Patent GB-831323-A (GB)
Abstract: 831,323. Handling material in radioactive environment. BABCOCK & WILCOX Ltd. Oct. 23, 1956 [Oct. 24, 1955], No. 30360/55. Class 39(4). An arrangement for conveying spent fuel elements from a nuclear reactor to a storage pond comprises a hoist shaft 4, 5 formed at the side of the concrete biological shield 2 of the reactor, runners 11 guiding a hoist 8 permitting lowering of a container 21 for the fuel elements from the loading position shown in Fig. la to the bottom position shown in Fig. 1b below the level of the pond 6, from where the container may be moved to a suitable position in the pond by a grab 42. The hoist is operated by a cable 13 controlled by a winch motor disposed in a concrete-walled room at the side of the upper part of the shaft, Fig. 2 (not shown). The container 21 is supported by a turntable 12 on the hoist, rotation of the turntable when the hoist is lowered being prevented by a gravity-biased bolt 40 on the hoist, this bolt being withdrawn by a rail 56 when the hoist is in the upper position. A conical top 38 on the turntable co-operates with the recessed underside 34 of the container to ensure accurate positioning of an empty container on the hoist by the grab 42. The container holds forty eight spent fuel element rods 72 each in a separate compartment 32 and is divided by three concentric walls 23 . . . 25 to form three annular spaces, the outer space between wall 23 and the container exterior 22 being subdivided by radial walls to form 24 compartments, and each inner space between walls 23, 24 and 24, 25 being subdivided by radial walls to form 12 compartments. The container is loaded through a rotor 44 having forty-eight passages 46 corresponding to the container compartments 32, alignment of the passages with the compartments when the container is raised being ensured by lugs 43 on the container entering between the bent out ends 53<SP>1</SP> of forks 53 on the rotor, the engagements of the lugs in the forks also effecting a driving connection between the rotor and the container. The rotor is mounted on rollers 47 and is rotatable in steps of 15 degrees by a hydraulic cylinder through a ratchet so that the passages 46 may be brought in succession beneath a discharge tube 62, 63 or 64. The tubes 62 . . . 64 are arranged in-line in the concrete floor 61, the tubes serving respectively, the three annular spaces in which the fuel elements are to be arranged, the upper ends of the tubes being closable by hydraulically operated slide plate valves in housings 65. A spent element discharging machine 67 is loaded with twenty-four elements and run on rails on to an electrically controlled traverser 66 mounted on rails on the floor 61. The machine 67 is locked on the traverser and the latter is moved to one of three positions in which it is locked by a plunger 69 so that a discharge aperture 68 on the machine is opposite one of the tubes 62 . . . 64. Normally the aperture 68 is closed by an hydraulically operated slide plate valve ; connection between the aperture and the selected one of the tubes 62 . . . 64 is established by a telescopic tube 71 on the traverse having two parts 71a, 71b hydraulically operated in opposite directions. Thus by bringiing the traverser to a first position in which the aperture 68 is opposite tube 62 the twentyfour elements 72 in the machine may be emptied into the twenty-four compartments of the outer annular space of the container, lowering means in the machine lowering each element in turn through the tube 71 and a passage 46 in the rotor, the rotor and container being stepped round correspondingly for each element. The machine 67 is refilled with a further twenty-four elements which are emptied into the two inner annular spaces of the container by bringing the aperture 68 opposite the tubes 63, 64 in succession. Air is sucked from the shaft 4, 5 by a ventilating system and discharged in safe manner.