JPS645666B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides a fuel assembly support for grinding a deformed part of a semi-used or spent fuel assembly support grid or for cutting a part of the support grid to take out a fuel rod. This invention relates to a grating remote controlled underwater gripping device.

The fuel assemblies that make up the core of pressurized water reactors currently in use are removed from the core after a certain period of combustion, undergo various inspections, and then are reloaded into the reactor. During fuel handling such as loading and unloading into the reactor, fuel assemblies may interfere with each other, resulting in slight damage or deformation to part of the sides and corners of the support grid outer periphery of the fuel assemblies. It can happen sometimes. Such fuel assemblies cannot be reused because it is geometrically difficult to reload them into the reactor and construct the reactor core, so they have lost their value as fuel. For this reason, it has been desired to develop a remote-controlled underwater repair device that can restore the value of the support grid as a fuel by polishing and repairing a portion of the support grid that has suffered such minute damage and produced protrusions.

In addition, among the fuel assemblies burned in the reactor core, fuel assemblies with leaking fuel rods or fuel rods suspected of leaking, and fuel assemblies in which fretting between the support grid and fuel rods has been observed. In order to remove a fuel rod or observe the inside of a support grid by cutting a part of the support grid, it has been desired to develop a remote-controlled underwater cutting device for the support grid.

Regarding the underwater remote repair device for fuel assembly support grids, patent application No. 16437 of 1982 (Japanese Patent Application Laid-Open No. 1983-1983) was previously filed.
112693), in which a fuel assembly is fixed upright to a fixed part provided in the water of a spent fuel pit, and a tool support is also attached to the fixed part in the water. Using a tool movably attached to the lower end of the pillar, the damaged part of the support grid can be ground away while checking the grinding position with an underwater television camera.

However, since the device is fixed in the spent fuel pit, it is inconvenient and costly to transport the device to another nuclear power plant for use.

The present invention has been made in view of the above circumstances, and provides a remote-controlled underwater gripping device for fuel assembly support grids that is small, lightweight, has low manufacturing costs, does not take up much space, and can be easily changed in its use location. The purpose is to

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. Reference numeral 1 in FIG. 1 is a spent fuel pit in which water is stored, and within this spent fuel pit 1, a fuel assembly 2 is held with its upper nozzle 3 held by a fuel handling tool 4 by generally known means. It is kept in a suspended position.

The fuel assembly 2 includes a plurality of support grids 5 that are spaced apart and facing each other, a large number of control rod guide tubes 6 that are inserted through these support grids 5, and upper parts that are attached to the upper and lower parts of these control rod guide tubes 6. It consists of a nozzle 3, a lower nozzle 7, and fuel rods 8 located between the upper nozzle 3 and the lower nozzle 7 and inserted into the support grid 5 in a grouped manner.

The water in the spent fuel pit 1 is stored for temporary storage or repair of the fuel assembly 2, and in this water, the fuel handling tool 4 and the support column 9 placed close to the fuel assembly 2 are installed with a crane. It is suspended and movably held. A frame-shaped main body 10 is attached to the lower end of the support column 9, as shown in FIGS. 2 to 4. As shown in FIG. 3, the main body 10 has a receiving part 1 consisting of a bracket.
1 and 12 are provided. The receiving parts 11 and 12 are provided along planes that are perpendicular to each other, and are
It has receiving surfaces 13 and 14 that can receive two orthogonally adjacent surfaces of the support grid 5. A central portion of a bell crank 16 is rotatably attached to one end of the receiving portion 11 via a shaft 15. The tip of a piston rod of a cylinder mechanism 17 rotatably attached to the receiving portion 11 is rotatably attached to one end of the bell crank 16. A pressing member 18 having a pad is provided at the other end of the bell crank 16.
is rotatably attached.

Further, the main body 10 is provided with a bracket 19, and a central portion of a bell crank 21 is rotatably attached to one end of the bracket 19 via a shaft 20. At one end of the bell crank 21, the tip of a piston rod of a cylinder mechanism 22, which is rotatably attached to the bracket 19, is rotatably attached. A pressing member 23 having a pad is rotatably attached to the other end of the bell crank 21. The cylinder mechanisms 17 and 22 are each connected to a remote control section 24 provided at the upper part of the side wall of the spent fuel pit 1 by a connecting tube. And these bell cranks 16,
The cylinder mechanism 17 and the pressing member 18 constitute a series of pressing mechanisms, and the bell crank 21, the cylinder mechanism 22, and the pressing member 23 constitute another pressing mechanism.

