Method for treating radioactive waste liquid, and system for treating radioactive waste liquid

Abstract

To provide a method for treating radioactive waste liquid, capable of reducing a generation amount of a radioactive waste.SOLUTION: A method for treating radioactive waste liquid comprises a concentration measurement step of measuring a concentration of radioactive nuclides in the radioactive waste liquid, and a radioactive nuclide removal step of contacting the radioactive waste liquid with an adsorbent to adsorb the radioactive nuclides in the radioactive waste liquid to the adsorbent. The method for treating radioactive waste liquid also comprises a concentration step of removing moisture from the radioactive waste liquid containing the adsorbent to increase a concentration of the adsorbent in the radioactive waste liquid. The method for treating radioactive waste liquid further comprises a flocculation step of supplying a flocculant to the radioactive waste liquid after the concentration step to perform flocculation precipitation, and a dehydration step of dehydrating the radioactive waste liquid after the flocculation precipitation.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for treating radioactive liquid waste and a radioactive liquid waste treatment system.

Background Art

[0002] Filter sludge and other radioactive organic wastes containing cellulosic filter aids, ion exchange resins, etc., generated from the reactor coolant purification system, fuel pool coolant purification system, etc. of nuclear power plants, are stored in storage tanks for a long time. These radioactive organic wastes are constantly generated along with the operation of nuclear power plants. In order to secure storage space for radioactive organic wastes, volume reduction treatment is being carried out to efficiently reduce the volume of radioactive organic wastes currently in storage (see, for example, Patent Documents 1, Patent Document 2, and Patent Document 3). In the technologies described in Patent Documents 1 to 3, volume reduction is achieved by coagulation precipitation of wastes containing radionuclides, dehydration of supernatant water, removal of nuclides by adsorbents, and recovery and concentration by cross-flow filtration of adsorbents (spent adsorbents) and colloids after nuclide adsorption.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even when using the technologies described in the aforementioned Patent Documents 1 to 3, the water content of the radioactive waste increases during coagulation and sedimentation and dewatering of the supernatant water. As a result, the volume of the radioactive waste increases, and a large amount of radioactive waste may be generated. In the treatment of radioactive liquid waste, it is necessary to further reduce the amount of radioactive waste generated.

[0005] To solve the above-mentioned problems, the present invention provides a method for treating radioactive liquid waste and a system for treating radioactive liquid waste that can reduce the amount of radioactive waste generated.

[0006] Furthermore, the above-mentioned objectives and other objectives of the present invention, as well as the novel features of the present invention, will be made clearer by the description herein and the accompanying drawings. [Means for solving the problem]

[0007] The present invention provides a method for treating radioactive waste liquid, which includes a concentration measurement step of measuring the concentration of radioactive nuclides in the radioactive waste liquid, and a radioactive nuclide removal step of bringing an adsorbent into contact with the radioactive waste liquid and adsorbing the radioactive nuclides in the radioactive waste liquid onto the adsorbent. The method also includes a concentration step of removing water from the radioactive waste liquid containing the adsorbent to increase the concentration of the adsorbent in the radioactive waste liquid. Furthermore, the method also includes a coagulation step of supplying a coagulant to the radioactive waste liquid after the concentration step to perform coagulation and sedimentation, and a dewatering step of dewatering the radioactive waste liquid after coagulation and sedimentation.

[0008] Furthermore, the radioactive waste treatment system of the present invention comprises a radioactive nuclide concentration measuring device for measuring the concentration of radionuclides in the radioactive waste, and a radioactive nuclide removal device for bringing an adsorbent into contact with the radioactive waste and allowing the adsorbent to adsorb the radionuclides in the radioactive waste. The radioactive waste treatment system also comprises a concentration device for removing water from the radioactive waste containing the adsorbent. Furthermore, the radioactive waste treatment system comprises a coagulation device for supplying a coagulant to the radioactive waste from which water has been removed, causing the adsorbent to coagulate and settle, and a dewatering device for dewatering the radioactive waste after coagulation and settling. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a method for treating radioactive liquid waste and a system for treating radioactive liquid waste that can reduce the amount of radioactive waste generated.

[0010] Furthermore, issues, configurations, and effects other than those mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0011] [Figure 1] This is a flowchart showing the procedure for processing radioactive liquid waste. [Figure 2] This figure shows an example of the configuration of a radioactive waste liquid treatment system. [Figure 3] Figure 2 is a detailed diagram of the processing system, from the radionuclide concentration measuring device to the dewatering device. [Figure 4] This graph shows the relationship between adsorbent concentration and decontamination coefficient. [Figure 5] This graph shows the relationship between the water content of radioactive waste and the concentration of waste adsorbent. [Figure 6] This diagram illustrates the effect of differences in processing methods on the volume of radioactive waste. [Figure 7] This is a flowchart showing the procedure for processing radioactive liquid waste. [Modes for carrying out the invention]

[0012] The following describes, with reference to text and drawings, a method for treating radioactive waste liquid and a system for treating radioactive waste liquid according to embodiments of the present invention. However, the structures, materials, and other specific configurations shown in the present invention are not limited to the embodiments and examples discussed herein, and can be appropriately combined or improved without changing the gist of the invention. Furthermore, elements not directly related to the present invention are omitted from the illustrations.

[0013] The object of providing a method for treating radioactive liquid waste that can reduce the amount of radioactive waste generated, as described above, can be achieved by the following method for treating radioactive liquid waste and a radioactive liquid waste treatment system. The description will be made in the following order. 1. First Embodiment of the Method for Treating Radioactive Liquid Waste and the Radioactive Liquid Waste Treatment System 2. Second Embodiment of the Method for Treating Radioactive Liquid Waste and the Radioactive Liquid Waste Treatment System

[0014] 〈1. First Embodiment of the Method for Treating Radioactive Liquid Waste and the Radioactive Liquid Waste Treatment System〉 The method for treating radioactive liquid waste and the radioactive liquid waste treatment system of the first embodiment will be described with reference to FIGS. 1 to 5. The method for treating radioactive liquid waste and the radioactive liquid waste treatment system of this embodiment are applied to the treatment of radioactive waste generated in nuclear power plants.

