Abstract: The invention relates to a process for repairing at least one connecting area between a partition plate (8) and a tube plate (5) of a water chamber (7) of a heat exchanger (1), in which process the area of weld requiring repair is identified, at least one rail (11) is inserted into the water chamber, the said rail (11) is attached below the tube plate (5), a robot arm (20) is inserted, the robot arm is hoisted within the water chamber, the robot arm is remotely controlled, the connecting area requiring repair is machined and a check is made to ensure that cracks have been eliminated from the repaired area.

Abstract: The invention relates to a method for producing a thread in a bore (2) by remote automatic machining characterized in that the method consists in introducing into the bore (2) an electrode (11) provided with a thread (20) whose shape and dimensions are pre-determined according to the shape and dimensions of an inside thread to be produced, in machining the internal threads by electroerosion displacing the electrode (11) in an orbital manner in the bore (2) according to a predetermined number of operations and in adjusting the machining parameters according to each operation. A device for carrying out said method is also disclosed.

Abstract: The invention relates to a process for repairing at least one connecting area between a partition plate (8) and a tube plate (5) of a water chamber (7) of a heat exchanger (1), in which process the area of weld requiring repair is identified, at least one rail (11) is inserted into the water chamber, the said rail (11) is attached below the tube plate (5), a robot arm (20) is inserted, the robot arm is hoisted within the water chamber, the robot arm is remotely controlled, the connecting area requiring repair is machined and a check is made to ensure that cracks have been eliminated from the repaired area.

Abstract: The invention relates to a method for producing a thread in a bore (2) by remote automatic machining characterized in that said method consists in introducing into the bore (2) an electrode (11) provided with a thread (20) whose shape and dimensions are pre-determined according to the shape and dimensions of an inside thread to be produced, in machining the internal threads by electroerosion displacing the electrode (11) in an orbital manner in the bore (2) according to a predetermined number of operations and in adjusting the machining parameters according to each operation. A device for carrying out said method is also disclosed.

Abstract: After a nuclear reactor has been stopped and allowed to cool down following a period of operation, action is taken in a pool of the nuclear reactor on at least one guide tube of the activated upper internal equipment of the nuclear reactor to enlarge (21b, 21c) guide channels (16b, 16c) of the guide tube (8) in at least one continuous guidance zone. The enlargement is preferably performed by machining discontinuous cavities along the length of the guide channel (16b, 16c). Enlargement is preferably performed on the guide tube (8) in place within the upper internal equipment that has been placed on a storage stand in the reactor pool.

Abstract: After a nuclear reactor has been stopped and allowed to cool down following a period of operation, action is taken in a pool of the nuclear reactor on at least one guide tube of the activated upper internal equipment of the nuclear reactor to enlarge (21b, 21c) guide channels (16b, 16c) of the guide tube (8) in at least one continuous guidance zone. The enlargement is preferably performed by machining discontinuous cavities along the length of the guide channel (16b, 16c). Enlargement is preferably performed on the guide tube (8) in place within the upper internal equipment that has been placed on a storage stand in the reactor pool.

Abstract: An electrolyte is circulated between the surface to be machined, raised to an anode potential, and a tool electrode (9') raised to a cathode potential. The electrolyte contains lithium nitrate as a unique active product with a concentration of between 20 g/l and 2350 g/l and preferably between 50 g/l and 250 g/l. The process can be applied to the machining of the surface of any metallic component and in particular to the machining of the internal surface of tubular components (5) such as penetrations in the vessel bottom or closure head of a nuclear reactor; in this case the electrochemical machining cell consists of a cylindrical tool electrode (9') placed inside the component to be machined.

Abstract: A method and device for removal of a specimen (30), especially a parallelepipedal specimen, from within the internal wall of the vessel of a nuclear reactor which is at the end of its service and whose core has previously been dismantled, but which retains a high residual radioactivity. A rotating platform (10) carrying tools (23, 24) for cutting out by electrical discharge is inserted into the vessel (1), maintained under protective water (7). A first electrode produces a recess in a direction perpendicular to the internal wall (21) of the vessel, delimiting the external contour of the specimen, and a second electrode cuts the rear of the latter to a specified depth, before the withdrawal thereof from the wall. The specimen thus obtained is then extracted from the vessel.

Abstract: Process and device for the positioning of a tool (10) carried by a manipulating arm displaceable in three respectively perpendicular directions of space in relation to the vertical axis of a tube carried by the tube plate of a steam generator for a nuclear reactor. The process involves arranging symmetrically on the arm a set of at least three lighting sources (17) each supplying a light beam directed tangentially towards the periphery of a tube (5), retransmitting, via an optical assembly (18) also carried by the arm, the images of three specific points of the tube illuminated by the sources in the direction of a video monitor, the screen (21) of which comprises three reticles (42, 43, 44) delimiting the actual contour of the tube, and then bringing these images into coincidence with the reticles in order to center the axis (28) of the tools strictly on the axis (35) of the tube.

Abstract: The remote measurement device comprises a supporting structure (5) consisting of a plane annular base connected to the end of a handling pole of great length, and a movable measuring assembly carried by the base (5) and consisting of a stage (30) movable in all directions of the plane of the base coming to rest on the plate (3). The stage (30) is integral with a tubular sleeve (36) the axis of which is perpendicular to the plane of the stage (30), and the supporting structure (5) has a thrust assembly (18) abutting against the outer surface of the sleeve (36). A tracer (38) with a movable rod is mounted on the sleeve (36), with its rod (40) in a radial direction and pointed towards the interior of the sleeve (36). For measurement, the sleeve (36) is slipped onto the cylindrical element (4), and the thrust assembly (18) moves the sleeve (36) and the stage (30) forming the movable measuring assembly as a result of a radial thrust exerted on the sleeve (36) in a zone diametrically opposite the tracer (38).