JPH07122679B2 - Fast breeder reactor refueling system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a fast breeder reactor refueling device mounted on a tank-type fast breeder reactor core.

[Conventional technology]

Conventionally, Japanese Patent Publication No. 60-2640 has been proposed in relation to this type of technology.

The refueling machine is a double rotary plug type due to the difference in the structure and operation method of the rotary plug, and the double rotary plug vertically movable system in which the gripper device moves up and down. There are five types of systems: a fixed double rotation plug fixing method that does not rotate the arm, a triple vertical movable method with triple rotation plugs, a single rotation plug fixed arm method with only one rotation plug, and a single rotation plug variable arm method. Is being considered. The fixed arm method is a fixed method in which a fixed arm (pantograph arm) that supports a gripper rotating and opening / closing drive shaft, a pantograph opening / closing shaft, and a gripper device driven by a pantograph opening / closing lever does not rotate. The refueling device that has been conventionally used is a double rotary plug system, and the present invention also relates to improvement of this system. The double rotary plug fixed arm method has two large and small eccentric rotary plugs and a fixed arm, and a gripper device at the tip of a pantograph arm (fixed arm) at any position to be exchanged by combining these rotations. Is a method that can approach.
In this fuel exchanger, a gripper device is attached to a lower end portion of a vertically movable housing via a pantograph arm, and the gripper device and the vertically movable housing cooperate with each other to arrange the gripper device in, for example, a lattice position in a core portion of the reactor vessel. The existing nuclear fuel assemblies are being replaced.

The conventional structure will be described with reference to FIGS. FIG. 5 is an explanatory view of a pantograph type fuel exchanger, and FIG. 6 is a plan explanatory view of a state in which the fuel exchanger of FIG. 5 is attached to a nuclear reactor. In the figure, 1 is a refueling machine, 20 is a reactor vessel, 21 is a roof deck, 23 is a pantograph, 24 is a gripper device, 25 is a vertically moving housing, 26 is a gripper rotation and opening / closing drive shaft,
Reference numeral 27 is a pantograph opening / closing shaft, 28 is a nuclear fuel assembly, 30 is a small rotation plug, 31 is a large rotation plug, 32 is a small rotation plug drive device, 19 is a small rotation plug drive gear, and 33 is a pantograph opening / closing lever.

Since the gripper device 24 is positioned by the cooperation of the rotations of the large and small rotary plugs 31 and 30 and the vertical movement housing 25 of the refueling machine 1, the two large and small rotary plugs 31 and 30 are arranged as shown in FIG. is necessary. On the other hand, large rotation plug 3
Since the small rotation plug 30 is installed on the above 1, the small rotation plug drive gear 19 and the small rotation plug drive device 32 are arranged, so that the diameter of the large rotation plug 31 is increased and the reactor structure is downsized. It is inhibiting. In addition, from the viewpoint of seismic design and strength design, it is essential to remove the small rotating plug 30 in the demonstration reactor.

In addition, here, in the prior art, a pantograph arm
The length of 23 is increased to a single rotation plug fixed arm system,
When removing the small rotating plug 30, the pantograph arm 23
The load on the vertical movement housing 25 and the gripper rotation / opening / closing drive shaft 26 increases by the increase in the length, and the load on the pantograph opening / closing shaft 27 and the pantograph opening / closing lever 33 also increases. Due to space problems of these members, the diameters of the pantograph opening / closing shaft 27 and the gripper rotation / opening / closing driving shaft 26 are limited by the inner diameter of the vertical movement housing 25. Moreover, there is a problem in that the supporting moment load increases due to the increase in the length of the pantograph arm 23, and the gripper rotation and the drive by the opening / closing drive shaft 26 and the pantograph opening / closing shaft 27 become impossible. Further, since the through hole 29 through which the gripper rotation and the opening / closing drive shaft 26 of the vertical movement housing 25 penetrate has both functions of sliding and sealing, there is a structural problem in increasing the load. As mentioned above, in order to miniaturize the reactor structure, it is indispensable to delete the small rotation plug 30 as described above, and the small rotation plug 30 is deleted to form a single rotation plug. There is a problem in that it is impossible structurally to make the length of the pantograph arm 23 longer by adopting the plug fixed arm system.