[0015] [[ID=十六]][Method for Treating Radioactive Liquid Waste][[ID=十七]] First, the outline of the method for treating radioactive liquid waste will be described with reference to FIG. 1. FIG. 1 is a flowchart showing the procedure of the method for treating radioactive liquid waste. In a nuclear power plant, for example, in the core inside the reactor pressure vessel of a boiling water nuclear power plant that has experienced operation, a fuel assembly is loaded. Also, used fuel assemblies are stored in the fuel storage pool. The fuel rods of these fuel assemblies are provided with cladding tubes. In the unlikely event that the cladding tube is damaged, nuclear fuel substances (including uranium, plutonium, neptunium, americium, curium, etc., which are α nuclides) and radionuclides in the fuel rods will leak into the cooling water inside the reactor pressure vessel or the cooling water inside the fuel storage pool. Then, the radionuclides leaked into the cooling water inside the reactor pressure vessel are removed by ion exchange resins in the purification device of the reactor coolant purification system. Also, the radionuclides leaked into the cooling water inside the fuel storage pool are removed by ion exchange resins in the purification device of the fuel pool coolant purification system.

[0016] Filter sludge (radioactive organic waste) containing cellulose-based filter aids and ion exchange resins, generated from the reactor coolant purification system and fuel pool coolant purification system of boiling water reactor nuclear power plants, is stored for a long period in high-dose resin storage tanks. After a predetermined storage period has elapsed, the radioactive organic waste stored in these high-dose resin storage tanks is removed from the tanks.

[0017] The first washing process (cladding process) S1 shown in Figure 1 is performed on the radioactive organic waste containing cation exchange resin that has been removed from the high-dose resin storage tank. The first washing step S1 involves contacting the radioactive organic waste with an aqueous solution of a reducing organic acid (for example, an aqueous solution of oxalic acid). The organic acid in this aqueous solution then dissolves the cladding, such as iron oxides, contained in the radioactive organic waste. Radioactive nuclides, such as cobalt-60, contained in the cladding are transferred into the organic acid aqueous solution as the cladding dissolves.

[0018] The organic acid used in the first washing step S1 has carbon, hydrogen, oxygen, and nitrogen as its main constituent elements. Therefore, by using an organic acid in the first washing step S1, when the aqueous solution of the organic acid generated as washing wastewater in the first washing step S1 is oxidized using, for example, ozone (wastewater decomposition step S4 described later), no non-volatile residue is produced in the wastewater. As the organic acid, it is desirable to use one or more selected from, for example, formic acid, oxalic acid, acetic acid, and citric acid.

[0019] After the first washing process S1 has been performed and the cladding has been dissolved, the second washing process (radionic nuclide elution process) S2 is carried out on the radioactive organic waste. In this second washing step S2, an aqueous solution of organic acid salts is brought into contact with the radioactive organic waste in which the cladding has been dissolved. The organic acid salts contained in the aqueous solution then elute radioactive nuclides, such as alpha-nuclides, that have been adsorbed onto the radioactive organic waste.

[0020] The organic acid salt used in the second washing step S2 is preferably an organic acid salt that dissociates in aqueous solution and produces cations that are more readily adsorbed by the cation exchange resin than hydrogen ions. That is, the organic acid salt should have carbon, hydrogen, oxygen, and nitrogen as its main constituent elements, and should not produce non-volatile residues in the wastewater when the aqueous solution of the organic acid salt, which is the washing wastewater after the completion of the second washing step S2, is oxidized using, for example, ozone (wastewater decomposition step S4). As the organic acid salt, it is preferable to use, for example, ammonium salts, barium salts, or cesium salts of formic acid, oxalic acid, acetic acid, or citrate. Formic acid hydrazine may also be used as the organic acid salt.

[0021] Ammonium salts decompose into nitrogen gas and water through oxidation, thus reducing the amount of radioactive waste generated compared to barium and cesium salts. Ammonium, barium, or cesium salts of formic acid, oxalic acid, acetic acid, or citric acid dissociate in aqueous solution, forming NH3. 4+ Ba 2+ or Cs + It will become NH 4+ Ba 2+ or Cs + This is a cation that is more readily adsorbed by cation exchange resins than hydrogen ions.

[0022] In the second washing process S2, the radioactive organic waste separated from the radioactive nuclide eluent is subjected to the incineration and solidification process S3. The radioactive organic waste separated from the nuclide eluent is transferred to an incineration facility, where it is incinerated. After incineration, the ash generated is solidified in a solidification container with a solidifying agent such as cement.

[0023] In the first washing step S1, a wastewater decomposition step S4 is performed on the aqueous organic acid solution (cladding solution) containing the cladding dissolving components, which is generated as washing wastewater. In the second washing step S2, a wastewater decomposition step S4 is also performed on the aqueous organic acid salt solution containing eluted radioactive nuclides such as alpha nuclides, which is generated as washing wastewater. In the wastewater decomposition step (decomposition step of either organic acid or organic acid salt) S4, an oxidizing agent such as ozone or hydrogen peroxide is aerated into the aqueous organic acid solution or the aqueous organic acid salt solution, and the organic acid or organic acid salt is decomposed by the oxidizing action of the oxidizing agent.

[0024] After the organic acids or organic acid salts are decomposed in the waste liquid decomposition process S4, the concentration of radionuclides is measured in the residual aqueous solution (radioactive waste liquid) containing radionuclides (measurement of radionuclide concentration S5). Here, the concentration of radionuclides may be measured by sampling the radioactive waste liquid and measuring it with an analytical instrument, or by measuring it with a survey meter. Alternatively, the concentration of radionuclides may be measured online. If the concentration of radioactive nuclides measured in radioactive nuclide concentration measurement S5 is below a predetermined concentration, container filling or solidification S10 is performed without removing the radioactive nuclides. Alternatively, the water may be recycled and used as washing water in the first washing process S1 or the second washing process S2. To reduce the amount of radioactive waste generated, it is preferable to recycle the water and use it in the first washing process S1 or the second washing process S2.

[0025] On the other hand, if the concentration of radionuclides measured in radionuclide concentration measurement S5 is above a predetermined concentration, the radionuclide removal process S6 is performed. In the radionuclide removal process S6, an adsorbent for radionuclides is supplied to the radioactive waste liquid. In the removal process, by bringing the radioactive waste liquid into contact with the adsorbent, the radionuclides in the radioactive waste liquid are adsorbed onto the adsorbent, and the radionuclides are removed from the liquid phase of the radioactive waste liquid. Examples of adsorbents that can be used include cation exchange resins, Fe oxides, titanate compounds, titanate compounds, ferrocyanide compounds, chelate resins, activated carbon, oxin-impregnated activated carbon, zeolites, silica particles, and alumina particles.

