JP2010125482A - Maintenance apparatus and method of welded joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a maintenance apparatus and method of welded joints, by which the welded joints of a plurality of nozzles installed in a pressure container can be maintained in a short period. <P>SOLUTION: In a maintenance apparatus 6 of welded joints 5 for which cladding by welding is performed on the inner face of the welded joints 5 formed between nozzles 3 and piping 4 installed in plurality in the pressure container 1 of a nuclear reactor; there is arranged, in the upper part of the pressure container 1, a structure 7 that is rotatable around the center axis of the pressure container 1. The structure 7 is hangingly provided with a pair of base parts 9, 10 that are arranged vertically apart inside the pressure container 1. In these base parts 9, 10, nozzle plug devices 13, 14 are installed in-between movably in the radial direction through rail members 11, 12 and in a manner to be situated between the base parts 9, 10, wherein the nozzle plug devices 13, 14 are inserted in the nozzles 3 for grooving and for cladding-by-welding on the inner face of the welded joints 5. With one nozzle plug device 13 situated in the center part of the pressure container 1, for the purpose of retreating the other nozzle plug device 14 to the outer periphery of the pressure container 1, the other rail member 12 is installed movably in a direction crossing the moving direction of the one nozzle plug device 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a weld joint maintenance device and maintenance method for maintaining a weld joint formed between a nozzle provided in a pressure vessel of a nuclear reactor and a pipe connected to the nozzle.

  Primary water stress corrosion cracking (PWSCC) occurs in a dissimilar weld joint of a pressurized water reactor (PWR) in an environment of primary cooling water. Thereby, the maintenance treatment is applied to the weld joint portion of the dissimilar material in the similar environment, for example, the weld joint portion of the nozzle provided in the pressure vessel (RV).

As a maintenance method of the welded joint,
(a) Mechanical stress improvement process (MSIP) that suppresses the occurrence of PWSCC by mechanically applying compressive stress to the outer surface of the welded joint,
(b) High-frequency induction heating stress improvement (IHSI: Induction Heating Stress. Improvement) that thermally applies compressive stress to the surface of the welded joint.
(c) Weld overlay (SWOL: Structural Weld Overlay) is generally adopted to build up the weld wall from the outer surface of the pipe with weld metal to ensure the required thickness of the pipe.

  However, the welded joint part between the nozzle and the pipe is in the vicinity of the concrete wall penetrating part, and the space that can be used for maintenance work is limited, and the accessibility to the welded joint part is poor. There are places where it is difficult to apply (a), (b) and (c).

  In such difficult locations, the welded joint part is accessed from the inner surface of the pipe, the inner surface of the welded joint part is made as necessary, and a groove is formed. The maintenance method (d) that improves the PWSCC resistance of the part is adopted. In particular, since this maintenance method (d) accesses the welded joint from the inside of the pressure vessel, it must be constructed with the top cover open during the periodic inspection period when the reactor is shut down. It becomes. For this reason, complete remote construction, construction that isolates workers from the radiation source as much as possible, or construction under a sufficient radiation shielding environment is required. In addition, as the periodical inspection period is being shortened recently, it is required to select applicable technologies and manage the construction so that there are no backhauls caused by the periodic inspection work, such as the occurrence of welding defects. Yes.

  Also, in this maintenance method (d), a method is adopted in which workers access the vicinity of the construction target site across the shielding body, which means that the work is under a high dose and that large devices such as shielding bodies are stored. There are problems such as carrying in the vessel and installing it on the reactor vessel. In repair welding, the occurrence of welding defects due to the chemical composition of the base material of the dissimilar weld joint has been reported. In particular, in a dissimilar material welded joint of a combination of stainless steel and a nickel-base alloy or the like, when a dissimilar material welded joint is directly deposited with a weld metal of Alloy 52/152, a weld crack such as a high temperature crack occurs. As a method for preventing this weld cracking, a high sulfur mitigation layer, which is a special process different from the remaining layer (other than the first layer), in which only the first layer is made of Alloy 82/182 or ER309L weld metal, is employed. Moreover, in large diameter piping, the improvement of welding efficiency is calculated | required from a viewpoint of shortening the period of periodic inspection days.

  Moreover, the thing of patent document 1 is known as a maintenance apparatus which maintains the location where construction is difficult as mentioned above.

  As shown in FIG. 12, the maintenance device 60 is used in a state where the pressure vessel 2 is filled with reactor water, and is inserted into the nozzle 3 and is welded to the inner surface of the welded joint portion 5. A nozzle plug device 61 is provided.

