JP6150485B2 - Method and apparatus for removing stud bolt - Google Patents

Description

  The present invention relates to a method and an apparatus for removing a stud bolt used for fixing a reactor vessel lid to an upper portion of a reactor vessel body constituting the reactor vessel.

  For example, a nuclear power plant equipped with a pressurized water reactor (PWR: Pressurized Water Reactor) uses light water as a reactor coolant and a neutron moderator, and converts it into steam that does not boil over the entire core. It is sent to a generator to generate steam by heat exchange, and this steam is sent to a turbine generator to generate electricity.

  In such a nuclear power plant, the pressurized water reactor needs to periodically inspect various structures in order to ensure sufficient safety and reliability. The reactor vessel is configured such that a reactor internal structure is accommodated in a reactor vessel body, and a reactor vessel lid is fixed to the upper part. In this case, the reactor vessel main body has screw holes formed in the upper surface portion at equal intervals in the circumferential direction, and stud bolts are screwed into these screw holes. On the other hand, the reactor vessel lid has a plurality of through holes formed in the flange portion at equal intervals in the circumferential direction. The reactor vessel lid is placed on the upper surface of the reactor vessel main body so that each stud bolt penetrates into each through hole, and a nut is screwed into each stud bolt, so that The furnace vessel lid is fastened. Therefore, when carrying out periodic inspection of the reactor vessel, each nut is loosened and removed, and each stud bolt is loosened and removed from the reactor vessel body, and the reactor vessel lid is removed from the reactor vessel body. In addition, as a handling apparatus of a stud bolt, there exists a thing described in the following patent document 1. FIG.

  By the way, when removing each stud bolt from the reactor vessel body, if a foreign object enters between the screw hole of the reactor vessel body and the screw portion of the stud bolt, the screw portion is fixed and the screw of the reactor vessel body is fixed. In some cases, the stud bolt cannot be rotated and relaxed with respect to the hole. When the threaded portion of the stud bolt is fixed to the screw hole of the reactor vessel main body, if the stud bolt is forcibly rotated, not only the stud bolt but also the screw hole of the reactor vessel main body may be damaged. As a solution to this problem, for example, there is one described in Patent Document 2 below. In this stud bolt removal method described in Patent Document 2, the upper portion of the stud bolt that has been fixed to the female screw of the structure is cut and removed while leaving a length necessary for crushing, and a hole is formed in the remaining portion. A thin cylindrical state is formed, and a plurality of vertical slits extending in the circumferential direction of the stud bolt are formed on the inner surface of the thin cylindrical portion, and the thin cylindrical stud bolt is pushed from the outer peripheral surface toward the center side. By crushing, the male screw of the stud bolt is detached from the female screw of the structure, and the stud bolt is removed from the screw hole of the structure.

Japanese Patent No. 3679881 Japanese Patent Laid-Open No. 2004-042194

  In the conventional stud bolt removing method described above, when the stud bolt is fixed to the screw hole of the reactor vessel body, various devices are installed on the upper portion of the reactor vessel body after removing the reactor vessel lid from the reactor vessel body. The stud bolt is removed by this device. At this time, the reactor vessel body contains the reactor internals and is immersed in cooling water, but the operator may be exposed to radiation, and sufficient work safety is ensured. I can't say.

  The present invention solves the above-described problems, and an object of the present invention is to provide a stud bolt removing method and apparatus that can efficiently remove a stud bolt while ensuring sufficient work safety. .

  A method for removing a stud bolt of the present invention for achieving the above object is a method for removing a stud bolt for removing a stud bolt for fastening a reactor vessel lid screwed into a female screw hole of a reactor vessel body, From the step of supporting the reactor vessel lid above the reactor vessel body, the step of cutting the stud bolt from between the reactor vessel lid and the reactor vessel body, and the cutting surface of the stud bolt The method includes a step of cutting the inside of the stud bolt, and a step of removing the male screw portion of the stud bolt that has been hollowed out.

  Therefore, with the reactor vessel lid placed above the reactor vessel body, the stud bolt cutting operation, the stud bolt cutting operation, and the male screw portion removal operation are performed, and the radiation exposure from the reactor internal structure is performed. Is suppressed, and the stud bolt can be efficiently removed while ensuring sufficient work safety.

  In the stud bolt removing method of the present invention, a work space is provided between the reactor vessel body and the reactor vessel lid by supporting the reactor vessel lid via a raised spacer on the reactor vessel body. The stud bolt is cut using the work space.

  Therefore, a reactor vessel lid is always arranged above the reactor vessel body, and it is possible to suppress radiation exposure from the reactor internal structure and to prevent the reactor vessel body and the reactor vessel lid from being exposed. By using the work space in between, the stud bolt can be cut efficiently.

  In the stud bolt removing method of the present invention, the reactor vessel lid is placed on the reactor vessel main body, and a cutting tool is inserted from above the reactor vessel lid through the through hole for inserting the stud bolt, An internal cutting operation of the stud bolt is performed.

  Therefore, the reactor vessel lid is placed on the reactor vessel body, and the stud bolt is internally cut from above the reactor vessel lid by using a cutting tool. Can be suppressed.

  In the stud bolt removing method of the present invention, the cutting device is held above the reactor vessel lid using the female screw hole adjacent to the stud bolt, and the cutting tool is positioned using the shaft hole of the stud bolt. It is characterized by performing.

  Accordingly, the cutting tool is positioned from above the reactor vessel lid, and the stud bolt is cut, so that the radiation exposure from the reactor internal structure can be suppressed.

  The stud bolt removing method of the present invention is characterized in that only the top of the male screw portion of the stud bolt remains spirally by cutting the inside from the cut surface of the stud bolt.

  Therefore, only the top part of the spiral male screw part remains in the stud bolt, and the removal work can be easily performed from the female screw hole.

  In the stud bolt removing method of the present invention, after the stud bolt is removed from the female screw hole, when the female screw portion of the female screw hole has a damaged portion, the female screw portion where the damaged portion exists is partially removed. It is characterized by doing.

  Therefore, when the female screw portion of the female screw hole is partially damaged, the female screw portion having the damaged portion is partially removed, so that it is not necessary to significantly repair the female screw hole, thereby shortening the work time and reducing the work cost. Reduction can be made possible.

  In the stud bolt removing method of the present invention, after the stud bolt is removed from the female screw hole, when there is a damaged part in the female screw part of the female screw hole, a threading operation for expanding the inner diameter of the female screw part is performed. It is characterized by.

  Therefore, when the female screw portion of the female screw hole is significantly damaged, the screw working operation for expanding the inner diameter of the female screw portion is performed, so that the female screw hole can be restored with high accuracy.

