Liquid metal-cooled nuclear reactor incorporating a completely passive residual power removal (DHR) system

A liquid metal-cooled fast-neutron nuclear reactor, comprising:

• a vessel referred to as the primary vessel, filled with a liquid metal as the heat transfer fluid of the primary circuit of the reactor;
• a vessel well arranged around the primary vessel, defining an inter-vessel space;
• a top slab for enclosing the liquid metal inside the primary vessel;
• a removal system for removing at least part of both the nominal power and the residual power of the reactor, the removal system comprising:
• a closed circuit filled with a heat transfer liquid comprising:
• an array of a plurality of U-shaped pipes, arranged in the inter-vessel space, being distributed around the primary vessel and each U-shaped pipe extending along the primary vessel with the bottom of the U shapes being adjacent to a bottom of the primary vessel,
• a first collector, referred to as the cold collector, connected to one of the branches of the U, referred to as the cold branch, of each of the pipes of the array, the cold collector being arranged on the outside of the primary vessel, above the top slab,
• a second collector, referred to as the hot collector, connected to the other branch of the U, referred to as the hot branch, of each of the pipes of the array, the hot collector being arranged on the outside of the primary vessel, above the top slab,
• at least one single-pipe heat exchanger, one end of which is connected to the cold collector and the other end of which is connected to the hot collector,
• the circuit being configured such that the heat transfer liquid flows inside the circuit by natural convection and remains in the liquid state both during nominal operation of the nuclear reactor and during shutdown operation of the nuclear reactor releasing residual power;
• a cold source comprising at least one container arranged at a distance from the primary vessel and above the top slab, the container containing a solid-liquid phase-change material (PCM) into which the single-pipe heat exchanger is inserted, the PCM being capable, during the exchange with the liquid metal of the single-pipe heat exchanger, of being in the solid state during nominal operation of the nuclear reactor and of switching to the liquid state during shutdown operation of the nuclear reactor releasing residual power.