JPH08110391A - Refueling machine gripper for fast reactor - Google Patents

Abstract

PURPOSE: To reduce dynamic load during earthquake and lighten, simplify and improve in maintainability. CONSTITUTION: On a ball screw 12 provided in a holddown tube l0, a ball nut 14 is screwed in. The ball nut 14 is provided on an upper gripper cylinder 22 and a lower gripper cylinder 23 is coupled in the lower end of the cylinder 22. A sodium damper 26 is placed in the coupling part. Inside the cylinder 22, a tension spring 24 of which lower part is fixed to the upper side of the cylinder 23, is provided. A nail open/close rod 20 penetrating through the cylinder 22 and the cylinder 23 is provided. At the lower part of the nail open/close rod 20 and lower part of the cylinder 23, a gripper nail 15 for grasping a fuel assembly is provided. A nail open/close screw 19 provided at the upper part of the rod 2O is connected with screw to a gear with screw 18. The gear 18 is rotated with a spline 13 to move the rod up and down.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gripper for a refueling machine of a fast reactor for transporting and exchanging fuel assemblies under the liquid level of liquid metal sodium used in a liquid metal sodium cooled fast reactor.

[0002]

2. Description of the Related Art Fuel exchange in a reactor vessel of a liquid metal sodium cooled fast reactor is carried out by a fuel exchanger installed so as to penetrate a wall of the reactor vessel. The outline of this fuel exchanger will be described with reference to FIG.

That is, in FIG. 7, a reactor vessel 1 of a fast reactor is loaded with a large number of fuel assemblies 2 and contains a sodium coolant 3 therein. An upper lid 4 is installed on the upper part of the reactor vessel 1, and a fuel exchanger 6 is installed so as to reach the top of the fuel assembly 2 from an opening 5 provided in the upper lid 4.

The refueling machine 6 includes a drive unit 7 on the upper lid 4, a main body barrel 8 in the reactor vessel 1, a pantograph mechanism 9, a holddown tube 10 attached to the tip of the pantograph mechanism 9, and this holddown tube 10. A gripper mechanism 21 that is housed inside and that holds and separates the fuel assembly 2.
And a gripper drive shaft 29 that drives the gripper mechanism 21.

As described above, the refueling machine 6 includes a rotatable main body cylinder for refueling, an expandable telescopic variable arm pantograph mechanism 9 extending from the main body cylinder 8, and a gripper mechanism 21 at the tip of the pantograph mechanism 9. It has a holddown tube 10 with a built-in.

There is also a system in which the variable arm type pantograph mechanism 9 which can be expanded and contracted has a constant arm length and the vertical angle of the fixed arm length is combined with the vertical movement of the main body cylinder. Since it is common to all, the fuel exchanger having the variable arm type pantograph mechanism 9 which can be expanded and contracted will be described below.

[0007]

The core of a nuclear reactor is large along with the increase in power, and the thickness of the fuel assembly 2 and its fuel pin is also increasing. Along with this, the arm of the pantograph mechanism 9 has become longer, and the gripper mechanism 21 and the hold-down tube 10 attached to the tip of the arm have also become larger and have increased weight.

As described above, in order to withstand an earthquake load in the state where the fuel assembly 2 is housed in the holddown tube 10 at the tip of the long arm, the long variable arm mechanism which can be expanded and contracted has an excessive structure.

Therefore, in the fuel exchanger of the pantograph mechanism of the long variable arm type, a large force is applied to the base portion of the variable arm against a vertical earthquake at the time of handling the fuel, and there is a structural problem.

The present invention has been made in order to solve the above-mentioned problems, and a hold-down tube or a gripper mechanism is provided with a dynamic vibration absorbing function against a vertical motion earthquake to reduce the vertical motion load at the time of an earthquake, thereby reducing the weight. Another object of the present invention is to provide a gripper for a refueling machine of a fast reactor having a variable arm mechanism which is simplified and ensures maintainability.

[0011]

SUMMARY OF THE INVENTION The present invention is a gripper for a fast reactor refueling machine using a liquid metal coolant, in which a gripper body for attaching and detaching a fuel assembly is divided into an upper gripper cylinder and a lower gripper cylinder, The gripper cylinder is provided with a tension spring, the lower gripper cylinder is supported by the lower part of the upper gripper cylinder, and a coolant damper is provided at an engaging portion of the upper and lower gripper cylinders.