  As shown in FIG. 13, the nozzle plug device 61 includes a first seal member 62 that closes the pipe 4 connected to the nozzle 3 and a second seal member 63 that closes the nozzle 3, and the first seal member 62. The second seal member 63 divides the work area A at the connection portion between the pipe 4 and the nozzle 3. When maintaining the welded joint using the nozzle plug device 61, the reactor water in the work area A is discharged and air is supplied into the work area A to form a gas atmosphere. The repair / maintenance device 64 is used to perform predetermined repair / maintenance in a gas atmosphere. Further, as shown in FIG. 12, the nozzle plug device 61 is installed on a beam-structured structure 65 via a linear motion (linear motion) guide rail (not shown). The structure 65 is suspended by a crane or the like and is lowered into the pressure vessel 2. The nozzle plug device 61 is introduced into the pressure vessel 2 in a state where it is mounted on the structure 65, moves along the linear motion guide rail, and is inserted into the nozzle 3. According to the maintenance device 60, maintenance work can be performed safely by remote operation, and high-quality welding can be performed.

International Publication No. 2007/116532 Pamphlet JP-A-7-12978 Japanese Patent No. 3918217 JP-A-1-83378 JP-A-10-258364 JP 61-38780 A JP-A-9-85440 JP 2000-312969 A

  By the way, the nozzle plug device has a third seal member for closing the nozzle from the inside of the pressure vessel in addition to the first seal member and the second seal member described above, and guarantees the sealability of the work area with these three seal members. It has a structure to do. For this reason, the nozzle plug device has a structure longer than the distance from the inner wall surface of the pressure vessel to the weld joint, and the length thereof is larger than the radius in the pressure vessel. In addition, the nozzle plug device is inserted along the linear guide rail as described above, and only one nozzle plug device is installed in the pressure vessel from the viewpoint of the relative space between the furnace inner diameter and the entire length of the device. And repaired and maintained one nozzle at a time. From this, when considering the construction time for each nozzle and the time for moving the nozzle plug device to another nozzle sequentially, there is a problem that it takes a long time to complete repair and maintenance of all the nozzles.

  On the other hand, the period for carrying out periodic inspections, including nozzle repair and maintenance work, is required to be shortened from the viewpoint of improving the facility operation rate. However, when this technology is applied, the repair and maintenance work described above is required. Due to this, it was necessary to extend the regular inspection period from the usual, and it was difficult to shorten the periodic inspection period.

  Then, the objective of this invention is providing the maintenance apparatus and maintenance method of the welded joint part which can maintain the said subject and can maintain the welded joint part of the some nozzle provided in a pressure vessel in a short period of time.

  In order to solve the above problems, the present invention is formed between a plurality of nozzles provided along a circumferential direction on a cylindrical side wall of a reactor pressure vessel and a pipe connected to the nozzle by welding. In a maintenance device for welded joints that performs overlay welding on the inner surface of the welded joint to maintain the welded joints, a structure that is rotatable about the central axis of the pressure vessel is disposed above the pressure vessel, and the structure A pair of bases, which are spaced apart from each other in the pressure vessel in the body, are suspended via suspension members, and these bases are inserted into the nozzle and grooved on the inner surface of the weld joint. When the nozzle plug device for overlay welding is provided so as to be movable in the radial direction via the rail member and positioned between the base portions, and one nozzle plug device is located at the center of the pressure vessel The other nozzle plug device is a pressure vessel As it is retracted in the outer peripheral portion, in which the rail member for supporting the other nozzle plug device is movable in a direction intersecting the moving direction of one of the nozzle plug device to the base.

  The base portion that supports the other nozzle plug device via the rail member may include a traverse rail that obliquely guides the rail member that supports the other nozzle plug device with respect to the moving direction of the one nozzle plug device.

  The structure may be provided at the upper end of the side wall of the pressure vessel so as to be rotatable around the central axis of the pressure vessel.

  The suspension member may be a jack.

  It is preferable that a plurality of stoppers in contact with the side walls of the pressure vessel are provided on the base portion so as to extend radially outward and in the circumferential direction so as to fix the base portion.

  Also, a welded joint is provided to maintain a welded joint formed between a plurality of nozzles provided along the circumferential direction on the cylindrical side wall of the reactor pressure vessel and a pipe connected to the nozzle by welding. In the maintenance device for a welded joint portion that performs overlay welding on the inner surface of the portion, a structure that can rotate around the central axis of the pressure vessel is disposed above the pressure vessel, and the structure is vertically moved into the pressure vessel. A nozzle that suspends a pair of spaced-apart bases through suspension members, inserts the bases into the nozzle, processes the groove on the inner surface of the weld joint, and performs overlay welding The plug device is provided so as to be movable in the radial direction via the rail member and positioned between the base portions. When one nozzle plug device is at the center of the pressure vessel, the other nozzle plug device is attached to the pressure vessel. So as to retract to the outer periphery, One rail plug member is provided at the base so as to be movable in a direction crossing the moving direction of one nozzle plug device, and after inserting one nozzle plug device positioned at the center of the pressure vessel into the nozzle, The rail member is moved to the central portion, the other nozzle plug device is moved to the central portion, and the nozzle plug device is inserted into a nozzle different from the nozzle into which the one nozzle plug device is inserted. The apparatus simultaneously performs groove processing and build-up welding on the inner surfaces of the two weld joints.

