Radioactive isotope production system and radioactive isotope production method

Abstract

The present invention provides a radioactive isotope production system and a radioactive isotope production method that can be miniaturized. [Solution] According to this radioactive isotope production system 100, the target 10 after irradiation with charged particle beam B is made smaller than it was during irradiation, and the radioactive isotope is recovered. Figure 6(b) shows what happens when the target 10 after irradiation with charged particle beam B is placed in the purification apparatus 103 at its original size. As shown in Figure 6(b), because the size of the target 10 is large, the internal space 31 needs to be enlarged, and as a result, the entire purification apparatus 103 must be enlarged. In contrast, by making the target 10 smaller after irradiation, a smaller purification apparatus 103 can be used, as shown in Figure 6(a). Thus, the system can be miniaturized.

Description

Technical Field

[0001] The present invention relates to a radioactive isotope production system and a radioactive isotope production method.

Background Art

[0002] Conventionally, a target device for producing radioactive isotopes using a solid target has been known (see, for example, Patent Document 1). In this type of target device using a solid target, accelerated particles are introduced from an accelerator such as a cyclotron, and a nuclear reaction is caused with the element constituting the solid target, thereby generating a radioactive isotope in the solid target. Then, the solid target in which the nuclear reaction has occurred is recovered from the target device, and separation and purification are performed by a method using the difference in melting point or boiling point from the raw material (dry purification method), or a method using the difference in chemical properties after treating the solid target by dissolving it using a liquid of a strong acid or strong base (wet purification method), to obtain a radioactive isotope. In many cases, the separation and purification are also implemented in a device (purification device).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the above-described radioactive isotope production system, after the charged particle beam is irradiated onto the target, the target is directly put into the purification device on the downstream side. Here, by widening the area of the charged particle beam with respect to the target material and arranging the target obliquely, heat generation concentration is prevented and irradiation is performed with a large current, so that the production amount of the radioactive isotope may be increased. However, in this case, the target itself also becomes large. When the size of the target is large, there is a problem that the purification device also becomes large accordingly.

[0005] Therefore, the objective is to provide a radioactive isotope production system and a radioactive isotope production method that can be miniaturized. [Means for solving the problem]

[0006] A radioactive isotope production system according to one aspect of the present invention is a radioactive isotope production system that generates radioactive isotopes by irradiating a target with a charged particle beam, wherein the target after irradiation with the charged particle beam is made smaller than it was during irradiation, and the radioactive isotopes are recovered.

[0007] This radioactive isotope production system recovers radioactive isotopes by reducing the size of the target after irradiation with charged particle beams to a smaller size than during irradiation. In this case, a smaller purification device can be used compared to when the target after irradiation with charged particle beams is placed into the purification device at its original size. Therefore, the system can be miniaturized.

[0008] A radioactive isotope production system according to one aspect of the present invention is a radioactive isotope production system that generates radioactive isotopes by irradiating a target with a charged particle beam, wherein the target after irradiation with the charged particle beam is processed to be smaller than it was during irradiation.

[0009] This radioactive isotope production system processes the target after irradiation with charged particle beams to make it smaller than it was during irradiation. In this case, a smaller target can be obtained through processing than the target was during irradiation. This allows for the use of a smaller purification apparatus than when the irradiated target is placed in the purification apparatus at its original size. As a result, the system can be miniaturized.

[0010] The target comprises a target substrate and a target material fixed to the target substrate. When reducing the size of the target, the area of ​​the target substrate not to which the target material is fixed is cut. In this case, before cutting, the area not to which the target material is fixed can be used for sealing. On the other hand, by cutting this area during the cutting process, the entire target can be reduced in size without cutting the target material.

[0011] Before cutting, the target substrate may have a portion at the cutting location that is thinner than other parts. In this case, the thinner portion can be easily cut when cutting the target.

[0012] The target substrate may have a notch at the planned cutting location before cutting. In this case, the target can be easily cut by the notch.

