JP2022051176A - Nuclide conversion system and nuclide conversion method - Google Patents

Abstract

To provide a nuclide conversion system and a nuclide conversion method capable of recognizing the degree of progress of reaction of a heavy hydrogen with a radioactive substance in a nondestructive and non-contact state.SOLUTION: A nuclide conversion system 1 comprises: a reaction apparatus 10 having a structure 13 allowing a heavy hydrogen to penetrate, a storage part 11, a heavy hydrogen low-concentration part 12, an electrode 14 and a power source 15; an electrolyte solution supply part 60 for supplying an electrolyte-containing heavy water solution to the storage part 11; a circulation part 30 for extracting a solution from the storage part 11 and returning the extracted solution to the storage part 11; and a first detector 100 for measuring an amount of radiation of the structure 13. The structure 13 has a surface layer 25 having a hydrogen storage metal or a hydrogen storage alloy, and a radioactive substance at a storage part 11 side, and the circulation part 30 has a solution storage part 101 for storing the solution extracted from the storage part 11.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a nuclide conversion system and a nuclide conversion method relating to radioactive waste treatment technology, technology for producing rare elements from elements abundant in nature, and the like.

When reprocessing spent nuclear fuel, first, the spent nuclear fuel is 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 effluent is disposed of by burying it in the stratum, for example, but how to dispose of it is an issue to be examined.

Patent Documents 1 and 2 disclose a technique for converting a substance such as Cs into another nuclide by using a simple and small-scale device. In Patent Documents 1 and 2, deuterium is reacted with a substance to be converted into a nuclide.

In Patent Document 2, a heavy aqueous solution containing an electrolyte is electrolyzed to generate deuterium gas, and the generated deuterium gas is permeated through a structure provided with a substance to be subjected to nuclide conversion to carry out a nuclide conversion reaction. I'm waking you up.

Japanese Patent No. 4346838 Japanese Patent No. 6486600

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

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

When a radioactive substance is used as a substance to be converted into a nuclide, it is necessary to pay attention to its handling from the viewpoint of safety and the like. Therefore, it is preferable that the progress of the reaction can be determined in such a manner that the worker does not come into contact with radioactive substances.

The present disclosure is made in view of such circumstances, and provides a nuclide conversion system and a nuclide conversion method capable of determining the progress of the reaction between deuterium and radioactive substances in a non-destructive and non-contact manner. With the goal.

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

The present disclosure discloses a structure through which heavy hydrogen can permeate, a storage portion separated by the structure and forming a closed space, a heavy hydrogen low concentration portion, and a storage portion accommodated in the storage portion on the storage portion side of the structure. An electrode arranged facing the surface, a reaction device having a power source connected to the electrode, an electrolyte solution supply unit connected to the storage unit and supplying a heavy aqueous solution containing an electrolyte to the storage unit, and the storage unit. The structure is provided with a circulation unit which is connected to the storage unit, extracts a solution from the storage unit, and returns the extracted solution to the storage unit, and a first detector for measuring the radiation dose of the structure. The storage unit side has a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance, and the circulation unit provides a nuclear species conversion system having a solution storage unit for storing a solution extracted from the storage unit. ..

In the present disclosure, a structure through which heavy hydrogen can permeate, a storage portion separated by the structure and forming a closed space and a low concentration portion of heavy hydrogen, respectively, and a storage portion housed in the storage portion on the storage portion side of the structure. An electrode arranged facing the surface, a reaction device having a power source connected to the electrode, an electrolyte solution supply unit connected to the storage unit and supplying a heavy aqueous solution containing an electrolyte to the storage unit, and the storage unit. A circulation unit that is connected to the storage unit, extracts a solution from the storage unit, and returns the extracted solution to the storage unit, and a first detector that is housed in the heavy hydrogen low concentration unit and measures the radiation dose of the structure. The structure provides a nuclear species conversion system having a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance on the reservoir side.

The present disclosure discloses a structure through which heavy hydrogen can permeate, a storage portion separated by the structure and forming a closed space, a low concentration portion of heavy hydrogen, and a storage portion accommodated in the storage portion on the storage portion side of the structure. It is a nuclear species conversion method using an electrode arranged facing the surface and a reactor having a power source connected to the electrode, and a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance is placed on the storage portion side. A heavy aqueous solution containing an electrolyte is supplied to the storage portion, and a voltage is applied to the electrode immersed in the heavy aqueous solution containing the electrolyte to apply a voltage between the electrode and the structure. In the space between the electrode and the structure, the heavy hydrogen is generated from the heavy aqueous solution containing the electrolyte, and the weight is generated from the storage portion side of the structure by a concentration gradient for a predetermined time. The heavy hydrogen is permeated toward the hydrogen low concentration portion side, the permeation of the heavy hydrogen is stopped, the solution is withdrawn from the reservoir to empty the inside of the reservoir, and then the structure is subjected to the first detector. When the radiation amount is measured and the first radiation amount obtained by the measurement of the first detector drops below the first threshold value, the reaction is terminated and the first radiation amount is higher than the first threshold value. Provided is a nuclear species conversion method in which the extracted solution is returned to the reservoir and the permeation of the heavy hydrogen is restarted when the amount is high.

The present disclosure discloses a structure through which deuterium can permeate, a storage portion separated by the structure and forming a closed space, a deuterium low concentration portion, and a storage portion on the storage portion side of the structure, which is housed in the storage portion. It is a nuclear species conversion method using an electrode arranged facing the surface and a reactor having a power source connected to the electrode, and has a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance on the storage portion side. The structure is arranged toward the center, a first detector for measuring the radiation amount of the structure is arranged in the deuterium low concentration portion, a heavy aqueous solution containing the electrolyte is supplied to the storage portion, and the electrolyte is provided. A voltage is applied to the electrode immersed in the heavy aqueous solution containing hydrogen to generate a voltage difference between the electrode and the structure, and the heavy aqueous solution containing the electrolyte is generated in the space between the electrode and the structure. The deuterium is generated from the above, and the deuterium is permeated from the storage portion side of the structure toward the deuterium low concentration portion side by a concentration gradient, and the first detector is permeated while permeating the deuterium. Provided is a method for converting a nuclear species, which measures the radiation amount of the structure and terminates the reaction when the first radiation amount obtained by the measurement of the first detector drops below the first threshold value.

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

It is a schematic diagram of the nuclide conversion system which concerns on 1st Embodiment. It is sectional drawing of an example of a structure. It is a schematic diagram which illustrates the arrangement of a shielding material. It is a flow chart which shows the procedure of the nuclide conversion method which concerns on 1st Embodiment. It is an energy spectrum diagram obtained by the measurement of the 1st detector. It is a schematic diagram of the nuclide conversion system which concerns on 2nd Embodiment. It is a flow chart which shows the procedure of the nuclide conversion method which concerns on 2nd Embodiment. It is a schematic diagram which shows an example of the arrangement of the 2nd detector. It is a schematic diagram of the nuclide conversion system which concerns on 3rd Embodiment. It is a flow chart which shows the procedure of the nuclide conversion method which concerns on 3rd Embodiment. It is an energy spectrum diagram obtained by the measurement of the 1st detector and the 2nd detector. It is an energy spectrum diagram obtained by the measurement of the 1st detector and the 2nd detector. It is a figure which shows the γ-ray intensity (normalization) before and after a reaction. It is a flow chart which shows the procedure of the nuclide conversion method which concerns on 4th Embodiment. It is a figure which shows the relationship between the amount of radioactive substances elution into an electrolyte solution, and the conversion reaction efficiency.

