Abstract: A plugging apparatus for fixing a mechanical plug within a heat transfer tube of a heat exchanger includes a main body capable of being coupled to a tool guide robot movable under remote control inside a water chamber of the heat exchanger, a plug fixing mechanism mounted on the main body for conveying a mechanical plug from outside the heat exchanger and fixing the mechanical plug in the heat transfer tube, and a clamping mechanism for clamping the main body to a tube plate of the heat exchanger at a desired position on the tube plate of the heat exchanger. The invention makes it possible to fix a mechanical plug in a heat transfer tube of a steam generator or heat exchanger of a reactor in a remote-controlled and continuous manner.

Abstract: An improved laser beam welding apparatus for an inner circumferential surface of a tube is disclosed herein, which apparatus comprises an elongated flexible tube containing an optical fiber extended along the length thereof so as to transmit a laser beam, position detecting means disposed in the vicinity of the top end of the flexible tube to determine relative positioning thereof with respect to a work tube in which the flexible tube is inserted, holding means provided with an expander and disposed adjacent to the position detecting means for holding the tip end of the flexible tube in the work tube, rotary drive means disposed closer to the tip end of the flexible tube than the holding means, a rotary cylinder connected to the rotary drive means to be rotated with respect to the flexible tube, guide means mounted on the rotary cylinder in a relatively rotatable manner with respect to the rotary cylinder and held in contact with the inner surface of the work tube for supporting the rotary cylinder in a conce