CONTROL-ROD DRIVING PART HAVING MAGNETIC COUPLING DEVICE

摘要

PROBLEM TO BE SOLVED: To eliminate the need of a packing type sealing unit for preventing leakage from a reactor pressure vessel in the vicinity of a spindle. SOLUTION: The control rod drive section comprises a drive rotor 112 and a driven rotor 110 separated by a pressure barrier 124 forming a part of pressure boundary of reactor. The driven rotor is coupled magnetically with the drive rotor and rotates in response to the rotation of the drive rotor and thereby a control rod 40 is displaced in response to the operation of a drive motor. The driven rotor and drive rotor are constructed by stacking a plurality of circular magnetic rings each having a large number of poles distributed in the circumferential direction. A unit for preventing free rotation of a spindle at the time when the drive motor is removed in maintenance work is also provided. The unit comprises a push rod actuator 138 having one end penetrating the pressure barrier and touching the drive motor and the other end engaging a stopper 150 upon removal of the drive motor to block rotation of the spindle.