JP5277481B1 - Decontamination method and decontamination apparatus for contaminated structures with radioactive substances - Google Patents

Abstract

An object of the present invention is to provide a method for effectively cleaning a structure contaminated with radioactive material and preventing re-diffusion of the contaminated material after cleaning.
A surfactant, a potassium salt or an ammonium salt of an inorganic acid, and a cleaning water containing fulvic acid are sprayed or discharged on the object to be decontaminated, washed, and sprayed or discharged on the object to be decontaminated. A step of recovering the washed waste water after washing, a step of coagulating and precipitating radioactive substances contained in the washing waste water, a step of separating the coagulated sediment, and a step of storing the separated coagulated sediment in a storage container [Selection] Figure 1

Description

  The present invention relates to a decontamination method and decontamination apparatus for contaminated structures with radioactive substances, and more particularly, a decontamination method and decontamination apparatus for asphalt or concrete paved roads, sites or buildings contaminated with radioactive substances. About.

  Conventionally, decontamination of asphalt or concrete paved roads, sites, buildings, etc., contaminated with radioactive substances, has been conventionally performed by high-pressure water discharge. The radioactive pollutant penetrates into the contaminated material with the passage of time, and a large amount of water and repeated washing are required to perform sufficient decontamination by washing with simple water. In addition, since the contaminated cleaning wastewater containing radioactive material is not treated or collected, it causes problems such as re-diffusion of radioactive material and the concentration of contamination in specific areas depending on the distribution of drainage channels.

  As one of the decontamination methods for improving the above-mentioned problem, dry ice particles are conveyed and blasted with pressurized air on the surface of a place contaminated with radioactive material, and the surface is peeled off, or the material to be peeled and dry A method for decontaminating radioactive material contaminants has been proposed in which mixed air with ice particles is sucked to collect and collect dust (see Patent Document 1).

  However, the method as described above is effective for target decontamination of radioactive material contaminants where the location of radioactive material is clear, but unspecified radioactive material at large contaminated sites such as paved roads. The decontamination of pollutants was inefficient and lossy.

JP 2002-196097 A

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to effectively clean a structure contaminated with radioactive material, and to re-diffuse the contamination after cleaning. It is to provide a method to prevent.
Another object of the present invention is to provide an apparatus that effectively cleans a structure contaminated with radioactive material and prevents re-diffusion of the contaminated material after cleaning.

  The decontamination method according to one aspect of the present invention made to achieve the above object includes spraying or discharging water on a decontamination target with a surfactant, a potassium salt or an ammonium salt of an inorganic acid, and fulvic acid. Cleaning, spraying or discharging water onto the decontamination object, recovering the cleaning waste water after cleaning, coagulating and precipitating the radioactive material contained in the cleaning waste water, and the coagulation precipitation And a step of storing the separated aggregated precipitate in a storage container.

  It is preferable to have a step of rinsing the decontamination object with water or warm water after the step of spraying or discharging water on the decontamination object and washing.

  It is preferable that the method further includes a step of adsorbing a dissolved radioactive substance in the washing waste water from which the aggregated precipitate has been separated, after the step of separating the aggregated precipitate.

  It is preferable that after the step of adsorbing the dissolved radioactive substance, a step of discharging the washing waste water in which the dissolved radioactive substance is adsorbed on an adsorbent as general waste water is included.

  The inorganic acid potassium salt or ammonium salt is ammonium chloride, ammonium perchlorate, ammonium sulfate, ammonium nitrate, ammonium carbonate, potassium carbonate, potassium hydroxide, potassium permanganate, potassium nitrate, potassium sulfate, potassium chlorate, potassium chloride, It is preferably at least one selected from the group consisting of potassium bromide and potassium iodide.

