JPS586491A - Nozzle dismontling device in fuel assembly - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention is used in nuclear reactors. The present invention relates to a nozzle disassembly device for a fuel assembly that disassembles a nozzle of the fuel assembly in order to remove, for example, a damaged fuel rod from the fuel assembly.

Fuel assemblies are used in pressurized water reactors currently in use. As shown in FIG. 1, this fuel assembly includes an upper nozzle 1 and a lower nozzle 2 which are arranged vertically apart, and which are arranged with a predetermined interval between them and formed by a strap. The support grids 8 are inserted into the grid spaces at predetermined intervals and supported by the support portions of the support grids 3, and the upper and lower ends of each are connected to the upper nozzle. 1. It has a control rod guide tube 4 connected to the lower nozzle 2, a large number of fuel pellets 6 sealed in a cladding tube 5, and a pressing spring 7, and is inserted into a predetermined position in the lattice space of the support lattice 3. , support grid 3
It is composed of a large number of fuel rods 8 that are elastically supported by a support section. Such fuel assemblies are removed from the reactor core after burning for a certain period of time, and after undergoing various inspections, only those with no problems are reloaded into the reactor core.

However, conventionally, among the fuel assemblies, the fuel assemblies in which damaged fuel rods were detected in the various inspections mentioned above were found to have a bulky 1 to 2 damaged fuel rods per fuel assembly. First, if even one fuel rod is damaged, the reactor core cannot be reloaded for use, and the fuel assembly must be stored in a spent fuel tank, which is extremely uneconomical.

Therefore, it was considered to pull out the damaged fuel rod from the fuel assembly, but in this case, since the fuel assembly containing the damaged fuel rod has radiation, it is necessary to remove it from the water surface to shield this radiation. ) must be located at a distance of 3 m or less.

In addition, the upper end of each control rod guide tube is welded all around to the upper nozzle, so it is not possible to remove the nozzle from the fuel assembly and pull out the damaged fuel rod to make the fuel assembly reusable. It was even possible. That is, the welding of the entire circumference weld of each control rod guide tube is removed, the upper nozzle is removed from the fuel assembly, the damaged fuel rod is pulled out, a dummy rod is inserted in its place, and each control rod is reassembled. The upper nozzle must be welded to the upper end of the guide tube underwater, and the control rod guide tube cannot be removed from the weld to the upper nozzle without cutting, or the control rod guide tube must be welded to the upper nozzle underwater. It was not possible to weld the control rod guide tubes because this welding had to be done by operating on a water tank.

This invention has been made in view of the above circumstances, and is based on a hanging tool that is slidably and detachably attached to a guide bin of a positioning plate having a clamping plate and a clamping claw. Attach the positioning plate to the lower nozzle located at the top of the fuel assembly fixed in the water of the water tank, and place it vertically on the XY table movably provided at the top of the water tank. The mounted no-using shaft is moved up and down to fit into the guide hole, and the drive shaft, which is provided inside the no-used shaft and has a tool attached to the lower end, is rotated and moved up and down. Alternatively, the lower nozzle can be removed from the fuel assembly by cutting the attachment part of each control rod guide tube to the lower nozzle, which allows the spent fuel assembly to be used for reprocessing. It is now possible to carry out the unburned fuel assembly, and if the damaged fuel rod is pulled out, a dummy rod is inserted in its place, and a lower nozzle of another type is installed, the fuel assembly can be reused. It is an object of the present invention to provide a nozzle dismantling device in a fuel assembly, which can be used to disassemble the nozzle in a fuel assembly, and which can significantly reduce costs.

An embodiment of the present invention will be described below with reference to FIGS. 2 to 17. Reference numeral 11 in FIG. 2 is a fuel transfer canal (water tank) provided between walls 12 and 12, and an upper fixing plate 13 is attached to a predetermined location above the fuel transfer canal 11.
2.12. A guide frame 14.15 is provided in a hanging manner on the upper fixing plate 13, and a lower fixing plate 16 is provided below the guide frame 14.15.
．． 17 is attached. The lower fixing plate 16.17 is fixed to the wall 12.12 via an overhang 18. Can support frames 19 and 20 are provided facing each other between the guide frames 14 and 115. Sheaves 2 are installed on the top of the can support frame 19 and 20, respectively.
3 is installed and the can support frame 19
．． 20 is vertically movably suspended via an electric winch 22, a wire rope 24, and a sheep 2L 23 attached to the upper fixed plate 13, and is attached to the guide frame 14-11.
It is supported by a holding member 25 attached to 5. A can 26 rotatably attached to the can support frame 19.20 is provided between the can support frames 19.20 and fixed by a stopper 27 provided on the can support frame 19.20. ing. A fuel assembly 29 including a damaged fuel rod is fitted into the can 26 and is held in the can 26 by a holding mechanism 30 rotatably attached to the can 26 . The holding mechanism 30 is connected to a cylinder mechanism 28 rotatably attached to the side wall of the can 26.
It is designed so that it can be rotated by. This can 26 is reversed in the water of the fuel transfer cal 11 by a reversing mechanism 31, and is fixed by stoppers 27, 32. Therefore, the fuel assembly 29 in the can 20 is fixed with the lower nozzle 33 positioned above the upper nozzle.

