JP2014102092A - Storage container for waste containing radioactive materials - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage container for waste containing radioactive materials that houses waste in association with decontamination of radioactive materials and soil generated during a water purification process, sludge, or the like where radiation is measured.SOLUTION: A storage container 1 for waste containing radioactive materials is composed of a container body 2 comprising sides and a bottom and a lid 3 comprising sides and a top face. The top face, the bottom, and the sides of the storage container are composed of at least three layers of radiation shield layers 4, water shield layers 5, and radioactive material adsorption layers 6.

Description

  The present invention relates to a waste storage container containing a radioactive substance.

  Due to the accident at the Fukushima Daiichi Nuclear Power Station, a large amount of radioactive material was released and dropped to a wide area. Because this radioactive material contaminated the soil, radiation levels higher than usual were measured in many areas. In contrast, the need for decontamination has been pointed out, and decontamination work is being carried out by the national and local governments. In the planned evacuation area, large-scale decontamination work is planned for the future return.

  Decontamination is to reduce the amount of radiation in the living space by removing soil and vegetation with radioactive material attached or covering it with uncontaminated soil, removing topsoil, branches and leaves, When the fallen leaves are removed, a large amount of waste is generated.

  Patent Document 1 discloses a container for decontamination waste in which a plurality of resin sheets having a thickness of about 5 mm are stacked and each layer contains an ultraviolet absorber, thereby taking measures against deterioration of the resin due to ultraviolet rays.

  In addition, Patent Document 2 discloses a storage system in which a plurality of concrete frames are stacked, a water shielding sheet is used, and an open / close lid is provided on the upper part, etc., for the purpose of storing waste in community-based decontamination. A box is disclosed.

Registered Utility Model No. 3173174 Registered Utility Model No. 3178715

  However, in Patent Document 1, radiation shielding is not taken into consideration, and when decontamination waste is collected and stored in such a container, the radiation dose in a storage place such as a temporary storage place is high. There is a problem of becoming. In addition, because it is a sheet, the container may be damaged if it is not suitable for stacking and cannot be used effectively, or if decontaminated waste contains sharp objects or if heavy machinery comes into contact with it. In addition, when the storage period becomes long, there is a problem that it may be broken due to deterioration over time.

  In the thing of the cited reference 2, although radiation can be attenuated with the surrounding wall part made from concrete, it is a laminated structure and there is anxiety about the waterproofness of a joint. Also, it takes time to install because parts are brought to the installation site and assembled by laminating a plurality of concrete frames on site.

  The present invention has been made in view of the above-described problems, and prevents radioactive materials from leaking when containing waste containing radioactive materials, and can be stored safely and reliably for a long period of time, with a high radiation shielding rate. The object is to provide a storage container.

  The invention according to claim 1, which has been made to achieve the above object, is a waste storage container containing a radioactive substance composed of a container main body part and a lid part, wherein the upper surface, the bottom surface, and the side surface of the storage container are: It is composed of at least three layers of a radiation shielding layer, a water shielding layer, and a radioactive substance adsorption layer.

  According to this configuration, the waste contained in the interior is attenuated by the radiation shielding effect of the radiation shielding layer, so that the radiation emitted to the surroundings is attenuated. There is no hot spot around.

  Moreover, since it has a water shielding layer, water containing radioactive substances does not leak out. As a preferred embodiment, the resin layer can be a vinyl chloride water shielding sheet. In this way, the water shielding effect can be surely provided.

  Further, since the radioactive substance adsorbing layer can adsorb radioactive substances such as cesium, there is no risk of the radioactive substance leaking out. Moreover, it has a simple configuration with a small number of parts, and there is no need to assemble the main body container part on site.

  As a preferred embodiment, the radiation shielding layer is made of concrete, so that the entire container can have strength, can be stacked, and a limited area can be used effectively.

  According to the present invention, the radioactive waste contained in the storage container is attenuated by the radiation shielding layer. In addition, there is no possibility of leakage of water containing radioactive substances due to the water shielding layer. Furthermore, since radioactive substances such as cesium can be adsorbed by the radioactive substance adsorbing layer, there is no fear of leakage of radioactive substances. Therefore, for example, it is suitable as a container for storing waste containing radioactive substances such as decontamination waste.

It is a perspective view of the storage container of this invention. It is sectional drawing which shows the structure of a storage container. It is process drawing which shows the manufacturing process of a storage container.

  Hereinafter, specific embodiments of a waste storage container containing a radioactive substance of the present invention will be described with reference to the drawings. As shown in FIG. 1, the storage container 1 according to the embodiment of the present invention includes a container body 2 and a lid 3.

