Patent Number: 050080695
Section: claims

1. In a nuclear reactor system which includes a pressure vessel containing a reactor core and an aqueous neutron-absorbing liquid, the improvement wherein a circulation system is connected to said pressure vessel through which liquid and/or steam and any uncondensable gas can circulate, said circulation system including a cooling device which comprises an evaporator in an evaporating pool,  a first conduit which extends from an outlet opening in an upper part of said pressure vessel to said evaporator,  a second conduit which extends from said evaporator downwardly to an inlet opening in said pressure vessel, said inlet opening being located below said outlet opening,  a discharge vessel that includes at least one outlet for gas and steam and for maintaining a lower pressure therein than in said evaporator, and  a third conduit connected to said second conduit at a point above a bottom of said second conduit and extending to said discharge vessel, said third conduit enabling a small portion of fluid flow in said second conduit to pass therethrough. 2. A nuclear reactor system according to claim 1, including a fourth conduit connected to said first conduit at a point above a bottom of said first conduit and extending to said discharge vessel, said fourth conduit enabling a small portion of fluid flow in said first conduit to pass therethrough. 3. A nuclear reactor system according to claim 1, wherein said discharge vessel includes an outlet at a lower end thereof for liquid and is partially filled with liquid. 4. A nuclear reactor system according to claim 1, including a heat sink and another conduit which extends from said evaporator pool to said heat sink. 5. A nuclear reactor system according to claim 4, including a concrete containment vessel in which said pressure vessel and said evaporation pool are located, said heat sink being located outside said containment vessel. 6. A nuclear reactor system according to claim 1, including a heat sink and an additional conduit which extends from said discharge vessel to said heat sink. 7. A nuclear reactor system according to claim 6, including a concrete containment vessel in which said pressure vessel and said discharge vessel are located, said heat sink being located outside said containment vessel. 8. A nuclear reactor system according to claim 6, including a concrete containment vessel in which said pressure vessel and said discharge vessel are located, wherein said heat sink comprises a tank containing a liquid pool located in said containment vessel below said discharge vessel, said additional conduit extending through a space in said containment vessel from said discharge vessel to below a surface of said liquid pool in said tank, and sealed means providing communication between said liquid pool and said space. 9. A nuclear reactor system according to claim 1, including a concrete containment vessel in which said pressure vessel and said evaporation pool are located. 10. A nuclear reactor system according to claim 1, including a concrete containment vessel in which said pressure vessel and said discharge vessel are located.