Bottom-component detachment apparatus and method of using the same

Abstract

To provide a lower component attaching / detaching device capable of easily attaching a spool piece to a main body of a control rod drive mechanism.SOLUTION: And a push-up mechanism 14 that pushes up and holds the spool piece 32a to a height at which the spool piece 32a can be attached to the drive mechanism body 31 of the control rod drive mechanism 3 in a case where the spool piece 32a that can be included in the control rod drive mechanism 3 that drives the control rod cannot be held by the lifting and lowering mechanism 11 due to the expansion and contraction of the plurality of fluid pressure cylinders 11a.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a lower component detachment device that includes a jig that holds the bottom of a spool piece of a lower component located at the bottom of a drive mechanism body in order to detach the spool piece, and a method for using the lower component detachment device. [Background technology]

[0002] In recent years, advanced boiling water reactors (ABWRs) have adopted an electrically driven fine motion control rod drive mechanism (FMCRD: Fine Motion Control Rod Drive mechanism), which is equipped with a drive mechanism body, motor unit, motor bracket, and spool piece and enables fine control rod movement.

[0003] This improved control rod drive mechanism is removed from the bottom of the reactor pressure vessel for maintenance and inspection during periodic inspections of the reactor, and is then reattached to the bottom of the reactor pressure vessel.

[0004] Since the installation and removal of this advanced control rod drive mechanism is performed in a location with a high level of radiation, it must be completed in a short time. To address this, Patent Document 1 discloses a lower component installation and removal device for installing and removing the motor bracket, motor unit, and spool piece, which are components located at the bottom of the drive mechanism body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-176419 Summary of the Invention [Problem to be solved by the invention]

[0006] The lower component removal device in Patent Document 1 uses multiple pneumatic cylinders (multi-stage cylinders) to lift the motor bracket, motor unit, and spool piece, which are held by jigs, to positions where they can be removed and installed. Pneumatic cylinders allow for a more compact lifting mechanism than those that use electricity or hydraulics, making them suitable for use in the narrow environments where lower component removal and installation work is performed.

[0007] The spool piece, one of the lower components, is used to position the control rods within the control rod drive mechanism. Therefore, when attaching the spool piece to the drive mechanism body, the spool piece must be held in place while the load applied from the control rod to the spool piece is supported by a pneumatic cylinder.

[0008] However, the load applied to the spool piece from the control rod includes the hydraulic head pressure of the cooling water in the pressure vessel applied via the control rod, and therefore can be significantly larger than the load applied to the motor unit or motor bracket, and may exceed the support capacity of the pneumatic cylinder. Therefore, in the lower component installation / removal device of Patent Document 1, when attaching the spool piece to the drive mechanism body, the multiple pneumatic cylinders may not be able to support the load applied to the spool piece from the control rod. In other words, depending on the load applied to the spool piece, the pneumatic cylinders may not be able to hold the spool piece at a height that allows it to be attached to the body of the control rod drive mechanism, and the spool piece may not be able to be attached to the drive mechanism body.

[0009] An object of the present invention is to provide a lower component installation / removal device that, when installing a spool piece in the drive mechanism body, allows a plurality of multi-stage cylinders to hold the spool piece at a height that allows the spool piece to be installed in the body of the control rod drive mechanism. [Means for solving the problem]

[0010] The present application includes multiple means for solving the above-mentioned problems. To cite one example, the lower component removal device of the present invention includes a lifting mechanism that raises and lowers a spool piece that may be included in a control rod drive mechanism that drives a control rod by extending and contracting a plurality of fluid pressure cylinders, and a push-up mechanism that, when the lifting mechanism cannot hold the spool piece at a height that allows it to be attached to the main body of the control rod drive mechanism, pushes up and holds the spool piece to that height. [Effects of the Invention]

[0011] According to the present invention, even if the load applied from the control rod prevents the multiple multi-stage cylinders from pushing the spool piece up to a height at which it can be attached to the drive mechanism body, the push-up mechanism can push the spool piece up to that height and hold it there, making it easy to attach the spool piece to the body of the control rod drive mechanism. Problems, configurations, and effects other than those described above will become apparent from the description of the following embodiments. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 10 is a schematic side view showing a state in which the lower component installation / removal device according to the first embodiment of the present invention is unable to use the lifting mechanism to push up and hold the spool piece of the lower component to a height at which it can be attached to the main body of the control rod drive mechanism, and instead uses the push-up mechanism to push up and hold the spool piece to that height. [Figure 2] FIG. 1 is an exploded view of the lower components of the control rod drive mechanism. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. 10 is a schematic perspective view showing a state in which a spool piece holding jig is fixed to the upper ends of a plurality of retracted fluid pressure cylinders and the spool piece is held by the spool piece holding jig in the lower component installation and removal device according to the first embodiment of the present invention. [Figure 6]FIG. 10 is an enlarged side view of a spool piece holding jig fixed to the upper ends of multiple retracted fluid pressure cylinders of the lower component installation and removal device according to the first embodiment, and a spool piece held by the spool piece holding jig. [Figure 7] 3 is a schematic side view showing a state in which a spool piece is raised by a lifting mechanism in the lower component installation and removal device according to the first embodiment of the present invention. FIG. [Figure 8] FIG. 10 is a perspective view of a first jig fixed to the upper ends of two retracted fluid pressure cylinders, a second jig placed on the first jig, and a motor bracket held by the second jig. [Figure 9] FIG. 10 is a perspective view of a first jig fixed to the upper ends of two retracted fluid pressure cylinders and a motor unit held by the first jig. [Figure 10] FIG. 10 is a schematic perspective view showing a state in which the lifting mechanism cannot hold the spool piece at a height at which it can be attached to the drive mechanism body, and the push-up mechanism pushes the spool piece up to that height and holds it there, in the lower component removal device according to the first embodiment of the present invention. [Figure 11] 3 is a schematic side view of a push-up mechanism in the lower component installation and removal device according to the first embodiment of the present invention. FIG. [Figure 12] 2 is a schematic side view showing an enlarged view of a push-up part of a push-up mechanism 14 in the lower component installation and removal device according to the first embodiment of the present invention. FIG. [Figure 13] FIG. 10 is a schematic perspective view showing a state in which the lifting mechanism cannot hold the spool piece at a height at which it can be attached to the drive mechanism body, and the push-up mechanism pushes the spool piece up to that height and holds it there, in a lower component removal device according to a second embodiment of the present invention. [Figure 14] FIG. 10 is a side view of a torque wrench installation jig for a lower component installation and detachment device according to a second embodiment of the present invention. [Figure 15] FIG. 10 is a perspective view of a torque wrench installation jig for a lower component installation and removal device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, the configuration and operation of a lower component installation and removal device according to first and second embodiments of the present invention will be described with reference to the drawings.

