- 115 - The material provisions concern the following fields: civil engineering: construction of protective walls, raising or reinforcement of embankments, installation and repair of seals between buildings, installation of pumping systems, raising of equipment, installation of thresholds, etc. mechanical: installation of specific equipment (sluice gates, watertight doors, closures), modification of existing equipment (for example increase in pump capacity or installation of nonreturn valves), and so on. electrical and I&C equipment: raising or relocation of the electrical equipment (in particular I&C), installation of automatic systems or shutoffs (for example for the closures), installation of electrical backups for certain equipment, transmission of alarms to the control room, etc. Subsequent to the evaluation of this "Le Blayais operating experience feedback" approach, and the opinion of the advisory committees in March 2007, ASN considered that the steps planned or already in place on the sites represented significant progress in terms of safety and should provide the power plants with a sufficient level of protection against off-site flooding. However, certain modifications and tasks defined by the "Le Blayais operating experience feedback" approach have yet to be carried out. These modifications primarily concern work to guarantee the peripheral protection of the Cruas and Tricastin sites in the event of the maximum thousand year flood and dam burst, finalisation of the peripheral protection work on the Saint-Alban site, raising and strengthening of the wave protection at Gravelines, installation of an automatic shutdown controller for the circulating water system (CRF) on certain sites, electrical back-up for the plant sewer system (SEO) pumps on the Gravelines and Le Blayais sites and installation of door threshold sills at the entrance to certain buildings on some of the sites. To ensure that this work is completed as rapidly as possible, this issue will be the subject of an ASN requirement. Furthermore, in order to prevent any entrance of water into a perimeter encompassing the buildings containing equipment required to guarantee reactor safety (equipment necessary for emergency shutdown and maintaining a safe shutdown state in the event of off-site flooding), EDF has set up volumetric protection (VP ) on all sites. This perimeter encompasses at least the infrastructures of the premises to be protected (in this case, the perimeter of the VP excludes level +0.00 m); on certain sites, it is extended above level +0.00 m. The choice of the contour takes account of the specificities of each site or the construction constraints. The perimeter of the VP consists of the outer walls of this assembly: walls, floors and ceilings. These walls may comprise openings which could compromise the role of the VP if not watertight (doors, openings, hatches); measures are thus taken accordingly to ensure their watertightness;. Operating measures In addition to the material provisions, EDF presents its operational measures for each site, aimed at protecting the facility against the flood level for which it was designed. The operating measures comprise: alert systems in the event of a foreseeable hazard (failure of a retaining structure upstream of the site, riverside or coastal flooding, possibly combined with extreme winds, rainfall) liable to lead to flooding of the site. These alert systems comprise several surveillance levels: maximum of four phases (watch, vigilance, pre-alert and alert). Depending on the risk to the site, there are not always 4 phases; Agreements with organisations within or outside EDF (Météo France, prefecture, etc.) in order to obtain forecasts concerning the above hazards. special operating rules in the event of a flood (flood RPCs) which are based on alert systems in order to anticipate the steps to be taken to protect the sites in the event of a flood (during the flood rise and fall phases) as well as to prepare for the possible transition to emergency shutdown state. These RPCs in particular make it possible to anticipate and manage the possible isolation of the site; local procedures (in particular clarifying the flood RPCs). These operating measures are determined according to both the vulnerabilities of the sites and and the critical events in the case of flooding, that is isolation of the site, loss of off-site electrical sources, loss of the pumping station and flooding of the site platform.
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