JP2000275382A - Clamping bolt welding part removing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and securely remove the tack welding part of a clamping bolt for fixing an acceleration application test piece by sliding an electrode part that is engaged to the head part of the clamping bolt for removing the tack welding part of the clamping bolt by discharge so that it can be moved up and down and engaging it to the head part of the clamping bolt. SOLUTION: A body part of a clamping bolt welding part removing device 42 is suspended by the auxiliary hoist of a fuel exchanger and the position is adjusted by an operation pole 43. The body part supports an electrode 44 and an upper/lower slide mechanisms being provided at the upper part, moves the electrode up and down by the drive of a servo motor 46, and engages it to the tack welding part of a clamping bolt 41. For the electrode part 44, a cylindrical electrode, a round-rod electrode, or the like is used so that it can be adapted to the shape of the clamping bolt 41 and that of the tack welding part. An insulation member 45 is provided inside the electrode part 44 so that only the lower tack welding part of the clamping bolt 41 can be cut and machined without causing the head part of the clamping bolt 41 to be subjected to discharge cutting when a current flows to the electrode part 44.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tightening bolt weld removing device for removing a tack weld for stopping a tightening bolt used in a reactor pressure vessel or a pool.

[0002]

2. Description of the Related Art Generally, in a boiling water reactor, a core portion is formed in a reactor pressure vessel, and a number of fuel assemblies are mounted on the core portion. Four fuel assemblies form a set, and control rods having a cross-shaped cross section are put in and out between the fuel assemblies in each set.

FIG. 6 is a perspective view showing a part of the internal structure of a nuclear reactor. As shown in FIG. 6, the core 1 of the reactor pressure vessel 11
The four combustion assemblies 10 are mounted in pairs in pairs. The core portion 12 includes a core support plate 14 and an upper grid plate 15.
Are laid horizontally to form a furnace internal structure.

A lower portion of the core support plate 14 is reinforced by a reinforcing beam 16 to reinforce mechanical and physical strength, and a fuel support 17 is provided on the core support plate 14. This fuel support bracket 17
The lower part of a set of four fuel assemblies 10 is mounted on the upper part, and the upper part of the fuel assembly 10 is supported by an upper grid plate 15.

[0005] Between the four fuel assemblies 10, a control rod 22 having a cross-shaped cross section is guided so as to be able to enter and exit. The control rod 22 is driven by the control rod drive mechanism 23, passes through the control rod guide tube 24, passes through a cross-shaped slit in the fuel support bracket 17, and moves between the four fuel assemblies 10 between the insertion position and the withdrawal position. You will be guided.

FIG. 7 is a partially cutaway sectional view of the internal structure of the nuclear reactor. As shown in FIG. 7, the upper lattice plate 15 is supported by a core shroud 19. The fuel assembly 10 is configured by storing a fuel bundle 31 in which a large number of fuel rods are bundled in a fuel channel 30 which is a rectangular cylindrical channel box.
The fuel bundle 31 and the fuel channel 30 are connected to the fuel assembly 1.
The fastener is fastened by a channel fastener 20 attached to the upper corner portion of the "0" and is assembled integrally.

That is, a channel fastener 20 is provided at the top corner of a set of four fuel assemblies 10, and the spacing between the fuel assemblies 10 is held by the channel fastener 20 with the assistance of the spacing spacer 21. Is done.

The fuel bundle 31 comprises a number of fuel rods and is held between a lower tie plate 33 and an upper tie plate. The lower body plate 33 is supported by the fuel support bracket 17, and the upper tie plate is integrally provided with a handle 35 used when the fuel assembly 10 moves.

An acceleration irradiation test piece for a material irradiation test during operation of the nuclear reactor is mounted on the upper portion of the upper lattice plate 15 in such a reactor internal structure by a bolted structure. The accelerated irradiation test specimen is removed at the time of the periodic inspection of the reactor, and is used for analyzing material irradiation during operation of the reactor. Heretofore, the accelerated irradiation test piece has been configured to be mounted in a nested manner so that it can be easily removed.

[0010]

However, since there is a risk that the accelerated irradiation test piece may come off during the operation of the reactor due to the influence of vibration or the like during the operation of the reactor, it is fixed using a plurality of tightening bolts. The scheme has been adopted. In this case, the ends of the tightening bolts are further fixed by tack welding to prevent rotation, so that the state of the accelerated irradiation test specimen during the operation of the reactor is stabilized.

