JP6560304B2 - Decontamination agent - Google Patents

Description

  The present invention relates to a decontamination agent, in particular, a biodegradable decontamination agent that can be easily post-treated and reusable.

  In nuclear power facilities such as nuclear power plants, there is a possibility that the surface of surrounding structures will be contaminated with radioactive materials such as cobalt and manganese due to work such as decontamination of radioactive materials. .

  The radioactive material attached to the surface of the structure continues to emit radiation, so that workers are exposed to radiation. Therefore, structures contaminated with radioactive materials need to be decontaminated at an early stage.

  As one method for decontaminating a structure to which radioactive material is attached, there is a method in which high-pressure water is sprayed on the surface of the structure for cleaning, and the contaminated waste liquid is collected and disposed.

  However, the operation of spraying high pressure water evenly on the surface of the structure to clean it requires a lot of time and labor. In addition, it takes a lot of time and labor to collect the contaminated waste liquid. Furthermore, there is a possibility that the contaminated waste liquid flows out to the surroundings or penetrates underground to cause secondary contamination.

  Therefore, as a decontamination method for solving the above problems, there is a method in which a gel-like decontamination agent film is formed on the surface to be decontaminated, and the decontamination agent enclosing the radioactive substance is peeled off from the surface to be decontaminated and removed. Proposed.

  An example of a decontamination method using a gel-like decontamination agent is disclosed in Patent Document 1. Hereinafter, this decontamination method is referred to as a conventional decontamination method.

  Conventional decontamination methods consist of the following steps.

  A decontamination agent (A) in which the monovalent metal salt of alginic acid is composed of an aqueous sodium alginate solution and a decontamination agent (B) composed of an aqueous calcium chloride solution are prepared.

  Next, the decontamination agent (A) is applied or spread on the decontamination surface 2 of the structure 1 by any means, for example, a brush, roller, shower or spray.

  Next, the decontamination agent (B) is applied or spread on the surface 2 to be decontaminated of the structure 1 as shown in FIG. 5 by any means such as a brush, roller, shower or spray.

  Thus, when the decontaminating agent (A) and the decontaminating agent (B) are brought into contact with each other, an ionic cross-linking reaction occurs between the alginic acid molecules and the calcium ions in the decontaminating agent, resulting in gelation. At this time, as shown in FIG. 6, the decontamination agent 3 is solidified on the surface 2 to be decontaminated while containing a radioactive substance.

  After the predetermined time has passed and the gelation has sufficiently progressed, as shown in FIG. 7, the gelled decontamination agent 3 is peeled off from the surface of the structure 1 and removed to enclose the decontamination agent. The radioactive material is removed together with the gelled decontamination agent.

JP2013-96984A

  According to the conventional decontamination method, it is possible to remove radioactive substances adhering to the surface to be decontaminated such as buildings without causing secondary contamination.

  However, in the conventional decontamination method, it is necessary to apply or disperse the decontamination agent (A) and the decontamination agent (B) separately on the surface to be decontaminated. In addition, the treatment of the gelled decontamination agent enclosing the radioactive substance is costly.

  Accordingly, an object of the present invention is to provide a decontaminating agent that can be easily decontaminated and biodegradable, and therefore can be easily post-treated and reusable.

  The present invention has been made to achieve the above object, and is characterized by the following.

  The invention according to claim 1 is a gel-like decontamination agent for removing radioactive substances adhering to the surface to be decontaminated. It is characterized by containing sand and reducing monosaccharides / oligosaccharides.

  According to this invention, since it can decontaminate only by apply | coating or spraying on the to-be-decontaminated surface once, a labor and labor are not required for decontamination.

  In addition, if the decontamination reagent of the present invention is used, the gel-like spent decontamination agent containing the radioactive substance is liquefied, and then the radioactive substance is separated and removed from the liquefied used decontamination reagent. Thereafter, the used decontamination reagent that has been liquefied is gelled again, whereby the used decontamination reagent can be reused. As a result, the decontamination cost can be reduced.

  In addition, according to the present invention, since chemicals that are biodegradable and troublesome to use are not used, post-processing can be easily performed.

It is process drawing which shows the processing method for reusing the decontamination agent of this invention. It is process drawing which shows the liquefaction means of a used decontamination agent. It is process drawing which shows the liquefaction means of another used decontamination agent. It is process drawing which shows the liquefaction means of another used decontamination agent. It is sectional drawing which shows the state which apply | coated or sprayed the decontamination agent on the to-be-decontaminated surface by the conventional decontamination method. It is sectional drawing which shows the state which included the radioactive substance of the to-be-decontaminated surface by the conventional decontamination method, and was gelatinized. It is sectional drawing which shows the state which isolate | separated the decontamination agent which included the radioactive substance from the surface to be decontaminated by the conventional decontamination method, and was gelatinized.

  One embodiment of the decontamination reagent of the present invention will be described with reference to the drawings.

  The decontamination agent of the present invention includes at least one of Guar Gum, Tara Gum, and konjac flour, borax as a cross-linking agent thereof, and reducing monosaccharide / oligosaccharide. It has become.

  Borax has an action of increasing the rigidity of the gel-like decontaminating agent by promoting a cross-linking reaction that connects the guar gum molecules. However, when borax is added to guar gum, the rigidity of the gel-like decontamination agent increases, but the fluidity decreases.

  Therefore, in this invention, both the rigidity and the fluidity of the gel-like decontamination agent are improved by further adding reducing monosaccharides / oligosaccharides.

