JP6046372B2 - Decontamination composition and decontamination method - Google Patents

Description

  The present invention relates to a decontamination composition and a decontamination method, and more specifically to a decontamination composition and a decontamination method for radioactive contaminants containing radioactive substances.

  The Tokyo Electric Power Fukushima Daiichi NPS, which was damaged by the unprecedented Great East Japan Earthquake in March 2011, was damaged by the earthquake and tsunami. It developed into a serious nuclear accident involving the accident (Fukushima Daiichi nuclear power plant accident).

  In particular, soil, buildings, roads, forests, debris, and incineration ash are contaminated by radioactive materials due to the leakage of large amounts of radioactive materials, and decontamination methods that remove radioactive materials from these radioactive contaminants are the most important in disaster areas. It is one of the important matters.

  Here, for example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-078336), a radioactive substance adhering to a decontamination target having a complicated shape is also contaminated with oil, coating film, dust, and oxide film. It is intended to provide a decontamination method capable of obtaining a sufficient decontamination effect even for radioactive wastes having different pollution forms, etc., and solving the problem of secondary waste, and a decontamination apparatus used therefor Technology has been proposed.

  That is, in Patent Document 1, an object for decontamination generated from a nuclear facility is processed by an alkali decontamination step using an alkali decontamination agent and an acid decontamination step using an acid decontamination agent that combines an organic acid and an inorganic acid. There has been proposed a method for removing a radioactive substance characterized by being subjected to a decontamination treatment in combination with

  Patent Document 2 (Japanese Patent Laid-Open No. 2004-286471) provides a radioactive chemical decontamination method and apparatus having a high decontamination rate, low corrosion of the decontamination apparatus, and a small amount of secondary waste. The intended technology has been proposed.

  That is, in Patent Document 2, the decontamination object contaminated with a radioactive substance is immersed in a decontamination liquid composed of formic acid and oxalic acid, and the potential of the decontamination object is lowered to a corrosive region, thereby decontamination object. A technique has been proposed in which the metal ion in the decontamination solution is separated and removed by a cation exchange resin.

JP 2006-078336 A JP 2004-286471 A

  However, in the alkaline decontamination agent and the decontamination liquid composed of formic acid and oxalic acid provided in the prior arts such as Patent Document 1 and Patent Document 2, radioactive materials such as soil, buildings, roads, forests, rubble and incineration ash are used. Radioactive materials cannot always be efficiently removed from pollutants, and it cannot be said that they contain naturally-friendly components, and there is still room for improvement.

  Accordingly, an object of the present invention is to provide a decontaminating agent composition that can efficiently remove radioactive substances from radioactive contaminants such as soil, buildings, roads, forests, rubble and incineration ash, and is composed of naturally-friendly components. And a decontamination method using the decontaminant composition.

  In order to solve the above-described problems, the present inventors have repeatedly studied earnestly, and as a result, a decontaminant composition that can efficiently remove radioactive substances from radioactive contaminants and is composed of naturally-friendly components. In order to obtain this, if a component derived from the genus Troy's genus, which is a natural component, is used, the component derived from the genus Troy's genus can absorb and reliably capture the radioactive material, and efficiently remove the radioactive material from the radioactive contaminants. As a result, the present invention has been completed.

  That is, this invention provides the decontaminant composition of the radioactive pollutant containing the radioactive substance characterized by including the component derived from the mallow family Troloae mushroom.

  According to the decontaminating agent composition of the present invention having such a structure, the component derived from the genus Troy's genus Troyae adsorbs and captures the radioactive material contained in the radioactive contaminant, so that the radioactive material is removed from the radioactive contaminant. Can be removed efficiently. In addition, since the component derived from the genus Troeroaoi is a natural component, the decontamination composition of the present invention is naturally gentle.

  The decontamination composition of the present invention preferably further contains a keratin hydrolyzate.

  According to the decontamination composition of the present invention having such a configuration, the keratin hydrolyzate adsorbs and captures the radioactive substance contained in the radioactive pollutant together with the components derived from the genus Troy's family, from the radioactive contaminant. Radioactive material can be removed more efficiently. Further, since the keratin hydrolyzate is a protein, the decontamination composition of the present invention is naturally gentle.