For this reason, it is difficult to remove the accelerated irradiation test specimen during the periodic inspection of the reactor, and it takes time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tightening bolt weld removal apparatus which can reliably remove a tack weld of a tightening bolt fixing an accelerated irradiation test piece in a short time.

[0013]

According to a first aspect of the present invention, there is provided an apparatus for removing a welded portion of a tightening bolt which is engaged with a head of a tightening bolt of a component installed in a reactor pressure vessel and discharges the tightened bolt. An electrode part for removing a tack welding portion of the bolt, an up-down sliding mechanism for sliding the electrode part up and down and engaging with a head of the tightening bolt, and the electrode part and the up-down sliding And a main body for supporting the mechanism.

According to a first aspect of the present invention, there is provided an apparatus for removing a welded portion of a fastening bolt, wherein an electrode portion is engaged with a head of a fastening bolt of a component installed in the reactor pressure vessel by a vertical sliding mechanism. The tack welding part of the tightening bolt is removed by the discharge of the part.

According to a second aspect of the present invention, there is provided a tightening bolt welding portion removing apparatus according to the first aspect of the present invention, further comprising a rotation mechanism for rotating the electrode portion.

According to the second aspect of the present invention, in addition to the function of the first aspect of the present invention, in addition to the operation of the first aspect, the electrode portion is rotated at the rear of the rotating machine to uniformly remove the tack weld of the tightening bolt. Make sure.

According to a third aspect of the present invention, in the second aspect of the present invention, there is provided the tightening bolt welding portion removing device, wherein the electrode portion comprises:
A plurality of through holes are provided for discharging chips of the tightening bolt separated by electric discharge.

According to the third aspect of the present invention, in addition to the function of the second aspect, the clamp bolt chips separated by the discharge of the electrode portion are passed through a plurality of through holes. Is discharged.

According to a fourth aspect of the present invention, there is provided a fastening bolt welding portion removing apparatus according to the third aspect of the invention, further comprising a chip discharging device for discharging the chips generated by the discharge cutting of the electrode portion. Features.

According to the fourth aspect of the present invention, in addition to the function of the third aspect, chips generated by the discharge cutting of the electrode portion are discharged to the outside by the chip discharging device. You.

According to a fifth aspect of the present invention, there is provided the tightening bolt welding portion removing device according to the fourth aspect of the present invention, wherein the chip discharging device comprises: a submersible pump for sucking chips from the through hole together with water; A filter for extracting and collecting the chips from the water sucked by the submersible pump.

According to the fifth aspect of the present invention, in the chip discharging device of the tightening bolt welding portion removing apparatus, in addition to the function of the fourth aspect, the chips from the through holes are sucked together with water by a submersible pump, and The chips in the water sucked by the pump are collected by a filter and collected.

According to a sixth aspect of the present invention, there is provided a tightening bolt welding portion removing apparatus according to any one of the first to fifth aspects, wherein a scale for confirming a discharge cutting position is provided. Features.

According to a sixth aspect of the present invention, in addition to the function of any one of the first to fifth aspects, the discharge cutting position is confirmed by a scale.

According to a seventh aspect of the present invention, there is provided the tightening bolt welding portion removing device according to any one of the first to sixth aspects, wherein the device is provided at the bottom of the main body to stabilize the main body. A weight member for self-supporting is provided.

According to a seventh aspect of the present invention, there is provided an apparatus for removing a welded portion of a fastening bolt in addition to the operation of any one of the first to sixth aspects. The member stabilizes the main body and becomes independent.

According to an eighth aspect of the present invention, there is provided a tightening bolt welding portion removing apparatus according to any one of the first to seventh aspects, wherein the electrode portion comprises a cylindrical electrode, a round bar electrode, and a grooved electrode. It is characterized in that any one of a rod electrode, a lotus-like electrode and a square rod electrode is used.

According to an eighth aspect of the present invention, in addition to the function of any one of the first to seventh aspects of the present invention, in addition to the operation of the first aspect of the present invention, in addition to the function of the first aspect of the present invention, the apparatus according to the present invention is adapted to the cutting condition of the welding part of the tightening bolt. Any one of a cylindrical electrode, a round bar electrode, a grooved bar electrode, a lotus-shaped electrode, and a square bar electrode is mounted on an electrode portion and used.

