Disposal method of used ion exchange resin, and disposal device of used ion exchange resin

Abstract

To provide a disposal method of a used ion exchange resin and a disposal device of a used ion exchange resin which can efficiently dispose a large amount of a used ion exchange resin compared to conventional ones.SOLUTION: A disposal method of a used ion exchange resin includes: a plasma irradiation step of irradiating a used ion exchange resin with plasma; and a compression volume reduction step of compressing and volume reducing the used ion exchange resin irradiated with plasma in the plasma irradiation step.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a method for disposing of used ion exchange resin and an apparatus for disposing of used ion exchange resin. [Background technology]

[0002] In nuclear power plants, ion exchange resins are used in purification equipment such as reactor water purification systems and waste liquid treatment systems. The used ion exchange resins used in such purification equipment adsorb radioactive materials and have high radioactivity concentrations, so safe and inexpensive processing and disposal technologies are required. As an example of processing, used ion exchange resins are solidified with solidifying agents such as cement and stored in waste containers.

[0003] As a method for treating used ion exchange resin using plasma, for example, a method has been proposed in which the resin is treated with oxygen plasma in a vacuum chamber while being heated with a heater, and then the resin is incinerated and reduced in volume by a combustion reaction with the high-temperature oxygen (see, for example, Patent Document 1).As a method for treating low-level radioactive ion exchange resin using plasma, for example, a method has been proposed in which carbon dioxide or carbon monoxide is supplied as an oxidizing gas, and the resin is oxidized and decomposed by plasma treatment at high temperatures (700K to 1500K) (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4032606 [Patent Document 2] Patent No. 4403240 Summary of the Invention [Problem to be solved by the invention]

[0005] When solidifying used ion exchange resin, generally, only about 20 vol% of a 200 L drum is filled into the waste container. This is because the cross-linked structure of ion exchange resin causes the resin to swell and exert swelling pressure on the surrounding area (this volume expansion due to swelling is commonly known as springback), and if the amount of used ion exchange resin is increased, this swelling pressure may damage the soundness of the surrounding solidifying agent and waste container, so by reducing the amount of resin and increasing the amount of solidifying agent in the waste container, the robustness of the solidified body is increased.

[0006] Due to the swelling of the resin, only a small amount of used ion exchange resin can be disposed of as a percentage of the capacity of the waste container, which makes disposal less economical. Used ion exchange resin from the condensate purification systems generated at nuclear power plants and used ion exchange resin with relatively low levels of radioactivity generated at waste treatment facilities (L2 waste) are solidified and disposed of as waste bodies using operations that reduce the amount of resin filled in this way.

[0007] Meanwhile, nuclear power facilities store untreated used ion exchange resins generated in equipment for purifying reactor water and equipment for purifying water in spent fuel storage pools. These used ion exchange resins have radioactivity levels several orders of magnitude higher (L1 waste) than the used ion exchange resins from the condensate purification system mentioned above and the used ion exchange resins generated from waste treatment facilities, and in the future it will be necessary to process these used ion exchange resins.

[0008] For this reason, there is a demand for the development of a simple processing method that can suppress the scattering of radioactive materials during the processing process, increase the volume reduction rate, and safely process used ion exchange resins with high levels of radioactivity. For example, as a processing method before disposal of used ion exchange resins, it is desirable to compress and reduce the volume of the used ion exchange resins themselves using a compression device or the like.

[0009] However, when trying to reduce the volume by compression, there is a problem that the resin expands due to springback, making it difficult to reduce the volume sufficiently, and there is also a risk of damaging the integrity of the surrounding solidification agent and waste container. If the used ion exchange resin could be compressed and molded into a waste body, it would be possible to dispose of large amounts of resin more efficiently.

