Patent Number: 040240185
Section: claims

1. A liquid metal cooled fast breeder nuclear reactor comprising: a primary vessel containing a pool of coolant,  a reactor core submerged in the pool of coolant,  a transfer rotor submerged in the pool of coolant alongside the reactor core, the transfer rotor being rotatable about a vertical axis and having an annular series of apertures disposed about said axis,  a plurality of elongate thimble shape containers for receiving fuel assemblies disposed one in each of said apertures,  a plurality of helical coil compression springs mounted on and carried by said rotor each spring operatively engaging and elastically supporting one of said containers in upright position in its aperture, and  at least one hydraulic dash pot located directly below the path of the containers arranged so that, by rotation of the rotor, the containers are successively brought into register with the dash pot, the construction and arrangement being such that the momentum of a falling fuel element is transferred to the container and then to the dashpot, and after arrest of the container and fuel element they are returned to normal operating position of the container by the associated compression spring. 2. A liquid metal cooled fast breeder nuclear reactor according to claim 1 having a second helical coil compression spring in each aperture of the rotor, the second helical coil compression spring being reactively opposed to the first helical coil compression spring and the container being elastically suspended between the springs. 3. A liquid metal cooled fast breeder reactor according to claim 2 wherein the dash pot comprises a piston within a static cylinder, the piston having a horizontal plane surface arranged for impact with a descending container. 4. A liquid metal cooled fast breeder nuclear reactor according to claim 2, wherein the hydraulic dash pot comprises a static cylinder arranged for receiving the lower end of a descending container, the lower end of each container being adapted to form a piston for the dash pot.