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WO2017006973A1 - Procédé de récupération de tritium à partir d'un absorbeur de tritium et procédé de réutilisation comme absorbeur - Google Patents

Procédé de récupération de tritium à partir d'un absorbeur de tritium et procédé de réutilisation comme absorbeur Download PDF

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WO2017006973A1
WO2017006973A1 PCT/JP2016/070057 JP2016070057W WO2017006973A1 WO 2017006973 A1 WO2017006973 A1 WO 2017006973A1 JP 2016070057 W JP2016070057 W JP 2016070057W WO 2017006973 A1 WO2017006973 A1 WO 2017006973A1
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tritium
water
manganese oxide
absorbent
electrode film
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Japanese (ja)
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古屋仲　秀樹
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Forward Science Laboratory Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D59/00—Separation of different isotopes of the same chemical element
    • B01D59/22—Separation by extracting
    • B01D59/26—Separation by extracting by sorption, i.e. absorption, adsorption, persorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/34—Regenerating or reactivating
    • 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
    • G21F9/02—Treating gases
    • 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

Definitions

  • the present invention relates to a method for recovering tritium from a tritium absorbent material and a method for reusing it as an absorbent material.
  • Tritium (T) is dissolved in light water (H 2 O) as an isotope isomer of water molecules (T 2 O, HTO).
  • Tritium (T) is an isotope of hydrogen (H), and is a radioactive element that emits ⁇ rays (electron beams) and has a half-life of 12.3 years.
  • tritium ions (T +) in order to similar chemical properties and hydrogen ions (H +), the nature remain in the body by ion exchange with hydrogen ions (H +) which constitutes the DNA in the body of an organism Have For this reason, it can be a causative substance of internal exposure and is harmful.
  • the wastewater concentration limit for tritium is set at 60,000 Bq / L (60 Bq / L) per liter of sample water in a notification that specifies dose limits based on the regulations of regulations on the installation and operation of practical power reactors. mL).
  • the hydrogen ion conductive film is disposed on one surface of the electrode and the hydrogen ion conductive film is brought into contact with the dilute acid aqueous solution, so that hydrogen ions (H + ) are continuously supplied from the dilute acid aqueous solution to the electrode.
  • a reaction system was proposed, Hideki Furuya, Yasuto Igarashi, Separation and Recovery of Tritium in Water Using Manganese Oxide Electrode Membrane, 83rd Annual Meeting of the Electrochemical Society, Lecture Number 3Q29, Osaka University (2016). Tritium contained at a low substance concentration of several nanograms per liter of water can be continuously collected from the water at room temperature into the solid phase of manganese oxide by the method using the reaction system.
  • tritium-containing water In order to efficiently separate and recover tritium collected by manganese oxide having a spinel crystal structure from the solid phase of the manganese oxide into the gas phase in the reaction vessel, tritium-containing water is used.
  • the hydrogen ion concentration (pH) is preferably acidic.
  • the pH of the tritium-containing water is preferably neutral to weakly alkaline. Hideki Koyanaka and Hideo Miyatake, Extracting Tritium from Water Using a Protonic Manganese Oxide Spinel ", Separation Science and Technology, 50, 14, 2142-2146, (2015).
  • manganese oxide when reusing manganese oxide as a tritium absorber.
  • the present invention has been made in view of the circumstances as described above, and a method for recovering tritium capable of efficiently recovering tritium from manganese oxide having a spinel crystal structure in which tritium is collected, and tritium.
  • An object is to provide an improvement in reusability as an absorbent material.
  • a method for recovering tritium includes a method in which tritium is collected from the manganese oxide in which tritium is collected in a gas phase in the reaction vessel and water containing tritium in the reaction system vessel. Tritium is released in a small amount of water (H 2 O) by releasing it as an isotope isomer (HTO) or isotope isomer (HT) of hydrogen gas, and sucking a gas containing tritium from the same gas phase with a pump or the like.
  • HTO isotope isomer
  • HT isotope isomer
  • the tritium-containing water HTO
  • oxygen O or O 2
  • copper oxide CuO
  • the tritium recovery method of the present invention is characterized by accelerating the release of tritium by irradiating the manganese oxide collecting tritium with ultraviolet light.
  • the method for recovering tritium according to the present invention includes applying tritium to a conductive gel by applying a voltage in a state where the manganese oxide that has collected tritium is in contact with a conductive gel containing lithium ions (Li + ). And a method of recovering in the electrolyte.
  • manganese oxide having a spinel crystal structure containing tritium in contact with a conductive gel containing lithium ions is used as a positive electrode
  • a carbon rod is used as a negative electrode
  • both electrodes are an aqueous solution containing an electrolyte. It is characterized by being arranged inside.
  • an appropriate amount of lithium ions (Li + ) is added to the aqueous solution in contact with the manganese oxide, and the pH of the aqueous solution in contact with the manganese oxide is adjusted from neutral to alkaline.
  • the method for recovering tritium according to the present invention comprises oxidizing an oxide having a spinel crystal structure that collects tritium by irradiating manganese oxide having a spinel crystal structure that collects tritium with various ultraviolet light such as an LED and a discharge lamp. The release of tritium from manganese may be promoted.
  • manganese oxide having a spinel crystal structure in which tritium has been collected is brought into contact with water having an acidic pH to release HTO gas or HT gas from the manganese oxide in which the tritium has been collected. May be promoted.
  • a small amount of HTO or HT released using various gas cleaning bottles for example, Walter type, Ichinose type, dresser type, Muenke type, etc.
  • a gas dissolution tower using a fine bubble foaming method You may collect
  • an electrode obtained by fixing manganese oxide powder having a spinel crystal structure to the surface of a conductive material such as metal or carbon with a conductive paint is brought into contact with tritium-containing water to obtain tritium.
  • the tritium collected in the manganese oxide may be eluted in the aqueous solution containing the conductive gel or the electrolyte by the above-described voltage application method to collect the tritium.
  • manganese oxide after collecting tritium by the recovery method may be reused as a tritium absorbent material.
  • the lithium ion-containing manganese oxide obtained by substituting tritium with lithium ions by the above recovery method from manganese oxide that has collected tritium is brought into contact with a dilute acid containing hydrogen ions. Then, the lithium ion contained in the spinel crystal structure of the manganese oxide may be regenerated as a tritium absorbent by substituting hydrogen ions.
  • the method for reusing the tritium absorbent material of the present invention is to stabilize the crystal structure of manganese oxide and adjust the pH of the aqueous solution by adding lithium hydroxide (LiOH) to tritium-containing water in contact with the manganese oxide.
  • LiOH lithium hydroxide
  • a water-soluble lithium salt such as lithium chloride (LiCl) may be added to water containing tritium in contact with the manganese oxide, and the pH of the aqueous solution may be adjusted by adding sodium hydroxide (NaOH) or the like.
  • a water-soluble lithium salt such as lithium chloride (LiCl) may be added to an aqueous solution of dilute hydrochloric acid or dilute nitric acid in contact with the manganese oxide to stabilize the crystal structure of the manganese oxide.
  • LiCl lithium chloride
  • tritium collected in manganese oxide can be efficiently recovered, and manganese oxide can be reused.
  • the tritium absorbent material of the present invention is composed of hydrogen ion-containing manganese oxide having a spinel crystal structure.
  • Lithium ion-containing manganese oxide having a spinel crystal structure is mixed using chemicals such as manganese carbonate such as manganese carbonate and manganese carbonate hydrate, lithium hydroxide such as lithium hydroxide, etc. as raw materials. It can be obtained through steps of baking and purification. Further, chemicals such as manganese-containing hydroxide and lithium-containing carbonate may be used as a raw material. Furthermore, the hydrogen ion-containing manganese oxide having a spinel crystal structure can be obtained through an acid treatment step in addition to the steps described above.
