Radionuclide production system and radionuclide production method

Abstract

To provide a radioactive nuclide production system and a radioactive nuclide production method capable of safely, efficiently producing Ac-225.SOLUTION: A radioactive nuclide production system S relating to the invention includes an electron accelerator 1 for emitting an electron beam 3, a metal target unit 2 for generating a bremsstrahlung radiation 4 by the emitted electron beam 3, a Ra-226 solution target unit 5 that is irradiated with the generated bremsstrahlung radiation 4, can accommodate two or more kinds of phase-separating solvent containing a Ra-226 raw material, and produces Ac-225 from the Ra-226 raw material by being irradiated with the bremsstrahlung radiation 4, a solvent extraction unit 6 for extracting a first solvent 5b containing more Ac-225 among the two or more kinds of phase-separating solvent, a solvent addition unit 8 for adding the solvent of an amount reduced by consumption to the Ra-226 solution target unit 5, and a radon processing unit 7 for processing radon gas generated in the Ra-226 solution target unit 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radionuclide production system and a radionuclide production method. [Background technology]

[0002] One of the cancer treatment methods is RI (Radio Isotope) internal therapy. RI internal therapy is a treatment method in which a drug incorporating a radionuclide is administered to the human body, and the drug selectively accumulates in cancer cells, allowing the cancer to be directly irradiated with radiation and kill the cancer cells. Conventional RI internal therapy uses a beta-ray source, such as iodine-131 (I-131, 131 Thyroid cancer treatment using RI has been carried out since the 1940s. In recent years, RI internal therapy using α-ray sources, which have a shorter range and higher linear energy transfer than β-ray sources, has attracted attention due to its high therapeutic effectiveness.

[0003] Actinium-225 (Ac-225, 225 Ac-225 is one of the therapeutic alpha nuclides, and the development of drugs using it is underway. Currently, the production of Ac-225 is being carried out by thorium-229 (Th-229, 229 This is done by the decay of Th). Because Th-229 does not exist naturally, the clinically available radionuclide Ac-225 must be supplied from one of the few Th-229 storage facilities in the world, and the supply of Ac-225 is insufficient. As treatment using alpha nuclides becomes more widespread in the future, it is predicted that the supply of Ac-225 will become significantly short. Therefore, there is a need for active production of Ac-225 using accelerators.

[0004] As a method for producing Ac-225 using an accelerator, naturally occurring radium-226 (Ra-226, 226One method uses a cyclotron that utilizes the Ra-226(p,2n)Ac-225 reaction using Ra as a raw material (see, for example, Non-Patent Document 1). However, this manufacturing method has problems such as: (1) the range of accelerated protons in the Ra-226 target is short, making mass production impossible even if the Ra-226 target is made thick; and (2) most of the energy of the accelerated protons is lost in the target, making it difficult to remove heat from the target, making it impossible to increase the current value or energy for mass production.

[0005] Another accelerator-based manufacturing method is to use naturally occurring Ra-226 as a raw material and utilize the Ra-226(γ,n)Ra-225→Ac-225 reaction with an electron beam accelerator. Electron beam accelerators can be made smaller than proton or heavy particle accelerators at the same acceleration energy. Furthermore, unlike particle beams such as protons, electron beam accelerators have little attenuation within the target, meaning that even if the raw material Ra-226 is increased, the production volume does not decrease, making them suitable for mass production.

[0006] In both of the above manufacturing methods, a step is required to separate and purify Ac-225 from the irradiated Ra-226 target, recover the raw Ra-226, and reuse it as an irradiation target. Although the raw Ra-226 exists in nature, it is not easy to obtain, so reuse is a prerequisite. Because Ra-226 has a long half-life of 1600 years, it can be used almost indefinitely.