[0026] Furthermore, as a pre-process for the radioactive nuclide removal process S6, a pH adjusting agent may be supplied to the radioactive waste liquid to adjust the pH and control the chemical form of the radioactive nuclide (not shown). As pH adjusting agents, inorganic acids (hydrochloric acid, sulfuric acid, nitric acid, etc.), inorganic alkalis (sodium hydroxide, calcium hydroxide, magnesium hydroxide, etc.), organic acids (carboxylic acids, ascorbic acid, etc.), and organic alkalis (ammonium-based, etc.) can be used.

[0027] After the radioactive nuclide removal process S6, a concentration process S7 is performed in the radioactive waste liquid containing the adsorbent to increase the concentration of the adsorbent that has adsorbed the radioactive nuclides. In the concentration process S7, a cross-flow filter is used to separate the adsorbent that has adsorbed the radioactive nuclides from the waste liquid from which the radioactive nuclides have been removed. In the concentration process S7, there are adsorbents in the radioactive waste liquid that have not coagulated and settled, and in many cases, the solid components such as adsorbents are dispersed in the waste liquid from which the radionuclides have been removed. In other words, in the concentration process S7, a concentrated solution of radioactive waste liquid is produced by separating a portion of the liquid from which the radionuclides have been removed, thereby increasing the concentration of solid components such as adsorbents that have adsorbed radionuclides in the radioactive waste liquid. In this process, the solid components, including a slurry containing radioactive nuclides along with the adsorbent that has adsorbed the radioactive nuclides, are separated from the waste liquid from which the radioactive nuclides have been removed. Furthermore, in the concentration process S7, in addition to a cross-flow filter, the above-mentioned solid-liquid separation and concentration may be performed using, for example, a press filter or an evaporator. The filtered water (waste liquid) separated in the concentration process S7 from which the radioactive nuclides have been removed may be recycled and used as washing water in the first washing process S1 or the second washing process S2.

[0028] The concentrated liquid containing solid components such as adsorbent and slurry separated in the concentration step S7 is subjected to coagulation and precipitation in the coagulation step S8. In the coagulation step S8, a coagulant is supplied to the concentrated liquid to coagulate and precipitate the solid components, including adsorbent and slurry containing radionuclides, in the concentrated liquid. As the coagulant, for example, inorganic coagulants (aluminum sulfate, polyaluminum chloride, ferric sulfate, ferric chloride, etc.) and organic coagulants (natural polymers, synthetic polymers, etc.) can be used.

[0029] The concentrated liquid (radioactive waste) containing adsorbent material and solid components such as slurry containing radioactive nuclides, which have been coagulated and precipitated in the coagulation step S8, undergoes a dewatering step S9 using a dewatering device. In the dewatering step S9, similar to the concentration step S7, solid-liquid separation is performed to separate the waste liquid from which radioactive nuclides have been removed from the solid components such as slurry containing adsorbent material and radioactive nuclides, using, for example, a cross-flow filter, a press filter, and an evaporator.

[0030] After the dewatering process S9, the solid components such as the slurry containing the adsorbent and radionuclides are either filled into containers or solidified in S10. The dewatered radioactive waste is transferred to a solidification facility, where a solidifying agent (e.g., cement) is supplied. The powder inside the solidification container is solidified by the solidifying agent. Alternatively, the dewatered radioactive waste is transferred to a filling facility, the containers filled with powder are sealed, and then the containers are stored in a storage location. The waste liquid from which the radionuclides have been removed by the dewatering process S9 may be recycled and used as washing water in the first washing process S1 or the second washing process S2.

[0031] [Radioactive waste liquid treatment system] Next, an example of the configuration of a radioactive waste treatment system including each of steps S1 to S10 of the radioactive waste treatment method described above will be explained with reference to Figure 2. The radioactive waste treatment system 1 shown in Figure 2 includes a chemical washing section 10 for treating radioactive organic waste, and a wastewater treatment section 19 for treating the washing wastewater (radioactive wastewater) discharged from the chemical washing section 10.

[0032] The chemical cleaning unit 10 includes a first receiving tank 3, a chemical reaction vessel (cleaning tank) 4, a cleaning liquid supply tank 6, an organic acid tank 7, and an organic acid salt tank 8 and a transfer water tank 9. In addition, a high-dose resin storage tank 2 is provided in front of the chemical cleaning unit 10, and a second receiving tank 11 and an incineration facility (or cement solidification facility) 12 are provided below the chemical cleaning unit 10 in the diagram. In the chemical cleaning section 10, among the processes shown in Figure 1, the first cleaning step S1, which dissolves the cladding, and the second cleaning step S2, which elutes radionuclides from the radioactive organic waste, are performed.

[0033] The chemical cleaning section 10 has an organic waste supply pipe 23 equipped with a transfer pump 22, which connects to the high-dose resin storage tank 2 and the first receiving tank 3. The chemical reaction vessel 4 is connected to the first receiving tank 3 by an organic waste transfer pipe 25 equipped with a transfer pump 24. A heating device 5 is arranged around the chemical reaction vessel 4. The cleaning solution supply tank 6 is connected to the chemical reaction vessel 4 by a cleaning solution supply pipe 33 equipped with a transfer pump 32. A return pipe 36, connected to the bottom of the chemical reaction vessel 4 and equipped with a transfer pump 34 and a valve 35, is connected to the cleaning liquid supply tank 6.

[0034] A pipe 29, equipped with a valve 26, is connected to an organic acid tank 7 filled with an organic acid aqueous solution, such as an oxalic acid aqueous solution, and is connected to a cleaning solution supply tank 6. The oxalic acid aqueous solution filled in the organic acid tank 7 is a saturated aqueous solution, and its oxalic acid concentration is, for example, 0.8 mol / L. A pipe 30, which is connected to an organic acid salt tank 8 filled with an aqueous solution of an organic acid salt, such as an aqueous solution of hydrazine formate, and is equipped with a valve 27, is connected to a pipe 29 downstream of the valve 26. A pipe 31, which is connected to a transfer tank 9 filled with water to be transferred and has a valve 28, is connected to a pipe 30 downstream of the valve 27.

[0035] A valve 37 is provided, and a pipe 38 connected to the bottom of the chemical reaction vessel 4 is connected to the second receiving tank 11. The piping connected to the second receiving tank 11 is connected to the incineration equipment (or cement solidification equipment) 12.

