- 246 - the supporting structures of the plant 130 and 140 generator sets would withstand the MHPE; the structures of the gallery interlinking the plants would withstand the SSE; the structural steelwork would also withstand the SSE. Resistance to the SSE is globally ensured for the Programme Resource Department (DRP) building. However, the stability of the blocks of annex U cannot be substantiated. Destruction of this building could lead to an criticality accident due to the presence of enriched uranium and hydrogen, and a violent exothermic reaction resulting from with the presence of ClF3 and hydrogenated compounds. Comurhex The majority of the units are not designed to withstand the SSE. The licensee had envisaged several reinforcements but none has been scheduled due to the forthcoming shutdown of the facilities. Socatri According to the safety documents, the only equipment items or structures designed to withstand the SSE are: building 63B (stockers upstream of STEU); the safe-geometry storage of spray unit 19D; building 64D (license to operate pending). The licensee has not assessed their behaviour in the event of an earthquake intensity exceeding the SSE. TU5 unit The process building, the facilities in the stripping zone and the effluent storage zone are designed to withstand the SSE in accordance with RFS I.2.c of 1981. W plant (ICPE) The licensee indicates that the structures of the buildings and the retention area are designed to withstand the SSE. For tanks SFH1 and SFH2 however, cracking or partial rupture at the joint between the skirt and the bottom of these tanks is to be feared in the event of an earthquake. AREVA points out in this respect that the SSE behaviour of the "emission" zone must be studied, as this part of the facility is unlikely to be stable in the SSE or even the MHPE. AREVA has moreover announced that a project to replace the storage tanks in being studied, and that it plans verifying the earthquake resistance of the emission zone in the first half of 2012. As regards the behaviour of the W plant in an earthquake exceeding the SSE, AREVA indicates that an earthquake of magnitude 6 would cause major structural damage. With regard to the storage yards, yards P08 and P09 are not designed to withstand the SSE. Georges Besse II plant and Comurhex II facility The Georges Besse II plant (GB II) (civil engineering structures and equipment housing the UF6 of the North and South Units and of REC II) and the Comurhex II facility have been designed integrating paraseismic measures dimensioned for the SSE in accordance with current design methods. The measures taken in the studies and construction of the civil engineering structures for GB II, and the verification calculations performed for each building show that the seismic coefficient is greater than 1.5 for deformations remaining within the elastic domain (thereby guaranteeing that the facilities meet the assigned safety requirements) and enable a seismic coefficient of 3 to be retained at the upper limit of the plastic domain. According to the licensee, the verification calculations performed for the equipment items confirm a margin of at least 15% at any point with respect to the elastic limit of the materials. For the Comurhex II facility, the civil engineering structures design integrated a margin of 15% on the reinforcements as a provision.
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