JP7455714B2 - Radionuclide processing system and radionuclide processing method - Google Patents

Description

The present disclosure relates to a radionuclide processing system and a radionuclide processing method related to radioactive waste processing technology, technology for producing rare elements from elements abundantly present in nature, and the like.

When reprocessing spent nuclear fuel, the spent nuclear fuel is first dissolved in a nitric acid (HNO ₃ ) solution to separate uranium (U) and plutonium (Pu). The solution after separation (acidic waste liquid) contains cesium-137 (Cs-137), strontium-90 (Sr-90), and the like.

Acidic waste liquid is disposed of, for example, underground, but how to dispose of it is an issue to be considered.

Patent Documents 1 and 2 disclose techniques for converting substances such as Cs into other nuclides using simple and small-scale equipment. In Patent Documents 1 and 2, deuterium and a substance to be subjected to nuclide conversion are reacted.

In Patent Document 2, a heavy aqueous solution containing an electrolyte is electrolyzed to generate deuterium gas, and the generated deuterium gas is transmitted through a structure equipped with a substance to be subjected to nuclide conversion, thereby causing a nuclide conversion reaction. I'm making it happen.

Patent No. 4346838 Patent No. 6486600

It takes tens to hundreds of hours to convert elements using the seed conversion device described in Patent Document 2. If the conversion reaction does not occur after the end of the experiment, there will be a large loss in time and cost (material costs such as deuterium gas and electricity). Therefore, it is desirable to be able to confirm the progress of the reaction between deuterium and the substance undergoing nuclide transmutation during the experiment.

However, it is difficult to confirm the progress of the reaction during experiments. In Patent Document 2, the amount of reaction products is confirmed using ICP-MS, but this method is not suitable for confirmation during experiments because it is necessary to destroy the structure.

When using radioactive materials as materials to undergo nuclide transmutation, care must be taken when handling them from the standpoint of safety. Therefore, it is preferable that the progress of the reaction can be determined in a manner that does not allow workers to come into contact with radioactive substances.

The present disclosure has been made in view of these circumstances, and provides a radionuclide processing system and a radionuclide processing method that can non-destructively and non-contact determine the degree of progress of the reaction between deuterium and radioactive materials. The purpose is to

In order to solve the above problems, the nuclide conversion system and nuclide conversion method of the present disclosure employ the following means.

The present disclosure provides a structure through which deuterium can permeate, a storage part and a deuterium low concentration part separated by the structure and each forming a closed space, and a deuterium low concentration part housed in the storage part on the storage part side of the structure. a reaction device having an electrode arranged to face a surface and a power source connected to the electrode; an electrolyte solution supply section connected to the storage section and supplying a heavy aqueous solution containing an electrolyte to the storage section; and the storage section a circulation unit connected to the storage unit, which extracts the solution from the storage unit and returns the extracted solution to the storage unit; a first detector that measures the radiation dose of the structure; and a first detector that measures the radiation dose of the solution extracted from the storage unit. a second detector that measures the amount of radiation; and a determination unit that determines that the reaction has ended when the second radiation dose obtained by the measurement of the second detector increases to a second threshold value or more, and the structure The body has a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance on the side of the storage part, and the circulation part has a solution storage part that stores a solution extracted from the storage part. Provide processing systems.

The present disclosure provides a structure through which deuterium can permeate, a storage part and a deuterium low concentration part separated by the structure and each forming a closed space, and a deuterium low concentration part housed in the storage part on the storage part side of the structure. a reaction device having an electrode arranged to face a surface and a power source connected to the electrode; an electrolyte solution supply section connected to the storage section and supplying a heavy aqueous solution containing an electrolyte to the storage section; and the storage section a circulation unit that is connected to the storage unit and extracts the solution from the storage unit and returns the extracted solution to the storage unit; a first detector that is housed in the low deuterium concentration unit and measures the radiation dose of the structure; , a second detector that measures the radiation dose of the solution extracted from the storage section; and a determination that the reaction is complete when the second radiation dose obtained by measurement by the second detector increases to a second threshold value or more. and a determination unit for determining the structure , the structure providing a radionuclide processing system having a surface layer including a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance on the storage unit side.

The present disclosure provides a structure through which deuterium can permeate, a storage part and a deuterium low concentration part separated by the structure and each forming a closed space, and a deuterium low concentration part housed in the storage part on the storage part side of the structure. A radionuclide processing method using a reaction device having an electrode disposed opposite to a surface and a power source connected to the electrode, the surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance being placed in the storage section. The structure is placed facing toward the side, a heavy aqueous solution containing an electrolyte is supplied to the reservoir, and a voltage is applied to the electrode immersed in the heavy aqueous solution containing the electrolyte to connect the electrode and the structure. A voltage difference is generated between the electrodes and the structure to generate the deuterium from the heavy aqueous solution containing the electrolyte in the space between the electrode and the structure. After the deuterium is permeated toward the deuterium low concentration part side, the permeation of the deuterium is stopped, and the solution is extracted from the storage part to empty the inside of the storage part, a first detector detects the structure. When the first radiation dose obtained by the measurement by the first detector falls below the first threshold value, the reaction is terminated, and the first radiation dose is equal to or less than the first threshold value. , the extracted solution is returned to the reservoir, the permeation of deuterium is restarted , a second radiation dose of the electrolyte solution extracted from the reservoir is measured by a second detector, and the second radiation dose of the electrolyte solution extracted from the reservoir is measured by a second detector, Provided is a radionuclide processing method that determines that the reaction has ended when the second radiation dose increases to a second threshold value or more .

The present disclosure provides a structure through which deuterium can permeate, a storage part and a deuterium low concentration part separated by the structure and each forming a closed space, and a deuterium low concentration part housed in the storage part on the storage part side of the structure. A radionuclide processing method using a reaction device having an electrode disposed opposite to a surface and a power source connected to the electrode, the surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance being placed in the storage section. The structure is placed facing toward the side, a first detector for measuring the radiation dose of the structure is placed in the low deuterium concentration part, a heavy aqueous solution containing the electrolyte is supplied to the storage part, A voltage is applied to the electrode immersed in a heavy water solution containing an electrolyte to create a voltage difference between the electrode and the structure, and the heavy water solution containing the electrolyte is applied in the space between the electrode and the structure. The deuterium is generated from an aqueous solution, the deuterium is permeated from the storage part side of the structure toward the deuterium low concentration part side according to a concentration gradient, and while the deuterium is permeated, the first detection is performed. The radiation dose of the structure is measured by a device, and when the first radiation dose obtained by the measurement by the first detector decreases to a first threshold value or less, the reaction is terminated and the electrolyte is extracted from the storage portion. Provided is a radionuclide processing method in which a second radiation dose of a solution is measured by a second detector, and when the second radiation dose rises to a second threshold value or more, it is determined that the reaction has ended .

By monitoring the decline in the radiation dose in the structure, it is possible to determine the progress of the reaction between deuterium and radioactive materials in a non-destructive and non-contact manner.

FIG. 1 is a schematic diagram of a nuclide conversion system according to a first embodiment. FIG. 2 is a schematic cross-sectional view of an example of a structure. It is a schematic diagram which illustrates arrangement|positioning of a shielding material. FIG. 3 is a flow diagram showing the procedure of the nuclide conversion method according to the first embodiment. FIG. 3 is an energy spectrum diagram obtained by measurement with the first detector. FIG. 2 is a schematic diagram of a nuclide conversion system according to a second embodiment. It is a flowchart which shows the procedure of the nuclide conversion method based on 2nd Embodiment. It is a schematic diagram showing an example of arrangement of a 2nd detector. It is a schematic diagram of the nuclide conversion system concerning a 3rd embodiment. It is a flowchart which shows the procedure of the nuclide conversion method based on 3rd Embodiment. FIG. 3 is an energy spectrum diagram obtained by measurement with a first detector and a second detector. FIG. 3 is an energy spectrum diagram obtained by measurement with a first detector and a second detector. FIG. 3 is a diagram showing the γ-ray intensity (normalized) before and after the reaction. It is a flowchart which shows the procedure of the nuclide conversion method based on 4th Embodiment. FIG. 3 is a diagram showing the relationship between the amount of radioactive material eluted into an electrolyte solution and conversion reaction efficiency.

A radioactive material processing system (radioactive nuclide processing system) according to the present disclosure includes a reaction device, a high concentration device, and a low concentration device. The reactor includes a structure having a surface layer. The surface layer includes a radioactive substance and a hydrogen storage metal or hydrogen storage alloy.

The radioactive substance processing method (radioactive nuclide processing method ) according to the present disclosure allows deuterium to pass through the structure from the surface layer side, and processes the radioactive material contained in the surface layer to become a non-radioactive nuclide.

The present disclosure is characterized in that the radiation dose of the structure is monitored, the degree of progress of the reaction is determined based on the monitored value, and the timing of completion of the reaction is determined.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a radioactive material processing system (radioactive nuclide processing system ) and a radioactive material processing method (radioactive nuclide processing method ) according to the present disclosure will be described below with reference to the drawings.

[First embodiment]
FIG. 1 is a schematic diagram of a nuclide conversion system according to a first embodiment. The nuclide conversion system 1 includes a reaction device 10, a high concentration device (electrolyte solution supply section) 60, a low concentration device 17, a circulation section 30, and a first detector 100.

The nuclide conversion system 1 may include a discharge section 40 and an electrodeposition liquid supply section 50. The nuclide conversion system 1 may include a cleaning liquid supply section 90. The nuclide conversion system 1 may include a determination unit 110. The nuclide conversion system 1 may include a control unit 111.

(Reactor)
The reaction device 10 includes a storage section 11, a low deuterium concentration section 12, a structure 13, an electrode 14, and a power source 15.

The storage section 11 and the low deuterium concentration section 12 are separated by a structure 13, and each constitute a closed space. The storage section 11 and the low deuterium concentration section 12 are configured to allow γ rays derived from radioactive substances contained in the surface layer, which will be described later, to pass therethrough. In order to allow gamma rays to pass through, it is better to use a material with the lowest possible density for the storage section 11 (at least the gamma ray detection section). For example, it is more desirable to use PTFE (2.2 g/cm ³ ) or aluminum (2.7 g/cm ³ ) than lead (11.3 g/cm ³ ) or iron (7.87 g/cm ³ ). The storage section 11 can store liquid in a closed space.

