Target substrate loading device and radioactive isotope production device

Abstract

This target substrate loading device: holds a plurality of target substrates arranged in the thickness direction, which are to be irradiated with a charged particle beam from a particle accelerator and are to be loaded to a target device that holds the target substrates; and automatically sends the target substrates to the target device.

Description

Target substrate loading device and radioisotope production device

[0001] The present disclosure relates to a target substrate loading device and a radioisotope production device.

[0002] Conventionally, target devices for producing radioisotopes using a solid target have been known (see, for example, Patent Document 1). In this type of target device using a solid target, accelerated particles are introduced from a particle accelerator such as a cyclotron, and a nuclear reaction occurs between the particles and elements constituting the solid target, thereby producing radioisotopes within the solid target. The solid target after the nuclear reaction is then recovered from the target device, and the radioisotopes are obtained by processing the solid target, such as dissolving it using a strong acid or strong base liquid.

[0003] Japanese Unexamined Patent Publication No. 61-246699

[0004] However, when loading or unloading a target substrate, which is a solid target, into or from a target device, it is necessary to stop the particle accelerator, confirm that the radioactivity has decreased to a predetermined level, and then have a worker enter the shield to perform the work. Therefore, the work of setting the target substrate into the target device involves exposure to radiation. The present disclosure aims to provide a target substrate loading device and a radioisotope production apparatus that enable automatic loading of target substrates into the target device.

[0005] The gist of the present disclosure lies in the following [1] to [5].

[0006] [1] A target substrate loading device that holds a plurality of target substrates arranged in the thickness direction to be loaded into a target device that holds target substrates to be irradiated with a charged particle beam from a particle accelerator, and automatically sends the target substrates to the target device.

[0007] [2] The target substrate loading device described in [1], comprising: a magazine section that holds a plurality of the target substrates arranged in the thickness direction; and a substrate delivery section that delivers the target substrates held in the magazine section to the target device.

[0008] [3] The target substrate loading device described in [2], wherein the substrate discharge section is provided below the target substrate held in the magazine section and comprises a substrate discharge hole through which the target substrate passes and drops, and a magazine drive section that drives the magazine section relative to the substrate discharge hole in the arrangement direction of the target substrates.

[0009] [4] The target substrate loading device described in [3], wherein the magazine drive unit comprises: a ratchet unit provided in the magazine unit and having a plurality of ratchet teeth arranged in the same direction as the target substrates; and a claw unit that engages with the ratchet unit and reciprocates in the arrangement direction of the target substrates.

[0010] [5] A radioisotope manufacturing apparatus comprising: a target substrate loading device according to any one of [1] to [4]; and a target device that receives and holds the target substrate sent from the target substrate loading device, wherein the target substrate held by the target device is irradiated with the charged particle beam to manufacture a radioisotope.

[0011] According to the present disclosure, it is possible to provide a target substrate loading device and a radioisotope manufacturing apparatus that enable automatic loading of a target substrate into a target device.

[0012] 1 is a side view schematically showing a radioisotope manufacturing apparatus according to an embodiment; FIG. 2 is a plan view schematically showing a radioisotope manufacturing apparatus according to an embodiment; FIG. 3 is a plan view schematically showing a target device in an open state; (a) is a cross-sectional view showing the vicinity of a substrate slot when the target device is in an open state, (b) is a cross-sectional view showing the vicinity of a substrate slot when the target device is in a closed state, and (c) is a cross-sectional view taken along line IVc-IVc in (b); (a) is a plan view showing a mechanism of a target substrate loading device, and (b) is a side cross-sectional view thereof; (a) is a plan view showing a target substrate loading device in operation, continuing from FIG. 6; (b) is a side cross-sectional view thereof; (a) is a plan view showing a target substrate loading device in operation, continuing from FIG. 7; and (b) is a side cross-sectional view thereof.

[0013] A radioisotope manufacturing apparatus 100 according to this embodiment will be described with reference to the drawings. Fig. 1 is a side view schematically showing the radioisotope manufacturing apparatus 100, and Fig. 2 is a plan view thereof. As shown in the figures, the radioisotope manufacturing apparatus 100 includes a target device 101 and a target substrate loading device 103 disposed above the target device 101.

