JP2015137898A - Decontamination device of radioactive contaminant and decontamination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decontamination device capable of reducing sizes of a facility and a land for storing radioactive substances and a volume of radioactive contaminants by relatively easily extracting and separating the radioactive substances from the radioactive contaminants.SOLUTION: A decontamination device comprises: an electrolysis tank 2 which stores electrolysis solution 3 and radioactive contaminants D; an agitator 4; positive and negative electrode members 5 and 6 which are connected to an external DC power source 7; and a collection film coating the electrode member 6. The electrode members 5 and 6 are arranged opposite to each other in the electrolysis solution 3 in the electrolysis tank 2. The radioactive contaminants D are input into the electrolysis solution 3 in the electrolysis tank 2 and agitated by the agitator 4. Voltage is applied to the electrode members 5 and 6 in the electrolysis solution 3 through the DC power source 7. Then, radioactive substances F are extracted from the radioactive contaminants D and attracted to the electrode member 6 due to an electrokinetic phenomenon resulting from the voltage application. The radioactive substances F which precipitate on the collection film coating the electrode member 6 are collected and sealed in a radioactive waste storing container together with the collection film.

Description

  The present invention relates to an apparatus and method for separating and recovering radioactive substances from radioactive pollutants such as waste water, soil, sludge, sludge incineration ash, and building waste materials contaminated with radioactive substances.

As one of the decontamination measures for radioactive materials released in large quantities from the Fukushima Daiichi nuclear power plant due to the Great East Japan Earthquake, contaminated soil is stored in flexible container bags and temporarily stored in temporary storage. However, there are problems such as large-scale storage facilities, a great amount of continuous management, lack of existing land, and difficulty in acquiring new land. The same applies to the case where a large amount of radioactive waste such as building waste materials in a future decommissioning furnace is enclosed and stored in a container.
Conventionally, after mixing and stirring the radiation-contaminated soil to be treated in water, it is separated into liquid surface suspended material, diffusing material and precipitated material, separating the precipitated material from the separated composition, and further into the liquid phase of the diffusing material. By adding a flocculant, it is separated into water and agglomerated material, and separated into liquid surface floating material, diffusing material and precipitated material, among which liquid surface floating material and diffusing material are dried and stored or treated as radioactive waste. There is a method (see Patent Document 1).

JP 2013-117498

In the above conventional method, radioactive waste pollutants are concentrated and recovered. However, the work of separating pollutants requires a long stay at the work site, and the radioactive material itself is removed. It is difficult to extract, and it is not sufficient to reduce the scale of the storage facility for the final managed objects, and the labor for securing the facility site and storage management is still not improved.
Accordingly, the present invention provides a decontamination apparatus and decontamination method for radioactive contaminants that extract radioactive materials from radioactive waste relatively easily, and promotes the reduction of radioactive material storage facilities and the downsizing of facility sites. To do.

In order to solve the above-described problems, the present invention provides an electrolytic cell 2 for immersing the radioactive contaminant D in the electrolytic solution 3 in the radioactive contaminant decontamination apparatus 1 that separates and recovers the radioactive substance F from the radioactive contaminant D. And positive and negative electrode members 5 and 6 for separating and attracting the radioactive substance F from the radioactive contaminant D. A voltage is applied between the electrode members 5 and 6 to electrolyze the radioactive contaminant D, the radioactive substance F is extracted to the electrode member 5 (6) by electrophoresis or electroosmosis, and this is recovered and disposed.
The electrolytic solution 3 contains a cleaning agent that promotes elution of radioactive substances.
The electric field tank 2 is provided with a stirring means for the electrolytic solution 3 such as a stirrer 4.
The electrode member 5 (6) is covered with a conductive recovery film 8 to which a radioactive substance is attached, and the radioactive substance is recovered and disposed of together with the recovery film 8.
The collection film 8 is formed by applying a conductive adhesive to a metal thin film, applying a conductive resin to the electrode member 5 (6), or is formed of a conductive resin thin film.
A treatment tank 14 containing an electrolyte containing a radioactive material attracted in the vicinity of the electrode member 5 (6), a heat source for evaporating the electrolyte 3 in the treatment tank 14, and an evaporation residue laid at the bottom of the treatment tank 14 The heat-resistant film 15 holding the product G is provided, and the electrolyte solution 3 in which the radioactive substance is concentrated is dried, and the evaporation residue G is recovered and disposed of together with the heat-resistant film 15.
A radioactive substance adsorbent may be fixed to the surface of the electrode member 5 (6), the recovery film 8 or the heat-resistant film 15.
The radioactive material adsorbent is formed of at least one of zeolite, lamellar clay mineral, or ferric ferrocyanide compound and at least one of carbon powder, sludge incineration ash, peat (peat), or metal powder. .
The radioactive substance adsorbing member 17 may contain at least one of zeolite, layered clay mineral, or ferric ferrocyanide compound as a radioactive substance adsorbent in a water permeable container.
The electrode member 5 (6) was formed of any one or more of zeolite, layered clay mineral or ferrocyanide compound, and one or more of carbon powder, sludge incineration ash, peat (peat), or metal powder. Shall.
The heat-resistant film 15 is formed by applying a heat-resistant adhesive to a metal thin film, or formed by applying a heat-resistant resin to the bottom of the treatment tank, or formed by a heat-resistant resin thin film.