The structure 13 is permeable to deuterium. FIG. 2 illustrates a schematic cross-sectional view of the structure 13. The structure 13 has a structure in which a substrate 21, an intermediate layer 24, and a surface layer 25 are laminated in this order. The surface layer 25 is formed on the outermost surface of the structure 13 on one side (the surface on the opposite side to the substrate 21). In the reaction apparatus 10, the structure 13 is arranged such that the substrate 21 faces the deuterium low concentration region 12 side and the surface layer 25 faces the storage region 11 side.

Substrate 21 includes a bulk hydrogen storage metal or hydrogen storage alloy. Examples of hydrogen storage metals include palladium (Pd) and nickel (Ni). Hydrogen storage alloys include palladium alloys and nickel alloys. The thickness of the substrate 21 is preferably thinner in terms of cost, but considering mechanical strength, the thickness is, for example, 0.01 mm to 1 mm.

The intermediate layer 24 is a laminate in which first layers 22 and second layers 23 are alternately stacked. The first layer 22 and the second layer 23 may be laminated on the substrate 21 by sputtering or electrodeposition. In the sputtering method, film formation is repeatedly performed to form a layer of a predetermined thickness.

The first layer 22 includes a hydrogen storage metal or a hydrogen storage alloy. The hydrogen storage metal or hydrogen storage alloy contained in the first layer 22 is preferably the same type as the hydrogen storage metal or hydrogen storage alloy contained in the substrate 21.

The second layer 23 includes a low work function material that has a relatively lower work function than the metal contained in the substrate 21 . The low work function material is a material that easily emits electrons.The work function of the low work function material is less than 3 eV. Examples of low work function substances include calcium oxide (CaO, work function 1.2 eV), yttrium oxide (Y ₂ O ₃ , work function 2.2 eV), and strontium titanate (SrTiO ₃ , work function 4.2 eV). be. From the viewpoint of conversion efficiency, calcium oxide is preferably selected as the low work function substance.

The surface layer 25 includes a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance.

Examples of the hydrogen storage metal include palladium (Pd) and nickel (Ni). Examples of hydrogen storage alloys include palladium alloys and nickel alloys.

Radioactive substances have nuclides that emit gamma rays or neutron rays. Examples of nuclides that emit gamma rays include Cs-137, Cs-134, Sb-125, and Co-60. The nuclide that emits neutron beams is, for example, Pu-241.

Electrode 14 is housed within reservoir 11 . The electrode 14 is arranged to face and be spaced apart from the surface of the structure 13 on the storage section 11 side. The electrode 14 is a plate-shaped member made of platinum (Pt) or the like. The electrode 14 may have a mesh structure. The physically perforated structure allows radiation emitted from the structure 13 to easily pass through.

Power source 15 is placed outside reactor 10 . A power source 15 is connected to the electrode 14 .

A check valve 16 is installed in the storage section 11 . The check valve 16 is provided in a flow path that connects the storage section 11 and the external atmosphere. The check valve 16 closes when the atmospheric pressure of the external atmosphere is greater than the atmospheric pressure of the gas stored in the storage section 11 . The check valve 16 opens when the pressure of the gas stored in the storage section 11 is greater than the pressure of the external atmosphere, and exhausts the gas in the storage section 11 to the outside atmosphere.

The reaction device 10 may include a heater 20. The heater 20 is installed near the structure 13 within the low deuterium concentration section 12 . The heater 20 heats the low deuterium concentration portion 12 side of the structure 13 to a predetermined temperature.

(Electrolyte solution supply section)
The electrolyte solution supply section 60 is configured to supply deuterium to the storage section 11 so that the concentration of deuterium in the storage section 11 is relatively high compared to the low deuterium concentration section 12 .

The electrolyte solution supply section 60 includes an electrolyte solution tank 61, an electrolyte solution supply pipe 62, a heavy water supply section 65, and an inert gas supply section 71.

The heavy water supply section 65 includes an inert gas supply pipe 66, a dehumidifier 67, a dry inert gas supply pipe 68, a heavy water tank 69, and a heavy water supply pipe 70.

The inert gas supply pipe 66 forms a flow path that connects a gas source (not shown) to the dehumidifier 67. The dry inert gas supply pipe 68 forms a flow path that connects the dehumidifier 67 and the heavy water tank 69.

The heavy water tank 69 constitutes a closed space in which heavy water (D ₂ O) is stored. The heavy water supply pipe 70 forms a flow path that connects the heavy water tank 69 and the electrolyte solution tank 61.

Inert gas supplied from a gas source (not shown) is supplied to the heavy water tank 69 via an inert gas supply pipe 66, a dehumidifier 67, and a dry inert gas supply pipe 68. As a result, the inside of the heavy water tank 69 is pressurized, and heavy water is supplied to the electrolyte solution tank 61 through the heavy water supply piping 70. A valve V5 installed in the heavy water supply pipe 70 controls the amount of heavy water supplied.

The inert gas supply section 71 includes an inert gas supply pipe 72, a dehumidifier 73, and a dry inert gas supply pipe 74.

The inert gas supply pipe 72 forms a flow path that connects a gas source (not shown) to the dehumidifier 73. The dry inert gas supply pipe 74 forms a flow path that connects the dehumidifier 73 and the electrolyte solution tank 61.

The inert gas supply section 71 supplies nitrogen gas supplied from a gas source (not shown) to the electrolyte solution tank 61. By supplying nitrogen gas from the dry inert gas supply piping 74 to the electrolyte solution tank 61, the inside of the electrolyte solution tank 61 is pressurized.

The electrolyte solution tank 61 constitutes a closed space in which an electrolyte solution is stored. An electrolyte salt 63 is placed at the bottom of the electrolyte solution tank 61. The type of electrolyte salt 63 is not particularly limited, but it is preferably a salt of the same element as the radioactive substance described below. For example, cesium nitrate _CsNO3 , cesium hydroxide _CsOH , antimony sulfide _Sb2S3 , cobalt nitrate Co( _NO3 ) ₂ , and plutonium nitrate Pu( _NO3 ) ₄ . The solvent for the electrolyte solution is heavy water. When the electrolyte salt 63 is immersed in heavy water, it is dissolved, and an electrolyte solution (a heavy water solution containing an electrolyte) is generated.

A heater 64 is arranged around the outside of the electrolyte solution tank 61. The heater 64 controls the electrolyte solution in the electrolyte solution tank 61 to a predetermined temperature. By controlling the temperature of the electrolyte solution and the amount of heavy water supplied from the heavy water supply section 65, the electrolyte concentration in the electrolyte solution is adjusted. In this embodiment, the electrolyte concentration is between 0.001 mol/l and saturation concentration.

The electrolyte solution supply pipe 62 forms a flow path that connects the electrolyte solution tank 61 and the storage section 11 . By pressurizing the inside of the electrolyte solution tank 61, the electrolyte solution is supplied to the storage section 11 through the electrolyte solution supply piping 62. A valve V4 installed in the electrolyte solution supply pipe 62 controls the amount of electrolyte solution supplied.

The electrolyte solution supply section 60 may include a heavy water replenishment section 80. The heavy water replenishment section 80 is connected to the storage section 11. The heavy water replenishment unit 80 includes an inert gas supply pipe 81, a dehumidifier 82, a dry inert gas supply pipe 83, a heavy water tank 84, and a heavy water replenishment pipe 85.

The inert gas supply pipe 81 forms a flow path that connects a gas source (not shown) to the dehumidifier 82 . The dry inert gas supply pipe 83 forms a flow path that connects the dehumidifier 82 and the heavy water tank 84. The heavy water replenishment pipe 85 forms a flow path that connects the heavy water tank 84 and the storage section 11 . The heavy water tank 84 constitutes a closed space in which heavy water (D ₂ O) is stored.

Nitrogen gas supplied from a gas source (not shown) is supplied to the heavy water tank 84 via an inert gas supply pipe 81, a dehumidifier 82, and a dry inert gas supply pipe 83, and the inside of the heavy water tank 84 is Pressurized. By pressurizing the inside of the heavy water tank 84, heavy water is fed to the storage section 11 through the heavy water replenishment piping 85. A valve V6 installed in the heavy water replenishment pipe 85 controls the amount of heavy water supplied.

(Low concentration device)
The low concentration device 17 is configured to make the deuterium concentration in the low deuterium concentration section 12 relatively low with respect to the storage section 11 . In this embodiment, the concentration lowering device 17 has an exhaust means 18 and an exhaust route 19.

The exhaust means 18 is connected to the low deuterium concentration section 12 via an exhaust path 19. The exhaust means 18 exhausts the gas inside the low deuterium concentration section 12 to reduce the pressure inside the low deuterium concentration section 12 . FIG. 1 shows a case where a vacuum pump is used as the exhaust means 18. Vacuum pumps include, for example, turbomolecular pumps and dry pumps.

Note that the concentration lowering device 17 may be an inert gas supply section. The inert gas supply section includes a gas source, an inert gas supply pipe, and an exhaust pipe. The inert gas supply section supplies an inert gas (eg, N ₂ , Ar) to the low deuterium concentration section 12 . In order to maintain the pressure within the low deuterium concentration section 12 at a predetermined pressure, the gas within the low deuterium concentration section 12 is exhausted through the exhaust pipe.

(1st detector)
The first detector 100 is a device capable of detecting radiation emitted from the structure 13 (radioactive material contained in the surface layer 25). When the radioactive substance contained in the surface layer 25 has a nuclide that emits gamma rays, a gamma ray detector such as a Ge semiconductor detector is used as the first detector 100. Ge semiconductor detectors have high spectral resolution and can focus on desired radioactive substances. When the radioactive substance contained in the surface layer 25 has a nuclide that emits neutron beams, a neutron detector is used as the first detector 100.

The first detector 100 is arranged to be able to detect radiation emitted from the structure 13. The relative positions of the first detector 100 and the reaction device 10 (measurement target) are fixed.