[0014] The target device 101 is a device that holds a target substrate 10. The target substrate 10 is configured, for example, in the shape of an oval disk, and a metal layer made of a target material is formed on the surface of the target substrate 10. In the radioisotope production process, the target substrate 10 is set in the target device 101, and the target device 101 is moved leftward from the state shown in FIGS. 1 and 2 . Then, the front end of the target device 101 is inserted into the manifold 201 of the particle accelerator 200, and the target device 101 is attached to the manifold 201 of the particle accelerator 200 so that the front end face of the target device 101 is pressed against the receiving surface of the manifold 201. The target substrate 10 is held in the target device 101 in an orientation tilted about an axis vertical to the irradiation direction of the charged particle beam B. In this state, the charged particle beam B is irradiated from the particle accelerator 200 onto the target substrate 10 in the target device 101. In the area irradiated with the charged particle beam B, a small amount of radioactive isotopes are produced by nuclear reactions in the target material.

[0015] In the radioisotope production system 100 of this embodiment, the target substrate 10 is a meltable metal target, and after irradiation with the charged particle beam B, the target material can be melted at the irradiation position. After the melting operation, the liquid is transferred to a hot cell refinement device (not shown) in the subsequent process. Note that metal nuclide refinement using this mechanism can be realized by adding one liquid transfer pipe to an existing facility.

[0016] FIG. 3 is a plan view schematically illustrating the target device 101 in an open state. As shown in FIGS. 1 to 3, the target device 101 has a cylindrical shape. The target device 101 includes a main body 2, a front flange 3 provided in front of the main body 2 (upstream of the charged particle beam B), and an intermediate holder 4 provided between the main body 2 and the front flange 3. The main body 2, the intermediate holder 4, and the front flange 3 are separated in the irradiation direction of the charged particle beam B. The joint between the main body 2 and the intermediate holder 4 and the joint between the intermediate holder 4 and the front flange 3 exist along a vertical plane that obliquely intersects with the irradiation direction of the charged particle beam B.

[0017] The front flange 3 is capable of reciprocating movement relative to the main body 2 in the irradiation direction of the charged particle beam B, and the intermediate holder 4 is similarly capable of reciprocating movement relative to the main body 2 in the irradiation direction of the charged particle beam B. To enable such reciprocating movement, the target device 101 is provided with a drive unit (not shown), and also with a guide bar 42 that guides the movement.

[0018] The main body 2 is formed with a cooling water circulation hole 13 for cooling the target substrate 10. In the irradiation process of the charged particle beam B, the cooling water in the cooling water circulation hole 13 comes into contact with and flows through the back surface of the target substrate 10 in the intermediate holder 4, thereby cooling the target substrate 10 that generates heat.

[0019] The front flange 3 is formed with a through-hole 32 for passing the charged particle beam B. An O-ring (not shown) is provided on the front surface of the front flange 3 so as to surround the opening of the through-hole 32. In the irradiation process of the charged particle beam B, the front surface of the front flange 3 is pressed against the receiving surface of the manifold 201 ( FIG. 1 ) of the particle accelerator 200, thereby connecting the through-hole 32 to the beam exit port of the particle accelerator 200.

[0020] The intermediate holder 4 is a member that holds the target substrate 10. The intermediate holder 4 is held in a substrate slot 47 of the intermediate holder 4 in an orientation inclined about an axis vertical to the irradiation direction of the charged particle beam B. The intermediate holder 4 includes a front plate 43 and a rear plate 44 that are parallel to each other and sandwich the target substrate 10 in the thickness direction. The substrate slot 47, into which the target substrate 10 is loaded, is formed as a space between the front plate 43 and the rear plate 44. Note that the intermediate holder 4 does not have a top plate and a bottom plate for the substrate slot 47, and therefore the intermediate holder 4 alone cannot support the target substrate 10 in the substrate slot 47. The structure for supporting the target substrate 10 in the substrate slot 47 will be described later.