  The stud bolt removing device of the present invention is a stud bolt removing device for removing a stud bolt for fastening a reactor vessel lid screwed into a female screw hole of a reactor vessel body, A cutting device capable of entering the working space between the reactor vessel lid supported above and cutting the stud bolt, and cutting from above the reactor vessel lid through the through hole for inserting the stud bolt And a cutting device capable of cutting the inside from the cut surface of the stud bolt by inserting a tool.

  Therefore, with the reactor vessel lid placed above the reactor vessel body, the stud bolt cutting operation and the stud bolt cutting operation will be performed, and the radiation exposure from the reactor internal structure will be suppressed and sufficient. Stud bolts can be efficiently removed while ensuring work safety.

  According to the stud bolt removing method and apparatus of the present invention, the reactor vessel lid is supported above the reactor vessel body, the stud bolt is cut between the reactor vessel lid and the reactor vessel body, and the stud bolt is provided. Since the internal thread is cut from the cut surface and the male screw portion of the stud bolt that has been hollowed out is removed, the stud bolt can be efficiently removed while ensuring sufficient work safety.

FIG. 1 is a perspective view showing a stud bolt cutting device in a stud bolt removing device according to an embodiment of the present invention. FIG. 2 is a plan view of the stud bolt cutting device. FIG. 3 is a longitudinal sectional view of the stud bolt cutting device. FIG. 4 is a perspective view showing a stud bolt cutting device in the stud bolt removing device. FIG. 5 is a front view showing the stud bolt cutting device. FIG. 6 is a perspective view showing the female thread portion removing device in the stud bolt removing device. FIG. 7 is a flowchart showing the stud bolt removing method of this embodiment. FIG. 8 is a schematic view showing the operation of raising the reactor vessel lid. FIG. 9 is a schematic view illustrating the work of attaching the chip dust prevention cover. FIG. 10 is a schematic diagram illustrating the mounting operation and the cutting operation of the stud bolt cutting device. FIG. 11 is a schematic diagram showing the stud bolt upper part collecting operation. FIG. 12 is a schematic diagram illustrating the mounting operation of the stud bolt cutting device. FIG. 13 is a schematic view showing the operation of attaching the trepanning tool to the stud bolt cutting device. FIG. 14 is a schematic diagram showing trepanning work by the stud bolt cutting device. FIG. 15 is a schematic diagram showing a tool change operation from a trepanning tool to a boring tool of a stud bolt cutting device. FIG. 16 is a schematic view showing boring work by a stud bolt cutting device. FIG. 17 is a schematic diagram illustrating a removal operation of the stud bolt cutting device. FIG. 18 is a schematic diagram illustrating the operation of raising the reactor vessel lid. FIG. 19 is a schematic view showing the cutting operation of the remaining stud bolt of the reactor vessel body. FIG. 20 is a schematic diagram illustrating a removal operation of the remaining stud bolt of the reactor vessel body. FIG. 21 is a schematic diagram showing nondestructive inspection of the internal thread portion of the reactor vessel main body. FIG. 22 is a schematic diagram illustrating cleaning work and visual inspection of the female thread portion of the reactor vessel main body. FIG. 23 is a schematic configuration diagram of a nuclear power plant. FIG. 24 is a longitudinal sectional view showing a pressurized water reactor.

  Exemplary embodiments of a stud bolt removing method and apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example.

  FIG. 23 is a schematic configuration diagram of a nuclear power plant, and FIG. 24 is a longitudinal sectional view showing a pressurized water reactor.

  The nuclear reactor of this embodiment uses light water as a reactor coolant and neutron moderator, and generates high-temperature and high-pressure water that does not boil over the entire core and sends this high-temperature and high-pressure water to a steam generator to generate steam by heat exchange. This is a pressurized water reactor (PWR) that generates electricity by sending this steam to a turbine generator.

  In the nuclear power plant having the pressurized water reactor of the present embodiment, as shown in FIG. 23, the reactor containment vessel 11 stores therein the pressurized water reactor 12 and the steam generator 13, and this pressurized water type. The nuclear reactor 12 and the steam generator 13 are connected via a high temperature side supply pipe 14 and a low temperature side supply pipe 15, and a pressurizer 16 is provided in the high temperature side supply pipe 14, and the low temperature side supply pipe is provided. A primary cooling water pump 17 is provided at 15. In this case, light water is used as a moderator and primary cooling water (cooling material), and the primary cooling system maintains a high pressure state of about 150 to 160 atm by the pressurizer 16 in order to suppress boiling of the primary cooling water in the core. You are in control.

  Accordingly, in the pressurized water reactor 12, light water is heated as the primary cooling water by the low-enriched uranium or MOX as the fuel (nuclear fuel), and the high temperature primary cooling water is maintained at a predetermined high pressure by the pressurizer 16. , And is sent to the steam generator 13 through the high temperature side supply pipe 14. In the steam generator 13, heat exchange is performed between the high-temperature and high-pressure primary cooling water and the secondary cooling water, and the cooled primary cooling water is returned to the pressurized water reactor 12 through the low-temperature side supply pipe 15. .

  The steam generator 13 is connected to a steam turbine 32 via a pipe 31 for supplying heated secondary cooling water, that is, steam, and a main steam isolation valve 33 is provided in the pipe 31. The steam turbine 32 includes a high-pressure turbine 34 and a low-pressure turbine 35, and a generator (power generation device) 36 is connected to the steam turbine 32. Further, the high pressure turbine 34 and the low pressure turbine 35 are provided with a moisture separation heater 37 therebetween, and a cooling water branch pipe 38 branched from the pipe 31 is connected to the moisture separation heater 37, while the high pressure turbine 34 and the moisture separation heater 37 are connected by a low-temperature reheat pipe 39, and the moisture separation heater 37 and the low-pressure turbine 35 are connected by a high-temperature reheat pipe 40.

  Further, the low-pressure turbine 35 of the steam turbine 32 includes a condenser 41. The condenser 41 is connected to a turbine bypass pipe 43 having a bypass valve 42 from the pipe 31, and is also supplied with cooling water (for example, , Seawater) is connected to a water intake pipe 44 and a drain pipe 45. The intake pipe 44 has a circulating water pump 46, and the other end portion thereof is disposed in the sea together with the drain pipe 45.

  The condenser 41 is connected to a pipe 47, and is connected to a condensate pump 48, a ground condenser 49, a condensate demineralizer 50, a condensate booster pump 51, and a low-pressure feed water heater 52. The piping 47 is connected to a deaerator 53 and is provided with a main feed water pump 54, a high-pressure feed water heater 55, and a main feed water control valve 56.

