JPH1164582A - Temporary shield device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a worker from being exposed to radiation during work around a pressure vessel nozzle inside a biological shield wall so as to positively prevent the influence of radiation. SOLUTION: A shield body frame 1 is provided with two rails 5, 6 with one ends supported to the shield body frame 1 and with the other ends laterally extended to a pressure vessel external wall 14. A molded shield body 12 with wheels moving by the wheels rolling on the rails are provided on the rails 5, 6. Expansion devices 4 and strut devices 11 of the shield body frame 1 are operated to fix the shield body frame 1 in a biological shield wall plug, and the molded shield body 12 with wheels on the rails 5, 6 are placed near the pressure vessel external wall 14 to prevent a worker from being exposed to radiation from a reactor core part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to reduce the effects of radiation from a reactor core in a work inside a biological shield wall (hereinafter referred to as BSW) plug having a high dose equivalent rate in a reactor containment vessel. The present invention relates to a temporary shielding device to be used.

[0002]

2. Description of the Related Art In a nuclear plant, it is sometimes necessary to carry out work in a BSW when inspecting a pressure vessel joint part in a periodic inspection work of a nuclear reactor. Since this area is to be operated near the reactor pressure vessel (hereinafter referred to as RPV), the environmental dose equivalent rate is high due to the influence of the high dose equivalent rate part in the core, and it is inevitable that the working dose will increase. . The work performed under these high dose equivalent rates includes many important works, and the proportion depending on skilled workers increases. The number of trained workers is limited, and there is a concern that doses may be concentrated on the trained workers to perform some tasks.

Conventionally, work is carried out by installing permanent and temporary shields for protection against major radiation sources.
In the work around the RPV nozzle in W, the degree of the dose equivalent rate from the core, as well as the pipes and nozzles near the main radiation source in the BSW plug, has a high degree of influence.

[0004]

The effect of radiation from pipes, nozzles, etc., close to the main radiation source in the BSW plug is reduced by winding a lead plate or a lead mat around these elements to provide a sufficient shielding effect. It is possible to obtain However, such a method using a lead plate or the like is not used to reduce the influence of radiation from the core, and no effective countermeasure can be taken. For this reason, workers are forced to work at a high dose equivalent rate, and urgent improvement is required.

Therefore, an object of the present invention is to provide an RPV in a BSW.
It is an object of the present invention to provide a temporary shielding device in which an operator is not exposed to radiation while working around a nozzle and is reliably prevented from being affected by radiation.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a shield base fixed at a bottom, both sides and an upper part in contact with a BSW, and one end supported by the shield base. , Two rails extending in the lateral direction so as to reach the outer wall of the RPV, and a molded shield movably provided on the two rails.

[0007] In the temporary shielding device constructed as described above, the molded shield is moved along the rail and placed near the outer wall of the RPV without entering the high dose equivalent rate BSW plug, so that radiation from the reactor core can be obtained. Accordingly, it is possible to effectively prevent the worker from being exposed to the radiation, and it is possible to reliably avoid the influence of radiation in the work around the RPV nozzle.
Further, in the present invention, preferably, a telescopic device is provided at the bottom of the shield base that is in contact with the BSW, and a tension device is provided at both sides and at the top.

In the temporary shielding device configured as described above, the shield base can be stretched and fixed to the inner surface of the BSW plug by a telescopic device and a stretching device extending toward the BSW plug. And it can be fixed in the BSW plug safely.

Further, the present invention provides a cam device at the end of the rail, preferably against the RPV outer wall.

In the temporary shielding device configured as described above, the rail can be fixed to the outer wall of the RPV by the load of the molded shield itself by the function of the cam device.

The present invention also provides a locking device for fixing the molded shield to a rail near the RPV outer wall, preferably closer to the RPV outer wall.

In the temporary shielding device configured as described above, the molded shield can be fixed to a predetermined location near the outer wall of the RPV by the function of the lock device, thereby preventing the shielding effect of the movable forming shield from being impaired. It is possible.

