ASN Report 2018

The detection, characterisation and handling of deviations are covered by regulatory provisions of the Order of 7 February 2012. These provisions are important because they contribute to controlling the conformity of the facilities with the requirements for protection of the interests stipulated by the law, a pre-condition for their operation. Moreover, control of conformity should enable the improvements that result from the periodic safety reviews to be based on a known and robust actual status of the facilities. In recent years, ASN identified the management of deviations affecting NPPs as one of its priority inspection topics. The results of these inspections brought to light difficulties encountered by the NPPs in identifying, characterising and processing deviations. The checks carried out by EDF or requested by ASN in 2018, during reactor scheduled outages and during reactor operating periods, revealed a number of deviations calling into question the ability of certain systems important for safety to perform their functions, such as the electrical systems, control rod assemblies, back-up systems, certain ventilation systems or the heat sink. Some of the deviations identified are linked to failure modes not considered in the design of the reactors. This is for example the case with the significant safety event concerning the lack of seismic resistance of the catwalks on certain 1,300 MWe reactors and the significant safety event concerning the risk of control rod blockage as a result of significant wear on the thermal sleeves of the reactor pressure vessel closure heads (see relevant boxes). Other deviations are linked to poor condition or to non- compliance with the equipment drawings. This is for example the case with the inadequate seismic resistance of certain flanges positioned on the discharge from the emergency service water system (heat sink), or the non-compliance of the supports on the auxiliary piping of the medium-pressure safety injection system pumps. Finally, ASN served EDF with formal notice to carry out the work needed to ensure the compliance of 14 pressure equipment items on certain 900 MWe reactors, which were under-sized. In 2018, ASN carried out a tightened inspection on the topic of identifying and processing deviations in the Cruas-Meysse NPP. In the field, the inspectors more particularly observed several examples of serious deterioration liable to affect the working of various systems (steam generators emergency power supply, emergency generating systems, spent fuel storage pool cooling system). The deviations identified in 2018 and the findings of the inspections lead to the same conclusion as that presented in the 2017 annual report: the actual conformity of the facilities needs to be appreciably improved. In 2018, EDF undertook a revision of its internal baseline requirements applicable to its NPPs in order to improve deviations processing and ensure that ASN receives information that is both reactive and proportionate to the safety implications. In 2018, ASN more particularly noted that EDF’s rapid rectification of deviations had improved. ASN will be particularly attentive as to how the situation develops in 2019 and will in this respect continue its inspections of the condition of equipment and systems. Control of the conformity of the facilities in operation will be a major focus for ASN oversight in 2019, notably on the occasion of the fourth ten-yearly outage inspection of the Tricastin NPP reactor 1. • Analysis of significant events statistics In accordance with the rules concerning the notification of significant events (see point 3.3 of chapter 3), EDF in 2018 notified ASN of 686 significant safety events, 169 radiation protection events and 75 environmental protection events. Table 1 shows how the number of significant events notified by EDF and classified on the INES scale has evolved since 2008. Table 2 shows the trend since 2008 in the number of significant events according to the notification field: Significant Safety Events (ESS), Significant Radiation Protection Events (ESR) and Significant Environmental Events (ESE). Events off the INES scale are also taken into account. Several events which are similar or the result of common causes affect several NPPs. They are grouped under the term Generic Significant Events (ESG). Twenty-six were notified in 2018, of which twenty-five were in the field of safety and one in the field of radiation protection. The number of significant events increased by about 1.5% in 2018 by comparison with the previous year. ASN in-depth inspection at the Gravelines NPP – May 2018 294  ASN report on the state of nuclear safety and radiation protection in France in 2018 10 – EDF NUCLEAR POWER PLANTS