| 摘要 |
1365519 Controlling reactors SIEMENS AG 29 Nov 1971 [30 Nov 1970] 55396/71 Heading G6C A control rod assembly comprises a tubular control rod formed with a coaxial internal screw thread and rotary driving means for engagement with the screw thread for bringing about longitudinal movement of the rod. As shown in Fig. 1, a tubular control rod 1 comprises a support tube covered with a layer 2 of neutron-absorbing material and formed with an internal screw thread 3. A cylindrical drive tube 6 is rotatably supported within a stub 4 on the reactor cover (not shown), and arranged coaxially around the stub 4 is the stator 8 of an electric motor, the rotor 9 of which extends within the stub 4 coaxially with the control rod 1 and is secured to the drive tube 6 through a flange 10. The rotor 9 is supported by antifriction bearings 11 against the upper end of a guide tube 5 extending down from the stub 4. The drive tube 6 is coupled to the control rod 1 through rollers 12, each formed with an external screw thread 13 engaging the internal screw thread 3 of the control rod 1. This engagement is effected by means of a coupling rod 21 guided within the drive tube 6 and drawn upwardly by the action of an electromagnet 25 on a disc 22 at the upper end of the rod 21 so that cams 28, 29 on the rod 21 act on transverse pins 30, 31 to press cylindrical segments 15, 16 bearing the rollers 12 on bolts 14 radially outwards against springs 18, 19 so that the rollers 12 engage with the screwthread 3. Depending on the direction of rotation of the drive tube 6, the control rod 1 is then raised or lowered. The control rod 1 is prevented from rotating by means of a roller (not shown) mounted on the rod and engaging a longitudinal groove 32 in the inner side of the guide tube 5. In order, in the event of withdrawl of the rollers 12 and the consequent rapid dropping-in of the control rod 1, to brake the control rod towards the end of its fall, the external diameter of the drive tube 6 increases downwardly at its lower portion 34. By this means a flow gap 35 between the upper end of the control rod 1 and the drive tube 6 for water flowing out of the control rod diminishes progressively, resulting in a shock absorber effect. |
