JP5044178B2 - Radionuclide-containing waste liquid treatment method and apparatus - Google Patents

Description

  The present invention relates to a radionuclide-containing waste liquid treatment method for a nuclear power plant. In particular, radionuclides and organic impurities, which were difficult to remove with conventional waste liquid treatment systems, can be removed sufficiently. High purity of recovered water, cleaner waste liquid recovery system, reduced burden on workers, and reduced exposure. An object of the present invention is to provide a radionuclide-containing waste liquid treatment method and apparatus that can be expected to reduce the running cost.

  In a nuclear power plant, in order to purify and reuse the generated waste liquid, a filtration apparatus and a concentrator such as a waste liquid desalination apparatus and a hollow fiber membrane filter that use an ion exchange resin are usually installed as purification equipment.

  Waste liquid generated in nuclear power plants contains radionuclides such as Co60, ionic impurities, suspended corrosion products, and organic impurities. All waste liquid is collected in a tank for purification. Is going. Waste liquid collected in the tank includes equipment drain water such as reactor water and rotating equipment seal water, floor drain water such as floor cleaning waste liquid, regenerated waste liquid generated by backwashing and passing medicines of ion exchange resin, and from hot labs. There are various types of waste liquid such as waste liquid. In addition to waste liquid collection tanks and recovery tanks, there are many facilities that store water in nuclear power plants, such as fuel pools, site bunker pools, and suppression chambers. These waters also need to be purified.

  These waste liquids have different treatment methods depending on their properties. Filtration treatment is performed for waste liquids with a large amount of suspended solids, and concentration treatment using an evaporator is performed for waste liquids with high ion concentration. It is processed and recovered and reused by a waste liquid desalinator filled with resin.

  In recent nuclear power plants, cleanup of the entire plant has been promoted, and it is indispensable to prevent radioactivity from being detected for purification of radioactive liquid waste. This is because in the periodic inspection of the plant, the presence of the radionuclide leads to an increase in the equivalent dose of radiation exposure to workers and also causes a reduction in work efficiency. Further, it is required to reduce organic impurities as much as possible. This is because organic impurities may contain S elements and N elements, and when these flow into the system, they decompose by heat and become nitrate ions and sulfate ions, deteriorating the water quality and causing corrosion of equipment components. It is because it causes.

  However, the waste liquid treatment equipment that has been installed in the past is designed mainly for the removal of ionic impurities such as Na and Cl and metal oxides. It is not assumed that the following will be removed. Also, the problem of organic impurities has recently become apparent, and no attempt is made to remove it. For this reason, in a waste liquid desalination apparatus using a granular ion exchange resin installed for the purpose of final purification of treated water, it cannot be said that the removal rate of radionuclides and organic impurities present in trace amounts is sufficient. Furthermore, since organic impurities are eluted from the ion exchange resin itself, it is inevitable that a trace amount of organic impurities is present in the recovered liquid.

  Furthermore, in the current wastewater desalination equipment, when the radionuclide concentration and organic impurities show a tendency to breakthrough, the removal ability is recovered by carrying out the regeneration of the filled ion exchange resin with chemicals. Regenerated chemicals are generated as a secondary waste liquid, and it is necessary to treat the recycled waste liquid. Since a large amount of sulfuric acid and caustic soda are used to regenerate the ion exchange resin, a huge amount of waste containing sodium sulfate is generated. In addition, when the ion exchange resin is replaced without regeneration, the used ion exchange resin is exposed to radioactivity and becomes a radioactive solid waste, and this disposal becomes a problem. On the other hand, the concentrator has a high ability to remove radionuclides, but has a low processing capacity, and is not sufficient in capacity for processing waste liquid generated in large quantities in the plant. In addition, volatile organic substances having a low boiling point cannot be removed due to the evaporation treatment, and are mixed into the condensed water, and measures for these problems are also required.

  So far, radionuclide removal apparatuses using activated carbon have been proposed as described in Patent Documents 1 to 3, and a technique using a granular inorganic adsorbent as described in Patent Document 4 has been proposed. Although proposed, the devices according to these proposals still do not sufficiently satisfy the above-mentioned problems and sufficiently satisfy the required performance.

  Further, Patent Document 5 proposes an electric regenerative purification device in which a granular ion exchange resin is filled between ion exchange membranes instead of a waste liquid desalination device filled with an existing ion exchange resin. The above-mentioned problems have not been sufficiently solved and the required performance has not been sufficiently satisfied.

