WO2021152975A1 - Radioactive waste liquid treatment system and method for treating radioactive waste liquid - Google Patents

Radioactive waste liquid treatment system and method for treating radioactive waste liquid Download PDF

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WO2021152975A1
WO2021152975A1 PCT/JP2020/043404 JP2020043404W WO2021152975A1 WO 2021152975 A1 WO2021152975 A1 WO 2021152975A1 JP 2020043404 W JP2020043404 W JP 2020043404W WO 2021152975 A1 WO2021152975 A1 WO 2021152975A1
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nuclide
radioactive
waste
liquid
organic acid
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PCT/JP2020/043404
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French (fr)
Japanese (ja)
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伊藤　剛
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日立Ｇｅニュークリア・エナジー株式会社
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G21F9/12—Processing by absorption; by adsorption; by ion-exchange
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the present invention relates to a radioactive liquid waste treatment system and a method for treating radioactive liquid waste, and in particular, a radioactive liquid waste treatment system and a radioactive liquid waste liquid suitable for treatment of radioactive liquid waste generated by cleaning waste resin generated from a nuclear plant. Regarding the processing method.
  • Cellulose-based filtration aids generated from nuclear reactor coolant purification systems, fuel pool coolant purification systems, etc., filter sludge containing ion exchange resins, and other radioactive organic waste are stored in storage tanks for a long period of time. Has been done. These radioactive organic wastes are constantly generated during the operation of nuclear power plants. In order to secure a storage space for radioactive organic waste, volume reduction treatment technology that efficiently reduces the volume of radioactive organic waste currently being stored is required.
  • the ion exchange resin is based on styrene / divinylbenzene and is chemically stable, so it can be safely stored for a long period of time.
  • the decomposition treatment is difficult due to its stability, and when the volume of the ion exchange resin is reduced, a thermal decomposition treatment at a high temperature is usually required.
  • the ion exchange resin which is a waste resin
  • the organic acid salt aqueous solution to the ion exchange resin is dissolved in the organic acid salt aqueous solution to the ion exchange resin.
  • each of the organic acid contained in the organic acid aqueous solution used for dissolving the clad (iron oxide, etc.) and the organic acid salt contained in the organic acid aqueous solution used for elution of the radioactive nuclei is prepared by ozone or the like.
  • the waste liquid containing the radioactive nuclei which is decomposed and remains after the decomposition of the organic acid and the organic acid salt, is made into a dry powder, and the obtained powder containing the radioactive nuclei is solidified with a solidifying agent (cement or the like).
  • the contaminated water treatment method described in JP-A-2019-70581 is a radionuclide adsorption removal method for adsorbing and removing radionuclides contained in contaminated water after a pH buffering step of making the contaminated water weakly alkaline and a pH buffering step. Including the step, before the radionuclide adsorption step, the water quality of the contaminated water is controlled so that the sodium contained in the contaminated water becomes excessive with respect to calcium.
  • the nuclear fuel reprocessing method described in JP-A-2002-257980 includes a fluorination treatment step and a solvent extraction step.
  • fluorination treatment step fluorine is brought into contact with the nuclear fuel material contained in the spent fuel assembly taken out from the nuclear reactor, and uranium contained in the nuclear fuel material is reacted with fluorine to convert it into volatile UF 6.
  • uranium contained in the nuclear fuel material is reacted with fluorine to convert it into volatile UF 6.
  • the remaining uranium and plutonium are recovered in the solvent extraction step.
  • the solvent extraction step is a dissolution step of dissolving the remaining nuclear fuel substance by the solution containing nitric acid, and the extract containing tributylphosphate (TBP) is brought into contact with the solution containing the dissolved nuclear fuel substance and contained in the solution.
  • TBP tributylphosphate
  • a large number of fuel assemblies are loaded in the core of the nuclear reactor of a nuclear power plant.
  • Each fuel assembly has a plurality of fuel rods filled with nuclear fuel material in a cladding tube.
  • a coolant specifically cooling water
  • the cooling water is heated by the heat generated by the nuclear fission of the nuclear fuel material in the fuel rods in the fuel assembly.
  • a part of the cooling water flowing in the reactor is supplied to a purification device provided in the reactor coolant purification system, and the radionuclides contained in the cooling water are removed by the purification device.
  • the cooling water is purified by a purification device provided in the purification system piping of the reactor cooling material purification system that supplies the cooling water in the reactor (Japanese Patent Laid-Open No. 2018-48831). reference). Inside the purification device, there is an ion exchange resin that purifies the cooling water.
  • a pressurized water reactor is also provided with a reactor coolant purification system that purifies the cooling water in the reactor, and this reactor coolant purification system is provided with a purification device in which an ion exchange resin is present.
  • Japanese Patent Application Laid-Open No. 2014-66647 describes that a liquid containing a radioactive substance is brought into contact with the adsorbent to adsorb the radioactive substance to the adsorbent, and the liquid containing the adsorbent is cross-flow filtered to obtain the radioactive substance.
  • a method for separating the adsorbent that has adsorbed the above and the liquid after the adsorption treatment is described.
  • Japanese Unexamined Patent Publication No. 2015-64334 Japanese Unexamined Patent Publication No. 2019-70581 JP-A-2002-257980 Japanese Unexamined Patent Publication No. 2018-48831 Japanese Unexamined Patent Publication No. 2014-66647
  • the nuclear fuel materials in the fuel rods that is, uranium (U), americium (Am), plutonium (Am), plutonium ( Actinides, which are ⁇ -nuclear species such as Pu), plutonium (Np) and curium (Cm), leak into the cooling water.
  • the cooling water containing those ⁇ -nuclide is guided to the purification device of the reactor coolant purification system, and each ⁇ -nuclide is removed by the ion exchange resin in the purification device.
  • the half-life of ⁇ -nuclide is the super half-life.
  • an organic acid aqueous solution and an organic acid salt aqueous solution are sequentially brought into contact with an ion exchange resin, which is a waste resin adsorbing ⁇ nuclei, to form an ion exchange resin.
  • an ion exchange resin which is a waste resin adsorbing ⁇ nuclei
  • the contained clad is dissolved and the radioactive nuclei adsorbed on the ion exchange resin are eluted.
  • the ⁇ -nuclide removed by the ion exchange resin is also eluted and transferred into each of the organic acid aqueous solution and the organic acid salt aqueous solution.
  • a liquid containing a radioactive substance is brought into contact with the adsorbent.
  • the radioactive substance may be adsorbed. Radioactive substances may remain in the liquid after the adsorbent is separated due to insufficient adsorption.
  • An object of the present invention is to provide a radioactive liquid waste treatment system and a method for treating radioactive liquid waste, which can make an ⁇ -nuclide removing device for removing ⁇ -nuclide contained in radioactive liquid waste compact.
  • the feature of the present invention that achieves the above-mentioned object is that a water quality adjusting device for adjusting the water quality of the radioactive liquid waste containing ⁇ -nuclide and a radioactive waste liquid having the water quality adjusted downstream of the water quality adjusting device are supplied. It is equipped with a filter that is used.
  • a water quality adjusting device for adjusting the water quality of the radioactive effluent containing ⁇ -nuclide and a filter arranged downstream of the water quality adjusting device to supply the radioactive effluent having the adjusted water quality.
  • a radioactive liquid containing ⁇ -nuclide ions flowing out of the filter is supplied and an ⁇ -nuclide adsorbent exists inside, and the ⁇ -nuclide adsorbent adsorbs ⁇ -nuclide ions to adsorb ⁇ -nuclide ions to the radioactive waste liquid. It is desirable to have an ⁇ -nuclide removal device for removing from.
  • an ⁇ -nuclide adsorbent injection device that injects an ⁇ -nuclide adsorbent into a radioactive liquid containing ⁇ -nuclide ions flowing out of the filter, and an ⁇ -nuclide adsorbing device that is supplied with a radioactive liquid containing ⁇ -nuclide ions and exists inside. It is desirable to provide an ⁇ -nuclide removing device that adsorbs ⁇ -nuclide ions by the material and removes ⁇ -nuclide ions from the radioactive liquid waste liquid.
  • the above-mentioned purpose can also be achieved by injecting a pH adjuster into a radioactive liquid containing ⁇ -nuclide to generate a colloid of ⁇ -nuclide in the radioactive liquid waste, and removing the produced colloid of ⁇ -nuclide with a filter.
  • the ⁇ -nuclide removing device for removing the ⁇ -nuclide contained in the radioactive liquid waste compact.
  • FIG. 1 It is a flowchart which shows the procedure of the radioactive waste liquid treatment method of Example 1 applied to the treatment of the radioactive organic waste generated in the boiling water type nuclear power plant which is a preferable example of this invention.
  • FIG. It is a block diagram of an example of the radioactive waste liquid treatment system which carries out the radioactive liquid waste treatment method of Example 1.
  • FIG. It is a detailed block diagram of the waste liquid decomposition apparatus shown in FIG. It is a detailed block diagram of the water quality adjustment device and the ⁇ -nuclide removal device shown in FIG. It is a detailed block diagram of another example of the water quality adjustment apparatus shown in FIG.
  • a pH adjuster is injected into a radioactive liquid solution containing ⁇ nuclides generated by desorption of radio nuclides containing ⁇ nuclides adsorbed on a cation exchange resin which is a radioactive organic waste, and contains ⁇ nuclides and a pH adjuster.
  • Japanese Patent Application No. 2018-210315 is a method for treating radioactive effluent by supplying radioactive effluent to an ⁇ -nuclide removing device having an ⁇ -nuclide adsorbent and removing ⁇ -nuclide contained in the radioactive effluent with the ⁇ -nuclide adsorbent in the ⁇ -nuclide removing device. Proposed by issue (Filing date: November 8, 2018).
  • the inventor examined in detail the method for treating radioactive liquid waste proposed in Japanese Patent Application No. 2018-210315. As a result, the inventor needs a large amount of ⁇ -nuclide adsorbent in order to remove ⁇ -nuclide contained in the radioactive liquid waste in the method for treating the radioactive liquid waste, and there is a problem that the ⁇ -nuclide removing device becomes large in size. I realized that.
  • the ⁇ -nuclide adsorbent for example, ferrite (Fe 3 O 4 ), activated carbon, or the like can be used. Not limited to ferrite and activated carbon, any adsorbent capable of adsorbing ⁇ -nuclide can be used as an ⁇ -nuclide adsorbent.
  • the inventors conducted various studies on how to reduce the amount of ⁇ -nuclide adsorbent in the ⁇ -nuclide removing device in order to make the ⁇ -nuclide removing device compact.
  • ferrite Fe 3 O 4
  • three ferrite layers filled with ferrite particles are formed in the ⁇ -nuclide removing device.
  • the particle size of the ferrite particles becomes smaller from the upstream ferrite layer to the downstream ferrite layer.
  • the ⁇ -nuclide removing device used in Japanese Patent Application No. 2018-210315 has three ferrite layers inside and uses a large amount of ferrite.
  • the ⁇ -nuclides uranium, plutonium and neptinium contained in the radioactive liquid waste become colloids and the particle size becomes large when the pH of the radioactive liquid waste is set to less than 8. Therefore, if the inventor removes ⁇ -nuclides (for example, uranium, plutonium, and neptinium) that have become colloidal and have a large particle size upstream of the ⁇ -nuclide removing device, the ⁇ -nuclide supplied to the ⁇ -nuclide removing device.
  • ⁇ -nuclides for example, uranium, plutonium, and neptinium
  • the amount of ⁇ -nuclide adsorbent in the ⁇ -nuclide removal device could be reduced by reducing the amount of ⁇ -nuclide.
  • the colloidal ⁇ -nuclide can be removed, and the amount of ⁇ -nuclide supplied to the ⁇ -nuclide removing device can be reduced.
  • the inventor examined the effect of the removal of ⁇ -nuclide contained in radioactive liquid waste by the water quality of the radioactive liquid waste.
  • alkali for example, nalium hydroxide
  • Np plural carbonate
  • At least one of an acid, an oxidizing agent for adjusting the water quality (hereinafter referred to as an oxidizing agent for adjusting the water quality) and a reducing agent may be injected together with the alkali.
  • any one of sodium hydroxide, potassium hydroxide, calcium hydroxide and sodium carbonate is used.
  • the acid for example, dilute nitric acid, dilute sulfuric acid, dilute hydrochloric acid and the like are used.
  • the oxidizing agent for water quality adjustment either an organic acid or an organic acid salt is used.
  • the reducing agent for example, any one of hydrazine derivatives such as hydrazine, formhydrazine, hydrazinecarbamide and carbhydrazide, hydroxylamine, ascorbic acid and sulfites is used. In particular, ascorbic acid and sulfites are called redox potential regulators, although they are reducing agents.
  • the redox potential modifier is weakly acidic.
  • the reducing agents other than the oxidation-reduction potential adjusting agent are weakly alkaline and are referred to as alkaline reducing agents for convenience.
  • the expression "reducing agent" includes a redox potential modifier and an alkaline reducing agent.
  • acids, water quality adjusting oxidizing agents and oxidation-reduction potential adjusting agents have the effect of acidifying the radioactive waste liquid
  • alkaline and alkaline reducing agents have the effect of making the radioactive waste liquid alkaline.
  • an oxidation-reduction potential modifier In order to adjust the redox potential of the radioactive liquid waste, it is desirable to use an oxidation-reduction potential modifier.
  • the water quality of the radioactive effluent containing ⁇ -nuclide was adjusted as described above, the radioactive effluent with the adjusted water quality was supplied to the filter, and the proportion of ⁇ -nuclide remaining in the radioactive effluent that passed through the filter was investigated.
  • the ratio of ⁇ -nuclide contained in the radioactive liquid waste discharged from the filter to the amount of ⁇ -nuclide contained in the radioactive liquid waste before flowing into the filter is called the residual ratio of ⁇ -nuclide.
  • U, Pu and Np become colloids having a large particle size by adjusting the water quality of the radioactive liquid waste, and can be removed by a filter.
  • FIG. 6 shows the effect of pH on U as a representative of U, Pu and Np. Based on FIG. 6, the residual rate of U in the radioactive liquid discharged from the filter was found to be the largest in alkaline (pH 9) and smaller in neutral (pH 7) and acidic (pH 4). When the pH of the radioactive liquid waste is set to 7 or less, the removal rate of U by the filter becomes high, and the residual rate of U in the radioactive liquid discharged from the filter becomes small.
  • the inventor also investigated the effect of the pH of the radioactive liquid waste on the removal of U, Pu and Np by the filter between pH 7 and pH 9.
  • the removal rates of U, Pu and Np by the filter were high.
  • the pH of the radioactive liquid waste becomes 8 or more, each of U, Pu and Np becomes an ion, so that each of U, Pu and Np cannot be removed by a filter.
  • the pH of the radioactive liquid waste is less than 4
  • the colloid of the ⁇ -nuclide generated in the radioactive liquid waste dissolves and cannot be removed by the filter. Therefore, it is desirable that the pH of the radioactive liquid waste be in the range of 4 or more and less than 8 (4 ⁇ pH ⁇ 8).
  • the oxidation-reduction potential of the radioactive liquid is changed to "-0.5V", "0V” and "0.2V” as shown in FIG. 7 while the pH of the radioactive liquid is set to 6.
  • the ⁇ -nuclide contained in the radioactive effluent can be more efficiently removed from the radioactive effluent, and the residual rate of the ⁇ -nuclide in the radioactive effluent discharged from the filter becomes smaller as the oxidation-reduction potential becomes lower. Further, as shown in FIG. 8, if the dissolved carbonic acid concentration of the radioactive liquid waste is reduced, the residual rate of ⁇ -nuclide in the radioactive liquid waste discharged from the filter can be further reduced.
  • a dissolved carbonic acid for example, sodium sulfite, N 2 (nitrogen) gas, and Ar gas
  • any of a dissolved carbonic acid for example, sodium sulfite, N 2 (nitrogen) gas, and Ar gas
  • Pu and Np contained in the radioactive effluent for example, soluble ⁇ -nuclides such as americium and curium
  • filters are used.
  • the ⁇ -nuclide adsorbent After passing the radioactive effluent containing radionuclides, whose water quality was adjusted in the water quality adjustment step, through the filter, the ⁇ -nuclide adsorbent is injected into the radioactive effluent to dissolve amerythium, curium, etc. in the ⁇ -nuclide removal device.
  • the ion removal step S7 of the sex ⁇ -nuclide is carried out.
  • the ⁇ -nuclide adsorbent any one of ferrite (Fe 3 O 4 ), chelate resin, activated carbon, oxine-impregnated activated carbon, zeolite, titanic acid and ferrocyanide is used.
  • FIG. 9 shows the residual ratio of ⁇ -nuclide in the radioactive liquid waste discharged from the filter for each of a certain method “A” and method “B” in the two methods for removing ⁇ -nuclide contained in the radioactive liquid waste.
  • the method "A" shown in FIG. 9 is eluted with an aqueous solution of ammonia oxalate, which is an aqueous organic acid salt solution containing an ⁇ -nucleus species adsorbed on a cation exchange resin, for example, uranium and americium, and is contained in the aqueous solution of ammonia oxalate.
  • ammonia oxalate is decomposed with ozone and the eluted water (concentration is on the order of ppb) is not removed (in an untreated state), and water containing americium is discharged as it is. Therefore, in the method "A", the uranium residual rate (residual rate of ⁇ -nuclide) of the discharged water is 100%.
  • the method "B" shown in FIG. 9 decomposes ammonia oxalate in an aqueous solution of ammonia oxalate containing eluted uranium and americium with ozone, and adjusts the water quality to water containing uranium and americium produced by this decomposition.
  • Hydrazin which is an alkaline reducing agent, is injected to adjust the pH of the water to 5 in the range of 4 or more and less than 8, and ferrite (Fe 3 O 4 ) is added to water containing uranium or americium having a pH of 5. This is the case of injection.
  • the concentration of uranium and americium in the water before supplying ferrite in the method “B” is the same as the concentration of americium in the water in the method “A”.
  • the residual rate of americium is about 6.7%, and the residual rate is about 1/15 of that of the method "A”.
  • a pH adjuster is injected into water containing ⁇ -nuclide after decomposition of an organic acid salt to adjust the pH of the water to a range of 4 or more and less than 8, and ferrite is added to the pH-adjusted water containing ⁇ -nuclide. It was found that by supplying the water, the ⁇ -nuclide contained in the water can be significantly removed.
  • the pH adjusting agent an acid, an oxidizing agent for adjusting water quality, a reducing agent and an alkali are used.
  • the particles of the ⁇ -nuclide absorber can be made finer, and the specific surface area of the ⁇ -nuclide absorber can be increased. Further, by injecting the ⁇ -nuclide adsorbent into the radioactive waste liquid, it becomes possible to control the time during which the ⁇ -nuclide adsorbent is immersed in the radioactive waste liquid. Thereby, it is possible to control so that the ⁇ -nuclide adsorbent is immersed in the radioactive liquid waste until the time when the desired amount of ⁇ -nuclide is adsorbed.
  • the ⁇ -nuclide adsorbent is injected into the radioactive liquid waste liquid. Improves the removal performance of ⁇ -nuclide and makes it possible to reduce the amount of radioactive waste containing ⁇ -nuclide.
  • the ⁇ -nuclide adsorbent especially the above-mentioned ferrite, has the ability to adsorb ⁇ -nuclide (adsorption performance), which changes depending on the pH of the radioactive liquid waste and the oxidation-reduction potential (Eh). Therefore, the pH of the radioactive effluent is set to a pH within the range of 4 or more and less than 8 by injecting a pH adjusting agent, and the redox potential of the radioactive effluent is set to a specific redox by injecting an oxidation-reduction potential adjusting agent. If it is within the range of the potential, the adsorption performance of the ⁇ -nuclide adsorbent can be sufficiently exhibited.
  • the pH and oxidation-reduction potential of the radioactive liquid are adjusted.
  • the pH and oxidation-reduction potential of the radioactive liquid waste can be set within the range of a specific pH and oxidation-reduction potential at which the adsorption performance of the ⁇ -nuclide adsorbent can be sufficiently exhibited.
  • the above-mentioned water quality adjustment of the radioactive effluent is carried out to generate a colloid having a large particle size for the ⁇ nuclide, and the radioactive effluent containing this colloid is passed through the filter, and the ⁇ nuclide, particularly U, Pu and
  • An embodiment of the present invention created based on a method for treating radioactive effluent, which reduces ⁇ -nuclide contained in the radioactive effluent discharged from the filter by removing the above-mentioned colloid of Np, will be described below.
  • Example 1 The method for treating the radioactive liquid waste of Example 1, which is a preferred embodiment of the present invention, will be described with reference to FIGS. 1 to 4.
  • This embodiment is a method for treating radioactive liquid waste that treats radioactive organic waste generated in a boiling water reactor.
  • FIG. 1 is a flowchart showing a procedure of a method for treating radioactive liquid waste according to Example 1.
  • Fuel rods contained in a nuclear plant for example, a fuel assembly loaded in the core of a reactor pressure vessel of a boiling water nuclear plant that is experiencing operation, or a spent fuel assembly stored in a fuel storage pool.
  • the nuclear fuel material including ⁇ nuclei such as uranium, plutonium, neptunium and curium
  • the nuclear fuel material in the fuel rod will be removed from the cooling water in the reactor pressure vessel or the fuel storage pool. Leaks into the cooling water inside. Then, the ⁇ -nuclide leaked into the cooling water in the reactor pressure vessel is removed by the ion exchange resin in the purification device of the reactor cooling material purification system. Further, the ⁇ -nuclide leaked into the cooling water in the fuel storage pool is removed by the ion exchange resin in the purification device of the fuel pool cooling material purification system.
  • Filter sludge (radioactive organic waste) containing cellulosic filtration aids, ion exchange resins, etc. generated from the reactor coolant purification system and fuel pool coolant purification system of boiling water reactors is a high-dose resin. It is stored in a storage tank for a long period of time. The radioactive organic waste stored in the high-dose resin storage tank is taken out from the high-dose resin storage tank after a predetermined storage period has elapsed.
  • the first cleaning step (clad dissolution step) S1 is carried out on the radioactive organic waste containing the cation exchange resin taken out from the high-dose resin storage tank.
  • an aqueous solution of a reducing organic acid for example, an aqueous solution of oxalic acid
  • a reducing organic acid for example, an aqueous solution of oxalic acid
  • Clads such as oxides are dissolved.
  • Radionuclides such as cobalt-60 contained in the clad are transferred into the organic acid aqueous solution by dissolving the clad.
  • the reason why the organic acid is used in the first cleaning step S1 is that the main constituent elements of the organic acid are carbon, hydrogen, oxygen and nitrogen, so that the organic acid aqueous solution which is the cleaning waste liquid generated in the first cleaning step S1 is used, for example. This is because no non-volatile residue is generated in the waste liquid when the oxidation treatment (the waste liquid decomposition step S4 described later) is performed using ozone.
  • the organic acid for example, formic acid, oxalic acid, acetic acid or citric acid is preferably used.
  • the waste liquid decomposition step S4 is carried out on the organic acid aqueous solution (clad solution) which is the cleaning waste solution containing the clad dissolving component generated in the first cleaning step S1.
  • a waste liquid decomposition step decomposition step of either organic acid or organic acid salt
  • an oxidizing agent for decomposition such as hydrogen peroxide or ozone (hereinafter referred to as a decomposition oxidizing agent) is exposed to the organic acid aqueous solution.
  • the organic acid is decomposed by the oxidizing action of the oxidizing agent for decomposition.
  • the first cleaning step S1 is performed, and the second cleaning step (radionuclide elution step) S2 is carried out on the radioactive organic waste in which the clad is dissolved.
  • the organic acid salt aqueous solution is brought into contact with the radioactive organic waste in which the clad is dissolved, and the radioactive acid such as ⁇ nuclei adsorbed on the radioactive organic waste by the organic acid salt contained in the aqueous solution is radioactive.
  • the nuclei are eluted.
  • the organic acid salt used in the second cleaning step S2 is an organic acid salt that dissociates in an aqueous solution to generate cations that are more easily adsorbed on the cation exchange resin than hydrogen ions. That is, the organic acid salt has carbon, hydrogen, oxygen and nitrogen as its main constituent elements, and after the completion of the second cleaning step S2, the organic acid salt aqueous solution which is a cleaning waste liquid is oxidized using, for example, ozone. It is desirable that no non-volatile residue is generated in the waste liquid when the (waste liquid decomposition step S4) is performed.
  • organic acid salt for example, it is desirable to use an ammonium salt, barium salt or cesium salt of formic acid, oxalic acid, acetic acid or citric acid.
  • hydrazine formate may be used as an organic acid salt.
  • the ammonium salt is decomposed into nitrogen gas and water by the oxidation treatment, the amount of radioactive waste generated can be reduced as compared with the barium salt and the cesium salt.
  • Formic acid, oxalic acid, acetic acid or citric acid ammonium salts, barium salts or cesium salts dissociate in aqueous solution to NH 4+ , Ba 2+ or Cs + .
  • NH 4+ , Ba 2+ or Cs + are cations that are more easily adsorbed on the cation exchange resin than hydrogen ions.
  • the waste liquid decomposition step S4 is carried out on the organic acid salt aqueous solution which is the cleaning waste liquid containing radioactive nuclides such as the eluted ⁇ nuclides generated in the second cleaning step S2.
  • a decomposition oxidizing agent such as ozone or hydrogen peroxide is exposed to the organic acid salt aqueous solution, and the organic acid salt is decomposed by the decomposition oxidizing agent. Is disassembled.
  • the colloid generation step S5 of the ⁇ nuclide is carried out in the residual aqueous solution (radioactive waste liquid) containing the radionuclide remaining after the organic acid or the organic acid salt is decomposed in the waste liquid decomposition step S4.
  • the water quality of the radioactive effluent is adjusted by injecting at least one of an acid, an oxidizing agent for adjusting the water quality, a reducing agent, and an alkali.
  • the pH is adjusted to the range of 4 or more and less than 8, and some chemical forms of ⁇ -nuclide contained in the radioactive liquid liquid are made colloid.
  • the remaining nuclides of ⁇ -nuclide remain ions even if the water quality of the radioactive liquid waste is adjusted.
  • U, PU and Np contained in the ⁇ nuclide become colloids having a large particle size, and americium and curium contained in the ⁇ nuclide remain ions in the radioactive liquid waste liquid.
  • the pH adjuster for example, the reducing agent, which was injected into the radioactive liquid waste before the ⁇ -nuclide adsorbent was injected, is discharged in a state of being contained in the radioactive liquid waste. Then, the colloids having large particle sizes of U, PU, and Np, which are a part of the ⁇ -nuclide, produced in the radioactive liquid waste by adjusting the water quality of the radioactive liquid waste are subjected to a filter in the colloid removal step S6 of the ⁇ -nuclide. Will be removed.
  • the small colloids of U, PU and Np, the ions of U, PU and Np, and the remaining americium and curium of the ⁇ nuclide that remain in the radioactive liquid liquid pass through the filter and are downstream of the filter. It is adsorbed and removed by the ⁇ -nuclide adsorbent in the ⁇ -nuclide removing device arranged in ( ⁇ -nuclide ion removing step S7). The ⁇ -nuclide adsorbent is injected into the radioactive liquid waste that has passed through the filter and guided into the ⁇ -nuclide removal device.
  • the ⁇ -nuclide adsorbent is separated from the radioactive liquid discharged from the ⁇ -nuclide removal device. Then, it is determined whether the pH adjuster injected into the radioactive liquid waste in the colloid production step S5 of the ⁇ -nuclide can be decomposed (pH adjuster determination step S9).
  • the pH adjuster is, for example, a decomposable pH adjuster
  • the determination is "YES”
  • the radioactive liquid waste containing the pH adjuster discharged from the ⁇ nuclide remover is a catalyst (for example, a noble metal). Is supplied to a decomposition device having an internal structure.
  • the pH adjuster is decomposed in the decomposition apparatus by the action of the catalyst and the decomposition oxidizing agent (for example, hydrogen peroxide) supplied to the decomposition apparatus (decomposition step S10 of the decomposable pH adjuster).
  • the radioactive waste liquid containing no pH adjuster (including the radioactive waste liquid containing the injected acid) is subjected to a concentration treatment or a dry powder treatment.
  • the container filling or solidification step S12 the concentrated waste liquid generated by the concentration treatment or the powder of the radioactive waste generated by the dry powdering treatment is filled in the container and stored, or the container is filled with a solid agent such as cement. Solidified within.
  • the radioactive liquid waste treatment system 1 includes a chemical cleaning unit 10 for treating radioactive organic waste and a waste liquid treatment unit 19 for treating the cleaning waste liquid (radioactive waste liquid) discharged from the chemical cleaning unit 10.
  • a first cleaning step S1 for dissolving the clad and a second cleaning step S2 for eluting the radionuclide from the radioactive organic waste are performed.
  • the chemical cleaning unit 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. Further, the high-dose resin storage tank 2 is arranged in front of the chemical cleaning unit 10, and the second receiving tank 11 and the incinerator (or cement solidification equipment) 12 are arranged downstream of the chemical cleaning unit 10.
  • the organic waste supply pipe 23 provided with the transfer pump 22 connects the high-dose resin storage tank 2 and the first receiving tank 3.
  • the chemical reaction tank 4 is connected to the first receiving tank 3 by an organic waste transfer pipe 25 provided with a transfer pump 24.
  • the heating device 5 is arranged around the chemical reaction tank 4.
  • the cleaning liquid supply tank 6 is connected to the chemical reaction tank 4 by a cleaning liquid supply pipe 33 provided with a transfer pump 32.
  • the return pipe 36 which is connected to the bottom of the chemical reaction tank 4 and is provided with the transfer pump 34 and the valve 35, is connected to the cleaning liquid supply tank 6.
  • a pipe 29 connected to an organic acid tank 7 filled with an organic acid aqueous solution, for example, an oxalic acid aqueous solution and provided with a valve 26 is connected to a cleaning liquid supply tank 6.
  • the oxalic acid aqueous solution filled in the organic acid tank 7 is a saturated aqueous solution, and the oxalic acid concentration of the oxalic acid aqueous solution is, for example, 0.8 mol / L.
  • a pipe 30 connected to an organic acid salt tank 8 filled with an aqueous organic acid salt solution, for example, an aqueous solution of hydrazine formate and provided with a valve 27 is connected to the pipe 29 downstream of the valve 26.
  • the pipe 31 provided with the valve 28 connected to the transfer water tank 9 filled with water to be the transfer water is connected to the pipe 30 downstream of the valve 27.
  • the pipe 38 provided with the valve 37 and connected to the bottom of the chemical reaction tank 4 is connected to the second receiving tank 11.
  • the pipe connected to the second receiving tank 11 is connected to the incinerator (or cement solidification facility) 12.
  • the waste liquid treatment unit 19 includes a waste liquid decomposition device 13, a water quality adjusting device 54, an ⁇ nuclide removing device 14, an ⁇ nuclide adsorbent injection device 69, an ⁇ nuclide adsorbent separating device 72, a decomposition device 107, an oxidizing agent supply device 108, and the like. It has a treated water recovery tank 18.
  • the pipe 40 which is connected to the return pipe 36 between the transfer pump 34 and the valve 35 and is provided with the valve 39, is connected to the waste liquid decomposition device 13.
  • the pipe 45 provided with the transfer pump 43 and the valve 44 is connected to the waste liquid decomposition device 13, the water quality adjusting device 54, and the ⁇ nuclide removing device 14.
  • the pipe 45 is a “radioactive waste liquid supply pipe that guides radioactive waste liquid containing ⁇ -nuclide”.
  • the waste liquid decomposition device 13 is composed of a waste liquid storage tank, and an ozone injection pipe 51 is installed at the bottom of the waste liquid storage tank. A large number of injection holes are formed in the ozone injection pipe 51.
  • the ozone injection pipe 51 is connected to the ozone supply device 50 by the ozone supply pipe 52.
  • the pipe 40 is connected to the waste liquid storage tank of the waste liquid decomposition device 13. One end of the pipe 45 is inserted into the waste liquid storage tank. Further, a gas exhaust pipe 53 is connected to the waste liquid storage tank of the waste liquid decomposition device 13.
  • the pipe 46 is connected to the ⁇ nuclide removing device 14, the ⁇ nuclide adsorbent separating device 72, the decomposition device 107, and the treated water recovery tank 18.
  • the ⁇ -nuclide adsorbent injection device 69 is contacted with the ⁇ -nuclide removal device 14.
  • the water quality adjusting device 54 is provided in a pipe 45 connected to the ⁇ nuclide removing device 14, and has a pH adjusting agent injection device 55 and a pH meter 49A.
  • the pH adjuster injection device 55 includes a reducing agent injection device 17, an acid injection device 56, an oxidant injection device 75, and an alkali injection device 79.
  • the reducing agent injection device 17 has an injection pipe 42 provided with a reducing agent supply device 85, a redox potential adjusting agent supply device 89, a mixing tank 17A, and a valve 41.
  • the reducing agent supply device 85 has a reducing agent tank 86 and an injection pipe 88 provided with a valve 87.
  • the injection pipe 88 is connected to the reducing agent tank 86 and is connected to the pipe 88 connected to the mixing tank 17A.
  • the reducing agent tank 86 is filled with an alkaline reducing agent aqueous solution, for example, a hydrazine aqueous solution.
  • the redox potential adjusting agent supply device 89 has an oxidation-reduction potential adjusting agent tank 90 and an injection pipe 92 provided with a valve 91.
  • the injection pipe 92 is connected to the redox potential adjusting agent tank 90 and further connected to the pipe 93.
  • the redox potential adjusting agent tank 90 is filled with an aqueous solution of the redox potential adjusting agent, for example, an aqueous solution of ascorbic acid.
  • the injection pipe 42 connected to the mixing tank 17A is connected to the pipe 45 between the transfer pump 41 (see FIG. 2) and the ⁇ -nuclide removing device 15 described later.
  • the acid injection device 56 has an acid tank 57 and an injection pipe 59A provided with a valve 58.
  • the injection pipe 59A is connected to the acid tank 57 and further connected to the injection pipe 42 downstream of the valve 41.
  • the acid tank 57 is filled with an acid aqueous solution, for example, a dilute nitric acid aqueous solution.
  • the oxidant injection device 75 has an oxidant tank 76 and an injection pipe 78 provided with a valve 77.
  • the injection pipe 78 connected to the oxidant tank 76 is connected to the injection pipe 42 downstream of the valve 41.
  • the oxidant tank 76 is filled with an aqueous oxidant solution for adjusting water quality, for example, an oxalic acid aqueous solution.
  • the alkali injection device 79 has an alkali tank 80 and an injection pipe 82 provided with a valve 81.
  • the injection pipe 82 is connected to the alkaline tank 80 and further connected to the injection pipe 78 downstream of the valve 77.
  • the alkaline tank 80 is filled with an alkaline aqueous solution, for example, a sodium hydroxide aqueous solution.
  • the pH meter 49A is attached to the pipe 45 at a portion downstream from the connection point of the injection pipe 42 and the pipe 45 connected to the reducing agent injection device 17.
  • the ⁇ -nuclide concentration meter 65 is attached to the pipe 45 between the portion where the pH meter 49A is attached to the pipe 45 and the connection point between the pipe 45 and the pipe 67.
  • the pipe 67 is connected to the return pipe 36 of the chemical cleaning unit 10 between the transfer pump 34 and the valve 35.
  • Hydrazin existing in the reducing agent tank 86 which is an alkali reducing agent from the reducing agent injection device 17 which is an alkali reducing agent from the reducing agent injection device 17
  • sodium hydroxide which is an alkali from the alkali injection device 79
  • ascorbic acid oxidation-reduction potential adjuster
  • the radioactive liquid liquid flowing in the pipe 45 can be adjusted to be alkaline, and the radioactive liquid liquid can be adjusted to a reducing atmosphere. It becomes possible to do.
  • At least one substance is dilute nitric acid which is an acid from the acid injection device 56, oxalic acid which is an oxidant for water quality adjustment from the oxidant injection device 75, and ascorbic acid which is an oxidation-reduction potential adjuster from the reducing agent injection device 54.
  • the filter 66 is installed in the pipe 45 between the water quality adjusting device 54 and the ⁇ nuclide removing device 14, specifically, between the position where the ⁇ nuclide concentration meter 65 is attached to the pipe 45 and the ⁇ nuclide removing device 14. (See FIG. 4).
  • the filter 66 has, for example, a membrane having a pore size on the order of ⁇ m or less.
  • the filter 66 is installed in the pipe between the attachment position of the ⁇ -nuclide concentration meter 65 to the pipe 45 and the connection point between the pipe 67 and the pipe 45.
  • the ⁇ -nuclide removing device 14 has a casing arranged downstream of the filter 66, connected to the pipe 45, and accommodating the radioactive liquid waste whose water quality has been adjusted by the water quality adjusting device 54 through the pipe 45. ing.
  • a space region 15 and a region 16 in which a large amount of ferrite particles, which are ⁇ -nuclide adsorbents, are present are formed in the casing.
  • the space region 15 is located upstream of the region 16.
  • the magnetic susceptibility measuring device 49B is installed on the outer surface of the casing of the ⁇ -nuclide removing device 14 facing the region 16.
  • the ⁇ -nuclide adsorbent injection device 69 includes an adsorbent tank 70 filled with ⁇ -nuclide adsorbent, for example, ferrite (Fe 3 O 4 ) particles, and an injection pipe provided with a valve 72A. Has 71. One end of the injection pipe 71 is connected to the adsorbent tank 70, and the other end of the injection pipe 71 is inserted into the space region 15 in the ⁇ -nuclide removing device 14.
  • Ferrite particles which are ⁇ -nuclide adsorbents, can be injected into the radioactive liquid liquid existing in the space region 15 in the casing of the ⁇ -nuclide removing device 14 from the adsorbent tank 70 of the ⁇ -nuclide adsorbent injection device 69 through the injection pipe 71. can.
  • the ⁇ -nuclide adsorbent separating device 72 has, for example, a membrane having a pore size on the order of ⁇ m or less, similarly to the filter 66.
  • the pipe 68 connected between the transfer pump 34 and the valve 35 of the return pipe 36 of the chemical cleaning unit 10 is connected to the ⁇ -nuclide adsorbent separating device 72. Then, the radioactive liquid waste liquid, which is the filtered water from which the ⁇ -nuclide adsorbent has been separated by filtering in the ⁇ -nuclide adsorbent separating device 72, returns to the return pipe 36 through the pipe 68. As a result, the filtered water can be circulated as circulating water.
  • each pipe 36, 67 and 68 are connected to each connection portion between the return pipe 36 and the pipes 67 and 68.
  • a valve (not shown).
  • the decomposition device 107 is filled with, for example, an activated carbon catalyst in which ruthenium is adhered to the surface of the activated carbon.