[0013] In the target, the target substrate may be cut in a straight line along the edge of the target material. In this case, the target can be made smaller by a simple operation or a simple cutting mechanism.

[0014] A radioactive isotope production method according to one aspect of the present invention is a method for producing radioactive isotopes by irradiating a target with a charged particle beam, wherein the target after irradiation with the charged particle beam is made smaller than it was during irradiation, and the radioactive isotope is recovered.

[0015] This method for producing radioactive isotopes allows for the same effects and benefits as the radioactive isotope production system described above. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a radioactive isotope production system and a radioactive isotope production method that can be miniaturized. [Brief explanation of the drawing]

[0017] [Figure 1] It is a block diagram of a radioactive isotope production system according to an embodiment. [Figure 2] It is a diagram schematically showing an irradiation device. [Figure 3] It is a diagram showing a target. [Figure 4] It is a diagram schematically showing a processing device 102. [Figure 5] It is a diagram showing the target before and after processing. [Figure 6] It is a diagram schematically showing a purification device. [Figure 7] It is a diagram showing an example of a target. [Figure 8] It is a diagram showing a method for cutting a target according to a modification.

Embodiments for Carrying Out the Invention

[0018] The radioactive isotope production system 100 according to the present embodiment will be described while referring to the drawings. FIG. 1 is a block diagram of the radioactive isotope production system 100. As shown in FIG. 1, the radioactive isotope production system 100 includes an irradiation device 101, a processing device 102, and a purification device 103. A transport mechanism for transporting the target is provided between the devices. The target is transported in the order of the irradiation device 101, the processing device 102, and the purification device 103. The radioactive isotope production system 100 is a system that irradiates a target 10 with a charged particle beam B to generate a radioactive isotope. The radioactive isotope production system 100 reduces the target 10 after irradiation with the charged particle beam B to be smaller than the state during irradiation, and recovers the radioactive isotope.

[0019] FIG. 2 is a schematic diagram schematically showing the irradiation device 101. The irradiation device 101 is a device that irradiates the target 10 with the charged particle beam B. As shown in FIG. 2, the irradiation device 101 is a device that irradiates the target 10 with the charged particle beam B from an accelerator (not shown) and, if necessary, a beam line 1 under high vacuum to generate a radioisotope. The inside of the accelerator and the beam line 1 are kept under high vacuum to prevent beam loss, and the most downstream side thereof is separated by a thin film 20 made of a high-strength material to keep these interiors under high vacuum. The irradiation device 101 irradiates the charged particle beam B along the irradiation axis CL1. The irradiation device 101 has a container 2 through which the vacuum charged particle beam B passes. The container 2 constitutes a beam line that guides the charged particle beam B along the irradiation axis CL1. Further, the container 2 has a gas supply unit 3 having a spraying function for spraying a gas (for example, He) that is difficult to be activated in order to cool the surfaces of the thin film 20 and the target 10. Among the irradiation device 101, a portion 4 downstream of the target 10 has a cooling unit 6 that supplies cooling water to the target 10.

[0020] Here, the target 10 will be described with reference to Figure 3. Figure 3 shows the target 10 before irradiation with charged particle beam B and during irradiation. Figure 3(a) is a plan view of the target 10 used in this embodiment. Figure 3(b) is a side view of the target 10. The target 10 comprises a target substrate 11 and a target material 12 fixed to the target substrate 11. The target material 12 is a solid layer formed on one side of the main surface 11a of the target substrate 11. As the target material 12, elements of Ni, Y, Zn, Bi, Te or compounds thereof may be used. As the target substrate 11, Al, Au, Cu, Ag, etc. may be used. For example, when producing astatine-211, a bismuth target material 12 may be fixed to an inexpensive aluminum target substrate 11 and irradiated with helium nuclei. The target material 12 is formed in a region of the main surface 11a of the target substrate 11 that includes at least the central position. The main surface 11a of the target substrate 11 has a region E1 in which the target material 12 is not fixed, within a predetermined distance from the outer peripheral edge 11c toward the inner peripheral edge. As shown in Figure 3(a), the target 10 has an oval shape extending in the direction of the long axis. The target material 12 also has an oval shape extending in the direction of the long axis. Figure 3(b) is a view of the target 10 from the direction of the long axis. The shape of the target 10 is not limited and may have a circular shape as shown in Figure 3(c).

