JP5058373B2 - Processing method of used ion exchange resin - Google Patents

Description

  The present invention relates to a method for treating used ion exchange resin, which is one of operating wastes of nuclear facilities.

  One of the operating wastes of nuclear facilities is used ion exchange resin. Since this used ion exchange resin adsorbs a large amount of radionuclide, it contributes greatly to exposure, and its treatment as a waste subject to marginal disposal is being studied.

  However, since wastes subject to marginal depth disposal are costly and laborious to dispose, it is not efficient to dispose of all used ion exchange resins as wastes subject to marginal depth disposal.

  For this reason, in the treatment and disposal of used ion exchange resins, development of technology aimed at reducing the volume of waste to be disposed of has been performed prior to disposal. Examples of such techniques include steam reformer processing, incineration processing using IC plasma, and the like. However, in these treatments, it is difficult to completely treat the ion exchange resin, and there is a problem that almost the entire amount of waste after volume reduction becomes a target for disposal at a sufficient depth.

  In addition, a technique has been developed in which a used ion exchange resin is completely decomposed with supercritical water and a radionuclide is confined in a solution (for example, see Patent Document 1). In the case of this technology, the radionuclide chemical separation operation of the decomposition treatment liquid is possible, so after performing the separation operation, it is possible to dispose the waste separately for the extra depth disposal target and the other, and the extra depth It is effective for volume reduction of disposal waste.

Japanese Patent Laid-Open No. 11-23793

  As described above, the technique of completely decomposing used ion exchange resin with supercritical water and confining the radionuclide in the solution is effective for reducing the volume of waste disposal waste. However, supercritical water treatment requires a large-scale device for ensuring high temperature and high pressure, and there is a problem that costs increase.

  The present invention has been made in response to the above-described conventional circumstances, and provides a method for treating a used ion exchange resin that can efficiently dispose of a used ion exchange resin at a lower cost than in the past. Objective.

  One embodiment of the present invention is a treatment method of a used ion exchange resin in which a radioactive substance is adsorbed, in the method for treating a used ion exchange resin, an ion that is an adsorption site of the used ion exchange resin by alkali melting with a strong basic salt An ion exchange group disabling treatment step for disabling an exchange group, a separation step for separating the used ion exchange resin in which the ion exchange group is disabled, and the radioactive substance are provided.

  ADVANTAGE OF THE INVENTION According to this invention, the processing method of used ion exchange resin which can dispose of used ion exchange resin efficiently at low cost compared with the former can be provided.

Explanatory drawing which shows typically schematic structure of embodiment of the processing method of the used ion exchange resin of this invention. Explanatory drawing which shows typically schematic structure of the apparatus used for embodiment of this invention. The graph which shows the temperature dependence at the time of the hydrothermal decomposition process of the ion exchange capacity change of an ion exchange resin.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a schematic configuration of a method for treating a used ion exchange resin according to the present embodiment.

  As shown in FIG. 1A, a used radionuclide (radioactive substance) 2 (A shown in the lower part of FIG. 1A) is adsorbed on the used ion exchange resin (sulfonic acid series) 1. In the present embodiment, first, the used ion exchange resin 1 is mixed with the reaction liquid in the reaction vessel and reacted to disable the ion exchange group (disengage the functional group and neutralize electrically). ) Ion exchange group disabling treatment process is performed.

  As the ion exchange group disabling treatment step, any of hydrolysis under hydrothermal conditions, alkali melting with a strong basic salt, and reduction treatment can be used. Through this ion exchange group disabling treatment step, the radionuclide 2 adsorbed on the used ion exchange resin 1 leaves the used ion exchange resin 1 and moves into the reaction liquid.

  As a result, as shown in FIG. 1B, the used ion exchange resin 1a that has undergone the ion exchange group disabling process is in a state in which the radionuclide 2 has been detached. In addition, as such a radionuclide 2, Co-60 etc. which bring about a high dose rate to an ion exchange resin are contained, for example.

  Next, the used ion exchange resin 1a in which the radionuclide 2 is released from the ion exchange group deactivation process is separated from the reaction liquid containing the released radionuclide 2, and the used ion exchange resin is separated. 1a is treated as a waste subject to disposal in a shallow area at a relatively low level. Thereby, the used ion exchange resin 1 which generate | occur | produces abundantly can be made outside the waste object for marginal depth disposal. On the other hand, the radioactive waste liquid containing the radionuclide 2 such as Co-60 after separation is treated as a relatively high level waste subject to disposal at a relatively high level after being concentrated or diluted as necessary.

  FIG. 2 is a diagram schematically illustrating a schematic configuration of an example of a processing apparatus for used ion exchange resin used in the present embodiment.