  Since the electric regenerative purification device continuously regenerates the ion exchange resin by electricity, there is no need to regenerate with chemicals when the ion load increases like a general granular ion exchange resin demineralizer, It is widely used as a general water treatment apparatus instead of a granular ion exchange resin type desalination apparatus. In an electric regeneration type desalination apparatus used as a general water treatment apparatus, a desalination chamber and a concentration chamber are filled with a granular ion exchange resin. Examples of commercially available devices include “KCDI” from Kurita Kogyo Co., Ltd. and “D2EDI” from Organo Corporation. In application to general water treatment, there is no problem because the substance to be removed is an ionic impurity such as a cation such as sodium ion or calcium ion or an anion such as chlorine ion. However, in nuclear power plants, Co-60, Co-58, Mn-54, Fe-59, which leaks without being removed by the granular ion exchange resin-filled waste liquid desalination equipment equipped in the existing waste liquid treatment system. It is difficult to remove organic impurities such as radioactive nuclides such as Cr-51, effluents from ion exchange resins, and volatile components from paints with an electric regenerative purification device for general water treatment. In addition, when an electric regeneration type purification device in which a granular ion exchange resin is filled in a desalination chamber or a concentration chamber is applied instead of an ion exchange resin type desalination device, not only the above-mentioned radionuclides and organic impurities cannot be removed. As described in Patent Document 5, since a lot of concentrated waste liquid is generated due to the exclusion of ions, it is necessary to install a concentrating device such as an evaporator for this treatment, which is a huge burden in terms of cost. .

In general, an electric regenerative purification apparatus supplies concentrated liquid and electrode liquid at a flow rate substantially equal to that of supply water in order to obtain pure water. This is because industrial water, river water, and groundwater are used as raw water to be supplied to pure water production equipment in general industries, so the water contains a lot of hardness components such as Ca and Mg and silica. This is because, if treated with an electric regenerative purifier, an event may occur where the flow rate cannot be ensured due to precipitation on the concentrated liquid side and the flow rate cannot be secured, or the current efficiency is reduced and a high voltage needs to be applied. .
Japanese Patent Laid-Open No. 5-168917 JP-A-6-343856 JP-A-10-170696 JP 2004-45371 A JP-A-6-3495

  The object of the present invention is to sufficiently remove radionuclides and organic impurities that have been difficult to remove with conventional waste liquid treatment systems, and to improve the purity of the recovered water, clean the waste liquid recovery system, and reduce the burden on workers. Another object of the present invention is to provide a radionuclide-containing waste liquid treatment method and apparatus from a nuclear power plant that can be expected to have effects such as reduction of exposure and reduction of running cost.

  As a result of intensive studies, the present inventors have found that heavy metals such as cobalt and manganese, which are radionuclides, easily form chelates with sulfate ions, organic substances, and the like that are present in waste liquids. As a result of further study, it was found that radioactive heavy metals and organic impurities in the waste liquid have a low reaction rate and are difficult to remove.

  As a result of earnestly researching and developing electric regenerative purification equipment for nuclear power plants that efficiently removes radionuclides and organic impurities, the amount of radioactive heavy metals present in the waste liquid in nuclear power plants is slightly increased. It was found that it can be removed by using an electric regenerative purifier having a desalting chamber filled with ion exchange fibers whose surface area is much larger than that of the granular ion exchange resin. Further, the present inventors have found that organic impurities are extremely slightly negatively charged and can be removed by using an electric regenerative purification apparatus having a desalting chamber filled with ion exchange fibers. Based on these findings, the present inventors applied an electric regenerative purification device filled with ion exchange fibers to the subsequent stage of a waste liquid desalination device filled with a granular ion exchange resin to remove radionuclides and organic impurities. It was conceived to remove efficiently and treat the waste liquid with high purity.

  This invention is made | formed based on this knowledge, The said objective is achieved by providing the following structures.

  The present invention includes a waste liquid primary treatment apparatus including a waste liquid filtration apparatus and / or a waste liquid desalination apparatus using a granular ion exchange resin, and an anode and a cathode at a subsequent stage of the waste liquid primary treatment apparatus, and a cation therebetween. A plurality of desalting chambers and concentration chambers and a pair of electrode chambers formed by alternately arranging exchange membranes and anion exchange membranes are formed, and any one of the desalting chambers, the concentration chambers, and the electrode chambers One or more ion-exchange fibers are filled, and an electric regenerative purification device that can be desalted by passing water to be treated in a state where a direct current is applied, from a nuclear power plant Provided is a radionuclide-containing waste liquid treatment apparatus (hereinafter, may be abbreviated as “radioactive waste liquid treatment apparatus”) that can treat a waste liquid containing a radionuclide.