Further, according to the present invention, a flange is provided at an upper end of the lower gripper cylinder, and the lower gripper cylinder is supported by being mounted on a spring provided in the upper gripper cylinder, and the spring is provided on the upper and lower gripper cylinders. It is characterized in that it is built in a damper provided in the engaging portion of.

[0013]

[Function] A dynamic vibration absorbing function combining a spring and a damper is provided in the gripper. Liquid metal sodium as a coolant is used as the damper, and the fuel assembly being handled is used as the mass of the dynamic vibration absorbing function. The above-mentioned dynamic vibration absorption function delays the vertical movement of the fuel assembly with respect to the holddown tube portion that moves in response to vertical vibration, and reduces the vertical movement of the holddown tube portion by making it move in a phase opposite to that of the holddown tube. .

According to this, it is possible to solve the problem of structural countermeasures that a large force is applied to the base of the variable arm in response to vertical earthquake motion during fuel handling, and to simplify the variable arm. it can. A dynamic vibration absorber can be installed on the upper part of the holddown tube, and a magnetic damper can be used as the damper.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a gripper for a fuel exchanger of a fast reactor according to the present invention will be described with reference to the drawings. FIG. 1 is an assembly diagram for explaining a first embodiment of a gripper for a fast reactor refueling machine according to the present invention and a sixth embodiment described later.

In FIG. 1, a hole screw 12 for raising and lowering a gripper 11 and two opening and closing splines 13 of a gripper claw 15 for gripping and releasing the fuel assembly 2 are vertically installed in a holddown tube 10. ing. A ball nut 14 attached to the upper flange 22a of the upper gripper cylinder 22 is screwed into the ball screw 12.

The opening / closing mechanism of the gripper claw 15 includes a spline 13 for transmitting the rotational force from the outside of the reactor, a spline nut gear 16, a spur gear 17, and a screw gear 18 for transmitting the rotational force of the spline 13 to the gripper 15 side. It is composed of a claw open / close screw 19 for transmitting the rotational force in the axial direction, a claw open / close rod 20 and a gripper claw 15 for opening / closing the gripper claw 15 by this axial force.

The gripper 11 includes an upper gripper cylinder 22 provided with a ball nut 14, a lower gripper cylinder 23 incorporating a gripper claw 15 for gripping the fuel assembly 2, and an upper gripper cylinder.
22 and a tension spring 24 provided at an engaging portion between the lower gripper cylinder 23. A sodium damper 26 is formed in the inside 25 of the upper gripper cylinder 22 incorporating the tension spring 24 and the engaging portion between the upper gripper cylinder 22 and the lower gripper cylinder 23.

That is, the upper flange of the lower gripper cylinder 23
23a and the lower flange 22b of the upper gripper cylinder 22 are engaged with each other, and the engaging portion forms a void to allow sodium in the reactor to enter and form a sodium damper 26.

The tension spring 24, which supports the lower gripper cylinder 23 and is provided on the upper flange 23a of the lower gripper cylinder 23, exerts a spring force that causes a slight extension when the fuel assembly 2 of several hundred kg is suspended. Have

Next, an operation example of the first embodiment will be described. The gripper 11 is moved up and down by transmitting the rotational drive from outside the nuclear reactor to the ball screw 12, the rotational force of the ball screw 12 is transmitted to the ball nut 14, and the ball nut 14 is moved up and down, and the gripper 11 is held accordingly. Move up and down in the down tube 10.

The gripper claws 15 of the gripper 11 are opened and closed by rotating the spline 13 installed on the lateral side of the ball screw 12 from the outside of the nuclear reactor so that the spline 13, the spline nut-equipped gear 16 and the spur gear 17 are rotated in this order. To transmit the rotational force,
When the claw opening / closing screw 19 in the gripper 11 rotates via the threaded gear 19, the claw opening / closing rod 20 moves up and down to open / close the gripper claw 15.

When gripping the fuel, the weight of the fuel assembly 2 is transferred to the upper gripper cylinder 22 via the gripper claw 15 attached to the lower gripper 23, the tension spring 24 connecting the upper gripper cylinder 22 and the lower gripper cylinder 23. And the load is transmitted, and finally,
It is transmitted from the ball screw 12 to the holddown tube 10.