An XY table 35 is provided on the upper fixed plate 13 so as to be movable in the directions of arrows A, B, O, D (X-axis, Y-axis) in FIG. The XY table 35 has an upper fixed plate 13
On two parallel rails 37 provided on the upper base 36,
In FIG. 5, a first table 38 is fitted to be slidable in the directions of arrows A and E (X-axis direction), and two parallel rails 39 provided on this first table 38 are connected to In Figure 5, arrow 0. It consists of a second table 40 fitted in a slidable manner in the D direction (Y-axis direction). The first table 38 is screwed onto a screw punch 41 that is rotatably attached to the base 36, and the rotation of a motor 42 connected to the screw punch 41 moves in the directions of arrows A and B. It is designed to be moved. The second table 40ti has two parallel T-grooves 43, and is rotated in the direction of arrow OsD by the rotation of a motor 45 connected to a screw punch 44 rotatably attached to the first table 38. It is designed to be moved.

On the second table 40, a tool mounting plate 46 is attached to the T-slot 43.
It is fitted into the holder and installed so that its position can be adjusted freely. A hole 47 is formed in the tool mounting plate 46 as shown in FIG.
A housing shaft 4.8 is fitted into this hole 47 so as to be vertically movable. A chic 49 is formed on the outer peripheral surface of the upper part of the housing shaft 48, and a pinio 151 is rotatably mounted on the rack 4-9 at a predetermined location of the tool mounting plate 46 via a shaft 50. are interlocked. axis 50
A handle 62 is attached to the housing shaft 48, and rotation of the handle 52 causes the housing shaft 48 to move up and down via the pinion 51 and the rack 49. A motor (rotary drive machine) 53 is attached to the upper end of the housing shaft 48 . Further, within the housing shaft 4.8, a drive shaft 54 is connected to a joint 56 attached to a rotation shaft 55 of the motor 53 so as to be vertically slidable and to rotate together with the rotation shaft 55. Further, a collar 57 is provided on the upper part of the drive shaft 54, and a spring 59 is provided between the collar 57 and a spring seat 58 formed on the housing shaft 48.
is interposed, and this spring 59) drives the drive shaft 5.
The book is biased upwards. A hexagonal hole 60 is formed at the lower end of the drive shaft 54. A lever 63 is rotatably attached to the housing shaft 8 via a connecting fitting 62. Rotation of the lever 63 in the direction of arrow E in FIG. 8 causes the drive shaft 54. is lowered relative to the housing shaft 48 against the force of the spring 69, and when the force acting on the lever 63 in the direction of arrow E is removed, the drive shaft 54 is returned to its original position by the force of the spring 59. Further, a housing (one component of the housing shaft 48) 64 is detachably attached to the lower end of the housing shaft 4.8 with a set screw 65. The housing 64 has a tool insertion hole 66, and recesses 67 are formed at both ends of the tool insertion hole 66.
．． 68 is formed. Also, Howe Synchro 4 (7
) A mounting portion 69 is provided on the - side, and a communication hole 70 communicating with the tool insertion hole 66 is formed in the mounting portion 69 . The recess 68 consists of a small diameter part and a large diameter part, and a spring 71 is fitted into the small diameter part, and a stopper 72 is fitted into the large diameter part.

A screw hole is formed in the stopper 72. Drive shaft 54
The lower end of the tool is inserted into the recess 67 and has a tool insertion hole 66.
A tool 73 is inserted into the tool 73 and further screwed into the stopper 72
is inserted into the hexagonal hole 6o and is detachably attached.

Further, there is a space 74 between the inner peripheral surface of the recess 67 and the tool 73.
is formed.