  Also, a welded joint is provided to maintain a welded joint formed between a plurality of nozzles provided along the circumferential direction on the cylindrical side wall of the reactor pressure vessel and a pipe connected to the nozzle by welding. In the maintenance device for a welded joint portion that performs overlay welding on the inner surface of the portion, a structure that can rotate around the central axis of the pressure vessel is disposed above the pressure vessel, and the structure is vertically moved into the pressure vessel. A nozzle that suspends a pair of spaced-apart bases through suspension members, inserts the bases into the nozzle, processes the groove on the inner surface of the weld joint, and performs overlay welding The plug device is provided so as to be movable in the radial direction via the rail member and positioned between the base portions. When one nozzle plug device is at the center of the pressure vessel, the other nozzle plug device is attached to the pressure vessel. So as to retract to the outer periphery, One rail member is provided at the base so as to be movable in a direction crossing the moving direction of one nozzle plug device, and a welding machine for the nozzle plug device is welded to supply a welding torch and a welding wire to the welding torch. A wire supply unit and a magnetic stirring unit that magnetically stirs the build-up weld formed by the welding torch, and when welding by the welding machine, the welding wire is supplied to the welding torch to provide a welding wire. The molten metal in the build-up welded portion is stirred with a magnetic stirring portion while melting.

  ADVANTAGE OF THE INVENTION According to this invention, the welded joint part of the some nozzle provided in a pressure vessel can be maintained in a short time.

  Preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a side view of the maintenance device installed in the pressure vessel, and FIG. 2 is a plan view of the maintenance device installed in the pressure vessel. 3 is a cross-sectional view taken along line AA of FIG. 1, and FIG. 4 is a plan view of the upper rail member and the first nozzle plug device suspended by the upper rail member of FIG. 5 is a cross-sectional view taken along line B-B in FIG. 1, and FIG. 6 is a plan view of the lower rail member and the second nozzle plug device provided on the lower rail member in FIG. 5.

  As shown in FIGS. 1 and 2, a nozzle 3 for passing reactor water from the inside of the pressure vessel 1 to the outside or from the outside to the inside is provided in the circumferential direction on the cylindrical side wall 2 of the pressure vessel 1 of the pressurized water reactor. A plurality are provided along. The nozzle 3 is welded with a water supply pipe for supplying cooling water into the pressure vessel 1 and a pipe 4 such as an introduction pipe for introducing high-temperature water heated in the pressure vessel into a steam generator (not shown). Connected at.

  The pressure vessel 1 is made of a low alloy steel (for example, P-3). The pressure vessel 1 is formed of a clad layer whose inner wall surface is made of stainless steel (for example, SUS308).

  The pipe 4 is made of stainless steel (for example, P-8). The pipe 4 is connected to the nozzle 3 via a welded joint portion 5 made of a nickel-based alloy (for example, Inconel (registered trademark) 82 or Inconel 182).

  The maintenance device 6 protects the welded joint portion 5 by overlay welding on the inner surface of the welded joint portion 5. The maintenance device 6 includes a structure 7 that is rotatably provided around the central axis of the pressure vessel 1 at the upper end of the side wall 2 of the pressure vessel 1 with an upper lid (not shown) removed, and a suspension member 8 that is attached to the structure 7. A pair of base portions 9 and 10 that are suspended through and spaced apart from each other in the pressure vessel 1, and are movable to the base portions 9 and 10 in the radial direction via rail members 11 and 12, and the base portion 9. 10 and a pair of nozzle plug devices 13 and 14 provided so as to be positioned between the two.

  The structure 7 is formed in a frame shape extending in the diameter direction, and is provided on the annular rail 15 temporarily provided along the upper end of the pressure vessel 1 so as to be able to travel. A plurality of wheels 16 that run on the annular rail 15 are provided at both ends of the structure 7. In addition, the structure 7 is provided with a driving device 17 for causing the structure 7 to travel along the annular rail 15. The drive device 17 is provided with a pinion gear 19 on the drive shaft of the electric motor 18. The pinion gear 19 is meshed with an annular rack gear 20 provided on the inner periphery of the annular rail 15, and takes a reaction force from the rack gear 20 when the electric motor 18 is driven to rotate.

  The base portions 9 and 10 include an upper base portion 9 disposed above the nozzle 3 and a lower base portion 10 disposed below the nozzle 3.

  As shown in FIGS. 1 and 3, the upper base portion 9 is formed in a rectangular frame shape extending in the same direction as the structure body 7, and the four corners are suspended by suspension members 8. The suspension member 8 is composed of a hydraulic jack, and the height of the upper base 9 can be adjusted by the expansion and contraction of the suspension member 8. In addition, the upper base 9 is provided with a plurality of stoppers 21 in the circumferential direction that can extend radially outward in order to contact the side wall 2 of the pressure vessel 1 in order to fix the upper base 9. The stopper 21 is provided with a pad 23 that is in contact with the side wall 2 of the pressure vessel 1 at one end of the hydraulic jack 22. The stoppers 21 are provided at the four corners of the upper base 9, and the upper base 9 is fixed to the pressure vessel 1 by extending the respective stoppers 21 and contacting the side walls 2 of the pressure vessel 1. The upper base 9 has an upper transverse rail 24 extending in the short direction. The upper traverse rail 24 is formed at the bottom of the upper base 9 and suspends the upper rail member 11 so as to be slidable in the lateral direction of the upper base 9. The transverse rails 24 and 29 are provided with jacks (not shown) that can be adjusted in the vertical direction (up and down direction), and are finely adjusted so that the axis of the nozzle plug devices 13 and 14 and the axis of the nozzle 3 coincide with each other. Can be done.