[0021] FIG. 4A is a cross-sectional view showing the vicinity of the substrate slot 47 when the target device 101 is open. FIG. 4B is a cross-sectional view showing the vicinity of the substrate slot 47 when the target device 101 is closed. FIG. 4C is a cross-sectional view taken along line IVc-IVc in FIG. 4B. As shown in FIG. 4, the front plate 43 is formed with a hole 43a of a predetermined shape that prevents the target substrate 10 from passing through. During the irradiation process of the charged particle beam B, the rear surface 3b of the front flange 3 is brought into close contact with the front surface of the target substrate 10 in the substrate slot 47 through the hole 43a, and the opening end face of the through-hole 32 faces the target material on the target substrate 10. Similarly, the rear plate 44 is formed with a hole 44a of a predetermined shape that prevents the target substrate 10 from passing through. During the irradiation process of the charged particle beam B, the front surface 2a of the main body 2 is brought into close contact with the back surface of the target substrate 10 in the substrate slot 47 through the hole 44a, and the cooling water circulation hole 13 is connected to the back surface of the target substrate 10. In this manner, in the target device 101 , the target substrate 10 is sandwiched between the front flange 3 and the main body 2 .

[0022] Furthermore, a flange 20 is formed on the front surface 2a of the main body 2 below the cooling water circulation hole 13. The flange 20 protrudes outward toward the intermediate holder 4 by an amount approximately equal to the thickness of the substrate slot 47. When the main body 2 and the intermediate holder 4 are joined, the flange 20 is inserted into the lower end of the substrate slot 47 through the hole 44a, thereby forming the bottom wall of the substrate slot 47. The target substrate 10 inserted from above into the substrate slot 47 is supported by the flange 20 located at the lower end of the substrate slot 47 and remains within the substrate slot 47. Furthermore, when the main body 2 and the intermediate holder 4 move away from each other in the irradiation direction of the charged particle beam B, the flange 20 is removed from within the substrate slot 47, and the unsupported target substrate 10 falls downward from the substrate slot 47.

[0023] Next, the target substrate loading device 103 will be described. Below, a reference axis A is set as shown in FIG. 2 and will be used to explain the positional relationships of the various parts. In a plan view, the reference axis A extends in a direction perpendicular to the target substrate 10 held in the target device 101. FIG. 5( a) is a plan view showing the mechanism of the target substrate loading device 103, and FIG. 5( b) is a side cross-sectional view thereof. The target substrate loading device 103 is a device that stores a plurality of new target substrates 10 and automatically loads these target substrates 10 one by one into the substrate slots 47 of the target device 101.

[0024] The target substrate loading device 103 comprises a housing 51, a magazine section 53 which is provided within the housing 51 and forms a frame for holding a plurality of target substrates 10, and a substrate sending section 55 which automatically sends the target substrates 10 held in the magazine section 53 to the target device 101 one by one.

[0025] A groove 53a is formed within the frame of the magazine section 53, capable of accommodating the target substrates 10 one by one. The groove 53a can accommodate the target substrates 10 in a vertically standing position (with the front and back surfaces forming vertical planes), and the target substrates 10 in the groove 53a are perpendicular to the reference axis A. That is, the target substrates 10 are accommodated in the groove 53a with the reference axis A direction as the thickness direction. The target substrates 10 are not firmly held within the groove 53a; the groove 53a restricts horizontal displacement but not vertical movement. The lower end of the target substrate 10 accommodated in the groove 53a contacts the bottom surface of the housing 51, and the target substrate 10 is supported by the bottom plate of the housing 51 and remains within the groove 53a. If the housing 51 did not have a bottom plate, the target substrate 10 would slip out of the groove 53a and slide downward.

[0026] A plurality of grooves 53a as described above are arranged in the direction of the reference axis A at a pitch of, for example, about two to three times the thickness of the target substrate 10. Therefore, the magazine section 53 holds a plurality of target substrates 10 arranged in the thickness direction at a pitch of, for example, about two to three times the thickness of the target substrates 10.

[0027] The magazine unit 53 is configured to be movable parallel to the reference axis A direction within the housing 51. Specifically, a guide shaft 52 extending in the reference axis A direction is provided within the housing 51, and the side surface of the magazine unit 53 is slidably engaged with the guide shaft 52. The magazine unit 53 is guided by the guide shaft 52 and moves parallel to the reference axis A direction within the housing 51.