[0021] The irradiation device 101 has a holding part 7 that holds the target material 12 of the target 10 at the position of the irradiation axis CL1. As a result, the target material 12 of the target 10 is irradiated with charged particle beam B. The holding part 7 holds the target 10 by sandwiching it between part 2 and the downstream part 4. The holding part 7 holds the portion of the target substrate 11 that is on the outer periphery of the target material 12, i.e., the region E1 where the target material 12 is not fixed. The holding part 7 presses an annular sealing member 16 against the main surface 11a of the target substrate 11 at a position corresponding to region E1. The holding part 7 presses an annular sealing member 17 against the main surface 11b of the target substrate 11 opposite to the target material 12. The sealing members 16 and 17 are in close contact with the target substrate 11 so as to surround the target material 12 from the outer periphery (see Figure 3(a)).

[0022] Next, the processing apparatus 102 will be described with reference to Figure 4. The processing apparatus 102 is a device that processes the target 10 after irradiation with charged particle beam so that it becomes smaller than it was during irradiation. The processing apparatus 102 reduces the size of the target 10 by cutting a part of it. When reducing the size of the target 10, the processing apparatus 102 cuts the region E1 of the target substrate 11 in which the target material 12 is not fixed.

[0023] Here, with reference to Figure 5, the target 10 before and after cutting will be described. Figure 5(a) shows the target 10 before it is processed by the processing device 102. Figure 5(b) shows the target 10 after it has been processed by the processing device 102. Figure 5(a) shows the planned cutting position CT, which is the position where the processing device 102 is scheduled to cut. The processing device 102 cuts the target 10 at the planned cutting position CT. The planned cutting position CT is set to a position and shape that surrounds the target material 12 on its outer circumference.

[0024] The position of the planned cutting position CT is not particularly limited, but in the example shown in Figure 5, it is set in region E1, at a position that is spaced away from the outer edge of the target material 12. The dimension between the outer edge 12a of the target material 12 and the planned cutting position CT is denoted as "GP". The ratio of dimension GP to the dimension between the outer edge 12a of the target material 12 and the outer edge 11c of the target substrate 11 is set to 100%, and this ratio can be set to any range. The planned cutting position CT is set closer to the outer edge 12a of the target material 12 than to the outer edge 11c of the target substrate 11 (dimension GP < 50%). However, the planned cutting position CT may also be set at approximately the same position as the outer edge 12a of the target material 12 (dimension GP = 0%). Furthermore, the planned cutting position CT may be set at the midpoint between the outer edge 12a of the target material 12 and the outer edge 11c of the target substrate 11 (dimension GP = 50%), or it may be set closer to the outer edge 11c than to the outer edge 12a (dimension GP > 50%). Although not particularly limited, the dimension GP may be 2 mm or more from the viewpoint of ensuring a cutting allowance to avoid cutting the target material 12. If the target 10X is sufficiently small, the dimension GP may be 1 mm or less.

[0025] By performing the cut at the planned cutting position CT described above, the area of ​​the target substrate 11 on the outer periphery of the planned cutting position CT is removed from the target 10. As a result, the processed target 10X will be in the state shown in Figure 5(b). The processed target 10X will be smaller than the unprocessed target 10 shown in Figure 5(a). Specifically, the long axis dimension LD2 of the processed target 10X is smaller than the long axis dimension LD1 of the unprocessed target 10. The short axis dimension SD2 of the processed target 10X is smaller than the short axis dimension SD1 of the unprocessed target 10.