  As shown in the figure, a used ion exchange resin processing apparatus 10 stores a resin storage tank 11 for storing a used ion exchange resin 1 that has captured a radionuclide, and a chemical (reaction liquid) 12. A chemical tank 13, a reaction tank 14 for performing ion exchange group disabling treatment, an aqueous solution containing a radionuclide desorbed together with a functional group of the ion exchange resin, and a used ion exchange resin that has been subjected to ion exchange disabling treatment And a concentrating tank 16 for concentrating and reducing an aqueous solution containing a radionuclide. In FIG. 2, 20 is a pipe connecting the chemical tank 13 and the reaction tank 14, 21 is a pipe connecting the resin storage tank 11 and the reaction tank 14, and 22 is a separation tank 15 and a concentration tank 16. It is the piping which connects.

  In the spent ion exchange resin processing apparatus 10 having the above-described configuration, the spent ion exchange resin 1 is introduced from the resin storage tank 11 into the reaction tank 14 and a predetermined amount from the chemical tank 13 to the reaction tank 14. The chemical | medical solution 12 is introduce | transduced and the ion exchange group disabling process process mentioned above in the reaction tank 14 is performed.

  When this ion exchange group disabling treatment step is performed by hydrolysis under hydrothermal conditions, the treatment temperature is preferably 250 ° C. or higher, more preferably about 300 ° C. This is for the following reason.

  That is, FIG. 3 shows the temperature dependence of the ion exchange capacity during the hydrothermal decomposition treatment as a result of the decomposition treatment for the sulfonic acid resin with the vertical axis representing the ion exchange capacity (%) and the horizontal axis representing the temperature (° C.). Is. As shown in FIG. 3, the ion exchange capacity decreases as the temperature during the hydrothermal decomposition treatment decreases, and the ion exchange capacity is about 30% under the 250 ° C. treatment condition and about 90% under the 300 ° C. treatment condition. It turns out that it is lost. By performing the hydrothermal decomposition treatment under such temperature conditions, it is expected that the functional group portion of the used ion exchange resin is hydrolyzed and the captured ionic radionuclide is effectively released.

  Moreover, when performing the said ion exchange group deactivation process process by the alkali fusion | melting by a strong basic salt, it can carry out by exposing a used ion exchange resin to sodium hydroxide or potassium hydroxide, for example. . In this case, the treatment temperature is preferably 200 ° C. or higher, for example.

  Furthermore, when performing the said ion exchange group disabling process process by a reduction process, it can carry out by exposing used ion exchange resin to a hydrogen iodide solution, for example.

  As described above, in the reaction tank 14, after performing the ion exchange group disabling treatment step by any of hydrolysis under hydrothermal conditions, alkali melting with a strong basic salt, and reduction treatment, A solid spent ion exchange resin that has been subjected to ion exchange group deactivation treatment and a solution containing a radionuclide are separated.

  The solution containing the radionuclide separated from the used ion exchange resin as described above is concentrated and reduced in the concentration tank 16 as necessary. The waste containing the reduced radionuclide is treated as a waste subject to disposal at a sufficient depth. On the other hand, the solid used ion exchange resin that has been subjected to the ion exchange group disabling treatment is treated as a waste subject to disposal in shallow areas.

  As described above, according to the present embodiment, the used ion exchange resin is subjected to the ion exchange group disabling treatment, and the functional group is released to neutralize the used ion exchange resin, thereby performing the used ion exchange resin. The radionuclide adsorbed on the waste can be separated from the used ion exchange resin. Can be processed as This makes it possible to reduce the amount of waste subject to disposal at a deeper depth without performing supercritical water treatment or the like that increases the processing cost, and to dispose of used ion exchange resin efficiently at a low cost.

  As described above, according to the present embodiment, the used ion exchange resin can be efficiently disposed of at a lower cost than in the past.

  DESCRIPTION OF SYMBOLS 1,1a ... Used ion exchange resin, 2 ... Radionuclide, 10 ... Used ion exchange resin processing apparatus, 11 ... Resin storage tank, 12 ... Chemical solution (reaction liquid), 13 ... Chemical solution Tank, 14 ... Reaction tank, 15 ... Separation tank, 16 ... Concentration tank, 20, 21, 22 ... Piping.

Claims (3)

In the processing method of the used ion exchange resin which processes the used ion exchange resin which the radioactive substance adsorbed,
An ion exchange group disabling treatment step of disabling the ion exchange group that is the adsorption site of the used ion exchange resin by alkali melting with a strong basic salt;
A method for treating a used ion exchange resin, comprising: the used ion exchange resin in which an ion exchange group is disabled; and a separation step of separating the radioactive substance. In the processing method of the used ion exchange resin of Claim 1,
A method for treating a used ion exchange resin, wherein the alkali melting with the strong base salt is performed by exposing the used ion exchange resin to sodium hydroxide or potassium hydroxide. In the processing method of the used ion exchange resin of Claim 1 or 2,
A method for treating a used ion exchange resin, wherein the alkali melting with the strong basic salt is performed under a temperature condition of 200 ° C. or higher.

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