Treatment method of radioactive waste liquid and radioactive waste liquid treatment system

Abstract

To provide a method for treating a radioactive waste liquid and a radioactive waste liquid treatment system capable of separating and treating α, β, γ nuclides.SOLUTION: A method for treating a radioactive waste liquid includes: a first measurement process for measuring β and γ nuclide concentration of a radioactive waste liquid; a first nuclide removal process for removing at least one of β and γ nuclides by adding β and γ nuclide adsorbents so as to maintain less than a predetermined pH when at least one of the β and γ nuclide concentration is equal to or more than a predetermined concentration in the first measurement process; and an α nuclide removal process for removing an α nuclide from a radioactive waste liquid in which at least one of β and γ nuclide concentration is less than a predetermined concentration in the first measurement process, or from a radioactive waste liquid subjected to the first nuclide removal process.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] As an example of a contaminated water treatment facility and method that can efficiently treat contaminated water containing radioactive materials while suppressing the amount of secondary waste, Patent Document 1 describes that the facility and method include a radiation measurement mechanism that measures the radionuclide concentration in the contaminated water, a water quality measurement mechanism that measures water quality information including the amount of ions coexisting in the contaminated water, a pretreatment mechanism that performs pretreatment of the contaminated water, a plurality of radionuclide removal mechanisms that remove radionuclides from the contaminated water, and a control unit that selects the mechanism required for treating the contaminated water from the pretreatment mechanism and the plurality of radionuclide removal mechanisms based on the measurement results of the radiation measurement mechanism and the water quality measurement mechanism. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-118283 Summary of the Invention [Problem to be solved by the invention]

[0004] Radioactive organic wastes, such as filter sludge containing cellulose-based filter aids and ion exchange resins, generated from reactor coolant purification systems, fuel pool coolant purification systems, etc., of nuclear power plants are stored for long periods in storage tanks. These radioactive organic wastes are generated regularly during the operation of nuclear power plants.

[0005] In order to secure storage space for radioactive organic waste, volume reduction treatment is being carried out to efficiently reduce the volume of radioactive organic waste currently in storage (see, for example, Patent Document 1).

[0006] In the technology described in Patent Document 1, radioactive liquid waste containing α, β, and γ radionuclides is reduced in volume by removing the nuclides using an adsorbent, recovering and concentrating the adsorbent (waste adsorbent) or colloid after nuclide adsorption using cross-flow filtration, coagulating and precipitating the waste adsorbent, and dehydrating the supernatant water.

[0007] The waste adsorbent after the above treatment needs to be stored in a storage container for a long period until disposal, and the dose in the storage container needs to be managed taking into consideration the reduction of worker exposure and the amount of radiation at the site boundary. Furthermore, when the waste adsorbent is finally disposed of, it may be necessary to separate it into alpha, beta, and gamma nuclides from the perspective of radioactive waste classification.

[0008] However, the technology described in the above-mentioned Patent Document 1 has the problem that it does not separate α, β, and γ nuclides. This may result in the upper concentration limits for the disposal categories established for each α, β, and γ nuclide. This may increase the amount of radioactive waste at the time of disposal and may increase processing costs, so improvements are required.

[0009] In order to solve the above-mentioned problems, the present invention provides a method and system for treating radioactive liquid waste that can separate and treat alpha, beta and gamma nuclides. [Means for solving the problem]

[0010] The present invention includes a plurality of means for solving the above-mentioned problems, and examples thereof include a first measurement step of measuring the β nuclide concentration and the γ nuclide concentration of the radioactive liquid waste, a first β,γ nuclide removal step of removing at least one of the β nuclide and the γ nuclide by adding a β,γ nuclide adsorbent so as to maintain the pH below a predetermined value when at least one of the β nuclide concentration and the γ nuclide concentration is at or above a predetermined value in the first measurement step, and an α nuclide removal step of removing α nuclide from the radioactive liquid waste in which at least one of the β nuclide concentration and the γ nuclide concentration is below the predetermined value in the first measurement step, or from the radioactive liquid waste that has been subjected to the first β,γ nuclide removal step. [Effects of the Invention]

[0011] According to the present invention, α-, β-, and γ-nuclides can be separated and treated. Objects, configurations, and effects other than those described above will become apparent from the following description of the examples. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a flowchart showing the steps of a method for treating radioactive liquid waste according to a first embodiment. [Figure 2] 1 is a diagram showing an example of the configuration of a radioactive liquid waste treatment system according to a first embodiment. [Figure 3] FIG. 2 is a diagram showing a detailed configuration of the radioactive waste liquid treatment system of the first embodiment, from a radionuclide concentration measuring device to a radionuclide removal device. [Figure 4] FIG. 10 is a graph showing the relationship between the inlet cesium concentration and the amount of cesium adsorbed by the α nuclide adsorbent. [Figure 5] FIG. 1 is a diagram showing the relationship between the solid-liquid ratio of a β,γ nuclide adsorbent and the Cs adsorption amount and the Am adsorption amount. [Figure 6] FIG. 1 is a graph showing the effect of pH on the amount of α-nuclides adsorbed by an α-nuclides adsorbent. [Figure 7] FIG. 2 is a diagram showing another example of the detailed configuration of the radioactive waste liquid treatment system of the first embodiment, from the radionuclide concentration measuring device to the radionuclide removal device. [Figure 8] 10 is a flowchart showing the procedure of a method for treating radioactive liquid waste according to a second embodiment. [Figure 9] FIG. 10 is a diagram showing a detailed configuration of the radioactive waste liquid treatment system of the second embodiment, from a radionuclide concentration measuring device to a radionuclide removal device. DETAILED DESCRIPTION OF THE INVENTION

[0013] The radioactive liquid waste treatment method and radioactive liquid waste treatment system according to the embodiments of the present invention will be described below with reference to text and drawings. However, the structures, materials, and other specific configurations shown in the present invention are not limited to the embodiments and examples described here, and can be appropriately combined and improved within the scope that does not change the gist of the present invention.

[0014] Furthermore, elements not directly related to the present invention are omitted for convenience of illustration. Furthermore, in the drawings used in this specification, identical or similar reference numerals are used to denote identical or corresponding elements, and repeated explanations of these elements may be omitted.

[0015] The above-mentioned object of providing a method for treating radioactive liquid waste that can reduce the amount of radioactive waste generated can be achieved by the following method for treating radioactive liquid waste and system for treating radioactive liquid waste.

[0016] First Embodiment A first embodiment of a method for treating radioactive liquid waste and a radioactive liquid waste treatment system according to the present invention will be described with reference to Figures 1 to 7. The method for treating radioactive liquid waste according to this embodiment is applied to the treatment of radioactive waste generated in a nuclear power plant.

[0017] First, the details of each of steps S1 to S9 of the method for treating radioactive liquid waste of this embodiment will be described with reference to Fig. 1. Fig. 1 is a flow chart showing the procedure of the method for treating radioactive liquid waste of the first embodiment.

[0018] In a nuclear power plant, for example, a boiling water nuclear power plant currently in operation, fuel assemblies are loaded into the reactor core within the reactor pressure vessel, and spent fuel assemblies are stored in a fuel storage pool. The fuel rods of these fuel assemblies are provided with cladding tubes.

[0019] If the cladding tube were to break, the nuclear fuel material (including alpha nuclides such as uranium, plutonium, neptunium, americium, and curium) and radioactive nuclides (including strontium, the source of beta nuclides, and cesium, the gamma nuclides) in the fuel rods would leak into the cooling water in the reactor pressure vessel and the cooling water in the fuel storage pool. Radioactive nuclides that leak into the cooling water in the reactor pressure vessel are removed by ion exchange resins in the purification device of the reactor coolant purification system. Radioactive nuclides that leak into the cooling water in the fuel storage pool are also removed by ion exchange resins in the purification device of the fuel pool coolant purification system.

