JP2013104802A - Radiation shielding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shield radiation emitted from a large amount of soil and the like contaminated by radioactive materials.SOLUTION: A radiation shielding member 1 is a member formed in a sheet shape, comprising: a shielding layer 2 made of a lead sheet; buffering layers 3 laminated so as to cover both surfaces of the shielding layer 2 and made of a non-woven fabric impregnated with rubberized asphalt; and a film-like surface covering layer 4 covering the buffering layer and made of a synthetic resin. The radiation shielding member 1 has flexibility and durability and has such a thickness as to be able to be rolled up in a roll shape. The radiation shielding members are laid and spread without a gap along the outer surface of stacked contaminated soil and the like. Moreover, one of the buffer layers laminated on both surfaces of the shielding layers may be covered with the surface covering layer and the other thereof may be laminated with release paper. The radiation shielding member solidifies the soil contaminated by radioactive materials to form soil blocks to attach them to its surface to wrap them. The soil blocks are used as a part of an embankment of a dam body, for example.

Description

  The present invention relates to a radiation shielding member that shields radiation by covering soil, sludge and the like contaminated with radioactive substances.

  Radiation is used for medical treatment and is indispensable for humankind. On the other hand, it is also known that exposure to a large amount of radiation has a profound effect on the human body. For this reason, radiation shielding members are used in facilities that handle radiation, such as medical institutions, for the purpose of suppressing leakage of radiation or protecting persons engaged in radiation handling from radiation. In addition, even in facilities that handle radioactive substances such as nuclear power plants, it is necessary to shield a predetermined area with a radiation shielding member so that workers are not exposed to radiation. Such a radiation shielding member uses, for example, a metal having radiation shielding properties such as lead in the form of a plate or a sheet, as shown in Patent Document 1, and is used in walls, ceilings, floors in facilities that handle radiation. And the like that prevent leakage of radiation, and those that are worn by a person and shield the body from being irradiated with radiation have been proposed.

JP 11-2111888 A

  A large amount of radioactive material is released into the surrounding environment due to an accident at a nuclear power plant, and the surrounding soil is contaminated. In addition, due to the scattering of radioactive material over a wide area, a high concentration of radioactive material is detected in the incinerated ash after incineration of sludge and garbage after sewage treatment. Contaminated soil and sewage sludge must be treated promptly to make the living environment safe, but there is a large amount of contaminated soil and sludge. It is expected that a considerable period will be required. Therefore, a large amount of soil and sludge must be stored in an emergency evacuation site at a temporary disposal site or the like to shield radiation generated from the contaminated soil. In the final disposal, a large amount of soil and sludge must be disposed in a state where radiation is shielded.

However, the conventional radiation shielding member as described in Patent Document 1 is not supposed to shield radiation by covering a large amount of contaminated soil or the like. In addition, it is necessary to have durability when used so as to cover contaminated soil deposited outdoors, and further, it is necessary to prevent the soil from being dissipated.
Therefore, there is a need for a simple and easy means for quickly shielding radiation emitted from a large amount of soil or sludge contaminated with radioactive substances.

  This invention is made | formed in view of the above situations, and it aims at providing the radiation shielding member which can shield easily the radiation which arises from a lot of soil and sludge.

  In order to solve the above-mentioned problem, the invention according to claim 1 is made of a metal having a radiation shielding property, comprising a shielding layer formed in a plate shape or a sheet shape, and a flexible asphalt material, and the shielding layer There is provided a radiation shielding member having a buffer layer laminated on both sides of the material and a surface coating layer made of a synthetic resin and covering the buffer layer.

  This radiation shielding member can shield radiation efficiently at low cost by using a thin plate-like or sheet-like metal such as lead. Then, by laminating a flexible asphalt material on the metal, it is possible to reinforce the plate-like or sheet-like metal and to reduce the force and impact acting from the outside. That is, when covering contaminated soil or the like, damage caused by rubbing against gravel, concrete pieces or the like contained in the soil, damage due to bending or the like is suppressed, and it can be used outdoors. Moreover, when using heavy metals, such as lead, as a metal, the lead damage etc. which lead etc. leak to a surrounding ground can be prevented because the metal surface is coat | covered with the buffer layer which consists of asphalt materials.