[Problems to be solved by the invention]

As described above, in the conventional structure, it is structurally impossible to remove the small rotating plug and use the single rotating plug fixed arm method as described above.The single rotating plug is moved horizontally in the diameter direction through the monorail. However, there was a problem in that it did not give consideration to this, and hindered the compactness of the reactor structure.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fast breeder reactor refueling device capable of eliminating the small rotary plug and downsizing the reactor structure.

[Means for solving problems]

 The above object can be achieved as follows.

A lifting motor fixed directly or indirectly to a rotating plug rotatably attached to the roof deck of a tank-type reactor, a lifting tube drive wire that is wound and unwound by the rotation of the lifting motor, and a lifting tube drive wire. The hoisting tube is connected to the lower end of the hoisting tube, and the hoisting and lowering of the hoisting tube drive wire raises and lowers the hoisting tube, the horizontally moving monorail horizontally supported at the lower end of the hoisting tube, the moving carriage that moves on the horizontally moving monorail, and moves. The trolley has an upper end fixed, and the lower end has an expandable tube with a gripper for holding the upper end of the fuel assembly attached. By moving the trolley, the moving carriage is set at a desired position above the core of the plug-type nuclear reactor, and a high-pressure machine equipped with a fuel exchanger that replaces the fuel assemblies in the core is installed. In breeder reactor refueling device,
It is fixed directly or indirectly to the hoisting pipe and is installed in parallel in the upward direction from the transmission shaft drive motor, which is the power source for the movement of the moving carriage and the expansion and contraction of the expansion and contraction pipe, to the horizontal movement monorail. The drive transmission shaft I and the drive transmission shaft II, each of which has a worm attached to the lower end thereof, and two shafts which are rotatable at both end portions of the shafts are loosely engaged with the bearings installed on the horizontally moving monorail. Consists of
A worm gear and a worm are formed in the main shaft portion other than both ends of the shaft. Of these, the worm gear is a horizontal driven shaft I that meshes with the worm of the drive transmission shaft I, and the drive transmission shaft.
A horizontal driven shaft II that meshes with the worm of II, a ball screw that is installed on the moving carriage and that meshes with the worm of the horizontal driven shaft I, and a telescopic tube that expands and contracts the expansion tube by engaging with the worm of the horizontal driven shaft II that is installed on the moving carriage. It has a worm gear for expansion and contraction, and the movement of the moving carriage is driven by the drive transmission shaft I.
And the drive transmission shaft II is simultaneously rotated, and the expansion and contraction of the expansion and contraction tube is equipped with a fuel exchanger that is rotated only by the drive transmission shaft II, and the fuel exchange device is made of a highly rigid structural material.

[Action]

In the present invention, when the transmission shaft drive motor starts shaft rotation,
One of the rotational forces of the transmission shaft drive motor is transmitted to the drive transmission shaft I via the gear device, and then the worm of the drive transmission shaft I and the worm gear of the horizontal driven shaft I are engaged with each other so that the horizontal driven shaft I Be transmitted to. When the horizontal driven shaft I rotates, the worm of the horizontal driven shaft I and the ball screw of the moving carriage are engaged with each other, whereby the rotational force of the horizontal driven shaft I is transmitted to the moving carriage and the moving carriage is moved. Moves on a horizontally moving monorail. Further, along with this, the expansion tube attached to the movable carriage also moves.

On the other hand, the other one of the rotational force of the transmission shaft drive motor is
It is transmitted to the drive transmission shaft II via the gear unit, and then transmitted to the horizontal driven shaft II by the engagement of the worm of the drive transmission shaft II and the worm gear of the horizontal coaxial shaft II. And in this case, the worm of the drive transmission shaft II and the horizontal driven shaft II
The ratio of the number of meshing teeth with the worm gear is the same as the ratio of the number of meshing teeth with the worm gear of the drive transmission shaft I and the worm of the horizontal driven shaft I described above.
And the horizontal driven shaft II have the same worms,
The horizontal driven shaft I and the horizontal driven shaft II rotate at the same rotation speed and the same screw transfer speed.

Further, the worm of the horizontal driven shaft II is attached to the moving carriage and meshes with the worm gear for telescopic tube expansion and contraction that expands and contracts the telescopic tube by its own rotation.