The first detector 100 is preferably placed near the surface layer 25 of the structure 13, for example, close to the reservoir 11. The closer the distance from the radiation source (radioactive material), the greater the amount of radiation that can be detected, increasing detection accuracy.

In FIG. 1, the first detector 100 is placed next to the reservoir 11, but the arrangement of the first detector 100 is not limited to this.

For example, the first detector 100 may be arranged to directly face the surface of the structure 13 on the surface layer 25 side. In FIG. 1, the position directly facing the surface on the surface layer 25 side is the upper part of the storage section 11 (the side where the electrode 14 is arranged).

Radioactive materials are dispersed throughout the surface layer. When the first detector 100 is placed on the side of the plate-shaped structure 13 (on the left side in FIG. 1), the first detector 100 is placed on the side near the first detector 100 and on the opposite side. There is a difference in distance from As the distance from the source increases, the amount of radiation that can be detected decreases. Therefore, it is preferable that the distance between the radiation source and the first detector 100 is constant. By fixing the first detector 100 directly facing the surface of the structure 13 on the surface layer 25 side, the distance between each of the radioactive substances dispersed on the surface layer of the structure 13 and the first detector 100 can be varied. The width can be made smaller.

FIG. 3 shows an image of the first detector 100 directly facing the structure 13. In FIG. 3, illustrations of the storage section 11 and the low deuterium concentration section 12 are omitted. The structure 13 has a surface layer (not shown) on the side facing the first detector 100. The reaction device 10 may be surrounded by a shielding material 102.

The shielding material 102 is made of a material that can shield radiation emitted from the structure 13. When the radioactive substance contained in the surface layer has a nuclide that emits gamma rays, a lead block with a predetermined thickness can be used as the shielding material 102, for example. When the radioactive substance contained in the surface layer has a nuclide that emits neutron beams, a water wall or the like can be used as the shielding material 102, for example.

By surrounding the reaction device 10 with the shielding material 102, the influence of disturbance factors can be reduced during radiation measurement. When the influence of disturbance factors is small, noise is reduced and background can be kept low, making it possible to obtain changes in radiation dose more accurately.

In FIG. 3, the reaction apparatus 10 is surrounded on three sides by shielding materials 102, but the arrangement of the shielding materials 102 is not limited to this. The shielding material 102 may be arranged so that radiation emitted from other structures having radiation sources, such as the electrolyte solution tank 61 and/or the solution reservoir 101, is blocked.

The first detector 100 may be installed at multiple locations. This improves detection accuracy.

(circulation department)
The circulation section 30 can extract the solution from within the storage section 11 and return the extracted solution into the storage section 11 . The circulation section 30 includes an extraction piping 31, a solution storage section 101, a heat exchanger 32, a filter 33, a pump 34, a resupply piping 35, and a valve V1 installed in the resupply piping 35.

One end of the extraction pipe 31 is connected to the reservoir 11 so that the solution can be extracted from the reservoir 11 . The extraction piping 31 is preferably configured to be able to extract substantially the entire amount of the solution in the storage section 11 . For example, in FIG. 1, the extraction pipe 31 is passed through the middle part of the wall surface of the storage section 11, and one end is arranged at the bottom of the storage section 11. The extraction piping 31 may be connected to the lower wall surface or the bottom surface of the storage section 11 without being limited thereto.

The other end of the extraction pipe 31 is connected to the solution storage section 101. The solution storage section 101 has a capacity capable of receiving and storing the entire amount of the solution stored in the storage section 11 . The solution reservoir 101 includes a conduit (not shown) that guides the received liquid to the heat exchanger 32 without storing it.

The solution storage section 101, the heat exchanger 32, the filter 33, and the pump 34 are connected in order through piping. The solution extracted from the storage section 11 enters the heat exchanger 32 via the solution storage section 101.

The heat exchanger 32 cools the solution extracted from the storage section 11. The filter 33 filters the solution extracted from the reservoir 11 to remove impurities. The pump 34 returns the solution filtered by the filter 33 to the storage section 11 via the resupply pipe 35 . The resupply pipe 35 is preferably placed between the structure 13 and the electrode 14. Thereby, the surface of the structure 13 can be efficiently cooled.

(Discharge section)
The discharge part 40 is connected to the upstream side of the valve V1 of the resupply pipe 35. The discharge section 40 includes a discharge pipe 41 and a valve V2. The discharge section 40 discharges the solution extracted from the storage section 11 by the circulation section 30 to the outside of the system. Note that the discharge section 40 may be directly connected to the storage section 11.

(Electrodeposition liquid supply section)
The electrodeposition liquid supply section 50 is connected to the storage section 11 . In FIG. 1, the electrodeposition liquid supply section 50 is connected to the resupply pipe 35 of the circulation section 30, but the present invention is not limited thereto, and the electrodeposition liquid supply section 50 may be directly connected to the storage section 11 of the reaction apparatus 10. The electrodeposition liquid supply section 50 supplies an electrodeposition liquid containing a radioactive substance and a hydrogen storage metal or a hydrogen storage alloy to the storage section.

The electrodeposition liquid supply unit 50 includes an electrodeposition liquid tank 51, an electrodeposition liquid supply pipe 52, an inert gas supply pipe 53, a dehumidifier 54, and a dry inert gas supply pipe 55.

The inert gas supply pipe 53 forms a flow path that connects a gas source (not shown) and the dehumidifier 54. The inert gas supply pipe 53 supplies the dehumidifier 54 with a predetermined flow rate of the inert gas (CE (Cold Evaporator)_N ₂ in FIG. 1) supplied from the gas source. Ar gas or the like can also be used as the inert gas.

The dehumidifier 54 includes a filter with a dehumidifying function, such as silica gel. The dehumidifier 54 removes impurities from the inert gas supplied from the inert gas supply pipe 53 and dries the inert gas.

The dry inert gas supply pipe 55 forms a flow path that connects the dehumidifier 54 and the electrodeposition liquid tank 51. The dry inert gas supply pipe 55 supplies a predetermined flow rate of the inert gas dried by the dehumidifier 54 to the electrodeposition liquid tank 51 .

The electrodeposition liquid tank 51 constitutes a closed space in which the electrodeposition liquid is stored. The electrodeposition solution contains a salt of a hydrogen storage metal (for example, a Pd salt) or a salt of a hydrogen storage alloy. The electrodeposition solution further includes a radioactive substance to be included in the surface layer 25. A salt of the radioactive substance may be added to the electrodeposition solution.

A heater 56 is arranged around the outside of the electrodeposition liquid tank 51. The heater 56 controls the electrodeposition liquid in the electrodeposition liquid tank 51 to a predetermined temperature.

In the configuration of FIG. 1, the electrodeposition liquid supply pipe 52 forms a flow path that connects the electrodeposition liquid tank 51 and the resupply pipe 35.

The inside of the electrodeposition liquid tank 51 is pressurized by supplying the inert gas from the dry inert gas supply piping 55 to the electrodeposition liquid tank 51 . Thereby, the electrodeposition liquid is supplied to the storage section 11 of the reaction device 10 through the electrodeposition liquid supply pipe 52. A valve V3 installed in the electrodeposition liquid supply pipe 52 controls the supply amount of the electrodeposition liquid.

(Cleaning liquid supply section)
The cleaning liquid supply section 90 is connected to the resupply pipe 35. The cleaning liquid supply section 90 may be directly connected to the storage section 11 of the reaction device 10.

The cleaning liquid supply section 90 includes an inert gas supply pipe 91, a dehumidifier 92, a dry inert gas supply pipe 93, a cleaning liquid tank 94, and a cleaning liquid supply pipe 95. The dry inert gas supply pipe 93 forms a flow path that connects the dehumidifier 92 and the cleaning liquid tank 94. The cleaning liquid supply pipe 95 forms a flow path that connects the cleaning liquid tank 94 and the storage section 11 . A valve V7 is installed in the cleaning liquid supply pipe 95.

The cleaning liquid tank 94 constitutes a closed space in which cleaning liquid is stored. Considering contamination during the nuclide transmutation reaction, heavy water is optimal as the cleaning liquid, but other liquids such as light water can also be used.

(Judgment Department)
The determination unit 110 is electrically connected to the first detector 100. The determining unit 110 determines that the reaction has ended when the radiation dose measured by the first detector 100 has decreased to a first threshold value or less.

The first threshold value can be set, for example, to a value at which the amount of radiation captured per hour is 50% of the initial value, or to 1000 counts or less per hour. Preferably, the first threshold value is a background level radiation dose. The initial value is the radiation dose of the structure 13 placed in the reservoir 11 obtained by measurement by the first detector 100 before supplying the electrolyte solution.

(control unit)
The control unit 111 is electrically connected to the determination unit 110, the electrolyte solution supply unit 60, the concentration lowering device 17, the circulation unit 30, the discharge unit 40, the electrodeposition liquid supply unit 50, the heavy water replenishment unit 80, and the cleaning liquid supply unit 90. has been done. The control unit 111 can control the supply, discharge, and exhaust of the solution from each part. When the determination unit 110 determines that the reaction has ended, the control unit 111 stops the supply of the electrolyte solution and the exhaust from the concentration lowering device 17.

The control unit 111 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a computer-readable storage medium, and the like. A series of processes for realizing various functions is stored in a storage medium, etc. in the form of a program, for example, and the CPU reads this program into a RAM, etc., and executes information processing and arithmetic processing. By doing so, various functions are realized. Note that the program may be pre-installed in a ROM or other storage medium, provided as being stored in a computer-readable storage medium, or distributed via wired or wireless communication means. etc. may also be applied. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like.

Next, the nuclide conversion method according to this embodiment will be described with reference to FIG. 4. The nuclide conversion method according to the present embodiment includes a step of forming a surface layer <S1-3>, a step of reacting <S4-5>, a step of determining the end of the reaction <S6-7>, and a step of recovering radioactive substances <S8>. >Including.

When using the structure 13 on which the surface layer 25 has been formed in advance, the steps of forming the surface layer (S1 to S3) are omitted.