[0029]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a tightening bolt welding portion removing device according to a first embodiment of the present invention. The tightening bolt welding portion removing device 42 is used for removing the tightening bolt 41 of the accelerated irradiation test piece 13 attached to the upper surface of the upper lattice plate 15 in the reactor by electric discharge cutting.

An acceleration irradiation test piece 13 is fixed to the upper peripheral portion of the upper lattice plate 15 by a plurality of tightening bolts 41. The fastening bolt 41 is welded at two points between a lower portion thereof and the accelerated irradiation test piece 13 to be tack-welded, and is fixed so as not to be loosened by vibration or temperature change during operation of the reactor. . The fastening bolt 41 of the accelerated irradiation test piece 13 is located in water.

The main body of the tightening bolt weld removing device 42 is suspended from an auxiliary hoist (not shown) of a fuel exchanger, and the position of the main body is adjusted by an operation pole 43 detachably mounted on the upper part of the main body. Then, the electrode portion 44 provided at the lower portion of the main body portion is engaged with the head of the tightening bolt 41 located in the water.

The body supports the electrode 44 and a vertical sliding mechanism provided on the electrode 44. The vertical sliding mechanism rotates the screw 48 by driving a servo motor 46 to move the electrode 44 up and down, as will be described later. Move. As a result, the electrode portion 44 is driven to a position where the electrode portion 44 properly engages with the tack welding portion of the fastening bolt 41.

The electrode portion 44 includes electrodes such as a cylindrical electrode, a round rod electrode, a grooved rod electrode, a lotus rod-shaped electrode, a square rod electrode, etc., so as to conform to the shape of the tightening bolt 41 and the shape of the tack welding portion. Used. Further, an insulating member 4 is provided inside the electrode portion 44.
5 is provided, which is moved up and down by using the head of the tightening bolt 41 as a guide. The insulating member 45 is used to cut off only the tack welded portion below the tightening bolt 41 without discharging the head of the tightening bolt 41 when a current flows through the electrode portion 44. Is provided.

A vertical sliding mechanism for driving the electrode section 44 up and down is provided above the electrode section 44, and is configured under the vertical sliding mechanism. Servo motor 4
Numeral 6 applies a rotational force to the screw 48 via the universal joint 47 to move the electrode section 44 while maintaining a constant discharge interval.

That is, a screw 48 is connected to an output shaft portion of the servomotor 46 via a universal joint 47, and a nut 49 is incorporated in the screw 48, and the nut 49 is fixed to a base 50 by a bolt 51. ing.
A guide rod 52 is inserted through the base 50 so as to prevent the base 50 from rotating, and the slide bearing 53 smoothly moves up and down. In addition, base 5
Numeral 0 is constituted by an insulating member so that current flows only to the electrode portion 44.

A plate 54 is incorporated below the guide rod 52, and an electrode holder 55 is fixed to the plate 54 by bolts 56. Further, the entirety of the tightening bolt weld removal device 42 is covered with a cover 57 so that chips (fine powder of cuttings) during electric discharge machining do not diffuse to the outside.

FIG. 2 is a schematic side view of the tightening bolt welding portion removing device 42 according to the first embodiment. Base 5
A scale needle 74 is fixed to the side surface of the “0” so that the operation stroke of the electrode unit 44 can be visually checked. Also, two underwater lighting fixtures 77 are incorporated inside the cover 57, and are brightened so that they can be monitored from outside by an underwater camera 78. Further, a suction pump is connected to the joint 76 so that water is discharged.

Next, the operation of the tightening bolt weld removal device 42 will be described. The tightening bolt weld removal device 42 is suspended at a predetermined position in the core portion, and the electrode portion 44 provided at the lower portion is engaged with the head of the tightening bolt 41. Then, the electrode unit 44 is vertically driven by the vertical drive mechanism, and the operation stroke of the electrode unit 44 is visually confirmed by the scale 74 to determine the positioning. After the positioning, the gap between the electrode portion 44 and the tack welding portion of the fastening bolt 41 is separated by electric discharge. The chips separated by the discharge are accumulated in the cover 57. During this operation, the underwater lighting fixture 77 is turned on and monitored by the underwater camera 78. Then, a suction pump is connected to the joint 76 to discharge water together with the chips.

According to the first embodiment, the fastening bolts of the components installed in the reactor pressure vessel can be remotely removed underwater. That is, since the tack welding portion of the fastening bolt 41 can be separated by the discharge cutting of the electrode portion 44, the tack welding portion of the fastening bolt fixing the acceleration irradiation test piece can be reliably removed in a short time. .