  Therefore, the steam generated by exchanging heat with the high-temperature and high-pressure primary cooling water in the steam generator 13 is sent to the steam turbine 32 (from the high-pressure turbine 34 to the low-pressure turbine 35) through the pipe 31. The turbine 32 is driven to generate power by the generator 36. At this time, the steam from the steam generator 13 drives the high-pressure turbine 34, and then the moisture contained in the steam is removed and heated by the moisture separation heater 37, and then the low-pressure turbine 35 is driven. Then, the steam that has driven the steam turbine 32 is cooled using seawater in the condenser 41 to become condensed water, and the ground condenser 49, the condensate demineralizer 50, the low pressure feed water heater 52, the deaerator 53, the high pressure It returns to the steam generator 13 through the feed water heater 55 or the like.

  In the pressurized water reactor 12 of the nuclear power plant configured as described above, as shown in FIG. 24, the reactor vessel 61 includes a reactor vessel main body 62 and its reactor so that the reactor internal structure can be inserted therein. The reactor vessel lid (upper mirror) 63 is mounted on the upper portion. The reactor vessel lid 63 is fixed to the reactor vessel body 62 by a plurality of stud bolts 64 and nuts 65 so as to be opened and closed. Yes.

  The reactor vessel main body 62 has a cylindrical shape whose upper portion can be opened by removing the reactor vessel lid 63 and whose lower portion is closed by a lower mirror 66 having a hemispherical shape. The reactor vessel body 62 is formed with an inlet nozzle (inlet nozzle) 67 for supplying light water (coolant) as primary cooling water and an outlet nozzle (exit nozzle) 68 for discharging light water at the upper part. Yes. Further, in the case of a two-loop plant, the reactor vessel main body 62 is formed with a water injection nozzle (water injection pipe stand) (not shown) separately from the inlet nozzle 67 and the outlet nozzle 68.

  In the reactor vessel main body 62, the upper core support plate 69 is fixed above the inlet nozzle 67 and the outlet nozzle 68, while the lower core support plate 70 is fixed in the vicinity of the lower mirror 66 below. Has been. The upper core support plate 69 and the lower core support plate 70 have a disk shape and are formed with a number of communication holes (not shown). The upper core support plate 69 is connected to an upper core plate 72 formed with a plurality of communication holes (not shown) below via a plurality of core support rods 71.

  In the reactor vessel main body 62, a cylindrical core tank 73 having a cylindrical shape is disposed with a predetermined gap from the inner wall surface. The core tank 73 is connected to the upper core plate 72 at the upper part and has a disk shape at the lower part. Thus, a lower core plate 74 having a plurality of communication holes (not shown) is connected. The lower core plate 74 is supported by the lower core support plate 70. That is, the core tank 73 is suspended and supported by the lower core support plate 70 of the reactor vessel main body 62.

  The core 75 is formed by an upper core plate 72, a core tank 73, and a lower core plate 74, and the core 75 has a large number of fuel assemblies 76 disposed therein. Although not shown, the fuel assembly 76 is configured by bundling a large number of fuel rods in a lattice pattern by a support lattice, and an upper nozzle is fixed to the upper end portion and a lower nozzle is fixed to the lower end portion. The core 75 has a large number of control rods 77 arranged therein. The large number of control rods 77 are combined at the upper end portion into a control rod cluster 78 that can be inserted into the fuel assembly 77. A number of control rod cluster guide tubes 79 are fixed to the upper core support plate 69 so as to pass through the upper core support plate 69, and each control rod cluster guide tube 79 has a lower end control within the fuel assembly 76. It extends to the bar cluster 78.

  The reactor vessel lid 63 constituting the reactor vessel 61 has a hemispherical upper portion and is provided with a magnetic jack control rod drive device 80 and is housed in a housing 81 that is integral with the reactor vessel lid 63. Has been. A large number of control rod cluster guide tubes 79 extend to the control rod drive device 80 at the upper end, and the control rod cluster drive shaft 82 extends from the control rod drive device 80 in the control rod cluster guide tube 79. It extends to the fuel assembly 76 and can grip the control rod cluster 78.

  The control rod driving device 80 extends in the vertical direction and is connected to the control rod cluster 78, and a control rod cluster driving shaft 82 having a plurality of circumferential grooves arranged on the surface thereof at equal pitches in the longitudinal direction. The power of the reactor is controlled by moving up and down with a magnetic jack.

  The reactor vessel main body 62 is provided with a number of instrumentation nozzles 83 penetrating the lower mirror 66, and each instrumentation nozzle 83 is connected to an inner instrumentation guide tube 84 at the upper end portion inside the reactor. On the other hand, a conduit tube 85 is connected to a lower end portion outside the furnace. Each in-core instrumentation guide tube 84 has an upper end connected to the lower core support plate 70, and upper and lower connecting plates 86 and 87 for suppressing vibration are attached. The thimble tube 88 is equipped with a neutron flux detector (not shown) capable of measuring a neutron flux, passes from the conduit tube 85 through the instrumentation nozzle 83 and the in-core instrumentation guide tube 84, and passes through the lower core plate 74. The fuel assembly 76 can be inserted through.

  Accordingly, the control rod drive device 80 moves the control rod cluster drive shaft 82 to extract a predetermined amount of the control rod 77 from the fuel assembly 76, thereby controlling the nuclear fission in the core 75 and generating the nuclear reactor by the generated thermal energy. The light water filled in the container 61 is heated, and high-temperature light water is discharged from the outlet nozzle 68 and sent to the steam generator 13 as described above. That is, the nuclear fuel constituting the fuel assembly 76 is fissioned to release neutrons, and the light water as the moderator and the primary cooling water reduces the kinetic energy of the released fast neutrons to become thermal neutrons. It is easy to cause nuclear fission and takes away the generated heat to cool. On the other hand, by inserting the control rod 77 into the fuel assembly 76, the number of neutrons generated in the reactor core 75 is adjusted, and by inserting all the control rod 77 into the fuel assembly 76, the nuclear reactor is emergency Can be stopped.

  Further, the reactor vessel 61 has an upper plenum 89 communicating with the outlet nozzle 68 above the core 75 and a lower plenum 90 formed below. A downcomer portion 91 communicating with the inlet nozzle 67 and the lower plenum 90 is formed between the nuclear reactor vessel 61 and the reactor core 73. Accordingly, the light water flows into the reactor vessel main body 62 from the inlet nozzle 67, flows down the downcomer portion 91, reaches the lower plenum 90, and is guided upward by the spherical inner surface of the lower plenum 90. Then, after passing through the lower core support plate 70 and the lower core plate 74, it flows into the core 75. The light water that has flowed into the core 75 absorbs heat energy generated from the fuel assemblies 76 constituting the core 75 to cool the fuel assemblies 76, while passing through the upper core plate 72 at a high temperature. Ascending to the upper plenum 89 and discharged through the outlet nozzle 68.