[0020] Filter sludge (radioactive organic waste) containing cellulose-based filter aids and ion exchange resins, which is generated from the reactor coolant purification system and fuel pool coolant purification system of a boiling water nuclear power plant, is stored for a long period of time in a high-dose resin storage tank. After a predetermined storage period has elapsed, the radioactive organic waste stored in the high-dose resin storage tank is removed from the high-dose resin storage tank.

[0021] The radioactive organic waste containing the cation exchange resin removed from the high-dose resin storage tank is subjected to a first cleaning step (crad dissolving step) S1 shown in FIG.

[0022] In the first cleaning step S1, an aqueous solution of a reducing organic acid (e.g., an aqueous solution of oxalic acid) is brought into contact with the radioactive organic waste. The organic acid contained in this aqueous solution dissolves crud such as iron oxide contained in the radioactive organic waste. Radionuclides such as cobalt-60 contained in the crud are transferred into the organic acid aqueous solution as the crud is dissolved.

[0023] The organic acid used in the first cleaning step S1 is mainly composed of carbon, hydrogen, oxygen, and nitrogen. Therefore, by using an organic acid in the first cleaning step S1, when the organic acid aqueous solution generated as cleaning waste liquid in the first cleaning step S1 is subjected to oxidation treatment using, for example, ozone (waste liquid decomposition step S4 described below), no nonvolatile residue is generated in the waste liquid. 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.

[0024] The radioactive organic waste that has been subjected to the first cleaning step S1 and from which the crud has been dissolved is subjected to a second cleaning step (radionuclide elution step) S2.

[0025] In this second cleaning step S2, an aqueous solution of an organic acid salt is brought into contact with the radioactive organic waste in which the crud has been dissolved, and the radioactive nuclides, such as alpha nuclides, adsorbed to the radioactive organic waste are eluted by the organic acid salt contained in the aqueous solution.

[0026] The organic acid salt used in the second cleaning step S2 is preferably an organic acid salt that dissociates in the aqueous solution to produce cations that are more easily adsorbed by the cation exchange resin than hydrogen ions. In other words, the organic acid salt is preferably one whose main constituent elements are carbon, hydrogen, oxygen, and nitrogen, and which does not produce nonvolatile residues in the wastewater when the organic acid salt aqueous solution, which is the cleaning wastewater after the second cleaning step S2, is subjected to oxidation treatment, for example, using ozone (wastewater decomposition step S4). As the organic acid salt, for example, ammonium salts, barium salts, or cesium salts of formic acid, oxalic acid, acetic acid, or citric acid are preferably used. Hydrazine formate may also be used as the organic acid salt.

[0027] Ammonium salts are decomposed into nitrogen gas and water by oxidation treatment, so they can generate less radioactive waste than barium salts and cesium salts. Ammonium salts of formic acid, oxalic acid, acetic acid, or citric acid, as well as barium and cesium salts, dissociate in aqueous solution to form NH4 + , Ba 2+ or Cs +NH4 + , Ba 2+ or Cs + is a cation that is more easily adsorbed by a cation exchange resin than a hydrogen ion.

[0028] The radioactive organic waste separated from the eluate of radionuclides in the second washing step S2 is subjected to the incineration and solidification step S3. The radioactive organic waste separated from the eluate of radionuclides is transferred to an incineration facility and incinerated there, and the ash produced by the incineration is solidified in a solidification vessel with a solidifying agent such as cement.

[0029] The organic acid solution (clad solution) containing dissolved components of the crud, which is generated as a cleaning waste liquid in the first cleaning step S1, is subjected to a waste liquid decomposition step (a step of decomposing either an organic acid or an organic acid salt) S4. The organic acid solution (organic acid solution) containing eluted radionuclides such as alpha nuclides, which is generated as a cleaning waste liquid in the second cleaning step S2, is also subjected to the waste liquid decomposition step S4.

[0030] In the waste liquid decomposition step S4, an oxidizing agent such as ozone or hydrogen peroxide is aerated into an aqueous solution of an organic acid or an aqueous solution of an organic salt, and the organic acid or organic salt is decomposed by the oxidizing action of the oxidizing agent.

[0031] After the organic acid or organic acid salt is decomposed in the waste liquid decomposition step S4, the beta nuclide concentration and the gamma nuclide concentration are measured for the remaining aqueous solution containing radionuclides (radioactive waste liquid) (radioactive nuclide concentration measurement S5). This radioactive nuclide concentration measurement S5 corresponds to the first measurement step.

[0032] In this radionuclide concentration measurement S5, it is desirable to also measure the alpha nuclide concentration for the radioactive liquid waste.

[0033] In this radionuclide concentration measurement S5, the radioactive liquid waste may be sampled and measured continuously or intermittently by an analyzer, or may be measured intermittently by a survey meter, or may be measured online.

[0034] Next, a step of determining whether or not at least one of the β nuclide concentration and the γ nuclide concentration is equal to or greater than a predetermined concentration in the radionuclide concentration measurement S5 (β, γ nuclide concentration determination step) S5A is carried out.

[0035] The predetermined concentration used in this β, γ nuclide concentration determination step S5A can be determined from the relationship between the β nuclide concentration or γ nuclide concentration at the start of the α nuclide removal step S7 described later and the β, γ nuclide adsorption amount of the α nuclide adsorbent.

[0036] In the β, γ nuclide concentration determination step S5A, if it is determined that both the β nuclide concentration and the γ nuclide concentration are less than the predetermined concentration, the β, γ nuclide removal step S6 is omitted and the process proceeds to the subsequent α nuclide removal step S7.

[0037] On the other hand, if it is determined in the β,γ nuclide concentration determination step S5A that at least one of the β nuclide concentration and the γ nuclide concentration is equal to or greater than the predetermined concentration, a step of removing at least one of the β nuclide and the γ nuclide by adding a β,γ nuclide adsorbent so as to maintain the pH below a predetermined value (β,γ nuclide removal step) S6 is carried out. This β,γ nuclide removal step S6 corresponds to the first β,γ nuclide removal step.

[0038] The amount of β,γ nuclide adsorbent used in this β,γ nuclide removal step S6 can be determined from the relationship between the solid-liquid ratio of the β,γ nuclide adsorbent and the β,γ nuclide adsorption amount and the α nuclide adsorption amount. Furthermore, a pH lower than the predetermined value can be determined from the effect of pH on the α nuclide adsorption amount of the α nuclide adsorbent. Furthermore, in the β,γ nuclide removal step S6, a pH lower than the predetermined value can be maintained by using a type of β,γ nuclide adsorbent that keeps the increase or decrease of pH below the predetermined pH.

[0039] Next, α nuclides are removed from the radioactive liquid waste in which either one or more of the β nuclide concentration and the γ nuclide concentration is less than a predetermined concentration in the above-mentioned radioactive nuclide concentration measurement S5, or from the radioactive liquid waste that has been subjected to the β, γ nuclide removal step S6 (α nuclide removal step S7). This α nuclide removal step S7 corresponds to the α nuclide removal step.

[0040] After the removal of the α nuclides, the concentrations of β and γ nuclides in the radioactive liquid waste are measured again, and a step (radioactive nuclide concentration measurement and determination step) S7A is carried out to determine whether the concentrations of β and γ nuclides are less than the predetermined concentrations. This radioactive nuclide concentration measurement and determination step S7A corresponds to the second measurement step.