  The container body 2 constitutes the bottom and side surfaces of the storage container 1 and has a rectangular parallelepiped shape with one surface opened, and has a three-layer structure as shown in the sectional view of FIG. The outermost layer is a radiation shielding layer 4, the intermediate layer is a water shielding layer 5, and the innermost layer is a radioactive substance adsorption layer 6.

  The radiation shielding layer 4 is made of precast concrete. The upper part of the container main body 2 is open, and includes an anchor nut 7 for fixing the lid body 3 above the side surface as shown in FIG. The radiation shielding layer 4 bears the mechanical strength of the entire container as an outer frame, and has the strength to withstand stacking. The bottom surface and the side surface are integrally formed, and there are no seams or holes.

  As is well known, concrete has the ability to block radiation, and the radiation shielding layer 4 attenuates the radiation emitted from the decontamination waste contained therein, and the radiation emitted to the outside of the storage container 1. Reduce the amount. Moreover, since there are no joints or holes, it has a certain level of waterproofing effect by concrete. The thickness was about 50 mm to 100 mm.

  The water shielding layer 5 has a water shielding function, and a commercially available water shielding sheet made of polyvinyl chloride was used. In the present embodiment, a CIN Kasei “Sheet for Binon Civil Engineering SNK-XC” (Binon is a registered trademark) having a thickness of 1.5 mm is used, but there is no particular limitation as long as it has a water shielding ability. In decontamination work, a high-pressure washing machine is often used to wash away with water, and in such a case, waste due to decontamination contains a large amount of water. The water-impervious layer 5 can prevent water containing radioactive substances from leaking outside the storage container 1.

  The radioactive substance adsorbing layer 6 was a functional soil obtained by adding an inorganic solidifying material to a clay-like natural soil containing a layered or reticulated silicate mineral. It is dried and solidified after adding water, and is porous.

  The functional soil used for the radioactive substance adsorbing layer 6 was subjected to a moisture absorption / release test based on JIS A 1470-1, and as a result, the water absorption was 44.5%. Further, regarding the adsorption ability of non-radioactive cesium, the removal rate was 98.0%, and the removal rate of non-radioactive strontium was 42.8%. Even when used in a storage container, it is considered to have the same high water absorption rate, cesium removal rate, and strontium removal rate. In the present embodiment, the radioactive substance adsorbing layer 6 has a thickness of 50 [mm]. Therefore, it is considered that the radioactive substance is adsorbed in the innermost layer.

  As shown in FIG. 1, the lid part 3 constitutes the upper surface and a part of the side surface of the storage container 1, and four hooks 8 for lifting the lid part are provided on the upper part. Further, the same anchor nut 7 as that of the container main body 2 is provided, and these are fastened with bolts 10 using the plate 9, whereby the container main body 2 and the lid body 3 are fixed.

In the container main body 2, the thickness of the concrete layer did not change in the height direction, but in the lid 3, as can be seen from FIG. 2, to prevent the water shielding layer 5 and the radioactive substance adsorbing layer 6 from falling. The radiation shielding layer 4 has a thick lower portion and has a cross-sectional shape of a dovetail.
The overall dimensions of the storage container 1 were about 700 to 1500 [mm] in width and depth, and about 400 to 900 [mm] in height.

  As can be seen from FIG. 2, the lid 3 has a three-layer structure similar to the container body 2 and has a similar configuration. As a result, the four side surfaces, the bottom surface, and the top surface of the storage container 1 all have a three-layer structure, and radiation and radioactive substances leak out to the surroundings by the radiation shielding layer 4, the water shielding layer 5, and the radioactive substance adsorption layer 6. To prevent this.

  A method for manufacturing the container body 2 will be described. As shown to Fig.3 (a), the container made from concrete used as the radiation shielding layer 4 is prepared. As shown in FIG. 3 (b), as the water shielding layer 5, a polyvinyl chloride water shielding sheet is appropriately fixed to the inside of the radiation shielding layer 4 using a double-sided tape or an adhesive. Adhere the overlapped surface by heat welding. Next, functional soil is laid on the bottom surface of the water shielding layer 5 so as to ensure a predetermined amount of thickness (here, 50 [mm]). At this time, as the functional soil, a predetermined amount of water necessary for solidification is added and mixed in advance.