  The upper rail member 11 includes a rectangular frame-shaped frame portion 25 that extends in the same direction as the upper base portion 9 and is shorter than the upper base portion 9, and a perpendicular rail that is provided on the lower surface of the frame portion 25 and extends in the longitudinal direction. Part 26. The direct rail portion 26 suspends a first nozzle plug device 13 to be described later so as to be slidable in the longitudinal direction. Further, the upper rail member 11 is arranged so as to be biased toward one end side of the structure 7 so that one end can be brought close to the nozzle 3.

  As shown in FIG. 5, the lower base 10 is formed in a rectangular frame shape extending in the same direction as the structure 7. Specifically, the lower base portion 10 includes a base body portion 27 having the same shape as the upper base portion 9 and a base extension portion 28 provided so as to protrude from the base body portion 27 on one side. It is designed to be hung by. The suspension member 8 is made of a hydraulic jack. At the four corners of the base main body 27, stoppers 21 similar to those described above are provided. The base extension portion 28 is formed in a substantially trapezoidal shape so as to constrict the tip end side, and does not interfere with the pressure vessel 1. The lower base 10 has a lower traverse rail 29 extending in the short direction. The lower traverse rail 29 is formed on the upper portion of the lower base 10 so as to extend over the base main body 27 and the base extension 28, and the lower rail member 12 is connected to the base main body 27 and the base extension. 28 so as to be slidable between the upper side and the upper side. As a result, when the first nozzle plug device 13 is at the center of the pressure vessel 1, the lower rail so that the second nozzle plug device 14, which will be described later, is retracted to the base extension portion 28, that is, to the outer peripheral portion of the pressure vessel 1. The member 12 can be moved.

  The lower rail member 12 includes a frame portion 30 having a rectangular frame shape extending in the same direction as the lower base portion 10, and an orthogonal rail portion 31 provided on the upper surface of the frame portion 30 and extending in the longitudinal direction. The direct rail portion 31 supports a second nozzle plug device 14 to be described later so as to be slidable in the longitudinal direction. In particular, the lower traverse rail 29 is disposed obliquely so as to be closer to the other end side of the structural body 7 from the base extension portion 28 side toward the base body portion 27 side, and the lower rail member 12 is the base portion. When moved onto the main body 27, the lower rail member 12 is guided so as to be biased toward the other end of the structure 7 to bring the lower rail member 12 closer to the nozzle 3 to be constructed, and the lower rail member 12 Is moved onto the base extension 28, the lower rail member 12 is moved to the vicinity of the center of the structure 7 in the longitudinal direction. This prevents the lower rail member 12 and the second nozzle plug device 14 from hitting the pressure vessel 1.

  As shown in FIGS. 1 and 4, the first nozzle plug device 13 is provided so as to travel along the direct rail portion 26 of the upper rail member 11 and to be able to rotate about the vertical axis in the traveling portion 32. A proximal end side shaft portion 33 that is provided so as to be rotatable about the horizontal axis and extends along the horizontal axis, and a distal end side shaft portion 34 that is provided on the distal end of the proximal end side shaft portion 33 so as to be rotatable about the same axis (rotation-free). The base end side shaft portion 33 is provided on the outer periphery of the base end side shaft portion 33 so as to be rotatable about the same axis (rotation-free). The third seal member 35 that closes the nozzle 3 and the outer periphery of the proximal end side shaft portion 33 on the insertion direction side of the third seal member 35 so as to be coaxially rotatable (rotation-free) and inserted into the nozzle 3. A second seal that contacts the inner peripheral surface of the nozzle 3 and closes the nozzle 3. , A grinder 37 provided on the proximal side shaft portion 33 on the insertion direction side of the second seal member 36 so as to be movable in the radial direction and axially movable, and a base on the insertion direction side of the second seal member 36. A welding machine 38 provided in the end side shaft portion 33 so as to be movable in the radial direction and axially movable, and a tip end side shaft portion 34 provided to extend radially outward from the tip side shaft portion 34. A guide wheel 39 that contacts the inner peripheral surface of the nozzle 3 or the pipe 4 when being inserted into the pipe 4 and guides the distal end side shaft portion 34, and is provided in the distal end side shaft portion 34 on the insertion direction side from the guide wheel 39. And a first seal member 40 that contacts the inner peripheral surface of the pipe 4 to close the inside of the pipe 4. Even if the pipe 4 into which the first nozzle plug device 13 is inserted (the pipe 4 connected to the nozzle 3) is bent, the distal end side shaft portion 34 and the later-described shaft portion 34 can be inserted so that the first nozzle plug device 13 can be inserted. The closing board 45 is connected through a universal joint (not shown).