[0041] Here, in this radionuclide concentration measurement and determination step S7A, similar to the radionuclide concentration measurement step S5, the concentration can be measured by any of the following methods: sampling the radioactive waste liquid and measuring it with an analytical device, measuring it with a survey meter, or measuring it online.

[0042] If the concentrations of β and γ nuclides are below the final target concentrations, or after the β and γ nuclides have been removed so that they are below the final target concentrations in the β and γ nuclide removal step S8, the waste liquid is directly stored, treated, and disposed of S9. The waste liquid after treatment may be circulated and used as cleaning water in the first cleaning step S1 and the second cleaning step S2.

[0043] On the other hand, when at least one of the β nuclide concentration and the γ nuclide concentration is equal to or greater than the final target concentration in the step S7A of measuring and determining the concentration of radioactive nuclides, a step (β,γ nuclide removal step) S8 of removing at least one of the β nuclide and the γ nuclide using a β,γ nuclide adsorbent until the concentration becomes less than the final target concentration is carried out. This β,γ nuclide removal step S8 corresponds to the second β,γ nuclide removal step.

[0044] After this β and γ nuclide removal step S8, it is not necessary to measure the β and γ nuclide concentrations again, and it may or may not be performed. For example, if it is known that the conditions are such that they can be completely removed, it can be omitted, or it can be performed for safety reasons.

[0045] In these β and γ nuclide removal steps S6 and S8 and α nuclide removal step S7, an adsorbent for radioactive nuclides is supplied to the radioactive liquid waste.

[0046] In these removal steps, the radioactive liquid waste is brought into contact with an adsorbent, so that the radionuclides in the radioactive liquid waste are adsorbed onto the adsorbent, and the radionuclides are removed from the liquid phase of the radioactive liquid waste.

[0047] The adsorbent may be, for example, one or more selected from cation exchange resins, Fe oxides, titanic acid compounds, silicic titanic acid compounds, titanate compounds, ferrocyanide compounds, chelating resins, activated carbon, oxine-impregnated activated carbon, zeolite, silica particles, alumina particles, and the like.

[0048] In this way, one or more of the β, γ nuclide removal steps S6 and S8 can be performed by supplying a β, γ nuclide adsorbent to the radioactive waste liquid, or by passing the radioactive waste liquid through a container filled with a β, γ nuclide adsorbent.

[0049] After the removal of alpha, beta, and gamma nuclides is complete, the radioactive liquid waste is separated into solids such as waste adsorbent and slurry from the liquid waste from which the radionuclides have been removed by filtering using a cross-flow method, filtering using a press filter, concentrating using an evaporator, etc., flocculating by adding a flocculant, and dehydrating using a dehydrator, etc., and then solidifying using a solidifying agent, before being filled into containers for storage, treatment, and disposal (storage, treatment, and disposal step) S9. This storage, treatment, and disposal step S9 corresponds to the separation step.

[0050] When a flocculant is used in this storage, treatment and disposal step S9, the flocculant can be one or more selected from inorganic flocculants including at least one of aluminum sulfate, polyaluminum chloride, ferric sulfate and ferric chloride, and organic flocculants including at least one of natural polymers and synthetic polymers.

[0051] The waste liquid after the treatment may be circulated and used as washing water in the first washing step S1 and the second washing step S2.

[0052] Next, the configuration of a radioactive liquid waste treatment system according to this embodiment, which is capable of carrying out the above-described method for treating radioactive liquid waste, will be described with reference to Figures 2 to 7. Figure 2 is a diagram showing an example of the configuration of a radioactive liquid waste treatment system according to the first embodiment, and Figures 3 and 7 are diagrams showing an example of the detailed configuration from the radionuclide concentration measuring device to the radionuclide removal device.

[0053] The radioactive liquid waste treatment system 1 shown in FIG. 2 includes a chemical cleaning unit 10 that treats radioactive organic waste, and a waste liquid treatment unit 19 that treats cleaning waste liquid (radioactive liquid waste) discharged from the chemical cleaning unit 10.

[0054] The chemical cleaning section 10 has a first receiving tank 3, a chemical reaction tank (cleaning tank) 4, a cleaning liquid supply tank 6, an organic acid tank 7, an organic acid salt tank 8, and a transfer water tank 9. A high-dose resin storage tank 2 is provided upstream of the chemical cleaning section 10, and a second receiving tank 11 and an incineration facility (or cement solidification facility) 12 are provided below the chemical cleaning section 10 in the drawing.

[0055] In the chemical cleaning section 10, of the steps shown in FIG. 1, a first cleaning step S1 for dissolving the crud and a second cleaning step S2 for eluting radioactive nuclides from the radioactive organic waste are carried out.

[0056] In the chemical cleaning section 10, an organic waste supply pipe 23 equipped with a transfer pump 22 connects the high-dose resin storage tank 2 and the first receiving tank 3.

[0057] The chemical reaction tank 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 tank 4.

[0058] The cleaning liquid supply tank 6 is connected to the chemical reaction tank 4 by a cleaning liquid supply pipe 33 to which a transfer pump 32 is attached.

[0059] A return pipe 36 connected to the bottom of the chemical reaction tank 4 and equipped with a transfer pump 34 and a valve 35 is connected to the cleaning liquid supply tank 6 .

[0060] A pipe 29 equipped with a valve 26 is connected to an organic acid tank 7 filled with an aqueous organic acid solution, for example, an aqueous oxalic acid solution, and is connected to the cleaning liquid supply tank 6. The aqueous oxalic acid solution filled in the organic acid tank 7 is a saturated aqueous solution, and the oxalic acid concentration of the aqueous oxalic acid solution is, for example, 0.8 mol / L.

[0061] A pipe 30 equipped with a valve 27 is connected to an organic acid salt tank 8 filled with an aqueous solution of an organic acid salt, for example, an aqueous solution of formic acid hydrazine. The pipe 30 is connected to a pipe 29 downstream of the valve 26 .

[0062] A pipe 31 connected to a transfer water tank 9 filled with water to be transferred and provided with a valve 28 is connected to a pipe 30 downstream of the valve 27 .

[0063] A pipe 38 equipped with a valve 37 and connected to the bottom of the chemical reaction tank 4 is connected to the second receiving tank 11 .

[0064] The pipe connected to the second receiving tank 11 is connected to an incineration facility (or cement solidification facility) 12.

[0065] The waste liquid treatment unit 19 includes a waste liquid decomposition device 13, radionuclide concentration measuring devices 14A and 14B, a radionuclide removal device 15, a flocculation device 16, a dehydration device 20, an adsorbent supply device 121, a flocculant supply device 122, and a concentration device 131.

[0066] In the waste liquid treatment unit 19, of the processes shown in Figure 1, from the waste liquid decomposition process S4, which decomposes the organic acid in the organic acid aqueous solution containing the dissolved components of the crud, to the storage, treatment and disposal of the waste adsorbent S9, are carried out.

[0067] A waste liquid supply pipe 40 equipped with a valve 39 is connected to the return pipe 36 between the transfer pump 34 and the valve 35 of the chemical cleaning section 10 on the upstream side, and is connected to the waste liquid decomposition device 13 on the downstream side.

[0068] A pipe 45 equipped with a transfer pump 43 and a valve 44 is connected to the liquid waste decomposition apparatus 13 and the radionuclide removal apparatus 15. This pipe 45 is a supply pipe for the radioactive liquid waste that leads the radioactive liquid waste containing radionuclides to the radionuclide removal apparatus 15 in the above-mentioned method for treating radioactive liquid waste. A radionuclide concentration measuring apparatus 14A and an adsorbent supplying apparatus 121 are connected to this pipe 45.