[0010] The present invention has been made to solve the above-mentioned problems, and has an object to provide a method and an apparatus for disposing of used ion exchange resin, which enable disposing of large amounts of used ion exchange resin more efficiently than conventional methods. [Means for solving the problem]

[0011] A method for disposing of used ion exchange resin according to an embodiment of the present invention is characterized by comprising a plasma irradiation process for irradiating plasma onto used ion exchange resin, and a compression and volume reduction process for compressing and reducing the volume of the used ion exchange resin that has been irradiated with plasma in the plasma irradiation process.

[0012] A used ion exchange resin disposal device according to an embodiment of the present invention is a used ion exchange resin disposal device, characterized in that it has a plasma generating device that generates plasma, a plasma irradiation unit that irradiates the used ion exchange resin with the plasma generated by the plasma generating device, and a compression and volume reduction device that compresses and reduces the volume of the used ion exchange resin that has been irradiated with plasma by the plasma irradiation unit. Effect of the Invention

[0013] According to the embodiments of the present invention, it is possible to provide a method and an apparatus for disposing of used ion exchange resin, which are capable of disposing of large amounts of used ion exchange resin more efficiently than conventional methods. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a flow chart showing the process flow of the method for disposing of used ion exchange resin according to the first embodiment. [Diagram 2] FIG. 1 is a diagram showing a schematic configuration of a used ion exchange resin disposal device according to a first embodiment. [Diagram 3] 1 is a graph showing a change in molecular weight of an ion exchange resin due to exposure to atmospheric pressure non-equilibrium plasma. [Figure 4] 1 is a graph showing the relationship between the degree of crosslinking and the swelling pressure of a cation exchange resin. [Diagram 5] FIG. 11 is a flow chart showing the process flow of a method for disposing of used ion exchange resin according to a second embodiment. [Figure 6] FIG. 11 is a flow chart showing the process flow of a method for disposing of used ion exchange resin according to a third embodiment. [Figure 7] FIG. 11 is a flow chart showing the process flow of a method for disposing of used ion exchange resin according to a fourth embodiment. [Figure 8] FIG. 13 is a flow chart showing the process flow of a method for disposing of used ion exchange resin according to a fifth embodiment. [Figure 9] FIG. 13 is a flow chart showing the process flow of a method for disposing of used ion exchange resin according to a sixth embodiment. [Figure 10] FIG. 13 is a flow chart showing the process flow of a method for disposing of used ion exchange resin according to the seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a method for disposing of used ion exchange resin and an apparatus for disposing of used ion exchange resin according to an embodiment will be described with reference to the drawings.

[0016] (First embodiment) First, a method for disposing of used ion exchange resin and an apparatus for disposing of used ion exchange resin according to a first embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a flow diagram showing the process flow of the method for disposing of used ion exchange resin according to the first embodiment, and Fig. 2 is a diagram showing a schematic configuration of the apparatus for disposing of used ion exchange resin according to the first embodiment.

[0017] As shown in Fig. 1, in the first embodiment and the second to seventh embodiments described later, a plasma irradiation process 102 is performed in which plasma is irradiated to used ion exchange resin 101 in which radioactive substances have been ion-exchanged. The main purpose of this plasma irradiation process 102 is not to reduce the volume of the resin by incineration and mineralization, but to cut bonds (crosslinked structures) in the resin composed of polymers and reduce the swelling property of the resin.

[0018] An example of the plasma used in the plasma irradiation step 102 is atmospheric pressure non-equilibrium plasma. The atmospheric pressure non-equilibrium plasma is a plasma in which only the electron temperature is high (for example, tens of thousands of degrees Celsius or higher), while the ion temperature and gas temperature are about room temperature, and can be generated by applying electrical energy in a gas atmosphere such as air. In this case, plasmas such as glow discharge plasma, barrier discharge plasma, arc discharge plasma, high-frequency induction plasma, and corona plasma can be used.