  • the oxidant supply device 108 has a chemical solution tank 109 and a supply pipe 110.
  • the chemical tank 109 is connected to the disassembling device 107 by a supply pipe 110 having a valve 111.
  • the chemical tank 109 is filled with hydrogen peroxide, which is an oxidizing agent for decomposition.
  • hydrogen peroxide which is an oxidizing agent for decomposition.
  • ozone or water in which oxygen is dissolved may be used instead of hydrogen peroxide.
  • a dry powdering device 20 and a solidifying facility 21 are arranged on the downstream side of the treated water recovery tank 18.
  • a pipe 48 provided with a transfer pump 47 connects the treated water recovery tank 18 and the dry powdering device 20.
  • the pipe 49 connected to the dry powdering apparatus 20 is connected to the solidification equipment 21.
  • a radioactive waste concentrating device may be used instead of the dry powdering device 20, a radioactive waste concentrating device may be used.
  • Radioactive organic waste discharged from the reactor cooling material purification system and fuel pool cooling purification system of a boiling water reactor and stored in the high-dose resin storage tank 2 for a predetermined period of time is a cellulose-based filtration aid. , Ion exchange resin, etc.
  • the radioactive organic waste stored in the high-dose resin storage tank 2 can be easily transferred by supplying the water in the transfer water tank (not shown) to the high-dose resin storage tank 2 by a pipe (not shown). It becomes a slurry state.
  • the radioactive organic waste in the high-dose resin storage tank 2 contains a clad removed from the cooling water by the reactor cooling material purification system, the fuel pool cooling purification system, etc., and the clad is radioactive such as cobalt-60. Contains nuclear species.
  • ions of radionuclides other than ⁇ -nuclide such as cobalt-60, cesium-137, carbon-14, and chlorine-36 are adsorbed on the ion exchange resin stored in the high-dose resin storage tank 2. Further, as described above, ⁇ -nuclides (uranium, plutonium, americium, neptunium, curium, etc.) are adsorbed on the ion exchange resin.
  • a slurry containing about 10 wt% of radioactive organic waste is transferred from the high-dose resin storage tank 2 to the first receiving tank 3 through the organic waste supply pipe 23 in a predetermined amount.
  • the slurry of radioactive organic waste in the first receiving tank 3 is supplied to the chemical reaction tank 4 through the organic waste transfer pipe 25 by driving the transfer pump 24.
  • the transfer pump 24 is stopped, and the supply of the slurry to the chemical reaction tank 4 is stopped.
  • the transfer pump 34 is driven, and the water contained in the slurry in the chemical reaction tank 4 is used as radioactive waste liquid (hereinafter referred to as “third radioactive liquid waste”) through the return pipe 36 and the pipe 40 of the waste liquid decomposition device 13.
  • third radioactive liquid waste guided to the waste liquid storage tank is guided to the ⁇ -nuclide removal device 14 through the pipe 45 by driving the transfer pump 43.
  • the third radioactive liquid solution in the waste liquid storage tank does not contain ⁇ -nuclide and contains radionuclides other than ⁇ -nuclide. Includes. Therefore, the water quality of the third radioactive liquid waste containing no ⁇ -nuclide is not adjusted by using the water quality adjusting device 54.
  • the third radioactive liquid waste passes through the ⁇ nuclide removal device 14, is discharged to the pipe 46, and is guided to the treated water recovery tank 18.
  • the ferrite particles in the ⁇ -nuclide removing device 14 injected from the ⁇ -nuclide adsorbent injection device 69 were the ⁇ -nuclide and the radionuclide other than the ⁇ -nuclide. Does not adsorb.
  • the colloidal substances and solids contained in the third radioactive liquid waste are removed by the filter 66 before the third radioactive liquid liquid flows into the ⁇ -nuclide removing device 14.
  • the reducing agent for example, hydrazine which is the decomposable pH adjuster in the decomposition step S10 of the decomposable pH adjuster is not decomposed.
  • the third radioactive effluent contains ⁇ -nuclide
  • decomposition of the pH adjuster that can be decomposed from the ⁇ -nuclide colloid generation step S5 carried out for the first radioactive effluent and the second radioactive effluent, which will be described later.
  • Each step up to the step of step S10 is also carried out for the third radioactive liquid waste.
  • the pH adjuster determination step S9 is "NO"
  • the decomposition step S10 of the decomposable pH adjuster is not carried out. Whether or not the third radioactive liquid contains ⁇ -nuclide is determined based on the radiation intensity detected by the radiation detector arranged near the outer surface of the waste liquid storage tank of the waste liquid decomposition device 13.
  • the third radioactive liquid waste does not contain ⁇ nuclides, and if the radiation intensity exceeds the set value, the third radioactive liquid waste is ⁇ . It is determined that the nuclide is contained.
  • the transfer pump 43 is stopped.
  • the third radioactive liquid waste collected in the treated water recovery tank 18 is supplied to the dry powdering device 20 through the pipe 48 by driving the transfer pump 47 in a predetermined amount.
  • the third radioactive liquid waste containing radionuclides other than ⁇ -nuclide is pulverized by the dry powdering apparatus 20 (volume reduction step S11).
  • the powder produced by the dry powdering apparatus 20 is transferred to the solidifying facility 21 (or filling facility).
  • the powder is filled in the solidification container, and a solidifying material (for example, cement) is injected into the solidification container.
  • the powder in the solidification container is solidified by the solidifying material (container filling or solidification step S12).
  • the solidified powder is present inside and the sealed solidified container is stored in a storage location. There are no ultra-half-life alpha nuclides in this solidified vessel that is stored.
  • a filling facility is used, the container is filled with powder, the container filled with the powder is sealed, and then the container is stored in a storage place.
  • an oxalic acid aqueous solution (oxalic acid concentration of 0.8 mol) of about 72 g / L is driven by the transfer pump 32. / L) is supplied from the cleaning liquid supply tank 6 through the cleaning liquid supply pipe 33.
  • This oxalic acid aqueous solution is an organic acid aqueous solution.
  • the valve 26 is opened, the oxalic acid aqueous solution having a oxalic acid concentration of 0.8 mol / L is supplied to the cleaning liquid supply tank 6 from the organic acid tank 7 through the pipe 29.
  • the valve 27 and the valve 28 are in the fully closed state.
  • a citric acid aqueous solution may be used instead of the oxalic acid aqueous solution.
  • the oxalic acid aqueous solution in the chemical reaction tank 4 is heated by the heating device 5.
  • the heating temperature of the oxalic acid aqueous solution is less than 100 ° C.
  • the oxalic acid contained in the oxalic acid aqueous solution supplied into the chemical reaction tank 4 dissolves the clad adhering to the radioactive organic waste in the chemical reaction tank 4 (first cleaning step S1). By dissolving the clad, the radionuclides contained in the clad, for example, cobalt-60, are transferred into the aqueous oxalic acid solution.
  • the clad component contained in the oxalic acid aqueous solution generated by the dissolution of the clad with the oxalic acid aqueous solution in the chemical reaction tank 4 is precipitated in the chemical reaction tank 4. Only the oxalic acid aqueous solution, which is the supernatant liquid in the chemical reaction tank 4, generated by the precipitation of the clad-dissolved component is collected in the cleaning liquid supply tank 6 through the return pipe 36 by driving the transfer pump 34. At this time, the valve 39 is closed and the valve 35 is open. The oxalic acid aqueous solution recovered in the cleaning liquid supply tank 6 is supplied to the chemical reaction tank 4 and reused for dissolving the clad in the chemical reaction tank 4.
  • the ion exchange resin which is a part of the radioactive organic waste is immersed in the oxalic acid which is an organic acid
  • a part of the radionuclides adsorbed on the ion exchange resin is an ion exchange resin. Be separated from. Specifically, hydrogen ions and oxalate ions generated by dissociation of oxalic acid are ion-exchanged with radioactive nuclei adsorbed on the cation exchange resin and anion exchange resin, respectively, so that some radioactive nuclei ( ⁇ nuclei and radioactive nuclei other than ⁇ nuclei) are desorbed from the ion exchange resin.
  • first radioactive waste liquid is transferred to the waste liquid storage tank of the waste liquid decomposition device 13 through the pipes 36 and 40 by driving the transfer pump 34.
  • the transfer of the first radioactive liquid waste and the second radioactive liquid waste described later from the chemical reaction tank 4 of the chemical cleaning unit 10 to the waste liquid decomposition device 13 of the waste liquid treatment unit 19 is, for example, sampling attached to the return pipe 36.
  • the fact that the ⁇ -nuclear species concentration of each of the collected first radioactive liquid and second radioactive liquid became a predetermined concentration means that the clad adhering to the radioactive organic waste in the chemical reaction tank 4 in the first cleaning step S1 is chemical.
  • the ⁇ nuclei that were sufficiently dissolved in the organic acid aqueous solution in the reaction tank 4 and that were adsorbed on the radioactive organic waste (for example, cation exchange resin) in the chemical reaction tank 4 were organic in the chemical reaction tank 4. It means that it was sufficiently eluted in the aqueous acid salt solution.
  • the waste liquid decomposition step S4 is carried out.
  • ozone is supplied from the ozone supply device 50 through the ozone supply pipe 52 to the ozone injection pipe 51 in the waste liquid storage tank for a predetermined time, and the waste liquid is discharged from a large number of injection holes formed in the ozone injection pipe 51. It is sprayed into the first radioactive liquid waste in the storage tank.
  • Oxalic acid which is an organic component contained in the first radioactive liquid waste, is decomposed by the injected ozone.
  • Oxalic acid reacts with ozone and is decomposed into carbon dioxide and water.
  • the residue of ozone injected into the waste liquid storage tank and carbon dioxide gas are supplied to the off-gas treatment device (not shown) through the gas exhaust pipe 53 connected to the waste liquid storage tank, and are contained in the gas discharged to the gas exhaust pipe 53.
  • the radioactive gas is removed by an off-gas treatment device.
  • the ⁇ nuclide colloid production step S5 is carried out.
  • the pH adjusting agent is injected from the pH adjusting agent injection device 55 through the injection pipe 42 into the first radioactive liquid waste in the pipe 45.
  • an acid, an oxidizing agent for adjusting water quality, a reducing agent and an alkali are used as the pH adjusting agent to be injected into the first radioactive liquid waste in the pipe 45.
  • the water quality adjusting device 54 By using an acid, a water quality adjusting oxidant, a reducing agent and an alkali as the pH adjusting agent, the water quality adjusting device 54 causes the ⁇ nuclei species colloid production step S5 to be performed among the acid, the water quality adjusting oxidizing agent, the reducing agent and the alkali.
  • the corresponding pH adjuster can be injected into the first radioactive effluent in the pipe 45. Which of the acid, the oxidizing agent for water quality adjustment, the reducing agent and the alkali is injected is determined according to the properties of the first radioactive liquid waste before the water quality adjustment and the target properties of the first radioactive liquid waste after the water quality adjustment. ..
  • the corresponding pH adjuster in order to adjust the pH of the first radioactive liquid containing the ⁇ -nuclide in the pipe 45 to a pH in the range of 4 or more and less than 8, the corresponding pH adjuster is used. It is injected into the pipe 45 from the water quality adjusting device 54.
  • the pH of the first radioactive liquid waste after adjusting the water quality is set to acidic, for example, "4", a predetermined amount of dilute nitric acid aqueous solution which is an acid is injected into the first radioactive liquid waste from the acid injection device 56.
  • the pH of the first radioactive liquid waste When the pH of the first radioactive liquid waste is set to neutral "7", a predetermined amount of dilute nitric acid aqueous solution is added from the acid injection device 56 and a predetermined amount of sodium hydroxide which is alkaline is added from the alkali injection device 79 to the first radioactive liquid waste liquid. Inject into. Further, when the pH of the first radioactive waste liquid is set to, for example, weakly alkaline "7.8", a predetermined amount of dilute nitrate aqueous solution from the acid injection device 56 and a predetermined amount of hydroxide from the alkali injection device 79.
  • Sodium is injected into the first radioactive liquid waste liquid, and further, for example, a predetermined amount of hydrazine, which is an alkaline reducing agent, is injected from the reducing agent supply device 85 of the reducing agent injection device 17.
  • a predetermined amount of hydrazine which is an alkaline reducing agent
  • the pH of the first radioactive effluent is set to, for example, the weakly acidic "6.5”
  • a predetermined amount of dilute nitric acid aqueous solution from the acid injection device 56 and a predetermined amount of sodium hydroxide from the alkali injection device 79 are predetermined amount of sodium hydroxide from the alkali injection device 79, respectively.
  • oxalic acid organic acid
  • a predetermined amount of oxalic acid which is an oxidizing agent for adjusting water quality
  • the pH of the first radioactive effluent is set to, for example, acidic "4.5”
  • a predetermined amount of dilute nitric acid aqueous solution is used from the acid injection device 56, and the reducing agent supply device 85 of the reducing agent injection device 17 is used, for example.
  • a predetermined amount of dilute nitrate aqueous solution, a predetermined amount of sodium hydroxide, a predetermined amount of hydrazine and a predetermined amount of oxalic acid are injected. Increase the injection amount of hydrazine slightly more than the injection amount of oxalic acid.
  • inject a predetermined amount of dilute nitrate aqueous solution, a predetermined amount of sodium hydroxide, a predetermined amount of hydrazine and a predetermined amount of oxalic acid, and oxalic acid inject a predetermined amount of dilute nitrate aqueous solution, a predetermined amount of sodium hydroxide, a predetermined amount of hydrazine and a predetermined amount of oxalic acid, and oxalic acid.
  • the injection volume of hydrazine is slightly larger than the injection volume of hydrazine.
  • the redox potential in the reducing agent injection device 17 The redox potential adjusting agent aqueous solution in the redox potential adjusting agent tank 90 of the adjusting agent supply device 89, for example, the ascorbic acid aqueous solution may be injected into the first radioactive liquid waste in the pipe 45.
  • the injection amount of the ascorbic acid aqueous solution is adjusted by controlling the opening degree of the valve 91.
  • the change in pH of the first radioactive liquid by the ascorbic acid aqueous solution to the acidic side is made into the first radioactive liquid by the reducing agent supply device 85 of the reducing agent injection device 54, for example, the hydrazine aqueous solution which is an alkaline reducing agent. It may be supplemented by injecting, and the pH of the first radioactive effluent may be adjusted to the above-mentioned predetermined pH value.
  • the acid is injected by injecting the dilute nitric acid aqueous solution in the acid tank 57 of the acid injection device 56 into the pipe 45 through the injection pipes 59A and 42 by opening the valve 58.
  • the injection amount of the dilute nitric acid aqueous solution is adjusted by controlling the opening degree of the valve 58.
  • Alkali injection is performed by injecting the sodium hydroxide aqueous solution in the alkali tank 80 of the alkali injection device 79 into the pipe 45 through the injection pipes 82 and 42 by opening the valve 81.
  • the injection amount of the sodium hydroxide aqueous solution is adjusted by controlling the opening degree of the valve 81.
  • the hydrazine aqueous solution in the reducing agent tank 86 of the reducing agent supply device 85 in the reducing agent injection device 17 is supplied to the mixing tank 17A through the injection pipe 88 and the pipe 93 by opening the valve 87, and further. , Is performed by injecting into the pipe 45 from the mixing tank 17A through the injection pipe 42. At this time, the valve 41 is open. The injection amount of the hydrazine aqueous solution is adjusted by controlling the opening degree of the valve 87.
  • the ascorbic acid aqueous solution in the redox potential adjusting agent tank 90 of the redox potential adjusting agent supply device 89 in the reducing agent injection device 54 is injected into the injection pipe 92 and the pipe by opening the valve 91. This is performed by supplying the mixture to the mixing tank 17A through 93, and further injecting the mixture from the mixing tank 17A into the pipe 45 through the injection pipe 42. At this time as well, the valve 56 is open. The injection amount of the ascorbic acid aqueous solution is adjusted by controlling the opening degree of the valve 91.
  • the water quality adjusting oxidant is injected by injecting the oxalic acid aqueous solution in the oxidant tank 76 of the oxidant injection device 75 into the pipe 45 through the injection pipes 78 and 42 by opening the valve 77.
  • the injection amount of the oxalic acid aqueous solution is adjusted by controlling the opening degree of the valve 77.
  • the hydrazine aqueous solution from the reducing agent supply device 85 and the ascorbic acid aqueous solution from the oxidation-reduction potential adjuster supply device 89 are each mixed in the mixing tank 17A.
  • the hydrazine aqueous solution and the ascorbic acid aqueous solution may be injected into the pipe 45 from the mixing tank 17A through the injection pipe 42.
  • the pH of the first radioactive liquid waste liquid in the pipe 45 whose water quality has been adjusted by injecting the pH adjusting agent into the pipe 45 by the water quality adjusting device 54 is measured by a pH meter 49A.
  • Corresponding injection device (reducing agent injection device 17, acid injection device 56, oxidant) of the pH adjuster injection device 54 that supplies the pH adjuster that needs to be injected into the pipe 45 based on the pH measurement value of the pH meter 49A.
  • the opening of the valve of the injection device 75 and at least one of the alkali injection devices 79) is controlled, and the pH of the first radioactive liquid waste liquid is adjusted to a predetermined value from the corresponding injection device to the pipe 45. Adjust the injection amount of the pH adjuster.
  • the pH of the first radioactive liquid waste discharged from the waste liquid decomposition device 13 to the pipe 45 before the water quality is adjusted is, for example, 6.
  • the pH adjuster is injected from the water quality adjusting device 54 into the first radioactive liquid through the injection pipe 42.
  • the pH of the first radioactive liquid waste is adjusted to a range of 4 or more and less than 8, for example, 7.8.
  • a predetermined amount of the sodium hydroxide aqueous solution in the alkaline tank 80 of the alkaline injection device 79 is passed through the injection pipes 82 and 42 by opening the valve 81, and the inside of the pipe 45 is filled. Inject into. Further, the dilute aqueous nitrate solution in the acid tank 57 of the acid injection device 56 is injected into the pipe 45 through the injection pipes 59A and 42 by opening the valve 58 in a predetermined amount, and is injected into the reducing agent tank 86 of the reducing agent supply device 85.
  • aqueous solution of sodium hydroxide and an aqueous solution of dilute nitric acid are injected so that the injection amount of sodium hydroxide is slightly increased to make the pH of the first radioactive waste liquid slightly higher than that of neutral 7, and the first radioactive solution is used. This is done by injecting an aqueous hydrazine solution so that the pH of the waste liquid is 7.8.
  • the ascorbic acid aqueous solution in the redox potential adjusting agent tank 90 of the redox potential adjusting agent supply device 89 is passed through the injection pipe 42 into the pipe 45 by opening the valve 91. inject.
  • Such adjustment of the injection amount of each pH adjusting agent is performed on the corresponding valve of valves 58, 77, 81, 87 and 92 based on the measured value of the pH of the first radioactive liquid solution measured by the pH meter 49A. This is done by controlling the opening degree.
  • the valve 77 of the oxidant injection device 75 is closed.
  • the water quality adjustment of the first radioactive liquid waste carried out by the water quality adjusting device 54 for example, the pH adjustment of the first radioactive liquid waste is performed with respect to the second radioactive liquid waste described later. Will also be implemented.
  • the pH of the first radioactive liquid waste is set to 7.8, the pH of the first radioactive liquid waste solution is set to 8 or more, for example, 8, and then the inside of the oxidizing agent tank 76 of the oxidizing agent injection device 75.
  • oxalic acid may be injected into the first radioactive liquid waste having a pH of 8 to bring the pH of the first radioactive liquid waste liquid to 7.8.
  • the pH of the first radioactive liquid temporarily exceeds less than 8 until the pH of the first radioactive liquid becomes 7.8, which is less than 8, due to the injection of oxalic acid.
  • Each of the contained U, Pu and Np remains ionic rather than colloidal and solid.
  • Each of the ionic states U, Pu and Np is not removed by the filter 66, but flows into the ⁇ -nuclide removing device 14. Therefore, by injecting at least one of dilute nitric acid and sodium hydroxide, the pH of the first radioactive liquid waste is adjusted to a pH value within the range of 4 or more and less than 8, and then the reducing agent and water quality are adjusted.
  • the pH of the first radioactive liquid waste may be adjusted to the target pH value by injecting at least one of the adjusting oxidizing agents.
  • Acids such as dilute nitrates and alkalis, such as sodium hydroxide, can significantly change the pH and redox potential of radioactive effluents and are reducing agents such as hydrazine and water quality adjusting reducing agents.
  • the change in pH and redox potential of the radioactive effluent is smaller than that of dilute nitric acid and sodium hydroxide.
  • the pH of the first radioactive liquid waste containing the corresponding pH adjuster for example, sodium hydroxide, dilute nitrate and hydrazine
  • the first Of the ⁇ -nuclides contained in the radioactive waste liquid the colloids and solids of U, Pu and Np are generated in the first radioactive liquid waste and precipitated in the first radioactive liquid waste.
  • the pH of the first radioactive liquid waste is adjusted to a value in the range of 4 or more and less than 8
  • Am and Cm of ⁇ nuclides do not become colloids and solids and remain ions.
  • the colloid removal step S6 of the ⁇ nuclide is carried out.
  • the first radioactive liquid waste whose pH is adjusted within the above range is supplied to the filter 66.
  • the colloids and solids having a large particle size contained in the first radioactive liquid waste produced by the above-mentioned water quality adjustment are filtered by a cross-flow filter method using a membrane having a pore size of ⁇ m or less in the filter 66. , Removed by its membrane. That is, colloids and solids having a large particle size are removed by the filter 66.
  • the amount of ⁇ -nuclide remaining in the first radioactive liquid waste that has passed through the filter 66 is significantly reduced.
  • the first radioactive liquid waste that has passed through the filter 66 is U, Pu, and Np, which are colloids and solids having a small particle size that cannot be removed by the filter 66, ions of U, Pu, and Np, and Am, which is an ⁇ nuclide. And Cm of each ion.
  • the first radioactive liquid liquid having a pH of 7.8 that has passed through the filter 66 flows into the space region 15 in the ⁇ -nuclide removing device 14.
  • a part of the first radioactive liquid waste in which the concentration of ⁇ -nuclide discharged from the filter 66 is reduced to a predetermined concentration or less is returned to the return pipe 36 through the pipe 67.
  • the concentration of ⁇ -nuclide in the first radioactive liquid waste discharged from the filter 66 is measured by an ⁇ -nuclide concentration meter 65.
  • the first radioactive liquid waste in which the concentration of ⁇ -nuclide is reduced to a predetermined concentration or less, which has been returned to the return pipe 36 through the pipe 67, is supplied from the cleaning liquid supply tank 6 to the chemical reaction tank 4 and reused. Emissions can be reduced.
  • ferrite particles are supplied into the ⁇ -nuclide removal device 14 by the ⁇ -nuclide adsorbent injection device 69. Inject into the space area 15. Specifically, in the ⁇ -nuclide adsorbent injection device 69, the valve 72A is opened to inject the ferrite particles in the adsorbent tank 70 into the space region 15 through the injection pipe 71.
  • ⁇ shown in the ⁇ nuclide removing device 14 is an ⁇ nuclide adsorbent (ferrite particle), and ⁇ is an ⁇ nuclide.
  • the colloids and solids having a small particle size that have passed through the filter 66 contained in the first radioactive liquid waste are removed by the ferrite particles.
  • the magnetic susceptibility measuring device 49B provided in the ⁇ -nuclide removing device 14 detects whether ferrite is present in the ⁇ -nuclide removing device 14.
  • FIG. 10 shows the relationship between the size of the ferrite particles, which are the ⁇ -nuclide adsorbent, and the amount of ⁇ -nuclide adsorbed per 1 g of the ferrite particles.
  • the sizes of the ferrite particles are granular (particle size ⁇ 100 ⁇ m) and fine powder (particle size ⁇ 1 ⁇ m), and adsorption of each of the granular (particle size ⁇ 100 ⁇ m) and fine powder (particle size ⁇ 1 ⁇ m) ⁇ nuclides.
  • the amount is being compared. As shown in FIG. 10, when the ferrite particles are in the form of fine powder, the amount of ⁇ -nuclide adsorbed per 1 g of the ferrite particles is improved 100 times or more as compared with the case where the ferrite particles are in the form of granules.
  • the ferrite particles on which the ⁇ -nuclide is adsorbed in the ⁇ -nuclide removing device 14 are discharged from the ⁇ -nuclide removing device 14 together with the first radioactive liquid waste as used ferrite particles, and are discharged to the ⁇ -nuclide adsorbent separating device 72 through the pipe 46. Be supplied.
  • the ferrite particles in which the ⁇ -nuclide is adsorbed contained in the first radioactive liquid liquid are first filtered by a cross-flow filter method using, for example, a film having a pore size of ⁇ m order or less. It is separated from the radioactive liquid waste (adsorbent separation step S8).
  • Ferrite particles may be separated by the ⁇ -nuclide adsorbent separating device 72 by a dead-end filter method instead of the cross-flow filter method.
  • the first radioactive liquid waste from which the ferrite particles on which the ⁇ -nuclide is adsorbed is separated is discharged from the ⁇ -nuclide adsorbent separating device 72 to the pipe 46.
  • the filtrate filtered by the membrane is supplied to the return pipe 36 through the pipe 68.
  • the acid (for example, dilute nitrate) and alkali (for example, sodium hydroxide) injected into the first radioactive liquid (or the second radioactive liquid described later) are indestructible pH adjusters.
  • the alkaline reducing agent (eg, hydrazine) and the oxidation-reducing potential regulator (eg, ascorbic acid) are degradable pH regulators.
  • a water quality adjusting oxidant for example, oxalic acid
  • the water quality adjusting oxidant for example, oxalic acid
  • dilute nitrate and sodium hydroxide which are non-decomposable pH reducers are used.
  • the “pH adjuster degradable pH adjuster” in the pH adjuster determination step S9 The determination of "is” is "YES", and the first radioactive liquid containing hydrazine and ascorbic acid from which ⁇ nuclides, colloidal substances and solids have been removed by the ferrite particles of the ⁇ nuclide removal device 14 is ⁇ .
  • the nuclide adsorbent separating device 72 is guided to the decomposition device 107 through the pipe 46.
  • Hydrazine and ascorbic acid contained in the first radioactive liquid waste are decomposed in the decomposition apparatus 107. That is, the valve 111 is opened to supply the hydrogen peroxide in the chemical solution tank 109 to the decomposition device 107 through the supply pipe 110.
  • the action of the activated carbon catalyst and hydrogen peroxide decomposes hydrazine contained in the first radioactive liquid waste into nitrogen and water, and ascorbic acid into oxygen and water (a decomposable pH adjuster). Disassembly step S10).
  • the first radioactive liquid waste containing no ⁇ -nuclide and hydrazine but containing dilute nitric acid and sodium hydroxide discharged from the decomposition apparatus 107 is guided to the treated water recovery tank 18 through the pipe 46.
  • the ⁇ -nuclide colloid production step S5 when a dilute aqueous nitric acid solution and sodium hydroxide are injected into the primary radioactive effluent to bring the pH to 7, a pH adjuster (hydrazine) that can be decomposed into the primary radioactive effluent is used. And oxalic acid) are not contained, so that the determination in the pH adjuster determination step S9 is “No”. Therefore, the first radioactive liquid waste containing dilute nitric acid and sodium hydroxide discharged from the ⁇ -nuclide removal device 14 is guided to the decomposition device 107, but in this case, since the valve 111 is closed, the chemical liquid tank. The hydrogen peroxide in 109 is not supplied to the decomposition apparatus 107. The first radioactive liquid waste containing dilute nitric acid and sodium hydroxide is discharged from the decomposition apparatus 107 as it is and guided to the treated water recovery tank 18.
  • a pH adjuster hydrozine
  • the water quality adjusting oxidizing agent for example, oxalic acid
  • the filter 66 colloids and solids having large particle sizes of U, Pu and Np produced in the first radioactive liquid waste having a pH of 6 are removed by the filter 66 (colloid removal step S6 of ⁇ -nuclide).
  • the first radioactive effluent discharged from the filter 66 and from which the colloid and solid content have been removed is supplied to the ⁇ -nuclide removing device 14, and the ⁇ -nuclide ions contained in the first radioactive effluent are ferrite in the ⁇ -nuclide removing device 14. It is adsorbed on the particles and removed (alpha nuclide ion removal step S7).
  • the ferrite particles contained in the first radioactive liquid waste are separated by the ⁇ -nuclide adsorbent separator 72, and the pH adjuster determination step S9 is determined for the first radioactive liquid liquid containing no ferrite particles and having a pH of 6. .. Since the first radioactive liquid waste having a pH of 6 contains a water quality adjusting oxidizing agent (for example, oxalic acid) as a decomposable pH adjusting agent, the determination in the pH adjusting agent determination step S9 is "YES". Become.
  • the first radioactive liquid waste is supplied to the decomposition device 107, and the action of hydrogen peroxide in the activated carbon catalyst and the chemical liquid tank 109 in the decomposition device 107 causes an oxidizing agent for adjusting the water quality (for example, Shu) contained in the first radioactive liquid waste.
  • Acid is decomposed.
  • oxalic acid is decomposed into carbon dioxide and water in the decomposition apparatus 107.
  • the amount of the first radioactive liquid waste can be reduced by decomposing the water quality adjusting oxidizing agent (for example, oxalic acid) contained in the first radioactive liquid waste liquid.
  • the first radioactive liquid waste (the first radioactive liquid waste in which hydrazine or oxalic acid is decomposed and contains dilute nitrate and sodium hydroxide) in the treated water recovery tank 18 described above is dried powder by a pipe 48 by driving a transfer pump 47. It is supplied to the chemical conversion device 20 and pulverized (volume reduction step S11).
  • the ⁇ -nucleus-free powder produced by the dry powdering apparatus 20 is transferred to the solidifying facility 21 through the pipe 49 and filled in the solidifying container, and the solidifying material is injected into the solidifying container to solidify it. (Container filling or solidification step S12). This solidified container is sealed and then stored in a storage location. There are no ultra-half-life alpha nuclides in this solidified vessel that is stored.
  • the powder produced by powdering the first radioactive liquid waste liquid contains nitric acid and sodium hydroxide, and this powder is contained in the solidification container.
  • the vitrified material produced by solidifying with the glass melted in (1) also contains nitric acid and sodium hydroxide.
  • the clad is still dissolved in the chemical reaction tank 4, and the radioactive organic waste containing the cation exchange resin is contained. However, it remains. Subsequently, the radioactive organic waste containing this cation exchange resin will be treated.
  • an aqueous solution of hydrazine formate (organic acid salt aqueous solution) of about 40 to 400 g / L is continuously discharged from the cleaning liquid supply tank 6 through the cleaning liquid supply pipe 33 into the chemical reaction tank 4 in which radioactive organic waste remains. Is supplied.
  • the concentration of hydrazine formate in an aqueous solution of hydrazine formate is the mass of solute (hydrazine formate) per liter of solution.
  • the aqueous solution of hydrazine formate supplied to the chemical reaction tank 4 is a neutral liquid having a pH of about 7.
  • the hydrazine formate aqueous solution is supplied to the cleaning liquid supply tank 6 from the organic acid salt tank 8 through the pipe 30 and the pipe 29 by opening the valve 27.
  • the valve 26 and the valve 28 are closed.
  • the radioactive organic waste comes into contact with the aqueous solution of hydrazine formate in the chemical reaction tank 4.
  • the ⁇ nuclides uranium, plutonium, americium, neptunium and chlorine adsorbed on the cation exchange resin, which is a radioactive organic waste, and cobalt, which is a radionuclide other than the ⁇ nuclide, are adsorbed by this contact.
  • the ions of 60, cesium-137, carbon-14, and chlorine-36 are eluted in the aqueous solution of hydrazine formate (second washing step S2).
  • the decontamination performance (decontamination coefficient) for cobalt-60 adsorbed on the cation exchange resin is about DF4.
  • the decontamination performance was DF20 or higher, and the decontamination performance was improved as compared with the case where the oxalic acid aqueous solution was brought into contact with the resin.
  • the hydrazine formate aqueous solution is used, the repetition becomes unnecessary, and the amount of the cleaning agent used, that is, the amount of oxalic acid can be reduced.
  • the decontamination coefficient DF is a numerical value calculated by (counting rate before decontamination) / (counting rate after decontamination).
  • Decontamination with hydrazine formate ion elution
  • oxalic acid clad dissolution
  • the decontamination coefficient DF is (counting rate before decontamination) / (clad dissolution). It is a value calculated by the count rate of only).
  • the decontamination coefficient DF is a value calculated by (counting rate before decontamination) / (counting rate after clad dissolution and ion elution).
  • second radioactive liquid waste containing the eluted ⁇ -nuclide and radioactive nuclides other than the ⁇ -nuclide in the chemical reaction tank 4 passes through the pipe 36 and the pipe 40 to the above-mentioned waste liquid decomposition apparatus. It is transferred to 13 waste liquid storage tanks.
  • the valve 25 is opened and the radioactive organic waste remaining in the chemical reaction layer 4 is guided to the second receiving tank 11 by the pipe 26. ..
  • the radioactive organic waste taken out from the second receiving tank 11 is transferred to the incinerator 12 in a predetermined amount and incinerated in the incinerator 12.
  • the ash produced by incineration is solidified by a solidifying agent such as cement in a solidifying container (incinerator or solidification step S3).
  • the waste liquid decomposition step S4 is carried out.
  • ozone from the ozone supply device 50 is injected into the hydrazine formate aqueous solution in the waste liquid storage tank.
  • Formic acid and hydrazine contained in the aqueous solution of hydrazine formate are decomposed by the injected ozone.
  • Formic acid is decomposed into nitrogen gas and water, and hydrazine is decomposed into carbon dioxide gas and water.
  • the remaining ozone, carbon dioxide gas and nitrogen gas injected into the waste liquid storage tank are supplied to the off-gas treatment device (not shown) through the gas exhaust pipe 53 connected to the waste liquid storage tank.
  • waste liquid decomposition step S4 After the decomposition of formic acid and hydrazine in the waste liquid storage tank of the waste liquid decomposition apparatus 13 (waste liquid decomposition step S4), which was carried out after the second cleaning step S2, is completed, the supply of ozone to the waste liquid storage tank is stopped and transferred.
  • the pump 43 is driven, and the second radioactive liquid containing the ⁇ -nuclide and the radionuclide other than the ⁇ -nuclide, which remains in the waste liquid storage tank after the decomposition of formic acid and hydrazine, is supplied to the water quality adjusting device 54 through the pipe 45. At this time, the valve 44 is open.
  • the ⁇ -nuclide colloid production step S5 is carried out after the waste liquid decomposition step S4 for the second radioactive liquid as well as the above-mentioned first radioactive liquid.
  • the water quality adjusting device 54 injects the corresponding pH adjusting agent from the pH adjusting agent injection device 55 through the injection pipe 42 into the second radioactive liquid waste in the pipe 45.
  • an acid, an oxidizing agent for adjusting water quality, a reducing agent and an alkali are used as the pH adjusting agent to be injected into the second radioactive liquid waste in the pipe 45.
  • an acid, an oxidizing agent for adjusting water quality, a reducing agent and an alkali are used as the pH adjusting agent to be injected into the second radioactive liquid waste in the pipe 45.
  • an acid, an oxidizing agent for adjusting water quality, a reducing agent and an alkali are used as the pH adjusting agent to be injected into the second radioactive liquid waste in the pipe 45.
  • a pH adjuster By injecting a
  • the pH of the second radioactive liquid waste discharged from the waste liquid decomposition device 13 to the pipe 45 before the water quality is adjusted is, for example, 6.
  • the pH adjuster is applied from the water quality adjusting device 54 through the injection pipe 42 in the same manner as the first radioactive liquid.
  • (Ii) Injected into radioactive liquid waste.
  • the pH of the second radioactive liquid waste is in the range of 4 or more and less than 8, for example, 7.8, a predetermined amount of the sodium hydroxide aqueous solution in the alkaline tank 80 is added to the pipe 45 by opening the valve 81. Inject inside.
  • the dilute nitric acid aqueous solution in the acid tank 57 is injected into the pipe 45 by opening the valve 58 in a predetermined amount
  • the hydrazine aqueous solution in the reducing agent tank 17A is injected into the pipe 45 by opening the valve 41 in a predetermined amount.
  • inject into for example, an aqueous solution of sodium hydroxide and an aqueous solution of dilute nitric acid are injected so that the injection amount of sodium hydroxide is slightly increased to make the pH of the second radioactive waste liquid slightly higher than that of neutral 7, and the second radioactive solution is used. This is done by injecting an aqueous hydrazine solution so that the pH of the waste liquid is 7.8.
  • the ascorbic acid aqueous solution in the redox potential adjusting agent tank 90 of the redox potential adjusting agent supply device 89 is passed through the injection pipe 42 and into the pipe 45 by opening the valve 91. Inject into the second radioactive effluent.
  • Such adjustment of the injection amount of each pH adjuster controls the opening degree of the corresponding valve among the valves 41, 58 and 80 based on the measured value of the pH of the second radioactive liquid solution measured by the pH meter 49A. It is done by doing.
  • the valve 77 of the oxidant injection device 75 is closed.
  • the second radioactive liquid liquid having a pH of 7.8 containing the ions of the above flows into the space region 15 in the ⁇ -nuclide removing device 14.
  • the ferrite particles are injected from the ⁇ -nuclide adsorbent injection device 69 into the space region 15.
  • each ⁇ -nuclide (U, Pu, Np, Am and Cm) contained in the second radioactive liquid waste and having a valence of "3 to 5" is high. , Adjusted to "3" within the space area 15.
  • Each ⁇ -nuclide whose valence is adjusted to “3” contained in the second radioactive liquid waste is efficiently adsorbed and removed by ferrite particles in the region 16 in the presence of a reducing agent (for example, hydrazine) ( Ion removal step S7) for ⁇ -nuclide.
  • a reducing agent for example, hydrazine
  • the ferrite particles on which the ⁇ -nuclide is adsorbed in the ⁇ -nuclide removing device 14 are discharged from the ⁇ -nuclide removing device 14 together with the second radioactive liquid waste as used ferrite particles, and are discharged to the ⁇ -nuclide adsorbent separating device 72 through the pipe 46. Be supplied.
  • the ferrite particles in which the ⁇ -nuclide is adsorbed contained in the second radioactive liquid waste liquid are present in the ⁇ -nuclide adsorbent separator 72, for example, by filtration by a cross-flow filter method using a film having a pore size of ⁇ m order or less.
  • the second radioactive liquid waste from which the ferrite particles on which the ⁇ -nuclide is adsorbed is separated is discharged from the ⁇ -nuclide adsorbent separating device 72 to the pipe 46.