[0069] The pipe 46 is connected to the radionuclide removal device 15, the concentration device 131, and the flocculation device 16. The flocculation agent supply device 122 is connected to the flocculation device 16.

[0070] A pipe 48 equipped with a transfer pump 47 is connected to the flocculation device 16 and the dehydration device 20 , and a pipe 49 is further connected to the dehydration device 20 and the solidification equipment 21 .

[0071] A pipe 55 is connected to the concentrator 131, which is connected between the transfer pump 34 and the valve 35 of the return pipe 36 of the chemical cleaning unit 10. The filtered water, from which the adsorbent and the slurry containing radionuclides have been separated by filtration in the concentrator 131, returns to the return pipe 36 through the pipe 55. This allows the filtered water to be circulated as circulating water.

[0072] In addition, valves (not shown) are provided upstream of the connection between the return pipe 36 and pipe 55 on each pipe 36, 55 (on the chemical reaction tank 4 side and the concentration device 131 side) to enable switching between water from the chemical reaction tank 4 and filtered water from pipe 55.

[0073] The dehydration device 20 may include, for example, a solid-liquid separator using a cross-flow filter method that uses a membrane with a pore size on the order of μm or less, a solid-liquid separator using a press filter method that performs filtration by pressure, or a solid-liquid separator that performs concentration by an evaporation concentration method that uses an evaporator.

[0074] Similar to the concentrating device 131 described above, the dehydrating device 20 is connected to a pipe 56 that is connected between the transfer pump 34 and the valve 35 of the return pipe 36 of the chemical cleaning section 10. The water from which radionuclides have been removed and dehydrated in the dehydrating device 20 returns to the return pipe 36 through the pipe 56. This allows the water to be circulated as circulating water. Valves (not shown) are provided on the upstream side of each pipe 36, 56 (on the chemical reaction tank 4 side and the dehydrating device 20 side) of the connection between the return pipe 36 and the pipe 56, respectively, to enable switching between the water from the chemical reaction tank 4 and the water from the pipe 56. Furthermore, the dehydrating device 20 can perform dehydration using a cross-flow filter method, a press filter method, or the like, as described for the concentrating device 131.

[0075] There is no limitation on the timing for transferring the radioactive liquid waste from the chemical cleaning unit 10 to the liquid waste treatment unit 19. For example, a sampling valve may be attached to the return pipe 36, and the radioactive liquid waste collected by the sampling valve may be periodically analyzed, so that the radioactive liquid waste may be transferred when the measured concentration of radionuclides reaches a desired concentration.

[0076] Next, details of the configuration around the radionuclide removal device 15 in the waste liquid treatment unit 19 shown in Fig. 2 will be described with reference to Fig. 3. Fig. 3 also shows piping connected to the radionuclide removal device 15 and components (tanks, devices, etc.) installed nearby.

[0077] As shown in Figure 3, the radioactive nuclide removal device 15 has a β, γ nuclide removal device 101, an α nuclide removal device 102, etc., and is composed of a waste liquid treatment tank that contains radioactive waste liquid sent from the waste liquid decomposition device 13 through piping 45.

[0078] A radionuclide concentration measuring device 14A that measures the beta and gamma nuclide concentrations in the radioactive waste liquid is connected to the piping 45, which is a supply pipe for the radioactive waste liquid connected to the beta, gamma nuclide removal device 101, and a radionuclide concentration measuring device 14B that measures the beta and gamma nuclide concentrations in the radioactive waste liquid from which the alpha nuclides have been removed by the alpha nuclide removal device 102 is connected to the piping 46, which is a discharge pipe for the radioactive waste liquid connected to the alpha nuclide removal device 102.

[0079] In addition, the radionuclide concentration measuring devices 14A, 14B can also be configured not to be connected to the waste liquid treatment device 19, but to measure the radionuclide concentration of the sampled radioactive waste liquid, and to reflect the determination result in the amount of adsorbent supplied by the adsorbent supply device 121.

[0080] Here, when the concentration of radionuclides in the radioactive waste liquid is measured by the radionuclide concentration measuring device 14A and the result is that the concentration of the radionuclides is equal to or lower than a predetermined concentration, the radioactive waste liquid may be returned to the return pipe 36 through the pipe 54 and circulated as circulating water.

[0081] As a result of measuring the concentrations of radionuclides in the radioactive liquid waste, if the concentrations of β and γ nuclides are equal to or higher than a predetermined concentration (described later in FIG. 4), the radioactive liquid waste is supplied to the β,γ nuclide removal device 101. Before supplying the radioactive liquid waste to the β,γ nuclide removal device 101, the pH of the radioactive liquid waste may be adjusted to control its chemical form.

[0082] The β,γ nuclide removal device 101 is a device that removes at least one of β nuclides and γ nuclides by adding a β,γ nuclide adsorbent to radioactive liquid waste in which at least one of the β nuclide concentration and the γ nuclide concentration is measured to be at or above a predetermined concentration by the radioactive nuclide concentration measuring device 14A so as to maintain the pH below a predetermined value, and is a suitable entity for carrying out the β,γ nuclide removal step S6.

[0083] In the β,γ nuclide removal apparatus 101, an adsorbent is supplied from an adsorbent supply device 121. Then, the radioactive liquid waste is brought into contact with the adsorbent in the β,γ nuclide removal apparatus 101. As a result, in the β,γ nuclide removal apparatus 101, the β,γ nuclides are adsorbed by the adsorbent, and the β,γ nuclides are removed from the liquid phase of the radioactive liquid waste.

[0084] In addition, when the concentrations of β and γ nuclides are less than a predetermined concentration, water may be passed through the β,γ nuclide removal device 101 and into the α nuclide removal device 102 via a pipe 103 for bypassing the β,γ nuclide removal device 101.

[0085] In the β, γ nuclide removal device 101, radioactive waste liquid in which the β, γ nuclides have been adsorbed by the adsorbent to a concentration below a predetermined level, or radioactive waste liquid in which the radioactive nuclide concentration measuring device 14A has measured that at least one of the β nuclide concentration and the γ nuclide concentration is below a predetermined level, is supplied to the α nuclide removal device 102 through piping 45.

[0086] The α nuclide removal device 102 is a device that removes α nuclides from radioactive liquid waste in which β and γ nuclides have been adsorbed by an adsorbent to a concentration below a predetermined level, or from radioactive liquid waste in which the radionuclide concentration measuring device 14A has measured that at least one of the β nuclide concentration and the γ nuclide concentration is below a predetermined level.

[0087] In the α-nuclide removal equipment 102, an adsorbent is supplied from an adsorbent supplying equipment 121. Then, the radioactive liquid waste is brought into contact with the adsorbent in the α-nuclide removal equipment 102. As a result, in the α-nuclide removal equipment 102, the α-nuclide is adsorbed by the adsorbent, and the α-nuclide is removed from the liquid phase of the radioactive liquid waste.

[0088] In addition, when the radioactive liquid waste has passed through the α nuclide removal device 102 once and either one or more of the β nuclide concentration and the γ nuclide concentration is equal to or greater than the final target concentration, the radioactive liquid waste after having either one or more of the β nuclide and the γ nuclide concentration removed by the β,γ nuclide adsorbent until the concentration becomes less than the final target concentration may be passed through the piping 46, bypassing the α nuclide removal device 102, via the piping 103A for bypassing the α nuclide removal device 102.