The nuclide conversion system and the radioactive material treatment system according to the present disclosure include a reaction device, a high concentration device, and a low concentration device. The reactor comprises a structure having a surface layer. The surface layer contains radioactive materials and hydrogen storage metals or hydrogen storage alloys.

In the nuclide conversion method according to the present disclosure, deuterium is permeated through the structure from the surface layer side, and the radioactive substance contained in the surface layer is converted into 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 monitoring value, and the timing of the end of the reaction is measured.

Hereinafter, an embodiment of the nuclide conversion system and the nuclide conversion method according to the present disclosure will be described with reference to the drawings.

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

The nuclide conversion system 1 may include a discharge unit 40 and an electrodeposition liquid supply unit 50. The nuclide conversion system 1 may include a cleaning liquid supply unit 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 apparatus 10 includes a storage unit 11, a deuterium low concentration unit 12, a structure 13, an electrode 14, and a power source 15.

The storage portion 11 and the deuterium low concentration portion 12 are separated by a structure 13, and each constitutes a closed space. The storage unit 11 and the deuterium low-concentration unit 12 are configured to allow γ-rays derived from radioactive substances contained in the surface layer, which will be described later, to pass through. In order to allow γ-ray transmission, it is better to use a material having as low a density as possible for the storage unit 11 (at least the γ-ray detection unit). For example, it is preferable to apply PTFE (2.2 g / cm ³ ) or aluminum (2.7 g / cm ³ ) rather than lead (11.3 g / cm ³ ) or iron (7.87 g / cm ³ ). The storage unit 11 can store the liquid in the 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 (the surface opposite to the substrate 21) on one surface side of the structure 13. In the reaction apparatus 10, the structure 13 is arranged so that the substrate 21 faces the deuterium low concentration portion 12 side and the surface layer 25 faces the storage portion 11.

The substrate 21 contains a bulk hydrogen storage metal or hydrogen storage alloy. The hydrogen storage metal is palladium (Pd), nickel (Ni) or the like. The hydrogen storage alloy is a palladium alloy, a nickel alloy, or the like. The thickness of the substrate 21 should be thin in terms of cost, but in consideration of mechanical strength, it is, for example, 0.01 mm to 1 mm.

The intermediate layer 24 is a laminated body in which the first layer 22 and the second layer 23 are alternately laminated. The first layer 22 and the second layer 23 can be laminated on the substrate 21 by a sputtering method or an electrodeposition method. In the sputtering method, film formation is repeatedly performed in order to form a layer having a predetermined thickness.

The first layer 22 contains a hydrogen storage metal or a hydrogen storage alloy. The hydrogen storage metal or hydrogen storage alloy contained in the first layer 22 may be of the same type as the hydrogen storage metal or hydrogen storage alloy contained in the substrate 21.

The second layer 23 contains a low work function substance having a relatively low work function with respect to the metal contained in the substrate 21. The low work function substance is a substance that easily emits electrons, and the work function of the low work function substance is less than 3 eV. Low work function substances include, for example, 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 should be selected as the low work function substance.

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

The hydrogen storage metal is, for example, palladium (Pd), nickel (Ni), or the like. The hydrogen storage alloy is, for example, a palladium alloy, a nickel alloy, or the like.

Radioactive materials have nuclides that emit gamma or neutron rays. The nuclides that emit γ-rays are, for example, Cs-137, Cs-134, Sb-125, and Co-60. The nuclide that emits neutron rays is, for example, Pu-241.

The electrode 14 is housed in the reservoir 11. The electrodes 14 are arranged so as to face each other apart from the surface of the structure 13 on the storage portion 11 side. The electrode 14 is a plate-shaped member manufactured from platinum (Pt) or the like. The electrode 14 may have a mesh structure. By making the structure physically perforated, the radiation emitted from the structure 13 can easily pass through.

The power supply 15 is arranged outside the reactor 10. The power supply 15 is connected to the electrode 14.

A check valve 16 is installed in the storage unit 11. The check valve 16 is provided in a flow path connecting the storage unit 11 and the external atmosphere. The check valve 16 closes when the air pressure of the external atmosphere is higher than the air pressure of the gas stored in the storage unit 11. The check valve 16 is opened when the air pressure of the gas stored in the storage unit 11 is larger than the air pressure of the external atmosphere, and the gas in the storage unit 11 is exhausted to the external atmosphere.

The reactor 10 may include a heater 20. The heater 20 is installed in the vicinity of the structure 13 in the deuterium low concentration portion 12. The heater 20 heats the deuterium low concentration portion 12 side of the structure 13 to a predetermined temperature.

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

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

The heavy water supply unit 65 includes an inert gas supply pipe 66, a dehumidifying device 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 connecting the gas source (not shown) and the dehumidifying device 67. The dry inert gas supply pipe 68 forms a flow path connecting the dehumidifying device 67 and the heavy water tank 69.

The heavy water tank 69 constitutes a closed space in which heavy water ₍ D2O) is stored. The heavy water supply pipe 70 forms a flow path connecting the heavy water tank 69 and the electrolyte solution tank 61.

The inert gas supplied from the gas source (not shown) is supplied to the heavy water tank 69 via the inert gas supply pipe 66, the dehumidifying device 67, and the dry inert gas supply pipe 68. As a result, the inside of the heavy water tank 69 is pressurized, and the heavy water is supplied to the electrolyte solution tank 61 through the heavy water supply pipe 70. The amount of heavy water supplied is controlled by the valve V5 installed in the heavy water supply pipe 70.

The inert gas supply unit 71 includes an inert gas supply pipe 72, a dehumidifying device 73, and a dry inert gas supply pipe 74.

The inert gas supply pipe 72 forms a flow path connecting the gas source (not shown) and the dehumidifying device 73. The dry inert gas supply pipe 74 forms a flow path connecting the dehumidifying device 73 and the electrolyte solution tank 61.

The inert gas supply unit 71 supplies nitrogen gas supplied from a gas source (not shown) to the electrolyte solution tank 61. The inside of the electrolyte solution tank 61 is pressurized by supplying nitrogen gas from the drying inert gas supply pipe 74 to the electrolyte solution tank 61.

The electrolyte solution tank 61 constitutes a closed space in which the electrolyte solution is stored. The electrolyte salt 63 is arranged at the bottom of the electrolyte solution tank 61. The type of the electrolyte salt 63 is not particularly limited, but it is preferably a salt having the same element as the radioactive substance described later. For example, cesium nitrate CsNO ₃ , cesium hydroxide CsOH, antimony sulfide Sb ₂ S ₃ , cobalt nitrate Co (NO ₃ ) ₂ , and plutonium nitrate Pu (NO ₃ ) ₄ . The solvent of the electrolyte solution is heavy water. The electrolyte salt 63 is dissolved by immersing it in heavy water to generate an electrolyte solution (heavy aqueous solution containing an electrolyte).

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 unit 65, the concentration of the electrolyte in the electrolyte solution is adjusted. In this embodiment, the electrolyte concentration is between 0.001 mol / l and the saturated concentration.

The electrolyte solution supply pipe 62 forms a flow path connecting the electrolyte solution tank 61 and the storage portion 11. By pressurizing the inside of the electrolyte solution tank 61, the solution is supplied to the storage unit 11 through the electrolyte solution supply pipe 62. The supply amount of the electrolyte solution is controlled by the valve V4 installed in the electrolyte solution supply pipe 62.

