Channel fastener handling device

Abstract

To easily position a screwdriver to the position of a fixing screw, in a device for handing a channel fastener attached to the upper part of a fuel assembly.SOLUTION: A channel fastener handling device 60 includes a turning device 68, a turning part 70, a screw operation rotation shaft part 74, a screwdriver 78, and an engagement member 72. The turning device 68 turnably drives the turning part 70 around a turning axis AX1 by a turning motor 69. One end side of the screw operation rotation shaft part 74 is rotatably supported by the turning part 70 and the screw operation rotation shaft part 74 is rotationally driven around a rotation axis AX2 arranged coaxially with the turning axis AX1 by a screw rotation motor 71. The screw driver 78 is connected to the other end part of the screw operation rotation shaft part 74 and arranged on the rotation axis AX2. One end side of the engagement member 72 is connected to the turning part 70 and the engagement member is turned. The engagement member 72 has a guide plate 82 inserted into a gap between a fuel rack and the fuel assembly, at a place out of the turning axis AX1 on the other end side.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] This invention relates to a device for handling channel fasteners that are attached to the top of a fuel assembly, and which uses power to rotate and drive the fixing screws of the channel fasteners. [Background technology]

[0002] The following Patent Document 1 describes a channel fastener handling device that uses power to remove channel fasteners from fuel assemblies housed in a fuel rack in a fuel pool in a boiling water nuclear reactor. This conventional channel fastener handling device will be described. Figure 15 shows Figure 1 of Patent Document 1. This channel fastener handling device is configured such that a device body 10 is suspended from a hoist 9, submerged in the fuel pool, and the fixing screws 7 of the channel fasteners 6 are operated by a screw rotation motor 25. Specifically, a guide 10a is formed at the bottom end of the device body 10. An air cylinder 14, which constitutes a vertical drive mechanism, is attached to the side of the device body 10 so that it can rotate around a rotation shaft 11 located within the device body 10 by driving a rotation motor 13. A fastener clamping mechanism 22 is connected to a shaft 15 of the air cylinder 14. A screwdriver 27 for rotating the fixing screws 7 is located at the bottom end of the fastener clamping mechanism 22. The screw driving tool 27 is rotated by a screw rotation motor 25 provided in the fastener clamping mechanism 22 .

[0003] The operation of removing a channel fastener using this conventional channel fastener handling device is performed as follows: The hoist 9 is operated to lower the device body 10 and submerge it in the fuel pool. The guide 10a at the bottom of the device body 10 is engaged with the handle 3 on the top of the fuel assembly 2 stored in the fuel rack 5, supporting the device body 10 above the fuel assembly 2. In this state, the rotation motor 13 is driven to rotate the air cylinder 14 around the rotation axis 11, positioning the screwdriver 27 of the fastener clamping mechanism 22 directly above the fixing screw 7. The air cylinder 14 is driven in the extension direction to lower the fastener clamping mechanism 22, and the screwdriver 27 is fitted onto the head of the fixing screw 7. A steel ball 28 arranged on the screwdriver 27 locks this fitted state. The screw rotation motor 25 in the fastener clamping mechanism 22 is driven to rotate the screw driving tool 27, loosening the fixing screw 7. Once the fixing screw 7 has been removed from the fuel assembly 2, the air cylinder 14 is driven in the contracting direction to raise the fastener clamping mechanism 22 and pull up the fixing screw 7 together with the channel fastener 6. The air cylinder 14 is rotated around the rotation axis 11 by the drive of the rotation motor 13, and positioned directly above the channel fastener receiver 30. The lock on the fixing screw 7 by the steel ball 28 is released, and the channel fastener 6 is dropped into the channel fastener receiver 30 and stored therein. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2563427 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the conventional channel fastener handling device, a two-stage rotation operation is required to engage the screw driving tool 27 with the fixing screw 7. First, the device body 10 is positioned directly above the handle 3. Then, for example, the hook of the hoist 9 is rotated to rotate the device body 10 about its own axis, aligning the engagement groove (not numbered) of the guide 10a with the orientation that engages with the handle 3 (first-stage rotation). The hoist 9 is lowered to engage the engagement groove of the guide 10a with the handle 3. This supports the device body 10 on top of the fuel assembly 2. Next, the rotation motor 13 is driven to rotate the air cylinder 14 about the rotation axis 11, positioning the screw driving tool 27 directly above the fixing screw 7 (second-stage rotation). In this state, the air cylinder 14 is driven in the extension direction to lower the fastener clamping mechanism 22, thereby engaging the screw driving tool 27 with the head of the fixing screw 7. Furthermore, as with the fuel assemblies stored in the spent fuel pool of Unit 3 of the Fukushima Daiichi Nuclear Power Plant, the handles may be deformed by scattered debris. When the handles are deformed in this way, the conventional channel fastener handling device is unable to engage the guide 10a with the handle 3, making it impossible to handle the channel fastener 6. Furthermore, since the conventional channel fastener handling device is used with the device main body 10 submerged in the fuel pool (see FIG. 3 of Patent Document 1), strict waterproofing measures were required for the swing motor 13 and the screw rotation motor 25.

[0006] SUMMARY OF THE INVENTION The present invention aims to provide a channel fastener handling device that can solve the problems in the prior art. [Means for solving the problem]

[0007] The present invention relates to a channel fastener handling device for handling channel fasteners to be attached to the top of a fuel assembly, the device comprising: a turning device having a turning motor; a turning section having a screw rotation motor and connected to the turning device, which is driven to turn around a predetermined turning axis by the turning motor; a screw operation rotating shaft section having one end rotatably supported by the turning section and driven to rotate around a rotation axis arranged coaxially with the turning axis by the screw rotation motor; and a screw operation rotating shaft section configured to be fitted onto the screw head of a fixing screw of the channel fastener. The screw driving tool includes a screw driving tool connected to the other end of the screw operation rotating shaft and disposed on the rotating shaft, the screw driving tool rotating about the rotating shaft in response to the rotation of the screw operation rotating shaft to rotate the engaged screw head, and an engagement member connected at one end to the swivel part and swiveling in response to the rotation of the swivel part, the engagement member having an engagement portion formed by a guide plate at a location on the other end of the engagement member that is spaced apart from the swivel shaft and that is inserted into a gap between a fuel rack in a fuel pool and the fuel assembly housed in the fuel rack. In this configuration, the swivel shaft of the swivel part and the rotation shaft of the screw operation rotating shaft part are coaxially arranged, and the screw driving tool is disposed on the rotation shaft. Therefore, even when the swivel part is rotated to position the guide plate so that it can be inserted into the gap between the fuel rack and the fuel assembly, the position of the screw driving tool relative to the fuel assembly does not change. In other words, since the position of the screw driving tool does not change relative to the fuel assembly as the swivel part rotates, the screw driving tool can be easily positioned at the position of the fixing screw. Furthermore, according to the present invention, the channel fastener handling device can be positioned relative to the fuel assembly by inserting the guide plate into the gap between the fuel rack and the fuel assembly. Therefore, since the handle of the fuel assembly is not used to position the channel fastener handling device relative to the fuel assembly, the channel fastener handling device of the present invention can be used even for fuel assemblies with deformed handles.

[0008] In this invention, the engaging member may have a tubular member, and the screw operation rotation shaft may be disposed coaxially with the tubular member in the internal space of the tubular member and supported rotatably around the rotation axis relative to the tubular member. In this way, the screw operation rotation shaft may be rotatably supported by the tubular member of the engaging member.

[0009] This invention can include a sleeve fitted around the outer periphery of the screw manipulation rotation shaft portion so as to be movable in the axial direction of the screw manipulation rotation shaft portion, a locking member that engages with the sleeve and is operated by movement of the sleeve in the axial direction to lock or unlock the fitted state between the screw driving tool and the screw head, and a sleeve drive unit that is supported by the tubular member and reversibly moves the sleeve in the axial direction of the screw manipulation rotation shaft portion.In this way, the fitted state between the screw driving tool and the screw head can be locked or unlocked by operating the locking member by reversibly moving the sleeve fitted around the screw manipulation rotation shaft portion in the axial direction of the screw manipulation rotation shaft portion with the sleeve drive unit.

[0010] This invention can include a cavity formed along the rotation axis inside the screw operation rotation shaft, a rod-shaped detection rod housed in the cavity so as to be movable along the rotation axis and having one end protruding from the screw driving tool so as to be able to abut against the screw head of the fixing screw fitted to the screw driving tool, and a position sensor that detects the position of the detection rod along the rotation axis relative to the swivel part or the screw operation rotation shaft. In this way, the detection rod and position sensor can detect the engaged / disengaged state of the screw driving tool and the screw head.

[0011] In this invention, the screw manipulation rotary shaft can be supported on the swivel unit so as to be movable along the rotation axis, and the screw manipulation rotary shaft can be supported on the swivel unit via a balance cylinder that cancels the weight of the screw manipulation rotary shaft acting on the fixing screw. This allows the axial movement of the fixing screw, which inevitably occurs when the fixing screw is turned with a screwdriver, to be absorbed by the movement of the screw manipulation rotary shaft relative to the swivel unit along the rotation axis. Furthermore, if a detection rod is incorporated in the screw manipulation rotary shaft and a position sensor is arranged to detect the position of the detection rod relative to the swivel unit along the rotation axis, the detection rod and position sensor can detect both the engaged / disengaged state between the screwdriver and the screw head, and the loosened (disengaged) / tightened (not disengaged) state of the fixing screw relative to the fuel assembly. Furthermore, the balance cylinder cancels the weight of the screw manipulation rotary shaft acting on the fixing screw, allowing the fixing screw to be turned with a light force using a screwdriver.

[0012] The present invention may further include a reinforcing frame connected to the fixed portion of the turning device and supporting the engaging member so that the engaging member can turn around the turning axis. In this way, the engaging member can be supported by the reinforcing frame.

[0013] The present invention may further comprise a television camera attached to the engaging member so as to be able to photograph the periphery of the guide plate, whereby the guide plate can be positioned in a position that allows it to be inserted into the gap between the fuel rack and the fuel assembly while watching the image from the television camera.