  • the above raw materials are mixed at room temperature. At this time, the mixture is mixed until it becomes black. As a result, crystal nuclei of lithium ion-containing manganese oxide having a spinel crystal structure are generated.
  • the firing step the nuclei generated in the mixing step are grown. For example, the mixture is heated in the atmosphere at a temperature of 200 ° C. to 1000 ° C., preferably 300 ° C. to 500 ° C., more preferably 350 ° C. to 450 ° C. for about 1 hour to 10 hours.
  • the fired product obtained in the firing step is suspended in weakly alkaline pure water, and then allowed to stand for a certain time to collect the precipitate.
  • This precipitate is lithium ion-containing manganese oxide having a spinel crystal structure.
  • the precipitate recovered by filtration or the like may be stored in a cool and dark place in a wet state.
  • lithium ion-containing manganese oxide having a spinel crystal structure is suspended and stirred in an acidic solution such as dilute hydrochloric acid aqueous solution, and then solid-liquid separation is performed.
  • an acidic solution such as dilute hydrochloric acid aqueous solution
  • the hydrogen ion-containing manganese oxide powder having a spinel crystal structure is stored in a cool and dark place in a wet state.
  • the powder should not be dried.
  • the reason for this is that when the reaction in which hydrogen ions in the crystal structure evaporate from the crystal as water progresses due to the drying treatment, the crystal structure changes to the crystal structure of lambda-type manganese dioxide that does not contain ion-exchangeable hydrogen ions, As a result, H. ⁇ Koyanaka, and H. Miyatake, Extracting tritium from water using a protonic manganese oxide spinel ", Separation Science and Technology, 50, 14, 2142 -Reported on 2146, Jun (2015).
  • the hydrogen ion-containing manganese oxide having a spinel crystal structure obtained from the above series of steps constitutes a tritium absorber.
  • the tritium absorbent material is also composed of hydrogen ion-containing manganese oxide having a spinel crystal structure synthesized by a method other than that described above.
  • the hydrogen ion-containing manganese oxide having a spinel crystal structure preferably has a primary particle diameter in the range of 20 to 70 nm from the viewpoint of tritium absorption ability.
  • the firing temperature may be set in the range of 350 ° C. to 450 ° C. in the above-described firing step.
  • the tritium-absorbing electrode film can constitute the electrode film as a structure comprising the above-described lithium ion-containing manganese oxide powder having a spinel crystal structure, a resin binder, and a hydrogen ion conductive film.
  • the electrode film has manganese oxide powder fixed on the surface of a conductive material such as a metal or carbon material with a conductive paint, and a hydrogen ion conductive material such as Nafion (registered trademark). It can comprise by arranging on the single side
  • the tritium absorption electrode film is formed by applying lithium ion-containing manganese oxide powder having a spinel crystal structure to a platinum mesh surface by applying and drying with a conductive paint containing a carbon filler, and then fixing the hydrogen. It is obtained by applying and drying an ion conductive material on one side of the electrode film and fixing it.
  • a dilute acid lithium ions can be eluted from the lithium ion-containing manganese oxide having a spinel crystal structure in the electrode film to be changed to hydrogen ion-containing manganese oxide.
  • the powdery absorbent material that collects tritium without forming an electrode may be packed in a metal container or the like, and a voltage applied.
  • the same electrode film containing manganese oxide that has collected tritium from weakly acidic to alkaline tritium-containing water is brought into contact with an acidic aqueous solution to bring the tritium into the reaction vessel. It is characterized by being discharged as water (HTO) gas containing tritium in the gas phase or hydrogen (HT) gas.
  • HTO water
  • HT hydrogen
  • Oxygen in the same gas phase is supplied from an oxidative decomposition reaction (OT ⁇ ⁇ T + + 2e ⁇ + (1/2) O 2 ) of hydroxide ions (OT ⁇ ) contained in tritium-containing water.
  • manganese dioxide MnO 2
  • OH ⁇ hydroxide ions
  • the HTO gas released from the electrode film collecting tritium into the gas phase in the reaction vessel can be easily sucked and removed from the gas phase in the reaction vessel with a vacuum pump or the like. For this reason, tritium can be recovered by introducing a gas containing the HTO gas removed by suction into a small amount of water (H 2 O).
  • the HT gas released from the electrode film that collects the tritium is introduced into a heat resistant glass tube and heated to 250 ° C. to 500 ° C.
  • the tritium can be collected by oxidizing HT to convert it to HTO by introducing it into a small amount of water (H 2 O) as described above.
  • the tritium recovery method of the present embodiment accelerates the release of tritium from the electrode film into water by irradiating the electrode film collecting the tritium with ultraviolet light, and in a small amount of water (H 2 O). In addition, tritium can be recovered.
  • a voltage is applied to the electrode film that collects the tritium in contact with a gel containing lithium ions, so that lithium ions contained in the gel are converted to manganese oxide.
  • a voltage is applied to the electrode film that collects the tritium in contact with a gel containing lithium ions, so that lithium ions contained in the gel are converted to manganese oxide.
  • tritium contained in the manganese oxide is eluted into the gel and an aqueous electrolyte solution electrically connected to the gel.
  • manganese oxide having a spinel crystal structure into which lithium ions are inserted can be obtained by the same recovery method. If lithium ions are replaced with hydrogen ions by acid treatment with dilute acid again, a hydrogen ion-containing manganese oxide maintaining a spinel crystal structure can be obtained, so that it can be easily reused as a tritium absorbent. .
  • the method for reusing a tritium absorbent material of the present embodiment is characterized in that after releasing tritium from the electrode film collecting tritium as HTO or HT, lithium ions are added to an aqueous solution in contact with the electrode film.
  • This is a method of reusing tritium absorbent.
  • the spinel-type manganese oxide after the release of tritium has an unstable crystal structure in neutral to alkaline water, and manganese ions are eluted from the manganese oxide.
  • the electrode film contains lithium ions (Li + ).
  • a water-soluble chemical containing lithium such as lithium chloride so that the lithium concentration in the aqueous solution in contact with the electrode film is several tens mg / L or less per gram of manganese oxide contained (LiCl), lithium hydroxide (LiOH) and the like were added.
  • the method of recovering tritium from an electrode film composed of manganese oxide powder having a spinel crystal structure or collecting the tritium according to the present invention provides simple tritium recovery at room temperature.
  • it provides an economical technology that can reuse the manganese oxide after tritium recovery as a tritium absorber.
  • a tritium absorbent material composed of hydrogen ion-containing manganese oxide having a spinel crystal structure was synthesized according to the following procedure.
  • ⁇ Mixing with raw materials> Reagent manganese carbonate hydrate (MnCO 3 ⁇ nH 2 O) and lithium hydroxide hydrate (LiOH ⁇ H 2 O) powder are mixed at a weight ratio of 2 to 1 and blackened at room temperature. Mix well until ⁇ Firing> The mixed powder was heated in the atmosphere at 390 ° C. for 6 hours using an electric furnace, and then cooled to room temperature.
  • the supernatant manganese carbonate was removed using an aspirator or the like, and a lithium ion-containing manganese oxide powder having a precipitated spinel crystal structure was recovered.
  • the pH of ion-exchanged pure water in which the powder was suspended was maintained from a weak alkali to an alkali side.
