Patent Number: 042499950
Section: claims

1. A liquid-metal cooled nuclear reactor comprising an open-topped main vessel having a vertical axis and containing liquid metal, a reactor core, an inner vessel mounted and coaxial within the main vessel, and an inner vessel extension in the form of a transverse skew wall provided with a downwardly-bent edge joined to a structure connected to said main vessel, said skew wall being transversed by cylindrical sleeves providing a leak-tight passage for the bodies of pumps and heat exchangers disposed at intervals around the reactor core, a baffle extending above said skew wall and delimiting therewith a space containing a practically static volume of liquid metal which forms a thermal screen between hot liquid metal located within the inner vessel above said baffle and cold liquid metal located between the inner vessel and the main vessel beneath said skew wall. 2. A liquid-metal cooled reactor according to claim 1, wherein the skew wall has the shape of a portion of a torus of revolution about the axis of the main vessel and has an inner and an outer edge and is joined by means of conical walls to the inner vessel at its inner edge and to the structure which is connected to said main vessel at its outer edge. 3. A liquid-metal cooled reactor according to claim 1, wherein the baffle has a horizontal surface which rests freely on stationary bearing members and is provided on its internal and external peripheries as well as at the point of penetration by each cylindrical sleeve with a downwardly-extending side portion which is immersed in the liquid metal and traps a blanket layer of neutral gas beneath the horizontal surface of said baffle. 4. A liquid-metal cooled reactor according to claim 1 or 2, wherein the baffle is constituted by a single unit supported on the stationary bearing members by means of sliding contacts. 5. A liquid-metal cooled reactor according to claim 4, wherein the baffle is constituted by adjacent sectors in juxtaposed relation and provided successively with overlapping edges for ensuring continuity of the baffle, each sector being joined to one of the cylindrical sleeves through which a pump or heat exchanger is intended to pass. 6. A liquid-metal cooled reactor according to claim 4, wherein the baffle is provided with circumferential ribs. 7. A liquid-metal cooled reactor according to claim 1 or claim 2, wherein the baffle is self-supporting and inclined towards the axis of the main vessel, said baffle being provided with an extension in the form of a lateral and vertical bearing shell placed within the inner vessel. 8. A liquid-metal cooled reactor according to claim 7, wherein the baffle is provided at its periphery and around the sleeves with downwardly-directed side portions extending parallel to the axis of the main vessel to the bottom level of the baffle, said side portions delimiting a plurality of annular spaces with lower ends which open into the hot liquid metal located above the baffle and within the space containing the volume which forms a thermal screen. 9. A liquid-metal cooled reactor according to claim 7, wherein the baffle is provided at its periphery and around the sleeves with upwardly-directed side portions extending parallel to the axis of the main vessel, said side portions delimiting a plurality of annular spaces with upper ends which open into a gaseous atmosphere located above the hot liquid metal, orifices being also formed in the lower portion of the bearing shell which supports the baffle.