JPWO2012165027A1 - Cleaning decontamination method and cleaning decontamination apparatus vehicle inside structure contaminated by radioactive material - Google Patents

Abstract

Radioactivity that uses reduced water as cleaning water to remove the contamination of floors, walls, ceilings, etc. inside structures that are contaminated with radioactive materials, and cleans and reuses wastewater used for decontamination Provide a method for decontamination inside a structure contaminated with a substance. A cleaning stage for spraying reduced water charged negatively at a potential of −400 mV to −600 mV to a decontamination target contaminated with radioactive substances, a cleaning waste water recovery stage for recovering the cleaning waste water, and a cleaning waste water Filtration stage for filtering coarse solids to filter and washing wastewater packed with a column filled with a mixture of clay and alum saturated with hydrogen ions or a cation exchange resin saturated with hydrogen ions A first adsorption stage that adsorbs and removes cationized radioactive material in the washing wastewater by passing through the column, and anion exchange resin column saturated with hydroxide ions in the washing wastewater to be anionized in the washing wastewater. The second adsorption stage that removes radioactive substances by adsorption, and the washing wastewater is further passed through a column packed with zeolite to remove the remaining radioactive substances in the washing wastewater. That has a third adsorption step, a washing waste liquid, and the micro-bubble treatment step for returning to the high biological activity of water treated with air microbubbles, the.

Description

  The present invention relates to a cleaning decontamination method and a cleaning decontamination apparatus inside a structure contaminated with a radioactive substance. More specifically, the present invention relates to an oxidation / reduction treatment technique to remove contamination due to a radioactive substance, and to decontamination. The present invention relates to a cleaning and decontamination method and a cleaning and decontamination vehicle for the inside of a structure contaminated with a radioactive substance that can be reused by cleaning used wastewater.

  At a nuclear power plant, the concrete surface of the inner wall and the exposed metal surface are oxidized due to high temperature exposure for a long period of time, but at the oxidation stage, a high level of radioactive material is added to the end of the oxidized material on the concrete surface and exposed metal surface. As the time passes, radioactive materials are taken into the oxidized materials, and highly concentrated radioactive materials accumulate on the walls and metal surfaces of nuclear power plants. Such contamination by radioactive substances is not easy to clean because the contaminants are taken into the walls and the like.

  On the other hand, even in the case of leakage of low-level radioactivity due to cracks in cooling water pipes, etc. due to accidents at nuclear power generation facilities etc., radioactive substances are chemisorbed on concrete surfaces such as floors, walls, ceilings and removed easily. Difficult to do. Such contamination, unlike contamination in the reactor, has a large effect on the human body even at low levels, and its removal is performed by elution with a chelating agent, organic acid, etc. Since there is a residual radioactive material, there is a need for a technique for removing this to the limit.

In nuclear power plants, the removal of radioactivity is performed by solidifying high-level spent nuclear fuel with concrete, burying deep in the ground, and placing low-level radiation, such as clothing, gloves, and other contaminated machinery in contact with the radioactivity in concrete burial. Active pollutants were also packed in drums and hardened with concrete, and buried deep underground, and it was said that the contamination would not spread outside the nuclear power plant.
However, the Fukushima nuclear power plant accident caused by the Great East Japan Earthquake in 2011 caused a lot of radioactive material to be scattered in the vicinity, resulting in contamination by radioactive material on a scale that was not previously envisaged. There is an increasing need for techniques for the removal of contamination.

Although there are very few prior arts for the removal of contamination by radioactive material, typical ones are outlined below.
Patent Document 1 discloses that the elution of metal ions from the corrosion film becomes large at an appropriate water temperature, and that the elution of metal ions is further promoted by the presence of hydrogen peroxide. A method of shutting down a boiling water reactor plant is described that removes material and reduces the air dose rate of the piping.