  • ⁇ Storage> The lithium ion-containing manganese oxide powder having a spinel crystal structure recovered by filtration or the like was stored in a cool and dark place. When a drying treatment was necessary, the film was dried at room temperature under reduced pressure (about minus 50 cmHg). Or it dried at the temperature of 100 degrees C or less under atmospheric pressure.
  • the lithium-containing manganese oxide powder obtained by the above synthesis method is fixed to the surface of a platinum mesh or stainless steel mesh using a commercially available conductive paint, and heated and dried at 150 ° C. in the atmosphere using a dryer. A membrane was created. Thereafter, a Nafion (registered trademark) dispersion is applied to one side of the electrode film, dried at 60 ° C. in the atmosphere, and then heated at 120 ° C. in the atmosphere to form a hydrogen ion conductive film on the surface of the electrode film.
  • the tritium absorbing electrode film was manufactured by fixing.
  • HTO Tritium-containing water
  • HT Hydrogen
  • the analytical test apparatus is composed of a cathode (voltage: 0 V) of an aluminum tube (diameter 8 cm, length 50 cm) to which a voltage is applied and a gold wire plated tungsten wire (diameter 20) at the center of the aluminum tube.
  • a proportional counter composed of ( ⁇ m) anode (voltage: +1750 V) is used as a detector.
  • This detector analyzes the waveform of the output voltage obtained by introducing the sample gas together with the carrier gas at a pressure of 900 KPa, and generates a wave height (a signal derived from tritium and a background signal derived from external radiation such as cosmic rays). By distinguishing from the difference in energy and rise time, it is possible to detect tritium at a very low concentration (detection limit: 1 Bq / L) contained in the gas.
  • GC-MASS gas chromatograph mass spectrometry
  • Tritium collected by the tritium absorbing electrode film was collected in a gel containing lithium ions and water containing an electrolyte as follows.
  • the upper half of the electrode film in which tritium was collected was inserted into a gel containing lithium ions filled in a metal mold.
  • the lower part of the electrode film inserted into the gel was brought into contact with an aqueous electrolyte solution containing lithium ions.
  • the gel is prepared by adding a reagent lithium chloride powder and a reagent agar powder to distilled water and heating the mixture. After sufficiently dissolving the agar powder, the gel is poured into a stainless steel mold and allowed to stand at room temperature to solidify the agar. Created.
  • membrane which collected tritium was made to contact the distilled water which added electrolyte.
  • Examples of the electrolyte that can be used include hydroxides and chlorides such as lithium, sodium, and potassium, or dilute hydrochloric acid, dilute sulfuric acid, and dilute nitric acid.
  • an electrode such as a carbon rod is arranged, and an electrode film containing tritium inserted in the gel in the metal mold placed in the conductive aqueous solution is used as a positive electrode, and the electrode film is arranged in the conductive aqueous solution.
  • a carbon rod was used as the negative electrode.
  • the above-mentioned chemical containing lithium was added so that the amount of lithium in the tritium-containing water did not exceed about 30 mg per gram of the tritium absorbent powder. Moreover, the addition amount was set so that the lithium concentration in the tritium-containing water did not exceed 50 mg / L. If the amount of lithium added is too large, the hydrogen-containing manganese oxide will dissolve, so the amount of lithium added should be limited to the above-mentioned appropriate amount. By adding an appropriate amount of lithium, the crystal structure of spinel-type manganese oxide after tritium release is stabilized.
  • the valence of manganese (Mn) constituting the hydrogen ion-containing manganese oxide is +3.5. Therefore, it is considered that HMn 2 O 4 obtained by replacing lithium ions with hydrogen ions by acid treatment maintains +3.5 valence in order to maintain charge neutrality.
  • the spinel-type hydrogen ion-containing manganese oxide obtained by acid treatment of spinel-type lithium-containing manganese oxide baked at a relatively low temperature of 390 ° C. as in the present invention is as follows.
  • the spinel crystal structure lithium manganese oxide obtained by firing at a high temperature such as 500 to 1000 ° C. has a remarkably higher degree of freedom regarding the movement of hydrogen ions inside the crystal.
  • H. Koyanaka, O. Matsubaya, Y. Koyanaka, and N. Hatta Quantitative correlation between Li absorption and H content in Manganese Oxide Spinel ⁇ -MnO 2 ", Journal of Electroanalytical Chemistry 559 (2003) 77-81, and H. Koyanaka, Y. Ueda, K.
  • a tritium absorbent was prepared using a sample prepared by stirring hydrogen ion-containing manganese oxide (about 1 g) functioning as a tritium absorbent in 100 mL of ultrapure water (H 2 O) for 2 days.
  • the valence of Mn constituting was examined by X-ray absorption spectroscopy. This analysis method was described in detail in Example 5 below.
  • the hydrogen ion-containing manganese oxide that functions as the tritium absorbent material had the same spinel crystal structure as the previous knowledge (WO2015 / 037734). It was newly revealed that most manganese valences are +4.
  • composition formula of the present tritium absorbent is (H + , e ⁇ ) x Mn 2 O 4 , and hydrogen ions (H + ) having a high degree of freedom of movement (conductivity) in the crystal.
  • the electron (e ⁇ ) is not involved in the d orbital of manganese.
  • the tritium absorber collects tritium in water in the solid phase of the absorber and releases it into the gas phase as water molecule (HTO) gas containing tritium from the solid phase. It was suggested that it progressed like this.
  • Chemical formula (1) shows a reaction in which the present absorbent (H + , e ⁇ ) x Mn 2 O 4 is obtained by acid treatment of lithium ion-containing manganese oxide.
  • the chemical formula (2) is based on the ion exchange reaction of H + and T + accompanied by an oxidative decomposition reaction with respect to OT ⁇ in tritium-containing water. Reactions trapped in the structure are shown.
  • Chemical formula (3) shows a reaction in which the present absorbent releases tritium as hydrogen gas (HT) from the spinel crystal structure in acidic water.
  • Chemical formula (4) shows an apparent reaction in which the formulas (2) and (3) are integrated, and tritium present in water as OT ⁇ is HTO gas and the reaction vessel is exposed from the position where the present absorbent is exposed to the gas phase. It shows the reaction released by evaporation to the gas phase inside.
  • the symbol x represents the molar ratio of hydrogen ions or lithium ions contained in the absorbent to other components
  • y represents the molar ratio of tritium absorbed in the absorbent to other components
  • the molar ratio of water (HTO) gas containing tritium generated and hydrogen gas (HT) is shown.
  • this absorbent material when this absorbent material is applied as the electrode film, hydrogen ions (H + ) are replenished from the dilute aqueous acid solution through the hydrogen ion conductive film to the empty adsorbing site. It is considered that the present absorbent (H + , e ⁇ ) x Mn 2 O 4 on the left side of is reconstructed, and as a result, the tritium absorption reaction is sustained. Furthermore, this absorbent material can selectively absorb and separate tritium from water.
  • (H + , e ⁇ ) xy ( ⁇ , e ⁇ ) y Mn 2 O 4 shown on the right side of the chemical formula (3) indicates spinel-type manganese oxide after the release of tritium ions (T + ).
  • T + tritium ions
  • lithium of about 1 to 30 mg per gram of the tritium absorbent material of the present invention, and the lithium concentration in the aqueous solution in contact with the tritium absorbent material is about 1 to 50 mg / L from the water using the present manganese oxide. This is preferable for the collection and recovery of tritium.
  • the tritium-absorbing electrode film of the present invention by applying the tritium-absorbing electrode film of the present invention to weakly acidic to alkaline (for example, pH 6-9) tritium-containing water in the reaction vessel, tritium in water is continuously collected, and tritium-containing water is further collected.
