Emergency cooling system for nuclear reactors

DETAILED DESCRIPTION What we claim as new and desire to secure by United States Letters Patent is: 1.
An emergency cooling system for a nuclear reactor comprising: a pressure vessel having a closure head secured in fluid-tight relationship therewith and including liquid supply and discharge ducts for circulating coolant through a core in the vessel, said core including upper and lower core plates having multiple fuel assemblies disposed therebetween which generate heat while undergoing a fission process; said multiple fuel assemblies including selected fuel assemblies containing fuel elements with guide thimbles interspersed therebetween and other fuel assemblies containing fuel elements and guide thimbles having control rods reciprocally movable therein, said control rods being the only control rods present in said nuclear reactor; emergency coolant inlet piping connected at one end to coolant supply means containing emergency coolant under high pressure and its other end to a manifold mounted within the reactor vessel; piping extending from the manifold to distributor means mounted on said upper core plate above only said selected fuel assemblies in the pressure vessel; said distributor means including a support base mounted on said upper core plate surmounting each selected fuel assembly, and laterally extending emergency coolant passageways in said base; means connecting each of said passageways with a corresponding guide thimble mounted in each said selected fuel assembly; and each of said corresponding guide thimbles in selected fuel assemblies having openings in the walls thereof, which openings are spaced along the guide thimble length and are located in a position to spray emergency coolant against the fuel elements in said selected fuel assemblies to absorb heat generated by said fuel elements.
2.
The cooling system according to claim 1 including a coolant outlet for each selected fuel assembly; a mixing device mounted on said distributor means and positioned in at least one fuel assembly outlet, said device having depending nozzles directed toward different quadrants in the assembly so that coolant flowing therethrough into the mixing device provides a mixed coolant having a temperature representative of average temperatures in the assembly; and thermocouple means in the outlet for sensing the temperature of the mixed coolant