In this embodiment, it is assumed that the surface layer 25 is not formed on the structure 13 at the time the structure 13 is installed in the reaction apparatus 10. The present invention is not limited to this, and the structure 13 on which the surface layer 25 is formed may be installed. In that case, the steps of forming the surface layer (S1 to S3) are omitted. The structure 13 is arranged so that the surface layer 25 faces the storage section 11 side.

(preparation)
The structure 13 is arranged in the reaction apparatus 10 so that the storage section 11 and the low deuterium concentration section 12 are airtightly maintained closed spaces. The electrode 14 is arranged to face the structure 13 with a space therebetween.

(Formation of surface layer)
<S1> Supply of electrodeposition liquid The electrodeposition liquid contains a hydrogen storage metal or a hydrogen storage alloy to be included in the surface layer 25 and a radioactive substance.

The heater 56 of the electrodeposition liquid supply unit 50 maintains the electrodeposition liquid in the electrodeposition liquid tank 51 at a predetermined temperature (specifically, 25 to 75° C.).

Valve V2 of the discharge section 40 is closed. The pump 34 of the circulation section 30 operates, and the valve V1 installed in the resupply pipe 35 is opened.

The valve V13 of the inert gas supply pipe 53, the valve V23 of the dry inert gas supply pipe 55, and the valve V3 of the electrodeposition liquid supply pipe 52 are opened. As a result, the electrodeposition liquid in the electrodeposition liquid tank 51 is supplied to the storage section 11 through the electrodeposition liquid supply pipe 52 and the resupply pipe 35.

When the electrode 14 is immersed in the electrodeposition liquid and a predetermined amount of the electrodeposition liquid is stored in the reservoir 11, the valves V1, V3, V13, and V23 are closed and the pump 34 is stopped.

<S2> Electrodeposition The power supply 15 applies a positive voltage to the electrode 14. The hydrogen storage metal or hydrogen storage alloy in the electrodeposition liquid is electrodeposited on the surface of the structure 13 to form a surface layer (electrodeposition layer). During the process of forming the surface layer, radioactive substances contained in the electrodeposition solution are taken in (embedded) into the surface layer.

<S3> Recovery of electrodeposition liquid After the surface layer formation is completed, valve V2 is opened and pump 34 is started. The electrodeposited liquid in the storage section 11 is discharged to the outside of the system through the extraction pipe 31 and the discharge section 40. The discharged electrodeposition liquid is collected. The collected electrodeposition liquid may be returned to the electrodeposition liquid tank 51.

After the electrodeposition liquid is discharged, a cleaning step may be performed to wash away the electrodeposition liquid remaining in the reservoir 11 or the like.

In the cleaning process, valve V2 is closed and valve V1 is opened. Next, valve V17 of inert gas supply piping 91 of cleaning liquid supply section 90, valve V27 of dry inert gas supply piping 93, and valve V7 of cleaning liquid supply piping 95 are opened. The cleaning liquid in the cleaning liquid tank 94 is supplied to the storage section 11 through the cleaning liquid supply piping 95 and the resupply piping 35. The cleaning liquid circulates through the storage section 11 and the circulation section 30.

After a predetermined period of time has elapsed, valves V1, V7, V17, and V27 close, and valve V2 opens. As a result, the cleaning liquid is discharged to the outside of the system through the discharge section 40.

(reaction)
<S4> Supply of electrolyte solution When the discharge of the electrodeposition solution or the cleaning solution (if a cleaning process is performed) is completed, the valve V2 is closed and the valve V1 is opened.

Valve V14 of inert gas supply piping 53, valve V24 of dry inert gas supply piping 55, and valve V4 of electrolyte solution supply piping 62 in electrolyte solution supply section 60 are opened. The electrolyte solution in the electrolyte solution tank 61 is supplied to the storage section 11 through an electrolyte solution supply pipe 62.

The electrolyte solution is a heavy water solution containing electrolytes. Once the electrolyte solution has been delivered until the electrode 14 is immersed, valves V14, V24, V4 are closed.

The electrolyte solution in the storage section 11 is circulated using the circulation section 30. During this circulation process, the electrolyte solution extracted from the storage section 11 is not stored in the solution storage section 101, but is guided from the conduit to the heat exchanger 32. The electrolyte solution introduced into the heat exchanger 32 is adjusted to a predetermined temperature. In this embodiment, the temperature of the electrolyte solution in the reservoir 11 is maintained at about 20 to 40°C.

The circulation by the circulation unit 30 is continued in <S5> deuterium permeation, which will be described later. By circulating the cooled electrolyte solution, it is possible to suppress an increase in temperature of the surface layer 25 due to heat generated due to the reaction.

<S5> Deuterium permeation The low concentration device 17 operates. In the nuclide conversion system 1 of FIG. 1, the vacuum pump (exhaust means 18) is started, and the pressure inside the deuterium low concentration section 12 is reduced. It is preferable that the pressure within the deuterium low concentration section 12 is <0.1 Pa.

When an inert gas supply device is installed as the low concentration device 17, the inert gas is supplied to the deuterium low concentration section 12 and a predetermined pressure is maintained.

Here, the deuterium low concentration portion 12 side of the structure 13 is heated to about 70° C. by the heater 20 .

A power source 15 applies a voltage to the electrode 14 immersed in the electrolyte solution, generating a voltage difference between the electrode (anode) 14 and the structure (negative electrode) 13 . The voltage difference is at least 2V or more. By applying the voltage, heavy water is electrolyzed on the surface of the structure 13 on the storage portion 11 side, and deuterium (D ₂ ) is generated. In this embodiment, since a heavy water solution containing electrolyte is used, electrolysis is promoted. If the voltage difference is less than 2V, the electrolysis reaction will not proceed sufficiently.

When deuterium is generated on the surface of the storage section 11 side, a concentration gradient of deuterium is generated between the surface of the structure 13 on the storage section 11 side and the surface of the structure 13 on the low deuterium concentration section 12 side. When the low deuterium concentration section 12 is under reduced pressure (or filled with inert gas), the concentration gradient between the surface of the structure 13 on the storage section 11 side and the surface on the low deuterium concentration section 12 side increases. . Due to the concentration gradient, deuterium generated in the storage section 11 flows toward the low deuterium concentration section 12 and permeates through the structure 13 .

Furthermore, by heating the deuterium low concentration part 12 side of the structure 13 with the heater 20, a temperature gradient is generated between the surface of the structure 13 on the storage part 11 side and the surface on the deuterium low concentration part 12 side. . The temperature gradient facilitates deuterium permeation.

When deuterium permeates, radioactive substances contained in the surface layer 25 are converted into non-radioactive nuclides. For example, conversion reactions such as Cs-137→Eu-153 and Cs-134→La-138 occur. When the electrolyte salt 63 is a salt of the same element as the radioactive substance contained in the surface layer 25, the element derived from the electrolyte salt 63 is also subjected to nuclide conversion.

Due to electrolysis and nuclide transmutation reactions, the amount of heavy water (electrolyte solution) and electrolyte (if a salt of a radioactive substance is used) in the reservoir 11 decreases, and the electrolyte concentration fluctuates. The electrolyte solution supply section 60 adjusts the opening degree of the valve V4 and supplies the electrolyte solution from the electrolyte solution tank 61 to the storage section 11 so as to maintain a predetermined water level at which the electrode 14 can be immersed in the electrolyte solution.

The heavy water supply section 65 adjusts the opening degree of the valve V5 and supplies a predetermined amount of heavy water so that the water level in the electrolyte solution tank 61 is maintained. The heater 64 of the electrolyte solution supply unit 60 maintains the electrolyte solution at a predetermined temperature (specifically, 20 to 40° C.). The electrolyte concentration in the electrolyte solution tank 61 is appropriately adjusted in consideration of the amount of heavy water supplied from the heavy water supply section 65, the electrolyte solution temperature, and the amount of electrolyte solution fed to the storage section 11.

The electrolyte concentration within reservoir 11 is monitored by known means. When the electrolysis rate is high and the electrolyte concentration in the storage section 11 increases, the heavy water replenishment section 80 is activated and the valve V6 is opened to supply heavy water from the heavy water tank 84 to the storage section 11. Adjust the electrolyte concentration within.

When deuterium is generated by electrolysis of heavy water, oxygen (O ₂ ) is generated. Further, an inert gas (such as N ₂ ) is conveyed to the storage section 11 along with the supply of the electrolyte solution. When the pressure inside the reservoir 11 reaches 1 atmosphere (1×10 ⁵ Pa) or more, the check valve 16 opens and gas is discharged from the reservoir 11 .

(Determination of completion of reaction)
<S6> Recovery (extraction) of electrolyte solution
After a predetermined period of time has elapsed since the start of deuterium permeation, deuterium permeation is stopped. Specifically, the voltage application by the power source 15 and the exhaust means 18 are stopped, the valves V4, V5, V14, and V24 are closed, and the electrolyte solution supply section 60 is stopped, so that the supply of the electrolyte solution is stopped. . If the heavy water replenishment section 80 has been activated, the valve V6 closes and the heavy water replenishment section 80 stops.

The circulation section 30 extracts substantially all of the electrolyte solution from the storage section 11, making the storage section 11 empty (liquid-free state). The extracted electrolyte solution is temporarily stored in the solution storage section 101.

"Empty (liquid-free state)" means that almost all of the solution stored in the storage section 11 has been extracted, but due to the device configuration, some liquid that could not be physically removed is allowed to remain. do. The electrolyte solution is extracted until at least the surface layer 25 is exposed.

By extracting the electrolyte solution from the reservoir 11 and exposing the surface layer 25, it is possible to suppress radiation detection loss due to the electrolyte solution. This increases detection accuracy.

Depending on the type, the radioactive substance contained in the surface layer 25 may be eluted into the electrolyte solution. By extracting the electrolyte solution from the storage section 11, the influence of radiation emitted from the radioactive substance eluted into the electrolyte solution can be excluded. Thereby, the amount of radioactive material purely in the surface layer 25 can be determined.

After drawing out substantially all of the electrolyte solution, the inside of the reservoir 11 may be dried by a drying means (not shown).

<S7> Monitoring of Radiation Dose The first detector 100 measures the radiation emitted from the structure 13 (radioactive material on the surface layer 25). If the radiation dose obtained through measurement is higher than the first threshold, the determination unit 110 determines that the reaction continues. Based on the determination, the control unit 111 returns the electrolyte solution temporarily stored in the solution storage unit 101 into the storage unit and restarts the reaction. That is, the steps from <S4> to <S7> described above are repeated.