[0019] When atmospheric pressure non-equilibrium plasma is used, a device requiring high temperature, high pressure, and high vacuum is not required, and a device with a simple configuration can be used. Note that the form of plasma called atmospheric pressure non-equilibrium plasma is presented as an example, and other forms of plasma can be used in the plasma irradiation process 102. However, as described above, the plasma irradiation process 102 is not intended to incinerate and mineralize the resin, but rather to cut the bonds (crosslinked structure) of the resin composed of polymers and reduce the swelling property of the resin, so it is preferable to use a plasma that can efficiently achieve this purpose.

[0020] Next, the used ion exchange resin (hereinafter referred to as used ion exchange resin residue) 103 that has been subjected to the plasma irradiation step 102 is subjected to a compression and volume reduction step 104 in which the used ion exchange resin residue 103 is compressed and reduced in volume.

[0021] As shown in FIG. 2, the used ion exchange resin disposal device includes a used ion exchange resin storage tank 1, a transfer line 2 (shown as 2-1 and 2-2 in FIG. 2), a plasma generator 3, a plasma irradiation section 4, and a compression volume reduction device 5.

[0022] The transfer line 2 is composed of a mechanism for physically transferring the used ion exchange resin 101 and the residue 103 of the used exchange resin, such as a screw conveyor or a belt conveyor. The compressive volume reduction device 5 includes a transfer device 6 to a waste container 6a and a compression device 7 for compressing and reducing the volume of the ion exchange resin residue 103. As shown in FIG. 2, the compressive volume reduction device 5 may also include a solidification device 8 for injecting a solidification agent to solidify the ion exchange resin residue 103. In the example of FIG. 2, a radiation dose monitoring unit 9 is provided in each of the used ion exchange resin storage tank 1, the plasma irradiation unit 4, and the compressive volume reduction device 5, enabling safe processing while monitoring the radiation dose.

[0023] In the waste disposal device for used ion exchange resin having the above-mentioned configuration, the used ion exchange resin 101 transferred from the used ion exchange resin storage tank 1 to the plasma irradiation section 4 via the transfer line 2-1 is irradiated with plasma generated by the plasma generator 3. After the plasma irradiation, the residue 103 of the used exchange resin is transferred to the compression volume reduction device 5 via the transfer line 2-2.

[0024] In the compression and volume reduction device 5, the residue 103 of the used exchange resin is compressed and reduced in volume by the compression device 7 before or after being transferred to the waste container 6a. After this, it is solidified as necessary by the solidification device 8. When compressing and reducing the volume by the compression device 7 after transferring the residue 103 of the used exchange resin to the waste container 6a, as described below, the residue 103 of the used exchange resin is compressed and reduced in volume together with the waste container 6a in a state in which the residue 103 of the used exchange resin is contained in the waste container 6a.

[0025] As described above, in this embodiment, the used ion exchange resin 101 is subjected to the plasma irradiation process 102 to break the bonds of the resin. The results of an experiment conducted to confirm the change in molecular weight of the ion exchange resin due to the irradiation of such atmospheric pressure non-equilibrium plasma are shown in the graph of FIG.

[0026] The ion exchange resin used was a sample made by mixing a cation exchange resin and an anion exchange resin in a 1:1 ratio, adding water to the mixture so that the water content was 70%, and molding the mixture.

[0027] The plasma used was a plasma jet, which was a low-temperature plasma created by a gas flow using an arc discharge as a seed. The irradiation conditions were nitrogen gas flow rate of 40 L / min, power of 490 W, irradiation distance between the nozzle and the sample of 20 mm, and irradiation time of several tens of seconds to irradiate the entire sample, but irradiation time to the same location was only several seconds.