[0014] (First embodiment) FIG. 1 is a schematic side view showing a state in which the lower component installation / removal device according to the first embodiment of the present invention is unable to use the lifting mechanism to push up and hold the spool piece of the lower component to a height at which it can be attached to the main body of the control rod drive mechanism, and instead uses the push-up mechanism to push up and hold the spool piece to that height.

[0015] The lower component detachment device 1 is a device for detaching a lower component 32 of a control rod drive mechanism 3 provided in the lower part of a reactor pressure vessel 2, and will be described in detail later.

[0016] The reactor pressure vessel 2, with the control rod drive mechanism 3 installed at the bottom, is a cylindrical steel structure that houses the fuel assemblies, and is installed, for example, on a pedestal space 5, which is a cylindrical space surrounded by a pedestal 4.

[0017] The pedestal 4 is a foundation that supports the reactor body in the reactor containment vessel of the advanced boiling water reactor. A plurality of control rod housings 21 protrude downward from the bottom of the reactor pressure vessel 2.

[0018] The control rod drive mechanism 3 is a device that controls nuclear fission by inserting and removing the control rods, which are located in the center of the fuel assemblies, into and from the reactor core. Under normal circumstances, the control rod drive mechanism 3 inserts and removes the control rods into the reactor core using the power of the motor unit 32c, which will be described later. On the other hand, in the event of an abnormality, the control rod drive mechanism 3 inserts the control rods into the reactor core in one go using water pressure.

[0019] The control rod drive mechanism 3 includes a drive mechanism body 31 which is the main body of the control rod drive mechanism, and a lower component 32 .

[0020] The drive mechanism body 31 is a component that grips and moves the control rod and is housed within the control rod housing 21 , and the lower end of the drive mechanism body 31 is flange-fastened to the lower part of the control rod housing 21 .

[0021] The lower component 32 is a plurality of components provided below the drive mechanism main body 31. Fig. 2 is an exploded view of the lower component 32 of the control rod drive mechanism 3. As shown in Fig. 2, the lower component 32 includes a spool piece 32a, a motor bracket 32b, and a motor unit 32c.

[0022] Fig. 3 is a perspective view of spool piece 32a. Spool piece 32a is a component that transmits the rotational force generated by motor unit 32c to drive mechanism body 31 and positions the control rod. As shown in Fig. 3, a flange portion 32aa is provided at the upper end of spool piece 32a. Furthermore, flange portion 32aa is provided with a plurality of (eight in this embodiment) through-holes 32ab that penetrate vertically.

[0023] Connecting parts (preferably bolts) are inserted into the plurality of through holes 32ab from below and screwed into bolt holes (not shown) provided on the underside of the flange of the drive mechanism body 31. In this way, the spool piece 32a is connected to the drive mechanism body 31.

[0024] 2, the motor bracket 32b is a cylindrical component that connects the spool piece 32a and the motor unit 32c, and includes a motor bracket main body 32ba and a flange portion 32bc. A through-hole (not shown) is provided in the center of the motor bracket main body 32ba for inserting the shaft 32ca that protrudes from the motor unit 32c. The motor bracket main body 32ba also has a plurality of through-holes 32bb that penetrate vertically, and a plurality of bolt holes 32bd in the underside of the flange portion 32bc.

[0025] Connecting parts (preferably bolts) are inserted from below into the multiple through holes 32bb of the motor bracket body 32ba and screwed into bolt holes 32ac provided in the underside of the spool piece 32a, thereby connecting the motor bracket 32b to the spool piece 32a.

[0026] Fig. 4 is a perspective view of motor unit 32c. Motor unit 32c is a component that houses an electric motor serving as a drive source, and as shown in Fig. 4, shaft 32ca, serving as an output shaft, protrudes from the upper end surface. A flange portion 32cb is provided on the upper portion of motor unit 32c, and multiple through-holes 32cc are provided in flange portion 32cb, which penetrates vertically.

[0027] A connecting part (preferably a bolt) is inserted into each of the through holes 32cc from below and screwed into one of the bolt holes 32bd provided in the underside of the flange portion 32bc of the motor bracket 32b, thereby connecting the motor unit 32c to the motor bracket 32b.

[0028] 1, a rail 6 is provided below the lower component installation / removal device 1 to support the movement of the lower component installation / removal device 1. A platform 7 is also provided below the rail 6, which can be remotely controlled to rotate around a vertical axis.

[0029] The lower component attachment / detachment device 1 includes a lifting mechanism 11 that lifts and lowers a spool piece 32a that may be included in a control rod drive mechanism 3 that drives a control rod by expanding and contracting a plurality of fluid pressure cylinders.

[0030] As shown in FIG. 1, the lifting mechanism 11 includes a plurality of (two in this embodiment) fluid pressure cylinders 11a and a support plate 11b that supports the plurality of fluid pressure cylinders 11a.

[0031] The fluid pressure cylinder 11a is a device that converts fluid pressure into mechanical force and expands and contracts in the vertical direction. In this embodiment, the fluid pressure cylinder 11a expands and contracts directly below the reactor pressure vessel 2 and is used for work that requires positional accuracy, so a water pressure cylinder is preferable.

[0032] Furthermore, since the lower component 32 is provided at a high place and its inspection is performed by lowering it from a high place to a low place, it is preferable that the stroke of the fluid pressure cylinder 11a is long. Therefore, it is preferable that the fluid pressure cylinder 11a is a multi-stage cylinder.

[0033] The support plate 11b is a plate-like member to which the lower portions of the plurality of fluid pressure cylinders 11a are fixed and which supports the plurality of fluid pressure cylinders 11a standing in the vertical direction. The support plate 11b can slide and rotate by a slide table 13e and a rotary table 13f, which will be described later.

[0034] FIG. 5 is a schematic perspective view showing the state in which the spool piece holding jig 12 is fixed to the upper ends of multiple retracted fluid pressure cylinders 11a in the lower component installation and removal device 1 according to this embodiment, and the spool piece 32a is held by the spool piece holding jig 12.

[0035] As shown in FIG. 5, a spool piece holding jig 12 is preferably fixed to the upper ends of a plurality of fluid pressure cylinders 11a.

[0036] Figure 6 is an enlarged side view of the spool piece holding jig 12 fixed to the upper ends of multiple retracted fluid pressure cylinders 11a of the lower component removal and installation device 1 of this embodiment, and the spool piece 32a held by the spool piece holding jig 12.