[0026] As shown in Figure 4, the processing apparatus 102 has a cutting mechanism 20 for cutting the target substrate 11 at the planned cutting position CT as described above. The cutting mechanism 20 shown in Figure 4(a) comprises a base portion 23 and a blade portion 24 fixed to the base portion 23. The cutting mechanism 20 shown in Figure 4(a) cuts the target substrate 11 by pressing the blade portion 24 against the target 10 supported on the support base 21 from above. The blade portion 24 has an oval annular shape corresponding to the planned cutting position CT. The cutting mechanism 20 punches out the target 10X by pressing the blade portion 24 against the target substrate 11 with the tip of the blade portion 24 positioned on the planned cutting position CT.

[0027] The specific configuration of the cutting mechanism 20 is not particularly limited. For example, as shown in Figure 4(b), the cutting mechanism 20 may cut the target substrate 11 by moving the blade portion 26 so as to trace the cutting position CT. Alternatively, as shown in Figure 4(c), the cutting mechanism 20 may cut the target substrate 11 by irradiating the laser LZ from the laser cutting portion 27 toward the cutting position CT and moving the laser LZ so as to trace the cutting position CT.

[0028] Next, the purification apparatus 103 will be described with reference to Figure 6(a). The purification apparatus 103 is a device that recovers radioactive isotopes from the target material 12 of the target 10 after irradiation with charged particle beam B by purification. In the example shown in Figure 6(a), a dry purification apparatus is used as the purification apparatus 103. The purification apparatus 103 has a tubular furnace 30. The tubular furnace 30 has an internal space 31 made of an inert, high-melting-point material such as quartz in which the processed target 10X is placed. The target 10X is placed in the internal space 31 such that its long axis extends along the longitudinal direction of the internal space 31. The tubular furnace 30 heats the target 10X. At this time, the difference in the volatilization temperatures of different compounds is used to separate the radioactive isotopes in the target material 12 from other compounds, and the radioactive isotopes are purified by flowing them downstream using a carrier gas and taking them out to a collection section outside the tubular furnace. Furthermore, the purification apparatus 103 is not limited to a dry purification apparatus, and a dissolution apparatus for a wet purification method may also be used.

[0029] Next, the operation and effects of the radioactive isotope production system 100 and the radioactive isotope production method according to this embodiment will be described.

[0030] The radioactive isotope production system 100 according to this embodiment is a radioactive isotope production system 100 that generates radioactive isotopes by irradiating a target 10 with a charged particle beam B. The radioactive isotope production system 100 recovers the radioactive isotopes by reducing the size of the target 10 after irradiation with the charged particle beam B to a size smaller than that during irradiation.

[0031] According to this radioactive isotope production system 100, the target 10, after irradiation with charged particle beam B, is made smaller than it was during irradiation, and the radioactive isotope is recovered. Figure 6(b) shows what happens when the target 10, after irradiation with charged particle beam B, is placed in the purification apparatus 103 at its original size. As shown in Figure 6(b), because the target 10 is large, the internal space 31 needs to be enlarged, and as a result, the entire purification apparatus 103 must be enlarged. In contrast, by reducing the size of the target 10 after irradiation, a smaller purification apparatus 103 can be used, as shown in Figure 6(a). Thus, the system can be miniaturized.

[0032] Furthermore, by reducing the size of the target 10 after irradiation, it becomes possible to design a target substrate 11 suitable for irradiation by the irradiation device 101 without having to forcibly miniaturize the target substrate 11 during irradiation in order to miniaturize the purification device 103. In addition, by reducing the size of the target 10 after irradiation, the amount of heat lost to the target substrate 11 can be suppressed, so the target material 12 can be heated efficiently.

[0033] The radioactive isotope production system 100 according to this embodiment is a radioactive isotope production system 100 that generates radioactive isotopes by irradiating a target 10 with a charged particle beam B. The radioactive isotope production system 100 processes the target 10 after irradiation with the charged particle beam B so that it is smaller than it was during irradiation.

[0034] According to this radioactive isotope production system 100, the target 10 after irradiation with charged particle B is processed to be smaller than its size during irradiation. In this case, a smaller target 10X can be obtained through processing than the target 10 when it was irradiated with charged particle B. In this case, a smaller purification apparatus 103 can be used than when the irradiated target 10 is placed in the purification apparatus 103 at its original size (see Figure 6(b)) (see Figure 6(a)). As a result, the system can be miniaturized.