When the radiation dose obtained by measurement falls below the first threshold value, the determination unit 110 determines that the reaction has ended.

<S8> Recovery of surface layer When it is determined that the reaction has ended, the surface layer 25 is recovered from the structure 13.

The power source 15 applies a negative voltage to the electrode 14 that is opposite to that in the step of forming the surface layer 25 . The surface layer 25 is eluted from the structure 13 into the electrolyte solution and peeled off from the structure 13. By obtaining the relationship between the current density and the film forming speed (equivalent to the peeling speed) in advance, it is possible to obtain the time during which only the surface layer 25 is peeled off. Therefore, the peeling of the surface layer 25 can be time-controlled.

After a predetermined period of time has elapsed, power supply 15 stops applying voltage to electrode 14 . Valve V1 is closed and valve V2 is opened. The electrolyte solution containing the eluted component in the storage section 11 is discharged from the storage section 11 to the outside of the nuclide conversion system 1 through the discharge piping 41 and the discharge section 40 . The discharged electrolyte solution is collected.

In the nuclide conversion method of this embodiment, the step of forming the surface layer to the step of recovering the surface layer can be repeatedly performed without replacing the structure 13. The above-mentioned cleaning step can be carried out between the step of collecting the surface layer and the step of forming the next surface layer.

In the description of the first embodiment, the cleaning liquid supply section 90 and the heavy water replenishment section 80 are used together, but since the cleaning liquid supply section 90 and the heavy water replenishment section 80 have the same configuration, in this embodiment, only one of them is used. may be installed.

FIG. 5 shows an energy spectrum diagram obtained by monitoring the radiation dose of the structure 13 having the surface layer 25 containing Cs-137. In FIG. 5, the left side of the thick arrow is before the reaction (initial value before deuterium permeation), and the right side of the thick arrow is after the reaction (after deuterium permeation for a predetermined time). In the figure, the horizontal axis is the energy (keV) of γ-rays, and the vertical axis is the amount of captured γ-rays.

Cs-137 emits 662 keV gamma rays. By monitoring the amount of captured γ-rays around 662 keV on the energy spectrum, changes in the amount of Cs-137 present in the surface layer 25 can be confirmed.

When Cs-137 is converted to a non-radioactive nuclide by the permeation of deuterium, the peak of Cs-137 becomes lower as shown in the graph on the right side of the arrow in Figure 5, and the peak of Cs-137 becomes lower when the raw material Cs-137 is used up. Reactions originating from Cs-137 cannot occur. Therefore, the reaction can be considered to have ended when the amount of γ-ray capture has decreased to the first threshold value.

Preferably, the first threshold is a background level. The first threshold value may be, for example, a value at which the amount of gamma rays captured per hour is 50% of the initial value, or a value at which the number of radiations detected per hour is 1000 counts or less.

[Second embodiment]
FIG. 6 is a schematic diagram of the nuclide conversion system 2 according to this embodiment. FIG. 7 is a flow diagram showing the procedure of the nuclide conversion method according to this embodiment. Descriptions of configurations common to the first embodiment will be omitted.

The nuclide conversion system according to this embodiment differs from the first embodiment in that the first detector 103 is disposed within the low deuterium concentration region 12. In this embodiment, the solution storage section 101 of the circulation section 30 is omitted.

The structure 13 used in this embodiment has a thickness that allows beta rays to pass through. The thickness of the substrate 21 may be 0.01 mm or more and 0.05 mm or less. Substrate 21 includes a bulk hydrogen storage metal or hydrogen storage alloy. Examples of hydrogen storage metals include palladium (Pd) and nickel (Ni). Hydrogen storage alloys include palladium alloys and nickel alloys.
The intermediate layer 24 and the surface layer 25 are the same as those in the first embodiment.

The first detector 103 is placed within the low deuterium concentration section 12 . The first detector 103 may be placed directly opposite the structure 13 and/or in close proximity to the structure 13.

A determination unit 110 is electrically connected to the first detector 103 .

As the first detector 103 disposed in the low deuterium concentration section 12, a β-ray detector is suitable. In that case, the radioactive substance contained in the surface layer 25 is a nuclide that emits β rays.

The β-ray detector is, for example, a Geiger counter. Since the Geiger counter is small and the measuring board and head can be separated, it is relatively easy to approach the object to be measured. Geiger counters have no limit to the continuous operation time. Geiger counters are inexpensive compared to gamma ray detectors.

Examples of nuclides that emit β-rays include Cs-137, Cs-134, Sb-125, Co-60, Pu-241, Sr-90, Ni-63, and H-3.

The nuclide conversion method according to the present embodiment includes a step of forming a surface layer <S11-13>, a step of reacting <S14-15>, a step of determining the end of the reaction <S16>, and a step of recovering radioactive material <S17>. include.

The steps of forming a surface layer <S11-13>, the step of reacting <S14-15>, and the step of recovering radioactive substances <S17> are the same as those of the first embodiment. > is the same. The step <S16> of determining the end of the reaction differs from the first embodiment in that the electrolyte solution is not recovered. In this embodiment, the electrolyte solution extracted from the storage section 11 does not need to be temporarily stored in the solution storage section 101 as in the first embodiment.

(Determination of completion of reaction: S16)
In this embodiment, the completion of the reaction is determined without stopping the permeation of deuterium. Specifically, the first detector 103 measures the radiation continuously emitted from the structure 13 while the electrode 14 is immersed in the electrolyte solution.

If the radiation dose obtained through measurement is higher than the first threshold, the determination unit 110 determines that the reaction continues. The control unit 111 continues the permeation of deuterium and the circulation of the electrolyte solution by the circulation unit 30 until it is determined that the reaction has ended. That is, <S14 to S16> are repeated.

When the radiation dose obtained by the measurement has decreased below the first threshold value, the determining unit 110 determines that the reaction has ended, and proceeds to <S17> the step of collecting the surface layer.

FIG. 8 illustrates a more specific schematic diagram of the vicinity of the structure. The structure 13 is held between a sample stage 120 and a sample fixing jig 121. The storage section 11 and the low deuterium concentration section 12 are each kept airtight by an O-ring 122 attached to the sample stage 120.

A plurality of through holes 123 are formed in a region 120a of the sample stage 120 overlapping with the structure 13. When viewed from the deuterium low concentration region 12 side, the through hole 123 is completely covered by the structure 13. The sample stage 120 is preferably made of aluminum in consideration of workability. The region 120a of the sample stage 120 may be made of punched metal, foamed metal, or metal mesh. By forming the through hole 123 in the region 120a, the structure 13 can be supported while allowing deuterium to pass therethrough. In such a structure, when the structure 13 is thin, the mechanical strength of the structure 13 can be supplemented.

In order to reduce deformation of the sample fixing jig 121 when it is fixed, the sample fixing jig 121 is preferably made of a hard material such as molybdenum or stainless steel.

As shown in FIG. 8, the β-ray detector detects β-rays on the low deuterium concentration region 12 side. There is no electrolyte in the low deuterium concentration section 12. Further, during the reaction process, the inside of the deuterium low concentration section 12 is in a vacuum. Therefore, there is less radiation loss.

In this embodiment, by arranging the first detector 103 within the low deuterium concentration section 12, the progress of the reaction can be confirmed in real time.

[Third embodiment]
FIG. 9 is a schematic diagram of the nuclide conversion system 3 according to this embodiment. FIG. 10 is a flow diagram showing the procedure of the nuclide conversion method according to this embodiment.

The nuclide conversion system 3 according to this embodiment differs from the first embodiment in that a second detector 104 is arranged. Descriptions of configurations common to the first embodiment will be omitted.

The second detector 104 is a device that can detect radiation emitted from the solution stored in the solution storage section 101. When the radioactive substance contained in the surface layer 25 has a nuclide that emits gamma rays, a gamma ray detector such as a Ge semiconductor detector is used as the second detector 104. When the radioactive substance contained in the surface layer 25 has a nuclide that emits neutron beams, a neutron detector is used as the second detector 104. The second detector 104 may be of the same type as the first detector 100 or a different type.

The second detector 104 is arranged to be able to detect radiation emitted from the solution within the solution storage section 101. The relative positions of the second detector 104 and the solution reservoir 101 are fixed.

The second detector 104 is preferably placed close to the solution reservoir 101 . The closer the distance from the radiation source (radioactive material), the greater the amount of radiation that can be detected, increasing detection accuracy.

The second detector 104 may be installed at multiple locations. This improves detection accuracy.

The determination unit 110 is electrically connected to the first detector 100 and the second detector 104.

Similarly to the reaction device 10, the solution storage section 101 may be surrounded by a shielding material (not shown). The shielding material is made of a material capable of shielding radiation emitted from the radioactive substance of the surface layer 25.

The nuclide conversion method according to the present embodiment includes a step of forming a surface layer <S21-23>, a step of reacting <S24-25>, a step of determining the end of the reaction <S26-27>, and a step of recovering radioactive substances <S28>. >Including.

The steps of forming a surface layer <S21-23>, the step of reacting <S24-25>, and the step of recovering radioactive substances <S28> are the same as those of the first embodiment. > is the same. The steps <S26 to S27> for determining the end of the reaction differ from the first embodiment in that they include determination using the second detector.

(Determination of completion of reaction)
<S26> Recovery of electrolyte solution In this embodiment, similarly to <S6> Recovery of electrolyte solution in the first embodiment, after allowing deuterium to permeate for a predetermined period of time, the electrolyte solution is extracted from the storage section 11, and the electrolyte solution is extracted from the storage section 11. Empty 11. The extracted electrolyte solution is temporarily stored in the solution storage section 101.

It is even better to dry the inside of the reservoir 11 using a drying means (not shown) after drawing out substantially all of the electrolyte solution.

<S27> Radiation dose monitoring Radiation dose monitoring is performed by both the first detector 100 and the second detector 104. Monitoring by the first detector 100 is similar to that in the first embodiment.

