JPH0727059B2 - A device that applies a turning force to the shield plug - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus used for withdrawing a shield plug inserted in a lower extension tube of a pressure tube of a pressure tube reactor. . More specifically, when the shield plug held by the ball latch mechanism in the pressure pipe lower extension pipe is pulled out by releasing the ball latch mechanism, when the ball latch mechanism cannot be released smoothly, The present invention relates to a device for applying a rotational force to a shield plug to enable smooth release of a ball latch mechanism.

<Prior Art> As is well known, pressure tube reactors support a large amount of fuel assemblies and coolant in pressure tubes of appropriate thickness to support the pressure associated with high-temperature and high-pressure coolant. By doing so, the core is constructed. At the end of the lower extension pipe of the pressure pipe, a plug called a seal plug prevents leakage of high temperature and high pressure coolant, and a shielding plug is inserted above the seal plug to shield radiation. Has become. The shield plug is connected to the fuel assembly at its upper end, and is inserted into the pressure pipe together with the fuel assembly.

As shown in FIG. 6, the shield plug 10 is held in the pressure pipe lower member extension pipe 20 by a ball latch mechanism.
That is, the ball 12 fitted in the ball mounting hole 11 of the shield plug 10 is pressed outward in the radial direction of the shield plug by the latch body 14 which is always elastically pressed downward by the spring 13.
The extension pipe 20 is fitted in a recess groove 21 machined on the inner wall of the extension pipe 20, whereby the shield plug 10 can be held at a predetermined position of the extension pipe 20.

When exchanging the fuel assembly in the pressure pipe, it is necessary to pull out the shield plug from below the lower extension pipe of the pressure pipe by releasing the ball latch mechanism of the shield plug using the fuel exchanger. FIG. 7 illustrates the operation of the fuel exchanger. The tip of the fuel exchanger grab 30 introduced from the lower end of the pressure pipe lower extension pipe 20 is inserted through the opening of the shield plug lower end 15 (FIG. 7A). A piston that moves axially up and down within the grab when the grab is properly fitted to the shield plug by the ball latch mechanism of 30
The latch body 14 of the shielding plug is pushed up by raising (Fig. 7B). The process of releasing the ball latch mechanism of the shielding plug by pushing up the rack body 14
Shown in the figure. FIG. 8A shows a state in which the shield plug 10 is held by the ball latch mechanism, and the ball 12 is inserted into the extension pipe recess groove 21 by the latch body 14 which is elastically pressed downward by the spring 13 (see FIG. 6). Pressed. FIG. 8B shows a state where the latch body 14 is pushed up by the piston of the grab of the refueling machine, and the recess groove 16 machined on the outer wall of the latch body is at the same level as the ball 12.
In this state, due to the taper effect of the extension pipe recess groove 21, the ball 12 is pushed out in the radial direction of the shielding plug, and the ball 12 is housed in the latch body recess groove 16 as shown in FIG. 8C. The ball latch mechanism is released. By lowering the fuel exchanger in this state, the fuel assembly together with the shielding plug can be extracted from the pressure pipe,
It becomes possible to change fuel.

<Problems to be Solved by the Invention> As described above, when the ball latch mechanism of the shield plug is released, the balls 12 are pushed inward in the shield plug radial direction by the taper effect of the recess groove 21 of the pressure pipe lower extension pipe. It depends on just that. However, when the plant is operated at a high temperature and a high pressure for a long time, the parts 11a and 11b of the ball mounting hole 11 of the shield plug shown in FIG. It is conceivable that the ball 12 may become stuck at the portion 21a of. In such a case, the conventional refueling machine does not have a mechanism for pulling the balls 12 inward in the shield plug radial direction, so the taper effect does not work due to the recess groove 21, and as a result, the ball latch of the shield plug does not function. It becomes impossible to release the mechanism smoothly.

Therefore, an object of the present invention is to fix the ball in the ball latch mechanism of the shield plug as described above without changing the structure of the conventional shield plug and the fuel exchanger and without affecting the normal operation of the plant. An object of the present invention is to provide a device that can easily and reliably cancel a phenomenon.

<Means for Solving Problems> When a ball sticking phenomenon occurs in the ball latch mechanism of the shield plug, the ball may be forcibly rotated by some means.

In this invention, it is an object of the present invention to provide a device that applies a rotational force to the shield plug so as to forcibly rotate the ball by rotating the shield plug in the circumferential direction.

