- 71 - CHAPTER 2 COMPLEMENTARY SAFETY ASSESSMENTS OF THE NUCLEAR POWER PLANTS AND EUROPEAN STRESS TESTS......................................................................................................................75 1 OVERVIEW OF THE FRENCH NUCLEAR POWER PLANT FLEET..................................................... 75 1.1 Description of the nuclear power plants................................................................................................75 1.1.1 Main characteristics..............................................................................................................................76 1.1.2 Description of the main safety systems................................................................................................78 1.2 The main differences between nuclear power plant installations..........................................................83 1.3 The periodic safety reviews...................................................................................................................84 1.4 Use of probabilistic studies in the reactor safety assessment................................................................85 2 EARTHQUAKES.............................................................................................................................. 87 2.1 Design of the facilities...........................................................................................................................87 2.1.1 Seismic level for which the facilities are designed...............................................................................88 2.1.2 Steps designed to protect the facilities from the earthquake for which they are designed....................96 2.1.3 Conformity of facilities with existing safety requirements.................................................................101 2.2 Evaluation of safety margins...............................................................................................................103 2.2.1 Seismic level leading to significant damage of the fuel assemblies...................................................107 2.2.2 Seismic level leading to a loss of containment...................................................................................107 2.2.3 Seismic level leading to non-design-basis flooding............................................................................107 2.2.4 Measures envisaged to reinforce the robustness of the facilities to the seismic risk..........................108 3 FLOODING................................................................................................................................... 109 3.1 Design of the facilities.........................................................................................................................110 3.1.1 Floods for which the facilities are designed.......................................................................................110 3.1.2 Measures to protect facilities from the flooding risk, including in the design process.......................113 3.1.3 Conformity of facilities with the current baseline safety requirements..............................................116 3.2 Evaluation of safety margins...............................................................................................................118 3.2.1 Estimation of margins in the event of flooding..................................................................................118 3.2.2 Measures envisaged to reinforce the robustness of the facilities to the flooding risk.........................124 4 OTHER EXTREME NATURAL PHENOMENA RELATED TO FLOODING.......................................... 128 4.1 Equipment design for these extreme climatic phenomena..................................................................128 4.2 Evaluation of safety margins...............................................................................................................130 4.2.1 Estimation of margins in extreme meteorological conditions ............................................................130 4.2.2 Measures envisaged to reinforce the robustness of the facilities to extreme meteorological conditions ........................................................................................................................................... 132 5 LOSS OF ELECTRICAL POWER SUPPLIES AND COOLING SYSTEMS............................................. 133 5.1 Loss of electrical power supplies........................................................................................................133 5.1.1 Loss of the off-site electrical power supplies.....................................................................................135 5.1.2 Loss of off-site electrical power supplies and conventional backup supplies.....................................137 5.1.3 Loss of the off-site electrical power supplies and of the conventional backup supplies and any other on-site backup electrical power source........................................................................142 5.1.4 Conclusion on the planned measures to protect the facilities against the risk of electrical power supply loss...............................................................................................................................144 5.1.5 Measures envisaged to enhance facility robustness with respect to electrical power supply losses...145
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