APPARATUS FOR EXECUTING MAINTENANCE WORK ON THE WALL OF VACUUM VESSEL

Abstract: Apparatus for executing maintenance work on the inner wall of a vacuum vessel 4, comprising a tubular stucture 2 connected to the vessel, an arm 8a in the tubular structure, an arm end 8 movable elevationally in a Z-axis direction and rotatable in a X-Y plane with the Z-axis as a centre in a manner projected in a direction perpendicular to the Z-axis, in X-Y-Z orthogonal coordinates having the axis of the tubular structure as a Z-axis, a movable block 23 capable of freely moving in the lengthwise direction of and mounted on the arm end, a titanium deposition source 9 mounted in the block to thereby fuse and diffuse the titanium at an arbitrary coodinate position of the X-Y-Z coordinates in a predeter­ mined range in the vacuum vessel, and an image guide sensor 12 mounted at the arm end to observe the state in the vacuum vessel.

Description: APPARATUS FOR EXECUTING MAINTENANCE WORK ON THE WALL OF VACUUM VESSEL BACKGROUND OF THE INVENTION The present invention relates to an apparatus for executing maintenance work or the inner wall of a vacuum vessel such as in a vacuum vessel of a nuclear fusion reactor. A titanium coating is formed on the inner wall of a vacuum vessel of this type. In the conventional mainteance work of the inner wall of the vacuum vessel, a defective portion of the titanium coating is repared by applying a high voltage large current to a titanium ball held at a predetermined position in the vaccum vessel to melt and diffuse the ball. The titanium ball is mounted at the end of a shaft-shaped structure. In order to maintain the vacuum vessel in a vacuum, the outside of the shaft-shaped structure is surrounded by a tubular guide, which is connected to a predetermined portion of the vessel, the shaft-shaped structure is hung in the tubular guide by a drive mechanism provided at the top of the tubular guide to be elevationally driven upwards and ddwnwards in the state that the interior of the structure in which the tubular guide is connected to the vessel is maintained in a vacuum. When the titanium coating is formed at this time, the titanium ball mounted at the end of the shaft-shaped structure is moved down to a predetermined position in the vessel. After the titanium coating is finished, the shaft-shaped structure and the titanium ball are again contained in the tubular guide. A high voltage lead assembly for energizing the titanium ball is connected to the ball, but the outside of the lead assembly for electrically insulating the lead assembly from the shaft-shaped structure is covered with an inorganic insulator. The conventional apparatus is constructed as described above, the titanium ball can be fused and diffused only at one predetermined position in the vacuum vessel, but it cannot locally form a titanium coating selected for only a necessary portion to repair the coating in the vessel. Further, the apparatus does not have means for observing the state in the vacuum vessel. Therefore, it has such disadvantages that the titanium ball is consumed unnecessarily, the working time for forming the coating is long, and it is necessary to replace the titanium ball many times, thereby resulting in poor economy as well as making it difficult to determine the state of the coating after forming the coating. SUMMARY OF THE INVENTION The present invention was accomplished in order to eliminate the above-mentioned defects inherent in the conventional art, and has for its object to provide an apparatus for executing maintenance work on the inner wall of a vacuum vessel which is provided with an arm end movable elevationally in a Z-axis direction and rotatable in a X-Y plane with the Z-axis as a center in a manner projected in a direction perpendicular to the Z-axis by presuming an X-Y-X orthogonal coordinates having an axial center direction of a tubular structure connected to a vacuum vessel as a Z-axis, a movable block capable of freely moving in the lengthwise direction and mounted on the arm end, a titanium deposition source mounted in the block to thereby fuse and diffuse the titanium deposition source at an arbitrary coordinate position of the X-Y-Z coordinates in a predetermined range in the vacuum vessel and to observe the state in the vacuum vesel via an image guide sensor mounted at the arm end. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an explanatory view showing an embodiment of an apparatus for executing maintenance work of the inner wall of a vacuum vessel according to the present invention; Fig. 2 is an explanatory view showing a principle of an image guide of Fig 1; Fig. 3 is an explanatory view showing the detail of the vicinity of the end of an arm of Fig. 1; Fig. 4 is an explanatory view showing the construction of the interior of a winding mechanism of Fig. 1; Fig. 5 is a partial sectional elevational view of a trunk support; and Fig. 6 is a partial sectional elevational view showing the construction of a titanium deposition preventing mechanism and a titanium deposition amount monitoring plate. In the drawings, the same symbols indicate the same or corresponding parts. