a degraded situation or an emergency situation; ཛྷ ཛྷ its processes for verification and validation of the documents used in an incident or accident situation; ཛྷ ཛྷ the integration of operating experience feedback into the processes for modification of the documents used in an incident or accident situation. In 2018, ASN will check the application of the provisions of its resolution 2017-DC-0592 of 13th June 2017 concerning the obligations incumbent up on BNI licensees in terms of preparedness for and management of emergency situations and the content of the PUI. Most of these provisions have been applicable since 1st January 2018 for nuclear power reactors. 2.4.3 Monitoring maintenance of the facilities Preventive maintenance is an essential line of defence in maintaining the conformity of a facility with its baseline safety requirements. This is an important topic, checked by ASN during its inspections in the NPPs. In order to improve the reliability of the equipment contributing to safety but also to industrial performance, EDF is optimising its maintenance activities, drawing on other practices in use in conventional industry and by the licensees of NPPs in other countries. Since 2010, EDF has thus initiated the deployment of a new maintenance methodology, called AP-913, developed by the American nuclear licensees. The main interest of this method is to make the equipment more reliable through in-service monitoring, in order to improve preventive maintenance. Deployment of the AP-913 maintenance methodology is based on implementation of the following six processes: ཛྷ ཛྷ identification of critical equipment and definition of the associated maintenance and monitoring programmes; ཛྷ ཛྷ definition of equipment monitoring and maintenance requirements; ཛྷ ཛྷ equipment and systems performance analysis; ཛྷ ཛྷ definition and oversight of corrective measures; ཛྷ ཛྷ continuous improvement of baseline requirements and oversight of reliability; ཛྷ ཛྷ equipment lifecycle management. After a review of the deployment of AP-913 in mid-2016, EDF aims to change its practices in order to limit the volume of maintenance work generated and focus performance monitoring on the highest risk equipment and systems. 2.4.4 Evaluation of maintenance ASN considers that the quality of maintenance work could still be improved, given that the number of maintenance work quality defects found remains high. Delays in the performance of checks or in the integration of new maintenance programmes into the documentation and preventive maintenance measures that are inappropriate to the safety functions performed by the equipment concerned, are still leading to the belated detection of deviations or equipment deterioration. Several significant events related to insufficient maintenance were notified in 2017 (see point 2.4.7). Even if the numbers are dropping, ASN still observes activity management problems owing to difficulty with the procurement of spares, in particular because spares are unavailable or non-conforming. The workers still have to deal with constraints linked to work organisation, such as insufficient preparation for certain activities, unplanned scheduling changes and problems with worksite coordination, leading to activity delays or postponements. These difficulties are more particularly encountered with regard to unscheduled activities such as dealing with unexpected events. ASN also regularly observes a lack of rigour in technical oversight of interventions and in monitoring of contractors, along with deficiencies in the traceability of the interventions. The management of maintaining equipment qualification for accident conditions is improving. However, post- maintenance qualification of equipment is not always able to detect any work that has been incorrectly performed. ASN considers that the AP-913 maintenance method will give the licensee a clearer picture of the condition of its facilities and ensure more regular maintenance. However, it considers that proactive measures must be taken by EDF in its NPPs to allow correct implementation and ensure that it is effective. EDF must in particular ensure stricter management and allocate the necessary workforce. EDF must ensure that all participants follow the recommended methods for filling out the equipment monitoring indicators, for the preparation, performance and write-up of field inspections and for the traceability of maintenance decisions. With a view to extending the service life of the NPPs in operation and in the light of the “major overhaul” programme and the lessons learned from the Fukushima Daiichi accident, ASN considers that it is important for EDF to continue the efforts started to resolve the difficulties encountered and improve the effectiveness of its maintenance work (see point 2.6). ASN asked EDF to carry out design reviews. It is also conducting inspections to assess the adequacy of the maintenance operations for the potential and actual degradation modes identified. On this subject, it notes that