Further, a cylinder mechanism 25 is attached to one side of the main body 10, and a piston rod of this cylinder mechanism 25 passes through the main body 10, and a yoke 26 is attached to the tip thereof. A pinion 27 is rotatably attached to the yoke 26. A rack 28 is provided at the top of the main body 10,
A pinion 27 is engaged with this rack 28. A guide bar 29 is provided at the bottom of the main body 10 in parallel with the rack 28. This guide bar 29 includes a tool holder 30 and a rack holder 31.
are slidably fitted. A rack 32 is attached to the upper part of each of the tool fixture 30 and the rack holder 31.
is installed. The pinion 27 is engaged with this rack 32. Further, a rotary shaft 33 is rotatably attached to the lower part of the main body 10 parallel to the rack 28. This rotating shaft 33
One end projects from the side wall of the main body 10, and a worm wheel 34 is fixedly attached to this projecting end. The bracket 19 is provided with a bearing portion 35, and a shaft 36 is rotatably supported by the bearing portion 35. A worm 37 is fixedly attached to the shaft 36 and is meshed with the worm wheel 34. A pulley 38 is fixedly attached to the end of the shaft 36, and a wire rope 39 is wound around the pulley 38. The wire rope 39 is movably passed through the support column 9 and taken out from the upper side wall of the support column 9 to the spent fuel pit 1.
The pulley 38 is connected to a remote control section 24 by operating a wire rope 39 at the remote control section 24. A sector gear 40 is fitted to the rotating shaft 33, for example, by being fitted into a key (not shown) provided between the sector gear 40 and the rotating shaft 33 so as to rotate together with the rotating shaft 33. 33 so as to be movable in the axial direction. Note that the sector gear 40 is aligned with the axis of the rotating shaft 33 together with the tool fixture 30 by fitting a protrusion (not shown) provided on the tool fixture 30 into a recess (not shown) provided in the upper part of the sector gear 40 . It is possible to move in the direction. Further, a mounting shaft 41 is fitted into the lower part of the tool fixture 30 so as to be movable in a direction perpendicular to the rotating shaft 33. A rack 42 is formed on the upper surface of this mounting shaft 41 (the surface on the side of the sector gear 40), and the sector gear 40 is meshed with this rack 42. A tool holder 4 is attached to one end of the mounting shaft 41.
3 is installed. A tool 45 having a grinding grinder 44 or a tool 47 having a cutting grinder 46 is fitted and attached to the tool holder 43 . The grinder 44 of the tool 45 is covered by an adapter 48, and a chip collection device (not shown) having a built-in metal filter is connected to the adapter 48 via a pipe 49. As shown in FIG. 5, the tool 47 includes a cutting grinder 46 that can be moved up and down by operating a wire 50 that is attached to the cutting grinder 46 and led to the remote control section 24. is being done.

Further, brackets 52 and 53 are rotatably attached to the main body 10 via a shaft 51. One end of each of these brackets 52, 53 is fixed to shaft 51. A bevel gear 54 is attached to the upper end of the shaft 51. Further, a pulley 57 is rotatably attached to the main body 10 via a bearing 55 and a shaft 56. Pulley 57 is connected to shaft 56
is fixed. A wire rope 58 is wound around this pulley 57, and this wire rope 58 is wound around a pulley 59 rotatably attached to a bracket (not shown) extending from the upper part of the side wall of the spent fuel pit 1. and this pulley 59
It is connected to the remote control section 24 via. A bevel gear 60 is attached to one end of the pulley 59, and this bevel gear 60 meshes with the bevel gear 54. A shaft 61 is attached to the brackets 52 and 53.
An underwater television camera 63 is rotatably attached via a holder 62. By operating the wire rope 58 at the remote control unit 24, the shaft 55 is rotated via the bevel gears 60, 54, and thereby the underwater television camera 63 can be moved in parallel via the brackets 52, 53. is being done.

Next, the operation of the fuel assembly support grid remote control underwater gripping device having the above configuration will be explained. First, the fuel assembly 2 to be ground or cut is attached to the fuel handling tool 4, the fuel handling tool 4 is suspended by a crane, etc., the fuel assembly 2 is moved in the spent fuel pit 1, and this fuel assembly is assembled. 2 is kept suspended in the water.