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is an explanatory view showing an embodiment of the present invention. In Fig. 1, numeral 1 designates a drive unit, numeral 2 a tubular structure, numeral 3 a gate valve, numeral 4 a vacuum vessel, and numeral 5 a port which forms part of the vessel 4. The vessel 4 and the port 5 communicate with or shut off the inner atmosphere of the structure 2 by opening or closing the gate valve 3. Numeral 6 denotes an arm body, numeral 7 an arm rotary unit, numeral 8 an arm end, numeral 8a a drive wire, numeral 9 a titanium deposition source, numeral 10 a high voltage lead assembly, numeral 11 high voltage lead supporting rings, numeral 12 an image guide sensor, numeral 12a an image guide, numeral 13 a vacuum pump unit, numeral 14 an operation board, numeral 15 a winding mechanism box, numeral 16 a winding drum, numeral 17 an optical connector, numeral 18 a television camera, and numeral 19 a monitor television receiver. Fig. 2 is an explanatory view showing a principle of the image guide 12a. Numeral 12 indicates an image guide sensor similar to that in Fig. 1, numeral 20 an image guide receiver, numeral 21 an image, and numeral 22 an object. Fig. 3 is an explanatory view showing the detail of the vicinity of the arm end 8 of Fig. 1, wherein the corresponding parts are denoted by the same symbols as those shown in Fig. 1, numeral 23 indicates a movable block, numeral 24 a cam follower, and numeral 25 a light guide. The image guide 12a comprises, for example, several ten thousands of ultrafine optical fibers of quarts, one end of which constructs the image guide sensor 12, a light incident to the ends of the respective optical fibers of the image guide sensor 12 is transmitted through the image guide 12a, received through the optical connector 17 by the television camera 18, and displayed on the monitor television receiver 19, The drive unit 1 elevationally drives upwards and downwards the arm body 6 in the tubular structure 2 and the port 5, converts an angle between the state that the coaxial center of the arm end 8 conincides with the Z-axis (not shown) and the state that the coaxial center of the arm end 8 is disposed in X-Y plane (the state shown in Fig. 1), rotates the arm end 8 through the arm rotary unit 6 around the Z-axis to wind the drive wire 8a through the cam follower 24, thereby varying the position in the arm end 8 of the titanium deposition source 9 mounted in the movable block 23. When the position of the block 23 varies, the high voltage lead supporting rings 11 for supporting leads at a plurality of positions are provided along the portion of the high voltage lead assembly 10 along the arm end 8 so as to readily elongate and contract while maintaining the insulation of the lead assembly 10. The tubular structure 2 is connected to the port 5, the drive unit 1 is controlled from the operation board 14 to set the movable block 23 to a predetermined position, the vacuum pump unit 13 is controlled from the operation board 14 to evacuate the vacuum vessel 4 in a vacuum atmosphere, and a current is flowed to the titanium deposition source 9 to fuse and fiffuse the titanium deposition source 9. Further, the entire zone in the vacuum vessel 4 can be monitored by the image guide sensor 12 fastened to the arm end 8. A light guide 25 applied the optical fibers in the same manner as the image guide 12a to transmit a light from a light source, thereby illuminating th interior of the vessel 4, When the object 22 is introduced in the vacuum vessel 4, the image thereof is introduced into the image guide sensor 12 and is transmitted through the image guide 12a to the image guide receiver 20, where it is converted via the television camera 18 into an elecyric signal and displayed as an image on, the monitor television receiver 19. As described above, the local titanium coating can be repaired and the states in the vacuum vessel before and after the repair can be observed. Fig. 4 is an explanatory view showing the internal construction of the winding mechanism box 15 shown in Fig. 1. In Fig. 4, the corresponding parts are denoted by the same symbols as those shown in Fig. 1. Referring to the Fig., numeral 26 designates a drum shaft of the winding drum 16, numeral 27 bearings of the drum shaft 26, numeral 28 shaft seals, numerals 29, 30 reduction gears, numeral 31 a motor for driving the drum shaft 26, and numeral 32 a wire penetrating unit. The interior of the winding mechanism box 15 is airtighly sealed from the outer stmosphere through a connecting mechanism of the shaft seals 