JPH0821897A - Shield - Google Patents

Abstract

(57) [Abstract] [Purpose] Shielding that can perform the work during installation and the shielding / opening operation for the radiation source after installation extremely easily and in a short time, and can maintain the shielding effect for a long time. Provide the body. A plurality of exterior panels 15 capable of accommodating a plurality of metal plate blocks 22 having a high radiation shielding effect in a plane.
The foldable shield door 14 is configured by connecting the hinges to each other, and the shield door 14 is hung on a support rail 18 installed above so that the shield door 14 can be expanded horizontally in an empty state in which the metal plate block 22 is not housed. A guide rail 20 which is supported downward and is laid below so that the engaging portion 21 at the lower end of each exterior panel 15 can be guided corresponding to the support rail 18.
After that, the metal plate block 22 is housed in each exterior panel 15 for installation. Further, the shielding / opening operation for the main steam pipe which is a radiation source is performed by unfolding and folding the shielding door 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield for enclosing a radiation source in a reactor containment facility or the like.

[0002]

2. Description of the Related Art FIG. 6 shows an example of a reactor containment facility in which a reactor pressure vessel 1 accommodating a reactor core also functions as a main structural element of a reactor building. 2 contained in the reactor containment vessel 2
Is composed of reinforced concrete which becomes a pressure obstacle against an increase in internal pressure and an inner steel plate for maintaining airtightness.

Further, inside the reactor containment vessel 2, an upper dry well 4 for storing main piping such as a main steam pipe 3 and a bottom portion of the reactor pressure vessel 1 or an interface directly attached to the bottom portion thereof. It is divided into a lower dry well 5 for storing a null pump and a control rod drive mechanism (not shown) and the like, and a suppression chamber 7 formed around the lower dry well 5 and storing pool water 6. The upper dry well 4 and the suppression chamber 7 are arranged by vertically inserting through a substantially cylindrical pedestal 8 that defines the lower dry well 5, and the lower part of the pedestal 8 is located in the pool water 6 in the suppression chamber 7. The upper dry well 4 is connected by a vent pipe 9 submerged in water.
When a phenomenon of loss of coolant occurs in the inside, the high temperature and high pressure fluid discharged into the upper dry well 4 is ejected into the pool water 6 in the suppression chamber 7 through the vent pipe 9, and the ejected high temperature and high pressure fluid is ejected. Is cooled and condensed so that the energy released can be attenuated.

In the reactor containment facility 10 as described above, since it is necessary for an operator to enter the upper dry well 4 to perform various types of maintenance, the pedestal 8 is covered with a living body so as to surround the reactor pressure vessel 1. The wall 11 is erected to shield the radiation emitted from the reactor, but the main steam pipe 3 for guiding steam from the reactor pressure vessel 1
Should also be considered as a radiation source.

Therefore, conventionally, the iron plate block 12 is fixedly attached to the main steam pipe 3 so as to surround it.
Alternatively, the main steam pipe 3 is surrounded by suspending and supporting the lead bristle mat 13 made of lead fiber from the ceiling portion of the upper dry well 4 in a curtain shape.

[0006]

However, when the iron plate block 12 is adopted, it takes time and trouble to remove and reattach the iron plate block 12 when performing maintenance of the main steam pipe 3 itself. During this period, there is a risk that the radiation dose of the worker will increase.

When the lead bristle mat 13 is adopted, the lead bristle mat 13 itself is a heavy object, so that the lead fiber is cut by its own weight by suspending it for a long period of time, and the shielding effect is weakened. There was a problem.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to perform the work during installation and the shielding / opening operation for the radiation source after installation extremely easily and in a short time, and the shielding effect is maintained for a long time. It is an object of the present invention to provide a shield that can be maintained as desired.

[0009]

DISCLOSURE OF THE INVENTION The present invention is a shield for surrounding a radiation source to shield radiation, and a plurality of metal plate blocks having a high radiation shielding effect, and each metal plate block having a planar shape. A plurality of exterior panels that can be housed side by side in a hinged manner by a hinged connection, a support rail that suspends and supports the shielded door so that it can be deployed in the horizontal direction, and each of the shielded doors. And a guide rail which guides an engaging portion provided at a lower end of the exterior panel in correspondence with the support rail.