Next, the operation and effect of the gripper having the dynamic vibration absorbing mechanism of the combination of the tension spring 24 and the sodium damper 26 according to the first embodiment will be described. In the normal handling of the fuel assembly 2 by the gripper 11, the own weight of the fuel assembly 2 is supported by the spring force of the tension spring 24 between the upper gripper cylinder 22 and the lower gripper cylinder 23. In the event of an earthquake, the movement of this tension spring 24 and the upper gripper cylinder 22 and the lower gripper cylinder
A dynamic vibration absorbing mechanism that uses a sodium damper 26 provided between 23 and the held fuel assembly 2 as an inertial mass body to move the holddown tube in a phase opposite to the vertical vibration. A mechanism is provided.

Therefore, the maximum bending moment applied to the base of the pantograph mechanism at the time of a vertical earthquake can be greatly reduced, whereby the gripper 11, the pantograph mechanism (reference numeral 9 in FIG. 7) and the main body (FIG. 7). The force acting on the code 8) in 7 can be greatly reduced,
This makes it possible to downsize the fuel exchanger and downsize the reactor structure.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is a gripper having therein a dynamic vibration absorbing mechanism that is a combination of a compression spring and a damper. In FIG. 2, a ball screw 12 for moving the gripper 11 up and down in the holddown tube 10 and a gripper claw opening / closing spline 13 for gripping and releasing the fuel assembly 2.
Are installed vertically. A ball nut 14 is attached to a portion of the gripper 11 through which the ball screw 12 penetrates.

The gripper claw opening / closing mechanism includes a spline 13 for transmitting a rotational force from the outside of the reactor and a gripper claw for transmitting this rotational force.
The gear 16 with spline nut, the spur gear 17, and the gear 18 with screw, which are transmitted to the 15 side, the pawl open / close screw 19 for transmitting the rotational force of these gears in the axial direction, and the gripper pawl 15 by this axial force.
Claw open / close rod 20 and gripper claw 15 for opening and closing
It consists of and.

Next, the structure of the dynamic vibration absorbing mechanism incorporated in the gripper 11 will be described. The gripper cylinder in the gripper 11 is an upper gripper cylinder with a ball nut 14.
22 and a lower gripper cylinder 23 incorporating a gripper claw 15 for gripping the fuel assembly 2.

Lower gripper tube incorporating the gripper claw 15
The ends of 23 and the upper gripper cylinder 22 are made to protrude in a disk shape by an upper flange 23a and a lower flange 22b.
Sodium damper 26 is formed between the protrusions,
A compression spring 27 is incorporated in the sodium damper 26 to vertically engage the upper and lower gripper cylinders 22 and 23.

That is, a sodium damper 26 is provided at the engaging portion of the upper gripper cylinder 22 and the lower gripper cylinder 23 incorporating the compression spring 27 and at the upper end of the upper gripper cylinder 22. In addition, the compression spring 27 supporting the lower gripper tube 23
Has a spring force that causes a slight extension when the fuel assembly 2 of several hundred kg is suspended.

Next, the operation of the second embodiment will be described. The lifting and lowering operations of the gripper 11 and the gripper claw opening / closing operations are the same as those of a gripper mechanism having a dynamic vibration absorbing mechanism in which a combination of a tension spring and a damper is provided, and a description thereof will be omitted.

That is, when gripping the fuel, the weight of the fuel assembly 2 is determined by the gripper claw 1 attached to the lower gripper cylinder 23.
5, the load is transmitted to the upper gripper cylinder 22 via the compression spring 27 provided between the lower flange 22b of the upper gripper cylinder 22 and the upper flange 23a of the lower gripper cylinder 23, and finally,
It is transmitted from the ball screw 12 to the holddown tube 10.

Next, a compression spring is internally provided according to the second embodiment.
The action and effect of the gripper provided with the dynamic vibration absorbing mechanism of the combination of 27 and the sodium damper 26 will be described. In the gripper 11 of this embodiment, when the fuel assembly 2 is normally handled, the self-weight of the fuel assembly 2 is supported by the spring force of the compression spring 27 between the upper gripper cylinder 22 and the lower gripper cylinder 23.