  The surfactant is pure soap (fatty acid sodium), pure soap (fatty acid potassium), sodium alphasulfo fatty acid, sodium linear alkylbenzene sulfonate, sodium alkyl sulfate, sodium alkyl ether sulfate, sodium alpha olefin sulfonate, alkyl Sodium sulfonate, sucrose fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkanolamide, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, alkylamino fatty acid sodium, alkylbetaine, alkylamine oxide, alkyltrimethyl Selected from the group consisting of ammonium salt, dialkyldimethylammonium salt, lecithin, saponin and casein It is preferable was at least one.

  The storage container for storing the separated adsorbed and aggregated radioactive material preferably has a multiple wall structure.

  The storage container has a two-tank structure of an inner tank and an outer tank, and the outer tank is preferably made of lead.

  It is preferable that the decontamination target is a paved road, a building, a house, a drainage ditch, an asphalt, or a concrete laid site.

  A decontamination apparatus according to an aspect of the present invention, which has been made to achieve the above object, discharges cleaning water containing fulvic acid, a potassium salt or an ammonium salt of an inorganic acid, and a surfactant to an object to be decontaminated. Water discharging means for collecting, washing means for collecting the washing water discharged to the decontamination object, coagulating sedimentation means for coagulating and precipitating the radioactive substance contained in the collected washing water, and coagulating sediment of the radioactive substance It is characterized by having a filtration / separation means for filtering and separating, and an adsorption means for adsorbing the dissolved radioactive substance contained in the filtered washing wastewater to the adsorbent.

  The adsorbing means is preferably constituted by a replaceable cartridge system in which an adsorbent is filled in the container.

  According to the decontamination method of the present invention, in the cleaning of a structure contaminated with a radioactive substance, the radioactive substance can be washed with a small amount of water in a short time, and the washing wastewater is recovered together with the washing. The effect is that it does not cause the diffusion of substances or the concentration of contamination in specific areas.

  According to the decontamination apparatus of the present invention, since radioactive substances are separated and removed from contaminated cleaning wastewater, it can be discharged as general wastewater containing no radioactive substances after treatment.

  According to the decontamination apparatus of the present invention, it is possible to effectively decontaminate a structure contaminated by radioactive substances, and by collecting the removed contaminants, the radioactive substances can be re-diffused or distributed to specific areas. Concentration of contamination can be prevented.

It is a figure for demonstrating the decontamination method by one Embodiment of this invention. It is a figure for demonstrating the structure of the decontamination apparatus by one Embodiment of this invention.

Hereinafter, the specific example of the form for implementing the decontamination method of the contaminated structure by the radioactive substance of this invention is demonstrated in detail.
In the method for decontamination of a contaminated structure with a radioactive substance according to the present invention, the structure to be decontaminated is sprayed or sprayed with cleaning water containing fulvic acid, an inorganic acid potassium salt or ammonium salt, and a surfactant. In addition to decontamination of contaminated structures with radioactive substances, the cleaning wastewater used for decontamination is recovered, and the radioactive substances in the cleaning wastewater are separated and removed so that they can be discharged as general wastewater. It also decontaminates washing wastewater.

  As decontamination targets of the decontamination method of the present invention, pavement (asphalt or concrete) roads, drainage grooves, houses, buildings, etc. contaminated with radioactive substances are preferable. It is preferable from the point of recovery that the radioactive material is a decontamination object of a material that does not.

FIG. 1 is a diagram for explaining a decontamination method according to an embodiment of the present invention.
The first stage of the decontamination method according to the present embodiment is a stage (S1) of spraying washing water containing a potassium salt or ammonium salt of a fulvic acid and an inorganic acid and a surfactant on a decontamination object or discharging water.

The fulvic acid contained in the wash water has a strong complex-forming ability with radioactive metals and heavy metals, and by including it in the wash water, it is possible to effectively clean the structure due to radioactive substances. .
The amount of fulvic acid to be contained in the washing water is usually used in the range of 0.01 to 3% by weight with respect to water.