  Further, when the contaminated soil is covered with the radiation shielding member, the contaminated soil adheres to the removed radiation shielding member when the soil is moved thereafter. However, the surface of this radiation shielding member is covered with a synthetic resin, so that soil contaminated with radioactive substances can be easily washed away by washing. Therefore, it is possible to prevent the radioactive substance from adhering to the radiation shielding member and diffusing.

In addition, the radiation shielding member that has been used and used in a temporary storage place of contaminated soil can be easily separated into lead and asphalt material by heat treatment, and can be reused.
The surface covering layer may be laminated so as to cover both the buffer layers laminated on both sides of the shielding layer, or may cover one buffer layer and the other buffer layer may be the other. It may be coated with a sheet-like member.

  The invention according to claim 2 is the radiation shielding member according to claim 1, wherein the surface coating layer is laminated and covered on one of the buffer layers laminated on both surfaces of the shielding layer, On the other side of the buffer layer, a release paper that is adhered to the buffer layer and can be easily peeled off from the buffer layer is laminated.

In this radiation shielding member, one side of the asphalt material laminated on both surfaces of the shielding layer is coated with the surface coating layer, and the other surface is coated with release paper. Thereby, even when the radiation shielding members are stacked or wound in a roll shape, it is possible to avoid a situation in which the laminated radiation shielding members adhere to each other with a flexible asphalt material. Further, it is possible to prevent troubles due to the viscosity of the asphalt material during handling such as transportation.
On the other hand, when covering the object emitting radiation, if the object is solidified, the release paper is peeled off and the layer of asphalt material is pressed against the object. Thereby, a radiation shielding member can be affixed on a target object with the adhesiveness of asphalt material. Therefore, it can coat | cover so that a target object may be wrapped by simple operation | work.

  The invention according to claim 3 is the radiation shielding member according to claim 1 or 2, wherein the buffer layer is a non-woven fabric or woven fabric made of synthetic fiber, glass fiber or carbon fiber, and synthetic rubber mixed with asphalt. It is formed by impregnating rubberized asphalt, or formed by embedding the nonwoven fabric, the woven fabric, or a metal mesh in rubberized asphalt.

  In this radiation shielding member, it is reinforced by the nonwoven fabric, woven fabric or metal mesh contained in the buffer layer, and the tensile strength is increased and the flexibility is maintained. Therefore, it is possible to prevent breakage when extended to cover soil or sludge contaminated with radioactive substances. In addition, it is possible to effectively prevent breakage when a sharp stone or the like contained in soil or the like is abutted.

  The invention according to claim 4 is the radiation shielding member according to any one of claims 1 to 3, wherein the shielding layer, the buffer layer, and the surface coating layer are formed in a roll shape when they are laminated. It is assumed that the thickness is set so as to allow winding.

  This radiation shielding member can be wound up in a roll shape, and handling such as transportation and work for covering soil and the like are facilitated. Further, the accumulated radiation-contaminated soil and the like can be covered with a simple operation, the radiation emitted from the radioactive substance can be shielded, and the outflow of the contaminated soil and the like can be suppressed.

  As described above, the radiation shielding member of the present invention can cover a large amount of soil and sludge with a simple operation and shield radiation.

It is a schematic sectional drawing which shows the radioactive shielding member which is one Embodiment of this invention. It is the schematic sectional drawing and schematic perspective view which show the use condition of the radiation shielding member which concerns on this invention. It is the schematic which shows an example of the method of laying the radiation shielding member which concerns on this invention. It is a schematic sectional drawing of the radiation shielding member which is other embodiment of this invention. It is the schematic which shows the use condition of the radiation shielding member shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view showing a radiation shielding member according to an embodiment of the present invention.
The radiation shielding member 1 is composed of a shielding layer 2 in which lead is formed in a sheet shape, a buffer layer 3 laminated on the shielding layer 2, and a surface coating layer 4 covering the buffer layer 3. It is a sheet-like member that can be wound up.
The shielding layer 2 is made of lead, which has high radiation shielding performance, is inexpensive, and can be easily formed thin. The thickness of the lead sheet is appropriately determined according to the contamination concentration of the soil to be covered, but is preferably 0.1 mm or more and 5 mm or less.
In addition, as the shielding layer, tungsten or the like can be adopted as a metal having a large specific gravity. Depending on the required radiation shielding performance, metals such as aluminum steel can be used.