  The traveling unit 32 includes a traveling unit main body 41 formed in a rectangular frame shape, and a vertical axis portion 42 provided on the traveling unit main body 41 so as to extend vertically. The proximal end side shaft portion 33 is provided so as to be rotatable around the axis of the longitudinal axis portion 42. The third seal member 35 includes a plate portion 43 that curves along the inner surface of the side wall of the pressure vessel 1, and a seal material 44 that is annularly provided on the surface of the plate portion 43 on the insertion direction side. The first seal member 40 and the second seal member 36 include a closing plate 45 formed in a disk shape, and a seal tube 46 that is provided on the outer periphery of the closing plate 45 and can be expanded and contracted. A pipe 47 for supplying a fluid such as air or water is connected to the seal tube 46.

  As shown in FIG. 7, the welding machine 38 includes a welding torch 48, a welding wire supply unit 50 that supplies an SCC-resistant and corrosion-resistant welding wire 49 to the tip of the welding torch 48, and a welding torch 48. And a magnetic stirrer 52 that magnetically stirs the built-up welded part 51. The magnetic stirring unit 52 is composed of a magnetic coil wound around the welding torch 48.

  Further, the third seal member 35 and the second seal member 36 have a supply pipe (not shown) for supplying air into the working area 53 formed between the first seal member 40 and the second seal member 36. While being inserted, a drain pipe (not shown) for discharging water from the work area 53 is inserted.

  The second nozzle plug device 14 has the same configuration as the first nozzle plug device 13. The same reference numerals as those of the first nozzle plug device 13 are assigned to the respective parts of the second nozzle plug device 14 and description thereof is omitted.

  Next, a maintenance method and operation of the welded joint portion 5 using the maintenance device 6 will be described.

  When carrying out maintenance work of the welded joint portion 5, after stopping the nuclear reactor, the upper lid of the pressure vessel 1 is removed. Thereafter, as shown in FIGS. 1, 2, and 8, the maintenance device 6 is installed in the pressure vessel 1. First, the maintenance device 6 is installed by temporarily installing the annular rail 15 on the upper end of the side wall 2 of the pressure vessel 1 and then installing the structure 7 on the annular rail 15. At this time, the two nozzle plug devices 13 and 14 are suspended in advance in the structure 7, and the structure 7 is suspended from above the pressure vessel 1 with a crane or the like. Further, when the structure 7 is suspended by a crane or the like, the first nozzle plug device 13 is aligned with the position of the nozzle 3 to be maintained. The first nozzle plug device 13 descends on the central axis of the pressure vessel 1 and is introduced into the pressure vessel 1 containing the reactor water, and the second nozzle plug device 14 descends from the outer periphery of the pressure vessel 1 to increase the pressure. It is introduced into the container 1. Thereafter, the hydraulic jack as the suspension member 8 is appropriately expanded and contracted to move the first nozzle plug device 13 and the second nozzle plug device 14 to the height position of the nozzle 3 to be maintained. The first nozzle plug device 13 is coaxial with the nozzle 3 to be maintained, and the second nozzle plug device 14 is at the same height as the nozzle 3 while being displaced in the horizontal direction with respect to the nozzle 3 to be maintained. The stoppers 21 of the upper base 9 and the lower base 10 are respectively extended and brought into contact with the side wall 2 of the pressure vessel 1, and the upper base 9 and the lower base 10 are fixed to the pressure vessel 1. In addition, an inspection device 54 for performing inspection before and after inspection of the welded joint portion 5 of the nozzle 3 is introduced into the pressure vessel 1 from the opening of the pressure vessel 1 on both sides of the structure 7.

  After that, as shown in FIG. 9, the first nozzle plug device 13 is moved outward in the radial direction of the pressure vessel 1 along the upper rail member 11. As a result, the first nozzle plug device 13 is linearly inserted into the nozzle 3, and a blank space is formed at the position where the first nozzle plug device 13 has been located so far.

  Thereafter, as shown in FIG. 10, the lower rail member 12 is moved along the lower traversing rail 29 toward the center of the pressure vessel 1 so that the second nozzle plug device 14 is placed on the axis of the nozzle 3 to be maintained. Position. Since the central portion of the pressure vessel 1 is a blank space, the first nozzle plug device 13 and other devices do not interfere with the second nozzle plug device 14.

  After that, as shown in FIG. 11, the second nozzle plug device 14 is moved along the lower rail member 12 radially outward of the pressure vessel 1 (in the direction opposite to the first nozzle plug device 13). As a result, the second nozzle plug device 14 is linearly inserted into the nozzle 3.