During an earthquake, the hold-down tube is moved by the movement of the compression spring 27 and the dynamic vibration absorption mechanism of the sodium damper 26 provided between the upper gripper cylinder 22 and the lower gripper cylinder 23.
Since the dynamic vibration absorbing mechanism is designed to move in the opposite phase with respect to the 10 vertical vibrations, the maximum bending moment at the base of the pantograph mechanism during a vertical earthquake can be significantly reduced. it can.

As a result, the gripper 11, the pantograph mechanism (reference numeral 9 in FIG. 7) and the body cylinder (reference numeral 8 in FIG. 7).
The force acting on can be significantly reduced, which enables downsizing of the fuel exchanger and downsizing of the reactor structure.

When the fuel assembly 2 is normally handled, the self-weight of the fuel assembly 2 is supported by the spring force of the compression spring 27 between the holddown tube 10 and the inner cylinder 28. 27 movements and holddown tube 10
By the dynamic vibration absorbing mechanism of the sodium damper 28 provided at the upper end,
Since it is a dynamic vibration absorbing mechanism that makes the holddown tube 10 move in the opposite phase with respect to the vertical vibration, the maximum bending moment at the base of the pantograph mechanism can be significantly reduced during an earthquake. it can.

Next, referring to FIGS. 3 and 4, the third embodiment of the present invention will be described.
An example will be described. Note that FIG. 4 is a transverse cross-sectional view taken along the line AA in FIG. This third
In the above example, the upper gripper tube is obtained by dividing the gripper into upper and lower parts.
A gripper is provided with a damping mechanism by a magnetic damper by disposing a magnet 35 and a conductor plate 36 in the lower gripper cylinder 23 and the lower gripper cylinder 23 so as to face each other.

In the first and second embodiments, the relative displacement of the upper and lower gripper cylinders 22 and 23 divided into the upper and lower parts of the gripper 11 causes the contained liquid sodium to flow in and out to generate flow resistance, that is, sodium. damper
26 is the damping mechanism. However, in the third embodiment, the magnet 35 and the conductor plate 36 are attached to the upper and lower gripper cylinders 22 and 23 of the gripper to form a damping mechanism.

As shown in FIG. 4, a pair of magnets 35 are adjacently fixed to the lower portion of the upper gripper cylinder 22 with a gap so as to have mutually different magnetic poles. Lower gripper tube
A conductor plate 36 is fixed to the upper part of 23, and the conductor plate 36 is inserted into a gap between a pair of magnets 35 facing each other.

Therefore, when relative motion occurs in the upper and lower split members of the gripper connected by the tension spring 24, the magnetic flux applied from the magnet 35 to the conductor plate 36 changes due to the relative motion of the pair of magnets 35 and conductor plate 36. Then, a magnetic damping force is generated by the eddy current loss generated in the conductor plate 36.

In this embodiment, magnetic dampers consisting of a pair of magnets 35 and a conductor plate 36 are installed at four places with a 90 ° gap.
You may arrange | position continuously in a place or the circumferential direction. Also,
The magnet 35 may be arranged on the lower side of the gripper and the conductor plate 36 may be arranged on the upper side of the gripper, and the magnet 35 may be not only a permanent magnet but also an electromagnet.

In this embodiment, the coil spring is used as the spring member, but other spring members such as a leaf spring may be used. Further, by covering the magnet 35 and the conductor plate 36 with a covering material, deterioration of the material and friction of the sliding portion can be reduced.

Next, the upper and lower gripper cylinders 22 of the gripper 11,
The effect of the gripper mechanism having the damping mechanism by the magnetic damper will be described by disposing the magnet 35 and the conductor plate 36 in 23 respectively so as to face each other.

The upper and lower grippers 22 and 23 of the gripper are connected by a tension spring 24, and the relative motion of the upper and lower gripper cylinders 22 and 23 can be damped by a magnetic damper. Therefore, the fuel assembly grasped by the gripper claws 15 can be absorbed. A dynamic vibration absorber can be constructed by adjusting the spring constant of the spring 24 and the damping constant of the magnetic damper using 2 as an inertial mass body.
Further, since the magnetic damper is used as the damping mechanism, a velocity-proportional damping force is obtained, and the vibration design is easy.