  • a reducing agent which is a decomposable pH adjuster, for example, hydrazine is injected into the second radioactive liquid waste, so that the determination in the pH adjuster determination step S9 is “YES”. Therefore, the second radioactive liquid waste having a pH of 7.8 and containing hydrazine in the pipe 46 is guided from the ⁇ -nuclide adsorbent separating device 72 to the decomposition device 107.
  • the hydrazine contained in the second radioactive liquid waste is decomposed by the action of the activated carbon catalyst and hydrogen peroxide in the decomposition apparatus 107 in the same manner as the hydrazine contained in the first radioactive liquid waste (reducing agent decomposition step S10).
  • the first radioactive liquid waste containing no ⁇ -nuclide and hydrazine but containing dilute nitric acid and sodium hydroxide discharged from the decomposition apparatus 107 is guided to the treated water recovery tank 18 through the pipe 46.
  • a non-decomposable pH adjuster for example, dilute nitrate and sodium hydroxide
  • the pH that can be decomposed into the second radioactive liquid is
  • the adjusting agent for example, hydrazine and oxalic acid
  • the determination in the pH adjusting agent determination step S9 becomes "No"
  • the second radioactive liquid waste discharged from the ⁇ nuclide removing device 14 is a chemical liquid tank. No hydrogen peroxide is supplied from 109, and the hydrogen peroxide passes through the decomposition device 107 as it is and is guided to the treated water recovery tank 18.
  • the second radioactive liquid waste (the first radioactive liquid waste in which hydrazine or oxalic acid is decomposed and contains dilute nitrate and sodium hydroxide) in the treated water recovery tank 18 is driven by a transfer pump 47 and dried and powdered by a pipe 48. It is supplied to No. 20 and pulverized (volume reduction step S11).
  • the ⁇ -nucleus-free powder produced by the dry powdering apparatus 20 is transferred to the solidifying facility 21 through the pipe 49 and filled in the solidifying container, and the solidifying material is injected into the solidifying container to solidify it. (Container filling or solidification step S12). This solidified container is sealed and then stored in a storage location. There are no ultra-half-life alpha nuclides in this solidified vessel that is stored.
  • the powder produced by powdering the second radioactive waste liquid contains nitric acid and sodium hydroxide, and this powder is contained in the solidification container.
  • the vitrified material produced by solidifying with the glass melted in (1) also contains nitric acid and sodium hydroxide.
  • a pH adjuster alkaline, acid, at least one of an oxidizing agent for adjusting water quality and a reducing agent
  • the radioactive liquid waste containing ⁇ -nuclide each of the first radioactive liquid waste and the second radioactive liquid liquid described later.
  • U, Pu and Np colloids of ⁇ nuclides having a super half-life can be produced in the radioactive liquid waste. Since the produced colloid is removed by the filter 66 in the colloid removal step S6 of the ⁇ -nuclide, the concentration of the ⁇ -nuclide having a super half-life contained in the radioactive liquid liquid flowing into the ⁇ -nuclide removing device 14 is reduced.
  • the amount of the ⁇ -nuclide adsorbent (for example, ferrite particles) injected into the ⁇ -nuclide removing device 14 can be reduced, and the amount of the ⁇ -nuclide adsorbent used can be reduced. As a result, the ⁇ -nuclide removing device 14 becomes more compact.
  • the ⁇ -nuclide adsorbent for example, ferrite particles
  • a pH adjusting agent is injected into the radioactive liquid waste containing the ⁇ -nuclide, and the pH of this radioactive liquid waste is set to a pH within the range of 4 or more and less than 8. , Can be produced in radioactive liquid waste.
  • the granular ⁇ -nuclide adsorbent is injected from the ⁇ -nuclide adsorbent injection device 69 into the radioactive liquid waste containing the ⁇ -nuclide in the ⁇ -nuclide removal device 14, the ⁇ -nuclide that comes into contact with the radioactive liquid in the ⁇ -nuclide removal device 14
  • the surface area of the adsorbent increases, and the ⁇ -nuclide removed by the ⁇ -nuclide adsorbent increases.
  • the amount of ⁇ -nuclide adsorbed by the ⁇ -nuclide adsorbent particles is remarkably increased.
  • the ⁇ -nuclide adsorbent layer filled with the ⁇ -nuclide adsorbent particles described in the specification of Japanese Patent Application No. 2018-210315 is inside. It is possible to control the time during which the ⁇ -nuclide adsorbent particles are immersed in the radioactive liquid waste in the ⁇ -nuclide removing device 14 as compared with the case where the radioactive liquid containing the ⁇ -nuclide is supplied to the formed ⁇ -nuclide removing device.
  • the ⁇ -nuclide adsorbent particles from the ⁇ -nuclide removing device 14 to the ⁇ -nuclide adsorbent separating device 72 are included. It becomes possible to supply radioactive liquid waste. Therefore, radioactive waste containing ⁇ -nuclide can be reduced.
  • an organic acid aqueous solution for example, an oxalic acid aqueous solution
  • an organic acid salt aqueous solution for example, formic acid
  • the concentration of radionuclides contained in the radioactive organic waste can be reduced, and the amount of high-dose radioactive waste can be reduced. Can be reduced.
  • the ions of radioactive nuclei including the ions of ⁇ nuclei remaining adsorbed on the cation exchange resin without being desorbed from the cation exchange resin by the organic acid aqueous solution are brought into contact with the organic acid salt aqueous solution to the radioactive organic waste. By doing so, it can be efficiently desorbed from the cation exchange resin.
  • the ⁇ -nuclide having an ultra-half-life contained in the radioactive effluent is an ⁇ -nuclide removing device. It is easily removed by the ferrite ( ⁇ -nuclide adsorbent) injected into 14.
  • the ⁇ -nuclide contained in the radioactive effluent is removed by the ⁇ -nuclide removing device 14, and the ⁇ -nuclide having a super half-life contained in the radioactive effluent flowing out from the ⁇ -nuclide removing device 14 is significantly reduced.
  • the radiation dose of the radioactive liquid spilled from the ⁇ -nuclide removing device 14 is remarkably reduced, and the amount of radioactive waste (for example, solidified body) containing the ⁇ -nuclide having a super half-life can be reduced.
  • the ⁇ -nuclide concentration of each of the first radioactive liquid and the second radioactive liquid discharged from the chemical reaction tank 4 to the return pipe 36 reaches a predetermined concentration
  • the ⁇ -nuclide is transferred from the chemical reaction tank 4 to the waste liquid decomposition apparatus 13.
  • the adsorption performance of the ⁇ -nuclide in the ⁇ -nuclide adsorbent contained in each of the first radioactive effluent and the second radioactive effluent can be sufficiently exhibited. ..
  • the ⁇ -nuclide adsorbent existing in the ⁇ -nuclide removing device 14 is separated as the used ⁇ -nuclide adsorbent by the ⁇ -nuclide adsorbent separating device 72.
  • the separated ⁇ -nuclide adsorbent is stored in a solidification container (hereinafter, referred to as “first solidification container”).
  • first solidification container a solidification container
  • the molten glass is filled in a first solidification container containing a predetermined amount of used ⁇ -nuclide adsorbent adsorbing ⁇ -nuclide.
  • the first solidifying container containing a predetermined amount of used ⁇ -nuclide adsorbent is sealed.
  • the radioactive organic waste stored in the high-dose resin storage tank 2 contains a cation exchange resin in which ⁇ -nuclides are adsorbed, the radioactive organic described in JP-A-2015-64334 described above
  • ⁇ -nuclide is found in each of the organic acid aqueous solution in which the clad contained in the radioactive organic waste is dissolved and the organic acid salt aqueous solution in which the ⁇ -nuclide is desorbed from the cation exchange resin.
  • the first radioactive effluent produced by decomposing the organic acid of the organic acid aqueous solution containing ⁇ nuclei with a decomposition oxidant, and the organic acid salt of the organic acid aqueous solution containing ⁇ nuclei are decomposed with a decomposing oxidant.
  • Each of the second radioactive effluents produced is pulverized and filled in separate solidification containers (hereinafter referred to as "second solidification containers"), and then, for example, molten glass is placed in each second solidification container. Is filled with. After the molten glass that solidifies the powder containing the ⁇ -nuclide of the first radioactive liquid waste is solidified in the second solidifying container, the second solidifying container is sealed. After the molten glass that solidifies the powder containing the ⁇ -nuclide of the second radioactive liquid waste is solidified in the second solidifying container, the second solidifying container is sealed.
  • the processing method of this example and the processing method described in Japanese Patent Application Laid-Open No. 2015-64334 are compared.
  • the amount of radioactive organic waste to be carried out in the first cleaning step S1 and the second cleaning step S2 is the same, and the amount of clad to be dissolved and the amount of ⁇ -nuclide to be desorbed are the same. It is assumed that the amount of the first radioactive liquid waste and the amount of the second radioactive liquid waste generated are the same.
  • the number of vitrified wastes generated by vitrifying the ferrite adsorbed with ⁇ nuclei in the first solidification vessel, which is generated in this example is the treatment described in JP-A-2015-64334.
  • the organic acid contained in the organic acid aqueous solution in which the clad is dissolved for example, oxalic acid
  • the organic acid salt contained in the organic acid salt aqueous solution in which ⁇ nuclei are eluted for example, hydrazine formate
  • the clad contained in the radioactive organic waste is dissolved by the organic acid aqueous solution (first cleaning step S1), and the organic acid salt aqueous solution is adsorbed by the cation exchange resin which is the radioactive organic waste. Since the desorption of the ⁇ nuclei (second cleaning step S2) is sequentially carried out in one cleaning tank (for example, the chemical reaction tank 4), the radioactive liquid waste treatment system can be made more compact.
  • the water quality adjusting device 54A shown in FIG. 5 can be used instead of the water quality adjusting device 54.
  • the water quality adjusting device 54A includes a desolved carbon dioxide agent injection device 59, an oxidation-reduction potential measuring device 63, and a carbon dioxide concentration meter 64, as well as a pH adjusting agent injection device 55 and a pH meter 49A in the water quality adjusting device 54.
  • the dissolved carbonic acid agent injection device 59 has a dissolved carbonic acid agent tank 60 and an injection pipe 62 provided with a valve 61.
  • the injection pipe 62 connected to the dissolved carbonate tank 60 is connected to the pipe 45 between the attachment position of the pH meter 49A to the pipe 45 and the filter 66.
  • the removal of dissolved carbon dioxide agent tank 60, as de-dissolved carbon agent, sodium sulfite, N 2 gas and Ar gas or the like is filled.
  • the redox potential measuring device 63 is attached to the pipe 45 between the attachment position of the pH meter 49A to the pipe 45 and the connection position between the injection pipe 62 and the pipe 45.
  • the carbonic acid concentration meter 64 is attached to the pipe 45 between the connection position of the injection pipe 62 and the pipe 45 and the attachment position of the ⁇ -nuclide concentration meter 65 to the pipe 45.
  • the ⁇ -nuclide colloid production step S5 carried out for each of the first radioactive liquid waste and the second radioactive liquid waste liquid when the water quality adjusting device 54A is used will be described below.
  • the waste liquid decomposition step S4 after the oxalic acid contained in the first radioactive liquid in the waste liquid storage tank of the waste liquid decomposition apparatus 13 is decomposed, the ⁇ nuclide and the first radioactive liquid containing radioactive nuclides other than the ⁇ nuclide are discharged into the pipe 45. It is supplied to the water quality adjusting device 54A through.
  • the water quality is injected from the water quality adjusting device 54A into the first radioactive liquid waste in the pipe 45 through the injection pipe 42.
  • a pH adjuster By injecting a pH adjuster, the pH of the first radioactive liquid waste is adjusted to a range of 4 or more and less than 8, for example, 7.8.
  • a predetermined amount of sodium hydroxide aqueous solution from the alkali injection device 79 of the water quality adjusting device 54A, a dilute nitric acid aqueous solution from the acid injection device 56, and a hydrazine aqueous solution from the reducing agent injection device 17 are provided in the pipe 45. Infused into.
  • the valve 61 is opened to dissolve the dissolved carbonic acid agent 59 in the dissolved carbonic acid tank 60.
  • a carbonate for example sodium sulfite, is injected into the pipe 45 through the injection pipe 62. Injection of sodium sulfite reduces the amount of carbon dissolved in the primary radioactive effluent with a pH of 7.8.
  • the pH of the first radioactive liquid waste can be adjusted to a range of 4 or more and less than 8, for example, 7.8, and is dissolved in the first radioactive liquid waste liquid.
  • the amount of carbon present can be reduced. Therefore, as compared with the case where only the pH of the first radioactive liquid is adjusted by the water quality adjusting device 54, the pH of the first radioactive liquid is adjusted and the amount of dissolved carbon in the first radioactive liquid is reduced by using the water quality adjusting device 54A. In this case, the amount of each colloid of U, Pu and Np among the ⁇ nuclides contained in the first radioactive liquid waste increases.
  • the filter 66 Therefore, more colloids can be removed by the filter 66, and the amount of ⁇ -nuclide removed by the filter 66 increases. Therefore, the amount of ⁇ -nuclide contained in the first radioactive liquid waste supplied from the filter 66 to the ⁇ -nuclide removing device 14 can be reduced, and the amount of ⁇ -nuclide adsorbent injected into the ⁇ -nuclide removing device 14 can also be reduced.
  • alkalinity measuring device 50 ... ozone supply device, 51 ... ozone injection tube, 54, 54A ... Water quality adjusting device 54 ... pH adjusting agent injection device, 56 ... acid injection device, 59 ... dissolved carbonate injection device, 66 ... filter, 69 ... ⁇ nuclei adsorbent injection device, 72 ... ⁇ nuclei adsorbent separator, 75 ... Oxidizing agent injection device, 79 ... Alkali injection device, 107 ... Decomposition device.

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Abstract

Provided is a radioactive waste liquid treatment system whereby an α-nuclide remover for removing α nuclides contained in radioactive waste liquid can be made compact. Crud included in radioactive organic waste containing a positive ion exchange resin is dissolved using an organic acid aqueous solution (S1). The organic acid aqueous solution is exposed to ozone to decompose the organic acid (S4). α nuclides adsorbed on the radioactive organic waste in which crud has been dissolved are eluted by an organic acid salt aqueous solution (S2). The organic acid salt aqueous solution is exposed to ozone to decompose the organic acid salt (S4). A pH adjuster (acid, alkali, reducing agent, oxidizing agent for water conditioning) is poured into the radioactive waste liquid containing the α nuclides, generated in S4 (S5). A colloid of the α nuclides is formed in the radioactive waste liquid, which has been pH-adjusted to a range of no less than 4 to less than 8 by the pH adjuster. The colloid is removed using a filter (S6). Ions of the α nuclides contained in the radioactive waste liquid discharged from the filter are removed by an α-nuclide remover (S7).

Description

放射性廃液処理システム及び放射性廃液の処理方法Radioactive waste liquid treatment system and radioactive liquid waste treatment method
　本発明は、放射性廃液処理システム及び放射性廃液の処理方法に係り、特に、原子力プラントから発生した廃樹脂の洗浄で発生した放射性廃液の処理に適用するのに好適な放射性廃液処理システム及び放射性廃液の処理方法に関する。 The present invention relates to a radioactive liquid waste treatment system and a method for treating radioactive liquid waste, and in particular, a radioactive liquid waste treatment system and a radioactive liquid waste liquid suitable for treatment of radioactive liquid waste generated by cleaning waste resin generated from a nuclear plant. Regarding the processing method.
　原子力プラントの原子炉冷却材浄化系、燃料プール冷却材浄化系等から発生するセルロース系のろ過助材、イオン交換樹脂等を含むフィルタスラッジその他の放射性有機廃棄物は、貯蔵タンクに長期間貯蔵保管されている。これらの放射性有機廃棄物は、原子力プラントの運転に伴って定常的に発生する。放射性有機廃棄物の保管スペースを確保するためには、現在貯蔵中の放射性有機廃棄物の体積を効率的に減らす減容処理技術が必要となる。 Cellulose-based filtration aids generated from nuclear reactor coolant purification systems, fuel pool coolant purification systems, etc., filter sludge containing ion exchange resins, and other radioactive organic waste are stored in storage tanks for a long period of time. Has been done. These radioactive organic wastes are constantly generated during the operation of nuclear power plants. In order to secure a storage space for radioactive organic waste, volume reduction treatment technology that efficiently reduces the volume of radioactive organic waste currently being stored is required.
　イオン交換樹脂は、スチレン・ジビニルベンゼンを基材としており、化学的に安定であるため、長期間安全に貯蔵することが可能である。しかしながら、その安定性のために分解処理が難しく、イオン交換樹脂を減容する場合には、通常、高温での熱分解処理が必要となる。 The ion exchange resin is based on styrene / divinylbenzene and is chemically stable, so it can be safely stored for a long period of time. However, the decomposition treatment is difficult due to its stability, and when the volume of the ion exchange resin is reduced, a thermal decomposition treatment at a high temperature is usually required.
　熱分解処理、及び熱分解処理以外の方法で放射性有機廃棄物を減容する方法が知られており、それらの減容方法の一部が、特開２０１５－６４３３４号公報に記載されている。この特開２０１５－６４３３４号公報には、放射性有機廃棄物を減容するだけでなく、さらに、放射性有機廃棄物に含まれる放射性物質の濃度を低減することができる減容方法が記載されている。特開２０１５－６４３３４号公報に記載された減容方法では、具体的には、有機酸水溶液によって、放射性有機廃棄物に含まれているクラッド（コバルト６０等の放射性核種、酸化鉄等を含む）をコバルト６０等の放射性核種と共に溶解し、有機酸塩水溶液によって、放射性有機廃棄物、例えば、廃樹脂であるイオン交換樹脂に吸着されている放射性核種（コバルト６０、セシウム１３７等）をイオン交換樹脂から溶離させる。さらに、クラッド（酸化鉄等）の溶解に用いられた有機酸水溶液に含まれる有機酸、及び放射性核種を溶離する際に用いられた有機酸塩水溶液に含まれる有機酸塩のそれぞれをオゾン等により分解し、有機酸及び有機酸塩の分解後に残留する、放射性核種を含む廃液を乾燥粉体化し、得られた放射性核種を含む粉体を固形化剤（セメント等）により固化処理する。 Methods for reducing the volume of radioactive organic waste by methods other than thermal decomposition treatment and thermal decomposition treatment are known, and some of these volume reduction methods are described in Japanese Patent Application Laid-Open No. 2015-64334. Japanese Unexamined Patent Publication No. 2015-64334 describes a volume reduction method capable of not only reducing the volume of radioactive organic waste but also reducing the concentration of radioactive substances contained in the radioactive organic waste. .. In the volume reduction method described in JP-A-2015-64334, specifically, a clad (including a radionuclide such as cobalt-60, iron oxide, etc.) contained in radioactive organic waste by an organic acid aqueous solution is used. Is dissolved together with a radionuclide such as cobalt-60, and the radionuclide (cobalt-60, cesium-137, etc.) adsorbed on the radioactive organic waste, for example, the ion exchange resin which is a waste resin, is dissolved in the organic acid salt aqueous solution to the ion exchange resin. Elute from. Further, each of the organic acid contained in the organic acid aqueous solution used for dissolving the clad (iron oxide, etc.) and the organic acid salt contained in the organic acid aqueous solution used for elution of the radioactive nuclei is prepared by ozone or the like. The waste liquid containing the radioactive nuclei, which is decomposed and remains after the decomposition of the organic acid and the organic acid salt, is made into a dry powder, and the obtained powder containing the radioactive nuclei is solidified with a solidifying agent (cement or the like).
　特開２０１９－７０５８１号公報に記載された汚染水処理方法は、汚染水を弱アルカリ性とするｐＨ緩衝工程、及びｐＨ緩衝工程の後に、汚染水に含まれる放射性核種を吸着除去する放射性核種吸着除去工程を含み、放射性核種吸着工程の前に、汚染水に含まれるナトリウムがカルシウムに対して過剰となるように、汚染水の水質を制御する。 The contaminated water treatment method described in JP-A-2019-70581 is a radionuclide adsorption removal method for adsorbing and removing radionuclides contained in contaminated water after a pH buffering step of making the contaminated water weakly alkaline and a pH buffering step. Including the step, before the radionuclide adsorption step, the water quality of the contaminated water is controlled so that the sodium contained in the contaminated water becomes excessive with respect to calcium.
　特開２００２－２５７９８０号公報に記載された核燃料の再処理方法は、フッ化処理工程及び溶媒抽出工程を含んでいる。フッ化処理工程では、原子炉から取り出された使用済燃料集合体に含まれる核燃料物質にフッ素を接触させ、核燃料物質に含まれるウランをフッ素と反応させて揮発性のＵＦ6に変換させる。核燃料物質に含まれるウランの一部もしくは大部分をＵＦ6として揮発除去した後、残ったウラン、及びプルトニウムを、溶媒抽出工程において回収する。溶媒抽出工程は、硝酸を含む溶解液によって残留する核燃料物質を溶解する溶解工程、トリブチルリン酸（ＴＢＰ）を含む抽出液を溶解された核燃料物質を含む溶解液に接触させ、溶解液に含まれるウラン及びプルトニウムを抽出液側に移行させる共除染工程、及び抽出されたウラン及びプルトニウムを含む抽出液を硝酸濃度が低い硝酸水溶液と接触させ、抽出液に含まれるウラン及びプルトニウムを硝酸水溶液側に移行させる逆抽出工程を含んでいる。 The nuclear fuel reprocessing method described in JP-A-2002-257980 includes a fluorination treatment step and a solvent extraction step. In the fluorination treatment step, fluorine is brought into contact with the nuclear fuel material contained in the spent fuel assembly taken out from the nuclear reactor, and uranium contained in the nuclear fuel material is reacted with fluorine to convert it into volatile UF 6. After volatilizing and removing part or most of the uranium contained in the nuclear fuel material as UF 6 , the remaining uranium and plutonium are recovered in the solvent extraction step. The solvent extraction step is a dissolution step of dissolving the remaining nuclear fuel substance by the solution containing nitric acid, and the extract containing tributylphosphate (TBP) is brought into contact with the solution containing the dissolved nuclear fuel substance and contained in the solution. The co-decontamination step of transferring uranium and plutonium to the extract side, and the extracted extract containing uranium and plutonium are brought into contact with a nitrate aqueous solution having a low nitrate concentration, and the uranium and plutonium contained in the extract are moved to the nitrate aqueous solution side. Includes a back-extraction step to transition.
　原子力プラントの原子炉の炉心には、多数の燃料集合体が装荷されている。各燃料集合体は、被覆管内に核燃料物質を充填した複数の燃料棒を有する。炉心には、冷却材、具体的には冷却水が供給され、この冷却水は燃料集合体内の燃料棒内の核燃料物質の核分裂によって発生する熱で加熱される。原子炉内を流れる冷却水の一部は、原子炉冷却材浄化系に設けられる浄化装置に供給され、冷却水に含まれる放射性核種が浄化装置によって除去される。 A large number of fuel assemblies are loaded in the core of the nuclear reactor of a nuclear power plant. Each fuel assembly has a plurality of fuel rods filled with nuclear fuel material in a cladding tube. A coolant, specifically cooling water, is supplied to the core, and the cooling water is heated by the heat generated by the nuclear fission of the nuclear fuel material in the fuel rods in the fuel assembly. A part of the cooling water flowing in the reactor is supplied to a purification device provided in the reactor coolant purification system, and the radionuclides contained in the cooling water are removed by the purification device.
　沸騰水型原子力プラントにおいては、原子炉内の冷却水を供給する原子炉冷却材浄化系の浄化系配管に設けられた浄化装置で、冷却水の浄化が行われる（特開２０１８－４８８３１号公報参照）。その浄化装置の内部には、冷却水を浄化するイオン交換樹脂が存在する。加圧水型原子力プラントにおいても、原子炉内の冷却水を浄化する原子炉冷却材浄化系が設けられ、この原子炉冷却材浄化系には、イオン交換樹脂が内部に存在する浄化装置が設けられる。 In a boiling water reactor, the cooling water is purified by a purification device provided in the purification system piping of the reactor cooling material purification system that supplies the cooling water in the reactor (Japanese Patent Laid-Open No. 2018-48831). reference). Inside the purification device, there is an ion exchange resin that purifies the cooling water. A pressurized water reactor is also provided with a reactor coolant purification system that purifies the cooling water in the reactor, and this reactor coolant purification system is provided with a purification device in which an ion exchange resin is present.
　また、特開２０１４－６６６４７号公報は、放射性物質を含む液を吸着材に接触させることにより、放射性物質を吸着材に吸着させて、さらに吸着材を含む液をクロスフローろ過して、放射性物質を吸着した吸着材と吸着処理後の液を分離する方法が記載する。 Further, Japanese Patent Application Laid-Open No. 2014-66647 describes that a liquid containing a radioactive substance is brought into contact with the adsorbent to adsorb the radioactive substance to the adsorbent, and the liquid containing the adsorbent is cross-flow filtered to obtain the radioactive substance. A method for separating the adsorbent that has adsorbed the above and the liquid after the adsorption treatment is described.
特開２０１５－６４３３４号公報Japanese Unexamined Patent Publication No. 2015-64334 特開２０１９－７０５８１号公報Japanese Unexamined Patent Publication No. 2019-70581 特開２００２－２５７９８０号公報JP-A-2002-257980 特開２０１８－４８８３１号公報Japanese Unexamined Patent Publication No. 2018-48831 特開２０１４－６６６４７号公報Japanese Unexamined Patent Publication No. 2014-66647
　もし、炉心に装荷されている燃料集合体に含まれる燃料棒の被覆管が、万が一、破損した場合には、燃料棒内の核燃料物質、すなわち、ウラン（Ｕ）、アメリシウム（Ａｍ）、プルトニウム（Ｐｕ）、ネプツニウム（Ｎｐ）及びキュリウム（Ｃｍ）等のα核種であるアクチノイドが冷却水中に漏洩する。それらのα核種を含む冷却水が原子炉冷却材浄化系の浄化装置に導かれ、それぞれのα核種がその浄化装置内のイオン交換樹脂によって除去される。α核種の半減期は、超半減期である。 If the cladding of the fuel rods contained in the fuel assembly loaded in the core is damaged, the nuclear fuel materials in the fuel rods, that is, uranium (U), americium (Am), plutonium (Am), plutonium ( Actinides, which are α-nuclear species such as Pu), plutonium (Np) and curium (Cm), leak into the cooling water. The cooling water containing those α-nuclide is guided to the purification device of the reactor coolant purification system, and each α-nuclide is removed by the ion exchange resin in the purification device. The half-life of α-nuclide is the super half-life.
　α核種を吸着している、廃樹脂であるイオン交換樹脂に、特開２０１５－６４３３４号公報に記載されているように、有機酸水溶液及び有機酸塩水溶液を順次接触させて、イオン交換樹脂に含まれているクラッドを溶解し、イオン交換樹脂に吸着されている放射性核種を溶離させる。このとき、そのイオン交換樹脂によって除去されたα核種も、溶離されて有機酸水溶液及び有機酸塩水溶液のそれぞれの中に移行する。 As described in Japanese Patent Application Laid-Open No. 2015-64334, an organic acid aqueous solution and an organic acid salt aqueous solution are sequentially brought into contact with an ion exchange resin, which is a waste resin adsorbing α nuclei, to form an ion exchange resin. The contained clad is dissolved and the radioactive nuclei adsorbed on the ion exchange resin are eluted. At this time, the α-nuclide removed by the ion exchange resin is also eluted and transferred into each of the organic acid aqueous solution and the organic acid salt aqueous solution.
　α核種を含む有機酸水溶液に含まれる有機酸及びα核種を含む有機酸塩水溶液に含まれる有機酸塩を分解して除去し、その後、α核種が残留する水溶液を濃縮すると、超半減期のα核種を含む放射性廃棄物が多量に発生する。超半減期のα核種を含む放射性廃棄物の発生量を低減することが望ましい。 When the organic acid contained in the organic acid aqueous solution containing α-nuclide and the organic acid salt contained in the organic acid salt aqueous solution containing α-nuclide are decomposed and removed, and then the aqueous solution in which α-nuclide remains is concentrated, the super-half-life is achieved. A large amount of radioactive waste containing α-nuclide is generated. It is desirable to reduce the amount of radioactive waste containing α-nuclide with a super half-life.
　特開２０１４－６６６４７号公報に記載された方法では、放射性物質を含む液を吸着材に接触させているが、放射性物質を含む液の水質によっては、吸着材で放射性物質を吸着しても、十分に吸着しきれずに、吸着材を分離した後の液に放射性物質がある程度残ることがある。 In the method described in JP-A-2014-66647, a liquid containing a radioactive substance is brought into contact with the adsorbent. However, depending on the water quality of the liquid containing the radioactive substance, even if the radioactive substance is adsorbed by the adsorbent, the radioactive substance may be adsorbed. Radioactive substances may remain in the liquid after the adsorbent is separated due to insufficient adsorption.
　本発明の目的は、放射性廃液に含まれるα核種を除去するα核種除去装置をコンパクトにできる放射性廃液処理システム及び放射性廃液の処理方法を提供することにある。 An object of the present invention is to provide a radioactive liquid waste treatment system and a method for treating radioactive liquid waste, which can make an α-nuclide removing device for removing α-nuclide contained in radioactive liquid waste compact.
　上記した目的を達成する本発明の特徴は、α核種を含む前記放射性廃液の水質を調整する水質調整装置と、その水質調整装置の下流に配置されて、水質が調整された記放射性廃液が供給されるフィルタとを備えたことにある。 The feature of the present invention that achieves the above-mentioned object is that a water quality adjusting device for adjusting the water quality of the radioactive liquid waste containing α-nuclide and a radioactive waste liquid having the water quality adjusted downstream of the water quality adjusting device are supplied. It is equipped with a filter that is used.
　α核種を含む前記放射性廃液の水質を調整する水質調整装置と、その水質調整装置の下流に配置されて、水質が調整された放射性廃液が供給されるフィルタとを備えているため、水質調整装置によってα核種を含む放射性廃液の水質を調整することにより、放射性廃液内で生成されて析出するα核種のコロイドをフィルタで除去することができ、放射性廃液に含まれるα核種を低減することができる。 A water quality adjusting device for adjusting the water quality of the radioactive effluent containing α-nuclide and a filter arranged downstream of the water quality adjusting device to supply the radioactive effluent having the adjusted water quality. By adjusting the water quality of the radioactive effluent containing α-nuclide, the colloid of α-nuclide generated and precipitated in the radioactive effluent can be removed by a filter, and the α-nuclide contained in the radioactive effluent can be reduced. ..
　好ましくは、フィルタから流出するα核種のイオンを含む放射性廃液が供給されてα核種吸着材が内部に存在し、このα核種吸着材によってα核種のイオンを吸着してα核種のイオンを放射性廃液から除去するα核種除去装置を備えることが望ましい。 Preferably, a radioactive liquid containing α-nuclide ions flowing out of the filter is supplied and an α-nuclide adsorbent exists inside, and the α-nuclide adsorbent adsorbs α-nuclide ions to adsorb α-nuclide ions to the radioactive waste liquid. It is desirable to have an α-nuclide removal device for removing from.
　好ましくは、フィルタから流出するα核種のイオンを含む放射性廃液にα核種吸着材を注入するα核種吸着材注入装置と、α核種のイオンを含む放射性廃液が供給され、内部に存在するα核種吸着材によってα核種のイオンを吸着してα核種のイオンを放射性廃液から除去するα核種除去装置とを備えることが望ましい。 Preferably, an α-nuclide adsorbent injection device that injects an α-nuclide adsorbent into a radioactive liquid containing α-nuclide ions flowing out of the filter, and an α-nuclide adsorbing device that is supplied with a radioactive liquid containing α-nuclide ions and exists inside. It is desirable to provide an α-nuclide removing device that adsorbs α-nuclide ions by the material and removes α-nuclide ions from the radioactive liquid waste liquid.
　上記した目的は、α核種を含む放射性廃液にｐＨ調整剤を注入して放射性廃液内でα核種のコロイドを生成し、生成されたα核種のコロイドをフィルタによって除去することによっても達成できる。 The above-mentioned purpose can also be achieved by injecting a pH adjuster into a radioactive liquid containing α-nuclide to generate a colloid of α-nuclide in the radioactive liquid waste, and removing the produced colloid of α-nuclide with a filter.
　本発明によれば、放射性廃液に含まれるα核種を除去するα核種除去装置をコンパクト化することができる。 According to the present invention, it is possible to make the α-nuclide removing device for removing the α-nuclide contained in the radioactive liquid waste compact.
本発明の好適な一実施例である、沸騰水型原子力プラントで発生する放射性有機廃棄物の処理に適用される実施例１の放射性廃液の処理方法の手順を示すフローチャートである。It is a flowchart which shows the procedure of the radioactive waste liquid treatment method of Example 1 applied to the treatment of the radioactive organic waste generated in the boiling water type nuclear power plant which is a preferable example of this invention. 実施例１の放射性廃液の処理方法を実行する放射性廃液処理システムの一例の構成図である。It is a block diagram of an example of the radioactive waste liquid treatment system which carries out the radioactive liquid waste treatment method of Example 1. FIG. 図２に示す廃液分解装置の詳細構成図である。It is a detailed block diagram of the waste liquid decomposition apparatus shown in FIG. 図２に示す水質調整装置及びα核種除去装置の詳細構成図である。It is a detailed block diagram of the water quality adjustment device and the α-nuclide removal device shown in FIG. 図４に示す水質調整装置の他の例の詳細構成図である。It is a detailed block diagram of another example of the water quality adjustment apparatus shown in FIG. 放射性廃液に含まれるα核種の除去方法に対応した、放射性廃液内のα核種の残留率を示す説明図である。It is explanatory drawing which shows the residual rate of the α-nuclide in the radioactive liquid waste corresponding to the method of removing the α-nuclide contained in the radioactive liquid waste. 放射性廃液の酸化還元電位による放射性廃液内のα核種の残留率への影響を示す説明図である。It is explanatory drawing which shows the influence on the residual rate of α nuclide in the radioactive liquid waste by the redox potential of the radioactive liquid waste. 放射性廃液の溶存炭酸ガス濃度による放射性廃液内のα核種の残留率への影響を示す説明図である。It is explanatory drawing which shows the influence on the residual rate of α nuclide in the radioactive liquid waste by the dissolved carbon dioxide gas concentration of the radioactive waste liquid. 吸着材による放射性廃液内のα核種の残留率への影響を示す説明図である。It is explanatory drawing which shows the influence on the residual rate of α nuclide in a radioactive liquid waste by an adsorbent. α核種吸着材のサイズによるα核種の吸着量の違いを示す説明図である。It is explanatory drawing which shows the difference of the adsorption amount of α nuclide by the size of α nuclide adsorbent.
　放射性有機廃棄物である陽イオン交換樹脂に吸着されているα核種を含む放射性核種の脱離によって発生した、α核種を含む放射性廃液にｐＨ調整剤を注入し、α核種及びｐＨ調整剤を含む放射性廃液をα核種吸着材を有するα核種除去装置に供給し、α核種除去装置内でα核種吸着材によって放射性廃液に含まれるα核種を除去する放射性廃液の処理方法が、特願２０１８－２１０３１５号（出願日：２０１８年１１月８日）によって提案されている。発明者は、特願２０１８－２１０３１５号で提案された放射性廃液の処理方法を詳細に検討した。この結果、発明者は、その放射性廃液の処理方法において、放射性廃液に含まれるα核種を除去するために多量のα核種吸着材が必要となり、α核種除去装置が大型化するという課題が存在することを認識した。α核種吸着材としては、例えば、フェライト（Ｆｅ3Ｏ4）及び活性炭等を使用することができる。なお、フェライト及び活性炭に限らず、α核種を吸着できる吸着材であれば、α核種吸着材として使用できる。 A pH adjuster is injected into a radioactive liquid solution containing α nuclides generated by desorption of radio nuclides containing α nuclides adsorbed on a cation exchange resin which is a radioactive organic waste, and contains α nuclides and a pH adjuster. Japanese Patent Application No. 2018-210315 is a method for treating radioactive effluent by supplying radioactive effluent to an α-nuclide removing device having an α-nuclide adsorbent and removing α-nuclide contained in the radioactive effluent with the α-nuclide adsorbent in the α-nuclide removing device. Proposed by issue (Filing date: November 8, 2018). The inventor examined in detail the method for treating radioactive liquid waste proposed in Japanese Patent Application No. 2018-210315. As a result, the inventor needs a large amount of α-nuclide adsorbent in order to remove α-nuclide contained in the radioactive liquid waste in the method for treating the radioactive liquid waste, and there is a problem that the α-nuclide removing device becomes large in size. I realized that. As the α-nuclide adsorbent, for example, ferrite (Fe 3 O 4 ), activated carbon, or the like can be used. Not limited to ferrite and activated carbon, any adsorbent capable of adsorbing α-nuclide can be used as an α-nuclide adsorbent.
　発明者らは、α核種除去装置をコンパクトにするために、どのようにすればα核種除去装置内のα核種吸着材の量を減少できるかについて種々の検討を行った。 The inventors conducted various studies on how to reduce the amount of α-nuclide adsorbent in the α-nuclide removing device in order to make the α-nuclide removing device compact.
　特願２０１８－２１０３１５号では、α核種吸着材としてフェライト（Ｆｅ3Ｏ4）を使用し、α核種除去装置内にフェライト粒子を充填した３つのフェライト層を形成している。上流のフェライト層から下流のフェライト層に向かうほど、フェライト粒子の粒径が小さくなっている。このように、特願２０１８－２１０３１５号で用いられるα核種除去装置は、内部に３つのフェライト層を有しており、多量のフェライトを使用している。 In Japanese Patent Application No. 2018-210315, ferrite (Fe 3 O 4 ) is used as the α-nuclide adsorbent, and three ferrite layers filled with ferrite particles are formed in the α-nuclide removing device. The particle size of the ferrite particles becomes smaller from the upstream ferrite layer to the downstream ferrite layer. As described above, the α-nuclide removing device used in Japanese Patent Application No. 2018-210315 has three ferrite layers inside and uses a large amount of ferrite.
