JP2005003408A - Method for decontaminating radioactive contaminant and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for decontaminating radioactive contaminant with simple decontamination work and the structure of a decontamination device and safe and easy disposal of a collected radioactive substance. <P>SOLUTION: A supercritical or liquid-state decontamination fluid is jetted out into a decontamination container 20 to decontaminate the contaminant. The radioactive substance separated from the contaminant is deposited on a container bottom part 25. A decontaminated fluid after the decontamination is turned into a gaseous state by a pressure reducing device 14. The radioactive substance in the decontaminated fluid in a gaseous state is collected by a radioactive substance separator 17. The gaseous decontaminated fluid from which the radioactive substance is collected is pressurized by a compressor 11 into a supercritical or liquid state. In this process, the decontaminated fluid is circulated sequentially through the compressor 11, the decontamination container 20, the reducing device 14, and the substance separator 17. After the decontaminated fluid is circulated for a prescribed period of time, the decontaminated fluid is jetted in a gaseous state together with the radioactive substance deposited out of the decontamination container 20 into a radioactive-substance storage container 60. Further, the gaseous-state decontaminated fluid is discharged out of the storage container 60 into the reducing device 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
This invention economically removes work tools and measuring tools that are contaminated with radioactivity by using regular inspection work at nuclear facilities, or radioactively contaminated solid waste generated by regular inspection work. The present invention relates to a decontamination method for dyeing and a decontamination apparatus used therefor.
[0002]
[Prior art]
Conventionally, hand tools such as spanners, pliers, hammers, etc. that have been contaminated with radioactive materials by using regular inspection work at nuclear facilities, etc., and measuring tools such as scales, calipers, and micrometers (hereinafter referred to as both work tools) Was washed with a cleaning solution using a cloth or brush, and then wiped off with a waste cloth to decontaminate. However, these conventional methods newly generate contaminated wastes such as cleaning liquids and wastes contaminated with radioactive substances, and work tools with complicated shapes cannot completely remove radioactive substances contained in narrow gaps. There was a problem. In addition, some of them are decontaminated as much as possible so that the radioactivity level is not lowered to an allowable value that can be taken out of the nuclear facility, and unavoidably discarded as solid waste. there were.
[0003]
Solid waste such as pipes, pumps, valves, and electric wires is processed by the blast decontamination method after, for example, relatively simple shapes of pipes, and complex debris such as pumps and valves are processed by the chemical decontamination method. Etc. Although the blast decontamination method can be decontaminated relatively easily, there are environmental problems such as the decontamination target being limited and the diffusion of dust containing radioactive substances into the air during blasting. The chemical decontamination method requires a long time for decontamination and is difficult to apply to oily and fat contaminants and paints. In addition, the treatment of the decontamination solution containing the radioactive material after dissolution requires a high level of processing technology, and a large amount of decontamination solution contaminated with the original contamination must be treated. There were many problems. For this reason, the cost of decontamination treatment has increased, and a large contaminant storage place has been required.
[0004]
As a technique for solving these problems, recently, a decontamination method for radioactive substances using supercritical or liquid carbon dioxide as a decontamination agent has been proposed. This decontamination method of radioactive material includes a pretreatment process in which a contaminated material to which powdered radioactive material is attached is brought into contact with supercritical or liquid carbon dioxide, and supercritical or liquid carbon dioxide is depressurized and superconducting. In a radioactive material decontamination method including a step of separating a radioactive substance from a contaminated substance by converting the carbon dioxide in a critical or liquid state into a gaseous state, liquid carbon dioxide is supplied to the radioactive substance separated in the separation step. And cleaning the radioactive material, and separating the fluid containing the radioactive material cleaned in the cleaning step and the liquid carbon dioxide into the radioactive material aggregate and the fluid to collect the radioactive material aggregate. The first recovery step and the fluid separated in the first recovery step are depressurized, and the liquid state carbon dioxide contained in the fluid is changed to a gaseous state to increase the volume, thereby giving the fluid a flow rate. A pressure step, a second recovery step in which the fluid is separated into radioactive fine particles and gaseous carbon dioxide to recover the radioactive fine particles, and the gaseous carbon dioxide separated in the second recovery step is pressurized And a pressurizing step for producing carbon dioxide in a supercritical or liquid state (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP 2002-207097 (2nd page, left column)
[0006]
[Problems to be solved by the invention]
In the conventional decontamination method, a pretreatment process, a separation process, a washing process, and an aggregate recovery process are required to recover the aggregates of radioactive substances, so that the decontamination process is complicated. Further, since the decontamination apparatus requires a solid-liquid separator in addition to a cleaning apparatus, a solid-gas separator, etc., the apparatus configuration is also complicated.