In this embodiment, the second detector 104 is used to measure radiation emitted from the electrolyte solution stored in the solution storage section 101.

If the first radiation dose obtained by the measurement by the first detector 100 is higher than the first threshold, and the second radiation dose detected by the second detector 104 is less than the second threshold, the determination unit 110 It is determined that the reaction continues. The control unit 111 returns the electrolyte solution temporarily stored in the solution storage unit 101 into the storage unit, and restarts the reaction as in the first embodiment. That is, the steps from <S24> to <S27> described above are repeated.

If the first radiation dose decreases to below the first threshold, if the second radiation dose increases to above the second threshold, and if the first radiation dose is below the first threshold and the second radiation dose increases to If it is two or more thresholds, the determination unit 110 determines that the reaction has ended, and proceeds to <S28> the step of collecting the surface layer.

The second threshold value can be set to a value equivalent to 50% of the initial value of the radiation dose of the structure 13.

During the reaction step <S24-25>, the structure 13 including the surface layer 25 is immersed in the electrolyte solution. A part of the radioactive substance contained in the surface layer 25 may be eluted into the electrolyte solution. The radiation dose obtained by the measurement by the second detector 104 reflects the amount of radioactive material eluted into the electrolyte solution.

The solubility of radioactive substances in electrolyte solutions differs depending on the type. For example, alkali metals are easily soluble, while Co and the like are difficult to dissolve. Moreover, the radioactive substance on the surface of the surface layer 25 is more easily eluted than when it is in the surface layer.

When the first radiation dose exceeds the first threshold value, it is preferable to continue the reaction because there is a large amount of radioactive substance that is a material for the conversion reaction in the structure 13 (surface layer 25). When the first radiation dose exceeds the first threshold value, the amount of radioactive material eluted into the electrolyte solution is small, so it will never exceed the second threshold value.

When the first radiation dose is less than or equal to the first threshold, the reaction efficiency decreases because there is little radioactive material present in the structure 13 (surface layer 25). When the second radiation dose is equal to or greater than the second threshold, much radioactive material is eluted into the electrolyte solution. Therefore, the amount of radioactive substances present in the structure 13 is small, and the reaction efficiency is reduced.

FIGS. 11 and 12 illustrate energy spectrum diagrams obtained by measurements by the first detector and the second detector. FIG. 11 is an energy spectrum diagram when the amount of radioactive material (Cs) eluted into the electrolyte solution is small. FIG. 12 is an energy spectrum diagram when the amount of radioactive material (Cs) eluted into the electrolyte solution is large. In FIGS. 11 and 12, the horizontal axis represents the energy (keV) of γ-rays, and the vertical axis represents the γ-ray count number.

At the start of the conversion reaction, a peak of the radioactive substance (Cs) is observed in the first detector (structure) in both FIGS. 11 and 12. No peak of radioactive substance (Cs) is observed in the second detector (electrolyte solution). The peak of the radioactive substance (Cs) on the first detector becomes smaller during the conversion reaction, and becomes even smaller at the end of the conversion reaction.

When the elution into the electrolyte solution is small, as shown in FIG. 11, the peak of the radioactive substance (Cs) does not become very large in the second detector even at the end of the conversion reaction.

The reaction device 10 and the circulation section 30 are closed spaces, and the radioactive substance (Cs) does not leak to the outside. Radioactive substances (Cs) have a long half-life. Since the reaction step takes about several tens to several hundreds of hours, it is unlikely that the radiation dose would fluctuate as much as shown in FIG. 11 due to natural decay. Therefore, in FIG. 11, it is considered that the radioactive substance (Cs) has been converted to a non-radioactive nuclide.

On the other hand, when there is a large amount of elution into the electrolyte solution, as shown in FIG. 12, the peak of the radioactive substance (Cs) at the second detector becomes a little larger during the conversion reaction, and becomes even larger at the end of the conversion reaction.

Figure 12 shows that even if the radiation dose on the surface of the structure is low, if the radiation dose in the electrolyte solution is high, no conversion reaction is occurring, but radioactive substances are simply eluted from the surface layer. suggests something.

FIG. 13 shows the γ-ray intensity (normalized) before and after the reaction. In any of Runs 1 to 5, it was confirmed that the γ-ray intensity after the reaction (the radiation dose of the structure 13 and the solution stored in the reservoir) was lower than that before the reaction (the initial value of γ-rays).

The nuclide transmutation reaction of the present disclosure occurs by permeating deuterium into a radioactive substance present in the crystal lattice of a hydrogen storage metal or hydrogen storage alloy. Conversion reactions do not occur in radioactive substances that are separated from the structure (surface layer). Therefore, as the amount of radioactive material eluted into the electrolyte solution increases, the radioactive material conversion reaction efficiency decreases.

In this embodiment, the degree of progress of the reaction can be determined more accurately by checking the radiation dose on the surface of the structure and the electrolyte solution. This embodiment is advantageous when the detection target is a radioactive substance that is relatively easily soluble in an electrolyte solution.

[Fourth embodiment]
FIG. 14 is a flow diagram showing the procedure of the nuclide conversion method according to this embodiment. The nuclide conversion system according to this embodiment has the same configuration as the third embodiment (FIG. 9).

In this embodiment, the placement of the second detector 104 is not limited to the vicinity of the solution reservoir 101. The second detector 104 may be arranged so as to be able to measure the radiation of the circulating water flowing through the circulation section 30. The relative positions of the second detector 104 and the circulation section 30 (the location to be measured) are fixed. The second detector 104 may be placed near the extraction pipe 31 and the heat exchanger 32, for example. The wall surface (measurement surface) of the location to be measured is made of a material that can transmit the same type of radiation as the radiation emitted by the radioactive substance of the surface layer 25.

The nuclide conversion method according to the present embodiment includes a step of forming a surface layer <S31-33>, a step of reacting <S34-35>, a step of determining the end of the reaction <S36>, and a step of recovering radioactive material <S37>. include.

The steps of forming a surface layer <S31-33>, the step of reacting <S34-35>, and the step of recovering radioactive substances <S37> are the same as <S1-3>, <S4-5>, and <S8> of the first embodiment. > is the same.
The step <S36> of determining the end of the reaction differs from the first embodiment in that the electrolyte solution is not recovered and determination is made using the second detector. In this embodiment, the electrolyte solution extracted from the storage section 11 does not need to be temporarily stored in the solution storage section 101 as in the first embodiment.

(Determination of completion of reaction: S36)
In this embodiment, the completion of the reaction is determined without stopping the permeation of deuterium. Radiation dose monitoring is performed on both the first detector 100 and the second detector 104.

The first detector 100 continuously measures radiation emitted from the structure 13 while the electrode 14 is immersed in the electrolyte solution.

The second detector 104 continuously measures radiation emitted from the circulating water flowing through the circulation section 30.

If the first radiation dose obtained by the measurement by the first detector 100 is higher than the first threshold, and the second radiation dose detected by the second detector 104 is less than the second threshold, the determination unit 110 It is determined that the reaction continues. The control unit 111 continues the permeation of deuterium and the circulation of the electrolyte solution by the circulation unit 30 until it is determined that the reaction has ended. That is, <S34 to S36> are repeated.

If the first radiation dose decreases to below the first threshold, if the second radiation dose increases to above the second threshold, and if the first radiation dose is below the first threshold and the second radiation dose increases to If it is two or more thresholds, the determination unit 110 determines that the reaction has ended, and proceeds to <S37> the step of collecting the surface layer.

The first threshold value can be set, for example, to a value at which the amount of radiation captured per hour is 50% of the initial value, or to 1000 counts or less per hour. Preferably, the first threshold value is a background level radiation dose.

The second threshold value can be set to a value equivalent to 50% of the initial value of the radiation dose of the structure 13.

In this embodiment, the radiation dose of the structure 13 is measured while the electrolyte solution is stored in the storage part 11. Since a part of the radioactive substance in the surface layer 25 is eluted into the electrolyte solution, it is preferable to consider the detection efficiency of the first detector and the second detector. For example, the value obtained by calculating the radiation dose ratio between the structure and the electrolyte solution from the signal ratio of the first detector and the second detector (for example, 80% of the amount of radioactive material eluted into the electrolyte solution) is set as the second threshold value. It's okay.

FIG. 15 shows the relationship between the amount of radioactive material eluted into the electrolyte solution (first detector:second detector signal ratio) and conversion reaction efficiency. In the figure, the horizontal axis represents the amount of radioactive material eluted into the electrolyte solution (%), and the vertical axis represents the conversion reaction efficiency (%).

As shown in FIG. 15, as the amount of radioactive material eluted into the electrolyte solution increases, the radioactive material conversion reaction efficiency decreases.

In this embodiment, the progress of the reaction can be checked in real time without stopping the reaction.

In the first to fourth embodiments, an internal standard substance may be placed in the field of view of the first detector (100, 103) and the second detector (104). The internal standard substance may be placed, for example, near the surface layer 25, on the wall of the reaction device 10, or the like. When disposed near the surface layer 25, it is preferable to arrange and fix it at a position where it does not touch the surface layer 25. The same applies to the case where it is placed on the wall surface of the reaction device 10.

When the radioactive substance contained in the surface layer 25 is a nuclide that emits gamma rays, Am-241 or the like can be used as an internal standard substance. When the radioactive substance contained in the surface layer 25 is a nuclide that emits neutron beams, 252Cf, 241Am-Be, etc. can be used as an internal standard substance. When the radioactive substance contained in the surface layer 25 is a nuclide that emits β rays, Sr-90 or the like can be used as an internal standard substance.

Quantitative calculation becomes possible by placing an internal standard substance. By placing an internal standard substance, changes in measurement sensitivity can be accommodated.

In the first to fourth embodiments, a calibration curve may be created in advance using an external standard substance for the radiation dose of the structure 13 placed in the reaction apparatus.

In the third embodiment, a calibration curve may be created in advance for the radiation dose of the electrolyte solution stored in the solution storage section 101 using an external standard substance.

In the fourth embodiment, a calibration curve may be created in advance using an external standard substance for the radiation dose of circulating water flowing through the measurement location.

〈Additional notes〉
The nuclide conversion system and nuclide conversion method described in the embodiments described above can be understood, for example, as follows.