[0037] 5 and 6, the spool piece holding jig 12 is a jig that holds the spool piece 32a of the lower component 32. As shown in FIGS. 5 and 6, the spool piece holding jig 12 preferably includes an upper plate 12a that is connected to the upper part of the lifting mechanism 11 (two fluid pressure cylinders 11a) and has a hole 12ab into which the spool piece 32a is inserted, a lower plate 12c that is provided below the upper plate 12a and is connected to the upper plate 12a via a plurality of rod-shaped members 12b to support the spool piece 32a, and a plurality of bolt wrenches 12d that are rotatably attached to the lower plate 12c in the circumferential direction and that tighten or loosen a plurality of bolts 32ad that connect the spool piece 32a to the drive mechanism main body 31. The number of bolts 32ad and bolt wrenches 12d is preferably the same as the number of through holes 32ab formed in the flange portion 32aa of the spool piece 32a, and is eight in this embodiment.

[0038] The upper plate 12a is preferably a plate-like member fixed to the upper end of the fluid pressure cylinder 11a by, for example, a bolt, and is preferably a circular plate with a fixing portion 12aa (see FIG. 5) fixed by the bolt protruding radially outward. Also, as shown in FIG. 5, a hole 12ab into which the spool piece 32a is inserted is preferably provided at the center of the upper plate 12a.

[0039] The plurality of rod-shaped members 12b are rod-shaped members that connect the upper plate 12a and the lower plate 12c.

[0040] The lower plate 12c is a plate-like member that is connected to the upper plate 12a via a plurality of rod-like members 12b, and supports the spool piece 32a that is inserted through the hole 12ab of the upper plate 12a.

[0041] It is preferable that a support rod 12ca (see Figure 6) is provided on the upper surface of the lower plate 12c to fit into a hole in the bottom 32ae (see Figure 6) of the spool piece 32a to prevent the spool piece 32a from moving or tipping over, and to support the spool piece 32a.

[0042] In addition, the multiple bolt wrenches 12d are parts for tightening and loosening the multiple bolts 32ad that are inserted from below into the multiple through holes 32ab in the flange portion 32aa of the spool piece 32a and screwed into the multiple bolt holes in the flange portion of the drive mechanism main body 31 to connect the spool piece 32a to the drive mechanism main body 31.

[0043] Each of the plurality of bolt wrenches 12d is preferably attached to the lower plate 12c so as to be rotatable in the circumferential direction.

[0044] In this embodiment, the bolts 32ad are hexagon socket bolts, and the upper end of each of the bolt wrenches 12d is a hexagon wrench 12da that is inserted into a hexagon socket provided in the head 32af of each of the bolts 32ad.

[0045] Furthermore, the main body 12db of each of the bolt wrenches 12d is preferably formed of a round bar covered with a pipe, thereby ensuring strength and safety.

[0046] The lower ends of the round bars forming the bodies 12db of the plurality of bolt wrenches 12d are attached to the lower plate 12c so as to be rotatable in the circumferential direction of each of the plurality of bolt wrenches 12d. On the other hand, the lower portions of the pipes that form the bodies 12db of the plurality of bolt wrenches 12d and cover the round bars are preferably fixed to the lower plate 12c.

[0047] The upper ends of the round bars forming the bodies 12db of the bolt wrenches 12d are attached to the intermediate plate 12g so as to be rotatable in the circumferential direction of each of the bolt wrenches 12d. On the other hand, the upper ends of the pipes that form the bodies 12db of the bolt wrenches 12d and cover the round bars are preferably fixed to the intermediate plate 12g.

[0048] The intermediate plate 12g is a plate provided between the upper plate 12a and the lower plate 12c. The intermediate plate 12g has through holes for passing the multiple rod-shaped members 12b and holes for inserting the spool piece 32a. This prevents each of the multiple bolt wrenches 12d from moving up, down, left, right, front, and back in the spool piece holding jig 12, and allows them to rotate only in the circumferential direction.

[0049] In addition, the upper plate 12a is provided with a plurality of through holes 12ac (see Figure 5; in this embodiment, these are connected to the through holes for inserting the spool pieces 32a) having a diameter larger than the outer diameter of the heads 32af of the plurality of bolts 32ad so that the heads 32af can pass through.

[0050] Furthermore, as shown in FIG. 6, the spool piece holding jig 12 according to this embodiment may have a plurality of sockets 12f below the lower plate 12c, which can be connected to any of a plurality of bolt wrenches 12d and rotate the connected bolt wrench 12d in the circumferential direction.

[0051] This allows the spool piece holding jig 12 to have a hexagonal wrench inserted into the hexagonal holes provided in the multiple sockets 12f, and to tighten the multiple bolts 32ad into bolt holes provided on the underside of the flange of the drive mechanism main body 31.

[0052] FIG. 7 is a schematic side view showing a state in which the spool piece 32a has been raised by the lifting mechanism 11 in the lower component installation and removal device 1 according to this embodiment.

[0053] The spool piece 32a held by the spool piece holding jig 12 fixed to the upper ends of the multiple fluid pressure cylinders 11a of the lower component installation / removal device 1 is raised by extending the multiple fluid pressure cylinders 11a, as shown in Figure 7.

[0054] Fig. 8 is a perspective view of a first jig 15 fixed to the upper ends of the two retracted fluid pressure cylinders 11a, a second jig 16 placed on the first jig 15, and a motor bracket 32b held by the second jig 16. Fig. 9 is a perspective view of the first jig 15 fixed to the upper ends of the two retracted fluid pressure cylinders 11a and a motor unit 32c held by the first jig 15.

[0055] The spool piece holding jig 12 can be removed from the upper end of the fluid pressure cylinder 11a by removing the bolts of the fixing portion 12aa (see FIG. 5). Therefore, after the spool piece 32a is attached to the drive mechanism body 31, the multiple fluid pressure cylinders 11a are retracted and the spool piece holding jig 12 is removed from the upper end of the multiple fluid pressure cylinders 11a.

[0056] 8, a first jig 15 is attached to the upper ends of the multiple fluid pressure cylinders 11a, a second jig 16 is placed on the first jig 15, and the motor bracket 32b is held by the second jig 16. Then, by extending the multiple fluid pressure cylinders 11a and raising the second jig 16 holding the motor bracket 32b, the motor bracket 32b can be joined to the spool piece 32a joined to the drive mechanism main body 31.