[0014] The present invention can be configured such that, when the fuel assemblies are housed in a fuel rack in a fuel pool, the guide plate is inserted into the gap between the fuel rack and the fuel assemblies, and the screw driving tool rotates the screw heads, the turning shaft and the rotation shaft are disposed perpendicular to the water surface of the fuel pool, and the turning motor and the screw turning motor are disposed in positions above the fuel pool where they will not be submerged. In this way, because the turning motor and the screw turning motor are disposed in positions above the fuel pool where they will not be submerged, strict waterproofing measures are not required. [Brief explanation of the drawings]

[0015] [Figure 1A] 1 is an elevational view (partially sectional front view) showing the overall configuration of a channel fastener handling device according to an embodiment of the present invention; [Figure 1B] FIG. 1B is a plan view of the channel fastener handling device of FIG. 1A. [Figure 1C] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 1D] FIG. 2 is a cross-sectional view taken along the arrow BB in FIG. [Figure 2] 1B is a schematic elevation view showing an outline of a system configuration for performing channel fastener removal work using the channel fastener handling device of FIG. 1A inside a reactor building. FIG. [Figure 3A] 1B is a partially cutaway perspective view showing the general configuration of a turning device in FIG. 1A. FIG. [Figure 3B] FIG. 2 is a cross-sectional front view showing the detailed configuration of the turning device. [Figure 3C] FIG. 2 is a plan view showing the detailed configuration of the rotation device. [Figure 4A] 2 is a partially cutaway perspective view showing the general configuration of a swivel unit in FIG. 1. FIG. [Figure 4B] FIG. 2 is a cross-sectional front view showing the detailed configuration of the swivel unit. [Figure 4C] FIG. 2 is a plan view showing the detailed configuration of the swivel unit. [Figure 4D] FIG. 2 is a cross-sectional side view showing the detailed configuration of the swivel unit. [Figure 5A] 2 is a partial cross-sectional view showing the configuration of one of the divided portions of the coaxial assembly member in FIG. 1 that exists in the shaft portion, taken along a plane passing through the rotation axis. FIG. [Figure 5B] 2 is an exploded perspective view showing the connection structure between the divided parts of the coaxial assembly member in FIG. 1. FIG. [Figure 6A] 2 is a partially cutaway perspective view showing the schematic configuration of the head unit in FIG. 1 in an unlocked state. FIG. [Figure 6B] 2 is a partially cutaway perspective view showing the general configuration of the head unit in FIG. 1 in a locked state. FIG. [Figure 6C] FIG. 2 is a cross-sectional front view showing a detailed configuration of the head portion in FIG. 1 (shown in a state engaged with a fuel assembly). [Figure 6D] FIG. 6D is a cross-sectional view taken along the line AA in FIG. 6C. [Figure 6E] FIG. 6D is a cross-sectional view taken along the arrow BB in FIG. 6C. [Figure 6F] FIG. 6D is a cross-sectional view taken along the arrow CC in FIG. 6C. [Figure 6G] FIG. 6D is a cross-sectional view taken along the arrow DD in FIG. 6C. [Figure 6H] FIG. 6D is an enlarged view of the tip of the head part of FIG. 6C. [Figure 7A] 2A and 2B are diagrams showing step (1) of the assembly procedure for the channel fastener handling device in Fig. 1, illustrating the assembly process of the reinforcing frame top and the swivel device. (a) is a plan view, and (b) is a sectional front view. [Figure 7B] 1. This figure shows step (2) of the assembly procedure for the channel fastener handling device in FIG. 1, showing the step of attaching a rotating guide plate to the bottom of the rotating part. (a) is a plan view, and (b) is a cross-sectional front view. [Figure 7C] 1. FIG. 4 is a front view showing step (3) of the assembly procedure for the channel fastener handling device of FIG. 1, and is a cross-sectional front view showing the step of attaching the swivel portion 70 to the swivel device 68. [Figure 7D] FIG. 2 is a front view showing step (4) of the assembly procedure for the channel fastener handling device of FIG. 1, illustrating the step of connecting the shank and head to the base to complete the entire device. [Figure 8]2 is a block diagram showing an outline of a control system (a control system for the entire system configuration in FIG. 2) for removing a channel fastener using the channel fastener handling device in FIG. 1. FIG. [Figure 9A] FIG. 2 is a side view showing the mock fuel rack used in the test of the channel fastener removal operation using the channel fastener handling device of FIG. 1 and the upper structure of the mock fuel assembly stored in the mock fuel rack. [Figure 9B] FIG. 9B is a plan view corresponding to FIG. 9A. [Figure 10A] FIG. 9C is a side view showing the configuration of the channel fastener of FIGS. 9A and 9B. [Figure 10B] FIG. 10B is a plan view corresponding to FIG. 10A. [Figure 11] 9A and 9B using the system configuration of FIG. 2 having the channel fastener handling device of FIG. 1 and the control system of FIG. 8. FIG. [Figure 12A] Figures 12A to 12C are sectional front views showing the operation of the head portion of the channel fastener handling device in the removal operation of the channel fastener of Figure 11. Of these, Figure 12A shows the state after the guide plate has been positioned above the channel fastener and before it has been inserted into the gap between the fuel assembly and the fuel rack. [Figure 12B] 12B is a cross-sectional front view showing the operation subsequent to FIG. 12A, showing the state after the channel fastener handling device is lowered to insert the guide plate into the gap between the fuel assembly and the fuel rack, and the screw driving tool is fitted onto the screw head, before being locked by the sleeve. [Figure 12C] 12C is a sectional front view showing the operation subsequent to FIG. 12B, in which the air cylinder is driven in the extension direction to move the sleeve to a lower position, thereby locking the engagement between the screw driving tool and the screw head. [Figure 13] 12 is a diagram showing the operation of the fiber sensor in the removal operation of the channel fastener in FIG. 11, showing the positional relationship between the fiber sensor and the sensor dog. [Figure 14]12 is a photograph showing the state when the screw-driving tool at the head of the channel fastener handling device is engaged with the fixing screw of the channel fastener and the engagement is locked in the operation of FIG. 11. [Figure 15] FIG. 1 is a diagram showing a conventional channel fastener handling device described in Patent Document 1. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will be described below, in which a channel fastener handling device according to the present invention is used for removing channel fasteners.

[0017] <<Description of the layout of the channel fastener handling device in the reactor building when in use and the general configuration of the device>> FIG. 2 shows a schematic overview of the arrangement of a channel fastener handling device 60 according to this embodiment within a reactor building 40. Rails 46, 46 are laid on both sides of a fuel pool 44 (spent nuclear fuel storage pool) on the floor 42 within the reactor building 40. A fuel rack 45 is installed submerged within the fuel pool 44. Fuel assemblies 47 are stored in the fuel rack 45 so that they can be moved in and out. A crane travel unit 48 is arranged on the rails 46, 46 by motor drive and movable along the rails 46, 46 in a direction perpendicular to the plane of the paper in FIG. 2. The crane travel unit 48 has a gate-shaped configuration consisting of left and right legs 50, 50 and a girder 52 stretched horizontally between the tops of the legs 50, 50. The crane travel unit 48 is supported on the rails 46, 46 by wheels 50a, 50a attached to the lower ends of the legs 50, 50. A hoist 54 is disposed on the girder 52 so as to be movable in the left-right direction of the plane of FIG. 2 along the girder 52 by motor drive. A moving device, a hoisting device, etc. (not shown) are mounted on the hoist main body 54a. The moving device moves the hoist main body 54a along the girder 52 by motor drive. A wire rope 56 is suspended from the hoisting device. A hook block 58 is suspended from the wire rope 56. The hoisting device raises and lowers the hook block 58 by winding up and down the wire rope 56 by motor drive. A hook 58a is attached to the hook block 58. A hanging ring 62 at the top of the channel fastener handling device 60 is detachably hung on the hook 58a. As a result, the channel fastener handling device 60 is detachably suspended from the hook 58a in an orientation in which its longitudinal direction extends vertically.

[0018] The channel fastener handling device 60 has an external configuration in which, from top to bottom, a base 60A, a shaft 60B, and a head 60C are coaxially arranged in a line and assembled as a whole. The total length in the longitudinal direction (vertical direction) of the channel fastener handling device 60 is set to the length necessary to operate the channel fasteners attached to the top of the fuel assemblies 47 in the fuel rack 45, and is, for example, about 10 m.

[0019] The base 60A is equipped with a rotation motor, a screw rotation motor, etc. The head 60C is equipped with a screwdriver, a guide plate, a television camera, etc. The screwdriver fits into the head of the fixing screw of the channel fastener and rotates the fixing screw, loosening or tightening the fixing screw against the top of the fuel assembly 47 depending on the direction of rotation. The guide plate is used to guide the screwdriver to a position just above the fixing screw. The television camera is used by an operator to check the position of the guide plate relative to the fuel assembly 47 on an operation monitor (television monitor) during this guiding operation. The guide plate is also used to support the channel fastener handling device 60 on the fuel assembly 47 when the channel fastener handling device 60 is used for operation.

[0020] A coaxial assembly member 61 is disposed on the shaft portion 60B. The assembly member 61 includes three coaxial shaft members (described later in detail) arranged coaxially on the shaft portion 60B: a guide tube (engagement member), a screw operation rotation shaft, and a detection rod. The guide tube is rotated around its axis by the driving of a rotation motor, and the rotation is transmitted to a guide plate (engagement member). As a result, the guide plate rotates around its axis and is positioned in the rotation direction relative to the fuel assembly 47. The screw operation rotation shaft is inserted and supported by the guide tube and rotated around its axis by the driving of a screw rotation motor. The rotation of the screw operation rotation shaft is transmitted to a screwdriver that is coaxially coupled to the tip of the screw operation rotation shaft. As a result, the screwdriver rotates around its axis and rotates a fixing screw fitted to the screwdriver. The detection rod is inserted and supported by the screw operation rotation shaft, and is disposed so that its lower end can protrude a predetermined amount from the screwdriver (so that it can move in and out of a recess in the screwdriver) due to its own weight. The detection rod detects the completion of engagement of the fixing screw with the screwdriver and the completion of removal of the fixing screw from the fuel assembly during the operation of removing the channel fastener from the fuel assembly.

[0021] The shaft portion 60B has a reinforcing frame 63. The reinforcing frame 63 is arranged in a rectangular prism shape along the coaxial assembly 61, surrounding and supporting the coaxial assembly 61. The coaxial assembly 61 is supported by the reinforcing frame 63 so that it can pivot about its axis. The top of the reinforcing frame 63 is fixedly connected to the bottom plate 65b of the reinforcing frame top 65 of the base portion 60A. The guide tube of the coaxial assembly 61 can pivot relative to the reinforcing frame 63, but cannot be raised or lowered. The screw operation rotation shaft portion of the coaxial assembly 61 can rotate and rise and fall relative to the guide tube (however, a stopper is provided to prevent it from falling out in the downward direction). The detection rod of the coaxial assembly 61 can rise and fall relative to the screw operation rotation shaft portion (however, a stopper is provided to prevent it from falling out in the downward direction) and can rotate (however, it is not necessary for it to be non-rotatable). The rotation axis AX1 of the guide tube and the rotation axis AX2 of the screw operation rotation shaft portion are arranged coaxially.