The electrolyte solution supply unit 60 may include a heavy water replenishment unit 80. The heavy water replenishment unit 80 is connected to the storage unit 11. The heavy water replenishment unit 80 includes an inert gas supply pipe 81, a dehumidifying device 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 connecting the gas source (not shown) and the dehumidifying device 82. The dry inert gas supply pipe 83 forms a flow path connecting the dehumidifying device 82 and the heavy water tank 84. The heavy water replenishment pipe 85 forms a flow path connecting the heavy water tank 84 and the storage portion 11. The heavy water tank 84 constitutes a closed space in which heavy water ₍ D2O) is stored.

Nitrogen gas supplied from a gas source (not shown) is supplied to the heavy water tank 84 via the inert gas supply pipe 81, the dehumidifying device 82, and the dry inert gas supply pipe 83, and the inside of the heavy water tank 84 is filled. It is pressurized. By pressurizing the inside of the heavy water tank 84, heavy water is supplied to the storage unit 11 through the heavy water replenishment pipe 85. The amount of heavy water supplied is controlled by the valve V6 installed in the heavy water replenishment pipe 85.

(Low concentration device)
The low concentration device 17 has a configuration in which the deuterium concentration is relatively low in the deuterium low concentration section 12 with respect to the storage section 11. In the present embodiment, the low concentration device 17 has an exhaust means 18 and an exhaust path 19.

The exhaust means 18 is connected to the deuterium low concentration portion 12 via the exhaust path 19. The exhaust means 18 discharges the gas inside the deuterium low concentration unit 12 to reduce the pressure inside the deuterium low concentration unit 12. FIG. 1 shows a case where a vacuum pump is used as the exhaust means 18. Vacuum pumps are, for example, turbo molecular pumps and dry pumps.

The concentration reducing device 17 may be an inert gas supply unit. The inert gas supply unit includes a gas source, an inert gas supply pipe, and an exhaust pipe. The inert gas supply unit supplies the inert gas (for example, _N2 , Ar) to the deuterium low concentration unit 12. Since the inside of the deuterium low concentration portion 12 is maintained at a predetermined pressure, the gas in the deuterium low concentration portion 12 is discharged through the exhaust pipe.

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

The first detector 100 is arranged so that the radiation emitted from the structure 13 can be detected. The relative position between the first detector 100 and the reaction device 10 (measurement target) is fixed.

The first detector 100 may be arranged near the surface layer 25 of the structure 13, for example, close to the storage unit 11. The closer the distance from the radiation source (radioactive substance), the larger the amount of radiation that can be detected, so the detection accuracy can be improved.

In FIG. 1, the first detector 100 is arranged next to the storage unit 11, but the arrangement of the first detector 100 is not limited to this.

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

The radioactive material is dispersed in the surface layer. When the first detector 100 is arranged on the side surface of the plate-shaped structure 13 (on the left side of the paper in FIG. 1), the first detector 100 is located on the side close to the first detector 100 and on the side opposite to the first detector 100. There is a difference in the distance from. As the distance from the radiation source increases, the amount of radiation that can be detected decreases. Therefore, it is preferable that the distance between the radioactive source and the first detector 100 is constant. By fixing the first detector 100 so as to face 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 surface of the structure 13 and the first detector 100 varies. The width can be reduced.

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

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

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 the disturbance factor is small, the noise is reduced and the background is kept low, so that the change in the radiation dose can be obtained more accurately.

In FIG. 3, three sides of the reaction device 10 are surrounded by the shielding material 102, but the arrangement of the shielding material 102 is not limited to this. The shield 102 may be arranged to shield radiation emitted from other configurations having a radiation source, such as the electrolyte solution tank 61 and / or the solution reservoir 101.

The first detector 100 may be installed at a plurality of places. As a result, the detection accuracy is improved.

(Circulation part)
The circulation unit 30 can extract the solution from the storage unit 11 and return the extracted solution to the storage unit 11. The circulation unit 30 includes an extraction pipe 31, a solution storage unit 101, a heat exchanger 32, a filter 33, a pump 34, a resupply pipe 35, and a valve V1 installed in the resupply pipe 35.

One end of the extraction pipe 31 is connected to the storage unit 11 so that the solution can be extracted from the storage unit 11. The extraction pipe 31 is preferably configured so that substantially the entire amount of the solution in the storage unit 11 can be extracted. For example, in FIG. 1, the extraction pipe 31 is passed through the middle portion of the wall surface of the storage portion 11, and one end thereof is arranged at the bottom of the storage portion 11. Not limited to this, the extraction pipe 31 may be connected to the lower wall surface or the bottom surface of the storage unit 11.

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

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

The heat exchanger 32 cools the solution extracted from the reservoir 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 via the resupply pipe 35 to the storage unit 11. The resupply pipe 35 may be temporarily arranged so as to face between the structure 13 and the electrode 14. As a result, the surface of the structure 13 can be efficiently cooled.

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

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

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 dehumidifying device 54, and a dry inert gas supply pipe 55.

The inert gas supply pipe 53 forms a flow path connecting the gas source (not shown) and the dehumidifying device 54. The inert gas supply pipe 53 supplies the inert gas having a predetermined flow rate among the inert gases supplied from the gas source (CE (Cold Evaporator) _N ₂ in FIG. 1) to the dehumidifying device 54. Ar gas or the like can also be applied as the inert gas.

The dehumidifying device 54 includes a filter with a dehumidifying function exemplified by silica gel. The dehumidifying device 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 connecting the dehumidifying device 54 and the electrodeposition liquid tank 51. The drying inert gas supply pipe 55 supplies the inert gas having a predetermined flow rate among the inert gases dried by the dehumidifying device 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 liquid 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 contains radioactive material to be contained in the surface layer 25. A salt of the radioactive substance may be added to the electrodeposition liquid.

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 connecting 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 drying inert gas supply pipe 55 to the electrodeposition liquid tank 51. As a result, the electrodeposition liquid is supplied to the storage unit 11 of the reaction device 10 through the electrodeposition liquid supply pipe 52. The supply amount of the electrodeposition liquid is controlled by the valve V3 installed in the electrodeposition liquid supply pipe 52.

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

The cleaning liquid supply unit 90 includes an inert gas supply pipe 91, a dehumidifying device 92, a dry inert gas supply pipe 93, a cleaning liquid tank 94, and a cleaning liquid supply pipe 95. The drying inert gas supply pipe 93 forms a flow path connecting the dehumidifying device 92 and the cleaning liquid tank 94. The cleaning liquid supply pipe 95 forms a flow path connecting the cleaning liquid tank 94 and the storage unit 11. A valve V7 is installed in the cleaning liquid supply pipe 95.

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

(Judgment unit)
The determination unit 110 is electrically connected to the first detector 100. The determination unit 110 determines that the reaction is completed when the radiation amount obtained by the measurement of the first detector 100 drops below the first threshold value.

The first threshold value can be set, for example, to be a value at which the amount of radiation captured per hour is 50% of the initial value, or 1000 counts or less per hour. The first threshold is preferably a background level radiation dose. The initial value is the radiation dose of the structure 13 arranged in the reservoir 11 obtained by the measurement of 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 reducing 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, exhaust, and the like of the solution from each unit. When the determination unit 110 determines that the reaction is completed, the control unit 111 stops the supply of the electrolyte solution and the exhaust gas in the concentration reducing device 17.