The buffer layer 3 is obtained by impregnating a non-woven fabric made of synthetic fibers with rubberized asphalt obtained by mixing synthetic rubber with asphalt, and further applying rubberized asphalt on both sides to embed the non-woven fabric in the rubberized asphalt. Is about 0.5 mm to 5 mm. The buffer layer 3 is flexibly deformed in the direction along the surface and in the thickness direction, and protects the shielding layer 2 from being damaged even when a stone piece or the like is pressed or rubbed. It has become. Further, the nonwoven fabric is reinforced so as to be resistant to tensile force.
The buffer layer 3 can be adjusted in thickness according to the use of the radiation shielding member, etc., and can be used only in the rubberized asphalt layer without including a nonwoven fabric, and the nonwoven fabric, woven fabric, A metal mesh or the like formed so as to be embedded in rubberized asphalt can also be used.

  The buffer layer 3 is preferably formed at the end of the shielding layer 2 so as to cover the end face of the shielding layer 2 as shown in FIG. That is, the size of the buffer layer 3 is made larger than that of the shielding layer 2, and the buffer layer 3 bonded to both surfaces of the shielding layer 2 is bonded to each other at the portion where the buffer layer 3 protrudes from the edge of the shielding layer 2. It is. Alternatively, one buffer layer may be bent so as to cover the end face of the shielding layer, and folded back onto the other coating layer to be bonded.

The surface coating layer 4 forms the surface of the radiation shielding member 1, and is formed by laminating a synthetic resin in the form of a film having a thickness of about 0.1 μm to 1 mm on the buffer layer 3. As the synthetic resin, for example, polyester, polyethylene, polypropylene, or the like can be used. The lamination to the buffer layer 3 may be performed by applying an adhesive, for example, or may be performed by the viscosity of rubberized asphalt.
The surface coating layer 4 formed in this way suppresses the soil contaminated with the radioactive material from adhering to the buffer layer 3 and easily decontaminates the surface to which the radioactive material is adhered by washing. It is possible.

  As described above, the radiation shielding member 1 formed of a plurality of layers is preferably a strip having a thickness of about 1.2 mm to 17 mm, a width of 0.9 m to 2.0 m, and a length of about 10 m. . And it has the softness | flexibility of the grade which can be wound up in roll shape. When the width is 0.9 m, the length is 10 m, the thickness of the shielding layer 2 is 1 mm, and the thickness of the buffer layer 4 is 1 mm, the sheet wound up in a roll shape has a weight of about 130 kg to 140 kg. . Further, when the width is 2 m and the length is 10 m, the weight is about 260 kg to 280 kg. Therefore, it can be handled by a simple lifting machine or the like, and can be easily transported to the site to be used and covered with contaminated soil or the like.

FIG. 2 is a schematic cross-sectional view and a schematic perspective view illustrating an example of a usage state of the radiation shielding member 1.
Radioactive substances released from the nuclear power plant into the environment are scattered in the atmosphere and fall to the surrounding area to contaminate the soil. Many of the radioactive substances stay in the soil near the ground surface, which is a factor that increases the amount of radiation measured. For this reason, excavating and removing the soil near the ground surface is performed. The removed soil needs to be finally disposed of so as not to affect the residents, but a large amount of contaminated soil is generated and temporarily accumulated in a temporary disposal site.
In addition, a large amount of sewage sludge containing radioactive materials has been generated, and it must be stored indoors or outdoors in an accumulation place until the final disposal method is realized.
FIG. 2 shows a state in which the radiation shielding member 1 of the present invention is laid so as to cover the soil and sludge in the temporary disposal site for contaminated soil and the accumulation site of sewage sludge contaminated with radioactive substances as described above. is there. In this way, radiation is shielded by covering contaminated soil and sludge, thereby preventing the influence on the neighborhood.

  In a contaminated soil or sludge accumulation site, it is desirable to lay a sheet 12 having water-impervious properties in a range where soil or sludge is accumulated. This prevents radioactive material from penetrating into the groundwater. Then, contaminated soil or the like is carried and deposited thereon. The soil or the like may be deposited as it is or may be piled up in a bag. After that, as shown in FIG. 2A, the radiation shielding member 1 covers the soiled soil 11 or the like that is accumulated or stacked.