[0007]
An object of the present invention is to solve the above-mentioned problems and to provide a decontamination method for radioactive contaminants and a decontamination device with a simple decontamination work and configuration of the decontamination device.
[0008]
[Means for Solving the Problems]
In the method for decontaminating radioactive contaminants according to the present invention, the decontamination fluid is made of carbon dioxide, and the decontamination fluid is supplied to a decontamination container containing the contaminants contaminated with the radioactive material to decontaminate the contaminants. In the decontamination method, a decontamination fluid in a supercritical or liquid state is ejected into the decontamination container to decontaminate the contaminants, and radioactive substances separated from the contaminants are precipitated at the bottom of the container, and the decontamination fluid after decontamination The gas decontamination fluid in a gaseous state is collected with a radioactive material separator, and the gas decontamination fluid that has collected the radioactive material is pressurized with a compressor to be in a supercritical or liquid state. In this process, the decontamination fluid is sequentially circulated through the compressor, the decontamination container, the decompression device and the radioactive substance separator, and after the decontamination fluid is circulated for a predetermined time, the decontamination fluid is changed to a gaseous state from the decontamination container. Injected into the radioactive material storage container together with the precipitated radioactive material Is allowed to further discharge the decontamination fluid in the gas state to the decompressor from the radioactive substance storing container. Here, the radioactive substance refers to a radioactive substance itself, or a strip or particle of metal, metal oxide, plastic or the like to which the radioactive substance is bound or attached.
[0009]
In the above decontamination method for radioactive contaminants, a supercritical decontamination fluid is sequentially circulated through the decontamination container, the decompression device, the radioactive substance separator and the compressor in succession, so that pretreatment, separation, washing, and coagulation are performed. The decontamination work and the configuration of the apparatus are simpler than the conventional decontamination method in which each step of collecting and collecting is performed independently.
[0010]
In the decontamination method, the liquid decontamination fluid may be ejected from a plurality of nozzles toward the contaminant, or ultrasonic waves may be applied to the liquid decontamination fluid in the decontamination container. Thereby, decontamination in a decontamination container is accelerated | stimulated and decontamination time is shortened. Further, when the radioactive substance in the radioactive substance storage container reaches a predetermined amount, the radioactive substance can be discharged into the radioactive substance recovery container. Thereby, the accumulated radioactive substance can be discarded simply and safely. Further, when the radioactive material is fixed and cannot be easily decontaminated, it is preferable to use a decontamination aid such as a surface active agent or oxalic acid depending on the contamination status.
[0011]
A decontamination apparatus for radioactive contamination according to the present invention includes a compressor that compresses a decontamination fluid composed of carbon dioxide into a supercritical or liquid state, a decompression device that converts the decontamination fluid into a gaseous state, and a radioactive material in the gas decontamination fluid. A radioactive substance separator that separates the substance from the gaseous decontamination fluid; a decontamination container that contains contaminants contaminated with the radioactive substance; a decontamination fluid supply pipe that connects the compressor and the decontamination container; A decontamination fluid supply stop valve provided in the decontamination fluid supply pipe, a decontamination fluid return pipe connecting the decontamination container and the decompression device, and a decontamination fluid detent valve provided in the decontamination fluid return pipe; A decontamination apparatus for radioactive contaminants, wherein the decontamination container is stored at a pressure lower than that of the decontamination container and accumulates a radioactive substance precipitated at the bottom of the decontamination container, and the decontamination container Of radioactive material connecting the bottom of the product and the radioactive material storage container A gas, a radioactive substance discharge stop valve provided in the radioactive substance discharge pipe, a gas decontamination fluid discharge pipe connecting the radioactive substance storage container and the decompression device, and a gas provided in the gas decontamination fluid discharge pipe It consists of a decontamination fluid stop valve.
[0012]
In this radioactive contaminant decontamination apparatus, the decontamination fluid in the supercritical state can be continuously decirculated by continuously circulating the decontamination container, the decompression apparatus, the radioactive substance separator and the compressor. The decontamination work and the configuration of the apparatus are simpler than the decontamination method.