That is, a device for applying a rotational force to a shield plug according to the present invention will be described with reference to FIG. 1 showing an embodiment of the present invention, in which an axial vertical movement of a piston 31 of a conventionally used refueling machine grab 30 is rotated. A rack and pinion mechanism 40 for converting into motion, and a bevel gear 50 for converting the direction of rotational motion obtained by the rack and pinion mechanism into rotational motion in the direction perpendicular to the axis.
, A rotating disc 60 horizontally arranged above the bevel gear, a spur gear 70 that decelerates the rotation of the bevel gear and transmits a rotational force to the rotating disc, and a rotating disc that sandwiches the rotating disc. It is composed of ball holding discs 80, 81 horizontally arranged vertically and having a diameter larger than that of the rotating discs, and a plurality of balls 90 rotatably placed on the outer periphery of the rotating discs between the ball holding discs. There is. The ball holding discs 80, 81 have a diameter that allows them to be fitted in the lower opening of the shield plug, and the outer circumference of the rotating disc 60 is rotated by the rotation of the rotating disc so that the balls 90 are radially outward of the rotating disc. It has a shape that can extrude.

<Operation> By the rack and pinion mechanism 40 and the bevel gear 50, the axial vertical movement of the piston 31 of the refueling machine grab 30 is converted into a rotational movement in the axial perpendicular direction, and this spur gear 70 decelerates this rotational force to rotate the rotary circle. Transmitted to the plate 60. Therefore, with the ball holding disks 80, 81 and the rotating disk 60 fitted in the lower opening of the shielding plug, the piston of the fuel exchanger grab 30 is
If 31 is raised and the rack and pinion mechanism 40 is operated,
The rotating disc 60 can rotate to push the balls 90 radially outward of the rotating disc. When the ball 90 is pushed out and comes into pressure contact with the inner wall of the shield plug lower end portion, the rotational force of the rotating disk 60 is transmitted to the shield plug lower end portion through the ball 90, and the shield plug can be rotated.

Thus, the ball 12 of the ball latch mechanism of the shield plug
Even when (Fig. 6) is fixed, these balls 12 can be rotated in the ball mounting hole 11 as the shield plug rotates, and as a result, the fixation of the balls 12 can be released.

<Embodiment> FIG. 1 illustrates a preferred embodiment of the apparatus of the present invention, and a broken line in the drawing shows a fuel exchanger grab 30 to which the apparatus is attached.

This device is a rack and pinion mechanism 40 that converts vertical movement into rotary motion, a bevel gear 50 that converts the direction of rotary motion by 90 °,
A rotating disc 60 horizontally arranged above the bevel gear, and a spur gear 7 for decelerating the rotation of the bevel gear and transmitting the rotational force to the rotating disc.
0, a ball holding disc that is arranged in parallel above and below the rotating disc so as to sandwich the rotating disc and has a diameter larger than that of the rotating disc.
80, 81, and a plurality of balls 90 rotatably placed on the outer circumference of the rotating disk between these ball holding disks.

The rack and pinion mechanism 40 may have a well-known structure including a rack 41 and a pinion 42 as shown in FIG.
At the lower end of 41, a piston receiving portion 42 (FIG. 1) having a shape that fits into the head portion of the piston 31 in the refueling machine glove 30 is formed.

The bevel gear 50 is a pair of gears 51, 5 having a shape as shown in FIG.
The shaft 51 of one of these gears 51 serves as the pinion 42 of the rack and pinion mechanism 40.

As shown in FIG. 4, the outer circumference 61 of the rotating disc 60 is a ball when the rotating disc 60 is rotated in one direction (arrow).
90 is pushed outward in the radial direction of the rotating disk, and is pressed against the inner wall of the shield plug lower end portion 15 shown by the phantom line, so that when the rotating disk 60 is rotated in the opposite direction, this pressure contact is released. It has a shape with many locally eccentric portions.

Reference numeral 100 in FIG. 1 is a cylindrical frame for attaching the device of the present invention to the fuel exchanger grab 30.
0a is fixed to the lower surface of the ball holding disk 81 in the device of the present invention, and the frame lower end 100b is supported by the shoulder portion 32 formed on the outer periphery of the fuel exchanger grab 30. Therefore, the ball holding disk 81 does not rotate. The shoulder portion 32 is a shoulder portion (see FIG. 7A) that is conventionally formed on the glove 30 to support the lower edge of the shield plug when the glove 30 is fitted into the lower opening of the shield plug. is there.

FIG. 5 shows a state in which the device of the present invention is fitted in the opening of the lower end 15 of the shielding plug. The operation of this device will be described with reference to this figure. Refueling machine grab 30 as shown in FIG.
After this device is mounted on the ball, the grab is raised to allow the ball 90 to reach a predetermined position within the opening of the lower end 15 of the shielding plug. In the example of FIG. 5, when the refueling machine grab is directly inserted into the lower end opening of the shield plug at the time of refueling (see No. 7).
Fig.), Recessing glove 30 side ball latch mechanism ball 33 ball 33 fits the shield plug lower end 15 opening inner wall recess groove 17
The ball 90 of the device of the present invention is fitted to the.