[0022] When using the channel fastener handling device 60 to remove a channel fastener from a fuel assembly, as shown in FIG. 2, the entire head portion 60C and a portion of the shaft portion 60B up to a midpoint in the longitudinal direction are submerged in the fuel pool 44, while the base portion 60A is not submerged. In this embodiment, the hook 58a of the hoist 54 is attached to the hook block 58 so as not to rotate about the vertical axis. The hook block 58 itself is also suspended from the hoist body portion 54a so as not to rotate about the vertical axis. Therefore, the hanging ring 62 at the top of the channel fastener handling device 60 is also hung from the hook 58a so as not to rotate about the vertical axis. The reinforcing frame top 65 and reinforcing frame 63, which are connected and fixed to the hanging ring 62, are also unable to rotate about the vertical axis.

[0023] In Figure 2, a control panel 64 is installed on the floor 42. Various cables and hoses 66, such as electric cables, signal cables, and air hoses for driving and controlling the channel fastener handling device 60, are drawn out from the control panel 64 and led to the channel fastener handling device 60. The control panel 64 is connected to a touch panel operation panel located in an operation room (not shown). By operating the touch panel operation panel, an operator in the operation room can remotely control the channel fastener handling device 60 via the control panel 64. The crane travel unit 48 and hoist 54 can also be remotely controlled from the operation panel located in the operation room.

[0024] The operation of removing the channel fasteners of the fuel assembly 47 using the configuration shown in Figure 2 is generally performed as follows: The channel fastener handling device 60 is suspended from the hook 58a of the hoist 54. While watching the video from a television camera mounted at an appropriate location in the reactor building 40 and the head 60C of the channel fastener handling device 60, an operator in the control room moves the crane traveling mechanism 48 in a direction perpendicular to the plane of the drawing in Figure 2, moves the hoist 54 left and right on the plane of the drawing, and drives the hoist 54 to wind down, positioning the head 60C directly above the target fuel assembly 47 in the fuel rack 45. While watching the video from the television camera mounted on the head 60C, the coaxial assembly member 61 is rotated about its vertical axis to position the guide plate of the head 60C so that it can engage with a predetermined position on the fuel assembly 47 (here, the corner of the gap between the fuel assembly 47 and the fuel rack 45). The hoist 54 is further driven to wind down, inserting the guide plate into the gap, and the screwdriver in the head portion 60C is fitted into the fixing screw of the channel fastener attached to the fuel assembly. The screwdriver is rotated by driving the screw rotation motor in the base portion 60A, loosening the fixing screw. Once the fixing screw has been removed from the fuel assembly 47, the hoist 54 is driven to wind up, and the fixing screw is pulled out together with the channel fastener from the fuel assembly 47. The pulled channel fastener is collected in a collection box at a predetermined collection position.

[0025] <<Overall explanation of the channel fastener handling device>> The configuration of the channel fastener handling device 60 will be described in more detail. Figures 1A and 1B show the overall configuration of the channel fastener handling device 60 in its assembled state. Figure 1A is an elevation view (partially cross-sectional front view), and Figure 1B is a plan view. The structural components of each part of the channel fastener handling device 60 are composed of metal members, such as stainless steel. As described above, in Figure 1A, the channel fastener handling device 60 has a configuration in which, from top to bottom, a base 60A, a shaft 60B, and a head 60C are coaxially aligned and assembled together. The base 60A has a reinforcing frame top 65. The reinforcing frame top 65 has a disk-shaped top plate 65a and a bottom plate 65b of the same diameter. These top plate 65a and bottom plate 65b are interconnected by four pipes 65c arranged at equal intervals around the pivot axis AX1 to form a cage-like structure. The openings between the four pipes 65c are open. In the front view of FIG. 1A, the four pipes 65c are shown rotated 45 degrees around the pivot axis AX1 relative to the plan view of FIG. 1B for ease of viewing the devices mounted on the base 60A. The same applies to FIG. 7A and other figures described below. A cylindrical pivot guide tube 65d is fixed to the top of the bottom plate 65b, inscribed within the four pipes 65c. The pivot guide tube 65d faces the outer peripheral surface of a circular pivot guide plate 183 attached to the bottom of the pivot unit 70, with a small gap between them, to enable the pivot unit 70 to smoothly pivot within the internal space 65e surrounded by the four pipes 65c of the reinforcing frame top 65 (see FIG. 1C). In the base 60A, the pivot device 68 is disposed above the internal space 65e of the reinforcing frame top 65, and the pivot unit 70 is disposed below. The swivel unit 70 is suspended from the swivel device 68 and is arranged so that it can reversibly rotate within a predetermined angle range around the swivel axis AX1 relative to a fixed part (a part connected and fixed to the reinforcing frame top 65) of the swivel device 68 by driving a swivel motor 69 mounted on the swivel device 68. A swivel guide plate 183 of the swivel unit 70 is arranged floating above the bottom plate 65b of the reinforcing frame top 65.

[0026] A coaxial assembly member 61 extends downward from the swivel member 70 along the swivel axis AX1. The coaxial assembly member 61 is configured with three coaxially arranged shaft members (described in detail below) arranged in order from the outside: a guide tube 72 (engagement member), a screw operation rotation shaft portion 74, and a detection rod 76. The guide tube 72 is configured as a large-diameter round pipe-like tubular member, and the screw operation rotation shaft portion 74 is configured as a small-diameter round pipe-like tubular member. The detection rod 76 is further configured by fitting short round rod members into both ends of a small-diameter round pipe-like tubular member. However, the detection rod 76 can also be configured as a rod-shaped member (for example, a round rod-shaped member). The guide tube 72, the screw operation rotation shaft portion 74, and the detection rod 76 are configured as metal members such as stainless steel. The coaxial assembly 61 extends from the base 60A, through the shaft 60B, to the head 60C, a length necessary to operate the channel fasteners attached to the top of the fuel assemblies 47 (FIG. 2) in the fuel pool 44. The upper end of the guide tube 72 is fixedly connected to a fixed portion 102 (a structural portion suspended from the swivel device 68) of the swivel unit 70 at the base 60A. Therefore, when the swivel device 68 is driven, the coaxial assembly 61 (the entirety of the guide tube 72, screw operation rotating shaft 74, and detection rod 76) rotates integrally with the swivel unit 70 around the swivel axis AX1. The upper end of the screw operation rotating shaft 74 is rotatably supported by the swivel unit 70, and is driven by a screw rotation motor 71 mounted on the swivel unit 70 to reversibly rotate (however, in this case, only rotation in the direction to loosen the fastening screw is used) around a rotation axis AX2 (coaxial with the pivot axis AX1) relative to the guide tube 72, thereby rotating a screwdriving tool 78 (a socket-shaped tool having a recess that fits into the head of the fastening screw) coaxially connected and fixed to the lower end (located in the head unit 60C) of the screw operation rotating shaft 74. The screw operation rotating shaft 74 is also arranged to be movable along the rotation axis AX2 relative to the guide tube 72 so as to absorb the axial movement of the fastening screw when loosening it. The detection rod 76 is arranged to be movable along the rotation axis AX2 relative to the screw operation rotating shaft 74.That is, the detection rod 76 moves downward under its own weight and advances to a predetermined position in the recess of the screwdriving tool 78, and is then pushed upward by the top surface of the screw head of the fixing screw that fits into the screwdriving tool 78, causing it to move back and be pushed out of the recess of the screwdriving tool 78.

[0027] In FIG. 1A, a reinforcing frame 63 is connected and fixed to the bottom plate 65b of the reinforcing frame top 65. The reinforcing frame 63 is divided into multiple reinforcing frame segments 63-1 to 63-4 in the longitudinal direction, which can be connected and disassembled with screws and nuts. Accordingly, the portion of the coaxial assembly 61 located in the shaft portion 60B is also divided into multiple coaxial assembly segment segments 61-1 to 61-4 in the longitudinal direction, which can be connected and disassembled with each other. This facilitates transport to and assembly of the coaxial assembly 61 and the reinforcing frame 63 at the work site. The coaxial assembly 61 also has a coaxial assembly segment 61-0 located in the base portion 60A and a coaxial assembly segment 61-5 located in the head portion 60C. The coaxial assembly member segments 61-0 to 61-5 are connected to each other (non-rotatably connected) by, for example, couplers (connecting fittings that allow a detachable connection through the fitting of a plug and socket) at their screw-operated rotating shafts 74, and by, for example, ferrule joints (joints that connect the ferrules at the ends of the guide tubes 72 by fastening them with a clamp band with a ferrule gasket sandwiched between them). The use of couplers and ferrule joints makes it easy to connect the coaxial assembly member segments 61-0 to 61-5 to each other on-site. The detection rods 76 of the coaxial assembly member segments 61-0 to 61-5 are not connected to each other; they are simply positioned with their end faces butted together under their own weight.

[0028] Each reinforcement frame segment 63-1 to 63-4 is constructed by assembling rods into a rectangular prism shape. A coaxial assembly member support plate 80 is attached to each reinforcement frame segment 63-1 to 63-4 midway along its length. The front view of the coaxial assembly member support plate 80 is shown in FIG. 1D (a cross-sectional view taken along the arrow B in FIG. 1A). The coaxial assembly member support plate 80 has two rectangular plates 80-1 and 80-2. The plates 80-1 and 80-2 are attached to the reinforcement frame segments 63-1 to 63-4 by butting one side of each plate against the other and screwing them to the reinforcement frame segments 63-1 to 63-4. A circular hole 80a is drilled in the center of the coaxial assembly member support plate 80. The coaxial assembly member 61 is rotatably inserted through the circular hole 80a. As a result, the coaxial assembly member 61 is rotatably supported at a central position (on the central axis of the reinforcing frame 63) in a direction perpendicular to the axis of the reinforcing frame 63. A notch 80b is formed in the coaxial assembly member support plate 80 in a portion of the circumference of the circular hole 80a, connecting to the circular hole 80a. This notch 80b is for passing signal cables (such as video signals from a television camera 84, described later, and detection signals from a proximity switch 175) connecting the base 60A and the head 60C, and air hoses (hoses that supply air to an air cylinder 171, described later) as needed. Instead of passing the signal cables and air hoses through the notch 80b, they can also be secured to the reinforcing frame 63 with lock ties (cable ties) or the like. In addition, the suspension ring 88 attached to the side of the reinforcing frame 63 at a midpoint in the longitudinal direction is provided so that after the channel fastener handling device 60 has been assembled horizontally on site, a hook 58a can be hung on the suspension ring 62 at the top of the channel fastener handling device 60 and the channel fastener handling device 60 can be gradually raised and lifted up with the hoist 54 and dropped into the fuel pool 44 by hanging a chain block on this suspension ring 88 on the side.

