Patent GB-1260685-A (GB)
Title: Nuclear reactor fuelling installation
IPC: G21C19/16
Filed: 1969-04-14
Abstract: 1,260,685. Fuelling reactors; fuel elements. ATOMIC ENERGY OF CANADA Ltd. 14 April, 1969 [15 April, 1968], No. 18966/69. Heading G6C. The Specification relates to the fuelling arrangement disclosed in Specification 1,260,682 in which the fuel channels D of a reactor each accommodate a fuel assembly comprising a fuel string V, Fig. 3b, detachably coupled at its lower end to a plug assembly, the plug assembly consisting of an upper shield plug S and a lower closure plug (Fig. 3a, not shown) which may be locked to the wall of the fuel channel. To refuel a channel D, the snout P of the head L, Fig. 2, of a fuelling machine is locked to the lower end of the channel. The head L includes a turret 102 rotatable on a bearing 101 whereby a ram barrel 121 or a fuel barrel 122 may be aligned with a passage 107 leading to the channel D. To remove a fuel assembly from a channel D, a ram Q is advanced through its barrel 121 and the passage 107 to lock on to the plug assembly and to release the plug assembly from its locking engagement with the channel wall. On retraction of the ram Q it withdraws the entire fuel assembly until the detachable coupling between the lower end of the fuel string V and the upper end of plug S is level with the end 270 of the barrel 121. A stop mechanism W, Fig. 4, on the head L is actuated to engage the fuel string V and support it in the passage 107 against further longitudinal movement. The turret 102 is now rotated to align a fuel barrel 122 with the passage 107 and this rotation automatically disengages the coupling between the fuel string V and the plug S. Coupling construction.-The lower end of the fuel string V, Figs. 3b, 5, comprises a plate 240 rotatably supported by a bolt 254 on a member 253 connected to a casing 252. The upper end of the casing is abutted by a spring 251, the lower end of the spring acting on a tube 247 through a member 250. The tube 247 extends through the string V and abuts a surface (not shown) at the top end of the string whereby the several fuel bundles 243 of the string are maintained together under compression. A depending projection 303 on the plate 240 has a T-section slot 242 formed therein, this slot cooperating with a T-shaped pin 239 formed on the plug S. Thus, providing the cross-arm of the T is parallel to a radius of the turret 102, rotation of the latter will cause the pin 239 to leave the slot 242. The correct alignment of the slot 242 is obtained by a mechanism X, Fig. 4, mounted on the head L. As the fuel barrel 122 comes into alignment with the passage 107 a pin 162, similar in shape to the pin 239, situated on the end of a piston 160 in the barrel, enters the slot 242, whereby, after releasing the stop mechanism W, the piston may withdraw the fuel string V into the barrel. Mechanisms W, X.-Stop mechanism W comprises two detents 280, 281 mounted on a pin 282 and pivoted in opposite directions by a sliding yoke 283 connected to the detents by links 284. The yoke 283 is connected by a rod 285, coupling 310 and rod 308 to a piston 286 operated by oil introduced under pressure to passages 288, 289. When the yoke 283 is moved to the left, as shown, the detents 280, 281 engage an annular projection 293 on the member 253 of the fuel string V. Alignment mechanism X comprises a slide 300 driven by a piston 301 through a coupling 311 and rod 309. The piston 301 is controlled by oil admitted to passages 306, 307. When the slide 300 is advanced, as shown, it engages the cam surface formed by the side of the projection 303 to rotate the latter and correctly orientate the slot 242. The coupling 311 also serves to operate limit switches 515, 516.