Method for producing radionuclide and apparatus for producing radionuclide

Abstract

To provide a method for producing a radionuclide in which a target material is irradiated with an electron beam to efficiently generate the radionuclide.SOLUTION: A method for producing a radionuclide, in which an electron beam 31 accelerated by an electron beam accelerator is applied onto a target material 11 containing a nuclide serving as a raw material, and the radionuclide is produced by utilizing a reaction of the raw material with bremsstrahlung radiation generated from the target material 11, the method comprising: Step A: accommodating the target material 11 in a tubular container 12 made of an electron-beam transmissive material and capable of sealing the interior thereof; Step B: generating the radionuclide by rotating the tubular container 12 about its axis and irradiating an outer wall surface of the tubular container 12 with the electron beam 31 reciprocated in the axial direction of the tubular container 12, thereby irradiating the target material 11 with the electron beam 31; and Step C: cooling the tubular container 12 with a cooling medium 24.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a radionuclide and an apparatus for producing a radionuclide. [Background technology]

[0002] In the field of nuclear medicine, radionuclides are used for diagnosis, treatment, and the like. Generally, radionuclides are produced by irradiating a raw material nuclide with radiation to generate a radioisotope (RI) through a nuclear reaction, and then chemically separating the target radionuclides. Charged particle beams, neutron beams, bremsstrahlung, etc. are used as radiation to induce the nuclear reaction.

[0003] Radionuclides known for use in diagnosis include technetium-99m (Tc-99m) and gallium-67 (Ga-67), which emit gamma rays, and fluorine-18 (F-18), oxygen-15 (O-15), nitrogen-14 (N-14), and carbon-11 (C-11), which emit beta rays.

[0004] Technetium-99m is metastable in its excited state and emits gamma rays when it undergoes isomeric transition to the ground state, making it a widely used radionuclide for diagnostics. The most common source of technetium-99m is molybdenum-99. The daughter nuclide, technetium-99m, is produced by beta decay of the parent nuclide, molybdenum-99.

[0005] Molybdenum-99 has a short half-life of approximately 66 hours, making it difficult to store for long periods of time. Therefore, in most cases, it must be transported by air immediately before use. To resolve this supply issue, new production methods are being considered, including activation methods that activate natural isotopes such as molybdenum oxide.

[0006] When producing radionuclides by irradiating a target material with radiation, the heat generated by the irradiation can cause the irradiated target to locally become hot and melt. If the target material melts, there is a risk of RI leaking, so the target must be cooled. Conventional technology has proposed an idea to improve cooling performance by dividing the target where RI is produced into small pieces to disperse the high heat generation areas and increase the surface area that comes into contact with cooling water and air.

[0007] Patent Document 1 shows a conventional radionuclide manufacturing apparatus shown in FIGS. 12A and 12B. 12A is a configuration diagram of a radionuclide production apparatus 100 including a target device 10. The radionuclide production apparatus 100 includes the target device 10 and an accelerator 60 that generates a particle beam.

[0008] FIG. 12B is a schematic cross-sectional view of the target device 10. As shown in FIG. The target device 10 is composed of a plurality of target material plates 20 and a holding frame 30 that holds the target material plates 20 in an array with spaces between them. The target material plates 20 are made of molybdenum metal in the shape of a disk.

[0009] The accelerator 60 is a linear accelerator (LINAC) that accelerates an electron beam in a straight line. A linearly formed cylindrical acceleration cavity 62 is connected to the accelerator 60, and the acceleration cavity 62 accelerates the electron beam using an electric field to generate a particle beam (electron beam EB) of a desired energy. The electron beam EB generated by the accelerator 60 is directly irradiated onto the target material plate 20, and when the electron beam EB collides with the target material plate 20, braking radiation occurs, generating braking radiation (bremsstrahlung photons), which produces radioactive nuclides within the target.