Next, a third embodiment of the present invention will be described. FIG. 3 is a configuration diagram of a tightening bolt welding portion removing device according to a second embodiment of the present invention. This second embodiment is different from the first embodiment shown in FIG.
4 is provided with a rotating mechanism for rotating 4 and a plurality of through holes 79 for discharging chips from the welded portion of the fastening bolt 41 separated by electric discharge.

Referring to FIG. 3, the electrode portion 61 is
The electrode portion 61 is provided with a plurality of through-holes 79. The through hole 79 is provided not only in the lateral direction but also in the axial direction at a position off the central axis of the electrode portion 61. This through hole 7
Reference numeral 9 is provided for discharging fine powder of chips separated by electric discharge machining, and a suction line 62 is provided at an upper portion. Further, an insulating guide 63 is incorporated in the outer periphery of the electrode portion 61, and a plurality of through holes 79 are used in the insulating guide 63 as well, so that the fine powder melted by the discharge cutting is easily discharged. Further, a water injection line 64 is incorporated from above the insulating guide 63, and the fine powder is suctioned by the water injection line 6
Discharge from 2.

A drive motor 65 for rotating and driving the electrode portion 61 is housed in a housing 66 above the electrode portion 61. The rotation shaft of the drive motor 65 is connected to the electrode section 61 by a connection joint 67. The drive motor 65 is fixed to a base 68, and a nut 69
Has been fixed. A screw 70 is incorporated in the nut 69, and is connected to a servomotor 72 via a gear 71 below the screw 70.

Accordingly, when the servo motor 72 is driven, the torque is transmitted to the gear 71, the screw 70 rotates, the nut 69 and the base 68 move up and down, and the electrode 61 also moves up and down in conjunction. The electrode section 61 is controlled by a servomotor 72 so as to move while maintaining a constant discharge interval with the member. A guide rod 73 penetrates and is incorporated into the base 68, and can be moved up and down without rotating.

A scale needle 74 is provided on the side of the base 68.
Are fixed, and the operation stroke of the electrode portion 61 is visible. Tightening bolt weld removal device 4
2 is covered with a cover 75, and a joint 76 connected to a suction pump is mounted on the upper part.

FIG. 4 is a side view showing the entirety of the tightening bolt weld removal device 42 according to the first embodiment or the second embodiment. An operation pole 43 is detachably provided on the upper portion of the main body of the tightening bolt weld removal device 42, and the position of the main body with respect to the tightening bolt 41 is adjusted by the operation pole 43. A chip discharging device for discharging chips is composed of a submersible pump 81 and a filter 82, and is connected to a joint 76 provided at an upper portion of a main body of the tightening bolt welding portion removing device 42 through a suction hose 80. The pump 81 is connected. That is, the fine powder generated by the electric discharge machining is absorbed by the suction pump 81 and collected by the filter 82.

FIG. 5 shows a state in which a weight member 85 is attached to the tightening bolt welding portion removing device 42 according to the first embodiment or the second embodiment to remove the tack welding portion of the tightening bolt. It is a schematic plan view showing a state.

The weight member 85 is a long plate connected to the tightening bolt welding portion removing device 42.
5, the tightening bolt weld removal device 42 is connected to the upper lattice plate 1
5 over the grid. Therefore, the tightening bolt welding portion removing device 42 can be self-standing.

Next, the operation of the tightening bolt weld removal device 42 of the present invention will be described. The main body of the tightening bolt weld removing device 42 and the submersible pump 81 are suspended at a predetermined position in the core, and the electrode portions 44 and 61 of the tightening bolt weld removing device 42 are attached to the head of the tightening bolt 41. The upper and lower portions are engaged with each other and driven up and down to separate the electrode portions 44 and 61 from the tack welding portion of the fastening bolt 41 by electric discharge. At this time, the electrode portion 61 is rotated by the rotation mechanism, and the tack welded portion is cut evenly.

The fine powder melted by the septum is supplied to the submersible pump 8
1 and is collected by the filter 82. At this time, the underwater lighting fixture 77 is turned on and the state of the electric discharge machining state is monitored by the underwater camera 78. The operation strokes of the electrode portions 44 and 61 are visually confirmed by a graduation needle 74 incorporated in the main body of the tightening bolt welded portion removing device 42, and the operation is visually confirmed through an underwater camera 78.