  The inorganic acid potassium salt or ammonium salt contained in the washing water together with the fulvic acid has the function of raising the cesium ion, which is a contaminating component, to the surface. By combining it with the fulvic acid, the structure is more effective in contaminating the structure with radioactive materials. Can be cleaned.

  The negative charge of clay mineral components, such as materials contaminated with radioactive material, makes the cesium ion “fixed” very strongly and cannot be easily replaced by other cations. A clay mineral having such properties is called a 2: 1 type layered silicate, and thin sheet-like layers are stacked and have a negative charge between the layers. Where there is a negative charge between the layers of 2: 1 type layered silicate, it looks like a hole of just the right size to confine cesium ions. This hole is just the right size to confine potassium ions and ammonium ions in addition to cesium ions. Also, once cesium ions are fixed at this location, it is not easy to remove them from the location, but if ionic ions of fulvic acid, potassium ions, or ammonium ions are present at a certain concentration, cesium ions can be expelled. it can.

Examples of such inorganic acid potassium salts or ammonium salts include ammonium salts such as ammonium chloride, ammonium perchlorate, ammonium sulfate, ammonium nitrate, ammonium carbonate, potassium carbonate, potassium hydroxide, potassium permanganate, potassium nitrate, sulfuric acid. Examples include potassium salts such as potassium, potassium chlorate, potassium chloride, potassium bromide, potassium iodide.
The amount of the inorganic acid potassium salt or ammonium salt to be contained in the washing water is usually in the range of 0.01 to 1% by weight with respect to water.

  The cleaning water of this embodiment contains a surfactant in addition to fulvic acid, potassium salt or ammonium salt of inorganic acid. By including a surfactant, washing water containing potassium or ammonium salts of fulvic acid and inorganic acid can easily spread on the surface of the contaminant, and also easily penetrate into the interior of the contaminant. It is possible to more effectively clean the contamination with radioactive materials.

Examples of surfactants that can be included in the wash water include pure soap (fatty acid sodium), pure soap (fatty acid potassium), alphasulfo fatty acid sodium, sodium linear alkylbenzene sulfonate, sodium alkyl sulfate, and alkyl ether. Sodium sulfate, sodium alpha olefin sulfonate, sodium alkyl sulfonate, sucrose fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkanolamide, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, sodium alkylamino fatty acid Alkyl betaines, alkyl amine oxides, alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, etc. , Lecithin as a natural surfactant, saponin, etc. casein.
The amount of the surfactant to be contained in the washing water is usually used in the range of 0.01 to 0.5% by weight with respect to water.

In the stage of spraying the cleaning water of this embodiment on the object to be decontaminated or washing with water, the cleaning water contains a component that facilitates the removal of contamination by radioactive substances. It is sprayed at low pressure without discharging water at high pressure, and a sufficient amount of washing water is demonstrated with a small amount of washing water compared to normal water washing.
If the object to be decontaminated is a paved road or a drainage ditch, it is preferable that the contaminants adhere, and it is preferable to increase the water discharge pressure of the washing water. Effective cleaning can be performed.

It is preferable to perform a step (S2) of spraying rinse water that does not include fulvic acid, potassium salt or ammonium salt of inorganic acid and surfactant after the step of spraying and discharging the cleaning water, and cleaning including radioactive substances The decontamination effect can be enhanced by washing away the water, and the diffusion of the contamination can be prevented by collecting the rinse water together with the washing water in the next stage.
In addition, when the decontamination target is firmly adhered to a pollutant such as a paved road, it is preferable to use warm water as the rinse water in terms of the cleaning effect of the radioactive material.

Following the washing / rinsing water spraying / water discharge washing stage, washing waste water and rinse waste water are collected (S3). It is preferable to start the recovery stage of the washing waste water and the rinse waste water almost simultaneously with the start of the washing water spray and the rinse water spray. This is to prevent the radioactive material from diffusing to other places and re-adsorbing to the cleaning object.
Further, the washing waste water and the rinse waste water may be collected after spraying and discharging the cleaning water and after spraying and discharging the rinse water, and the cleaning water and the rinse water may be collected in a lump.