[0010] The target device 10 is disposed inside a cooling device 50. Cooling water CW is supplied to the cooling device 50. In this embodiment, a heat exchanger 52 and a water supply line 54 are connected to the cooling device 50, and the cooling water CW is circulated and supplied to the target device 10. The holding frame 30 holds the target material plates 20 with a gap V provided between adjacent target material plates 20. Cooling water CW passes through the gap V to cool the target material plates 20 that generate heat upon collision with the electron beam EB and bremsstrahlung photons. After irradiation, the target material plate 20 is chemically treated to separate the radionuclides from the target material plate 20 . As described above, in Patent Document 1, the target material is divided into a plurality of pieces to disperse the high heat generating portions, thereby increasing the surface area in contact with the cooling water and air, thereby improving the cooling performance. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-156143 Summary of the Invention [Problem to be solved by the invention]

[0012] When producing molybdenum-99 by irradiating molybdenum-100 with an electron beam, it is necessary to irradiate a target material containing the raw material nuclide with a large current in order to increase the amount of molybdenum-99 produced. However, irradiating the target material with a large current generates a lot of heat, which makes it difficult to cool the target material.

[0013] In conventional technology, the use of solid metals as target materials has been considered, but when irradiated with large currents, the irradiated area can instantly rise to several thousand degrees, posing the risk of the metal melting and vaporizing and leaking into the surrounding area. Furthermore, if an attempt is made to increase the surface area in contact with the cooling water and air, the RI density generated within the target material becomes low, resulting in the problem of the irradiated radiation not being used effectively.

[0014] An object of the present invention is to provide a method and an apparatus for producing radioactive nuclides that can efficiently produce radioactive nuclides by irradiating a target material with an electron beam at a large current using an electron beam accelerator. [Means for solving the problem]

[0015] The present invention, which aims to solve the above problems, provides a method for producing a radionuclide as described below. A method for producing radioactive nuclides by irradiating a target material containing raw material nuclides with an electron beam accelerated by an electron beam accelerator, and utilizing the reaction between the raw material and the bremsstrahlung radiation generated from the target material, the method comprising the following steps: Step A: A step of placing the target material in a tubular container made of an electron beam transparent material and capable of being sealed, and sealing the container. Step B: A step of irradiating the target material with the electron beam to generate radioactive nuclides by irradiating the outer wall surface of the tubular container along the outer peripheral surface of the tubular container and irradiating the target material with the electron beam in a reciprocating manner in the axial direction of the tubular container. Step C: Cooling the tubular container with a cooling medium [Effects of the Invention]