  • pH is acidic (for example, pH 3 or lower)
  • the release of tritium becomes active.
  • the reusability of this tritium absorbent material can be improved by adding lithium ions to the aqueous solution in contact with the tritium absorbent electrode film.
  • the technique of the present invention has made it possible to recover low-concentration tritium in water significantly more easily and at a lower cost than conventional techniques.
  • Example 1 ⁇ Tritium collection test using an electrode film in which a Nafion (registered trademark) film is coated on one side of an electrode film containing hydrogen oxide-containing manganese oxide having a spinel crystal structure>
  • a tritium absorbent material composed of lithium ion-containing manganese oxide having a spinel crystal structure and hydrogen ion-containing manganese oxide having a spinel crystal structure was synthesized.
  • a tritium absorbent material composed of lithium ion-containing manganese oxide having a spinel crystal structure with a primary particle size of 20 to 70 nm and hydrogen ion-containing manganese oxide having a spinel crystal structure was obtained.
  • dilute nitric acid (7 M) with a concentration of 0.5 M to donate hydrogen ions (H + ) to the electrode film constituting the tritium absorption electrode film unit shown in FIG. 0.0 mL) was used.
  • the acrylic plate and the silicone rubber film waterproof seal constituting the unit, and the acrylic container have a circular hole (area 12.2 mm).
  • dilute nitric acid was removed from the unit and the cubic acrylic container, and the inner surfaces of these containers were sufficiently rinsed with distilled water to wash away the dilute nitric acid.
  • 7.0 mL of dilute nitric acid with a concentration of 0.5 M was newly injected from the small hole at the top of the unit, and this was added to 140 mL of tritium-containing water with a radioactive concentration of 3105 Bq / mL placed in a cubic acrylic container. Soaked. Further, a copper wire was connected to the upper end of the electrode film and grounded to the ground.
  • FIG. The experimental results are shown in FIG.
  • the figure shows the change with time of the radioactivity concentration of tritium in tritium-containing water. From the figure, it can be seen that the tritium radioactivity concentration of tritium-containing water continuously decreases. During the experiment, since the pH of the tritium-containing water gradually decreased, the pH of the tritium-containing water was maintained at 3.0 or more and 9.7 or less by dropping a 0.1M or 0.5M aqueous sodium hydroxide solution at an appropriate time.
  • the position of the electrode membrane unit immersed in the tritium-containing water was finely adjusted at the time of sample collection, so that the water surface of the tritium-containing water filled in the cubic acrylic container and the rarely injected into the electrode membrane unit were A difference in water level between the nitric acid and the water surface was prevented. This is to prevent a static pressure load from being applied to the electrode film due to the same water level difference.
  • the radioactivity concentration of tritium in the tritium-containing water in this experiment varied from the initial concentration (3105 Bq / mL) to the final concentration (2777 Bq / mL).
  • Example 2 ⁇ Detection test of tritium evaporating from an electrode film containing a hydrogen ion-containing manganese oxide having a spinel crystal structure and coated with a Nafion (registered trademark) film on one side>
  • HTO tritium-containing water
  • HT hydrogen gas
  • the experimental system in this example is shown in FIG. Experiments were conducted according to the same method as in Example 1 with respect to the method for synthesizing the tritium absorbent material, the method for preparing the electrode film, the method for arranging the electrode film, and the method for measuring the tritium concentration.
  • FIG. 1 This experimental system is shown in FIG.
  • the unit in which the tritium absorbing electrode film was arranged was immersed in 140 mL of tritium-containing test water having an initial tritium concentration of 5450 Bq / mL filled in a transparent acrylic resin container (5.8 ⁇ 5.8 ⁇ 5.8 cm 3 ).
  • the unit in which the electrode film was arranged was arranged in another transparent acrylic resin sealed container (7.8 ⁇ 7.8 ⁇ 7.8 cm 3 ).
  • Example 3> ⁇ Experiment for recovering tritium evaporated from an electrode film containing a hydrogen ion-containing manganese oxide having a spinel crystal structure and coated with a Nafion (registered trademark) film on one side>
  • the reaction system shown in FIG. In the reaction system, the tritium absorbing electrode membrane is brought into contact with tritium-containing water in a sealed container, the gas in the head space inside the reaction container is passed through a molecular sieve and dehydrated, and then the copper oxide heated to 400 ° C. ( CuO) and 0.1 g were contacted to oxidize HT gas contained in the gas to HTO and attempt to recover it in distilled water in a gas washing bottle.
  • CuO copper oxide heated to 400 ° C.
  • 0.1 g were contacted to oxidize HT gas contained in the gas to HTO and attempt to recover it in distilled water in a gas washing bottle.
  • the tritium absorption electrode film was manufactured by heating at 120 ° C. in the atmosphere for 1 hour to fix the film as a hydrogen ion conductive film on the surface of the electrode film.
  • This electrode film was placed in the acrylic resin container shown in FIG. 3 (a), and 200 mL of dilute nitric acid having a concentration of 0.5 M was injected into both the tritium-containing water tank side and the dilute nitric acid tank, and held for 1 hour. .
  • the dilute nitric acid on the tritium-containing water tank side was stirred for 1 hour by a magnetic stirrer using a stirring bar coated with Teflon (registered trademark).
  • the composition of the lithium ion-containing manganese oxide contained in the electrode film is changed to hydrogen ion-containing manganese oxide by eluting lithium ions into the dilute nitric acid.
  • the dilute nitric acid was removed by sufficiently rinsing with distilled water.
  • FIG. 3A shows a reaction vessel of this experimental system.
  • the reaction vessel is a reaction vessel made of an acrylic resin partitioned by a tritium absorption electrode film containing hydrogen ion-containing manganese oxide manufactured by the above method. Furthermore, 1 cm from the upper end of the electrode film to which the manganese oxide was fixed was disposed so as to protrude from the water surface of the tritium-containing water and contact the gas phase.
  • tritium-containing water tank On the side of the tritium-containing water tank, 200 mL of tritium-containing water (initial tritium radioactivity concentration: 99253 Bq / mL, adjusted to an initial pH of 9.29 by adding a 0.1 M sodium hydroxide aqueous solution) was placed, and the dilute nitric acid water tank Distributed 200 mL of dilute nitric acid with a concentration of 0.5M. At that time, the water temperature of the tritium-containing water was 20.0 ° C. The electrode film was grounded through a copper wire. The tritium-containing water was stirred with a magnetic stirrer using a stir bar coated with Teflon (registered trademark). The pH of the tritium-containing water was maintained at pH 6.8 to 9.0 by adding a 0.1 M aqueous sodium hydroxide solution.
  • the gas in the head space inside the reaction vessel shown in FIG. 3 (a) is pumped by a pump (JPO W600, discharge pressure: 0.16 kg / cm 2 ), and has a length of 40 cm, an outer diameter of 9 mm, and an inner diameter of 7 mm.
  • a pump JPO W600, discharge pressure: 0.16 kg / cm 2
  • Contact was made with copper oxide (0.1 g, CuO: 99.9%, powder, Wako Pure Chemical Industries, Ltd. 038-13191) placed in a glass tube.
  • the outer wall of the quartz glass tube was heated and held at 400 ° C. using a heater (Daika Electric Type CL, 100 V, 60 W) with a temperature controller (ASONE TC-3000). By this heating, the temperature of the copper oxide disposed in the quartz glass tube was maintained at 350 to 400 ° C.