With such a configuration, the horizontal driven shaft II has the same rotational speed as the horizontal driven shaft I, even when the movable carriage and the expansion tube attached to the movable carriage move due to the rotation of the horizontal driven shaft I. Rotate at the same screw moving speed. Therefore, the meshing between the worm of the horizontal driven shaft II and the worm gear for expanding / contracting the expansion tube simply indicates the meshing state, and no rotational force is transmitted from the worm of the horizontal driven shaft II to the expansion / contraction worm gear. The worm gear for expanding / contracting the expansion / contraction tube moves together with the movable carriage without rotating. That is, the telescopic tube is set to a desired position above the core of the tank reactor by rotating the rotary plug, moving the hoist tube up and down, and moving the moving carriage on the horizontally moving monorail while the telescopic tube is not expanding and contracting. .

Next, in the state where the expansion tube is set as described above, the gear device that transmits one of the rotational forces of the transmission shaft drive motor to the drive transmission shaft I is removed, and the rotation force of the transmission shaft drive motor is removed. Only transmit to the horizontal driven shaft II. In this case, since the movable carriage remains stopped, the rotational force is transmitted from the worm of the horizontal driven shaft II to the worm gear for expanding and contracting the expansion tube. Therefore, it is possible to expand and contract the expandable tube and hold and transport the nuclear fuel assembly while the movable carriage is stopped. Further, since the fuel exchanger is made of a high-rigidity structural material, there is no problem in strength and the performance can be sufficiently exhibited.

〔Example〕

Hereinafter, using the fast breeder reactor refueling device of the present invention as an example,
The same parts as the conventional ones are indicated by the same reference numerals and will be described with reference to FIGS. 1 to 4. 1 is a vertical cross-sectional view, FIG. 2 is a vertical cross-sectional view showing a state in which the fuel exchange device of FIG. 1 is installed in a tank-type reactor, and FIG. 3 is an explanation of movement of a moving carriage of the fuel exchange device of FIG. Figure,
FIG. 4 is also an operation explanatory view. As described in the prior art, since the pantograph type fixed arm of FIG. 5 has a structure using a pipe material or a bar material, it is said that it does not have sufficient rigidity for use in a single-rotation plug in terms of structure and operation. For the reason, in this embodiment, the fixed arm is of a monorail type using a structural member having high rigidity such as H-section steel.
Therefore, since the gripper device 24 is configured to move the tip of the pantograph-type fixed arm, it is configured to move in the radial direction of the core on the monorail, so a small rotating plug is not required, and it is necessary for the pantograph-type fixed arm. The rotation function of the Atsuta arm itself is also unnecessary. The movement of the gripper on the core is performed by rotating the single rotation plug in the circumferential direction, and by the moving carriage mechanism in which the gripper device is installed on the monorail in the radial direction.

In the figure, 2 is a single-rotation plug, 3 is a drive transmission shaft, 4 is a horizontal moving monorail using a structural member having high rigidity such as H-shaped steel, 5 is a moving carriage, and 6 is an axial direction so that friction resistance is small. Linear bearing that is movably formed,
7 is a ball screw, 8 is a transmission shaft drive motor, 9 is a drive gear, 10a is a high-rigidity beam for maintaining horizontal movement monorail strength, 10b and 10c are horizontal driven shafts, 11 is a worm gear for expanding / contracting a telescopic tube, 12 is a telescopic tube, Reference numeral 13 is a gripper, and 14 is a gripper opening / closing motor. 15 is gripper drive wire, 16 is hoisting pipe, 17
Is a lifting tube drive wire, 18 is a lifting motor, and 22 is a core. A drive system for moving the refueling machine 1 is installed on the upper surface of the single rotation plug 2. The horizontally moving monorail 4 is supported by a hoisting pipe 16 and is suspended by a hoisting pipe drive wire 17. Then, the hoisting motor 18 drives the hoisting tube drive wire 17 to hoist the hoisting tube 16 and the horizontally moving monorail 4. The horizontally movable monorail 4 is provided with a movable carriage 5 that moves on the horizontally movable monorail 4, and the upper end of the expansion tube 12 is fixed to the movable carriage 5 to expand and contract the expansion tube 12. 11 is installed.

The horizontal moving monorail 4 is provided with a high-rigidity beam 10a for holding the strength of the horizontal moving monorail, a horizontal driven shaft 10b, and a horizontal driven shaft 10c, respectively. To help maintain the strength of the. Horizontal driven shaft 10b and horizontal driven shaft 10c
Both ends of the shaft are engaged with bearings installed on the horizontally moving monorail 4 so that they can freely rotate. In addition, one worm gear and one worm are formed in the shaft main part other than the shaft both ends of the horizontal driven shaft 10b, and the shaft main part other than the shaft both ends of the horizontal driven shaft 10c includes
Two worm gears and one worm are formed.