  In the present invention, the radioactive material can be easily recovered by concentration and extraction by electrolysis, it is easy to mechanize in a closed facility, it does not require long-term stay of workers at the work site, and the labor of processing work is reduced. In addition, it is possible to reduce the exposure risk of workers and to reduce the difficulty of managing the radioactive waste storage facility and securing the site for the facility.

It is the schematic of the decontamination apparatus which concerns on 1st Example of this invention. It is the schematic of an electrode member. It is the schematic of the decontamination apparatus which concerns on 2nd Example of this invention. It is the schematic of the decontamination apparatus which concerns on 3rd Example of this invention. It is the schematic of the decontamination apparatus which concerns on 4th Example of this invention.

Embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, a radioactive contaminant decontamination apparatus 1 according to the first embodiment includes an electrolytic tank 2 that contains an electrolytic solution 3, waste water contaminated with radioactive substances in the electrolytic solution 3 in the electrolytic tank 2, soil, A stirrer 4 for sinking radioactive contaminants D such as sludge, sludge incineration ash, and building waste, and agitating the electrolytic solution 3; a pair of positive and negative electrode members 5 and 6 inserted into the electrolytic solution 3 in the electrolytic cell 2; A DC power source 7 to which the electrode members 5 and 6 are connected is provided.
The electrolytic cell 2 performs an electrolysis process of the radioactive contaminant D. An electrolytic aid such as sodium chloride is added to the electrolytic solution 3 as necessary.
The stirrer 4 is for pre-cleaning the radioactive contaminant D by stirring the electrolytic solution 3. Instead of the stirrer 4, a decanter type cleaning device or the like may be provided in order to improve the cleaning efficiency.
Although a pair of positive and negative electrode members 5 and 6 are opposed to each other so as to form an electric field in the electrolytic solution 3 in the electrolytic cell 2, a plurality of pairs may be provided in an arrangement in which electrolysis occurs efficiently. The electrode members 5 and 6 are made of a general electrode material such as metal or carbon in a long bar shape or a flat plate shape. The electrode members 5 and 6 may be formed by mixing a powdered electrode material of a metal powder such as carbon powder, sludge incineration ash, peat (peat) or iron powder, aluminum powder, and a radioactive substance adsorbent.

  As shown in FIG. 2, the electrode members 5 and 6 may be covered with a recovery film 8 that is easily attached and detached on the surface of a general electrode material. The recovery film 8 is formed by covering a metal thin film or a conductive resin thin film with a conductive adhesive material and molding it. Further, the recovery film 8 may include a radioactive material adsorbent. The radioactive material adsorbent is, for example, at least one or more of zeolite, layered clay mineral or ferrocyanide compound, and conductive such as carbon powder, sludge incineration ash, peat (peat), metal powder such as iron powder or aluminum powder. Including at least one of the substances.