  The present invention also relates to a method for treating a waste liquid containing a radionuclide from a nuclear power plant, wherein the waste liquid undergoes a primary treatment by filtration and / or ion exchange to obtain a primary treated water, and the waste liquid. After the primary treatment step, a plurality of desalting chambers and concentrating chambers and a pair of electrode chambers are formed by having an anode and a cathode and alternately arranging a cation exchange membrane and an anion exchange membrane between them. The primary treated water is supplied in a state where a direct current is applied using an electric regeneration type purifying apparatus in which any one or more of the desalting chamber, the concentrating chamber, and the polar chamber are filled with ion exchange fibers. The present invention provides a method for treating a radionuclide-containing waste liquid characterized by performing an electric regeneration type purification step of passing water as treated water and performing a secondary treatment to remove the radionuclide.

  According to the radionuclide-containing waste liquid treatment method and apparatus of the nuclear power plant of the present invention, it is possible to sufficiently remove radionuclides and organic impurities that have been difficult to remove by conventional waste liquid treatment systems, and to improve the purity of recovered water, It is expected that the waste liquid recovery system will be cleaned, the burden on workers and exposure will be reduced, and the running cost will be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

  Here, FIG. 1 is a schematic view showing an outline of a preferred embodiment of the radionuclide-containing waste liquid treatment apparatus of the present invention. FIG. 2 is a schematic view showing an embodiment of an electric regeneration type purification apparatus used in the radionuclide-containing waste liquid treatment apparatus shown in FIG. FIG. 3 is a schematic view showing the outline of another embodiment of the radionuclide-containing waste liquid treatment apparatus of the present invention. FIG. 4 is a schematic view showing an outline of still another embodiment of the radionuclide-containing waste liquid treatment apparatus of the present invention. FIG. 5 is a schematic view showing a main part of another embodiment of the radionuclide-containing waste liquid treatment apparatus of the present invention. FIG. 6 is a schematic view showing the main part of another embodiment of the radionuclide-containing waste liquid treatment apparatus of the present invention.

  A radionuclide-containing waste liquid treatment apparatus of the form shown in FIG. 1 includes a radionuclide-containing waste liquid collection tank 1 for collecting radionuclide-containing waste liquid, a pump 2 for transferring the radionuclide-containing waste liquid, and a radionuclide via the pump 2. A hollow fiber membrane filter 3 as a radionuclide-containing waste liquid filtration device connected to the waste liquid collection tank 1 and a granular ion-exchange resin type desorber connected so that the radionuclide-containing waste liquid flows from the hollow fiber membrane filter 3 A waste liquid primary treatment apparatus I including a salt apparatus 4 is provided. Further, the ion-exchange fiber-filled electric regenerative purification device 8 (hereinafter simply referred to as “the primary treatment water (containing radionuclide)) treated by the waste liquid primary treatment device I is connected to the waste liquid primary treatment device I so as to flow in. "Electric regeneration purification equipment" is installed. A liquid sampling tank 5 for confirming that the treated liquid processed by the electric regenerative purification apparatus 8 is sampled and purified is connected to the subsequent stage of the electric regenerative purification apparatus 8. The double water storage tank 7 is connected to which the treated liquid that has been confirmed to be purified is transferred via the pump 6.

  As the hollow fiber membrane filter 3 and the granular ion exchange resin type waste liquid demineralizer 4, generally known ones can be used without particular limitation.

  In the present invention, by installing the electric regenerative purification device 8, radionuclides such as Co-60, Co-58, Mn-54, Fe-59, and Cr-51, which have been difficult to remove with the existing waste liquid treatment system. In addition, organic impurities such as eluate from the ion exchange resin and volatile components from the paint can be efficiently removed.

  Next, the electric regenerative purification device 8 will be described with reference to FIG. As shown in FIG. 2, the electric regenerative purification device 8 has an anode (+) and a cathode (−), and is formed by alternately arranging a cation exchange membrane C and an anion exchange membrane A therebetween. A plurality of desalting chambers and concentrating chambers and a pair of polar chambers, and any one or more of the desalting chambers, the concentrating chambers and the polar chambers are filled with ion exchange fibers, In this state, the water to be treated can be passed through and demineralized. In the electric regenerative purification apparatus 8 shown in FIG. 2, the anion exchange nonwoven fabric 81 and the cation exchange nonwoven fabric 82 are alternately stacked and filled in the desalting chamber and the concentration chamber so as to be orthogonal to the flow direction of the water to be treated. Yes. By passing water to be treated through each chamber from the direction of the arrow in FIG. 2 in a state where a direct current is applied, concentrated water is discharged from the polar chamber and the concentrating chamber, and demineralized water is discharged from the desalting chamber. The filling method of the ion exchange fiber is not limited to the illustrated form, and only the anion exchange nonwoven fabric 81 or the cation exchange nonwoven fabric 82 may be laminated so as to be orthogonal to the flow direction of the water to be treated.