The worm gear on the horizontal driven shaft 10b is connected to the drive transmission shaft 3
The worm gear mounted on the lower end portion of a is meshed with the worm gear of the horizontal driven shaft 10b and the worm gear mounted on the moving carriage 5 moving on the horizontally moving monorail 4. In addition, the horizontal driven shaft 10
A linear bearing 6 which is loosely engaged with the shaft portion of b is attached to the movable carriage 5 so as to tightly connect the horizontal driven shaft 10b and the movable carriage 5. The two worm gears on the horizontal driven shaft 10b have different left and right twist directions of the teeth, and one of the two worm gears is a worm attached to the lower end of the drive transmission shaft 3b. The other one engages with the worm attached to the lower end of the drive transmission shaft 3c. That is, the drive transmission shaft
The worms of 3b and the drive transmission shaft 3c also have different left and right twist directions of the teeth, and when the drive motor 8 starts rotating,
Both the drive transmission shaft 3b and the drive transmission shaft 3c are configured to be able to transmit the rotational force in the same direction to the horizontal driven shaft 10c. That is,
Although two transmission shafts, a drive transmission shaft 3b and a drive transmission shaft 3c, are used for the rotation of the horizontal driven shaft 10c, the drive force is increased when the expansion tube 12 described later is contracted. ing. Further, the worm of the horizontal driven shaft 10c is engaged with the worm gear 11 for expanding and contracting the expansion tube, which is attached to the moving carriage 5 regardless of the driving of the moving carriage 5.

Next, the operation status of the fuel exchanger 1 having the above-described configuration will be described. In order to grip and transport the fuel assembly, it is necessary to move the telescopic tube for gripping and lifting the fuel assembly to above the target fuel assembly. Rotation of plug 2, lifting tube
It is carried out by raising and lowering 16 and moving the moving carriage 5 on the horizontal moving monorail 4. Of these, the rotation of the single-turn plug 2 and the raising / lowering of the hoisting pipe 16 are mechanically easy, and therefore the description thereof is omitted, and the movement of the moving carriage 5 on the horizontally moving monorail 4 in the present embodiment will be described.

In order to move the moving carriage 5 on the horizontally moving monorail 4, the drive motor 8 is rotated and the drive transmission shafts 3a to 3c are rotated via the drive gear 9. The rotational force of the drive transmission shafts 3a to 3c has the same meshing ratio, and the horizontal driven shafts are transmitted through the meshes of the respective worm and worm gears.
It is transmitted to 10b and the horizontal driven shaft 10c. Also, the horizontal driven shaft
The worms of 10c and the horizontal driven shaft 10b have the same shape. Therefore, the horizontal driven shaft 10c and the horizontal driven shaft 1
It rotates at the same rotation speed as 0b and at the same transition speed of the screw part.

Of these, when the horizontal driven shaft 10b rotates, the rotational force of the worm of the horizontal driven shaft 10b is transmitted to the ball screw 7 of the moving carriage 5, and the moving carriage 5 moves horizontally.
Will move up. On the other hand, the worm of the horizontal driven shaft 10c is in mesh with the worm gear 11 for expanding and contracting the expansion tube that is fixed to the moving carriage 5, but the screw part transition in the worm of the horizontal driven shaft 10c due to the rotation of the horizontal driven shaft 10c. Since the speed and the moving speed of the moving carriage 5 match, the moving speed of the threaded portion in the worm of the horizontal driven shaft 10c also matches the moving speed of the worm gear 11 for expanding and contracting the expansion tube fixed to the moving carriage 5. It will be.

From the above, the worm of the horizontal driven shaft 10c and the worm gear 11 for telescopic tube expansion and contraction are in mesh with each other, but since the rotational force is not transmitted from the worm of the horizontal driven shaft 10c to the worm gear 11 for telescopic tube expansion and contraction, The worm gear 11 for expanding and contracting the expansion tube does not rotate, and the movable carriage 5 moves while the expansion and contraction of the expansion tube 12 is stopped. That is, telescopic tube
While the expansion and contraction of 12 is stopped, the expansion tube 12 whose upper end is fixed to the moving carriage 5 is rotated by the single rotation plug 2,
By moving the hoisting pipe 16 up and down and moving the carriage 5 on the horizontally moving monorail 4, the hoisting pipe 16 is moved above the target nuclear fuel assembly.