A chip collection device 75 is attached to the attachment portion 69. As shown in FIG. 9, this chip collection device 75 includes a motor 76 attached to the upper part of the wall 12, a centrifugal pump 77 having a suction pipe 77 inserted into the water, and a centrifugal pump 77 having a suction pipe 77 inserted into the water.
7, a discharge pipe 79 connected to this ejector 78 and inserted into the water, a suction part 80 of the ejector 78, and a mounting part 69 dedicated to the No-Uji puffer fish 6.
It consists of a flexible hose 81 that connects the flexible hose 81, a filter 82, a cock 83, 84, and a strainer 85 that are interposed in the pipeline of the flexible hose 81. Note that 86, 87, and 88 are all hanging tools.

On the other hand, a positioning plate 91 is placed above the lower nozzle 33 of the fuel assembly 29 which is held in the can 26 and fixed in water with the lower nozzle 33 positioned above the upper nozzle. A guide hole 90 is formed in the positioning plate 91 to face the end of the control rod guide tube 89 attached to the lower nozzle 33 in FIG. A holding plate 92 is attached to the upper and left side of the positioning plate 91 in FIG. These clamping plates 92 are brought into contact with the side surfaces of the lower nozzle. A bracket 93 is provided on the opposite side of the two clamping plates 92 of the positioning plate 91.
are provided, and these brackets 93 have clamping claws 94,
It is rotatably attached to a shaft 95. Further, an L guide bin 96 is provided upright in the center of the positioning plate 91. As shown in FIGS. 10 to 14, this guide bin 96 has large diameter portions 9 with a circular cross section located at both ends thereof. ,
98, and a small diameter portion 99 with a circular cross section located between these.
and a □ medium diameter portion 100 having a substantially oval cross section. Further, a guide body 101 is fitted into the guide bin 96 so as to be vertically slidable. A recess 102 is formed in the guide body 101 . This recess 102 has a small diameter part 103 with a circular cross section located at the lower end, an oval hole part 104 with an oval cross section located at the upper end, and a medium diameter part 105 with a circular cross section slightly larger than the small diameter part 103. , and a large-diameter portion 106 having a circular cross section and a diameter slightly larger than that of the medium-diameter portion 105.

A disk-shaped spacer 107 is fitted into the middle diameter portion 105 . A hole 108 is formed in the center of the spacer 107, and includes a substantially oval-shaped hole 108& and a circular hole 108b.

Further, #109 is formed on the upper surface of the spacer 107. The spacer 107 is urged upward by a spring 110 fitted into the small diameter portion 103. Guide body 1
01 on the outer circumferential surface of the lower end thereof, two portions facing the clamping claws 94 are provided with links 111, respectively, as shown in FIGS. 7 and 8.
One end is rotatably attached via a shaft 112. The other end of the link 111 has a shaft 113 at the upper end of the nine clamping claws.
It is rotatably attached via the When the guide body 101 is separated from and above the positioning plate 91, the slot 111 and the clamping claw 94 are in the position shown by the two-dot chain line in FIG. 3
Move away from 3. When the guide body 101 is in contact with the positioning plate 91, the link 111 and the clamping claw 94 are in the position shown by the solid line in FIG. It is configured to be fixed to the lower nozzle 33. And the guide body 10
Hanging tools 11 are installed in the 10 oval holes and the large diameter part 106 of 1.
4 is inserted freely. A recess 115 having a circular cross section is formed at the lower end of the hanging tool 114. Furthermore, a collar 116 that fits into the oval hole 104 of the guide body 101 is provided on the outer periphery of the lower end of the hanging tool 114, and a protrusion 117 that fits in and out of the groove 109 is provided at the lower part of the hanging tool 114. is formed. Hanging tool 114. A hanging ring 11 is attached to the upper end of the
8 is provided.