[0036] The wastewater treatment unit 19 includes a wastewater decomposition unit 13, a radionuclide concentration measuring unit 14, a radionuclide removal unit 15, a coagulation unit 16, a dewatering unit 20, an adsorbent supply unit 121, a coagulant supply unit 122, and a concentration unit 131. In the wastewater treatment section 19, the processes shown in Figure 1 are carried out from the wastewater decomposition process S4, which decomposes organic acids in an aqueous solution of organic acids containing the dissolving components of the cladding, to the dewatering process S9, which performs solid-liquid separation to separate the solid components such as a slurry containing adsorbent and radioactive nuclides from the wastewater.

[0037] A waste liquid supply pipe 40, which is connected to a return pipe 36 between the transfer pump 34 and the valve 35 and has a valve 39, is connected to the waste liquid decomposition device 13. The piping 45, which is equipped with a transfer pump 43 and a valve 44, is connected to the waste liquid decomposition unit 13 and the radionuclide removal unit 15. This piping 45 is a supply pipe for radioactive waste liquid that guides the radioactive waste liquid containing radionuclides to the radionuclide removal unit 15 in the radioactive waste liquid treatment method described above. A radionuclide concentration measuring device 14 and an adsorbent supply device 121 are connected to this piping 45.

[0038] Piping 46 is connected to the radionuclide removal device 15, the enrichment device 131, and the coagulation device 16. The coagulant supply device 122 is connected to the coagulation device 16. Furthermore, the piping 48, which is equipped with a transfer pump 47, is connected to the coagulation device 16 and the dewatering device 20, and the piping 49 is further connected to the dewatering device 20 and the solidification equipment 21.

[0039] The concentration device 131 includes, for example, a solid-liquid separation device using a cross-flow filter with a membrane having a pore size of the order of μm or less. This solid-liquid separation device filters the radioactive waste liquid and separates the adsorbent material that has adsorbed radionuclides from the radioactive waste liquid, the slurry containing radionuclides, etc., from the filtered water (waste liquid) from which the radionuclides have been removed. The concentration device 131 may also include a device for concentration that uses a press filter system for filtration under pressure or an evaporation concentration system that uses an evaporation device as the solid-liquid separation device.

[0040] Furthermore, the concentration device 131 is connected to a pipe 55 that is connected between the transfer pump 34 and valve 35 of the return pipe 36 of the chemical washing section 10. The filtered water from which the slurry containing adsorbent and radionuclides has been separated by filtration in the concentration device 131 returns to the return pipe 36 through pipe 55. This allows the filtered water to be circulated as circulating water. Upstream of the connection between the return pipe 36 and pipe 55 (on the chemical reaction tank 4 side and the concentration device 131 side), valves (not shown) are provided to allow switching between water from the chemical reaction tank 4 and filtered water from pipe 55.

[0041] The dehydration device 20 includes, for example, a solid-liquid separation device using a cross-flow filter system with a membrane having a pore size of μm or less, a solid-liquid separation device using a press filter system that performs filtration under pressure, and a solid-liquid separation device that performs concentration using an evaporation concentration system that uses an evaporation device. Similar to the concentration device 131 described above, the dewatering device 20 is connected to a pipe 56 that is connected between the transfer pump 34 and valve 35 of the return pipe 36 of the chemical washing unit 10. The water from which radioactive nuclides have been removed by the dewatering device 20 returns to the return pipe 36 through pipe 56. This allows the water to be circulated as circulating water. Valves (not shown) are provided upstream of the connection between the return pipe 36 and pipe 56 (on the chemical reaction vessel 4 side and the dewatering device 20 side) to allow switching between water from the chemical reaction vessel 4 and water from pipe 56. In addition, the dewatering device 20 may perform dewatering using the cross-flow filter method, press filter method, etc., as described in the concentration device 131.

[0042] The timing of transferring the radioactive waste liquid from the chemical cleaning unit 10 to the waste liquid processing unit 19 is not limited. For example, a sampling valve may be installed in the return pipe 36, and the radioactive waste liquid collected by the sampling valve may be periodically analyzed. The radioactive waste liquid may then be transferred when the concentration of the measured radioactive nuclide reaches a desired concentration.

[0043] Here, Figure 3 shows a detailed configuration diagram of the wastewater treatment unit 19 shown in Figure 2, from the radionuclide concentration measuring device 14 to the dewatering device 20. In addition, Figure 3 also shows the piping connected to the radionuclide removal device 15 and the components (tanks, devices, etc.) located nearby.

[0044] As shown in Figure 3, a radionuclide concentration measuring device 14 is connected to a pipe 45, which is a supply pipe for radioactive waste liquid connected to the radionuclide removal device 15. Alternatively, the radionuclide concentration measuring device 14 may be used to measure the radionuclide concentration of sampled radioactive waste liquid without being connected to the waste liquid processing unit 19, and the result may be reflected in the amount of adsorbent supplied by the adsorbent supply device 121.

[0045] The radioactive nuclide removal device 15 consists of a waste liquid treatment tank that contains the radioactive waste liquid sent from the waste liquid decomposition device 13 through the piping 45. Furthermore, if the concentration of radionuclides in the radioactive waste liquid is measured by the radioactive nuclide concentration measuring device 14 and the concentration of radionuclides is below a predetermined concentration, the radioactive waste liquid may be returned to the return pipe 36 through the pipe 54 and circulated as circulating water.

[0046] If the concentration of radionuclides in the radioactive waste liquid is found to be above a predetermined concentration, the radioactive waste liquid is supplied to the radioactive nuclide removal device 15. Alternatively, the pH of the radioactive waste liquid may be adjusted to control its chemical form before supplying it to the radioactive nuclide removal device 15.

[0047] Adsorbent material is supplied to the radioactive nuclide removal device 15 from the adsorbent supply device 121. Then, the radioactive waste liquid is brought into contact with the adsorbent within the radioactive nuclide removal device 15. As a result, in the radioactive nuclide removal device 15, the radioactive nuclides are adsorbed onto the adsorbent and removed from the liquid phase of the radioactive waste liquid.