[0089] The radioactive liquid waste in which the α nuclides have been adsorbed by the adsorbent in the α nuclide removal device 102 until the concentration is less than a predetermined value is supplied to the concentrator 131 through the pipe 46. At this time, a radioactive nuclide concentration measuring device 14B is connected to the pipe 46, and as a result of measuring the concentrations of the β, γ nuclides in the radioactive liquid waste, if the concentrations of the β, γ nuclides are equal to or greater than the final target concentration, the radioactive liquid waste is supplied to the β, γ nuclide removal device 101 through the pipe 104. In the β, γ nuclide removal device 101, the radioactive liquid waste in which the β, γ nuclides have been adsorbed by the adsorbent until the concentrations are less than the final target concentration is supplied to the concentrator 131 through the pipe 46.

[0090] Here, the criteria for determining whether the β and γ nuclides are above or below a predetermined concentration by measuring the radionuclide concentration will be explained with reference to the relationship between the inlet cesium (Cs) concentration and the amount of Cs adsorbed by the α nuclide adsorbent in Fig. 4. The example shown in Fig. 4 shows the results using 100-fold diluted simulated seawater (pH 6) as the test liquid, Cs as the γ nuclide, and magnetite (Fe3O4) as the α nuclide adsorbent.

[0091] As shown in Figure 4, it was confirmed that the amount of Cs adsorption increased as the inlet Cs concentration increased.

[0092] For example, if you want to dispose of waste adsorbent in a radioactive waste classification equivalent to pit disposal, the amount of Cs adsorbed by Fe3O4 is 4 x 10 11 It is desirable to keep the inlet Cs concentration below 4×10 7 If the concentration is above 4×10 Bq / L (beta and gamma nuclides are above the specified concentration), the Cs concentration is increased to 4×10 before removing the alpha nuclides. 7 It is desirable to remove the β and γ nuclides to less than Bq / L. In this way, by determining whether or not it is necessary to remove the β and γ nuclides before removing the α nuclides (whether or not the β and γ nuclides are at or above a predetermined concentration) from the adsorption amounts of the β and γ nuclides in the α nuclide adsorbent, it is possible to provide a method for treating radioactive liquid waste that can more accurately separate and treat the α nuclides, β nuclides, and γ nuclides.

[0093] Next, in the removal of β and γ nuclides before the removal of α nuclides, a method of selectively adsorbing β and γ nuclides without adsorbing α nuclides to the β and γ nuclide adsorbent as much as possible will be explained with reference to the relationship between the solid-liquid ratio of the β and γ nuclide adsorbent and the Cs adsorption amount and the Am adsorption amount in Fig. 5. The example shown in Fig. 5 shows the results using 100-fold diluted simulated seawater (pH 6) as the test liquid, Cs as the γ nuclide, americium (Am) as the α nuclide, and a silicic titanate compound (CST) as the β and γ nuclide adsorbent.

[0094] As shown in Figure 5, if a large amount of CST is used (solid-liquid ratio 1:1000), the pH of the waste liquid will change to the alkaline side (pH 6 → 10), and it is expected that a large amount of Am will be adsorbed in addition to Cs.8 It is expected that the amount of Am adsorbed will be more than Bq / t.

[0095] In contrast, by using a small amount of CST (solid-liquid ratio 1:10000) to adsorb Cs while maintaining a neutral pH (pH 6 to 7), the amount of Am adsorbed increased by 5 × 10 without changing the amount of Cs adsorbed. 8 It can be kept below Bq / t.

[0096] By controlling the solid-liquid ratio of the β,γ nuclide adsorbent in this way, it is possible to treat the β,γ nuclide adsorbent so that it selectively adsorbs β,γ nuclide while minimizing the adsorption of α nuclide, and it is possible to provide a method for treating radioactive liquid waste that can more accurately separate and treat α nuclide, β nuclide, and γ nuclide.

[0097] Furthermore, as described above, another effect obtained by removing β and γ nuclides while maintaining a neutral pH and not alkaline by controlling the solid-liquid ratio of the β and γ nuclide adsorbent and passing the water through the α nuclide removal device will be explained with reference to the effect of pH on the amount of α nuclide adsorption by the α nuclide adsorbent in Fig. 6. The example shown in Fig. 6 shows the results using 100-fold diluted simulated seawater as the test liquid, Am as the α nuclide, and Fe3O4 as the α nuclide adsorbent.

[0098] As shown in Figure 6, the distribution coefficient (Kd) of Am in Fe3O4 is higher under neutral pH conditions than under alkaline conditions. In this way, by controlling the solid-liquid ratio of the β,γ nuclide adsorbent, the pH is maintained neutral rather than alkaline, and β,γ nuclides are removed, and the water is passed through the α nuclide removal device, improving the adsorption performance of the α nuclide adsorbent and reducing the amount of waste.

[0099] In the method for treating radioactive liquid waste according to the present embodiment, radionuclides other than those mentioned above may also be targeted for removal.

[0100] Target alpha nuclides include, in addition to uranium, plutonium, neptunium, americium, and curium, one or more of the following metal elements: transition metals such as ruthenium, technetium, and niobium; alkali metals such as cesium; alkaline earth metals such as strontium; and rare earth elements such as cerium; and non-metallic elements: halogens such as antimony, tellurium, and iodine; carbon; and boron.

[0101] Furthermore, in the first embodiment described above, the β and γ nuclides are simultaneously removed in the β and γ nuclide removal steps S6 and S8, but they may be removed individually.

[0102] Furthermore, the β,γ nuclide removal step S6 and the α nuclide removal step S7 can be carried out simultaneously based on the relationship between the solid-liquid ratio of the β,γ nuclide adsorbent and the β,γ nuclide adsorption amount and the α nuclide adsorption amount in the α nuclide removal step S7. For example, when it is not necessary to separate and treat α, β, and γ nuclides, a large amount of CST can be used to change the pH to alkaline, as shown in Figure 5, and α and β,γ nuclides can be removed simultaneously.

[0103] Furthermore, in the above-described first embodiment, when β and γ nuclides are removed to the final target concentration, the β and γ nuclides are circulated through the piping 104 and removed to the final target concentration in the same β,γ nuclide removal device 101, but the present invention is not limited to this.

[0104] Another embodiment will be described with reference to Fig. 7. Similar to Fig. 3, Fig. 7 shows the periphery of the radionuclide removal device 15A in the waste liquid treatment unit 19, along with piping connected to the radionuclide removal device 15A and components (tanks, devices, etc.) provided nearby.

[0105] As shown in the radionuclide removal device 15A in FIG. 7, the β,γ nuclide removal device 101A removes either one or more of the β nuclide and the γ nuclide by adding a β,γ nuclide adsorbent to maintain a pH below a predetermined level for radioactive waste liquid in which the radionuclide concentration measuring device 14A has measured that either one or more of the β nuclide concentration and the γ nuclide concentration is equal to or higher than a predetermined level. An α nuclide removal device 102 is provided downstream of the β,γ nuclide removal device 101A, which removes either one or more of the β nuclide and the γ nuclide by adding a β,γ nuclide adsorbent to maintain a pH below a predetermined level for radioactive waste liquid in which the radionuclide concentration measuring device 14A has measured that either one or more of the β nuclide concentration and the γ nuclide concentration is lower than a predetermined level, or from radioactive waste liquid from which either one or more of the β nuclide and the γ nuclide has been removed by the β,γ nuclide removal device 101A.

[0106] Furthermore, at the downstream of the α nuclide removal device 102, a β,γ nuclide removal device 101B is provided which, when at least one of the β nuclide concentration and the γ nuclide concentration is equal to or greater than the final target concentration in the radioactive nuclide concentration measurement and determination step S7A, removes at least one of the β nuclide and the γ nuclide by a β,γ nuclide adsorbent until the concentration becomes less than the final target concentration.