  The present invention also provides a decontamination method for removing the radioactive substance from the radioactive contaminant by mixing the decontaminant composition with the radioactive contaminant containing the radioactive substance in, for example, an aqueous phase. It is.

  According to the decontamination method of the present invention having such a configuration, the component derived from the genus Troy's family, adsorbs and captures the radioactive substance contained in the radioactive contaminant, so that the radioactive substance is efficiently removed from the radioactive contaminant. It can be removed and a drainage containing radioactive material can be obtained. In addition, since the component derived from the genus Troy's family is a natural component, the decontamination composition of the present invention is naturally gentle.

  In the decontamination method of the present invention, it is preferable to inject a gas into the mixture of the decontaminant composition and the radioactive contaminant.

  According to the decontamination method of the present invention having such a configuration, bubbles are generated in the mixture of the decontaminant composition and the radioactive contaminants by gas injection, and the contaminants contained in the radioactive contaminants by the bubbles. (For example, if the radioactive contaminant is soil, it can be classified and separated by foam that floats clay and silt), and the size such as particle size, which is considered difficult to decontaminate, is small. Radioactive materials can be more reliably removed from radioactive contaminants (in this case silt and clay). Thereby, the volume after the decontamination process of a radioactive contaminant can be made small, and it is suitable for volume reduction of the radioactive contaminant after a decontamination process. Note that bubbles generated after gas injection may be collected, and the bubbles may be physically or chemically defoamed using a keratin hydrolyzate.

  In the decontamination method of the present invention, the decontaminant composition is mixed with radioactive contaminants to remove radioactive substances from the radioactive contaminants, and then the radioactive contaminants are further washed with a surfactant. preferable.

  According to the decontamination method of the present invention having such a configuration, radioactive contaminants that have undergone decontamination treatment with a single component derived from the genus Troy's family, or a combination of a genus Troy's species and a keratin hydrolyzate When the radioactive substance remains on the surface, the residual radioactive substance can be washed away, and the radioactive substance can be more efficiently removed from the radioactive contaminant.

  In the decontamination method of the present invention, it is preferable that a flocculant is further added to the waste liquid containing the radioactive substance obtained by the decontamination method, and the radioactive substance is aggregated and separated.

  According to the decontamination method of the present invention having such a configuration, radioactive substances can be agglomerated and separated and concentrated from radioactive contaminants, and the volume reduction efficiency of radioactive contaminants is high. Furthermore, since the effluent after the coagulation sedimentation treatment does not contain radioactive substances, it can be safely discharged into public water areas, and it can be said that the volume reduction efficiency of radioactive contaminants is high.

  In the decontamination method of the present invention, it is preferable that the flocculant contains a component derived from the genus Troy's family.

  According to the decontamination method of the present invention having such a configuration, the radioactive substance contained in the drainage can be efficiently agglomerated and separated, and the coagulant remains in the drainage more because it is aggregated by natural components. Even if it is, it can be safely discharged into public waters and is friendly to nature.

  According to the present invention, it is possible to efficiently remove radioactive substances from radioactive contaminants such as soil, buildings, roads, forests, rubble and incineration ash, and a decontaminating agent composition composed of naturally-friendly components, And a decontamination method using the decontamination composition.

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

(1) Decontaminating agent composition The decontaminating agent composition of this invention is characterized by including the radioactive substance characterized by containing the component derived from the genus Troyaeaceae as an essential component. The component derived from the genus Troloaoi is a component derived from plants such as anthracnose, dicotyledonous plant, mallow, mallow, abelmoschus, okra and ryukyuroarooi.

  The component derived from the genus Troy's genus is a powdered product obtained by drying and pulverizing a plant classified into the genus Troy's genus, such as a powdery product (Okra-derived component) obtained by drying and pulverizing okra. In addition to pectin, galactan, araban, mucin, etc., it contains okra components such as minerals, calcium, potassium, vitamins A, B1, B2, and C.

  If the dried and pulverized component derived from the genus Troy's family is used as the component of the genus Troy's family, the surface area of the genus Troy's family will increase, and the decontamination with the decontamination composition of the present invention. It is easier to obtain a dyeing effect.