　発明者による検討の結果、放射性廃液に含まれるα核種であるウラン、プルトニウム及びネプチニウムは、放射性廃液のｐＨを８未満にすることによってコロイドになり、粒径が大きくなることが判明した。このため、発明者は、コロイドになって粒径が大きくなったα核種（例えば、ウラン、プルトニウム及びネプチニウム）をα核種除去装置の上流で除去すれば、α核種除去装置に供給されるα核種の量が減少し、α核種除去装置内のα核種吸着材の量を減少できるのではと考えた。フィルタをα核種除去装置の上流に配置することによってコロイドになったα核種を除去することができ、α核種除去装置に供給されるα核種の量を減少させることが可能になる。 As a result of the examination by the inventor, it was found that the α-nuclides uranium, plutonium and neptinium contained in the radioactive liquid waste become colloids and the particle size becomes large when the pH of the radioactive liquid waste is set to less than 8. Therefore, if the inventor removes α-nuclides (for example, uranium, plutonium, and neptinium) that have become colloidal and have a large particle size upstream of the α-nuclide removing device, the α-nuclide supplied to the α-nuclide removing device. It was thought that the amount of α-nuclide adsorbent in the α-nuclide removal device could be reduced by reducing the amount of α-nuclide. By arranging the filter upstream of the α-nuclide removing device, the colloidal α-nuclide can be removed, and the amount of α-nuclide supplied to the α-nuclide removing device can be reduced.
　発明者は、放射性廃液に含まれるα核種の除去がその放射性廃液の水質によって受ける影響を検討した。 The inventor examined the effect of the removal of α-nuclide contained in radioactive liquid waste by the water quality of the radioactive liquid waste.
　α核種を含む放射性廃液へのアルカリ（例えば、水酸化ナリウム）の注入を行うことによって放射性廃液の水質調整を行うことにより、放射性廃液に含まれるα核種のうちＵ（ウラン）、Ｐｕ（プルトニウム）及びＮｐ（ネプツニウム）のそれぞれの化学形態をコロイドにすることができる。粒径が大きいコロイドになったＵ、Ｐｕ及びＮｐのそれぞれは、フィルタで捕捉することができ、放射性廃液から除去することができる。その放射性廃液の水質調整のために、アルカリと共に、酸、水質調整用の酸化剤（以下、水質調整用酸化剤という）及び還元剤の少なくとも１つを注入してもよい。 U (uranium) and Pu (plutonium) among the α nuclei contained in the radioactive effluent by adjusting the water quality of the radioactive effluent by injecting alkali (for example, nalium hydroxide) into the radioactive effluent containing the α nuclei. And each chemical form of Np (plutonium) can be colloidal. Each of U, Pu and Np, which have become colloids having a large particle size, can be captured by a filter and removed from the radioactive liquid waste. In order to adjust the water quality of the radioactive liquid waste, at least one of an acid, an oxidizing agent for adjusting the water quality (hereinafter referred to as an oxidizing agent for adjusting the water quality) and a reducing agent may be injected together with the alkali.
　アルカリとしては水酸化ナトリウム、水酸化カリウム、水酸化カルシウム及び炭酸ナトリウムのいずれかを用いる。酸としては、例えば、希硝酸、希硫酸及び希塩酸等が用いられる。水質調整用酸化剤としては有機酸及び有機酸塩のいずれかを用いる。還元剤としては、例えば、ヒドラジン、ホルムヒドラジン、ヒドラジンカルボアミド及びカルボヒドラジド等のヒドラジン誘導体、ヒドロキシルアミン、アスコルビン酸及び亜硫酸塩のいずれかが用いられる。特に、アスコルビン酸及び亜硫酸塩は、還元剤ではあるが、酸化還元電位調整剤と称する。酸化還元電位調整剤は弱酸性である。上記の還元剤のうち酸化還元電位調整剤以外の還元剤は、弱アルカリ性であり、便宜的に、アルカリ性還元剤という。「還元剤」との表現は、酸化還元電位調整剤及びアルカリ性還元剤を含む。 As the alkali, any one of sodium hydroxide, potassium hydroxide, calcium hydroxide and sodium carbonate is used. As the acid, for example, dilute nitric acid, dilute sulfuric acid, dilute hydrochloric acid and the like are used. As the oxidizing agent for water quality adjustment, either an organic acid or an organic acid salt is used. As the reducing agent, for example, any one of hydrazine derivatives such as hydrazine, formhydrazine, hydrazinecarbamide and carbhydrazide, hydroxylamine, ascorbic acid and sulfites is used. In particular, ascorbic acid and sulfites are called redox potential regulators, although they are reducing agents. The redox potential modifier is weakly acidic. Among the above-mentioned reducing agents, the reducing agents other than the oxidation-reduction potential adjusting agent are weakly alkaline and are referred to as alkaline reducing agents for convenience. The expression "reducing agent" includes a redox potential modifier and an alkaline reducing agent.
　ｐＨ調整剤のうち酸、水質調整用酸化剤及び酸化還元電位調整剤は放射性廃液を酸性にする作用を有し、アルカリ及びアルカリ性還元剤は放射性廃液をアルカリ性にする作用を有する。放射性廃液の酸化還元電位を調整するためには、酸化還元電位調整剤を用いることが望ましい。 Of the pH adjusters, acids, water quality adjusting oxidizing agents and oxidation-reduction potential adjusting agents have the effect of acidifying the radioactive waste liquid, and alkaline and alkaline reducing agents have the effect of making the radioactive waste liquid alkaline. In order to adjust the redox potential of the radioactive liquid waste, it is desirable to use an oxidation-reduction potential modifier.
　α核種を含む放射性廃液の水質を上記のように調整して水質が調整された放射性廃液をフィルタに供給し、フィルタを通過した放射性廃液に残留しているα核種の割合を調べた。フィルタに流入する前の放射性廃液に含まれているα核種の量に対する、フィルタから流出した放射性廃液に含まれるα核種の割合を、α核種の残留率という。α核種のうちＵ、Ｐｕ及びＮｐは、放射性廃液の水質調整により、粒径の大きなコロイドになるため、フィルタによって除去することが可能になる。 The water quality of the radioactive effluent containing α-nuclide was adjusted as described above, the radioactive effluent with the adjusted water quality was supplied to the filter, and the proportion of α-nuclide remaining in the radioactive effluent that passed through the filter was investigated. The ratio of α-nuclide contained in the radioactive liquid waste discharged from the filter to the amount of α-nuclide contained in the radioactive liquid waste before flowing into the filter is called the residual ratio of α-nuclide. Of the α nuclides, U, Pu and Np become colloids having a large particle size by adjusting the water quality of the radioactive liquid waste, and can be removed by a filter.
　Ｕ、Ｐｕ及びＮｐを含む放射性廃液を上記のように水質調整を行い、フィルタによって除去される割合への、放射性廃液のｐＨによる影響を調べた。図６に、Ｕ、Ｐｕ及びＮｐのうち代表としてＵに及ぼすｐＨの影響を示した。フィルタから排出された放射性廃液におけるＵの残留率は、図６に基づいて、アルカリ性（ｐＨ９）で最も大きくなり、中性（ｐＨ７）及び酸性（ｐＨ４）で小さくなることが分った。放射性廃液のｐＨを７以下にすれば、フィルタによるＵの除去率が高くなり、フィルタから排出された放射性廃液におけるＵの残留率が小さくなる。一方で、放射性廃液のｐＨを９以上にすればフィルタによるＵの除去率が小さくなり、フィルタから排出された放射性廃液におけるＵの残留率が大きくなることが確認できた。Ｐｕ及びＮｐにおいても、Ｕと同様な傾向がみられた。これは、Ｕ、Ｐｕ及びＮｐが放射性廃液のｐＨによってそれぞれの粒径を変化させていることを示している。 The water quality of the radioactive liquid waste containing U, Pu and Np was adjusted as described above, and the effect of the pH of the radioactive liquid waste on the ratio of the radioactive liquid waste removed by the filter was investigated. FIG. 6 shows the effect of pH on U as a representative of U, Pu and Np. Based on FIG. 6, the residual rate of U in the radioactive liquid discharged from the filter was found to be the largest in alkaline (pH 9) and smaller in neutral (pH 7) and acidic (pH 4). When the pH of the radioactive liquid waste is set to 7 or less, the removal rate of U by the filter becomes high, and the residual rate of U in the radioactive liquid discharged from the filter becomes small. On the other hand, it was confirmed that when the pH of the radioactive waste liquid was set to 9 or more, the removal rate of U by the filter decreased, and the residual rate of U in the radioactive liquid discharged from the filter increased. Similar trends to U were observed in Pu and Np. This indicates that U, Pu and Np change their respective particle sizes depending on the pH of the radioactive liquid waste.
　さらに、発明者は、ｐＨ７からｐＨ９の間において、放射性廃液のｐＨの、フィルタによるＵ、Ｐｕ及びＮｐのそれぞれの除去に与える影響についても調べた。この結果、放射性廃液のｐＨが８未満の領域では、フィルタによるＵ、Ｐｕ及びＮｐのそれぞれの除去率が高くなった。放射性廃液のｐＨが８以上になると、Ｕ、Ｐｕ及びＮｐのそれぞれがイオンになるため、Ｕ、Ｐｕ及びＮｐのそれぞれをフィルタで除去することができなくなった。また、放射性廃液のｐＨが４未満になると、放射性廃液内に生成されたα核種のコロイドが溶解し、フィルタで除去することができなくなる。このため、放射性廃液のｐＨは、４以上８未満（４≦ｐＨ＜８）の範囲にすることが望ましい。 Furthermore, the inventor also investigated the effect of the pH of the radioactive liquid waste on the removal of U, Pu and Np by the filter between pH 7 and pH 9. As a result, in the region where the pH of the radioactive liquid waste was less than 8, the removal rates of U, Pu and Np by the filter were high. When the pH of the radioactive liquid waste becomes 8 or more, each of U, Pu and Np becomes an ion, so that each of U, Pu and Np cannot be removed by a filter. Further, when the pH of the radioactive liquid waste is less than 4, the colloid of the α-nuclide generated in the radioactive liquid waste dissolves and cannot be removed by the filter. Therefore, it is desirable that the pH of the radioactive liquid waste be in the range of 4 or more and less than 8 (4 ≦ pH <8).
　放射性廃液のｐＨを６にした状態で、放射性廃液の酸化還元電位を、図７に示すように、「－０．５Ｖ」、「０Ｖ」及び「０．２Ｖ」に変化させた場合には、放射性廃液に含まれるα核種を、さらに、効率良く放射性廃液から除去することができ、フィルタから排出された放射性廃液におけるα核種の残留率は、酸化還元電位が低くなるほど、小さくなる。さらに、図８に示すように、放射性廃液の溶存炭酸濃度を低減すると、さらに、フィルタから排出された放射性廃液におけるα核種の残留率を低減できる。放射性廃液の溶存炭酸濃度が低くなるほど、その放射性廃液におけるα核種の残留率は低くなる。なお、溶存炭酸濃度の低減には、脱溶存炭酸剤、例えば、亜硫酸ナトリウム、Ｎ２（窒素）ガス、Ａｒガスのいずれかを放射性廃液に注入すると良い。 When the oxidation-reduction potential of the radioactive liquid is changed to "-0.5V", "0V" and "0.2V" as shown in FIG. 7 while the pH of the radioactive liquid is set to 6. The α-nuclide contained in the radioactive effluent can be more efficiently removed from the radioactive effluent, and the residual rate of the α-nuclide in the radioactive effluent discharged from the filter becomes smaller as the oxidation-reduction potential becomes lower. Further, as shown in FIG. 8, if the dissolved carbonic acid concentration of the radioactive liquid waste is reduced, the residual rate of α-nuclide in the radioactive liquid waste discharged from the filter can be further reduced. The lower the dissolved carbonic acid concentration of the radioactive liquid waste, the lower the residual rate of α-nuclide in the radioactive liquid waste. In order to reduce the dissolved carbon dioxide concentration, it is advisable to inject any of a dissolved carbonic acid, for example, sodium sulfite, N 2 (nitrogen) gas, and Ar gas into the radioactive liquid waste.
　放射性廃液に含まれるＵ、Ｐｕ及びＮｐ以外の他のα核種（例えば、アメリシウム、キュリウム等の溶解性のα核種）については、放射性廃液の水質調整を行っても、コロイドが成長しないため、フィルタで除去することができない。このため、アメリシウム及びキュリウムは、フィルタの下流に配置されたα核種除去装置内に存在するα核種吸着材に吸着させて除去する。 For α-nuclides other than U, Pu and Np contained in the radioactive effluent (for example, soluble α-nuclides such as americium and curium), even if the water quality of the radioactive effluent is adjusted, colloids do not grow, so filters are used. Cannot be removed with. Therefore, americium and curium are removed by adsorbing to an α-nuclide adsorbent existing in the α-nuclide removing device arranged downstream of the filter.
　水質調整工程で水質が調整された、放射性核種を含む放射性廃液をフィルタに通水した後、放射性廃液にα核種吸着材を注入することにより、α核種除去装置内で、アメリシウム及びキュリウム等の溶解性のα核種のイオン除去工程Ｓ７が実施される。α核種吸着材としては、フェライト（Ｆｅ3Ｏ4）、キレート樹脂、活性炭、オキシン添着活性炭、ゼオライト、チタン酸及びフェロシアン化物のいずれかが用いられる。 After passing the radioactive effluent containing radionuclides, whose water quality was adjusted in the water quality adjustment step, through the filter, the α-nuclide adsorbent is injected into the radioactive effluent to dissolve amerythium, curium, etc. in the α-nuclide removal device. The ion removal step S7 of the sex α-nuclide is carried out. As the α-nuclide adsorbent, any one of ferrite (Fe 3 O 4 ), chelate resin, activated carbon, oxine-impregnated activated carbon, zeolite, titanic acid and ferrocyanide is used.
　発明者は、放射性廃液に含まれるα核種の除去に関する実験を行った。この結果を、図９を用いて説明する。図９は、放射性廃液に含まれるα核種の２つの除去方法で或る方法「Ａ」及び方法「Ｂ」のそれぞれに対する、フィルタから排出された放射性廃液におけるα核種の残留率を示している。 The inventor conducted an experiment on the removal of α-nuclide contained in radioactive liquid waste. This result will be described with reference to FIG. FIG. 9 shows the residual ratio of α-nuclide in the radioactive liquid waste discharged from the filter for each of a certain method “A” and method “B” in the two methods for removing α-nuclide contained in the radioactive liquid waste.
　図９に示す方法「Ａ」は、陽イオン交換樹脂に吸着されたα核種、例えば、ウラン及びやアメリシウムを含む有機酸塩水溶液であるシュウ酸アンモニア水溶液により溶離させ、シュウ酸アンモニア水溶液に含まれるシュウ酸アンモニアをオゾンで分解し、溶離したアメリシウム（濃度はｐｐｂオーダー）を除去しないで（未処理の状態で）、アメリシウムを含む水をそのまま排出したケースである。このため、方法「Ａ」では、排出される水のウラン残留率（α核種の残留率）は１００％である。 The method "A" shown in FIG. 9 is eluted with an aqueous solution of ammonia oxalate, which is an aqueous organic acid salt solution containing an α-nucleus species adsorbed on a cation exchange resin, for example, uranium and americium, and is contained in the aqueous solution of ammonia oxalate. This is a case where ammonia oxalate is decomposed with ozone and the eluted water (concentration is on the order of ppb) is not removed (in an untreated state), and water containing americium is discharged as it is. Therefore, in the method "A", the uranium residual rate (residual rate of α-nuclide) of the discharged water is 100%.
　図９に示す方法「Ｂ」は、溶離したウラン及びアメリシウムを含むシュウ酸アンモニア水溶液のシュウ酸アンモニアをオゾンで分解し、この分解で生成されるウラン及びアメリシウムを含む水に、水の水質を調整するアルカリ性還元剤であるヒドラジンを注入してその水のｐＨを４以上８未満の範囲内の５に調節し、ｐＨが５である、ウランやアメリシウムを含む水にフェライト（Ｆｅ3Ｏ4）を注入したケースである。方法「Ｂ」における、フェライトを供給する前の水のウラン及びアメリシウムの濃度は、方法「Ａ」における水のアメリシウム濃度と同じである。方法「Ｂ」では、アメリシウム残留率（α核種の残留率）は、約６．７％となり、その残留率は方法「Ａ」の約１／１５になる。 The method "B" shown in FIG. 9 decomposes ammonia oxalate in an aqueous solution of ammonia oxalate containing eluted uranium and americium with ozone, and adjusts the water quality to water containing uranium and americium produced by this decomposition. Hydrazin, which is an alkaline reducing agent, is injected to adjust the pH of the water to 5 in the range of 4 or more and less than 8, and ferrite (Fe 3 O 4 ) is added to water containing uranium or americium having a pH of 5. This is the case of injection. The concentration of uranium and americium in the water before supplying ferrite in the method "B" is the same as the concentration of americium in the water in the method "A". In the method "B", the residual rate of americium (residual rate of α-nuclide) is about 6.7%, and the residual rate is about 1/15 of that of the method "A".
　したがって、有機酸塩分解後のα核種を含む水にｐＨ調整剤を注入してその水のｐＨを４以上８未満の範囲に調節し、ｐＨが調節された、α核種を含む水にフェライトを供給することによって、その水に含まれるα核種を著しく除去できることが分かった。なお、ｐＨ調整剤としては、酸、水質調整用酸化剤、還元剤及びアルカリが用いられる。 Therefore, a pH adjuster is injected into water containing α-nuclide after decomposition of an organic acid salt to adjust the pH of the water to a range of 4 or more and less than 8, and ferrite is added to the pH-adjusted water containing α-nuclide. It was found that by supplying the water, the α-nuclide contained in the water can be significantly removed. As the pH adjusting agent, an acid, an oxidizing agent for adjusting water quality, a reducing agent and an alkali are used.
　前述のように、α核種吸着材を放射性廃液に注入するので、α核種吸収材の粒子を細かくすることができ、α核種吸収剤の比表面積を増加させることが可能になる。また、α核種吸着材を放射性廃液に注入することにより、α核種吸着材が放射性廃液に浸漬される時間を制御することが可能になる。これにより、所望のα核種吸着量となる時間までα核種吸着材を放射性廃液に浸漬させるように、制御することができる。 As described above, since the α-nuclide adsorbent is injected into the radioactive liquid waste liquid, the particles of the α-nuclide absorber can be made finer, and the specific surface area of the α-nuclide absorber can be increased. Further, by injecting the α-nuclide adsorbent into the radioactive waste liquid, it becomes possible to control the time during which the α-nuclide adsorbent is immersed in the radioactive waste liquid. Thereby, it is possible to control so that the α-nuclide adsorbent is immersed in the radioactive liquid waste until the time when the desired amount of α-nuclide is adsorbed.
　したがって、α核種吸着材のα核種除去性能を向上して、α核種を含む放射性廃棄物の発生量をさらに低減することができる。 Therefore, it is possible to improve the α-nuclide removal performance of the α-nuclide adsorbent and further reduce the amount of radioactive waste containing the α-nuclide.
　そして、α核種吸収材をα核種除去装置内に充填して、α核種除去装置内にα核種吸着材の層を形成した構成と比較しても、α核種吸着材を放射性廃液に注入する場合は、α核種の除去性能が向上して、α核種を含む放射性廃棄物の発生量を低減することが可能になる。 Then, even when compared with the configuration in which the α-nuclide absorber is filled in the α-nuclide removing device and the layer of the α-nuclide adsorbent is formed in the α-nuclide removing device, the α-nuclide adsorbent is injected into the radioactive liquid waste liquid. Improves the removal performance of α-nuclide and makes it possible to reduce the amount of radioactive waste containing α-nuclide.
　α核種吸着材、特に上記のフェライトは、α核種を吸着する性能（吸着性能）が、放射性廃液のｐＨ及び酸化還元電位（Ｅｈ）によって変化する。このため、放射性廃液のｐＨを、ｐＨ調整剤の注入により、前述の４以上８未満の範囲内のｐＨにし、放射性廃液の酸化還元電位を、酸化還元電位調整剤の注入により、特定の酸化還元電位の範囲内にすれば、α核種吸着材の吸着性能を十分に発揮することができる。 The α-nuclide adsorbent, especially the above-mentioned ferrite, has the ability to adsorb α-nuclide (adsorption performance), which changes depending on the pH of the radioactive liquid waste and the oxidation-reduction potential (Eh). Therefore, the pH of the radioactive effluent is set to a pH within the range of 4 or more and less than 8 by injecting a pH adjusting agent, and the redox potential of the radioactive effluent is set to a specific redox by injecting an oxidation-reduction potential adjusting agent. If it is within the range of the potential, the adsorption performance of the α-nuclide adsorbent can be sufficiently exhibited.
　そして、上述した放射性廃液処理システムにおいて、特に、水質調整装置がα核種を含む放射性廃液にｐＨ及び還元酸化電位調整剤を注入する構成としたときには、放射性廃液のｐＨ及び酸化還元電位を調整することができ、放射性廃液のｐＨ及び酸化還元電位を、α核種吸着材の吸着性能を十分に発揮できる特定のｐＨ及び酸化還元電位の範囲内にできる。 Then, in the above-mentioned radioactive liquid waste treatment system, particularly when the water quality adjusting device is configured to inject a pH and reduction oxidation potential adjusting agent into the radioactive liquid containing α-nuclide, the pH and oxidation-reduction potential of the radioactive liquid are adjusted. The pH and oxidation-reduction potential of the radioactive liquid waste can be set within the range of a specific pH and oxidation-reduction potential at which the adsorption performance of the α-nuclide adsorbent can be sufficiently exhibited.
　これにより、放射性廃液に含まれる超半減期のα核種がα核種吸着材によって除去されやすくなり、α核種を除去した後の放射性廃液に含まれるα核種が著しく低減されるため、α核種を吸着した使用済α核種吸着材の量が少なくなる。その結果、α核種を含む放射性廃棄物の発生量を低減できる。 This makes it easier for the α-nuclide adsorbent to remove the α-nuclide with a super half-life contained in the radioactive effluent, and the α-nuclide contained in the radioactive effluent after removing the α-nuclide is significantly reduced, so that the α-nuclide is adsorbed. The amount of used α-nuclide adsorbent used is reduced. As a result, the amount of radioactive waste containing α-nuclide can be reduced.
　以上に述べた、放射性廃液の水質調整を実施してα核種を粒径の大きなコロイドを生成し、このコロイドを含む放射性廃液をフィルタに通水し、フィルタによってα核種、特に、Ｕ，Ｐｕ及びＮｐの前述のコロイドを除去することによってフィルタから排出された放射性廃液に含まれるα核種を低減するという放射性廃液の処理方法に基づいて創成された本発明の実施例を以下に説明する。 The above-mentioned water quality adjustment of the radioactive effluent is carried out to generate a colloid having a large particle size for the α nuclide, and the radioactive effluent containing this colloid is passed through the filter, and the α nuclide, particularly U, Pu and An embodiment of the present invention created based on a method for treating radioactive effluent, which reduces α-nuclide contained in the radioactive effluent discharged from the filter by removing the above-mentioned colloid of Np, will be described below.
　本発明の好適な一実施例である実施例１の放射性廃液の処理方法を、図１ないし図４を用いて説明する。本実施例は、沸騰水型原子力プラントで発生する放射性有機廃棄物の処理を行う放射性廃液の処理方法である。 The method for treating the radioactive liquid waste of Example 1, which is a preferred embodiment of the present invention, will be described with reference to FIGS. 1 to 4. This embodiment is a method for treating radioactive liquid waste that treats radioactive organic waste generated in a boiling water reactor.
　まず、図１を参照して、本実施例の放射性廃液の処理方法の概要を説明する。図１は、実施例１の放射性廃液の処理方法の手順を示すフローチャートである。 First, the outline of the radioactive liquid waste treatment method of this embodiment will be described with reference to FIG. FIG. 1 is a flowchart showing a procedure of a method for treating radioactive liquid waste according to Example 1.
　原子力プラント、例えば、運転を経験している沸騰水型原子力プラントの原子炉圧力容器内の炉心に装荷された燃料集合体、または燃料貯蔵プールに保管された使用済燃料集合体に含まれる燃料棒の被覆管が、万が一、破損した場合には、燃料棒内の核燃料物質（α核種であるウラン、プルトニウム、ネプツニウム及びキュリウム等を含む）が、原子炉圧力容器内の冷却水中、または燃料貯蔵プール内の冷却水中に漏洩する。そして、原子炉圧力容器内の冷却水中に漏洩したα核種は、原子炉冷却材浄化系の浄化装置内のイオン交換樹脂によって除去される。また、燃料貯蔵プール内の冷却水中に漏洩したα核種は、燃料プール冷却材浄化系の浄化装置内のイオン交換樹脂によって除去される。 Fuel rods contained in a nuclear plant, for example, a fuel assembly loaded in the core of a reactor pressure vessel of a boiling water nuclear plant that is experiencing operation, or a spent fuel assembly stored in a fuel storage pool. In the unlikely event that the cladding tube is damaged, the nuclear fuel material (including α nuclei such as uranium, plutonium, neptunium and curium) in the fuel rod will be removed from the cooling water in the reactor pressure vessel or the fuel storage pool. Leaks into the cooling water inside. Then, the α-nuclide leaked into the cooling water in the reactor pressure vessel is removed by the ion exchange resin in the purification device of the reactor cooling material purification system. Further, the α-nuclide leaked into the cooling water in the fuel storage pool is removed by the ion exchange resin in the purification device of the fuel pool cooling material purification system.
　沸騰水型原子力プラントの原子炉冷却材浄化系及び燃料プール冷却材浄化系等から発生する、セルロース系のろ過助材、イオン交換樹脂等を含むフィルタスラッジ（放射性有機廃棄物）は、高線量樹脂貯蔵タンクに長期間に亘って貯蔵される。その高線量樹脂貯蔵タンク内に貯蔵されている放射性有機廃棄物は、所定の貯蔵期間が経過した後、高線量樹脂貯蔵タンクから取り出される。 Filter sludge (radioactive organic waste) containing cellulosic filtration aids, ion exchange resins, etc. generated from the reactor coolant purification system and fuel pool coolant purification system of boiling water reactors is a high-dose resin. It is stored in a storage tank for a long period of time. The radioactive organic waste stored in the high-dose resin storage tank is taken out from the high-dose resin storage tank after a predetermined storage period has elapsed.
　高線量樹脂貯蔵タンクから取り出された、陽イオン交換樹脂を含む放射性有機廃棄物に対して、第一洗浄工程（クラッド溶解工程）Ｓ１が実施される。この第一洗浄工程Ｓ１では、還元性のある有機酸の水溶液（例えば、シュウ酸水溶液）が放射性有機廃棄物に接触され、その水溶液に含まれるその有機酸によって、放射性有機廃棄物に含まれる鉄酸化物などのクラッドが溶解される。クラッドに含まれているコバルト６０等の放射性核種は、クラッドの溶解によって有機酸水溶液中に移行する。 The first cleaning step (clad dissolution step) S1 is carried out on the radioactive organic waste containing the cation exchange resin taken out from the high-dose resin storage tank. In this first cleaning step S1, an aqueous solution of a reducing organic acid (for example, an aqueous solution of oxalic acid) is brought into contact with the radioactive organic waste, and the organic acid contained in the aqueous solution causes iron contained in the radioactive organic waste. Clads such as oxides are dissolved. Radionuclides such as cobalt-60 contained in the clad are transferred into the organic acid aqueous solution by dissolving the clad.
　第一洗浄工程Ｓ１において有機酸を用いる理由は、有機酸の主たる構成元素が炭素、水素、酸素及び窒素であるため、第一洗浄工程Ｓ１において発生する洗浄廃液である有機酸水溶液を、例えば、オゾンを用いて酸化処理（後述の廃液分解工程Ｓ４）をしたときに、廃液中に不揮発性の残渣を生じないからである。有機酸としては、例えば、ギ酸、シュウ酸、酢酸またはクエン酸を用いることが望ましい。 The reason why the organic acid is used in the first cleaning step S1 is that the main constituent elements of the organic acid are carbon, hydrogen, oxygen and nitrogen, so that the organic acid aqueous solution which is the cleaning waste liquid generated in the first cleaning step S1 is used, for example. This is because no non-volatile residue is generated in the waste liquid when the oxidation treatment (the waste liquid decomposition step S4 described later) is performed using ozone. As the organic acid, for example, formic acid, oxalic acid, acetic acid or citric acid is preferably used.
　第一洗浄工程Ｓ１において発生する、クラッドの溶解成分を含む、洗浄廃液である有機酸水溶液（クラッド溶解液）に対して、廃液分解工程Ｓ４が実施される。この廃液分解工程（有機酸及び有機酸塩のいずれかの分解工程）Ｓ４では、過酸化水素またはオゾン等の分解用の酸化剤（以下、分解用酸化剤という）が有機酸水溶液中に曝気され、その分解用酸化剤の酸化作用により有機酸が分解される。 The waste liquid decomposition step S4 is carried out on the organic acid aqueous solution (clad solution) which is the cleaning waste solution containing the clad dissolving component generated in the first cleaning step S1. In this waste liquid decomposition step (decomposition step of either organic acid or organic acid salt) S4, an oxidizing agent for decomposition such as hydrogen peroxide or ozone (hereinafter referred to as a decomposition oxidizing agent) is exposed to the organic acid aqueous solution. , The organic acid is decomposed by the oxidizing action of the oxidizing agent for decomposition.
　第一洗浄工程Ｓ１が施されて、クラッドが溶解された放射性有機廃棄物に対して、第二洗浄工程（放射性核種溶離工程）Ｓ２が実施される。この第二洗浄工程Ｓ２では、有機酸塩水溶液が、クラッドが溶解された放射性有機廃棄物に接触され、その水溶液に含まれる有機酸塩によって、放射性有機廃棄物に吸着されたα核種等の放射性核種が溶離される。 The first cleaning step S1 is performed, and the second cleaning step (radionuclide elution step) S2 is carried out on the radioactive organic waste in which the clad is dissolved. In this second cleaning step S2, the organic acid salt aqueous solution is brought into contact with the radioactive organic waste in which the clad is dissolved, and the radioactive acid such as α nuclei adsorbed on the radioactive organic waste by the organic acid salt contained in the aqueous solution is radioactive. The nuclei are eluted.
　第二洗浄工程Ｓ２で使用される有機酸塩は、水溶液中で解離し、水素イオンよりも陽イオン交換樹脂に吸着されやすい陽イオンを生じる有機酸塩であることが望ましい。すなわち、有機酸塩は、その主たる構成元素が炭素、水素、酸素及び窒素であって、第二洗浄工程Ｓ２の終了後において洗浄廃液である有機酸塩水溶液を、例えば、オゾンを用いて酸化処理（廃液分解工程Ｓ４）をしたときに、廃液中に不揮発性の残渣を生じないものであることが望ましい。有機酸塩としては、例えば、ギ酸、シュウ酸、酢酸またはクエン酸のアンモニウム塩、バリウム塩またはセシウム塩を用いることが望ましい。なお、有機酸塩として、ギ酸ヒドラジンを用いてもよい。 It is desirable that the organic acid salt used in the second cleaning step S2 is an organic acid salt that dissociates in an aqueous solution to generate cations that are more easily adsorbed on the cation exchange resin than hydrogen ions. That is, the organic acid salt has carbon, hydrogen, oxygen and nitrogen as its main constituent elements, and after the completion of the second cleaning step S2, the organic acid salt aqueous solution which is a cleaning waste liquid is oxidized using, for example, ozone. It is desirable that no non-volatile residue is generated in the waste liquid when the (waste liquid decomposition step S4) is performed. As the organic acid salt, for example, it is desirable to use an ammonium salt, barium salt or cesium salt of formic acid, oxalic acid, acetic acid or citric acid. In addition, hydrazine formate may be used as an organic acid salt.
　アンモニウム塩は、酸化処理により、窒素ガス及び水に分解されるため、バリウム塩及びセシウム塩に比べて、放射性廃棄物の発生量を低減することができる。ギ酸、シュウ酸、酢酸またはクエン酸のアンモニウム塩、バリウム塩またはセシウム塩は、水溶液中で解離して、ＮＨ４＋、Ｂａ２＋またはＣｓ＋になる。ＮＨ４＋、Ｂａ２＋またはＣｓ＋は、水素イオンよりも陽イオン交換樹脂に吸着されやすい陽イオンである。 Since the ammonium salt is decomposed into nitrogen gas and water by the oxidation treatment, the amount of radioactive waste generated can be reduced as compared with the barium salt and the cesium salt. Formic acid, oxalic acid, acetic acid or citric acid ammonium salts, barium salts or cesium salts dissociate in aqueous solution to NH 4+ , Ba 2+ or Cs + . NH 4+ , Ba 2+ or Cs + are cations that are more easily adsorbed on the cation exchange resin than hydrogen ions.
　第二洗浄工程Ｓ２において発生する、溶離されたα核種等の放射性核種を含む、洗浄廃液である有機酸塩水溶液に対して、廃液分解工程Ｓ４が実施される。廃液分解工程（有機酸及び有機酸塩のいずれかの分解工程）Ｓ４では、オゾンまたは過酸化水素等の分解用酸化剤が有機酸塩水溶液中に曝気され、その分解用酸化剤により有機酸塩が分解される。 The waste liquid decomposition step S4 is carried out on the organic acid salt aqueous solution which is the cleaning waste liquid containing radioactive nuclides such as the eluted α nuclides generated in the second cleaning step S2. In the waste liquid decomposition step (decomposition step of either organic acid or organic acid salt) S4, a decomposition oxidizing agent such as ozone or hydrogen peroxide is exposed to the organic acid salt aqueous solution, and the organic acid salt is decomposed by the decomposition oxidizing agent. Is disassembled.
　廃液分解工程Ｓ４で有機酸または有機酸塩が分解されて残った、放射性核種を含む残留水溶液（放射性廃液）に、α核種のコロイド生成工程Ｓ５が実施される。α核種のコロイド生成工程Ｓ５では、酸、水質調整用酸化剤、還元剤及びアルカリうちの少なくとも１つの注入を行うことにより、その放射性廃液の水質を調整して、具体的には、放射性廃液のｐＨを４以上８未満の範囲に調整して、放射性廃液に含まれるα核種の一部の化学形態をコロイドにする。α核種の残りの核種は、放射性廃液の水質を調整してもイオンのままである。α核種に含まれるＵ，ＰＵ及びＮｐは、粒径の大きなコロイドになり、α核種に含まれるアメリシウム及びキュリウムは放射性廃液中でイオンのままである。 The colloid generation step S5 of the α nuclide is carried out in the residual aqueous solution (radioactive waste liquid) containing the radionuclide remaining after the organic acid or the organic acid salt is decomposed in the waste liquid decomposition step S4. In the α-nuclide colloid generation step S5, the water quality of the radioactive effluent is adjusted by injecting at least one of an acid, an oxidizing agent for adjusting the water quality, a reducing agent, and an alkali. The pH is adjusted to the range of 4 or more and less than 8, and some chemical forms of α-nuclide contained in the radioactive liquid liquid are made colloid. The remaining nuclides of α-nuclide remain ions even if the water quality of the radioactive liquid waste is adjusted. U, PU and Np contained in the α nuclide become colloids having a large particle size, and americium and curium contained in the α nuclide remain ions in the radioactive liquid waste liquid.
　α核種のコロイド除去工程Ｓ６では、α核種吸着材を注入するよりも前に放射性廃液に注入されたｐＨ調整剤、例えば、還元剤は、放射性廃液に含まれた状態で排出される。そして、放射性廃液の水質調整により、放射性廃液内で生成された、α核種の一部であるＵ，ＰＵ及びＮｐのそれぞれの粒径の大きなコロイドは、α核種のコロイド除去工程Ｓ６において、フィルタによって除去される。 In the α-nuclide colloid removal step S6, the pH adjuster, for example, the reducing agent, which was injected into the radioactive liquid waste before the α-nuclide adsorbent was injected, is discharged in a state of being contained in the radioactive liquid waste. Then, the colloids having large particle sizes of U, PU, and Np, which are a part of the α-nuclide, produced in the radioactive liquid waste by adjusting the water quality of the radioactive liquid waste are subjected to a filter in the colloid removal step S6 of the α-nuclide. Will be removed.
　放射性廃液内に残存する、Ｕ，ＰＵ及びＮｐのそれぞれの粒径の小さなコロイド、Ｕ，ＰＵ及びＮｐのそれぞれのイオン、及びα核種の残りのアメリシウム及びキュリウムは、フィルタを通過し、フィルタの下流に配置されたα核種除去装置内のα核種吸着材に吸着されて除去される（α核種のイオン除去工程Ｓ７）。α核種吸着材は、フィルタを通過した放射性廃液に注入されてα核種除去装置内に導かれる。 The small colloids of U, PU and Np, the ions of U, PU and Np, and the remaining americium and curium of the α nuclide that remain in the radioactive liquid liquid pass through the filter and are downstream of the filter. It is adsorbed and removed by the α-nuclide adsorbent in the α-nuclide removing device arranged in (α-nuclide ion removing step S7). The α-nuclide adsorbent is injected into the radioactive liquid waste that has passed through the filter and guided into the α-nuclide removal device.
　α核種のイオン除去工程Ｓ７の次の吸着材分離工程Ｓ８では、α核種除去装置から排出された放射性廃液からα核種吸着材を分離する。その後、その放射性廃液にα核種のコロイド生成工程Ｓ５において注入されたｐＨ調整剤が分解可能であるかを判定する（ｐＨ調整剤判定工程Ｓ９）。ｐＨ調整剤が、例えば、分解可能なｐＨ調整剤であるとき、その判定が「ＹＥＳ」となり、α核種除去装置から排出された、そのｐＨ調整剤を含む放射性廃液は、触媒（例えば、貴金属）を内部に有する分解装置に供給される。そのｐＨ調整剤は、分解装置内で、その触媒と分解装置に供給される分解用酸化剤（例えば、過酸化水素）の作用によって分解される（分解可能なｐＨ調整剤の分解工程Ｓ１０）。 In the adsorbent separation step S8 following the α-nuclide ion removal step S7, the α-nuclide adsorbent is separated from the radioactive liquid discharged from the α-nuclide removal device. Then, it is determined whether the pH adjuster injected into the radioactive liquid waste in the colloid production step S5 of the α-nuclide can be decomposed (pH adjuster determination step S9). When the pH adjuster is, for example, a decomposable pH adjuster, the determination is "YES", and the radioactive liquid waste containing the pH adjuster discharged from the α nuclide remover is a catalyst (for example, a noble metal). Is supplied to a decomposition device having an internal structure. The pH adjuster is decomposed in the decomposition apparatus by the action of the catalyst and the decomposition oxidizing agent (for example, hydrogen peroxide) supplied to the decomposition apparatus (decomposition step S10 of the decomposable pH adjuster).
　なお、ｐＨ調整剤として酸（例えば、希硝酸水溶液）を放射性廃液に注入した場合、及びα核種のコロイド生成工程Ｓ５において分解可能なｐＨ調整剤を用いない水質調整が実施された場合には、上記の判定が「Ｎｏ」となり、分解可能なｐＨ調整剤の分解工程Ｓ１０が実施されない。 When an acid (for example, a dilute nitric acid aqueous solution) is injected into the radioactive liquid waste liquid as a pH adjuster, or when the water quality is adjusted without using a decomposable pH adjuster in the α nuclei colloid production step S5, the water quality is adjusted. The above determination becomes "No", and the decomposition step S10 of the decomposable pH adjuster is not carried out.