[0013]
The decontamination apparatus may have a structure in which the decontamination container has a basket shape extending in a vertical direction, and includes a cage that accommodates contaminants and can be taken in and out from the opening. Since the decontamination fluid flows from the side surface and the lower surface of the car and the entire contaminant is decontaminated at the same time, the decontamination work time can be greatly shortened.
[0014]
The body of the decontamination container has a cylindrical shape, and includes a rotating rod extending along the center axis of the cylinder, and a car rotation driving device connected to the driving rod, so that the driving rod penetrates the center portion. A structure in which a plurality of cars are stacked may be used. According to this decontamination apparatus, since a plurality of cars are rotated by the car rotation driving device, the decontamination fluid ejected from the ejection nozzle is uniformly decontaminated from the entire solid waste stored in the car. The improvement of the decontamination effect is obtained compared with the case of not using it.
[0015]
The decontamination container has a horizontal shape extending in the horizontal direction, and includes a rail extending from one end of the container to the opening at the other end, and the car moves on the rail via a wheel provided at the bottom of the container. It is good also as a structure which is possible.
[0016]
The decontamination apparatus may have a structure in which a plurality of nozzles for ejecting the liquid decontamination fluid toward the contaminants are provided on the inner wall of the contamination container. An ultrasonic oscillator that applies ultrasonic waves to the liquid decontamination fluid may be arranged in a decontamination container. Furthermore, the radioactive substance recovery container that is held at a pressure lower than the pressure in the radioactive substance storage container and is shielded against radiation, the radioactive substance recovery pipe that connects the radioactive substance storage container and the radioactive substance recovery container, and the radioactive substance recovery It is good also as a structure provided with the radioactive substance collection | recovery stop valve provided in the pipe | tube.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show a first embodiment of the present invention. FIG. 1 is a configuration diagram of the decontamination apparatus, FIG. 2 is a schematic diagram of the decontamination apparatus including a longitudinal sectional view of the decontamination container, and FIG. In this embodiment, a hand tool or a measuring tool (hereinafter referred to as a work tool) contaminated with a radioactive substance is a decontamination target, and the decontaminated work tool is reused.
[0018]
The decontamination apparatus mainly includes a decontamination fluid processing apparatus 10, a decontamination container 20a, a radioactive substance storage container 60, and a radioactive substance collection container 70.
The decontamination fluid processing apparatus 10 includes a compressor 11, a decompression device 14, and a radioactive substance separator 17. The compressor 11 pressurizes the decontamination fluid (carbon dioxide) to a supercritical or liquid state. The decompression device 14 decompresses the decontamination fluid sent from the decontamination container 20 to a predetermined pressure. The supercritical or liquid decontamination fluid becomes a gas in the decompression device 14. As the pressure reducing device 14, a pressure reducing valve, a pressure adjusting valve, or the like is used. The radioactive substance separator 17 includes a filter. The radioactive substance separator 17 collects the fine radioactive substance in the gas decontamination fluid sent from the decompression device 14 by the filter, and separates the radioactive substance from the decontamination fluid.
[0019]
The decontamination container 20a includes a bowl-shaped body 21a having a pressure resistance function. The body 21a is hermetically sealed by a cover 30a being fastened with bolts 32 via a gasket 31 at the top. A pedestal 28 for seating on the floor surface is attached to the bottom 25 of the body 21 a with a set bolt 29. The cover 30a is provided with an eyebolt 33 for suspension at the top. In addition, an injection boss 23 for injecting a decontamination fluid and a return boss 24 for discharging the decontamination fluid are provided on the side wall 22 of the body 21a. The injection boss 23 is connected to a supply port of the decontamination fluid processing apparatus 10 via a decontamination fluid supply pipe 43. A decontamination fluid supply stop valve 37 is attached to the decontamination fluid supply pipe 43. The return boss 24 is connected to the return port 15 of the decontamination fluid processing apparatus 10 via the decontamination fluid return pipe 44. A decontamination fluid detent valve 40 is attached to the decontamination fluid return pipe 44. Thereby, a decontamination fluid circulation loop is formed. A radioactive substance discharge port 26 is provided at the bottom of the body 21.