[0107] In addition, also in FIG. 7, a bypass line that bypasses the α nuclide removal device 102 and the β,γ nuclide removal device 101B can be provided, and the α nuclide removal device 102 and the β,γ nuclide removal device 101B can be bypassed depending on the β nuclide concentration, the γ nuclide concentration, and the α nuclide concentration.

[0108] In the example of the first embodiment, the adsorbent is injected into the β,γ nuclide removal devices 101, 101A, 101B and the α nuclide removal device 102, but the adsorbent may be filled in the β,γ nuclide removal devices 101, 101A, 101B and the α nuclide removal device 102 in advance, and the radioactive waste liquid may be passed through the radioactive nuclide removal devices filled with the adsorbent.

[0109] Next, the effects of this embodiment will be described.

[0110] The method for treating radioactive liquid waste according to the first embodiment of the present invention described above includes a radionuclide concentration measurement S5 in which the β nuclide concentration and the γ nuclide concentration of the radioactive liquid waste are measured, a β,γ nuclide removal step S6 in which, when at least one of the β nuclide concentration and the γ nuclide concentration is equal to or greater than a predetermined concentration in the radionuclide concentration measurement S5, a β,γ nuclide adsorbent is added to maintain a pH below a predetermined level to remove at least one of the β nuclide and the γ nuclide, and an α nuclide removal step S7 in which α nuclide is removed from the radioactive liquid waste in which at least one of the β nuclide concentration and the γ nuclide concentration is less than the predetermined level in the radionuclide concentration measurement S5, or from the radioactive liquid waste that has been subjected to the β,γ nuclide removal step S6.

[0111] The radioactive liquid waste treatment system 1 of the first embodiment also comprises a radioactive nuclide concentration measuring device 14A that measures the β nuclide concentration and the γ nuclide concentration of the radioactive liquid waste, β,γ nuclide removal devices 101, 101A, 101B that remove either or both of the β nuclide and the γ nuclide by adding a β,γ nuclide adsorbent to maintain the pH below a predetermined level for the radioactive liquid waste measured by the radioactive nuclide concentration measuring device 14A as having at least one of the β nuclide concentration and the γ nuclide concentration equal to or higher than a predetermined level, and an α nuclide removal device 102 that removes α nuclide from the radioactive liquid waste measured by the radioactive nuclide concentration measuring device 14A as having at least one of the β nuclide concentration and the γ nuclide concentration equal to or higher than a predetermined level, or from the radioactive liquid waste from which either or both of the β nuclide concentration and the γ nuclide concentration have been removed by the β,γ nuclide removal devices 101, 101A, 101B.

[0112] This allows for the separation and treatment of α-, β-, and γ-nuclides. In particular, by controlling the solid-liquid ratio of the β- and γ-nuclide adsorbent, the pH is maintained neutral rather than alkaline, and β- and γ-nuclides are removed before passing the water through the α-nuclide removal device 102, which makes it possible to both suppress the adsorption of α-nuclides to the β- and γ-nuclide adsorbent and improve the α-nuclide adsorption performance of the α-nuclide adsorbent, thereby achieving a reduction in radioactive waste and, further, facilitating the disposal of waste adsorbent from the perspective of radioactive waste classification.

[0113] In addition, by further comprising a radionuclide concentration measurement and determination step S7A for measuring the beta nuclide concentration and the gamma nuclide concentration of the radioactive liquid waste that has undergone the alpha nuclide removal step S7, and a beta, gamma nuclide removal step S8 for removing at least one of the beta nuclide and the gamma nuclide concentration by a beta, gamma nuclide adsorbent until the concentration becomes less than the final target concentration when at least one of the beta nuclide concentration and the gamma nuclide concentration is equal to or greater than the final target concentration in the radionuclide concentration measurement and determination step S7A, or by further comprising a radionuclide concentration measurement device 14B for measuring the beta nuclide concentration and the gamma nuclide concentration of the radioactive liquid waste from which the alpha nuclide has been removed by the alpha nuclide removal device 102, further removal of beta nuclide and gamma nuclide can be performed only when necessary, thereby improving the efficiency of the waste treatment.

[0114] Furthermore, in the radionuclide concentration measurement S5, the alpha nuclide concentration of the radioactive waste liquid is also measured, which makes it easier to estimate the amount of unintentional alpha nuclide removal in the subsequent beta, gamma nuclide removal step S6 and the amount of alpha nuclide removal in the alpha nuclide removal step S7, and allows the removal work to proceed more efficiently.

[0115] Furthermore, by determining the predetermined concentration from the relationship between the β nuclide concentration or γ nuclide concentration at the start of the α nuclide removal step S7 and the β,γ nuclide adsorption amount of the α nuclide adsorbent, and by determining the amount of the β,γ nuclide adsorbent to be added from the relationship between the solid-liquid ratio of the β,γ nuclide adsorbent and the β,γ nuclide adsorption amount and the α nuclide adsorption amount, it is possible to realize selective adsorption of β,γ nuclide by the β,γ nuclide adsorbent while minimizing the adsorption of α nuclide.

[0116] Furthermore, by determining the pH below a predetermined level based on the effect of pH on the amount of alpha nuclides adsorbed by the alpha nuclide adsorbent, it becomes possible to perform adsorption treatment according to the characteristics of the adsorbent, and therefore it becomes possible to selectively adsorb beta and gamma nuclides while minimizing the adsorption of alpha nuclides to the beta and gamma nuclide adsorbent.

[0117] Furthermore, in the β and γ nuclide removal step S6, the β and γ nuclide adsorbents are used to remove them separately, which makes it possible to easily treat the adsorbents.

[0118] On the other hand, by simultaneously performing the β,γ nuclide removal step S6 and the α nuclide removal step S7 based on the relationship between the solid-liquid ratio of the β,γ nuclide adsorbent and the β,γ nuclide adsorption amount and the α nuclide adsorption amount, the processing time can be shortened, and therefore the efficiency of the removal process can be further improved.

[0119] Furthermore, in the β,γ nuclide removal step S6, by using a type of β,γ nuclide adsorbent that keeps the increase or decrease of pH below a predetermined pH, it is possible to maintain the pH below the predetermined pH, thereby realizing the removal of β,γ nuclide while further suppressing the adsorption of α nuclide to the β,γ nuclide adsorbent.

[0120] Furthermore, by carrying out either or both of the β,γ nuclide removal step S6 and the β,γ nuclide removal step S8 by supplying a β,γ nuclide adsorbent to the radioactive liquid waste or by passing the radioactive liquid waste through a container filled with a β,γ nuclide adsorbent, more stable adsorption treatment can be carried out using a simple method.

[0121] In addition, safe concentration measurement can be achieved by measuring one or more of the radionuclide concentration measurement S5 and the radionuclide concentration measurement and determination step S7A using any of the following methods: sampling the radioactive waste liquid and measuring it with an analytical device, measuring it with a survey meter, or measuring it online.

[0122] Furthermore, by further including a separation step of performing solid-liquid separation by one or more treatments selected from a cross-flow filtration treatment, a press filter treatment, and a flocculation treatment by adding a flocculant after removing the β and γ nuclides, more appropriate disposal treatment can be carried out.

[0123] Furthermore, the alpha nuclides are plutonium, americium, curium, neptunium, and uranium; the transition metals are ruthenium, technetium, and niobium; the alkali metal is cesium; the alkaline earth metal is strontium; the rare earth is cerium; and the non-metallic elements are one or more of antimony, tellurium, halogens such as iodine, carbon, and boron, thereby providing a new radioactive waste treatment method and treatment system that has never existed before.

