| 摘要 |
1,251,174. Controlling reactors. ROYAL INDUSTRIES Inc. 18 May, 1970 [9 July, 1969], No. 23944/70. Heading G6C. A nuclear reactor control rod drive mechanism includes means for linearly positioning a control rod in a reactor core, and means responsive to a compressive loading of the control rod for preventing excessive loading of the control rod by the linearly positioning means. In one embodiment, a "part length" control rod, i.e. a control rod of which only a portion of its length contains poison, is connected to a lead screw 22 which is driven by an electric motor via a roller nut assembly 23. The loadlimiting action is effected by "floating" the motor rotor and allowing it to translate upwardly in response to a compressive overload. The rotor comprises two pivoted segments, segment 21-B of which is adapted to coact with a stop 50. The stop 50 has an abutment portion 50-S for engaging an abutment portion 21-S on the segment 21-B when this is caused to translate into rotational engagement with the portion 50-S. These two portions do not engage one another except when an outward load is transmitted to the rotor as a result of a compressive overload. Any stoppage of the control rod as a result of excessive friction, interference, a stuck rod or a rod bottom condition will cause the rotor to move along the lead screw 22 thereby removing all compression loading from the control rod, except as a result of gravity. A compression load on the control rod is transferred by the provision of the floating rotor from the control rod and/or lead screw 22 to the rotor segment 21-B. This causes the abutment portion 21-S to translate upwardly while rotating to the position shown in broken outline thereby engaging the abutment portion 50-S of the stop 50. With the interengagement of the portions 21-S and 50-S the rotor torque load is transferred from the lead screw to the external mechanism supporting members and the movement of the control rod ceases. |
