JPS6318159B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel assembly holding device for fixing a fuel assembly in a water tank in order to remove the fuel rods of the fuel assembly used in a nuclear reactor.

Fuel assemblies are used in pressurized water reactors currently in use. This fuel assembly
As shown in the figure, an upper nozzle 1 and a lower nozzle 2 are arranged vertically apart, and a plurality of support grids are arranged at a predetermined interval between them and have grid spaces formed by straps. 3 is inserted into the grid space of this support grid 3 at a predetermined interval and fixed by the fixing part of the support grid 3, and the upper and lower ends of each are inserted into 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 grid space of the support grid 3 to be supported. It is composed of a large number of fuel rods 8 that are elastically supported by the support portions of the lattice 3. Such fuel assemblies are removed from the reactor core after burning for a certain period of time, and after undergoing various inspections, only those that are found to be in good condition are reloaded into the reactor core.

However, conventionally, among the fuel assemblies, the number of damaged fuel rods in the fuel assemblies in which damaged fuel rods were detected in the above various inspections was 1 to 2 per fuel assembly. Nevertheless, 1
Even in the case of damaged fuel rods, the reactor core could not be reloaded for use, and the fuel assemblies had to be stored in spent fuel tanks, which was 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 should be located 3 m or less from the water surface in order to shield this radiation. There must be. In particular, when pulling out a damaged fuel rod, the upper end of the damaged fuel rod must be located 3 m or less above the water surface when pulled out from the fuel assembly, so the position of the fuel assembly must be 3 m + approximately 4 m. There was a situation in which the length of the fuel rods had to be 7 m or less above the water surface.

The upper end of each control rod guide tube is welded all around to the upper nozzle, and in order to remove the upper nozzle from the fuel assembly, pull out the damaged fuel rod, and make the fuel assembly reusable, each control rod guide tube must be welded to the upper nozzle. Weld the entire circumference of the control rod guide tube, remove the upper nozzle from the fuel assembly, and pull out the damaged fuel rod.
Instead, a dummy rod must be inserted and the upper nozzle must be welded underwater again to the upper end of each control rod guide tube, and the control rod guide tube must be removed from the weld with the upper nozzle without cutting. Not only was it impossible to re-weld the control rod guide tube to the upper nozzle underwater, but this welding had to be carried out above the water tank, making it impossible.

In addition, in order to make the fuel assembly reusable by removing the lower nozzle from the fuel assembly and pulling out the damaged fuel rod, it is necessary to remove the lower nozzle from each control rod guide tube and the lower nozzle. Although it is not impossible to attach the fuel assembly to the control rod guide tube, it is possible to attach the Remove the lower nozzle and pull out the damaged fuel rod from 7m above the water surface.
This was extremely difficult as it had to be carried out within a range of 11 meters or less and above the water tank.

This invention was made in view of the above circumstances,
A can that is vertically submerged in water in a water tank is fixed to the water tank, a fuel assembly inserted into the can is fixed to the can by a holding mechanism, the can is turned over and fixed to the water tank, and then By moving this can up and down, at the top of the aquarium,
Using remote control, the lower nozzle is removed from the fuel assembly located underwater and the damaged fuel rod is pulled out.
In place of this, a dummy rod is inserted and another lower nozzle is attached to the fuel assembly so that the fuel assembly can be reused, and the purpose is to provide an extremely economical fuel assembly holding device. do.

Hereinafter, one embodiment of the present invention will be explained with reference to FIGS. 2 to 20.
This will be explained based on the diagram. Reference numeral 11 in FIG. 2 is a fuel transfer canal (water tank) provided between the spent fuel pit walls 12 and 12 and in which water is stored. is provided. As shown in FIGS. 2 and 4, the upper fixing plate 13 is made of shaped steel, a plate, etc., and is attached to the upper ends of the walls 12, 12. As shown in FIG. 7, a recess 14 is formed in the upper fixing plate 13, and on both sides of this recess 14, as shown in FIGS.
is provided. Lower fixing plates 17 and 18 are fixedly provided below the upper fixing plate 13, that is, near and at the lower ends of the guide frames 15 and 16. These upper fixing plate 13, guide frames 15 and 16, and lower fixing plates 17 and 18 constitute a frame body. Fixing members 19 and 20 are provided on the lower fixing plates 17 and 18, respectively, so as to be movable in the directions of arrows A and B in FIG. The fixing member 19 is attached to the disk 2 as shown in FIGS. 9 and 10.
1 and a shaft 22, a rack 23 is provided on the upper surface of this shaft 22, and the shaft 22 is
As shown in the figure, it is slidably fitted to the lower fixing plate 17. Further, a worm 24 and a worm wheel 25 meshed with the worm 24 are rotatably attached to the lower fixing plate 17 through shafts 26 and 27, respectively. The upper end of the shaft 26 projects upward from the lower fixing plate 17 and is formed into a hexagonal column shape. Further, a pinion 28 is attached to the shaft 27, and the pinion 28 is meshed with a rack 23 formed on the shaft 22. Note that the fixing member 20 provided on the lower fixing plate 18 and its moving mechanism have the same configuration as the fixing member 19 provided on the lower fixing plate 17 and its moving mechanism, so a description thereof will be omitted. However, the worm shaft 29 (corresponding to the shaft 26) provided on the lower fixing plate 18 is elongated and extends to the upper part of the lower fixing plate 17. Then, by fitting a long box wrench from the upper part of the fuel transfer canal 11 to the upper ends of the shafts 26, 29 and rotating these shafts 26, 29, the worm 24, the worm wheel 25,
Fixing member 1 via pinion 28 and rack 23
9 and 20 are extended toward the wall 12, so that the lower fixing plates 17 and 18 are fixed between the walls 12 and 12.