[0029] 1A, the head unit 60C includes a screwdriver 78, two guide plates 82 (engagement portion), and two television cameras 84 (underwater cameras) at the lower end of the coaxial assembly 61. The screwdriver 78 is coaxially connected and fixed to the lower end of the screw operation rotation shaft 74. The two guide plates 82 are connected and fixed to the lower end of the guide tube 72, positioned perpendicular to each other when viewed in the axial direction of the pivot axis AX1. Each television camera 84 is positioned diagonally above the corresponding guide plate 82 so as to be able to capture images of the corresponding guide plate 82 and its surroundings. The television cameras 84 are attached to the guide tube 72 via a bracket-like mount 86. As will be described later, the guide plates 82 function as guides (guiding members) for positioning the screwdriver 78 directly above the fixing screws 213 (FIG. 12A). In addition, after the guide plate 82 is inserted into the gap 208 between the fuel assembly 47 and the fuel rack 45 (Figures 12B and 12C), it functions as a support member that enables work to be performed with the lower part of the channel fastener handling device 60 stably supported on the upper part of the fuel assembly 47 or the upper part of the fuel rack 45.

[0030] <<Explanation of each part of the channel fastener handling device>> ◎Swivel 68: The configuration of the swivel device 68 is shown in Figures 3A to 3C. Figure 3A shows a schematic configuration, while Figures 3B and 3C show detailed configurations. In Figure 3A, the swivel device 68 has a fixed part 90 (structural part) that is fixed to the top plate 65a (Figure 1A) of the reinforcing frame top 65. A hanging ring 62, to which a hook 58a (Figure 2) of the hoist 54 is hung, is fixed to the center of the upper surface of the fixed part 90. A driven spur gear 92 is rotatably supported on the lower surface of the fixed part 90 with its rotation axis aligned with the central axis (swivel axis AX1) of the fixed part 90. A swivel shaft rod 94 is connected to the lower surface of the driven spur gear 92 and is attached to the rotation axis. A connecting block 96 is connected and fixed to the lower end of the swivel shaft rod 94. A horizontal plate member 106c (Figure 4A) of a hanger 106 of the swivel part 70, which will be described later, is inserted into a slit 96a opening downward in the connecting block 96. A round bar key 97 is inserted into a circular key hole 96b formed through the connecting block 96 between both side surfaces across the slit 96a and a key hole 106d (FIG. 4A) in the horizontal plate 106c. This connects the swivel unit 70 to the swivel device 68.

[0031] In Figure 3B, a swing motor 69 is fixed to the underside of the fixed part 90 of the swing device 68. A geared motor is used as the swing motor 69. A drive spur gear 98 is attached to the output shaft of the swing motor 69. The drive spur gear 98 meshes with a driven spur gear 92. As a result, when the swing motor 69 is driven, the connecting block 96 swings around the swing axis AX1 via the driven spur gear 92. This swing range is restricted to ±60 degrees by two limit switches 100 (see Figure 3C). The swing range is restricted because, during the channel fastener removal operation, the channel fastener handling device 60 as a whole is suspended from the hoist 54 so that it cannot swing freely (as shown in Figure 2). That is, when positioning the channel fastener handling device 60 relative to the fuel assembly 47, if the rotation angle is initially set to 0 degrees, the rough positions of the rotation directions of the two guide plates 82 (FIG. 1A) relative to the fuel assembly 47 are determined, and if the guide plates 82 are allowed to rotate within a limited range (allowing for fine adjustment), the guide plates 82 can be engaged with a predetermined position on the top of the fuel assembly 47 (the corner of the gap between the fuel assembly 47 and the fuel rack 45).

[0032] ◎Swivel section 70: The configuration of the swivel unit 70 is shown in Figures 4A to 4D. Figure 4A shows a schematic configuration, while Figures 4B, 4C, and 4D show detailed configurations. In Figure 4A, the fixed section 102 (structural section) of the swivel unit 70 has a structure in which a hanger 106 is attached to a common base 104. The hanger 106 has left and right vertical plate members 106a and 106b fixed to the common base 104, and a horizontal plate member 106c fixed to span the upper parts of the vertical plate members 106a and 106b. A circular keyhole 106d is formed in the longitudinal center of the horizontal plate member 106c at a position that passes through the swivel axis AX1. The horizontal plate 106c is inserted into the slit 96a of the connecting block 96 of the swivel device 68 (Fig. 3A), and the round key 97 is inserted through the key holes 96b and 106d, thereby connecting the swivel unit 70 to the swivel device 68. As a result, the swivel unit 70 is driven by the swivel device 68 and can be rotated around the swivel axis AX1 within a rotation angle range of ±60 degrees.

[0033] In FIG. 4B , the guide tube 72 is disposed coaxially with the pivot axis AX1. The upper portion of the guide tube 72 penetrates the center of the common base 104 and is fixed to the common base 104 at the penetration position. A screw operation rotation shaft 74 is inserted and supported in the guide tube 72 so as to be rotatable about the axis and movable in a direction along the axis. Rotation of the screw operation rotation shaft 74 about the axis rotates the fixing screw 213 of the channel fastener 211 (FIGS. 10A and 10B). The axial movement of the fixing screw that inevitably occurs as the fixing screw 213 is rotated is absorbed by movement of the screw operation rotation shaft 74 along the rotation axis AX2 relative to the fixed portion 102 of the swivel unit 70. A driven spur gear 111 is connected and fixed to the top of the screw operation rotation shaft 74 so as to be coaxial with the screw operation rotation shaft 74. A detection rod 76 is inserted and supported in a cavity 147 formed on the central axis of the screw operation rotation shaft portion 74 so as to be movable in a direction along the central axis. The upper part of the detection rod 76 passes through a driven spur gear 111, and a sensor dog 113 (see FIG. 4A) is fixed to the top of the detection rod 76. Two pairs of fiber sensors 115, 117 (see FIG. 4A) are fixedly arranged in two upper and lower stages on the common base 104. That is, a sensor base 119 is fixed to the upper surface of the common base 104 (FIGS. 4B to 4D), and a high sensor mount 121 and a low sensor mount 123 (FIG. 4D) are fixed to the sensor base 119. The high sensor mount 121 and the low sensor mount 123 are respectively equipped with fiber sensors 115, 117 (FIG. 4A). The fiber sensors 115, 117 are arranged with their light-emitting and light-receiving sections facing each other across the sensor dog 113. A slit 113a is formed in the middle of the sensor dog 113 in the vertical direction. The optical paths of the fiber sensors 115, 117 are blocked by the sensor dog 113, but when the detection rod 76 moves up and down in accordance with the movement of the detection rod 76 in the vertical direction, the optical paths of the fiber sensors 115, 117 are transmitted at two positions, upper and lower, where the slit 113 faces the fiber sensors 115, 117.During the operation of removing the channel fastener, the fiber sensors 115, 117 detect whether the optical paths are blocked or transmitted, thereby detecting that the screwdriver 78 has engaged with the screw head 213a of the fixing screw 213 and that the fixing screw has been removed from the fuel assembly 47. This detection operation will be described later (FIG. 13).

[0034] In FIG. 4B , two balance cylinders 108 are fixed to the upper surface of the common base 104 at symmetrical positions across the pivot axis AX1. The balance cylinders 108 cancel the weight of the screw operation rotating shaft 74 acting on the fixing screw 213 during the channel fastener removal operation, allowing the fixing screw 213 to be turned with a light force using the screwdriver 78. In this example, the balance cylinders 108 are diaphragm cylinders. A thrust bearing 125 is coaxially disposed below the driven spur gear 111. The upper washer of the thrust bearing 125 is connected to the underside of the driven spur gear 111. The lower washer of the thrust bearing 125 is connected to the tip of the piston rod 108a of the balance cylinder 108. As a result, the driven spur gear 111 is supported on the balance cylinder 108 so that it can move up and down and rotate around the pivot axis AX1 in response to the extension and contraction of the piston rod 108a of the balance cylinder 108. Since the driven spur gear 111 and the screw operation rotation shaft portion 74 are interconnected, the movement of the driven spur gear 111 is transmitted directly to the screw operation rotation shaft portion 74, and the screw operation rotation shaft portion 74 rises and falls and rotates in conjunction with the rise and fall and rotation of the driven spur gear 111.

[0035] 4A and 4B, a motor stand 127 is fixed upright on the upper surface of the common base 104. A screw-rotating motor 71 is mounted on the motor stand 127. A torque-controlled servo motor is used as the screw-rotating motor 71 here. A drive spur gear 131 is connected to the output shaft of the screw-rotating motor 71 via a coupling 129. The drive spur gear 131 meshes with the driven spur gear 111. As a result, when the screw-rotating motor 71 is driven, the screw operation rotation shaft 74 coaxially connected to the driven spur gear 111 rotates, which in turn rotates the screw driving tool 78 coaxially connected to the lower end of the screw operation rotation shaft 74, which in turn rotates the fixing screw 213 fitted in the screw driving tool 78. The drive spur gear 131 is formed with an axial length longer than the axial length of the driven spur gear 111 so that the engagement between the drive spur gear 131 and the driven spur gear 111 is maintained regardless of the elevation position of the driven spur gear 111 (see Figures 4A and 4D).

[0036] 4B, terminal box 101, solenoid valve 103, etc. are mounted on common base 104. Pressure reducing valve 105 (regulator), precision pressure reducing valve 200 (precision regulator), stacked signal light (warning light) 107, etc. are mounted on hanger 106. Pressure reducing valve 105 adjusts the pressure of air supplied to air cylinder 171 (described later), and solenoid valve 103 switches the drive direction (extension direction, retraction direction) of the air cylinder. Precision pressure reducing valve 200 precisely adjusts the pressure of air supplied to balance cylinder 108 to cancel the weight of screw operation rotation shaft 74 acting on fixing screw 213.

[0037] ◎ Coaxial assembly member 61: FIG. 5A shows the configuration of one of the coaxial assembly member segments 61-1 to 61-4 present on the shaft portion 60B of the coaxial assembly member 61. Each of the coaxial assembly member segments 61-1 to 61-4 has a configuration in which, from the outside in, a guide tube 72, a screw operation rotating shaft portion 74, and a detection rod 76 are coaxially arranged. Ferrules 132 are formed at both axial ends of the guide tubes 72. Axially adjacent guide tubes 72 are connected by butting the ferrules 132 together with a gasket sandwiched between them and fastening them with a clamp band 134. Near both axial ends of the internal space 72a of the guide tubes 72, plain bearings 133 are immovably held by plain bearing retainers 135 and 137. The screw operation rotating shaft portion 74 is inserted coaxially into the internal space 72a of the guide tube 72, with both axial ends slidably supported by the plain bearings 133. The screw operation rotation shaft portion 74 is slidable on the plain bearing 133, and is rotatable about its axis relative to the guide tube 72 and is movable in the direction along the axis.