It is desirable that the radiation shielding member 1 is wound in a roll shape using the core material 1a, and handling such as transportation is performed by supporting the core material 1a. Moreover, the radiation shielding member 1 wound in a roll shape while supporting the core material 1a can be pulled out and laid on the contaminated soil 11 or the like. That is, as shown in FIG. 3, the core material 1 a around which the sheet-like radiation shielding member 1 is wound is supported by a crane 13 or the like, and is deposited on the surface at a predetermined height from the surface of the accumulated contaminated soil 11. The radiation shielding member 1 is pulled out while moving along. Thereby, the sheet-like radiation shielding member 1 can be efficiently laid on the contaminated soil 11 or the like.
Even when the radiation shielding member 1 is dragged on the contaminated soil 11 at the time of laying, the shielding layer 2 made of lead is protected by the buffer layer 3 of the radiation shielding member 1 and the buffer layer 3 has. Reinforced by the nonwoven fabric and the surface coating layer 4, damage to the shielding layer 2 is suppressed.

  As shown in FIG. 2B, the radiation shielding member 1 is laid without gaps along the outer shape of the accumulated contaminated soil 11 while overlapping a predetermined range 1b of the radiation shielding members 1 that are arranged adjacent to each other. Cover and make sure there are no exposed parts. In a portion where gaps are likely to be generated between the overlapping radiation shielding members 1 due to the accumulated shape of contaminated soil or the like, and a portion where displacement is likely to occur between them, the overlapped predetermined range 1b is joined with an adhesive or a tape. May be.

As described above, the radiation shielding member 1 covers the soil containing the radioactive material, the sludge generated in the sewage treatment, the incineration ash of garbage, and the like, so that the radiation dose in the surrounding area can be reduced. The radiation shielding member 1 has durability against solar radiation, wind, rain, temperature difference and the like by the buffer layer 3 made of non-woven fabric impregnated with rubberized asphalt, even when the laying place is outdoors. It has become a thing.
Further, when moving the contaminated soil 11 or the like accumulated in the temporary disposal site to the final disposal site, the radiation shielding member 1 is peeled off, and the surface of the radiation shielding member 1 is washed with water to adhere the contaminated soil or the like. Can be washed away. Therefore, the radiation shielding member 1 can be reused and the diffusion of the radioactive substance can be prevented.

  Moreover, the radiation shielding member 1 that can no longer be reused can be separated and reused by heating. That is, the synthetic resin forming the surface coating layer 4, the rubberized asphalt forming the buffer layer 3, and the lead of the shielding layer 2 can be separated by the difference in melting temperature.

Next, another embodiment of the present invention will be described.
FIG. 4 is a cross-sectional view of a radiation shielding member according to another embodiment of the present invention.
The radiation shielding member 21 includes a shielding layer 22 formed of lead in a sheet shape, a buffer layer 23 laminated on both surfaces of the shielding layer 22, a surface coating layer 24 covering one of the buffer layers 23, and a buffer layer. 23 and the release paper 25 laminated on the other surface.

The said shielding layer 22, the buffer layer 23, and the surface coating layer 24 can use the thing similar to the radiation shielding member shown in FIG.
The release paper 25 is made of a hard-to-break paper such as kraft paper, which is coated with a silicone resin, silicone oil or the like, and a synthetic resin that can suppress the adhesive force with rubberized asphalt is used. ing. Therefore, although it can be laminated and bonded to the buffer layer 23 made of rubberized asphalt, it can be easily peeled off.
Such a radiation shielding member can be stored and transported by being wound or laminated in a roll shape, and the release paper is peeled off immediately before use, and the adhesive strength of the buffer layer 23 made of rubberized asphalt is utilized. can do.