  As the ion exchange fiber used in the electric regenerative purification apparatus, an electron beam, radiation or ultraviolet ray, preferably radiation is used for a woven or non-woven base material made of olefin polymer fiber such as polyethylene or polypropylene. Strong acidic functional groups such as sulfone groups, strong basic functional groups such as quaternary ammonium bases, non-strong acidic functional groups such as phosphoric acid groups, carboxyl groups, nonionic hydrophilic groups and primary to tertiary amino groups, or non-strong A synthetic fiber having a fiber diameter of 0.5 to 50 μm formed by graft polymerization (preferably radiation graft polymerization) of a basic functional group can be preferably used.

  If the fiber diameter is less than 0.5 μm, the water flow resistance increases, and the pressure loss is large as a filtering material, which is not suitable. When the fiber diameter exceeds 50 μm, the surface area becomes large, which is not suitable as an ion exchange material.

  The cation exchange fibers and the anion exchange fibers are alternately filled in a direction perpendicular to the flow direction of the water to be treated. Thereby, the desalination treatment efficiency can be improved, the applied current can be reduced, and the apparatus can be made compact.

  Further, by filling the ion exchange fiber, it is possible to achieve a more compact size than the conventional electric regenerative purification device filled with the granular ion exchange resin. This is considered to be because the ion exchange fiber diameter is about one-hundred compared with the granular ion exchange resin, and the surface area is the square of the ion exchange fiber, so that the ion exchange reaction rate is overwhelmingly advantageous. Furthermore, by filling at least the cation ion exchange fiber and the anion ion exchange fiber in the desalting chamber in a laminated state in a direction perpendicular to the flow direction of the water to be treated, the desalting treatment efficiency is improved, the applied current is reduced, Further downsizing of the apparatus can be achieved.

  A hollow fiber membrane filter or a granular ion exchange resin is used for the treatment of the conventional radioactive liquid waste. However, since the hollow fiber membrane filter has no ion exchange ability, it has little ability to remove ionic impurities. The granular ion exchange resin is a strongly acidic cation exchange resin and a strongly basic anion exchange resin having a diameter of about 0.3 to 1.2 mm, and has a certain ability to adsorb ions existing in water, but has a small surface area. For this reason, the reaction rate is low, and the ability to remove radionuclides and organic impurities present in trace amounts is not sufficient.

  In order to remove these radionuclides and organic impurities, the waste liquid treatment apparatus of the present invention is an electric regenerative purification apparatus in which ion exchange fibers are filled in any one or all of a desalting chamber, a concentration chamber, and an electrode chamber. Is installed in the subsequent stage of the existing granular ion exchange resin-filled waste liquid primary treatment apparatus 4. The electric regenerative purification device 8 cannot be removed by the granular ion exchange resin-filled waste liquid primary treatment device 4 because the desalination chamber is filled with ion exchange fibers having a larger surface area than the granular ion exchange resin under a DC power source. Impurities such as radioactive heavy metals and organic substances can be efficiently removed.

  As an electric regeneration type purifier filled with such ion exchange fibers, there is a trade name “GDI” manufactured by Ebara Corporation. GDI is an electric regenerative purification device in which a desalting chamber or the like is filled with an ion exchange nonwoven fabric produced by radiation graft polymerization instead of an ion exchange resin, and the desalting rate is greatly improved as compared with the conventional one.

  Next, another embodiment of the present invention will be described. In the following description of the apparatus, portions different from the embodiment shown in FIG. 1 will be particularly described. The description in the embodiment shown in FIG. 1 described above is appropriately applied to portions that are not particularly described.

  The embodiment shown in FIG. 3 is an embodiment in which the impurity-containing water in the tank is circulated through an electric regenerative purification device. In the form shown in FIG. 3, the granular ion exchange resin-filled waste liquid primary treatment device 4 and the liquid sampling tank 5 are directly connected, and the electric regenerative purification device 8 is connected to the liquid sampling tank 5 via a pump 12. It is connected so that can be circulated.

  The embodiment shown in FIG. 4 is an embodiment in which the electric regenerative purification device is unitized. In the form shown in FIG. 4, a pipe cleaning device 9 is installed in front of the hollow fiber membrane filter 3, and a processed liquid recovery tank 11 into which a processed liquid discharged from the electric regenerative purification device 8 is introduced. Is provided.

  Next, with reference to FIG. 5, the form which accommodated the electric regenerative purification apparatus 8 in containers, such as an overpack, is demonstrated.