[0048] In the radioactive nuclide removal device 15, the radioactive waste liquid, on which radioactive nuclides have been adsorbed by the adsorbent, is supplied to the concentration device 131 through piping 46. In the concentration device 131, the concentrated liquid containing the slurry of the adsorbent and other materials, concentrated by solid-liquid separation, is supplied to the coagulation device 16 through piping 46. Alternatively, the filtered water may be returned to the return pipe 36 through piping 55 and circulated as circulating water. At this time, valves (not shown) are provided upstream of the connection between the return pipe 36 and pipe 55 (on the chemical reaction tank 4 side and the concentration device 131 side) to allow switching between water from the chemical reaction tank 4 and filtered water from pipe 55.

[0049] The coagulation device 16 consists of a concentrated liquid treatment tank that contains the concentrated liquid sent from the concentration device 131 through the piping 46. In the coagulation device 16, a coagulant is supplied to the concentrated liquid from the coagulant supply device 122, and the concentrated liquid is subjected to coagulation and sedimentation treatment. The concentrated liquid (radioactive waste) containing solids such as the adsorbed material and slurry containing radionuclides, which have been coagulated and precipitated, is supplied to the dewatering device 20 through piping 48. The water from which the radionuclides have been removed in the dewatering device 20 is returned to the return piping 36 through piping 56. This allows it to be circulated as circulating water. In addition, valves (not shown) are provided upstream of each pipe 36 and 56 (on the chemical reaction tank 4 side and the dewatering device 20 side) from the connection point between the return piping 36 and piping 56, so that the water from the chemical reaction tank 4 and the water from piping 56 can be switched.

[0050] The radioactive waste dewatered in the dewatering unit 20 is transferred to the solidification unit 21 (or filling unit). In the solidification unit 21, the powder is filled into a solidification container, and a solidifying agent (e.g., cement) is supplied into the container. The powder inside the container is solidified by the solidifying agent (container filling or solidification process S10). The solidified container, now sealed and containing the solidified powder, is stored in a storage area. Alternatively, if a filling unit is used, the container is filled with powder, the container is sealed, and then the container is stored in a storage area.

[0051] [Adsorbent supply amount] Here, the determination of the amount of adsorbent to supply based on the measurement of radionuclide concentrations will be explained by referring to the relationship between adsorbent concentration and decontamination factor (DF) shown in Figure 4. The example shown in Figure 4 is a graph showing the results when using 1000-fold diluted simulated seawater (pH 6) as the test solution, americium (Am) as the radionuclide, and magnetite (Fe3O4) as the adsorbent.

[0052] As shown in Figure 4, it was confirmed that DF increases as the adsorbent concentration increases. DF is calculated by dividing the concentration of radioactive nuclides in the radioactive waste liquid before removal by the concentration of radioactive nuclides in the radioactive waste liquid after removal. Therefore, a larger DF value indicates that a greater amount of radioactive nuclides are removed by the adsorbent in the radioactive waste liquid. In other words, the graph in Figure 4 shows the relationship between the concentration of adsorbent in the radioactive waste liquid and the adsorption performance of the adsorbent at that concentration.

[0053] For example, in order to reduce the Am concentration of radioactive waste liquid, obtained by radioactive nuclide concentration measurement, from 400 Bq / L to the notified concentration of 4 Bq / L or less, the nuclide concentration of the radioactive waste liquid needs to be reduced to 1 / 100. In this case, as shown in the graph in Figure 4, the nuclide concentration of the radioactive waste liquid can be reduced to 1 / 100 by supplying adsorbent at an adsorbent concentration that results in DF100. Therefore, the adsorbent concentration required in the radioactive nuclide removal process and the amount of adsorbent to be supplied are determined from the graph showing DF and adsorbent concentration shown in Figure 4, the radioactive nuclide concentration of the radioactive waste liquid obtained by radioactive nuclide concentration measurement, and the notified concentration.

[0054] [Reduction of radioactive waste volume through concentration process] Next, we will explain a method for reducing the amount of radioactive waste generated by coagulation and sedimentation when adsorbing radioactive nuclides into the adsorbent material (hereinafter, to distinguish it from the adsorbent material before adsorption, the adsorbent material after adsorption of radioactive nuclides will be referred to as waste adsorbent material).

[0055] (Equilibrium point between waste adsorbent concentration and water content) Figure 5 is a graph showing the relationship between the water content of radioactive waste and the concentration of waste adsorbent generated during coagulation and sedimentation treatment. The example shown in Figure 5 uses Fe3O4 as the waste adsorbent and aluminum sulfate (Al2(SO4)3: 1000 ppm) as the coagulation agent. The waste adsorbent concentration is the adsorbent concentration in the radioactive waste liquid when the coagulant is supplied, and the water content of the radioactive waste is the water concentration in the radioactive waste after the dewatering process.

[0056] As shown in Figure 5, up to a waste adsorbent concentration of 10 g / L, the moisture content of the radioactive waste generated after coagulation and sedimentation decreases as the waste adsorbent concentration increases. On the other hand, it was confirmed that the moisture content of the radioactive waste generated after coagulation and sedimentation remains almost unchanged when the waste adsorbent concentration is 10 g / L or higher. In other words, as shown in Figure 5, in the relationship between waste adsorbent concentration and moisture content, once the waste adsorbent concentration exceeds a certain value, the moisture content becomes almost constant regardless of increases or decreases in waste adsorbent concentration, and the moisture content of the radioactive waste reaches an equilibrium state with respect to the waste adsorbent concentration. The waste adsorbent concentration and the moisture content of the radioactive waste at which the moisture content of the radioactive waste reaches equilibrium with respect to the waste adsorbent concentration are defined as the equilibrium point of moisture content.

[0057] Furthermore, when the moisture content of radioactive waste decreases, the amount of water in the radioactive waste decreases, so the overall volume of the radioactive waste decreases, and the amount of radioactive waste is reduced (as described later in Figure 6). From the above results, it can be seen that within the range where the moisture content of radioactive waste decreases, the moisture content of the radioactive waste can be reduced, i.e., the amount of radioactive waste can be reduced, by performing coagulation and sedimentation under conditions of high concentration of waste adsorbent.

[0058] (Reduction of radioactive waste through the concentration process) Next, the effects of the radioactive waste treatment method shown in Figure 1 and the radioactive waste treatment system shown in Figure 2 on reducing radioactive waste will be explained by referring to the effect of differences in the treatment process on the volume of radioactive waste shown in Figure 6. Note that the example shown in Figure 6 is the result when Fe3O4 is used as the adsorbent and Al2(SO4)3 is used as the coagulant (using Figures 4 and 5).