A nuclide conversion system (1) according to the present disclosure includes a structure (13) through which deuterium can pass, a storage part (11) and a deuterium low concentration part (12) that are separated by the structure and each form a closed space. , a reaction device (10) having an electrode (14) housed in the reservoir and arranged to face the surface of the structure on the reservoir side, and a power source (15) connected to the electrode; an electrolyte solution supply section (60) that is connected to the storage section and supplies a heavy aqueous solution containing electrolyte to the storage section; The structure includes a return circulation section (30) and a first detector (100) that measures the radiation dose of the structure, and the structure has a hydrogen storage metal or a hydrogen storage alloy and a radioactive material on the side of the storage section. The circulation section has a solution storage section (101) that stores the solution extracted from the storage section.

According to the nuclide transmutation system disclosed above, the heavy aqueous solution can be electrolyzed by immersing the electrode in a heavy aqueous solution containing an electrolyte (electrolyte solution). Heavy water is generated by electrolyzing a heavy water solution containing electrolytes in the reservoir. As a result, the deuterium concentration within the storage portion becomes relatively high, and a deuterium concentration gradient is formed in the thickness direction of the structure (direction from the storage portion side toward the low deuterium concentration portion). Deuterium flows from higher to lower concentrations, resulting in deuterium permeation through the structure. Heavy aqueous solutions do not pass through the structure.

When deuterium is permeated through the structure, a reaction occurs in which radioactive substances contained in the surface layer are converted to other nuclides. Thereby, radioactive substances can be converted into non-radioactive substances.

The first detector can measure the radiation dose of the structure. When radioactive material is converted to non-radioactive material, the amount of radioactivity in the structure decreases. By monitoring the decrease in the radiation dose of the structure using the first detector, the degree of progress of the reaction can be determined.

In the nuclide conversion system disclosed above, the solution extracted from the reservoir can be temporarily stored in the solution reservoir. Thereby, the inside of the storage section can be kept in a solution-free state.

When transmitting deuterium, the structure is immersed in a heavy water solution containing an electrolyte, but some radioactive substances may be eluted into the heavy water solution.

By measuring the radiation dose of the structure after making the inside of the storage part solution-free, the influence of radioactive substances eluted into the solution can be removed. This makes it possible to more accurately determine the amount of radiation emitted from radioactive substances contained in the surface layer.

In one aspect of the above disclosure, the radioactive substance may include a nuclide that emits gamma rays, and the first detector may be a gamma ray detector.

Since γ-rays have high transparency, the radiation dose of the structure can be measured even from outside the reactor. Therefore, the gamma ray detector can be easily installed in existing systems. A gamma ray detector has high spectral resolution and can focus on a desired radioactive substance.

In one aspect of the disclosure, the reaction device may be surrounded by a shielding material (102).

By arranging a shielding material around the reactor, the influence of disturbance factors can be reduced. Disturbing factors are cosmic rays and other radiation sources. Other sources of radioactivity include, for example, heavy water solutions containing electrolytes drawn from reservoirs and stored in solution reservoirs, and electrodeposition solutions.

A nuclide conversion system (2) according to the present disclosure includes a structure through which deuterium can permeate, a storage part and a deuterium low concentration part separated by the structure and each forming a closed space, and a deuterium low concentration part housed in the storage part and the deuterium low concentration part. a reaction device having an electrode arranged to face the surface of the structure on the reservoir side, and a power source connected to the electrode; and an electrolyte connected to the reservoir and supplying a heavy water solution containing the electrolyte to the reservoir. a solution supply section, a circulation section connected to the storage section, which extracts the solution from the storage section and returns the extracted solution to the storage section; and a circulation section, which is housed in the low deuterium concentration section, and is configured to control the radiation dose of the structure. a first detector (103) for measuring , and the structure has a surface layer including a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance on the side of the storage section.

The structure does not allow the heavy water solution contained in the storage section to pass through to the low deuterium concentration section. That is, there is no heavy water solution containing electrolyte in the low deuterium concentration area.
By placing the first detector in the low deuterium concentration area, the first detector can be brought close to the structure. Further, inside the low deuterium concentration area, there is no barrier separating the first detector and the structure. Therefore, radiation loss is small and detection accuracy is high.
When an exhaust means and an exhaust route are connected to the deuterium low concentration section as a low concentration device, the deuterium low concentration section can be evacuated. This reduces radiation loss.

By arranging the first detector in the low deuterium concentration area, there is no need to extract the heavy water solution containing the electrolyte, so continuous monitoring becomes possible. Thereby, the degree of progress of the reaction can be determined without stopping the reaction (while operating continuously).

In one aspect of the above disclosure, the radioactive substance may include a nuclide that emits β-rays, and the first detector may be a β-ray detector.

Beta-emitting nuclides are easier to shield and handle than gamma-emitting nuclides.
The β-ray detector is small and relatively easy to approach the object to be measured. Beta-ray detectors have no restrictions on continuous operation time and are cheaper than gamma-ray detectors. Therefore, it can be easily placed in a low deuterium concentration area.

In one aspect of the above disclosure, the nuclide conversion system may further include a determination unit (110) that determines that the reaction has ended when the radiation dose measured by the first detector has decreased to a first threshold value or less. .

By providing the first threshold value, the criterion for determining the completion of the reaction becomes clear. The first threshold value can be set, for example, to a value at which the amount of radiation captured per hour is 50% of the initial value, or to 1000 counts or less per hour. Preferably, the first threshold value is a background level radiation dose.

In one aspect of the above disclosure, the nuclide conversion system (3) may further include a second detector (104) that measures the radiation dose of the solution extracted from the storage section.

As mentioned above, the solution extracted from the storage unit may contain radioactive substances eluted from the surface layer. By providing a second detector that measures the radiation dose of the solution stored in the solution storage section or the radiation dose of the solution extracted from the storage section, it is possible to know the amount of eluted radioactive material.

In one aspect of the above disclosure, the second detector (104) may have a fixed relative position with respect to the solution storage section so as to be able to measure the radiation dose of the solution stored in the solution storage section.

The solution storage section stores the solution extracted from the storage section. Therefore, by measuring the radiation dose in the solution storage section, a large amount of radiation can be detected. This increases measurement accuracy.

In one aspect of the above disclosure, the nuclide transmutation system further includes a determination unit (110) that determines that the reaction has ended when the second radiation dose obtained by measurement by the second detector increases to a second threshold value or more. Be prepared.

The second radiation dose may reflect the amount of radioactive material eluted from the surface layer. A large amount of eluted radioactive material means that the amount of radioactive material contained in the surface layer is decreasing. As the amount of radioactive material contained in the surface layer decreases, the reaction efficiency also decreases. By adding the second threshold value to the criterion for determining the completion of the reaction, the degree of progress of the reaction can be determined more accurately.

In one aspect of the above disclosure, the first detector may be directly facing the structure.

Radioactive materials are dispersed on the surface. By arranging the first detector to directly face the structure, it is possible to reduce deviation in the distance between each dispersed radioactive substance and the first detector. This increases the accuracy of measuring radiation emitted from radioactive substances.

In one aspect of the above disclosure, the nuclide transmutation system is connected to the storage section and supplies an electrodeposition liquid containing the hydrogen storage metal or the hydrogen storage alloy and the radioactive substance to the storage section. and a discharge part (40) for discharging the solution extracted from the storage part to the outside of the system.

When the electrodeposition liquid is supplied from the electrodeposition liquid supply part into the storage part, the structure and the electrode are immersed in the electrodeposition liquid, and a voltage is applied to the electrode to create a voltage difference between the electrode and the structure, The radioactive substance and hydrogen storage metal or hydrogen storage alloy contained in the electrodeposition solution are electrodeposited on the surface of the structure. This may form a surface layer. After the surface layer is formed, the electrodeposition solution can be discharged out of the system from the discharge section, so that the inside of the storage section is kept solution-free, and a heavy aqueous solution containing an electrolyte can be supplied. In a nuclide conversion system equipped with an electrodeposition liquid supply section, processes from surface layer formation to reaction can be performed within the same device. This greatly reduces the frequency with which radioactive materials are exposed outside the equipment, increasing worker safety.

In one aspect of the above disclosure, an internal standard substance may be placed in the field of view of the first detector.

An internal standard substance is a radioactive substance with known radioactivity. The field of view of the first detector is at least the inside of the reaction device, for example, the inner wall of the reservoir. An internal standard may be placed in the surface layer.

In one aspect of the above disclosure, the nuclide conversion system may further include a cleaning liquid supply unit (90) connected to the storage unit and supplying a cleaning liquid into the storage unit.

The cleaning liquid supply unit can clean the inside of the storage unit from which the electrodeposition liquid is extracted after forming the surface layer using the electrodeposition liquid supply unit. Components of the electrodeposition solution remaining in the reservoir may inhibit the nuclide transmutation reaction. By removing the electrodeposited liquid remaining in the reservoir, the effects of contamination can be reduced.

In one aspect of the disclosure, the structure includes a substrate made of the hydrogen storage metal or the hydrogen storage alloy, and an intermediate layer formed on the substrate, and the intermediate layer includes the hydrogen storage metal or the hydrogen storage alloy. A first layer made of a hydrogen storage alloy and a second layer made of a substance having a relatively low work function with respect to the hydrogen storage metal or the hydrogen storage alloy are laminated, and the surface layer is an intermediate layer. It can be on top of.

It has been confirmed that a conversion reaction occurs when the structure has the above configuration.

The nuclide conversion method according to the present disclosure includes a structure through which deuterium can permeate, a storage part and a deuterium low concentration part separated by the structure and each forming a closed space, and a deuterium low concentration part housed in the storage part and arranged in the structure. A nuclide conversion method using a reaction device having an electrode arranged to face the surface on the storage side and a power supply connected to the electrode, the surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance. The structure is arranged with the structure facing toward the storage part, a heavy water solution containing an electrolyte is supplied to the storage part, and a voltage is applied to the electrode immersed in the heavy water solution containing the electrolyte, so that the electrode and the A voltage difference is generated between the structure and the deuterium is generated from a heavy aqueous solution containing the electrolyte in a space between the electrode and the structure, and the deuterium is stored in the structure by a concentration gradient for a predetermined period of time. The deuterium is transmitted from the deuterium low concentration part side toward the deuterium low concentration part side, the permeation of the deuterium is stopped, and the solution is extracted from the storage part to empty the inside of the storage part, and then the first detector The radiation dose of the structure is measured by, and when the first radiation dose obtained by the measurement by the first detector decreases to a first threshold value or less, the reaction is terminated, and the first radiation dose is When it is higher than the first threshold, the extracted solution is returned to the storage section and the deuterium permeation is restarted.

In one aspect of the above disclosure, the radioactive substance may include a nuclide that emits gamma rays, and the first detector may be a gamma ray detector.

In one aspect of the above disclosure, the reaction device may be surrounded by a shielding material.

The nuclide conversion method according to the present disclosure includes a structure through which deuterium can permeate, a storage part and a deuterium low concentration part separated by the structure and each forming a closed space, and a deuterium low concentration part housed in the storage part and arranged in the structure. A nuclide conversion method using a reaction device having an electrode arranged to face the surface on the storage side and a power supply connected to the electrode, the surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance. a first detector for measuring the radiation dose of the structure is placed in the low deuterium concentration area, and a heavy aqueous solution containing the electrolyte is placed in the storage area. A voltage is applied to the electrode immersed in a heavy water solution containing the electrolyte to create a voltage difference between the electrode and the structure, and the Generating the deuterium from a heavy aqueous solution containing an electrolyte, permeating the deuterium from the storage part side of the structure toward the deuterium low concentration part side according to a concentration gradient, and permeating the deuterium, A first radiation dose of the structure is measured by the first detector, and the reaction is terminated when the first radiation dose obtained by the measurement by the first detector decreases to a first threshold value or less.

In one aspect of the above disclosure, the radioactive substance may include a nuclide that emits β-rays, and the first detector may be a β-ray detector.

In one aspect of the above disclosure, a second radiation dose of the electrolyte solution extracted from the storage part is measured by a second detector, and when the second radiation dose increases to a second threshold value or more, the reaction is terminated. It's okay.

In one aspect of the above disclosure, it is preferable that an internal standard substance be placed in the field of view of the first detector.

1, 2, 3 Nuclide conversion system 10 Reactor 11 Storage part 12 Deuterium low concentration part 13 Structure 14 Electrode 15 Power supply 16 Check valve 17 Low concentration device 18 Exhaust means 19 Exhaust route 20, 56, 64 Heater 21 Substrate 22 First layer 23 Second layer 24 Intermediate layer 30 Circulation section 31 Extraction piping 32 Heat exchanger 33 Filter 34 Pump 35 Re-supply piping 40 Discharge section 41 Discharge piping 50 Electrodeposition liquid supply section 51 Electrodeposition liquid tank 52 Electrodeposition Liquid supply piping 53, 66, 72, 81, 91 Inert gas supply piping 54, 67, 73, 82, 92 Dehumidifier 55, 68, 74, 83, 93 Dry inert gas supply piping 60 Electrolyte solution supply Part 61 Electrolyte solution tank 62 Electrolyte solution supply pipe 63 Electrolyte salt 65 Heavy water supply part 69, 84 Heavy water tank 70 Heavy water supply pipe 71 Inert gas supply part 80 Heavy water replenishment part 85 Heavy water replenishment pipe 90 Cleaning liquid supply part 94 Cleaning liquid tank 95 Cleaning liquid supply piping 100, 103 First detector 101 Solution storage section 102 Shielding material 104 Second detector 110 Judgment section 111 Control section 120 Sample stage 120a Region 121 Sample fixing jig 122 O ring 123 Through hole

Claims (18)

a structure through which deuterium can permeate; a storage part and a deuterium low concentration part separated by the structure and each forming a closed space; housed in the storage part and arranged to face a surface of the structure on the storage part side; a reaction device having an electrode connected to the electrode, and a power source connected to the electrode;
an electrolyte solution supply unit connected to the storage unit and supplying a heavy water solution containing electrolyte to the storage unit;
a circulation unit connected to the storage unit, which extracts the solution from the storage unit and returns the extracted solution to the storage unit;
a first detector that measures the radiation dose of the structure;
a second detector that measures the radiation dose of the solution extracted from the storage section;
a determination unit that determines that the reaction has ended when a second radiation dose obtained by measurement by the second detector increases to a second threshold value or more;
Equipped with
The structure has a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance on the storage side,
The circulation section is a radionuclide processing system including a solution storage section that stores the solution extracted from the storage section. The radioactive substance has a nuclide that emits γ rays,
The radionuclide processing system according to claim 1, wherein the first detector is a gamma ray detector. The radionuclide processing system according to claim 1 or 2, wherein the reaction device is surrounded by a shielding material. a structure through which deuterium can permeate; a storage part and a deuterium low concentration part separated by the structure and each forming a closed space; housed in the storage part and arranged to face a surface of the structure on the storage part side; a reaction device having an electrode connected to the electrode, and a power source connected to the electrode;
an electrolyte solution supply unit connected to the storage unit and supplying a heavy water solution containing electrolyte to the storage unit;
a circulation unit connected to the storage unit, which extracts the solution from the storage unit and returns the extracted solution to the storage unit;
a first detector that is housed in the low deuterium concentration area and measures the radiation dose of the structure;
a second detector that measures the radiation dose of the solution extracted from the storage section;
a determination unit that determines that the reaction has ended when a second radiation dose obtained by measurement by the second detector increases to a second threshold value or more;
Equipped with
The structure is a radionuclide processing system having, on the side of the storage section, a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance. The radioactive substance has a nuclide that emits β rays,
The radionuclide processing system according to claim 4, wherein the first detector is a β-ray detector. The radionuclide treatment according to any one of claims 1 to 5, further comprising a determination unit that determines that the reaction has ended when the first radiation dose obtained by measurement by the first detector decreases to a first threshold value or less. system. The radionuclide treatment according to any one of claims 1 to 3, wherein the second detector has a fixed position relative to the solution storage unit so as to be able to measure the radiation dose of the solution stored in the solution storage unit. system. The radionuclide processing system according to claim 1 , wherein the first detector directly faces the structure. an electrodeposition liquid supply unit connected to the storage unit and supplying an electrodeposition liquid containing the hydrogen storage metal or the hydrogen storage alloy and the radioactive substance to the storage unit;
a discharge section that discharges the solution extracted from the storage section to the outside of the system;
The radionuclide processing system according to any one of claims 1 to 8 , further comprising: The radionuclide processing system according to any one of claims 1 to 9 , wherein an internal standard substance is placed in the field of view of the first detector. The radionuclide processing system according to claim 10 , further comprising a cleaning liquid supply unit connected to the storage unit and supplying cleaning liquid into the storage unit. The structure includes a substrate made of the hydrogen storage metal or the hydrogen storage alloy, and an intermediate layer formed on the substrate,
The intermediate layer includes a first layer made of the hydrogen storage metal or the hydrogen storage alloy, and a second layer made of a substance having a relatively low work function with respect to the hydrogen storage metal or the hydrogen storage alloy. The configuration is
The radionuclide processing system according to any one of claims 1 to 11 , wherein the surface layer is above the intermediate layer. a structure through which deuterium can permeate; a storage part and a deuterium low concentration part separated by the structure and each forming a closed space; housed in the storage part and arranged to face a surface of the structure on the storage part side; A radionuclide processing method using a reaction device having an electrode and a power source connected to the electrode, the method comprising:
arranging the structure with a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance facing the reservoir side;
supplying a heavy water solution containing an electrolyte to the storage section;
A voltage is applied to the electrode immersed in a heavy water solution containing the electrolyte to create a voltage difference between the electrode and the structure, and the space between the electrode and the structure contains the electrolyte. generating the deuterium from a heavy aqueous solution and permeating the deuterium from the storage part side of the structure toward the deuterium low concentration part side according to a concentration gradient for a predetermined time;
After stopping the permeation of the deuterium and draining the solution from the reservoir to empty the reservoir, the radiation dose of the structure is measured by a first detector, and the radiation dose obtained by the measurement by the first detector is terminating the reaction when the first radiation dose received falls below a first threshold;
When the first radiation dose is higher than the first threshold, returning the extracted solution to the storage section and restarting the permeation of the deuterium,
Measuring a second radiation dose of the electrolyte solution extracted from the storage part with a second detector,
A radionuclide processing method that determines that the reaction has ended when the second radiation dose increases to a second threshold value or more . The radioactive substance has a nuclide that emits γ rays,
The radionuclide processing method according to claim 13 , wherein the first detector is a gamma ray detector. The radionuclide processing method according to claim 13 or 14 , wherein the reaction device is surrounded by a shielding material. a structure through which deuterium can permeate; a storage part and a deuterium low concentration part separated by the structure and each forming a closed space; housed in the storage part and arranged to face a surface of the structure on the storage part side; A radionuclide processing method using a reaction device having an electrode and a power source connected to the electrode, the method comprising:
arranging the structure with a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance facing the reservoir side;
disposing a first detector for measuring the radiation dose of the structure in the low deuterium concentration area;
supplying a heavy water solution containing an electrolyte to the storage section;
A voltage is applied to the electrode immersed in a heavy water solution containing the electrolyte to create a voltage difference between the electrode and the structure, and the space between the electrode and the structure contains the electrolyte. generating the deuterium from a heavy aqueous solution and permeating the deuterium from the storage section side of the structure toward the deuterium low concentration section side according to a concentration gradient;
measuring a first radiation dose of the structure with the first detector while transmitting the deuterium;
terminating the reaction when the first radiation dose obtained by measurement by the first detector falls below a first threshold;
Measuring a second radiation dose of the electrolyte solution extracted from the storage part with a second detector,
A radionuclide processing method that determines that the reaction has ended when the second radiation dose increases to a second threshold value or more . The radioactive substance has a nuclide that emits β rays,
The radionuclide processing method according to claim 16 , wherein the first detector is a β-ray detector. The radionuclide processing method according to any one of claims 13 to 17 , wherein an internal standard substance is placed in the field of view of the first detector.

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