JP2002257983A - Temporary structure for shielding from radiation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temporary shielding structure against radiation capable of easily shielding indirect radiation from a pressure vessel of an atomic reactor and a radioactivated structure, and making the actual work time extraordinarily longer. SOLUTION: A support member 23 is temporarily fixed by a temporary fixing means such as temporary welding and propping, lateral members 24 and 24a are supported roughly horizontally to the support member 23, and the lateral members 24 and 24a are connected to each other by joint members 26 and 27 as combination, so that a temporary frame 21 is composed around a work space to be shielded from radiation. On this temporary frame 21, shielding members 22 such as mats of lead plates and mats of lead bristles are installed for shielding from radiation. The shielding members 22 can thus be installed even on a flat space, investigation in advance or manufacture based on design is not necessary, emergent construction can be coped with, workers or the like can be easily shielded from indirect radiation, and the actual work time can be extraordinarily made longer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temporary shielding structure for radiation, and more particularly to a temporary shielding structure for radiation when working near a reactor pressure vessel or an activated structure. It is suitable for shielding radiation when working in a shield box around the nozzle of the container.

[0002]

2. Description of the Related Art In a nuclear facility, for example, a BWR nuclear power plant, as shown in FIG.
Various pipes 2 are provided to supply water and the like to the reactor inside the reactor and take out water and steam from the reactor,
A pipe 2 is welded to a nozzle 3 protruding from the reactor pressure vessel 1, and is piped through a radiation shielding wall 4 provided around the reactor pressure vessel 1 for radiation shielding.

As shown in FIG. 4, an opening 5 larger than the pipe 2 is formed in the reactor shield wall 4 to shield the penetration of the pipe 2 of the reactor shield wall 4. A shield box 6 that is covered with a metal plate is attached, and a neutron shield 7 is attached to the inside of the pipe 2 in the shield box 6 in the axial direction, for example, so as to close the gap between the pipe 2 and the shield box 6. A pair of right and left doors 9 attached by hinges 8 close the gap between the pipe 2 on the outside in the axial direction and the shield box 6, and a radiation shield such as a lead plate is attached inside the door 9. is there.

[0004] In order to maintain and check the quality and performance of the welded portion of the pipe 2 connected to the reactor pressure vessel 1 to the nozzle 3 and the like, it is necessary to carry out inspections and improvement work on the pipe during the service period in order to maintain the quality and performance. It is necessary to open the door 9 of the shield box 6 and remove the neutron shield 7 and the like.

[0005] In performing such a work, a shield such as a lead plate mat or a lead bristle mat is wrapped around a pipe or a nozzle to prevent radiation directly received from equipment such as a pipe or a nozzle. If it is possible to conduct site surveys in advance, design and manufacture a lead-molded shield that is suitable for the situation at the site, and use it to use radiation shielding in a work space such as a shield box. We are trying to shield.

[0006]

However, at present,
Although shielding against direct radiation from pipes and nozzles is performed, shielding against indirect radiation from reactor pressure vessels and activated structures is not considered so much, especially until construction. In the case of a sudden construction that does not take much time, a lead molded body designed and manufactured in advance cannot be prepared and shielded, and the work time is strictly controlled to prevent excessive exposure. .

[0007] For this reason, there is a problem that it is not possible to secure a long actual working time, and in a flat working space such as a shield box, a shield such as a lead plate mat or a lead bristle mat is easily temporarily provided. There was also a problem that it could not be attached.

The present invention has been made in view of the above-mentioned problems of the prior art, and can easily shield indirect radiation from a reactor pressure vessel, an activated structure, or the like, and can reduce the actual working time. It is an object of the present invention to provide a temporary shielding structure for radiation that can dramatically increase the length of radiation.

[0009]

According to a first aspect of the present invention, there is provided a temporary shielding structure for radiation, comprising: a support member temporarily fixed by temporary fixing means; and a support member substantially horizontally supported by the support member. A temporary frame is constructed around a work space where radiation should be shielded by combining the horizontal member to be formed and a joint member connecting the horizontal members together, and the radiation is shielded by attaching a shielding member to the temporary frame. It is characterized by the following.

According to the temporary shielding structure for radiation, the support member is temporarily fixed by temporary fixing means such as temporary welding or stretching.
While supporting the horizontal member almost horizontally on this support member,
A temporary frame is constructed around the work space to shield radiation by combining the connection of these lateral members with joint members, and a shielding member such as a lead plate mat or a lead bristle mat is attached to the temporary frame to block radiation. It is designed to shield, and even in a flat space, a shielding member can be attached, there is no need for prior investigation or production based on design, it can respond to sudden construction, etc. In addition to being able to shield easily, the actual working time can be greatly increased.