  • the position of the copper oxide powder in the quartz glass tube is fixed using glass wool (TOSO Grade: fine 2 to 6 ⁇ m, coarse 4 to 9 ⁇ m). Further, in the quartz glass tube, water penetrates into the front stage of the copper oxide. In order to prevent this, molecular sieve 3A1 / 16 (Wako Pure Chemical Industries 134-06095) was fixed with glass wool.
  • FIG. 3 (b) shows the change in the amount of tritium recovered in the water in the Walter type gas cleaning bottle.
  • a result was obtained in which the amount of tritium recovered during 25 hours increased linearly. This increase is caused by the movement of tritium absorbed in the tritium-absorbing electrode film from the tritium-containing water into the gas phase as a gas containing tritium (HTO or HT), and HT and copper oxide in the reaction system of FIG. This is considered to be the result of reaction, conversion to water HTO, and accumulation in the water of the Walter gas scrubber.
  • HTO or HT gas containing tritium
  • the outer wall temperature of the peripheral glass tube where the copper oxide powder is located in the quartz glass tube was kept at 350 to 400 ° C.
  • the temperature was set at 270 ° C., no increase in the radioactivity of tritium in water in the Walter gas scrubber was observed. This is presumably because the temperature in the tube was not sufficiently raised to 250 ° C., which is the minimum temperature required for the oxidation reaction of hydrogen gas using copper oxide.
  • the gas in the headspace of the experimental system of this example was introduced into a hydrogen isotope concentration analysis test apparatus in gas manufactured by IsoShield using a mixed gas of 10% methane and 90% argon (flow rate 300 mL / min) as a carrier gas. It was confirmed that tritium was contained in the gas in the head space.
  • the gas in the head space inside the reaction vessel is mixed with a mixed gas of 10% methane and 90% argon (flow rate 300 mL / min), which is the carrier gas of the apparatus, and a glass tube made of Pyrex (registered trademark).
  • a sample of test water 150 mL was prepared by irradiating the tritium-absorbing electrode film with ultraviolet light from the outside of the reaction vessel using the acrylic resin reaction vessel shown in FIG.
  • the change in the tritium concentration was investigated.
  • a small hole (diameter 5 mm) is provided in the acrylic plate at the top of the reaction vessel, and a silicon tube can be inserted into the tritium-containing test water from the small hole to collect the sample of the test water. I did it.
  • the small holes were sealed with aluminum tape except during sample collection.
  • UV-LED (wavelength: 375 nm, three-lamp specification, with lens, PW-UV343H-02) manufactured by Nichia Chemical Co., Ltd., contact surface of tritium-absorbing electrode film with test water containing tritium For one hour through the acrylic wall of the reaction vessel.
  • a disposable filter (DISMIC AS-25) manufactured by Advantech, and emitted as ⁇ -rays as a scintillator.
  • the radioactivity concentration derived from tritium from about 1.0 mL of the sample was measured.
  • the tritium radioactivity concentration in the tritium-containing test water 150 mL was 3737 Bq / mL before irradiation with the same ultraviolet light, and after the irradiation was continued for 1 hour, the tritium radioactivity concentration in the tritium-containing test water was It increased to 3752 Bq / mL.
  • the radioactivity concentration of tritium was reduced to 3672 Bq / mL in a sample collected 40 minutes after the irradiation was stopped.
  • This variation in tritium radioactivity concentration caused by ultraviolet light irradiation is suggested to be based on the phenomenon that tritium is eluted from the electrode film into water by ultraviolet light irradiation. That is, the irradiation of the tritium-absorbing electrode film with ultraviolet light has the effect of promoting the release of tritium from the electrode film, and the tritium released in the test water containing tritium is re-dissolved in the test water containing tritium. The concentration is thought to have increased. Further, it is considered that the radioactivity concentration of tritium decreased as a result of reducing the amount of tritium released from the electrode film by stopping the irradiation of ultraviolet light and restarting the absorption of tritium by the electrode film.
  • An electrode film containing hydrogen ion-containing manganese oxide with one side coated with a Nafion (registered trademark) film was prepared in the same manner as in Example 3.
  • the reaction system shown in FIG. 4A was configured, and tritium-containing water was brought into contact with the electrode film coated with a Nafion (registered trademark) film on one side.
  • tritium is evaporated to the gas phase inside the reaction vessel from the surface where the electrode film is in contact with the gas phase inside the reaction vessel, and sucked through a silicon tube into distilled water disposed in the gas washing bottle 1 by a pump. It was collected.
  • the reaction vessel and the pump were connected with a silicon tube.
  • the gas exhausted from the gas cleaning bottle 1 is brought into contact with 0.1 g of copper monoxide (CuO) heated to 400 ° C. with a heater in the same manner as in the third embodiment, and led to the gas cleaning bottle 2 in the subsequent stage. Then, it was returned from the upper part of the same reaction vessel and circulated again.
  • CuO copper monoxide
  • the inside of the reaction vessel is prevented from becoming negative pressure due to pressure loss caused by circulation of the headspace gas inside the reaction vessel, Experiments were performed under atmospheric pressure.
  • a transparent acrylic water tank was divided into two tanks by the electrode film containing the lithium ion-containing manganese oxide powder.
  • each seam of the acrylic tank was coated with a silicon sealer (Chemedine Bascoke) and dried for 2 days.
  • the head space of the water tank containing tritium-containing water and the water tank containing the dilute nitric acid aqueous solution is shared by both tanks, and external air is sucked into the reaction system.
  • the pressure applied to the electrode membrane partitioning both water tanks was considered to be equal.
  • lithium ion-containing manganese oxide having a spinel crystal structure was synthesized according to the method described in Example 1 above.
  • 0.83 g of lithium ion-containing manganese oxide powder was formed on the surface (4 cm ⁇ 3 cm ⁇ 0.16 cm) of a stainless mesh (SUS304, 100 mesh, 6 cm ⁇ 3 cm ⁇ 0.16 cm).
  • a stainless mesh SUS304, 100 mesh, 6 cm ⁇ 3 cm ⁇ 0.16 cm.
  • a Nafion (registered trademark) dispersion made by Wako Pure Chemical Industries, Ltd.
  • the acrylic plate and the silicone rubber membrane waterproof seal constituting the unit, and the acrylic container have a circular hole (area of 4 mm in diameter). 12.6 mm 2 ) are provided at five locations, so that the total area of the contact holes is 63.0 mm 2 . Furthermore, 1 cm from the upper end of the electrode film to which the manganese oxide was fixed was disposed so as to protrude from the water surface of the tritium-containing water and contact the gas phase.
  • the electrode film was acid-treated in a water tank in the reaction vessel shown in FIG.
  • 200 mL of dilute nitric acid having a concentration of 0.5 M is filled in both water tanks in the reaction vessel, and left for 1 hour to dilute lithium from the lithium ion-containing manganese oxide contained in the electrode film.
  • the composition was changed to hydrogen ion-containing manganese oxide.
  • the dilute nitric acid was removed from both the water tanks, and the dilute nitric acid was washed away from the inner surfaces of both the water tanks by leaving it to stand for 1 hour in a state where each of the water tanks was filled with 200 mL of distilled water.
  • tritium-containing water When preparing tritium-containing water, dilute tritium standard reagent (PerkinElmer 3 H, water) with 200 mL of room-temperature distilled water (manufactured by Wako Pure Chemical Industries, Ltd.) to obtain tritium-containing water with a radioactivity concentration of 4408.7 Bq / mL. was formulated. Next, the tritium-containing water (200 mL) is placed in the right-side water tank in FIG. 4A, and a 0.5 M dilute nitric acid aqueous solution (200 mL) (manufactured by Wako Pure Chemical Industries, Ltd.) is placed in the left-side water tank. Arranged.