  More specifically, it is desirable that the particle size of the powdery body forming the component derived from the genus Troy's family is 18 mesh or less, and more preferably 40 mesh or less. The particle size of the component of the genus Troy's family is preferably as fine as possible in consideration of the degree of dispersion and reactivity when the decontaminant composition is introduced into the radioactive contaminant to be treated. Further, the form to be used may be a powder or an aqueous solution (or dispersion) in which a powder is dissolved (or dispersed) in water.

  In addition, the “component from the genus Troy's family” in the present invention refers to the epidermis part of a plant belonging to the genus Troy's family, the fiber wall that forms the inner wall in the plant (hereinafter also referred to as “inner fiber wall”) and the seed. Either of them may be dried and pulverized together, or may be selected by combining any of these and dried and pulverized.

  As will be described later, the component derived from the genus Troy's family has the same effect on all of the epidermis part, inner fiber wall and seed, but is classified into the genus Troy's family such as Okra which is easy to manufacture and raw materials. From the standpoint of effectively utilizing the plant to be used, it is preferable to use a plant obtained by drying and pulverizing all parts of the plant belonging to the genus Troyceae as a component derived from the genus Troyceae.

  In the decontamination composition of the present invention, the content of the component from the genus Troy's family can be adjusted as appropriate according to the amount of radioactive substances contained in the radioactive contaminant, for example. From the viewpoint of preparation and storage stability, for example, when the radioactive contaminant is soil, the amount of radioactive substance contained in a sample obtained by dispersing the soil in water is measured in advance. Correspondingly, it may be selected appropriately.

  Moreover, it is preferable that the decontaminant composition of this invention contains a keratin hydrolyzate in addition to the component derived from the genus Troyceae which is an essential component.

  Because keratin hydrolyzate can adsorb and capture radioactive substances contained in radioactive pollutants, together with components derived from the genus Trolloi, from mallow, and more efficiently remove radioactive substances from radioactive contaminants, because keratin hydrolysates are proteins This decontamination composition of the present invention is also naturally gentle.

  The content of the keratin hydrolyzate in the decontaminating agent composition of the present invention is 1 to 100,000 times the mass of the component derived from the genus Troarooai from the viewpoint of foamability, adsorption ability of radioactive substances, and economy. Any degree is acceptable.

  The decontamination composition of the present invention is a hydrocarbon surfactant, foaming aid, foam stabilizer, pH adjuster, rust preventive, antiseptic, foam control agent, as long as the effects of the present invention are not impaired. An optional component such as an alkaline agent may be included.

(2) Decontamination method Next, the decontamination method of this invention is demonstrated. The decontamination method of this invention removes a radioactive substance from a radioactive contaminant by spraying or mixing the said decontaminant composition to the radioactive contaminant containing a radioactive substance.

  It is also possible to mix radioactive contaminants such as soil, buildings, roads, forests, rubble and incinerated ash as they are with the above decontaminant composition, and after crushing these radioactive contaminants as finely as possible (soil and incinerated ash etc. It is also possible to disperse in water and obtain an aqueous dispersion of radioactive contaminants, and then mix with the decontaminant composition.

  By this mixing, the radioactive substance contained in the radioactive pollutant is adsorbed and captured by the component derived from the genus Trolloiaceae contained in the decontamination composition, and the radioactive pollutant is efficiently decontaminated.

  In the decontamination method of the present invention, it is preferable to inject a gas into the mixture of the decontaminant composition and the radioactive contaminant. As described above, bubbles are generated in the mixture of the decontaminating agent composition and the radioactive contaminants by gas injection, and the contaminants contained in the radioactive contaminants can be floated and classified by the bubbles (for example, radioactive If the pollutant is soil, it can be classified and separated by foam that floats up clay and silt), and small-sized radioactive pollutants (in this case silt and organic matter) that are difficult to decontaminate This is because radioactive substances can be more reliably removed from. Thereby, the volume after the decontamination process of a radioactive contaminant can be made small. Note that bubbles generated after gas injection may be collected, and the bubbles may be physically or chemically defoamed using a keratin hydrolyzate.

  Examples of the gas injection method include a method called bubbling or aeration. Further, as the gas injection amount, the flow rate per minute is, for example, about 0.1 to 100 times the volume of the processed product from the viewpoint of the processing work load, the scale of the processing apparatus, and the economy. Good.

