- 233 - Leakage in the "HF storage" area This area comprises two stores, SHF1 and et SHF2, consisting of two separate structural steelwork buildings with a light roof. The structural steelwork supports the service walkways and the pipes. The two storage buildings each contain: HF storage tanks in HDPE (high-density polyethylene) situated in a reinforced concrete retention area; an oil spreading system in a retention area to limit HF evaporation in the event of leakage; two "tanker truck" and "railway wagon" loading stations. The key SSCs identified by the licensee in the event of earthquake or flooding are: the building structure and foundations; the tanks and their anchoring; the tank retention areas. UF6 leak in the "emission" area This area comprises 4 defluoridation lines, each comprising three drying ovens connected to a manifold (one oven in emission, one in deicing and one in cooling or unloading). The key SSCs identified by the licensee in the event of earthquake or flooding are: the "emission" building; the UF6 containers; the container supporting trolleys; the drying ovens. Key SSCs in the "hydrogen yard" area The maximum capacity of this yard is six road trailers each carrying 9 or 18 pressurised hydrogen tanks connected in series. The hydrogen is routed from the yard at a reduced pressure of 8 bars to the W plant buildings, where its pressure is further reduced to 3 bars. The key SSCs identified by the licensee in the event of earthquake or flooding are: the trailers of H2 tanks interconnected in series and equipped with a supply hose, the hydrogen pipes, the pressure-reducing stations and the supply cut-off valve in the event of leakage. Georges Besse II plant The main feared event is leakage of liquid or gaseous UF6 at above-atmospheric pressure (which could occur further to an earthquake of intensity exceeding the SSE). The identified source terms are the liquid reception and sampling autoclaves of the REC II unit. In view of the characteristics of the gas centrifugation process (very small quantities of UF6 used), the consequences of an accident scenario on GB II are identical, whether one considers the design-basis initiating events of the initiating events considered in the complementary safety assessments (CSAs). ASN considers that the identification of the feared situations for the Georges Besse II plant is satisfactory. The La Hague site The feared situations identified by AREVA for the La Hague site are: For risks due to thermal releases of radioactive materials: o loss of cooling of the fuel assembly pools in the NPH, C, D and E unit (time lapse of 6 days before a dose rate of 2 mSv.h-1 is reached in the pool and 10 days for fuel assembly exposure);
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