[0057] Furthermore, after the motor bracket 32b is joined to the spool piece 32a, the multiple fluid pressure cylinders 11a are retracted, the second jig 16 is removed from the first jig 15, and the motor unit 32c is held by the first jig 15, as shown in Fig. 9. Then, by extending the multiple fluid pressure cylinders 11a and raising the first jig 15 holding the motor unit 32c, the motor unit 32c can be joined to the motor bracket 32b joined to the spool piece 32a.

[0058] Conversely, after the motor unit 32c is removed from the motor bracket 32b using the first jig 15, the second jig 16 is placed on the first jig 15 as shown in Fig. 8. This allows the motor bracket 32b to be held by the second jig 16, and the motor bracket 32b to be removed from the spool piece 32a.

[0059] Furthermore, after removing the motor bracket 32b from the spool piece 32a, the second jig 16 is removed from the first jig 15, and the first jig 15 is removed from the upper ends of the multiple fluid pressure cylinders 11a. Then, the spool piece holding jig 12 is attached to the upper ends of the fluid pressure cylinders 11a. This allows the spool piece 32a to be held by the spool piece holding jig 12, and the spool piece 32a can be removed from the drive mechanism body 31.

[0060] Therefore, the lower component attachment / detachment device 1 can attach and detach each of the spool piece 32 a , the motor bracket 32 ​​b , and the motor unit 32 c that constitute the lower component 32 from the control rod drive mechanism 3 .

[0061] 1, 5 and 7, the lower component removal device 1 preferably includes a moving mechanism 13 that allows the lower component removal device 1 to be freely moved on a platform 7 below the reactor pressure vessel 2. As shown in FIGS.

[0062] 1, 5, and 7, the moving mechanism 13 may include a carriage 13c having flanged wheels 13a that can be moved manually along rails 6 laid on the platform 7, and a gripping portion 13b that an operator can grip to move the lower component installation / removal device 1. Note that the carriage 13c is preferably provided with a stopper 13d (see FIG. 5) that fixes the carriage 13c after it has been moved below the lower component 32.

[0063] Furthermore, it is preferable that the moving mechanism 13 is provided with at least one of a slide table 13e that can slide and position the support plate 11b of the lifting mechanism 11 along the surface of the support plate 11b, and a rotary table 13f that can rotate the support plate 11b around an axis in the vertical direction and can position the rotation angle.

[0064] In this embodiment, the slide table 13e is fixed on the carriage 13c, the rotary table 13f is fixed on the slide table 13e, and the support plate 11b is fixed on the rotary table 13f.

[0065] In addition, it is preferable that the slide table 13e is provided with a stopper (not shown) for positioning the slid table, and it is preferable that the rotation table 13f is provided with a stopper (not shown) for positioning the rotation angle of the rotated table.

[0066] Figure 10 is a schematic perspective view showing a state in which, in the lower component installation / removal device 1 according to this embodiment, the lifting mechanism 11 is unable to hold the spool piece 32a at a height at which it can be attached to the drive mechanism main body 31, and the push-up mechanism 14 pushes the spool piece up to that height and holds it there.

[0067] The push-up mechanism 14 is a mechanism for lifting the spool piece 32a using the lifting mechanism 11, and if the spool piece 32a cannot be held at a height at which it can be attached to the drive mechanism main body 31, it pushes the spool piece 32a up to a height at which it can be attached to the drive mechanism main body 31 via the lower plate 12c of the spool piece holding jig 12, and holds the spool piece 32a at that height.

[0068] In order to attach the spool piece 32a to the drive mechanism main body 31, it is necessary to raise the spool piece 32a to a height where the upper surface of the flange portion 32aa of the spool piece 32a comes into surface contact with the lower surface of the flange portion of the drive mechanism main body 31 (a height at which the spool piece 32a can be attached to the drive mechanism main body 31), and then hold the spool piece 32a at that height.

[0069] However, since a load including the head pressure of the cooling water in the reactor pressure vessel 2 is applied to the spool piece 32a via the control rod, this load may be significantly larger than the load applied to the motor unit and motor bracket.

[0070] In such a case, it becomes difficult for the lifting mechanism 11 to raise the spool piece 32a to a height where the upper surface of the flange portion 32aa of the spool piece 32a comes into surface contact with the lower surface of the flange portion of the drive mechanism main body 31, and to hold the spool piece 32a at that height.

[0071] In such a case, the lower component installation / removal device 1 is provided with a push-up mechanism 14 that pushes up the spool piece 32a to a height at which it can be attached to the drive mechanism body 31 and holds it there.

[0072] Fig. 11 is a schematic side view of the push-up mechanism 14 in the lower component installation / removal device 1 according to this embodiment. As shown in Fig. 11, the push-up mechanism 14 has a push-up part 14a and a bracing part 14b.

[0073] FIG. 12 is a schematic side view showing an enlarged view of the push-up portion 14a of the push-up mechanism 14 in the lower component installation and removal device 1 according to this embodiment.

[0074] It is preferable that the lifting section 14a is provided with a mechanical jack 14aa, and a load receiving section 14ab of the mechanical jack 14aa lifts and holds the spool piece 32a to a height at which it can be attached to the drive mechanism body 31 via a tension section 14b.

[0075] The mechanical jack 14aa is preferably a so-called pantograph jack, which is placed on the support plate 11b of the lifting mechanism 11 and can move the load receiving section 14ab up and down by operating a handle (not shown).

[0076] The lifting section 14a further includes a driven plate 14ac that follows the up and down movement of the load receiving section 14ab of the mechanical jack 14aa, and a plurality of (two in this embodiment) pins 14ad that support the up and down movement of the driven plate 14ac.

[0077] The driven plate 14ac is a plate-like member whose lower surface contacts the upper part of the goods receiving part 14ab and on whose upper surface the lower part of the tensioning part 14b rests, and which has a plurality of through holes that penetrate vertically and into which one of the plurality of pins 14ad is inserted. Bushings 14ae are attached to the plurality of through holes so that the inner peripheral surfaces of the plurality of through holes slide over the side surfaces of the plurality of pins 14ad.

[0078] The positioning pins 14ad are cylindrical bodies whose lower ends are fixed to the support plate 11b and extend upward, and whose upper ends are preferably located higher than the highest position of the load receiving portion 14ab of the mechanical jack 14aa.

[0079] As a result, the driven plate 14ac rises along the pins 14ad as the load receiving portion 14ab of the mechanical jack 14aa rises, and can stably push up the lower portion of the tension portion 14b.

[0080] It is also possible to provide a mechanism for attaching and detaching the upper surface of the driven plate 14ac and the lower part of the tension part 14b so that the lower part of the tension part 14b can be attached and detached to the upper surface of the driven plate 14ac.