Further, in the present invention, it is desirable that the molded shield comprises a wheeled molded shield having a plurality of wheels, and the molded shield is moved by wheels rolling on rails.

[0014] In the temporary shielding device configured as described above, the molded shield can be moved by a small force that does not burden the operator.

Further, in the present invention, it is desirable that the rail is formed of a rail with rollers provided with a large number of rotating rollers, and the molded shield is moved by sliding on the rotating rollers.

In the temporary shielding device constructed as described above, the molded shielding body can be moved by a small force without imposing a burden on the operator.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the temporary shielding device is B
It has a shield base 1 formed in a size that can be fixed in a SW plug (not shown). The shield base 1 is composed of two front base legs 2a, 2b and two rear base legs 3a, and the inside of the BSW plug is controlled by a telescopic device 4 provided on each of the base legs 2a, 2b, 3a, 3b. The height of the gantry can be changed. Also, two rails 5, 6 are provided so as to extend over both of the pedestal legs 2a, 2b, 3a, 3b. These rails 5 and 6 are pedestal legs 2
a, 2b and supported by two beams 7, 8 extending over the pedestal legs 3a, 3b, the distance between the rails 5, 6 is changed by changing the beam length by connecting fittings 9 at the tip of each beam 7. It is supposed to be. Bolts and nuts 10 are used to connect the connection fittings 9.

Further, the pedestal legs 2a, 3a are attached to the upper and lower two locations and the upper portion of the left side opposed to the BSW plug, while the pedestal legs 2b and 3b are attached to the upper and lower two locations and the upper portion of the right side opposed to the BSW plug. A device 11 is provided for each. Further, a molded shield 12 with wheels is provided that can move back and forth in the BSW plug along the upper surfaces of the rails 4 and 5. A molded lead 13 for shielding radiation is mounted on the molded shield 12 with wheels, and the molded lead 13 is arranged in accordance with the RPV outer wall 14. The rails 5 and 6 are provided with a cam device 15 for fixing the rails 5 and 6 to the RPV outer wall 14.

FIG. 2 shows the pedestal legs 2a, 2b, 3a, 3a.
3B shows details of the telescopic device 4 attached to b. This telescopic device 4 is a hollow column 1 arranged inside a pedestal 2a.
6, a first bevel gear 17 and a second bevel gear 18 provided in the column 6, a remote control handle 19 to which the first gear 17 is connected, and the second bevel gear 18. It is composed of a screw 20 and a fixing nut 21 screwed with the screw 20.

FIG. 3 shows the pedestal legs 2a, 2b, 3a,
3b shows details of a tension device 11 provided in 3b. The stretching device 11 includes a frame member 22 and the frame member 22.
First bevel gear 23 and second bevel gear 2 provided therein
4, a remote device handle 25 connected to the first bevel gear 23, and a bar 2 connected to the second bevel gear 24.
6 and a fixing nut 2 screwed with the strut 26
7 is comprised.

FIG. 4 shows details of the cam device 15 provided on the rails 5 and 6. The cam device 15 includes a cam 29 provided at the end of the rail 5 via a roller pin 28, and a spring 30 connected to the cam 29 and urging the cam 29 upward.

FIG. 5 shows a lock device 31 for fixing the molded shield 12 with wheels. The lock device 31 includes a jack 32 fixed to the lower surface of the rail 5 and a stopper 34 having a spring 33 mounted on the jack 32. In this figure, reference numeral 35 indicates wheels provided on the molded shield 12 with wheels.

FIG. 6 shows details of the remote control handle 19 (25) used for the telescopic device 4 and the tension device 11. The handle 19 (25) is provided with a rotating handle 37 together with a bearing 36 for smooth operation. This handle 19 (25) is connected to the first bevel gear 17 (23) on the front side thereof.
It has a guide member 38 for guiding (25) straight to the first bevel gear 17 (23).