  When the first nozzle plug device 13 and the second nozzle plug device 14 are respectively inserted into the nozzles 3, maintenance work is simultaneously performed on the welded joint portions 5 of the respective nozzles 3.

  In the maintenance work, the working area 53 between the first seal member 40 and the second seal member 36 is made into a gas atmosphere, and then the groove is processed by the grinder 37 and the welded surface is polished to adhere to the welded surface. By removing foreign matter such as dust and clad, and performing build-up welding on the inner peripheral surface of the weld joint 5 in the work area 53 over the entire circumference, and grinding the build-up weld 51 by the grinder 37 as appropriate. Do.

  The work in which the inside of the work area 53 is in a gas atmosphere is performed by supplying a fluid into the seal tube 46 of the first seal member 40 and the second seal member 36 to inflate, thereby closing the nozzle 3 and the pipe 4 in a liquid-tight manner. This is done by supplying air into the work area 53 and draining the water in the work area 53.

  The welding operation involves arc discharge between the electrode of the welding torch 48 and the surface to be welded while rotating the base end side shaft portion 33 at a predetermined speed and moving the welding machine 38 in the circumferential direction. The welding wire 49 is supplied to 48 and the molten metal of the build-up welded portion 51 is stirred by the magnetic stirring portion 52 while melting the welding wire 49. That is, welding is performed by a magnetic stir welding (MSW) method. A Lorentz force is generated in the molten metal by a magnetic flux generated by flowing an alternating current through the magnetic coil serving as the magnetic stirring unit 52 and an electric current generated by arc welding, and the molten metal is stirred by the Lorentz force. By stirring the molten metal by magnetic force, heat transfer can be improved, wettability of the weld bead end (molten metal) can be improved, and occurrence of poor fusion can be reduced without increasing welding heat input. Similarly, in the base material of the dissimilar material welded joint portion 5 containing a large amount of chemical components that adversely affect welding, such as sulfur, fusion failure can be reduced. In the dissimilar material welded joint portion 5 including such a base material, In addition, the applicable welding condition range can be expanded. Also, for the dissimilar welded joint portion 5 of a combination of stainless steel and nickel-base alloy or the like, the alloy 52/152 is directly deposited as a weld metal in the first layer as well as the remaining layer without adopting the high sulfur mitigation layer. And weld cracking such as hot cracking can be prevented. In order to improve the wettability of the molten metal, MSW can flatten the bead cross-sectional shape even if the supply amount of the welding wire 49 is larger than that of the TIG welding. For this reason, the penetration of the base material (welded joint part 5) can be reduced, the dilution rate (ratio of penetration depth to the build-up amount) can be reduced, and when the welding conditions are the same, compared to TIG welding (GTAW), When MSW is applied, welding can be performed without causing poor fusion even in a region where the wire feed amount is large. That is, MSW can suppress hot cracking by suppressing the absorption of impurities such as sulfur from the base material. As a result, the amount of weld metal welded per unit time can be increased, so that the desired build-up welding can be performed in a relatively short period of time even in a large-diameter pipe.

  Further, when the second nozzle plug device 14 is inserted into the nozzle 3, a blank space is formed at the position where the second nozzle plug device 14 was located. The nozzle 3 that has finished the work and the nozzle 3 that performs the maintenance work next are inspected. Thereby, maintenance work and inspection work can be performed at the same time, which can contribute to further shortening of the maintenance work.

  When the maintenance work and the inspection work for the two welded joint portions 5 are thus completed, the inspection device 54 is retracted to the original position, and the seal tubes 46 of the first seal member 40 and the second seal member 36 are reduced. After the first seal member 40 and the second seal member 36 are separated from the nozzle 3 or the pipe 4 and the second nozzle plug device 14 is moved into the pressure vessel 1 and pulled out from the nozzle 3, the lower rail member 12 is moved. The first nozzle plug device 13 is moved into the pressure vessel 1 and removed from the nozzle 3 along the lower traverse rail 29, and the structure 7 is predetermined around the central axis of the pressure vessel 1. The first nozzle plug device 13 is adjusted to the position of the nozzle 3 to be maintained next by rotating the angle. Thereafter, maintenance work for all the nozzles 3 is performed by repeating the same work as described above.

  Thus, the structure 7 that can rotate around the central axis of the pressure vessel 1 is disposed above the pressure vessel 1, and a pair of base portions 9 that are arranged on the structure 7 so as to be spaced apart from each other in the vertical direction in the pressure vessel 1, 10 is suspended via a suspension member 8, and nozzle plug devices 13, 14 that are inserted into the nozzles 3 and are welded to the inner surfaces of the welded joint portions 5 on the base portions 9, 10 are rail members 11, 12. The second nozzle plug device 14 is disposed in the pressure vessel 1 when the first nozzle plug device 13 is at the center of the pressure vessel 1. 1, the lower rail member 12 is provided on the lower base 10 so as to be movable in a direction intersecting the moving direction of the first nozzle plug device 13 so as to be retracted to the outer peripheral portion of the pressure vessel 1. Nozzle longer than the radius of the container 1 Two lug devices 13 and 14 can be introduced at the same time, and these nozzle plug devices 13 and 14 can be inserted into the nozzle 3 respectively, and maintenance work of the welded joint portion 5 can be performed simultaneously at two locations. The welded joint part 5 can be maintained in a short time.