  In the pressurized water reactor 12 configured as described above, the reactor vessel 61 is provided with a reactor vessel lid 63 on the reactor vessel main body 62 and fastened by a plurality of stud bolts 64 and nuts 65. . That is, in the reactor vessel main body 62, a plurality of female screw holes 62b are formed at equal intervals in the circumferential direction on the upper surface portion of the upper flange 62a, and the lower screw portion 64a of the stud bolt 64 is screwed into each screw hole 62b. Yes. On the other hand, the reactor vessel lid 63 has a plurality of through holes 63b formed in the outer peripheral flange portion 63a at equal intervals in the circumferential direction. The reactor vessel lid 63 is placed on the upper flange 62a of the reactor vessel body 62 so that each stud bolt 64 penetrates each through hole 63b, and a nut 65 is attached to the upper threaded portion 64b of each stud bolt 64. The reactor vessel lid 63 is fastened to the upper portion of the reactor vessel main body 62 by screwing.

  Incidentally, the pressurized water reactor 12 periodically inspects various structures in order to ensure sufficient safety and reliability. In this case, it is necessary to remove the reactor vessel lid 63 from the reactor vessel main body 62 and to remove a plurality of stud bolts 64 from the reactor vessel main body 62. However, if a foreign object enters between the screw hole 62b of the reactor vessel main body 62 and the lower screw portion 64a of the stud bolt 64, the screw portion is fixed and the stud bolt 64 cannot be rotated. The stud bolt 64 cannot be removed from 62.

  In this embodiment, when the lower screw portion 64a of the stud bolt 64 is fixed to the screw hole 62b of the reactor vessel body 62, only the stud bolt 64 is cut and cut into the screw hole 62b of the reactor vessel body 62. To be removed.

  Hereinafter, the stud bolt removing device of this embodiment will be described in detail.

  1 is a perspective view showing a stud bolt cutting device in a stud bolt removing device according to one embodiment of the present invention, FIG. 2 is a plan view of the stud bolt cutting device, and FIG. 3 is a longitudinal section of the stud bolt cutting device. 4 is a perspective view showing a stud bolt cutting device in the stud bolt removing device, FIG. 5 is a front view showing the stud bolt cutting device, and FIG. 6 is a female screw portion removing device in the stud bolt removing device. It is a perspective view.

  As shown in FIG. 1, the stud bolt removing apparatus of the present embodiment enters the working space S between the reactor vessel main body 62 and the reactor vessel lid 63 supported above the reactor vessel main body 62 and inserts the stud bolt 64. As shown in FIG. 4, the cutting tool 101 can be cut from the cut surface of the stud bolt 64 by inserting a cutting tool through the through hole 63 b for inserting the stud bolt from above the reactor vessel lid 63. Cutting device 201.

  In the cutting device 101, as shown in FIGS. 1 to 3, the apparatus main body 111 has two casters 113 mounted on the left and right side portions via travel support members 112. Further, the apparatus main body 111 is provided with leg portions 114 on the left and right side portions. In this case, the apparatus main body 111 can be driven by the caster 113 by raising the leg portion 114 and lowering the caster 113, while the device body 111 is lowered by raising the caster 113 by lowering the leg portion 114. The leg portion 114 can stop at a predetermined position.

  The apparatus main body 111 has a pair of guide rails 115 that are parallel to the left and right sides. The cutting tool 116 is a band saw, and an annular cutting blade 118 is movably supported in the case 117 and can be moved by a driving device 119. One of the cutting blades 118 can be moved from the front notch 117a. The part is exposed. The cutting tool 116 is accommodated in a cover 120 having substantially the same shape as the case 117, and a part of the cutting blade 118 is exposed from the front notch 120a. The cover 120 (cutting tool 116) is disposed with the front portion (left portion in FIG. 3) inclined downward with respect to the apparatus main body 111, and a support member 121 fixed to the left and right side portions is provided for each guide. The rail 115 is supported so as to be movable. In this case, a part of the cutting blade 118 is exposed at the front of the cover 120 (cutting tool 116).

  Further, the apparatus main body 111 is provided with a tool driving device (fluid cylinder) 122 at the rear, and the tip of the driving rod 122a is connected to the cover 120 (cutting tool 116). Therefore, the cutting tool 116 can be moved forward or backward by the tool driving device 122.

  The apparatus main body 111 is provided with support plates 123 on both sides of the front portion, and each support plate 123 is formed with a positioning hole 124. When the positioning holes 124 are aligned with the female screw holes 62 b formed in the reactor vessel main body 62, the positioning of the positioning pins 125 allows the apparatus main body 111 to be fixed. Further, in the apparatus main body 111, a notch portion 126 into which the stud bolt 64 can be inserted is formed at the front end portion, and an operation member 127 operated by an operator is fixed at the rear end portion.

  The chip scattering prevention cover 131 is provided separately from the apparatus main body 111 and includes a chip scattering prevention shield 132. The chip scattering prevention shield 132 is attached to the inner side (center side) of the stud bolt 64 at the upper flange 62a of the reactor vessel main body 62, and the generated chips are generated when the stud bolt 64 is cut. It covers the main body 62 so that it does not scatter. Further, the chip scattering prevention cover 131 is provided with support plates 133 on both sides, and each support plate 133 is formed with a positioning hole 134. When the positioning holes 134 are aligned with the female screw holes 62 b formed in the reactor vessel main body 62, the positioning pins 125 are penetrated together with the positioning holes 124 of the apparatus main body 111. Fixing can be performed.

  Accordingly, the reactor vessel lid 63 is supported at the upper position by the raised spacer 401 (see FIG. 8) with respect to the reactor vessel body 62, and the work space S is provided between the reactor vessel body 62 and the reactor vessel lid 63. Secure. In this state, the chip scattering prevention cover 131 is disposed at a predetermined position, and when the apparatus main body 111 is advanced and stopped at the predetermined position, the positioning pin 125 is inserted into the reactor vessel main body 62 through the positioning holes 124 and 134. The chip scattering prevention cover 131 and the apparatus main body 111 are fixed by penetrating the female screw hole 62b. When the cutting tool 116 is operated and the cutting tool 116 is advanced by the tool driving device 122, the stud bolt 64 can be cut by the cutting blade 118. At this time, the chip scattering prevention cover 131 can prevent the generated chips from scattering. Then, after cutting the stud bolt 64, the cutting tool 116 is retracted by the tool driving device 122, the positioning pin 125 is pulled out, and the chip scattering prevention cover 131 and the apparatus main body 111 can be collected.