28, the wire penetrating unit 32 and the optical connector 17, and connected to the tubular structure 2 to pass the high voltage lead assembly 10 and the image guide 12a. When the arm body 6 is moved by the drive unit 1 in the Z-axis direction, the high voltage lead assembly 10 and the image guide 12 provided along the arm end 8 from the arm body 6 are slackened or tensed. Therefore, the drum shaft 26 is rotated in accordance with the rise or fall of the arm body 6 to wind or rewind the lead assembly 10 and the image guide 12 on the winding drum 16. The driving characteristic of the arm driving system is improved by providing such a winding mechanism to prevent the lead assembly 10 and the image guide 12a from deteriorating. Fig. 5 is a sectional view of an embodiment in which a trunk support is provided in the port 5 of the invention. In Fig. 5, the corresponding parts are denoted by the same symbols as those shown in Fig. 1. Referring to the Fig., numeral 33 denotes guide rollers, numeral 34 springs, numeral 35 fasteners, numeral 36 fulcra of the fasteners 35, and numeral 37 trunk support driving wires. A trunk support 8b has a cylindrical structure, the guide rollers 33 provided on the outer peripheral surface of the support 8b are always contacted with the inner surface of the port 5 by the springs 34, and the support 8b is driven by the drive unit 1 through the trunk support driving wire 37 in the Z-axis direction. The trunk support 8b is perforated axially (i.e., in the Z-axis direction) with penetrating holes, through which the arm body 6, the high voltage lead assembly 10 and the image guide 12a are respectively slidably penetrated, When the lead assembly 10 and the image guide 12a are wound by the winding drum 16, the fasteners 35 are operated by the drive wire 8a to move the lead assembly 10 and the image guide 12a in the X-Y plane at the position of the trunk support 8b to fasten the trunk support 8b at a predetermined position in the port 5. When the lead assembly 10 and the image guide 12a are fastened at a predetermined position in the X-Y plane in the axial length of the trunk support 8b, the lead assembly 10 and the image guide 12a can be readily wound on the drum 16. Fig. 6 is a partial sectional elevational view showing an embodiment in which a titanium deposition preventing mechanism is provided on the light transmitting surfaces of the image guide sensor and the light guide radiating end, and a titanium deposition amount monitoring plate is provided at the arm end of the invention. In Fig. 6, numeral 38 indicates a screen, i.e., the surfaces of the image guide sensor 12 and the light guide radiating end 25 for transmitting a light, numeral 39 cylindrical bellows, numeral 39a a stationary flange provided at one end of the bellows 39, numeral 39b a movable flange provided at the other end of the bellows 39, numeral 40 a wire for a titanium deposition preventing mechanism, numeral 41 a cam follower, and numeral 42 a titanium mounting monitor supporting trestle. When the inner wall of the vacuum vessel 4 is observed, a tension is applied to the wire 40 to draw the movable flange 39b toward the stationary flange 30a so as to shorten the bellows 39, thereby disposing the screen 38 at the position so as not to disturb the light to be introduced to the screen 38. Thus, the tension of the wire 40 is loosened while a current is flowed to the titanium deposition source 9 to fuse the titanium to thereby perform the depositing work, the bellows 39 are elongated, the flange 39b is returned to the position shown in Fig. 6 to prevent the titanium from depositing on the screen 38. Since it is difficult to actually measure the amount of the titanium deposited on the inner wall of the vacuum vessel 4, two monitoring plates 25b are, for example, mounted on the supporting trestle 42, whereby the titanium deposition amount to the inner wall of the vessel 4 is presumed to be equal to the quantity of the titanium deposited on the monitoring plates 25b. In the above description, the trunk support driving wire 37, the fasteners 35 and the titanium deposition preventing mechanism wire 40 in Fig. 5 are driven by the drive unit 1. In the embodiments described above, the present invention has been described with respect to the case applied to the nuclear fusion reactor. However, the apparatus of the present invention can be applied also to a light-water type nuclear reactor and a fast breeder. As set forth above, according to the present invention, since the apparatus is constructed so that the titanium deposition source can be fused and diffused at the arbitrary position in a predetermined range in a vacuum vessel and the function of observing the interior of the vessel is provided, the maintenance work of the inner wall of the vessel can be efficiently performed and the technical reliability can be improved.