[0007] Furthermore, a method for producing, separating and purifying Ac-225 using an accelerator is described, for example, in Patent Document 1. Patent Document 1 describes a radiation irradiating device provided on a support. 226 From Ra target (Ra-226 raw material) 225 As a method for purifying Ac (Ac-225), a specific extractant was used. 226 A method is described which involves elution of the Ra target and extraction chromatography. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2009-527731 [Non-patent literature]

[0009] [Non-Patent Document 1] C. Apostolidis, et al., Appl Radiat Isotope, (2005) 62, p383-387 Summary of the Invention [Problem to be solved by the invention]

[0010] The technology described in Patent Document 1 makes it possible to extract Ac-225 from solid Ra-226 raw materials using dissolution and extraction chromatography. However, as with the technology described in Patent Document 1, the process of extracting a sample from a solid target by dissolution, passing the sample through an extraction chromatography resin, washing, and eluting it is cumbersome and inefficient. In addition, the Ra-226 raw material produces the radioactive gas radon as a daughter nuclide, and this requires operation in a closed system to control this, which is not easy to operate (safe).

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radionuclide production system and a radionuclide production method that can produce Ac-225 simply, safely, and efficiently. [Means for solving the problem]

[0012] The radionuclide production system according to the present invention, which has solved the above-mentioned problems, comprises an electron accelerator that irradiates an electron beam; a metal target section that generates bremsstrahlung radiation by the irradiated electron beam; a Ra-226 solution target section that is irradiated with the generated bremsstrahlung radiation and can accommodate two or more solvents that contain a Ra-226 raw material and undergo phase separation, and that produces Ac-225 from the Ra-226 raw material by irradiating the bremsstrahlung radiation; a solvent extraction section that extracts a first solvent that contains a large amount of Ac-225 from the two or more solvents that undergo phase separation; a solvent addition section that adds the solvent to the Ra-226 solution target section in an amount equivalent to the decrease in the amount of solvent consumed; and a radon treatment section that treats gaseous radon generated in the Ra-226 solution target section. [Effects of the Invention]

[0013] The radionuclide production system and radionuclide production method according to the present invention can produce Ac-225 simply, safely and efficiently. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram illustrating the configuration of a radionuclide production system according to one embodiment of the present invention. [Figure 2] 1 is a schematic diagram illustrating the configuration of a radionuclide production system according to one embodiment of the present invention. [Figure 3] 1 is a schematic diagram illustrating the configuration of a radionuclide production system according to one embodiment of the present invention. [Figure 4] 1 is a schematic diagram illustrating the configuration of a radionuclide production system according to one embodiment of the present invention. [Figure 5] 1 is a flow chart illustrating the details of a radionuclide production method according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, a radionuclide production system and a radionuclide production method according to one embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the description of the embodiment, substantially identical or similar components are denoted by the same reference numerals, and redundant descriptions may be omitted.

[0016] (Radionuclide Production System) 1 to 3 are schematic diagrams illustrating the configuration of a radionuclide production system S according to one embodiment of the present invention. FIG. 1 shows the state of the solvent in the Ra-226 solution target section 5 before phase separation, while FIGS. 2 and 3 show the state of the solvent in the Ra-226 solution target section 5 after phase separation. In FIGS. 2 and 3, the positions of the phase-separated first solvent 5b and second solvent 5c are reversed. Accordingly, the position of the solvent extraction section 6 has also been changed.

[0017] 1 to 3, the radionuclide production system S according to this embodiment includes an electron accelerator 1, a metal target section 2, a Ra-226 solution target section 5, a solvent extraction section 6, a radon treatment section 7, and a solvent addition section 8. The electron accelerator 1, the metal target section 2, and the Ra-226 solution target section 5 are arranged on the irradiation line (path) of the electron beam 3 (and bremsstrahlung radiation 4). The solvent extraction section 6, the radon treatment section 7, and the solvent addition section 8 are provided in the Ra-226 solution target section 5.

[0018] The electron accelerator 1 irradiates the metal target portion 2 with an electron beam 3 . The metal target portion 2 generates bremsstrahlung radiation 4 by the electron beam 3 irradiated thereon. The Ra-226 solution target section 5 is irradiated with the generated bremsstrahlung radiation 4. The Ra-226 solution target section 5 also contains two or more solvents that undergo phase separation. These solvents contain Ra-226 raw materials. The Ra-226 solution target section 5 produces Ac-225 from the Ra-226 raw materials by irradiating the Ra-226 raw materials contained in the solvent with bremsstrahlung radiation 4. The solvent extraction section 6 extracts the first solvent 5b, which contains a large amount of the produced Ac-225, from the two or more solvents that undergo phase separation. The radon treatment unit 7 treats gaseous radon generated in the Ra-226 solution target unit 5. The solvent adding section 8 adds the solvent to the Ra-226 solution target section 5 in an amount equivalent to the amount of solvent consumed.