[0081] 11, the tension portion 14b is preferably a long support rod that is provided above the load receiving portion 14ab of the mechanical jack 14aa and supports the load of the spool piece 32a. The tension portion 14b, which is a long support rod, is preferably formed by arranging a plurality of rods (two rods 14ba and 14bb in this embodiment) in series in the axial direction.

[0082] The uppermost bar material (bar material 14ba in this embodiment) among the multiple bar materials forming the tension portion 14b is preferably attached to the lower surface of the lower plate 12c of the spool piece holding jig 12. The lowermost bar material (bar material 14bb in this embodiment) among the multiple bar materials forming the tension portion 14b is preferably attached to the upper surface of the driven plate 14ac of the push-up portion 14a.

[0083] In this embodiment, the plurality of rods is two rods 14ba and 14bb, and no other rod is attached to the lower end of the uppermost rod 14ba. However, if the plurality of rods is three or more rods, it is preferable to attach rods other than the lowermost rod to the lower end of the uppermost rod 14ba in series in the axial direction to form upper rods.

[0084] It is preferable to leave a space between the bottom end of the upper bar (bar 14ba in this embodiment) and the top end of the lowest bar (bar 14bb in this embodiment) before pushing up the load receiving portion 14ab of the mechanical jack 14aa, which makes it easier to attach the tensioning portion 14b.

[0085] Furthermore, it is preferable that the lower end of the upper bar (bar 14ba in this embodiment) and the upper end of the lowest bar (bar 14bb in this embodiment) have a flat shape. This allows the lower end of the upper bar (bar 14ba in this embodiment) and the upper end of the lowest bar (bar 14bb in this embodiment) to come into surface contact when the load receiving portion 14ab of the mechanical jack 14aa is pushed up, thereby preventing buckling of the tensioning portion 14b.

[0086] Alternatively, a flange may be provided at the bottom end of the upper bar (bar 14ba in this embodiment) and the top end of the lowest bar (bar 14bb in this embodiment), and after the bottom end of the upper bar (bar 14ba in this embodiment) and the top end of the lowest bar (bar 14bb in this embodiment) come into contact, they may be joined with bolts. This improves safety.

[0087] Furthermore, the plurality of rods (two rods 14ba and 14bb in this embodiment) may be formed from pipes that can withstand the load applied from the spool piece 32a.

[0088] (How to use the lower component removal device 1) Next, a method of using the lower component installation and removal device 1 according to this embodiment will be described.

[0089] First, the bolts 32ad are inserted from below into each of the through holes 32ab of the spool piece 32a that has been inspected and maintained in the repair room 8, and are temporarily fixed so as not to fall off.

[0090] Next, the spool piece 32a is lifted by a crane or the like so that the spool piece 32a is positioned above the spool piece holding jig 12 fixed to the upper ends of the plurality of retracted fluid pressure cylinders 11a of the lower component installing / removing device 1.

[0091] Next, the spool piece 32a is lowered so that the bottom portion 32ae of the spool piece 32a passes through the hole 12ab of the upper plate 12a of the spool piece holding jig 12 and the hole of the intermediate plate 12g.

[0092] Next, the spool piece 32a is further lowered so that the upper ends of the hexagonal wrenches 12da of the plurality of bolt wrenches 12d provided on the spool piece holding jig 12 are inserted into the hexagonal holes provided in the heads 32af of the plurality of bolts 32ad.

[0093] Next, the spool piece 32a is further lowered until the bottom 32ae of the spool piece 32a engages with the support rod 12ca provided on the upper surface of the lower plate 12c. After confirming that the spool piece 32a is supported by the lower plate 12c, the spool piece 32a is removed from the crane or the like.

[0094] Next, the lower component installation / removal device 1 is moved onto the rails 6 of the platform 7, and the platform 7 is remotely rotated so that the rails 6 pass below the drive mechanism body 31 to which the spool piece 32a is attached.

[0095] Next, the lower component installation / removal device 1 is manually moved along the rails 6 to immediately below the drive mechanism body 31 to which the spool piece 32a is attached, and the carriage 13c is fixed by the stopper 13d.

[0096] Next, water is injected into the plurality of fluid pressure cylinders 11a by an operating device provided on the lower component installation / removal device 1, the plurality of fluid pressure cylinders 11a are extended, and the spool piece 32a is raised.

[0097] At this time, the spool piece holding jig 12 is raised to a height where the upper surface of the flange portion 32aa of the spool piece 32a and the lower surface of the flange portion of the drive mechanism main body 31 are in surface contact without interfering with the surrounding control rod drive mechanism 3.

[0098] If the lifting mechanism 11 cannot raise the spool piece 32a and maintain it at a height where the upper surface of the flange portion 32aa of the spool piece 32a and the lower surface of the flange portion of the drive mechanism main body 31 are in surface contact, a push-up mechanism 14 is attached below the spool piece 32a.

[0099] Next, the push-up mechanism 14 pushes up the spool piece 32a to a height where the upper surface of the flange portion 32aa of the spool piece 32a and the lower surface of the flange portion of the drive mechanism body 31 come into surface contact with each other, and holds the spool piece 32a.

[0100] Next, the spool piece 32a is attached to the drive mechanism body 31 by the following steps.

[0101] On the other hand, if it is determined that the lifting mechanism 11 can raise the spool piece 32a to a height where the upper surface of the flange portion 32aa of the spool piece 32a is in surface contact with the lower surface of the flange portion of the drive mechanism main body 31 and maintain it at that height, the process proceeds to the following step without attaching the push-up mechanism 14 below the spool piece 32a.

[0102] Next, the position and orientation of the fluid pressure cylinder 11a are finely adjusted using the slide table 13e and the rotary table 13f so that each of the multiple bolts 32ad can be attached to a multiple bolt holes (not shown) provided on the underside of the drive mechanism body 31.

[0103] Next, hexagonal wrenches are attached to the multiple sockets 12f, and the multiple bolt wrenches 12d are rotated to tighten the multiple bolts 32ad into the multiple bolt holes on the underside of the drive mechanism body 31, thereby connecting the spool piece 32a to the drive mechanism body 31.

[0104] (effect) The lower component installation and removal device 1 of this embodiment includes a lifting mechanism 11 that raises and lowers a spool piece 32a that may be included in a control rod drive mechanism 3 that drives a control rod by extending and contracting a plurality of fluid pressure cylinders 11a, and a push-up mechanism 14 that pushes up and holds the spool piece 32a to a height at which it can be attached to the drive mechanism body 31 of the control rod drive mechanism 3 when the lifting mechanism 11 cannot hold the spool piece 32a at a height at which it can be attached to the drive mechanism body 31 of the control rod drive mechanism 3.

