KR830001421B1 - How to repair the steam generator - Google Patents

Abstract

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Description

How to repair the steam generator

FIG. 1 is a vertical sectional view of the line I-I of FIG. 2, shown with parts removed for simplicity of illustration.

2 is a bottom view of the steam generator of FIG.

3 is a plan view showing the arrangement of holes formed in the tube sheet.

4 is a partial vertical cross-sectional view of the tube sheet showing the concavely curved tube sheet surface.

5 is a side view of a repair machine used to practice the present invention.

6 is an enlarged vertical cross-sectional view of the Wangbukdae mounted on the repair machine of FIG.

7 is a plan view of the carriage.

8 is a block diagram of a control device used to practice the present invention.

FIG. 9 is a block diagram showing a part of the control device of FIG. 8 in detail. FIG.

10 is a side view of a probe used in the practice of the present invention.

11 is a sectional view taken along the line XI-XI of FIG.

FIG. 12 is an enlarged plan view of a part of the hole rows of the tube plate shown in FIG.

13 is a flowchart showing the installation process of the repair machine by the control device.

14 is a flow chart showing a positioning process.

FIG. 15 is a flow chart illustrating a process of adjusting the operation of two repair machines during relocation of a tube.

FIG. 16 is a flowchart showing a process of performing work on each hole of a tube sheet. FIG.

The present invention relates to a method of repairing a steam generator, and more particularly to a method of remotely repairing the tubes and tube plates of a steam generator.

In a power plant using a boiling water reactor, the heat generated by the nuclear reaction is absorbed by the main coolant circulating through the reactor core and used to generate steam in the steam generator. Steam generators are typically upright cylindrical pressure vessels with hemispherical ends. The diaphragm, which is located at the bottom of the cylindrical part of the steam generator, called a tube plate, divides the steam generator into a first part, which is a hemispherical part located under the plate, and a second part located on the plate side. In addition, the first part of the steam generator is divided into an inlet and an outlet by vertical walls. The tube sheet is a thick carbon steel sheet, which has thousands of holes formed to receive the ends of the U-shaped tube. Thus, one end of the U-shaped tube is inserted into the hole communicating with the inlet of the first part, and the other end is inserted into the hole communicating with the outlet of the first part. Thus, the main coolant pressurized into the inlet of the first part is circulated through the U-shaped tube and discharged to the outlet. It is also possible that during the operation of the steam generator accidentally leaks in some pipes, such leaks are undesirable because the main coolant is radioactive and flows into the second part of the steam generator to contaminate the steam. will be. However, it is uneconomical to replace a tube that produces such a leak, and instead of temporarily replacing it, it will not be used to temporarily block both ends of the tube. Blocking does not affect heat transfer efficiency.

However, in the end, if a significant number of pipes are blocked, the heat generator efficiency and the steam generator efficiency will be affected, and the steam generator must be stopped for the replacement of the pipe. In a tube replacement operation, all holes in the tube sheet, including blind holes, are drilled to spotfacing from the first part of the steam generator and then drawn out of the second part of the steam generator. Thereafter, a new tube is inserted through the second part of the steam generator, and when the tube is inserted, the tube guide is installed at the end of the tube, into the hole of the transverse support plate located in the second part of the steam generator and into the hole of the tube plate. Insertion of the tube can be facilitated. After the insertion of the tube is completed, the tube guide is removed from the first part of the steam generator, and the end of the tube is aligned with the spot faced end of the tube plate hole, fixed by the tack roll method, and welded in place. .

In the second part of the steam generator there is no problem of spatial adjustment, but the hemispherical first part, which is partitioned by the vertical wall, has a radius of about 1.5 m (5 feet), so it is particularly useful near the tube plate. Not enough space to do it. In addition, since the first portion has radioactivity, it is necessary to limit the worker's protection and exposure time.

A tool device has been developed which is capable of at least partially automatic regrinding of the steam generator, which has been configured to be cam-locked in the hole of the tube sheet to automatically support the tool. However, with this device only drilling and spotfacing operations and welding were required, and moving the device between the holes required the operator to enter the first part of the steam generator, where thousands of holes were formed in the tube sheet. In view of this, such work was a waste of time.

Thus, so-called "mobile" tool devices have been developed that allow the operator to move between the holes as they adjust outside the steam generator. In the case of this device, the operator adjusts the scale model while watching the television subtitle to make the camlock move between holes. In addition, this device can speed up the drilling and spotfacing work and the welding work, which can reduce the worker's exposure to radiation, but it requires skilled work. Was not only as fast as desired speed, but also not all the work could be done, so the operator had to stay in the first part of the steam generator for a significant amount of time. In addition, the use of the above two conventional tooling devices prevents the spot facing surface from being located on a common plane, that is, on the same plane because the pipe holes are spot-facing to a certain depth with respect to the adjacent tube sheet surface. .

Accordingly, the present invention is to provide a steam generator repair method that can automate all the replacement work to minimize the downtime of the steam generator and the worker's exposure to radiation.