  The lower base 10 that supports the lower rail member 12 includes the lower traverse rail 29 that obliquely guides the lower rail member 12 with respect to the moving direction of the first nozzle plug device 13. Preventing the second nozzle plug device 14 from interfering with the first nozzle plug device 13 and the pressure vessel 1 when the lower rail member 12 is moved between the base main body 27 and the base extension 28. And maintenance work can be performed safely and reliably.

  Since the structure 7 is provided at the upper end of the side wall 2 of the pressure vessel 1 so as to be rotatable around the central axis of the pressure vessel 1, the structure 7 can be stably supported and can be easily put into a desired posture. The operation | work which matches the 1st nozzle plug apparatus 13 to the position of 3 can be performed reliably and rapidly.

  Since the suspension member 8 is made of a jack, the height of the first nozzle plug device 13 and the second nozzle plug device 14 can be easily adjusted.

  Since the bases 9 and 10 are provided with a plurality of stoppers 21 extending radially outward and circumferentially in order to fix the bases 9 and 10 in order to fix the bases 9 and 10. The base portions 9 and 10 can be reliably fixed to the side wall 2 with a simple structure, and the nozzle plug devices 13 and 14 can be stably moved.

  Further, after the first nozzle plug device 13 positioned at the center of the pressure vessel 1 is inserted into the nozzle 3, the lower rail member 12 is moved to the center of the pressure vessel 1 to press the second nozzle plug device 14. The second nozzle plug device 14 is moved to the center of the container 1 and inserted into a nozzle 3 different from the nozzle 3 into which the first nozzle plug device 13 is inserted. Since build-up welding is performed simultaneously on the inner surface of the portion 5, maintenance work of the welded joint portion 5 can be performed at two places simultaneously, and the welded joint portions 5 of the plurality of nozzles 3 can be maintained in a short period of time.

  Magnetic welding that magnetically stirs the welding machine 38 of the nozzle plug devices 13, 14, the welding torch 48, the welding wire supply unit 50 that supplies the welding wire 49 to the welding torch 48, and the build-up weld 51 formed by the welding torch 48. The welding stirrer 52 is provided, and when the weld welding is performed by the welding machine 38, the welding wire 49 is supplied to the welding torch 48 to melt the welding wire 49, and the molten stirrer 52 is melted by the magnetic stirrer 52. Since it stirs, the wettability of the weld bead end can be improved, the occurrence of poor fusion can be reduced, and weld cracks such as hot cracks can be prevented. In addition, the amount of weld metal deposited per unit time can be increased, so that high-temperature cracking can be suppressed by suppressing the uptake of impurities such as sulfur from the base metal. Can be welded.

  Although the structure 7 is provided to be able to run on the annular rail 15, the structure 7 is not limited to this. For example, the structure 7 can be rotated around the central axis of the pressure vessel 1 above the pressure vessel 1 by an overhead crane or the like. It may be supported by.

  The upper base portion 9 and the lower base portion 10 are suspended from the structural body 7 by separate suspension members 8, but may be suspended by a common suspension member (not shown).

  Further, when the lower rail member 12 is provided so as to be movable in a direction crossing the moving direction of the first nozzle plug device 13, and the first nozzle plug device 13 is at the center of the pressure vessel 1, the second nozzle plug device 14 is provided. However, the upper rail member 11 is movably provided in a direction crossing the moving direction of the second nozzle plug device 14, and the second nozzle plug device 14 is The first nozzle plug device 13 may be retracted to the outer periphery of the pressure vessel 1 when it is in the center of the pressure vessel 1. In this case, the upper base 9 has a base body 27 and a base extension 28 in the same manner as the lower base 10, and the upper traverse rail 24 is between the base body 27 and the base extension 28 below the upper base 9. Therefore, the upper rail member 11 is preferably slidably suspended, and the upper base portion 9 and the lower base portion 10 are preferably suspended by the common suspension member 8.

It is a side view of the maintenance device showing a preferred embodiment of the present invention. It is a top view of FIG. It is the sectional view on the AA line of FIG. It is a top view of the nozzle plug apparatus suspended by the rail member of FIG. It is the BB sectional view taken on the line of FIG. It is a top view of the nozzle plug apparatus supported on the rail member of FIG. It is a schematic explanatory drawing of a welding machine. It is plane explanatory drawing of the maintenance apparatus installed in the pressure vessel. It is a plane explanatory view in which one nozzle plug device was inserted in the nozzle. FIG. 6 is an explanatory plan view of the other nozzle plug device moved to the center of the pressure vessel. It is plane explanatory drawing in which the other nozzle plug apparatus was inserted in the nozzle. It is a sectional side view of the conventional maintenance apparatus. It is a sectional side view of the conventional nozzle plug device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure vessel 2 Side wall 3 Nozzle 4 Piping 5 Welded joint part 6 Maintenance apparatus 7 Structure 8 Suspension member 9 Upper base 10 Lower base 11 Upper rail member 12 Lower rail member 13 First nozzle plug device 14 Second nozzle plug device 21 Stopper 29 Lower traverse rail 38 Welding machine 48 Welding torch 49 Welding wire 50 Welding wire supply part 51 Overlay welding part 52 Magnetic stirring part

