JPH0226080Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a nuclear fuel transfer device.
In particular, the present invention relates to a nuclear fuel transfer system in which nuclear fuel is transferred by a transfer vehicle that enters and exits the containment vessel through a transfer pipe that penetrates the containment vessel bulkhead.

[Conventional technology]

During periodic inspections of nuclear power plants, nuclear fuel transfer is required to remove fuel assemblies taken from the reactor from the reactor containment vessel, or to transport fuel assemblies to be loaded into the reactor into the reactor containment vessel. A device is used. The nuclear fuel transfer device is installed in each fuel transfer canal connected by a transfer pipe embedded through a partition wall separating the inside of the reactor containment vessel and the fuel handling building.

Conventional nuclear fuel transfer devices penetrate the bulkhead of the reactor containment vessel, extend almost horizontally, and connect the reactor cavity inside the containment vessel with the spent fuel pit outside the containment vessel. A track extending between the reactor cavity and the spent fuel pit, a nuclear fuel receiving container for receiving nuclear fuel therein, are pivotally mounted, and a transfer vehicle capable of traveling on the track and driving the transfer vehicle along the track are mounted. The reactor cavity is equipped with a drive device that moves the nuclear fuel receiving container into and out of the reactor cavity. The drive device is formed into a long loop along the track by passing around chain sprockets near both ends of the track. The transfer vehicle is moved along a track by driving a chain, and the nuclear fuel receiving container thereon is moved in and out of the reactor containment vessel.

In such conventional nuclear fuel transfer equipment,
For example, when transferring nuclear fuel from a nuclear reactor containment vessel to a spent fuel pit, an underwater limit switch detects that the transfer vehicle has been inserted a predetermined distance into the containment vessel and stops it at a predetermined position. Next, the nuclear fuel receiving container pivoted on the transfer device is rotated until it comes into contact with a stopper on the track support structure, and the container is erected. In this upright position, the nuclear fuel removed from the core can be placed into a container using fuel handling equipment such as a crane. The container containing the nuclear fuel is then tipped into a horizontal position to allow the transfer vehicle to pass through the transfer pipe, and the transfer vehicle is pulled out of the containment vessel so that the nuclear fuel receiving container is completely located within the spent fuel pit. Make it. At this point, the nuclear fuel receiving container is again brought into an upright position and the nuclear fuel is removed from the container by fuel handling equipment such as a crane and stored in a spent fuel pit.

[Problem that the invention attempts to solve]

However, in conventional nuclear fuel transfer systems, as mentioned above, an underwater limit switch is used to detect the position, and a chain is used as a drive device. The transport vehicle may not be able to stop accurately at a predetermined position. If the stop position of the transfer vehicle is inaccurate, the position of the nuclear fuel receiving container itself will deviate from the predetermined position, and the relative position of the nuclear fuel receiving container and the stopper on the support structure will also deviate, causing the position and posture of the nuclear fuel receiving container to change. It deviates from the predetermined position and posture. Therefore, it becomes extremely difficult to deliver nuclear fuel to and from containers, and furthermore to transfer nuclear fuel.

[Means for solving problems]

In order to solve this problem, the nuclear fuel transfer device of the present invention has a rack provided along almost the entire length of the transfer vehicle, a pinion gear provided in the pit and engaged easily, and a control section provided at the top of the pit. and a gear train that couples a pinion gear to the drive motor and transmits rotation of the drive motor to the pinion gear.

[Effect]

This type of rack-and-pinion drive device has higher positional accuracy than the conventional chain-type drive device, and can stop the transport vehicle at a predetermined position, so there is no need to use a position detection device such as a limit switch. Since the nuclear fuel receiving container can be erected with high accuracy, nuclear fuel transfer work becomes easier and the structure of the nuclear fuel transfer device becomes simpler.

〔Example〕

Next, the present invention will be explained along with embodiments of the present invention shown in the accompanying drawings.

FIG. 1 shows a schematic cross-sectional view of a nuclear fuel transfer device of the present invention applied to a nuclear power plant. The illustrated nuclear power plant includes a reactor containment vessel 4 forming a reactor cavity 3 for accommodating a nuclear reactor (not shown) formed by a bulkhead 1 and a floor 2, and a bulkhead 1 outside the reactor containment vessel 4. A spent fuel pit 5 is provided adjacent to the fuel tank. A nuclear fuel transfer device 6 is provided in the partition wall 1 so as to pass through the partition wall 1 and straddle the reactor cavity 3 in the reactor containment vessel 4 and the spent fuel pit 5 .

