- 120 - ASN considers that the additional 1 metre adopted by EDF to characterise the marine hazard for coastal sites in the CSAs goes significantly beyond the marine levels currently utilised for these sites and thus meets the requirements of the specifications. 3. For river sites: Augmented river flood: 30% increase of the CMM rate of flow. Moreover, following submission of the CSA reports and on the occasion of the examination of these reports by IRSN, EDF made the following undertaking: "For sites on which the platform is currently considered to be above water level in the case of a maximum river flood scenario, particularly Tricastin and St Alban, EDF will examine (by end 2012) whether any phenomena induced by this type of flood on the behaviour of hydraulic structures are liable to lead to a revision of the levels adopted in the initial evaluations. The conclusions of this complementary analysis will be taken into account for the protection of the equipment in the "CSA hard core". For the particular case of the Tricastin NPP mentioned in the IRSN recommendation, EDF underlines the fact that the planned modifications to the Donzère-Mondragon hydraulic facility, to guarantee site protection against the CMM, provides for the creation of a emergency safety device (lateral weir on the right bank) designed to limit the level in the canal, including in the event of a malfunction of the facility's hydraulic systems." ASN considers that the 30% increase on the river flood adopted by EDF in its CSA reports goes significantly beyond the river flood levels currently used for its sites and thus meets the requirements of the specifications. The results given in the CSA reports are however to be considered in the light of significant uncertainties surrounding these initial evaluations. The behaviour of hydraulic structures in the case of the maximum river flood scenarios would need to be examined in greater detail, in particular for the Tricastin and SaintAlban sites. Earthquakes initiating dam bursts (including Le Blayais): EDF proposes performing additional studies on an earthquake initiating a dam burst (to confirm that the site protections against the flooding caused by this dam burst cannot be destroyed by the earthquake) and on an earthquake liable to cause several dam bursts (to confirm that the site flood protections are sufficient). During the course of the examination, EDF made the following undertaking: "For the purpose of the studies concerning the effects of dam bursts caused by an earthquake "beyond baseline safety standards", mentioned in the RECS, EDF will consider the induced risks to the equipment in the "CSA hard core" by multiple dam bursts situated in the same valley." ASN considers that the approach adopted by EDF and its undertaking provide a satisfactory response to the specifications. ASN will nonetheless be asking EDF to supplement its rainfall scenarios beyond design-basis, extending them to all sites. 4. EDF also studied other augmented scenarios when considering the flooding induced by an earthquake beyond design-basis or specific site characteristics, in particular flooding caused by the loss of integrity of the SEA (demineralisation plant water supply system) circulating water ponds (Flamanville, Penly and Paluel). Concerning the collapse of the SEA ponds on the three sites, EDF considers that the stability of the ponds is guaranteed for an earthquake bigger than the SSE. ASN considers that this approach is satisfactory, provided that the tightness of these ponds is guaranteed, in particular as EDF considers the SEA pond to be the emergency make-up source. Water heights resulting from the augmented rainfall scenarios and earthquakes beyond design-basis EDF calculated the water level resulting from the augmented scenarios, considering the protections implemented on the site for protection against the design-basis hazards, including those for which implementation is planned subsequently (for example 2014 for Cruas and Tricastin). ASN considers that this approach does not conform to the specifications and that EDF needs to take account of the real status of the facilities as at 30th June 2011.
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