Kernreaktor vom Schnellbrütertyp und Verfahren zu dessen Betrieb

1,034,870. Reactors. UNITED STATES ATOMIC ENERGY COMMISSION. Oct. 2, 1963 [Oct. 26, 1962], No. 38762/63. Heading G6C. A fast breeder reactor comprises a plurality of tubes 2 containing fuel in paste form suspended from a first header plate 3, the tubes 2 being closed at their lower ends and in communication at their upper ends with a channel 8 above which is a second header plate 7 from which is suspended a plurality of purge tubes 5, each of which extends almost to the bottom of a fuel tube 2. The fuel tubes 2 are enclosed in a vessel 28 through which liquid sodium coolant is pumped. A slurry of U-containing particles in liquid metal flows through the channel 8 from an inlet 10 to an outlet 11, a small portion of the particles being diverted into the fuel tubes 2 where they settle in the stagnant liquid metal to form a paste. The particles may be composed of U metal or alloy, or a ceramic or other compound containing U such as UO2 or UC. The U particles can contain Pu as well. The liquid metal can be any alkali metal, or bismuth, or gallium. The channel 8 is subdivided by two vertical partitions 9 to form a dual involute spiral channel from the inlet 10 to the outlet 11 (Fig. III, not shown). Above the header plate 7 are two individually rotatable discs 21, 22 containing ports 23, 24 and rotatable about a first 26 by means of a dual drive mechanism 25. On the centre of the assembly is a circular tube (not shown) extending down from the header plate 3 and out through the bottom of the vessel 28, a solid nickel cylinder being arranged to slide freely in this tube. The cylinder is supported so that it may quickly be dropped to a position out of the core region when desired, and slowly restored at will. At frequent intervals determined by the rate of accumulation of fission product gas bubbles in - the paste, a small amount of filtered liquid metal is introduced to the bottom of each fuel tube 2, or small group of tubes, in turn by operation of the discs 21, 22 and through the purge tubes 5 so that bubbles of the metal rise through the paste trapping the fission product gases and finally enter the stream of slurry through channel 8. On a much more infrequent schedule determined by the need for reprocessing of the fuel, the purge system is operated to accomplish the discharge and replacement of the fuel, filtered liquid metal being introduced continuously at the bottom of a fuel tube 2, or group of tubes, and the paste discharged being washed away by the slurr