JP2014013212A - Decontamination method of construction and weedproofing sheet therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decontamination method of construction that prevents flowing out of radioactive substance from sediment including radioactive substance deposited again in a border area between a forest area and a residence area after primary decontamination to the outside of a decontaminated area, and reducing the impact to the health of workers engaging in the decontamination work and reducing the decontamination cost.SOLUTION: A decontamination method of construction laying a weedproofing sheet which can absorb radioactive substance selectively on an area after a primary decontamination.

Description

  In the present invention, forests and living areas after decontamination of undergrowth, fallen leaves, dead branches, litter layers and topsoil containing radioactive substances such as cesium 137 and cesium 134 (hereinafter simply referred to as “radioactive substances”) are used. Fallen leaves and dead branches containing radioactive materials that will be newly deposited on the boundary between the road, the median strip, the roadside and around the trees (hereinafter referred to as the “border between the forest part and the living part”, etc.) The present invention relates to a decontamination method that removes radioactive materials continuously and efficiently without causing radioactive materials to flow out from the soil and inflowing soil, etc., and minimizing health damage to workers.

  Human power such as scoop, mower, rake, jojo, etc. The amount of radiation that affects people living in the living area is reduced by removing and transporting it to another place such as a temporary storage site. This action is called decontamination.

  At present, even if decontamination is performed once, fallen leaves, dead branches, inflow soil, etc. containing radioactive substances always flow into the boundary between the forest part and the living part, etc. due to rainfall, or accumulate due to plant growth. there's a possibility that.

  Therefore, as with the first decontamination (hereinafter referred to as “primary decontamination”), the fallen leaves, dead branches and inflowing soil containing radioactive material that has been deposited again, such as scoops, mowers, rakes, and jolts etc. Decontamination will be done by human power or vacuum machine.

  In decontamination to remove these deposits containing radioactive substances, it is necessary to decontaminate the same part continuously after the primary decontamination, and a method that reduces the impact on health and costs of workers is expected. It is rare.

  The present invention is based on the background of the conventional construction method, and deposits containing radioactive materials that are deposited again at the boundary between the forest part and the living part after the primary decontamination (hereinafter referred to as “next sediment”). Provides a decontamination method that prevents radioactive substances from flowing out of the decontaminated area, reduces the impact on the health of workers engaged in decontamination work, and reduces decontamination costs. The task is to do.

  In order to solve the above-mentioned problems, the present inventors have decontaminated radioactive materials contained in the next sediment by laying a herbicidal sheet made of a composite material using a special material in a primary decontaminated area. We found a construction method that can reduce the impact on the health and the decontamination cost of workers engaged in decontamination work without spilling out of the area.

That is, the present invention is as follows.
1. A decontamination method characterized by laying a herbicidal sheet capable of selectively adsorbing radioactive substances in the area after primary decontamination.
2. 2. The decontamination method as described in 1 above, wherein when the area after the primary decontamination is a slope, a flat field and / or a depression is provided in the lower part of the slope when the grass protection sheet is laid.
3. 3. The decontamination method according to 1 or 2 above, wherein a flat ground and / or a depression is provided at the end of the installation area when the grass protection sheet is installed in the area after the primary decontamination.
4). The next sediment when the next sediment is deposited or the radioactive material contained in the next sediment is adsorbed on the grass protection sheet laid in the area after primary decontamination according to any one of 1 to 3 above And decontamination method to remove the herbicidal sheet together.
5. The method for removing the next sediment and the weedproof sheet together as described in 4 above involves rolling the next deposit deposited on the weedproof sheet from the upper part of the slope together with the weedproof sheet, or weeding A decontamination method that removes the decontamination workers from direct contact with the next deposits and grass protection sheets as much as possible by wrapping them with ropes from the top of the sheet slope.
6). The herbicidal sheet used in the decontamination method according to any one of 1 to 5 above, wherein the ferrocyanide or ferrocyanide compound is contained in a fiber constituting the sheet-like material contained in the herbicidal sheet. .
7). The upper surface and / or the lower surface of the sheet-like material containing ferricyanide or ferrocyanide compound used in the decontamination method according to any one of the above 1 to 5 is included in the herbicidal sheet. , Or a weedproof sheet.
8). The weedproof sheet according to 6 or 7 above, which has air permeability and moisture permeability, has a non-slip surface, and has a light shielding ratio of 90% or more.

