Patent Number: 044877420
Section: claims

1. A fast neutron nuclear reactor comprising a vertically axed vessel containing the reactor core and a volume of liquid metal for cooling the same, a horizontal sealing slab sealing the upper part of the vessel, at least one pre-vacuum pump and at least one heat exchanger respectively ensuring in operation the circulation of the liquid metal in the core and its cooling, as well as at least one device for removing the residual power ensuring the cooling of the liquid metal in the case of a stoppage of the pre-vacuum pumps, wherein the residual power removal device comprises an evaporator incorporating a bundle of tubes in glove finger-like form immersed in the liquid metal, so as to pass into the vapour phase a heat transfer fluid initially in the liquid phase, an adiabatic collector of said vapour phase incorporating a pipe traversing the reactor slab and a condenser in which the heat transfer fluid in the vapour phase exchanges its heat with an external cooling fluid and condenses in the liquid phase before dropping again into the evaporator by the adiabatic collector and wherein the wall of the pipe constituting the collector, as well as the wall of each of the tubes of the evaporator internally have a capillary structure piping the heat transfer fluid in the liquid phase. 2. A nuclear reactor according to claim 1, wherein the heat transfer fluid is mercury. 3. A reactor according to claim 1, wherein the condenser comprises a caisson or box in which are located at least one substantially horizontal and rectilinear supply collector connected to the upper end of the pipe constituting the adiabatic collector, two condensate receiving collectors positioned below the supply collector and on either side of the vertical plane passing through the latter and two planar bundles of fin tubes connecting the supply collector to the condensate receiving collector in order to define a dihedron with substantially horizontal edges, the cooling fluid being atmospheric air which then enters the box via the interior of the dihedron and leaves it by a chimney or flue positioned above the bundle of tubes. 4. A nuclear reactor according to claim 1, wherein the upper end of the bundle of tubes is installed on a tube plate constituting the lower end of the adiabatic collector and the upper end of each of the tubes projects over a given height above the tube plate in order to define a buffer reservoir for the heat transfer fluid in the liquid phase. 5. A nuclear reactor according to claim 4, wherein the upper end of each of the tubes projecting above the tube plate has at least one row of slits and/or holes on its periphery. 6. A reactor according to claim 1, wherein the evaporator also has a ferrule surrounding the bundle of tubes, which is open at its lower end and has at least one inlet port at its upper end. 7. A reactor according to claim 1, wherein the condenser is supported by the reactor slab and is located in the reactor enclosure. 8. A reactor according to claim 1, wherein the condenser is positioned externally of the reactor enclosure. 9. A reactor according to claim 1, wherein the condenser comprises a caisson or box in which are located a toroidal supply or feeding collector connected to the upper end of the pipe constituting the adiabatic collector, a toroidal collector for receiving the condensate positioned below the supply collector and an annular bundle of fin tubes connecting the supply and condensate receiving collectors, the external cooling fluid being atmospheric air which enters the box by a lateral pipe and leaves it by a chimney or flue positioned above the supply collector.