  In the reactor vessel main body 62, a seal ring 62c is fixed to the upper flange 62a, and the apparatus main body 111 runs on the seal ring 62c. Further, the stud bolt 64 has a shaft hole 64c formed along the shaft center therein, and a hanging tool 64e is fixed to the upper end portion via a bolt gripping bolt 64d. Therefore, when the stud bolt 64 is cut, the upper portion of the cut stud bolt 64 can be recovered by hanging and supporting the stud bolt 64 via a hanging tool 64e by a crane (not shown).

  In the cutting device 201, as shown in FIGS. 4 and 5, the base plate 211 has a pair of left and right guide tubes 212 fixed to the upper surface portion, and the guide devices 213 are supported by the guide tubes 212. The guide device 213 includes a guide rod 214 inserted into each guide tube 212, a fitting portion 215 connected to the lower portion of the guide rod 214, and a connecting rod 216 connected to the lower portion of the fitting portion 215. The support rod 217 connected to the lower part of the connection rod 216, a pair of upper and lower guide clamps 218 and 219 provided at the upper and lower ends of the support rod 217, and the column clamp 220 provided at the upper part of the guide rod 214. And have.

  The guide clamps 218 and 219 are inserted from the fitting portion 215 through the connecting rod 216 and the support rod 217 with the support rod 217 inserted into the female screw hole 62b of the reactor vessel main body 62 through the through hole 63b of the reactor vessel lid 63. By supplying water, the diameter can be increased and the inner surface of the female screw hole 62 b can be pressed to fix the guide device 213 to the reactor vessel main body 62. On the other hand, when the water is discharged, the guide clamps 218 and 219 are reduced in diameter and separated from the inner surface of the female screw hole 62b, so that the guide device 213 can be fixed to the reactor vessel main body 62. In this case, since the female screw hole 62b is provided with a female screw portion at the intermediate portion and no female screw portion is provided at the upper end portion and the lower end portion, the guide clamps 218 and 219 are provided with the female screw portion in the female screw hole 62b. The inner surface is not pressed.

  Further, the column clamp 220 can hold the guide tube 212 and fix the base plate 211 to the guide device 213 by supplying water from the outside with the guide rod 214 penetrating into the guide tube 212. On the other hand, the column clamp 220 can release the grip of the guide tube 212 by discharging water.

  The left and right guide cylinders 212 are connected by a connecting frame 221, and a processing head 222 is supported by the connecting frame 221 so as to be movable up and down, and a main shaft 223 is rotatably supported by the processing head 222. A feed motor 224 provided on the connection frame 221 is connected to the machining head 222 via the speed reduction mechanism 225 and can move the main shaft 223 up and down via the machining head 222. A rotation motor 226 provided on the connection frame 221 is connected to the main shaft 223 via the speed reduction mechanism 227 and can rotate the main shaft 223.

  Various types of tools can be freely attached to and removed from the lower end of the main shaft 223, and a positioning tool (not shown), a trepanning tool 228, a boring tool 229 (see FIG. 16), a threading tool (not shown), and the like are attached and detached. be able to.

  Accordingly, the reactor vessel lid 63 is placed on the reactor vessel main body 62 via the spacer 402. In this state, first, the guide device 213 is mounted above the reactor vessel lid 63. That is, each support rod 217 is inserted into the female screw hole 62b of the reactor vessel main body 62 through the through hole 63b of the reactor vessel lid 63, and the diameter is increased by supplying water to the guide clamps 218 and 219. Fix to the container body 62. Next, the auxiliary plate 231 is inserted through each guide rod 214, placed on the upper surface of the outer peripheral flange portion 63a of the reactor vessel lid 63, and positioning pins (not shown) are inserted and fixed in the left and right through holes 63b. .

  Subsequently, the base plate 211 and the guide cylinders 212 are inserted through the guide rods 214, and the base plate 211 is placed on the auxiliary plate 231. Here, the position of the connecting frame 221, that is, the main shaft 223 is adjusted. A positioning tool is attached to the lower end portion of the main shaft 223, and the main shaft 223 (the connecting frame 221) is moved to a position where the lower end portion of the positioning tool fits into the shaft hole 64c of the stud bolt 64. In this case, the horizontality of the base plate 211, that is, the verticality of the main shaft 223 is adjusted using a plurality of adjustment bolts (not shown). Further, the horizontal position of the base plate 211, that is, the axis of the main shaft 223 and the axis of the stud bolt 64 are adjusted using a plurality of adjustment bolts (not shown). When this adjustment operation is completed, water is supplied to the column clamp 220 to grip the guide tube 212 and fix the base plate 211 to the guide device 213.

  Then, the rotary motor 226 is driven, the main shaft 223 is driven and rotated via the speed reduction mechanism 227, the feed motor 224 is driven, and the main shaft 223 is lowered via the speed reduction mechanism 225, whereby various types mounted on the main shaft 223. Various kinds of work can be performed with these tools. That is, if the trepanning tool 228 is mounted on the main shaft 223, the trepanning process can be performed on the stud bolt 64, and if the boring tool 229 is mounted on the main shaft 223, the stud bolt 64 can be cut. When a threading tool is attached to the main shaft 223, it is possible to perform a threading process for increasing the size of the female thread hole 62b of the reactor vessel main body 62.

  Further, the stud bolt removing device of the present embodiment has a female screw portion removing device 301. When the stud screw 64 is removed from the female screw hole 62b of the reactor vessel main body 62 and the female screw part of the female screw hole 62b has a damaged part, the female screw part removing device 301 removes the female screw part having the damaged part. It is partly removed.

  In the female screw part removing device 301, as shown in FIG. 6, the guide tube 311 has a cylindrical shape, extends from the reactor vessel lid 63 through the through hole 63b to the female screw hole 62b of the reactor vessel main body 62, and has an upper end. A base 312 mounted on the outer peripheral flange portion 63a of the reactor vessel lid 63 is attached to this portion, and a screw portion 313 is formed on the inner surface of the lower end portion. The rotating cylinder 314 has a cylindrical shape and is rotatably supported inside the guide cylinder 311. The rotating cylinder 314 extends downward in the guide cylinder 311, and a rotating disk 316 having a rotating handle 315 at the upper end is fixed, and a screw that engages with the threaded portion 313 on the outer surface of the lower end. A portion 317 is formed. The rotating shaft 318 extends downward in the rotating cylinder 314 and is rotatably supported by the rotating disk 316. The rotary shaft 318 has a rotating plate 320 having a pressing handle 319 at the upper end, a support plate 322 provided at the lower end via a pressing mechanism 321, and a cutting tool (for example, a grinder) on the support plate 322. ) A drive motor 324 having 323 is attached. In this case, the cutting tool 323 is disposed so as to protrude downward from the guide cylinder 311 and the rotary cylinder 314.