In the decontamination apparatus 1, first, in the cleaning process, the radioactive substance F is eluted from the radioactive contaminant D into the electrolytic solution 3 in the electrolytic tank 2, and the electrolytic solution 3 is stirred by the stirrer 4 to promote this. Depending on the contamination mode of the radioactive contaminant D, this cleaning step may be omitted.
Next, in the electrolysis process, the voltage of the DC power source 7 is applied to the electrode members 5 and 6, and the radioactive substance F is attracted to the electrode members 5 or 6 by electrokinetic phenomena such as electrophoresis and electroosmosis accompanying electrolysis. .
Next, in the recovery step, the radioactive substance F adhering to the electrode member 5 or 6 is recovered and sealed in a radioactive waste storage container such as a drum can. This radioactive waste storage container is stored in a predetermined storage facility.
When the electrode member 5 or 6 is coated with the recovery film 8, the radioactive substance F is deposited on the recovery film 8, so the precipitate is peeled off from the electrode member 5 or 6 together with the recovery film 8 and stored as radioactive waste. What is necessary is just to enclose in a container.

A second embodiment of the present invention will be described with reference to FIG. In the following, the same components as those in the previous embodiment are denoted by the same reference numerals, and description thereof is omitted.
In FIG. 3, the decontamination apparatus 9 includes, in the previous decontamination apparatus 1, a cleaning tank 10 that contains the cleaning liquid 11, and an agitator 12 that stirs the cleaning liquid 11 in which radioactive contaminants D are submerged in the cleaning tank 10. It has been added. The cleaning tank 10 preliminarily cleans the radioactive contaminant D, and the cleaning liquid 11 is an acid, an alkali, a chelate, a salt, an oxidizing agent, a reducing agent, etc. for promoting the extraction of the radioactive substance F from the radioactive contaminant D. It is an aqueous solution to which one or more are added.

  In the decontamination apparatus 9, the radioactive substance F is eluted from the radioactive contaminant D into the cleaning liquid 11 in the cleaning tank 10 in the cleaning process, and the cleaning liquid 11 is stirred by the stirrer 12 to promote this. Next, the cleaning liquid 11 and the radioactive contaminant D are transferred from the cleaning tank 10 to the electrolytic tank 2, and the electrolysis process and the recovery process are performed in the same manner as described above.

A third embodiment of the present invention will be described with reference to FIG.
The radioactive contaminant decontamination apparatus 13 includes a treatment tank 14 that receives the electrolytic solution 3 in which the radioactive substance F attracted to the electrode member 6 is eluted, and a heat-resistant film that is laid on the bottom of the treatment tank 14 or fixed by sticking. 15 is added. The heat-resistant film 15 may be formed by applying a metal thin film such as silicone, or a heat-resistant resin, a heat-resistant paint, a heat-resistant adhesive, a heat-resistant caulking agent, or the like to the bottom of the treatment tank 14. In the decontamination apparatus 13, as in the previous embodiments, the electrolytic solution 3 in which the radioactive substance F attracted to the electrode member 6 is eluted is transferred to the treatment tank 14, and the sun or an electric heater (not shown) is used. The treated water is evaporated by the heat source, and the evaporation residue G is peeled off together with the heat-resistant film 15 and stored in a radioactive waste storage container such as a drum can.

A fourth embodiment of the present invention will be described with reference to FIG.
This radioactive contaminant decontamination apparatus 16 is one in which a radioactive substance adsorbing member 17 is introduced into the treatment tank 14 in the previous embodiment. The radioactive substance adsorbing member 17 is formed of powder, granules or sheets of at least one of zeolite, layered clay mineral or ferrocyanide compound and accommodated in a water permeable container such as sandbag, nonwoven fabric or cartridge. It is a fruit. In this decontamination apparatus 16, as in the previous embodiments, the electrolytic solution 3 from which the radioactive substance F has been eluted is transferred to the treatment tank 14, and is poured into the treated water so as to adsorb the radioactive substance F. The material adsorbing member 17 is stored in a radioactive waste storage container.

