CONTROL ROD DRIVE MECHANISM AND LUBRICANT INJECTION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a control rod drive mechanism for improving transfer efficiency of a ball screw shaft within an underwater environment.SOLUTION: A control rod drive mechanism comprises: a ball screw shaft 5; a ball nut 6 arranged in a periphery of the ball screw shaft; a plurality of balls 51 arranged in a ball rolling passage 50 formed by a ball screw groove 5a of the ball screw shaft 5 and a ball screw groove 6a of the ball nut 6; a ball return passage 52 for returning the balls 51 rolling in the ball rolling passage 50 to an initial position; and a hollow piston attached to the ball nut 6 and connected to a control rod. The ball screw shaft 5 and the ball nut 6 are arranged within an underwater environment immersed in cooling water inside a reactor pressure vessel, and a lubricant supply hole 60 capable of supplying a lubricant to the ball rolling passage 50 is formed in the ball screw shaft 5 or the ball nut 6.