[0016] An object of the present invention is to provide a method for producing radionuclides that can efficiently generate radionuclides by irradiating a large current electron beam using an electron beam accelerator. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram illustrating the method for producing a radionuclide of the present invention. [Figure 2] 2A to 2C are diagrams illustrating a tubular container and a target material accommodated in the tubular container according to the present invention. [Figure 3] 3A and 3B are diagrams showing how a support member of a support mechanism is attached to the upper end of a tubular container containing a target material. [Figure 4] 4A to 4C are diagrams showing how the shape of the target material inside the tubular container changes. [Figure 5]FIG. 5 is a diagram showing an example of a method for irradiating a target material with an electron beam. [Figure 6] 6A and 6B are diagrams showing an example of a method for irradiating a target material with an electron beam. [Figure 7] 7A and 7B are diagrams showing an example of a method for irradiating a target material with an electron beam. [Figure 8] 8A and 8B are diagrams showing an example of a method for irradiating a target material with an electron beam. [Figure 9] 9A and 9B are diagrams showing an example of a method for irradiating a target material with an electron beam. [Figure 10] 10A to 10D are diagrams showing an example of a method for irradiating a target material with an electron beam. [Figure 11] 11A to 11D are diagrams showing an example of a method for irradiating a target material with an electron beam. [Figure 12] 12A and 12B are diagrams illustrating a conventional method for producing radionuclides. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention relates to the method for producing a radionuclide described below in (1), but also includes the following embodiments (2) to (17), which will be described below. (1) A method for producing radionuclides by irradiating a target material containing a raw material nuclide with an electron beam accelerated by an electron beam accelerator, and producing a radionuclides by utilizing the reaction between the raw material and the bremsstrahlung radiation generated from the target material, the method comprising the following steps: Step A: A step of placing the target material in a tubular container made of an electron beam transparent material and capable of being sealed, and sealing the container. Step B: A step of irradiating the target material with the electron beam to generate radioactive nuclides by irradiating the outer wall surface of the tubular container along the outer peripheral surface of the tubular container and irradiating the target material with the electron beam in a reciprocating manner in the axial direction of the tubular container. Step C: Cooling the tubular container with a cooling medium (2) The method for producing a radionuclide according to (1) above, wherein in step B, the tubular container is rotated around its axis and reciprocated in the axial direction of the tubular container. (3) The method for producing a radionuclide according to (1) above, wherein in step B, the tubular container is rotated around the axis of the tubular container, and the electron beam accelerator is reciprocated in the axial direction of the tubular container. (4) The method for producing a radionuclide according to any one of (1) to (3) above, wherein in step B, the tubular container is supported so that the central axis of the tubular container is aligned with the vertical direction. (5) The method for producing a radionuclide according to any one of (1) to (4) above, wherein in step B, the tubular container is supported so that the tubular container is at an angle to the vertical direction. (6) The method for producing a radionuclide according to any one of (1) to (5) above, wherein in step B, the tubular container is vibrated so as to cross the electron beam. (7) A method for producing a radionuclide according to any one of (1) to (6) above, wherein in step B, the electron beam is irradiated onto the outer wall surface of the tubular container in such a manner that the electron beam oscillates in the axial direction of the tubular container. (8) The method for producing a radionuclide according to any one of (1) to (7) above, wherein in step B, the electron beam irradiates the outer wall surface of the tubular container from multiple directions. (9) The method for producing a radionuclide according to any one of (1) to (8) above, wherein the target material is one selected from the group consisting of molybdenum-100 (Mo-100), radium-226 (Ra-226), hafnium-178 (Hf-178), germanium-70 (Ge-70), zinc-66,68 (Zn-66,68), titanium-48 (Ti-48), and calcium-48 (Ca-48), or compounds thereof. (10) The method for producing a radionuclide according to (9) above, wherein the target material is molybdenum-100, and molybdenum-99 is produced from molybdenum-100 by irradiating the molybdenum-100 with the electron beam. (11) A radionuclide manufacturing device that irradiates a target material containing a raw material nuclide with an electron beam accelerated by an electron beam accelerator, thereby producing a radionuclide by utilizing the reaction between the raw material and the bremsstrahlung radiation generated from the target material, an electron beam accelerator; a tubular container made of an electron beam transparent material and having an inside sealed, which contains the target material; a support mechanism for supporting the tubular container; a tank that accommodates the tubular container; a cooling medium contained in the tank; and a heat exchanger for cooling the cooling medium; a pipe for sending the cooling medium in the tank to the heat exchanger and returning the cooling medium cooled by the heat exchanger to the tank, the support mechanism supports an upper end of the tubular container and is capable of causing the tubular container to rotate around its axis and reciprocate in its axial direction, The electron beam can be irradiated onto the target material through an outer wall surface of the tubular container. A radionuclide manufacturing apparatus characterized by: (12) A radionuclide manufacturing device that irradiates a target material containing a raw material nuclide with an electron beam accelerated by an electron beam accelerator, thereby manufacturing a radionuclide by utilizing the reaction between the raw material and the bremsstrahlung radiation generated from the target material, an electron beam accelerator; a tubular container made of an electron beam transparent material and having an inside sealed, which contains the target material; a support mechanism for supporting the tubular container; an electron beam accelerator reciprocating mechanism that holds the electron beam accelerator and reciprocates the irradiation position of the electron beam accelerator in the axial direction of the tubular container; a tank that accommodates the tubular container; a cooling medium contained in the tank; and a heat exchanger for cooling the cooling medium; a pipe for sending the cooling medium in the tank to the heat exchanger and returning the cooling medium cooled by the heat exchanger to the tank, the support mechanism supports an upper end of the tubular container and allows the tubular container to rotate about its axis, The electron beam can be irradiated onto the target material through an outer wall surface of the tubular container. A radionuclide manufacturing apparatus characterized by: (13) A radionuclide manufacturing apparatus according to (11) or (12) above, wherein the support mechanism has a function of reciprocating the tubular container in a direction perpendicular to the axial direction of the tubular container. (14) The radionuclide manufacturing apparatus according to any one of (11) to (13) above, wherein the support mechanism supports the tubular container at an angle relative to the vertical direction. (15) A radionuclide manufacturing apparatus according to any one of (11) to (14) above, comprising an electron beam oscillation means for oscillating the side surface of the tubular container in the axial direction of the tubular container. (16) A radionuclide manufacturing apparatus according to any one of (11) to (15) above, further comprising another electron beam accelerator, and configured to irradiate the target material through the outer wall surface of the tubular container by the other electron beam accelerator. (17) A radionuclide manufacturing apparatus according to any one of (11) to (16) above, wherein at least the wall portion of the tank through which the electron beam passes is made of a thin metal film or quartz.