  In the decontamination method of the present invention, it is preferable that the decontaminant composition is mixed with radioactive contaminants to remove radioactive substances from the radioactive contaminants, and then the radioactive contaminants are further washed with a surfactant. . Decontamination treatment as described above, with a component derived from the genus Troy's family, a combination of a genus Troy's genus and a keratin hydrolyzate, or a combination of a genus Troy's and keratin hydrolyzate and gas This is because when the radioactive substance remains in the radioactive contaminant subjected to the above, the residual radioactive substance can be washed away, and the radioactive substance can be more efficiently removed from the radioactive contaminant.

  Here, as the surfactant that can be used in the present invention, conventionally known surfactants can be employed as long as the effects of the present invention are not impaired. That is, the surfactant is one or more interfaces selected from known surfactants such as amphoteric surfactants, anionic surfactants, cationic surfactants, and nonionic surfactants. It may contain an activator, and its liquidity may be basic, acidic, or neutral.

  As the surfactant, it is possible to employ an alkylamine oxide which is a zwitterionic surfactant, an alkylamino fatty acid sodium, an alkylbetaine, or the like. Similarly, surfactant components include fatty acid sodium and fatty acid potassium, which are anionic surfactants, alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, nonionic surfactants, which are cationic surfactants. Certain polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and the like can be employed. In addition to the surfactant as described above, the surfactant component includes a foaming aid, a foam stabilizer, a pH adjuster, a rust inhibitor, an antiseptic, a foam adjuster, an alkali agent, and the like. May be.

  The amount of the surfactant used may be 0.05 to 10% with respect to the object to be cleaned from the viewpoint of cleaning performance and economy.

  Moreover, in the decontamination method of this invention, it is preferable to add a flocculant to the waste liquid containing the radioactive substance obtained by the said decontamination method, and to aggregate and isolate a radioactive substance by aggregation. As described above, radioactive substances can be aggregated and concentrated from radioactive contaminants, and the volume reduction efficiency of radioactive contaminants is increased. Furthermore, since the drained liquid after the aggregation and precipitation treatment does not contain radioactive substances, This is because it can be safely discharged into public water areas, and this also has a high volume reduction efficiency of radioactive contaminants.

  In this case, it is preferable that the flocculant contains a component derived from the genus Troy's family. As described above, radioactive substances contained in the drainage can be efficiently agglomerated and separated, and because of aggregation by natural components, even if the flocculant remains in the drainage, it is safely discharged into public waters. Because it is possible and nature friendly.

  It is also possible to use an aggregating agent other than the component derived from the genus Troy's genus, and it is also possible to use an aggregating agent comprising a component derived from the genus Troy's genus and an ingredient other than the genus Troy's is there.

  As the aggregating agent other than the components derived from the genus Troy's family, conventionally known aggregating agents can be used as long as the effects of the present invention are not impaired, and an aggregating aid may be used in combination.

As the flocculant, a flocculant containing a polyvalent metal salt or a polymer flocculant can be preferably used. The polyvalent metal salt that can be used as the aggregating agent can employ a polyvalent metal salt such as aluminum (Al), iron (Fe), magnesium (Mg), calcium (Ca), For example, aluminum sulfate (sulfuric acid band; Al ₂ (SO ₄ ) ₃ · nH ₂ O) (Japanese Industrial Standards standard number JISK1423), polyaluminum chloride (PAC; Al ₂ (OH) _m Cl _6-m ), etc. are suitable. It is possible to use.

  In addition, the polymer flocculant may be classified into any of the attributes of cationic, anionic and nonionic, and includes a carboxyl group, an amide group, a sulfone group in a water-soluble organic substance of an acrylic polymer. And the like can be suitably used as the flocculant component.

  The flocculant is composed of one or more substances selected from polyvalent metal salts such as aluminum sulfate (sulfuric acid band) and polyaluminum chloride, and one or more substances. May be included as a main component and other substances may be included as subcomponents. Similarly, the flocculant includes the above-described polymer flocculant combined with one or more substances, one or more substances as a main component, and other substances as subcomponents. It may be a thing. Further, the flocculant component may include both a flocculant composed of a polyvalent metal salt and a polymer flocculant.

