Patent GB-1007974-A (GB)
Title: Improvements relating to nuclear reactor servicing apparatus
Inventor: LONG EVERETT
IPC: G21C19/16
Filed: 1961-02-01
Abstract: 1,007,974. Servicing reactors. ENGLISH ELECTRIC CO. Ltd. Jan. 31, 1962 [Feb. 1, 1961], No. 3793/61. Heading G6C. Fue) element channels 25 of a reactor core 12 are serviced by a charge hub 15 rotatably supported by a bearing 18 carried by a shield plug 16, this plug being removably supported in the mouth of a standpipe 14 having an extension 21 passing through the pressure vessel 11, Figs. 1a, 1b, 1c. The end 22 of the extension 21 is flared outwardly and the shoot 15 has its longitudinal axis displaced from the standpipe axis and its lower end 17 cranked by the maximum amount permitting withdrawal of the shoot through the standpipe. The group of sixteen channels 25 serviced through the shoot are extended at their upper ends by a group of tubes 27 forming a guide tube assembly 24, this assembly being held together by plates 28, 29 and supported by brackets 23 from the standpipe extension 21. The upper ends of the tubes 27 lie on a pitch circle centred on the longitudinal axis of the shoot whereby the shoot end 17 may be aligned with any selected tube and the corresponding channel 25 refuelled by a machine (not shown), the machine first removing shoot plugs 19, 20. The shoot 15 is centred on the assembly 24 by a spigot 32 carried by a shoot extension 33 engaging a bush 31, the assembly 24 being aligned with the group of channels 25 by a pin 34. Gas sampling is permitted by a sampling annulus 41 attached to each tube 27, a pipe 40 extending from the annulus to a selector valve 42, this valve being actuated by pressure gas in a pipe 44 extending through a tube 45 to a solenoid 46. The solenoid controls the actuating gas. Group sampling and single sampling pipes 43 lead from the valve to a position outside the reactor. Thermocouples may be incorporated in the valve to allow continuous temperature indication either in the group or in the individual channels. In a modified arrangement, Figs. 2a, 2c, the plug 16 supports a control rod mechanism including a motor 60 driving a sprocket 54 controlling a chain 53 supporting a control rod 50 in a guide tube 51, the tube 51 being in alignment with a vertical tube 36 in the assembly 24. The chain is tensioned by a weight 57 supported by a pulley 56 suspended in a guide tube 55 by the chain. In a further modified arrangement, Figs. 3a, 3c, a string of five trailing lead thermo-couple fuel elements 70 are positioned in a guide tube 71 supported by the plug 16 prior to the insertion of the plug in the standpipe 14, these elements 70 being supported by their thermo-couple leads 72 which contain weak links and are connected to a chain 73 controlled by a sprocket 74 driven by a shaft 75. The fuelling machine lowers one or two new fuel elements into a channel 25 by means of the shoot 15 and is then removed to permit actuation of the shaft 75 to lower the string of elements 70 into that channel. To remove the elements 70 the fuelling machine lowers a weight on to the uppermost element and the shaft 75 is operated to raise the elements, the weight causing the leads 72 to break. The fuelling machine then removes the weight and discharges the channel in the normal manner. In another modification (Figs. 4, 8, not shown) the plug 16 carries a motor for lowering a flux scanning wire into the reactor. Specification 1,007,975 is referred to.