  Patent Document 2 discloses a method for removing radioactivity on a cementitious surface, in which a cementitious surface contaminated with a radioactive substance is degraded by applying microorganisms, and residues containing the radioactive substance are removed by suction, scraping, or the like. Patent Document 3 describes a radioactivity removal apparatus in a reactor pressure vessel that removes radioactivity by adsorbing it to an ion cladding, and Patent Document 4 injects a noble metal solution and hydrogen into a nuclear reactor. An apparatus and method for attaching a noble metal to a nuclear reactor structure material in which a noble metal is attached to the structural material and an oxide film on the surface of the nuclear reactor structure is removed by a shot peening method are described.

  Patent Document 5 describes a radioactivity removal apparatus that heats and pressurizes an extraction solvent of trifluoroacetylacetone to form a supercritical fluid and performs radioactivity decontamination. Patent Document 6 cleans air with a paper filter. Patent Document 7 describes a chemistry for decontaminating the surface of a steel material contaminated with radioactivity with dicarboxylic acid so that the decontamination solution used therein can be reused. Decontamination methods and chemical decontamination equipment are described.

  The above-mentioned conventional technologies are related to the decontamination of nuclear power plants, the surface of steel materials, and simple air cleaning, and are sufficient for removing pollution in the general living environment due to accidents at nuclear power plants. It wasn't possible.

JP-A-5-164890 JP-A-5-215896 JP-A-6-214091 JP-A-10-186085 JP-A-10-239493 JP 2005-010013 A JP 2006-098360 A

  Due to the accident at the Fukushima Nuclear Power Plant, radioactive material contamination in a wide range of living environments has been confirmed, and the influence of radioactive materials scattered in the air, such as dust, on the human body is considered a problem, and the removal of radioactive materials in the living environment It is an urgent issue. In particular, in factories for food and various equipment, even a slight contamination has a large effect on products and the like, and it is necessary to clean and remove radioactive substances to a level that does not affect them.

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to apply an oxidation / reduction treatment technique to contaminate floors, walls, ceilings, etc. of structures such as factories by radioactive substances. An object of the present invention is to provide a method for cleaning and decontaminating the inside of a structure contaminated with a radioactive material that can be reused by removing waste water used for decontamination.

  In addition, the object of the present invention is to apply oxidation / reduction treatment technology to remove contamination of floors, walls, ceilings, etc. due to radioactive substances, and to clean and reuse waste water used for decontamination. The object is to provide a vehicle for decontamination of a structure contaminated with radioactive material.

  In order to achieve the above object, a cleaning and decontamination method for a structure contaminated with a radioactive substance according to one embodiment of the present invention is applied to a decontamination target contaminated with a radioactive substance at a potential of −400 mV to −600 mV. A washing stage for spraying and discharging negatively charged reducing water, brushing the decontamination object, a washing waste water collecting stage for collecting washing waste water generated in the washing stage, and a filter for collecting the collected washing waste water A filtration step for filtering coarse solids, and the filtered washing waste water is packed with a column filled with a mixture of clay and alum saturated with hydrogen ions or a cation exchange resin saturated with hydrogen ions The first adsorption stage that adsorbs and removes the cationized radioactive material in the washing wastewater through the column, and the washing wastewater that has finished the first adsorption stage is saturated with hydroxide ions. A second adsorption stage that adsorbs and removes the anionized radioactive material in the washing wastewater by passing through the column of the anion exchange resin, and the washing wastewater that has finished the second adsorption stage passes through a column packed with zeolite. A third adsorption stage for removing the radioactive substances remaining in the washing wastewater, and a microbubble for treating the washing wastewater after the completion of the third adsorption stage with air microbubbles to produce highly biologically active water. And a processing stage.

  A vehicle for cleaning and decontaminating a structure contaminated with a radioactive substance according to an aspect of the present invention, which has been made to achieve the above object, is a reduced water connected to a water reduction treatment device that continuously generates reduced water. A water supply hose, a suction device that sucks cleaning wastewater and contaminated dust, a cleaning wastewater transfer hose that is connected to the suction device and transports the suctioned cleaning wastewater and contaminated dust to a cleaning wastewater cleaning device, and the reduced water supply A cleaning device connected to the hose and the cleaning wastewater transfer hose and brushing the object to be decontaminated while spraying the reducing water.