According to the present invention, the repair of the steam generator is made by accurately identifying and remembering the angular position of the tube plate hole by the probe, and the position of the memorized hole is performed by performing various tools when performing one or more operations for each hole. Used to allow it to be placed in place. In this operation, the old pipe is drilled, the drilled hole is spot-facing, preferably coplanar, a new pipe is inserted into the hole so that the end of the pipe is coplanar with the spot-facing surface and the tube plate And cleaning the tube end with a wire brush, and then expanding the tube and welding to fix the tube end in place, and cleaning the weld and remotely inspecting the weld end.

Positioning ensures that the probe that detects the hole wall of the tube plate is generally aligned in line with the hole, then moved into the hole, again adjusts the probe until it is exactly in the center of the hole and remembers the position of the hole. This can be achieved by. In a preferred embodiment of the present invention, the probes are aligned in line with the holes by adjusting the angular position of the arm mounted to rotate in parallel with the tube plate and the position of the carriage movable along the arm. have. Once the exact position of the hole is remembered, the position of the arm and the carriage is adjusted to cause the probe to be moved by a first set distance in a direction parallel to the column, to align it with the next hole to be probed, in such a way that the probe along the row Will move. The probe is also adjusted to move by a second set distance in a direction parallel to the row, so that the same sequence can be repeated to precisely position the selected hole in the other column. Since the probe is moved to the next hole by moving the set distance from the exact position of the already probed hole, the error does not accumulate.

If the first and second set distances are equal to each nominal distance between columns and rows, then all holes will be probed, and if such set distances are equal to multiples of the nominal distance, only some of the holes will be probed. The position of the other hole in the probe can be determined by adding or subtracting the nominal distance to the coordinate of the hole closest to that hole.

Before the hole positioning process, an electric signal indicating the distance from the free end of the arm to the tube plate measured at the angled position can be generated so that the arm can be accurately positioned parallel to the tube plate. Adjust the arm pivot axis against the tube until it is within error. Since the arm is pivoted with the pivot point near the center of the straight side of the semicircle of the tube plate, a fourth signal is generated representing the distance from the arm to the tube plate at the point near the pivot point of the arm and the signal is converted into the three signals. By comparison with, the plan view of the tube sheet can be determined. The resulting signal is then used to guide the drill to spotface all holes coplanar, regardless of non-uniformity of the tube surface.

In addition, according to the invention the operation of the arms respectively installed on both sides of the first part of the steam generator is to be coordinated. That is, the operation of the two arms is mutually coordinated to spotface the tube plate holes located on both sides of the divider in the same plane and to position the tool in the predetermined holes on both sides thereof. When the both ends of the U-shaped tube are inserted into the holes, the protruding length of the tube end from the tube plate is measured by the tools installed on the two arms, and the arm for repairing the tube end projected to the shortest distance is operated first. The tube ends are placed on the same plane as the spot face surface and then expanded. The other arm then operates to align and expand the other end of the tube as described above, after which both ends are automatically welded in place. The operation of each tool installed in the two arms is mutually coordinated in the manner described above for the holes arranged on both sides of the divider until the installation of all the tubes is completed.

As such, according to the present invention, the time required for repairing the tube sheet and the radiation exposure of the operator can be greatly reduced, and an accurate position data map of the tube sheet can be provided later. Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention.

As described above, the present invention may be applied to repairing other types of steam generators in addition to applying to repair the steam generator 1 (FIG. 1) of a power plant using a boiling water reactor. The apparatus used to practice the present invention has two repair machines 3 remotely controlled, one of which is shown in detail in FIGS. 5 to 7. The machine is capable of installing a number of tools to perform various functions in the steam generator and is operated by the control devices shown schematically in FIGS. 8 and 9. Such tools include probes to confirm the precise location of each hole in the steam generator tube, drill and spotfacing tools for spotfacing while drilling old pipes, such as blind pipes, and brushes for cleaning the holes. Can be heard. Other tools used during the tube exchange process include an extractor that removes the tube guide used to insert the tube through the tube plate, and expands the newly installed tube to coplanar with the tube plate and to hold them in place. An expander, a wire brush tool used to clean the weld before and after welding, and a welding tool for automatically welding the expanded tube. In addition, a closed-circuit television camera is used to inspect the installation of the tube.

As shown in FIG. 1, the steam generator 1 has a cylindrical body 5 in which a hemispherical shell 7 is fixed at the bottom, and at the bottom of the cylindrical body 5 is a transverse steel plate 9 called a tube plate. ) Is installed, which causes the steam generator to be split up and down into a first part (11) and a second part (13). The first part 11, referred to as a channel head, is divided in half into an inlet 17 and an outlet 19 by a vertical divider 15.

As shown in FIG. 3, the tube plate 9 is arranged with thousands of holes 21. Thus, thousands of U-shaped tubes 23 (only two are shown in FIG. 1 for simplicity of illustration) are inserted into corresponding holes 21 formed on both sides of the tube plate, so that one end of each tube 23 has a channel head. It is in communication with the inlet 17 of the other end is to be in communication with the outlet (19). The tube 23 is supported on the second part 13 of the generator by a divider 25 braced by a tie rod 27 and an anti-vibration bar 29.