[0059] First, we will explain the change in volume of radioactive waste in conventional radioactive waste liquid treatment methods. The conventional radioactive waste liquid treatment method is illustrated as a case where the radioactive nuclide concentration measurement step (S5), adsorbent supply (removal step S6), coagulant supply (coagulation step S8), and dewatering step (S9) are performed, but the concentration step (S7) is not.

[0060] Figure 6(a) shows the change in volume of radioactive waste resulting from the above treatment. In conventional methods for treating radioactive waste liquid, the concentration of radionuclides in the radioactive waste liquid is measured (S5), and the adsorbent concentration required to reduce the radionuclides to below the specified concentration is determined from the relationship between the adsorbent concentration and DF (Figure 4). From Figure 4, for example, if the required adsorbent concentration for treating radioactive waste liquid is determined to be 1 g / L, then from the relationship between the water content of the radioactive waste during coagulation and sedimentation and the adsorbent concentration (Figure 5), the water content of the radioactive waste liquid is 80 wt% (95 vol%). As a result, as shown in Figure 6(a), in the untreated radioactive waste liquid, there is 1000 mL of contaminated water per 1 g of waste adsorbent, whereas in the detreated radioactive waste, there is 20 mL of contaminated water per 1 g of waste adsorbent. Therefore, the volume of the detreated radioactive waste is approximately 1 / 50 of the volume of the untreated radioactive waste.

[0061] Furthermore, in conventional radioactive waste liquid treatment methods, Figure 6(b) shows the change in volume of radioactive waste when an adsorbent at a concentration that brings the water content of the radioactive waste to an equilibrium point is supplied to the radioactive waste liquid in order to reduce the water content of the radioactive waste. In this case, the concentration of radionuclides in the radioactive waste liquid is measured (S5), and the adsorbent concentration at which the water content of the radioactive waste reaches equilibrium is determined from the relationship between the water content of the radioactive waste during coagulation and sedimentation and the concentration of the waste adsorbent (Figure 5). From Figure 4, for example, if the adsorbent concentration at which the water content reaches equilibrium is determined to be 10 g / L, then from the relationship between the water content of the radioactive waste during coagulation and sedimentation and the concentration of the waste adsorbent (Figure 5), the water content of the radioactive waste liquid is 40 wt% (70 vol%).

[0062] As a result, as shown in Figure 6(b), in the untreated radioactive waste liquid, there is 1000 mL of contaminated water per 10 g of waste adsorbent, whereas in the detreated radioactive waste, there is 20 mL of contaminated water per 10 g of waste adsorbent. Therefore, the volume of the detreated radioactive waste is approximately 1 / 35 of the volume of the untreated radioactive waste. In this method, although the water content of the radioactive waste liquid is lower compared to Figure 6(a), the amount of adsorbent increases, resulting in a larger amount of radioactive waste. For example, in the example shown in Figure 6(a), the ratio of waste adsorbent to contaminated water in the radioactive waste is 20 mL of contaminated water per 1 g of waste adsorbent, whereas in the example shown in Figure 6(a), it is 20 mL of contaminated water per 10 g of waste adsorbent. Thus, when using an adsorbent concentration where the water content is at equilibrium, the amount of radioactive waste increases further due to the increase in the waste adsorbent concentration. Furthermore, since only a small amount of radionuclides are adsorbed relative to the adsorption capacity of the supplied adsorbent, this is an inefficient method of using adsorbent.

[0063] Next, Figure 6(c) shows the method for treating radioactive liquid waste according to this embodiment, and the change in the volume of radioactive waste due to the treatment system. In this embodiment of the radioactive waste liquid treatment method, the concentration of radionuclides in the radioactive waste liquid is measured (S5), and the adsorbent concentration required to reduce the radionuclides to below the specified concentration is determined from the relationship between the adsorbent concentration and DF (Figure 4). From Figure 4, for example, if the required adsorbent concentration for treating the radioactive waste liquid is determined to be 1 g / L, then the adsorbent is supplied to the radioactive waste liquid to achieve this concentration (removal step S6).

[0064] Next, a concentration process (S7) is performed on the radioactive waste liquid after the removal process (S6). In the concentration process (S7), based on the relationship between the water content of the radioactive waste during coagulation and sedimentation and the concentration of the waste adsorbent (Figure 5), the concentration of solid components such as adsorbent is concentrated to a level higher than the concentration at which the water content of the radioactive waste is at equilibrium. For this reason, in the concentration process (S7) of this example, filtered water is removed from the radioactive waste liquid so that the waste adsorbent concentration becomes 10 g / L, thereby concentrating the concentration of solid components such as adsorbent (10-fold concentration). As shown in Figure 6(b), this treatment reduces the ratio of waste adsorbent to contaminated water in the radioactive waste from 1 g of waste adsorbent to 100 mL of contaminated water in the concentrated solution compared to 1 g of waste adsorbent in the untreated radioactive waste liquid.

[0065] Subsequently, a coagulation and sedimentation process (S8) and a dewatering process (S9) are performed on the concentrated liquid. In this dewatering process (S9), the concentration of solids is concentrated to a level above the adsorbent concentration at which the water content is at equilibrium. Therefore, similar to Figure 6(b) above, from the relationship between the water content of the radioactive waste during coagulation and sedimentation and the concentration of the waste adsorbent (Figure 5), the water content of the radioactive waste can be reduced to 40 wt% (70 vol%) by the dewatering process (S9). As a result, as shown in Figure 6(c), the concentrated liquid before dehydration has a ratio of 100 mL of contaminated water per 1 g of waste adsorbent, whereas the radioactive waste after dehydration has a ratio of 2 mL of contaminated water per 1 g of waste adsorbent. Therefore, the volume of radioactive waste after concentration and dewatering is approximately 1 / 330 of the volume of untreated radioactive waste.

[0066] From the above, the radioactive waste liquid treatment method and radioactive waste liquid treatment system of this form can reduce the amount of radioactive waste after the dewatering process. In particular, by performing a concentration process to increase the solid content of the radioactive waste liquid after the removal process of radioactive waste liquid using an adsorbent and before supplying a coagulant, the concentration of waste adsorbent in the concentrated liquid can be increased without increasing the amount of adsorbent supplied. As a result, the concentration of waste adsorbent in the radioactive waste liquid (concentrated liquid) can be increased to a level above the equilibrium point of the water content of the radioactive waste shown in Figure 5, and the water content of the radioactive waste after the dewatering process can be reduced. As a result, the amount of radioactive waste generated can be reduced.