[0105] As a result, even if a load that exceeds the lifting capacity of the fluid pressure cylinder 11a of the lifting mechanism 11 acts on the spool piece 32a, the spool piece 32a can be pushed up by the push-up mechanism 14 to a height that allows it to be attached to the drive mechanism body 31 of the control rod drive mechanism 3, making it easy to attach the spool piece 32a to the drive mechanism body 31 of the control rod drive mechanism 3.

[0106] In addition, it is preferable that the push-up mechanism 14 of the lower component removal device 1 of this embodiment is equipped with a mechanical jack 14aa, and that the load receiving portion 14ab of the mechanical jack 14aa pushes up and holds the spool piece 32a to a height at which it can be attached to the drive mechanism body 31 of the control rod drive mechanism 3.

[0107] This not only reduces costs, but also reduces the risk of unexpected incidents such as fires, compared to when using hydraulic jacks or electric jacks.

[0108] Furthermore, the push-up mechanism 14 of the lower component detachment device 1 of this embodiment is provided with a support rod (tensioning portion 14b) that supports the load of the spool piece 32a above the load receiving portion 14ab of the mechanical jack 14aa, and it is preferable that the support rod (tensioning portion 14b) is formed by arranging multiple rods (in this embodiment, two rods 14ba, 14bb) in series in the axial direction.

[0109] This allows the load of spool piece 32a to be supported by a support rod (tensioning portion 14b) with a simple shape, thereby reducing costs. In addition, multiple rods (two rods 14ba and 14bb in this embodiment) can be easily transported to the work site, facilitating installation of push-up mechanism 14.

[0110] Furthermore, each of the multiple fluid pressure cylinders 11a of the lifting mechanism 11 of the lower component installation / removal device 1 of this embodiment is preferably a multi-stage cylinder, which allows for a larger stroke and allows the spool piece 32a to be positioned from a lower position to a higher position compared to a single-stage cylinder.

[0111] Furthermore, it is preferable that the fluid pressure cylinder 11a of the lifting mechanism 11 of the lower component installation / removal device 1 of this embodiment is a water pressure cylinder. This allows for improved response performance and positioning accuracy compared to pneumatic cylinders. In addition, the use of water pressure can reduce the occurrence of unexpected events such as fires compared to hydraulic or electrical systems.

[0112] Furthermore, the spool piece holding jig of the lower component installation and removal device 1 of this embodiment preferably includes an upper plate 12a connected to the upper part of the lifting mechanism 11 and having a hole 12ab into which the spool piece 32a is inserted, a lower plate 12c provided below the upper plate 12a and connected to the upper plate 12a via a plurality of rod-shaped members 12b to support the spool piece 32a, and a plurality of bolt wrenches 12d attached to the lower plate 12c so as to be rotatable in the circumferential direction and used to tighten or loosen each of a plurality of bolts 32ad that fix the spool piece 32a to the drive mechanism body 31 of the control rod drive mechanism 3. This allows the spool piece 32a to be installed and removed from the drive mechanism body 31 efficiently.

[0113] Furthermore, the method of using the lower component attachment / detachment device 1 according to this embodiment is a method of using the lower component attachment / detachment device 1 for attaching and detaching a spool piece 32a that may be included in the control rod drive mechanism 3 that drives the control rod from the drive mechanism main body 31 of the control rod drive mechanism 3, and the lower component attachment / detachment device 1 includes an elevator mechanism 11 that raises and lowers the spool piece 32a by extension and contraction of a plurality of fluid pressure cylinders 11a, and a method of using the elevator mechanism 11 to raise and lower the spool piece 32a by extension and contraction of a plurality of fluid pressure cylinders 11a when the elevator mechanism 11 cannot hold the spool piece 32a at a height that allows it to be attached to the drive mechanism main body 31 of the control rod drive mechanism 3. The spool piece 32a is raised by the lifting mechanism 11 to attach it to the drive mechanism body 31, and if the lifting mechanism 11 cannot hold the spool piece 32a at a height at which it can be attached to the drive mechanism body 31 of the control rod drive mechanism 3, the lifting mechanism 14 pushes the spool piece 32a up to a height at which it can be attached to the drive mechanism body 31 of the control rod drive mechanism 3 and holds it there, and the spool piece 32a is attached to the drive mechanism body 31.

[0114] This allows the spool piece 32a to be easily connected to the drive mechanism main body 31 by the lower component detachment device 1, even if a load exceeding the lifting capacity of the fluid pressure cylinder 11a of the lifting mechanism 11 acts on the spool piece 32a.

[0115] (Second embodiment) FIG. 13 is a schematic perspective view showing a state in which, in the lower component installation / removal device 201 according to the second embodiment of the present invention, the lifting mechanism 11 is unable to hold the spool piece 32a at a height at which it can be attached to the drive mechanism main body 31, and the push-up mechanism 14 pushes up the spool piece 32a to that height and holds it there.

[0116] The lower component installation / removal device 201 according to this embodiment differs from the lower component installation / removal device 1 according to the first embodiment in the following points.

[0117] First, the lower component detachment device 201 according to this embodiment differs from the lower component detachment device 1 according to the first embodiment in that it is provided with a torque wrench installation jig 217 that installs a torque wrench below the spool piece holding jig 212 to control the tightening torque of the multiple bolts 32ad for the multiple bolt holes in the drive mechanism main body 31.

[0118] Second, the lower component installation and removal device 1 according to the first embodiment includes a plurality of sockets 12f that are connected to any of the plurality of bolt wrenches 12d below the lower plate 12c of the spool piece holding jig 12. In contrast, the lower component installation and removal device 201 according to the present embodiment includes a hex wrench 212f that is connected to any of the plurality of bolt wrenches 12d below the lower plate 12c of the spool piece holding jig 212.

[0119] Fig. 14 is a side view of the torque wrench installation jig 217. Fig. 15 is a perspective view of the torque wrench installation jig 217.

[0120] The torque wrench installation jig 217 preferably includes a wrench mounting portion 217a to which the torque wrench is attached, a power-boosting wrench 217b, a power-boosting wrench holding plate 217c, a socket 217d, a connecting plate 217e, a handle 217f, a spring 217g, and a stop plate 217h.

[0121] Wrench mounting portion 217a has a mounting hole (not shown) for mounting a square drive, which is the output portion of a torque wrench set to input a specific torque value, and is provided below spool piece holding jig 212. Therefore, a torque wrench with a square drive attached to the mounting hole of wrench mounting portion 217a is placed below spool piece holding jig 212. The mounting hole of wrench mounting portion 217a connects to the lower part of power-boosting wrench 217b.

