JPS58140691A - Fuel exchanging device of reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a refueling apparatus for a nuclear reactor such as a fast breeder reactor, which is designed to absorb thermal expansion that affects the opening and closing times of a pantograph with a gripper that grips fuel.

TECHNICAL BACKGROUND OF THE INVENTION In nuclear reactors such as fast breeder reactors, a pantograph type refueling device is used, one example of which is shown in FIGS. 1 and 2.

First, a rotary plug 1 is rotatably provided in the upper part of the reactor vessel, and a cylindrical rotary housing 2 is mounted therethrough, and is supported so that it can rotate in any direction and can also move up and down. The rotating housing 2 has a lift housing 3 inserted therethrough as necessary, and has the function of rotating the fuel exchange device and holding down the fuel around the fuel to be exchanged. The lifting housing 3 has a cylindrical shape, and is equipped with a pantograph 4 consisting of a link mechanism at its lower end, and a gripper mechanism 5 for gripping and releasing the fuel 19 at the tip of the arm. In addition, the upper end plate is connected with a drive unit 6 which has a built-in opening/closing mechanism for the pantograph 4 and gripper mechanism 5, a fuel position sensing mechanism, etc., and is rotatably supported by the cover 7 via a bearing 9. There is. The cover 7 is guided in a non-rotatable but movable manner via a guide roller 10 inside the cask casing 8, and is guided by an upper hoisting device 11.
is suspended by a wire rope ζ, whereby the lifting and lowering of both the lifting housing 3 and the lifting housing 3 is controlled.

The rotary housing 2 is mounted on a guide sleeve 12 that is fitted into the through hole 1aK of the rotary plug 1. A sleeve-shaped body 14 is installed above through a bearing 13, and the rotary housing 2 is mounted in the body 14. A turning mechanism 15 and a hold-down mechanism 16 are provided. Further, there is a door valve 17 at the upper end of the shell 14, which can be connected to a door valve 18 at the lower end of the cask casing 8.

When exchanging fuel, place the cask casing 8 containing the elevating housing 3 on the rotating housing.
Connect the door valves 17 and 18 and replace the inside of the cask casing 8 with an inert gas such as Ar gas.Then, lower and insert the elevating housing 3 into the rotating housing 2. be done. The lower end of the lifting housing 3 is introduced into the furnace and the pantograph 4 is opened. The gripper mechanism 5 is controlled by the composite Jζ of each rotation angle of the rotating plug l and the rotating housing 2, so that the required fuel 1 is
9 position, grab this fuel 19 and 1 hoisting device 11
It is pulled out from the core according to the hoisting number ζ. Next, replace the fuel with new fuel at the designated location, then return to the original position and insert the new fuel.

Open and release the claws of the gripper mechanism 5. After that, the pantograph 4 is folded in the opposite manner to the above, and the elevating housing 3 is pulled up and stored in the cask casing 8.

The door valves 17 and 18 are separated and moved to a predetermined position for maintenance and inspection.

The structural concept of the above-mentioned fuel exchange device using a pantograph mechanism is shown in the second drawing ζ. The folding link 42 of the intermediate part lζ of the arm 41 of the pantograph 4 is pivotally mounted and guided by the folding link 3 & provided in the elevating housing 3. It is connected to the opening/closing rod I via the elevator 43. The drive unit 6 includes a pantograph opening/closing mechanism 8, and a torque detector 47 provided on the output shaft of a reducer to which the drive motor 45J is directly connected. A bevel gear 49 is shaft-mounted via a gearbox mallet. The bevel gear 49 meshes with a bevel gear 51 mounted on the ball screw main body, and a ball nut 52 converts the rotation of the ball screw into linear motion. This pole nut 52
Connect the upper end of the opening/closing rod I to. The mark indicates a position detector that detects the open/close position.

Problems with the Background Art In the opening/closing control of the pantograph of the conventionally used fuel exchange device as described above, there is no particular problem in both 1-position cutting and load cutting when the pantograph is opened, but there is no problem in opening/closing the pantograph when the pantograph is closed. A first-order problem occurs when the load is cut.