  The cleaning device is supported by an arm that can change the direction of the cleaning brush forward, down, left, and right, and includes a reducing water injection device, a rotating brush, and a cleaning waste water vacuum suction port. In addition, it is preferable that the cleaning waste water can be sucked at the same time.

  The washing / decontamination apparatus vehicle is preferably an unmanned remote control type vehicle.

According to the cleaning and decontamination method for the inside of the structure contaminated with the radioactive substance of the present invention, the decontamination inside the contaminated structure is performed by washing and decontamination using the reducing water having high adsorptivity of the radioactive substance as washing water. It is possible to efficiently decontaminate and restore the usable state without spreading the contamination, and to make the cleaning wastewater reusable as functional water.
Moreover, according to the cleaning and decontamination apparatus vehicle inside the structure contaminated by the radioactive substance of the present invention, it can cope with a wide range of radiation concentration environment, without diffusing the contamination inside the contaminated structure, It can be efficiently decontaminated and restored to a usable state.

It is the figure which showed the oxidation reduction potential of water by the reduction process of water. It is an illustration for demonstrating the manual cleaning operation | work of the decontamination method by one Embodiment of this invention. It is the figure which showed typically the structure of the decontamination reproduction | regeneration apparatus of the washing wastewater contaminated with the radioactive substance of the decontamination method by one Embodiment of this invention. It is the figure which showed typically the riding type radioactive substance decontamination apparatus vehicle by one Embodiment of this invention. It is the figure which showed typically the unmanned remote control type radioactive substance decontamination apparatus vehicle by one Embodiment of this invention.

Hereinafter, the specific example of the form for implementing the washing | cleaning decontamination method inside the structure contaminated with the radioactive substance of this invention is demonstrated in detail.
The present invention uses a contaminated structure by cleaning and decontamination using cleaning water as reducing water having high adsorptivity to the radioactive substance in cleaning and decontamination of the internal environment of the structure contaminated by the radioactive substance. In addition to restoring it to a possible state, it is possible to remove the radioactive substances from the washing wastewater and perform microbubble treatment to make it functional water with high biological activity so that the wastewater can be reused effectively.

As shown in FIG. 1, the reduced water used as the washing water in the present invention has a different oxidation-reduction potential (Eh) (under normal temperature and normal pressure) depending on the reduction treatment conditions.
The potential of the reducing water used in the present invention is negatively charged from −400 mV to −600 mV in terms of the cleaning effect and solubility of the ionized radioactive substance.

  The method for cleaning and decontaminating a structure according to an embodiment of the present invention is a cleaning method in which reducing water is sprayed and brushed on a decontamination target inside the structure such as a floor surface, a wall surface, or a ceiling surface contaminated with a radioactive substance. A washing waste water collecting stage for collecting washing waste water, a filtration stage for sending washing waste water to a filter to filter coarse particles, a first adsorption stage for passing washing waste water through a first adsorption column, A second adsorption stage for passing through the second adsorption column; a third adsorption stage for passing through the third adsorption column; and a microbubble treatment stage for subjecting the washing wastewater to microbubble treatment.

  The cleaning and decontamination method inside the structure differs depending on the size of the structure to be decontaminated, the contamination status, etc., so a manual method, a method using a passenger type vehicle with a protective device, an unmanned remote control vehicle Three examples of the method will be described with reference to the drawings.