The fine powder generated by the discharge is applied to the electrode 6
Water is circulated through one of the plurality of through-holes and removed in the water so that discharge can always be continuously performed. The chips mixed in the water are discharged to the outside by a chip discharge device and collected.

As described above, in the embodiment of the present invention, the strokes of the electrode portions 44 and 61 can be confirmed by the scale needle 74 and the operation can be visually confirmed through the underwater camera 78.
The state of the electric discharge machining state can be observed in real time, and the operation can be performed safely and reliably.

Further, since a rotating mechanism is added to the electrode portion 61, the tack welding portion can be cut evenly and reliably.
Work can be performed in a short time. Further, since the electrode portion 61 is provided with a plurality of through holes, the fine powder generated by the discharge can be collected smoothly and reliably.
For this reason, since the discharge can always be continuously performed, the workability can be greatly improved, and the work can be performed safely in a short time.

The underwater pump 8 is used as a chip discharging device.
1 and the filter 82, it is possible to reliably recover the powder generated at the time of electric discharge cutting, and thus it is possible to prevent turbidity of water in the nuclear reactor and contamination by the powder.

Further, since the tightening bolt welding portion removing device 42 is provided with a scale 74, the work can be performed while checking the strokes of the electrode portions 44 and 61 through the underwater camera 78. Performance can be improved. Further, since the electrode portions 44 and 61 can be processed by being replaced with a cylindrical, round rod, grooved rod, abundant rod, or square rod electrode, it is possible to respond to the cutting situation.

[0055]

As described above, according to the present invention, the removal of the tack welding portion of the tightening bolt used in the reactor pressure vessel or the pool or the work of removing the tightening bolt is performed. The electrode part engaged with the head of the tightening bolt is slidably movable up and down, and the gap between the electrode part and the tightening bolt is removed by electric discharge. A removal operation can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a tightening bolt welding portion removing device according to a first embodiment of the present invention.

FIG. 2 is a schematic side view of the tightening bolt welding portion removing device according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a tightening bolt welding portion removing device according to a second embodiment of the present invention.

FIG. 4 is a side view showing the entirety of the tightening bolt welding portion removing apparatus according to the present invention.

FIG. 5 is a schematic plan view showing an installed state in which a weight member of the tightening bolt welding portion removing device according to the present invention is attached.

FIG. 6 is a perspective view showing a part of the internal structure of the reactor.

FIG. 7 is a partially cutaway sectional view of the internal structure of the reactor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Reactor pressure vessel 13 Acceleration irradiation test piece 41 Tightening bolt 42 Tightening bolt weld removal device 44, 61 Electrode part 46, 72 Servo motor 47 Universal joint 48 Screw 65 Drive motor 74 Scale needle 79 Through hole 81 Submersible pump 82 Filter 85 Weight member

Claims (8)

[Claims] An electrode for engaging a head of a tightening bolt of a component installed in a reactor pressure vessel and removing a tack welded portion of the tightening bolt by electric discharge, and moving the electrode up and down. A tightening bolt welding portion, comprising: a vertical sliding mechanism that freely slides and engages with a head of the tightening bolt; and a main body that supports the electrode portion and the vertical sliding mechanism. Removal device. 2. The apparatus according to claim 1, further comprising a rotating mechanism for rotating the electrode unit. 3. The removal of the fastening bolt welding part according to claim 2, wherein the electrode part has a plurality of through holes for discharging chips of the fastening bolt separated by electric discharge. apparatus. 4. The apparatus according to claim 3, further comprising a chip discharging device for discharging the chips generated by electric discharge cutting of the electrode portion. 5. The chip discharging device includes a submersible pump for sucking chips from the through hole together with water, and a filter for extracting and collecting the chips from the water sucked by the submersible pump. The tightening bolt weld removal device according to claim 4, characterized in that: 6. The apparatus according to claim 1, further comprising a scale for confirming a discharge cutting position. 7. The tightening device according to claim 1, further comprising a weight member provided on a bottom portion of the main body portion for stabilizing the main body portion to be self-standing. Bolt weld removal device. 8. The electrode unit according to claim 1, wherein the electrode unit uses any one of a cylindrical electrode, a round bar electrode, a grooved bar electrode, a lotus-shaped electrode, and a square bar electrode. The tightening bolt weld removal device according to any one of claims 1 to 7.