- 160 - ASN considers that these water supply reinforcement measures, in their principles are likely to enhance the robustness of the facilities. They have the advantage of reinforcing and increasing the autonomy of the means of making up the primary and secondary cooling systems with the aim of coping with lasting site H1 situations, not taken into account in the current baseline safety standard. ASN considers that this ultimate make-up means must have substantial autonomy and function in a situation of total electrical power supply loss. ASN considers that the other safety objectives of this ultimate make-up means are: to be functional at the natural hazard levels considered in the CSAs, to be able to be implemented under the particular conditions that may be present on the site, especially skyshine irradiation from the fuel stored in the BK building spent fuel pit (low water inventory), to be able to be implemented within a time scale compatible with the envelope scenario considered, to allow boration of the water injected into the primary system. ASN will issue a requirement on this subject. ASN draws attention to the fact that the quality of the make-up water must be compatible with its used by the safety equipment (EFWS pumps, EVU spray nozzles on the Flamanville 3 EPR, etc.) and that the necessity to constitute a stock of boron for the replenishing of the PTR tank will have to be studied. The risks that wells descending into the water table could represent in the event of a severe accident will also have to be taken into account. EDF is taking other complementary measures: EDF has indicated that it was defining a "hard core" of equipment items comprising a limited number of structures, systems and components strictly necessary for the management of a whole-site H1+H3 situation, and therefore the safety objective is to prevent large radioactive releases into the environment. EDF has specified : "this hard core will include key existing and complementary equipment items (fixed or mobile), some of which serve to prevent entry into a severe accident (SA) condition (severe accident prevention)". EDF will verify the adequacy of the current water reserves of the auxiliary feedwater system (EFWS) for the steam generators (in 2012); EDF undertakes to reassess the minimum thresholds of the TS for the SER tanks in order to guarantee the targeted autonomy; EDF undertakes to implement additional pumping means for making up the primary and secondary cooling systems o motor-driven cooling pump in the primary system open states on the 900 MWe series, o ultimate backup diesel generator (DUS) to supply one CVCS pump and one EFWS motor-driven pump on all the reactor series. EDF envisages installing a motor-driven cooling pump for injecting water into the core from the PTR tank in situations of total loss of the electrical power supplies (before 2015); EDF envisages installing an ultimate backup pumping unit specific to each plant unit and having an ultimate make-up means that will draw water from the water table or from large-capacity ponds to enhance the reliability of the spent fuel pit top-up function; EDF will conduct studies and make operating procedure changes to limit the risk of a breach at the primary pump seals if their cooling is lost. Specifically for the EPR reactor, EDF plans: to reinforce the facilities' robustness against flooding limit water ingresses via the slabs in the pumping station and outfall structures. This provision concerns the EFWS, JAC, SEC and SRU systems used in H1 situations.
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