  Accordingly, when the driving motor 324 is driven to drive and rotate the cutting tool 323, and the rotating disk 320 is rotated by the pressing handle 319 in this state, the rotational force is transmitted to the pressing mechanism 321 via the rotating shaft 318, and cutting is performed. The tool 323 is moved outward in the radial direction in the female screw hole 62b of the reactor vessel main body 62 and pressed against the top of the female screw portion. When the rotating disk 316 is rotated by the rotation handle 315 and the rotating cylinder 314 is rotated, the rotating cylinder 314 is raised while rotating with respect to the guide cylinder 311 by the screw portions 313 and 317. That is, the cutting tool 323 can be moved along the top of the female screw portion in the female screw hole 62b by adjusting the pitch of the screw portions 313 and 317 to the pitch of the female screw hole 62b. Therefore, the internal thread portion where the damaged portion exists can be partially removed by the cutting tool 323.

  The stud bolt removing method of the present embodiment is performed using the cutting device 101 and the cutting device 201 as the stud bolt removing device of the above-described embodiment, and the reactor vessel is disposed above the reactor vessel main body 62. The step of supporting the lid 63, the step of cutting the stud bolt 64 from the work space S between the reactor vessel lid 63 and the reactor vessel body 62, and the inside of the stud bolt 64 are cut from the cut surface of the stud bolt 64. And a step of removing the male thread portion of the stud bolt 64 from which the interior is hollowed out.

  Here, the method for removing the stud bolt of this embodiment will be described in detail with reference to the flowchart of FIG. 7 and the schematic views of FIGS.

  FIG. 7 is a flowchart showing a method for removing a stud bolt of the present embodiment, FIG. 8 is a schematic diagram showing an operation for raising a reactor vessel lid, and FIG. 9 is a schematic diagram showing an operation for attaching a chip scattering prevention cover. FIG. 10 is a schematic diagram showing the mounting operation and cutting operation of the stud bolt cutting device, FIG. 11 is a schematic diagram showing the stud bolt upper collecting operation, and FIG. 12 is a schematic diagram showing the mounting operation of the stud bolt cutting device. 13 is a schematic diagram showing the mounting operation of the trepanning tool to the stud bolt cutting device, FIG. 14 is a schematic diagram showing the trepanning operation by the stud bolt cutting device, and FIG. 15 is from the trepanning tool of the stud bolt cutting device to the boring tool. FIG. 16 is a schematic diagram showing a boring operation by a stud bolt cutting device, and FIG. 17 is a stud bolt cutting. FIG. 18 is a schematic diagram showing the raising operation of the reactor vessel lid, FIG. 19 is a schematic diagram showing the cutting operation of the remaining stud bolt of the reactor vessel body, and FIG. FIG. 21 is a schematic diagram showing the removal operation of the stud bolt remaining portion of the reactor vessel body, FIG. 21 is a schematic diagram showing nondestructive inspection of the female screw portion of the reactor vessel main body, and FIG. It is a schematic diagram showing cleaning work and visual inspection.

  As shown in FIG. 7, first, in step S <b> 11, a bolt attaching / detaching device (not shown) is mounted on the upper portion of the reactor vessel 61, and the nut 65 is rotated and loosened to remove it from the stud bolt 64. Next, in step S <b> 12, the stud bolt 64 is rotated and relaxed to be extracted from the reactor vessel main body 62. At this time, in step S13, it is determined whether or not the stud bolt 64 is fixed. If it is determined that the stud bolt 64 is not fixed (No), the process ends without doing anything. On the other hand, if it is determined that the stud bolt 64 is firmly attached (Yes), the stud bolt 64 cannot be rotated and removed from the reactor vessel main body 62. Implement the method. In this case, all the removable nuts 65 and stud bolts 64 are removed in advance.

  As shown in FIGS. 7 and 8, in step S <b> 14, the reactor vessel lid 63 is lifted by a crane (not shown), and a raised spacer 401 is inserted between the reactor vessel body 62 and the reactor vessel lid 63. The reactor vessel lid 63 is supported above the reactor vessel body 62, and a work space S is secured between the reactor vessel body 62 and the reactor vessel lid 63. In this case, a plurality of (for example, three) raising spacers 401 are inserted at equal intervals in the circumferential direction between the reactor vessel main body 62 and the reactor vessel lid 63.

  As shown in FIGS. 7 and 9, in step S15, the chip scattering prevention cover 131 is disposed at a predetermined position in the reactor vessel main body 62 using the work space S, and as shown in FIG. The main body 111 moves forward on the seal ring 62c and the upper flange 62a of the reactor vessel main body 62, and stops at a predetermined position. Here, as shown in FIG. 2, the chip scattering prevention cover 131 and the apparatus main body 111 are connected to the reactor vessel by inserting the positioning pins 125 into the female screw holes 62b of the reactor vessel main body 62 through the positioning holes 124 and 134, respectively. Fix to the main body 62. Then, as shown in FIGS. 7 and 10, in step S <b> 16, the cutting tool 116 is operated, the cutting tool 116 is advanced by the tool driving device 122, and the stud bolt 64 is cut by the cutting blade 118. The cutting position of the stud bolt 64 is a position protruding a predetermined length from the upper surface of the upper flange 62a in the reactor vessel main body 62.

  When the cutting of the stud bolt 64 is completed, as shown in FIG. 7, in step S17, the cutting tool 116 is retracted by the tool driving device 122, the positioning pin 125 is pulled out, and the chip scattering prevention cover 131 and the apparatus main body 111 are removed. to recover. Further, as shown in FIG. 11, the stud bolt 64 is suspended and supported by a crane (not shown) via a hanging tool 64e, so that the cut stud bolt upper portion 64A is recovered as it is, and the reactor vessel main body 62 is recovered. The stud bolt lower part 64B after cutting remains in the female screw hole 62b.

  As shown in FIGS. 7 and 12, in step S18, the reactor vessel lid 63 is lifted by a crane, and the raising spacer 401 inserted between the reactor vessel body 62 and the reactor vessel lid 63 is removed. Instead, the reactor vessel lid 63 is placed on the reactor vessel main body 62 by inserting the spacer 402. In this case, as shown in FIG. 4, a spacer 402 that also serves as a chip scattering prevention jig (opening) is inserted at the position of the stud bolt 64 to be removed. 7 and 12, in step S19, first, the guide device 213 is mounted above the reactor vessel lid 63 and fixed to the reactor vessel main body 62 using the guide clamps 218 and 219. . Next, the auxiliary plate 231 is inserted through each guide rod 214 and fixed. Subsequently, the base plate 211 and the guide cylinders 212 are inserted through the guide rods 214 and placed on the auxiliary plate 231. After the position of the main shaft 223, that is, the cutting device 201 is adjusted in step S20, The base plate 211 is fixed to the guide device 213 by the column clamp 220.