Next, the operation of the nozzle dismantling device in the fuel assembly configured as described above will be explained. To remove the lower nozzle 33 from the fuel assembly 29, use the lifting tool 117JIh.
The lower end of the guide body 101 is fitted into the oval hole 104 and the large diameter part 106, and the protrusion 117 is fitted into the groove 109,
The lifting tool 114 is rotated 9CP with respect to the guide body 101, and the lifting tool 114 is hung by a bit crane or the like. Then, the collar 116 is attached to the upper part of the guide body 101, and the large diameter part 98
are respectively engaged with the spacer 107, and this spacer 1
07 engages with the guide body 101 against the force of the spring 110. As a result, the positioning plate 91 is suspended together with the 11 hanging rods JAc. At this time, the guide body 1
01 and the positioning plate 91 are separated from each other. In this state, the positioning plate 91 and the hanging tool 114 are positioned so that the lower nozzle 33 is positioned above the upper nozzle, and the fuel transfer canal 11 is
The cylinder mechanism 28 is operated to lower the holding mechanism 30 and the can 2
6 with the top open. At this time, the clamping plate 92
is brought into contact with the side surface of the lower nozzle 38 as shown in FIGS. 7 and 8. Next, when the hanging tool 114 is pushed down,
The guide body 101 comes into contact with the positioning plate 91, and the link 11
1, the upper part of the gripping claw 94 is indicated by the arrow in FIG. direction, the clamping claw 94 rotates in the direction of arrow G in the figure. Accordingly, the positioning plate 91 is fixed to the lower nozzle 38 by holding the first part (M?g) IV33 between the holding plate 92 and the holding claw 94. Here, the hanging tool 114 is turned around the guide body 101. At this time, the guide pin 96
, the guide body 101, the spacer 107, and the hanging tool 114 are in the positional relationship shown in FIGS. 10 to 14.
07 is prevented from rising relative to the guide bin 96 by the middle diameter portion 100 of the guide bin 96. Furthermore, since the guide body 101 is pressed against the positioning plate 91 by the force of the spring 110, the rotation of the clamping claws 94 is locked.

After this, pull up the hanging tool 114 and
is pulled out from the guide body 101 and removed from above the lower nozzle 33.

Next, motor 42! 5 to operate the XY table 35
and insert the tool 73 into the guide hole 90 of the positioning plate 91.
position it directly above.

Next, the handle 52 is turned to lower the housing shaft 48 and the lower end of the housing 64 is fitted into the guide hole 90. Then, the motor 53 is operated to rotate the tool 73, the lever 63 is further operated to lower the tool 73, and the upper surface of the simple screw 121 screwed into the lower nozzle 33 is cut. This allows simple screw 12
The welded portion of the locking pin 122, which is fitted into the groove of No. 1 and welded to the lower nozzle 83, is removed by cutting.

Chips during cutting pass through the space 74 between the housing 04 and the tool 73 and the communication hole 70, and are sucked into and collected by a chip collection device 75 shown in FIG. 9. This chip collection device 75
The rotation stopper pin 122 is then recovered after cutting. After the locking pin 122 is recovered, the simple screw 121 is turned and loosened using a nozzle removal tool 123 shown in FIG. 15, and is removed from the lower nozzle 33.

That is, the removal tool 123 attaches to the long connecting rod 124,
A tool 124 that fits into the groove of the simple screw 121
The simple screw 121 is pulled out from the lower nozzle 33 by turning the upper end of the connecting rod 124 on the upper fixed plate 13 to rotate the tool 124&. Thereafter, the simple screw 121 is collected by suction using a suction tool (not shown).

Next, hang the nozzle handling tool 125 shown in FIG.
The claw body 126 of the nozzle is hooked onto the leg 127 of the lower nozzle, the nozzle handling tool 125 is pulled upward slightly, and then moved laterally to temporarily store it at an appropriate location underwater in the fuel transfer canal 11. The nozzle handling tool 125 moves the actuator 129 relative to the tool head 7128 and moves the handle 130 up and down to move the claw body 126 rotatably attached to the tool head 128.
It can be rotated between the position shown by the two-dot chain line in FIG. 16 and the position shown by the solid line.

For fuel assemblies that have unburned fuel rods and are to be reused, pull out the damaged fuel rods from the fuel assembly, insert a dummy rod in its place, and then tighten the locking cap screw 132. The lower nozzle of the type that attaches the control rod guide tube to the lower nozzle is attached to the nozzle handling tool 125.
and lower the damaged fuel rod to the upper part of the fuel assembly 29 from which it has been pulled out, fit this lower nozzle into the control rod guide tube, and insert the locking cap screw fitted into the lower nozzle into the control rod guide tube. 132 is screwed together with the tool 131 to install the nozzle shown in FIG.
4 is connected to a tool 131a.

Note that a pipe is connected to each of the cylinder mechanisms,
These tubes are appropriately extended by the upper fixing plate 131 and connected to an operating unit (not shown) provided on the upper fixing plate 13. In addition, the operation of each of the mechanisms described above is performed by the television camera 13 shown in FIGS. 2 and 4.
3.Move the 134 appropriately to connect these TV cameras 133.
．． All of this is done on the upper fixing plate 13 while being monitored by 134. The movement of the television camera 133, 134 is also carried out on the upper fixed plate 13.
This is done via a connecting rod connected to 4.