The main coolant from the reactor enters the inlet portion 17 of the channel head through the inlet 31 (shown in FIG. 2), circulates through the U-shaped tube 23, and then through the outlet 33. It is discharged from the outlet 19 of the channel head. Water enters the second part 13 of the generator 1 through the inlet 35 and circulates around the pipe 23, which is then converted to steam by the heat released from the main coolant. A baffle 37 forms a preheating portion that initially directs water around the inlet of the tube 23 for increased efficiency. Steam generated in the second part 13 rises into the steam drum (not shown), where water droplets are removed by the demister and discharged from the steam generator through the second outlet (not shown). do. On the tube plate 9, scales and debris on which T-shaped blowdown tubes 39 (only one of which is shown in FIG. 1) installed on each side of the second part 13 of the generator are accumulated. It is used to periodically inject pressure fluid around the outside of the tube 23 to remove it.

The operator can enter and exit the inlet portion 17 and the outlet portion 19 of the channel head 11 through the inlets 41 and 43 so that maintenance can be performed. As shown in FIG. 23 and the repair machine 3 for repairing the tube plate 9 are inserted through the inlets 41 and 43 and installed in the channel head on each side of the divider plate 15.

A typical arrangement of the holes 21 formed in the tube plate 9 is shown in FIG. 3, as can be seen in the figure, the holes formed in each half of the tube plate 9 are in a vertically oriented row to form a hemispherical shape. In the figure, they are arranged in rows extending horizontally. In such an arrangement, no hole is formed where the T-shaped area 45 and the tie rod 27 are located below the blowdown tube 39. Only holes located on the periphery are shown in the figure, but it should be noted that the holes are also formed in the remaining parts.

The tube plate 9 is a large steel plate that is about 3 m (10 feet) in diameter and close to about 50 cm (2 feet) in thickness. The lower surface 10 of the tube plate is pore to be flat, but may be slightly convex or concave as shown in the enlarged form in FIG. 4 due to manufacturing tolerances. Such bending of the lower surface of the tube sheet is determined during the installation process as described later.

The repair machine 3 is described in detail in US Pat. No. 4,205,940. By referring to FIGS. 5 to 7, the structure of the apparatus necessary for understanding the present invention can be fully understood, as shown in the figure, the vertical column 47 is adjacent to the divider 15 and generally has a tube plate ( It is installed in the channel head 11 perpendicular to the 9). The lower end of the post 47 is pivotally supported by a bore bearing support 49 welded to the shell 7 and the upper end of the post 47 is fixed to the divider 15 by welding or the like. The column 47 is rotatably positioned in the second support device 51 by an antifriction bearing, such as a ball or roller bearing (not shown), and the second support device 51. The split collar 53 is positioned with a clearance 55 closed by the hydraulic cylinder 57 so as to fix the column 47 at any rotational position.

The upper end of the pillar 47 can be adjusted in two diagonal directions on a plane parallel to the tube plate 9 by the second support device 51. The top of the column 47 can also be pivoted from side to side with respect to the spherical bearing support 49 on the drawing plane of FIG. 5 by bolts 59, and with respect to the drawing plane by the dovetail and screw device 61. It can be moved in the vertical direction.

Arm 63 is pivotally connected to the top of column 47 by a suitable mounting bracket 65. The pivot connection is that the free end of the arm 63 lines up with the inlet 41 from the position parallel to the tube plate 9 as shown in FIG. 5 while the arm 63 rotates with the column 47. It is made to be able to pivot up to the position where it is located. Such a pivotal movement of the arm 63 is each a pair of hydraulic cylinders 67 pivotally connected to the lower end of the maneuver 47 by a bracket 69 and pivotally connected to the free end of the arm 63 by a bracket 71. (Only one city in FIG. 5).

An inverted hollow shaft DC motor 73 having a torque connector 75 mounted on the divider plate 15 and installed on the column 47 pivots the arm 63 on a plane parallel to the tube plate 9. Rotate the column 47. The motor is provided with a device for accurately indicating the hollow shaft and the respective positions of the arms 63.

Arm 63 has a pair of parallel rails or channels 77 (only one shown in FIG. 5) with passages 79 at the top and bottom. The passages 79 extend longitudinally along the arm and are parallel to each other. The carriage 81 slidingly mounted on the passageway 79 has a pair of bearings 83 connected to each passageway 79, so that the carriage 81 is about the longitudinal axis of the arm 63. Move in parallel and linearly.

As clearly shown in FIGS. 6 and 7, the carriages 81 are parallel to each other and the base plate being parallel to the tube plate 9 when the longitudinal axis of the arm 63 is parallel to the tube plate 9. (85) and platform (87). The base plate 85 is connected to the bearing 83 and the platform 87 is installed on the base plate 85 in parallel. An air motor 89 or other suitable device that supplies rotational driving force for various tools is connected to the platform 87.

A device for raising and lowering the platform 87 relative to the base plate and maintaining parallel between them slidably slides the four cylinder posts 91 and the posts 91 attached near the four corners of the platform 87. It consists of eight ball bushings 93 positioned on base plate 85 and a pair of hydraulic cylinders 95 connected to base plate 85 and platform 87 to act dually.

