Patent GB-1137501-A (GB)
Title: Improvements relating to means for handling nuclear reactor fuel elements
Inventor: LINDSTAEDT HORST KARL WILHELM
IPC: B23D57/00
Filed: 1965-01-29
Abstract: 1,137,501. Sawing. FAIREY ENG. Ltd. 28 April, 1966 [29 Jan., 1965], No. 4118/65. Heading B5L. A machine for dismantling a nuclear reactor fuel cluster having a plurality of suspended pencils 15 of fuel located by a skeleton locating structure comprises means 39 for supporting the cluster with its axis vertical, cutter means 41, 42, 43, indexing means for rotating the cluster about its vertical axis to bring a selected pencil into alignment with the cutter means which is operable to sever successively parts of the locating structure which retains the pencil against lateral withdrawal, and transfer means constructed and arranged to withdraw the selected pencil laterally from the structure after severance of the pencil retaining suspension. Each pencil may comprise a stainless steel tube containing the fuel and a number of pencils may be secured to an upper plate 16 by projecting studs (20, Fig. 6) and nuts (21), the plate being located on a central tube (17, Fig. 3) having a number of grids (23) disposed along its length for locating the pencils. The lower end of the tube (17) has a shroud (18, Fig. 5) and radial webs (19). The machine consists of a vessel (10, Fig. 1) situated in the pond area of the reactor and has access doors (11) through which the cluster is passed. The vessel has three vertical tubes 35, 36, 37 and the cluster is mounted on tube 37 by a pair of semi-cylindrical clamp members (50, 51, Figs. 2, 8 and 9) which are mounted on arms (53) on the tube 37 and can be moved to engage an adaptor (61) secured to the top plate (16) of the cluster, the adaptor being rotatable in the clamps by rotation through a drive 66 of a rod (65) operating through a toggle mechanism (62, 63, 64) to present a selected pencil to the cutting means. The lower end of the cluster is supported by a sleeve (70, Fig. 5) which is engaged by the central tube (17) of the cluster and carried by an arm (71) from the supporting tube (37). The tube 37 also carries a top horizontal cutter 42 consisting of a milling cutter (72, Fig. 10) driven by a water motor (73) which is movable along a pair of guide rods (74) by a rack-andpinion mechanism driven from a manually operated flexible drive (75), the advance of the cutter severing the stud (20, Fig. 6) supporting the selected pencil and being limited by a switch (76). The tube 37 also supports a lower vertical axis disc cutter 41 driven by a water motor 80 mounted on a lever movable by an hydraulic jack for effecting cutting of the webs (19, Fig. 5) at the lower end of the cluster. The supporting tubes 35, 36 slidably carry a yoke 90 having rods 89 carrying a slide which has further rods at 90 degrees thereto slidably carrying a motor 86 driving a cutter 43 for severing the grids 22 supporting the fuel pencils. In use, a defective cluster (59, Fig. 1) is loaded in the machine by resting the central tube (17) in the sleeve (70) and engaging the clamps (50, 51) with the adaptor, the correct positioning being determined by viewing through a periscope (14). The indexing device (61, Fig. 8) is then engaged with the cluster to permit rotation thereof to align a selected pencil with the cutters. The first cutting operation is effected by cutter 43 to dismember the shroud ring (18). The cutter 41 is then used to sever the webs (19). Thereafter the grids 22 are severed by the cutter 43, the pencils then being suspended only by the studs (20). A transfer device 45 is then engaged with a selected pencil and consists of a pair of tongs (109, 110, Figs. 13 and 14) on quadrants (106, 107) rockable about the centre (108) of the pencil to enclose it without gripping, the quadrants being rocked by gears rotated by a manually operated lead screw (116). The tongs are carried by a slide (102) movable along an arm (100) rotatable about a support tube (44) from a position aligned with a pencil to an unloading position by a lead screw (125). A locating mechanism 140 is associated with the transfer device to determine whether or not the pencil is in the correct position for engagement by the tongs. After the cutting operations by the cutters 41, 43, the transfer device is swung into operative position, a foot 135 being hydraulically moved beneath the selected pencil and the tongs being engaged about the pencil. The cutter (72, Fig. 10) is then advanced to sever the stud, the pencil dropping on to the foot. Thereafter, the device 45 is swung to the unloading position and the foot 135 retracted to permit the pencil to slide through the tongs into a container (13, Fig. 1). The operation is repeated to sever the remaining pencils which are unloaded into a plurality of containers mounted on a turntable (46). Water in the containers damps the fall of the pencils. All the operations of the machine are controlled remotely and viewed through the periscope 14, the machine being operated while submerged in water.