Patent GB-877423-A (GB)
Title: Improvements relating to fuel charging and discharging apparatus for a nuclear reactor
Inventor: BOYD WINNETT
IPC: G21C19/10
Filed: 1958-09-02
Abstract: 877,423. Nuclear reactors; handling nuclear fuel elements. BOYD Ltd., WINNETT. Sept. 1, 1959 [Sept. 2, 1958], No. 28180/58. Class 39(4). A gas-cooled reactor having horizontal fuel element channels 2 in its graphite core 1 has a spherical pressure vessel 3 surrounded by cooling and shielding water 6 within concrete shielding 5, the channels 2 being charged and discharged by apparatus contained in auxiliary pressure vessels which are permanently connected to the vessel 3 and subjected to the pressure therein whereby the fuel elements may be loaded and unloaded whilst the reactor is under load and without the necessity of making any gas-tight connections. The auxiliary pressure vessels comprise elevator shafts 15 which extend upwardly from a central position disposed at each end of the reactor and each of which contains tracks 14 for an elevator dolly 19 supported by chains 19a, the top end of each shaft having an enlarged head 18. A series of horizontal tracks 12 is disposed adjacent each load or unload face 13 of the core 1, the positions of the tracks corresponding to the channels 2, and each series of tracks serving to support a fuel element chargedischarge machine 11. The tracks 12 are interrupted at their central portions where they are intersected by the vertical tracks 14 and each dolly 19, Fig. 11, carries a pair of tracks 12a which are aligned with the tracks 12 to form bridging portions so that a machine 11 may be moved along selected tracks 12 to serve any channel 2 lying in the selected horizontal plane. When a machine 11 is positioned on the dolly tracks 12a it may be moved in a vertical direction to selected positions adjacent a face 13 or raised into a shaft 15. Cone shaped funnels 24 leading to pipes 25 permit removal of fuel elements accidentally dropped by a machine 11, these elements being collected in a flask 8 through valves 26. Each machine 11, Figs. 3, 5, comprises a magazine 28 having fuel element receiving holes 31 around its periphery and indexed by a pneumatic plunger operated roller (Fig. 4, not shown). The machine is driven along tracks 12 by wheels 37 rotated by pneumatic motors 35 through gear trains 36 and is steadied by further wheels 38. A plunger 32 driven by pneumatic motors 33 through a gear train 34 may be moved into any hole 31 to eject a fuel element. If, for example, a magazine 28 is to receive a spent fuel element, the plunger 32 of the machine 11 situated at the opposite end of the core is actuated to push all the fuel elements in that channel until the end fuel element of that channel is situated in a hole 31 of the receiving machine 11. The magazine of the receiving machine is then indexed to present an empty hole opposite its plunger 32 and the plunger is actuated to push back the protruding end of the next fuel element to its normal position 68 so that it does not extend beyond the core face 13. The position of the machines 11 is observable through telescoping periscopes 27, the machines carrying 45 degree mirrors 63 which reflect fuel channel numbers 60 (e.g. R-H 23) and indexing marks 61 on the core faces. When a machine 11 is raised through an isolating valve 16 (Fig. 7B, not shown) and a shielding gate 17 spent fuel elements may be removed therefrom by the plunger 32 which ejects them from the magazine 28 and discharges them into a pivoted dumper 48, Fig. 7A, the dumper then being rotated so that they slide down a shoot 98 through valves 55, 53 into a flask 52 containing trichlorethylene. The equipment includes a liquid expansion tank 54. In a modified equipment (Fig. 14, not shown) a welding station is interposed between the valves 55, 53 whereby the fuel elements are canned before entering the flask 52, and the latter may be gas or liquid filled. Fresh fuel elements are loaded into a magazine 28 by a pressurized glove box 45 (Fig. 8, not shown) having a plunger 92 which pushes a fuel element through valves 90, 91. Each dolly 19 is raised by a pair of chains 19a acting on a double sprocket 81 and two sprockets 42, the chains being driven by a worm gear-motor 73 housed in a head 44. A further worm gear-motor 80 causes the two sprockets 42 to rotate in opposite directions whereby the sprocket shaft 82 rotates the differential gearing 76, 77 to achieve this result being described with reference to Fig. 10 (not shown). Rotation of shaft 82 is transmitted to a concentric shaft 84, Fig. 11, when a key 83 forming part of the associated machine 11 is in place whereby bell cranks 85 integral with shaft 84 may be rotated to withdraw forks 86 from locking engagement with tracks 12. Thus a dolly 19 cannot be lifted by a motor 73 unless its machine 11 is positioned thereon. Further, when the key 83 is not horizontal it is locked in a housing 88 whereby the machine 11 cannot leave the dolly unless the forks 86 are in locking engagement. The compressed gas used for operating the several devices in the machines 11 is helium, this gas also serving as the reactor coolant, the gas being supplied to the machines without the use of rotating or sliding seals. Helium supply lines enter the heads 18 at 50 and then become rubber hoses bound together to form a flat belt 49 wound on a small pulley 51. These hoses are connected by passages and pipes 94 to a multiple metallic hose 22 wound on a large clockspring loaded sheave 41 coaxial and rotatable with the pulley 51. The hose 22 is terminated in a rocking block 40 on a machine 11, individual hoses 22a supplying the gas to the various devices on the machine.