Therefore, the third embodiment can reduce the response of the vibration mode having a vibration component especially in the vertical direction at the time of an earthquake, as in the first and second embodiments. For this reason, the force acting on the gripper, the pantograph mechanism, and the main body cylinder, which has been subjected to a large dynamic load due to the vertical seismic force, can be significantly reduced. This makes it possible to downsize the fuel exchanger and downsize the reactor structure.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is an inner cylinder 28 having a dynamic vibration absorbing mechanism.
In the hold-down tube 10. FIG. 5 shows a holddown tube portion for a fuel exchanger of a fast breeder reactor in a gripper which is a target of this embodiment.

In FIG. 6, an inner cylinder 28 is incorporated in the hold-down tube 10, and a ball screw 12 for raising and lowering the gripper 11 and a gripper claw opening / closing for gripping and separating the fuel assembly 2 are opened and closed. Spline for 13
Are installed vertically. The structure of the gripper 11 is the same as that of the gripper mechanism including the dynamic vibration absorbing mechanism of the combination of the tension spring and the damper described in the first to third embodiments, and therefore the description thereof will be omitted.

Next, the hold down tube 10 and the inner cylinder 28
The structure of the dynamic vibration absorbing mechanism incorporated between them will be described. The ball screw 12 that raises and lowers the gripper 11 and the spline 13 that opens and closes the gripper claw 15 are supported by an inner cylinder 28 in the holddown tube 10 at the top and bottom by bearings 32, and the upper end of the inner cylinder 28 protrudes. Has a curved shape,
This part and the stepped part at the top of the holddown tube 10
A compression spring 30 is incorporated between 33.

A sodium damper 31 also serves as a space between the hold-down tube 10 incorporating the compression spring 30 and the inner cylinder 28. In addition, hold down tube
The compression spring 30 provided between the inner cylinder 28 and the inner cylinder 28 has a spring force that causes a slight extension when the fuel assembly 2 of several hundred kg is suspended.

Next, the operation of the fourth embodiment will be described. The lifting and lowering operations of the gripper 11 and the gripper claw opening / closing operations are the same as those of a gripper mechanism having a dynamic vibration absorbing mechanism in which a combination of a tension spring and a damper is provided, and a description thereof will be omitted. That is, when the fuel assembly 2 is gripped, the weight of the fuel assembly 2 is transmitted to the gripper claw 15, the gripper 11, the ball screw 12, and the compression spring 30 between the holddown tube 10 and the inner cylinder 28.

During normal handling of the fuel assembly 2, the weight of the fuel assembly 2 is determined by the weight of the holddown tube 10 and the inner cylinder 28.
It is supported by the spring force of the compression spring 30 between, but during an earthquake, the movement of this compression spring 30 and the hold-down tube 10
Since the dynamic vibration absorption mechanism of the sodium damper 31 provided at the upper end of the vertical movement of the hold-down tube 10 causes the movement of the phase opposite to the vertical vibration of the hold-down tube 10, the vertical direction added to the base of the pantograph mechanism. The maximum bending moment at the time of earthquake can be greatly reduced.

Next, the operation and effect of the fuel exchanger in which the inner cylinder having the dynamic vibration absorbing mechanism according to the present invention is incorporated in the holddown tube will be described. When the fuel assembly 2 is normally handled by the gripper 11, the self-weight of the fuel assembly 2 is supported by the spring force of the compression spring 30 between the holddown tube 10 and the inner cylinder 28.

In the event of an earthquake, the compression spring 30 moves, and the sodium damper 31 provided between the holddown tube 10 and the inner cylinder 28 has a dynamic vibration absorption mechanism, so that the holddown tube moves in a phase opposite to the vertical vibration. A dynamic vibration absorbing mechanism is provided.

Therefore, the maximum bending moment applied to the root of the pantograph mechanism during an earthquake in the vertical direction can be greatly reduced. As a result, the force acting on the gripper 11, the pantograph mechanism, and the main body cylinder (FIGS. 7 and 8) can be significantly reduced, which enables downsizing of the fuel exchanger and downsizing of the reactor structure.