[0067] Therefore, this method and system for treating radioactive liquid waste can achieve both the specified concentration by removing radionuclides using the minimum necessary adsorbent and the reduction of radioactive waste generation by reducing water content. Furthermore, it can reduce the amount of radioactive waste containing long-half-life alpha nuclides. Furthermore, even if the concentration of waste adsorbent in the concentrated solution is increased beyond the equilibrium point during the concentration process, the water content of the solid components of the waste adsorbent after the dewatering process remains almost unchanged (equilibrium), and therefore the amount of radioactive waste does not decrease significantly. For this reason, in the concentration process, it is sufficient to increase the concentration of waste adsorbent in the concentrated solution to the equilibrium point of water content.

[0068] Furthermore, the radioactive waste liquid treatment method and radioactive waste liquid treatment system of this embodiment may also target the removal of radioactive nuclides other than alpha nuclides contained in the radioactive waste liquid. Examples of radioactive nuclides include one or more elements from among transition metals such as ruthenium, technetium, and niobium; alkali metals such as cesium; alkaline earth metals such as strontium; rare earth elements such as cerium; halogens such as antimony, tellurium, and iodine; and nonmetallic elements such as carbon and boron.

[0069] <2. Method for treating radioactive waste liquid, and a second embodiment of the radioactive waste liquid treatment system> Next, the radioactive waste treatment method and radioactive waste treatment system of the second embodiment will be described with reference to Figure 7. Note that the radioactive waste treatment method of the second embodiment overlaps in some steps with the radioactive waste treatment method of the first embodiment described above. Furthermore, the radioactive waste treatment system of the second embodiment can utilize the same configuration as the radioactive waste treatment system shown in Figures 2 and 3, which are the same as those of the first embodiment described above. Therefore, in the following description, the same processes and configurations as those of the first embodiment described above will be omitted.

[0070] The second embodiment of the radioactive waste liquid treatment method differs from the first embodiment in the operation of measuring the concentration of radionuclides and supplying adsorbent. The second embodiment of the radioactive waste liquid treatment method will be described with reference to Figure 7. Figure 7 is a flowchart showing the procedure of the second embodiment of the radioactive waste liquid treatment method.

[0071] First, the radioactive nuclide concentration measurement process S5 is performed according to the flowchart shown in Figure 1 above. Then, if the concentration of the radioactive nuclide is equal to or greater than a predetermined concentration as a result of the radioactive nuclide concentration measurement process S5, the adsorbent supply process S61 shown in Figure 7 is performed. In the adsorbent supply process S61, adsorbent is supplied to the radioactive nuclide removal device 15 in advance so that the concentration of the waste adsorbent is equal to or greater than the equilibrium point shown in Figure 5 for the radioactive waste liquid. For example, under the same conditions as the example shown in Figure 6 above, 10 g / L of adsorbent, which is the waste adsorbent concentration at which the water content of the radioactive waste is in equilibrium as shown in Figure 5, is supplied to the radioactive nuclide removal device 15.

[0072] Subsequently, the radioactive nuclide concentration of the radioactive waste liquid is measured (S62). This step may be replaced with the radioactive nuclide concentration measurement (S5). The order in which the radioactive nuclide concentration measurement (S62) and the adsorbent supply step (S61) are performed does not matter. Then, based on the measured radioactive nuclide concentration, a determination step (S63) is performed to determine whether the radioactive nuclide concentration of the radioactive waste liquid can reach the specified concentration by the adsorbent in the radioactive nuclide removal device (15) if this radioactive waste liquid is supplied to the radioactive nuclide removal device (15).

[0073] If the specified concentration can be achieved (YES in S63), step S64 is performed to supply the radioactive waste liquid to the radioactive nuclide removal device 15. In step S64, the radioactive waste liquid is brought into contact with an adsorbent inside the radioactive nuclide removal device 15, and the radioactive nuclides are adsorbed onto the adsorbent. This step S64, which supplies the radioactive waste liquid, corresponds to step S6 of the removal process in the flowchart shown in Figure 1 above.

[0074] Next, after a predetermined time has elapsed, a concentration step S7 is performed in the radioactive waste liquid containing the adsorbent to increase the concentration of the adsorbent that has adsorbed radionuclides. The concentration step S7 is performed in the same manner as the flowchart shown in Figure 1 above. After the concentration step S7, the concentrated liquid is supplied to the radioactive nuclide removal device 15, thereby performing the adsorbent supply step S61 to the radioactive nuclide removal device 15. By supplying the concentrated liquid to the radioactive nuclide removal device 15, the adsorbent containing the concentrated liquid that has sufficient adsorption capacity is reused. The water (filtered water) from which the dewatered radionuclides have been removed in the concentration device can be circulated as circulating water in the same manner as in the first embodiment. Furthermore, even when supplying the concentrated liquid to the radioactive nuclide removal device 15 after the concentration step S7, the execution order of the supply step S61, the radioactive nuclide concentration measurement S62, and the adsorbent supply step S61 does not matter, and either the supply step S61 or the radioactive nuclide concentration measurement S62 may be performed first.

[0075] The above-mentioned adsorbent supply process 61 to the radioactive waste liquid supply process S64, and the concentration process S7 are repeated (in multiple batches). Then, in the determination process S63 to determine whether the specified concentration can be achieved, if the specified concentration cannot be achieved (NO in S63), the reused concentrated liquid is subjected to the coagulation process S8 and the dewatering process S9, similar to the first embodiment described above. Specifically, after the supply process S61, in which the concentrated liquid generated in the concentration process S7 is supplied to the radioactive nuclide removal device 15, the concentrated liquid is supplied from the radioactive nuclide removal device 15 to the coagulation device 16 without supplying any new radioactive waste liquid to the radioactive nuclide removal device 15. Then, the coagulation process S8 and the dewatering process S9 are performed on the concentrated liquid in the coagulation device 16 and the dewatering device 20. After the coagulation process S8 and the dewatering process S9, the container filling or solidification process S10 is performed, similar to the flowchart shown in Figure 1 above.