[0019] The method for producing a radionuclide of the present invention will be outlined based on an embodiment. In the following, we will use molybdenum oxide ( 100 This section explains the case where MoO3 (melting point 795°C) is used and the radioactive nuclide produced is molybdenum-99.

[0020] The method for producing a radionuclide of the present invention comprises irradiating a target material containing a nuclide as a raw material with an electron beam accelerated by an electron beam accelerator, thereby producing a radionuclide by utilizing a reaction between the raw material and the bremsstrahlung radiation generated from the target material, and includes steps A, B, and C described below. Step A: A step of placing the target material in a tubular container made of an electron beam transparent material and capable of being sealed, and sealing the container. Step B: A step of irradiating the target material with the electron beam to generate radioactive nuclides by irradiating the outer wall surface of the tubular container along the outer peripheral surface of the tubular container and irradiating the target material with the electron beam in a reciprocating manner in the axial direction of the tubular container. Step C: Cooling the tubular container with a cooling medium

[0021] The step A is a step of housing and sealing the target material inside a tubular container made of an electron beam transparent material and capable of being sealed, in order to hold the target material to be irradiated with an electron beam. In step B, the electron beam is irradiated onto the target material contained in the tubular container along the outer surface of the tubular container, and also back and forth in the axial direction of the tubular container, thereby irradiating the electron beam evenly onto all of the target material to generate radioactive nuclides. The step C is a step of removing heat generated by irradiating the target material with an electron beam using a cooling medium.

[0022] In step B, the method of irradiating the outer wall surface of the tubular container with an electron beam along the outer peripheral surface of the tubular container can be carried out by rotating the tubular container around its axis or by rotating an electron beam accelerator around the axis of the tubular container. The method in step B in which the electron beam is irradiated by reciprocating in the axial direction of the tubular container can be carried out by causing the tubular container to move back and forth in the axial direction of the tubular container, or by causing an electron beam accelerator to move back and forth in the axial direction of the tubular container. Hereinafter, the present invention will be described based on an embodiment of the present invention.

[0023] (Embodiment 1) As shown in Fig. 1, a tubular vessel 12 containing a target material 11 is supported in a tank 21 by a support mechanism 13. At least the wall portion of the tank 21, through which the electron beam 31 passes, is made of a thin metal film or quartz, allowing the electron beam 31 to easily pass through. It is preferable that the distance between the tubular vessel 12 and the wall portion of the tank 21 where the electron beam 31 is incident be as small as possible to avoid absorption of the electron beam 31 by the cooling medium 24.

[0024] The tank 21 contains a cooling medium 24 (the following explanation will be given using the example of "cooling water"). This cooling water 24 is drawn out of the tank 21 through a suction pipe 25, cooled in a heat exchanger 22, and returned to the tank 21 through a discharge pipe 26. When the target material 11 is irradiated with the electron beam 31, the stable isotope of molybdenum-100 in the target material becomes molybdenum-99.

[0025] The target material 11 generates heat due to the irradiation of the electron beam 31. An agitator 23 is provided inside the tank 21, and the cooling water 24 inside the tank 21 is agitated to cool the target material 11. Cooling is also necessary to prevent the pressure inside the tank 21 from increasing and causing damage to the tank 21.

[0026] (target material) The target material 11 is housed in a tubular container 12 as shown in FIGS. 2A to 2C. The shape of the target material 11 is shown in FIGS. 2A, 2B, and 2C. FIG. 2A shows a powdered target material 11 housed in a tubular container 12. In FIG. 2B shows a powdered target material 11 compressed into a disk shape and housed in a tubular container 12. In the example shown in FIG. 2C shows a powdered target material 11 compressed into a tablet shape and housed in a tubular container 12. In the example shown in FIG. In the following, the present invention will be described taking as an example the case where the disk-shaped target material 11 shown in FIG. 2B is used.