[0124] Second Embodiment A radioactive liquid waste treatment method and a radioactive liquid waste treatment system according to a second embodiment of the present invention will be described with reference to FIGS. 8 and 9. FIG.

[0125] The method for treating radioactive liquid waste according to the second embodiment shown in Fig. 8 has some steps overlapping with the method for treating radioactive liquid waste according to the first embodiment described above. Furthermore, the radioactive liquid waste treatment system according to the second embodiment can be configured in a similar manner to the radioactive liquid waste treatment system shown in Fig. 2, which is similar to the first embodiment described above. Therefore, in the following description, explanations of the same processes and configurations as those of the first embodiment described above will be omitted.

[0126] The radioactive liquid waste treatment method of the second embodiment differs from the first embodiment in that in addition to the adsorbent supply operation, chemical injection and pH measurement are also performed. The radioactive liquid waste treatment method of the second embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the procedure of the radioactive liquid waste treatment method of the second embodiment. Note that, before the flowchart shown in Fig. 8, treatment up to the waste liquid decomposition step S4 is performed in accordance with the flowchart shown in Fig. 1 described above.

[0127] After the organic acid or organic acid salt is decomposed in the waste liquid decomposition step S4, the concentrations of α, β, and γ nuclides are measured for the remaining aqueous solution (radioactive waste liquid) containing radionuclides (radioactive nuclide concentration measurement S5). Here, the radioactive nuclide concentration may be measured by sampling the radioactive waste liquid and measuring it with an analytical device, or it may be measured with a survey meter. The radioactive nuclide concentration may also be measured online.

[0128] Thereafter, it is determined whether the concentration of either one or more of the β and γ nuclides in the radioactive liquid waste is equal to or greater than a predetermined concentration (β,γ nuclide concentration determination step S5A), and if it is determined that both the β nuclide concentration and the γ nuclide concentration are less than the predetermined concentration, the β,γ nuclide removal step S6 is omitted and the process proceeds to the subsequent α nuclide removal step S7. Up to this point, the flow is the same as that in Figure 1.

[0129] The difference is that if it is determined in the β, γ nuclide concentration determination step S5A that either one or more of the β nuclide concentration and the γ nuclide concentration is equal to or greater than a predetermined concentration, a step (pH adjustment determination step) S5B is carried out to determine whether or not reducing the β, γ nuclide concentrations to the predetermined concentration results in a predetermined pH or greater.

[0130] If it is determined that the pH will be equal to or higher than the predetermined value when the concentration is reduced, a step (chemical injection step) S5C of injecting a chemical into the radioactive liquid waste by chemical injection device 123 (see FIG. 9) is carried out.

[0131] In this way, in the β and γ nuclide removal step S6A, the pH can be maintained below a predetermined value while the agent is being injected. Furthermore, the injection of this agent can be managed by measuring the pH.

[0132] The chemical to be injected into the radioactive waste liquid in this chemical injection process S5C can be one or more selected from inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, etc., inorganic alkalis such as sodium hydroxide, calcium hydroxide, magnesium hydroxide, etc., organic acids such as carboxylic acids, ascorbic acid, etc., organic alkalis such as ammonium-based, etc.

[0133] By carrying out the above-mentioned chemical injection, it is possible to selectively remove β and γ nuclides using a large amount of adsorbent while maintaining the pH at neutral by chemical injection, without the need to maintain the pH at neutral by controlling the solid-liquid ratio as shown in Figure 5. This is an effective method, particularly when the concentrations of β and γ nuclides in the radioactive waste liquid are so high that a small amount of adsorbent cannot remove them to the desired concentration.

[0134] Thereafter, a step (β,γ nuclide removal step) S6A of removing β,γ nuclides so that the concentrations are less than a predetermined value is carried out in the β,γ nuclide removal devices 101, 101A, and then a step (α nuclide removal step) S7 of removing α nuclides is carried out in the α nuclide removal device 102.

[0135] On the other hand, if it is determined in the pH adjustment determination step S5B that the pH will be below the predetermined pH even if the β and γ nuclides are reduced to the predetermined concentration, the β and γ nuclides are removed by the β, γ nuclide removal devices 101, 101A without injecting any chemicals so that the concentration is below the predetermined level, and then a step (α nuclide removal step) S7 of removing α nuclides by the α nuclide removal device 102 is carried out.

[0136] The steps of measuring and determining the concentration of radionuclides after the α nuclide removal step S7, the β and γ nuclide removal step S8, and the storage, processing and disposal step S9 are the same as those shown in Figure 1.

[0137] Next, details of the radioactive waste liquid treatment system of the second embodiment will be described. The radioactive waste liquid treatment system of this embodiment is the same as the radioactive waste liquid treatment system 1 of the first embodiment shown in Figure 2 except that the radioactive nuclide removal device 15 in the waste liquid treatment unit 19 is replaced with a radioactive nuclide removal device 15B, so details will be omitted.

[0138] FIG. 9 also shows details from the radionuclide concentration measuring device 14A to the radionuclide removal device 15B, as well as piping connected to the radionuclide removal device 15B and components (tanks, devices, etc.) installed nearby.

[0139] 9, the radionuclide removal device 15B is composed of a β,γ nuclide removal device 101 and an α nuclide removal device 102. A radionuclide concentration measuring device 14A is connected to a pipe 45 which is a supply pipe for radioactive liquid waste connected to the β,γ nuclide removal device 101.

[0140] The radionuclide removal device 15B is also composed of a waste liquid treatment tank that stores the radioactive waste liquid sent from the waste liquid decomposition device 13 through the pipe 45.

[0141] As a result of measuring the concentrations of radionuclides in the radioactive waste liquid, if the concentrations of β and γ nuclides are equal to or higher than a predetermined concentration (as described above in FIG. 4), the radioactive waste liquid is supplied to the β and γ nuclide removal device 101.

[0142] An agent is injected into the β,γ nuclide removal device 101 from the agent injector 123. Then, an adsorbent is supplied from the adsorbent supply device 121. Then, the radioactive liquid waste is brought into contact with the adsorbent in the β,γ nuclide removal device 101. As a result, the β,γ nuclides are adsorbed by the adsorbent in the β,γ nuclide removal device 101, and the β,γ nuclides are removed from the liquid phase of the radioactive liquid waste. At this time, the pH is controlled by the pH measuring device 124 so that it does not exceed the predetermined pH mentioned above.

[0143] In addition, when the concentrations of β and γ nuclides are less than a predetermined concentration, the pH may be adjusted by injecting a chemical using only the chemical injection device 123 in the β, γ nuclide removal device 101, and the water may be passed through the α nuclide removal device 102.

[0144] In this embodiment, the increase in pH caused by the β,γ nuclide adsorbent is suppressed by injecting an agent, and the pH is maintained neutral without becoming alkaline. However, β,γ nuclide may be removed by using a β,γ nuclide adsorbent that does not make the pH alkaline.

[0145] The other configurations and operations are substantially the same as those of the radioactive liquid waste treatment method and radioactive liquid waste treatment system of the first embodiment described above, and details thereof will be omitted.

[0146] The radioactive waste liquid treatment method and radioactive waste liquid treatment system of the second embodiment of the present invention also provides substantially the same effects as those of the radioactive waste liquid treatment method and radioactive waste liquid treatment system of the first embodiment described above.

[0147] Also, in the β,γ nuclide removal step S6A, by injecting a chemical agent to maintain a pH below a predetermined value, it becomes possible to more reliably selectively adsorb β,γ nuclides to the β,γ nuclide adsorbent without adsorbing α nuclides as much as possible in the β,γ nuclide removal before α nuclide removal. Therefore, it is possible to more reliably perform the removal while distinguishing nuclides.