As the aggregation aid, an aggregation accelerator or a pH adjuster can be used. Specifically, as the coagulation assistant component, silicate clay that functions as an aggregation accelerator, other active silicic acid, sodium alginate, bentonite, powdered activated carbon, and the like can be suitably used. Silicate clay is mainly composed of silicon dioxide (SiO ₂ ), aluminum oxide (alumina) (Al ₂ O ₃ ), sodium oxide (Na ₂ O), iron oxide (Fe ₂ O ₃ ), calcium oxide ( CaO), potassium oxide (K ₂ O), magnesium oxide (MgO), water (H ₂ O) and the like.

As the silicate clay, those containing the above components in various blending ratios can be used. For example, silicon dioxide (SiO ₂ ) is 72.96% and aluminum oxide (Al ₂ O ₃ ) is 9.92%. Sodium oxide (Na ₂ O) 4.98%, iron oxide (Fe ₂ O ₃ ) 4.95%, calcium oxide (CaO) 3.27%, potassium oxide (K ₂ O) 0.13 %, Magnesium oxide (MgO) trace and moisture (H ₂ O) containing 3.81% can be suitably used. Specifically, the product name “Million” manufactured by Soft Silica Co., Ltd. can be suitably used for the silicate clay.

  Moreover, as the coagulation aid, a basic substance that functions as a pH adjuster, an acidic substance, or the like can be preferably used. As the basic substance, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate and the like can be suitably used. In addition, sulfuric acid, carbonic acid, hydrochloric acid and the like can be suitably used as the acidic substance. The agglomeration aid component is composed of a combination of one or more substances selected from the basic substances and acidic substances described above, or one or more substances as a main component and the other components as auxiliary substances. It may be included as a component.

  Here, FIG. 1 is a figure for demonstrating one Embodiment of the decontamination method of this invention. As shown in FIG. 1, when soil (contaminated soil) as a radioactive pollutant is subjected to decontamination treatment, first, the contaminated soil is stirred into water in a treatment container to form an aqueous dispersion, where decontamination is performed. The agent composition is charged.

  Next, in the aqueous dispersion, clay and silt are naturally separated, and gas is injected into the aqueous dispersion (bubbling or aeration). Thereby, the clay part (radioactive contaminant with a large size such as a particle size) and the radioactive contaminant with a small size such as a silt partial particle size) in the contaminated soil are more reliably floated and separated by bubbles. The silt part floated and separated together with the foam overflows from the processing container and moves to the adjacent second processing container.

  In this second processing container, a silt portion, which is a large part of radioactive contaminants containing radioactive substances, is stored, and the above-mentioned flocculant is added thereto and stirred. By this agitation, the radioactive substance contained in the silt portion is agglomerated and separated, and the wastewater as the drainage does not contain the radioactive substance and can be drained as it is.

  Moreover, although keratin hydrolyzate has foaming performance, it can be set as the performance which makes the foam after foaming foam easily or defoaming easily by setting the conditions. In addition, in order to easily defoam, if a method of defoaming with a mechanical structure such as a metal plate or a wire mesh or a method of chemically crushing is used, it can be further liquefied more easily.

  Below, the experiment example containing the Example about a decontaminant composition mentioned above and the decontamination method using the same, and a comparative example is demonstrated.

  The radiation dose obtained by decontamination of the soil contaminated with radioactivity with each decontamination composition was measured. Moreover, when it wash | cleaned by surfactant after decontaminating with a decontaminant composition, the radiation dose at the time of carrying out the water washing process after that was also measured. Specifically, the experiment was conducted according to the following procedure, and the results are shown in the following table.

≪Experiment 1≫
In order to evaluate the difference in adsorption effect between water alone and agent A (powder obtained by drying and crushing okra), a contaminated towel is placed in a washing machine, washed with 30 L of water for 5 minutes and then dried. The dried (contaminated towel) (solid phase) was measured for radiation (amount) concentration of cesium 137 by a gamma ray spectrometry method using a germanium semiconductor detector.

≪Experiment 2≫
Next, 1.5 g of agent A (powder obtained by drying and crushing okra) manufactured by Yaki Sangyo Co., Ltd. is dissolved in 30 L of water of Experiment 2 as a component derived from the genus Troy's family. The radiation density of the contaminated towel subjected to the same treatment as in Experiment 1 was measured.

  From the results of the above experiments, it can be seen that the decontamination composition of the present invention has higher decontamination efficiency than conventional water washing.

