Patent GB-1425919-A (GB)
Title: Nuclear reactor fuelling machine
IPC: G21C19/19
Filed: 1972-10-02
Abstract: 1425919 Nuclear reactor refuelling machines UNITED KINGDOM ATOMIC ENERGY AUTHORITY 21 Sept 1973 [2 Oct 1972] 45433/72 Heading B8H A nuclear reactor refuelling machine by means of which a fuel assembly 141 or a control rod assembly (not shown) may be lifted from the reactor core, rotated through 180 degrees and deposited back in the core, comprises a gripper assembly 54 which is movable along the inner surface of a gripper guide tube 32 which is attached to a rotatable support structure, in the form of a main support tube (3), by means of a parallel linkage (33, 34), Fig. 1b (not shown). The gripper assembly 54 includes a pair of jaws 117 mounted for pivotal rotation towards and away from each other on a rotatable head 56 which is rotatable about a vertical axis relative to a carriage 55 of the gripper assembly 54, both the head 56 and carriage 55 having rollers 120, 121 and 59, 64 which run along the inner surface of the guide tube 32. The condition of the jaws 117 shown in Fig. 6 is that which they assume when in a fuel assembly engaging condition and when it is desired to pick-up and rotate the fuel assembly 141 the gripper assembly 54 comprising the carriage 55 and head 56 is lowered relative to the tube 32 such that the jaws 117 extend below the lower end of the guide tube 32 and the rollers 120 of the head 56 each enter a recess 145 formed on the inner surface of the guide tube 32 and the rollers 121 ride on a lower swell 144 of the said inner surface which causes the jaws 117 to be moved to and held in a retracted condition such that they can enter the lifting ring 146 of the fuel assembly 141. The main support tube (3) is now lowered by means of a shaft (26), Fig. 1a (not shown), so that the lower end of the guide tube 32 surrounds the upper end of the fuel assembly 141 and the gripper assembly is progressively retracted into the guide tube 32 such that the rollers 120, 121 move away from the recesses 145 and swell 144 respectively to engage the inner surface of the guide tube 32, causing the jaws 117 to engage the lifting ring 146. The fuel assembly 141 is then lifted into the guide tube 32 by raising the gripper assembly 54 relative to the tube 32. A ring gear 106 on the head 56 meshes with a spur gear 105 mounted on a rotatable shaft 95, rotation of the latter producing the desired rotation through 180 degrees of the head 56 and thus the jaws 117 and the fuel assembly 141. The main support tube (3) which supports the guide tube 32 is mounted within a rotatable housing (7) which is mounted on a rotating shield (1) above the reactor core, Fig. la (not shown). By rotation of the housing (7) by means of a pinion gear (18), the tube (3) rotates, and by radial extension of the guide tube 32 from the tube (3) by means of the linkage (33, 34), the guide tube 32 can be brought into alignment with any one of the fuel assemblies in the reactor core. The movement of the gripper assembly 54 relative to the guide tube 32 is effected by means of a tape 124 located in a side lug 93 of the gripper carriage 55, the tape 124 passing about rollers (134, 136) at the upper and lower ends respectively of the guide tube 32, Fig. lb (not shown), and passing to two mutually pretensioned drums (128, 129), Fig. 1a (not shown). Rotation of the shaft 95, to produce the rotation of the head 56, is effected by means of a shaft (110), Fig. 1a (not shown), the shafts 95 and (110) being interconnected by means of a telescopic shaft (115), Fig. 1b (not shown).