An apparatus for indicating the position and velocity of the platform 87 relative to the base plate 85 is indicated by reference numeral 97.

A cantilevered tool holder 99 is attached to the platform 87 and connected to the drive motor 89. The tool holder has a tool chuck 101 at its distal end to support the tool, and a gear train or other drive device 103 connects the drive motor 89 to the tool chuck 101 to drive the tool 105. Provide power for

As shown in FIG. 5, the ball screw 107, the drive motor 109, and the ball nut 111 are installed in the arm 63 and the carriage 81 in a combination so that the armchair 81 can be moved. A device for linearly moving and maintaining at any moving position is thus provided. The ball screw 107 extends over the entire length of the arm 63 and is positioned generally parallel to the longitudinal axis of the arm. The ball nut 111 is attached to the carriage 81 and is screwed to the screw 107. A resolver 113 is installed to indicate the location of the carriage moving along the arm.

The arm 63 is equipped with a pair of hydraulic cylinders 115, the hydraulic cylinders of which the cell 105 holds the arm 63 to secure the arm 63 when the tool 105 performs work on the tube 23 or the tube plate 9. It has a piston rod 117 that can extend outward to contact the wall of (7).

As clearly shown in FIG. 7, the cantilevered tool holder 99 has an arc plate 119 installed at equal intervals on both sides of the drive motor 89 axis. The lug 121 allows the arc plate 119 and the tool holder 99 to be fastened to the platform 87. As dowels and more holes (not shown) are installed in the platform and arc, the tool holders are rotated in line with the arm axis, or 180 °, as shown in FIG. 6, or in FIG. As shown, it can be rotated to achieve a predetermined acute angle with respect to the arm axis. The change in the position of the tool holder and the column 47 allows access to all the pipes installed in the half of the tube plate, and enables accurate positioning of the tool holders for all pipes located in the half of the tube plate. It is possible to perform repetitive work by remote control. The tool holders described are particularly suitable for supporting drill tools, but can also be used to support probes or brushes. Support the other tool. Other tool holders may be installed on the carriage 81. Tool change can be accomplished by positioning the free ends of in-line 41 and arm 63 in a line as shown on the right side of FIG. The tool holder shown is to be manually rotated to the required position and to be fixed in that position, but may also use an autorotating tool holder as described in US Pat. No. 4,200,424.

The reinforcement bracket 123 of the C type is provided in the starting 47 supporting the motor 73, and acts to reduce the warpage of the column 47.

The repair machine described can be easily and quickly installed inside the head of a steam generator, and the tools installed therein can perform several operations on all the pipes located in the half of the pipe. The machine constructed as described above is robust and reliable and can be operated using remote control within the small tolerances required to exchange the steam generator tubes. For remote operation, each position of the arm and column must be repeatable. Accurate angular positioning of the pillars and arms and indications of their angular positions are provided by the motor 73, and once the pillars and the arms are positioned at the required angular positions, the split collar 53 is positioned therein. Fix it.

The carriage 81 is positioned by the rotation of the ball screw, and a brake is positioned inside the motor to act to keep the screw in the required position. The screw is also fitted with a nut with a number of balls that snap into its helix. This combination minimizes backlash, so that the positioning of the carriage is very accurate. The combination is not driven back by the carriage, so the drive motor brake is held in the bite and the carriage is held in a fixed position. . A hydraulic cylinder which raises the arm 63 from a position in line with the inlet 41 to a position substantially parallel to the tube plate 9 acts on the stop to increase the rigidity of the device in the stop position.

8 is a block diagram of a control device for controlling a repair machine, which includes power loss detection and protection, automatic restart characteristics, a bootstraploader, a real-time clock, and a 64k 16-bit / word non-volatile memory. Equipped with a digital computer such as Westinghouse 2500 Model D. The operator indicator panel 127 allows the operator to see the performance and status of the device. Cathode ray tube (CRT) display 129 with integrated alphanumerc keyboard and non-linear editing features allows the operator to input operating parameters, data and instructions to the computer, display and edit input information, and visually It acts as the primary connector connecting humans and machines to obtain the collected data or programmed responses that are automatically displayed for personal inspection. The hard copy printer 131 with an integrated alphanumeric keyboard operates as a hard copy data input and output device with a keyboard used as a back cathode ray tube data input device. A computer is programmed through the paper tape reader 133 and used to input data such as tube arrays of incremental tapes that the two magnetic tape devices 135 will repair.

The computer 125 supported by the peripheral equipment acts as the monitoring and control element of the device. The computer monitors all strategic system parameters and controls all tool operation functions via the control processor 137. The control processor 137 provides three axes of absolute position control with respect to the repair machine 3. That is, the control processing apparatus 137 follows the angular position (θ axis) of the arm 63 through the control of the monitor 73 with respect to the repair machine 3, and the arm through the control of the carriage drive motor 109. Control of the position (R axis) of the carriage 81 and control of the vertical position (Z axis) of the tool on the carriage via control of the dual actuating hydraulic cylinder 95. The drive device consists of a high performance closed loop servo control device with high accuracy, speed response and position control.