[0028] The graph in Figure 3 shows a comparison of the molecular weight distribution of the resin eluted before and after exposure to atmospheric pressure non-equilibrium plasma, as measured by gel permeation chromatography (GPC). The dotted line indicates the distribution before exposure, and the solid line indicates the distribution after exposure. In GPC analysis, the target resin is placed in a solvent and the molecular weight of the dissolved components is analyzed, but ion exchange resins are difficult to dissolve, and polymeric components that are difficult to dissolve tend to be difficult to observe. In the graph in Figure 3, the distribution of polymeric components increases in the sample after plasma exposure compared to the sample before plasma exposure. This can be said to be because the polymeric components that were outside the observation range in the sample before plasma exposure became observable in the sample after plasma exposure because the resin bonds were cut by plasma exposure, reducing the molecular weight. In this way, it is possible to cut the bonds (crosslinked structure) of ion exchange resins by exposure to atmospheric pressure non-equilibrium plasma.

[0029] The relationship between the degree of crosslinking of a cation exchange resin and the swelling pressure is shown in documents such as "F. Helfferich, Ion exchange, McGraw-Hill Book Company, Inc., 1962" and is shown in the graph of FIG. 4. The degree of crosslinking is the ratio of divinylbenzene (DVB) in the polymer matrix in the resin. As shown in the graph of FIG. 4, the swelling pressure increases as the degree of crosslinking increases. When the crosslinked structure of the resin is cut by plasma irradiation, the swelling property of the resin decreases. This makes it possible to reduce the amount of solidifying agent required to withstand the swelling pressure in the solidification process, and allows a larger amount of used exchange resin residue 103 to be disposed of relative to the capacity of the waste container 6a.

[0030] Furthermore, the springback that occurs when compressing the resin is reduced, making it easier to reduce the volume of the resin by compression and volume reduction treatment. In this way, by reducing the amount of solidifying agent and reducing the volume of the used ion exchange resin residue 103 itself, a large amount of used ion exchange resin 101 can be efficiently disposed of, improving the economic efficiency of disposal. In addition, when radioactive materials are separated by plasma irradiation, the radioactivity concentration decreases, making it possible to reduce processing costs.

[0031] Second embodiment Hereinafter, a second embodiment of the method for disposing of used ion exchange resin will be described with reference to Fig. 5. Fig. 5 is a flow chart showing the process flow of the method for disposing of used ion exchange resin according to this embodiment.

[0032] 5, in the second embodiment, a plasma irradiation step 102 is performed on used ion exchange resin 101, and then a transfer step 105 is performed on a residue 103 of the used ion exchange resin to a waste container 6a. Then, a compression and volume reduction step 104 is performed in which the waste container 6a containing the residue 103 of the used ion exchange resin is compressed to produce a waste body 106 with a reduced volume by compression. A drum can or the like can be used as the waste container 6a.

[0033] In the second embodiment having the above configuration, the residue 103 of the plasma-irradiated used ion exchange resin is compressed and reduced in volume to become the waste body 106, so that the volume of the residue 103 of the used ion exchange resin to be disposed can be reduced. Even in this case, the springback of the resin is reduced by the plasma irradiation step 102 compared to unirradiated resin, and the volume of the waste body can be reduced by compression, so that a larger amount of the used ion exchange resin 101 can be disposed, improving the economic efficiency of disposal. In addition, radioactive contamination of the compression device 7 can be reduced by compressing the waste container 6a as well.

[0034] Third embodiment Hereinafter, a third embodiment of the method for disposing of used ion exchange resin will be described with reference to Fig. 6. Fig. 6 is a flow chart showing the process flow of the method for disposing of used ion exchange resin according to this embodiment.

[0035] As shown in FIG. 6, in the third embodiment, similarly to the second embodiment, a compression and volume reduction process 104 is performed in which the residue 103 of the used ion exchange resin that has been subjected to the plasma irradiation process 102 is compressed and reduced in volume together with the waste container 6a to produce multiple waste bodies 106, and a transfer process 107 to a second waste container is performed in which these are transferred to another second waste container to produce a second waste body 108 containing the multiple waste bodies 106.