As explained above, according to the present invention, the upper part of the fuel assembly is fixed to the lifting tool which is slidably and removably attached to the guide plate of the positioning plate having the clamping plate and the clamping claw. The positioning plate is attached to the lower nozzle located at the lower nozzle, and the housing shaft, which is vertically attached to an XY table movably provided at the upper part of the water tank, is moved up and down to fit into the guide hole. However, since the configuration is such that the drive shaft, which is installed inside the nozzle and has a tool attached to its lower end, rotates and moves up and down, a positioning plate is attached to the lower nozzle of the fuel assembly fixed in the water at the top of the water tank. Attach the
In addition, by operating at the upper part of the water tank, the attachment part between the lower nozzle and each control rod guide tube is cut with a tool through the guide hole of the positioning plate, thereby removing the lower nozzle from the fuel assembly. be able to. Therefore, it is possible to transport spent fuel assemblies for reprocessing, and for unburned fuel assemblies, damaged fuel rods are pulled out, dummy rods are inserted in their place, and By installing other types of lower nozzles, the fuel assembly can be reused, resulting in significant cost savings.

[Brief explanation of the drawing]

Fig. 1 is a partially omitted longitudinal cross-sectional view of a fuel assembly loaded in a conventional nuclear reactor, Fig. 2 is a partially omitted front view showing an embodiment of the present invention, and Fig. 3 is its main components. 4 is a partially omitted side view, FIG. 5 is a plan view, FIG. 6 is a side view of the main part, and FIG. 7 is a positioning plate attached to the lower nozzle. Fig. 8 is a partially omitted longitudinal sectional view showing the mounting of the positioning plate to the lower nozzle, the mounting of the tool, and the cutting state of the tool, and Fig. 9 is the cutting state. 10 is a longitudinal sectional view showing one state of attachment of the positioning plate and the hanging device; FIG. 11 is a cross sectional view taken along line XI-M of the deposit drawing; FIG. 12 is a cross-sectional view taken along line M-M in Figure 10, Figure 13 is a cross-sectional view taken along line ■-■ in Figure 10,
Figure 4 is a cross-sectional view along the Xll/-ff line in Figure 1O, Figure 15 is a diagram showing the state in which the simple screw of the lower nozzle is rotated by the nozzle removal tool, 11
Figure 16 is a partially omitted vertical cross-sectional view showing a state in which a nozzle handling tool is engaged with the lower nozzle, and Figure 17 is a view showing a state in which the logic king cap screw of the lower nozzle is rotated by the tool for nozzle installation. be. 11... Fuel transfer canal (water tank) 13...
... Upper fixing plate, 16.17... Lower fixing plate, 1B... Overhanging member, 26... Can, 27.32... Stopper, 29...
・Fuel assembly, 30... Holding mechanism, 33...
... Lower nozzle, 35 ... XY table name ... Housing axis, 52 ... Handle, 5g ... Motor (rotary drive machine), 64 ...
...Drive shaft, 63...Lever, 64...
...No Uzing, 73...Tools, 75...
...Chip collection device, 89...Control rod guide tube,
90... Guide hole, 91... Positioning plate, 92... Holding plate, 94... Holding claw, 96... Guide pin, 107...Spacer, ttt...Link, 114...
・Hanging tool, 121...Simple screw, 1
22... Rotating pin, 123... Nozzle removal L work A, 125... Nozzle handling tool, 131... Tool for nozzle installation, 132... ...
・・Locking cap screw, 133.134・
...TV camera. Figure 1 Figure 7 94 93

Claims (1)

[Claims] A positioning plate is provided with a holding plate on one side, a holding claw is rotatably attached on the other side, and has a number of guide holes with a guide bin provided in the center, and a positioning plate that is slidably attached to the guide pin. The lower nozzle is positioned above the upper nozzle by rotating the clamping claw via a connecting member that is fitted and detachably attached to the positioning plate and connected to the clamping claw, so that the lower nozzle is positioned above the upper nozzle and placed in the water of the aquarium. a hanging tool for mounting the positioning plate on the lower nozzle of the fixed fuel assembly; an XY table provided at the top of the water tank so as to be movable vertically and horizontally in a horizontal plane; To,
and a housing shaft which is connected to be movable up and down and whose lower end is slidably fitted into the guide hole; 1. A nozzle dismantling device for a fuel assembly, comprising a drive shaft that can be rotated many times by a machine, and a tool that is detachably attached to the lower end of the drive shaft.