The main element of each axis drive device is an absolute position controller using a remote positive feedback device of a closed-loop position control device as shown in FIG. Input data for each axis is supplied from the computer 125 to the control processing unit 137 through the line 139, and the control processing unit 137 supplies the operation data to the predetermined axis processing unit 141 The required axis position is supplied to the position storage device 143. The shaft position comparator 145 then determines the amount of movement of the drive motor and determines the direction by comparing the actual position of the position indicator 147 with the required position. The output of the comparator 145 is supplied to the shaft motor driver 149 which supplies the shaft motor 151 with the appropriate polarity and the appropriate amount of power. When the selected motor is rotated, the position feedback device 153 connected thereto will report back to the processing unit 141 via the line 155. If the requested position is equal to the actual position, the motor drive is stopped. As shown in FIG. 8, the control processor 137 reports axis movement back to the computer via line 139. FIG. During the drilling operation, the drill bit rate is fed back to the computer 125 via the line 157, so that the drill bit rate is adjusted in response to the change in the drill speed due to the change in the hardness of the drill material and the wear of the drill bit. .

Each axis of the control processing device 137 operates in the same way to generate a control signal for the drive element connected to the repair machine 3, the Z axis signal being transmitted from the hydraulic system 161 to the tool holder 99. ) Is supplied to two hydraulic servos 159 that regulate the flow of hydraulic fluid to two hydraulic cylinders 95 that are dual actuated to raise and lower the installed platform 87. Height adjuster 163 may be used to set hydraulic servo 159 to elevate platform 87.

The above closed circuit control device is used to position and control the tool for installation, positioning, drilling and spotfacing, removal of pipe guides, wire breaking, pipe installation and expansion, welding and welding inspection, and the like. The positioning of the welding tool is controlled by the computer 125 and the welding parameters are automatically adjusted by the welding power source 151. When welding is complete, the power source 151 notifies the computer that the computer places the tool in the next hole and sends another start signal to the welder.

The computer 125 controls and monitors the work of the repair machine 3 through a similar control processing device 137. It also controls the operation of the repair machine during repositioning of the pipes, such as the hoops.

Repair tools use several tools or operators. This tool has a probe 165 having an elongated body 167 that is inserted into the hole 21 of the tube sheet as shown in FIGS. 10 and 11. A pair of diagonally positioned sense coils 169, 171 are installed on the sidewall of the probe 165. Each pair of coils forms a vortex proximity detector that generates a zero signal when the probe is positioned at a distance from the coil's axis to the hole wall into which the probe is inserted. The probe 165 in the tool holder 99 has the axis of the coil 169 parallel to the moving axis (R axis) of the carriage 81 and the axis of the coil 171 is the rotational movement trajectory of the buoy 63. By being mounted so as to be parallel to the tangent (θ axis) of the signal, the signal generated by the detector can be used in the driving device of the repair machine described later to accurately position the repair machine at the center of the hole 21. The probe 21 also has an end proximity sensor 173 that can also be used to determine the distance (Z-axis component) between the tube plate 9 and the carriage of the repair machine and the presence of a hole at a particular location for the purpose of the following. Is installed. As the probe, a suitable one of the above-described or another type may be purchased and used. In addition, the end proximity detector may be replaced by a limit switch to determine the Z-axis component.

Other tools used in repair machines include drills and spot facing tools. This tool is driven by the motor 89 via the gear train driver 103, which is used to drill blind holes and old tubes. The drill bite is provided with a shoulder for spotfacing the drilled hole indicated by reference numeral 175 in FIG. Another tool used with the repair machine is a brush inserted into the tube for cleaning before repositioning the tube. Subsequent to tube placement, a surface brush may also be used to clean the surface for welding prior to inspection.

As will be described later, the guide is inserted into the end of the U-shaped tube 23 to guide the replacement U-shaped tube 23 through the separating plate and tube plate 9, so that the guide is followed by pipe inspection using another tool. Should be removed. Suitable tools for this purpose include those described in US Pat. No. 4,180,902.

A tube expansion tool is also used to expand the newly installed tube in the hole 21 to hold the tube in place to seal and weld the hole. Tools of this kind are also readily available; hydraulic tube expanders suitable for this purpose are described in US Pat. No. 4,125,937. It is also possible to use a roller-type tube expander as described in US Pat. No. 4,178,787 and US Pat. No. 2,835,307. Welding tools for automatically welding around the pipe ends are also readily available and can be controlled by a repair device. Finally, a closed-loop TV camera could be installed on the carriage for inspection of the weld.

Probes, drills and brushes may be installed in the tool holders shown in FIG. 6 and FIG. Other tools, such as closed-loop TV cameras with or without a drive on their own, may be mounted to the tool arm without the need for a gear train driver as shown in FIG.

In order to exchange the various tools, the arm 63 is rotated, and the hydraulic cylinder 67 also lines the carriage 41 and the inlet 41 in line with each other as shown on the right side of FIG. It will work to align. In this way, the tool can be changed quickly to minimize the radiation exposure of the operator in the channel head.