<Manual cleaning and decontamination method for internal structures>
FIG. 2 is an exemplary view for explaining a manual cleaning operation of the decontamination method according to the embodiment of the present invention.
The situation shown in FIG. 2 is a situation where three workers wearing protective clothing are cleaning and decontaminating the floor surface 1 contaminated with radioactive materials inside the structure by human power. A worker has a reducing water injection gun 2 provided at the tip of a reducing water feed hose 3 connected to a reduction treatment tank 5, and sprays reducing water toward the floor surface 1. The surface 1 is brushed, and another worker has a suction nozzle 12 provided at the tip of the suction hose 13 connected to the suction device 14, and sucks contaminated reduced water (hereinafter referred to as cleaning waste water) after cleaning. The solution is sent to the wastewater treatment facility.

  In the present embodiment, since the reducing water used for cleaning the inside of the structure such as the floor surface, the wall surface, and the ceiling surface is negatively charged, the radioactive material charged positively such as cesium, cobalt, strontium, etc. is efficiently used. Because it dissolves well and the water cluster is small, it has strong penetrating power and high detergency.

  Reduced water is also negatively adsorbed to the decontamination target by spraying a large amount of negatively charged reduced water to the decontamination target, even for radioactive substances that are negatively charged, such as iodine. Since the charged radioactive substance is replaced with reduced water and the radioactive substance is transferred to the water side, it exhibits an excellent cleaning effect.

<Method of cleaning and decontaminating the interior of a structure with a passenger-type vehicle>
FIG. 4 is a diagram schematically showing a passenger-type radioactive material decontamination apparatus vehicle according to an embodiment of the present invention.
The cleaning and decontamination method using a passenger-type vehicle provided with a protective device corresponds to cleaning and decontamination inside a structure having a relatively large space where the radiation concentration is high and the working time is limited.

  The passenger-type radioactive material decontamination apparatus vehicle according to the present embodiment is connected to the reduced water feed hose connected to the water reduction treatment apparatus, the suction apparatus that sucks the cleaning waste water and the contaminated dust, and the suction apparatus. Cleaning wastewater transfer hose for transporting the cleaned cleaning wastewater and contaminated debris to the cleaning wastewater cleaning device, a reducing water supply hose, and a cleaning device connected to the cleaning wastewater transfer hose and brushing decontamination objects while spraying the reducing water And have.

  In addition, the passenger-type radioactive material decontamination apparatus vehicle according to the present embodiment is supported by an arm that can change the direction of the cleaning brush forward, down, left, and right, and the reduced water injection device, the rotating brush, and the cleaning waste water vacuum suction It is preferable to provide a mouth and to be able to simultaneously perform injection of reducing water, brushing with a rotating brush, and suction of cleaning wastewater.

  As shown in FIG. 4, the passenger-type radioactive material decontamination apparatus vehicle according to the present embodiment uses a rotating brush device 27 with a heavy motor 28 as a left and right rotating arm 29, an upper and lower front rotating fulcrum 30, and hydraulic pressure. A vertically moving main arm 31 that operates, a horizontal fulcrum 32 that enables the main arm to move left and right, a reducing water supply hose 33 that supplies reducing water, and suction that removes cleaning wastewater after cleaning with reducing water. This is a passenger-type radioactive decontamination vehicle equipped with a hose 34.

  Further, the vehicle can turn the rotating brush upward, forward, downward, left and right, and the vertical moving main arm allows the rotating brush to be raised and lowered and moved left and right.

<How to clean and decontaminate structures using unmanned remote-controlled vehicles>
FIG. 5 is a diagram schematically showing an unmanned remote control type radioactive material decontamination apparatus vehicle according to an embodiment of the present invention.
The method using the unmanned remote control vehicle corresponds to the cleaning and decontamination of the inside of the structure where the radiation dose is very high and a person cannot enter.

  The unmanned remote control type radioactive material decontamination apparatus vehicle according to the present embodiment is similar to the occupant type radioactive material decontamination apparatus vehicle. The reduced water feed hose connected to the water reduction treatment apparatus, the washing waste water, and the contaminated dust Connected to the suction device, and connected to the cleaning waste water transfer hose for transporting the suctioned cleaning waste water and contaminated dust to the cleaning waste water cleaning device, the reduced water feed hose and the cleaning waste water transfer hose for reduction. And a cleaning device that brushes the object to be decontaminated while spraying water.

