Patent GB-1260681-A (GB)
Title: Nuclear reactor fuelling installation
IPC: G21C19/02
Filed: 1969-04-14
Abstract: 1,260,681. Fuelling reactors. ATOMIC ENERGY OF CANADA Ltd. 14 April, 1969 [15 April, 1968], No. 18962/69. Heading G6C. The description concerns the fuelling arrangement disclosed in Specification 1,260,682 and is particularly directed to (a) the construction of the ram head Q operating in ram barrel 121, (b) the construction of the plug R normally locked in the lower end of a reactor fuel channel D, and (c) the manner of removal of the plug R from the channel D by the ram head Q. Ram head Q.-This comprises, Fig. 4, an outer ram tube 126 which is prevented from rotating in the barrel 121 by a key 156 on the barrel engaging a channel 155 in the tube. The tube 126 is moved axially by rotating a sleeve 134 containing a set of re-circulating balls 136, these balls travelling in a helical channel defined by the co-operation of helical grooves 137, 128 formed respectively in the sleeve and tube. The sleeve 134 is driven by a motor 131 through gears 132, 133. Slidably mounted in the ram tube 126 is a latch tube 140, rotation between the tubes being prevented by a key and channel arrangement 159. The tube 140 is moved lengthwise relative to the tube 126 be a re-circulating ball drive unit 141 including a ball-retaining sleeve 145. The sleeve 145 is keyed for sliding movement to a shaft 146 driven by a motor 150. Thus rotation of the sleeve 145 causes axial movement of the tube 140 relative to the tube 126, and rotation of the sleeve 134 causes axial movement of the tube 126 relative to the ram barrel 121. The upper end 200 of the tube 126, Fig. 7, contains captive balls 204 and the upper end 207 of the tube 140 contains captive balls 208. A member 220 fixed by pins 218 to the tube 126 supports one end of a spring 221, the other end of the spring engaging a collar 215 on a rod 214 slidable in the tube end 207. In Fig. 7, in which the ram barrel 121 is not shown, the snout P of the fuelling machine is shown connected to the fuel channel D by means of locking bars 180 engaging behind a lip 181 on the channel and the ram head Q has been advanced through the snout so that a surface 203 on the tube 126 abuts an end surface 202 of the plug R. Plug R.-This comprises an outer cylindrical member 182 having captive balls 183 projecting into a groove 184 in the channel D to lock the plug in the channel against the high water pressure existing in the reactor. An inner plug member 185 slidable in the member 182 has a peripheral surface 186 normally holding the balls 183 in the locking position and a groove 187 for releasing the balls when the member 185 is moved upwards against springs 188. A rod 189 slidable in the plug member 185 has a surface 212 at its lower end abutting the end surface 213 of the rod 214 and has a disc 190 at its upper end bearing against a bar 192. The bar 192 is connected to a sleeve 198. Two upstanding posts 193 on the outer plug member 182 are connected at their top ends to a member 196 having a flexible conic lip 195 making a seal with the channel D. When the bar 192 and sleeve 198 are moved upwards relative to the post 193, the sleeve edge 197 engages the lip 195 and releases the seal. Plug removal.-The latch tube 140 is moved upwards relative to the ram tube 126 whereby the outer surface of the tube end 207 locks the balls 204 in a groove 205 in the plug member 182 and an inner surface 209 on the tube 126 locks the balls 208 in a groove 210 in a downward extension 211 of the plug member 185. The water pressure in the fuelling machine is raised to equal that in the reactor thereby enabling the spring 221 to release the seal 195 by lifting the parts 214, 189, 192, 198. The tube 140 is further advanced to lift the inner plug member 182 to bring the groove 187 opposite the balls 183 and thus unlock the plug from the fuel channel D. The plug R is now withdrawn by retracting the tube 126, the tube 140 moving in unison therewith.