In general, the repair machine 3 is installed on both sides of the steam generator channel head 11 and the parallelism of the arms 63 and the depth to the spot facing surface are determined as follows. The remaining functions performed by the repair machine 3 can be broadly divided into pipe removal and pipe placement operations.

Tube removal operations include the process of locating tube plate holes and drilling and spotfacing the tube in the manner described in order to determine the exact position of each arrayed hole.

The repositioning of the tubes involves the step of inserting the end of the U-shaped tube into the hole of the tube plate in communication with the channel head inlet and outlet, respectively, and extracting the guide used to move the tube end through the separator plate and tube plate. The end of the tube is then coplanar with the spot facing surface adjacent to each hole and fixed in place by a tube expander. The tube end is then welded in place, followed by brushing and the weld is remotely inspected by the closed circuit TV.

The first step in repairing the steam generator is to install the repair machine 3 in the channel head 11 of the steam generator such that the rotational plane of the arm 63 is parallel to the lower surface of the tube plate 9. Once the repair machine is installed manually, the operator may use the methods and apparatus described, for example, in US Pat. No. 4,247,974, to make the arms parallel to the tube sheet surface.

By the system at widely separated three points the distance between the arm 63 and the tube plate 9 is represented as parallel points (A), (B) and (C) so that the arms can be accurately aligned parallel to the tube plate. It is measured automatically. Parallel points (A), (B) and (C) are located at 0 °, 90 ° and 180 °, respectively, as shown in FIG. 3 near the periphery of the row of holes so as to more accurately establish the plane of the tube plate. . The distance measurement at the three points takes the form of an electrical signal generated by the probe, and when the measurements are within a predetermined tolerance (eg 0.003 cm (0.001 inch)), the arms are parallel to the tube plate. It is considered to be one, and thus the apparatus proceeds to the next process. Four measurements are made at each of the parallel points (A), (B) and (C) in order to ensure accuracy in the alignment of the arm with respect to the tube. As shown in FIG. 12, four measurements at the parallel point A are made at the data points A ₁ to A ₄ around the hole centered at the parallel point. In addition, although there is no hole, four measurements are performed at the parallel point B at the data points around it. If the difference between the average measurements obtained at the parallel points (A), (B) and (C) is not within the predetermined tolerances, the measurement is repeated until the arrangement of the support columns 47 is adjusted as described above and parallelism is achieved. do.

Its sequence is schematically shown in the flow chart of FIG. As indicated in block 177, the data of the primary parallel point enters, and the arm 63 and the carriage 81 align the probe 165 mounted on the carriage 81 below the primary data point. So as to be indicated at block 179, each is angularly positioned in the longitudinal direction. The probe then moves up as shown in block 181 until its proximal end generates a set signal indicative of the set distance from the tube or the limit switch is activated. The height of the probe indicating the distance between the surface of the tube plate and the arm is recorded as indicated in block 183, after which the probe is lowered as indicated in block 185 so as to return to its original position. If it is determined in block 187 that the measured point is not the last of the four points of one parallel point selected in the three parallel points (A), (B) and (C), then the block 189 shows the next data as indicated. The coordinates of the point are input and the above process is repeated. Once the measurements for all four data points are complete, at block 191 the average measurement of this parallel point is determined. If it is determined in block 193 that the measured position is not the last of the three parallel points (A), (B), or (C), then data is entered for the parallel point of the next position, as in block 195. Therefore, the average distance of each position is determined as above. The average distances of the three parallel points A, B, and C are then compared as in block 197 to determine whether the arms are parallel to the tube plate. If at block 199 it is determined that the average distance is not within ± 0.003 cm (± 0.001 inches) as the expected nominal example, an operator alert is generated and the average distance is printed out as in block 201. The device then waits for reactivation until the arrangement of the support posts 47 is adjusted as described above based on the printed results as in block 203. After relocation, the operator starts the operation again and re-enter the data for the primary parallel point as in block 205, repeating the entire sequence described above to check the parallelism of the tube plate 9 and the arm 63. do. If it is determined at block 199 that the distance to the three parallel points is within a predetermined tolerance, that is, if the arm is parallel to the tube plate, the plan view of the tube plate is determined at block 207. Since the warpage of the tube sheet is concave or convex, one additional reading is required at one point D (shown in FIG. 3) near the center of the tube plate. This is done by retracting the carriage-mounted carriage 81 to the vicinity of the pivotal end of the arm 63, and then four distances around the point D as in the case of the three parallel points A, B, and C. This can be done by taking measurements and averaging them. If the distance between the arm and the tube plate at the point D is greater than the distance at the parallel points A to C, the tube plate is concave, while smaller than the distance at the parallel points A to C. If it is convex. Eventually, the spotfacing plane position in the double record 209 is determined by adding a predetermined tolerance to a larger value of the distance from the arm to the point D or the parallel points A, B and C, This Z-axis information is stored and printed as in block 211. Preferably, the common spot face plane can be established across the tube by comparing the two sides of the tube through the parallel point and the point D.