The nuclear fuel transfer device 6 extends substantially horizontally through the partition wall 1 of the reactor containment vessel 4, and communicates the bottom of the reactor cavity 3 inside the containment vessel with the bottom of the spent fuel pit 5 outside the containment vessel. A transfer pipe 7 is provided. The transfer pipe 7 is a tubular member with both ends open, and one end (the left end in the figure) is opened into the reactor cavity 3, and the other end (the right end in the figure) is opened into the spent fuel pit 5.

The nuclear fuel transfer device 6 also includes a track 8 that extends within the transfer pipe 7 and spans the inside of the reactor cavity 3, that is, the containment vessel, and the spent fuel pit 5. The track 8 consists of three tracks 9, 10 and 11 each having two rails. The first rail 9 is provided within the reactor cavity 3 and supported on a support structure 12 fixed to the bottom wall of the reactor cavity 3 . The support structure 12 is provided with mechanical stops 13 and 14, which will be explained later. The second rail 10 is fixed to the bottom of the transfer tube 7. The third rail 11 is provided within the spent fuel pit 5 and supported on a support structure 15 fixed to the bottom wall of the spent fuel pit 5. . Although not shown, stops similar to the stops 13 and 14 are provided on the support structure 15. The first to third rails 9 to 11 are aligned with each other, and the spacing between the abutting ends is made as small as possible so that the wheels can run thereon without difficulty.

Reactor cavity 3 and spent fuel pit 5
A transport vehicle 17 is provided on the track 8 which extends over the track 8 and is supported on the track 8 so as to be movable on the track 8 by means of wheels 16. Transport vehicle 17
is a long member with a substantially U-shaped cross section, and at the left end in the figure is a nuclear fuel receiving container 18 that receives and holds a fuel assembly (not shown) therein, and is pivoted by a pin 19. By means of a known suitable actuating device (not shown), the transport vehicle 17 can be selectively rotated between an upright position shown in solid lines and a horizontal position shown in two-dot chain lines when it is in a predetermined position shown in solid lines in FIG. It is being done. For this purpose, at least this part of the U-shaped transfer vehicle 17 has no bottom wall so as not to impede the rotation of the nuclear fuel receiving container 18. When the transfer vehicle 17 is placed in a predetermined position and the nuclear fuel receiving container 18 is rotated counterclockwise until it comes into contact with the stoppers 13 and 14, the nuclear fuel receiving container 18 is accurately stopped and held in the upright position shown by the solid line. Fuel exchange work can be performed easily and quickly using a crane or the like (not shown) inside the reactor containment vessel. The length of the transfer vehicle 17 is such that when the nuclear fuel receiving container 18 on the transfer vehicle 17 is placed at a predetermined position within the reactor containment vessel 4, the other end of the transfer vehicle 17 comes out from the bulkhead 1 and enters the spent fuel pit. The length is such that it remains within 5.

The nuclear fuel transfer device 6 also moves the transfer vehicle 17 onto the track 8.
Driving along the nuclear fuel receiving container 18
A drive device 20 for moving in and out of the containment vessel 4
It is equipped with According to the present invention, the drive device 20
As shown in FIGS. 1 and 2, there is a rack 21 provided over almost the entire length of the transfer vehicle 17, a pinion gear 22 provided in the spent fuel pit 5 and meshed with the rack 21, and a used fuel tank. A drive motor 23 with a speed reducer is provided on the floor of the operation section above the spent fuel pit 5, and a gear train connects the drive motor 23 and the pinion gear 22 and transmits the rotation of the drive motor 23 to the pinion gear 22. It is equipped with 24. The position of the phase wheel 17 is detected by an encoder (not shown) that counts the number of rotations of the drive device 20 such as the drive motor 23.

The drive motor 23 is installed on the floor of the fuel handling building above the spent fuel pit 5, and the pinion gear 22 is installed on the floor of the fuel handling building above the spent fuel pit 5.
It is provided in a portion near the transfer pipe 7. The racks 21 are also offset to either side of the transport vehicle 17 so as not to impede the rotation of the nuclear fuel receiving container 18 on the transport vehicle 17 to an upright position. Gear train 24 of drive device 20
As shown in FIG. 2, the bevel gear 26 is connected to the output shaft 25 of the drive motor 23 and the bevel gear 2
6 and a shaft 30 supported by bearings 28 and 29 mounted on the canal wall.
a bevel gear 31 coupled to the bevel gear 27 by a bevel gear 31, a bevel gear 32 meshing with the bevel gear 31, and a support structure 15.
Or a bearing 33 fixed to the bottom of the canal.
and a shaft 35 supported by and 34 for coupling the bevel gear 32 to the pinion gear 22. Each shaft 30 and 35 is provided with a thrust bearing. In the illustrated example, the shaft 35 passes below the track 8 and does not interfere with each other, but if the shaft 35 and the track 8 interfere with each other and become a hindrance, a part of the track 8 is passed through the shaft 35. However, it is possible to remove only the necessary amount so that the rolling of the wheels 16 is not hindered.