[0027] Conventionally, a plate material made of a metal element with a high atomic number and density, called a converter, is used as the target material, and an electron beam is collided with it to generate bremsstrahlung radiation, which is then collided with the raw material to produce radioactive nuclides. In contrast to this, in this embodiment, by using molybdenum 100, a metal element with a high atomic number and density, as the target material, it is possible to generate bremsstrahlung radiation even by collision of the target material with an electron beam. Therefore, in the method for producing radioactive nuclides of this embodiment, a converter is not required, and the device can be simplified.

[0028] (tubular container) The tubular container 12 used in the present invention is made of an electron beam transparent material and has a sealed interior. The electron beam transparent material is selected from those that satisfy the following conditions: a high melting point, high corrosion resistance, good processability, chemical stability even at high temperatures, and the required strength when made into a tubular container.Specific examples include metal materials such as quartz glass, stainless steel, titanium, nickel, titanium alloys, and nickel alloys (Inconel, Hastelloy, Monel, DSALOY, etc.), as well as various ceramics.

[0029] In the present invention, the target material is irradiated with an electron beam to become molten. When molybdenum oxide is used as the target material, the melting point of molybdenum oxide is 795°C, so the material of the tubular vessel must be heat-resistant.

[0030] Quartz glass is a preferred material for the tubular vessel because it can withstand temperatures as high as 1000°C. A quartz glass tube (quartz tube) is used as the electron beam transparent material, and after the target material is placed inside the quartz glass tube, the open end of the quartz glass tube is sealed to obtain a tubular container containing the target material. A large amount of heat is generated in the tubular container 12 by irradiation with the electron beam 31, and in order to remove this heat, cooling water 24 is used as shown in FIG. When quartz glass is used as the material for the tubular vessel 12, since quartz glass has a heat resistance of up to 1000 degrees, even if the target material 11 is locally melted and vaporized, there is no problem as long as the tubular vessel 12 can be kept sealed.

[0031] (Support mechanism) An embodiment of the support mechanism will be described with reference to FIG. The support mechanism comprises a support member 13 that supports the tubular container, a rotating shaft 14 joined to the support member, and a rotary / reciprocating drive mechanism 15 having a drive mechanism that rotates the rotating shaft 14 around its own axis and reciprocates the rotating shaft 14 in the axial direction.

[0032] FIG. 3A is a diagram showing a state in which a support member 13 having a rotation axis 14 is attached to the upper end of a tubular container 12 containing a target material 11. The rotating shaft 14 is connected to a rotary reciprocating drive mechanism 15 shown in Figure 1. When the rotary reciprocating drive mechanism 15 is driven, the rotating shaft 14 rotates around its own axis and also reciprocates in the axial direction of the rotating shaft 14. A support member 13 is attached to the upper end of the tubular container 12, and when the rotating shaft 14 rotates and reciprocates, the tubular container 12 also rotates around its axis and reciprocates in the axial direction of the rotating shaft 14.

[0033] 4A to 4C are diagrams that schematically show the change in state of the target material 11 when the target material 11 is irradiated with the electron beam 31. FIG. 4A shows the initial state of the target material 11 after it has been irradiated with the electron beam 31. The state is shown in which the target material 11 has been irradiated with the electron beam 31 and has partially melted, producing a melt 11a. 4B shows a state in which the molten material 11a has formed a solidified material 11b on the inner wall of the tubular vessel 12 and a state in which other portions of the target material 11 have melted. The molten material 11a is viscous and therefore adheres to the inner wall of the tubular vessel 12 in a thin, uniform manner, and since the tubular vessel 12 is cooled by the cooling water 24, the molten material 11a adhering to the inner wall of the tubular vessel 12 is cooled and forms a solidified material 11b. FIG. 4C shows a state in which the target material 11 is uniformly irradiated with the electron beam 31, and a solidified material layer 11c made of the solidified material 11b is formed on the inner wall of the tubular container 2.

[0034] By irradiating the tubular container 12 with an electron beam 31 in a direction perpendicular to the axial direction of the tubular container 12 while rotating and reciprocating the tubular container 12, the electron beam is irradiated evenly onto the target material 11 contained in the tubular container 12 regardless of the position of the target material within the tubular container 12, and the target material 11 can be used effectively.

[0035] (Embodiment 2) A second embodiment of the present invention is shown in FIG. This embodiment is the same as embodiment 1 in that the tubular container 12 is rotated by a rotation shaft 14, but instead of moving the tubular container 12 back and forth in the vertical direction, the electron beam 31 is moved back and forth in the vertical direction.

[0036] (Embodiment 3) Another embodiment 3 of the present invention is shown in FIGS. 6A and 6B. In this embodiment, in order to eliminate uneven melting of the target material 11c and maintain the target material 11c evenly attached to the inner wall surface of the tubular container 12, the electron beam 31 is irradiated with the tubular container 12 tilted at a predetermined angle θ as shown in Figures 6A and 6B. In the embodiment 3-1 shown in FIG. 6A, the tubular container 12 is rotated around its axis and reciprocated along an axis tilted at an angle θ, while the tubular container 12 is irradiated with an electron beam 31 from a horizontal direction. The embodiment 3-2 shown in Figure 6B is the same as the embodiment 3-1 in that the tubular container 12 is rotated by the rotation axis 14, but instead of reciprocating the tubular container 12 along an axis tilted at an angle θ, the electron beam 31 is reciprocated in the vertical direction.

[0037] (Embodiment 4) Another embodiment 4 of the present invention is shown in FIGS. 7A and 7B. In this embodiment, in order to eliminate uneven melting of the target material 11c and maintain the target material 11c evenly attached to the inner wall surface of the tubular vessel 12, the tubular vessel 12 is vibrated so as to cross the electron beam as shown in Figures 7A and 7B. In the examples shown in FIGS. 7A and 7B, the tubular container is vibrated in a direction perpendicular to the direction of the electron beam 31. The word "vibration" and the attached symbol in FIGS. 7A and 7B indicate that the vibration is in a direction perpendicular to the direction of the electron beam 31 (direction perpendicular to the paper surface). In embodiment 4-1 shown in Figure 7A, the tubular container 12 is rotated and reciprocated, and is also vibrated in a direction perpendicular to the direction of the electron beam 31 (a direction perpendicular to the paper surface), so that the electron beam 31 is irradiated onto the tubular container 12 from a horizontal direction. The embodiment 4-2 shown in Figure 7B is the same as embodiment 4-1 in that the tubular container 12 is rotated and vibrated in a direction perpendicular to the direction of the electron beam 31 (perpendicular to the paper surface), but instead of reciprocating the tubular container 12 in the vertical direction, the electron beam 31 is reciprocated in the vertical direction.

[0038] (Embodiment 5) Another embodiment 5 of the present invention is shown in FIGS. 8A and 8B. In this embodiment, in order to eliminate uneven melting of the target material 11c and maintain the target material 11c evenly attached to the inner wall surface of the tubular container 12, the electron beam 31 is oscillated in the vertical direction as shown in Figures 8A and 8B, so that it is irradiated from top to bottom of the target material 11c. In embodiment 5-1 shown in Figure 8A, the tubular container 12 is rotated and reciprocated, and the electron beam 31 is swung in an up and down direction from a horizontal direction relative to the tubular container 12 to irradiate the target material. In embodiment 5-2 shown in Figure 8B, the tubular container 12 is rotated while the electron beam 31 is oscillated vertically from a horizontal direction relative to the tubular container 12 to irradiate the target material, which is the same as embodiment 5-1. However, instead of moving the tubular container 12 back and forth vertically, the electron beam 31 is moved back and forth vertically to irradiate the target material.

[0039] (Embodiment 6) Another embodiment 6 of the present invention is shown in FIGS. 9A and 9B. In this embodiment, an additional electron beam accelerator is provided to irradiate the wall surface of the tubular container 12 with electron beams from two directions. 9A, an additional electron beam accelerator is provided, and the electron beam 31 is irradiated onto the tubular container 12 from direction a and direction b, which is the opposite direction to direction a. In this way, more electron beams 31 can be irradiated onto the target material 11c, and therefore the amount of radioactive nuclides produced can be increased. In the embodiment 6-2 shown in FIG. 9B, instead of the tubular container 12 in the embodiment 6-1 being reciprocated in the up and down direction, the electron beam 31 is reciprocated in the up and down direction.