　減容工程Ｓ１１では、ｐＨ調整剤を含まない放射性廃液（注入された酸を含む放射性廃液を含む）に対し、濃縮処理または乾燥粉体化処理が施される。容器充填または固化工程Ｓ１２では、濃縮処理により発生した濃縮廃液、または乾燥粉体化処理によって発生した放射性廃棄物の粉体が、容器内に充填されて保管され、またはセメント等の固形剤により容器内で固化される。 In the volume reduction step S11, the radioactive waste liquid containing no pH adjuster (including the radioactive waste liquid containing the injected acid) is subjected to a concentration treatment or a dry powder treatment. In the container filling or solidification step S12, the concentrated waste liquid generated by the concentration treatment or the powder of the radioactive waste generated by the dry powdering treatment is filled in the container and stored, or the container is filled with a solid agent such as cement. Solidified within.
　次に、実施例１のステップＳ１～Ｓ１２の各工程を含む放射性廃液の処理方法に用いられる放射性廃液処理システムの構造の一例を、図２を参照して説明する。 Next, an example of the structure of the radioactive waste liquid treatment system used in the method for treating the radioactive liquid waste including the steps S1 to S12 of the first embodiment will be described with reference to FIG.
　その放射性廃液処理システム１は、放射性有機廃棄物を処理する化学洗浄部１０、及び化学洗浄部１０から排出される洗浄廃液（放射性廃液）を処理する廃液処理部１９を備えている。化学洗浄部１０では、図１に示した各工程のうち、クラッドを溶解する第一洗浄工程Ｓ１、及び放射性核種を放射性有機廃棄物から溶離させる第二洗浄工程Ｓ２が行われる。 The radioactive liquid waste treatment system 1 includes a chemical cleaning unit 10 for treating radioactive organic waste and a waste liquid treatment unit 19 for treating the cleaning waste liquid (radioactive waste liquid) discharged from the chemical cleaning unit 10. In the chemical cleaning unit 10, among the steps shown in FIG. 1, a first cleaning step S1 for dissolving the clad and a second cleaning step S2 for eluting the radionuclide from the radioactive organic waste are performed.
　化学洗浄部１０は、第一受入タンク３、化学反応槽（洗浄槽）４、洗浄液供給タンク６、有機酸槽７、有機酸塩槽８及び移送水槽９を有する。また、高線量樹脂貯蔵タンク２が化学洗浄部１０の前段に配置され、第二受入タンク１１及び焼却設備（またはセメント固化設備）１２が化学洗浄部１０の下流に配置される。 The chemical cleaning unit 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. Further, the high-dose resin storage tank 2 is arranged in front of the chemical cleaning unit 10, and the second receiving tank 11 and the incinerator (or cement solidification equipment) 12 are arranged downstream of the chemical cleaning unit 10.
　移送ポンプ２２を設けた有機廃棄物供給管２３が、高線量樹脂貯蔵タンク２と第一受入タンク３を接続する。化学反応槽４が、移送ポンプ２４を設けた有機廃棄物移送管２５によって第一受入タンク３に接続されている。加熱装置５が化学反応槽４の周囲に配置される。洗浄液供給タンク６が、移送ポンプ３２を設けた洗浄液供給管３３によって、化学反応槽４に接続されている。化学反応槽４の底部に接続されて移送ポンプ３４及び弁３５が設けられた戻り配管３６が、洗浄液供給タンク６に接続される。 The organic waste supply pipe 23 provided with the transfer pump 22 connects the high-dose resin storage tank 2 and the first receiving tank 3. The chemical reaction tank 4 is connected to the first receiving tank 3 by an organic waste transfer pipe 25 provided with a transfer pump 24. The heating device 5 is arranged around the chemical reaction tank 4. The cleaning liquid supply tank 6 is connected to the chemical reaction tank 4 by a cleaning liquid supply pipe 33 provided with a transfer pump 32. The return pipe 36, which is connected to the bottom of the chemical reaction tank 4 and is provided with the transfer pump 34 and the valve 35, is connected to the cleaning liquid supply tank 6.
　有機酸水溶液、例えば、シュウ酸水溶液が充填された有機酸槽７に接続されて弁２６が設けられた配管２９が、洗浄液供給タンク６に接続される。有機酸槽７に充填されたシュウ酸水溶液は飽和水溶液であり、そのシュウ酸水溶液のシュウ酸濃度は、例えば、０．８ｍｏｌ／Ｌである。有機酸塩水溶液、例えば、ギ酸ヒドラジン水溶液が充填された有機酸塩槽８に接続されて弁２７が設けられた配管３０が、弁２６よりも下流で配管２９に接続される。移送水となる水が充填された移送水槽９に接続されて弁２８が設けられた配管３１が、弁２７よりも下流で配管３０に接続される。 A pipe 29 connected to an organic acid tank 7 filled with an organic acid aqueous solution, for example, an oxalic acid aqueous solution and provided with a valve 26 is connected to a cleaning liquid supply tank 6. The oxalic acid aqueous solution filled in the organic acid tank 7 is a saturated aqueous solution, and the oxalic acid concentration of the oxalic acid aqueous solution is, for example, 0.8 mol / L. A pipe 30 connected to an organic acid salt tank 8 filled with an aqueous organic acid salt solution, for example, an aqueous solution of hydrazine formate and provided with a valve 27 is connected to the pipe 29 downstream of the valve 26. The pipe 31 provided with the valve 28 connected to the transfer water tank 9 filled with water to be the transfer water is connected to the pipe 30 downstream of the valve 27.
　弁３７が設けられて化学反応槽４の底部に接続された配管３８が、第二受入タンク１１に接続されている。第二受入タンク１１に接続された配管が、焼却設備（またはセメント固化設備）１２に接続される。 The pipe 38 provided with the valve 37 and connected to the bottom of the chemical reaction tank 4 is connected to the second receiving tank 11. The pipe connected to the second receiving tank 11 is connected to the incinerator (or cement solidification facility) 12.
　また、廃液処理部１９は、廃液分解装置１３、水質調整装置５４、α核種除去装置１４、α核種吸着材注入装置６９、α核種吸着材分離装置７２、分解装置１０７、酸化剤供給装置１０８及び処理水回収タンク１８を有する。移送ポンプ３４と弁３５の間で戻り配管３６に接続されて弁３９が設けられた配管４０が、廃液分解装置１３に接続されている。移送ポンプ４３及び弁４４が設けられた配管４５が、廃液分解装置１３、水質調整装置５４及びα核種除去装置１４に接続されている。配管４５は、「α核種を含む放射性廃液を導く放射性廃液供給管」である。 Further, the waste liquid treatment unit 19 includes a waste liquid decomposition device 13, a water quality adjusting device 54, an α nuclide removing device 14, an α nuclide adsorbent injection device 69, an α nuclide adsorbent separating device 72, a decomposition device 107, an oxidizing agent supply device 108, and the like. It has a treated water recovery tank 18. The pipe 40, which is connected to the return pipe 36 between the transfer pump 34 and the valve 35 and is provided with the valve 39, is connected to the waste liquid decomposition device 13. The pipe 45 provided with the transfer pump 43 and the valve 44 is connected to the waste liquid decomposition device 13, the water quality adjusting device 54, and the α nuclide removing device 14. The pipe 45 is a “radioactive waste liquid supply pipe that guides radioactive waste liquid containing α-nuclide”.
　廃液分解装置１３は、図３に示すように、廃液貯槽で構成され、その廃液貯槽内の底部にオゾン噴射管５１が設置されている。このオゾン噴射管５１には、多数の噴射孔が形成されている。オゾン噴射管５１は、オゾン供給管５２によりオゾン供給装置５０に接続されている。配管４０は廃液分解装置１３の廃液貯槽に接続される。配管４５の一端部は廃液貯槽内に挿入されている。さらに、廃液分解装置１３の廃液貯槽には、ガス排気管５３が接続される。 As shown in FIG. 3, the waste liquid decomposition device 13 is composed of a waste liquid storage tank, and an ozone injection pipe 51 is installed at the bottom of the waste liquid storage tank. A large number of injection holes are formed in the ozone injection pipe 51. The ozone injection pipe 51 is connected to the ozone supply device 50 by the ozone supply pipe 52. The pipe 40 is connected to the waste liquid storage tank of the waste liquid decomposition device 13. One end of the pipe 45 is inserted into the waste liquid storage tank. Further, a gas exhaust pipe 53 is connected to the waste liquid storage tank of the waste liquid decomposition device 13.
　配管４６が、α核種除去装置１４、α核種吸着材分離装置７２、分解装置１０７及び処理水回収タンク１８に接続される。α核種吸着材注入装置６９は、α核種除去装置１４に連絡される。 The pipe 46 is connected to the α nuclide removing device 14, the α nuclide adsorbent separating device 72, the decomposition device 107, and the treated water recovery tank 18. The α-nuclide adsorbent injection device 69 is contacted with the α-nuclide removal device 14.
　水質調整装置５４、α核種除去装置１４及びα核種吸着材注入装置６９のそれぞれの詳細な構造は、図４を用いて順次説明する。 The detailed structures of the water quality adjusting device 54, the α nuclide removing device 14, and the α nuclide adsorbent injection device 69 will be sequentially described with reference to FIG.
　まず、水質調整装置５４について説明する。水質調整装置５４は、α核種除去装置１４に接続された配管４５に設けられ、ｐＨ調整剤注入装置５５及びｐＨ計４９Ａを有する。ｐＨ調整剤注入装置５５は、還元剤注入装置１７、酸注入装置５６、酸化剤注入装置７５及びアルカリ注入装置７９を有する。 First, the water quality adjusting device 54 will be described. The water quality adjusting device 54 is provided in a pipe 45 connected to the α nuclide removing device 14, and has a pH adjusting agent injection device 55 and a pH meter 49A. The pH adjuster injection device 55 includes a reducing agent injection device 17, an acid injection device 56, an oxidant injection device 75, and an alkali injection device 79.
　還元剤注入装置１７は、還元剤供給装置８５、酸化還元電位調整剤供給装置８９、混合槽１７Ａ、及び弁４１が設けられた注入配管４２を有する。還元剤供給装置８５は、還元剤槽８６、及び弁８７が設けられた注入配管８８を有する。注入配管８８は、還元剤槽８６に接続され、混合槽１７Ａに接続される配管８８に接続される。還元剤槽８６には、アルカリ性還元剤水溶液、例えば、ヒドラジン水溶液が充填される。酸化還元電位調整剤供給装置８９は、酸化還元電位調整剤槽９０、及び弁９１が設けられた注入配管９２を有する。注入配管９２は、酸化還元電位調整剤槽９０に接続され、さらに、配管９３に接続される。酸化還元電位調整剤槽９０には、酸化還元電位調整剤水溶液、例えば、アスコルビン酸水溶液が充填される。混合槽１７Ａに接続された注入配管４２は、移送ポンプ４１（図２参照）と後述のα核種除去装置１５の間で配管４５に接続される。 The reducing agent injection device 17 has an injection pipe 42 provided with a reducing agent supply device 85, a redox potential adjusting agent supply device 89, a mixing tank 17A, and a valve 41. The reducing agent supply device 85 has a reducing agent tank 86 and an injection pipe 88 provided with a valve 87. The injection pipe 88 is connected to the reducing agent tank 86 and is connected to the pipe 88 connected to the mixing tank 17A. The reducing agent tank 86 is filled with an alkaline reducing agent aqueous solution, for example, a hydrazine aqueous solution. The redox potential adjusting agent supply device 89 has an oxidation-reduction potential adjusting agent tank 90 and an injection pipe 92 provided with a valve 91. The injection pipe 92 is connected to the redox potential adjusting agent tank 90 and further connected to the pipe 93. The redox potential adjusting agent tank 90 is filled with an aqueous solution of the redox potential adjusting agent, for example, an aqueous solution of ascorbic acid. The injection pipe 42 connected to the mixing tank 17A is connected to the pipe 45 between the transfer pump 41 (see FIG. 2) and the α-nuclide removing device 15 described later.
　酸注入装置５６は、酸槽５７、及び弁５８が設けられた注入配管５９Ａを有する。注入配管５９Ａは、酸槽５７に接続され、さらに、弁４１の下流で注入配管４２に接続される。酸槽５７には、酸水溶液、例えば、希硝酸水溶液が充填される。 The acid injection device 56 has an acid tank 57 and an injection pipe 59A provided with a valve 58. The injection pipe 59A is connected to the acid tank 57 and further connected to the injection pipe 42 downstream of the valve 41. The acid tank 57 is filled with an acid aqueous solution, for example, a dilute nitric acid aqueous solution.
　酸化剤注入装置７５は、酸化剤槽７６、及び弁７７が設けられた注入配管７８を有する。酸化剤槽７６に接続された注入配管７８は、弁４１の下流で注入配管４２に接続される。酸化剤槽７６には、水質調整用酸化剤水溶液、例えば、シュウ酸水溶液が充填される。 The oxidant injection device 75 has an oxidant tank 76 and an injection pipe 78 provided with a valve 77. The injection pipe 78 connected to the oxidant tank 76 is connected to the injection pipe 42 downstream of the valve 41. The oxidant tank 76 is filled with an aqueous oxidant solution for adjusting water quality, for example, an oxalic acid aqueous solution.
　アルカリ注入装置７９は、アルカリ槽８０、及び弁８１が設けられた注入配管８２を有する。注入配管８２は、アルカリ槽８０に接続され、さらに、弁７７の下流で注入配管７８に接続される。アルカリ槽８０には、アルカリ水溶液、例えば、水酸化ナトリウム水溶液が充填される。 The alkali injection device 79 has an alkali tank 80 and an injection pipe 82 provided with a valve 81. The injection pipe 82 is connected to the alkaline tank 80 and further connected to the injection pipe 78 downstream of the valve 77. The alkaline tank 80 is filled with an alkaline aqueous solution, for example, a sodium hydroxide aqueous solution.
　また、ｐＨ計４９Ａが、還元剤注入装置１７に接続された注入配管４２及び配管４５の接続点よりも下流の部分で配管４５に取り付けられる。α核種濃度計６５が、ｐＨ計４９Ａが配管４５に取り付けられた部分と、配管４５と配管６７との接続点との間で、配管４５に取り付けられる。なお、その配管６７は、移送ポンプ３４と弁３５の間で、化学洗浄部１０の戻り配管３６に接続される。 Further, the pH meter 49A is attached to the pipe 45 at a portion downstream from the connection point of the injection pipe 42 and the pipe 45 connected to the reducing agent injection device 17. The α-nuclide concentration meter 65 is attached to the pipe 45 between the portion where the pH meter 49A is attached to the pipe 45 and the connection point between the pipe 45 and the pipe 67. The pipe 67 is connected to the return pipe 36 of the chemical cleaning unit 10 between the transfer pump 34 and the valve 35.
　還元剤注入装置１７からアルカリ還元剤であるヒドラジン（還元剤槽８６内に存在）、アルカリ注入装置７９からアルカリである水酸化ナトリウム及び還元剤注入装置５４から酸化還元電位調整剤であるアスコルビン酸（酸化還元電位調整剤槽９０内に存在）のうち少なくとも１つの物質を配管４５に注入することにより、配管４５内を流れる放射性廃液をアルカリ性に調整することができ、その放射性廃液を還元雰囲気に調整することが可能になる。また、酸注入装置５６から酸である希硝酸、酸化剤注入装置７５から水質調整用酸化剤であるシュウ酸及び還元剤注入装置５４から酸化還元電位調整剤であるアスコルビン酸のうち少なくとも１つの物質を配管４５に注入することにより、配管４５内を流れる放射性廃液を酸性に調整することができ、その放射性廃液を還元雰囲気に調整することが可能になる。 Hydrazin (existing in the reducing agent tank 86) which is an alkali reducing agent from the reducing agent injection device 17, sodium hydroxide which is an alkali from the alkali injection device 79, and ascorbic acid (oxidation-reduction potential adjuster) which is an oxidation-reduction potential adjuster from the reducing agent injection device 54. By injecting at least one substance (existing in the oxidation-reduction potential adjusting agent tank 90) into the pipe 45, the radioactive liquid liquid flowing in the pipe 45 can be adjusted to be alkaline, and the radioactive liquid liquid can be adjusted to a reducing atmosphere. It becomes possible to do. Further, at least one substance is dilute nitric acid which is an acid from the acid injection device 56, oxalic acid which is an oxidant for water quality adjustment from the oxidant injection device 75, and ascorbic acid which is an oxidation-reduction potential adjuster from the reducing agent injection device 54. By injecting the above into the pipe 45, the radioactive liquid waste flowing in the pipe 45 can be adjusted to be acidic, and the radioactive liquid waste liquid can be adjusted to a reducing atmosphere.
　フィルタ６６が、水質調整装置５４とα核種除去装置１４の間で、具体的には、α核種濃度計６５が配管４５に取り付けられた位置とα核種除去装置１４の間で、配管４５に設置される（図４参照）。フィルタ６６は、例えば、μｍオーダー以下の孔径を有する膜を有する。なお、フィルタ６６は、α核種濃度計６５の配管４５への取り付け位置と、配管６７と配管４５の接続点との間で、配管に設置される。 The filter 66 is installed in the pipe 45 between the water quality adjusting device 54 and the α nuclide removing device 14, specifically, between the position where the α nuclide concentration meter 65 is attached to the pipe 45 and the α nuclide removing device 14. (See FIG. 4). The filter 66 has, for example, a membrane having a pore size on the order of μm or less. The filter 66 is installed in the pipe between the attachment position of the α-nuclide concentration meter 65 to the pipe 45 and the connection point between the pipe 67 and the pipe 45.
　α核種除去装置１４は、図４に示すように、フィルタ６６の下流に配置されて配管４５に接続され、配管４５を通して水質調整装置５４によって水質が調整された放射性廃液を収容するケーシングを有している。スペース領域１５、及びα核種吸着材であるフェライト粒子が多く存在する領域１６が、そのケーシング内に形成されている。スペース領域１５は領域１６よりも上流に位置している。磁化率測定装置４９Ｂが、α核種除去装置１４のケーシングの、領域１６に対向する外面に設置されている。 As shown in FIG. 4, the α-nuclide removing device 14 has a casing arranged downstream of the filter 66, connected to the pipe 45, and accommodating the radioactive liquid waste whose water quality has been adjusted by the water quality adjusting device 54 through the pipe 45. ing. A space region 15 and a region 16 in which a large amount of ferrite particles, which are α-nuclide adsorbents, are present are formed in the casing. The space region 15 is located upstream of the region 16. The magnetic susceptibility measuring device 49B is installed on the outer surface of the casing of the α-nuclide removing device 14 facing the region 16.
　α核種吸着材注入装置６９は、図４に示すように、α核種吸着材、例えば、フェライト（Ｆｅ3Ｏ4）の粒子が充填される吸着材槽７０、及び弁７２Ａが設けられた注入配管７１を有する。注入配管７１の一端は吸着材槽７０に接続され、注入配管７１の他端はα核種除去装置１４内のスペース領域１５内に挿入されている。α核種吸着材注入装置６９の吸着材槽７０から注入配管７１を通して、α核種除去装置１４のケーシング内のスペース領域１５に存在する放射性廃液に、α核種吸着材であるフェライト粒子を注入することができる。 As shown in FIG. 4, the α-nuclide adsorbent injection device 69 includes an adsorbent tank 70 filled with α-nuclide adsorbent, for example, ferrite (Fe 3 O 4 ) particles, and an injection pipe provided with a valve 72A. Has 71. One end of the injection pipe 71 is connected to the adsorbent tank 70, and the other end of the injection pipe 71 is inserted into the space region 15 in the α-nuclide removing device 14. Ferrite particles, which are α-nuclide adsorbents, can be injected into the radioactive liquid liquid existing in the space region 15 in the casing of the α-nuclide removing device 14 from the adsorbent tank 70 of the α-nuclide adsorbent injection device 69 through the injection pipe 71. can.
　α核種吸着材分離装置７２は、フィルタ６６と同様に、例えば、μｍオーダー以下の孔径を有する膜を有する。化学洗浄部１０の戻り配管３６の移送ポンプ３４と弁３５の間に接続された配管６８が、α核種吸着材分離装置７２に接続される。そして、α核種吸着材分離装置７２においてろ過してα核種吸着材が分離されたろ過水である放射性廃液は、配管６８を通じて戻り配管３６に戻る。これにより、ろ過水を循環水として循環させることができる。 The α-nuclide adsorbent separating device 72 has, for example, a membrane having a pore size on the order of μm or less, similarly to the filter 66. The pipe 68 connected between the transfer pump 34 and the valve 35 of the return pipe 36 of the chemical cleaning unit 10 is connected to the α-nuclide adsorbent separating device 72. Then, the radioactive liquid waste liquid, which is the filtered water from which the α-nuclide adsorbent has been separated by filtering in the α-nuclide adsorbent separating device 72, returns to the return pipe 36 through the pipe 68. As a result, the filtered water can be circulated as circulating water.
　なお、戻り配管３６と配管６７及び６８との各接続部よりも各配管３６，６７及び６８の上流側（化学反応槽４側、水質調整装置５４側、α核種吸着材分離装置７２側）には、図示しない弁を設ける。これにより、化学反応槽４からの水と、配管６７からの水と、及び配管６８からのろ過水とを切り替えることができる。 In addition, on the upstream side (chemical reaction tank 4 side, water quality adjusting device 54 side, α-nuclide adsorbent separating device 72 side) of each pipe 36, 67 and 68 from each connection portion between the return pipe 36 and the pipes 67 and 68. Provide a valve (not shown). Thereby, the water from the chemical reaction tank 4, the water from the pipe 67, and the filtered water from the pipe 68 can be switched.
　分解装置１０７は、内部に、例えば、ルテニウムを活性炭の表面に添着した活性炭触媒を充填している。 The decomposition device 107 is filled with, for example, an activated carbon catalyst in which ruthenium is adhered to the surface of the activated carbon.
　酸化剤供給装置１０８は、薬液タンク１０９及び供給配管１１０を有する。薬液タンク１０９は、弁１１１を有する供給配管１１０によって分解装置１０７に接続される。この薬液タンク１０９内には、分解用酸化剤である過酸化水素が充填される。なお、分解用酸化剤として、過酸化水素の替りに、オゾン、または酸素を溶解した水を用いてもよい。 The oxidant supply device 108 has a chemical solution tank 109 and a supply pipe 110. The chemical tank 109 is connected to the disassembling device 107 by a supply pipe 110 having a valve 111. The chemical tank 109 is filled with hydrogen peroxide, which is an oxidizing agent for decomposition. As the oxidizing agent for decomposition, ozone or water in which oxygen is dissolved may be used instead of hydrogen peroxide.
　さらに、処理水回収タンク１８の下流側に、乾燥粉体化装置２０及び固化設備２１が配置される。移送ポンプ４７を設けた配管４８が、処理水回収タンク１８と乾燥粉体化装置２０を接続する。乾燥粉体化装置２０に接続された配管４９が、固化設備２１に接続される。なお、乾燥粉体化装置２０の替りに、放射性廃液の濃縮装置を用いてもよい。 Further, a dry powdering device 20 and a solidifying facility 21 are arranged on the downstream side of the treated water recovery tank 18. A pipe 48 provided with a transfer pump 47 connects the treated water recovery tank 18 and the dry powdering device 20. The pipe 49 connected to the dry powdering apparatus 20 is connected to the solidification equipment 21. Instead of the dry powdering device 20, a radioactive waste concentrating device may be used.
　次に、図２に示した放射性廃液処理システム１を用いた、本実施例の放射性廃液の処理方法を、詳細に説明する。 Next, the method of treating the radioactive liquid waste of this embodiment using the radioactive liquid waste treatment system 1 shown in FIG. 2 will be described in detail.
　沸騰水型原子力プラントの原子炉冷却材浄化系及び燃料プール冷却浄化系等から排出されて、高線量樹脂貯蔵タンク２に所定の長期間貯蔵された放射性有機廃棄物は、セルロース系のろ過助材、イオン交換樹脂、等を含む。高線量樹脂貯蔵タンク２に貯蔵された放射性有機廃棄物は、配管（図示せず）によって、移送水槽（図示せず）内の水を高線量樹脂貯蔵タンク２に供給することにより、移送し易いスラリーの状態になる。高線量樹脂貯蔵タンク２内の放射性有機廃棄物には、原子炉冷却材浄化系及び燃料プール冷却浄化系等で冷却水から除去されたクラッドが含まれており、クラッドにはコバルト６０等の放射性核種が含まれている。また、高線量樹脂貯蔵タンク２に貯蔵されたイオン交換樹脂には、コバルト６０、セシウム１３７、炭素１４、塩素３６等のα核種以外の放射性核種のイオンが吸着されている。さらに、そのイオン交換樹脂には、前述したように、α核種（ウラン、プルトニウム、アメリシウム、ネプツニウム及びキュリウム等）が吸着されている。 Radioactive organic waste discharged from the reactor cooling material purification system and fuel pool cooling purification system of a boiling water reactor and stored in the high-dose resin storage tank 2 for a predetermined period of time is a cellulose-based filtration aid. , Ion exchange resin, etc. The radioactive organic waste stored in the high-dose resin storage tank 2 can be easily transferred by supplying the water in the transfer water tank (not shown) to the high-dose resin storage tank 2 by a pipe (not shown). It becomes a slurry state. The radioactive organic waste in the high-dose resin storage tank 2 contains a clad removed from the cooling water by the reactor cooling material purification system, the fuel pool cooling purification system, etc., and the clad is radioactive such as cobalt-60. Contains nuclear species. Further, ions of radionuclides other than α-nuclide such as cobalt-60, cesium-137, carbon-14, and chlorine-36 are adsorbed on the ion exchange resin stored in the high-dose resin storage tank 2. Further, as described above, α-nuclides (uranium, plutonium, americium, neptunium, curium, etc.) are adsorbed on the ion exchange resin.
　移送ポンプ２２を駆動することにより、放射性有機廃棄物を約１０ｗｔ％含むスラリーが、所定量、高線量樹脂貯蔵タンク２から有機廃棄物供給管２３を通して第一受入タンク３に移送される。第一受入タンク３内の放射性有機廃棄物のスラリーは、移送ポンプ２４の駆動により、有機廃棄物移送管２５を通して化学反応槽４に供給される。化学反応槽４内で、放射性有機廃棄物スラリーの水位が所定レベルに達したとき、移送ポンプ２４が停止され、そのスラリーの化学反応槽４への供給が停止される。 By driving the transfer pump 22, a slurry containing about 10 wt% of radioactive organic waste is transferred from the high-dose resin storage tank 2 to the first receiving tank 3 through the organic waste supply pipe 23 in a predetermined amount. The slurry of radioactive organic waste in the first receiving tank 3 is supplied to the chemical reaction tank 4 through the organic waste transfer pipe 25 by driving the transfer pump 24. When the water level of the radioactive organic waste slurry reaches a predetermined level in the chemical reaction tank 4, the transfer pump 24 is stopped, and the supply of the slurry to the chemical reaction tank 4 is stopped.
　その後、移送ポンプ３４が駆動され、化学反応槽４内のスラリーに含まれる水が、放射性廃液（以下、「第三放射性廃液」とする）として、戻り配管３６及び配管４０を通して廃液分解装置１３の廃液貯槽（図示せず）に導かれる。このとき、弁３５は閉じており、弁３９は開いている。廃液貯槽に導かれた第三放射性廃液は、移送ポンプ４３の駆動により、配管４５を通してα核種除去装置１４に導かれる。化学反応槽４内で、放射性有機廃棄物スラリーに含まれる水はα核種を含んでいないので、廃液貯槽内の第三放射性廃液は、α核種を含んでおらず、α核種以外の放射性核種を含んでいる。このため、α核種を含んでいない第三放射性廃液に対する、水質調整装置５４を用いた水質調整は行われない。 After that, the transfer pump 34 is driven, and the water contained in the slurry in the chemical reaction tank 4 is used as radioactive waste liquid (hereinafter referred to as “third radioactive liquid waste”) through the return pipe 36 and the pipe 40 of the waste liquid decomposition device 13. Guided to a waste liquid storage tank (not shown). At this time, the valve 35 is closed and the valve 39 is open. The third radioactive liquid waste guided to the waste liquid storage tank is guided to the α-nuclide removal device 14 through the pipe 45 by driving the transfer pump 43. Since the water contained in the radioactive organic waste slurry in the chemical reaction tank 4 does not contain α-nuclide, the third radioactive liquid solution in the waste liquid storage tank does not contain α-nuclide and contains radionuclides other than α-nuclide. Includes. Therefore, the water quality of the third radioactive liquid waste containing no α-nuclide is not adjusted by using the water quality adjusting device 54.
　第三放射性廃液が、α核種除去装置１４内を通過し、配管４６に排出されて処理水回収タンク１８に導かれる。その第三放射性廃液がα核種除去装置１４に供給された際、α核種吸着材注入装置６９から注入された、α核種除去装置１４内のフェライト粒子は、α核種、及びα核種以外の放射性核種を吸着しない。なお、第三放射性廃液に含まれるコロイド性の物質及び固形分は、第三放射性廃液がα核種除去装置１４に流入する前にフィルタ６６によって除去される。第三放射性廃液がα核種を含んでいないため、分解可能なｐＨ調整剤の分解工程Ｓ１０における分解可能なｐＨ調整剤である還元剤（例えば、ヒドラジン）の分解も行われない。 The third radioactive liquid waste passes through the α nuclide removal device 14, is discharged to the pipe 46, and is guided to the treated water recovery tank 18. When the third radioactive liquid was supplied to the α-nuclide removing device 14, the ferrite particles in the α-nuclide removing device 14 injected from the α-nuclide adsorbent injection device 69 were the α-nuclide and the radionuclide other than the α-nuclide. Does not adsorb. The colloidal substances and solids contained in the third radioactive liquid waste are removed by the filter 66 before the third radioactive liquid liquid flows into the α-nuclide removing device 14. Since the third radioactive liquid waste does not contain α-nuclide, the reducing agent (for example, hydrazine) which is the decomposable pH adjuster in the decomposition step S10 of the decomposable pH adjuster is not decomposed.
　もし、第三放射性廃液がα核種を含んでいる場合には、後述の第一放射性廃液及び第２放射性廃液に対して実施されるα核種のコロイド生成工程Ｓ５から分解可能なｐＨ調整剤の分解工程Ｓ１０の工程までの各工程が、第三放射性廃液に対しても実施される。ｐＨ調整剤判定工程Ｓ９が「ＮＯ」である場合には、分解可能なｐＨ調整剤の分解工程Ｓ１０は実施されない。第三放射性廃液がα核種を含んでいるか、いないかは、廃液分解装置１３の廃液貯槽の外面付近に配置した放射線検出器で検出された放射線強度に基づいて判定される。検出された放射線強度が設定値以下であれば、第三放射性廃液にはα核種が含まれていないと判定し、その放射線強度が設定値を超えた場合には、第三放射性廃液にはα核種が含まれていると判定する。 If the third radioactive effluent contains α-nuclide, decomposition of the pH adjuster that can be decomposed from the α-nuclide colloid generation step S5 carried out for the first radioactive effluent and the second radioactive effluent, which will be described later. Each step up to the step of step S10 is also carried out for the third radioactive liquid waste. When the pH adjuster determination step S9 is "NO", the decomposition step S10 of the decomposable pH adjuster is not carried out. Whether or not the third radioactive liquid contains α-nuclide is determined based on the radiation intensity detected by the radiation detector arranged near the outer surface of the waste liquid storage tank of the waste liquid decomposition device 13. If the detected radiation intensity is less than or equal to the set value, it is determined that the third radioactive liquid waste does not contain α nuclides, and if the radiation intensity exceeds the set value, the third radioactive liquid waste is α. It is determined that the nuclide is contained.
　廃液貯槽内の第三放射性廃液のα核種除去装置１４への移送が終了したとき、移送ポンプ４３が停止される。処理水回収タンク１８内に回収された第三放射性廃液は、所定量、移送ポンプ４７を駆動することにより、配管４８を通して乾燥粉体化装置２０に供給される。α核種以外の放射性核種を含む第三放射性廃液は、乾燥粉体化装置２０で紛体化される（減容工程Ｓ１１）。 When the transfer of the third radioactive liquid waste in the waste liquid storage tank to the α-nuclide removing device 14 is completed, the transfer pump 43 is stopped. The third radioactive liquid waste collected in the treated water recovery tank 18 is supplied to the dry powdering device 20 through the pipe 48 by driving the transfer pump 47 in a predetermined amount. The third radioactive liquid waste containing radionuclides other than α-nuclide is pulverized by the dry powdering apparatus 20 (volume reduction step S11).
　その後、乾燥粉体化装置２０で生成された紛体は、固化設備２１（または充填設備）に移送される。固化設備２１では、その粉体が固化容器内に充填され、その固化容器内に固化材（例えば、セメント）が注入される。固化容器内の紛体は、固化材によって固化される（容器充填または固化工程Ｓ１２）。固化された粉体が内部に存在し、密封された固化容器は、保管場所において保管される。保管されるこの固化容器内には、超半減期のα核種が存在していない。また、充填設備を用いる場合には、容器内に粉体を充填し、粉体を充填した容器を密封した後、その容器が保管場所に保管される。 After that, the powder produced by the dry powdering apparatus 20 is transferred to the solidifying facility 21 (or filling facility). In the solidification equipment 21, the powder is filled in the solidification container, and a solidifying material (for example, cement) is injected into the solidification container. The powder in the solidification container is solidified by the solidifying material (container filling or solidification step S12). The solidified powder is present inside and the sealed solidified container is stored in a storage location. There are no ultra-half-life alpha nuclides in this solidified vessel that is stored. When a filling facility is used, the container is filled with powder, the container filled with the powder is sealed, and then the container is stored in a storage place.
　そして、第一洗浄工程Ｓ１が実施される。放射性有機廃棄物スラリーの水分が排出されて放射性有機廃棄物が残留している化学反応槽４には、移送ポンプ３２の駆動により、７２ｇ／Ｌ程度のシュウ酸水溶液（シュウ酸濃度が０．８ｍｏｌ／Ｌ）が、洗浄液供給タンク６から洗浄液供給管３３を通して供給される。このシュウ酸水溶液は、有機酸水溶液である。洗浄液供給タンク６への、シュウ酸濃度０．８ｍｏｌ／Ｌのシュウ酸水溶液の供給は、弁２６を開いたとき、配管２９を通して有機酸槽７から行われる。このとき、弁２７及び弁２８は全閉状態である。シュウ酸水溶液の替りにクエン酸水溶液を用いてもよい。これらの有機酸は、還元性を有する。 Then, the first cleaning step S1 is carried out. In the chemical reaction tank 4 where the water content of the radioactive organic waste slurry is discharged and the radioactive organic waste remains, an oxalic acid aqueous solution (oxalic acid concentration of 0.8 mol) of about 72 g / L is driven by the transfer pump 32. / L) is supplied from the cleaning liquid supply tank 6 through the cleaning liquid supply pipe 33. This oxalic acid aqueous solution is an organic acid aqueous solution. When the valve 26 is opened, the oxalic acid aqueous solution having a oxalic acid concentration of 0.8 mol / L is supplied to the cleaning liquid supply tank 6 from the organic acid tank 7 through the pipe 29. At this time, the valve 27 and the valve 28 are in the fully closed state. A citric acid aqueous solution may be used instead of the oxalic acid aqueous solution. These organic acids have reducing properties.
　加熱装置５によって、化学反応槽４内のシュウ酸水溶液が加熱される。シュウ酸水溶液の加熱温度は、１００℃未満とする。化学反応槽４内に供給されたシュウ酸水溶液に含まれるシュウ酸は、化学反応槽４内の放射性有機廃棄物に付着したクラッドを溶解する（第一洗浄工程Ｓ１）。このクラッドの溶解によって、クラッドに含まれた放射性核種、例えば、コバルト６０は、シュウ酸水溶液中に移行する。 The oxalic acid aqueous solution in the chemical reaction tank 4 is heated by the heating device 5. The heating temperature of the oxalic acid aqueous solution is less than 100 ° C. The oxalic acid contained in the oxalic acid aqueous solution supplied into the chemical reaction tank 4 dissolves the clad adhering to the radioactive organic waste in the chemical reaction tank 4 (first cleaning step S1). By dissolving the clad, the radionuclides contained in the clad, for example, cobalt-60, are transferred into the aqueous oxalic acid solution.
　化学反応槽４内でのシュウ酸水溶液によるクラッドの溶解によって生じた、シュウ酸水溶液に含まれるクラッド成分を、化学反応槽４で沈殿させる。クラッド溶解成分の沈殿によって生じた、化学反応槽４内の上澄み液であるシュウ酸水溶液のみを、移送ポンプ３４の駆動により、戻り配管３６を通して洗浄液供給タンク６に回収する。このとき、弁３９は閉じており、弁３５は開いている。洗浄液供給タンク６に回収されたシュウ酸水溶液は、化学反応槽４に供給され、化学反応槽４内でクラッドの溶解に再使用される。 The clad component contained in the oxalic acid aqueous solution generated by the dissolution of the clad with the oxalic acid aqueous solution in the chemical reaction tank 4 is precipitated in the chemical reaction tank 4. Only the oxalic acid aqueous solution, which is the supernatant liquid in the chemical reaction tank 4, generated by the precipitation of the clad-dissolved component is collected in the cleaning liquid supply tank 6 through the return pipe 36 by driving the transfer pump 34. At this time, the valve 39 is closed and the valve 35 is open. The oxalic acid aqueous solution recovered in the cleaning liquid supply tank 6 is supplied to the chemical reaction tank 4 and reused for dissolving the clad in the chemical reaction tank 4.
　第一洗浄工程Ｓ１では、放射性有機廃棄物の一部であるイオン交換樹脂が有機酸であるシュウ酸に浸漬されるため、イオン交換樹脂に吸着されている放射性核種の一部が、イオン交換樹脂から脱離される。具体的には、シュウ酸が解離して生じる水素イオン及びシュウ酸イオンが、それぞれ陽イオン交換樹脂及び陰イオン交換樹脂に吸着されている放射性核種とイオン交換されるため、一部の放射性核種（α核種、及びα核種以外の放射性核種）がイオン交換樹脂から脱離される。 In the first cleaning step S1, since the ion exchange resin which is a part of the radioactive organic waste is immersed in the oxalic acid which is an organic acid, a part of the radionuclides adsorbed on the ion exchange resin is an ion exchange resin. Be separated from. Specifically, hydrogen ions and oxalate ions generated by dissociation of oxalic acid are ion-exchanged with radioactive nuclei adsorbed on the cation exchange resin and anion exchange resin, respectively, so that some radioactive nuclei ( α nuclei and radioactive nuclei other than α nuclei) are desorbed from the ion exchange resin.