[0020]
Four nozzle headers 47 extending vertically are fixed to the inner surface of the side wall 22 of the body 21 a at intervals in the circumferential direction, and the nozzle header 47 communicates with the injection boss 23. Each nozzle header 47 is provided with an ejection nozzle 48. The ejection nozzle 48 has a variable ejection (expansion) angle.
[0021]
Inside the body 21a, an annular car 50 in which a metal net 52 or a lattice is attached to a frame 51 is housed. In the car 50, a rod 54 passes through a shaft hole 53 at the center of the car, and a flange 55 at the lower end of the rod is caught on the bottom of the car. The upper portion of the rod 54 is fitted in the guide hole 34 of the cover 30a. With the cover 30a removed, the rod 54 is lifted and lowered by an electric hoist (not shown) or the like, and the car 50 is taken in and out of the opening 27 of the body 21a. Six ultrasonic oscillators 57 are embedded in the side wall 22 of the body 21a at intervals in the circumferential direction, and the oscillator 58 of the ultrasonic oscillator 57 is exposed inside the body 21a.
[0022]
The radioactive substance storage container 60 has an inlet connected to the radioactive substance discharge port 26 at the bottom 25 of the decontamination container 20a via a radioactive substance discharge pipe 63. The pressure in the radioactive substance storage container 60 is maintained at a pressure lower than the pressure in the decontamination container 20a. The radioactive substance discharge pipe 63 is provided with a radioactive substance discharge stop valve 64. A gas chamber 61 at the top of the radioactive substance storage container 60 is connected to the decompression device 14 via a gas decontamination fluid discharge pipe 66. A gas decontamination fluid stop valve 67 is provided in the radioactive substance discharge pipe 63.
[0023]
The radioactive substance collection container 70 is disposed on the exit side of the radioactive substance storage container 60 and is connected to the radioactive substance storage container 60 via a radioactive substance collection pipe 71. The radioactive substance recovery pipe 71 is provided with a radioactive substance recovery stop valve 72. The radioactive substance recovery container 70 is surrounded by a lead plate to prevent leakage of radioactivity from the radioactive substance recovery container 70 to the outside.
[0024]
Next, a decontamination method using the decontamination apparatus configured as described above will be described.
First, the cover 30 is removed, the car 50 is taken out from the inside of the decontamination container 20a, and contaminants such as hand tools or measuring tools contaminated with radioactive substances are put into the car 50. The car 50 is hung with an electric hoist or the like and inserted into the body 21a. Next, the gasket 31 is set on the body 21a, the cover 30a is hung with an eyebolt 33 to cover it, and the bolt 32 is tightened to seal the body 21a.
[0025]
Before the decontamination apparatus is operated, all stop valves such as the decontamination fluid injection stop valve 37 are in a closed state. Further, the decontamination fluid processing apparatus 10 is configured so that the outlet pressure of the compressor 11 is equal to or higher than the critical pressure of carbon dioxide (7.1 MPa, 31 ° C.), and the decompression apparatus 14 is configured so that the outlet pressure is close to atmospheric pressure. Is set to
[0026]
In this state, the operation of the decontamination fluid treatment device 10 is started, the decontamination fluid injection stop valve 37 and the decontamination fluid detent valve 40 are opened, and the supercritical state removal is performed from the supply port 12 of the decontamination fluid treatment device 10. Send out the dye fluid. The pressure in the decontamination container 20a is set lower than the pressure at the outlet of the decontamination fluid injection stop valve 37. Accordingly, the supercritical decontamination fluid is ejected from the plurality of ejection nozzles 48 into the decontamination container 20 a via the decontamination fluid injection stop valve 37, the injection boss 23 and the nozzle header 47. The decontamination container 20a is filled with the ejected supercritical decontamination fluid.
[0027]
The impact force due to the dynamic pressure of the ejected supercritical decontamination fluid is applied to the radioactive material, and the radioactive material is separated from the contaminant. In addition, due to the high permeability and diffusivity of the supercritical decontamination fluid, fine radioactive materials that have entered the narrow part of the contaminant are washed out from the narrow part. Coarse radioactive materials and fine radioactive materials separated from the contaminants settle and settle on the bottom 25 of the decontamination container 20a.