[0076] In the multiple batch processing of radioactive waste liquid according to the flowchart in Figure 7 above, the process is repeated until the adsorption performance of the adsorbent at the concentration supplied to the radioactive nuclide removal device 15 is no longer sufficient to achieve the specified concentration for the next supply of radioactive waste liquid. When performing multiple batch processing in this manner, the number of times the radioactive waste liquid supply process S64 (removal process S6) is performed is determined from the concentration of radioactive nuclides in the radioactive waste liquid measured in the concentration measurement process S62, and the relationship between the adsorbent concentration and adsorption performance. For example, when supplying a radioactive nuclide removal device 15 supplied with adsorbent at the aforementioned adsorbent concentration of 10 g / L, and supplying radioactive waste liquid with an adsorbent concentration of 1 g / L required to achieve the specified concentration, 10 batch processes (steps S61-S64, S7) are possible. Then, before the 11th batch, new, unused adsorbent is supplied to the radioactive nuclide removal device 15 (S61), and the processing steps (steps S61-S64 and enrichment step S7) are repeated if the specified concentration can be achieved, such as measuring the radioactive nuclide concentration of the radioactive waste liquid.

[0077] According to the radioactive waste liquid treatment method of this embodiment, it is possible to achieve the specified concentration by removing radionuclides using the minimum necessary amount of adsorbent without the need to supply adsorbent each time, and to suppress the amount of radioactive waste generated by reducing the water content. Furthermore, it is possible to reduce the amount of radioactive waste containing long-half-life alpha nuclides.

[0078] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and the present invention is not necessarily limited to embodiments having all the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment. Furthermore, it is possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to delete or add / replace parts of the configuration of each embodiment. [Explanation of Symbols]

[0079] 1 Radioactive waste liquid treatment system, 2 High-dose resin storage tank, 3 First receiving tank, 4 Chemical reaction vessel, 5 Heating device, 6 Washing liquid supply tank, 7 Organic acid tank, 8 Organic acid salt tank, 9 Transfer water tank, 10 Chemical washing section, 11 Second receiving tank, 12 Incineration equipment, 13 Waste liquid decomposition device, 14 Radionuclide concentration measuring device, 15 Radionuclide removal device, 16 Coagulation device, 19 Waste liquid treatment section, 20 Dewatering device, 21 Solidification equipment, 22, 24, 32, 34, 43, 47 Transfer pumps, 23 Organic waste supply pipe, 25 Organic waste transfer pipe, 26, 27, 28, 35, 37, 39, 44 Valves, 29, 30, 31, 36, 38, 45, 46, 48, 49, 54, 55, 56 Piping, 33 Washing liquid supply pipe, 40 Waste liquid supply pipe, 121 Adsorbent supply device, 122 Coagulant supply device, 131 Concentration device

Claims

1. A concentration measurement process for measuring the concentration of radioactive nuclides in radioactive waste liquid, A step of removing radioactive nuclides by bringing an adsorbent into contact with the radioactive waste liquid and adsorbing the radioactive nuclides of the radioactive waste liquid onto the adsorbent, A concentration step to remove water from the radioactive waste liquid containing the adsorbent and increase the concentration of the adsorbent in the radioactive waste liquid, A coagulation step is performed by supplying a coagulant to the radioactive waste liquid after the concentration step to perform coagulation and sedimentation, The process includes a dewatering step of dewatering the radioactive waste liquid after coagulation and sedimentation, The concentration of the adsorbent in the concentration step is set to be equal to or greater than the concentration of the adsorbent at which the relationship between the concentration of the adsorbent and the water content of the radioactive waste is in equilibrium when the coagulant is supplied. Methods for treating radioactive liquid waste.

2. The amount of the adsorbent to be brought into contact with the radioactive waste liquid is determined from the concentration of the radioactive nuclide measured in the concentration measurement step, and the relationship between the concentration of the adsorbent and its adsorption performance. The method for treating radioactive waste liquid according to claim 1.

3. As the adsorbent, one or more selected from cation exchange resin, Fe oxide, titanate compound, titanate compound, ferrocyanine compound, chelate resin, activated carbon, oxin-impregnated activated carbon, zeolite, silica particles, and alumina particles are used. The method for treating radioactive waste liquid according to claim 1.

4. The concentration step and the dehydration step use one or more selected from cross-flow filtration, press filter filtration, and heating evaporation. The method for treating radioactive waste liquid according to claim 1.

5. As the flocculant, one or more selected from inorganic flocculants containing at least one of aluminum sulfate, polyaluminum chloride, ferric sulfate, and ferric chloride, and organic flocculants containing at least one of natural polymers and synthetic polymers are used. The method for treating radioactive waste liquid according to claim 1.

6. As the radioactive nuclide, one or more elements selected from metallic and nonmetallic elements are removed. The aforementioned metallic element is one or more selected from α-nuclides, transition metals, alkali metals, alkaline earth metals, and rare earth elements. The aforementioned nonmetallic element is one or more selected from antimony, tellurium, iodine, carbon, and boron. The method for treating radioactive waste liquid according to claim 1.

7. The α-nuclide includes one or more selected from plutonium, americium, curium, neptunium, and uranium. The transition metal comprises one or more selected from ruthenium, technetium, and niobium. The alkali metal includes cesium, The aforementioned alkaline earth metal includes strontium, The aforementioned rare earth elements include cerium The method for treating radioactive waste liquid according to claim 6.

8. In the removal process, the amount of adsorbent used in the removal process is determined from the concentration of the adsorbent at which the relationship between the concentration of the adsorbent and the water content of the radioactive waste is in equilibrium when the coagulant is supplied, and the process of bringing the adsorbent into contact with the radioactive waste liquid is carried out multiple times. The method for treating radioactive waste liquid according to claim 1.

9. The number of removal steps is determined by the concentration of the radioactive nuclide measured in the concentration measurement step, and This is determined from the relationship between the concentration of the adsorbent and its adsorption performance. The method for treating radioactive waste liquid according to claim 8.

10. A radionuclide concentration measuring device for measuring the concentration of radionuclides in radioactive waste liquid, A radioactive nuclide removal device comprising: bringing an adsorbent into contact with the radioactive waste liquid, wherein the adsorbent adsorbs the radioactive nuclides in the radioactive waste liquid; A concentration device that removes water from the radioactive waste liquid containing the adsorbent and sets the concentration of the adsorbent to a concentration of the adsorbent at or above the concentration of the adsorbent at which the relationship between the concentration of the adsorbent and the water content of the radioactive waste is in equilibrium when a coagulant is supplied, A coagulation device is provided which supplies the coagulant to the radioactive waste liquid from which the water has been removed, and which coagulates and settles the adsorbent, The system includes a dewatering device for dewatering the radioactive waste liquid after coagulation and sedimentation. A system for treating radioactive liquid waste.

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