Patent GB-912537-A (GB)
Title: Improvements in or relating to nuclear reactor refuelling machines
Inventor: JONES JACK
IPC: G21C19/20
Filed: 1959-11-26
Abstract: 912,537. Servicing reactors. UNITED KINGDOM ATOMIC ENERGY AUTHORITYNov. 24, 1960 [Nov. 26, 1959], No. 40173/59. Class 39 (4). A refuelling machine 50 for a steam-cooled reactor having a charge face 55 and movable over the face by a supporting carriage 51 having wheels 52, is characterized by an optical sighting member 126 movable transversely across the fuel element transfer path whereby the machine may be accurately aligned with a refuelling channel 56 leading to the reactor core. The member 126 when in its extended position, shown, enables the interior of the channel 56 to be viewed and after alignment of the machine it is moved to the withdrawn position to permit, the fuel element transfer operation to proceed. In greater detail the machine 50 comprises a pressure vessel 58 surrounded by shielding 84 and enclosing a fuel element magazine 59 having tubes 60. The magazine 59 is indexed by a steamoperated rack-and-pinion assembly 118 to align the tubes 60 with a telescopic shoot 57, this steam being admitted through a pipe 119. The machine is connectible with the channel 56 by the shoot 57 which has a part 92 rigid with the vessel 58 and a movable part 117, the part 117 comprising lower, intermediate and upper sections 64, 65, 66, interconnected by bellows 67, 68. The part 117 is movable within the part 92 by three actuating units 108 attached to a tubular structure 105 extending downwardly from a flange 95 of the shoot part 92. Each unit 108 comprises a piston 109 connected by a pin 112 to an arm 123 extending from the shoot section 64, the cylinder 110 having steam supply and exhaust pipes 114, 115. The part 117 is counter-balanced by weights 103 attached to ropes 99 extending over pulleys 101 supported by the flange 15, the other ends of the ropes being secured to a collar 97 on the shoot section 66. The vessel 58 also encloses a winch assembly 121 driven by a motor 122. Steam is supplied to the vessel 58 from a supply line 82 through a rotatable joint 83, the steam flowing through a pipe 106 and thence through a passage 162 to the interior of the vessel. Branches 164, 165 from the pipe 106 and shoot part 92, respectively, permit connection of the vessel 58 with a steam-cooling and re-circulating unit. A gate valve 89 in the shoot part 92 permits the vessel 58 to be isolated. The sighting member 126 is telescopically housed in a guide 128 and has a toothed rack 129 driven by a shaft 137 through gearing 135, 136 and a pinion (Fig. 6, not shown), coaxial with the gear 135. The shaft 137 is driven by a shaft 141 through gearing 139, the shaft 141 being connected to a motor 142 controlled from a cabin 87 mounted on the carriage 51. The member 126 houses prisms 144, 145 and lenses 146, 147 and has a cut-away portion 166 to expose the prisms to the channel 56. A right-angled tube 148 having one end connected to the guide 128 houses a prism 149, the tube extending upwardly to the cabin 87 where a right-angled extension 150 carries an eye-piece 151 incorporating cross-wires. In use, the machine 50 is moved to an approximate position above the channel 56 and a lamp 153 is switched on so that light rays 160 are directed by the prism 144 down the channel 56, the reflected rays 127 being directed by prisms 145, 149 to the eyepiece 151. The upper one, 77, of two sealing plugs 77, 78 in the channel 56 carries a target 134 and the machine is manoeuvred until the target coincides with the cross-wires. The member 126 is then withdrawn by the motor 142 and the pistons 109 are moved down by admitting steam to the pipes 114 so that a spigot 74 on shoot section 64 engages a recess 73 in the channel 56. A sealing sleeve 69 is moved downwardly by ambient pressure within the section 64 by connecting the space 71 to a condenser through a pipe line 72, the sleeve sealing with the channel 56. With the valve 89 open the vessel 58 and shoot 57 are pressurized to reactor pressure by admitting steam through the line 82 and a grab (not shown) associated with the winch 121 withdraws the plugs 77, 78 into empty tubes 60 of the magazine. An irradiated fuel element 81 is now withdrawn into another tube of the magazine and replaced by a new fuel element previously stored in a further tube. New plugs 77, 78 are inserted in the channel 56 and the valve 89 is closed. The irradiated fuel element is cooled by circulation of steam through the unit connected to branches 164, 165. In a modified optical sighting member (Fig. 1, not shown), steam acting on a piston is used to move the member transversely across the fuel element transfer path.