- 117 - a VP management rule, which must be applied to all the sites, in order to ensure real-time monitoring of VP tightness breaks, both planned and unforeseen. During the targeted inspections conducted in June and October 2011, ASN observed numerous anomalies regarding the monitoring, maintenance and perimeter of the volumetric protection. For example: the conformity work decided on subsequent to the Le Blayais operating experience feedback, which was to have been completed in 2007, is not finished on all the sites; some sites notified discrepancies observed between the VP perimeter identified in the EDF national level report and the actual situation on the site; some sites notified the fact that it was impossible to test the "waterstop"23 seals, which are a key part of the VP . For example, the Cattenom site declared a significant safety-related event (ESS) regarding flooding of the fuel oil tank room, partly owing to a loss of tightness of the "waterstop" seals; the identification of equipment and structures at the VP limits is absent on some sites; the day-to-day management and monitoring of the VP are not always carried out correctly, sometimes even not at all. Following the submission of the CSA reports, EDF has made the following commitment: "The VP conformity remediation work will be completed on all the NPPs before the end of 2011. With regard to the operational monitoring of the volumetric protection components, EDF confirms that the national VP management requirements will be effectively applied on all sites by the end of March 2012. The problem of the WATERSTOP seals observed at Cattenom has already been dealt with by a conformity remediation action. The maintenance programme for these seals will be reviewed on the basis of this experience feedback. EDF has also conducted an initial analysis of the feedback from the inspections on the Flooding topic. Based on this initial analysis, EDF considers that the nature of the findings is not such as to compromise the safety of the units concerned. By the end of March 2012, EDF will carry out an overall analysis of the findings of the "Post-Fukushima" inspections or the points raised by the NPPs regarding volumetric protection. EDF will then present: - the reactive measures already taken by the NPPs, - the strategy for dealing with findings of a generic nature, - the solutions provided to the requests for extension of the current volumetric protection perimeter." ASN considers that the measures proposed by EDF are satisfactory. Given that VP plays a key role in protecting the plants against the off-site flooding risk and that the anomalies observed are such as to compromise certain conclusions of the CSAs, ASN will be requiring that EDF implement rapid conformity remediation work. In particular, with regard to the waterstop seals, EDF considers that these cannot be subjected to watertightness testing. EDF therefore presented a strategy consisting in examining the stresses and displacement generated by differential settling of the buildings, for all the seals. Where the design of the seals does not enable them to deal with the corresponding displacements and stresses, EDF installed additional tightness strips on the inner wall side. ASN considers that EDF did not take account of seal ageing in its approach. Monitoring of the "waterstop" seals is a key factor in ensuring the effectiveness of the volumetric protection, so ASN will be asking EDF to demonstrate the effectiveness of its strategy and draw up a list of the sites for which an additional system needs to be deployed. EDF has also initiated a specific reliability review in accordance with the conclusions of the 2001-2 SOER report (Significant Operating Experience Report) issued by WANO (World Association of Nuclear Operators). ASN noted that when the licensee identified particular findings, it presented corrective measures. ASN considers that these corrective measures are satisfactory; however, EDF needs to set a deadline for each one. 23 Tightness of the expansion joints in the concrete walls (water stop strip)
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