[0010]

Therefore, in the present invention, when the shield is installed so as to surround the radiation source, the support rail is installed at a predetermined position and the guide rail is laid corresponding to the support rail to accommodate the metal plate block. A required number of shield doors consisting of empty empty exterior panels are suspended and supported from one end side in the longitudinal direction of each of the support rail and the guide rail while sequentially engaging the suspending roller and the engaging portion, and after that. If a plurality of metal plate blocks are stored flatly inside the exterior panel that constitutes each set of shielding doors to complete the installation, a chain block etc. for unloading will be required when installing the shield. Since it is possible to carry in and assemble all the assembled members to the installation position very easily, it is possible to complete the installation of the shield in a short time.

Further, the shielding operation for the radiation sources after installation may be carried out by deploying the shielding doors of each set in the horizontal direction manually by an operator so as to shield the radiation sources. The operation of opening the shield doors may be performed by folding the shield doors of each set in the horizontal direction and bringing them to one end side in the longitudinal direction of the support rail and the guide rail.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 show an embodiment of the shield of the present invention. In the upper dry well 4 in the reactor containment facility similar to that of FIG. 6, the main steam pipe 3 as a radiation source is provided. A plurality of shield doors 14 are hung and supported so as to surround (only two sets are shown in the figure for convenience of description).

The shielding door 14 is configured to be horizontally foldable by hinge-connecting a pair of exterior panels 15 with each other via hinges 16. The shield doors 14 can be swung to the center position in the width direction at the upper end of each exterior panel 15. The suspension roller 17 attached to the upper dry well 4 is suspended and supported by engaging the suspension roller 17 movably in the longitudinal direction of the support rail 18 installed at the upper position in the upper dry well 4.

A guide rail 20 corresponding to the support rail 18 is laid on the diaphragm floor 19 constituting the floor surface of the upper dry well 4, and each exterior panel constituting the shielding door 14. An engaging portion 21 projecting at the center of the lower end of the width direction 15 is movably engaged with and guided by a guide groove 20a (see FIG. 2) formed in the guide rail 20. ing.

Further, in each exterior panel 15 constituting the shielding door 14, a metal plate block 22 having a high radiation shielding effect, such as a hard lead plate or an iron plate, which is formed as a small piece that can be easily transported by an operator. A storage space 23 (see FIG. 2) is secured so that the storage space 23 can be stored in front and rear positions in the thickness direction inside each of the exterior panels 15, respectively.
3, an exterior panel includes a shelf portion 24 for supporting each metal plate block 22 in a plurality of stages (four stages in the illustrated example) in the up-down direction, and metal plate blocks 22 that are doubly arranged front and back in each stage. A flat bar 25 for holding along the inner side surface of the outer panel 15 is provided, and the metal plate block 22 is provided at the width direction outer end portion opposite to the hinge connection side of each exterior panel 15. An opening 26 is formed for insertion from one side, and the opening 26 can be closed by a removable lid 27.

When the shield as described above is installed so as to surround the main steam pipe 3 in the upper dry well 4, for example, the support rail 18 is erected at a predetermined position and the support rail 18 is mounted on the support rail 18. Corresponding guide rail 20
A plurality of sets of shielding doors 14 each including an empty exterior panel 15 in which the metal plate block 22 is not housed, are hung from the supporting rails 18 and the guide rails 20 from one end side in the longitudinal direction of each of the suspension rollers 17 and the engaging rollers. The mating portion 21 is suspended and supported while being sequentially engaged, and after that, from the opening 26 of the exterior panel 15 which constitutes each pair of the shielding doors 14 to the storage space 23.
Insert a plurality of metal plate blocks 22 into each exterior panel 1
5 are arranged in a plane shape at the front and rear positions in the thickness direction, and stored.
After the storage is completed, the opening 26 of each exterior panel 15 is closed by the lid 27 to complete the installation.