[0036] In the third embodiment having the above configuration, by using the second waste body 108 containing a plurality of waste bodies 106, the residue 103 of the used ion exchange resin is doubly enclosed by the waste body 106 compressed together with the container and the second waste body 108, thereby increasing physical shielding against radioactive substances and further strengthening the containment of the residue 103 of the used ion exchange resin containing radioactive substances, thereby reducing the risk of leakage of the radioactive substances.

[0037] (Fourth embodiment) Hereinafter, a fourth embodiment of the method for disposing of used ion exchange resin will be described with reference to Fig. 7. Fig. 7 is a flow chart showing the process flow of the method for disposing of used ion exchange resin according to this embodiment.

[0038] 7, in the fourth embodiment, similarly to the third embodiment, the plasma irradiation step 102 is performed, and the ion exchange resin residue 103 is compressed together with the container to produce a plurality of waste bodies 106. The waste bodies 106 are then transferred to a second waste container in a transfer step 107, and stored in the second waste container. Thereafter, a solidification step 109 is performed in which a solidification agent is injected into the gaps in the second waste container to produce second waste bodies 108. As the solidification agent, for example, cement, glass, plastic, etc. can be used, but the solidification agent is not limited thereto.

[0039] In the fourth embodiment having the above configuration, a solidifying agent is injected into the gaps between the waste bodies 106 containing the residue 103 of the used ion exchange resin to solidify the waste bodies 106, thereby increasing the physical shielding against radioactive substances. In addition, by carrying out the solidification step 109, the residue 103 of the used ion exchange resin containing the radioactive substances can be more firmly contained, thereby reducing the risk of leakage of the radioactive substances.

[0040] Fifth embodiment Hereinafter, a fifth embodiment of the method for disposing of used ion exchange resin will be described with reference to Fig. 8. Fig. 8 is a flow chart showing the process flow of the method for disposing of used ion exchange resin according to this embodiment.

[0041] As shown in FIG. 8, in this embodiment, the residue 103 of the used ion exchange resin that has been subjected to the plasma irradiation process 102 is subjected to a compression and volume reduction process 104 for compressing and reducing the volume, and then a transfer process 105 to a waste container for storage in the waste container 6a is performed to produce a waste body 106.

[0042] In the fifth embodiment having the above configuration, the volume of the plasma-irradiated residue 103 of the used ion exchange resin is reduced by compressing and reducing the volume in the compression and reduction step 104, and the amount of the residue 103 of the used ion exchange resin put into the waste container 6a is increased, making it possible to more efficiently dispose of a large amount of used ion exchange resin 101. Furthermore, compared to the case where the residue 103 of the used ion exchange resin is compressed together with the waste container 6a, the residue 103 of the used ion exchange resin is directly compressed, making it easier to compress and reduce the volume.

[0043] Sixth embodiment Hereinafter, a sixth embodiment of the method for disposing of used ion exchange resin will be described with reference to Fig. 9. Fig. 9 is a flow chart showing the process flow of the method for disposing of used ion exchange resin according to this embodiment.

[0044] 9, in the sixth embodiment, similarly to the fifth embodiment, the residue 103 of the used ion exchange resin that has been subjected to the plasma irradiation step 102 is subjected to a compression volume reduction step 104 for volume reduction, and then a transfer step 105 to a waste container for storing in the waste container 6a is performed. After that, a solidification step 109 is performed in which a solidification agent is injected into the waste container 6a and the residue and the solidification agent are kneaded to produce a waste body 106.

[0045] In the sixth embodiment having the above configuration, the volume of the plasma-irradiated residue 103 of the used ion exchange resin is reduced by compressing and reducing the volume in the compression and volume reduction step 104, thereby increasing the amount of the residue 103 of the used ion exchange resin put into the waste container 6a, and making it possible to more efficiently dispose of a large amount of the used ion exchange resin 101. In addition, by performing the solidification step 109 in which a solidifying agent is injected into the waste container 6a to solidify it, physical shielding against radioactive substances is increased, and the containment of the residue 103 of the ion exchange resin containing the radioactive substances is further strengthened, thereby reducing the risk of leakage of the radioactive substances.