Next, a fifth embodiment of the present invention will be described with reference to FIG. In the fifth embodiment, a dynamic vibration absorbing mechanism of a combination of a tension spring 24 and a sodium damper 26 is provided inside, and a gripper mechanism of a structure in which a tip portion swings is provided inside a dynamic vibration absorbing mechanism of a combination of a tension spring and a damper. 6 with a gripper equipped with
[Fig. 3] is an assembly diagram of a gripper mechanism for a fuel exchanger of a fast breeder reactor according to this embodiment.

In FIG. 6, a ball screw 12 for raising and lowering the gripper 11 and two gripper claw opening and closing splines 13 for gripping and releasing the fuel assembly 2 are vertically installed in the holddown tube 10. . At the part where the ball screw 12 of the gripper 11 penetrates, a ball nut 14
Is attached.

The gripper claw opening / closing mechanism includes a spline 13 for transmitting a rotational force from the outside of the reactor, and a gripper claw 15 for transmitting this rotational force.
Claw open / close screw that transmits the rotational force of the spline nut-equipped gear 16, spur gear 17, and threaded gear 18 to the axial direction
19. The gripper claw 15 is composed of a claw opening / closing rod 20 for opening and closing the gripper claw 15 by this axial force.

When the fuel assembly 2 is gripped by the gripper claws 15, the gripper claws 15 are pressed against the upper end of the gripper claws 15 by the safety ring 38 pressed by the internal sensing rod pressing spring 40. . A sensing rod 37 is attached to the safety ring 38 so that the gripper claw 15 can be closed only when the fuel assembly 2 reaches the loading completion position.

Further, between the gripper 11 and the fuel assembly 2,
Since the movement is restricted in the horizontal direction because it is pressed down by the sensing rod 37, and an excessive force acts on the gripper 11 in the event of an earthquake, the gripper 11 has a vertically divided structure and a spherical joint 39 is provided in the middle.

Next, the structure of the dynamic vibration absorbing mechanism incorporated in the gripper 11 will be described. The gripper cylinder in the gripper 11 includes an upper gripper cylinder 22 having a ball nut 14 and a lower gripper cylinder 23 incorporating a gripper claw 15 for gripping the fuel assembly 2, and the ends of the upper gripper cylinder 22 have upper flanges 23a thereof. , 23b so as to project inwardly and outwardly in a disk shape, and a tension spring 24 is incorporated in the upper part of the projecting portion and is connected in the vertical direction.

The engaging portion between the upper gripper cylinder 22 and the lower gripper cylinder 23 incorporating the tension spring 24, that is, the sodium damper 26 between the upper flange 23a of the lower gripper cylinder 23 and the lower flange 22b of the upper gripper cylinder 22. Is provided. Further, the tension spring 24 supported by the upper end of the lower gripper cylinder 23 has a spring force that causes a slight extension when the fuel assembly 2 of several hundred kg is suspended.

Next, the operation of the fifth embodiment will be described. The lifting and lowering operations of the gripper 11 and the gripper claw opening / closing operations are the same as those of a gripper mechanism having a dynamic vibration absorbing mechanism in which a combination of a tension spring and a damper is provided, and a description thereof will be omitted.

When the fuel assembly 2 is gripped, the upper end of the gripper claw 15 is closed by the opening operation of the gripper claw 15. Therefore, the safety ring 38 is pressed against this part by the sensing rod pressing spring 40, and the upper end of the gripper claw 15 is pressed. The covering and gripper claw 15 cannot be closed by the claw opening / closing driving force.

The closing operation of the gripper claw 15 is such that the safety ring 38 is pushed up only when the sensing rod 37 reaches the top of the fuel assembly 2, so that the gripper claw 15 is closed from the fuel assembly 2. It becomes possible.

The weight of the fuel assembly 2 is transferred to the upper gripper cylinder 22 via the gripper claw 15 attached to the lower gripper cylinder 23, the tension spring 24 connecting the upper gripper cylinder 22 and the lower gripper cylinder 23. And the load is transmitted, and finally,
It is transmitted from the ball screw 12 to the holddown tube 10. During normal handling of the fuel assembly 2, the self-weight of the fuel assembly 2 is supported by the spring force of the tension spring 24 between the upper gripper cylinder 22 and the lower gripper cylinder 23.