The control unit 111 is composed of, 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. As an example, a series of processes for realizing various functions are stored in a storage medium or the like in the form of a program, and the CPU reads this program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized. The program is installed in a ROM or other storage medium in advance, is provided in a state of being stored in a computer-readable storage medium, or is distributed via a wired or wireless communication means. Etc. may be applied. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

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

When the structure 13 on which the surface layer 25 is formed in advance is used, the steps (S1 to 3) for forming the surface layer are omitted.

In the present embodiment, it is assumed that the surface layer 25 is not formed on the structure 13 at the time when the structure 13 is installed on the reaction device 10. Not limited to this, 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 3) are omitted. The structure 13 is arranged so that the surface layer 25 faces the storage portion 11.

(Preparation)
The structure 13 is arranged in the reaction device 10 so that the storage portion 11 and the deuterium low concentration portion 12 are in a closed space in which airtightness is maintained. The electrodes 14 are arranged so as to face the structure 13 with a gap from the structure 13.

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

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

The valve V2 of the discharge unit 40 is closed. The pump 34 of the circulation unit 30 operates, and at the same time, 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 unit 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 storage unit 11, the valves V1, V3, V13, and V23 are closed, and the pump 34 is stopped.

<S2> The electrodeposition 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, and a surface layer (electrodeposition layer) is formed. In the process of forming the surface layer, radioactive substances contained in the electrodeposition liquid are taken in (embedded) in the surface layer.

<S3> Recovery of electrodeposition liquid After the surface layer formation is completed, the valve V2 is opened and the pump 34 is started. The electrodeposited liquid in the storage unit 11 is discharged to the outside of the system through the extraction pipe 31 and the discharge unit 40. The discharged electrodeposition liquid is collected. The recovered 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 storage unit 11 or the like.

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

After a lapse of a predetermined time, the valves V1, V7, V17, and V27 are closed and the valves V2 are opened. As a result, the cleaning liquid is discharged to the outside of the system through the discharge unit 40.

(reaction)
<S4> Supply of Electrolyte Solution When the discharge of the electrodeposition liquid or the cleaning liquid (when the cleaning step is performed) is completed, the valve V2 is closed and the valve V1 is opened.

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

The electrolyte solution is a heavy aqueous solution containing an electrolyte. When the electrolyte solution is fed until the electrode 14 is immersed, the valves V14, V24 and V4 are closed.

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

Circulation by the circulation unit 30 is also continued by permeation of <S5> deuterium, which will be described later. By circulating the cooled electrolyte solution, the temperature rise of the surface layer 25 due to the heat generated by the reaction can be suppressed.

<S5> The deuterium permeation low concentration device 17 operates. The vacuum pump (exhaust means 18) is started in the nuclide conversion system 1 of FIG. 1, and the deuterium low concentration portion 12 is depressurized. The pressure in the deuterium low concentration portion 12 is preferably <0.1 Pa.

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

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

The power supply 15 applies a voltage to the electrode 14 immersed in the electrolyte solution to generate a voltage difference between the electrode (anode) 14 and the structure (negative electrode) 13. The voltage difference is at least 2V or more. When a voltage is applied, heavy water is electrolyzed on the surface of the structure 13 on the storage portion 11 side, and deuterium (D ₂ ) is generated. Since a heavy aqueous solution containing an electrolyte is used in this embodiment, electrolysis is promoted. If the voltage difference is less than 2V, the electrolysis reaction does not proceed sufficiently.

When deuterium is generated on the surface on the storage portion 11 side, a deuterium concentration gradient is generated between the surface on the storage portion 11 side of the structure 13 and the surface on the deuterium low concentration portion 12 side. When the deuterium low concentration portion 12 is depressurized (or filled with an inert gas), the concentration gradient between the surface of the structure 13 on the storage portion 11 side and the surface on the deuterium low concentration portion 12 side becomes large. .. Due to the concentration gradient, the deuterium generated in the storage unit 11 flows to the deuterium low concentration unit 12 side and permeates the structure 13.

Further, when the deuterium low concentration portion 12 side of the structure 13 is heated by the heater 20, a temperature gradient is generated between the surface of the structure 13 on the storage portion 11 side and the surface of the structure 13 on the deuterium low concentration portion 12 side. .. The temperature gradient promotes deuterium permeation.

When deuterium permeates, the radioactive material contained in the surface layer 25 is 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 converted into a nuclide.

Due to the electrolysis and nuclide conversion reaction, the amount of heavy water (electrolyte solution) and the electrolyte (when a salt of radioactive substance is used) in the reservoir 11 is reduced, and the electrolyte concentration fluctuates. The electrolyte solution supply unit 60 adjusts the opening degree of the valve V4, and supplies the electrolyte solution from the electrolyte solution tank 61 to the storage unit 11 so that the electrode 14 maintains a predetermined water level at which the electrode 14 can be immersed in the electrolyte solution.

The heavy water supply unit 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 holds 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 unit 65, the temperature of the electrolyte solution, and the amount of the electrolyte solution supplied to the storage unit 11.

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

When deuterium is generated by the electrolysis of heavy water, oxygen (O ₂ ) is generated. Further, the inert gas (N ₂ or the like) is transported to the storage unit 11 along with the supply of the electrolyte solution. When the inside of the storage unit 11 becomes 1 atm (1 × 10 ⁵ Pa) or more, the check valve 16 is opened and gas is discharged from the inside of the storage unit 11.

(Judgment of reaction end)
<S6> Recovery (extraction) of electrolyte solution
After a predetermined time has elapsed from the start of deuterium permeation, the 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, V24 are closed, the electrolyte solution supply unit 60 is stopped, and the supply of the electrolyte solution is stopped. .. If the heavy water replenishment unit 80 has been activated, the valve V6 is closed and the heavy water replenishment unit 80 is stopped.

By the circulation unit 30, substantially the entire amount of the electrolyte solution is withdrawn from the storage unit 11, and the storage unit 11 is emptied (in a liquid-free state). The extracted electrolyte solution is temporarily stored in the solution storage unit 101.

"Empty (liquid-free state)" means that almost the entire amount of the solution stored in the storage unit 11 has been extracted, but the residual liquid that could not be physically extracted due to the equipment configuration is allowed. do. The electrolyte solution is withdrawn until at least the surface layer 25 is exposed.

By extracting the electrolyte solution from the reservoir 11 and exposing the surface layer 25, the radiation detection loss due to the electrolyte solution can be suppressed. This improves the detection accuracy.

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

After extracting substantially the entire amount of the electrolyte solution, the inside of the reservoir 11 may be dried by a drying means (not shown).

<S7> Radiation dose monitoring The first detector 100 measures the radiation emitted from the structure 13 (radiative material on the surface layer 25). When the radiation amount obtained by the measurement is higher than the first threshold value, the determination unit 110 determines that the reaction is continued. Based on this determination, the control unit 111 returns the electrolyte solution temporarily stored in the solution storage unit 101 to the storage unit and restarts the reaction. That is, the steps <S4> to <S7> are repeated.

When the radiation amount obtained by the measurement drops below the first threshold value, the determination unit 110 determines that the reaction is completed.