That is, in the case of a fast breeder reactor, the temperature inside the reactor during fuel exchange is generally about 200°C, and if position cutting is performed with the same stroke as at room temperature, the IF folding link 42. Arm 41. Since the opening/closing rod I is thermally expanded, it is not folded sufficiently, and it becomes difficult to pass through the rotary housing 2 and pull it out of the furnace.

On the other hand, in the case of load cutting, if the arm 41 is completely folded and the load is detected by colliding with a part of the lifting housing 3, the folding itself is completely carried out regardless of the temperature number. , after being stored in the cask casing 8, when the arm 41, etc. that had been thermally expanded cools and contracts,
A large thermal shrinkage force is generated in the opening/closing rod 44 and the pantograph opening/closing mechanism 8, which may lead to damage and accidents. A possible method for preventing this is to slightly open the pantograph 4 after storing the cask casing 8.

In reality, it is not perfect because various interlock circuits are incorporated into the control circuit, and handling operations become complicated, which can lead to forgetting operations.

Purpose of the Invention The present invention has been made in view of the above-mentioned problems.
To provide a fuel exchange device for a fast breeder nuclear reactor, in which even if thermal contraction occurs due to a temperature drop, the shrinkage is absorbed by a spring, and large stress is not applied to an opening/closing rod or a pantograph opening/closing mechanism.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides one of the opening/closing rods.
Separate the upper and lower parts and connect them with the elastic part interposed. The retractable part is always reduced to the minimum length by a spring, and its retracting force is set to slightly exceed the weight of the pantograph. That is, the opening/closing rod acts as a single rod that does not extend when simply opening/closing the pantograph. After the pantograph is completely stored and the load is removed, when heat shrinks in each part due to cooling, the elastic part expands and absorbs the shrinkage. Therefore, the stress equivalent to the slight extension of the spring acts on a series of devices such as the opening/closing rod and the pantograph opening/closing mechanism to which it is connected.
Stress that would forcefully extend the opening/closing rod can be prevented.

On the other hand, the load of pulling out and carrying the fuel gripped by the gripper mechanism is applied to the opening/closing rod, and the spring force of the telescoping section cannot withstand this load. A stopper is provided on the elevating housing so as to receive the lower end of the elevating housing. Loads such as the weight of fuel are received by the stopper and do not act on the telescopic part. The spring storage force of the telescopic part can be set to the minimum.

Stress during heat shrinkage can also be minimized.

The stopper is adjustable in vertical position so that the pantograph can be opened to the optimum position.

Furthermore, a disc spring is interposed between the telescopic lower end and the stopper or between the telescopic part and the end of the opening/closing rod, so that when the telescopic part descends together with the opening/closing rod and comes into contact with the stopper, the entire load is received by the stopper. Alleviate the impact that will occur.

Examples of the invention An embodiment of the present invention will be described below with reference to the drawings.

Figure 3 shows the main parts. The structure 1 mechanism and operation of other parts for fuel exchange are the same as those shown in FIGS. 1 and 2, so the same reference numerals are given and explanation thereof will be omitted.

Cut off the lower part of the opening/closing rod I to make a lower rod 44m,
A swollen portion 44b is provided at the separated end.

Attach the restriction plate 8 slightly upward. The lower end of the spring case is connected to the upper end of the lower rod 44m. The top of this spring case is open.

An open-ended inner flange portion 561 is provided. Insert the lower end of the above opening/closing rod shrine into the spring case audience,
The telescopic spring 5 is connected to the inner flange portion 56m and the enlarged portion 44.
Load the bullet between b. The elasticity of this telescopic spring reduces the relative position of the opening/closing rod 44m and the lower rod 44m, and the upper end of the spring case and the limiting plate contact and contract to the minimum. At this time, the stored force of the spring 5 is set to exceed the weight of the pantograph 4. In this way, the opening/closing rod and the lower rod 44m are integrally connected.

When the pantograph 4 is opened and closed, this spring case lowers and rises together with the opening/closing rod 44 (44a), but when the pantograph 4 is in the fully open position, a stopper is attached to the elevating housing 3, which comes into contact with the lower end of the spring case. A disc spring 57 is interposed on the top surface of the stopper strip. Further, the stopper blade is attached with a screw 59 and a lock nut 59m so that its upper position can be adjusted.