  The entire electric regenerative purification device 8 shown in FIG. 5 is housed in an overpack container 14, and the electric regenerative purification device 8 is joined to external piping by a plurality of joints 22 such as flanges or quick couplers. Has been.

  The overpack container 14 accommodates the electric regenerative purification device 8 therein, prevents leakage of radionuclide-containing waste liquid from the joint and the main body of the electric regenerative purification device 8 to the outside, and can be sealed. Any material can be used.

  In the present embodiment, in order to prevent leakage of the radionuclide-containing waste liquid to the outside, a leak detector 15 connected from the lower part of the overpack container 14 via a detection pipe is installed, and the radionuclide-containing waste liquid is contained. When the waste liquid leaks, the operation of the apparatus can be automatically stopped by contact with the leak detector 15.

  In addition, an installation stand 16 is provided between the bottom portion of the overpack container 14 and the electric regenerative purification device 8 from the viewpoint of preventing liquid contact of the electric regenerative purification device 8 at the time of leakage of radionuclide-containing waste liquid and preventing damage to the apparatus main body. ing.

  Normally, the main body of the electric regenerative purification device 8 has a structure in which a plurality of ion exchange membranes, non-woven fabrics, etc. are sandwiched by a frame and fixed to both end plates with a plurality of through bolts. High potential (possibility of leakage). Therefore, in order to apply to a nuclear power plant as in this embodiment, a part or the whole of the electric regenerative purification device 8 is accommodated in a container 14 such as an overpack, and sufficient consideration is given to leakage of radioactive waste liquid. It is preferable to do. Furthermore, it is more preferable to install a detector for detecting leakage during operation, and to take measures to automatically stop the water flow to the device should a leakage occur during operation.

  FIG. 6 shows another embodiment of the configuration between the waste liquid treatment apparatus and the liquid sampling tank.

  The embodiment shown in FIG. 6 includes an electric regenerative purification device 8 and an overpack container 14 that houses the entire electric regenerative purification device 8. The electric regenerative purification device 8 inside the overpack container 14 is connected to the outside by a flange connection. Specifically, the water to be treated (radionuclide-containing waste liquid) receiving tank 19 is connected to the pump 20 and two transfer pipes, and one of them is connected to the water receiving tank 19 to be circulated again. However, the other is connected to the sampling tank via the pump 20. The electric regenerative purification device is connected to the leak detector 15. In addition, piping, valves, instruments, control panels, etc. are also arranged as appropriate.

  In the present embodiment, the flow path A is the anolyte, the flow path B is the water to be treated (waste liquid), the flow path C is the concentrated liquid, and the flow path D is the catholyte flow path. The anolyte and catholyte are respectively collected in the water tank 19 to be treated and processed at the same time. Further, since the concentrated liquid has an increased impurity concentration, the flow path C is connected so as to be collected in a waste liquid receiving tank (not shown) of the existing plant. The water to be treated is treated by an electric regenerative purification device and then collected in a treatment waste liquid collection tank (not shown) of an existing plant and used as pure water.

  In the apparatus of the present embodiment, each apparatus and tank are flange-connected, and the part surrounded by the one-dot chain line in the figure is a portable module so that it can be operated smoothly according to the operation status of the plant. ing. In addition, if the connection valve at the inlet and outlet of the portable module is an electric valve or an air operated valve, it can appropriately correspond to the plant operating condition.

  Next, the processing method of the present invention will be described with reference to FIGS.

  The waste liquid treatment method of the present embodiment transfers the radionuclide-containing waste liquid from the radionuclide-containing waste liquid collection tank 1 to the hollow fiber membrane filter 3 through a pump and performs filtration, and then the granular ion exchange resin waste liquid primary treatment apparatus. 4 is used to perform desalting treatment of the radionuclide-containing waste liquid by ion exchange to obtain a primary treated water, and after the waste liquid primary treatment process, the above-described electric regenerative purification device 8 is used for direct current treatment. It can be carried out by removing the radionuclide by conducting an electrical regeneration purification process in which the primary treated water is passed as treated water and subjected to secondary treatment in a state where current is applied.