[0038] The screw operation rotation shaft 74 has a round pipe-shaped shaft main body 74a, round bar members 74b and 74c welded to both ends of the shaft main body 74a, a socket 139a (female member) of a coupler 139 connected to the end of the upper round bar member 74b, and a plug 139b (male member) of the coupler 139 connected to the end of the lower round bar member 74c. In this case, a fluid coupler is used as the coupler 139. Axially adjacent coaxial assembly member segments 61-1 to 61-4 can be connected and disconnected with a single touch by fitting the socket 139a into the plug 139b. When the socket 139a and plug 139b are mated, the socket 139a and plug 139b cannot rotate relative to each other due to the engagement of half-round pipe-shaped anti-rotation pieces 143a (one semicircular portion) and 143b (the other semicircular portion) of the same diameter formed on the mating portions of the socket 139a and plug 139b. As a result, the coaxial assembly member divided parts 61-1 to 61-4 are integrated and cannot rotate relative to each other when connected by the coupler 139, ensuring that the rotation of the screw rotation motor 71 can be reliably transmitted to the screw driving tool 78 at the lower end of the coaxial assembly member 61. A circumferential groove is formed on the upper outer surface of the upper round rod member 74b, and a retaining ring 141 is fitted and fixed in this groove. The retaining ring 141 forms the large diameter portion of the round bar member 74b, and when the coaxial collective member divided parts 61-1 to 61-4 are handled individually (in an unconnected state) before connection or after disassembly, the retaining ring 141 engages with the sliding bearing retainer 135 when the coaxial collective member divided parts 61-1 to 61-4 are erected, thereby preventing the screw operation rotation shaft part 74 from falling out of the guide tube 72.

[0039] Circular holes 145, 146 are formed on the central axes of the round bar members 74b, 74c, respectively. As a result, a cavity 147 is formed in the screw operation rotation shaft portion 74 that communicates between both ends. The detection rod 76 is inserted into the cavity 147. Small diameter portions 145a, 146a are formed in the circular holes 145, 146 at intermediate positions in the axial direction, respectively, and the detection rod 76 is loosely supported in the radial direction by the small diameter portions 145a, 146a. As a result, the detection rod 76 is supported so as to be movable axially relative to the screw operation rotation shaft portion 74 without significant rattle in the radial direction. A large diameter portion 76a is formed at the upper end of the detection rod 76. When the coaxial assembly member segments 61-1 to 61-4 are handled individually (unconnected) before connection or after disassembly, the large diameter portion 76a engages with the small diameter portion 145a when the coaxial assembly member segments 61-1 to 61-4 are held upright, preventing the detection rods 76 from falling out of the screw operation rotation shaft 74. The detection rods 76 of the coaxial assembly member segments 61-0 to 61-5 abut against each other at their ends due to their own weight, and all of the detection rods 76 rise and fall together relative to the screw operation rotation shaft 74.

[0040] Figure 5B shows the connection structure between coaxial assembly member segments 61-0 to 61-5 before they are connected. While the connection structure between coaxial assembly member segments 61-1 and 61-2 is shown here, the connection structure between the other coaxial assembly member segments is the same. Axially adjacent screw-operated rotating shafts 74, 74 are connected to each other with a single touch by mating the socket 139a and plug 139b of the coupler 139. After this connection, axially adjacent guide tubes 72, 72 are connected to each other by butting their ferrules 132 together with a gasket 149 between them and tightening them with clamp bands 134.

[0041] ◎Head section 60C: The configuration of the head unit 60C is shown in Figures 6A to 6H. Figures 6A and 6B show a schematic configuration, while Figures 6C to 6H show a detailed configuration. For convenience, in Figures 6A to 6H, the position of the proximity switch 175 may be shown as being rotated around the rotation axis AX1. Figure 6A shows the unlocked state (the state before the screw head is engaged with the screw driving tool, or the state after the screw head is engaged with the screw driving tool and before the engagement is locked; the screw head is not shown). Figure 6B shows the locked state (the state after the screw head is engaged with the screw driving tool and the engagement is locked; the screw head is not shown). In Figure 6A, two guide plates 82 are fixedly arranged in a hanging state at the lower end of the guide tube 72. The guide plates 82 are made of flat, rectangular metal plates made of, for example, stainless steel. The surfaces of the guide plates 82 are arranged parallel to the pivot axis AX1 and away from the pivot axis AX1. The upper ends of the guide plates 82 are fixed to the side of the guide tube 72 via a bracket-shaped hanger plate 151 (support plate). The lower ends of the guide plates 82 are free ends. The two guide plates 82 are arranged so that their surfaces are perpendicular to each other when viewed in the axial direction of the rotation axis AX1. This allows the two guide plates 82 to be inserted from above into the corners of the gap between the fuel assemblies and the fuel rack (the state shown in Figures 6C and 6G). Two television cameras 84 are fixedly mounted on the side of the guide tube 72. That is, each television camera 84 is positioned diagonally above the opposite guide plate 82 so that it can capture images of the guide plate 82 and its surroundings. The television cameras 84 are attached to the guide tube 72 via bracket-shaped mounts 86. The television cameras 84 are used to insert the guide plates 82 from above into the corners of the gap between the fuel assemblies and the fuel rack while checking the positional relationship between the guide plates 82 and the gap using images on a work monitor. After being inserted into the gap, the channel fastener handling device 60 is used to support the lower part of the device 60 on the upper part of the fuel assembly so that the screw driving operation can be performed stably.

[0042] In Figure 6H, a screwdriving tool 78 is fixedly disposed coaxially with the screwdriving shaft 74 at the lower end of the screwdriving shaft 74. The screwdriving tool 78 is disposed facing the external space (lower space) from the open end 74d at the lower end of the screwdriving shaft 74. A recess 77 (socket) that opens downward is formed in the screwdriving tool 78. The recess 77 has a back space 77a and an entrance space 77b. The back space 77a accommodates the screw head 213a of the fixing screw 213 of the channel fastener 211 (Figures 10A and 10B). Six fitting protrusions 78e (vertical protrusions) extending vertically are formed at equal intervals around the entire circumference of the peripheral wall surface of the back space 77a. The fitting protrusions 78e fit into fitting grooves 213d (vertical grooves, FIGS. 10A and 10B) formed in the outer wall surface of the screw head 213a of the fixing screw 213. This allows the fixing screw 213 to be rotated by the screwdriver 78. Holes 78b that house lock balls 79 (locking members, FIGS. 12A to 12C) are formed in a plurality of locations (3 to 4 locations) around the circumference at equal angular intervals on the side wall surface of the inlet space 77b. The lock balls 79 fit into lock grooves 213b (FIGS. 10A and 10B) of the fixing screw 213, and function to lock the fitted state between the screwdriver 78 and the screw head 213a.

[0043] In Figure 6H, a sleeve 153 is fitted around the outer periphery of the open end 74d of the screw operation rotary shaft 74 so as to be movable in the axial direction of the screw operation rotary shaft 74. A circumferential groove is formed on the outer periphery of the screw operation rotary shaft 74 above the sleeve 153, and a locking ring 154 is fitted into and fixed in this groove. The locking ring 154 acts as a stopper against the upward movement of the sleeve 153. The sleeve 153 operates a locking ball 79 at its lower end to switch between the unlocked state and the locked state (see Figures 12B and 12C). A bearing metal 155 is arranged coaxially with the guide tube 72 and fixed to the open end at the lower end of the guide tube 72. The sleeve 153 is inserted into the bearing metal 155 and is supported by the bearing metal 155 so as to be slidable in the axial direction.

[0044] 6A, a sleeve drive device 157 is attached to the outer periphery of the lower part of the guide tube 72. The sleeve drive device 157 drives the sleeve 153 in the axial direction relative to the guide tube 72, moving the sleeve 153 between an unlocked position (upward movement position) and a locked position (downward movement position). A rail 153a is formed extending around the entire periphery on the outer periphery of the upper end of the sleeve 153, where the acting portion (engagement rods 169a, 170a) of the sleeve drive device 157 acts. A rail 74e is formed extending around the entire periphery on the outer periphery of the screw operation rotation shaft portion 74, located slightly above the sleeve 153. In order to allow the engagement rods 169a, 170a of the sleeve drive device 157 to be engaged with the rails 153a, 74e, respectively, so that the engagement rods 169a, 170a can be raised and lowered relative to the guide tube 72, long holes 159, 161 that are long in the vertical direction are formed in the guide tube 72 to allow the engagement rods 169a, 170a to enter the internal space 72a of the guide tube 72.

[0045] The configuration of the sleeve drive device 157 will be described. In Fig. 6A, the sleeve drive device 157 has two tiers of upper and lower annular members 169, 170, each of which has an octagonal planar shape. The annular members 169, 170 are each disposed so as to surround the guide tube 72 without contacting it (see Figs. 6E and 6F). The annular member 169 moves up and down integrally with the screw operation rotation shaft portion 74, and the annular member 170 moves up and down integrally with the sleeve 153. The support structure of the annular members 169, 170 will be described. Two hollow guide posts 165 are fixedly disposed in a hanging state on the flange 163 of the guide tube 72 at diagonal positions across the rotation axis AX2. A guide shaft 167 is housed within the hollow interior of the guide post 165 via a sliding bearing so as to be able to move up and down freely.

[0046] An annular member 169 is connected to the lower end of the guide shaft 167. Two engagement rods 169a are fixed to the inner circumferential surface of the annular member 169, protruding in opposing directions (directions perpendicular to the rotation axis AX2) at diagonal positions across the rotation axis AX2. A guide roller 169b is attached to the tip of the engagement rod 169a so as to be rotatable around the axis of the engagement rod 169a. The guide roller 169b is inserted into the elongated hole 159 of the guide tube 72 and loosely engages with the inner circumferential space of the rail 74e of the screw operation rotation shaft 74. The guide roller 169b abuts against the bottom or ceiling surface of the inner circumferential space and rotates in response to the rotation of the screw operation rotation shaft 74 around the central axis AX2. When the screw operation rotation shaft 74 moves up and down relative to the guide tube 72, the annular member 169 also moves up and down via the engagement rods 169a engaged with the rail 74e.