[0148] Furthermore, by measuring and controlling the pH of the chemical agent injection in the β,γ nuclide removal step S6A, it is possible to avoid injecting more chemical agent than necessary.

[0149] <Others> Also, the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the above embodiments have been described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to the embodiments having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Also, the configuration of another embodiment can be added to the configuration of one embodiment. Also, for a part of the configuration of each embodiment, it is possible to delete it, or add or replace other configurations.

Explanation of Reference Numerals

[0150] 1…Radioactive waste liquid treatment system 2…High-dose resin storage tank 3…First receiving tank 4…Chemical reaction tank 5…Heating device 6…Cleaning liquid supply tank 7…Organic acid tank 8…Organic acid salt tank 9…Transfer water tank 10…Chemical cleaning section 11…Second receiving tank 12…Incineration facility 13…Waste liquid decomposition device 14A…Radioactive nuclide concentration measuring device (first measurement section) 14B…Radioactive nuclide concentration measuring device (second measurement section) 15,15A,15B…Radioactive nuclide removal device 16...Agglomeration device 19...Waste liquid treatment unit 20...Dehydration 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, 103, 103A, 104...Piping 33...Cleaning liquid supply pipe 40...Waste liquid supply pipe 101,101A,101B...β,γ nuclide removal device (β,γ nuclide removal section) 102... alpha nuclide removal device (alpha nuclide removal section) 121…Adsorbent supply device 122...Flocculant supply device 123...Drug injection device 124...pH measuring device 131...Concentrator

Claims

1. a first measuring step of measuring the beta nuclide concentration and the gamma nuclide concentration of the radioactive liquid waste; a first β,γ nuclide removal step of removing at least one of the β nuclide concentration and the γ nuclide concentration by adding a β,γ nuclide adsorbent so as to maintain a pH below a predetermined value when at least one of the β nuclide concentration and the γ nuclide concentration is at or above a predetermined value in the first measurement step; an α nuclide removal step of removing α nuclides from the radioactive liquid waste in which at least one of the β nuclide concentration and the γ nuclide concentration is less than the predetermined concentration in the first measurement step, or from the radioactive liquid waste that has been subjected to the first β and γ nuclide removal step. Methods for treating radioactive liquid waste.

2. 2. The method for treating radioactive liquid waste according to claim 1, a second measuring step of measuring the β nuclide concentrations and the γ nuclide concentrations of the radioactive liquid waste that has been subjected to the α nuclide removal step; and a second β, γ nuclide removal step of removing at least one of the β nuclide concentration and the γ nuclide concentration by the β, γ nuclide adsorbent until the concentration becomes less than the final target concentration when at least one of the β nuclide concentration and the γ nuclide concentration is equal to or greater than the final target concentration in the second measurement step. Methods for treating radioactive liquid waste.

3. 2. The method for treating radioactive liquid waste according to claim 1, In the first measurement step, the α nuclide concentration of the radioactive liquid waste is also measured. Methods for treating radioactive liquid waste.

4. 2. The method for treating radioactive liquid waste according to claim 1, The predetermined concentration is determined from the relationship between the β nuclide concentration or the γ nuclide concentration at the start of the α nuclide removal step and the β and γ nuclide adsorption amounts of the α nuclide adsorbent. Methods for treating radioactive liquid waste.

5. 2. The method for treating radioactive liquid waste according to claim 1, The amount of the β,γ nuclide adsorbent to be added is determined based on the relationship between the solid-liquid ratio of the β,γ nuclide adsorbent and the β,γ nuclide adsorption amount and the α nuclide adsorption amount. Methods for treating radioactive liquid waste.

6. 2. The method for treating radioactive liquid waste according to claim 1, The pH less than the predetermined pH is determined based on the effect of pH on the amount of alpha nuclide adsorption of the alpha nuclide adsorbent. Methods for treating radioactive liquid waste.

7. 2. The method for treating radioactive liquid waste according to claim 1, In the first β and γ nuclide removal step, β nuclide adsorbents and γ nuclide adsorbents are used to remove the β and γ nuclide species separately. Methods for treating radioactive liquid waste.

8. 2. The method for treating radioactive liquid waste according to claim 1, The first β,γ nuclide removal step and the α nuclide removal step are carried out simultaneously based on the relationship between the solid-liquid ratio of the β,γ nuclide adsorbent and the β,γ nuclide adsorption amount and the α nuclide adsorption amount. Methods for treating radioactive liquid waste.

9. 2. The method for treating radioactive liquid waste according to claim 1, In the first β and γ nuclide removal step, a chemical is injected to maintain the pH below the predetermined value. Methods for treating radioactive liquid waste.

10. 10. The method for treating radioactive liquid waste according to claim 9, The injection of the agent in the first β and γ nuclide removal step is controlled by measuring pH. Methods for treating radioactive liquid waste.

11. 2. The method for treating radioactive liquid waste according to claim 1, In the first β, γ nuclide removal step, the pH is maintained below the predetermined pH by using the β, γ nuclide adsorbent of a type that keeps the increase or decrease of pH below the predetermined pH. Methods for treating radioactive liquid waste.

12. 3. The method for treating radioactive liquid waste according to claim 2, At least one of the first β, γ nuclide removal step and the second β, γ nuclide removal step is carried out by supplying the β, γ nuclide adsorbent to the radioactive liquid waste or by passing the radioactive liquid waste through a container filled with the β, γ nuclide adsorbent. Methods for treating radioactive liquid waste.

13. 3. The method for treating radioactive liquid waste according to claim 2, At least one of the first measuring step and the second measuring step is carried out by any of the following methods: sampling the radioactive liquid waste and measuring it with an analytical device, measuring it with a survey meter, or measuring it online. Methods for treating radioactive liquid waste.

14. 2. The method for treating radioactive liquid waste according to claim 1, After removing the β nuclides and the γ nuclides, the method further includes a separation step of performing solid-liquid separation by one or more treatments selected from a cross-flow filter treatment, a press filter treatment, and a flocculation treatment by adding a flocculant. Methods for treating radioactive liquid waste.

15. 2. The method for treating radioactive liquid waste according to claim 1, The alpha nuclides are one or more of plutonium, americium, curium, neptunium, and uranium; transition metals are ruthenium, technetium, and niobium; alkali metals are cesium; alkaline earth metals are strontium; rare earths are cerium; non-metal elements are antimony, tellurium, halogens such as iodine, carbon, and boron. Methods for treating radioactive liquid waste.

16. a first measuring unit for measuring the beta nuclide concentration and the gamma nuclide concentration of the radioactive liquid waste; a β, γ nuclide removal unit that adds a β, γ nuclide adsorbent to the radioactive liquid waste in which at least one of the β nuclide concentration and the γ nuclide concentration is measured to be equal to or higher than a predetermined concentration by the first measurement unit, so as to maintain the pH below a predetermined value, thereby removing at least one of the β nuclide and the γ nuclide; an α nuclide removal unit that removes α nuclides from the radioactive liquid waste in which the first measurement unit has measured that at least one of the β nuclide concentration and the γ nuclide concentration is less than the predetermined concentration, or from the radioactive liquid waste from which at least one of the β nuclide and the γ nuclide has been removed in the β, γ nuclide removal unit. Radioactive waste treatment system.

17. 17. The radioactive liquid waste treatment system according to claim 16, a second measuring unit for measuring the beta nuclide concentration and the gamma nuclide concentration of the radioactive liquid waste from which the alpha nuclide has been removed by the alpha nuclide removal unit; Radioactive waste treatment system.

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