Then, when the piston of the grab is raised, the raising force of the piston is converted into the rotational force of the piston 42 via the rack 41 of the rack and pinion mechanism 40. The generated rotational force is bevel gear
After being turned 90 ° by 50, it is decelerated by spur gear 70 and transmitted to rotating disc 60. When the rotary disc 60 rotates in the direction of the arrow in FIG. 4, the balls 90 are pushed outward in the radial direction of the rotary disc while rotating, and press contact with the inner wall of the shield plug lower end portion 15, that is, the surface of the recess groove 17.

When the grab piston is further raised at this point, the rotary disc 60 is further rotated, and the rotational force is transmitted to the shield plug 10 via the ball 90.

When the shield plug rotates, a rotational force is applied to the ball 12 of the ball latch mechanism of the shield plug. As a result, the restraint force at the fixing points 11a, 11b, 21a of the ball shown in FIG. 8B is released, so that the ball 12 is not moved by the taper effect of the pressure pipe lower extension pipe recess groove 21 as shown in FIG. 8C. It is housed in the latch body recess groove 16 and the ball latch mechanism of the shielding plug can be released.

The shape of the outer circumference 61 of the rotating disk 60 is not necessarily limited to the shape shown in FIG. 4, and for example, the outer peripheral surface of the rotating disk is tapered so as to taper upward. It can also be formed into a curved shape. As a result, the balls arranged on the outer periphery can be pushed out to the outer periphery in the radial direction of the rotating disc by raising the rotating disc while rotating.

<Effects of the Invention> Since the device of the present invention is configured as described above, the following effects can be obtained.

i) By mechanically rotating the ball of the ball latch mechanism of the shield plug through the rotation of the entire shield plug, the ball fixation can be effectively released.

ii) Since the load can be applied to the balls arranged on the outer circumference of the rotating disk not only in the vertical direction but also in the circumferential direction, the load can be efficiently transmitted.

iii) Since the drive motor, power supply, control circuit, etc. are unnecessary, the structure is simple and the reliability of the device is high.
It can be manufactured at low cost and has a high certainty of its operating function.

iv) It can be dealt with only by installing the device of the present invention without making a great change in the structure of the shield plug or the fuel exchanger grab.

v) It has no effect on the normal operation of the plant.

[Brief description of drawings]

1 is a sectional view showing an embodiment of the apparatus of the present invention; FIG. 2 is a rack and pinion mechanism of the apparatus of the present invention, FIG.
Fig. 3 is a sectional view taken along line II-II; Fig. 3 is a bevel gear of the device of the present invention. Fig. 1 is a perspective view of the device taken along line III-III; Fig. 4 is a rotating disk of the device of the present invention. Fig. 1 is a sectional view taken along line IV-IV; Fig. 5 is a sectional view showing a state in which the device of the present invention is fitted in a shielding plug; Fig. 6 is a shielding plug inserted in a pressure pipe lower extension pipe. FIG. 7A and FIG. 7B are sectional views for explaining the operation of the fuel exchanger; FIG. 8A, FIG. 8B and FIG. 8C are sectional views of the ball latch mechanism of the shield plug. It is sectional drawing explaining a cancellation | release process. 10 ... Shielding plug, 15 ... Shielding plug lower end, 20 ... Pressure pipe lower extension pipe, 30 ... Fuel exchange grab, 31 ... Piston, 40 ...
Rack and pinion mechanism, 50 ... Bevel gear, 60 ... Rotating disk, 61
… Rotating disk outer circumference, 70… spur gears, 80,81… ball holding disk, 90… balls.

Claims (1)

[Claims] 1. A rack and pinion mechanism for converting axial up and down movement of a piston of a refueling machine grab into rotary motion, and a bevel gear for converting the direction of rotary motion obtained by the rack and pinion mechanism into rotary motion in the direction perpendicular to the axis. A rotating disc horizontally arranged above the bevel gear, a spur gear that decelerates the rotation of the bevel gear and transmits a rotational force to the rotating disc, and a rotating disc that sandwiches the rotating disc. A ball holding disc, which is horizontally arranged above and below the plate and has a diameter larger than that of the rotating disc, and a plurality of balls rotatably placed on the outer peripheral portion of the rotating disc between the ball holding discs. The disk has a diameter that can fit in the lower opening of the shield plug, and the outer peripheral portion of the rotating disk has a shape capable of pushing the ball outward in the radial direction of the rotating disk due to the rotation of the rotating disk. And this Means for providing a rotational force to the shielding plug, characterized in that the ball has to rotational force of the rotary disc when pressed against the extruded with shielded plug lower end inner wall is transmitted to the shielding plug.