Control Rod Drive Mechanism

摘要

A control rod drive mechanism includes an outer tube and a guide tube which is arranged in the outer tube and is held by the outer tube. Furthermore, the control rod drive mechanism includes a spool piece with an inner magnet coupling and a rotary shaft connected to the inner magnet coupling arranged internally. The lower end portion of the outer tube is supported by the spool piece in the spool piece. The outside diameter of the outer tube, through the length of the outer tube, is smaller than the inside diameter of the spool piece and the outer tube, in the radial direction of the outer tube, is not projected outside the inner surface of the spool piece. Therefore, the installation places of the O-rings which are a seal member are reduced and the time required for maintenance of the control rod drive mechanism can be shortened.

主权项

1. A control rod drive mechanism including an outer tube, a guide tube disposed in said outer tube, a spool piece in which a lower end portion of said outer tube inserted, and supporting said outer tube and said guide tube, an inner magnet coupling disposed in said spool piece, a ball screw which is rotated by said inner magnet coupling and is disposed in said guide tube, a ball nut mating with said ball screw, a piston tube which is put on said ball nut and is connected to a control rod, a motor disposed below said spool piece and attached removably to said spool piece, and an outer magnet coupling which is disposed outside said spool piece, is connected to a rotary shaft of said motor, and is disposed opposite to said inner magnet coupling across said spool piece,
Wherein an outside diameter of said outer tube is smaller than an inside diameter of said spool piece through an entire length of said outer tube and said outer tube has a structure that it is not projected outside an inner surface of said spool piece in a radial direction of said outer tube.