[0019] As shown in the above configuration, the radionuclide production system S generates bremsstrahlung radiation 4 by irradiating a metal target portion 2, which is a target for generating bremsstrahlung radiation, with electrons accelerated by an electron accelerator 1. In this embodiment, the generated bremsstrahlung radiation 4 is irradiated onto a Ra-226 raw material to produce Ac-225.

[0020] The production of Ac-225 from Ra-226 raw material is explained. First, a solution of radionuclide production material containing a large amount of Ra-226 material is irradiated with bremsstrahlung radiation 4, and Ra-225 is produced by the (γ,n) reaction, in which one neutron is generated by the irradiation of one bremsstrahlung radiation 4 (Ra-226(γ,n)Ra-225). Unlike particle beams such as protons, bremsstrahlung radiation 4 has high penetrating power, so it is not attenuated much in the solvent and can be irradiated with sufficient intensity.

[0021] The resulting Ra-225 becomes its progeny, Ac-225, with a half-life of 14.8 days. Ac-225 then becomes its progeny, francium-221 (Fr-221), with a half-life of 10.0 days. Fr-221 then becomes astatine-217 (At-217) with a half-life of 4.9 minutes, and At-217 then becomes bismuth-213 (Bi-213) with a half-life of 32 milliseconds. While Ac-225 and its progeny are effective in treatment, Ra-226 and Ra-225 are unnecessary nuclides for treatment because they cause unnecessary radiation exposure, and therefore require separation and purification from Ac-225. Furthermore, Ra-226, a raw material used in radionuclide production, is valuable and therefore must be recovered and reused.

[0022] Furthermore, Ra-226 undergoes alpha decay with a half-life of 1600 years, producing the daughter nuclide radon-222 (Rn-222). Rn-222 is a gaseous radioactive nuclide that readily disperses in the environment. It decays with a half-life of 3.8 days to form metallic nuclides (polonium-218 (Po-218) → lead-214 (Pb-214) →...), which deposit everywhere. Because Rn-222's progeny nuclides, such as Pb-214 and bismuth-214 (Bi-214), emit large amounts of radiation, gases containing Rn-222 must be managed for radiation safety reasons. Therefore, systems handling Ra-226 raw materials must be closed, and Rn-222 collection and capture devices must be installed in the exhaust path. Because Rn-222 is a rare gas and difficult to collect chemically, physical adsorption with cooled activated carbon is one method of collection. In addition to Rn, hydrogen and oxygen are produced when water in the solvent undergoes radiolysis due to bremsstrahlung radiation. 4 Also, alpha rays emitted from the Ra-226 raw material and its progeny nuclides cause radiolysis of water, producing hydrogen and oxygen.

[0023] Returning to FIGS. 1 to 3, the radionuclide production system S according to this embodiment irradiates a metal target 2, which is a target for generating bremsstrahlung, with an electron beam 3 accelerated by an electron accelerator 1 to generate bremsstrahlung radiation 4, which is then irradiated onto a Ra-226 solution target 5 containing a Ra-226 raw material. Examples of materials for the metal target 2 include heavy metals such as tungsten, platinum, and tantalum, iron, iron alloys, aluminum, aluminum alloys, copper, and copper alloys. The container for the Ra-226 solution target 5 may be made of metal, glass, or resin. When the Ra-226 solution target 5 is made of metal, it can also serve as the metal target 2.