[0122] When tightening or loosening the bolt 32ad in the lower component installation / removal device 1 of the first embodiment, the worker attaches a hexagonal socket to the square drive, which is the output part of the torque wrench, and inserts the tip of the hexagonal socket into the hexagonal hole of the socket 12f. Therefore, the worker needs to tighten or loosen the bolt 32ad while supporting the torque wrench so that the tip of the hexagonal socket does not come out of the hexagonal hole of the socket 12f.

[0123] In contrast, in this embodiment, the square drive, which is the output part of the torque wrench, is attached to the mounting hole of the wrench mounting portion 217a, so the operator does not need to support the torque wrench so that the tip of the hexagonal socket does not come out of the hexagonal hole of the socket 12f. This improves the efficiency and safety of the work of tightening and loosening the bolt 32ad.

[0124] The power-boosting wrench 217b is a tool for amplifying and outputting an input force. The torque wrench installation jig 217 of this embodiment has two power-boosting wrenches 217b. Therefore, the torque wrench installation jig 217 of this embodiment has two wrench attachment portions 217a.

[0125] A specific torque value input from the torque wrench to the power-boosting wrench 217b through the mounting hole of the wrench mounting portion 217a is amplified, for example, by 10 times by the power-boosting wrench 217b and output to a bit portion (not shown) at the top of the power-boosting wrench 217b.

[0126] The power-assist wrench holding plate 217c is a plate-like member that holds the power-assist wrench 217b. (Note that the power-assist wrench holding plate 217c in this embodiment holds the upper part of the power-assist wrench 217b.) A through-hole 217ca is provided in the center of the power-assist wrench holding plate 217c, into which the tension portion 14b of the push-up mechanism 14 is inserted. Therefore, the power-assist wrench holding plate 217c can rotate in the circumferential direction around the tension portion 14b, and can move along the axial direction of the tension portion 14b. Furthermore, a bit portion, which is the output portion of the power-assist wrench 217b, is exposed on the surface of the power-assist wrench holding plate 217c, and a socket 217d is attached to it.

[0127] The socket 217d is a tool for transmitting the output of the power-up wrench 217b to the bolt wrench 12d. The torque wrench installation jig 217 of this embodiment has two sockets 217d, the same number as the two power-up wrenches 217b. The lower part of the socket 217d is connected to the bit portion of the power-up wrench 217b exposed from the surface of the power-up wrench holding plate 217c.

[0128] The upper part of socket 217d is provided with a hole that fits onto the outer periphery of hexagonal wrench 212f provided below lower plate 12c of spool piece holding jig 212. Therefore, the upper end of socket 217d is annular. Therefore, damage to the lower surface of lower plate 12c when the upper end of socket 217d abuts against the lower surface of lower plate 12c can be reduced compared to damage to the lower surface of lower plate 12c when the upper end of a hexagonal wrench abuts against the lower surface of lower plate 12c.

[0129] The tip of hexagonal wrench 212f is inserted into the hole of socket 217d, and hexagonal wrench 212f fits into the hole of socket 217d. As socket 217d rotates in the circumferential direction, hexagonal wrench 212f rotates circumferentially together with socket 217d. Furthermore, as hexagonal wrench 212f rotates in the circumferential direction, bolt wrench 12d connected to hexagonal wrench 212f also rotates in the circumferential direction. As bolt wrench 12d rotates in the circumferential direction, hexagonal wrench 12da at the upper end of bolt wrench 12d rotates. Furthermore, as hexagonal wrench 12da rotates, bolt 32ad, whose tip is inserted into the hexagonal hole of head 32af, rotates and tightens or loosens the bolt hole in drive mechanism main body 31.

[0130] Therefore, the output torque output to the upper bit portion of the power-up wrench 217b is approximately equal to the tightening torque of the plurality of bolts 32ad into the bolt holes in the drive mechanism body 31. Therefore, the torque input from the torque wrench and amplified by the power-up wrench 217b is approximately equal to the tightening torque of the plurality of bolts 32ad into the bolt holes in the drive mechanism body 31. Therefore, the specific torque value input from the torque wrench to the power-up wrench 217b can be set to a small value.

[0131] The distance between the center axis of the through-hole 217ca, into which the central strut portion 14b of the power-assist wrench holding plate 217c is inserted, and the center axis of the upper hole of the socket 217d attached to the bit portion of the power-assist wrench 217b is approximately equal to the distance between the center axis of the strut portion 14b attached to the underside of the lower plate 12c of the spool piece holding jig 12 and the center axis of the hex wrench 212f. This makes it possible to rotate the power-assist wrench holding plate 217c in the circumferential direction around the strut portion 14b, and attach the socket 217d to each of the multiple hex wrenches 212f. This improves work efficiency.

[0132] A connecting plate 217e that connects the multiple power-assist wrenches 217b is preferably provided at the lower end of the power-assist wrenches 217b. As a result, the multiple power-assist wrenches 217b are sandwiched and integrated between the power-assist wrench holding plate 217c and the connecting plate 217e, and are prevented from coming off the power-assist wrench holding plate 217c, thereby improving safety.

[0133] The connecting plate 217e is a plate member that is coupled to the lower ends of the multiple power-assisting wrenches 217b and connects the multiple power-assisting wrenches 217b. A through-hole 217ea into which the tension member 14b is inserted is provided in the center of the connecting plate 217e. A wrench mounting portion 217a is provided on the underside of the connecting plate 217e.

[0134] Furthermore, the connecting plate 217e is preferably provided with a handle 217f for pulling down the torque wrench installation jig 217 or rotating it around the tension portion 14b. Note that the handle 217f in this embodiment is formed by two round bars extending downward from the lower surface of the connecting plate 217e.

[0135] Furthermore, it is preferable that the lower surface of connecting plate 217e contacts the annular portion at the upper end of spring 217g wound around tension portion 14b. Therefore, it is preferable that the inner diameter of through hole 217ea of ​​connecting plate 217e is larger than the outer diameter of tension portion 14b and smaller than the inner diameter of spring 217g, and that annular portion 217eb around through hole 217ea is larger than the outer diameter of spring 217g.

[0136] Spring 217g is a component for easily attaching socket 217d, which has been removed from hex wrench 212f, to another hex wrench 212f by pulling down handle 217f, and is preferably a helical spring wound around tension portion 14b. Preferably, the upper end of spring 217g contacts the lower surface of connecting plate 217e, and the lower end of spring 217g contacts stop plate 217h.