[0028]
Since the car 50 has a structure in which a metal mesh 52 or a lattice is attached to the frame 51, the supercritical decontamination fluid ejected from the plurality of ejection nozzles 48 can uniformly decontaminate the entire contaminants in the car 50. . Since the ejection angle of the ejection nozzle 48 is adjusted in advance according to the size and shape of the contaminant, the decontamination effect can be improved. Further, during the decontamination with the supercritical or liquid decontamination fluid, ultrasonic vibration is applied to the decontamination fluid by the ultrasonic oscillator 57. Thereby, decontamination is accelerated | stimulated and decontamination time is shortened.
[0029]
The supercritical decontamination fluid in the decontamination container 20a flows out from the decontamination container 20a through the return boss 24, the decontamination fluid detent valve 40, and the decontamination fluid return pipe 44, and returns to the decontamination fluid processing apparatus 10. . At this time, the fine radioactive material that has not precipitated in the decontamination container 20a flows out of the decontamination container 20a together with the decontamination fluid. The supercritical decontamination fluid becomes a liquid or gas having a pressure lower than the critical pressure when it leaves the decontamination container 20a, and is depressurized to near atmospheric pressure by the decompression device 14 to become a gas decontamination fluid. Next, the gas decontamination fluid is separated from the gas decontamination fluid by a radioactive substance separator 17 where fine radioactive substances are collected by a filter, a packed bed or the like, or adsorbed by an adsorbent. The fine radioactive material collected here flows out of the decontamination container 20a without being precipitated in the decontamination container 20a. Accordingly, since the amount of collection is considerably reduced compared to the method of collecting all radioactive substances with a filter or the like, the amount of radioactive material generated by the radioactive substance separator 17 and the number of times of cleaning and replacement of the filter are reduced. That's it.
[0030]
The decontamination fluid is circulated between the decontamination fluid processing apparatus 10 and the decontamination container 20a until contaminants such as hand tools and measuring tools are reduced to a reusable radioactivity level. In the initial stage of decontamination, the supercritical decontamination fluid is supplied to the decontamination container 20a. However, the liquid decontamination fluid may be supplied after the fine radioactive material that has entered the narrow portion is washed out from the narrow portion.
[0031]
When the decontamination process is completed, the decontamination fluid injection stop valve 37 and the decontamination fluid return stop valve 40 are closed, and the radioactive substance discharge stop valve 64 and the gas decontamination fluid discharge stop valve 67 are opened. As a result, the pressure in the decontamination container 20a is reduced, and the supercritical or liquid decontamination fluid rapidly expands to become a gas decontamination fluid, flows through the radioactive substance discharge stop valve 64, and flows into the radioactive substance accumulation container 60. . At this time, the radioactive substance adhering to the contaminant is separated by the flow of the gas decontamination fluid, and the separated radioactive substance and the radioactive substance deposited on the bottom 25 of the decontamination container 20a are combined with the gas decontamination fluid. It flows into the radioactive substance storage container 60. The gas decontamination fluid that has flowed into the radioactive substance storage container 60 passes from the gas chamber 61 at the top of the radioactive substance storage container 60 through the gas decontamination fluid discharge stop valve 67 and the gas decontamination fluid discharge pipe 66. Return to. At this time, the fine radioactive substance remaining in the decontamination container 20 a returns to the decontamination fluid processing apparatus 10 together with the gas decontamination fluid and is collected by the radioactive substance separator 17.
[0032]
The radioactive substance accumulation amount in the radioactive substance accumulation container 60 increases as the decontamination process is repeated. This accumulation amount is detected by the radioactive substance level sensor 69. When the accumulated amount reaches a preset amount, the radioactive substance discharge stop valve 64 and the gas decontamination fluid discharge stop valve 67 are closed, and the radioactive substance recovery stop valve 72 is gradually opened. Since the pressure in the radioactive substance storage container 60 is higher than the pressure (atmospheric pressure) in the radioactive substance recovery container 70, the gas decontamination fluid in the radioactive substance storage container 60 is the radioactive substance recovery stop valve 72 and the radioactive substance recovery pipe 71. And flows into the radioactive substance recovery container 70. The radioactive substance in the radioactive substance storage container 60 is discharged into the radioactive substance collection container 70 by the ejection of the gas decontamination fluid. When a predetermined amount of radioactive material accumulates, the radioactive material recovery container 70 is removed from the radioactive material recovery pipe 71 and transferred to the radioactive waste storage site.