During an earthquake, the hold down tube 10 is moved by the movement of the tension spring 24 and the dynamic vibration absorbing mechanism of the sodium damper 26 provided between the upper gripper cylinder 22 and the lower gripper cylinder 23.
Since it is a dynamic vibration absorbing mechanism that moves in the opposite phase with respect to the vertical vibration of, the maximum bending moment applied to the root of the pantograph mechanism during a vertical earthquake can be greatly reduced.

Next, the function and effect of the fifth embodiment will be described. When the fuel assembly 2 is normally handled by the gripper 11, the self-weight of the fuel assembly 2 is supported by the spring force of the tension spring 24 between the upper gripper cylinder 22 and the lower gripper cylinder 23. The gripper 11 and the fuel assembly 2 are pressed by the sensing rod 37, but the load applied to the gripper with respect to the horizontal movement at the time of an earthquake is relieved significantly by the rotatable joint 39.

Further, by allowing the joint 39 to freely move in the horizontal direction, the vertical movement is simplified, and the function of the dynamic vibration absorbing mechanism of this embodiment which is effective for the vertical movement is hindered. I can't.

As a result, the maximum bending moment during an earthquake can be greatly reduced, and the forces acting on the gripper 11, the pantograph mechanism (reference numeral 9 in FIG. 7) and the main body cylinder (reference numeral 8 in FIG. 7) are significantly reduced. The size of the refueling machine and the reactor structure can be reduced.

Further, since the gripper claw cannot be closed in the normal gripping state, there is no risk of fuel falling due to the gripper claw closing during fuel handling, and the reliability of the fuel exchanger is greatly improved.

Next, a sixth embodiment of the present invention will be described with reference to FIG. In the sixth embodiment, the damper of the dynamic vibration absorbing mechanism has a gas vent hole. The mechanism of the gripper of this embodiment is essentially a gas vent hole 34 in the upper part of the upper gripper tube 22.
The description is the same as that of the gripper provided with the dynamic vibration absorbing mechanism of the combination of the tension spring 24 and the sodium damper 26 in the first embodiment except that the above is provided. The difference from the first embodiment is that a gas vent hole 34 is provided in the upper flange 22a of the upper gripper cylinder 22.

Next, the operation of the sixth embodiment will be described. The lower part of the main body 8 of the fuel exchanger loaded in the reactor vessel for refueling is immersed in the coolant in the reactor vessel. At this time, sodium, which is a coolant, is absorbed through the gap between the damper 26 and the upper gripper cylinder 22 and the gas vent hole 34.
26, The upper gripper cylinder 22 is invaded and filled. Although one or more gas vent holes 34 are provided, they are set according to the seismic force so as not to impair the function of the damper.

When the refueling is completed, the refueling machine is pulled out of the reactor vessel and moved to the storage location. However, the sodium inside the damper 26 and the upper gripper cylinder 22 has a gas vent hole 34, so that it can be easily exchanged with the damper 26. It is drained from the gap of the upper gripper cylinder 22. Further, although the refueling machine is normally washed before storage, the gas vent hole 34 is also effective for intrusion of the cleaning liquid.

According to this embodiment, by providing the gas vent hole 34, the sodium damper 26 and the upper gripper cylinder 22 are provided.
Since the sodium in the inside can be easily drained, the sodium adhering to the fuel exchanger that is carried out after that can be reliably washed, and therefore the disassembly and maintenance of the fuel
It does not interfere with inspection and operation tests.

[0075]

According to the present invention, the force acting on the long arm pantograph mechanism and the main body cylinder of the fuel exchanger can be greatly reduced, and the weight and simplification of the relevant portion can be achieved. Also, it is possible to reduce the diameter of the main body,
As the diameter of the fuel exchanger is reduced, the maintenance cask used for installing and removing the fuel exchanger can be downsized.

Further, with respect to the fuel exchange system mounted and used on the rotary plug, the diameter of the rotary plug can be reduced along with the reduction of the diameter of the fuel exchanger, and hence the diameter of the reactor vessel can be reduced. it can.

Further, since the drainage of sodium in the sodium damper part is easy, the cleaning time for adhering sodium carried out after the end of the fuel exchanger is shortened and the workability at the time of disassembling and inspecting the gripper etc. is greatly improved, and a reliable operation is ensured. Maintainability such as inspection can be secured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the essential parts of first and sixth embodiments of a gripper for a fuel exchanger of a fast reactor according to the present invention.