  • dilute tritium standard reagent PerkinElmer 3 H, water
  • room-temperature distilled water manufactured by Wako Pure Chemical Industries, Ltd.
  • the reaction surface covered with Nafion (registered trademark) of the electrode film is a surface in contact with dilute nitric acid
  • the reaction surface of the electrode film in which the hydrogen ion-containing manganese oxide absorbent having a spinel crystal structure is exposed is a surface in contact with tritium-containing water.
  • the tritium-containing water and the dilute nitric acid aqueous solution filled in each of these two tanks, and the time-dependent change in the radioactivity concentration of tritium in distilled water (50 mL) arranged in advance in two gas washing bottles are shown in Example 1.
  • the liquid scintillation counter was used in the same manner as in 2 and 3.
  • the exhaust from the gas cleaning bottle 1 was brought into contact with 0.1 g of copper oxide (CuO) (038-13191 manufactured by Wako Pure Chemical Industries, Ltd.) heated and held at 400 ° C. in a quartz glass tube.
  • CuO copper oxide
  • the copper oxide powder is fixed in a quartz glass tube with glass wool (TOSO Grade: 2 to 6 ⁇ m, coarse 4 to 9 ⁇ m), and the outer wall of the glass tube is heated to a temperature. Heated with a heater (Osaka Denki Type CL, 100V, 60W) with a controller (ASONE TC-3000).
  • the gas that passed through the CuO was introduced into 50 mL of distilled water (manufactured by Wako Pure Chemical Industries, Ltd.) arranged in advance in a subsequent gas cleaning bottle 2 (Walter type: total volume 100 mL).
  • the buffer chamber was provided in piping of this experimental system.
  • the tritium-containing water at room temperature (15.7 to 21.6 ° C.) was stirred at a concentration of 0 while stirring the tritium-containing water with a stirrer coated with Teflon (registered trademark) and a magnetic stirrer.
  • the experiment was continued until it was adjusted to an initial pH of 9.36 by adding an appropriate amount of 1 M or 0.5 M sodium hydroxide aqueous solution, and then decreased to pH 4 or less spontaneously.
  • an aqueous sodium hydroxide solution was added to the tritium-containing water again to increase the pH to 8.10, and then the experiment was continued until it naturally decreased to pH 5 or lower again.
  • FIG.4 (b) shows the time-dependent change of the tritium radioactivity density
  • the vertical axis represents the tritium radioactivity concentration of the sample water, and the horizontal axis represents the reaction time.
  • a sample S1 in the figure
  • an aqueous sodium hydroxide solution was added again to raise the pH to 8.1. At that time, tritium-containing water colored light brown by the same pH adjustment.
  • FIG. 4C shows the change in tritium radioactivity concentration in 50 mL of distilled water disposed in the gas cleaning bottle 1 in the previous stage. From the figure, it was found that approximately 15885 Bq of tritium was recovered in the same distilled water after 50 hours. This is about 5 times more recovered than 3235 Bq recovered after 74 hours in 50 mL of distilled water placed in a similar gas washing bottle after contact with the molecular sieve in Example 3.
  • the distilled water in the gas cleaning bottle 1 almost maintained the volume obtained by subtracting the volume collected as a sample from the initial volume of 50 mL. Furthermore, the distilled water at the time when 50 hours passed in the gas cleaning bottle 1 was analyzed by atomic absorption method, and the concentrations of manganese (Mn), lithium (Li), and sodium (Na) contained in the distilled water were measured. As a result, it was confirmed that the Mn and Li concentrations were 0.01 mg / L below the detection limit, and the Na concentration was 0.48 mg / L.
  • the tritium extracted from the tritium-containing water is mainly contained in the distilled water of the gas washing bottle 1. You can see that it was recovered. As a result, the total amount of tritium confirmed to move to the distilled water and dilute nitric acid in the two gas washing bottles after 50 hours was 22605.8 Bq.
  • the total decrease amount of tritium calculated from the decrease value of the tritium concentration of the tritium-containing water shown in FIG. 4B is 71116.5 Bq, it is about 31.8% of the total decrease amount. Thus, 22605.8 Bq of tritium corresponding to the above could be recovered. About the remaining 68.2% of tritium, water droplets adhere to the inner wall surface of the reaction vessel during the experiment. Therefore, it is considered that these water droplets are not collected and reach the gas washing bottle 1. It is done.
  • An electrode film containing hydrogen ion-containing manganese oxide with one side coated with a Nafion (registered trademark) film was prepared in the same manner as in Examples 1, 2, 3, and 4.
  • the reaction system shown in FIG. 5 was configured, and tritium-containing water was brought into contact with the electrode film coated with a Nafion (registered trademark) film on one side.
  • tritium is evaporated from the surface of the reaction vessel where the electrode film is in contact with the gas phase into the gas phase inside the reaction vessel, and a tube made of Teflon (registered trademark) is applied to ultrapure water disposed in a gas cleaning bottle by a pump. It was pumped through and collected.
  • the reaction vessel and the pump were connected with a silicon tube.
  • a transparent acrylic water tank was divided into two tanks by an electrode film containing lithium ion-containing manganese oxide powder coated with a Nafion (registered trademark) film on one side.
  • each seam of the acrylic tank was coated with a silicon sealer (Chemedine Bascoke) and dried for 2 days.
  • the head space of the water tank in which tritium-containing water is arranged and the water tank in which dilute hydrochloric acid is arranged are shared by both tanks, and both water tanks are supplied when external air is supplied to the reaction system. Consideration was made so that the pressure applied to the electrode film partitioning was equal.
  • lithium ion-containing manganese oxide powder having a spinel crystal structure was synthesized according to the method described in Example 1.
  • lithium ion-containing manganese oxide powder 0 was applied to the surface (3.5 cm ⁇ 3 cm ⁇ 0.16 cm) of a platinum mesh (100 mesh, 5.5 cm ⁇ 3 cm ⁇ 0.16 cm). .92 g was heated and fixed in the same manner using the conductive paint.
  • a Nafion (registered trademark) dispersion made by Wako Pure Chemical Industries, Ltd.
  • drying in the atmosphere at 60 ° C. for 2 hours was repeated twice.
  • Nafion (registered trademark) was fixed to one surface of the electrode film as a hydrogen ion conductive film by heating in the atmosphere at 120 ° C. for 1 hour.
  • the film thickness of the obtained electrode film was about 1.3 mm.
  • the acrylic plate and the silicone rubber membrane waterproof seal constituting the electrode membrane unit, and the acrylic container have a circular hole ( The total contact area was 12.56 mm 2 by providing four areas (area 3.14 mm 2 ).
  • 1.5 cm from the upper end of the electrode film to which the manganese oxide was fixed was disposed so as to protrude from the water surface of the tritium-containing water and to come into contact with the gas phase.
  • the electrode film was acid-treated in the reaction vessel shown in FIG.
  • 200 mL of dilute hydrochloric acid aqueous solution having a concentration of 0.5 M is filled in both water tanks of the reaction vessel, and left for 1 hour, so that lithium is contained from the lithium ion-containing manganese oxide contained in the electrode film.
  • the composition was changed to manganese ion-containing manganese oxide.
  • the dilute hydrochloric acid aqueous solution was removed from both water tanks, and the dilute hydrochloric acid was washed off from the inner surfaces of both water tanks by leaving the both water tanks filled with 200 mL of ultrapure water for 1 hour.
  • a tritium standard reagent (PerkinElmer 3 H, water) was diluted with 150 mL of ultrapure water at room temperature to prepare tritium-containing water having a radioactivity concentration of 4054.2 Bq / mL.