[0033]
4 and 5 show a second embodiment of the present invention, FIG. 4 is a schematic view of a decontamination apparatus including a longitudinal sectional view of a horizontal decontamination container 20, and FIG. FIG. In this embodiment, a work tool contaminated with a radioactive substance is a decontamination target, and the decontaminated work tool is reused. In the following embodiments, the same components as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0034]
The decontamination container 20b includes a horizontal body 21b having a pressure resistance function and a cover 30b covering the opening of the body 21b. A car 50 having a wheel 77 attached to the bottom 25 is housed inside the body 21b. A rail 76 extending in the horizontal direction is fixed to the wall surface of the body 21b. The car 50 moves on the rail 76 and is inserted into the body 21b or pulled out from the body 21b.
[0035]
In the decontamination method using the decontamination apparatus, first, the car 50 inside the decontamination container 20b is pulled out, and the contaminated work tool is put into the car 50. In this state, the wheel 77 is moved along the rail 76 in the body 21b, and the car 50 is carried into the body 21b. Next, the gasket 31 is set on the body 21b, the cover 30b is hung with the eyebolt 33, covered, and fastened with the bolt 24 to seal the body 21b. In this state, the decontamination fluid is sent out from the supply port 12 of the decontamination fluid processing apparatus 10, and the decontamination fluid is sealed from the decontamination fluid supply pipe 43 through the decontamination fluid injection stop valve 37 and the injection boss 23. It is injected into the body 21b. The following cleaning process is the same as the process of the first embodiment.
[0036]
6 and 7 show a third embodiment of the present invention. FIG. 6 is a schematic view of a decontamination apparatus including a cross-sectional view of a bowl-shaped decontamination container, and FIG. FIG. In this embodiment, the decontamination target is solid waste, and the solid waste is decontaminated to a radioactive level that can be stored. Examples of solid waste include pipes and plates cut by regular inspection work.
6 and 7, the decontamination container 20c is sealed with a cover 30c. A plurality of annular cages 50 are stacked and housed inside the bowl-shaped body 21c. A car 50 in which rods 54 are stacked passes through a shaft hole 53 in the center, and a flange 55 at the lower end of the rod is hooked on the bottom of the car.
[0037]
The decontamination method using the decontamination apparatus will be described. First, solid waste is put into the car 50 in a state where a plurality of connected cars 50 inside the decontamination container 20c are taken out. In this state, the car 50 is suspended by the rod 54 and inserted into the body 21c. Next, the gasket 31 is set on the body 21 c, the cover 30 c is hung with the eye bolt 33, covered, and sealed with the bolt 32. The following cleaning process is the same as in the case of the first embodiment.
[0038]
In this decontamination equipment, the decontamination target is solid waste, and since the solid waste is in contact with the fluid containing the radioactive material for a long time, it is easily decontaminated by the occurrence of rust, etc. There are many things that cannot be done. Therefore, the decontamination fluid is not carbon dioxide alone, and it is preferable to use a decontamination aid depending on the contamination status. Of course, this decontamination apparatus can be used to decontaminate work tools and the like to a reusable radioactive level or lower.
[0039]
8 and 9 show a fourth embodiment of the present invention. 8 is a schematic view of a decontamination apparatus including a vertical cross-sectional view in a bowl-shaped decontamination container, and FIG. 9 is a view in the direction of arrow D in FIG. It is a cross-sectional view. In this embodiment, the decontamination target is a solid waste. In order to further improve the decontamination effect of the decontamination apparatus shown in FIG. 6, the decontamination apparatus includes a car rotation driving device.
[0040]
Although the basic configuration of the decontamination container 20d shown in FIG. 6 is the same as that of the decontamination container 20d, a rotation rod 80 for supporting a plurality of cars 50 is provided, and a drive rod 81 is connected thereto. That is, the rotating rod 80 is supported at the upper portion by the guide bush 82 so as to be rotatable, and the lower portion is coupled to the car rotation driving device 87 via the driving rod 81 supported by the bush 83. The drive rod 81 is rotatably supported by a bearing 84, and the seal ring 85 prevents leakage from the decontamination container 20d.