The probe 165 is also used to identify the hole position of the tube sheet so as to determine the exact position of the thousands of holes arranged as shown in FIG. For example, the holes in the tube plate are arranged in a row superheat with a center spacing of 2,6988 cm (1.0625 inches) and have a diameter of 1.935 to 1.948 (0.762 to 0.767 inches). It is desirable to determine the location of the holes that are carefully machined during fabrication and located at a distance closest to each other 0.003 cm (0.001 inch).

The order of the localization process is shown schematically in the flow diagram of FIG. The R-axis driver and the soccer synchronous, which control the angular position of the arm 63 and the longitudinal position of the carriage 81, respectively, operate to position the probe 165 accurately under the holes located in the first row and the first column. do. Then, the Z-axis driver for adjusting the vertical movement of the platform 87 installed in the carriage 81 is operated to insert the probe into the hole as indicated by the block 213. If the probe is not centered with respect to the hole and the zero point is not displayed on the θ axis detector or the R axis detector at block 215, then the θ or R axis actuators are respectively marked as shown in blocks 217 and 219. It will work to zero the sensor. Adjusting the probe to the zero position for one axis affects the zero position for the other axis, so adjust the probe until the center is precisely positioned with respect to the hole and then again center at block 215. Check Thereafter, the actual position of the holes spaced about 0.003 cm (0.001 inch) is stored at block 221.

If it is determined in block 223 that the memorized hole is not the last hole in the column, then a set distance is added to the row coordinates, for example a nominal distance of 2,6988 cm (1.0625 inches), so that the probe As in 225, the new position is moved. The end detector installed in the probe is then used to determine whether a new hole is blocked or not, as in block 227. If blocked, this fact is recorded and again the probe moves to the next hole in the heat, as in block 223. If this new hole is not blocked or present, the probe is inserted into the hole to a depth suitable for the operation of the R and θ axis sensors, as in block 229, whereby the exact position of the hole is determined and Are written together.

If the last exact position in the column is determined as in block 223 and also in block 231 it is determined that the last hole does not belong to the last heat flux, then the nominal between rows, for example 2,6988 cm (1.0625 inches). The distance is added to the column coordinates to align the probes in the next column as in block 233. Because each column does not have the same number of holes due to the shape of the hole arrangement, the row coordinates are adjusted for each new column to position the probe in the first hole in the column, as in block 235. Then, as in block 227, a check is made to see if the hole is blocked or not present again, and positioning of the heat continues as described above.

If all the holes in the row are similarly positioned by the determination at block 231, then re-inspection is performed for the unlocated holes, ie blocked holes, at block 237. If there are no blind holes, the positioning is complete. However, if there is a blocked hole, as in block 239, the angular distance between the columns and rows is added to the matrix coordinates of the hole adjacent to the blocked hole to calculate the location of the blocked hole and store the value. If at block 241 it is determined that the positions of all blocked holes have been calculated, the positioning operation is complete.

By the device storing the correct position of the holes in the array and whether they are blocked, it is useful for carrying out subsequent work in each hole, and by printing, it is possible to confirm the hole arrangement of the tube sheet accurately.

For most of the tube hole arrangements, it has been found that determination can be made within satisfactory tolerances without having to insert a probe into each hole. Alternatively, the probe can be inserted once every third or fifth hole or once every fifth hole, in which case the position of the skipped hole is the one closest to the hole that the probe skipped. It can be calculated by adding the nominal distance between the holes to the coordinate of. For example, if the probe is inserted only into each fifth hole in a column, the position of the second hole may be determined by adding, for example, 2.6988 cm (1.0625 inch) nominal nominal distance between the row coordinates of the first hole. The position of the third hole can be determined by adding 5.3976 cm (2.125 inches), which is twice the nominal distance. Similarly, the positions of the fourth and fifth holes can also be determined by subtracting 5.3976 cm (2.125 inches) and 2.6988 cm (1.0625 inches) from the row coordinates of the holes after the sixth hole has been probed. The column coordinates will also be the same as the column coordinates of the hole used to determine the row coordinates.

By using the skipping method as in the case of the row of the column, only the fourth or fifth column of holes is probed, and the position of the skipped column can be determined by the probed hole close to the hole. If the probe is only probed in the third row and row of holes, for example in the center hole A of FIG. 12, the positions of the six holes surrounding the hole A are determined by the row and row coordinates of the measured hole A. It can be calculated by subtracting each nominal distance between them. Thus, it will be appreciated that the location of the six holes surrounding each probe hole can be determined in a similar manner.

As shown in the flow chart of FIG. The set distance at which the probe is advanced along the row as indicated by block 225 is equal to the distance between the holes to be probed, for example, three times the nominal distance between holes if only the third or fifth holes are to be probed. Or 5 times the distance. If the hole selected to be probed is blocked or not present, the nominal distance between holes is added or subtracted from the set distance at block 225 to replace the hole to be probed with the next or previous hole of the blocked or non-existing hole. If a predetermined number of holes in the column are probed, the probe is advanced by the set distance along the row at three to five times the nominal distance between the columns, as in block 233 to place the probe in the next selected column.