[0028] The board feed unit 55 includes a magazine drive unit 57 and a board discharge hole 59. The magazine drive unit 57 drives the magazine unit 53 in the reference axis A direction relative to the board discharge hole 59. Specifically, the magazine drive unit 57 drives the magazine unit 53 in the reference axis A direction within the housing 51. The magazine drive unit 57 includes a ratchet unit 61 provided on the side of the magazine unit 53 opposite the guide shaft 52 side, a pawl unit 63 that engages with the ratchet unit 61, and a drive device 67 that reciprocates the pawl unit 63. The ratchet unit 61 has a plurality of ratchet teeth 61a linearly arranged in the reference axis A direction at the same pitch as the grooves 53a. The ratchet teeth 61a are inclined on only one side, and the pawl unit 63 is a ratchet pawl that hooks on only the other side of the ratchet teeth 61a. The ratchet mechanism that moves the magazine unit 53 in only one direction is configured by the ratchet portion 61 and the claw portion 63. In the example of Fig. 5, this ratchet mechanism is provided only on one side of the magazine unit 53, but one ratchet mechanism may be provided on each side of the magazine unit 53.

[0029] The drive unit 67 is fixed to the outer surface of the housing 51, and may be, for example, an air cylinder. The drive unit 67 reciprocates a piston 67a along the reference axis A. The pawl 63 is fixed to the piston 67a of the drive unit 67 via a predetermined connecting part 67b, and the drive unit 67 can reciprocate the pawl 63 along the reference axis A. When the drive unit 67 reciprocates the pawl 63 with a stroke equal to one pitch of the ratchet teeth 61a, the pawl 63 attracts one ratchet tooth 61a, and the magazine unit 53 can be moved leftward in the drawing along the reference axis A. The movement amount of the magazine unit 53 at this time is equal to one pitch of the arrangement of the target substrates 10. That is, in the example of FIG. 5 , the magazine unit 53 moves one pitch to the left each time the pawl 63 reciprocates with a stroke equal to one pitch of the ratchet teeth 61a.

[0030] A spring (not shown) that biases the magazine unit 53 in the direction opposite to the direction of movement is provided on the guide shaft 52. When the magazine unit 53 stops, the ratchet teeth 61 a are pressed against the pawl 63 by the biasing force of the spring, thereby positioning the magazine unit 53.

[0031] The substrate ejection hole 59 is a hole that is provided in the bottom plate of the housing 51 and penetrates the bottom plate from top to bottom. The substrate ejection hole 59 is a long, narrow hole that extends in a direction perpendicular to the direction of the reference axis A, and is sized and shaped to allow the target substrate 10 in a vertical position to pass through with a small gap. Such a substrate ejection hole 59 exists in one location within the movable range of the magazine unit 53.

[0032] A description will now be given of the operation of the above-described target substrate loading device 103 during operation. When the target substrate loading device 103 is in operation, the substrate slot 47 of the target device 101 is positioned vertically below the substrate discharge hole 59, and the target substrate loading device 103 is positioned so that the substrate discharge hole 59 and the substrate slot 47 overlap in a plan view. In addition, in the target device 101, the intermediate holder 4 and the main body 2 are joined, and the flange 20 is inserted into the lower end of the substrate slot 47.

[0033] The target substrate loading device 103 operates as follows. As shown in FIGS. 5( a) and 5(b), at the start of operation, one target substrate 10 is set in each groove 53a of the magazine unit 53 as a preliminary preparation. From this state, as shown in FIGS. 6(a) and 6(b) and 7(a) and 7(b), when the drive unit 67 is driven and the claw unit 63 makes one reciprocating motion, the magazine unit 53 is moved one pitch of the ratchet teeth 61a in the direction of the reference axis A. As a result, the frontmost target substrate 10 reaches the position of the substrate discharge hole 59. As shown in FIGS. 7(a) and 7(b), this target substrate 10 falls into the substrate discharge hole 59, exits the magazine unit 53, passes through the substrate discharge hole 59, and falls freely downward. Note that the substrate discharge hole 59 may be tapered, as shown in the figures, so that the target substrate 10 can smoothly fall into and pass through the substrate discharge hole 59.

[0034] The dropped target substrate 10 fits into the substrate slot 47 located vertically below, and is loaded in the substrate slot 47. The target device 101 loaded with the target substrate 10 is attached to the manifold 201 ( FIG. 1 ) of the particle accelerator 200 as described above, and the target substrate 10 is irradiated with the charged particle beam B. After the irradiation with the charged particle beam B, a predetermined process is performed, and the intermediate holder 4 and the main body 2 are moved away from each other, causing the flange 20 to retract from the substrate slot 47, and the target substrate 10 to slide down and be ejected from the substrate slot 47.

[0035] At the next operation, the drive device 67 is driven again, and the magazine unit 53 is moved in the direction of the reference axis A by one pitch of the ratchet teeth 61a. As a result, the second target substrate 10 from the front position passes through the substrate discharge hole 59 and falls, fitting into the substrate slot 47 of the target device 101. By repeating the above operation, the target substrate loading device 103 can load target substrates 10 one by one into the target device 101. Finally, as shown in FIGS. 8(a) and 8(b), when the previously prepared number of target substrates 10 has been used up, an operator can manually replenish the magazine unit 53 with target substrates 10, for example.

[0036] The effects of the target substrate loading device 103 and the radioisotope manufacturing apparatus 100 equipped with the same will now be described.

[0037] According to the target substrate loading device 103, by driving the drive device 67, the number of target substrates 10 prepared in advance in the magazine unit 53 can be automatically loaded one by one into the target device 101. Therefore, there is no need to manually load the target substrates 10 into the target device 101, and as a result, worker exposure to radiation can be avoided. Furthermore, there is no need for skills such as disassembling and assembling the target device 101 when loading the target substrates 10.

[0038] Furthermore, in the target substrate loading device 103, the target substrates 10 are arranged in the thickness direction and held in the magazine section 53. Therefore, many target substrates 10 can be prepared in the target substrate loading device 103 without becoming bulky. Therefore, the dimensions of the magazine section 53 can be kept small, the target substrate loading device 103 can be made smaller, and the radioisotope manufacturing apparatus 100 can be made smaller.

[0039] Furthermore, since the target substrate 10 is fed by moving the magazine section 53 one pitch at a time using a ratchet mechanism, the automatic loading of the target substrate 10 can be achieved by a simple driving device such as a reciprocating air cylinder.

[0040] The present disclosure can be implemented in various forms, including the above-described embodiments, with various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, it is also possible to configure modified examples by utilizing the technical matters described in the above-described embodiments. The configurations of the respective embodiments may be used in appropriate combination.

[0041] For example, in the embodiment, the target substrate 10 is loaded into the substrate slot 47 by being allowed to fall freely from the target substrate loading device 103, but a guide portion may be provided to guide the movement of the target substrate 10 due to gravity from the substrate discharge hole 59 of the target substrate loading device 103 to the substrate slot 47.

[0042] 10...target substrate, 53...magazine section, 55...substrate delivery section, 57...magazine drive section, 59...substrate discharge hole, 61...ratchet section, 61a...ratchet teeth, 63...claw section, 100...radioisotope manufacturing device, 101...target device, 103...target substrate loading device, 200...particle accelerator, B...charged particle beam.

Claims

1. A target substrate loading device that holds a plurality of target substrates arranged in the thickness direction for loading into a target device that holds a target substrate irradiated with a charged particle beam from a particle accelerator, and automatically sends out the target substrate to the target device.

2. The target substrate loading device according to claim 1, comprising: a magazine unit that holds a plurality of the target substrates arranged in the thickness direction; and a substrate sending unit that sends out the target substrate held by the magazine unit to the target device.

3. The substrate sending unit of the target substrate loading device according to claim 2, comprising: a substrate discharge hole provided below the target substrate held by the magazine unit for allowing the target substrate to pass through and drop; and a magazine driving unit that drives the magazine unit relative to the substrate discharge hole in the arrangement direction of the target substrates.

4. The magazine driving unit of the target substrate loading device according to claim 3, comprising: a ratchet unit provided in the magazine unit and having a plurality of ratchet teeth arranged in the same direction as the target substrate; and a claw unit that engages with the ratchet unit and reciprocates in the arrangement direction of the target substrates.

5. A radioactive isotope production device, comprising: the target substrate loading device according to claim 1; and the target device that receives and holds the target substrate sent out from the target substrate loading device, wherein the charged particle beam is irradiated onto the target substrate held by the target device to produce a radioactive isotope.

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