- 148 - The ASN specifications required EDF to describe the design measures for preventing loss of the heat sink (for example, several water intakes in different places, use of an alternate heat sink, etc.). The pumping station equipment is subject to safety requirements defined in the heat sink baseline safety standard. EDF indicates in its complementary safety assessments the water intake, the pumping station and the intake channel are monitored firstly through the periodic patrol inspections and secondly through application of the basic preventive maintenance programs (PBMP), which includes taking bathymetric measurements and cleaning channels. The heat sink water levels are monitored permanently, and vigilance, pre-alert and alert thresholds are specified. These thresholds are set such that preventive measures can be taken, particularly regarding the need to increase feedwater supplies, and optimised management of plant unit shutdown with the aim of reducing the residual energy to be removed from the core. In France, no nuclear power reactor apart from the EPR of Flamanville 3 currently under construction has an alternate heat sink (lake, water table or atmosphere). This being said, some NPPs have a larger water reserve through their design. At the Civaux and Cattenom NPPs there are seismic-classified ponds that constitute the heat sink of the ESWS safety system34: dedicated ponds at Civaux giving 10 days' autonomy, Mirgenbach lake with 30 days' autonomy. Another particularity of the Civeaux site is that the safety cooling circuit functions in a closed loop with a forced draft cooling tower associated with the reserve pond (whereas on most NPP sites the safety cooling system is an open loop configuration, the water being taken from and discharged into its natural environment). Lastly, EDF revises the design data periodically during the periodic safety reviews with the aim of reinforcing or improving the robustness of the facility. 34 "SEC" system: Essential Service Water System (which comes directly from the heat sink)
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