The radiation shielding member can be used as follows.
FIG. 5A is a schematic perspective view showing a soil block 31 in which contaminated soil or the like is wrapped with the radiation shielding member 21, and FIG. 5B is a state in which the soil block 31 is used as a part of the dam body 32. It is a schematic sectional drawing which shows.
The soil block 31 is formed by adding a cement-based solidifying agent to soil contaminated with radioactive material or contaminated sewage sludge, and curing it so that no gaps are generated by the radiation shielding member 21. is there. Such a soil block 31 can be formed as follows, for example. In other words, the formwork is assembled and the reinforcing bars are placed inside it. And the thing which added the solidification agent to the soil contaminated with radioactive substance, sludge, incineration ash, etc. is thrown in, and it is made to harden | cure by supplying moisture. The mold is removed after curing, and the entire outer peripheral surface of the cured soil block 31 is covered with the radiation shielding member 21 as shown in FIG.
The size of the soil block 31 can be a rectangular parallelepiped of about 1 m × 1 m × 6 m, for example.

  The radiation shielding sheet 21 is cut into a corresponding size at the site where the soil block 31 is formed, peeled off the release paper 25 and pressed against the surface of the soil block 31. Thereby, the radioactive ray shielding member 21 is bonded to the soil block 31 by the adhesive force of the buffer layer 23 made of rubberized asphalt. The vicinity of the edge of the radiation shielding member 21 to be attached is overlapped with the radiation shielding member 21 to be attached so as to be adjacent to each other. And the radiation from the radioactive substance contained in the soil block 31 can be shielded by sticking the radiation shielding member 21 to the whole surface of the soil block 31 without a gap.

  The plurality of soil blocks 31 formed in this way can be used as a part of a bank 32 in a river or a coast as shown in FIG. The support 32 is a structure in which soil blocks 31 covered with the radiation shielding member 21 are arranged so as to be stacked at the center of the support 32, and are covered and compacted with soil that is not contaminated with radioactive substances. Since the soil containing the radioactive substance is encased in the radiation shielding member 21 and further covered with the soil layer, the radiation dose on the surface of the body 32 can be made sufficiently small. Therefore, it becomes possible to make final disposal of soil containing radioactive substances, sewage sludge, and incineration ash of garbage.

  The radiation shielding members 1 and 21 according to the present invention are not limited to the above-described embodiments, and can be implemented in other forms that fall within the scope of the present invention. For example, the thickness of each of the shielding layer 2, the buffer layer 3, or the surface coating layer 4 can be appropriately changed, and the total thickness, width, and length of the radiation shielding members 1 and 21 on which these are laminated. Etc. can also be changed. Moreover, it can replace with the nonwoven fabric which consists of a synthetic fiber of the buffer layer 3, and can also use a woven fabric and a metal mesh, and it can replace with a synthetic fiber and can also use glass fiber or carbon fiber.

Further, in the above embodiment, the radiation shielding members 1 and 21 can be wound up in a roll shape, but may be a plate shape having a size of about 0.9 m × 2 m, for example.
On the other hand, the soil block 31 can be used not only in the embankment body 32 but also in the created ground or road embankment.

1: radiation shielding member, 2: shielding layer (sheet-like lead), 3: buffer layer, 4: surface coating layer,
11: soil contaminated with radioactive material, 12: sheet with water barrier,
21: radiation shielding member, 22: shielding layer, 23: buffer layer, 24: surface coating layer, 25: release paper,
31: Soil block, 32: Body

Claims (4)

A shielding layer made of a metal having radiation shielding properties and formed into a plate shape or a sheet shape;
A buffer layer made of a flexible asphalt material and laminated on both sides of the shielding layer;
A radiation shielding member comprising a surface coating layer made of a synthetic resin and covering the buffer layer. The surface coating layer is laminated and coated on one of the buffer layers laminated on both sides of the shielding layer,
The radiation shielding member according to claim 1, wherein a release paper that is bonded to the buffer layer and can be easily peeled off from the buffer layer is laminated on the other of the buffer layers.   The buffer layer is formed by impregnating a non-woven fabric or woven fabric made of synthetic fiber, glass fiber or carbon fiber with rubberized asphalt obtained by mixing synthetic rubber in asphalt, or the non-woven fabric or woven fabric on rubberized asphalt. Alternatively, the radiation shielding member according to claim 1, wherein the radiation shielding member is formed by embedding a metal mesh. The said shielding layer, the said buffer layer, and the said surface coating layer are set to the thickness which can be wound up in roll shape, when these are laminated | stacked, From Claim 1 to Claim 3 characterized by the above-mentioned. The radiation shielding member according to any one of the above.

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