[0047] Two air cylinders 171 are attached to the underside of the annular member 169 on extensions of the two guide shafts 167. The annular member 170 is connected to the lower end of the piston rod 171a of each air cylinder 171. Two engagement rods 170a are fixed to the inner circumferential surface of the annular member 170, protruding in directions facing each other (directions perpendicular to the rotation axis AX2) at diagonal positions across the rotation axis AX2. Guide rollers 170b are attached to the ends of the engagement rods 170a so as to be rotatable around the axis of the engagement rods 170a. The guide rollers 170b are inserted into the elongated holes 161 of the guide tube 72 and loosely engage with the inner circumferential space of the rail 153a of the sleeve 153. The guide rollers 170b abut against the bottom or ceiling surface of the inner circumferential space and rotate in response to the rotation of the sleeve 153 around the central axis AX2 of the screw operation rotation shaft 74 in the same direction. When the air cylinder 171 expands and contracts, the annular member 170 rises and falls relative to the upper annular member 169. When the annular member 170 rises and falls, the sleeve 153 also rises and falls together via the engagement rod 170a engaged with the rail 153a.

[0048] When the air cylinder 171 is retracted (the state shown in FIG. 6A ), the sleeve 153 is positioned at an unlocked position, where it has moved upward relative to the screw operation rotation shaft 74. When the air cylinder 171 is extended (the state shown in FIG. 6B ), the sleeve 153 is positioned at a locked position, where it has moved downward relative to the screw operation rotation shaft 74. Furthermore, when the screw operation rotation shaft 74 is rotated to loosen the fixing screw 213 while the sleeve 153 is in the locked position, the screw operation rotation shaft 74 rises relative to the guide tube 72 as the fixing screw 213 rises. At this time, the sleeve 153 remains in the locked position (the air cylinder 171 remains extended), and the annular members 169 and 170 rise together with the screw operation rotation shaft 74. At this time, the rise of the annular members 169 and 170 is absorbed by the rise of the guide shaft 167 relative to the guide post 165.

[0049] In FIG. 6A, a lock / unlock detector 173 is disposed in the sleeve drive device 157, which detects whether the sleeve 153 is in the locked or unlocked position. The lock / unlock detector 173 has a proximity switch 175 and a sensor dog 177. The proximity switch 175 is attached to the annular member 169 via a sensor mount 174. The sensor dog 177 is composed of a long, plate-shaped metal piece. One end (base end) of the sensor dog 177 is rotatably supported by a horizontally extending pin 179 fixed to the annular member 169. The other end (free end) of the sensor dog 177 is inserted into a vertically extending elongated hole 174a formed in the sensor mount 174 so as to be movable up and down. When rotated upward, the other end of the sensor dog 177 faces the sensing surface of the proximity switch 175 ( FIG. 6B ). An elongated hole 177a is formed in the sensor dog 177 at a position closer to the one end than the pin 179. A pin 181 attached to the annular member 170 is inserted into the elongated hole 177a so as to be able to move freely along the elongated hole 177a. With the above configuration, when the air cylinder 171 is in a retracted position (a position where the gap between the annular members 169 and 170 is narrowed), the sensor dog 177 rotates downward and moves away from the sensing surface of the proximity switch 175 (FIG. 6A), and the unlocked state is detected. When the air cylinder 171 is in an extended position (a position where the gap between the annular members 169 and 170 is widened), the sensor dog 177 rotates upward and faces the sensing surface of the proximity switch 175 (FIG. 6B), and the locked state is detected.

[0050] <<Explanation of the assembly procedure for the channel fastener handling device>> A description will now be given of the procedure for assembling the above-described channel fastener handling device 60. The assembly work is carried out at the site where the channel fastener handling device 60 is to be used. Step (1): Assembling the reinforcing frame top 65 and the swivel device 68 (Fig. 7A) As shown in FIG. 7A, the swivel device 68 is attached to the reinforcing frame top 65 by fastening the fixing portion 90 of the swivel device 68 to the top plate 65a of the reinforcing frame top 65 with screws.

[0051] Step (2): Attaching the rotating guide plate to the bottom of the rotating part 70 (FIG. 7B) As shown in FIG. 7B, two swivel guide plates 183 are screwed to the bottom of the swivel unit 70 so that the swivel unit 70 can smoothly rotate in the internal space 65e (FIG. 7A(b)) surrounded by the four pipes 65c of the reinforcing frame top 65. The two swivel guide plates 183 are made of metal disks whose diameter is slightly smaller than the inner diameter of the swivel guide tube 65d (FIG. 7A(b)) of the reinforcing frame top 65, and are arranged coaxially with the swivel axis AX1 as shown in FIG. 7B(a). They are cut into three pieces by two parallel chords of the same length, and the center section is removed, forming the remaining two pieces. The coaxial assembly member 61 (61-0) is passed through the space left after the center section is removed.

[0052] Step (3): Assemble the swivel unit 70 to the swivel device 68 to complete the base 60A (FIG. 7C). As shown in Figure 7C, the swivel unit 70 assembled in step (2) is attached to the swivel device 68 assembled in step (1). This attachment is performed by placing the swivel unit 70 on the raising platform 185, excluding the coaxial assembly member 61 (61-0) protruding downward, and then placing the reinforcing frame top 65 with the swivel device 68 attached over the swivel unit 70 from above. The hanger 106 of the swivel unit 70 is then connected to the connecting block 96 of the pivot rod 94. That is, the horizontal plate 106c of the hanger 106 is inserted into the slit 96a (Figure 3A) of the connecting block 96, and the round key 97 (Figure 3A) is inserted through the keyholes 96b and 106d, thereby connecting the swivel unit 70 to the swivel device 68. This completes the base 60A of the channel fastener handling device 60.

[0053] Step (4): Connect the shaft 60B and head 60C to the base 60A to complete the whole assembly (Fig. 7D). As shown in FIG. 7D, the reinforcing frame top 65 and the reinforcing frame segments 63-1 to 63-4 are connected while the coaxial assembly member segments 61-0 to 61-5 are connected. This connects the base 60A, shaft 60B, and head 60C, completing the assembly of the channel fastener handling device 60. Step (4) is performed with each component of the channel fastener handling device 60 laid horizontally on the floor. Once assembly is complete, the hook 58a of the hoist 54 (FIG. 2) is attached to the hanging ring 62 at the top of the base 60A, and a separately prepared chain block is attached to the hanging ring 88 on the side of the reinforcing frame 63-3. The entire channel fastener handling device 60 is gradually raised and lifted by the hoist 54 and chain block, and then lowered into the fuel pool 44 (FIG. 2). Once the loading into the fuel pool 44 is complete, the channel fastener removal process begins.

[0054] <<Explanation of the control system for removing channel fasteners>> FIG. 8 shows an overview of the control system (the control system for the entire system configuration in FIG. 2) for the channel fastener removal operation using the channel fastener handling device 60. A touch panel operation panel 187 is located in the operation room and operated by an operator. A Mitsubishi Electric GOT (Graphic Operation Terminal, registered trademark) can be used as the touch panel operation panel 187. The control panel 64 (FIG. 2), an operation monitor 189, a data logger 190, and other components are connected to the touch panel operation panel 187. Images captured by a television camera 84 mounted on the head unit 60C of the channel fastener handling device 60 are displayed on the operation monitor 189. The operator remotely controls the device by viewing this image. The data logger 190 records various data during the operation. A crane operation panel 180 and a hoist operation panel 182 are also located in the operation room adjacent to the touch panel operation panel 187. The operator remotely controls the crane travel unit 48 and the hoist 54 (FIG. 2), respectively, using the crane operation panel 180 and the hoist operation panel 182. Workers can check the operation of the crane travelling unit 48 and hoist 54 by watching images captured by television cameras placed at appropriate locations within the reactor building 40 and displayed on television monitors placed near the crane control panel 180 and hoist control panel 182.

[0055] A power supply 195 and an air compressor 197 are connected to the control panel 64. The control panel 64 receives inputs such as detection signals from two limit switches 100 that define the rotation range of the rotation device 68, detection signals from fiber sensors 115 and 117 that detect when the screwdriver 78 is engaged with the fixing screw 213 and when the fixing screw 213 is disengaged from the fuel assembly 47, torque detection signals from the torque control servo motor constituting the screw rotation motor 71, detection signals from a proximity switch 175 that detects the unlocked and locked positions of the sleeve 153, and video signals from a television camera 84 that confirms the positional relationship between the guide plate 82 and the gap between the fuel assembly and the fuel rack when the guide plate 82 is inserted from above into the corner of the gap. The control panel 64 outputs drive power for the rotation motor 69, drive power for the screw rotation motor 71, and drive air for the air cylinder 171 and balance cylinder 108 that drive the sleeve 153 to the unlocked and locked positions. The driving air for the air cylinder 171 is supplied to the air cylinder 171 via a pressure reducing valve 105 (regulator) and a solenoid valve 103 (air directional switching solenoid valve). The driving air for the balance cylinder 108 is supplied to the balance cylinder 108 via a precision pressure reducing valve 200 (precision regulator). The control panel 64 is equipped with a control device 199 that controls each part of the channel fastener handling device 60.

[0056] <<Channel fastener removal procedure>> The removal of the channel fasteners using the channel fastener handling device 60 will now be described. First, the upper structure of the fuel rack and fuel assembly, and the configuration of the channel fasteners will be described. Figures 9A and 9B show the upper structure of the fuel rack 45 and fuel assembly 47. Note that these figures show the mock fuel rack and mock fuel assembly used in the removal test. A fuel assembly 47 is housed in one storage space 45a of the fuel rack 45. A handle 47a is attached to the top of the fuel assembly 47. A channel fastener 211 is attached to the upper corner of the channel box 47b, which forms the outer shell of the fuel assembly 47, with a fixing screw 213. As a result, the fuel assembly 47 is supported on the inner wall surface of the storage space 45a of the fuel rack 45 via the leaf spring 217 of the channel fastener 211. In this state, gaps 208 are formed on two sides between the fuel assembly 47 and the fuel rack 45. In the operation of removing the channel fastener, the two guide plates 82 at the lower end of the channel fastener handling device 60 are inserted into the gaps 208 on the two sides, respectively.