Claims: CLAIMS: 1. An apparatus for executing maintenance work on the inner wall of a vacuum vessel, comprising: a tubular structure (2) connected to a port (5) of the vacuum vessel (4), a rod element (6) mounted movably in the tubular structure. and drive means (1) for moving the rod element, characterised in that the rod element comprises a rod-shaped arm body (6) elevationally movable in a Z-axis direction in said tubular structure (2) (in a system of X-Y-Z orthogonal coordinates having the axial centre of said structure as the Z-axis), a rod-shaped arm end (8) extending from the lower end of said arm body and constructed to vary in the extending direction thereof with respect to the axial direction of said arm body. an arm rotary unit (7) for rotating said arm end in the Z-axis as a centre, a movable block (23) capable of moving along the lengthwise direction of said arm end, for holding a titanium deposition source, a high voltage lead assembly (8a) arranged through said structure to said titanium deposition source to supply current to said titanium deposition source, a drive unit (1) for driving the elevational movements of said arm body (6) in the Z-axis direction, the alteration of the angle between the lengthwise direction of said arm end (8) and the lengthwise direction of said arm body (6), the rotation of said arm end (8) around the Z-axis as a centre through said arm rotary unit. and the movement of said movable block (23) along the arm end, an image guide sensor (12) mounted at said arm end for viewing the inner wall of said vacuum vessel, and an image guide (12a) provided to transmit light incident on said image guide sensor to a predetermined position of said structure. 2. Apparatus as claimed in claim 1, characterised by the provision of an optical connector (17) for optically coupling said image guide at the predetermined position of said tubular structure. 3. An apparatus for executing maintenance work on the inner wall of a vacuum vessel as defined in claim 2, characterised in that a winding mechanism (16) for winding or rewinding said high voltage lead assembly (10) and said image guide (12a) upon movement of said arm body (6) in the Z-axis direction is provided between said tubular structure (2) and said optical connector (17), and a winding mechanism box (15) connected to said structure and having a structure airtightly sealed from outer atmosphere is provided. 4. An apparatus for executing maintenance work on the inner wall of a vacuum vessel as defined in claim 1, 2 or 3, characterised in that a trunk support (8b) constructed to move in the Z-axis direction in the port (5) and to stop at an arbitrary position in the Z-axis direction and having penetrating holes, through which said arm body (6), said high voltage lead assembly (10) and said image guide (12a) respectively slidably penetrate. is provided in said structure. 5. An apparatus for executing maintenance work on the innr wall of a vacuum vessel as defined in claim 1, 2, 3 or 4, characterised in that a titanium deposition preventing mechanism is provided for shielding the light transmitting surfaces of said image guide sensor (12) and of a light guide radiating end (25) during the fusing and diffusing operations of titanium. 6. An apparatus as claimed in claim 4 in which the depositions preventing mechanism comprises a cylindrical bellows (39) arranged to prevent the titanium from depositing on the light transmitting surfaces of said image guide sensor and said light guide radiating end, and means for opening and closing the bellows to cover or expose the light transmitting surfaces of said image guide sensor and said light guide radiating end. 7. An apparatus for executing maintenance work on the inner wall of a vacuum vessel as defined in any preceding claim characterised in that a titanium deposition amount monitoring plate (256) for determining the amount of titanium deposited on the inner wall of said vacuum vessel is provided at said arm end. 8. Apparatus as claimed in any preceding claim characterised in that a gate valve (3) is provided for opening and closing gas communication between the vessel (4) and the tubular structure (2), and a vacuum pump (13) is provided for evacuating the vessel when the vessel is connected to the tubular structure. 9. Apparatus as claimed in any preceding claim characterised in that a plurality of high voltage lead supporting rings (11) are provided for holding a plurality of portions of said high voltage lead assembly (10) along said arm end and sliding on said arm and when said movable block moves along the said arm end.

Inventors: KOJIRO, TETSUYA
Applicants: MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1985
Main classification: G02B23
IPC codes: G02B23