  Subsequently, as shown in FIG. 3 (c), a mold 11 is set so that a gap of 50 [mm] is formed around the periphery, and functional soil is placed around the mold 100 [mm] in the height direction. Fill in to the upper and lower parts repeatedly. After a predetermined time has elapsed, the mold 11 is removed (FIG. 3 (d)) and dried. The lid 3 can also be manufactured in the same manner except that it is upside down from the final state. These may be performed in advance at a factory or the like, and need not be assembled at a storage place or a place where decontamination work is performed.

  About the storage container 1 produced in this way, the radiation shielding effect was evaluated. As shown in Table 1, a result of 94% or more was obtained as the shielding rate. As a measuring method, 11.1 [μSv / h] soil is prepared as a test body, and before and after putting the test body at a position 0.5 [m] away from the container with respect to the four side surfaces and the upper surface. The radiation was measured and the shielding rate was calculated.

  The usage method of the storage container 1 of this invention is demonstrated. Bring the storage container 1 to a place where decontamination work is to be performed, put decontamination waste into the container body 2, and cover the opening 3 of the container body 2 with a forklift or the like using the hook 8. . As shown in FIG. 1, the plate 9 is used to fix the container body 2 and the lid 3 to the anchor nuts 7 respectively provided on the container body 2 and the lid 3 with bolts 10. The

Alternatively, it may be installed in a temporary storage place for decontamination waste, and the decontamination waste packed in a bag may be brought in from the place where decontamination work is performed and placed in the storage container 1.
The present invention is not limited to the above-described embodiments and modifications, and various modifications can be made without departing from the gist of the present invention.

  In the embodiment, the decontamination waste has been described. However, when radiation is detected from the purified water generation soil of the water purification plant, the sludge of the sewage treatment plant, or the incineration ash of the incineration plant, these can be stored and stored. .

  In the embodiment, the outermost layer is the radiation shielding layer 4, the intermediate layer is the water shielding layer 5, and the innermost layer is the radioactive substance adsorbing layer 6, but other configurations may be used. For example, the outermost layer may be configured as a water shielding layer 5 using a plastic container, and the intermediate layer may be configured as a radiation shielding layer 4, which is slightly inferior in strength, but if it is small, there is no problem and the radiation shielding effect as a whole It can have a water shielding effect. In this case, as the radiation shielding layer 4, a radiation shielding sheet based on a synthetic resin or a metal plate can be used. In the embodiment, a three-layer structure is used, but four or more layers may be used to improve the function. For example, when it is desired to further increase the radiation shielding rate, the concrete layer may be thickened or a radiation shielding sheet layer may be provided separately.

  As the radioactive material adsorbing layer 6, a functional soil obtained by adding an inorganic solidifying material to a clay-like natural soil containing a layered or reticulated silicate mineral is used. However, the material is not limited to this, and is porous and has a high water absorption rate. Can be used as long as they exhibit a predetermined removal rate.

DESCRIPTION OF SYMBOLS 1 Storage container 2 Container body part 3 Cover body part 4 Radiation shielding layer 5 Water shielding layer 6 Radioactive substance adsorption layer 7 Anchor nut 8 Hook 9 Plate 10 Bolt 11 Formwork

Claims (8)

A waste storage container containing a radioactive substance comprising a container body (2) constituting a side surface and a bottom surface and a lid portion (3) constituting a side surface and an upper surface,
The top, bottom and side surfaces of the storage container are composed of at least three layers of a radiation shielding layer (4), a water shielding layer (5), and a radioactive substance adsorbing layer (6). Storage container.   The outermost layer is the radiation shielding layer (4), the intermediate layer is the water shielding layer (5), and the innermost layer is the radioactive substance adsorbing layer (6). Waste storage container containing radioactive material.   The said radioactive substance adsorption layer (6) has a water absorption property, The storage container of the waste containing the radioactive substance of Claim 1 or 2 characterized by the above-mentioned.   The said radioactive substance adsorption layer (6) adds the inorganic type solidification material to the clay-like natural soil containing a layered or reticulated silicate mineral, The Claim 1 characterized by the above-mentioned. Waste storage container containing radioactive material.   The said radioactive substance adsorption layer (6) is 50 [mm] or more in thickness, The storage container of the waste containing the radioactive substance as described in any one of Claim 1 to 4 characterized by the above-mentioned.   The said water-impervious layer (5) is a vinyl chloride water-impervious sheet, The storage container of the waste containing the radioactive substance as described in any one of Claim 1 to 5 characterized by the above-mentioned.   The said radiation shielding layer (4) is a product made from concrete, The storage container of the waste containing the radioactive substance as described in any one of Claim 1 to 6 characterized by the above-mentioned.   8. A waste storage container containing a radioactive substance according to claim 1, wherein the radiation shielding rate is 90% or more.

Images