In the recovery stage of the washing waste water and the rinse waste water, it is preferable to collect by performing a scattering prevention treatment such as a guide plate at a place where the spraying and discharging are performed. The method of recovery is not particularly limited, but it is preferable to recover the sludge containing radioactive substances using a suction device used in a city cleaner (mobile large vacuum cleaner), a high-pressure suction vehicle, or the like.
Further, depending on the shape of the structure to be decontaminated, the cleaning waste water and the rinse waste water may be treated so as to flow into the side groove using a guide plate or the like, and recovered at the downstream side of the side groove.

Next, a flocculant is added to the recovered washing waste water and rinse waste water to coagulate and precipitate the radioactive substance (S4). Examples of the flocculant used include inorganic flocculants such as aluminum sulfate and polyaluminum chloride, inorganic polymer flocculants such as activated silicic acid and polysilica iron, sodium alginate, chitin / xant, and bio-derived organisms such as seaweed. Natural organic polymer flocculants such as those based on cationic, anionic and nonionic synthetic organic polymer flocculants, and these can be used alone or in combination.
By using a flocculant having a high adsorptivity of radioactive substance, for example, trade name Bino Sfrock (manufactured by Japan Biomass Research Institute Co., Ltd.) as the flocculant, the recovery efficiency of the radioactive substance can be increased.
In the present invention, the washing water contains a radioactive substance and a highly adsorbing fulvic acid, so that not only the cleaning effect of contamination by the radioactive substance can be enhanced, but also the dissolved radioactive substance is adsorbed to the fulvic acid. Since it can be agglomerated together with radioactive substance-containing dust during agglomeration, the recovery efficiency of the radioactive substance can be increased.

  Next, the solid content containing the radioactive material which has been aggregated and precipitated is separated (S5). As a solid-liquid separation method, general methods such as gravity sedimentation treatment, centrifugal separation treatment, and membrane treatment can be used.

  The solid content (sludge) subjected to solid-liquid separation is stored in a radioactive material storage container (S6). As a radioactive material storage container, a radioactive waste storage container having a multi-walled container wall is preferable, which is composed of a two-tank structure of an inner tank and an outer tank, the outer tank is made of lead, and has a double structure gap. It is more preferable if it can be filled with a radiation absorbing material such as water.

The washing waste water and rinse waste water from which the solid content has been removed are preferably passed through an adsorbent packed in a column or the like in order to remove radioactive substances dissolved in the water (S7). As a radioactive material adsorbent, commonly used adsorbents such as zeolite particles, activated carbon particles and ion exchange resins can be used, and the surface is treated with a substance such as fulvic acid that has high adsorptivity to radioactive materials. It is preferable to use the adsorbent.
The cleaning wastewater treated with the adsorbent is clean water containing almost no radioactive substance, and can be discharged as general wastewater or reused as cleaning water and rinse water.

FIG. 2 is a diagram for explaining a configuration of a decontamination apparatus according to an embodiment of the present invention.
The decontamination apparatus shown in FIG. 2 includes a water discharge unit 11 having a water discharge nozzle 11A for discharging cleaning water containing a fulvic acid and a potassium or ammonium salt of an inorganic acid and a surfactant to a decontamination target. A recovery unit 12 having a recovery nozzle 12A for recovering the cleaning water discharged to the decontamination target, an aggregation precipitation unit 13 for aggregating and precipitating the radioactive substance contained in the recovered cleaning water, and a radioactive substance It has the solid-liquid separation part 14 which carries out solid-liquid separation of the aggregate deposit, and the adsorption | suction part 15 which adsorb | sucks the dissolved radioactive substance contained in the washing waste water solid-liquid-separated by adsorption agent.