[0041]
In the decontamination apparatus, by driving the car rotation driving device 87, the rotating rod 80 rotates through the driving rod 81, and the plurality of cars 50 attached to the rotating rod 80 are rotated accordingly. Since the decontamination fluid ejected from the ejection nozzle 48 uniformly decontaminates the entire solid waste stored in the car, further improvement of the decontamination effect can be obtained as compared with the case where the car 50 is not rotated. The basic configuration and decontamination function of the decontamination fluid processing apparatus 10 are the same as those of the decontamination fluid processing apparatus 10 shown in FIG. 1, but the capacity of the apparatus is large.
[0042]
10 and 11 show a fifth embodiment of the present invention. FIG. 10 is a schematic view of a decontamination apparatus including a longitudinal sectional view of a horizontal decontamination container, and FIG. 11 is a view taken in the direction of arrow E in FIG.
10 and 11, the decontamination apparatus includes a horizontal body 21e having a pressure resistance function, and a cover 30e is attached to the body 21e. Inside the body 21e, a long car 50 for containing contaminated solid waste is accommodated. A wheel 77 for insertion and withdrawal from the body 21 e is attached to the bottom of the car 50. A rail 76 extending in the horizontal direction is fixed to the inner surface of the side wall 22 of the body 21e.
[0043]
In the decontamination apparatus, solid waste is put into the car 50 in a state where the long car 50 inside the decontamination container 20e is pulled out. In this state, the wheel 50 is carried along the rail 76 in the body 21e and the car 50 is carried into the body 21e. Next, the gasket 31 is set on the body 21 e, the cover 30 e is hung with the eye bolt 33, covered, and sealed with the bolt 32. In this state, the decontamination fluid is injected from the supply port 12 of the decontamination fluid processing apparatus 10 into the sealed body 21e. The following cleaning process is the same as in the case of the decontamination container 20e.
[0044]
【The invention's effect】
In the method or apparatus for decontaminating radioactive contaminants according to the present invention, the decontamination work is simplified, so the work time is shortened and the radiation exposure amount of the worker is reduced. In addition, since the configuration of the decontamination apparatus becomes simple, the equipment cost is reduced, and the decontamination of the apparatus itself after maintenance and decontamination work becomes easy.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of the present invention and is a configuration diagram of a decontamination apparatus.
FIG. 2 is a schematic view of a decontamination apparatus including a longitudinal sectional view of a decontamination container.
FIG. 3 is a view taken in the direction of arrow A in FIG.
FIG. 4 shows a second embodiment of the present invention and is a schematic diagram of a decontamination apparatus including a longitudinal sectional view of a decontamination container.
5 is a view in the direction of arrow B in FIG.
FIG. 6 shows a third embodiment of the present invention and is a schematic view of a decontamination apparatus including a longitudinal sectional view of a decontamination container.
7 is a view in the direction of arrow C in FIG.
FIG. 8 shows a fourth embodiment of the present invention and is a schematic view of a decontamination apparatus including a longitudinal cross-sectional view of a decontamination container.
9 is a view in the direction of arrow D in FIG.
FIG. 10 shows a fifth embodiment of the present invention and is a schematic view of a decontamination apparatus including a longitudinal sectional view of a decontamination container.
11 is a view taken in the direction of arrow E in FIG.