  When the cutting device 201 is mounted at a predetermined position in the upper part of the reactor vessel lid 63 in this way, as shown in FIGS. 7 and 13, the trepanning tool 228 is mounted on the main shaft 223 in step S21. 14, the trepanning tool 228 performs trepanning on the stud bolt lower part 64 </ b> B remaining in the female screw hole 62 b of the reactor vessel main body 62 to cut the stud bolt 64. That is, the trepanning tool 228 is driven and rotated together with the main shaft 223, and is lowered so that the stud bolt lower portion 64B is trepanned from the upper end cutting surface by the trepanning tool 228. Then, as shown in FIG. 15, the stud bolt lower part 64B is separated into an inner core part 64C and an outer remaining cylinder 64D. Then, after removing the trepanning tool 228 from the cutting device 201, the core portion 64C is extracted from the remaining cylinder 64D using the core extraction jig 403, and then the boring tool 229 is mounted on the spindle 223 in step S22. .

  As shown in FIGS. 7 and 16, in step S23, the remaining portion of the bolt, that is, the inside of the remaining cylinder 64D is cut by the boring tool 229. That is, the boring tool 229 is driven to rotate together with the main shaft 223 and is lowered, whereby the inner peripheral surface of the remaining cylinder 64D is cut by the boring tool 229. When the remaining cylinder 64D is cut to a predetermined thickness, as shown in FIGS. 7 and 17, the cutting device 201 mounted on the upper portion of the reactor vessel lid 63 is removed in step S24.

  As shown in FIGS. 7 and 18, in step S <b> 25, the reactor vessel lid 63 is lifted by a crane, the spacer 402 is removed from between the reactor vessel body 62 and the reactor vessel lid 63, and the raised spacer 401 is used instead. Is inserted, the reactor vessel lid 63 is supported above the reactor vessel body 62, and a work space S is secured between the reactor vessel body 62 and the reactor vessel lid 63. 7 and 19, in step S26, the inside of the remaining cylinder 64D is further cut using a cutting tool (eg, a flap wheel) 404. Then, as shown in FIG. 20, the remaining cylinder 64 </ b> D remains only in the female screw portion in the female screw hole 62 b of the reactor vessel main body 62. That is, the remaining cylinder 64 </ b> D becomes a spiral remaining portion 64 </ b> E in which only the top portion of the male thread portion of the stud bolt 64 remains in a spiral shape, and this spiral remaining portion 64 </ b> E is recovered using a removal tool (for example, a flyer) 405.

  As shown in FIG. 7, in step S <b> 27, it is confirmed by visual inspection or nondestructive inspection whether or not there is a damaged portion in the internal thread portion of the internal thread portion 62 b of the reactor vessel main body 62. Here, if there is no damaged part in the internal thread part in the internal thread part 62b (No), the process proceeds to step S31. On the other hand, if there is a damaged portion in the female screw portion of the female screw portion 62b (Yes), it is examined in step S28 whether it is necessary to increase the size of the female screw portion 62b. That is, when there are a number of damaged parts in the female screw part in the female screw part 62b, partial repair cannot be performed.

  Here, if it is determined that there is a large number of damaged portions in the internal thread portion of the internal thread portion 62b and partial repair cannot be performed and it is necessary to increase the size of the internal thread portion 62b (Yes), the internal thread portion is determined in step S29. The size-up process of 62b is executed. On the other hand, if it is determined (No) that the female threaded portion of the female threaded portion 62b does not have many damaged portions and can be partially repaired (No), a partial repairing operation of the female threaded portion 62b is executed in step S30.

  Specifically, the size of the internal thread portion 62b is increased by attaching a cutting device 201 to the upper portion of the reactor vessel lid 63, attaching a bolt hole cutting tool (not shown) to the main shaft 223, and inserting into the internal thread hole 62b of the reactor vessel main body 62. On the other hand, the bolt hole (female screw hole 62b) is expanded (expanded) by cutting so as to remove the female screw (original thread), and then a screw tool (tapping tool) (not shown) is attached to the main shaft 223. The new thread female thread is formed in the female thread hole 62b of the furnace vessel main body 62, thereby increasing the size of the thread. That is, the threading operation for expanding the inner diameter of the female screw portion is performed by processing the surface of the female screw portion so that the damaged portion is completely removed in the female screw hole 62b of the reactor vessel main body 62.

  On the other hand, the partial repair work of the female screw part 62 b is performed using the female screw part removing device 301. That is, as shown in FIG. 6, the cutting tool 323 is driven to rotate and moves in the circumferential direction while pressing against the top of the damaged female screw portion in the female screw hole 62b. The internal thread portion to be removed is partially removed.

  Then, as shown in FIGS. 7 and 21, in step S31, a nondestructive inspection is performed on the female screw hole 62b of the reactor vessel body 62, and as shown in FIGS. 7 and 22, in step S32, The reactor vessel lid 63 is lifted by a crane, the raising spacer 401 is removed from between the reactor vessel body 62 and the reactor vessel lid 63, and the reactor vessel lid 63 is placed on the reactor vessel body 62. Thereafter, in step S32, the internal thread hole 62b is cleaned by a cleaning device (not shown). In step S33, the internal thread hole 62b is visually inspected, and all the operations are completed.

  As described above, in the stud bolt removing method according to the present embodiment, the step of supporting the reactor vessel lid 63 above the reactor vessel body 62 and the space between the reactor vessel lid 63 and the reactor vessel body 62 are described. The step of cutting the stud bolt 64 from, the step of cutting the inside of the stud bolt 64 from the cut surface of the stud bolt 64, and the step of removing the male thread portion of the stud bolt 64 from which the inside is cut out. .

  Therefore, in a state where the reactor vessel lid 63 is disposed above the reactor vessel main body 62, the cutting operation of the stud bolt 64, the cutting operation of the stud bolt 64, and the removing operation of the male screw portion are performed. Thus, the stud bolt 64 can be efficiently removed after the radiation exposure due to the radiation is suppressed and sufficient work safety is ensured.

  In the stud bolt removing method of the present embodiment, the reactor vessel lid 63 is supported on the reactor vessel body 62 via the raised spacer 401, so that the reactor vessel body 62 and the reactor vessel lid 63 are interposed between them. A work space S is secured, and the work space S is used to cut the stud bolt 64. Therefore, the reactor vessel lid 63 is always disposed above the reactor vessel main body 62, so that it is possible to suppress exposure to radiation from the internal structure of the reactor, and the reactor vessel main body 62 and the reactor vessel By using the work space S between the lid 63 and the lid 63, the stud bolt 64 can be cut efficiently.

