- 55 - 3.3.2 Nuclear fuel cycle facilities La Hague site In accordance with RFS 2001-01, the seismic risk for the La Hague site is characterised by an intensity of VI-VII MSK, for the maximum historically probable earthquake. This intensity is increased by one degree to characterise the safe shutdown earthquake at VII-VIII MSK (SSE). The licensee must identify the equipment participating in the facility's safety demonstration and define requirements with respect to its seismic resistance. With regard to the seismic detection instrumentation and resources, the inspectors asked for justification of the setting of the seismometer controlling the shutdown of operations above the NPH pool. The inspectors also found that the establishment's seismograph had been out of service for eight months and was not considered a priority by the licensee. They also made observations concerning justification of the seismic design of the pool make-up water equipment, especially the buffer tanks. Other requests concerned the management of inspections and periodic tests (CEP): as currently performed, a CEP is unable to test a safety system automatically making the facility safe (stoppage of material transfer) in the event of seismometer unavailability; certain automated safety systems triggered by seismometers are not covered by any CEP. The justification of the continued seismic qualification (calculation or testing) of the equipment performing functions important for safety must be demonstrated (ageing), in particular on the basis of its servicing and upkeep. The inspectors also asked for an overall earthquake or flooding exercise to be held on the site, as an overall exercise of this type has never been organised. For the facilities undergoing seismic strengthening or on which studies are currently in progress, the inspectors observed a lack of any documents indicating the progress of the overall worksite schedule, or tracing any anomalies or delays. The inspectors noted the existence of a seismic vulnerability study on the site's non-nuclear buildings, the conclusions of which had not yet been examined by experts from outside AREVA. Another remark was made during the inspection on the fact that the conformity studies during the safety reviews only covered 10% of the rooms in the nuclear buildings. With regard to potential hazards within the facility, the inspectors requested additional information on the accessibility and protection of the temperature probes on the R4 unit tanks in the event of an earthquake. Conclusion The inspectors noted that the seismic design of certain equipment items, whether this qualification was part of the original design or maintained after modification, needs to be demonstrated, in particular with regard to the instrumentation part. Moreover, the ageing topic needs to be integrated in order to justify the continued seismic qualification of equipment taking part in functions important for safety. In the light of the studies performed, the electrical backup resources for the facilities would probably be damaged by other equipment not designed to seismic standards. This finding needs to be addressed by the licensee so that these resources are kept serviceable and accessible in the event of an incident, even if there is a third safeguard level of electrical backup. In addition, the continued long-term effectiveness (unavailability, CEP) of the seismograph and the correct tripping of the automated safety systems must be reinforced. Finally, a study of the vulnerability of the site's non-nuclear buildings has not yet been analysed and will need to be examined in order to identify the consequences of such an earthquake and in particular its effects on the accessibility of the various site facilities. Tricastin site The recent facilities on the site (Georges Besse II) or those under construction (Comurhex II) are designed to safe shutdown earthquake standards (SSE).
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