FIG. 2 is a vertical cross-sectional view showing a main part of a second embodiment of the gripper for a fuel exchanger of a fast reactor according to the present invention.

FIG. 3 is a vertical cross-sectional view showing the essential parts of a third embodiment of a gripper for a fuel exchanger of a fast reactor according to the present invention.

FIG. 4 is a cross-sectional view showing a section taken along the line AA in FIG.

FIG. 5 is a vertical cross-sectional view showing the essential parts of a fourth embodiment of the gripper for a fuel exchanger of a fast reactor according to the present invention.

FIG. 6 is a vertical cross-sectional view showing a main part of a fifth embodiment of a gripper for a fuel exchanger of a fast reactor according to the present invention.

FIG. 7 is a schematic configuration diagram for explaining a conventional fast reactor fuel exchanger.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor vessel, 2 ... Fuel assembly, 3 ... Coolant sodium, 4 ... Upper lid, 5 ... Opening, 6 ... Refueling machine, 7 ... Drive part, 8 ... Main body barrel, 9 ... Pantograph mechanism, 10 ... Hold Down tube, 11 ... Gripper, 12 ... Ball screw, 13 ...
Spline, 14 ... Ball nut, 15 ... Gripper claw, 16 ...
Gear with spline nut, 17… Spur gear, 18… Screw gear, 19… Claw opening / closing screw, 20… Claw opening / closing rod, 21… Gripper mechanism, 22… Upper gripper tube, 23… Lower gripper tube, 24…
Tension spring, 25 ... Inside, 26 ... Sodium damper, 27 ... Compression spring, 28 ... Inner cylinder, 29 ... Gripper drive shaft, 30 ... Compression spring, 31 ... Sodium damper, 32 ... Bearing, 33 ... Stepped portion, 34 ... Gas vent hole, 35 ... Magnet, 36 ... Conductor plate, 37 ... Sensing rod, 38 ... Safety ring, 39 ... Joint, 40 ... Sensing rod pressing spring.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Katayama 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Incorporated Toshiba Research and Development Center

Claims (6)

[Claims] 1. A gripper for a fuel exchanger, wherein a fuel assembly loaded into a core of a fast reactor using a liquid metal coolant is attached and detached, and a cylinder constituting the gripper body is formed of an upper gripper cylinder and a lower gripper cylinder. A spring is provided in the upper gripper cylinder, the lower gripper cylinder is engaged and supported by a lower portion of the upper gripper cylinder, and a coolant damper is provided at an engaging portion of the upper and lower gripper cylinders. A gripper for a fast reactor refueling machine. 2. A flange is provided on an upper end of the lower gripper cylinder, an engaging portion for engaging the flange and a lower portion of the upper gripper cylinder is provided, and a cooling material damper is provided at the engaging portion. The gripper for a fuel exchange machine of a fast reactor according to claim 1, wherein a compression spring is provided in the damper. 3. A magnetic generator is provided on at least one of the upper gripper cylinder and the lower gripper cylinder, and
A conductor is provided on at least one of the gripper cylinders facing the magnetism generating means with a gap, and a relative displacement is generated between the magnetism generating means and the conductor in the engaging direction of the upper and lower gripper cylinders. The gripper for a refueling machine according to claim 1, wherein: 4. The lower gripper cylinder includes a plurality of sensing rods, a safety ring interlocked with the movement of the sensing rods, and a spring installed on the safety ring, and the upper gripper cylinder and the lower gripper cylinder are incorporated. 4. The gripper for a refueling machine of a fast reactor according to claim 1, wherein the gripper is connected with a rotatable joint. 5. A groove is formed in a flange portion of the damper,
A gripper for a fuel exchange machine of a fast reactor according to any one of claims 1 to 4, wherein a gap or a gas vent hole is provided. 6. An inner cylinder is provided in the holddown tube, a gripper mechanism and a mechanism such as a ball screw and a spline for driving the gripper mechanism are incorporated in the inner cylinder, and a coil spring is provided at an upper joint portion of the holddown tube and the inner cylinder. A gripper for a refueling machine of a fast reactor, characterized in that a coolant damper is installed.