　化学反応槽４内でのクラッドの溶解が終了した後、弁３５が閉じられて弁３９が開けられる。化学反応槽４内の、クラッドの溶解に供用され、クラッドに含まれていた放射性核種（例えば、コバルト６０等）、及びシュウ酸が解離して生じる前述の水素イオン及びシュウ酸イオンとのイオン交換により、放射性有機廃棄物の一部であるそれぞれの陽イオン交換樹脂及び陰イオン交換樹脂から脱離された一部の放射性核種（α核種、及びα核種以外の放射性核種のそれぞれ）を含むシュウ酸水溶液（以下、「第一放射性廃液」とする）は、移送ポンプ３４の駆動により、配管３６及び配管４０を通して、廃液分解装置１３の廃液貯槽に移送される。 After the dissolution of the clad in the chemical reaction tank 4 is completed, the valve 35 is closed and the valve 39 is opened. Ion exchange with the above-mentioned hydrogen ion and oxalate ion generated by dissociation of the radionuclide (for example, cobalt 60, etc.) contained in the clad and the radionuclide contained in the clad, which was used for dissolving the clad in the chemical reaction tank 4. Phosphorus containing some radionuclides (α nuclides and radionuclides other than α nuclides) desorbed from each cation exchange resin and anion exchange resin that are part of the radioactive organic waste. The aqueous solution (hereinafter referred to as "first radioactive waste liquid") is transferred to the waste liquid storage tank of the waste liquid decomposition device 13 through the pipes 36 and 40 by driving the transfer pump 34.
　なお、化学洗浄部１０の化学反応槽４から廃液処理部１９の廃液分解装置１３への第一放射性廃液及び後述の第二放射性廃液のそれぞれの移送は、例えば、戻り配管３６に取り付けられたサンプリング弁（図示せず）を介して採取された第一放射性廃液及び第二放射性廃液のそれぞれを定期的に分析し、採取された第一放射性廃液及び第二放射性廃液のそれぞれに含まれるα核種の濃度が所定の濃度になったときに行われる。採取された第一放射性廃液及び第二放射性廃液のそれぞれのα核種濃度が所定の濃度になったことは、第一洗浄工程Ｓ１において化学反応槽４内の放射性有機廃棄物に付着したクラッドが化学反応槽４内の有機酸水溶液中に十分に溶解されたこと、及び化学反応槽４内の放射性有機廃棄物（例えば、陽イオン交換樹脂）に吸着されたα核種が化学反応槽４内の有機酸塩水溶液中に十分に溶離されたことを意味する。 The transfer of the first radioactive liquid waste and the second radioactive liquid waste described later from the chemical reaction tank 4 of the chemical cleaning unit 10 to the waste liquid decomposition device 13 of the waste liquid treatment unit 19 is, for example, sampling attached to the return pipe 36. Periodically analyze each of the first radioactive liquid waste and the second radioactive liquid waste collected through a valve (not shown), and the α-nuclear species contained in each of the collected first radioactive liquid waste and second radioactive liquid waste. It is performed when the concentration reaches a predetermined concentration. The fact that the α-nuclear species concentration of each of the collected first radioactive liquid and second radioactive liquid became a predetermined concentration means that the clad adhering to the radioactive organic waste in the chemical reaction tank 4 in the first cleaning step S1 is chemical. The α nuclei that were sufficiently dissolved in the organic acid aqueous solution in the reaction tank 4 and that were adsorbed on the radioactive organic waste (for example, cation exchange resin) in the chemical reaction tank 4 were organic in the chemical reaction tank 4. It means that it was sufficiently eluted in the aqueous acid salt solution.
　廃液分解装置１３の廃液貯槽へのシュウ酸を含む第一放射性廃液の移送が終了した後、廃液分解工程Ｓ４が実施される。廃液分解工程Ｓ４では、オゾンが、オゾン供給装置５０からオゾン供給管５２を通して、所定時間、廃液貯槽内のオゾン噴射管５１に供給され、オゾン噴射管５１に形成された多数の噴射孔から、廃液貯槽内の第一放射性廃液中に噴射される。第一放射性廃液に含まれる有機成分であるシュウ酸が、噴射されたオゾンにより分解される。シュウ酸は、オゾンと反応して、炭酸ガスと水に分解される。廃液貯槽内に噴射されたオゾンの残り、及び炭酸ガスが、廃液貯槽に接続されたガス排気管５３を通してオフガス処理装置（図示せず）に供給され、ガス排気管５３に排出されたガスに含まれる放射性ガスが、オフガス処理装置で取り除かれる。 After the transfer of the first radioactive liquid containing oxalic acid to the waste liquid storage tank of the waste liquid decomposition apparatus 13 is completed, the waste liquid decomposition step S4 is carried out. In the waste liquid decomposition step S4, ozone is supplied from the ozone supply device 50 through the ozone supply pipe 52 to the ozone injection pipe 51 in the waste liquid storage tank for a predetermined time, and the waste liquid is discharged from a large number of injection holes formed in the ozone injection pipe 51. It is sprayed into the first radioactive liquid waste in the storage tank. Oxalic acid, which is an organic component contained in the first radioactive liquid waste, is decomposed by the injected ozone. Oxalic acid reacts with ozone and is decomposed into carbon dioxide and water. The residue of ozone injected into the waste liquid storage tank and carbon dioxide gas are supplied to the off-gas treatment device (not shown) through the gas exhaust pipe 53 connected to the waste liquid storage tank, and are contained in the gas discharged to the gas exhaust pipe 53. The radioactive gas is removed by an off-gas treatment device.
　廃液分解装置１３の廃液貯槽内での、第一放射性廃液に含まれるシュウ酸の分解（廃液分解工程Ｓ４）が終了した後、廃液貯槽へのオゾンの供給が停止されて移送ポンプ４３が駆動され、シュウ酸分解後において廃液貯槽内に残留する、脱離されたα核種、及びα核種以外の放射性核種のそれぞれを含む水溶液、すなわち、第一放射性廃液が、配管４５を通して水質調整装置５４に供給される。このとき、弁４４は開いている。 After the decomposition of oxalic acid contained in the first radioactive liquid waste (waste liquid decomposition step S4) in the waste liquid storage tank of the waste liquid decomposition device 13 is completed, the supply of ozone to the waste liquid storage tank is stopped and the transfer pump 43 is driven. , An aqueous solution containing each of the desorbed α-nuclide and the radioactive nuclide other than the α-nuclide, which remains in the waste liquid storage tank after the decomposition of oxalic acid, that is, the first radioactive liquid waste is supplied to the water quality adjusting device 54 through the pipe 45. Will be done. At this time, the valve 44 is open.
　上述した廃液分解工程Ｓ４の後に、α核種のコロイド生成工程Ｓ５が実施される。本実施例では、水質調整装置５４において、ｐＨ調整剤注入装置５５から注入配管４２を通してｐＨ調整剤が配管４５内の第一放射性廃液に注入される。本実施例において、配管４５内の第一放射性廃液に注入されるｐＨ調整剤としては、酸、水質調整用酸化剤、還元剤及びアルカリが用いられる。 After the above-mentioned waste liquid decomposition step S4, the α nuclide colloid production step S5 is carried out. In this embodiment, in the water quality adjusting device 54, the pH adjusting agent is injected from the pH adjusting agent injection device 55 through the injection pipe 42 into the first radioactive liquid waste in the pipe 45. In this embodiment, as the pH adjusting agent to be injected into the first radioactive liquid waste in the pipe 45, an acid, an oxidizing agent for adjusting water quality, a reducing agent and an alkali are used.
　ｐＨ調整剤として酸、水質調整用酸化剤、還元剤及びアルカリを用いることにより、水質調整装置５４によって、α核種のコロイド生成工程Ｓ５において、酸、水質調整用酸化剤、還元剤及びアルカリのうち該当するｐＨ調整剤を配管４５内の第一放射性廃液に注入する注入することができる。酸、水質調整用酸化剤、還元剤及びアルカリのうちどれを注入するかは、水質調整前の第一放射性廃液の性状及び水質調整後における第一放射性廃液の目標とする性状に応じて決められる。 By using an acid, a water quality adjusting oxidant, a reducing agent and an alkali as the pH adjusting agent, the water quality adjusting device 54 causes the α nuclei species colloid production step S5 to be performed among the acid, the water quality adjusting oxidizing agent, the reducing agent and the alkali. The corresponding pH adjuster can be injected into the first radioactive effluent in the pipe 45. Which of the acid, the oxidizing agent for water quality adjustment, the reducing agent and the alkali is injected is determined according to the properties of the first radioactive liquid waste before the water quality adjustment and the target properties of the first radioactive liquid waste after the water quality adjustment. ..
　本実施例では、α核種のコロイド生成工程Ｓ５において、配管４５内のα核種を含む第一放射性廃液のｐＨを４以上８未満の範囲内のｐＨに調節するために、該当するｐＨ調整剤が水質調整装置５４から配管４５に注入される。水質調整後の第一放射性廃液のｐＨを酸性、例えば、「４」にする場合には、第一放射性廃液に酸注入装置５６から酸である所定量の希硝酸水溶液を注入する。第一放射性廃液のｐＨを中性の「７」にする場合には、酸注入装置５６から所定量の希硝酸水溶液及びアルカリ注入装置７９からアルカリである所定量の水酸化ナトリウムを第一放射性廃液に注入する。また、第一放射性廃液のｐＨを、例えば、弱アルカリ性の「７．８」にする場合には、酸注入装置５６から所定量の希硝酸水溶液、及びアルカリ注入装置７９からの所定量の水酸化ナトリウムを第一放射性廃液に注入し、さらに、還元剤注入装置１７の還元剤供給装置８５から、例えば、アルカリ性還元剤である所定量のヒドラジンを注入する。第一放射性廃液のｐＨを、例えば、弱酸性の「６．５」にする場合には、酸注入装置５６から所定量の希硝酸水溶液、アルカリ注入装置７９からの所定量の水酸化ナトリウムのそれぞれを第一放射性廃液に注入し、さらに、酸化剤注入装置７５から、例えば、水質調整用酸化剤である所定量のシュウ酸（有機酸）を注入する。第一放射性廃液のｐＨを、例えば、酸性の「４．５」にする場合には、酸注入装置５６から所定量の希硝酸水溶液、及び還元剤注入装置１７の還元剤供給装置８５から、例えば、アルカリ性還元剤である所定量のヒドラジンを注入する。また、第一放射性廃液のｐＨを「７」付近の弱アルカリ性にする場合には、所定量の希硝酸水溶液、所定量の水酸化ナトリウム、所定量のヒドラジン及び所定量のシュウ酸を注入し、ヒドラジンの注入量をシュウ酸の注入量よりも若干多くする。第一放射性廃液のｐＨを「７」付近の弱酸性にする場合には、所定量の希硝酸水溶液、所定量の水酸化ナトリウム、所定量のヒドラジン及び所定量のシュウ酸を注入し、シュウ酸の注入量をヒドラジンの注入量よりも若干多くする。 In this embodiment, in the α-nuclide colloid production step S5, in order to adjust the pH of the first radioactive liquid containing the α-nuclide in the pipe 45 to a pH in the range of 4 or more and less than 8, the corresponding pH adjuster is used. It is injected into the pipe 45 from the water quality adjusting device 54. When the pH of the first radioactive liquid waste after adjusting the water quality is set to acidic, for example, "4", a predetermined amount of dilute nitric acid aqueous solution which is an acid is injected into the first radioactive liquid waste from the acid injection device 56. When the pH of the first radioactive liquid waste is set to neutral "7", a predetermined amount of dilute nitric acid aqueous solution is added from the acid injection device 56 and a predetermined amount of sodium hydroxide which is alkaline is added from the alkali injection device 79 to the first radioactive liquid waste liquid. Inject into. Further, when the pH of the first radioactive waste liquid is set to, for example, weakly alkaline "7.8", a predetermined amount of dilute nitrate aqueous solution from the acid injection device 56 and a predetermined amount of hydroxide from the alkali injection device 79. Sodium is injected into the first radioactive liquid waste liquid, and further, for example, a predetermined amount of hydrazine, which is an alkaline reducing agent, is injected from the reducing agent supply device 85 of the reducing agent injection device 17. When the pH of the first radioactive effluent is set to, for example, the weakly acidic "6.5", a predetermined amount of dilute nitric acid aqueous solution from the acid injection device 56 and a predetermined amount of sodium hydroxide from the alkali injection device 79, respectively. Is injected into the first radioactive liquid waste liquid, and further, for example, a predetermined amount of oxalic acid (organic acid) which is an oxidizing agent for adjusting water quality is injected from the oxidizing agent injection device 75. When the pH of the first radioactive effluent is set to, for example, acidic "4.5", a predetermined amount of dilute nitric acid aqueous solution is used from the acid injection device 56, and the reducing agent supply device 85 of the reducing agent injection device 17 is used, for example. , Inject a predetermined amount of hydrazine, which is an alkaline reducing agent. When making the pH of the first radioactive liquid waste liquid weakly alkaline around "7", a predetermined amount of dilute nitrate aqueous solution, a predetermined amount of sodium hydroxide, a predetermined amount of hydrazine and a predetermined amount of oxalic acid are injected. Increase the injection amount of hydrazine slightly more than the injection amount of oxalic acid. To make the pH of the first radioactive liquid waste solution weakly acidic near "7", inject a predetermined amount of dilute nitrate aqueous solution, a predetermined amount of sodium hydroxide, a predetermined amount of hydrazine and a predetermined amount of oxalic acid, and oxalic acid. The injection volume of hydrazine is slightly larger than the injection volume of hydrazine.
　α核種を含む第一放射性廃液のｐＨを４以上８未満の範囲内のｐＨに調節する場合において、第一放射性廃液の酸化還元電位を調整する場合には、還元剤注入装置１７における酸化還元電位調整剤供給装置８９の酸化還元電位調整剤槽９０内の酸化還元電位調整剤水溶液、例えば、アスコルビン酸水溶液を配管４５内の第一放射性廃液に注入すればよい。アスコルビン酸水溶液の注入量は、弁９１の開度制御により調節される。アスコルビン酸水溶液を注入すると、第一放射性廃液のｐＨは酸性側に変化する。このため、アスコルビン酸水溶液による第一放射性廃液のｐＨの酸性側への変化を、アルカリ性還元剤である、例えば、ヒドラジン水溶液を、還元剤注入装置５４の還元剤供給装置８５によって第一放射性廃液に注入することにより補い、第一放射性廃液のｐＨを上記の所定のｐＨ値に調整すればよい。 When adjusting the pH of the first radioactive liquid containing α nuclei to a pH within the range of 4 or more and less than 8, and adjusting the redox potential of the first radioactive liquid, the redox potential in the reducing agent injection device 17 The redox potential adjusting agent aqueous solution in the redox potential adjusting agent tank 90 of the adjusting agent supply device 89, for example, the ascorbic acid aqueous solution may be injected into the first radioactive liquid waste in the pipe 45. The injection amount of the ascorbic acid aqueous solution is adjusted by controlling the opening degree of the valve 91. When an aqueous ascorbic acid solution is injected, the pH of the first radioactive liquid waste changes to the acidic side. Therefore, the change in pH of the first radioactive liquid by the ascorbic acid aqueous solution to the acidic side is made into the first radioactive liquid by the reducing agent supply device 85 of the reducing agent injection device 54, for example, the hydrazine aqueous solution which is an alkaline reducing agent. It may be supplemented by injecting, and the pH of the first radioactive effluent may be adjusted to the above-mentioned predetermined pH value.
　酸の注入は、酸注入装置５６の酸槽５７内の希硝酸水溶液を、弁５８を開くことにより注入配管５９Ａ及び４２を通して配管４５内に注入することによって行われる。希硝酸水溶液の注入量は、弁５８の開度を制御することによって調節される。アルカリの注入は、アルカリ注入装置７９のアルカリ槽８０内の水酸化ナトリウム水溶液を、弁８１を開くことにより注入配管８２及び４２を通して配管４５内に注入することによって行われる。水酸化ナトリウム水溶液の注入量は、弁８１の開度を制御することによって調節される。 The acid is injected by injecting the dilute nitric acid aqueous solution in the acid tank 57 of the acid injection device 56 into the pipe 45 through the injection pipes 59A and 42 by opening the valve 58. The injection amount of the dilute nitric acid aqueous solution is adjusted by controlling the opening degree of the valve 58. Alkali injection is performed by injecting the sodium hydroxide aqueous solution in the alkali tank 80 of the alkali injection device 79 into the pipe 45 through the injection pipes 82 and 42 by opening the valve 81. The injection amount of the sodium hydroxide aqueous solution is adjusted by controlling the opening degree of the valve 81.
　アルカリ性還元剤の注入は、還元剤注入装置１７における還元剤供給装置８５の還元剤槽８６内のヒドラジン水溶液を、弁８７を開くことにより注入配管８８及び配管９３を通して混合槽１７Ａに供給し、さらに、混合槽１７Ａから注入配管４２を通して配管４５内に注入することによって行われる。このとき、弁４１は開いている。ヒドラジン水溶液の注入量は、弁８７の開度を制御することによって調節される。酸化還元電位調整剤水溶液の注入は、還元剤注入装置５４における酸化還元電位調整剤供給装置８９の酸化還元電位調整剤槽９０内のアスコルビン酸水溶液を、弁９１を開くことにより注入配管９２及び配管９３を通して混合槽１７Ａに供給し、さらに、混合槽１７Ａから注入配管４２を通して配管４５内に注入することによって行われる。このときも、弁５６は開いている。アスコルビン酸水溶液の注入量は、弁９１の開度を制御することによって調節される。水質調整用酸化剤の注入は、酸化剤注入装置７５の酸化剤槽７６内のシュウ酸水溶液を、弁７７を開くことにより注入配管７８及び４２を通して配管４５内に注入することによって行われる。シュウ酸水溶液の注入量は、弁７７の開度を制御することによって調節される。 To inject the alkaline reducing agent, the hydrazine aqueous solution in the reducing agent tank 86 of the reducing agent supply device 85 in the reducing agent injection device 17 is supplied to the mixing tank 17A through the injection pipe 88 and the pipe 93 by opening the valve 87, and further. , Is performed by injecting into the pipe 45 from the mixing tank 17A through the injection pipe 42. At this time, the valve 41 is open. The injection amount of the hydrazine aqueous solution is adjusted by controlling the opening degree of the valve 87. To inject the redox potential adjusting agent aqueous solution, the ascorbic acid aqueous solution in the redox potential adjusting agent tank 90 of the redox potential adjusting agent supply device 89 in the reducing agent injection device 54 is injected into the injection pipe 92 and the pipe by opening the valve 91. This is performed by supplying the mixture to the mixing tank 17A through 93, and further injecting the mixture from the mixing tank 17A into the pipe 45 through the injection pipe 42. At this time as well, the valve 56 is open. The injection amount of the ascorbic acid aqueous solution is adjusted by controlling the opening degree of the valve 91. The water quality adjusting oxidant is injected by injecting the oxalic acid aqueous solution in the oxidant tank 76 of the oxidant injection device 75 into the pipe 45 through the injection pipes 78 and 42 by opening the valve 77. The injection amount of the oxalic acid aqueous solution is adjusted by controlling the opening degree of the valve 77.
　ヒドラジン水溶液及びアスコルビン酸水溶液の両者を第一放射性廃液に注入する場合には、還元剤供給装置８５からのヒドラジン水溶液及び酸化還元電位調整剤供給装置８９からのアスコルビン酸水溶液のそれぞれを、混合槽１７Ａに供給して混合し、混合されたヒドラジン水溶液及びアスコルビン酸水溶液を混合槽１７Ａから注入配管４２を通して配管４５内に注入すればよい。 When both the hydrazine aqueous solution and the ascorbic acid aqueous solution are injected into the first radioactive waste liquid, the hydrazine aqueous solution from the reducing agent supply device 85 and the ascorbic acid aqueous solution from the oxidation-reduction potential adjuster supply device 89 are each mixed in the mixing tank 17A. The hydrazine aqueous solution and the ascorbic acid aqueous solution may be injected into the pipe 45 from the mixing tank 17A through the injection pipe 42.
　本実施例で、前述のように、水質調整装置５４による配管４５へのｐＨ調整剤の注入によって水質が調整された配管４５内の第一放射性廃液のｐＨが、ｐＨ計４９Ａで測定される。ｐＨ計４９ＡのｐＨ測定値に基づいて、配管４５への注入が必要なｐＨ調整剤を供給するｐＨ調整剤注入装置５４の該当する注入装置（還元剤注入装置１７、酸注入装置５６、酸化剤注入装置７５及びアルカリ注入装置７９のうちの少なくとも一つの注入装置）の弁の開度を制御し、第一放射性廃液のｐＨが所定の値になるように、該当する注入装置から配管４５へのｐＨ調整剤の注入量を調節する。 In this embodiment, as described above, the pH of the first radioactive liquid waste liquid in the pipe 45 whose water quality has been adjusted by injecting the pH adjusting agent into the pipe 45 by the water quality adjusting device 54 is measured by a pH meter 49A. Corresponding injection device (reducing agent injection device 17, acid injection device 56, oxidant) of the pH adjuster injection device 54 that supplies the pH adjuster that needs to be injected into the pipe 45 based on the pH measurement value of the pH meter 49A. The opening of the valve of the injection device 75 and at least one of the alkali injection devices 79) is controlled, and the pH of the first radioactive liquid waste liquid is adjusted to a predetermined value from the corresponding injection device to the pipe 45. Adjust the injection amount of the pH adjuster.
　廃液分解装置１３から配管４５に排出された、水質調整が行われる前の第一放射性廃液のｐＨは、例えば、６である。配管４５内を流れるｐＨ６の第一放射性廃液が、注入配管４２と配管４５の接続点に到達したとき、ｐＨ調整剤が水質調整装置５４から注入配管４２を通してその第一放射性廃液に注入される。ｐＨ調整剤の注入により、第一放射性廃液のｐＨは、４以上８未満の範囲内の、例えば、７．８に調整される。第一放射性廃液のｐＨを７．８にする場合には、アルカリ注入装置７９のアルカリ槽８０内の水酸化ナトリウム水溶液を、所定量、弁８１を開くことにより注入配管８２及び４２を通して配管４５内に注入する。さらに、酸注入装置５６の酸槽５７内の希硝酸水溶液を、所定量、弁５８を開くことにより注入配管５９Ａ及び４２を通して配管４５内に注入し、還元剤供給装置８５の還元剤槽８６内のヒドラジン水溶液を、所定量、弁８７を開くことにより注入配管４２を通して配管４５内に注入する。このｐＨ調整は、例えば、水酸化ナトリウム水溶液及び希硝酸水溶液を水酸化ナトリウムの注入量が若干多くなるよう注入して第一放射性廃液のｐＨを中性の７よりも少し大きくし、第一放射性廃液のｐＨが７．８になるように、ヒドラジン水溶液を注入することにより行われる。また、酸化還元電位の調整を行う場合には、酸化還元電位調整剤供給装置８９の酸化還元電位調整剤槽９０内のアスコルビン酸水溶液を、弁９１を開くことにより注入配管４２を通して配管４５内に注入する。このような各ｐＨ調整剤の注入量の調節は、ｐＨ計４９Ａで測定された第一放射性廃液のｐＨの測定値に基づいて弁５８，７７，８１，８７及び９２のうちの該当する弁の開度を制御することによって行われる。このとき、酸化剤注入装置７５の弁７７は閉じている。 The pH of the first radioactive liquid waste discharged from the waste liquid decomposition device 13 to the pipe 45 before the water quality is adjusted is, for example, 6. When the first radioactive liquid having a pH of 6 flowing in the pipe 45 reaches the connection point between the injection pipe 42 and the pipe 45, the pH adjuster is injected from the water quality adjusting device 54 into the first radioactive liquid through the injection pipe 42. By injecting a pH adjuster, the pH of the first radioactive liquid waste is adjusted to a range of 4 or more and less than 8, for example, 7.8. When the pH of the first radioactive liquid waste is set to 7.8, a predetermined amount of the sodium hydroxide aqueous solution in the alkaline tank 80 of the alkaline injection device 79 is passed through the injection pipes 82 and 42 by opening the valve 81, and the inside of the pipe 45 is filled. Inject into. Further, the dilute aqueous nitrate solution in the acid tank 57 of the acid injection device 56 is injected into the pipe 45 through the injection pipes 59A and 42 by opening the valve 58 in a predetermined amount, and is injected into the reducing agent tank 86 of the reducing agent supply device 85. The hydrazine aqueous solution of No. 1 is injected into the pipe 45 through the injection pipe 42 by opening the valve 87 in a predetermined amount. In this pH adjustment, for example, an aqueous solution of sodium hydroxide and an aqueous solution of dilute nitric acid are injected so that the injection amount of sodium hydroxide is slightly increased to make the pH of the first radioactive waste liquid slightly higher than that of neutral 7, and the first radioactive solution is used. This is done by injecting an aqueous hydrazine solution so that the pH of the waste liquid is 7.8. When adjusting the redox potential, the ascorbic acid aqueous solution in the redox potential adjusting agent tank 90 of the redox potential adjusting agent supply device 89 is passed through the injection pipe 42 into the pipe 45 by opening the valve 91. inject. Such adjustment of the injection amount of each pH adjusting agent is performed on the corresponding valve of valves 58, 77, 81, 87 and 92 based on the measured value of the pH of the first radioactive liquid solution measured by the pH meter 49A. This is done by controlling the opening degree. At this time, the valve 77 of the oxidant injection device 75 is closed.
　以上に述べた、α核種のコロイド生成工程Ｓ５において、水質調整装置５４により実施される第一放射性廃液の水質調整、例えば、第一放射性廃液のｐＨ調整は、後述の第二放射性廃液に対しても実施される。 In the above-mentioned α-nuclide colloid production step S5, the water quality adjustment of the first radioactive liquid waste carried out by the water quality adjusting device 54, for example, the pH adjustment of the first radioactive liquid waste is performed with respect to the second radioactive liquid waste described later. Will also be implemented.
　第一放射性廃液のｐＨを７．８にする場合には、水酸化ナトリウム水溶液を第一放射性廃液のｐＨを８以上の、例えば、８にし、その後、酸化剤注入装置７５の酸化剤槽７６内の、例えば、シュウ酸をｐＨ８の第一放射性廃液に注入して、第一放射性廃液のｐＨを７．８にしてもよい。ただし、この場合には、シュウ酸の注入により第一放射性廃液のｐＨが８未満の７．８になるまで、第一放射性廃液のｐＨが８未満を一時的に越えるため、第一放射性廃液に含まれるＵ，Ｐｕ及びＮｐのそれぞれはコロイド及び固形分にならなくイオンの状態のままである。イオン状態のＵ，Ｐｕ及びＮｐのそれぞれは、フィルタ６６で除去されず、α核種除去装置１４内に流入する。このため、希硝酸及び水酸化ナトリウムのうちの少なくとも一つを注入することによって第一放射性廃液のｐＨが４以上８未満の範囲内のｐＨ値になるように調整し、その後、還元剤及び水質調整用酸化剤のうちの少なくとも一つを注入することによって第一放射性廃液のｐＨを目標のｐＨ値に調整するとよい。 When the pH of the first radioactive liquid waste is set to 7.8, the pH of the first radioactive liquid waste solution is set to 8 or more, for example, 8, and then the inside of the oxidizing agent tank 76 of the oxidizing agent injection device 75. For example, oxalic acid may be injected into the first radioactive liquid waste having a pH of 8 to bring the pH of the first radioactive liquid waste liquid to 7.8. However, in this case, the pH of the first radioactive liquid temporarily exceeds less than 8 until the pH of the first radioactive liquid becomes 7.8, which is less than 8, due to the injection of oxalic acid. Each of the contained U, Pu and Np remains ionic rather than colloidal and solid. Each of the ionic states U, Pu and Np is not removed by the filter 66, but flows into the α-nuclide removing device 14. Therefore, by injecting at least one of dilute nitric acid and sodium hydroxide, the pH of the first radioactive liquid waste is adjusted to a pH value within the range of 4 or more and less than 8, and then the reducing agent and water quality are adjusted. The pH of the first radioactive liquid waste may be adjusted to the target pH value by injecting at least one of the adjusting oxidizing agents.
　酸である、例えば、希硝酸及びアルカリである、例えば、水酸化ナトリウムは、放射性廃液のｐＨ及び酸化還元電位を大きく変化させることができ、還元剤である、例えば、ヒドラジン及び水質調整用還元剤である、例えば、シュウ酸によれば、希硝酸及び水酸化ナトリウムよりも放射性廃液のｐＨ及び酸化還元電位の変化が小さくなる。 Acids, such as dilute nitrates and alkalis, such as sodium hydroxide, can significantly change the pH and redox potential of radioactive effluents and are reducing agents such as hydrazine and water quality adjusting reducing agents. For example, according to oxalic acid, the change in pH and redox potential of the radioactive effluent is smaller than that of dilute nitric acid and sodium hydroxide.
　水質調整が行われて該当するｐＨ調整剤（例えば、水酸化ナトリウム、希硝酸及びヒドラジン）を含む第一放射性廃液のｐＨが、４以上８未満の範囲内の値に調整されると、第一放射性廃液に含まれるα核種のうちＵ，Ｐｕ及びＮｐのそれぞれのコロイド及び固形分が第一放射性廃液内で生成されて、第一放射性廃液内に析出する。第一放射性廃液のｐＨが４以上８未満の範囲内の値に調整された場合でも、α核種のうちＡｍ及びＣｍは、コロイド及び固形分にならなくイオンのままである。 When the water quality is adjusted and the pH of the first radioactive liquid waste containing the corresponding pH adjuster (for example, sodium hydroxide, dilute nitrate and hydrazine) is adjusted to a value within the range of 4 or more and less than 8, the first Of the α-nuclides contained in the radioactive waste liquid, the colloids and solids of U, Pu and Np are generated in the first radioactive liquid waste and precipitated in the first radioactive liquid waste. Even when the pH of the first radioactive liquid waste is adjusted to a value in the range of 4 or more and less than 8, Am and Cm of α nuclides do not become colloids and solids and remain ions.
　その後、α核種のコロイド除去工程Ｓ６が実施される。このα核種のコロイド除去工程Ｓ６において、ｐＨが上記の範囲内に調整された第一放射性廃液はフィルタ６６に供給される。前述の水質調整によって生成された、第一放射性廃液に含まれている粒径の大きなコロイド及び固形分は、フィルタ６６内のμｍオーダー以下の孔径を有する膜を用いたクロスフローフィルタ方式によりろ過され、その膜によって除去される。すなわち、粒径の大きなコロイド及び固形分はフィルタ６６によって除去される。 After that, the colloid removal step S6 of the α nuclide is carried out. In the colloid removal step S6 of the α-nuclide, the first radioactive liquid waste whose pH is adjusted within the above range is supplied to the filter 66. The colloids and solids having a large particle size contained in the first radioactive liquid waste produced by the above-mentioned water quality adjustment are filtered by a cross-flow filter method using a membrane having a pore size of μm or less in the filter 66. , Removed by its membrane. That is, colloids and solids having a large particle size are removed by the filter 66.
　フィルタ６６を通過した第一放射性廃液内に残っているα核種の量、特に、Ｕ，Ｐｕ及びＮｐのそれぞれの量が著しく低減される。フィルタ６６を通過した第一放射性廃液は、Ｕ，Ｐｕ及びＮｐのそれぞれの、フィルタ６６で除去できない粒径が小さいコロイド及び固形分、Ｕ，Ｐｕ及びＮｐのそれぞれのイオン、及びα核種であるＡｍ及びＣｍのそれぞれのイオンを含んでいる。フィルタ６６を通過したｐＨ７．８の第一放射性廃液は、α核種除去装置１４内のスペース領域１５に流入する。 The amount of α-nuclide remaining in the first radioactive liquid waste that has passed through the filter 66, particularly the amount of each of U, Pu and Np, is significantly reduced. The first radioactive liquid waste that has passed through the filter 66 is U, Pu, and Np, which are colloids and solids having a small particle size that cannot be removed by the filter 66, ions of U, Pu, and Np, and Am, which is an α nuclide. And Cm of each ion. The first radioactive liquid liquid having a pH of 7.8 that has passed through the filter 66 flows into the space region 15 in the α-nuclide removing device 14.
　フィルタ６６から排出されたα核種の濃度が所定濃度以下に低減された第一放射性廃液の一部は、配管６７を通して戻り配管３６に戻される。なお、フィルタ６６から排出された第一放射性廃液のα核種の濃度は、α核種濃度計６５によって測定される。配管６７を通して戻り配管３６に戻された、α核種の濃度が所定濃度以下に低減された第一放射性廃液を、洗浄液供給タンク６から化学反応槽４に供給して再利用することにより、放射性廃液の排出量を低減することができる。 A part of the first radioactive liquid waste in which the concentration of α-nuclide discharged from the filter 66 is reduced to a predetermined concentration or less is returned to the return pipe 36 through the pipe 67. The concentration of α-nuclide in the first radioactive liquid waste discharged from the filter 66 is measured by an α-nuclide concentration meter 65. The first radioactive liquid waste in which the concentration of α-nuclide is reduced to a predetermined concentration or less, which has been returned to the return pipe 36 through the pipe 67, is supplied from the cleaning liquid supply tank 6 to the chemical reaction tank 4 and reused. Emissions can be reduced.
　α核種のイオン除去工程Ｓ７では、まず、フィルタ６６から排出された第一放射性廃液をα核種除去装置１４に供給するとき、フェライト粒子をα核種吸着材注入装置６９によりα核種除去装置１４内のスペース領域１５に注入する。具体的には、α核種吸着材注入装置６９において、弁７２Ａを開いて吸着材槽７０内のフェライト粒子を、注入配管７１を通してそのスペース領域１５に注入する。 In the α-nuclide ion removal step S7, first, when the first radioactive liquid discharged from the filter 66 is supplied to the α-nuclide removal device 14, ferrite particles are supplied into the α-nuclide removal device 14 by the α-nuclide adsorbent injection device 69. Inject into the space area 15. Specifically, in the α-nuclide adsorbent injection device 69, the valve 72A is opened to inject the ferrite particles in the adsorbent tank 70 into the space region 15 through the injection pipe 71.
　α核種除去装置１４に流入する第一放射性廃液のｐＨが、α核種のコロイド生成工程Ｓ５において、４以上８未満の範囲内の７．８に調整されているため、第一放射性廃液に含まれる、価数が「３～５」である各α核種（Ｕ，Ｐｕ，Ｎｐ，Ａｍ及びＣｍ）の価数が、スペース領域１５内で「３」に調整される。第一放射性廃液に含まれる、価数が「３」に調整された各α核種は、アルカリ性還元剤（例えば、ヒドラジン）の存在下で、領域１６においてフェライト粒子に効率良く吸着されて除去される（α核種のイオン除去工程Ｓ７）。図４において、α核種除去装置１４内に示される〇はα核種吸着材（フェライト粒子）であり、◇はα核種である。第一放射性廃液に含まれる、フィルタ６６を通過した粒径の小さいコロイド及び固形分は、フェライト粒子によって除去される。α核種除去装置１４に設けられた磁化率測定装置４９Ｂは、α核種除去装置１４内にフェライトが存在しているかを検出する。 Since the pH of the first radioactive liquid flowing into the α-nuclide removing device 14 is adjusted to 7.8 in the range of 4 or more and less than 8 in the α-nuclide colloid generation step S5, it is included in the first radioactive liquid. , The valence of each α nuclide (U, Pu, Np, Am and Cm) having a valence of "3 to 5" is adjusted to "3" within the space region 15. Each α-nuclide whose valence is adjusted to “3” contained in the first radioactive liquid waste is efficiently adsorbed and removed by ferrite particles in the region 16 in the presence of an alkaline reducing agent (for example, hydrazine). (Ion removal step S7 of α nuclide). In FIG. 4, ◯ shown in the α nuclide removing device 14 is an α nuclide adsorbent (ferrite particle), and ◇ is an α nuclide. The colloids and solids having a small particle size that have passed through the filter 66 contained in the first radioactive liquid waste are removed by the ferrite particles. The magnetic susceptibility measuring device 49B provided in the α-nuclide removing device 14 detects whether ferrite is present in the α-nuclide removing device 14.
　ここで、放射性廃液内のα核種の除去率に及ぼすα核種吸着材の比表面積の影響を、図１０を参照して説明する。図１０は、α核種吸着材であるフェライト粒子のサイズと、フェライト粒子１ｇ当たりのα核種の吸着量の関係を示している。図１０では、フェライト粒子のサイズを粒状（粒径≧１００μｍ）及び微粉状（粒径≦１μｍ）とし、粒状（粒径≧１００μｍ）及び微粉状（粒径≦１μｍ）のそれぞれのα核種の吸着量を比較している。図１０に示すように、フェライト粒子を微粉状とした場合には、フェライト粒子を粒状とした場合と比較して、フェライト粒子１ｇ当りのα核種の吸着量が１００倍以上に向上する。 Here, the effect of the specific surface area of the α-nuclide adsorbent on the removal rate of α-nuclide in the radioactive liquid waste will be described with reference to FIG. FIG. 10 shows the relationship between the size of the ferrite particles, which are the α-nuclide adsorbent, and the amount of α-nuclide adsorbed per 1 g of the ferrite particles. In FIG. 10, the sizes of the ferrite particles are granular (particle size ≥ 100 μm) and fine powder (particle size ≤ 1 μm), and adsorption of each of the granular (particle size ≥ 100 μm) and fine powder (particle size ≤ 1 μm) α nuclides. The amount is being compared. As shown in FIG. 10, when the ferrite particles are in the form of fine powder, the amount of α-nuclide adsorbed per 1 g of the ferrite particles is improved 100 times or more as compared with the case where the ferrite particles are in the form of granules.