[0040] Modifications of the above embodiments will be described below. In the embodiment shown in FIG. 7A, a configuration is adopted in which the tubular container 12 is vibrated in a direction perpendicular to the direction of the electron beam 31 (hereinafter referred to as "vibration operation"). In FIG. 8A, a configuration is adopted in which the electron beam 31 is swung in an up and down direction (hereinafter referred to as "swinging operation"). In FIG. 9A, an additional electron beam accelerator is provided, and a configuration is adopted in which electron beam 31 is irradiated from two directions (hereinafter referred to as "two-directional irradiation"). The above-mentioned configurations of vibration operation, swing operation, and two-way irradiation can be appropriately selected or combined and applied to the embodiments shown in FIGS. 10 and 11 show examples of embodiments to which the above-mentioned configurations are applied.

[0041] FIG. 10A shows the embodiment of FIG. 4C, which employs vibration and rocking motions. FIG. 10B shows the embodiment of FIG. 4C, but with a rocking motion and two-way illumination. FIG. 10C shows the embodiment of FIG. 4C, but with vibration motion and two-way illumination. FIG. 10D shows the embodiment of FIG. 4C, which employs vibration and swinging motions and two-way illumination.

[0042] FIG. 11A shows the embodiment of FIG. 6A, which employs vibration and rocking motions. FIG. 11B shows the embodiment of FIG. 6A, but with a rocking motion and two-way illumination. FIG. 11C shows the embodiment of FIG. 6A, but with vibration motion and two-way illumination. FIG. 11D shows the embodiment of FIG. 6A, which employs vibration and swinging motions and two-way illumination.

[0043] The target material 11 produced as described above and containing molybdenum-99 is treated by an appropriate chemical treatment process to extract the radionuclide (technetium-99m). The molybdenum oxide from which the technetium 99m has been separated by a chemical treatment process is reused as the target material 11 again.

[0044] The method for producing radioactive nuclides according to the present invention has been explained above by taking as an example a method for producing molybdenum-99 from molybdenum-100 [nuclear reaction formula: Mo-100(γ,n)Mo-99]. The manufacturing method of the present invention is not limited to molybdenum, but can also be applied to nuclides that cause a nuclear reaction in the raw material due to bremsstrahlung radiation generated by irradiating the target material 11 with an electron beam 31. Specifically, radium-226, hafnium-178, germanium-70, zinc-66, zinc-68, titanium-48, calcium-48, or compounds thereof can be used as the raw material. [Explanation of symbols]

[0045] (Figures 1 to 11) 11 Target material 11a Melt 11b Coagulum 11c coagulum layer 12 Tubular container 13 Support member 14 Rotation axis 15 Rotational reciprocating drive mechanism 21 Tank 22 Heat exchanger 23 Mixer 24 Cooling medium, cooling water 25 Suction pipe 26 Discharge pipe 31 Electron beam

[0046] (Figure 12) 10 Target Device 20 target material plate 30 holding frame 50 Cooling device 52 Heat exchanger 54 Water supply channel 60 Accelerator 62 Acceleration Cavity 100 Radionuclide manufacturing equipment EB electron beam CW cooling water

Claims

1. A method for producing radioactive nuclides by irradiating a target material containing raw material nuclides with an electron beam accelerated by an electron beam accelerator, and utilizing the reaction between the raw material and the bremsstrahlung radiation generated from the target material, the method comprising the following steps: Step A: A step of placing the target material in a tubular container made of an electron beam transparent material and capable of being sealed, and sealing the container. Step B: A step of irradiating the target material with the electron beam to generate radioactive nuclides by irradiating the outer wall surface of the tubular container along the outer peripheral surface of the tubular container and irradiating the target material with the electron beam in a reciprocating manner in the axial direction of the tubular container. Step C: Cooling the tubular container with a cooling medium

2. 2. The method for producing a radionuclide according to claim 1, wherein in step B, the tubular container is caused to rotate around its axis and to reciprocate in its axial direction.

3. 2. The method for producing a radionuclide according to claim 1, wherein in step B, the tubular container is caused to rotate around its axis, and the electron beam accelerator is caused to reciprocate in the axial direction of the tubular container.