[0057] The configuration of the channel fastener 211 is shown in Figure 10. As is well known, the channel fastener 211 has a configuration in which a leaf spring 217 is assembled to a guard 215 with a fixing screw 213. The channel fastener 211 fastens the channel box 47b and the fuel assembly 47 by screwing the fixing screw 213 into the upper tie plate of the fuel assembly 47 through a threaded hole in the upper triangular corner plate of the channel box 47b of the fuel assembly 47 (Figures 9A and 9B). The channel fastener 211 is removed from the channel box 47b and the fuel assembly 47 by loosening the fixing screw 213. In other words, when the fixing screw 213 is grasped and pulled up, the entire channel fastener 211 is pulled up together. The fixing screw 213 has, from top to bottom, a screw head 213a, a lock groove 213b, and a screw shank 213c. On the outer peripheral surface of the screw head 213a, six fitting grooves 213d (vertical grooves) into which fitting protrusions 78e of a tool (screw driving tool 78 of the channel fastener handling device 60, see FIG. 6H) fit are formed at equal intervals around the entire circumference. A lock ball (FIGS. 12A to 12C) arranged on the screw driving tool 78 fits freely in the lock groove 213b. A thread groove is formed on the screw shank 213c so that it screws into a threaded hole in the channel box 47b. As can be seen from FIG. 10A, the portion of the screw shank 213c where the thread groove is formed has a larger diameter than the smaller diameter portion above it. Therefore, when the fixing screw 213 is grasped and pulled up for the channel fastener 211 alone, the guard 215 is caught on the steps between the smaller diameter portion and the larger diameter portion and does not fall off the fixing screw 213, so the entire channel fastener 211 is pulled up together.

[0058] 2 and 8 having the channel fastener handling apparatus 60 according to the present invention, an example of a series of operations for removing a channel fastener 211 from the arrangement shown in FIGS. 9A and 9B will be described with reference to FIG. 11. First, the channel fastener handling apparatus 60 is assembled horizontally according to the procedures shown in FIGS. 7A to 7D (S1). Air piping and electrical wiring are connected between the channel fastener handling apparatus 60 and the control panel 64 (S2). The touch panel operation panel 187, work monitor 189, touch panel operation panel 187, etc. are connected to the control panel 64 (S3). The hoist 54 is operated to raise the channel fastener handling apparatus 60 vertically (S4). The crane travel section 48 and the hoist 54 are moved to position the hoist 54 directly above the fuel assembly 47 to be operated, and then the hoist 54 is operated to lower the channel fastener handling apparatus 60 (S5). The positions of the fuel rack 45 and channel fasteners 211 are confirmed using the image from the television camera 84 displayed on the operation monitor 189 (S6). The swing motor 69 is operated to swing the guide tube 72 (S7). Once it is confirmed from the image on the operation monitor 189 that the two guide plates 82 at the lower end of the guide tube 72 have reached a swing position where they can be inserted into the gaps 208 (Figure 9B) on two sides between the fuel assembly 47 and the fuel rack 45, the swing motor 69 is stopped and the guide plates 82 are positioned there (S8). The state at this point is shown in Figure 12A. The air cylinder 171 is retracted, and the sleeve 153 is in the unlocked position where it is locked by the locking ring 154.

[0059] From this state, the hoist 54 is operated to lower the channel fastener handling device 60. When it is confirmed from the image on the operation monitor 189 that the two guide plates 82 have entered the gaps 208 on two sides, the hoist 54 is stopped and the descent of the channel fastener handling device 60 is temporarily halted (S9). At this time, the screw driving tool 78 at the lower end of the screw operation rotating shaft 74 has not yet reached the fastening screw 213. The torque and rotation speed of the screw turning motor 71 (torque control servo motor) are set to low values ​​(S10). The screw turning motor 71 is started at the set low torque and low rotation speed in the direction to loosen the fastening screw 213 (S11), and the hoist 54 is gradually lowered (S12). Then, the lower end surface 76b of the detection rod 76 abuts against the top surface of the screw head 213a of the fastening screw 213, and the screw head 213a enters the recess 77 of the screw driving tool 78 while pushing up the detection rod 76. Then, at a rotational position where the fitting groove 213d of the fixing screw 213 and the fitting protrusion 78e of the screwdriver 78 are aligned, the screw head 213a of the fixing screw 213 begins to fit into the inner space 77a of the recess 77 of the screwdriver 78. At this time, the guide plate 82 momentarily moves in the reaction force direction, which can be confirmed on the work monitor 189, so the worker watches this movement and temporarily stops the screw rotation motor 71. From this state, the hoist 54 is slightly lowered to gradually lower the channel fastener handling device 60. As the channel fastener handling device 60 descends, the screw head 213a penetrates deeper into the inner space 77a of the recess 77 of the screwdriver 78. Accordingly, the detection rod 76 is pushed up further. When the fiber sensors 115, 117 (FIG. 4A) of the swivel unit 70 detect via the detection rod 76 that the screw head 213a has fully fitted into the inner space 77a of the recess 77 of the screwdriver 78, the seating confirmation lamp on the touch panel operation panel 187 is turned on. When the seating confirmation lamp is turned on, the operator stops the fine-lowering operation of the hoist 54 (S13). The screwdriver 78 is now in a seated state in which it is fitted into the screw head 213a of the fixing screw 213 (the state shown in FIG. 12B), and the fixing screw 213 can now be rotated by the screwdriver 78. The air cylinder 171 continues to be driven in a retracted state, and the sleeve 153 is in the unlocked position locked by the locking ring 154.

[0060] When the seating confirmation lamp is lit, a seating confirmation button is displayed on the touch panel operation panel 187. When the operator turns on the seating confirmation button in response to this (S14), a lock operation button is displayed on the touch panel operation panel 187. When the operator turns on the lock operation button in response to this, the air cylinder 171 is extended. As a result, the sleeve 153 moves downward away from the locking ring 154 and abuts against the lock ball 79, moving the lock ball 79 inward. As a result, the lock ball 79 engages with the lock groove 213b of the fixing screw 213, resulting in a locked state (a state in which the screwdriver 78 and the screw head 213a are not disengaged) (S15) (the state shown in FIG. 12C). The photograph in FIG. 14 shows the surroundings of the head portion 60C when this locked state is reached. The fact that the locked state has been reached is determined by a detection signal from the proximity switch 175, and the lock confirmation lamp on the touch panel operation panel 187 lights up to notify the operator.

[0061] Next, the operator switches the air valve of the balance cylinder 108 to "pressurize" (S16). This drives the balance cylinder 108, reducing the weight of the screw operation rotation shaft 74 acting on the fixing screw 213, allowing the screw operation rotation shaft 74 to easily rotate the fixing screw 213. Next, when the operator turns on the screw loosening command button on the touch panel operation panel 187, the screw rotation motor 71 is started at the upper limit of the rotation speed for the screw loosening operation and an initial low torque command value (S17). As a result, the operator checks the rotation speed of the screw rotation motor 71 displayed on the touch panel operation panel 187, and increases the torque command value so that the desired rotation speed is obtained (S18, S19). When the fiber sensors 115, 117 detect that the fixing screw 213 has been loosened and removed from the fuel assembly 47, the screw loosening confirmation lamp on the touch panel operation panel 187 lights up to alert the operator. When the loose screw check lamp lights up, a loose screw check button is displayed on the touch panel operation panel 187. In response to this, the operator turns on the loose screw check button (S21).

[0062] Thereafter, the worker operates the hoist 54 to raise the channel fastener handling device 60, and the channel fastener 211 is extracted from the fuel assembly 47 (S22). The worker operates the hoist 54 and the crane traveling section 48 to transport the extracted channel fastener 211 to a recovery position (S23). When the channel fastener 211 arrives at the recovery position, the worker turns on the unlock operation button on the touch panel operation panel 187. This causes the air cylinder 171 to be retracted. As a result, the sleeve 153 moves upward, releasing the sleeve 153 from contact with the lock ball 79, and the lock ball 79 retracts to the outer periphery, releasing the locked state (S24). As a result, the screw driving tool 78 and the screw head 213a are no longer engaged, and the channel fastener 211 falls and is recovered in a recovery box.

[0063] The worker then saves and checks the data recorded in the data logger 190. Furthermore, the worker operates the hoist 54 to lift the channel fastener handling device 60 out of the fuel pool 44 (S26), places it on its side on the floor (S27), and disassembles it as necessary to complete the work (S28).

[0064] <<Explanation of the operation of the head unit and fiber sensor when removing a channel fastener>> The operation of the head portion and the fiber sensor in the above-described channel fastener removal operation will be described with reference to Figures 12A to 12C and 13. Note that Figures 12A to 12C illustrate the position and posture of the channel fastener 211 when attached to the fuel assembly 47, but the fuel assembly 47 is not shown. (1) After the guide plate is positioned and before it is inserted into the gap (Fig. 12A, Fig. 13(a)) 12A shows the state after the guide plate 82 has been positioned above the channel fastener 211 but before it is inserted into the gap 208 between the fuel assembly 47 and the fuel rack 45. When the guide plate 82 is positioned in the front-to-back, left-to-right, and rotational directions so that it can be inserted into the gap 208, the screwdriver 78 is positioned directly above the screw head 213a. That is, the positional relationship between the two guide plates 82 and the screwdriver 78 is set to achieve this position. The air cylinder 171 is in the retracted position, and the sleeve 153 is in the raised, unlocked position. The lower end surface 76b of the detection rod 76 protrudes into the recess 77 of the screwdriver 78 and has descended to a position approximately flush with the open end surface of the recess 77. That is, the detection rods 76 of each stage descend within the screw operation rotation shaft 74 under their own weight, but their descent is stopped at a position where the large-diameter portion at the upper end of the detection rod 76 (corresponding to large-diameter portion 76a in FIG. 5A) engages with the small-diameter portion of the circular hole in the screw operation rotation shaft 74 (corresponding to small-diameter portion 145a of circular hole 145 in FIG. 5A). At this time, the position of the lower end surface 76b of the lowest detection rod 76 is set to be roughly flush with the opening end surface of the recess 77 of the screw driving tool 78. The opposing surfaces of adjacent detection rods 76 (the lower end surface of the upper stage and the upper end surface of the lower stage) abut against each other, and the divided detection rod structure remains connected as a single rod. Figure 13(a) shows the positional relationship between the fiber sensors 115, 117 and the sensor dog 113 at this time. Note that the fiber sensors 115 and 117 are mounted on the fixed part 102 of the swivel part 70 (sensor base 119 fixed to the common base 104; see FIGS. 4A to 4C), and therefore do not move up and down relative to the fixed part 102 of the swivel part 70. In contrast, the screw operation rotation shaft part 74 and the detection rod 76 move up and down relative to the fixed part 102 of the swivel part 70. Furthermore, the detection rod 76 moves up and down relative to the screw operation rotation shaft part 74. In the state shown in FIG. 13(a), the optical path of the fiber sensor 115 is "blocked" by the sensor dog 113, and the optical path of the fiber sensor 117 is "transmitted" by the slit 113a. The detection signals of the fiber sensors 115 and 117 are input to a determination circuit (logic circuit) in the control device 199 (FIG. 8), and it is determined based on the combination of these detection signals that the screw driving tool 78 is not fitted into the screw head 213a.