  In the present invention, the radioactive material is adsorbed on the herbicidal sheet from the next sediment containing radioactive materials such as cesium 137 and cesium 134 that will be deposited in the area after the primary decontamination, so that the It is possible to reduce the amount that flows into the soil, and the work to remove the next sediment deposited on the boundary between the forest part and the living part after primary decontamination (hereinafter referred to as “secondary decontamination”) In addition, secondary decontamination is a safe and inexpensive decontamination method that can reduce the amount of human work and exposure during the third and subsequent decontamination operations. It is possible to recover radioactive materials.

It is the figure which showed the state which laid the grass prevention sheet as described in this invention in the forest part and the living part slope boundary part after primary decontamination. It is the figure which showed the state in which the deposit containing a radioactive substance was deposited on the surface of the weed prevention sheet described in this invention, or the radioactive substance was adsorbed by the weed prevention sheet. It is a figure which shows the state which winds up and removes the deposit containing a radioactive substance with the grass protection sheet as described in this invention in roll shape. It is the figure which showed the state which provided the depression in the lower part of the slope, and was laid, when laying the weedproof sheet described in this invention in the area after primary decontamination. It is the figure which showed the state which provided the flat ground in the installation area edge part, and laid, when laying the weedproof sheet described in this invention in the area after primary decontamination. It is a figure showing one form of the weedproof sheet as described in this invention. It is a figure showing one form of the weedproof sheet as described in this invention. It is a figure showing one form of the weedproof sheet as described in this invention. It is a figure showing one form of the weedproof sheet as described in this invention. It is a figure showing one form of the weedproof sheet as described in this invention.

  The decontamination method of the present invention first scoops grass, fallen leaves, dead branches, litter layers, topsoil, etc. containing radioactive material deposited in areas such as the boundary between forest and living areas, scoops, mowers, rakes, and jigs. Removed by human power such as shochu and vacuum machine, and carried out to another place such as temporary storage, etc., and then selected the area after performing primary decontamination to reduce the radiation dose that affects people living in living areas It is characterized by laying a weedproof sheet that can adsorb radioactive substances. At that time, the herbicidal sheet is laid on a flat or sloped surface with rolls or fabric products.

  After laying the weedproof sheet, secure the end and joints of the weedproof sheet so that it will not be turned over or damaged by surface water, inflow, wind and rain, wind and snow, or beasts. For this reason, it is better not to adopt a rigid fixing method such as concrete fixing.

  After laying the weedproof sheet, the fallen leaves and dead branches of the vegetation accumulated on the top of the weedproof sheet, the inflowing earth and sand contain radioactive substances, and if the radiation dose in the nearby designated area exceeds the specified value, Decontamination is performed by removing the deposits (next-generation deposits) together with the herbicidal sheet to the outside of the temporary storage area or the like. The decontamination work after the primary decontamination is called secondary decontamination.

  As a method of removing the weedproof sheet, the next sediment deposited on the top of the weedproof sheet is rolled up together with the weedproof sheet from the upper part of the slope by a natural fall or the rope from the upper end of the slope of the weedproof sheet It is possible to adopt a method of wrapping using the like. By adopting this method, the decontamination worker can remove the herbicidal sheet and the next sediment together, while avoiding direct contact with the next sediment and the herbicidal sheet as much as possible.

  The removal of the weed control sheet and the next deposit temporarily reduces the radiation dose in the nearby area after decontamination, but the next deposit accumulates again in the decontamination area. Therefore, it is necessary to repeat the secondary decontamination work until the radiation dose emitted from the next sediment in the vicinity designated area after decontamination becomes a numerical value lower than the specified value. The secondary decontamination includes not only the first decontamination work after the primary decontamination but also the second and subsequent decontamination work.

