- 127 - With regard to the state of the embankment and its general understanding by EDF, ASN considers that the permanent monitoring and seismic alert systems are satisfactory and appropriate. For seismic levels ranging from 0.2g to 0.5g, ASN considers that the countermeasures in place are sufficient so that the consequences of any damage to the embankment, in terms of leaks, remain acceptable for the facility. ASN also points out that because of the particular behaviour of this type of facility (a localised breach leads to complete failure of the embankment) and over and above any demonstration by calculation, the robustness of the canal embankments is based both on their guaranteed state (good understanding of these embankments, management of any problems) and on their constant monitoring. Given the time available, EDF presented the results of an existing study on the failure of the embankments of the Grand Canal dAlsace. According to this study, the potential consequences are the high water level on the site. Concerning the embankment failure scenario, regardless of the origin, EDF proposes: "Initiating a detailed examination of the ability of the embankments to withstand a level higher than the SSE, and determining a flood flow to be considered above the design level (ignoring completely implausible earthquake levels, in order to define the most appropriate countermeasures). In the light of these results, initiating calculation of the corresponding flood fields. In the light of these results, defining and implementing appropriate material and organisational countermeasures to prevent the critical situations which are, for this type of analysis [ ], significant release into the environment by the reactor and dewatering of the fuel assemblies in the fuel building." With regard to the risk of total collapse of the embankment, regardless of the origin, ASN considers the proposal in the CSA report to be satisfactory and notes the clarification made during the examination: "The material measures to be taken in this context would concern reinforcement of the robustness of the embankments (prevention) and/or reinforcement of the protection of the equipment necessary for management of an H1/H3 situation H1/H3 (mitigation), EDF being unable, as the studies currently stand, to issue a definitive position on the technical solutions to be preferred". ASN considers that EDF needs to confirm these elements.
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