Next, a grinding grinder 44 is attached in advance to the tool holder 43 when grinding the support grid 5, and a cutting grinder 46 is attached when cutting the support grid 5, and the support column 9 and the fuel handling tool 4 are suspended. The receiving part 1 was suspended from a position close to the underwater fuel assembly 2 by a crane different from the one used above, and the receiving part 1 was suspended while observing the fuel assembly 2 with an underwater television camera 63.
The receiving surfaces 13 and 14 of the fuel assembly 2 are brought into gentle contact with two orthogonal adjacent surfaces 5a and 5b of the support grid 5 to be ground or cut.

Next, the remote control unit 24 is operated to operate the cylinder mechanisms 17 and 22 to extend these piston rods. Then, the bell crank 16 rotates around the shaft 15 and presses the support grid 5 toward the receiving part 12 by the pressing member 18, and the bell crank 21 rotates around the shaft 20 and supports it by the pressing member 23. Press the grid 5 toward the receiving part 11,
12 and pressing members 18 and 23 grip the support grid 5.

Next, the portion of the support grid 5 to be ground or cut is inspected and confirmed using the underwater television camera 63, and the remote control section 24 is operated to operate the cylinder mechanism 25. Then, the tool holder 26 moves in the directions of arrows A and B in FIG.
rotates, and the rack 32 moves along the guide bar 29 together with the tool fixture 30 in the directions of arrows A and B in the figure. Therefore, tool 45 or tool 47
The tool holder 30 also moves in the same direction as the tool holder 30. Note that at this time, the stroke of the tool 45 or tool 47 is twice the stroke of the piston rod of the cylinder mechanism 25, since the rack 32 is engaged with the rotating pinion 27 and is movable. .

Next, in this state, while inspecting the area around the part of the support grid 5 to be ground or cut using the underwater television camera 63, the wire rope 39 is operated using the remote control unit 24 to rotate the pulley 38. Then, axis 3
6. The rotating shaft 33 rotates via the worm 37 and the worm wheel 34, and the sector gear 40 rotates together with this rotating shaft 33. As the sector gear 40 rotates, the tool 45 or 47 is moved through the mounting shaft 41 and the tool holder 43 by arrows C and D in FIG.
move in the direction. Therefore, when the grinding grinder 44 or the cutting grinder 46 is rotated and brought into contact with the support grid 5, the portion of the support grid 5 to be ground or cut is ground or cut.

Next, when the grinding or cutting of the support grid 5 is completed as described above, the tool 45 or the tool 47 is moved in the direction D in FIG. 2 by operating the wire rope 39, and then the arrow A or the arrow in FIG. B
The support grid 5 is moved toward one side of the main body 10 and stopped, and the underwater television camera 63 is used to confirm that the machining condition of the grinding or cutting portion of the support grid 5 is good.

Next, when the pressing mechanism is operated to shorten the cylinder mechanisms 17 and 22, the bell crank 16,
The pressing members 18, 23 are separated from the support grid 5 via the
4 is released from gripping the support grid 5.

All of the above operations can be performed by a crane outside the spent fuel pit 1 or by the remote control section 24.

As explained above, according to the present invention, a support column is movably suspended in water, and two adjacent orthogonal support columns of a support grid of a fuel assembly suspended in water are suspended.
The surface is received by a receiving part of the main body provided at the lower part of the support column by remote control, and the supporting grid is held underwater by the pressing mechanism provided on the main body and the receiving part, so it is small. It has the following advantages: it is lightweight, its manufacturing cost is low, it does not take up much space, its location can be easily changed, and its installation is simple.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram showing one embodiment of the present invention, Fig. 2 is a partially cutaway vertical side view of the main part, Fig. 3 is a plan view of the main part, and Fig. 4 is a diagram of the main part. The front view and FIG. 5 are diagrams showing a state in which a tool having a cutting grinder is attached to the tool holder. 2...Fuel assembly, 5...Support grid, 9...Support column, 10...Main body, 11, 12...Receptacle, 24
...Remote control unit, 63...Underwater television camera.

Claims (1)

[Claims] 1. A supporting column movably suspended in the water,
a main body provided at the lower part of the support column; a receiving part provided on the main body for receiving two orthogonal adjacent surfaces of the support grid of the fuel assembly suspended in the water; a pressing mechanism provided on the main body that can press the support grid of the body; a remote control unit connected to the pressing mechanism and provided above the water so as to be able to operate the pressing mechanism; 1. A remote-controlled underwater grasping device for a fuel assembly support grid, comprising: a television camera installed at a lower part of the support grid so as to be able to observe the outer peripheral surface of the support grid.