  The water discharge unit 11 includes a water discharge nozzle 11A, a high-pressure cleaning pump, a cleaning water tank, and a rinsing water tank. It is preferable that the water discharge nozzle 11 </ b> A can be connected to a connecting hose or combined with a cleaning brush so as to correspond to the form of the decontamination target.

The collection unit 12 includes a collection nozzle 12A, a collection tank for a collection object, and a blower for forming a negative pressure. The collection nozzle 12A is combined with a connection hose and a cleaning brush so as to correspond to the form of the object to be decontaminated. Is preferably possible.
The collection unit 12 preferably has a transfer unit such as a pump for transferring the waste water collected in the receiver tank to the next process, and the transfer unit is preferably capable of pumping the contents.

  The coagulation sedimentation unit 13 includes a coagulation sedimentation tank and a transfer unit to the separation unit 14 in the next step, and the coagulation sedimentation tank includes a coagulant addition unit and an agitation unit.

The solid-liquid separation unit 14 includes solid-liquid separation means, and as the solid-liquid separation means, gravity sedimentation treatment, coagulation sedimentation treatment, pressurized flotation treatment, centrifugal separation treatment, membrane treatment, etc. can be used. Treatment or continuous centrifugal dehydration is preferred from the viewpoint of treatment speed and separation solid content.
The sludge containing the radioactive material generated from the solid-liquid separation unit 14 is separately stored in a storage container for the treatment of the radioactive material.

The adsorption unit 15 has a column filled with an adsorbent, and the column is preferably a replaceable cartridge type.
The treated water that has passed through the adsorbing unit 15 has a radioactive substance reduced to a concentration below the standard, and is returned to the rinse water tank for reuse.

  Hereinafter, examples of decontamination on asphalt surfaces and drainage channels contaminated with radioactive materials by the decontamination method according to an embodiment of the present invention will be described.

<Decontamination of asphalt surface>
Prepare cleaning water containing 0.5% by weight of fulvic acid, 0.05% by weight of potassium carbonate and 0.1% by weight of sodium alkyl sulfate as a surfactant and spray it at a rate of 1 l / m ² with a drug pump. Washing water was aspirated while brushing with a cleaner (mobile large vacuum cleaner). Warm water (50 ° C.) rinse water was sprayed from the rear of the city cleaner at a discharge rate of 10 l / min, and the rinse water was sucked with a high-pressure suction vehicle equipped with an FRV (glass fiber reinforced PVC plate) attachment. The recovered washing water and rinsing water were transferred to a tank, and 0.1 g / liter of polyaluminum chloride (PAC) was added as a flocculant for coagulation sedimentation. The aggregated sediment is solid-liquid separated with a small centrifuge, the sludge containing radioactive material is stored in a double-walled storage container, and the waste water after solid-liquid separation passes through an adsorption column packed with zeolite, Return to rinse water tank. The radiation dose reduction rate on the asphalt surface by this cleaning was 90 to 95%.

<Decontamination of drains>
Wash water similar to that used for decontamination of the asphalt surface by attaching a special nozzle to the high pressure rubber hose of the Achumat high pressure sewage pipe washing car (water discharge amount: 234.7 l / min) and washing from the nozzle. The mud etc. of the drainage ditch was agitated and transferred downstream by jetting water, and the mud etc. flowing downstream was sucked with a high-pressure suction vehicle. The same amount of the flocculant used for decontamination of the asphalt surface was added to the washing water collected by the high-pressure suction vehicle per liter for coagulation precipitation. The coagulated sediment is solid-liquid separated with a small turbid water treatment facility, sludge containing radioactive material is stored in a double-walled storage container, and the waste water after solid-liquid separation is generally passed through an adsorption column packed with zeolite. It was discharged as waste liquid. The radiation dose reduction rate of the drainage ditch was 90%.