An electric winch 3 is installed on one side of the upper fixed plate 13.
0 is attached. In addition, the upper fixing plate 13
As shown in FIG. 4, a sheave 32 is rotatably attached via a bracket 31.
Also, a bracket 3 is installed at a distance from this sheave 32.
3 are installed in parallel.

On the other hand, two can support frames 34 and 35 are spaced apart and opposed to each other between the guide frames 15 and 16, and are provided in a downwardly movable manner. This can support frame 34,3
Reference numeral 5 denotes an elongated plate, and guide rollers 36 are rotatably attached to the upper, middle, and lower parts of each plate, respectively, and these guide rollers 36 are engaged with the guide frames 15 and 16. Further, a sheave 37 is rotatably attached to the upper part of the can support frames 34 and 35. A wire rope 38 is wound around the sheave 37, one end of which is attached to the electric winch 30, and which is wound around the sheave 32 and lowered downward. This wire rope 38 extends upward and its other end is attached to the bracket 33. Then, by the operation of the electric winch 30, the guide frame 15,
Can support frames 34, 35 along 16
is designed to move up and down. In this way, the can support frames 34, 35, the electric winch 30, the sheaves 32, 37, the wire rope 38, etc. constitute a vertical movement mechanism. guide frame 15 of can support frames 34, 35;
A protrusion 39 is provided on the upper part of the surface on the 16 side. Furthermore, positioning mechanisms 42, 43, and 44 are provided at predetermined locations on the guide frames 15 and 16, as shown in FIGS. 2 to 4. The positioning mechanism 42 is attached to the guide frames 15 and 16,
It consists of levers 46 and 47 that are rotatably attached by pins 45 and a cylinder mechanism 48 that connects the upper parts of the levers 46 and 47.
Recesses 49 and 50 are formed at the upper end portions of the levers 6 and 47 to receive the protrusion 39 when the levers 46 and 47 come into a folded position when the cylinder mechanism 48 is contracted. The positioning mechanism 43 has the same configuration as the positioning mechanism 42, so a description thereof will be omitted. The positioning mechanism 44 is made of a plate having a recess 51 in which the protrusion 39 can be received.

A rectangular cylindrical can 61 is provided between the can support frames 34 and 35. A tapered flange 62 is formed at the upper end of the can 61 . Furthermore, a frame 64 having a shaft 63 and a frame 66 having a shaft 65 are fixed to the center of the can 61. The shafts 63 and 65 are rotatably fitted approximately at the center of the can support frames 34 and 35, respectively. Further, a worm wheel 67 is attached to the shaft 65. A worm 69 having a shaft 68 is engaged with the worm wheel 67 . The shaft 68 is the can support frame 3
It is rotatably supported by bearings 70, 70 provided at 5 and extends upward. A shaft 72 is connected to the shaft 68 via a clutch 71 and extends above the upper fixed plate 13, and this shaft 72 is connected to a motor (not shown) provided on the upper fixed plate 13. By rotating the shaft 72 with this motor, the clutch 71, worm 69, worm wheel 67, shafts 63, 65, frame 64,
66, the can 61 can be rotated about shafts 63 and 65 in the direction of arrow C in FIG. the worm wheel 67;
The worm 69, shafts 68, 72, clutch 71, motor, etc. constitute a can rotation mechanism.

Bearings 73, 74 are provided at the upper ends of the can support frames 34, 35, respectively, and shafts 75, 76 are fitted into the bearings 73, 74, respectively. Approximately L-shaped stoppers 7 are provided at both ends of the shaft 75.
7, approximately L-shaped stoppers 78 are provided at both ends of the shaft 76.
are each rotatably attached. A cylinder mechanism 79 attached to the upper part of the can support frame 34 is connected to one end of the stopper 77. Further, a cylinder mechanism 80 attached to the upper part of the can support frame 35 is connected to one end of the stopper 78. The cylinder mechanisms 79 and 80 operate synchronously,
When the cylinder mechanisms 79 and 80 are extended, the stoppers 77 and 78 stop the can 61 as shown in FIG.
are clamped to prevent rotation of the can 61, and when the cylinder mechanisms 79, 80 are contracted, the stoppers 77, 78 are removed from the can 61, allowing the can 61 to rotate.

Further, a U-shaped stopper 81 is provided between the lower ends of the can support frames 34 and 35 to stop the opening from the first one.
The back part 81a of the stopper 81 allows the can 6 to be
Rotation of the lower part of 1 in the direction of arrow D in FIG. 12 is prevented. Stoppa 81
has shafts 82 and 83, and the shafts 82 and 83 are rotatably fitted to the can support frames 34 and 35. A chain wheel 84 is attached to the end of the shaft 83. A chain 87 connected to two cylinder mechanisms 85 and 86 attached to one side of the can support frame 35 is wound around the chain wheel 84 . By synchronously operating the cylinder mechanisms 85 and 86 so that one of them is extended and the other contracted, the stopper 81 is rotated and reversed via the chain 87 and the chain wheel 84. is being done.

Moreover, U-shaped nozzle fixing members 88 and 89 are rotatably attached to the upper and lower parts of the can 61. Projections are formed on the nozzle fixing members 88 and 89, and a cylinder mechanism 90, which is rotatably attached to the outer wall of the can 61, is attached to the projections.
91 are connected. In addition, the nozzle fixing member 8
A fixing plate 93 having a screw rod 92 is screwed into each of the fixing plates 8 and 89.

As shown in FIGS. 13 to 15, four nozzle receiving mechanisms 94 and 95 are attached to the top and bottom of two orthogonally adjacent outer walls of the can 61, respectively. The nozzle receiving mechanism 94 is constructed as shown in FIGS. 18 to 20. That is, a holding plate 96 is attached to a pin 97 at the base of the collar 62 of the can 61.
It is attached like a hinge. Holding plate 96
A long hole 98 is formed in the holding plate 96, and the holding plate 96 is connected to a bracket 102 provided at the upper end of the collar 62 through a pin 99, a link 100, and a pin 101 fitted in the long hole 98. . The pin 99 has a yoke 10 provided at the tip of a piston rod 104 of a cylinder mechanism 103 rotatably attached to the outer wall of the can 61 via a bracket.
5 are connected. A notch hole 106 is formed in a portion of the collar portion 62 that faces the retaining plate 96.
The holding plate 96 is operated by the cylinder mechanism 103.
It is designed to rotate around a pin 97 between the position of the holding plate 96 shown in FIG. 18 and the position of the holding plate 96 shown in FIG. Nozzle receiving mechanism 9
5 is similar to the nozzle receiving mechanism 94, so its explanation will be omitted.

Further, on the upper and lower parts of the can 61, there is a nozzle pressing mechanism 107 located at the upper right corner in FIG.
is installed. This nozzle pressing mechanism 10
7, as shown in FIG. 16, a bell crank 109 is rotatably attached to the base of the collar portion 62 via a pin 108, and a bell crank 109 is rotatably attached to the upper end of this bell crank 109 via a pin 110. A press plate 111 is rotatably attached to the outer wall of the can 61 via a bracket and a pin 112, and a yoke 114 provided at the tip of the piston rod 113 is attached to the lower end of the bell crank 109 via a pin 115. Connected cylinder mechanism 11
It consists of 6. Note that a bell crank 10 is provided in a portion of the collar portion 62 that faces the bell crank 109.
A cutout hole 117 is formed through which 9 can go in and out.

Further, the nozzle receiving mechanism 94 of the can 61,
Support grid pressing mechanisms 120 and 121 are attached to the other two outer walls opposite to the two outer walls to which the fuel assembly 95 is attached, facing a support grid 119 of a fuel assembly 118, which will be described later, inserted into the can 61. It is being As shown in FIG. 17, the support grid pressing mechanism 120 includes brackets 122 and 123 provided on the outer wall of the can 61, a bell crank 125 rotatably attached to the bracket 122 with a pin 124, and a pin 126 attached to the bracket 123.
A lever 127 rotatably attached to
A pressing plate 130 is rotatably attached to the bell crank 125 and the lever 127 by pins 128 and 129, and a pin 131 is attached to the bracket 123.
The tip of the piston rod is connected to the bell crank 125 by a pin 132.
The cylinder mechanism 133 is rotatably connected to the cylinder mechanism 133. Further, an appropriate hole 134 is formed in the outer wall of the can 61 at a portion where the pressing plate 130 enters and exits. Note that the support grid pressing mechanism 121 is the same as the support grid pressing mechanism 120, so a description thereof will be omitted.

Note that a holding mechanism is constituted by the nozzle fixing members 88 and 89, the nozzle receiving mechanisms 94 and 95, the nozzle pressing mechanism 107, the support grid pressing mechanisms 120 and 121, and the like. Further, pipes are connected to each of the cylinder mechanisms, and these pipes are appropriately extended to the upper fixing plate 13 and connected to an operating unit (not shown) provided on the upper fixing plate 13.

Next, the operation of the fuel assembly holding device configured as described above will be explained.

To pull out a damaged fuel rod from a fuel assembly containing the damaged fuel rod, attach the upper fixing plate 13 to the upper part of the wall 12 of the fuel transfer canal 11, lower the long box wrench onto the upper fixing plate 13, and remove the broken fuel rod. Fit a box wrench to the upper ends of the shafts 26, 29 and turn them to attach the fixing members 19, 20 to the wall 12.
The lower fixing plates 17 and 18 are fixed to the wall 12 by extending to the side.

Next, the cylinder mechanisms 48 of the positioning mechanisms 42 and 43 are operated to open the levers 46 and 47, and the electric winch 30 is operated to move the can support frames 34 and 35 through the wire ropes 38 and sheaves 32 and 37. lower the upper end of the can 61 to a height of 7 m from the horizontal level of the fuel transfer canal 11.
the protrusion 3 by the positioning mechanism 44.
9 is received in the recess 51.

Next, the cylinder mechanism 90 at the top of the can 61
is activated to collapse the nozzle fixing member 88 and open the upper end of the can 61.

Next, the fuel assembly 118 containing the damaged fuel rods is suspended by a pit crane (not shown) provided above the fuel transfer canal 11 and transferred to the fuel transfer canal 11 in water, and is placed at the bottom of the can 61. The lower nozzle is placed on the fixing plate 93 of the nozzle fixing member 89 by lowering the lower nozzle and inserting it into the can 61 .

Next, the retaining plate 96 of the nozzle receiving mechanism 94, 95
While the can 61 is held upright, the cylinder mechanisms 116 of the nozzle pressing mechanisms 107 provided on the upper and lower sides of the can 61 are operated, and the upper and lower nozzles are moved by the pressing plate 111 to the nozzle receiving mechanisms 94 and 9.
It is pressed against the holding plate 96 of No. 5 and held.

Next, the cylinder mechanism 133 of the support grid pressing mechanism 120, 121 is operated to release the bell crank 125.
Each support grid 119 is fixed to the can 61 by pressing the pressing plate 130 against the support grid 119 via the support plate 130 . (When the cylinder mechanism 133 is extended or contracted, the pressing plate 13 is moved through the bell crank 125 and the lever 127.
0 moves in parallel and approaches and separates from the support grid 119. ) Note that the multiple cylinder mechanisms 133 operate synchronously.

Next, the cylinder mechanism 90 is operated to rotate the nozzle fixing member 88 to position the fixing plate 93 above the upper nozzle. Next, the positioning mechanisms 42, 4
3, the levers 46 and 47 are activated, and the electric winch 30 is activated to raise the can support frames 34 and 35 via the wire rope 38 and the sheaves 32 and 37, and lift the upper end of the can 61. The cylinder mechanism 48 is located approximately 3 m below the water surface of the fuel transfer canal 11.
levers 46, 4 of the positioning mechanism 42.
7 is closed and the protrusion 39 is received in the recesses 49 and 50.

Next, lower a long box wrench from above the upper fixing plate 13, fit it into the hexagonal bar formed at the top of the screw rod 92, and turn the screw rod 92 to secure the fixing plates of the nozzle fixing members 88, 89. The fuel assembly is fixed between 93 and 93.

Next, the cylinder mechanisms 79 and 80 are operated synchronously, and the stoppers 77 and 78 are removed from the can 61.

Next, on the upper fixing plate 13, the shaft 72 is
A motor (not shown) connected to this shaft 72 is actuated to rotate the can 61 via the clutch 71, shaft 68, worm 69, worm wheel 67, shafts 63, 65, and frames 64, 66. Rotate in the direction of arrow C in the figure to reverse it. As a result, the lower nozzle is located above and the upper nozzle is located below the lower nozzle. Incidentally, before the rotation of the can 61 starts and the can 61 is reversed, the cylinder mechanisms 85 and 86 are operated synchronously, the stopper 81 is reversed, and the opening is opened to the right side of the can 61 in FIG. to be located.

Next, the cylinder mechanisms 79 and 80 are operated synchronously, and each pair of stoppers 77 and 78 is moved to the can 61.
These stoppers 77 and 78 clamp the can 61 and prevent the can 61 from rotating.

After that, the cylinder mechanism 91 is operated to collapse the nozzle fixing member 89 to open the upper end of the can 61, and as necessary, the can 61 is moved up and down by moving the can support frames 34 and 35 up and down. By fixing it in place, it is possible to remove the lower nozzle from the fuel assembly in the can 61 and pull out the damaged fuel rod so that the fuel assembly can be reused.

The operation and operation of each of the mechanisms described above is carried out while monitoring the television cameras 135 and 136 shown in FIGS. 2 and 4 by moving them as appropriate.

As explained above, according to the present invention, a can that is vertically movably submerged in water in a water tank is fixed to the water tank, and a fuel assembly inserted into the can is connected to the nozzle fixing member, the nozzle receiving mechanism, and the nozzle. The structure is such that the can is fixed to the can using a holding mechanism such as a pressing mechanism and a support grid pressing mechanism, the can is inverted and fixed to the water tank, and the can is moved up and down. The operation of removing the lower nozzle from the assembly, pulling out the damaged fuel rod, inserting a dummy rod in its place, and attaching another lower nozzle to the fuel assembly so that the fuel assembly can be reused. This makes it possible to save a huge amount of costs.

[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 front view of the frame, FIG. 6 is a side view of the frame, and FIG. 7 is a plan view of the upper fixing plate. Figure 8 is an enlarged plan view of the lower fixing plate, and Figure 9 is an enlarged plan view of the lower fixing plate.
Figures 1 and 10 show the mechanism for fixing the lower fixing plate to the wall, Figures 11 and 12 show how the can is installed, and Figures 13 to 15 show the structure of the fuel assembly. FIG. 16 is a view showing the holding mechanism attached to the can; FIG. 16 is a view taken in the direction of the arrow in FIG. 15; FIG. 17 is a view showing the support grid pressing mechanism installed; FIGS. FIG. 20 is a sectional view taken along the - line in FIG. 19, showing the state in which the nozzle receiving mechanism is installed. 11...Fuel transfer canal (water tank), 13...
Upper fixing plate, 15, 16...Guide frame, 1
7, 18... Lower fixing plate, 19, 20... Fixing member, 30... Electric winch, 32, 37... Sheave, 34, 35... Can support frame, 3
8...Wire rope, 39...Protrusion, 42,4
3, 44...positioning mechanism, 61...can, 6
3, 65...axis, 67...worm wheel, 6
8,72...shaft, 69...worm, 71...clutch, 77,78...clutch, 79,80...
... cylinder mechanism, 85, 86... cylinder mechanism,
81... Stoppa, 84... Chain wheel, 8
7... Chain, 88, 89... Nozzle fixing member,
94, 95... Nozzle receiving mechanism, 107... Nozzle pressing mechanism, 118... Fuel assembly, 119...
Support grid, 120, 121...Support grid pressing mechanism.

Claims (1)

[Claims] 1 A fuel assembly holding device used when disassembling and assembling the fuel assembly by attaching and detaching the lower nozzle of the fuel assembly having an upper nozzle and a lower nozzle fixed to the upper and lower ends, respectively, A water tank in which the water is stored, an upper fixing plate fixedly provided on the upper part of the water tank, a frame body connected to the upper fixing plate and fixed in the water tank, and having a shaft and being connected to the water tank through the shaft. a can that is vertically movable and rotatably held by the frame and positioned in the water and into which the fuel assembly is inserted; and an operating section that is connected to the can and reaches the top of the water tank. a vertical movement mechanism that moves the can up and down when the operating section is operated; and an operating section that is connected to the can and reaches the top of the water tank, and when the operating section is operated, the can is moved vertically. a rotation mechanism connected to the frame and removably engaged with the can to prevent rotation of the can; a stopper attached to the can and inserted into the can; and a holding mechanism for holding the fuel assembly in the can by pressing the fuel assembly held in the can, and inverting the can with the fuel assembly held inside to place the lower nozzle above the upper nozzle. A fuel assembly holding device, characterized in that the fuel assembly is positioned and fixed in the water of the water tank.