  In the stud bolt removing method of this embodiment, the reactor vessel lid 63 is placed on the reactor vessel body 62, and a cutting tool is inserted from above the reactor vessel lid 63 through the through hole 63b of the stud bolt 64, An internal cutting operation of the stud bolt 64 is performed. Accordingly, the reactor vessel lid 63 is placed on the reactor vessel main body 62, and the internal cutting operation of the stud bolt 64 is performed from above the reactor vessel lid 63 using a cutting tool, thereby reducing the internal structure of the reactor vessel. Can be suppressed from radiation exposure.

  In the stud bolt removing method of this embodiment, the cutting device 201 is held above the reactor vessel lid 63 using the female screw hole 62b adjacent to the stud bolt 64, and the cutting tool is used using the shaft hole 64c of the stud bolt 64. Positioning is performed. Therefore, the cutting tool is positioned from above the reactor vessel lid 63 and the stud bolt 64 is cut, so that the radiation exposure from the reactor internal structure can be suppressed.

  In the stud bolt removing method of the present embodiment, the inside of the stud bolt 64 is cut from the cut surface, so that only the top of the male screw portion of the stud bolt 64 remains spirally. Therefore, only the top part (spiral remaining part 64E) of the helical male screw part remains in the stud bolt 64, and the removal work can be easily performed from the female screw hole 62b.

  In the stud bolt removing method of the present embodiment, after the stud bolt 64 is removed from the female screw hole 62b of the reactor vessel main body 62, when the female screw portion of the female screw hole 62b has a damaged portion, the female screw portion where the damaged portion exists. Is partially removed. Therefore, when the female screw portion of the female screw hole 62b is partially damaged, the female screw portion having the damaged portion is partially removed, so that the female screw hole 62b is not required to be greatly repaired, and the working time can be shortened. Cost can be reduced.

  In the stud bolt removing method of this embodiment, after the stud bolt 64 is removed from the female screw hole 62b of the reactor vessel main body 62, when the female screw portion of the female screw hole 62b has a damaged portion, the inner diameter of the female screw portion is enlarged. The screw machining work is performed. Therefore, when the internal thread portion of the internal thread hole 62b is significantly damaged, the threading operation for expanding the internal diameter of the internal thread portion is performed, so that the internal thread hole can be restored with high accuracy.

  Further, in the stud bolt removing apparatus of the present embodiment, the stud bolt 64 can be cut by entering from the work space S between the reactor vessel main body 62 and the reactor vessel lid 63 supported above the reactor vessel main body 62. And a cutting device 201 capable of inserting a cutting tool from above the reactor vessel lid 63 through the through hole 63b of the stud bolt 64 and cutting the inside from the cut surface of the stud bolt 64.

  Accordingly, the cutting operation of the stud bolt 64 and the cutting operation of the stud bolt 64 are performed in a state in which the reactor vessel lid 63 is disposed above the reactor vessel main body 62, and the radiation exposure from the reactor internal structure is suppressed. Thus, the stud bolt 64 can be efficiently removed while ensuring sufficient work safety.

  In the embodiment described above, the cutting device includes a step of cutting the stud bolt 64 from between the reactor vessel lid 63 and the reactor vessel main body 62 and a step of cutting the inside from the cut surface of the stud bolt 64. Although it performed by 101 and the cutting device 201, the process of removing the external thread part of the stud bolt 64 by which the inside was hollowed may be performed by the apparatus.

  Further, although the stud bolt removing method and apparatus of the present invention have been described as applied to the reactor vessel 61 of the pressurized water reactor 12, it may be applied to a boiling water reactor.

61 Reactor vessel 62 Reactor vessel body 62a Upper flange 62b Female screw hole 63 Reactor vessel lid 63a Outer peripheral flange portion 63b Through hole 64 Stud bolt 64a Lower screw portion 64b Upper screw portion 64A Stud bolt upper portion 64B Stud bolt lower portion 64C Core portion 64D Remaining tube 64E Spiral remaining portion 65 Nut 101 Cutting device 111 Device body 116 Cutting tool 122 Tool drive device 131 Chip scattering prevention cover 201 Cutting device 211 Base plate 212 Guide tube 213 Guide device 218, 219 Guide clamp 220 Column clamp 223 Main shaft (Cutting) tool)
228 Trepanning tool 229 Boring tool 301 Female thread removal device

Claims (6)

A stud bolt removing method for removing a stud bolt for fastening a reactor vessel lid screwed into a female screw hole of a reactor vessel main body,
Supporting the reactor vessel lid via a raised spacer on the reactor vessel body, and securing a working space between the reactor vessel body and the reactor vessel lid ;
Cutting the stud bolt from between the reactor vessel main body and the reactor vessel lid using the work space ; and
Placing the reactor vessel lid on the reactor vessel body, and cutting the inside of the stud bolt from the cut surface of the stud bolt through the stud bolt insertion hole from above the reactor vessel lid And
Removing the external threaded portion of the stud bolt with the interior hollowed out;
A method for removing a stud bolt, comprising: The cutting tool is held above the reactor vessel lid using the female screw hole adjacent to the stud bolt, and the cutting tool for cutting the inside of the stud bolt is positioned using the shaft hole of the stud bolt. The method for removing a stud bolt according to claim 1. 3. The method for removing a stud bolt according to claim 1 , wherein only the top of the male screw portion of the stud bolt remains spirally by cutting the inside from the cut surface of the stud bolt. 4. After the stud bolt is removed from the female screw hole, when there is a damaged portion on the internal thread portion of the female screw hole, claim 1, characterized in that the partial removal of the female thread the injury portion is present 4. The method for removing a stud bolt according to any one of 3 above. After the stud bolt from the female screw hole is removed, the case is damaged portion with the female screw portion of the female screw hole, of claims 1 to 3, characterized in that the thread cutting work to expand the inner diameter of the female screw portion The stud bolt removing method according to any one of the above. In the stud bolt removing device for removing the stud bolt for fastening the reactor vessel lid screwed into the female screw hole of the reactor vessel body ,
A cutting device that enters the working space between the reactor vessel main body and the reactor vessel lid that is raised and supported above, and cuts the stud bolt;
A cutting device that inserts a cutting tool from above the reactor vessel lid placed on the reactor vessel body through the stud bolt insertion through-hole and cuts the inside from the cut surface of the stud bolt;
A device for removing a stud bolt, comprising: