JPS6324279B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel channel attaching and detaching machine for attaching and detaching channel boxes for inspecting fuel bundles.

Generally, nuclear reactor fuel is usually inserted into many pipes, and the many pipes are bundled into a prismatic fuel bundle, and the fuel bundle is covered with a prismatic channel box. Loaded into the reactor core. Then, depending on the predetermined burnup, shuffling within the core or replacement with new fuel is performed. A visual inspection of the fuel bundle is also performed periodically, which requires the removal of the channel box from the fuel bundle. Therefore, a fuel channel attachment/detachment machine (hereinafter simply referred to as an attachment/detachment machine) is provided for the purpose of inspecting the fuel bundle, and this attachment/detachment machine removes the channel box covering the fuel bundle and visually inspects the fuel bundle. After confirming the integrity of the fuel bundle, it is reused, re-inspected, or reprocessed.

FIG. 1 schematically shows the entirety of a conventional attachment/detachment machine, and the attachment/detachment machine 1 mainly consists of a main body 2, a cart 3, and a drive mechanism 4. The main body 2 is attached to one side of the spent fuel pool 5 along the vertical direction, and supports the cart 3 so as to be movable up and down. The vertical position of the cart 3 is maintained by a wire rope 18 wrapped around the sheave and an idler sheave 14 provided at the lower end of the pool. A lower support 10 that receives the weight of the fuel assembly 9 and an upper guide 11 that supports the fuel assembly 9 so that it stands upright and does not fall over are substantially integrally formed in the cart 3. Then, the cart holding the fuel assembly is raised and lowered, the channel box is removed, and the fuel bundle is inspected. This operation is carried out manually and remotely from the refueling floor 6. The figure shows a state in which the channel box 7 is removed from the fuel assembly 9 by the auxiliary hoist 17 via the channel handling tool 13 and pulled up.

FIG. 2 shows the channel box being moved using the auxiliary hoist 17. Since the channel box 7 is highly radioactive, it is necessary to handle it while maintaining a predetermined water depth from the pool water surface 16. In Figure 3, channel box 7
After the fuel bundle 8 has been removed, the bail 19 fixed to the top thereof is grabbed by a handling tool (not shown), and
The fuel inspection cart 3 is visually checked using an underwater periscope or an underwater television while rotating or moving the fuel inspection cart 3 up and down by the drive motor 4. Conventionally, an air motor has been used as a mechanism for lifting and lowering this fuel inspection cart, but an electric mechanism drive is desired due to problems such as improved product reliability, improved accuracy in lifting and lowering positions, and improved constant speed control. Each of the devices built into the elevating drive mechanism driven by the electric mechanism is a very precise device, and requires maintenance such as oiling and inspection. If the drive section is maintained while the main body is still installed, there is a high risk of it falling into the pool, and work efficiency is also poor. When maintaining the drive part by lifting the entire main body, there are disadvantages in maintainability such as exposure to radiation from pool water and difficult work due to the length of the product.

SUMMARY OF THE INVENTION An object of the present invention is to propose a channel attachment/detachment machine that allows easy attachment and detachment of the drive section, in order to reduce exposure and reduce time required for maintenance of the drive section.

To achieve the above object, the present invention provides a fuel channel attachment/detachment machine that includes a vertical member installed underwater, a cart that moves up and down along the vertical member to hold a fuel assembly, and a fuel channel attachment/detachment machine installed above the water surface of the vertical member. A sprocket that is rotatably installed at the upper end, a chain that is wrapped around the sprocket and attached to the cart, a coupling that is connected to the rotating shaft of the sprocket, a motor that is connected to the coupling, and a motor that rotates the rotating shaft of the sprocket. It consists of a fixing member that holds the cart movably, and a cart fall prevention pin that is inserted into the rotating shaft of the sprocket through the fixing member.

The present invention will be explained in detail below based on the drawings.

A preferred embodiment of the present invention is shown in FIGS. 4 to 6.