In this way, after installing a plurality of sets of shield doors 14 made up of empty exterior panels 15, a plurality of metal plate blocks 22 are arranged in a flat plane in each exterior panel 15 to be housed therein. Since it is possible to carry in and assemble all the assembly members into the upper dry well 4 very easily without the need for a chain block for unloading during installation, the installation of the shield is completed in a short time. It becomes possible to do.

Further, as for the shielding operation for the main steam pipe 3 which is the radiation source after the installation, as shown in FIG. 3, a plurality of sets of shielding doors 14 are horizontally expanded by the human power of the worker to open the main steam pipe 3. It should be shielded, while the main steam pipe 3
Alternatively, the opening operation when performing various maintenance around the main steam pipe 3 is performed by folding the shield doors 14 of each set in the horizontal direction as shown in FIG. You just have to get it.

When a plurality of sets of shielding doors 14 are used to shield the radiation source, it is preferable that adjacent shielding doors 14 be connected to each other via a connecting tool or the like (not shown).

Therefore, according to the above-mentioned embodiment, the work at the time of installation and the shielding / opening operation for the radiation source after the installation can be performed very easily and in a short time, so that the exposure dose to the operator can be remarkably reduced. The safety can be greatly improved.

Further, there is no problem that the shielding effect is diminished by suspending for a long period of time like the conventional lead hair mat, and the shielding effect by the plurality of metal plate blocks 22 housed in the exterior panel 15 in a plane shape is long-term. Can be maintained.

FIG. 5 shows another embodiment of the present invention.
This is an example in which one side portion and the other side portion of the hinge connection portion of the exterior panels 15 composing the shielding door 14 are nested so as to overlap each other. In this way, the shielding door 14 is expanded. Since the gaps formed between the exterior panels 15 at this time can be closed, it is possible to shield the entire surface of the deployed shielding door 14 from radiation.

The shield of the present invention is not limited to the above-described embodiment, and the radiation source to be shielded is not necessarily limited to the main steam pipe in the upper dry well of the reactor containment facility. However, it may be other piping in the upper dry well or a radiation source in equipment other than the reactor containment equipment, the shielding door may be composed of three or more exterior panels, etc. Needless to say, various changes can be made without departing from the scope of the present invention.

[0025]

According to the above-mentioned shield of the present invention, various excellent effects as described below can be obtained.

(I) Since the work at the time of installation and the operation of shielding and opening the radiation source after the installation can be performed extremely easily and in a short time, the dose of the worker is remarkably reduced and the safety is greatly improved. Can be improved.

(II) There is no problem that the shielding effect is weakened by suspending for a long period of time like the conventional lead hair mat,
It is possible to maintain the shielding effect by the plurality of metal plate blocks housed in the exterior panel in a flat shape for a long period of time.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a view taken along the line II-II in FIG.

3 is a view in the direction of arrow III-III in FIG.

FIG. 4 is a plan view showing a state in which the shielding door of FIG. 3 is opened.

FIG. 5 is a sectional plan view showing another embodiment of the present invention.

FIG. 6 is a front sectional view showing an example of a reactor containment facility.

[Explanation of symbols]

 3 Main Steam Pipe (Radiation Source) 14 Shielding Door 15 Exterior Panel 18 Support Rail 20 Guide Rail 21 Engagement Part 22 Metal Plate Block

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Kato 17-17 Shinjuji, Kashiwa-shi, Chiba 1 Yoshizawa Elue Co., Ltd. Harima Heavy Industries Ltd. Yokohama Engineering Center (72) Inventor Toshio Tanaka 1 Shinshinarahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Ishi Kawashima Harima Heavy Industries Ltd. Yokohama Engineering Center

Claims (1)

[Claims] 1. A shield that surrounds a radiation source and shields radiation, and includes a plurality of metal plate blocks having a high radiation shielding effect, and a plurality of exteriors capable of accommodating the metal plate blocks arranged in a plane. A shielding door configured to be foldable by hinge-connecting the panels, a support rail for suspending and supporting the shielding door so that the shielding door can be deployed in a horizontal direction, and an engagement provided at a lower end of each exterior panel of the shielding door. A guide rail that guides the portion corresponding to the support rail.