DESCRIPTION OF SYMBOLS 1 Decontamination apparatus 2 Electrolytic tank 3 Electrolytic solution 4 Agitator 5 Electrode member 6 Electrode member 7 DC power supply 8 Collected film 9 Decontamination apparatus 10 Cleaning tank 11 Cleaning liquid 12 Stirrer 13 Decontamination apparatus 14 Treatment tank 15 Heat-resistant film 16 Decontamination apparatus 17 Radioactive material adsorbing member D Radioactive contaminant F Radioactive material G Evaporation residue

Claims (16)

In the decontamination equipment for radioactive contaminants that separates and recovers radioactive materials from radioactive contaminants,
An electrolytic cell containing an electrolytic solution for immersing the radioactive contaminant in the electrolytic solution, and a positive and negative electrode member for separating and attracting the radioactive material from the radioactive contaminant,
Radioactive contaminants are electrolyzed by applying a voltage between the electrode members, and the radioactive substances are extracted and collected on electrode members by electrokinetic phenomena such as electrophoresis or electroosmosis. Dyeing equipment.   2. The radioactive contaminant decontamination apparatus according to claim 1, wherein the electrolyte contains a cleaning agent that promotes elution of the radioactive substance.   The decontamination apparatus for radioactive contaminants according to claim 1 or 2, wherein the electrolytic cell is provided with a stirring means for an electrolytic solution.   The decontamination of radioactive contaminants according to any one of claims 1 to 3, wherein the electrode member is covered with a conductive recovery film to which a radioactive substance is attached, and the radioactive substance is recovered and disposed of together with the recovery film. apparatus.   The recovery film is any one formed by applying a conductive adhesive to a metal thin film, formed by applying a conductive resin to the electrode member, or a conductive resin thin film. The decontamination apparatus for radioactive contaminants according to claim 4. A treatment tank containing an electrolytic solution containing a radioactive material attracted in the vicinity of the electrode member; a heat source for evaporating the discharged liquid in the treatment tank; and a heat-resistant film laid on the bottom of the treatment tank to hold the evaporation residue Comprising
2. The radioactive contaminant decontamination apparatus according to claim 1, wherein the electrolyte containing the radioactive substance is dried, and the evaporation residue is collected and disposed of together with the heat-resistant film.   The radioactive contaminant decontamination device according to any one of claims 1 to 6, wherein a radioactive substance adsorbent is fixed to the electrode member, the recovery film, or the heat-resistant film.   8. The radioactive contaminant decontamination apparatus according to claim 7, wherein the radioactive substance adsorbing material contains one or more of zeolite, lamellar clay minerals, or iron ferrocyanide compounds.   9. The radioactive contaminant removal according to claim 8, wherein the radioactive material adsorbent is formed together with at least one of carbon powder, sludge incineration ash, peat (peat), or metal powder. Dyeing equipment.   The radioactive contaminant decontamination apparatus according to claim 8, wherein the radioactive substance adsorbing material is housed in a water-permeable container.   The electrode member is formed of at least one of zeolite, layered clay mineral, or ferrocyanide compound, and at least one of carbon powder, sludge incineration ash, peat (peat), or metal powder. The decontamination apparatus for radioactive contaminants according to any one of claims 1 to 3, wherein   The heat-resistant film is formed by applying a heat-resistant adhesive to a metal thin film, formed by applying a heat-resistant resin to the bottom of the treatment tank, or a heat-resistant resin thin film. A decontamination apparatus for radioactive contaminants according to claim 6. A decontamination method for radioactive contaminants that separates and recovers radioactive materials from radioactive contaminants,
An elution step of immersing the radioactive contaminant in an electrolytic solution;
An electrolysis process in which a voltage is applied between positive and negative electrode members in the electrolyte solution to electrolyze radioactive contaminants, and the radioactive material is attracted to one electrode member by electrophoresis or electroosmosis;
A decontamination method for radioactive contaminants, comprising: a recovery step of recovering a radioactive substance attached to the electrode member.   14. The method for decontaminating radioactive contaminants according to claim 13, wherein in the collecting step, the radioactive material adsorbed on the conductive collecting film coated on the electrode member is peeled off from the electrode member together with the collecting film.   In the recovery step, the electrolyte containing the radioactive material attracted in the vicinity of the electrode member is transferred to a treatment tank, the electrolyte is evaporated by a heat source, and the evaporation residue on the heat-resistant film laid at the bottom of the treatment tank is removed from the heat-resistant film. 14. The method for decontaminating radioactive contaminants according to claim 13, wherein the whole is collected.   14. The recovery step according to claim 13, wherein in the recovery step, an electrolyte containing a radioactive substance attracted in the vicinity of the electrode member is transferred to a treatment tank, and the radioactive substance is adsorbed and separated from the electrolyte by a radioactive substance adsorbent. Decontamination method for radioactive contaminants.

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