4. The method for producing a radionuclide according to claim 1 , wherein in step B, the tubular container is supported so that the central axis of the tubular container coincides with the vertical direction.

5. The method for producing a radionuclide according to claim 1 , wherein in step B, the tubular container is supported so that it is angled relative to the vertical direction.

6. The method for producing a radionuclide according to claim 1 , wherein in step B, the tubular container is vibrated so as to cross the electron beam.

7. The method for producing a radionuclide according to claim 1 , wherein in step B, the electron beam irradiates the outer wall surface of the tubular container so as to oscillate in the axial direction of the tubular container.

8. The method for producing a radionuclide according to claim 1 , wherein in step B, the electron beam irradiates the outer wall surface of the tubular container from a plurality of directions.

9. 4. The method for producing a radionuclide according to any one of claims 1 to 3, wherein the target material is one selected from molybdenum-100 (Mo-100), radium-226 (Ra-226), hafnium-178 (Hf-178), germanium-70 (Ge-70), zinc-66,68 (Zn-66,68), titanium-48 (Ti-48), and calcium-48 (Ca-48), or compounds thereof.

10. The method for producing a radionuclide according to claim 9, wherein the target material is molybdenum-100, and molybdenum-99 is produced from the molybdenum-100 by irradiating the molybdenum-100 with the electron beam.

11. A radionuclide manufacturing device for manufacturing radionuclides by irradiating a target material containing raw material nuclides with an electron beam accelerated by an electron beam accelerator, and utilizing a reaction between the raw material and the bremsstrahlung radiation generated from the target material, an electron beam accelerator; a tubular container made of an electron beam transparent material and having an inside sealed, which contains the target material; a support mechanism for supporting the tubular container; a tank that accommodates the tubular container; a cooling medium contained in the tank; and a heat exchanger for cooling the cooling medium; a pipe for sending the cooling medium in the tank to the heat exchanger and returning the cooling medium cooled by the heat exchanger to the tank, the support mechanism supports an upper end of the tubular container and is capable of causing the tubular container to rotate around its axis and reciprocate in its axial direction, The electron beam can be irradiated onto the target material through an outer wall surface of the tubular container. A radionuclide manufacturing apparatus characterized by:

12. A radionuclide manufacturing device for manufacturing radionuclides by irradiating a target material containing raw material nuclides with an electron beam accelerated by an electron beam accelerator, and utilizing a reaction between the raw material and the bremsstrahlung radiation generated from the target material, an electron beam accelerator; a tubular container made of an electron beam transparent material and having an inside sealed, which contains the target material; a support mechanism for supporting the tubular container; an electron beam accelerator reciprocating mechanism that holds the electron beam accelerator and reciprocates the irradiation position of the electron beam accelerator in the axial direction of the tubular container; a tank that accommodates the tubular container; a cooling medium contained in the tank; and a heat exchanger for cooling the cooling medium; a pipe for sending the cooling medium in the tank to the heat exchanger and returning the cooling medium cooled by the heat exchanger to the tank, the support mechanism supports an upper end of the tubular container and allows the tubular container to rotate about its axis, The electron beam can be irradiated onto the target material through an outer wall surface of the tubular container. A radionuclide manufacturing apparatus characterized by:

13. 13. The radionuclide manufacturing apparatus according to claim 11 or 12, wherein the support mechanism has a function of reciprocating the tubular container in a direction perpendicular to the axial direction of the tubular container.

14. 13. The radionuclide manufacturing apparatus according to claim 11 or 12, wherein the support mechanism supports the tubular container at an angle relative to the vertical direction.

15. 13. The radionuclide manufacturing apparatus according to claim 11, further comprising an electron beam swinging means for swinging the electron beam along the side surface of the tubular container in the axial direction of the tubular container.

16. 13. The radionuclide manufacturing apparatus according to claim 11 or 12, further comprising another electron beam accelerator, wherein the target material is irradiated by the other electron beam accelerator through an outer wall surface of the tubular container.

17. 13. The radionuclide manufacturing apparatus according to claim 11, wherein at least a wall portion of the tank through which the electron beam passes is made of a metal thin film or quartz.

Images