  The electric regenerative purification process will be described in detail. The flow rate of the concentrated liquid that is allowed to act on the treated water in the concentration chamber and the flow rate of the polar liquid that is allowed to act on the treated water in the polar chamber are: The water to be treated is preferably continuously flowed at a flow rate of 1/5 or less, more preferably 1/10 to 1/20, or intermittently at a flow rate of 1/5 or less. This is due to the following reason. In other words, the waste liquid generated at nuclear power plants by investigation and research has almost no impurities exceeding 1 mg / L, and in addition, there are almost no hardness components such as Ca and Mg, and silica. Absent. Therefore, almost no precipitation of these components occurs, so there is no problem in the ability to remove radioactive heavy metals and organic impurities even if the concentrated water is 1/5 or less of the water to be treated or intermittent water operation is performed. It was confirmed. In particular, since the concentrated liquid becomes a waste liquid, it is necessary to suppress the amount of the concentrated liquid used as much as possible. In the conventional electric regenerative desalination equipment used in the production of pure water, the flow rate of concentrated water and polar liquid is higher than the flow rate of water to be treated. It is set to about the same level or about 1/2 to suppress this. However, if this is applied to radioactive liquid waste treatment, the concentrated liquid becomes waste liquid and must be processed again in another facility such as an evaporator, reducing the waste liquid to 1/5 or less of the water to be treated. It is important in terms of When concentrated water exceeds 1/5 of the water to be treated, all the radioactive liquid waste is treated with the above-mentioned electric regenerative purification device based on a comparison of the treatment capacity of the ion exchange resin tower and the treatment capacity of the evaporator in the nuclear power plant. However, the concentrated liquid cannot be continuously processed with an evaporator, and the processing efficiency of the waste liquid may be reduced.

  In the case of using the electric regenerative purification apparatus of this embodiment, for example, while applying a direct current of 0.1 to 1 A between both electrodes, the water to be treated (primary treated water containing radionuclide) is flowed at a flow rate of 0.1 to 1 m / h. Concentrated water (primary treated water containing radionuclides) in the desalination chamber at a flow rate of 1/5 or less of the treated water, and polar chamber water (primary treated water containing radionuclides) in 1/5 of the treated water Water is passed through each of the polar chambers at the following flow rate to obtain a treated liquid from the desalting chamber.

  The treated liquid processed by the electric regenerative purification device 8 is transferred to the sampling tank 5, where it is confirmed that it has been sampled and purified. If it is sufficiently purified, the treated liquid is transferred to the double water storage tank 7 via the pump 6. Since the treated liquid transferred to the double water storage tank 7 is pure water, it can be used for various purposes. On the other hand, when purification is insufficient, it is transferred again to the electric regenerative purification device 8 and re-purification is performed.

  In the nuclear power plant, equipment is being cleaned. For example, flushing of equipment and piping before regular inspection with water, and chemical dewashing that dissolves and removes attached metal using chemicals are performed, and waste liquid is generated at that time. The waste liquid generated in these operations is processed in a filtration device and a desalination device using a granular ion exchange resin and recovered in a waste liquid collection pit. By collecting water in the collection pit after passing water, it is possible to remove radionuclides and organic impurities.

  Hereinafter, a processing method when the apparatus of the form shown in FIGS. 3 to 6 is used will be described. However, since the portions different from FIGS. .

  In the treatment method using the apparatus shown in FIG. 3, after the waste liquid primary treatment step, the primary treatment water is temporarily stored in the liquid sampling tank, and the stored primary treatment water is used as the water to be treated. Do.

  In the processing method using the apparatus shown in FIG. 4, the waste liquid generated from the pipe cleaning apparatus 9 is processed. In the pipe cleaning apparatus 9, a nuclear power plant valve or the like is put into the apparatus, and a reducing agent such as oxalic acid or potassium permanganate is used to remove radioactive corrosion oxide adhering to the valve. The waste liquid generated here contains a lot of radionuclides, and finally this is generated as a radioactive liquid waste. About this waste liquid, a waste liquid primary process is performed. Next, an electrical regeneration purification process is performed, and the treated water after the treatment is directly transferred to the waste liquid recovery tank.

  In the treatment method using the apparatus shown in FIG. 5, the water to be treated that has undergone the primary treatment in the waste liquid primary treatment process is injected into the electric regenerative purification device 8 through the joint 22 to perform the electric regenerative purification process in an overpack container. Do it within. At this time, when the waste liquid leaks, the operation of the apparatus is automatically stopped by contact with the leak detector 15. In the figure, the black valve is in a closed state.

  In the treatment method using the apparatus shown in FIG. 6, the treated water subjected to the primary treatment in the waste liquid primary treatment step is stored in the treated water receiving tank 19, and each flow path A to D is passed from the treated water receiving tank 19. Then, an electric regenerative treatment process is performed through the water to be treated through the electric regenerative purification device 8. In the figure, the black valve is in a closed state.

  As described above in detail, the above-described problems in the nuclear power plant can be solved by implementing the processing method of the present invention using the apparatus of the present invention.

  Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not limited to these examples. The radionuclide in nuclear power plants is mainly composed of Co-60, and more than 90% of the total radioactivity is derived from Co-60. In the waste liquid of Example 3 below, of the total radioactivity of 1.6 Bq / mL, Co-60 is 1.5 Bq / mL, and other Co-58, Mn-54, Fe-59, and Cr-51 are slightly present. . Those skilled in the art will readily understand that Co, Fe, and Ni are transition metals of the same group VIII element, and that the same behavior will be obtained if confirmation is made with Co. Also, those skilled in the art can easily understand that Mn, Cr is also an element that exists as an oxide in the neutral region and exists as a + ion in the acidic region, so that it can be considered a substance equivalent to Co. Will. Therefore, in the following examples, Co-60 was verified as a representative radionuclide.

[Examples 1 and 2 (reference example)]
The electric regeneration type purification process was verified by the following experiment.

  In each purification device with the following configuration, 0.2 mg / L cobalt sulfate aqueous solution as Co simulating radioactive heavy metal containing waste liquid, and cation resin elution organic simulating primary treated water obtained from conventional ion exchange resin desalination process Mix the same amount of an aqueous solution containing 200μg / L of impurities (thus, the concentration of Co and organic impurities are 0.1mg / L and 100μg / L, respectively) to make a simulated waste liquid, and measure their removal rate after 2 hours did. The cobalt concentration was measured according to a conventional method using a plasma emission analyzer SPS4000 manufactured by Seiko Denshi Kogyo. Moreover, the organic impurity density | concentration was measured in accordance with the conventional method using the total organic carbon meter TOC5000 by Shimadzu Corporation. The results are shown in Table 1. Here, the reason for using cobalt sulfate aqueous solution as the radioactive heavy metal-containing waste liquid is that Co is the main substance that accounts for 90% or more as the heavy metal in the radioactive waste liquid, and exists as an oxide in the waste liquid in the neutral region. When trapped by filtration and adsorption on the exchange fiber, the functional group is a strong acid having a pH of about 1.3, and thus exists as Co ions.

Comparative Example 1: A column having an inner diameter of 25 mmΦ and a column length of 1200 mm is packed with a granular ion exchange resin (mixed with Dow Chemical's cationic resin HCR-W2 (H) and anionic resin SBR-PC (OH) at a volume ratio of 2: 1). Then, water was passed at 10 L / h through a desalting apparatus having a resin layer with a resin layer height of 1 m. In addition, the flow rate of the desalting chamber influent / concentration chamber inflow / electrode chamber inflow was all 20 L / h. Example 1: Into the electric regenerative purifier shown in FIG. The flow rate of the chamber influent / electrode chamber influent is 20 L / h. Invention 2: The electric regenerative purifier shown in FIG. 2 has a desalination chamber influent flow rate of 20 L / h and the concentration chamber influent. As can be seen from the results shown in Table 1, desalting treatment with granular ion exchange resin and granular ion exchange, which are the prior art, are evident. Compared with the resin-filled electric regenerative purifying apparatus, the present invention is seen to have a high removal rate. It was also confirmed that the removal rate was not affected even if the flow rate of the concentrated chamber influent was reduced.

[Examples 3 and 4]
Using the waste liquid generated in an actual nuclear power plant, a treatment test was conducted to confirm the effect of the electric regeneration type treatment process. The radioactive concentration of the waste liquid used was 1.6 Bq / mL, and the removal rate after 1 hour was measured. The radioactivity concentration was measured using a trade name “SEG-EGS” manufactured by Seiko.

Comparative Example 3: A column with an inner diameter of 30 mmΦ and a column length of 500 mm is packed with granular ion exchange resin (mixed with Dow Chemical's cation resin HCR-W2 (H) and anion resin SBR-PC (OH) at a volume ratio of 2: 1). Then, water was passed through the desalinator having a resin layer with a resin layer height of 1 m at 6 L / h. Example 3: The electric regenerative purification device shown in FIG. Example 4: The flow rate of the desalination chamber inflow is 20 L / h, the concentration chamber inflow and the electrode chamber inflow in the electric regenerative purifier shown in FIG. As can be seen from the results shown in Table 2, the ion exchange fiber filling used in the present invention as compared with the comparative example using the conventional granular ion exchange resin filling desalination apparatus is clear. It can be seen that the removal rate is high when the electric regenerative purifier is used. Further, it can be seen that the removal rate is not affected even if the flow rate of the concentrated chamber influent is reduced in the examples.