The present embodiment has the above configuration, and
In carrying out the work around the nozzle, the pedestal legs 2a, 2b, 3a, 3 separated one by one in the BSW plug
b is carried in, the gantry legs 2a, 2b are arranged in the front, and the gantry legs 3a, 3b are arranged in the back, and assembled to the shield base 1.
The shield base 1 faces each beam 7, 8;
The connection metal 9 connects the beams 7 and 8 to each other. At this time,
The beam length is adjusted according to the diameter of the nozzle or pipe, and the connection fitting 9 is fixed at that position with bolts and nuts 10.

After the connection between the shield base 1 and the rails 5 and 6 is completed, the ends of the rails 5 and 6 are pressed against the RPV outer wall 14 to be fixed. That is, when the rails 5 and 6 are pressed against the RPV outer wall 14, the cam 29 rotates downward around the roller pin 28, rotates below the rails 5 and 6, and the upper portion of the cam 29 contacts the RPV outer wall 14. The shield base 1 is fixed.

After the position of the shield base 1 is thus determined, the shield base 1 is fixed to the inner surface of the BSW by operating the remote control handles 19 and 25 prepared for the telescopic device 4 and the tensioning device 11, respectively. . That is, when the handle 19 of the telescopic device 4 is inserted straight into the first bevel gear 17 through the guide member 38 and rotated, the screw 20 integral with the second bevel gear 18 meshing with the first bevel gear 17 rotates, and the screw 20 is rotated. The support 16 moves forward and is fixed to the BSW surface in close contact therewith.

When the handle 25 of the tensioning device 11 is inserted straight through the guide member 38 into the first bevel gear 23 and rotated, the second bevel gear 23 meshes with the first bevel gear 23.
The strut 26 integral with the bevel gear 24 advances, and the BSW
It adheres to the surface and is fixed there.

After the fixing to the BSW surface is completed, the molded shield 12 with wheels is mounted on the rails 5 and 6, and the molded lead 13 is mounted on the molded shield 12 with wheels. Thereafter, the molded shield 12 with wheels is carried near the RPV outer wall 14 by the wheels 35 mounted on the rails 5 and 6, and the locking device 3 is used.
1 is operated to fix the wheeled shield 12 there. That is, when the wheel 35 passes, the spring 33 contracts under the stopper 34 mounted on the jack 32. At this time, the stopper 34 descends. When the wheel 35 passes, the spring 33 extends and the stopper 34 moves upward. At this time, the wheeled shield 12 is fixed there.

When the wheeled shield 12 is to be moved after being fixed by the lock device 31, the jack 32 is operated to lower the stopper 34 itself, and the restraint of the wheel 35 is released, and then the wheeled shield 12 is pulled out. .

Molded shield 12 with wheels used here
Must have a width equal to or larger than the diameter of the nozzle or tubing to maintain adequate protection against radiation.

In such a temporary shielding device, the length of the beams 7 and 8 can be changed to match the diameter of the nozzle or pipe, and a molded shield 12 with wheels having a width corresponding to the rail width is mounted. By maintaining a balance between the two, it is possible to obtain a sufficient shielding effect. In addition, the molded shield 12 with wheels does not require a large force when the operator moves the wheels 35 rolling on the rails 5 and 6, and does not impose an excessive burden.

Further, the wheeled molded shield 12 is connected to the rails 5 and 6 without entering the high dose equivalent rate BSW plug.
Moving along the RPV outer wall 14, it is possible to effectively prevent workers from being exposed to radiation from the core, and to reliably avoid the effects of radiation during work around the RPV nozzle. It becomes possible.

Further, the bottom of the shield base 1 is extended and contracted by a telescoping device 4 extending toward the BSW plug, and the upper and lower two sides of the left and right sides and a tensioning device 11 which is extended toward the BSW plug are respectively formed on the inner surface of the BSW plug. Since the shield base 1 is stretched and fixed, the shield base 1 can be extremely firmly and stably fixed in the BSW plug.