[0035] The target 10 comprises a target substrate 11 and a target material 12 fixed to the target substrate 11. When reducing the size of the target 10, a region E1 of the target substrate 11 where the target material 12 is not fixed is cut. In this case, before cutting, the region E1 where the target material 12 is not fixed can be used for sealing. On the other hand, by cutting this region E1 during the cutting process, the entire target 10X can be reduced in size without cutting the target material 12.

[0036] The radioactive isotope production method according to this embodiment is a method for producing radioactive isotopes by irradiating a target 10 with a charged particle beam B. In this radioactive isotope production method, the target 10 after irradiation with the charged particle beam B is made smaller than it was during irradiation, and the radioactive isotopes are recovered.

[0037] This method for producing radioactive isotopes can be used to obtain the same effects and benefits as the radioactive isotope production system 100 described above.

[0038] The present invention is not limited to the embodiments described above.

[0039] For example, the structure of the target substrate 11 is not limited to the embodiments described above. As shown in Figure 7(a), the target substrate 11 before cutting may have a portion 40 at the planned cutting position CT that is thinner than other parts. Specifically, the target substrate 11 has a thin-walled portion 41 that becomes thinner due to a depression in the main surface 11b opposite to the target material 12. The thin-walled portion 41 may be formed to be at least the size that includes the planned cutting position CT. In this case, the thin portion 40 can be easily cut when cutting the target 10.

[0040] For example, as shown in Figure 7(b), the target substrate 11 before cutting may have a notch 50 at the planned cutting position CT. In this case, the target 10 can be easily cut by the notch 50.

[0041] Furthermore, the shape of the cutting position CT is not limited to the embodiments described above. For example, as shown in Figure 8, the target substrate 11 may be cut linearly along the outer edge 12a of the target material 12 in the target 10. In the example shown in Figure 8, a rectangular cutting position CT is set that surrounds the target material 12. In order to cut the linear cutting position CTs corresponding to the four sides, the cutting mechanism 20 is moved linearly along each cutting position CT. In this case, the target 10 can be made smaller by simple operation or a simple cutting mechanism (for example, the cutting mechanism 20 in Figures 4(b) and 4(c)).

[0042] The configurations of the irradiation device 101, processing device 102, purification device 103, target substrate, etc., in the above-described embodiment are merely examples and can be modified as appropriate without departing from the spirit of the invention. [Explanation of Symbols]

[0043] 10...Target, 11...Target substrate, 12...Target material, 40...Thinning area, 50...Incision, 100...Radioactive isotope production system.

Claims

1. A radioisotope production system that generates radioisotopes by irradiating a target with a charged particle beam, A radioisotope production system for recovering the radioisotope by reducing the size of the target after irradiation with the charged particle beam to a size smaller than that during irradiation.

2. A radioisotope production system that generates radioisotopes by irradiating a target with a charged particle beam, A radioactive isotope production system that processes a target after irradiation with the aforementioned charged particle beam so that it becomes smaller than it was during irradiation.

3. The target comprises a target substrate and a target material fixed to the target substrate. The radioactive isotope production system according to claim 1 or 2, wherein when reducing the size of the target, a region of the target substrate on which the target material is not fixed is cut.

4. The radioactive isotope production system according to claim 3, wherein the target substrate before cutting has a portion at the cutting location where the thickness is thinner than other portions.

5. The radioactive isotope production system according to claim 3, wherein the target substrate before cutting has an incision at the position to be cut.

6. The radioactive isotope production system according to claim 3, wherein the target substrate is cut in a straight line along the edge of the target material in the target.

7. A method for producing radioactive isotopes by irradiating a target with a charged particle beam, A method for producing radioactive isotopes, comprising reducing the size of the target after irradiation with the charged particle beam to a size smaller than that during irradiation, thereby recovering the radioactive isotope.

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