Sleeving of steam generators

摘要

A tool for inserting sleeve blanks in damaged steam-generator tubes of light weight capable of being manipulated by ROSA, a remotely operated service arm. ROSA permits the tool to be attached externally of the channel head of the steam generator. The tool includes a fixed gripper and a moveable gripper. The gripping member of each gripper is a flexible sheet or bladder which conforms readily to the surface being engaged. For insertion, the sleeve blank is mounted on a mandrel. The insertion is carried out by operating the grippers repeatedly through the following cycle until the sleeve blank is inserted into the damaged tube: (a) The moveable gripper is set in the lowermost position. (b) The fixed gripper is open. (c) The moveable gripper engages the sleeving assembly. (d) The moveable gripper raises the sleeving assembly to the uppermost position. (e) The sleeving assembly is engaged by the fixed gripper. (f) The moveable gripper is disengaged from the sleeving assembly. (g) The moveable gripper is returned to the lowermost position to start a succeeding cycle. For positioning, the tool includes a closed-circuit TV unit for centering the tool with reference to a tube other than the damaged tube and another closed-circuit TV unit for monitoring the insertion of the sleeve blank.