- 270 - shutoff valves at the oven exits are 3 m above the ground (the remotely controllable valves are installed upstream). Furthermore, the drying ovens are sealed and anchored to the concrete foundation. The Georges Besse II plant The installation platform is situated at an elevation (51.94 m NGFO for the south unit, 54.05 m NGFO for the north unit, 53.00 m NGFO for the REC II unit) that should maintain the sensitive facilities above water in the event of flooding (of level 51.10 m NGFO). The walls and basemats situated below the platform level are made from water-repellent concrete and designed to withstand the hydrostatic pressure of the water table. The backup generator sets and the compressors for producing the compressed air necessary for preserving the centrifuges are also above water. The crystallizing containers, cold traps and equipment other than containers 30B and 48Y of GB II are installed at least 4 m above the level of the platforms. Measures relative to the risk of extreme rainfall events have also been taken at the design stage. Each buffer yard has a storm water retention area. The storm water from the south unit retention area is directed to the storm water tank and the storm water from the north unit and the REC II unit is directed towards the intermediate tank. The storm water tank, which discharges into the river Gaffière, collects the storm water from the roofs and roads of the south unit. The intermediate tank does likewise for the north unit and the REC II unit, discharging the water into the AREVA NC storm water drainage system. Measures to protect the facilities against the flood risk The site systematically receives the meteorological bulletins from Météo France, which represent a pre-alert threshold for all the platform licensees. A local tripartite agreement between the Compagnie Nationale du Rhône (CNR), EDF and AREVA provides for the mutual communication of information in the event of unfavourable climatic situations or a rise in water levels. Georges Besse I plant The licensee's file does not contain any information on the measures to protect the facility against flooding. Comurhex A vertical screen associated with three pumping wells has been installed along the river Gaffière, raising its banks to an elevation of 52.39 m NGFO along the first 200 metres after it enters the site. The licensee indicates that the land is to be further levelled to reach the same elevation over another 200 m. This will give the facility an additional protection barrier. Furthermore, in the event of rainfall of higher intensity than the 100-year return storms, the facilities are shut down and placed in safe condition and the effluents present in the pits are disposed of. Socatri The licensee's file gives no information on the consequences of a flood on the facility. The safety frame of reference for the facility, however, plans for it to be placed in safe condition as soon as the 47.8 m level is reached, with the installation of flood gates at building entrances and raising of the materials above floor level with the units. TU5 W The licensee indicates that the following measures are taken for this facility "HF storage" area: a protective wall surrounds the retention tanks (48 cm for SHF1 and 20 cm for SHF2); "Emission" area: the shutoff valves are closed preventively and production is stopped in the event of flooding. Georges Besse II plant Protection of the facility against the flood risk relies on the elevation of the different key constituents.
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