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

The power supply 15 applies a negative voltage to the electrode 14 opposite to the step of forming the surface layer 25. The surface layer 25 elutes from the structure 13 into the electrolyte solution and peels off from the structure 13. If the relationship between the current density and the film forming speed (equivalent to the peeling speed) is acquired in advance, it is possible to obtain the time for peeling only the surface layer 25. Therefore, it is possible to control the time when the surface layer 25 is peeled off.

After the lapse of a predetermined time, the power supply 15 stops applying the voltage to the electrode 14. The valve V1 closes and the valve V2 opens. The electrolyte solution containing the elution component in the storage unit 11 is discharged from the storage unit 11 to the outside of the nuclide conversion system 1 through the discharge pipe 41 and the discharge unit 40. The discharged electrolyte solution is recovered.

In the nuclide conversion method of the present embodiment, the steps from the step of forming the surface layer to the step of recovering the surface layer can be repeatedly carried out without exchanging 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 unit 90 and the heavy water replenishment unit 80 are used in combination, but since the cleaning liquid supply unit 90 and the heavy water replenishment unit 80 have the same configuration, only one of them is used in the present embodiment. May be installed.

FIG. 5 shows an energy spectrum diagram in which the radiation dose of the structure 13 including the surface layer 25 containing Cs-137 is monitored. 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 of γ-rays (keV), and the vertical axis is the amount of γ-rays captured.

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

When Cs-137 is converted to non-radioactive nuclides by deuterium permeation, the peak of Cs-137 becomes lower as shown in the graph on the right side of the arrow in FIG. A reaction starting from Cs-137 cannot occur. Therefore, it can be considered that the reaction is completed when the amount of gamma ray trapped drops to the first threshold value.

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

[Second Embodiment]
FIG. 6 is a schematic diagram of the nuclide conversion system 2 according to the present embodiment. FIG. 7 is a flow chart showing the procedure of the nuclide conversion method according to the present embodiment. The description of the configuration common to the first embodiment will be omitted.

The nuclide conversion system according to the present embodiment is different from the first embodiment in that the first detector 103 is arranged in the deuterium low concentration unit 12. In this embodiment, the solution storage unit 101 of the circulation unit 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. The substrate 21 contains a bulk hydrogen storage metal or hydrogen storage alloy. The hydrogen storage metal is palladium (Pd), nickel (Ni) or the like. The hydrogen storage alloy is a palladium alloy, a nickel alloy, or the like.
The intermediate layer 24 and the surface layer 25 are the same as those in the first embodiment.

The first detector 103 is arranged in the deuterium low concentration unit 12. The first detector 103 may face the structure 13 and / or be in close proximity to the structure 13.

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

As the first detector 103 arranged in the deuterium low concentration portion 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 board and head of the measuring instrument can be separated, it is relatively easy to approach the object to be measured. The Geiger counter has no limit on continuous operation time. Geiger counters are cheaper than gamma-ray detectors.

The nuclides that emit β rays are, for example, 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 to 13>, a step of reacting <S14 to 15>, a step of determining the completion of the reaction <S16>, and a step of recovering radioactive substances <S17>. include.

The steps <S11 to 13> for forming the surface layer, the steps <S14 to 15> for reacting, and the step <S17> for recovering the radioactive substance are <S1 to 3>, <S4 to 5>, and <S8> of the first embodiment. > Is the same. The step <S16> for determining the end of the reaction is different from the first embodiment in that the electrolyte solution is not recovered. In the present embodiment, unlike the first embodiment, the electrolyte solution extracted from the storage unit 11 does not need to be temporarily stored in the solution storage unit 101.

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

When the radiation amount obtained by the measurement is higher than the first threshold value, the determination unit 110 determines that the reaction is continued. The control unit 111 continues to permeate deuterium and circulate the electrolyte solution by the circulation unit 30 until it is determined that the reaction is completed. That is, <S14 to 16> is repeated.

When the radiation amount obtained by the measurement drops below the first threshold value, the determination unit 110 determines that the reaction is completed, and proceeds to the step of collecting the <S17> surface layer.

FIG. 8 illustrates a more specific schematic view of the vicinity of the structure. The structure 13 is sandwiched between the sample stage 120 and the sample fixing jig 121. The O-ring 122 attached to the sample stage 120 keeps the storage unit 11 and the deuterium low concentration unit 12 in an airtight manner.

A plurality of through holes 123 are formed in the region 120a overlapping the structure 13 of the sample stage 120. When viewed from the deuterium low concentration portion 12 side, the through hole 123 is completely covered with 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 composed of punching metal, foamed metal, or metal mesh. By forming the through hole 123 in the region 120a, the structure 13 can be supported so that deuterium can permeate. In such a structure, when the structure 13 is thin, the mechanical strength of the structure 13 can be supplemented.

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

As shown in FIG. 8, the β-ray detector detects β-rays on the deuterium low concentration portion 12 side. There is no electrolytic solution in the deuterium low concentration portion 12. Further, during the reaction step, the inside of the deuterium low concentration portion 12 is evacuated. Therefore, there is little radiation loss.

In the present embodiment, by arranging the first detector 103 in the deuterium low concentration unit 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 the present embodiment. FIG. 10 is a flow chart showing the procedure of the nuclide conversion method according to the present embodiment.

The nuclide conversion system 3 according to the present embodiment is different from the first embodiment in that the second detector 104 is arranged. The description of the configuration common to the first embodiment will be omitted.

The second detector 104 is a device capable of detecting the radiation emitted from the solution stored in the solution storage unit 101. When the radioactive substance contained in the surface layer 25 has a nuclide that emits γ-rays, a γ-ray detector such as a Ge semiconductor detector is used as the second detector 104. When the radioactive material contained in the surface layer 25 has a nuclide that emits a neutron beam, a neutron detector is used as the second detector 104. The second detector 104 may be a model of the same type as the first detector 100, or a model of a different type.

The second detector 104 is arranged so as to detect the radiation emitted from the solution in the solution storage unit 101. The relative position between the second detector 104 and the solution storage unit 101 is fixed.

The second detector 104 may be placed in close proximity to the solution storage section 101. The closer the distance from the radiation source (radioactive substance), the larger the amount of radiation that can be detected, so the detection accuracy can be improved.

The second detector 104 may be installed at a plurality of places. As a result, the detection accuracy is improved.

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

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

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

The steps <S21 to 23> for forming the surface layer, the steps <S24 to 25> for reacting, and the step <S28> for recovering the radioactive substance are <S1 to 3>, <S4 to 5>, and <S8> of the first embodiment. > Is the same. The steps <S26 to 27> for determining the end of the reaction are different from the first embodiment in that the determination using the second detector is included.

(Judgment of reaction end)
<S26> Recovery of Electrolyte Solution In the present embodiment, as in the case of recovery of the <S6> electrolyte solution of the first embodiment, after deuterium is permeated for a predetermined time, the electrolyte solution is withdrawn from the storage section 11 and the storage section is used. Empty the inside of 11. The extracted electrolyte solution is temporarily stored in the solution storage unit 101.

It is even more preferable to dry the inside of the reservoir 11 by a drying means (not shown) after extracting substantially the entire amount of the electrolyte solution.

<S27> Radiation dose monitoring Radiation dose monitoring is performed by both the first detector 100 and the second detector 104. The monitoring by the first detector 100 is the same as that of the first embodiment.

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

When the first radiation amount obtained by the measurement of the first detector 100 is higher than the first threshold value and the second radiation amount detected by the second detector 104 is less than the second threshold value, the determination unit 110 determines. It is determined that the reaction is continued. The control unit 111 returns the electrolyte solution temporarily stored in the solution storage unit 101 to the storage unit, and restarts the reaction in the same manner as in the first embodiment. That is, the steps <S24> to <S27> are repeated.