FIG. 4 shows a structural diagram of the motor drive mechanism. The motor 20 is driven by a shaft converter 21 using bevel gears.
The signal is transmitted to the speed reducer 22 via. Additionally, a torque limiter 23 is provided between the reducer 22 and the shaft converter 21.
This ensures the safety of the roller chain. A shaft 25 to which a sprocket 26 is fixed is connected to the output shaft of the reducer 22 by a coupling ring 31 and held by a pillow block 24. A chain 27 connected to the cart 3 is engaged with the sprocket 26 to raise and lower the cart 3. In this structure, the driving force of the motor 20 is transmitted to the shaft converter 21, the reducer 22, the shaft 25,
It is transmitted to the sprocket 26, and the sprocket 26
The cart 3 moves up and down by the rotation of. Further, a reducer 28 is further connected to the shaft 25 to reduce the rotational speed of the shaft 25 and transmit it to the rotating shaft of the cam. The position of the fuel inspection cart is controlled by a limit switch 30 through the rotation of the cam 29. It also has a mechanism that uses the rotation of the sprocket shaft to digitally display the elevation position by detecting pulses.

Next, installation and removal of the drive section will be explained.

In FIG. 5, vertical grooves 33 are provided at four locations on the drive unit mounting plate 32, and convex portions matching the structure are provided at four locations on the drive box 34 to eliminate misalignment with the drive unit mounting plate 32. At the bottom of the mounting plate, there is a plate 35 for fixing the drive unit.
The drive box 34 was fixed by providing a.
Further, the drive unit mounting box 34 is provided with a pothole and is fixed to the drive unit mounting plate 32 with hexagon socket head bolts. The hexagon socket head bolt has a wiring ring to prevent it from falling and loosening. The drive section is removed after the movement of the fuel inspection cart 3 relative to the main body frame 2 is restrained and the main body frame 2 and the fuel inspection cart 3 are integrated. That is, the drive section is removed after the fuel inspection cart 3 is prevented from falling. To prevent the fuel inspection cart 3 from falling,
It is sufficient to fix the roller chain 27 for raising and lowering the fuel inspection cart, and in the present invention, this fixing is provided on the sprocket shaft 25 through a hole provided in a fixing member 39 that rotatably holds the sprocket shaft 25. This is done by inserting the fuel inspection cart fall prevention pin 36 into the fuel inspection cart fall prevention hole. After preventing the fuel inspection cart from falling in this way, the drive box 34 can be separated from the main body frame 2 and the fuel inspection cart 3 by removing the roller chain couplings 31, 31' that fix both ends of the sprocket. It becomes possible.

Since the drive box 34 is fixed to the drive unit mounting plate 32 with hexagon socket bolts, the hexagon socket bolts are loosened and the drive box 34 is lifted up by an overhead crane or an auxiliary crane. The drive box 34 is separated into a drive system 37 and a control system 38, but they are in the same box, so that they can be installed and removed in the same way.

The drive mechanism with the above structure allows only the drive unit to be installed and removed with the main body frame 2 and cart 3 installed, making it easy to inspect and maintain each device within the drive mechanism. Because of this, it is possible to reduce radiation exposure,
There is no longer a need to handle a long object such as the entire main body, so maintenance can be shortened and work safety can be ensured.

[Brief explanation of the drawing]

Figure 1 is an overall schematic diagram of a conventional channel attachment/detachment machine.
Fig. 2 is an explanatory diagram of the operation of the auxiliary hoist, Fig. 3 is an external view of the channel attachment/detachment machine shown in Fig. 1, Fig. 4 is a detailed view of the drive mechanism, Fig. 5 is a plan view of the drive mechanism, and Fig. 6 is a diagram illustrating the operation of the auxiliary hoist.
The figure is a removed view of the drive mechanism. 3... Cart, 4... Drive mechanism, 5... Spent fuel pool, 7... Channel box, 8...
Fuel bundle, 32...Drive unit mounting plate, 3
3... Vertical groove, 34... Drive box, 35...
Drive unit fixing plate, 36...Fall prevention pin, 3
7... Drive system, 38... Control system, 39... Fixed member.

Claims (1)

[Scope of Claims] 1. A vertical member installed in the water; a cart that moves up and down along the vertical member to hold a fuel assembly; and a cart rotatably installed at the upper end of the vertical member above the water surface. a chain wrapped around the sprocket and attached to the cart; a coupling coupled to the rotating shaft of the sprocket; a motor coupled to the coupling; and a motor capable of freely rotating the rotating shaft of the sprocket. A fuel channel attaching/detaching machine comprising: a fixing member that is held on the sprocket; and a cart fall prevention pin that is inserted into the rotating shaft of the sprocket through the fixing member.