DESCRIPTION OF SYMBOLS 10 Decontamination apparatus 11 Water discharge part 11A Water discharge nozzle 12 Recovery part 12A Recovery nozzle 13 Coagulation sedimentation part 14 Solid-liquid separation part 15 Adsorption part

Claims (11)

Spraying or discharging water containing fulvic acid, potassium salt or ammonium salt of inorganic acid and a surfactant on a decontamination object, and washing;
Recovering washing waste water after spraying or discharging water to the decontamination object and washing;
Coagulating and precipitating radioactive material contained in the washing waste water;
Solid-liquid separation of the aggregated precipitate;
Storing the separated aggregated precipitate in a storage container;
A method for decontaminating a contaminated structure with a radioactive substance, comprising:   The radioactive substance contamination according to claim 1, further comprising a step of rinsing the decontamination object with water or warm water after the step of spraying or discharging the cleaning water on the decontamination object and washing. Decontamination method for structures.   The radioactive substance according to claim 1, further comprising a step of adsorbing a dissolved radioactive substance in the washing waste water from which the aggregated precipitate has been separated to an adsorbent after the step of separating the aggregated precipitate. Decontamination method for contaminated structures.   4. The radioactive substance-contaminated structure according to claim 3, further comprising, after the step of adsorbing the dissolved radioactive substance, discharging the washing waste water in which the dissolved radioactive substance is adsorbed on an adsorbent as general waste water. Decontamination method.   The inorganic acid potassium salt or ammonium salt is ammonium chloride, ammonium perchlorate, ammonium sulfate, ammonium nitrate, ammonium carbonate, potassium carbonate, potassium hydroxide, potassium permanganate, potassium nitrate, potassium sulfate, potassium chlorate, potassium chloride, 5. The method for decontaminating a contaminated structure with a radioactive substance according to claim 1, wherein the decontamination structure is at least one selected from the group consisting of potassium bromide and potassium iodide.   The surfactant is pure soap (fatty acid sodium), pure soap (fatty acid potassium), alpha sulfo fatty acid ester sodium, linear alkylbenzene sulfonate sodium, alkyl sulfate sodium, alkyl ether sodium sulfate, alpha olefin sulfonic acid sodium salt, Sodium alkyl sulfonate, sucrose fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkanolamide, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, alkylamino fatty acid sodium, alkyl betaine, alkyl amine oxide, alkyl Group consisting of trimethylammonium salt, dialkyldimethylammonium salt, lecithin, saponin, casein Decontamination method contaminated structures by the radioactive material according to claim 1, wherein the at least one member selected Ri.   The method for decontaminating a contaminated structure with a radioactive substance according to claim 1, wherein the storage container for storing the separated aggregated radioactive substance deposit has a multiple wall structure.   The method for decontaminating a contaminated structure with a radioactive substance according to claim 7, wherein the storage container has a two-tank structure of an inner tank and an outer tank, and the outer tank is made of lead.   The method for decontamination of a contaminated structure with a radioactive substance according to claim 1, wherein the decontamination target is a paved road, a building, a house, a drainage ditch, an asphalt, or a concrete laid site. A water discharge means for discharging cleaning water containing a fulvic acid, a potassium salt or an ammonium salt of an inorganic acid, and a surfactant to a decontamination object;
Recovery means for recovering the wash water discharged to the decontamination object;
A coagulating sedimentation means for coagulating and precipitating the radioactive material contained in the recovered washing water;
A solid-liquid separation means for solid-liquid separation of the aggregated precipitate of the radioactive substance;
An adsorbing means for adsorbing the dissolved radioactive substance contained in the washing wastewater separated into solid and liquid to an adsorbent;
An apparatus for decontamination of a contaminated structure with a radioactive substance, comprising:   The apparatus for decontaminating a contaminated structure with a radioactive substance according to claim 10, wherein the adsorbing means is constituted by a replaceable cartridge system in which an adsorbent is filled in a container.

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