  • 150 mL of the tritium-containing water was placed in the right-side water tank in FIG. 5, and 150 mL of a dilute hydrochloric acid aqueous solution having a concentration of 0.5 M (manufactured by Wako Pure Chemical Industries, Ltd.) was placed in the left-side water tank.
  • the reaction surface of the electrode film coated with Nafion is the surface in contact with dilute hydrochloric acid
  • the reaction surface of the electrode film with exposed hydrogen ion-containing manganese oxide absorbent having a spinel crystal structure is the surface in contact with tritium-containing water.
  • tritium-containing water and dilute hydrochloric acid aqueous solution filled in each of these two tanks, and time-dependent changes in the radioactivity concentration of tritium in 50 mL of ultrapure water previously arranged in a gas washing bottle were measured in Examples 1, 2, 3, and In the same manner as in No. 4, a liquid scintillation counter was used.
  • the pH and temperature of tritium-containing water were monitored using a pH meter (HORIBA pH meter, F-55 glass electrode type 6378-10D) and pH test paper.
  • the electrode film was grounded to the earth using a copper wire.
  • the gas in the head space inside the reaction vessel was pumped using a small pump (EP-01 manufactured by ADVANTEC), and a Teflon (registered trademark) tube (outer diameter 3 mm, inner diameter 2 mm). And introduced into 50 mL of ultrapure water (manufactured by Wako Pure Chemical Industries, Ltd.) arranged in advance in a gas washing bottle (Walter type: total volume 100 mL).
  • tritium-containing water at room temperature (24.0 to 28.2 ° C.) was stirred at a concentration of 0 while stirring the tritium-containing water with a stirrer coated with Teflon (registered trademark) and a magnetic stirrer.
  • Teflon registered trademark
  • a magnetic stirrer After adjusting to an initial pH of 9.26 by adding an appropriate amount of 1 M or 0.5 M sodium hydroxide aqueous solution, the experiment was continued until it naturally decreased to pH 2.7 or lower.
  • an aqueous sodium hydroxide solution was added again to the tritium-containing water to raise the pH to 7, and then the experiment was continued until it naturally decreased to pH 2.7 or lower again. The experiment was continued for 89 hours while such readjustment of pH with respect to tritium-containing water was repeated 5 times.
  • each sample was collected by filtration from tritium-containing water, dilute hydrochloric acid aqueous solution, and ultrapure water in a gas washing bottle.
  • the timing of collecting each sample was the time when the pH of the tritium-containing water dropped to 2.7 or lower.
  • a disposable filter DISMIC GS-25AS020AN manufactured by ADVANTEC
  • SS-02SZP disposable syringe
  • FIGS. 6 (a), (b), (c), and (d) The experimental results are shown in FIGS. 6 (a), (b), (c), and (d). All data plotted in each figure has been corrected to account for the amount of tritium that decreases with sampling. In addition, when 89 hours passed in this example, the ultrapure water in the gas cleaning bottle almost maintained the capacity obtained by subtracting the capacity collected as a sample from the initial capacity of 50 mL.
  • FIG. 6 (a) shows the change with time of tritium radioactivity concentration in tritium-containing water. The vertical axis represents the tritium radioactivity concentration of the sample water, and the horizontal axis represents the reaction time. From the result of FIG.
  • the tritium concentration of the tritium-containing water decreased by 858.67Bq / mL from the initial value of 4054.2Bq / mL to 3195.53Bq / mL after 89 hours. It was found that the tritium concentration corresponding to 21.2% decreased.
  • the pH adjustment of tritium-containing water was repeated as described above. However, every time the pH was adjusted to neutral by the addition of an aqueous sodium hydroxide solution, the tritium-containing water colored light brown. The sediment sludge accumulated.
  • FIG.6 (b) shows the change of the tritium radioactivity density
  • FIG. 6C shows the mass balance regarding the amount of tritium removed from the tritium-containing water, the total amount of tritium accumulated in the ultrapure water and dilute hydrochloric acid in the gas washing bottle, and the amount of tritium accumulated in the dilute hydrochloric acid. The change with time is shown. From the result of FIG.
  • FIG. 6C shows the change with time of the amount of tritium collected per unit time collected in the ultrapure water of the gas washing bottle with respect to the pH change of the tritium-containing water.
  • FIG. 6 (d) shows that the recovery rate is significantly improved when the pH of the tritium-containing water is 3 or less.
  • Example 5 In Example 5 described above, after the tritium-containing water was lowered to pH 3 or lower, the pH was readjusted to pH 7 again by the addition of an aqueous sodium hydroxide solution, whereby the reuse of the tritium absorbent was repeated. However, during the readjustment of the same pH in Example 5, sludge based on manganese elution was generated. In order to solve this problem, an aqueous lithium hydroxide solution was added in place of the aqueous sodium hydroxide solution in Example 5 as a reagent used for readjustment of the same pH. The reaction vessel and the electrode film were the same as in Example 5, and the experiment was performed in the same procedure.
  • the addition amount of the lithium hydroxide aqueous solution to the tritium-containing water is such that 0.1 g of 1M LiOH.H 2 O is added to about 150 mL of tritium-containing water, and the pH of the tritium-containing water is increased.
  • the amount of sludge generated per readjustment of pH could be reduced to 0.016 g, which is about 1/20 or less of the dry weight.
  • coloring of tritium-containing water due to elution of manganese ions could be suppressed.
  • the preferable effects as described above are that the addition of the lithium hydroxide aqueous solution to the tritium-containing water raises the pH of the tritium-containing water from acidic to neutral or more, and the unstable manganese oxide after the release of tritium. This is presumably based on the effect of lithium ions entering the crystal structure and stabilizing the crystal structure. A similar effect was confirmed when lithium chloride (LiCl) was added to tritium-containing water and the pH was readjusted with an aqueous sodium hydroxide solution.
  • LiCl lithium chloride
  • the lithium reagent to be added is water-soluble, the dissolution of manganese and the presence of anions in the lithium-containing complex, such as hydroxides and chlorides, compared to when lithium ions are not added, Generation of sludge can be suppressed.
  • An appropriate amount of lithium added to the tritium-containing water is preferably about 1 to 30 mg per 1 g of the manganese oxide powder having the spinel crystal structure.
  • the lithium concentration is preferably in the range of about 1 to 50 mg / L. This is because the addition of a large amount or high concentration of lithium ions exceeding the appropriate amount promotes dissolution of the manganese oxide.
  • the addition of the above lithium ion that achieves an appropriate amount and an appropriate concentration for the tritium-containing water of the present invention suppresses the generation of sludge when the present technology is put to practical use, and extends the life of the tritium absorbent. This is a useful finding.
  • the present invention is not limited to the method of recovering in water, and existing substances such as porous bodies having a high absorption capacity for normal hydrogen and water can be used in place of distilled water and ultrapure water in this embodiment.
  • Example 6> ⁇ Experiment to collect tritium in gel and electrolyte from electrode film collecting tritium> Using the experimental system shown in FIG. 7, an attempt was made to recover tritium in water containing a gel and an electrolyte from an electrode film that collected tritium.
  • the tritium recovery method of the present invention will be described with reference to FIG.
  • 10 g of lithium chloride powder (Wako Pure Chemical Industries, special grade reagent 127-01165, 99% or more) and reagent agar powder (special grade of Wako Pure Chemical Industries, Ltd.) are placed in a glass beaker. 018-15811) 1.7 g was added to distilled water (50 mL) and heated with a heater to dissolve the agar powder.