Referring to FIG. 5, the unmanned remote control type radioactive material decontamination apparatus vehicle of this embodiment will be described in detail. This is an unmanned vehicle capable of remote control equipped with a reducing water supply hose 33 and a washing waste water suction hose 34. The operation direction change of the apparatus vehicle is a system in which the command receiving antenna 44 catches a radio command while checking the position with the radioactivity measuring device 42 and the rotatable rotary camera 43 and operates.
Further, the vehicle is provided with a front rotary brush 37 on the front surface and a plurality of bottom rotary brushes 38 on the bottom surface, and the reduced water is jetted from both sides downward from the reduced water injection port 36 to the front rotary brush 37. While the reducing water is jetted toward the floor surface, brushing is performed with a plurality of bottom rotating brushes 38, and cleaning wastewater contaminated by cleaning can be sucked and removed by a suction device 41 having a vacuum suction pipe built therein.

  In addition, the unmanned remote control type radioactive material decontamination apparatus vehicle of this embodiment is provided with a pair of moving wheels 40 on the left and right sides and four auxiliary casters 39 on the front and rear ends. By rotating, it is possible to smoothly rotate and change direction on the spot, and to direct the front brush in the target direction.

  The cleaning and decontamination method for the inside of a structure according to the present invention can reduce the radioactive material of the contamination source in any of a manual method, a method using a passenger type vehicle with a protective device, and a method using an unmanned remote control vehicle. Since the reducing water dissolved in water and dissolved in the radioactive substance is collected and transferred to the treatment apparatus, the diffusion of the contamination does not occur, and the concentration of the contamination in the drainage can be avoided.

<Removal of radioactive material from washing wastewater>
FIG. 3 is a diagram schematically showing a method for decontamination and regeneration of cleaning wastewater contaminated with radioactive substances in the decontamination method according to an embodiment of the present invention.
The decontamination and regeneration of the washing wastewater includes a first adsorption stage, a second adsorption stage, a third adsorption stage, and a microbubble treatment stage.

The suctioned and recovered cleaning wastewater is stored in the cleaning wastewater storage tank 16 through a filtration stage in which coarse particles are filtered by a filter (not shown), and the first adsorption stage for performing the first adsorption stage from the cleaning wastewater storage tank 16. 1 is sent to the adsorption column 18.
The first adsorption stage is a stage in which washing waste water is passed through the first adsorption column in order to adsorb and remove positively charged radioactive substances such as cesium, cobalt, and strontium in the washing waste liquid. May be a column filled with a mixture of clay and alum saturated with hydrogen ions or a column filled with a cation exchange resin saturated with hydrogen ions.

The washing waste water that has finished the first adsorption stage is sent to the second adsorption column 20 for performing the second adsorption stage.
The second adsorption stage is a stage in which a negatively charged radioactive substance such as iodine is passed through the second adsorption column in order to adsorb and remove it. As the second adsorption column, anion exchange saturated with hydroxide ions is performed. A resin packed column 18 is used.

The washing waste water that has finished the second adsorption stage is sent to the third adsorption column 22 for performing the third adsorption stage.
The third adsorption stage is a stage for removing radioactive substances that could not be removed in the first and second adsorption stages, and a column filled with zeolite is used as the third adsorption column.
Zeolite is porous and negatively charged, and the radioactive material is drawn into the porous material and adsorbs the radioactive material very strongly. By passing the washing wastewater through the third adsorption column, the first and second adsorption It is possible to adsorb and remove radioactive substances that could not be removed in stages.

The washing wastewater that has finished the third adsorption stage is sent to the microbubble generation apparatus 24 by the powerful pump 23 in order to perform the microbubble treatment stage.
The microbubble treatment stage is a stage where air microbubbles are generated in the cleaning wastewater from which radioactive substances have been removed to return it to highly biologically active water. The microbubble generator used in this stage is a cavitation method, etc. A well-known thing can be used.