[0065] (2) After the screwdriver is fitted onto the screw head, but before it is locked (Fig. 12B, Fig. 13(b)) Figure 12B shows the state after the channel fastener handling device 60 has been lowered by the hoist 54 from the state shown in Figure 12A, the guide plate 82 has been inserted into the gap 208 between the fuel assembly 47 and the fuel rack 45, and the screw driving tool 78 has been fitted into the screw head 213a, but before locking with the sleeve 153. The screw head 213a is fitted into the back space 77a of the screw driving tool 78. The air cylinder 171 remains in the retracted position, the sleeve 153 is in the upper position, and the lock ball 79 is not fitted into the lock groove 213b of the fixing screw 213. Figure 13(b) shows the positional relationship between the fiber sensors 115, 117 and the sensor dog 113 at this time. 13(a), the detection rod 76 is pushed up by contact with the top surface of the screw head 213a, and so the detection rod 76 moves upward relative to the fixed part 102 of the swivel part 70 (the height of the screw operation rotation shaft part 74 relative to the fixed part 102 of the swivel part 70 does not change). As a result, the optical path of the fiber sensor 115 is "transmitted" by the slit 113a, and the optical path of the fiber sensor 117 is "blocked" by the sensor dog 113. The detection signals of the fiber sensors 115 and 117 are input to a determination circuit (logic circuit) in the control device 199 (FIG. 8), and it is determined that the screw driving tool 78 has fitted into the screw head 213a based on the combination of these detection signals.

[0066] (2) After locking (Fig. 12C, Fig. 13(b)) Figure 12C shows the state in which the air cylinder 171 is driven in the extension direction from the state shown in Figure 12B to move the sleeve 153 to a lower position. At this time, the sleeve 153 moves the lock ball 79 inward and engages it with the lock groove 213b of the fixing screw 213. This locks the engagement between the screw driving tool 78 and the screw head 213a. The positional relationship between the fiber sensors 115, 117 and the sensor dog 113 remains the same as in Figure 13(b).

[0067] (4) Complete loosening of the fixing screws (Figure 13(c)) From the state shown in FIG. 12B, the screw rotation motor 71 is driven to loosen the fixing screw 213 and remove it from the fuel assembly 47. FIG. 13(c) shows the relative positions of the fiber sensors 115, 117 and the sensor dog 113 when the fixing screw 213 has been removed from the fuel assembly 47. During the loosening operation, the fixing screw 213 is removed upward from the fuel assembly 47 while the screw driving tool 78 remains engaged with the screw head 213a. As a result, the detection rod 76 and the screw operation rotation shaft 74 move upward together compared to the state shown in FIG. 13(a). As a result, the optical paths of both fiber sensors 115, 117 are "blocked" by the sensor dog 113. The detection signals of the fiber sensors 115, 117 are input to a determination circuit (logic circuit) in the control device 199 (FIG. 8), and it is determined that the fixing screw 213 has been removed from the fuel assembly 47 based on the combination of these detection signals.

[0068] In the above embodiment, the channel fastener handling device of the present invention has been described as being used for removing channel fasteners, but it can also be used for installing channel fasteners. Also, in the above embodiment, electric motors are used as the turning motor and screw rotating motor 71, but this is not limiting and hydraulic motors, pneumatic motors, etc. can also be used. [Explanation of symbols]

[0069] 2...fuel assembly, 3...handle, 5...fuel rack, 6...channel fastener, 7...fixing screw, 9...hoist, 10...device body, 10a...guide, 11...swivel shaft, 13...swivel motor, 14...air cylinder, 15...shaft, 22...fastener clamping mechanism, 25...screw rotation motor, 27...screw driving tool, 28...steel ball, 30...channel fastener holder, 40...reactor building, 42...floor, 44...fuel pool, 45...fuel rack, 45a...storage space, 46...rail, 47...fuel assembly, 47a...handle, 47b...channel box, 48...Crane running part, 50...Leg, 50a...Wheel, 52...Girder, 54...Hoist, 54a...Main body, 56...Wire rope, 58...Hook block, 58a...Hook, 60...Channel fastener handling device, 60A...Base, 60B...Shaft, 60C...Head, 61...Coaxial assembly member, 61-0 to 61-5...Coaxial assembly member divided parts, 62...Suspension ring, 63...Reinforcing frame, 63-1 to 63-4...Reinforcing frame divided parts, 64...Control panel, 65...Reinforcing frame top, 65a...Top plate, 65b...Bottom plate, 65c...Pipe, 65d...Slewing girder Guide tube, 65e... internal space, 66... ​​various cables and hoses, 68... swivel device, 69... swivel motor, 70... swivel portion, 71... screw rotation motor, 72... guide tube (tubular member, engaging member), 72a... internal space, 74... screw operation rotation shaft portion, 74a... shaft portion main body, 74b, 74c... round bar member, 74d... opening end, 74e... rail, 76... detection rod, 76a... large diameter portion, 76b... lower end surface, 77... recess, 77a... back side space, 77b... entrance side space, 78... screw driving tool, 78b... hole, 78e... fitting protrusion, 79... lock ball (lock member), 80... coaxial assembly member support plate, 80-1, 80-2... plate, 80a... round hole, 80b... notch, 82... guide plate (engagement portion of engagement member), 84... television camera, 86... mount, 88... hanging ring, 90... fixed portion, 92... driven spur gear, 94... pivot rod, 96... connecting block, 96a... slit, 96b... key hole, 97... round bar key, 98... driving spur gear, 100... limit switch, 101... terminal box, 102... fixed portion, 103... solenoid valve, 104... common base (fixed portion), 105... pressure reducing valve, 106... hanger, 106a,106b...Vertical plate material, 106c...Horizontal plate material, 106d...Key hole, 107...Stacked signal light (warning light), 108...Balance cylinder, 108a...Piston rod, 111...Driven spur gear, 113...Sensor dog, 113a...Slit, 115, 117...Fiber sensor (position sensor), 119...Sensor base, 121, 123...Sensor mount, 125...Thrust bearing, 127...Motor stand, 129...Coupling, 131...Drive spur gear, 132...Ferrule, 133...Slide bearing, 134...Clamp band, 13 5,137...Slide bearing holder, 139...Coupler, 139a...Socket (female member), 139b...Plug (male member), 141...Prevention ring, 143a...Half-split round pipe-shaped anti-rotation piece (one side semicircular portion), 143b...Half-split round pipe-shaped anti-rotation piece (other side semicircular portion), 145...Circular hole, 145a...Small diameter portion, 146...Circular hole, 146a...Small diameter portion, 147...Cavity, 149...Gasket, 151...Hanging plate, 153...Sleeve, 153a...Rail, 154...Latching ring, 155...Bearing metal, 157...Sleeve drive device, 159, 161...oblong hole, 163...flange, 165...guide post, 167...guide shaft, 169, 170...annular member, 169a, 170a...engagement rod, 169b, 170b...guide roller, 171...air cylinder (sleeve drive part), 171a...piston rod, 173...lock / unlock detection device, 174...sensor mount, 174a...oblong hole, 175...proximity switch, 177...sensor dog, 177a...oblong hole, 179...pin, 180...crane operation panel, 181...pin, 182...hoist operation panel, 18 3...Swivel guide plate, 185...Raising platform, 187...Touch panel operation panel, 189...Work monitor, 190...Data logger, 191...Crane travel control device, 193...Hoist control device, 195...Power supply device, 197...Air compressor, 199...Control device, 200...Precision pressure reducing valve, 208...Gap, 211...Channel fastener, 213...Fixing screw, 213a...Screw head, 213b...Lock groove, 213c...Screw shaft portion, 213d...Fitting groove, 215...Guard, 217...Leaf spring, AX1...Swivel axis, AX2...Rotating axis,

Claims

1. A channel fastener handling device for handling a channel fastener to be attached to an upper portion of a fuel assembly, a rotation device having a rotation motor; a rotating unit having a screw rotation motor, connected to the rotating device, and driven to rotate around a predetermined rotation axis by the rotating motor; a screw operation rotation shaft portion whose one end side is rotatably supported by the swivel portion and which is rotationally driven by the screw rotation motor in a direction around a rotation axis arranged coaxially with the swivel axis; a screw driving tool configured to be able to fit onto the screw head of the fixing screw of the channel fastener, connected to the other end of the screw operation rotating shaft and disposed on the rotating shaft, which rotates around the rotating shaft in response to the rotation of the screw operation rotating shaft, thereby rotating the fitted screw head; an engaging member whose one end side is connected to the swivel portion and which swivels in response to the swivel movement of the swivel portion; The engaging member has an engaging portion formed by a guide plate at a location on the other end side away from the pivot shaft, the engaging portion being inserted into a gap between a fuel rack in a fuel pool and the fuel assembly accommodated in the fuel rack. Channel fastener handling device.

2. the engaging member has a tubular member; The screw operation rotation shaft portion is disposed coaxially with the tubular member in the internal space of the tubular member and is supported rotatably around the rotation axis relative to the tubular member.

2. The channel fastener handling device of claim 1.

3. a sleeve fitted around the outer periphery of the screw operation rotation shaft portion so as to be movable in the axial direction of the screw operation rotation shaft portion; a locking member that engages with the sleeve and is operated by the axial movement of the sleeve to lock or unlock the engagement between the screw driving tool and the screw head; a sleeve drive unit supported by the tubular member and configured to reversibly move the sleeve in the axial direction of the screw operation rotation shaft; 3. The channel fastener handling device of claim 2, comprising:

4. a cavity formed along the rotation shaft inside the screw operation rotation shaft portion; a rod-shaped detection rod that is housed in the cavity so as to be movable in a direction along the rotation axis, one end of which protrudes from the screw driving tool and is arranged so as to be able to abut against the screw head of the fixing screw fitted to the screw driving tool; a position sensor that detects the position of the detection rod relative to the turning portion or the screw operation rotation shaft portion in a direction along the rotation shaft; 4. A channel fastener handling device according to any one of claims 1 to 3, comprising:

5. the screw operation rotation shaft portion is supported movably in a direction along the rotation axis relative to the turning portion, A channel fastener handling device as described in any one of claims 1 to 4, wherein the screw operation rotating shaft portion is supported by the rotating portion via a balance cylinder that cancels the weight of the screw operation rotating shaft portion acting on the fixing screw.

6. 6. A channel fastener handling device according to claim 1, further comprising a reinforcing frame connected to a fixed portion of said pivoting device to support said engaging member so as to be pivotable about said pivot axis.

7. 7. The channel fastener handling device according to claim 1, wherein when the fuel assembly is housed in a fuel rack in a fuel pool, the guide plate is inserted into the gap between the fuel rack and the fuel assembly, and the screw driving tool rotates the screw head, the turning axis and the rotation axis are arranged perpendicular to the water surface of the fuel pool, and the turning motor and the screw turning motor are arranged in positions above the fuel pool where they are not submerged.

Images