FIG. 1 is a schematic diagram showing an outline of a preferred embodiment of the radionuclide-containing waste liquid treatment apparatus of the present invention. FIG. 2 is a schematic view showing an embodiment of an electric regeneration type purification apparatus used in the radionuclide-containing waste liquid treatment apparatus shown in FIG. FIG. 3 is a schematic diagram showing an outline of another embodiment of the radionuclide-containing waste liquid treatment apparatus of the present invention. FIG. 4 is a schematic view showing the outline of still another embodiment of the radionuclide-containing waste liquid treatment apparatus of the present invention. FIG. 5 is a schematic diagram showing a main part of another embodiment of the radionuclide-containing waste liquid treatment apparatus of the present invention. FIG. 6 is a schematic diagram showing a main part of another embodiment of the radionuclide-containing waste liquid treatment apparatus of the present invention.

Explanation of symbols

1 Radionuclide-containing waste liquid collection tank 2, 6, 12, 20 Pump 3 Hollow fiber membrane filter 4 Waste liquid primary treatment device 5 Liquid sampling tank 5
7 Double Water Storage Tank 8 Electric Regenerative Purifier 14 Overpack Container 15 Leakage Detector 16 Installation Base 19 Water Receiving Tank 22 Joint

Claims (12)

A primary processing device including a waste liquid desalination apparatus using waste filtration equipment and particle-like ion exchange resins,
A plurality of desalting chambers and concentrating chambers and a pair of electrode chambers formed by alternately arranging a cation exchange membrane and an anion exchange membrane between the anode and the cathode after the waste liquid primary treatment apparatus And at least one of the desalting chamber, the concentrating chamber, and the polar chamber is filled with an ion exchange fiber, and water to be treated is passed through in a state where a direct current is applied. An electric regenerative purification device capable of secondary treatment;
A radionuclide-containing waste liquid treatment apparatus capable of treating waste liquid containing radionuclides from a nuclear power plant.   A synthetic fiber having a fiber diameter of 1 to 50 μm, wherein the ion exchange fiber is formed by graft-polymerizing a functional group on a woven or non-woven base material made of an olefin polymer using electron beam, radiation or ultraviolet ray The waste liquid treatment apparatus according to claim 1, wherein   The waste liquid treatment apparatus according to claim 1, wherein the cation exchange fibers and the anion exchange fibers are alternately packed in a stacked state with respect to the flow direction of the water to be treated.   The electric regenerative purification apparatus includes a leak detector that automatically or automatically stops operation when the waste liquid leaks, while the whole or a part of the apparatus is accommodated in an overpack container so as to prevent leakage of radioactive waste liquid to the outside. The waste liquid treatment apparatus according to claim 1, wherein:   The waste liquid treatment apparatus according to claim 1, wherein the electric regenerative purification apparatus is configured as a portable module. A method for treating waste liquid containing radionuclides from a nuclear power plant,
It performs primary processing of radionuclide-containing waste liquid by filtration及beauty ion exchange, and the primary treated water to obtain a radionuclide-containing waste liquid primary treatment step,
After the radionuclide-containing waste liquid primary treatment step, a plurality of desalting chambers and concentration chambers and a pair of electrode chambers formed by alternately arranging a cation exchange membrane and an anion exchange membrane between the anode and the cathode And using an electric regenerative purification device in which any one or more of the desalting chamber, the concentration chamber, and the polar chamber are filled with ion-exchange fibers, An electrically regenerative purification process in which the primary treated water is passed as treated water and further subjected to secondary treatment in a state where current is applied;
And a radionuclide-containing waste liquid treatment method, wherein the radionuclide is removed.   A synthetic fiber having a fiber diameter of 1 to 50 μm, wherein the ion exchange fiber is formed by graft polymerization of a functional group to a woven or non-woven base material made of an olefin polymer using electron beam, radiation or ultraviolet ray. The waste liquid treatment method according to claim 6, wherein   In the electric regenerative purification step, the flow rate of the concentrated liquid that is allowed to act on the water to be treated in the concentration chamber and the flow rate of the polar liquid that is allowed to act on the water to be treated in the polar chamber are removed. The waste liquid treatment method according to claim 7, wherein continuous water flow is performed at a flow rate of 1/5 or less of the flow rate of water to be treated into the salt chamber, or intermittent water flow is performed.   8. The waste liquid treatment apparatus according to claim 7, wherein the water to be treated is passed by manual operation or automatic operation.   The waste liquid treatment method according to claim 7, wherein the cation exchange membrane and the anion exchange membrane are filled in a stacked state.   The electric regenerative purification apparatus includes an overpack container that accommodates all or part of the apparatus so as to prevent leakage of radioactive liquid waste to the outside, and a leak detector that automatically stops operation when the liquid waste leaks. The waste liquid treatment method according to claim 7, wherein:   The waste liquid treatment method according to claim 7, wherein the electric regenerative purification device is configured as a portable module.

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