When the first radiation dose drops below the first threshold value, when the second radiation dose rises above the second threshold value, and when the first radiation dose is below the first threshold value and the second radiation dose is the first. If it is 2 threshold values or more, the determination unit 110 determines that the reaction is completed, and proceeds to the step of collecting the <S28> 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 steps <S24 to 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 of the second detector 104 reflects the amount of radioactive substances eluted in the electrolyte solution.

Radioactive substances have different solubilities in electrolyte solutions depending on the type. For example, alkali metals are easily dissolved, and Co and the like are difficult to elute. Further, the radioactive substance on the surface of the surface layer 25 is more likely to elute than the case where it is inside the surface layer.

When the first radiation dose exceeds the first threshold value, a large amount of radioactive material as a material for the conversion reaction is present in the structure 13 (surface layer 25), so that the reaction may be continued as it is. When the first radiation dose exceeds the first threshold value, the amount of radioactive substances eluted in the electrolyte solution is small, so that the radiation dose does not exceed the second threshold value.

When the first radiation dose is equal to or less than the first threshold value, the amount of radioactive substances present in the structure 13 (surface layer 25) is small, so that the reaction efficiency is lowered. When the second radiation dose is equal to or higher than the second threshold value, many radioactive substances are eluted in the electrolyte solution. Therefore, the amount of the radioactive substance present in the structure 13 is small, and the reaction efficiency is lowered.

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

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

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

The reactor 10 and the circulation unit 30 are closed spaces, and radioactive substances (Cs) do not leak to the outside. Radioactive substances (Cs) have a long half-life. Since the reaction step is about several tens to several hundred hours, it is unlikely that the radiation dose will fluctuate as shown in FIG. 11 due to natural decay. Therefore, in FIG. 11, it is considered that the radioactive material (Cs) was converted into 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) in the second detector becomes slightly larger during the conversion reaction, and further increases at the end of the conversion reaction.

In FIG. 12, even if the radiation dose on the surface of the structure is low, when the radiation dose of the electrolyte solution is high, the conversion reaction does not occur, but the radioactive substance is simply eluted from the surface layer. Suggest that there is.

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

The nuclide conversion reaction of the present disclosure occurs by permeating deuterium through a radioactive substance in the crystal lattice of a hydrogen storage metal or a hydrogen storage alloy. The conversion reaction does not occur in radioactive materials away from the structure (surface layer). Therefore, as the amount of radioactive material eluted in the electrolyte solution increases, the conversion reaction efficiency of the radioactive material decreases.

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

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

In this embodiment, the arrangement of the second detector 104 is not limited to the vicinity of the solution storage unit 101. The second detector 104 may be arranged so that the radiation of the circulating water flowing through the circulation unit 30 can be measured. The relative position between the second detector 104 and the circulation unit 30 (the point to be measured) is fixed. The second detector 104 may be arranged in the vicinity of the extraction pipe 31 and the heat exchanger 32, for example. The wall surface (measurement surface) of the measurement target portion is made of a material capable of transmitting the same type of radiation as the radiation emitted by the radioactive substance on the surface layer 25.

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

The steps <S31 to 33> for forming the surface layer, the steps <S34 to 35> for reacting, and the step <S37> for recovering the radioactive substance are <S1 to 3>, <S4 to 5>, and <S8> of the first embodiment. > Is the same.
The step <S36> for determining the end of the reaction is different from the first embodiment in that the electrolyte solution is not recovered and the determination using the second detector is used. In the present embodiment, unlike the first embodiment, the electrolyte solution extracted from the storage unit 11 does not need to be temporarily stored in the solution storage unit 101.

(Determination of reaction end: S36)
In the present embodiment, the end 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 the radiation emitted from the structure 13 with the electrode 14 immersed in the electrolyte solution.

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

When the first radiation amount obtained by the measurement of the first detector 100 is higher than the first threshold value and the second radiation amount detected by the second detector 104 is less than the second threshold value, the determination unit 110 determines. It is determined that the reaction is continued. The control unit 111 continues to permeate deuterium and circulate the electrolyte solution by the circulation unit 30 until it is determined that the reaction is completed. That is, <S34 to 36> is repeated.

When the first radiation dose drops below the first threshold value, when the second radiation dose rises above the second threshold value, and when the first radiation dose is below the first threshold value and the second radiation dose is the first. If it is 2 threshold values or more, the determination unit 110 determines that the reaction is completed, and proceeds to the step of collecting the <S37> surface layer.

The first threshold value can be set, for example, to be a value at which the amount of radiation captured per hour is 50% of the initial value, or 1000 counts or less per hour. The first threshold is preferably 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 the present embodiment, the radiation dose of the structure 13 is measured in a state where the electrolyte solution is stored in the storage unit 11. Since a part of the radioactive substance on the surface layer 25 elutes into the electrolyte solution, it is advisable to consider the detection efficiency of the first detector and the second detector. For example, a value obtained by obtaining 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, the amount of radioactive substance eluted into the electrolyte solution 80%) is set as the second threshold value. You may.

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

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

In the present embodiment, the progress of the reaction can be confirmed in real time without stopping the reaction.

In the first to fourth embodiments, the internal standard substance may be arranged in the field of view of the first detector (100, 103) and the second detector (104). The internal standard substance may be arranged, for example, in the vicinity of the surface layer 25, the wall surface of the reaction device 10, and the like. When arranging in the vicinity of 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 when the reaction device 10 is arranged on the wall surface.

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

By arranging the internal standard substance, quantitative calculation becomes possible. By arranging an internal standard substance, it is possible to respond to changes in measurement sensitivity.

In the first to fourth embodiments, a calibration curve may be prepared in advance using an external standard substance for the radiation dose of the structure 13 arranged in the reactor.

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

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

<Additional Notes>
The nuclide conversion system and the nuclide conversion method described in the embodiments described above are grasped as follows, for example.

The nuclear species conversion system (1) according to the present disclosure includes a structure (13) through which heavy hydrogen can permeate, a storage portion (11) separated by the structure and forming a closed space, and a heavy hydrogen low concentration portion (12), respectively. An electrode (14) housed in the storage unit and arranged to face the surface of the structure on the storage unit side, a reaction device (10) having a power source (15) connected to the electrode, and the storage unit. An electrolyte solution supply unit (60) connected to the unit and supplying a heavy aqueous solution containing an electrolyte to the storage unit, and a solution connected to the storage unit to extract a solution from the storage unit, and the extracted solution to the storage unit. The structure is provided with a circulating portion (30) to be returned and a first detector (100) for measuring the radiation dose of the structure, and the structure is radioactive with a hydrogen storage metal or a hydrogen storage alloy on the storage portion side. It has a surface layer (25) containing a substance, and the circulation unit has a solution storage unit (101) for storing a solution extracted from the storage unit.

According to the nuclide conversion system according to the above disclosure, the heavy aqueous solution can be electrolyzed by immersing the electrode in a heavy aqueous solution (electrolyte solution) containing an electrolyte. Heavy water is generated by electrolyzing a heavy aqueous solution containing an electrolyte in the reservoir. As a result, the deuterium concentration in the reservoir becomes relatively high, and a deuterium concentration gradient is formed in the thickness direction of the structure (direction from the reservoir side toward the deuterium low concentration portion). Deuterium flows from the higher concentration to the lower concentration, and as a result, deuterium is permeated through the structure. The heavy aqueous solution does not permeate the structure.

When deuterium is permeated through the structure, a reaction occurs in which the radioactive substances contained in the surface layer are converted into another nuclide. This makes it possible to convert radioactive substances 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 with the first detector, the progress of the reaction can be determined.

In the nuclide conversion system disclosed above, the solution extracted from the reservoir can be temporarily placed in the solution reservoir. As a result, the inside of the reservoir can be made solution-free.

When deuterium is permeated, the structure is immersed in a heavy aqueous solution containing an electrolyte, but some of the radioactive substances may elute into the heavy aqueous solution.

By making the inside of the reservoir solution-free and then measuring the radiation dose of the structure, the influence of radioactive substances eluted in the solution can be eliminated. This makes it possible to more accurately grasp the radiation dose emitted from the radioactive substance contained in the surface layer.

In one aspect of the disclosure, the radioactive material has a nuclide that emits γ-rays, and the first detector may be a γ-ray detector.

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

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

By arranging a shielding material around the reactor, the influence of disturbance factors can be reduced. Disturbance factors are cosmic rays and other sources of radiation. Other radioactive sources are, for example, a heavy aqueous solution containing an electrolyte extracted from the reservoir and stored in the solution reservoir, an electrodeposition solution, and the like.

The nuclear species conversion system (2) according to the present disclosure is housed in a structure that allows heavy hydrogen to permeate, a storage portion that is separated by the structure and forms a closed space, a heavy hydrogen low concentration portion, and the storage portion, respectively. An electrode arranged facing the surface of the structure on the reservoir side, a reaction device having a power source connected to the electrode, and an electrolyte connected to the reservoir and supplying a heavy aqueous solution containing an electrolyte to the reservoir. A solution supply unit, a circulation unit connected to the storage unit, extracting a solution from the storage unit, and returning the extracted solution to the storage unit, and a circulation unit connected to the heavy hydrogen low concentration unit, and the radiation amount of the structure. The structure comprises a first detector (103) for measuring the above, and the structure has a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance on the storage portion side.

The structure does not allow the heavy aqueous solution contained in the storage portion to permeate to the deuterium low concentration portion side. That is, there is no heavy aqueous solution containing an electrolyte in the low concentration portion of deuterium.
By arranging it in the deuterium low concentration part, the first detector can be brought closer to the structure. Further, if it is inside the deuterium low concentration portion, there is no barrier separating the first detector from the structure. Therefore, the radiation loss is small and the detection accuracy is high.
When the exhaust means and the exhaust path are connected to the deuterium low concentration portion as a low concentration device, the deuterium low concentration portion can be evacuated. This reduces radiation loss.

By arranging the first detector in the deuterium low concentration portion, it is not necessary to extract the heavy aqueous solution containing the electrolyte, so that continuous monitoring becomes possible. This makes it possible to determine the degree of progress of the reaction without stopping the reaction (while operating continuously).

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

Nuclides that emit β-rays are easier to shield and handle than nuclides that emit γ-rays.
The β-ray detector is small and relatively easy to approach the object to be measured. The β-ray detector has no limit on the continuous operation time and is cheaper than the γ-ray detector. Therefore, it is easy to place it in the deuterium low concentration part.

In one aspect of the above disclosure, the nuclide conversion system may further include a determination unit (110) for determining that the reaction is completed when the radiation dose measured by the first detector drops below the first threshold value. ..

By setting the first threshold value, the criterion for determining the end of the reaction becomes clear. The first threshold value can be set, for example, to be a value at which the amount of radiation captured per hour is 50% of the initial value, or 1000 counts or less per hour. The first threshold is preferably 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 reservoir.

As mentioned above, the solution extracted from the reservoir may contain radioactive material eluted from the surface layer. By providing a second detector for measuring the radiation dose of the solution stored in the solution storage unit or the radiation dose of the solution extracted from the storage unit, the amount of the eluted radioactive substance can be known.

In one aspect of the above disclosure, the second detector (104) may be fixed in a position relative to the solution storage unit so that the radiation dose of the solution stored in the solution storage unit can be measured.

The solution extracted from the reservoir is stored in the solution reservoir. Therefore, by measuring the radiation dose in the solution storage unit, a large amount of radiation can be detected. As a result, the measurement accuracy is improved.

In one aspect of the above disclosure, the nuclide conversion system further comprises a determination unit (110) that determines that the reaction is completed when the second radiation dose obtained by the measurement of the second detector rises above the second threshold value. 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 small. As the amount of radioactive substances contained in the surface layer decreases, the reaction efficiency also decreases. By adding the second threshold value to the criterion for determining the end of the reaction, the degree of progress of the reaction can be determined more accurately.

In one aspect of the disclosure, the first detector may face the structure.

Radioactive materials are dispersed in the surface layer. By facing the first detector to the structure, the deviation of the distance between each dispersed radioactive substance and the first detector can be reduced. As a result, the measurement accuracy of the radiation emitted from the radioactive substance is improved.

In one aspect of the above disclosure, the nuclear species conversion system is connected to the reservoir and supplies an electrodeposition solution containing the hydrogen storage metal or the hydrogen storage alloy and the radioactive substance to the reservoir. A unit (50) and a discharge unit (40) for discharging the solution extracted from the storage unit to the outside of the system may be further provided.

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

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

An internal standard substance is a radioactive substance whose radioactivity is known. The field of view of the first detector is at least in the reaction device, for example, the inner wall of the reservoir and the like. The internal standard material 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 the 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 by using the electrodeposition liquid supply unit. The components of the electrodeposited liquid remaining in the reservoir may inhibit the nuclide conversion reaction. By removing the electrodeposited liquid remaining in the reservoir, the effect of contamination can be reduced.

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

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

The nuclear species conversion method according to the present disclosure is a structure in which heavy hydrogen can permeate, a storage portion separated by the structure and forming a closed space, a heavy hydrogen low concentration portion, and the structure housed in the storage portion. A nuclear species conversion method using an electrode arranged to face the surface on the reservoir side and a reactor having a power source connected to the electrode, and is a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance. The structure is arranged toward the reservoir 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 apply a voltage to the electrode and the said. A voltage difference is generated between the structure and the heavy hydrogen solution containing the electrolyte in the space between the electrode and the structure, and the storage of the structure is stored by a concentration gradient for a predetermined time. The deuterium is permeated from the part side toward the decubitus low concentration part side, the permeation of the heavy hydrogen is stopped, the solution is withdrawn from the storage part, the inside of the storage part is emptied, and then the first detector is used. When the first radiation amount obtained by the measurement of the first detector drops below the first threshold value, the reaction is terminated and the first radiation amount is reduced. When it is higher than the first threshold value, the extracted solution is returned to the reservoir and the permeation of the heavy hydrogen is restarted.

In one aspect of the disclosure, the radioactive material has a nuclide that emits γ-rays, and the first detector may be a γ-ray detector.

In one aspect of the above disclosure, it is preferable to surround the reaction device with a shielding material.