Claims (7)

  In order to maintain a welded joint portion formed between a plurality of nozzles provided along the circumferential direction on the cylindrical side wall of the reactor pressure vessel and a pipe connected to the nozzle by welding, In a maintenance device for a welded joint portion that performs overlay welding on the inner surface, a structure that can be rotated around the central axis of the pressure vessel is disposed above the pressure vessel, and the structure is spaced apart vertically within the pressure vessel. A nozzle plug device that suspends a pair of base portions arranged via suspension members, inserts the base portions into the nozzle, forms a groove on the inner surface of the welded joint portion, and performs overlay welding Is provided so as to be movable in the radial direction via the rail member and positioned between the bases, and when one nozzle plug device is located at the center of the pressure vessel, the other nozzle plug device is connected to the outer periphery of the pressure vessel. To evacuate the other Security device of the welded joint rail member supporting the Zurupuragu device is characterized in that is movable in a direction intersecting the moving direction of one of the nozzle plug device to the base.   2. The base portion that supports the other nozzle plug device via a rail member has a traverse rail that obliquely guides a rail member that supports the other nozzle plug device with respect to the moving direction of the one nozzle plug device. The welded joint maintenance device as described.   The welded joint maintenance device according to claim 1 or 2, wherein the structure is provided at the upper end of a side wall of the pressure vessel so as to be rotatable about the central axis of the pressure vessel.   The apparatus for maintaining a welded joint according to any one of claims 1 to 3, wherein the suspension member is a jack.   The welded joint according to any one of claims 1 to 4, wherein the base is provided with a plurality of stoppers that extend radially outward and are provided with a plurality of stoppers in contact with the side wall of the pressure vessel in order to fix the base. Department maintenance equipment.   In order to maintain a welded joint portion formed between a plurality of nozzles provided along the circumferential direction on the cylindrical side wall of the reactor pressure vessel and a pipe connected to the nozzle by welding, In a maintenance device for a welded joint portion that performs overlay welding on the inner surface, a structure that can be rotated around the central axis of the pressure vessel is disposed above the pressure vessel, and the structure is spaced apart vertically within the pressure vessel. A nozzle plug device that suspends a pair of base portions arranged via suspension members, inserts the base portions into the nozzle, forms a groove on the inner surface of the welded joint portion, and performs overlay welding Is provided so as to be movable in the radial direction via the rail member and positioned between the bases, and when one nozzle plug device is located at the center of the pressure vessel, the other nozzle plug device is connected to the outer periphery of the pressure vessel. To evacuate the other A rail member that supports the slip plug device is provided at the base so as to be movable in a direction crossing the moving direction of the one nozzle plug device, and after inserting one nozzle plug device positioned at the center of the pressure vessel into the nozzle. The other rail member is moved to the central portion, the other nozzle plug device is moved to the central portion, the nozzle plug device is inserted into a nozzle different from the nozzle into which the one nozzle plug device is inserted, The maintenance method of the welded joint part characterized by carrying out groove processing and overlay welding simultaneously on the inner surface of two welded joint parts with these nozzle plug devices.   In order to maintain a welded joint portion formed between a plurality of nozzles provided along the circumferential direction on the cylindrical side wall of the reactor pressure vessel and a pipe connected to the nozzle by welding, In a maintenance device for a welded joint portion that performs overlay welding on the inner surface, a structure that can be rotated around the central axis of the pressure vessel is disposed above the pressure vessel, and the structure is spaced apart vertically within the pressure vessel. A nozzle plug device that suspends a pair of base portions arranged via suspension members, inserts the base portions into the nozzle, forms a groove on the inner surface of the welded joint portion, and performs overlay welding Is provided so as to be movable in the radial direction via the rail member and positioned between the bases, and when one nozzle plug device is located at the center of the pressure vessel, the other nozzle plug device is connected to the outer periphery of the pressure vessel. To evacuate the other A rail member for supporting the slip plug device is provided at the base so as to be movable in a direction intersecting with the moving direction of one nozzle plug device, a welding machine for the nozzle plug device, a welding torch, and a welding wire for the welding torch. A welding wire supply part to be supplied and a magnetic stirring part for magnetically stirring the build-up weld part formed by the welding torch are provided, and when welding with the welding machine, the welding wire is supplied to the welding torch. A method for maintaining a welded joint, comprising: stirring the molten metal of the build-up weld with a magnetic stirrer while melting the welding wire.

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