Next, in order to grip the nuclear fuel assembly by the gripper 13 attached to the tip of the expansion tube 12, the expansion tube 12 is extended. At this time, the rotational force from the transmission shaft drive motor 8 to the drive transmission shaft 3a is increased. Is disengaged from the drive gear 9, which is interposed for transmitting the torque, so that the rotational force is not transmitted to the horizontal driven shaft 10b even if the drive gear 9 rotates, and the movable carriage 5 is stopped. Keep it. In such a state, by rotating only the horizontal driven shaft 10c, the rotational force of the horizontal driven shaft 10c is changed.
The worm and the worm gear 11 for expanding and contracting the expansion tube are transmitted to the worm gear 11 for expanding and contracting the expansion tube, and the worm gear 11 for expanding and contracting the expansion tube rotates to extend the expansion tube 12 to a desired position. After gripping the nuclear fuel assembly, the transportation of the fuel assembly for accommodating the nuclear fuel assembly in another place is carried out by the operation opposite to the above.

Although the expansion tube 12 is normally in a contracted state, it is extended from the moving carriage 5 like a car antenna at the time of nuclear fuel exchange and installed at the top end of the expansion tube 12 at the upper end of the nuclear fuel assembly 28 in the core 22. A gripper 13 is reachable. The gripper 13 has a “C” shape, is guided in the horizontally moving monorail 4 via the moving carriage 5, and is attached to the lower end of the telescopic tube 12 by a gripper drive wire 15
The gripper 13 is driven by a gripper opening / closing motor 14 to open and close the gripper 13, and the nuclear fuel assembly 28 is locked by the gripper 13 and the expansion tube 12 is contracted to lift it from the reactor core 22.

In FIG. 2, the single rotation plug 2 is arranged on a roof deck 21 installed on the upper part of the reactor vessel 20, and the single rotation plug 2 is configured to be freely rotatable on the roof deck 21. The horizontally moving monorail 4 is on the core 22, and the moving carriage 5 having the expansion tube 12 installed is the horizontal monorail 4
The upper part can be moved in the radial direction from the center of the core 22. Telescopic tube 12
Has a sufficient length to reach the core 22 from the moving carriage 5, and the refueling machine 1 is moved in the circumferential direction by the rotation of the single-turn plug 2.
Further, gripping of the upper end of the fuel assembly 28 by the gripper 13 is
Gripper drive wire driven by the gripper opening / closing motor 14
15 is guided through the horizontally moving monorail 4 and the moving carriage 5 and supported by the lower end of the expandable tube 12.

The refueling work will be described in detail with reference to FIGS. 3 and 4. FIG. 3 (A) shows a standby state of the fuel exchanger 1, and FIG. 3 (B) shows a state in which the moving carriage 5 is moving. In both cases, the expansion tube 12 is in a contracted state. There is no contact interference with. Then, the rotation of the single-turn plug 2 and the movement of the moving carriage 5 on the moving monorail 4 cause the core 22 to move.
The expandable tube 12 at an arbitrary position (c) above expands and contracts and moves to the nuclear fuel assembly attachment / detachment work position. In (c), the nuclear fuel assembly 28 inserted at an arbitrary position in the core 22 is
After the expansion tube 12 is extended and gripped by the gripper 13 at the tip, the expansion tube 12 is contracted to hang up the nuclear fuel assembly 28, and the moving carriage 5 is horizontally moved monorail 4 in this hung state.
The upper part is moved and the single rotation plug 2 is rotated. When mounting the nuclear fuel assembly 28, the procedure is the reverse of the above.
The gripper 13 is driven by a gripper opening / closing motor 14 with the gripper drive wire 15 being pulled out to a position where the telescopic tube 12 is extended as the movable carriage 5 moves. As described above, movement in the circumferential direction is performed by the single rotation plug 2 mounted on the roof deck 21, and the gripper 13 is provided on the horizontally moving monorail 4 of the fuel exchanger 1 supported by the single rotation plug 2 in the radial direction. Since the expandable tube 12 is configured to move and the fuel of the nuclear fuel assembly 28 can be exchanged, the rotating plug can be significantly downsized. That is, the small rotary plug of the double rotary plug having the conventional structure can be eliminated. Further, it is possible to obtain rigidity and operability of the gripper 13 supporting portion which cannot be realized by the conventional pantograph type.