The nuclear species conversion method according to the present disclosure is a structure capable of permeating heavy hydrogen, a storage portion separated by the structure and forming a closed space, a heavy hydrogen low concentration portion, and the structure housed in the storage portion. A nuclear species conversion method using an electrode arranged to face the surface on the reservoir side and a reactor having a power source connected to the electrode, and is a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance. The structure is arranged toward the storage portion, the first detector for measuring the radiation amount of the structure is arranged in the heavy hydrogen low concentration portion, and the heavy aqueous solution containing the electrolyte is placed in the storage portion. A voltage is applied to the electrode that has been supplied and immersed in a heavy aqueous solution containing the electrolyte to generate a voltage difference between the electrode and the structure, and the space between the electrode and the structure is the same. The heavy hydrogen is generated from a heavy aqueous solution containing an electrolyte, and the heavy hydrogen is permeated from the storage portion side of the structure toward the heavy hydrogen low concentration portion side by a concentration gradient, and the heavy hydrogen is permeated while being permeated. The first radiation amount of the structure is measured by the first detector, and the reaction is terminated when the first radiation amount obtained by the measurement of the first detector drops below the first threshold value.

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

In one aspect of the above disclosure, the second radiation dose of the electrolyte solution extracted from the reservoir is measured by the second detector, and when the second radiation dose rises above the second threshold value, the reaction termination is terminated. You may.

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

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

Claims (21)

A structure that allows deuterium to permeate, a storage section that is separated by the structure and forms a closed space, and a deuterium low concentration section, which are housed in the storage section and are arranged to face the surface of the structure on the storage section side. An electrode to be used, and a reactor having a power source connected to the electrode,
An electrolyte solution supply unit connected to the storage unit and supplying a heavy aqueous solution containing an electrolyte to the storage unit,
A circulation unit that is connected to the storage unit, extracts a solution from the storage unit, and returns the extracted solution to the storage unit.
The first detector that measures the radiation dose of the structure,
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 portion side.
The circulation unit is a nuclide conversion system having a solution storage unit for storing a solution extracted from the storage unit. The radioactive material has a nuclide that emits gamma rays and has a nuclide.
The nuclide conversion system according to claim 1, wherein the first detector is a gamma ray detector. The nuclide conversion system according to claim 1 or 2, wherein the reactor is surrounded by a shielding material. A structure that allows deuterium to permeate, a storage section that is separated by the structure and forms a closed space, and a deuterium low concentration section, which are housed in the storage section and are arranged to face the surface of the structure on the storage section side. An electrode to be used, and a reactor having a power source connected to the electrode,
An electrolyte solution supply unit connected to the storage unit and supplying a heavy aqueous solution containing an electrolyte to the storage unit,
A circulation unit that is connected to the storage unit, extracts a solution from the storage unit, and returns the extracted solution to the storage unit.
A first detector housed in the deuterium low concentration portion and measuring the radiation dose of the structure,
Equipped with
The structure is a nuclide conversion system having a surface layer containing a hydrogen storage metal or a hydrogen storage alloy and a radioactive substance on the storage portion side. The radioactive material has a nuclide that emits β rays and has a nuclide.
The nuclide conversion system according to claim 4, wherein the first detector is a β-ray detector. The nuclide conversion system according to any one of claims 1 to 5, further comprising a determination unit for determining that the reaction is completed when the first radiation dose obtained by the measurement of the first detector drops below the first threshold value. .. The nuclide conversion system according to any one of claims 1 to 6, further comprising a second detector for measuring the radiation dose of the solution extracted from the reservoir. The nuclide conversion system according to claim 7, wherein the second detector can measure the radiation dose of the solution stored in the solution storage unit, and the position relative to the solution storage unit is fixed. The nuclide conversion system according to claim 7 or 8, further comprising a determination unit for determining that the reaction is completed when the second radiation dose obtained by the measurement of the second detector rises above the second threshold value.
The nuclide conversion system according to any one of claims 1 to 9, wherein the first detector 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 reservoir to the outside of the system, and a discharge section.
The nuclide conversion system according to any one of claims 1 to 10. The nuclide conversion system according to any one of claims 1 to 11, wherein the internal standard substance is arranged in the field of view of the first detector. The nuclide conversion system according to claim 12, further comprising a cleaning liquid supply unit connected to the storage unit and supplying the 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.
In the intermediate layer, 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 are laminated. It is a composition
The nuclide conversion system according to any one of claims 1 to 13, wherein the surface layer is above the intermediate layer. A structure that allows deuterium to permeate, a storage section that is separated by the structure and forms a closed space, and a deuterium low concentration section, which are housed in the storage section and are arranged to face the surface of the structure on the storage section side. It is a nuclide conversion method using a reaction device having an electrode to be formed and a power source connected to the electrode.
The structure is arranged with the surface layer containing the hydrogen storage metal or the hydrogen storage alloy and the radioactive substance facing the storage portion side.
A heavy aqueous solution containing an electrolyte is supplied to the reservoir to supply the reservoir.
A voltage is applied to the electrode immersed in a heavy aqueous solution containing the electrolyte to generate a voltage difference between the electrode and the structure, and the electrolyte is contained in the space between the electrode and the structure. The deuterium is generated from the heavy aqueous solution, and the deuterium is permeated from the storage portion side of the structure toward the deuterium low concentration portion side by a concentration gradient for a predetermined time.
After stopping the permeation of the deuterium, extracting the solution from the reservoir and emptying the reservoir, the radiation dose of the structure is measured by the first detector, and the result is obtained by the measurement of the first detector. When the first radiation dose obtained drops below the first threshold value, the reaction is terminated and the reaction is terminated.
A nuclide conversion method in which when the first radiation dose is higher than the first threshold value, the extracted solution is returned to the reservoir and the permeation of deuterium is restarted. The radioactive material has a nuclide that emits gamma rays and has a nuclide.
The nuclide conversion method according to claim 15, wherein the first detector is a gamma ray detector. The nuclide conversion method according to claim 15 or 16, wherein the reaction apparatus is surrounded by a shielding material. A structure that allows deuterium to permeate, a storage section that is separated by the structure and forms a closed space, and a deuterium low concentration section, which are housed in the storage section and are arranged to face the surface of the structure on the storage section side. It is a nuclide conversion method using a reaction device having an electrode to be formed and a power source connected to the electrode.
The structure is arranged with the surface layer containing the hydrogen storage metal or the hydrogen storage alloy and the radioactive substance facing the storage portion side.
A first detector for measuring the radiation dose of the structure is placed in the deuterium low concentration portion.
A heavy aqueous solution containing an electrolyte is supplied to the reservoir to supply the reservoir.
A voltage is applied to the electrode immersed in a heavy aqueous solution containing the electrolyte to generate a voltage difference between the electrode and the structure, and the electrolyte is contained in the space between the electrode and the structure. The deuterium is generated from the heavy aqueous solution, and the deuterium is permeated from the storage portion side of the structure toward the deuterium low concentration portion side by a concentration gradient.
The first radiation dose of the structure was measured by the first detector while allowing the deuterium to permeate.
A nuclide conversion method for terminating the reaction when the first radiation dose obtained by the measurement of the first detector drops below the first threshold value. The radioactive material has a nuclide that emits β rays and has a nuclide.
The nuclide conversion method according to claim 18, wherein the first detector is a β-ray detector. The second radiation dose of the electrolyte solution extracted from the reservoir was measured by the second detector, and
The nuclide conversion method according to any one of claims 15 to 19, wherein the reaction termination is terminated when the second radiation dose rises above the second threshold value. The nuclide conversion method according to any one of claims 15 to 20, wherein an internal standard substance is arranged in the field of view of the first detector.

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