　α核種除去装置１４内でα核種が吸着されたフェライト粒子は、使用済みフェライト粒子として、第一放射性廃液と共に、α核種除去装置１４から排出されて、配管４６を通してα核種吸着材分離装置７２に供給される。α核種吸着材分離装置７２において、第一放射性廃液に含まれてα核種が吸着されたフェライト粒子が、例えば、μｍオーダー以下の孔径を有する膜を用いたクロスフローフィルタ方式によるろ過により、第一放射性廃液から分離される（吸着材分離工程Ｓ８）。α核種吸着材分離装置７２でのフェライト粒子の分離は、クロスフローフィルタ方式の替りにデッドエンドフィルタ方式で行ってもよい。α核種が吸着されたフェライト粒子が分離された第一放射性廃液は、α核種吸着材分離装置７２から配管４６に排出される。α核種吸着材分離装置７２において、膜によってろ過されたろ液は、配管６８を通して戻り配管３６に供給される。 The ferrite particles on which the α-nuclide is adsorbed in the α-nuclide removing device 14 are discharged from the α-nuclide removing device 14 together with the first radioactive liquid waste as used ferrite particles, and are discharged to the α-nuclide adsorbent separating device 72 through the pipe 46. Be supplied. In the α-nuclide adsorbent separator 72, the ferrite particles in which the α-nuclide is adsorbed contained in the first radioactive liquid liquid are first filtered by a cross-flow filter method using, for example, a film having a pore size of μm order or less. It is separated from the radioactive liquid waste (adsorbent separation step S8). Ferrite particles may be separated by the α-nuclide adsorbent separating device 72 by a dead-end filter method instead of the cross-flow filter method. The first radioactive liquid waste from which the ferrite particles on which the α-nuclide is adsorbed is separated is discharged from the α-nuclide adsorbent separating device 72 to the pipe 46. In the α-nuclide adsorbent separating device 72, the filtrate filtered by the membrane is supplied to the return pipe 36 through the pipe 68.
　α核種のコロイド生成工程Ｓ５において、第一放射性廃液（または後述の第二放射性廃液）に注入される酸（例えば、希硝酸）及びアルカリ（例えば、水酸化ナトリウム）は分解不可能なｐＨ調整剤であり、アルカリ性還元剤（例えば、ヒドラジン）及び酸化還元電位調整剤（例えば、アスコルビン酸）は分解可能なｐＨ調整剤である。もし、α核種のコロイド生成工程Ｓ５において、第一放射性廃液に水質調整用酸化剤（例えば、シュウ酸）を注入した場合には、この水質調整用酸化剤（例えば、シュウ酸）も分解可能なｐＨ調整剤である。 In the α nuclei colloid production step S5, the acid (for example, dilute nitrate) and alkali (for example, sodium hydroxide) injected into the first radioactive liquid (or the second radioactive liquid described later) are indestructible pH adjusters. The alkaline reducing agent (eg, hydrazine) and the oxidation-reducing potential regulator (eg, ascorbic acid) are degradable pH regulators. If a water quality adjusting oxidant (for example, oxalic acid) is injected into the first radioactive liquid in the α-nuclide colloid production step S5, the water quality adjusting oxidant (for example, oxalic acid) can also be decomposed. It is a pH adjuster.
　本実施例では、α核種のコロイド生成工程Ｓ５において、第一放射性廃液のｐＨを７．８に調整するために、前述したように、分解不可能なｐＨ還元剤である希硝酸及び水酸化ナトリウムが第一放射性廃液に注入されているが、及び分解可能なヒドラジン及びアスコルビン酸が第一放射性廃液に注入されているので、ｐＨ調整剤判定工程Ｓ９における「ｐＨ調整剤が分解可能なｐＨ調整剤であるか」の判定が「ＹＥＳ」になり、α核種除去装置１４のフェライト粒子によりα核種、コロイド性の物質及び固形分が除去された、ヒドラジン及びアスコルビン酸を含む第一放射性廃液は、α核種吸着材分離装置７２から、配管４６を通して分解装置１０７に導かれる。 In this example, in order to adjust the pH of the first radioactive liquid to 7.8 in the α-nuclide colloid production step S5, as described above, dilute nitrate and sodium hydroxide which are non-decomposable pH reducers are used. Is injected into the first radioactive effluent, and since decomposable hydrazine and ascorbic acid are injected into the first radioactive effluent, the “pH adjuster degradable pH adjuster” in the pH adjuster determination step S9 The determination of "is" is "YES", and the first radioactive liquid containing hydrazine and ascorbic acid from which α nuclides, colloidal substances and solids have been removed by the ferrite particles of the α nuclide removal device 14 is α. The nuclide adsorbent separating device 72 is guided to the decomposition device 107 through the pipe 46.
　第一放射性廃液に含まれるヒドラジン及びアスコルビン酸は、分解装置１０７内で分解される。すなわち、弁１１１を開いて、薬液タンク１０９内の過酸化水素を、供給配管１１０を通して分解装置１０７に供給する。分解装置１０７内で、活性炭触媒及び過酸化水素の作用により、第一放射性廃液に含まれるヒドラジンが窒素及び水に分解され、アスコルビン酸が酸素及び水に分解される（分解可能なｐＨ調整剤の分解工程Ｓ１０）。分解装置１０７から排出された、α核種及びヒドラジンを含んでいなく希硝酸及び水酸化ナトリウムを含んでいる第一放射性廃液は、配管４６を通して処理水回収タンク１８に導かれる。 Hydrazine and ascorbic acid contained in the first radioactive liquid waste are decomposed in the decomposition apparatus 107. That is, the valve 111 is opened to supply the hydrogen peroxide in the chemical solution tank 109 to the decomposition device 107 through the supply pipe 110. In the decomposition apparatus 107, the action of the activated carbon catalyst and hydrogen peroxide decomposes hydrazine contained in the first radioactive liquid waste into nitrogen and water, and ascorbic acid into oxygen and water (a decomposable pH adjuster). Disassembly step S10). The first radioactive liquid waste containing no α-nuclide and hydrazine but containing dilute nitric acid and sodium hydroxide discharged from the decomposition apparatus 107 is guided to the treated water recovery tank 18 through the pipe 46.
　α核種のコロイド生成工程Ｓ５において、ｐＨを７にするために希硝酸水溶液及び水酸化ナトリウムが第一放射性廃液に注入された場合には、第一放射性廃液には分解可能なｐＨ調整剤（ヒドラジン及びシュウ酸）が含まれていないため、ｐＨ調整剤判定工程Ｓ９の判定が「Ｎｏ」になる。このため、α核種除去装置１４から排出された、希硝酸及び水酸化ナトリウムを含む第一放射性廃液は、分解装置１０７に導かれるが、この場合には弁１１１が閉じられているため、薬液タンク１０９内の過酸化水素が分解装置１０７に供給されない。希硝酸及び水酸化ナトリウムを含む第一放射性廃液は、そのまま、分解装置１０７から排出され、処理水回収タンク１８に導かれる。 In the α-nuclide colloid production step S5, when a dilute aqueous nitric acid solution and sodium hydroxide are injected into the primary radioactive effluent to bring the pH to 7, a pH adjuster (hydrazine) that can be decomposed into the primary radioactive effluent is used. And oxalic acid) are not contained, so that the determination in the pH adjuster determination step S9 is “No”. Therefore, the first radioactive liquid waste containing dilute nitric acid and sodium hydroxide discharged from the α-nuclide removal device 14 is guided to the decomposition device 107, but in this case, since the valve 111 is closed, the chemical liquid tank. The hydrogen peroxide in 109 is not supplied to the decomposition apparatus 107. The first radioactive liquid waste containing dilute nitric acid and sodium hydroxide is discharged from the decomposition apparatus 107 as it is and guided to the treated water recovery tank 18.
　第一放射性廃液のｐＨを、例えば、６にする場合には、α核種のコロイド生成工程Ｓ５において、希硝酸水溶液及び水酸化ナトリウム水溶液と共に水質調整用酸化剤（例えば、シュウ酸）を第一放射性廃液に注入する。ｐＨが６である第一放射性廃液内で生成されるＵ，Ｐｕ及びＮｐのそれぞれの粒径の大きなコロイド及び固形分は、フィルタ６６で除去される（α核種のコロイド除去工程Ｓ６）。フィルタ６６から排出されてそのコロイド及び固形分が除去された第一放射性廃液がα核種除去装置１４に供給されて、第一放射性廃液に含まれるα核種のイオンがα核種除去装置１４内でフェライト粒子に吸着されて除去される（α核種のイオン除去工程Ｓ７）。 When the pH of the first radioactive effluent is set to 6, for example, in the colloid production step S5 of the α-nuclide, the water quality adjusting oxidizing agent (for example, oxalic acid) is first radioactive together with the dilute nitric acid aqueous solution and the sodium hydroxide aqueous solution. Inject into the waste liquid. Colloids and solids having large particle sizes of U, Pu and Np produced in the first radioactive liquid waste having a pH of 6 are removed by the filter 66 (colloid removal step S6 of α-nuclide). The first radioactive effluent discharged from the filter 66 and from which the colloid and solid content have been removed is supplied to the α-nuclide removing device 14, and the α-nuclide ions contained in the first radioactive effluent are ferrite in the α-nuclide removing device 14. It is adsorbed on the particles and removed (alpha nuclide ion removal step S7).
　第一放射性廃液に含まれるフェライト粒子がα核種吸着材分離装置７２によって分離され、フェライト粒子を含まないｐＨが６である第一放射性廃液を対象に、ｐＨ調整剤判定工程Ｓ９の判定が行われる。ｐＨが６である第一放射性廃液には、分解可能なｐＨ調整剤として水質調整用酸化剤（例えば、シュウ酸）が含まれているため、ｐＨ調整剤判定工程Ｓ９の判定が「ＹＥＳ」になる。その第一放射性廃液は、分解装置１０７に供給され、分解装置１０７内で活性炭触媒及び薬液タンク１０９内の過酸化水素の作用によって、第一放射性廃液に含まれる水質調整用酸化剤（例えば、シュウ酸）が分解される。例えば、シュウ酸は、分解装置１０７内で二酸化炭素及び水に分解される。第一放射性廃液に含まれる水質調整用酸化剤（例えば、シュウ酸）の分解によって、第一放射性廃液の量を低減できる。 The ferrite particles contained in the first radioactive liquid waste are separated by the α-nuclide adsorbent separator 72, and the pH adjuster determination step S9 is determined for the first radioactive liquid liquid containing no ferrite particles and having a pH of 6. .. Since the first radioactive liquid waste having a pH of 6 contains a water quality adjusting oxidizing agent (for example, oxalic acid) as a decomposable pH adjusting agent, the determination in the pH adjusting agent determination step S9 is "YES". Become. The first radioactive liquid waste is supplied to the decomposition device 107, and the action of hydrogen peroxide in the activated carbon catalyst and the chemical liquid tank 109 in the decomposition device 107 causes an oxidizing agent for adjusting the water quality (for example, Shu) contained in the first radioactive liquid waste. Acid) is decomposed. For example, oxalic acid is decomposed into carbon dioxide and water in the decomposition apparatus 107. The amount of the first radioactive liquid waste can be reduced by decomposing the water quality adjusting oxidizing agent (for example, oxalic acid) contained in the first radioactive liquid waste liquid.
　前述した処理水回収タンク１８内の第一放射性廃液（ヒドラジンまたはシュウ酸が分解されて希硝酸及び水酸化ナトリウムを含む第一放射性廃液）は、移送ポンプ４７を駆動して配管４８により乾燥粉体化装置２０に供給されて紛体化される（減容工程Ｓ１１）。乾燥粉体化装置２０で生成された、α核種を含まない紛体は、配管４９を通して固化設備２１に移送されて固化容器内に充填され、その固化容器内に固化材が注入されて固化される（容器充填または固化工程Ｓ１２）。この固化容器は、密封された後、保管場所に保管される。保管されるこの固化容器内には、超半減期のα核種が存在していない。 The first radioactive liquid waste (the first radioactive liquid waste in which hydrazine or oxalic acid is decomposed and contains dilute nitrate and sodium hydroxide) in the treated water recovery tank 18 described above is dried powder by a pipe 48 by driving a transfer pump 47. It is supplied to the chemical conversion device 20 and pulverized (volume reduction step S11). The α-nucleus-free powder produced by the dry powdering apparatus 20 is transferred to the solidifying facility 21 through the pipe 49 and filled in the solidifying container, and the solidifying material is injected into the solidifying container to solidify it. (Container filling or solidification step S12). This solidified container is sealed and then stored in a storage location. There are no ultra-half-life alpha nuclides in this solidified vessel that is stored.
　ここで、第一放射性廃液に希硝酸を注入した場合には、この第一放射性廃液の粉体化により生成された粉体は硝酸及び水酸化ナトリウムを含んでおり、この粉体を固化容器内で溶融したガラスにより固化して生成されたガラス固化体も、硝酸及び水酸化ナトリウムを含んでいる。 Here, when dilute nitric acid is injected into the first radioactive liquid waste liquid, the powder produced by powdering the first radioactive liquid waste liquid contains nitric acid and sodium hydroxide, and this powder is contained in the solidification container. The vitrified material produced by solidifying with the glass melted in (1) also contains nitric acid and sodium hydroxide.
　上述したように第一放射性廃液の処理が行われ、固化設備２１で固化が実行された状態では、まだ化学反応槽４内に、クラッドが溶解された、陽イオン交換樹脂を含む放射性有機廃棄物が、残留している。引き続き、この陽イオン交換樹脂を含む放射性有機廃棄物の処理を行う。 As described above, in the state where the first radioactive liquid waste is treated and the solidification facility 21 is solidified, the clad is still dissolved in the chemical reaction tank 4, and the radioactive organic waste containing the cation exchange resin is contained. However, it remains. Subsequently, the radioactive organic waste containing this cation exchange resin will be treated.
　移送ポンプ３２の駆動によって、４０～４００ｇ／Ｌ程度のギ酸ヒドラジン水溶液（有機酸塩水溶液）が、洗浄液供給タンク６から洗浄液供給管３３を通して、放射性有機廃棄物が残留する化学反応槽４内に連続的に供給される。ギ酸ヒドラジン水溶液のギ酸ヒドラジンの濃度は、溶液１Ｌ当たりの溶質（ギ酸ヒドラジン）の質量である。化学反応槽４に供給されるギ酸ヒドラジン水溶液は、ｐＨ７程度の中性液である。洗浄液供給タンク６へのギ酸ヒドラジン水溶液の供給は、弁２７を開くことによって、配管３０及び配管２９を通して有機酸塩槽８から行われる。弁２６及び弁２８は閉じている。 By driving the transfer pump 32, an aqueous solution of hydrazine formate (organic acid salt aqueous solution) of about 40 to 400 g / L is continuously discharged from the cleaning liquid supply tank 6 through the cleaning liquid supply pipe 33 into the chemical reaction tank 4 in which radioactive organic waste remains. Is supplied. The concentration of hydrazine formate in an aqueous solution of hydrazine formate is the mass of solute (hydrazine formate) per liter of solution. The aqueous solution of hydrazine formate supplied to the chemical reaction tank 4 is a neutral liquid having a pH of about 7. The hydrazine formate aqueous solution is supplied to the cleaning liquid supply tank 6 from the organic acid salt tank 8 through the pipe 30 and the pipe 29 by opening the valve 27. The valve 26 and the valve 28 are closed.
　放射性有機廃棄物は、化学反応槽４内でギ酸ヒドラジン水溶液と接触する。化学反応槽４内では、この接触によって、放射性有機廃棄物である陽イオン交換樹脂に吸着された、α核種であるウラン、プルトニウム、アメリシウム、ネプツニウム及びキュリウム、及びα核種以外の放射性核種であるコバルト６０、セシウム１３７、炭素１４、塩素３６のそれぞれのイオンが、ギ酸ヒドラジン水溶液中に溶離する（第二洗浄工程Ｓ２）。 The radioactive organic waste comes into contact with the aqueous solution of hydrazine formate in the chemical reaction tank 4. In the chemical reaction tank 4, the α nuclides uranium, plutonium, americium, neptunium and chlorine adsorbed on the cation exchange resin, which is a radioactive organic waste, and cobalt, which is a radionuclide other than the α nuclide, are adsorbed by this contact. The ions of 60, cesium-137, carbon-14, and chlorine-36 are eluted in the aqueous solution of hydrazine formate (second washing step S2).
　化学反応槽４内からギ酸ヒドラジン水溶液のみを回収し、回収されたギ酸ヒドラジン水溶液は、戻り配管３６を通して洗浄液供給タンク６に移送される。このとき、弁３５は開いており、弁３９は閉じている。洗浄液供給タンク６に移送されたギ酸ヒドラジン水溶液は、再び、化学反応槽４に供給され、陽イオン交換樹脂に吸着された各放射性核種の溶離に使用される。ギ酸ヒドラジン水溶液の代わりに、シュウ酸、酢酸及びクエン酸のいずれかのヒドラジン塩の水溶液を用いてもよい。これらの有機酸塩は、水素イオンよりも陽イオン交換樹脂に吸着されやすい陽イオンを生じる有機酸塩である。 Only the hydrazine formate aqueous solution is recovered from the chemical reaction tank 4, and the recovered hydrazine formate aqueous solution is transferred to the cleaning liquid supply tank 6 through the return pipe 36. At this time, the valve 35 is open and the valve 39 is closed. The hydrazine formate aqueous solution transferred to the cleaning liquid supply tank 6 is again supplied to the chemical reaction tank 4 and used for elution of each radionuclide adsorbed on the cation exchange resin. Instead of the aqueous solution of hydrazine formate, an aqueous solution of any hydrazine salt of oxalic acid, acetic acid or citric acid may be used. These organic acid salts are organic acid salts that generate cations that are more easily adsorbed on the cation exchange resin than hydrogen ions.
　放射性有機廃棄物である陽イオン交換樹脂にシュウ酸水溶液を接触させた場合では、陽イオン交換樹脂に吸着されているコバルト６０に対する除染性能（除染係数）がＤＦ４程度である。これに対して、陽イオン交換樹脂にギ酸ヒドラジン水溶液を接触させた場合では、除染性能がＤＦ２０以上となり、シュウ酸水溶液を接触させた場合よりも、除染性能が向上した。シュウ酸水溶液のみを用いてＤＦ２０以上の除染性能を得るためには、繰り返し、シュウ酸を添加する必要がある。これに対して、ギ酸ヒドラジン水溶液を用いた場合には、その繰り返しが不要となり、使用する洗浄剤の量、すなわち、シュウ酸の量を低減することができる。 When an aqueous oxalic acid solution is brought into contact with a cation exchange resin, which is a radioactive organic waste, the decontamination performance (decontamination coefficient) for cobalt-60 adsorbed on the cation exchange resin is about DF4. On the other hand, when the hydrazine formate aqueous solution was brought into contact with the cation exchange resin, the decontamination performance was DF20 or higher, and the decontamination performance was improved as compared with the case where the oxalic acid aqueous solution was brought into contact with the resin. In order to obtain decontamination performance of DF20 or higher using only the oxalic acid aqueous solution, it is necessary to add oxalic acid repeatedly. On the other hand, when the hydrazine formate aqueous solution is used, the repetition becomes unnecessary, and the amount of the cleaning agent used, that is, the amount of oxalic acid can be reduced.
　ここで、除染係数ＤＦは、（除染前の計数率）／（除染後の計数率）で算出される数値である。なお、ギ酸ヒドラジンによる除染（イオン溶離）は、シュウ酸による除染（クラッド溶解）の後に行う。よって、有機酸水溶液によるクラッドの溶解のみを実施する場合には、有機酸塩水溶液を用いたイオンの溶離は行わないため、除染係数ＤＦは、（除染前の計数率）／（クラッド溶解のみの計数率）で計算される値となる。一方、イオンの溶離も行う場合には、除染係数ＤＦは、（除染前の計数率）／（クラッド溶解及びイオン溶離の後の計数率）で計算される値となる。 Here, the decontamination coefficient DF is a numerical value calculated by (counting rate before decontamination) / (counting rate after decontamination). Decontamination with hydrazine formate (ion elution) is performed after decontamination with oxalic acid (clad dissolution). Therefore, when only the clad is dissolved with the organic acid aqueous solution, the ions are not eluted with the organic acid aqueous solution, so that the decontamination coefficient DF is (counting rate before decontamination) / (clad dissolution). It is a value calculated by the count rate of only). On the other hand, when ion elution is also performed, the decontamination coefficient DF is a value calculated by (counting rate before decontamination) / (counting rate after clad dissolution and ion elution).
　化学反応槽４内での放射性核種の溶離（第二洗浄工程Ｓ２）が終了した後、弁３５を閉じて弁３９を開き、移送ポンプ３４を駆動する。化学反応槽４内の、溶離されたα核種及びα核種以外の放射性核種を含むギ酸ヒドラジン水溶液（以下、「第二放射性廃液」とする）が、配管３６及び配管４０を通して、前述した廃液分解装置１３の廃液貯槽に移送される。 After the elution of radionuclides in the chemical reaction tank 4 (second cleaning step S2) is completed, the valve 35 is closed, the valve 39 is opened, and the transfer pump 34 is driven. The hydrazine formate aqueous solution (hereinafter referred to as "second radioactive liquid waste") containing the eluted α-nuclide and radioactive nuclides other than the α-nuclide in the chemical reaction tank 4 passes through the pipe 36 and the pipe 40 to the above-mentioned waste liquid decomposition apparatus. It is transferred to 13 waste liquid storage tanks.
　その廃液分解装置１３の廃液貯槽へのギ酸ヒドラジン水溶液の移送が終了した後、弁２５を開いて化学反応層４内に残存する放射性有機廃棄物は、配管２６によって第二受入タンク１１に導かれる。第二受入タンク１１から取り出された放射性有機廃棄物は、所定量、焼却設備１２に移送され、焼却設備１２で焼却される。焼却により生成された灰は、固化容器内でセメント等の固化剤により固化される（焼却または固化工程Ｓ３）。 After the transfer of the hydrazine formate aqueous solution to the waste liquid storage tank of the waste liquid decomposition device 13 is completed, the valve 25 is opened and the radioactive organic waste remaining in the chemical reaction layer 4 is guided to the second receiving tank 11 by the pipe 26. .. The radioactive organic waste taken out from the second receiving tank 11 is transferred to the incinerator 12 in a predetermined amount and incinerated in the incinerator 12. The ash produced by incineration is solidified by a solidifying agent such as cement in a solidifying container (incinerator or solidification step S3).
　その廃液分解装置１３の廃液貯槽へのギ酸ヒドラジン水溶液の移送が終了した後、廃液分解工程Ｓ４が実施される。この廃液分解工程Ｓ４では、オゾン供給装置５０からのオゾンが、その廃液貯槽内のギ酸ヒドラジン水溶液中に噴射される。ギ酸ヒドラジン水溶液に含まれるギ酸及びヒドラジンが、噴射されたオゾンにより分解される。ギ酸は窒素ガスと水に、また、ヒドラジンは炭酸ガスと水に分解される。廃液貯槽内に噴射されたオゾンの残り、炭酸ガス及び窒素ガスが、廃液貯槽に接続されたガス排気管５３を通してオフガス処理装置（図示せず）に供給される。 After the transfer of the hydrazine formate aqueous solution to the waste liquid storage tank of the waste liquid decomposition device 13 is completed, the waste liquid decomposition step S4 is carried out. In this waste liquid decomposition step S4, ozone from the ozone supply device 50 is injected into the hydrazine formate aqueous solution in the waste liquid storage tank. Formic acid and hydrazine contained in the aqueous solution of hydrazine formate are decomposed by the injected ozone. Formic acid is decomposed into nitrogen gas and water, and hydrazine is decomposed into carbon dioxide gas and water. The remaining ozone, carbon dioxide gas and nitrogen gas injected into the waste liquid storage tank are supplied to the off-gas treatment device (not shown) through the gas exhaust pipe 53 connected to the waste liquid storage tank.
　第二洗浄工程Ｓ２の後に実施された、廃液分解装置１３の廃液貯槽内でのギ酸及びヒドラジンの分解（廃液分解工程Ｓ４）が終了した後、その廃液貯槽へのオゾンの供給が停止されて移送ポンプ４３が駆動され、ギ酸及びヒドラジンの分解後においてその廃液貯槽内に残留する、α核種及びα核種以外の放射性核種を含む第二放射性廃液が、配管４５を通して水質調整装置５４に供給される。このとき、弁４４は開いている。 After the decomposition of formic acid and hydrazine in the waste liquid storage tank of the waste liquid decomposition apparatus 13 (waste liquid decomposition step S4), which was carried out after the second cleaning step S2, is completed, the supply of ozone to the waste liquid storage tank is stopped and transferred. The pump 43 is driven, and the second radioactive liquid containing the α-nuclide and the radionuclide other than the α-nuclide, which remains in the waste liquid storage tank after the decomposition of formic acid and hydrazine, is supplied to the water quality adjusting device 54 through the pipe 45. At this time, the valve 44 is open.
　本実施例では、第二放射性廃液に対しても、前述の第一放射性廃液と同様に、廃液分解工程Ｓ４の後にα核種のコロイド生成工程Ｓ５が実施される。水質調整装置５４によって、ｐＨ調整剤注入装置５５から注入配管４２を通して該当するｐＨ調整剤が配管４５内の第二放射性廃液に注入される。本実施例において、配管４５内の第二放射性廃液に注入されるｐＨ調整剤としては、酸、水質調整用酸化剤、還元剤及びアルカリが用いられる。ｐＨ調整剤の注入により、第二放射性廃液のｐＨは４以上８未満の範囲内のｐＨに調整される。第二放射性廃液のｐＨを４以上８未満の範囲内のｐＨにすることによって、α核種のうちＵ，ＰＵ及びＮｐのそれぞれの粒径の大きなコロイド及び固形分が第二放射性廃液内で生成される。 In this embodiment, the α-nuclide colloid production step S5 is carried out after the waste liquid decomposition step S4 for the second radioactive liquid as well as the above-mentioned first radioactive liquid. The water quality adjusting device 54 injects the corresponding pH adjusting agent from the pH adjusting agent injection device 55 through the injection pipe 42 into the second radioactive liquid waste in the pipe 45. In this embodiment, as the pH adjusting agent to be injected into the second radioactive liquid waste in the pipe 45, an acid, an oxidizing agent for adjusting water quality, a reducing agent and an alkali are used. By injecting a pH adjuster, the pH of the second radioactive liquid waste is adjusted to a pH in the range of 4 or more and less than 8. By setting the pH of the second radioactive liquid waste to the pH range of 4 or more and less than 8, colloids and solids having large particle sizes of U, PU, and Np among the α nuclides are generated in the second radioactive liquid waste. NS.
　廃液分解装置１３から配管４５に排出された、水質調整が行われる前の第二放射性廃液のｐＨは、例えば、６である。配管４５内を流れるｐＨ６の第二放射性廃液が、注入配管４２と配管４５の接続点に到達したとき、第一放射性廃液と同様に、ｐＨ調整剤が水質調整装置５４から注入配管４２を通してその第二放射性廃液に注入される。第二放射性廃液のｐＨを、４以上８未満の範囲内の、例えば、７．８にする場合には、アルカリ槽８０内の水酸化ナトリウム水溶液を、所定量、弁８１を開くことにより配管４５内に注入する。さらに、酸槽５７内の希硝酸水溶液を、所定量、弁５８を開くことにより配管４５内に注入し、還元剤槽１７Ａ内のヒドラジン水溶液を、所定量、弁４１を開くことにより配管４５内に注入する。このｐＨ調整は、例えば、水酸化ナトリウム水溶液及び希硝酸水溶液を水酸化ナトリウムの注入量が若干多くなるよう注入して第二放射性廃液のｐＨを中性の７よりも少し大きくし、第二放射性廃液のｐＨが７．８になるように、ヒドラジン水溶液を注入することにより行われる。また、酸化還元電位の調整を行う場合には、酸化還元電位調整剤供給装置８９の酸化還元電位調整剤槽９０内のアスコルビン酸水溶液を、弁９１を開くことにより注入配管４２を通して配管４５内の第二放射性廃液に注入する。このような各ｐＨ調整剤の注入量の調節は、ｐＨ計４９Ａで測定された第二放射性廃液のｐＨの測定値に基づいて弁４１，５８及び８０の内の該当する弁の開度を制御することによって行われる。このとき、酸化剤注入装置７５の弁７７は閉じている。 The pH of the second radioactive liquid waste discharged from the waste liquid decomposition device 13 to the pipe 45 before the water quality is adjusted is, for example, 6. When the second radioactive liquid of pH 6 flowing in the pipe 45 reaches the connection point between the injection pipe 42 and the pipe 45, the pH adjuster is applied from the water quality adjusting device 54 through the injection pipe 42 in the same manner as the first radioactive liquid. (Ii) Injected into radioactive liquid waste. When the pH of the second radioactive liquid waste is in the range of 4 or more and less than 8, for example, 7.8, a predetermined amount of the sodium hydroxide aqueous solution in the alkaline tank 80 is added to the pipe 45 by opening the valve 81. Inject inside. Further, the dilute nitric acid aqueous solution in the acid tank 57 is injected into the pipe 45 by opening the valve 58 in a predetermined amount, and the hydrazine aqueous solution in the reducing agent tank 17A is injected into the pipe 45 by opening the valve 41 in a predetermined amount. Inject into. In this pH adjustment, for example, an aqueous solution of sodium hydroxide and an aqueous solution of dilute nitric acid are injected so that the injection amount of sodium hydroxide is slightly increased to make the pH of the second radioactive waste liquid slightly higher than that of neutral 7, and the second radioactive solution is used. This is done by injecting an aqueous hydrazine solution so that the pH of the waste liquid is 7.8. When adjusting the redox potential, the ascorbic acid aqueous solution in the redox potential adjusting agent tank 90 of the redox potential adjusting agent supply device 89 is passed through the injection pipe 42 and into the pipe 45 by opening the valve 91. Inject into the second radioactive effluent. Such adjustment of the injection amount of each pH adjuster controls the opening degree of the corresponding valve among the valves 41, 58 and 80 based on the measured value of the pH of the second radioactive liquid solution measured by the pH meter 49A. It is done by doing. At this time, the valve 77 of the oxidant injection device 75 is closed.
　第二放射性廃液のｐＨが７．８に調整されると、第二放射性廃液に含まれているα核種のうちＵ，Ｐｕ及びＮｐのそれぞれが、コロイド及び固形分となって第二放射性廃液内に析出する。第二放射性廃液に含まれているα核種のうちＡｍ及びＣｍは、イオンのままである。Ｐｕ及びＮｐのそれぞれのコロイド及び固形分を含む第二放射性廃液は、フィルタ６６に供給される。第二放射性廃液に含まれた粒径の大きなコロイド及び固形分は、フィルタ６６内のμｍオーダー以下の孔径を有する膜を用いたクロスフローフィルタ方式によりろ過され、その膜によって除去される（α核種のコロイド除去工程Ｓ６）。 When the pH of the second radioactive liquid waste is adjusted to 7.8, U, Pu and Np of the α nuclides contained in the second radioactive liquid waste become colloids and solids, respectively, in the second radioactive liquid waste. Precipitates in. Among the α nuclides contained in the second radioactive liquid waste, Am and Cm remain ions. The second radioactive liquid waste containing the colloids and solids of Pu and Np, respectively, is supplied to the filter 66. Colloids and solids having a large particle size contained in the second radioactive liquid waste are filtered by a cross-flow filter method using a membrane having a pore size of μm or less in the filter 66 and removed by the membrane (α-nuclide). Colloid removal step S6).
　フィルタ６６を通過して、フィルタ６６で除去できない粒径が小さい、Ｕ，Ｐｕ及びＮｐのそれぞれのコロイド及び固形分、Ｕ，Ｐｕ及びＮｐのそれぞれのイオン、及びα核種であるＡｍ及びＣｍのそれぞれのイオンを含むｐＨ７．８の第二放射性廃液は、α核種除去装置１４内のスペース領域１５に流入する。第一放射性廃液の場合と同様に、フェライト粒子をα核種吸着材注入装置６９からそのスペース領域１５に注入する。 The colloids and solids of U, Pu and Np, the ions of U, Pu and Np, and the α nuclides Am and Cm, which have a small particle size that cannot be removed by the filter 66 after passing through the filter 66, respectively. The second radioactive liquid liquid having a pH of 7.8 containing the ions of the above flows into the space region 15 in the α-nuclide removing device 14. As in the case of the first radioactive liquid waste, the ferrite particles are injected from the α-nuclide adsorbent injection device 69 into the space region 15.
　第二放射性廃液のｐＨが７．８であるため、第二放射性廃液に含まれる、価数が「３～５」である各α核種（Ｕ，Ｐｕ，Ｎｐ，Ａｍ及びＣｍ）の価数が、スペース領域１５内で「３」に調整される。第二放射性廃液に含まれる、価数が「３」に調整された各α核種は、還元剤（例えば、ヒドラジン）の存在下で、領域１６においてフェライト粒子に効率良く吸着されて除去される（α核種のイオン除去工程Ｓ７）。 Since the pH of the second radioactive liquid waste is 7.8, the valence of each α-nuclide (U, Pu, Np, Am and Cm) contained in the second radioactive liquid waste and having a valence of "3 to 5" is high. , Adjusted to "3" within the space area 15. Each α-nuclide whose valence is adjusted to “3” contained in the second radioactive liquid waste is efficiently adsorbed and removed by ferrite particles in the region 16 in the presence of a reducing agent (for example, hydrazine) ( Ion removal step S7) for α-nuclide.
　α核種除去装置１４内でα核種が吸着されたフェライト粒子は、使用済みフェライト粒子として、第二放射性廃液と共に、α核種除去装置１４から排出されて、配管４６を通してα核種吸着材分離装置７２に供給される。第二放射性廃液に含まれてα核種が吸着されたフェライト粒子は、α核種吸着材分離装置７２内に存在する、例えば、μｍオーダー以下の孔径を有する膜を用いたクロスフローフィルタ方式によるろ過により、第二放射性廃液から分離される（吸着材分離工程Ｓ８）。α核種が吸着されたフェライト粒子が分離された第二放射性廃液は、α核種吸着材分離装置７２から配管４６に排出される。 The ferrite particles on which the α-nuclide is adsorbed in the α-nuclide removing device 14 are discharged from the α-nuclide removing device 14 together with the second radioactive liquid waste as used ferrite particles, and are discharged to the α-nuclide adsorbent separating device 72 through the pipe 46. Be supplied. The ferrite particles in which the α-nuclide is adsorbed contained in the second radioactive liquid waste liquid are present in the α-nuclide adsorbent separator 72, for example, by filtration by a cross-flow filter method using a film having a pore size of μm order or less. , Separated from the second radioactive liquid waste (adsorbent separation step S8). The second radioactive liquid waste from which the ferrite particles on which the α-nuclide is adsorbed is separated is discharged from the α-nuclide adsorbent separating device 72 to the pipe 46.
　α核種のコロイド生成工程Ｓ５において、分解可能なｐＨ調整剤である還元剤、例えば、ヒドラジンが第二放射性廃液に注入されているので、ｐＨ調整剤判定工程Ｓ９の判定が「ＹＥＳ」になる。このため、ｐＨ７．８の、ヒドラジンを含む、配管４６内の第二放射性廃液は、α核種吸着材分離装置７２から分解装置１０７に導かれる。 In the α-nuclide colloid production step S5, a reducing agent which is a decomposable pH adjuster, for example, hydrazine is injected into the second radioactive liquid waste, so that the determination in the pH adjuster determination step S9 is “YES”. Therefore, the second radioactive liquid waste having a pH of 7.8 and containing hydrazine in the pipe 46 is guided from the α-nuclide adsorbent separating device 72 to the decomposition device 107.
　第二放射性廃液に含まれるヒドラジンは、第一放射性廃液に含まれるヒドラジンと同様に、分解装置１０７内で、活性炭触媒及び過酸化水素の作用により分解される（還元剤の分解工程Ｓ１０）。分解装置１０７から排出された、α核種及びヒドラジンを含んでいなく希硝酸及び水酸化ナトリウムを含んでいる第一放射性廃液は、配管４６を通して処理水回収タンク１８に導かれる。 The hydrazine contained in the second radioactive liquid waste is decomposed by the action of the activated carbon catalyst and hydrogen peroxide in the decomposition apparatus 107 in the same manner as the hydrazine contained in the first radioactive liquid waste (reducing agent decomposition step S10). The first radioactive liquid waste containing no α-nuclide and hydrazine but containing dilute nitric acid and sodium hydroxide discharged from the decomposition apparatus 107 is guided to the treated water recovery tank 18 through the pipe 46.
　α核種のコロイド生成工程Ｓ５において、分解不可能なｐＨ調整剤（例えば、希硝酸及び水酸化ナトリウム）が水質調整装置５４から第二放射性廃液に注入され、この第二放射性廃液に分解可能なｐＨ調整剤（例えば、ヒドラジン及びシュウ酸）が注入されない場合には、ｐＨ調整剤判定工程Ｓ９の判定が「Ｎｏ」になり、α核種除去装置１４から排出されたその第二放射性廃液は、薬液タンク１０９から過酸化水素が供給されず、分解装置１０７を、そのまま通過して、処理水回収タンク１８に導かれる。 In the α-nuclide colloid production step S5, a non-decomposable pH adjuster (for example, dilute nitrate and sodium hydroxide) is injected into the second radioactive liquid from the water conditioner 54, and the pH that can be decomposed into the second radioactive liquid is When the adjusting agent (for example, hydrazine and oxalic acid) is not injected, the determination in the pH adjusting agent determination step S9 becomes "No", and the second radioactive liquid waste discharged from the α nuclide removing device 14 is a chemical liquid tank. No hydrogen peroxide is supplied from 109, and the hydrogen peroxide passes through the decomposition device 107 as it is and is guided to the treated water recovery tank 18.
　処理水回収タンク１８内の第二放射性廃液（ヒドラジンまたはシュウ酸が分解されて希硝酸及び水酸化ナトリウムを含む第一放射性廃液）は、移送ポンプ４７を駆動して配管４８により乾燥粉体化装置２０に供給されて紛体化される（減容工程Ｓ１１）。乾燥粉体化装置２０で生成された、α核種を含まない紛体は、配管４９を通して固化設備２１に移送されて固化容器内に充填され、その固化容器内に固化材が注入されて固化される（容器充填または固化工程Ｓ１２）。この固化容器は、密封された後、保管場所に保管される。保管されるこの固化容器内には、超半減期のα核種が存在していない。 The second radioactive liquid waste (the first radioactive liquid waste in which hydrazine or oxalic acid is decomposed and contains dilute nitrate and sodium hydroxide) in the treated water recovery tank 18 is driven by a transfer pump 47 and dried and powdered by a pipe 48. It is supplied to No. 20 and pulverized (volume reduction step S11). The α-nucleus-free powder produced by the dry powdering apparatus 20 is transferred to the solidifying facility 21 through the pipe 49 and filled in the solidifying container, and the solidifying material is injected into the solidifying container to solidify it. (Container filling or solidification step S12). This solidified container is sealed and then stored in a storage location. There are no ultra-half-life alpha nuclides in this solidified vessel that is stored.