As described above, in the fast breeder reactor fuel exchange system of the present embodiment, the fuel exchanger is attached to the single-rotation plug, moves in the circumferential direction by the rotation of the single-rotation plug, and is suspended and attached to the fuel exchange machine in the radial direction. It is configured to move a moving carriage with a telescopic tube equipped with a gripper that holds a nuclear fuel assembly on a horizontally moving monorail made of a highly rigid material. The structure can be made compact. Also,
The conventional pantograph system has high rigidity that cannot be obtained, and reliable operability can be obtained.

〔The invention's effect〕

As described above, the fast breeder reactor fuel exchange system of the present invention is
This has the effect of eliminating the small rotating plug and making the reactor structure compact.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view of an embodiment of a fast breeder reactor fuel exchange apparatus of the present invention, FIG. 2 is a vertical cross-sectional view showing a state in which the fuel exchange machine of FIG. 1 is installed in a tank reactor, and FIG. ), (B),
(C) is a movement explanatory view of the moving carriage of the fuel exchanger of FIG. 1, FIG. 4 (a) is an operation explanatory view of the same, (b) is a detailed view of part A of (a), and FIG. FIG. 6 is an explanatory view of a pantograph type fuel exchanger, and FIG. 6 is a plan view showing a state in which the fuel exchanger of FIG. 5 is attached to a nuclear reactor. 1 ... Refueling machine, 2 ... Single rotation plug, 4 ... Horizontal moving monorail, 5 ... Moving carriage, 7 ... Ball screw, 8 ... Conduction shaft drive motor, 10a ... Horizontal moving monorail Rigid beam, 10b, 10c ... Horizontal driven shaft, 11
...... Telescopic tube Telescopic worm gear, 12 ...... Telescopic tube, 13 ......
Gripper, 14 ... Gripper opening / closing motor, 15 ... Gripper drive motor, 21 ... Roof deck, 22 ... Core, 28 ...
Nuclear fuel assembly.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-49-46096 (JP, A) JP-A-61-161494 (JP, A) JP-A-58-186091 (JP, A)

Claims (1)

[Claims] 1. An up-and-down tube drive motor fixed directly or indirectly to a rotary plug rotatably attached to a roof deck of a tank-type nuclear reactor, and an up-and-down operation in which the up-and-down tube drive motor is wound and unwound by rotation of the up-and-down tube drive motor. Tube drive wire,
This hoisting tube drive wire is connected to the lower end of the hoisting tube drive wire, and the hoisting and lowering of the hoisting tube drive wire raises and lowers the tube, the horizontally moving monorail horizontally supported at the lower end of the hoisting tube, and the horizontally moving monorail. A moving carriage that has a telescopic tube having an upper end fixed to the moving carriage and a gripper attached to the upper end of the fuel assembly attached to the lower end of the moving carriage. A fuel exchanger that sets the moving carriage to a desired position above the core of the tank reactor by elevating and lowering and moving the moving carriage on the horizontally moving monorail, and exchanges a fuel assembly in the core. In a fast breeder reactor refueling device including: a power source for directly or indirectly fixed to the lifting pipe, for moving the moving carriage and expanding and contracting the expansion pipe. A transmission shaft drive motor, a transmission transmission shaft I and a drive transmission shaft II in which a worm is attached to the lower end of each of the transmission shaft drive motor and the horizontally moving monorail, which are installed in parallel in the vertical direction. Each of the bearings installed on the shaft is composed of two shafts, each of which is rotatable at both ends of the shaft, and a worm gear and a worm are formed on a main part of the shaft other than the both ends of the shaft. Of these, the worm gear is A horizontal driven shaft I that meshes with the worm of the drive transmission shaft I, and the drive transmission shaft II.
A horizontal driven shaft II that meshes with the worm, a ball screw that is installed on the movable carriage and meshes with the worm of the horizontal driven shaft I, and a telescopic tube that expands and contracts by meshing with the worm of the horizontal driven shaft II that is installed on the movable carriage. And a worm gear for expanding and contracting the expansion and contraction tube, wherein the movement of the movable carriage is performed by simultaneous rotation of the drive transmission shaft I and the drive transmission shaft II, and the expansion and contraction of the expansion pipe is performed through the drive transmission shaft.
A fast breeder reactor refueling apparatus comprising the refueling machine that is operated by rotating only II, and the refueling machine is made of a highly rigid structural material.