Patent GB-942290-A (GB)
Title: Manipulating devices for actuating securing devices for fuel elements in nuclear reactors
IPC: G21C19/16
Filed: 1961-05-23
Abstract: 942,290. Fuelling reactors. SULZER FRERES S. A. May 23, 1961 [ June 8, 1960], No. 18606/61. Heading G6C. Fuel elements 38 through which coolant flows through connections 36, 37 leading to inlet and outlet pipes 34, 35 in a support 31, are supported by bayonet-type projections 42 on the lower end of a sleeve 40 engaging corresponding projections 43 on the fuel elements. The sleeve 40 is mounted for sliding and limited rotational movement on the support 31, the latter being H-shaped and secured by a stud 33 to the moderator shield 30, each support serving to carry two fuel elements by means of two sleeves. An upward thrust is exerted on the sleeve 40 by cup springs 48 acting on a pin 45 slidable in the upper end of the sleeve, the pin engaging a hollow screw 44 threaded into the sleeve. To permit the fuel elements to be charged or discharged by conveyer apparatus (not shown) situated at the other side of the core, i.e. beneath, a tool must first be employed for releasing the bayonet support 42, 43 by rotating the sleeve 40. Such a tool comprises four concentric tubes A, B, C, D carried by a frame 102 mounted on an anti-radiation screen 101 supported for movement, by means not shown, above the shield 30. The inner tube D includes an optical system 63 comprising prisms 127, 128 and tubes 125, 126 whereby the tool may be accurately aligned above a selected fuel element 38. The tube A has projections 60 at its lower end which may pass between projections 50 on the upper end of the sleeve 40, the upper end of the tube being supported by a bearing 131 on a casing 130. The casing 130 is supported by a casing 110 in turn supported by a plate 107 acting through a thrust bearing 108, the plate being connected to a piston 106 actuated by a pressure medium supplied to cylinder ports 105. The tube B has projections 61 which may mate with the projections 50 and is rigid with casing 130. The tube C is slidable in tube B and biased downwardly by a spring 141 so that a key 142 on the tube C engages an abutment on the casing 130. The key 142 has a driving connection with a bush 136 rotatable in the casing 130, this bush being driven by a motor 140 through worm gearing 137, 138. The lower end of the tube C has projections 62 which may mate with projections 51 on the screw 44. The upper end of the tube D is connected to a piston 124 movable in a cylinder 121. The tool is controlled from a panel 143. In operation the tool is centred over the fuel element and the gaps between the projections 60 and 61 are aligned with the projections 50 by rotation of the tube A by a motor 135 and by conjoint rotation of the tubes A, B, C, D on the bearing 108 by a handle 144 secured to the casing 110; also, the tube C is rotated by the motor 140 to align the projections 62 with the gaps between projections 51. The piston 106 is lowered whereby the projections 60 move past the projections 50, the projections 61 mate with the projections 50 and the projections 62 mate with the projections 51, as shown in Fig. 1, the tube A then being rotated by the motor 135 so that the projections 60 lie directly beneath the projections 50. The tube D is moved down by the piston 124 to depress the pin 45 and remove the upward thrust acting on the sleeve 40, the screw 44 is slackened by rotating the tube C through motor 140 and the sleeve 40 is rotated by the tube B by means of the handle 144 to disengage the projections 42, 43 and permit removal of the full element 38 by the conveyer apparatus situated beneath the reactor. A new fuel element is inserted from beneath the reactor and the projections 42, 43 are engaged by appropriate operation of the tubes A...D, after which the tool is removed. A modified tool is described with reference to Fig. 4 (not shown) in which the centring of the tool above the fuel element is indicated by an air pressure gauge, the optical system being omitted. The air is supplied to an inner tube within the tube D and when this inner tube is aligned with the screw 44 the air flow stops and the gauge reads a maximum.