[0137] The position of the lower end of spring 217g is preferably determined by stop plate 217h so that the upper end of socket 217d in unloaded torque wrench installation jig 217 comes into contact with the lower surface of lower plate 12c. Furthermore, spring 217g is preferably easily compressed by an operator pulling down handle 217f, allowing socket 217d to be easily separated from hexagonal wrench 212f.

[0138] This allows the worker to pull down the handle 217f and rotate it circumferentially around the tensioning portion 14b, thereby attaching the two sockets 217d attached to the two hex wrenches 212f to the other two hex wrenches 212f, thereby improving work efficiency.

[0139] The retaining plate 217h is a flange-shaped disk attached and fixed to the tension portion 14b. The torque wrench installation jig 217 is prevented from coming off the lower component installation / removal device 201 because the retaining plate 217h is fixed to the tension portion 14b.

[0140] It is preferable to attach the torque wrench installation jig 217 to the upper rod material (in this embodiment, rod material 14ba) among the multiple rod materials that form the tensioning portion 14b when attaching the upper rod material to the underside of the lower plate 12c of the spool piece holding jig 12.

[0141] (effect) As described above, the load applied to spool piece 32a from the control rod includes the head pressure of the cooling water in the pressure vessel applied via the control rod, and is therefore significantly larger than the load applied to motor unit 32c and motor bracket 32b. Therefore, a large load is applied to the multiple bolts 32ad that secure spool piece 32a to drive mechanism body 31, and if the tightening torque of the multiple bolts 32ad in the multiple bolt holes of drive mechanism body 31 is weak, the following risks may occur.

[0142] For example, there is a risk that vibrations occurring during operation of the control rod drive mechanism 3 may gradually loosen the bolts 32ad, causing the spool piece 32a to fall off. Also, there is a risk that a gap may form in the seal between the spool piece 32a and the drive mechanism main body 31, resulting in leakage of cooling water from the pressure vessel. Furthermore, there is a risk that the attachment position of the spool piece 32a may shift, preventing the control rod drive mechanism 3 from operating normally. Therefore, it is necessary to tighten the tightening torque of the bolts 32ad in the bolt holes of the drive mechanism main body 31.

[0143] On the other hand, if excessive torque is applied to the bolt 32ad, the head of the bolt 32ad may come off, or the threads of at least one of the multiple bolt holes in the drive mechanism body 31 and the multiple bolts 32ad may be damaged or worn, causing the bolt 32ad to no longer thread into the bolt hole in the drive mechanism body 31. Therefore, when attaching or detaching the spool piece 32a from the drive mechanism body 31, it is necessary to use a torque wrench to control the tightening torque of the multiple bolts 32ad to the multiple bolt holes in the drive mechanism body 31.

[0144] The lower component installation / removal device 201 according to this embodiment includes a torque wrench installation jig 217 that installs a torque wrench below the spool piece holding jig 12 to control the tightening torque of the plurality of bolts 32ad in the plurality of bolt holes in the drive mechanism main body 31. This allows the worker to tighten or loosen the bolts 32ad without having to support the torque wrench, thereby improving work efficiency and safety.

[0145] Furthermore, torque wrench installation jig 217 is provided with a power-boosting wrench 217b, which allows the specific torque value input using the torque wrench to be set to a small value, thereby reducing the labor required by the worker. [Explanation of symbols]

[0146] 1,201...Lower component removal device, 3...Control rod drive mechanism, 11...Lifting mechanism, 11a...Fluid pressure cylinder, 11b...Support plate, 12...Spool piece holding jig, 12a...Upper plate, 12b...Rod-shaped member, 12c...Lower plate, 12d...Bolt wrench, 14...Push-up mechanism, 14aa...Mechanical jack, 14ab...Load receiving section, 14b...Support rod (tensioning section), 14ba, 14bb...Rod material, 31...Drive mechanism body, 32a...Spool piece, 32ad...Bolt, 217...Torque wrench installation jig, 217b...Power-boosting wrench

Claims

1. a lifting mechanism that lifts and lowers a spool piece that may be included in a control rod drive mechanism that drives the control rod by expanding and contracting a plurality of fluid pressure cylinders; a push-up mechanism that, if the lifting mechanism cannot hold the spool piece at a height at which it can be attached to the main body of the control rod drive mechanism, pushes up the spool piece to the height and holds it there.

2. 2. The lower component detachment device according to claim 1, the lifting mechanism comprises a mechanical jack; A lower component removal device, characterized in that a load receiving portion of the mechanical jack pushes up and holds the spool piece to the height.

3. The lower component detachment device according to claim 2, The lifting mechanism includes a support rod that supports the load of the spool piece above the load receiving portion of the mechanical jack, The lower component removal device is characterized in that the support rod is formed by arranging a plurality of rod members in series in the axial direction.

4. 2. The lower component detachment device according to claim 1, 10. A lower component installation / removal device, wherein each of the plurality of fluid pressure cylinders is a multi-stage cylinder.

5. 2. The lower component detachment device according to claim 1, The lower component detachment device, wherein the fluid pressure cylinder is a water pressure cylinder.

6. 2. The lower component detachment device according to claim 1, an upper plate connected to an upper portion of the lifting mechanism and having a hole into which the spool piece is inserted; a lower plate provided below the upper plate, connected to the upper plate via a plurality of rod-shaped members, and supporting the spool piece; a spool piece holding jig attached to the lower plate so as to be freely rotatable in a circumferential direction, and having a plurality of bolt wrenches configured to tighten and loosen each of a plurality of bolts that connect the spool piece to a main body of the control rod drive mechanism.

7. 7. The lower component detachment device according to claim 6, a torque wrench installation jig that installs a torque wrench that manages the tightening torque of the plurality of bolts in the plurality of bolt holes in the main body of the control rod drive mechanism below the spool piece holding jig.

8. The lower component detachment device according to claim 7, The lower component removal and installation device, wherein the torque wrench installation jig is provided with a multiplying wrench.

9. A method for using a lower component removal device to remove a spool piece that may be included in a control rod drive mechanism that drives a control rod from a main body of the control rod drive mechanism, comprising: the lower component detachment device, a lifting mechanism that lifts and lowers the spool piece by expanding and contracting a plurality of fluid pressure cylinders; a push-up mechanism that pushes up and holds the spool piece to a height that allows attachment to the main body of the control rod drive mechanism when the lifting mechanism cannot hold the spool piece at the height, a lifting mechanism for lifting the spool piece to attach it to the main body of the control rod drive mechanism, and if the lifting mechanism cannot hold the spool piece at the height, a push-up mechanism for pushing up and holding the spool piece to the height, thereby attaching the spool piece to the main body of the control rod drive mechanism.

Images