Remote maintenance device for thermonuclear reactor

The device of the present invention is inserted into a thermonuclear reactor from a maintenance port of a the reactor thereby enabling to exchange protection tiles on first walls rapidly and reliably. Namely, a visual sensor has projection portions for two intersecting slit lights, a reflected light pick-up portion and a calculating portion for processing picked-up images, to measure a central position and direction of a central axis of an objective hole. An exchanging hand comprises a gripper and a nut runner. A manipulator has a driving device having plural degrees of freedom. Then, tiles on the first walls of the thermonuclear reactor are exchanged automatically by a programmed remote control. The shape of the bit at the top end of the nut runner is made hexagonal so that it can rotate slowly when it is inserted to a hexagonal hole of a bolt having a hexagonal hole for use as a tile attaching bolt. (I.S.)