If it is determined in block 231 that the probe process is complete, then it is determined in block 237 whether or not an unidentified hole is present. The location of the jumped or blocked hole is calculated at block 239 in the manner described above. Once the block 241 determines the positioning of all unidentified holes, the positioning process is complete.

Once the confirmation of the correct position of each hole in the tube plate is made, insert the drill and spot facing tool holder 99 and drill the hole to remove the end and the stopper of the old tube. As mentioned above, the drill has a shoulder for spotfacing the hole. The depth of drilling is controlled by the system so that all holes 21 are spot-facing as shown by reference numeral 175 in FIG. 4 on the common plane established during the installation process, regardless of the deflection of the tube surface 10. . In addition, as described above, the computer monitors the drill speed and adjusts the drill feed rate according to the change in the hardness of the material.

The U-shaped tube 23 is inserted into the tube plate 9 from the second part so that the end of the tube is located in a corresponding hole located on both sides of the divider plate 15. The tube extends from its spot facing surface located near the corresponding aperture 21 until its end is positioned 0.64-0.32 cm (1 / 4-1 / 8 inch) below. Thereafter, in the channel head 11, the operation of the two repair machines 3 located on both sides of the divider 15 is adjusted to position the tube so that its end is coplanar with the spot facing surface, Stick in that condition.

Such an order is shown in FIG. As indicated by block 243, positioning data for the corresponding pair of holes is supplied to each repair machine 3. The left and right repair machines are then moved to position the tool holders in line with the corresponding holes as indicated in blocks 245 and 247, respectively. Thereafter, the Z-axis of both machines is raised as indicated by blocks 249 and 251 to inspect the end of the tube extending down through the tube plate. This may be achieved by a limit switch installed in the tool holder, which may be installed in a tube expansion tool as described in US Pat. No. 4,261,094.

Thereafter, the protruding length of the tube protruding below the surface of the tube plate is determined at blocks 253 and 255, respectively, the protruding length being used during the installation work. By comparison, it is determined which end of the tube is closer to the plate, and if it is determined in block 259 that the right end is closer, the platform for holding the expansion tool on the right repair machine is indicated in block 261. Ascending, so that the spot facing surface 175 and the end of the right tube are coplanar, with the expansion tool as indicated in block 263 to be held in place for subsequent welding. It is expanded and the fact that this step is completed is recorded in block 265. If it is determined in block 267 that the left end is not expanded, the left end of the tube is shown in block 269. After being located coplanar with this spot facing surface, it is expanded as indicated by block 271, and data is recorded in block 273. In this embodiment, the right end portion is expanded in block 275. The system then proceeds to block 277 to determine whether all tubes have been inflated, as shown in Figure 15, after working from the tube end closest to the tube plate, The work is carried out, so that the other end can still be raised during the upward movement of the first end so that it can still be positioned under the tube plate and is easily in place by pushing after the first end is fixed. Can be located.

If it is determined at block 277 that there are still tubes to be aligned and fixed, then the coordinates of the next hole pair are determined at block 279 and the process is repeated. The fixation of all tube ends to the tube plate is done in a similar manner. If it is determined in block 277 that the last tube is stuck, then the result is printed in block 279.

The surface to be welded is cleaned with a brush tool and welded so that it can be welded and then welded. The welds are then inspected by a closed loop television. Once the welding tool is positioned under the tube to be welded by the repair machine, the tool automatically operates to move the welding arc along a circular path around the end of the tube. Similarly, the tube guide extractor and tube expander also operate automatically once positioned. Thus, the device only needs to locate a tool that requires work in a place where work is required, and the operation of the tool is then started. Such a sequence is shown in the flow chart of FIG. As indicated by block 281, the tool is placed in the first hole where the work will be performed by the repair apparatus. The tool is then operated as indicated in block 283, and upon completion of the operation it is determined whether or not there is a hole to be worked on in block 285.

If such a hole is present, the exact coordinates of the next position determined in the positioning process enter block 287, and the above sequence is repeated until the operation is completed. As described above, the power supply to the welder is directly controlled by the welder itself, and is controlled in the same manner as described above directly above the welding tool itself.

While the embodiments of the present invention have been described so far, the present invention is not limited to such embodiments, and changes and modifications may be made within the scope of the invention as described in the appended claims.

Claims (1)

Long tool arm 63 pivotally mounted at one end with respect to a pivot point located near the center of the straight portion of the semicircular tube plate on a virtual plane parallel to the surface of the semicircular tube plate 9 of the steam generator by an electrically controlled servo machine. A method of repairing a steam generator, the method comprising: generating a control signal to rotate the arm to first, second, and third angular positions on a plane generally parallel to the surface of the tube plate. And generating an electrical signal indicative of a distance from the set point on the arm to the tube plate at the angled position, comparing the electrical signal with each other, and when the pre-electrical signal is not within a predetermined error from each other. The process of adjusting the angle between the pivot axis of the arm and the tube plate and repeating the process until the preload signal is within a predetermined error from each other. A method for repairing a steam generator, characterized in that a generated.

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