According to a second aspect of the present invention, there is provided a temporary radiation shielding structure according to the first aspect, wherein the temporary frame is displaced by shifting a supporting position of the horizontal member supported by the support member. The shielding members are configured not to interfere with each other.

According to the temporary shielding structure for radiation, the temporary frame is configured such that the support position of the horizontal member supported by the support member is shifted so that the shielding members do not interfere with each other. Shielding members such as lead and lead wool mats can be arranged and shielded without waste without interfering with each other.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. 1 and 2 relate to an embodiment of a temporary radiation shielding structure according to the present invention. FIG. 1 is a schematic perspective view showing a state where a shielding member is not shown, and FIG. 2 is a partial schematic perspective view showing the shielding member together.

The temporary shielding structure 20 for radiation is used, for example, to inspect the pipe 2 attached to the reactor pressure vessel 1 via the nozzle 3 through the nozzle 3 described in FIG. It is used temporarily to shield radiation from the reactor pressure vessel 1 and activated structures, for example, when opening and removing the shield 7 installed inside to work.

In the temporary shielding structure 20 for radiation, for example, when working in the shield box 6, a temporary frame 21 is installed around the shield box 6 as a working space.
For example, a lead plate mat, a lead wool mat, or the like is attached by hanging or the like to shield it.

The temporary frame 21 is provided with a column member 23 arranged in the vertical direction. In this case, the temporary column 21 is formed by connecting two pipes having a rectangular cross section, and a lower column is attached to the lower side of the upper column member 23a. The member 23b is arranged and welded,
It is reinforced by the reinforcing rib 23c. Support holes 23d for the horizontal members 24 are horizontally formed at the lower end of the upper support member 23a and the lower end of the lower support member 23b, respectively, at the center in the width direction. By shifting 23d right and left by the width of the support member 23, the upper and lower shielding members 22 are prevented from interfering with each other when the shielding member 22 is attached by hanging or the like.

Therefore, the support member 23 is composed of two upper and lower support members 23a and 23b, and a support hole 23d is formed horizontally at the center of the lower end in the width direction to form the shield member 2
This is not limited to the case where the interference of 2 is avoided, and the positions of the plurality of support holes 23d formed in one support member 23 are vertically shifted in the width direction so that the shielding member 22 does not interfere. You can also.

The support members 23 are erected, for example, two are arranged on the left and right sides of the shield box 6 and temporarily fixed by temporary fixing means. As temporary fixing means for this temporary fixing,
Here, the upper end of the support member 23 was temporarily attached to the top surface of the shield box 6 by welding. The temporary fixing means is not limited to the case of welding, but other temporary fixing means may be used as long as the column member 23 can be fixed, such as temporarily fixed with a screw jack mechanism or the like. It is preferable to take no time to remove the waste from the viewpoint of reducing the radiation exposure.

A horizontal member 24 formed of a pipe having a circular cross section is inserted into a horizontally formed support hole 23d of the column member 23, and the position of the horizontal member 24 at a temporary site is determined. Is adjusted and then assembled by welding with the support member 23, and the back surface of the support member 23 and the horizontal member 24
The reinforcing diagonal member 25 is welded to the upper surface of the shielding member 2.
Even if a load of 2 is applied, sufficient strength is ensured. Further, as the horizontal member 24, in addition to those arranged in front and rear in parallel with the axial direction of the pipe 2, horizontal members 24a arranged in right and left directions perpendicular to this are also used.
A joint member 26 is used to connect the 4, 24a.

The joint member 26 is formed, for example, in the shape of a hollow rectangular parallelepiped. The end of the horizontal member 24 is welded to the front surface 26a, and a connecting hole 26c is formed through two right and left side surfaces 26b perpendicular to the horizontal member. This connection hole 26c
After the horizontal member 24a is inserted and adjusted in position, the horizontal member 24a and the joint member 26 are connected by welding at the temporary construction site. Further, a joint member 27 for connecting the horizontal members 24a so as to extend each other is also used. The joint member 27 is formed in a pipe shape having an inside diameter that allows the horizontal member 24a to be inserted, and the ends of the horizontal members 24a to be connected at the temporary site are inserted. Connected by welding.

The left and right side surfaces 2 of the joint member 26
A pipe-shaped connecting member such as a joint member 27 may be attached between the communication holes 26c penetrating through 6b.

Further, a backing plate 28 is welded in advance to the outer ends of the lateral members 24a disposed on the left and right sides, for example, by applying a metal plate 10 for keeping the reactor pressure vessel 1 warm to provide temporary strength. To improve.