≪Experiment 3≫
Next, in order to evaluate the adsorption effect of the agent A and the cleaning effect of the contaminants by the surfactant, 80 g of the contaminated soil was stirred and washed with 400 ml of water in which 40 mg of the agent A was dissolved, centrifuged, and dried. The solid phase radiation concentration was measured with a surface contamination survey meter.

≪Experiment 4≫
Following Experiment 3, the solid phase after centrifugation and drying was stirred and washed with 400 ml of water to which 1.2 ml of Pionein C-158D manufactured by Takemoto Yushi Co., Ltd. was added as an alkylbetaine that is an amphoteric surfactant. Thereafter, the mixture was centrifuged, and the radiation concentration of the solid phase after drying was measured with a surface contamination survey meter.

  From the above experimental results, it can be seen that the decontamination composition of the present invention has higher decontamination efficiency than conventional water washing. Furthermore, it turns out that the decontamination effect increases by washing | cleaning with surfactant.

≪Experiment 5≫
In order to confirm the radiation concentration for each particle diameter of the contaminated soil, the radiation concentration was measured with a surface contamination survey meter for the contaminated soil that was screened for each particle size using a standard sieve while dispersing the contaminated soil in an appropriate amount of water.

  From the results of the experiment, it can be seen that the radiation concentration of fine particle portions of 38 μm or less in the contaminated soil is concentrated.

≪Experiment 6≫
Next, in order to evaluate the soil classification effect by keratin hydrolyzate and gas, after stirring 40 kg of soil with 100 L of water in which 1 L of keratin hydrolyzate was dissolved, air was injected at a flow rate of 100 L per minute, The particle size distribution of the soil adhered to the foam while foaming was measured with a laser diffraction particle size distribution measuring device.

  From the above experimental results, it can be seen that only the fine particles of the soil can be efficiently captured by using the keratin hydrolyzate and gas injection in combination. This means that only the part where the radiation dose of the fine particle part in the contaminated soil is concentrated can be efficiently captured.

≪Experiment 7≫
In order to evaluate the adsorption effect of agent A, 60 g of contaminated soil was dispersed in 1 L of water in which 50 mg of agent A was dissolved, put into a container with a volume of 2.7 L, and microbubbles at a flow rate of 4.4 L / min from the bottom. The soil suspended in the container was collected while water was introduced, and the radiation concentration of cesium 137 was measured by the method of gamma-ray spectrometry using the germanium semiconductor detector for the solid phase after the drying. .

≪Experiment 8≫
Furthermore, 20 g of FROG manufactured by Yaki Sangyo Co., Ltd. and an auxiliary agent were added as an aggregating agent to the aqueous dispersion obtained by introducing microbubble water, and then agglomerated and separated by stirring. After filtration, the solid phase and The radiation concentration of the aqueous phase was measured.

  From the results of the above experiments, it can be seen that the decontamination composition of the present invention has higher decontamination efficiency than conventional water washing.

  In general, among radioactive contaminants, particles having a small particle size (large specific surface area) are highly contaminated. By injecting gas, the same adsorption effect can be obtained, and particles having a small particle size can be captured. Collection (classification) increases the volume reduction efficiency of pollutants after decontamination.

  In addition, it is expected that adhesion is enhanced when a radioactive contaminant composed of a three-dimensional structure such as a building is treated by mixing a gas with the decontaminating agent composition to form a foam. This prolongs the sensitization time for the radioactive contaminants of the decontamination component, and as a result, the decontamination effect can be enhanced.

Claims (4)

A decontaminating composition for a radioactive pollutant containing a radioactive substance, comprising a powdery product obtained by drying and pulverizing a plant classified into the genus Troloae , and a keratin hydrolyzate. Mixing the decontaminant composition according to claim 1 with radioactive contaminants containing radioactive substances in an aqueous phase; injecting a gas into the mixture to generate bubbles containing the radioactive contaminants; Collecting the bubbles, adding a flocculant, aggregating and separating the radioactive material contained in the bubbles, and defoaming the bubbles ;
A decontamination method for removing the radioactive substance from the radioactive contaminant.   The decontamination method according to claim 2, wherein the mixture after the radioactive substance is removed by the generation of the foam is further washed with a surfactant. The decontamination method according to claim 2, wherein the flocculant includes a powdery body obtained by drying and pulverizing a plant classified into the genus Troyae.