  • the aqueous solution of agar containing lithium ions obtained by heating is poured into a stainless steel (SUS304) mold (inner diameter 30 mm, height 20 mm, thickness 0.7 mm) and left at room temperature.
  • SUS304 stainless steel
  • the tritium-containing manganese oxide containing tritium was inserted into the conductive gel containing lithium ions by 15 mm of the electrode film in which tritium was collected in 10 minutes in the tritium collection experiment of Example 1 in 10 minutes. Placed in contact with.
  • the copper wire connected to the stainless steel mold part in the electrode film inserted into the gel in the stainless steel mold was connected to a constant voltage power source, and the electrode film was used as a positive electrode.
  • a copper wire connected to a carbon rod (diameter 5 mm, length 5 cm) was connected to a constant voltage power source to make the carbon rod a negative electrode.
  • the gel was sealed in a stainless steel can, and the stainless steel can was heated to liquefy the gel from which tritium was eluted, and a sample was collected.
  • DISVIC GS-25AS020AN made by ADVANTEC and disposable syringe SS-02SZP made by Terumo were used.
  • 1.0 mL was collected from the collected sample with a precision micropipette, and the radioactivity concentration of tritium in 1.0 mL of the sample was measured by the above-described method using a liquid scintillation counter.
  • the tritium concentration in 120 mL of distilled water added with conductivity by the addition of the electrolyte was measured to be 6.86 Bq / mL. This value was converted to the radioactivity of tritium eluted in 120 ml of distilled water to which the same conductivity was added, to obtain 823.2 Bq.
  • Tritium recovery experiment without using a gel containing lithium ions The tritium recovery experiment was performed using the above-mentioned gel by carrying out the tritium recovery experiment without using the gel containing lithium ions solidified in the stainless steel mold shown in FIG. Compared with the effect.
  • the electrode film containing tritium was directly connected to a constant voltage power source using a copper wire without going through the gel in FIG. The same electrode was used as the positive electrode, and a voltage of 4 to 5 V was applied between the negative electrode and the carbon rod of the negative electrode for 10 minutes as in the case of using gel.
  • a voltage of 4 to 5 V was applied between the negative electrode and the carbon rod of the negative electrode for 10 minutes as in the case of using gel.
  • 1.2% of the total amount of tritium contained in the electrode film was recovered in the distilled water. Therefore, it was found that by using a gel containing lithium ions according to the technique of the present invention, a recovery rate of tritium that is 30 times higher than that in the case of not using it can be obtained
  • the valence of manganese constituting the hydrogen ion-containing manganese oxide having the spinel type crystal structure which is the present tritium absorbent was analyzed by X-ray absorption spectroscopy (XANES).
  • XANES X-ray absorption spectroscopy
  • R-XAS LOOPER Rigaku X-ray absorption spectrometer
  • 1 g of the lithium ion-containing manganese oxide was suspended in 100 mL of dilute hydrochloric acid having a concentration of 0.5 M, and stirred for 24 hours with a stirrer coated with Teflon (registered trademark) and a magnetic stirrer.
  • a hydrogen ion-containing manganese oxide in which lithium ions were replaced with hydrogen ions was obtained.
  • Two types of samples were prepared by suspending the hydrogen ion-containing manganese oxide in 100 mL of distilled water adjusted to pH 3 and pH 6 and stirring for 2 days while maintaining each pH. For the pH adjustment, a concentration of 0.1M sodium hydroxide and 0.1M dilute hydrochloric acid were used. Further, a manganese metal powder, a manganese valence powder, a Mn 2 O 3 powder, a LiMn 2 O 4 powder, and a MnO 2 powder having a known valence of manganese were prepared. These were obtained from Wako Pure Chemical Industries as commercially available reagents, and were similarly measured as reference samples corresponding to manganese valences of 0, 3, 3, and 4, respectively.
  • FIG. 8A shows the measurement result of each sample.
  • the hydrogen ion-containing manganese oxide functioning as the present tritium absorbent
  • both the sample held in the pH 3 aqueous solution and the sample held in the pH 6 aqueous solution were measured as a reference.
  • the absorption edge shape was almost the same as that of manganese (MnO 2 ).
  • MnO 2 manganese
  • FIG.8 (b) the X-ray-diffraction (XRD) pattern of this hydrogen ion containing manganese oxide and the lithium ion containing manganese oxide before acid treatment was shown.
  • the manganese oxide When heated for about 24 hours to evaporate hydrogen ions from the spinel crystal structure into the atmosphere, the manganese oxide becomes lambda-type manganese dioxide, but the manganese dioxide is ion-exchangeable. Since the hydrogen ions are lost from the crystal, the hydrogen ion-containing manganese oxide of the present invention does not exhibit any absorbability for lithium ions or tritium ions, for example, Hideki Koyanaka and Hideo Miyatake, Extracting Tritium from Water. Using a Protonic Manganese Oxide Spinel ", Separation Science and Technology, 50, 14, 2142-2146, (2015), and H. Koyanaka, O. Matsubaya, Y. Koyanaka, and N.
  • the composition of the hydrogen ion-containing manganese oxide constituting the present tritium absorbent as (H + , e ⁇ ) Mn 2 O 4 in which charge neutrality is established.
  • hydrogen ions (H + ) are bonded to a special oxygen atom pair constituting the crystal by a weak covalent bond (which can be said to be a strong hydrogen bond) inside the crystal of spinel manganese oxide. It is pointed out in the following literature that hydrogen ion conductivity is exhibited according to the concentration gradient of hydrogen ions inside. H. Koyanaka, Y. Ueda, K.

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Abstract

La présente invention concerne la récupération de tritium à faible coût à partir d'un oxyde de manganèse contenant du tritium et la réutilisation dudit oxyde de manganèse. Le tritium est récupéré par évaporation à partir d'un oxyde de manganèse contenant du tritium et des ions lithium sont ajoutés pour stabiliser et réutiliser ledit oxyde de manganèse.
PCT/JP2016/070057 2015-07-06 2016-07-06 Procédé de récupération de tritium à partir d'un absorbeur de tritium et procédé de réutilisation comme absorbeur Ceased WO2017006973A1 (fr)

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CN106971766A (zh) * 2017-04-17 2017-07-21 中国工程物理研究院核物理与化学研究所 一种分子筛中氚水的回收装置
CN107705867A (zh) * 2017-11-09 2018-02-16 中国工程物理研究院核物理与化学研究所 一种含氚水的去氚化处理装置及方法
JP2019005702A (ja) * 2017-06-23 2019-01-17 株式会社フォワードサイエンスラボラトリ 三重水素吸収材及びその製造方法並びに軽水からの三重水素の分離方法

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JPS6223429A (ja) * 1985-07-24 1987-01-31 Ishikawajima Harima Heavy Ind Co Ltd 水素同位体の回収・貯蔵・供給装置
JPS62207702A (ja) * 1986-03-05 1987-09-12 Sumitomo Chem Co Ltd 水素同位体の回収方法
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106971766A (zh) * 2017-04-17 2017-07-21 中国工程物理研究院核物理与化学研究所 一种分子筛中氚水的回收装置
JP2019005702A (ja) * 2017-06-23 2019-01-17 株式会社フォワードサイエンスラボラトリ 三重水素吸収材及びその製造方法並びに軽水からの三重水素の分離方法
CN107705867A (zh) * 2017-11-09 2018-02-16 中国工程物理研究院核物理与化学研究所 一种含氚水的去氚化处理装置及方法
CN107705867B (zh) * 2017-11-09 2023-06-16 中国工程物理研究院核物理与化学研究所 一种含氚水的去氚化处理装置及方法

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