　ここで、第二放射性廃液に希硝酸を注入した場合には、この第二放射性廃液の粉体化により生成された粉体は硝酸及び水酸化ナトリウムを含んでおり、この粉体を固化容器内で溶融したガラスにより固化して生成されたガラス固化体も、硝酸及び水酸化ナトリウムを含んでいる。 Here, when dilute nitric acid is injected into the second radioactive waste liquid, the powder produced by powdering the second radioactive waste liquid contains nitric acid and sodium hydroxide, and this powder is contained in the solidification container. The vitrified material produced by solidifying with the glass melted in (1) also contains nitric acid and sodium hydroxide.
　本実施例によれば、α核種を含む放射性廃液（第一放射性廃液及び後述の第二放射性廃液のそれぞれ）にｐＨ調整剤（アルカリ、酸、水質調整用酸化剤及び還元剤の少なくとも１つ）を注入することによって放射性廃液内に超半減期のα核種のうちＵ，Ｐｕ及びＮｐのコロイドを生成することができる。生成されたコロイドはα核種のコロイド除去工程Ｓ６においてフィルタ６６によって除去されるため、α核種除去装置１４に流入する放射性廃液に含まれる超半減期のα核種の濃度が低減される。このため、α核種除去装置１４に注入するα核種吸着材（例えば、フェライト粒子）の量を減少させることができ、α核種吸着材の使用量を低減できる。これにより、α核種除去装置１４は、よりコンパクトになる。 According to this example, a pH adjuster (alkaline, acid, at least one of an oxidizing agent for adjusting water quality and a reducing agent) is added to the radioactive liquid waste containing α-nuclide (each of the first radioactive liquid waste and the second radioactive liquid liquid described later). By injecting, U, Pu and Np colloids of α nuclides having a super half-life can be produced in the radioactive liquid waste. Since the produced colloid is removed by the filter 66 in the colloid removal step S6 of the α-nuclide, the concentration of the α-nuclide having a super half-life contained in the radioactive liquid liquid flowing into the α-nuclide removing device 14 is reduced. Therefore, the amount of the α-nuclide adsorbent (for example, ferrite particles) injected into the α-nuclide removing device 14 can be reduced, and the amount of the α-nuclide adsorbent used can be reduced. As a result, the α-nuclide removing device 14 becomes more compact.
　特に、α核種のコロイドは、α核種のコロイド生成工程Ｓ５において、ｐＨ調整剤をα核種を含む放射性廃液に注入し、この放射性廃液のｐＨを４以上８未満の範囲内のｐＨにすることによって、放射性廃液内で生成することができる。 In particular, for the α-nuclide colloid, in the α-nuclide colloid production step S5, a pH adjusting agent is injected into the radioactive liquid waste containing the α-nuclide, and the pH of this radioactive liquid waste is set to a pH within the range of 4 or more and less than 8. , Can be produced in radioactive liquid waste.
　フィルタ６６で除去されなかった、放射性廃液に含まれるα核種のイオンは、α核種のイオン除去工程Ｓ７において、α核種除去装置１４内でα核種吸着材によって除去できる。 The α-nuclide ions contained in the radioactive liquid waste, which were not removed by the filter 66, can be removed by the α-nuclide adsorbent in the α-nuclide removing device 14 in the α-nuclide ion removing step S7.
　本実施例では、α核種のコロイド除去工程Ｓ６におけるフィルタ６６によるα核種のコロイドの除去、その後のα核種のイオン除去工程Ｓ７におけるα核種除去装置１４でのα核種のイオンの除去の二段階で、α核種を除去することができる。 In this embodiment, there are two steps: removal of the α-nuclide colloid by the filter 66 in the α-nuclide colloid removal step S6, and subsequent removal of the α-nuclide ion by the α-nuclide removal device 14 in the α-nuclide ion removal step S7. , Alpha nuclides can be removed.
　粒状のα核種吸着材がα核種吸着材注入装置６９からα核種除去装置１４内のα核種を含む放射性廃液中に注入されるため、α核種除去装置１４内でその放射性廃液と接触するα核種吸着材の表面積が増大し、α核種吸着材によって除去されるα核種が増加する。特に、α核種吸着材の粒径を１μｍ以下にすることにより、α核種吸着材粒子のα核種の吸着量が著しく増加する。 Since the granular α-nuclide adsorbent is injected from the α-nuclide adsorbent injection device 69 into the radioactive liquid waste containing the α-nuclide in the α-nuclide removal device 14, the α-nuclide that comes into contact with the radioactive liquid in the α-nuclide removal device 14 The surface area of the adsorbent increases, and the α-nuclide removed by the α-nuclide adsorbent increases. In particular, by reducing the particle size of the α-nuclide adsorbent to 1 μm or less, the amount of α-nuclide adsorbed by the α-nuclide adsorbent particles is remarkably increased.
　また、α核種除去装置１４へα核種吸着材粒子を注入することにより、特願２０１８－２１０３１５号の明細書に記載された、α核種吸着材粒子が充填されたα核種吸着材層が内部に形成されたα核種除去装置にα核種を含む放射性廃液を供給する場合に比べて、α核種吸着材粒子がα核種除去装置１４内の放射性廃液に浸漬される時間を制御することができる。これにより、α核種吸着材粒子のα核種吸着量が所定のα核種吸着量となる時間まで、α核種吸着材粒子を放射性廃液に浸漬させるように制御することができる。 Further, by injecting the α-nuclide adsorbent particles into the α-nuclide removing device 14, the α-nuclide adsorbent layer filled with the α-nuclide adsorbent particles described in the specification of Japanese Patent Application No. 2018-210315 is inside. It is possible to control the time during which the α-nuclide adsorbent particles are immersed in the radioactive liquid waste in the α-nuclide removing device 14 as compared with the case where the radioactive liquid containing the α-nuclide is supplied to the formed α-nuclide removing device. As a result, it is possible to control the α-nuclide adsorbent particles to be immersed in the radioactive liquid waste until the α-nuclide adsorption amount of the α-nuclide adsorbent particles reaches a predetermined α-nuclide adsorption amount.
　そして、所定のα核種吸着量となる所定の時間までα核種吸着材粒子を放射性廃液に浸漬させた後に、α核種除去装置１４からα核種吸着材分離装置７２へのα核種吸着材粒子を含む放射性廃液の供給が可能となる。このため、α核種を含む放射性廃棄物を低減できる。 Then, after immersing the α-nuclide adsorbent particles in the radioactive liquid waste until a predetermined time for adsorbing a predetermined α-nuclide, the α-nuclide adsorbent particles from the α-nuclide removing device 14 to the α-nuclide adsorbent separating device 72 are included. It becomes possible to supply radioactive liquid waste. Therefore, radioactive waste containing α-nuclide can be reduced.
　本実施例によれば、第一洗浄工程Ｓ１において、有機酸水溶液（例えば、シュウ酸水溶液）を用いて、放射性有機廃棄物に混在している酸化鉄成分を溶解させることができる。さらに、本実施例によれば、第二洗浄工程Ｓ２において、放射性有機廃棄物である陽イオン交換樹脂に吸着された、α核種のイオンを含む放射性核種イオンを、有機酸塩水溶液（例えば、ギ酸ヒドラジン水溶液）の陽イオン交換樹脂への接触によって陽イオン交換樹脂から脱離させることにより、放射性有機廃棄物に含まれる放射性核種の濃度を低減することができ、高線量の放射性廃棄物の量を低減することができる。特に、有機酸水溶液によっても陽イオン交換樹脂から脱離されずに陽イオン交換樹脂に吸着されて残っているα核種のイオンを含む放射性核種のイオンを、有機酸塩水溶液を放射性有機廃棄物に接触させることにより、効率良く、陽イオン交換樹脂から脱離させることができる。 According to this embodiment, in the first cleaning step S1, an organic acid aqueous solution (for example, an oxalic acid aqueous solution) can be used to dissolve the iron oxide component mixed in the radioactive organic waste. Further, according to the present embodiment, in the second cleaning step S2, the radionuclide ion containing the α-nuclide ion adsorbed on the cation exchange resin which is the radioactive organic waste is converted into an organic acid salt aqueous solution (for example, formic acid). By desorbing from the cation exchange resin by contacting the hydrazine aqueous solution) with the cation exchange resin, the concentration of radionuclides contained in the radioactive organic waste can be reduced, and the amount of high-dose radioactive waste can be reduced. Can be reduced. In particular, the ions of radioactive nuclei including the ions of α nuclei remaining adsorbed on the cation exchange resin without being desorbed from the cation exchange resin by the organic acid aqueous solution are brought into contact with the organic acid salt aqueous solution to the radioactive organic waste. By doing so, it can be efficiently desorbed from the cation exchange resin.
　本実施例によれば、α核種を含む放射性廃液に還元剤、例えば、ヒドラジンを注入して放射性廃液のｐＨを調節するため、放射性廃液に含まれる超半減期のα核種が、α核種除去装置１４に注入したフェライト（α核種吸着材）によって除去されやすくなる。このため、放射性廃液に含まれるα核種がα核種除去装置１４において除去され、α核種除去装置１４から流出する放射性廃液に含まれる超半減期のα核種が著しく低減される。この結果、α核種除去装置１４から流出する放射性廃液の放射線線量が著しく低減され、超半減期のα核種を含む放射性廃棄物（例えば、固化体）の発生量を低減できる。 According to this embodiment, in order to adjust the pH of the radioactive effluent by injecting a reducing agent, for example, hydrazine into the radioactive effluent containing the α-nuclide, the α-nuclide having an ultra-half-life contained in the radioactive effluent is an α-nuclide removing device. It is easily removed by the ferrite (α-nuclide adsorbent) injected into 14. Therefore, the α-nuclide contained in the radioactive effluent is removed by the α-nuclide removing device 14, and the α-nuclide having a super half-life contained in the radioactive effluent flowing out from the α-nuclide removing device 14 is significantly reduced. As a result, the radiation dose of the radioactive liquid spilled from the α-nuclide removing device 14 is remarkably reduced, and the amount of radioactive waste (for example, solidified body) containing the α-nuclide having a super half-life can be reduced.
　化学反応槽４から戻り配管３６に排出された第一放射性廃液及び第二放射性廃液のそれぞれのα核種濃度が所定の濃度になったときに、化学反応槽４から廃液分解装置１３にα核種を含む第一放射性廃液及び第二放射性廃液のそれぞれを移送することにより、第一放射性廃液及び第二放射性廃液のそれぞれに含まれるα核種吸着材におけるα核種の吸着性能を十分に発揮させることができる。 When the α-nuclide concentration of each of the first radioactive liquid and the second radioactive liquid discharged from the chemical reaction tank 4 to the return pipe 36 reaches a predetermined concentration, the α-nuclide is transferred from the chemical reaction tank 4 to the waste liquid decomposition apparatus 13. By transferring each of the first radioactive effluent and the second radioactive effluent contained therein, the adsorption performance of the α-nuclide in the α-nuclide adsorbent contained in each of the first radioactive effluent and the second radioactive effluent can be sufficiently exhibited. ..
　本実施例では、α核種除去装置１４内に存在するα核種吸着材が、使用済のα核種吸着材として、α核種吸着材分離装置７２で分離される。分離されたα核種吸着材は、固化容器（以下、「第１固化容器」という）内に収納される。その後、例えば、溶融したガラスが、α核種を吸着している所定量の使用済α核種吸着材が収納された第１固化容器内に充填される。溶融したガラスが固化した後、所定量の使用済α核種吸着材が収納された第１固化容器が密封される。 In this embodiment, the α-nuclide adsorbent existing in the α-nuclide removing device 14 is separated as the used α-nuclide adsorbent by the α-nuclide adsorbent separating device 72. The separated α-nuclide adsorbent is stored in a solidification container (hereinafter, referred to as “first solidification container”). Then, for example, the molten glass is filled in a first solidification container containing a predetermined amount of used α-nuclide adsorbent adsorbing α-nuclide. After the molten glass solidifies, the first solidifying container containing a predetermined amount of used α-nuclide adsorbent is sealed.
　高線量樹脂貯蔵タンク２内に貯蔵されている放射性有機廃棄物にα核種が吸着された陽イオン交換樹脂が含まれているときに、前述した特開２０１５－６４３３４号公報に記載された放射性有機廃棄物の処理方法を実施すると、放射性有機廃棄物に含まれているクラッドを溶解した有機酸水溶液、陽イオン交換樹脂からα核種を脱離させた有機酸塩水溶液のそれぞれには、α核種が含まれている。α核種を含む有機酸水溶液の有機酸を分解用酸化剤で分解して生成された第一放射性廃液、及びα核種を含む有機酸塩水溶液の有機酸塩を分解用酸化剤で分解して生成された第二放射性廃液のそれぞれは、粉体化されて別々の固化容器（以下、「第２固化容器」という）内に充填され、その後、例えば、溶融されたガラスが各第２固化容器内に充填される。第一放射性廃液の、α核種を含む粉体を固化する溶融ガラスが第２固化容器内で固化された後に、この第２固化容器が密封される。第二放射性廃液の、α核種を含む粉体を固化する溶融ガラスが第２固化容器内で固化された後に、この第２固化容器が密封される。 When the radioactive organic waste stored in the high-dose resin storage tank 2 contains a cation exchange resin in which α-nuclides are adsorbed, the radioactive organic described in JP-A-2015-64334 described above When the waste treatment method is implemented, α-nuclide is found in each of the organic acid aqueous solution in which the clad contained in the radioactive organic waste is dissolved and the organic acid salt aqueous solution in which the α-nuclide is desorbed from the cation exchange resin. include. The first radioactive effluent produced by decomposing the organic acid of the organic acid aqueous solution containing α nuclei with a decomposition oxidant, and the organic acid salt of the organic acid aqueous solution containing α nuclei are decomposed with a decomposing oxidant. Each of the second radioactive effluents produced is pulverized and filled in separate solidification containers (hereinafter referred to as "second solidification containers"), and then, for example, molten glass is placed in each second solidification container. Is filled with. After the molten glass that solidifies the powder containing the α-nuclide of the first radioactive liquid waste is solidified in the second solidifying container, the second solidifying container is sealed. After the molten glass that solidifies the powder containing the α-nuclide of the second radioactive liquid waste is solidified in the second solidifying container, the second solidifying container is sealed.
　ここで、本実施例の処理方法と特開２０１５－６４３３４号公報に記載された処理方法とを、比較する。これらの処理方法において、第一洗浄工程Ｓ１及び第二洗浄工程Ｓ２の実施の対象となる放射性有機廃棄物の量が同じであって溶解されるクラッドの量及び脱離されるα核種の量が同じであり、発生する第一放射性廃液の量及び第二放射性廃液の量が同じであるとする。このとき、本実施例で発生する、α核種を吸着したフェライトを第１固化容器内でガラス固化することにより生成されたガラス固化体の個数は、特開２０１５－６４３３４号公報に記載された処理方法で発生した、第一放射性廃液の、α核種を含む粉体を第２固化容器内でガラス固化することにより生成されたガラス固化体の個数と、第二放射性廃液の、α核種を含む粉体を第２固化容器内でガラス固化することにより生成されたガラス固化体の個数の合計よりも少なくなる。すなわち、本実施例で発生する、α核種を含むガラス固化体（α核種を含む放射性廃棄物）は、特開２０１５－６４３３４号公報記載された処理方法で発生する、α核種を含むガラス固化体（α核種を含む放射性廃棄物）よりも低減できる。 Here, the processing method of this example and the processing method described in Japanese Patent Application Laid-Open No. 2015-64334 are compared. In these treatment methods, the amount of radioactive organic waste to be carried out in the first cleaning step S1 and the second cleaning step S2 is the same, and the amount of clad to be dissolved and the amount of α-nuclide to be desorbed are the same. It is assumed that the amount of the first radioactive liquid waste and the amount of the second radioactive liquid waste generated are the same. At this time, the number of vitrified wastes generated by vitrifying the ferrite adsorbed with α nuclei in the first solidification vessel, which is generated in this example, is the treatment described in JP-A-2015-64334. The number of vitrified wastes produced by vitrifying the powder containing α-nucleus in the first radioactive liquid waste generated by the method in the second solidification vessel, and the powder containing α-nucleus in the second radioactive liquid waste. It is less than the total number of vitrified wastes produced by vitrifying the body in the second solidification vessel. That is, the vitrified body containing α-nuclide (radioactive waste containing α-nuclide) generated in this example is a vitrified body containing α-nuclide generated by the treatment method described in JP-A-2015-64334. It can be reduced more than (radioactive waste containing α-nuclide).
　本実施例によれば、クラッドを溶解した有機酸水溶液に含まれる有機酸（例えば、シュウ酸）、及びα核種を溶離した有機酸塩水溶液に含まれる有機酸塩（例えば、ギ酸ヒドラジン）が、分解用酸化剤を用いた酸化処理により分解されるため、α核種を含む放射性廃液の量が低減され、α核種除去後の放射性廃液の濃縮または粉体化によって、発生する放射性廃棄物の量が低減される。 According to this example, the organic acid contained in the organic acid aqueous solution in which the clad is dissolved (for example, oxalic acid) and the organic acid salt contained in the organic acid salt aqueous solution in which α nuclei are eluted (for example, hydrazine formate) are used. Since it is decomposed by oxidation treatment using a decomposition oxidant, the amount of radioactive waste liquid containing α nuclei is reduced, and the amount of radioactive waste generated by concentration or powdering of radioactive liquid after removal of α nuclei is reduced. It will be reduced.
　本実施例によれば、有機酸水溶液による、放射性有機廃棄物に含まれるクラッドの溶解（第一洗浄工程Ｓ１）、及び有機酸塩水溶液による、放射性有機廃棄物である陽イオン交換樹脂に吸着されたα核種の脱離（第二洗浄工程Ｓ２）を、一つの洗浄槽（例えば、化学反応槽４）内で順番に実施するので、放射性廃液処理システムをよりコンパクト化できる。 According to this embodiment, the clad contained in the radioactive organic waste is dissolved by the organic acid aqueous solution (first cleaning step S1), and the organic acid salt aqueous solution is adsorbed by the cation exchange resin which is the radioactive organic waste. Since the desorption of the α nuclei (second cleaning step S2) is sequentially carried out in one cleaning tank (for example, the chemical reaction tank 4), the radioactive liquid waste treatment system can be made more compact.
　実施例１において、水質調整装置５４の替りに、図５に示す水質調整装置５４Ａを用いることができる。水質調整装置５４Ａは、水質調整装置５４におけるｐＨ調整剤注入装置５５及びｐＨ計４９Ａと共に、脱溶存炭酸剤注入装置５９、酸化還元電位測定装置６３及び炭酸濃度計６４を備えている。脱溶存炭酸剤注入装置５９は、脱溶存炭酸剤槽６０、及び弁６１が設けられた注入配管６２を有する。脱溶存炭酸剤槽６０に接続された注入配管６２は、ｐＨ計４９Ａの配管４５への取り付け位置とフィルタ６６の間で配管４５に接続される。脱溶存炭酸剤槽６０には、脱溶存炭酸剤として、亜硫酸ナトリウム、Ｎ２ガス及びＡｒガス等が充填される。 In the first embodiment, the water quality adjusting device 54A shown in FIG. 5 can be used instead of the water quality adjusting device 54. The water quality adjusting device 54A includes a desolved carbon dioxide agent injection device 59, an oxidation-reduction potential measuring device 63, and a carbon dioxide concentration meter 64, as well as a pH adjusting agent injection device 55 and a pH meter 49A in the water quality adjusting device 54. The dissolved carbonic acid agent injection device 59 has a dissolved carbonic acid agent tank 60 and an injection pipe 62 provided with a valve 61. The injection pipe 62 connected to the dissolved carbonate tank 60 is connected to the pipe 45 between the attachment position of the pH meter 49A to the pipe 45 and the filter 66. The removal of dissolved carbon dioxide agent tank 60, as de-dissolved carbon agent, sodium sulfite, N 2 gas and Ar gas or the like is filled.
　酸化還元電位測定装置６３は、ｐＨ計４９Ａの配管４５への取り付け位置と、注入配管６２と配管４５の接続位置との間で、配管４５に取り付けられる。炭酸濃度計６４は、注入配管６２と配管４５の接続位置と、α核種濃度計６５の配管４５への取り付け位置との間で、配管４５に取り付けられる。 The redox potential measuring device 63 is attached to the pipe 45 between the attachment position of the pH meter 49A to the pipe 45 and the connection position between the injection pipe 62 and the pipe 45. The carbonic acid concentration meter 64 is attached to the pipe 45 between the connection position of the injection pipe 62 and the pipe 45 and the attachment position of the α-nuclide concentration meter 65 to the pipe 45.
　水質調整装置５４Ａを用いた場合における第１放射性廃液及び第二放射性廃液のそれぞれに対して実施されるα核種のコロイド生成工程Ｓ５を、以下に説明する。 The α-nuclide colloid production step S5 carried out for each of the first radioactive liquid waste and the second radioactive liquid waste liquid when the water quality adjusting device 54A is used will be described below.
　廃液分解工程Ｓ４において、廃液分解装置１３の廃液貯槽内の第一放射性廃液に含まれるシュウ酸が分解された後、α核種、及びα核種以外の放射性核種を含む第一放射性廃液が、配管４５を通して水質調整装置５４Ａに供給される。 In the waste liquid decomposition step S4, after the oxalic acid contained in the first radioactive liquid in the waste liquid storage tank of the waste liquid decomposition apparatus 13 is decomposed, the α nuclide and the first radioactive liquid containing radioactive nuclides other than the α nuclide are discharged into the pipe 45. It is supplied to the water quality adjusting device 54A through.
　α核種のコロイド生成工程Ｓ５において、水質調整装置５４Ａから注入配管４２を通して配管４５内の第一放射性廃液に注入される。ｐＨ調整剤の注入により、第一放射性廃液のｐＨは、４以上８未満の範囲内の、例えば、７．８に調整される。このとき、前述したように、水質調整装置５４Ａのアルカリ注入装置７９から水酸化ナトリウム水溶液が、酸注入装置５６から希硝酸水溶液が、還元剤注入装置１７からヒドラジン水溶液が、それぞれ所定量、配管４５内に注入される。 In the α-nuclide colloid production step S5, the water quality is injected from the water quality adjusting device 54A into the first radioactive liquid waste in the pipe 45 through the injection pipe 42. By injecting a pH adjuster, the pH of the first radioactive liquid waste is adjusted to a range of 4 or more and less than 8, for example, 7.8. At this time, as described above, a predetermined amount of sodium hydroxide aqueous solution from the alkali injection device 79 of the water quality adjusting device 54A, a dilute nitric acid aqueous solution from the acid injection device 56, and a hydrazine aqueous solution from the reducing agent injection device 17 are provided in the pipe 45. Infused into.
　さらに、α核種のコロイド生成工程Ｓ５では、第一放射性廃液における溶存炭素の量を調整するために、弁６１を開くことによって脱溶存炭酸剤注入装置５９の脱溶存炭酸剤槽６０内の脱溶存炭酸剤、例えば、亜硫酸ナトリウムが、注入配管６２を通して配管４５に注入される。亜硫酸ナトリウムの注入によりｐＨが７．８の第一放射性廃液に溶存している炭素の量が減少する。 Further, in the α-nuclide colloid formation step S5, in order to adjust the amount of dissolved carbon in the first radioactive liquid, the valve 61 is opened to dissolve the dissolved carbonic acid agent 59 in the dissolved carbonic acid tank 60. A carbonate, for example sodium sulfite, is injected into the pipe 45 through the injection pipe 62. Injection of sodium sulfite reduces the amount of carbon dissolved in the primary radioactive effluent with a pH of 7.8.
　水質調整装置５４Ａを用いることによって、前述したように、第一放射性廃液のｐＨを４以上８未満の範囲内の、例えば、７．８に調整することができ、第一放射性廃液に溶存している炭素の量を減少させることができる。このため、水質調整装置５４により第一放射性廃液のｐＨ調整だけを行う場合に比べて、水質調整装置５４Ａを用いて第一放射性廃液のｐＨ調整及び第一放射性廃液の溶存炭素量の減少を実施する場合には、第一放射性廃液に含まれているα核種のうちのＵ，Ｐｕ及びＮｐのそれぞれのコロイドの生成量が増加する。このため、フィルタ６６でより多くのコロイドを除去することができ、フィルタ６６で除去されるα核種の量が増加する。それだけ、フィルタ６６からα核種除去装置１４に供給される第一放射性廃液に含まれるα核種の量が少なくなり、α核種除去装置１４に注入されるα核種吸着材の量も減らすことができる。 By using the water quality adjusting device 54A, as described above, the pH of the first radioactive liquid waste can be adjusted to a range of 4 or more and less than 8, for example, 7.8, and is dissolved in the first radioactive liquid waste liquid. The amount of carbon present can be reduced. Therefore, as compared with the case where only the pH of the first radioactive liquid is adjusted by the water quality adjusting device 54, the pH of the first radioactive liquid is adjusted and the amount of dissolved carbon in the first radioactive liquid is reduced by using the water quality adjusting device 54A. In this case, the amount of each colloid of U, Pu and Np among the α nuclides contained in the first radioactive liquid waste increases. Therefore, more colloids can be removed by the filter 66, and the amount of α-nuclide removed by the filter 66 increases. Therefore, the amount of α-nuclide contained in the first radioactive liquid waste supplied from the filter 66 to the α-nuclide removing device 14 can be reduced, and the amount of α-nuclide adsorbent injected into the α-nuclide removing device 14 can also be reduced.
　Ｓ１…第一洗浄工程、Ｓ２…第二洗浄工程、Ｓ４…廃液分解工程、Ｓ５…α核種のコロイド生成工程、Ｓ６…α核種のコロイド除去工程、Ｓ７…α核種のイオン除去工程、Ｓ８…吸着材分離工程、１…放射性廃液処理システム、４…化学反応槽、７…有機酸槽、８…有機酸塩槽、９…移送水槽、１０…化学洗浄部、１３…廃液分解装置、１４…α核種除去装置、１７…還元剤注入装置、１７Ａ…還元剤槽、１９…廃液処理部、４９Ａ…ｐＨ計、４９Ｂ…磁化率測定装置、５０…オゾン供給装置、５１…オゾン噴射管、５４，５４Ａ…水質調整装置５４…ｐＨ調整剤注入装置、５６…酸注入装置、５９…脱溶存炭酸剤注入装置、６６…フィルタ、６９…α核種吸着材注入装置、７２…α核種吸着材分離装置、７５…酸化剤注入装置、７９…アルカリ注入装置、１０７…分解装置。 S1 ... 1st cleaning step, S2 ... 2nd cleaning step, S4 ... Waste liquid decomposition step, S5 ... α nuclei colloid generation step, S6 ... α nuclei colloid removal step, S7 ... α nuclei ion removal step, S8 ... Adsorption Material separation process, 1 ... Radioactive waste liquid treatment system, 4 ... Chemical reaction tank, 7 ... Organic acid tank, 8 ... Organic acid salt tank, 9 ... Transfer water tank, 10 ... Chemical cleaning unit, 13 ... Waste liquid decomposition device, 14 ... α Nucleus removal device, 17 ... reducing agent injection device, 17A ... reducing agent tank, 19 ... waste liquid treatment unit, 49A ... pH meter, 49B ... alkalinity measuring device, 50 ... ozone supply device, 51 ... ozone injection tube, 54, 54A ... Water quality adjusting device 54 ... pH adjusting agent injection device, 56 ... acid injection device, 59 ... dissolved carbonate injection device, 66 ... filter, 69 ... α nuclei adsorbent injection device, 72 ... α nuclei adsorbent separator, 75 ... Oxidizing agent injection device, 79 ... Alkali injection device, 107 ... Decomposition device.

Claims (16)

  1. 　α核種を含む放射性廃液を処理する放射性廃液処理システムであって、
    　前記α核種を含む前記放射性廃液の水質を調整する水質調整装置と、
    　前記水質調整装置の下流に配置されて、前記水質が調整された前記放射性廃液が供給されるフィルタとを備えたことを特徴とする放射性廃液処理システム。     A radioactive liquid waste treatment system that treats radioactive liquid waste containing α-nuclide.
    A water quality adjusting device for adjusting the water quality of the radioactive liquid waste containing the α-nuclide, and
    A radioactive liquid waste treatment system, which is arranged downstream of the water quality adjusting device and includes a filter to which the radioactive liquid waste having the adjusted water quality is supplied.
  2. 　前記放射性廃液の前記水質の調整によって前記放射性廃液内で生成される、前記α核種のコロイドを除去する前記フィルタを備えた請求項１に記載の放射性廃液処理システム。 The radioactive waste liquid treatment system according to claim 1, further comprising the filter for removing the colloid of the α-nuclide produced in the radioactive liquid waste by adjusting the water quality of the radioactive liquid waste liquid.
  3. 　前記フィルタから流出する前記α核種のイオンを含む前記放射性廃液が供給されてα核種吸着材が内部に存在し、このα核種吸着材によって前記α核種のイオンを吸着して前記α核種のイオンを前記放射性廃液から除去するα核種除去装置を備えた請求項１または２記載の放射性廃液処理システム。 The radioactive liquid containing the α-nuclide ion flowing out from the filter is supplied to the α-nuclide adsorbent, and the α-nuclide adsorbent adsorbs the α-nuclide ion to produce the α-nuclide ion. The radioactive liquid waste treatment system according to claim 1 or 2, further comprising an α-nuclide removing device for removing from the radioactive liquid.
  4. 　前記フィルタから流出する前記α核種のイオンを含む前記放射性廃液にα核種吸着材を注入するα核種吸着材注入装置と、前記α核種のイオンを含む前記放射性廃液が供給され、内部に存在する前記α核種吸着材によって前記α核種のイオンを吸着して前記α核種のイオンを前記放射性廃液から除去するα核種除去装置とを備えた請求項１または２記載の放射性廃液処理システム。 An α-nuclide adsorbent injection device that injects an α-nuclide adsorbent into the radioactive liquid containing the α-nuclide ions flowing out of the filter, and the radioactive waste liquid containing the α-nuclide ions are supplied and exist inside. The radioactive waste liquid treatment system according to claim 1 or 2, further comprising an α-nuclide removing device that adsorbs the α-nuclide ions with an α-nuclide adsorbent and removes the α-nuclide ions from the radioactive waste liquid.
  5. 　前記水質調整装置は、ｐＨ調整剤注入装置を備えている請求項４に記載の放射性廃液処理システム。 The radioactive liquid waste treatment system according to claim 4, wherein the water quality adjusting device includes a pH adjusting agent injection device.
  6. 　前記水質調整装置は、ｐＨ調整剤注入装置及び脱溶存炭酸剤注入装置を備えている請求項４に記載の放射性廃液処理システム。 The radioactive liquid waste treatment system according to claim 4, wherein the water quality adjusting device includes a pH adjusting agent injection device and a dissolved carbon dioxide injection device.
  7. 　前記ｐＨ調整剤注入装置は、還元剤注入装置、酸注入装置、酸化剤注入装置及びアルカリ注入装置を有する請求項５または６に記載の放射性廃液処理システム。 The radioactive waste liquid treatment system according to claim 5 or 6, wherein the pH adjuster injection device includes a reducing agent injection device, an acid injection device, an oxidant injection device, and an alkali injection device.
  8. 　放射性有機廃棄物が供給される洗浄槽と、
    　前記洗浄槽に接続され、有機酸水溶液を貯留する有機酸槽と、
    　前記洗浄槽に接続され、有機酸塩水溶液を貯留する有機酸塩槽と、
    　前記洗浄槽から排出される、前記α核種を含む放射性核種を含んでいる前記有機酸水溶液に含まれる有機酸の分解、及び前記洗浄槽から排出される、前記α核種を含む放射性核種を含んでいる前記有機酸塩水溶液に含まれる有機酸塩の分解を順次行う廃液分解装置と、
    　前記廃液分解装置に接続され、前記有機酸及び前記有機酸塩のそれぞれの分解によって生成されて前記廃液分解装置から排出される前記α核種を含む前記放射性廃液を前記フィルタに導く放射性廃液供給管を備え、
    　前記水質調整装置が前記放射性廃液供給管に接続されている請求項１ないし７のいずれか１項に記載の放射性廃液処理システム。     A cleaning tank to which radioactive organic waste is supplied and
    An organic acid tank connected to the washing tank and storing an aqueous organic acid solution,
    An organic acid salt tank connected to the washing tank and storing an aqueous organic acid salt solution,
    Decomposition of the organic acid contained in the organic acid aqueous solution containing the radionuclide containing the α-nuclide discharged from the washing tank, and containing the radionuclide containing the α-nuclide discharged from the washing tank. A waste liquid decomposition device that sequentially decomposes the organic acid contained in the organic acid aqueous solution.
    A radioactive liquid waste supply pipe connected to the waste liquid decomposition device and guiding the radioactive liquid containing the α-nuclide, which is generated by the decomposition of each of the organic acid and the organic acid salt and discharged from the waste liquid decomposition device, to the filter. Prepare,
    The radioactive liquid waste treatment system according to any one of claims 1 to 7, wherein the water quality adjusting device is connected to the radioactive liquid waste supply pipe.
  9. 　α核種を含む放射性廃液にｐＨ調整剤を注入して前記放射性廃液内で前記α核種のコロイドを生成し、生成された前記α核種のコロイドをフィルタによって除去することを特徴とする放射性廃液の処理方法。 Treatment of radioactive liquid waste, which comprises injecting a pH adjuster into a radioactive liquid containing α-nuclide to generate a colloid of the α-nuclide in the radioactive liquid, and removing the generated colloid of the α-nuclide with a filter. Method.
  10. 　前記ｐＨ調整剤の注入によって前記放射性廃液のｐＨが４以上８未満の範囲内のｐＨに調整され、ｐＨが４以上８未満の範囲内のｐＨである前記放射性廃液内で前記α核種のコロイドが生成される請求項９に記載の放射性廃液の処理方法。 By injecting the pH adjuster, the pH of the radioactive effluent is adjusted to a pH in the range of 4 or more and less than 8, and the colloid of the α-nuclide is contained in the radioactive effluent having a pH in the range of 4 or more and less than 8. The method for treating the generated radioactive liquid waste according to claim 9.
  11. 　前記フィルタから流出する前記α核種のイオンを含む前記放射性廃液が、α核種吸着材が内部に存在するα核種除去装置に供給され、前記放射性廃液に含まれる前記α核種のイオンが前記α核種吸着材に吸着されて前記放射性廃液から除去される請求項９または１０に記載の放射性廃液の処理方法。 The radioactive effluent containing the α-nuclide ions flowing out of the filter is supplied to an α-nuclide removing device in which an α-nuclide adsorbent is present, and the α-nuclide ions contained in the radioactive effluent adsorb the α-nuclide. The method for treating radioactive effluent according to claim 9 or 10, wherein the radioactive effluent is adsorbed on the material and removed from the radioactive effluent.
  12. 　前記フィルタから流出する前記α核種のイオンを含む前記放射性廃液がα核種除去装置内に供給され、α核種吸着材が前記放射性廃液に注入され、前記α核種除去装置内で、前記放射性廃液に含まれる前記α核種のイオンが前記α核種吸着材に吸着されて前記α核種のイオンを前記放射性廃液から除去する請求項９または１０に記載の放射性廃液の処理方法。 The radioactive effluent containing the ions of the α-nuclide flowing out from the filter is supplied into the α-nuclide removing device, the α-nuclide adsorbent is injected into the radioactive effluent, and contained in the radioactive effluent in the α-nuclide removing device. The method for treating a radioactive waste liquid according to claim 9 or 10, wherein the ions of the α-nuclide are adsorbed on the α-nuclide adsorbent and the ions of the α-nuclide are removed from the radioactive liquid.
  13. 　前記ｐＨ調整剤は、酸、水質調整用酸化剤、還元剤及びアルカリのうちの少なくとも１つの物質である請求項９ないし１２のいずれか１項に記載の放射性廃液の処理方法。 The method for treating radioactive waste liquid according to any one of claims 9 to 12, wherein the pH adjusting agent is at least one substance of an acid, an oxidizing agent for adjusting water quality, a reducing agent, and an alkali.
  14. 　前記ｐＨ調整剤以外に脱溶存炭酸剤を前記放射性廃液に注入する請求項９ないし１３のいずれか１項に記載の放射性廃液の処理方法。 The method for treating radioactive waste liquid according to any one of claims 9 to 13, wherein a dissolved carbonic acid agent is injected into the radioactive liquid waste in addition to the pH adjuster.
  15. 　放射性有機廃棄物に有機酸水溶液を接触させて前記放射性有機廃棄物に付着しているクラッドを溶解させ、
    　前記クラッドの溶解の後に、前記放射性有機廃棄物に有機酸塩水溶液を接触させて前記放射性有機廃棄物に吸着されているα核種を溶離させ、
    　前記クラッドを溶解させた、前記α核種を含む放射性核種を含んでいる前記有機酸水溶液に含まれる有機酸の分解、及び前記α核種を溶離させた、前記α核種を含む放射性核種を含んでいる前記有機酸塩水溶液に含まれる有機酸塩の分解を順次行い、
    　前記有機酸及び前記有機酸塩のそれぞれの分解によって生成される前記α核種を含む前記放射性廃液を前記フィルタに供給し、
    　前記α核種を含む前記放射性廃液が前記フィルタに到達する前に、前記ｐＨ調整剤の前記α核種を含む前記放射性廃液への注入が行われる請求項９ないし１４のいずれか１項に記載の放射性廃液の処理方法。     The organic acid aqueous solution is brought into contact with the radioactive organic waste to dissolve the clad adhering to the radioactive organic waste.
    After dissolution of the clad, an aqueous organic acid salt solution is brought into contact with the radioactive organic waste to elute the α-nuclide adsorbed on the radioactive organic waste.
    It contains the decomposition of the organic acid contained in the organic acid aqueous solution containing the radionuclide containing the α-nuclide in which the clad is dissolved, and the radionuclide containing the α-nuclide in which the α-nuclide is eluted. Decomposition of the organic acid salt contained in the organic acid salt aqueous solution is carried out in sequence.
    The radioactive liquid waste containing the α-nuclide produced by the decomposition of the organic acid and the organic acid salt is supplied to the filter.
    The radioactivity according to any one of claims 9 to 14, wherein the pH adjusting agent is injected into the radioactive liquid waste containing the α-nuclide before the radioactive liquid waste containing the α-nuclide reaches the filter. Waste liquid treatment method.
  16. 　前記ｐＨ調整剤以外に脱溶存炭酸剤も前記α核種を含む前記放射性廃液に注入する請求項９ないし１５のいずれか１項に記載の放射性廃液の処理方法。 The method for treating radioactive waste liquid according to any one of claims 9 to 15, wherein a dissolved carbonic acid agent is also injected into the radioactive liquid waste containing the α-nuclide in addition to the pH adjuster.
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