  The reclaimed purified water generated after the microbubble treatment stage is sent to the decontamination purified water tank 25 and can be reused from the water outlet 26.

  As mentioned above, although embodiment of this invention was described in detail, referring drawings, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the technical scope of this invention, it changes variously. It is possible to implement.

DESCRIPTION OF SYMBOLS 1 Floor surface 2 Reduced water injection gun 3 Reduced water feed hose 4 Reduced water outlet 5 Reduction treatment tank 6 Motor 7 Ejector 8 Hydrogen gas supply device 9 Water pump 10 Supply water source 11 Floor cleaning brush 12 Suction port 13 Suction hose 14 Suction device 15 Washing wastewater inlet 16 Washing wastewater reservoir 17 First adsorption column opening / closing valve 18 First adsorption column 19 Second adsorption column opening / closing valve 20 Second adsorption column 21 Third adsorption column opening / closing valve 22 Third adsorption column 23 Micro bubble pump 24 Micro Bubble Generator 25 Decontamination Functional Water Reservoir 26 Purified Water Discharge Port 27 Rotating Brush Device 28 Motor 29 Left / Right Rotating Arm 30 Vertical Front Rotating Support Point 31 Vertical Moving Main Arm 32 Horizontal Directional Support Point 33 Reducing Water Supply Hose 34 Suction Hose 35 Reduced water supply pipe 36 Reduced water jet Mouth 37 front rotary brush 38 bottom rotary brush 39 auxiliary castor 40 wheel 41 suction device 42 radioactivity measuring device 43 rotates the camera 44 command receiving antenna

Claims (4)

A cleaning step of spraying reduced water negatively charged at a potential of −400 mV to −600 mV to a decontamination target contaminated with a radioactive substance, discharging the brush, and brushing the decontamination target;
A cleaning wastewater recovery stage for recovering the cleaning wastewater generated in the cleaning stage;
A filtration step of sending the recovered washing wastewater to a filter to filter coarse solids;
The filtered washing wastewater was passed through a column filled with a mixture of clay and alum saturated with hydrogen ions or a column filled with a cation exchange resin saturated with hydrogen ions to cationize the washing wastewater. A first adsorption stage for adsorbing and removing radioactive material;
A second adsorption step of adsorbing and removing the anionized radioactive material in the washing wastewater by passing the washing wastewater having finished the first adsorption step through a column of anion exchange resin saturated with hydroxide ions;
A third adsorption stage for passing the washing wastewater that has finished the second adsorption stage through a column filled with zeolite to adsorb and remove the radioactive substances remaining in the washing wastewater;
A microbubble treatment step in which the cleaning wastewater that has finished the third adsorption step is treated with air microbubbles to form highly biologically active water, and the inside of the structure contaminated with radioactive material, Cleaning decontamination method. A reduced water feed hose connected to a water reduction treatment device that continuously produces reduced water;
A suction device for sucking cleaning wastewater and contaminated dust;
A cleaning wastewater transfer hose connected to the suction device and transporting the suctioned cleaning wastewater and contaminated dust to a cleaning wastewater cleaning device;
A cleaning device that is connected to the reduced water supply hose and the cleaning wastewater transfer hose and brushes the object to be decontaminated while spraying the reduced water, and has a structure contaminated with radioactive material. Cleaning decontamination equipment vehicle. The cleaning device is supported by an arm that can change the direction of the cleaning brush forward, down, left and right, and includes a reducing water injection device, a rotating brush, and a cleaning waste water vacuum suction port,
The apparatus for cleaning and decontaminating a structure contaminated with a radioactive substance according to claim 2, wherein the apparatus is capable of simultaneously performing injection of reducing water, brushing with a rotating brush, and suction of cleaning wastewater. vehicle.   The cleaning / decontamination apparatus vehicle inside a structure contaminated with a radioactive substance according to claim 2, wherein the cleaning / decontamination apparatus vehicle is an unmanned remote control type vehicle.

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