With the above structure, we will describe the missing number ζ action.

When the pantograph is opened, the drive motor is rotated to lower the opening/closing rod I, the lower part of the spring case contacts the stopper, and the torque detector 47 of the opening/closing mechanism performs load cutting. In this case, the disc spring 57 acts as a buffer and the load can be cut off without any shocking increase in load. When replacing fuel in this state, a load of several tons is applied to the lower rod 44m to extract the fuel, but the lower end of the spring case is supported on the stopper brocade and bears this load, causing the spring 55 to be affected. There isn't.

When the fuel is inserted in the reverse direction, a force is applied from below to the lower rod 44a, but the upper end of the spring case abuts against the restriction plate 8 and bears the load.

Therefore, the telescopic spring 5 does not need to bear the force of inserting and extracting fuel, and only needs to store enough strength to withstand the weight of the pantograph, so it can be constructed with a relatively compact spring case.

Next, when folding the pantograph, the opening/closing rod 44 (44 m) is raised by the reverse rotation of the drive motor 45, and the pantograph 4 is folded and the elevating housing 3
It is completely housed in the area and comes into contact with a part of it.

Since the load increases here, this is detected by the torque detector 47 between the opening and closing mechanisms, and the load is cut off. In this case as well, the spring i provides a buffer, and there is no shocking increase in load. Furthermore, in this case, reliability can be improved if the position detector ω is used in conjunction with the control.

After folding, the lifting housing 3 is stored in the cask casing 8, where the arms 41. Folding link 42. Even if the opening/closing rod I etc. cool down and contract, all of the contraction is absorbed by compressing the elastic spring 55, so that excessive thermal contraction force is not applied to the pantograph opening/closing mechanism &, the opening/closing rod I, etc. do not have.

Effects of the Invention As described above, the nuclear reactor fuel exchange device according to the present invention has a telescopic section in the middle of the opening/closing rod that opens and closes the pantograph, which is normally compressed by the accumulated force on the blade necessary to open and close the pantograph. is inserted, and a stopper is provided to catch the lower end of this telescoping section when the pantograph is fully open, allowing it to cope with heat contraction and fuel withdrawal/insertion without increasing the spring force of the telescoping section, regardless of temperature conditions. It is possible to completely store the pantograph in the lifting housing by cutting the load without any load, and there is no need to open the pantograph slightly after storing it in the cask casing, making it easy to handle, highly reliable, and compact equipment. .

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view showing the conventional structure of a fuel exchange device for a fast breeder reactor, Fig. 2 is a conceptual diagram of the configuration of a pantograph opening/closing mechanism, and Fig. 3 is a schematic diagram showing an embodiment of the fuel exchange device of the present invention. FIG. l... Rotating plug, 2... Rotating housing, 3...
- Lifting housing, 4... Pantograph, 5... Gripper mechanism, 6... Drive unit, 8... Cask casing, 11... Hoisting device, 17, 18... Door valve, 41... arm. 42...Folding link, 43...Elevator, 44...
・Opening/closing rondo. 47...torque detector, 53...pantograph opening/closing mechanism. 8... Limiting plate, 55... Spring, 56... Spring case, 57... Belleville spring, 58... Stopper. Original representative Kiyoshi Inomata J 2 M Tsumugi 3 figures

Claims (1)

[Scope of Claims] 1. A rotary housing rotatably mounted on a rotary plug provided at the upper part of the reactor vessel, an elevating housing that moves up and down within this housing, a pantograph with a gripper equipped with the lower part of the elevating housing, Installed at the top of the lifting housing,
A gripper and a drive section that accommodates the opening/closing mechanism of the pantograph are interposed in a part of the opening/closing rod that connects the pantograph and the pantograph opening/closing mechanism, and a telescoping section that is contracted by a predetermined spring force is inserted. 1. A refueling device for a nuclear reactor, characterized in that an adjustable stopper is installed in an elevating housing to catch the lower end of an extendable part that descends with an opening/closing ring during an opening operation. 2. The fuel exchange device for a fast breeder nuclear reactor as set forth in claim 1, characterized in that a cushion disc spring is interposed between the extendable part and the stopper or between the opening/closing rod and the extendable part. .