GB936451A - - Google Patents

Abstract

936,451. Handling nuclear fuel elements. BABCOCK & WILCOX Ltd. Feb. 3, 1960 [Feb. 6, 1959], No. 4341/59. Class 39 (4). A refuelling machine for a reactor comprises a pressure-vessel mounted on a carriage tha opening of the pressure vessel being approximately aligned with the selected reactor standpipe by movement of the carriage, exact alignment being obtained by a swinging movement of the pressure vessel about its support means on the carriage. As shown in Figs. 1, 2, the refuelling machine comprises a pressure vessel 1 supported in gimbal means 2 within a biological shielding housing 3, the housing 3 being mounted on a carriage 4 having wheels 13 running on tracks 5. The tracks 5 extend along a gantry 6 (one end being shown in Fig. 1) carried by bogies 7 running on tracks 11 on the reactor roof 8. The gimbal means 2 comprise a ring 25 surrounding the vessel 1 with clearance and having on its upper surface 26 at diametrically opposite positions a pair of rockers 34 formed with arcuate bosses 35. The rockers 34 cooperate with bearing-plates 33 carried at the lower ends of a pair of brackets 31 secured to the vessel 1. The lower surface 27 of the ring 25 has a pair of bearing plates 28 positioned on a diameter at right-angles to that of the rockers 34 and engaging rockers 29 supported by a shoulder 16 of the housing 3. The lower end 45 of the pressure vessel has an aperture 51 normally sealed by a plug 51A and leading to a sleeve 53 having a telescopic member 54 which may be extended, as shown, to sealingly engage at 54A with the selected standpipe 12 after the vessel has been rocked to ensure exact alignment. The swinging of the pressure vessel is controlled by two pairs of screw members 61 respectively arranged on the two diameters of the rockers 29, 34, the inner end of each member 61 engaging a flat surface 63 provided on the vessel. Thus radial movement of one pair of members 61 by the handles 62 to cause swinging of the vessel 1 about one horizontal axis is guided by the sliding action between the other pair of members 61 and their co-operating surfaces 63. The vessel 1 is filled with gas at a pressure equal to that in the reactor to enable refuelling to take with the reactor on load and contains a magazine 40 for receiving the fuel element assemblies. The magazine has four tubes 41 which may be selectively aligned with the aperture 51 by rotating the magazine shaft 42 by a motor 49 in an auxiliary pressure vessel 50. A motor 57 controls a hoist 55 having a rope 59 provided with automatic coupling and decoupling means 59<SP>1</SP> as disclosed in Specification 936,453 and enables the fuel element assemblies to be inserted in or removed from the tubes 41. Doors 24 in the housing 3 enable an operator to enter to remove a cap from the end of the standpipe 12 prior to the commencement of refuelling operation. A shield ring 18 of stepped crosssection attached to the housing 3 for vertical movement relative thereto is moved to its lower position, as shown, after the movement of the carriage 4. In a modified construction, Fig. 4, the vessel 1 is supported by four rods 71 suspended from the housing 3 by spherical washer assemblies 74 and carrying at their lower ends spherical washer assemblies 72 bearing against the undersurfaces of four brackets 70 secured to the vessel 1. The brackets 70 have flat surfaces 76 engaged by screw members 77 which are operated to exactly align the vessel 1 in a manner similar to the members 61 of Fig. 1. In Fig. 4 the members 61 (not shown), merely serve to clamp the vessel after it has been moved by the members 77.