The herbicidal sheet used in the decontamination method of the present invention has a function of selectively adsorbing the radioactive substance, so that the radioactive substance is added to the fiber itself of the sheet-like material having the herbicidal function constituting the herbicidal sheet. And a substance capable of selectively adsorbing by a method such as blending, impregnation or coating (FIG. 6). In this case, the weedproof sheet may be constituted by a sheet-like material alone, or may be laminated with other sheet-like materials.
In addition, as another configuration, radioactive material adsorption obtained by impregnating, spraying, applying and pasting a sheet-like material having a herbicidal function and a material capable of selectively adsorbing radioactive material on the upper surface and / or lower surface thereof The thing which laminated | stacked the layer is mentioned (FIGS. 7-9). In this configuration, a structure in which a sheet-like material having a herbicidal function is laminated on both surfaces of a radioactive substance adsorption layer obtained by impregnating, spraying, applying or pasting a substance capable of selectively adsorbing a radioactive substance, In addition, a structure (FIG. 10) in which a sheet-like material having a grass-proof function on one side and a sheet-like material having no grass-proof function on the other surface is laminated is included.

  As a substance capable of selectively adsorbing a radioactive substance, an iron ferrocyanide or an iron ferrocyanide compound capable of selectively adsorbing cesium can be preferably used.

  The herbicidal sheet used in the decontamination method of the present invention is a herbicidal sheet that is excellent in herbicidal properties, has air permeability and water permeability, has a non-slip property on the surface, and has a light shielding rate of 90% or more. Preferably there is. Furthermore, it is preferably flame retardant to prevent the spread of fire due to tobacco throwing.

  Since the strength of the herbicidal sheet used in the decontamination method of the present invention may be laid directly on the ground after decontamination, it preferably has an appropriate strength. Further, since the thickness, basis weight, etc. of the weedproof sheet are removed together with the deposits, it is preferable that the thickness of the weedproof sheet is appropriate and easy to handle.

  In the present invention, the radioactive material is adsorbed on the herbicidal sheet from the next sediment containing radioactive materials such as cesium 137 and cesium 134 that will be deposited in the area after the primary decontamination, so that the It is possible to reduce the amount of runoff to the soil, and the amount of human work and exposure when performing the work to remove the next sediment deposited at the boundary between the forest part and the living part after primary decontamination This is a safe and inexpensive decontamination method capable of reducing the amount, and it is possible to efficiently recover radioactive materials.

Claims (8)

  A decontamination method characterized by laying a herbicidal sheet capable of selectively adsorbing radioactive substances in the area after primary decontamination.   2. The decontamination method according to claim 1, wherein, when the area after primary decontamination is a slope, when a weedproof sheet is laid, a flat field and / or a depression is provided at the bottom of the slope.   The decontamination method according to claim 1 or 2, wherein when laying the grass-proof sheet in the area after the primary decontamination, a flat ground and / or a depression is provided at the end of the laying area.   When the next sediment is deposited on the grass-proof sheet laid in the area after the primary decontamination according to any one of claims 1 to 3, or the radioactive material contained in the next sediment is adsorbed, the next deposition Decontamination method that removes objects and weedproof sheets together.   The method for removing the next sediment and the weedproof sheet together according to claim 4, wherein the next deposit deposited on the weedproof sheet is rolled up together with the weedproof sheet from the upper part of the slope. A decontamination method that removes the decontamination workers from the upper edge of the grass sheet slope using a rope, etc., so that the decontamination workers do not touch the next deposits or grass protection sheets as much as possible.   The herbicide which is used for the decontamination method in any one of Claims 1-5, and the ferrocyanide or the ferrocyanide compound is contained in the fiber which comprises the sheet-like material contained in a herbicide sheet Sheet.   The upper surface and / or the lower surface of the sheet-like material containing the ferrocyanide or iron ferrocyanide compound used in the decontamination method according to any one of claims 1 to 5 is impregnated and sprayed. A herbicidal sheet that has been applied or pasted.   The weedproof sheet according to claim 6 or 7, which has air permeability and moisture permeability, has a non-slip surface, and has a light shielding ratio of 90% or more.