[0024] As described above, the solution target 5a contained in the Ra-226 solution target section 5 is composed of at least two phase-separating solvents. Examples of these solvents include a first solvent 5b, which is an organic solvent such as benzene, chloroform, an alkane, or dodecane, and a second solvent 5c, which is an aqueous solution or an acid solution. That is, the first solvent 5b is an organic solvent (nonpolar solvent), and the second solvent 5c is a polar solvent. When Ac and Ra exist in ionic form, an extractant is used to capture one of the ions and improve their solubility in the organic phase (first solvent 5b). Examples of extractants that selectively capture Ac-225 and do not bind to Ra-226 include N,N,N',N'-tetraoctyldiglycolamide (TODGA) and bis(2-ethylhexyl)phosphate (HDEHP). Ac-225 selectively bound to these extractants becomes nonpolar and more soluble in the organic solvent, the first solvent 5b.

[0025] Since many organic solvents have a lower specific gravity than water, as shown in Figure 2, the mixture is separated into two phases: an upper phase containing a large amount of Ac-225 (first solvent 5b, an organic solvent) and a lower phase containing a large amount of Ra-226 raw material (second solvent 5c, a polar solvent). In contrast, when an organic solvent with a higher specific gravity than water is used, as shown in Figure 3, vertical separation occurs into two phases: a lower phase rich in Ac-225 (organic first solvent 5b) and an upper phase rich in Ra-226 (polar second solvent 5c). In the embodiment shown in Figure 3, the amount of Rn produced in the upper Ra-226-rich second solvent 5c is reduced and mixed into the lower Ac-225-rich first solvent 5b. This reduces the amount of Rn mixed into the lower first solvent 5b. This allows for safer purification of Ac-225 after extraction by the solvent extraction unit 6.

[0026] The first solvent 5b containing a large amount of Ac-225 and the second solvent 5c containing a large amount of Ra-226 raw material may be arranged in either hierarchical relationship, but the solvent extraction section 6 is provided at the position of the first solvent 5b containing a large amount of Ac-225, as shown in Figures 2 and 3. Specifically, when the first solvent 5b containing a large amount of Ac-225 is on top, the solvent extraction section 6 is provided at the top of the side wall of the Ra-226 solution target section 5, as shown in Figure 2. On the other hand, when the first solvent 5b containing a large amount of Ac-225 is on the bottom, the solvent extraction section 6 is provided at the bottom of the Ra-226 solution target section 5, as shown in Figure 3.

[0027] Furthermore, when the first solvent 5b, which contains a large amount of Ac-225, is on top, the gaseous Rn generated in the second solvent 5c, which contains a large amount of Ra-226 raw material, rises and becomes mixed into the first solvent 5b, which contains a large amount of Ac-225. Rn is a nonpolar rare gas, and therefore has a higher solubility in the organic phase (first solvent 5b) than in the aqueous phase. To reduce the amount of Rn mixed into the first solvent 5b, a heating unit 6a may be provided in the solvent extraction unit 6 to reduce the gaseous solubility by heating. The heating temperature provided by the heating unit 6a can be several tens of degrees Celsius, for example, 50°C to 60°C. The heating unit 6a can be, for example, an electric heater or a gas heater, but is not limited thereto. The heating unit 6a may cover the entire solvent extraction unit 6 or may heat only a portion of it. If the Ra-226 solution target unit 5 and the solvent extraction unit 6 are connected by a hollow tube, the heating unit 6a may heat the hollow tube. Since the temperature of the solution target 5a increases due to irradiation with the bremsstrahlung radiation 4, it is not necessary to heat the first solvent 5b by the heating unit 6a if the solubility of Rn in the solvent is sufficiently low.

[0028] When the solution target 5a is irradiated with bremsstrahlung radiation 4, it reacts with the Ra-226 raw material in the solution target 5a to produce Ra-225 via the (γ, n) reaction. Although other nuclides are also produced via other reaction pathways, their impact on this embodiment is small and therefore not considered here. The produced Ra-225 becomes the daughter nuclide Ac-225 with a half-life of 14.8 days. When Ra-225 decays to Ac-225, Ac-225 selectively bonds with the extractant, becoming nonpolar, and transitions from the second solvent 5c, which is rich in Ra-226, to the first solvent 5b, which is rich in Ac-225.

[0029] This transfer proceeds more quickly as the contact area between the two solvents increases. Because the solution target 5a generates heat upon irradiation with bremsstrahlung radiation 4, convection causes some agitation, but more active agitation can improve separation efficiency. Examples of agitation mechanisms include a method using a liquid delivery mechanism to circulate the solvent, a method using gas bubbling, a method using vibrations such as a motor, and a method using a rotor installed in the solvent. The gas generated during irradiation with bremsstrahlung radiation 4 can be recycled and reused as the bubbling gas.

[0030] Rn-222 generated from the Ra-226 raw material in the solution target 5a is treated in the radon treatment unit 7 installed above the Ra-226 solution target unit 5. One method of treating Rn in the radon treatment unit 7 is adsorption using an activated carbon filter. Rn-222 has a half-life of about 3 days, but its daughter nuclides are Pb-210 (half-life of 22.2 years) and Po-210 (half-life of 138 days), so after adsorption it is managed as radioactive waste.

[0031] To extract the produced Ac-225, the solution target 5a is left to stand, allowing it to separate into two phases: a first solvent 5b rich in Ac-225 and a second solvent 5c rich in Ra-226. Then, only the first solvent 5b rich in Ac-225 is extracted from the solvent extraction section 6 (extracted Ac-225). This allows Ac-225 to be obtained. During phase separation, it is preferable to stop the irradiation of the bremsstrahlung 4 to suppress convection in the solution target 5a and accelerate phase separation. However, if the convection in the solution target 5a is small and the effect on phase separation is minimal, irradiation of the bremsstrahlung 4 may be continued even with irradiation of the bremsstrahlung 4. It is preferable to confirm the occurrence and magnitude of convection in the solution target 5a through a prior confirmation test. If an extractant is used, the extractant can be dissociated from the Ac-225 by changing the solvent property or type for the extracted Ac-225. Since the first solvent 5b containing a large amount of Ac-225 extracted in the solvent extraction unit 6 may contain the extractant and a small amount of Ra-226 raw material, it is preferable to perform additional purification in the Ac-225 purification unit 9. This allows highly purified Ac-225 to be obtained (purified Ac-225). Note that if the extractant can be dissociated from Ac-225 through purification in the Ac-225 purification unit 9, it is not necessary to change the liquidity or type of the solvent for Ac-225 after extraction.

[0032] Purification in the Ac-225 purification unit 9 is performed, for example, by extraction chromatography, ion exchange, solvent extraction, or the like. These methods may be used alone or in any combination. Extraction chromatography can be performed using, for example, DGA resin, LN resin, MnO2 resin, SR resin, UTEVA resin, RE resin, or the like manufactured by Eichrom Technologies. Ion exchange can be performed using, for example, AG50W resin or AG1 resin manufactured by Biorad, or DOWEX50W or DOWEX1 manufactured by The Dow Chemical Company. Solvent extraction in the Ac-225 purification unit 9 can be performed using a conventional method (solvent extraction method) used to separate radionuclides. The extraction conditions for extraction chromatography, ion exchange, and solvent extraction in the Ac-225 purification unit 9 vary depending on the type of extractant and solvent used, the concentration of impurities, and other factors, so it is preferable to confirm them in advance through confirmation tests. Extraction of these radionuclides is widely performed by those skilled in the art, and can be performed without excessive trial and error. At the stage of supplying the Ac-225 purification unit 9, the solvent contains almost no Ra, so Rn control is not required, improving workability.

[0033] As the solvent and extractant are consumed by the operation of the solvent extraction unit 6, the amount of solvent consumed is appropriately added from the solvent addition unit 8 to the Ra-226 solution target unit 5. The solvent added from the solvent addition unit 8 is mainly the first solvent 5b, but if the second solvent 5c has decreased, the second solvent 5c can also be added. The solvent addition unit 8 can also add the extractant. Since Ra is separated in the Ac-225 purification unit 9, albeit in small amounts, it is advisable to return this to the solvent addition unit 8 as appropriate. This can be done as follows.

[0034] FIG. 4 is a schematic diagram illustrating the configuration of a radionuclide production system S according to one embodiment of the present invention. As shown in FIG. 4, the radionuclide production system S may include a recovery unit 10 between the Ac-225 purification unit 9 and the solvent addition unit 8. The recovery unit 10 recovers a small amount of Ra-226 raw material obtained during the purification of Ac-225 in the Ac-225 purification unit 9 and the first solvent 5b containing a large amount of Ac-225, and returns these to the solvent addition unit 8. Furthermore, since the recovered first solvent 5b contains the extractant recovered during the purification, the recovery unit 10 returns the extractant along with the first solvent 5b to the solvent addition unit 8. In other words, the recovery unit 10 functions as a recycling mechanism for the Ra-226 raw material, the first solvent 5b, and the extractant. This reduces radioactive waste and facilitates the recycling of valuable Ra-226 raw material. The recovery section 10 can be configured, for example, by a flexible hollow tube connecting the Ac-225 purification section 9 and the solvent addition section 8, and a pressure-applying device (not shown) such as a diaphragm pump provided midway along the flexible hollow tube. However, the recovery section 10 is not limited to this embodiment as long as it can return the first solvent 5b and the extractant from the Ac-225 purification section 9 to the solvent addition section 8.

[0035] (Radioactive nuclide production method) Next, a radionuclide production method according to one embodiment of the present invention will be described with reference to Fig. 5. Fig. 5 is a flow chart illustrating the details of a radionuclide production method according to one embodiment of the present invention. As shown in FIG. 5, the radionuclide production method according to this embodiment includes a bremsstrahlung generation step S1, an Ac-225 production step S2, a solvent extraction step S3, and a solvent addition step S4. The radionuclide production method may further include an Ac-225 purification step S31 after the solvent extraction step S3. Furthermore, the radionuclide production method may further include a recovery step S32 after the Ac-225 purification step S31. These steps are described below.

[0036] In the bremsstrahlung generation step S1, an electron beam 3 is irradiated from the electron accelerator 1 toward the metal target portion 2, causing bremsstrahlung radiation 4 to be generated from the metal target portion 2. This step can be performed by the electron accelerator 1 and metal target portion 2 described above. In the Ac-225 production step S2, the generated bremsstrahlung radiation 4 is irradiated onto a solvent (i.e., two or more types of solvents containing Ra-226 raw material that undergo phase separation) contained in the Ra-226 solution target unit 5 to produce Ac-225 from the Ra-226 raw material while treating the generated gaseous radon. This step can be performed by the above-mentioned Ra-226 solution target unit 5. Furthermore, the gaseous radon can be treated by the above-mentioned radon treatment unit 7.

[0037] In the solvent extraction step S3, the first solvent 5b containing a large amount of Ac-225 is extracted from the two or more solvents that undergo phase separation. This step can be performed by the solvent extraction unit 6 described above. In the solvent addition step S4, the solvent is added to the Ra-226 solution target section 5 in an amount equivalent to the amount of solvent consumed. This step can be performed by the solvent addition section 8 described above.

[0038] In the Ac-225 purification step S31, Ac-225 is purified from the first solvent 5b containing a large amount of Ac-225 extracted in the solvent extraction step S3. This step can be performed by the Ac-225 purification unit 9 described above. In the recovery step S32, the Ra-226 raw material and the first solvent 5b containing a large amount of Ac-225 obtained when purifying Ac-225 in the Ac-225 purification step S31 are recovered and returned to the solvent addition step S4. This step can be performed by the recovery unit 10 described above.

[0039] As explained above, the radionuclide production system S and radionuclide production method according to this embodiment can produce Ac-225 simply and efficiently because they can separate Ra / Ac simultaneously with the irradiation of bremsstrahlung radiation 4. Furthermore, the radionuclide production system S and radionuclide production method according to this embodiment can be operated in a closed system during the production of Ac-225 to treat Rn, so that Ac-225 can be produced safely.

[0040] The radionuclide production system and radionuclide production method according to the present invention have been described in detail above using embodiments. However, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0041] S Radionuclide Production System 1 Electron accelerator 2 Metal target section 3. Electron beam 4. Bremsstrahlung 5 Ra-226 solution target part 5a Solution Target 5b First Solvent 5c Second Solvent 6 Solvent Extraction Section 6a Heating section 7 Radon Treatment Unit 8 Solvent addition section 9 Ac-225 Purification Department 10 Collection Department S1 Bremsstrahlung generation step S2 Ac-225 Manufacturing Steps S3 Solvent extraction step S31 Ac-225 purification step S32 Recovery step S4 Solvent addition step

Claims

1. an electron accelerator that irradiates electron beams; a metal target portion that generates bremsstrahlung radiation by the irradiated electron beam; a Ra-226 solution target section that is irradiated with the generated bremsstrahlung radiation and that can accommodate two or more types of solvents that contain a Ra-226 raw material and undergo phase separation, and that produces Ac-225 from the Ra-226 raw material when irradiated with the bremsstrahlung radiation; a solvent extraction section for extracting a first solvent containing a large amount of Ac-225 from the two or more solvents that undergo phase separation; a solvent addition unit that adds the solvent to the Ra-226 solution target unit in an amount corresponding to the amount of the solvent consumed; a radon treatment unit that treats gaseous radon generated in the Ra-226 solution target unit; A radionuclide production system comprising:

2. 2. The radionuclide production system according to claim 1, The Ra-226 solution target unit is equipped with a stirring device that mixes the two or more types of solvents that undergo phase separation. A radionuclide production system comprising:

3. 2. The radionuclide production system according to claim 1, The solvent extraction unit includes a heating unit that heats the first solvent containing a large amount of Ac-225. A radionuclide production system comprising:

4. 2. The radionuclide production system according to claim 1, The two or more types of solvents that undergo phase separation are composed of an organic solvent as the first solvent and a polar solvent as the second solvent, and contain an extractant that has the property of selectively binding to Ac-225. A radionuclide production system comprising:

5. 2. The radionuclide production system according to claim 1, The system further includes an Ac-225 purification unit that purifies the Ac-225 from the first solvent containing a large amount of the Ac-225 extracted in the solvent extraction unit. A radionuclide production system comprising:

6. 6. The radionuclide production system according to claim 5, Between the Ac-225 purification section and the solvent addition section, there is provided a recovery section for recovering the Ra-226 raw material obtained when refining the Ac-225 in the Ac-225 purification section and the first solvent containing a large amount of Ac-225 and returning the recovered first solvent to the solvent addition section. A radionuclide production system comprising:

7. 2. The radionuclide production system according to claim 1, The radon treatment unit includes an adsorbent that adsorbs the gaseous radon. A radionuclide production system comprising:

8. The radionuclide production system according to any one of claims 1 to 7, During the phase separation of the two or more solvents, the second solvent containing a large amount of the Ra-226 raw material is at the top in the vertical direction, and the first solvent containing a large amount of the Ac-225 is at the bottom. A radionuclide production system comprising:

9. a bremsstrahlung generating step of irradiating an electron beam from an electron accelerator toward a metal target portion to generate bremsstrahlung radiation from the metal target portion; an Ac-225 production step in which the generated bremsstrahlung radiation is irradiated onto two or more solvents that contain Ra-226 raw material and undergo phase separation, which are contained in an Ra-226 solution target unit, to produce Ac-225 from the Ra-226 raw material while treating the generated gaseous radon; a solvent extraction step of extracting a first solvent containing a large amount of Ac-225 from the two or more solvents that undergo phase separation; a solvent addition step of adding the solvent to the Ra-226 solution target portion in an amount corresponding to the reduced amount of solvent consumed; A method for producing a radionuclide, comprising:

10. 10. The method for producing a radionuclide according to claim 9, After the solvent extraction step, The method further includes an Ac-225 purification step of purifying the Ac-225 from the first solvent containing a high concentration of the Ac-225 extracted in the solvent extraction step. A method for producing a radionuclide.

11. 11. The method for producing a radionuclide according to claim 10, After the Ac-225 purification step, The method further includes a recovery step of recovering the Ra-226 raw material obtained when purifying the Ac-225 in the Ac-225 purification step and the first solvent containing a large amount of Ac-225, and returning the recovered Ra-226 raw material and the first solvent containing a large amount of Ac-225 to the solvent addition step. A method for producing a radionuclide.

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