  Test examples of the method for producing the decontamination reagent of the present invention will be described.

  Add 0.5 g of guar gum to 50 ml of water, stir and leave to swell. Subsequently, it can be manufactured by adding bolus sugar liquid (borax 10 wt% and fructose 13 wt%) and stirring.

  The viscosity of the decontamination reagent produced in this way can be adjusted by changing the amount of reducing monosaccharide / oligosaccharide added.

  In order to decontaminate a building or the like to which a radioactive substance has adhered by using the decontamination agent of the present invention, a gel-like decontamination agent is applied to the surface of a building or the like to which a radioactive substance has adhered by brush, roller, shower or spray. Alternatively, after spraying, the gel-like decontaminant containing the radioactive substance is peeled off from the surface of a structure such as a building and removed.

  In this way, since it is sufficient to apply or spray the decontamination agent once, the labor and labor required for decontamination can be reduced.

  Note that the gel-like decontamination agent lump may be rolled along the surface of the building or the like so that the radioactive substance adhering to the surface of the building or the like may be included in the decontamination agent lump.

  Next, a method for treating a used decontaminant for enabling reuse of a decontaminant after use containing a radioactive substance will be described with reference to the drawings.

  FIG. 1 is a process diagram showing a treatment method for reusing the decontamination reagent of the present invention.

  As shown in FIG. 1, the treatment method for reusing the decontamination reagent of the present invention is that the gel-like spent decontamination agent is liquefied by the liquefaction means, and the radioactive substance is used from the liquefied spent decontamination reagent. Is separated and removed by a separating means, and thereafter, the used decontaminating agent liquefied is gelled again by a regelling means.

  Thus, the decontamination cost can be reduced by re-gelling the liquefied used decontamination agent by the re-gelation means.

  Next, a means for liquefying a used decontaminating agent will be described with reference to the drawings.

  FIG. 2 is a process diagram showing a means for liquefying a used decontamination reagent.

  As shown in FIG. 2, the liquefaction means prepares a boric acid aqueous solution and a fructose aqueous solution, adds the boric acid aqueous solution to the gel-like spent decontaminant and stirs, and then adds the fructose aqueous solution and stirs. It is made to do.

  A test example of this liquefaction means is as follows.

  About 10 g of 5 wt% boric acid aqueous solution is added to the gel-like used decontaminant and stirred. In this state, the gel was still maintained, but about 5 g of a 75 wt% fructose aqueous solution was further added thereto and stirred to liquefy the gel used decontamination reagent.

  Another means for liquefying the used decontamination reagent will be described with reference to the drawings.

  FIG. 3 is a process diagram showing another used decontamination liquefaction means.

  As shown in FIG. 3, another used decontamination means liquefaction means preparing a mixed aqueous solution in which fructose is added to a boric acid aqueous solution, adding this mixed aqueous solution to the gel-like used decontamination agent, Consists of stirring.

  A test example of this other liquefaction means is as follows.

  An aqueous solution (pH 3.5) of boric acid 4.63 wt% and fructose 7.41 wt% was prepared, and about 20 g of this aqueous solution was added to the gel-like spent decontaminant and stirred to obtain a used decontaminant. It could be liquefied.

  Further, another means for liquefying the used decontamination agent will be described with reference to the drawings.

  FIG. 4 is a process diagram showing yet another liquefaction means for used decontamination reagent.

  As shown in FIG. 4, another used decontamination means for liquefaction is prepared by preparing an aqueous citric acid solution, adding the aqueous citric acid solution to the gel-like spent decontamination agent, and stirring. It consists of liquefying the used decontaminating agent.

  A test example of this further liquefaction means is as follows.

  Making a citric acid aqueous solution adjusted to about pH 3.3, adding about 8 g of this citric acid aqueous solution to the gel-like spent decontamination reagent, and stirring to liquefy the gel-like spent decontamination reagent I was able to.

  Next, there is a means for separating radioactive substances from the liquefied used decontamination reagent. This separation means uses a filtration method, a precipitation separation method based on a difference in specific gravity, a centrifugal separation method, or the like. It is also possible to separate by chemical precipitation.

  The radioactive material contained in the liquefied used decontamination agent is separated and removed by these separation means.

  Next, there is a regelation means for the liquefied used decontamination agent, which consists of adding sodium hydroxide to the liquefied used decontamination agent.

  For example, by adding about 10 g of 1 mol / L NaOH to the used decontamination reagent liquefied as described above and stirring, the liquefied used decontamination reagent can be re-gelled.

  As described above, according to the present invention, since decontamination can be performed only by applying or spraying the surface to be decontaminated once, no effort and labor are required for decontamination.

  In addition, if the decontamination reagent of the present invention is used, the gel-like spent decontamination agent containing the radioactive substance is liquefied, and then the radioactive substance is separated and removed from the liquefied used decontamination reagent. Thereafter, the used decontamination reagent that has been liquefied is gelled again, whereby the used decontamination reagent can be reused. As a result, the decontamination cost can be reduced.

  In addition, the decontamination reagent of the present invention is biodegradable and does not use troublesome chemicals, so that post-treatment can be easily performed.

1: Structure 2: Surface to be decontaminated 3: Decontamination agent

Claims (1)

In a gel-like decontamination agent for removing radioactive substances adhering to the surface to be decontaminated,
A decontamination agent comprising at least one of guar gum, tara gum, and konjac powder, borax, and reducing monosaccharides and oligosaccharides.

Images