The extension device 4 and the tension device 11
Is in a BSW plug with a high dose equivalent rate, but is operated from a place with a low dose equivalent rate using the remote control handles 19 and 25, so that the worker is not directly exposed to radiation.

On the other hand, in the present embodiment, the rail 5,
The rails 5 and 6 can be fixed to the RPV outer wall 14 by the load of the molded shield 12 with wheels by the action of the cam 29 which always contacts the RPV outer wall 14 at the tip of the 6.

Furthermore, the molded shield 12 with wheels can be fixed to a predetermined place near the RPV outer wall 14 by the lock device 31, so that the movable formation type shield moves due to an unexpected accident and the shielding effect is impaired. It is possible to prevent. The handle of this jack 32 has a high dose equivalent rate B
Although it is located inside the SW plug, it is operated from a place where the dose equivalent rate is low, so that the worker is not directly exposed to radiation.

Next, another embodiment of the present invention will be described. In FIG. 7, in this embodiment, rails with rollers are used instead of the rails 5 and 6 of the above embodiment. That is, the rail 4 on which the molded shield 39 is mounted
A number of rotating rollers 92 are mounted on 0 and 41.
The rotating roller 42 can freely rotate within the rails 40 and 41, and the roller 42 on which the molded shield 39 rotates.
It moves over the RPV outer wall 14 while sliding on the top. The molded shield 39 is fixed to the RPV outer wall 14 by the lock device 34 shown in FIG.

According to the present embodiment, since the molded shield 39 moves while sliding on the rotating roller 42, the frictional resistance during the movement of the molded shield 39 can be reduced. The burden on the worker due to the movement of the molded shield 39 can be further reduced as compared with the molded shield 12 with wheels.

[0039]

As described above, according to the present invention, since the molded shield is movably provided on the two rails supported by the shield base, the molded shield can be mounted without entering the BSW plug. By moving along the rail and placing it near the RPV outer wall, it is possible to effectively prevent workers from being exposed to radiation from the core, and to ensure that the radiation around the RPV nozzle is not affected by radiation. Can be spared.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a temporary shielding device according to the present invention.

FIG. 2 is a sectional view showing a telescopic device according to the present invention.

FIG. 3 is a cross-sectional view showing a tensioning device according to the present invention.

FIG. 4 is a configuration diagram showing a cam device according to the present invention.

FIG. 5 is a configuration diagram showing a lock device according to the present invention.

FIG. 6 is a configuration diagram showing a remote control handle according to the present invention.

FIG. 7 is a perspective view showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shield base 4 Telescopic device 5, 6 rail 11 Stretch device 12 Molded shield with wheels 15 Cam device 26 Strut rod 29 Cam 31 Lock device 39 Molded shield

Claims (6)

[Claims] 1. A shield base fixed at a bottom, both sides and an upper part in contact with a biological shield wall, one end of which is supported by the shield base and the other end is extended so as to reach an outer wall of the pressure vessel. A temporary shielding device comprising: two rails formed to extend in the direction; and a molded shielding body movably provided on the two rails. 2. The temporary shielding device according to claim 1, wherein a telescopic device is provided on a bottom portion of the shield base abutting on the living body shielding wall, and a stretching device is provided on both side surfaces and an upper portion. 3. The temporary shielding device according to claim 1, wherein a cam device is provided at an end of the rail that contacts the outer wall of the pressure vessel. 4. The temporary shielding device according to claim 1, wherein a lock device is provided on the rail near the outer wall of the pressure vessel to fix the molded shield closer to the outer wall of the pressure vessel. 5. The molded shield comprises a wheeled molded shield having a plurality of wheels, and the molded shield is moved by the wheels rolling on the rail. 2. The temporary shielding device according to 1. 6. The temporary installation according to claim 1, wherein the rail comprises a roller-equipped rail having a plurality of rotating rollers, and the molded shield is slid on the rotating rollers to be moved. Shielding device.