[Explanation of symbols]
10 Decontamination fluid processing device 11 Compressor
14 Pressure reducing device 17 Radioactive material separator
20 Decontamination container 21 Body
23 Injection boss 24 Return boss
25 Body bottom 26 Radioactive material outlet
27 Opening 28 Pedestal
30 Cover 31 Gasket
32 Volt 37 Decontamination fluid injection stop valve
40 Decontamination fluid detent valve 43 Decontamination fluid supply pipe
44 Decontamination fluid return pipe 47 Nozzle header
48 jet nozzle 50 basket
52 Car frame 53 Wire mesh
57 Ultrasonic oscillator 58 Oscillator
60 Radioactive substance storage container 61 Gas chamber
63 Radioactive material discharge pipe 64 Radioactive material discharge stop valve
66 Gas decontamination fluid discharge pipe 67 Gas decontamination fluid stop valve
69 Radioactive material level sensor 70 Radioactive material recovery container
71 Radioactive material recovery pipe 72 Radioactive material recovery stop valve
74 Radiation shielding plate 76 Rail
77 Wheel 80 Rotating rod
81 Drive rod 87 Car rotation drive device

Claims (12)

Supercritical or liquid decontamination in a decontamination method in which the decontamination fluid is made of carbon dioxide and the decontamination fluid is supplied to a decontamination container containing the contamination contaminated with radioactive substances. The fluid is ejected into the decontamination container to decontaminate the contaminants, the radioactive material separated from the contaminants is precipitated at the bottom of the container, and the decontamination fluid after decontamination is changed to a gaseous state with a decompression device. The radioactive material in the dyeing fluid is collected by the radioactive material separator, and the gas decontamination fluid that collects the radioactive material is pressurized by the compressor to bring it into the supercritical or liquid state. Circulate the decontamination container, the pressure reducing device and the radioactive substance separator, circulate the decontamination fluid for a predetermined time, and then make the decontamination fluid in a gaseous state and eject it together with the precipitated radioactive substance to the radioactive substance storage container And release the gaseous decontamination fluid. Decontamination method of radioactive contaminants, characterized by discharging the decompressor from sexual material accumulating vessel. The decontamination method for radioactive contaminants according to claim 1, wherein the decontamination fluid is ejected from a plurality of nozzles toward the contaminant. The method for decontaminating radioactive contaminants according to claim 1 or 2, wherein ultrasonic waves are applied to the decontamination fluid in the decontamination container. The method for decontaminating radioactive contaminants according to claim 1, 2 or 3, wherein when the radioactive substance in the radioactive substance storage container reaches a predetermined amount, the radioactive substance is discharged into a radioactive substance collection container which is shielded from radiation. The decontamination method for radioactive contaminants according to claim 1, wherein the decontamination fluid contains a decontamination aid. A compressor that compresses a decontamination fluid composed of carbon dioxide into a supercritical or liquid state, a decompression device that converts the decontamination fluid into a gas state, and a radioactive material that separates the radioactive material in the gas decontamination fluid from the gas decontamination fluid A separator, a decontamination container that contains contaminants contaminated with radioactive substances, a decontamination fluid supply pipe that connects the compressor and the decontamination container, and a decontamination fluid provided in the decontamination fluid supply pipe A decontamination apparatus for radioactive contaminants, comprising a supply stop valve, a decontamination fluid return pipe connecting the decontamination container and the decompression device, and a decontamination fluid detent valve provided in the decontamination fluid return pipe. A radioactive substance storage container that accumulates radioactive material that is held at a pressure lower than the pressure in the decontamination container and that settles at the bottom of the decontamination container, and connects the bottom of the decontamination container and the radioactive substance storage container Installed in the radioactive material discharge pipe and the radioactive material discharge pipe The radioactive material discharge stop valve, a gas decontamination fluid discharge pipe connecting the radioactive substance storage container and the pressure reducing device, and a gas decontamination fluid stop valve provided in the gas decontamination fluid discharge pipe. Characterized decontamination equipment for radioactive contaminants. The decontamination apparatus for radioactive contaminants according to claim 6, wherein the decontamination container has a basket shape extending in the vertical direction, and includes a cage that accommodates contaminants and can be taken in and out of the opening. The body of the decontamination container has a cylindrical shape, and includes a rotating rod extending along the center axis of the cylinder, and a car rotation driving device connected to the driving rod, so that the driving rod penetrates the center portion. The decontamination apparatus according to claim 7, wherein a plurality of cars are stacked. The decontamination container has a horizontal shape extending in the horizontal direction, and includes a rail extending from one end of the container to the opening at the other end, and the car moves on the rail via a wheel provided at the bottom of the container. The decontamination apparatus according to claim 7, which is possible. The decontamination apparatus for radioactive contaminants according to any one of claims 6 to 9, wherein a plurality of nozzles for ejecting liquid decontamination fluid toward the contaminants are provided on the inner wall of the contamination container. The decontamination apparatus for radioactive contaminants according to any one of claims 6 to 10, wherein an ultrasonic oscillator for applying ultrasonic waves to the liquid decontamination fluid is disposed in the decontamination container. Further, the radioactive substance recovery container that is held at a pressure lower than the pressure in the radioactive substance storage container and shielded against radiation, the radioactive substance recovery pipe that connects the radioactive substance storage container and the radioactive substance recovery container, and the radioactive substance recovery pipe The decontamination apparatus of the radioactive contaminant of any one of Claims 6-11 provided with the radioactive substance collection | recovery stop valve provided in.

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