The support member 23, the horizontal members 24, 2
4a, the frame-shaped temporary frame 21 is formed by combining the joint members 26 and 27, and is assembled by adjusting the positions of the respective members at the temporary site and welding them. It is fixed in a temporary state by welding the upper end. The temporary frame 21
The order of construction may be such that work at the site is facilitated, for example, after the support members 23 are welded and temporarily installed, and then other members are assembled.

A shield member 22 such as a lead plate mat or a lead bristle mat is attached to each of the horizontal members 24 and 24a.
In the horizontal direction, the adjacent members overlap each other, while the upper and lower
Since the shielding members 22, 24a are shifted from each other, the shielding members 22 are overlapped in the projected state but are not in direct contact with each other, and are attached so as not to interfere with each other.

According to such a temporary shielding structure 20 for radiation, the temporary frame 21 is constructed and temporarily installed in the work space, so that even in the flat shield box 6, a lead plate mat or a lead bristle mat is provided. And the like can be easily attached and shielded.

As a result, it is possible to shield the radiation from the reactor pressure vessel 1 and the activated structure, which has been difficult to shield, and to perform the operation, thereby greatly reducing the actual operation time under a high radiation dose. Can be secured for a long time.

The support members 23, the lateral members 24 and 24a, and the joint members 26 and 27 necessary for constructing the temporary frame 21 are prepared in approximate dimensions, and these are assembled according to the temporary site. Thus, the temporary frame 21 can be constructed, and the time required for the temporary installation can be greatly reduced.

Further, according to the temporary radiation shielding structure 20, since the shielding member 22 is shielded by using a lead plate mat or a lead bristle mat or the like which is normally provided in a nuclear facility, a lead molded body is formed. As compared with the case of preparing and shielding, the preparation in advance can be simplified, and the cost required for shielding can be reduced.

In the above-described embodiment, an example has been described in which the shielding is performed in the case where the operation is performed in the shield box of the pipe connected to the nozzle of the reactor pressure vessel. However, the present invention is not limited to this case. It can also be applied to shielding, and it is possible to easily cope with this by manufacturing each member with dimensions having some allowance and constructing a temporary frame while adjusting it on site.

[0030]

According to the temporary shielding structure for radiation according to the first aspect of the present invention, as described above in detail with one embodiment, the support members are temporarily fixed by temporary fixing means such as temporary welding or stretching. A temporary frame is constructed around a work space where radiation is to be shielded by combining and fixing the horizontal members to the support members substantially horizontally, and connecting the horizontal members with a joint member. A shielding member such as a lead plate mat or a lead wool mat is attached to the shield to shield radiation, so even in a flat space, the shielding member can be attached via a temporary frame, allowing for preliminary investigation and design. It can be used for sudden construction work without the need for production based on the standard, and can easily shield indirect radiation due to activation of structures, etc., and dramatically shorten the actual working time It can be lengthened.

Further, according to the temporary shielding structure for radiation according to claim 2 of the present invention, the temporary frame is displaced from the supporting position of the horizontal member supported by the support member so that the shielding members do not interfere with each other. Therefore, the shielding members such as the lead plate mat and the lead bristle mat can be arranged and shielded without waste without interfering with each other.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a temporary radiation shielding structure according to an embodiment of the present invention, excluding a shielding member according to an embodiment.

FIG. 2 is a partial schematic perspective view shown together with a shielding member according to an embodiment of a temporary shielding structure for radiation of the present invention.

FIG. 3 is a schematic cross-sectional view of a reactor pressure vessel according to an example to which the temporary radiation shielding structure of the present invention is applied.

FIG. 4 is a front view and a cross-sectional view of a shield box to which the temporary radiation shielding structure of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor pressure vessel 2 Piping 3 Nozzle 4 Reactor shielding wall 5 Opening 6 Shield box 10 Metal insulation 20 Temporary radiation shielding structure 21 Temporary frame 22 Shielding member 23 Support member 24 Horizontal member 24a Horizontal member 26 Joint member 27 Joint member 28 Patch plate 29 hook

Claims (2)

[The claims] A support member temporarily fixed by temporary fixing means;
A temporary frame is constructed around a work space where radiation is to be shielded by combining a horizontal member supported substantially horizontally by the support member and a joint member connecting the horizontal members to each other. A temporary shielding structure for radiation, characterized in that radiation is shielded by attaching a radiation shield. 2. The radiation frame according to claim 1, wherein the temporary frame is configured so that the support position of the horizontal member supported by the support member is shifted so that the shielding members do not interfere with each other. Temporary shielding structure.