When using the nuclear fuel transfer device 6 of the present invention configured as described above, the drive device 20 inserts the transfer vehicle 17 into the reactor containment vessel 4 through the transfer pipe 7 to a predetermined position, and the nuclear fuel receiving container 1
8 is rotated until it contacts the stoppers 13 and 14 to the upright position (solid line in FIG. 1), and the fuel to be replaced in the reactor containment vessel 4 is placed in the nuclear fuel receiving container 18 using a crane or the like. At this time, since the drive device 20 is of a rack-and-pinion type, the transfer vehicle 17 can be accurately stopped at a desired stop position with high reproducibility even by position detection using an encoder or the like of the drive motor 23. , is held in that position by a self-locking mechanism of the drive motor 23 with a speed reducer, making it extremely easy to transfer the fuel to the nuclear fuel receiving container 18.

Next, the nuclear fuel receiving container 18 is attached to the pin 19.
It is rotated clockwise around the center until it becomes horizontal.
To prevent the transfer car 17 from getting in the way when passing through the transfer pipe 7. When the drive motor 23 of the drive device 20 is energized in this state, its rotation is transmitted to the pinion gear 22 via the gear train 20, and the rack 21 attached to the transfer vehicle 17 moves the transfer vehicle 17 into the reactor containment vessel. 4 into the spent fuel pit 5.

The transfer vehicle 17 is stopped at a predetermined position within the spent fuel pit 5 by position detection by an encoder, and the nuclear fuel receiving container 18 is changed from a horizontal position to an upright position (double-dashed line in FIG. 1). At this location, the nuclear fuel in the nuclear fuel receiving container 18 is removed from the container by a fuel handling equipment (not shown) such as a crane in the spent fuel pit 5 and stored in the spent fuel pit 5. At this time as well, the stopping position of the transfer vehicle 17 and the upright precision of the nuclear fuel receiving container 18 are highly reproducible and accurate, so that the work can be done easily and quickly.

[Effect of idea]

As is clear from the above explanation, the nuclear fuel transfer system of the present invention uses a rack-and-pinion type drive unit, which has higher positional accuracy than the conventional chain type drive unit, and has a higher positional accuracy than the conventional chain type drive unit. Since the nuclear fuel receiving container can be stopped at a predetermined position, the nuclear fuel receiving container can be erected with high accuracy without using a position detection device such as a limit switch, the nuclear fuel transfer operation becomes easy, and the configuration of the nuclear fuel transfer device is simplified.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an example in which the nuclear fuel transfer device of the present invention is applied to a nuclear power plant, and FIG. 2 is a schematic diagram showing a driving device for the nuclear fuel transfer device shown in FIG. 1. 1... Bulkhead, 3... Reactor cavity, 4...
...Reactor containment vessel, 5...Spent fuel pit,
7... Transfer pipe, 8... Track, 18... Nuclear fuel receiving container, 17... Transfer vehicle, 20... Drive device, 21... Rack, 22... Pinion gear,
23... Drive motor, 24... Gear train.

Claims (1)

[Scope of Claim for Utility Model Registration] A transfer pipe extending substantially horizontally through a bulkhead of a reactor containment vessel forming a reactor cavity and communicating the reactor cavity with a spent fuel pit outside the containment vessel; a track extending between the reactor cavity and the spent fuel pit through a transfer pipe; a transfer vehicle in which a nuclear fuel receiving container for receiving nuclear fuel is mounted; and capable of traveling on the track; In a nuclear fuel transfer device including a drive device that moves the nuclear fuel receiving container into and out of the reactor cavity by driving along the track, the drive device is provided over substantially the entire length of the transfer vehicle. A rack, a pinion gear provided in the pit and meshed with the rack, a drive motor provided in an operating section above the pit, and a gear train coupling the drive motor and the pinion gear. Nuclear fuel transfer device.