Abstract: The control of the optical operation of a laser beam welding tool is carried out, when the tool is in an out of service position, by low-power auxiliary radiation. This radiation is passed to a measuring device (64) equipped with a photoelectric cell (86) after having traversed the tool as far as a welding head (58). The control can apply to an optical channel carried by a welding iron used for welding repair sleeves in pressurized water nuclear reactor steam generator tubes.

Abstract: The welding cane is equipped with a welding head (1) comprising an optical fiber (5) which emits a laser beam focused by an optical device (9) onto a wall (10) to be welded where a weld puddle (12) is formed. The welding head (1) comprises a photoelectric cell (45) illuminated by the scattered light around the end of the optical fiber. The signal emitted by the photoelectric cell (45) depends on the integrity of the optical fiber (5) and on the energy utilized for welding. It is used in the welding of a sealing sleeve in a pressurized water nuclear reactor steam generator tube.

Abstract: For laser welding in tubes of small diameter, protective gas is passed into the working zone by two currents originating from points situated on either side of this zone and converging towards it.

Abstract: The tubular casing (3) of the working head (1) exhibits two windows, upstream (4) and downstream (5), opposite each one of which there is mounted a deflecting mirror, a partially reflecting mirror (12) and a totally reflecting mirror (14) respectively. A first optical focusing device (8) is mounted in front of the upstream mirror, and a second optical focusing device (13) is mounted between the downstream mirror and the image focus (11) of the upstream optical device.Application to the simultaneous performance of a plurality of circular welds in tubes of small diameter.

Abstract: The head (1) for laser working in centered in the tube (2) by two open circular brushes. The laser working is performed under the protection of a primary gas emerging through the window (5) for passage of the laser beam and of a secondary gas circulating axially between the head and the tube (2). The invention is used in the socket fitting of the tubes of the steam generators of pressurized-water nuclear reactors.

Abstract: The frame (9), which is positioned in relation to the tubular element (T), comprises disengagable means (40) for driving the working rod (18) in rotation, and these means can co-operate with at least two regions (26 to 28) of the rod. It is thus possible to work in a plurality of different zones of the tubular element. Application to the sleeve coupling by laser welding of the steam generator tubes of pressurized-water nuclear reactors.

Abstract: The alignment apparatus is intended for repairing welds using infrared radiation and a weldhead (30) inside a heat exchanger tube (14) in the water box (20) of a steam generator associated with a nuclear reactor. A power beam (PE, PL, PS) is transported to the axis (24) of a tube (14) to be treated via two motor-driven light deflectors referred to as an "emitter" (11) fixed adjacent to an access hole into the water box, and as a "receiver" (12) carried by a "carrier" (22) at the entrance to the tube to be treated. The power beam is surrounded coaxially by a visible beam (AE, AL, AS) which is used for establishing and maintaining an optical connection between the emitter and the receiver by means of retroreflectors (15) and an autocollimation mirror (17) carried by the receiver (12) and by detectors (16, 18) carried by the emitter (11).

Abstract: During welding, the position of the mirror (37) reflecting the laser beam is controlled by a sensor (40) resting on the tubular element (M) to be welded.Application to the sleeve coupling of the tubes of steam generators of pressurized water nuclear reactors.

Abstract: A bush (M) is initially fixed inside a tube (T) which is fixed in a perforated plate (P) of a steam generator in a pressurized water nuclear power station, lining a damaged portion of the tube. A welding light beam is provided by a YAG laser and is conveyed by an optical fiber (F) to an optical cell (30, 37) which focuses the beam on the bush in order to weld it, the cell rotating about the fiber in order to form a circular weld fillet. The fiber is free to slide axially in order to improve focusing which is done by means of an adjustment beam provided by a helium-neon laser, the beam running along the fiber in both directions.

Abstract: A bush (M) is initially fixed inside a tube (T) which is fixed in a perforated plate (P) of a steam generator in a pressurized water nuclear power station, lining a damaged portion of the tube. A welding light beam is provided by a YAG laser and is conveyed by an optical fiber (F) to an optical cell (30, 37) which focuses the beam on the bush in order to weld it, the cell rotating about the fiber in order to form a circular weld fillet. The fiber is free to slide axially in order to improve focusing which is done to slide axially in order to improve focusing which is done by means of an adjustment beam provided by a hellium-neon laser, the beam running along the fiber in both directions.