[0046] Seventh embodiment Hereinafter, the seventh embodiment of the method for disposing of used ion exchange resin will be described with reference to Fig. 10. Fig. 10 is a flow chart showing the process flow of the method for disposing of used ion exchange resin according to this embodiment.

[0047] 10, in the seventh embodiment, similarly to the second embodiment, the residue 103 of the used ion exchange resin that has been subjected to the plasma irradiation step 102 is transferred to a waste container 6a in a transfer step 105, and the waste container 6a containing the residue 103 of the used ion exchange resin is compressed in a compression volume reduction step 104. Thereafter, a solidification step 109 is performed in which a solidification agent is injected into the waste container 6a and the residue and the solidification agent are mixed together to produce a waste body 106.

[0048] In the seventh embodiment having the above configuration, the volume of the plasma-irradiated residue 103 of the used ion exchange resin is reduced by compressing and reducing the volume in the compression and volume reduction step 104, thereby increasing the amount of the residue 103 of the used ion exchange resin put into the waste container 6a, and making it possible to more efficiently dispose of a large amount of the used ion exchange resin 101. In addition, by performing the solidification step 109 in which a solidifying agent is injected into the waste container 6a to solidify it, physical shielding against radioactive substances is increased, and the containment of the residue 103 of the ion exchange resin containing the radioactive substances is further strengthened, thereby reducing the risk of leakage of the radioactive substances.

[0049] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0050] 1...used ion exchange resin storage tank, 2...transfer line, 3...plasma generator, 4...plasma irradiation section, 5...compression volume reduction device, 6...transfer device to waste container, 7...compression device, 8...solidification device, 9...radiation dose monitoring section.

Claims

1. a plasma irradiation step of irradiating the used ion exchange resin with plasma; a compression and volume reduction step of compressing and reducing the volume of the used ion exchange resin irradiated with plasma in the plasma irradiation step; A method for disposing of used ion exchange resin, comprising:

2. In the plasma irradiation step, atmospheric pressure non-equilibrium plasma is used.

2. The method for disposing of used ion exchange resin according to claim 1.

3. In the compression and volume reduction step, the used ion exchange resin is placed in a waste container and compressed together with the waste container to produce a waste body.

3. The method for disposing of used ion exchange resin according to claim 1 or 2.

4. The waste body produced in the compressive volume reduction step is accommodated in a second waste container to form a second waste body.

4. The method for disposing of used ion exchange resin according to claim 3.

5. A solidification step of injecting a solidification agent into the second waste container containing the waste bodies.

5. The method for disposing of used ion exchange resin according to claim 4.

6. The method includes a step of transferring the used ion exchange resin compressed and reduced in volume in the compression and volume reduction step to a waste container and storing the same therein.

3. The method for disposing of used ion exchange resin according to claim 1 or 2.

7. A solidification step of injecting a solidification agent into the waste container is provided after the transfer step into the waste container.

7. The method for disposing of used ion exchange resin according to claim 6.

8. A used ion exchange resin disposal device, comprising: A plasma generating device that generates plasma; a plasma irradiation unit that irradiates the used ion exchange resin with the plasma generated by the plasma generator; A compression and volume reduction device that compresses and reduces the volume of the used ion exchange resin irradiated with plasma by the plasma irradiation unit; A used ion exchange resin disposal device comprising:

9. The plasma generating device generates atmospheric pressure non-equilibrium plasma.

9. The device for disposing of used ion exchange resin according to claim 8.

10. a used ion exchange resin storage tank for storing the used ion exchange resin; A transfer line for transferring the used ion exchange resin from the used ion exchange resin storage tank to the plasma irradiation unit and from the plasma irradiation unit to the compression volume reduction device; a solidification device for injecting a solidification agent into the waste container to solidify it; 10. The waste disposal device for used ion exchange resin according to claim 8 or 9, further comprising:

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