A target system for a neutron source

Abstract

The present application relates to a kind of target systems for neutron source, belong to neutron physics and neutron source technical field, including radiation conversion target, target cooling unit and target replacement unit, the target body of radiation conversion target is stacked by multiple target sheets, target sheet gap for cooling liquid flow is formed between adjacent target sheets, the inside of target cooling unit is equipped with cooling liquid flow passage, the radiation conversion target is located inside the cooling liquid flow passage, target replacement unit moves the radiation conversion target in cooling liquid flow passage to positioning table, the two sides of the positioning table are respectively equipped with target assembly and unloading target assembly, the unloading target assembly is used to disassemble before replacement radiation conversion target, the target assembly is used to install after replacement radiation conversion target, the present application can effectively radiate radiation conversion target, improve the beam current tolerance of radiation conversion target, and also can realize remote automatic replacement radiation conversion target, avoid operator close contact and be damaged by radiation.

Description

Technical Field

[0001] This invention belongs to the field of neutron physics and neutron source technology, and specifically relates to a target system for neutron sources. Background Technology

[0002] A neutron source is an extremely useful tool for nuclear data measurement and research, providing the necessary nuclear data measurements for nuclear astrophysics research, nuclear energy development, and applications. It has wide applications in nuclear technologies such as neutron radiography, neutron therapy, and neutron irradiation effects (e.g., material irradiation damage, biological effects). A high-current electron linear accelerator uses a high-current electron beam to bombard a high-atomic-number radiation conversion target to produce high-energy gamma rays. These high-energy gamma rays then bombard the radiation conversion target again to produce neutrons. When the high-energy electron beam bombards the radiation conversion target, almost all of the electron beam energy is deposited on the target, causing a sudden increase in target temperature. Therefore, the radiation conversion target needs to be cooled to prevent melting and damage, which would affect the stable operation of the device. Furthermore, the radiation conversion target in a neutron source needs to be selected with different thicknesses depending on the energy range of the accelerator's electron beam, or the target needs to be replaced when its service life reaches its limit. However, the radiation conversion target after being bombarded by a high-energy electron beam, the target chamber where the radiation conversion target is installed, and even all objects inside the target chamber after being irradiated with neutrons may all have induced radioactivity, making it impossible for operators to enter the target chamber for maintenance in a short period of time. Summary of the Invention

[0003] In order to address the shortcomings of existing technologies and solve the above problems, a target system for neutron sources is proposed. This system can effectively dissipate heat from the radiation conversion target, improve the beam current tolerance of the radiation conversion target, and enable remote automated replacement of the radiation conversion target, thus avoiding radiation damage to operators from close contact.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A target system for a neutron source, comprising:

[0006] The radiation conversion target is composed of multiple target plates stacked together, with gaps between adjacent target plates forming a channel for coolant flow.

[0007] The target cooling unit has a coolant flow channel inside, and the radiation conversion target is located inside the coolant flow channel.

[0008] The system also includes a target replacement unit, which moves the radiation conversion target in the coolant flow channel to the positioning platform. The positioning platform is equipped with a target loading assembly and a target unloading assembly on both sides. The target unloading assembly is used to disassemble the radiation conversion target before replacement, and the target loading assembly is used to install the radiation conversion target after replacement.

[0009] The technical solution is further configured to include a radiation shielding layer, wherein the radiation conversion target and the target cooling unit are located inside the radiation shielding layer, and the target replacement unit is located above the radiation shielding layer.

[0010] The technical solution is further configured such that the radiation shielding layer is provided with an electron beam vacuum channel and a neutron transmission channel, the electron beam vacuum channel being provided at the front end of the radiation conversion target and the neutron transmission channel being provided at the rear end of the radiation conversion target.

[0011] The technical solution is further configured such that, along the direction of electron beam propagation, the thickness of multiple target sheets varies from thin to thick.

[0012] The technical solution is further configured such that the target cooling unit includes an inner shell and an outer shell with a clearance fit, the interior of the inner shell and the gap between the inner shell and the outer shell constitute the coolant flow channel, and the radiation conversion target is located inside the inner shell.

[0013] The technical solution is further configured such that a sealing disk is provided on the top of the inner shell, and a plurality of first slots are provided on the outer circumference of the sealing disk at intervals. A sealing ring is fitted on the outer shell, and a second slot is provided on the inner circumference of the sealing ring at intervals. A wedge block is provided between adjacent second slots, and the distance between two adjacent first slots is less than the length of the second slot.

[0014] The technical solution is further configured such that the outer shell is provided with a sealing cylinder that drives the sealing ring to rotate along the central axis of the outer shell.

[0015] The technical solution is further configured such that the target changing unit also includes a lifting element, which is connected to the inner shell and is used to lift or lower the radiation conversion target.

[0016] The technical solution is further configured such that the target loading assembly, the target unloading assembly, and the positioning platform are arranged in a straight line on a movable tray, and a target compartment is provided between the target loading assembly and the positioning platform.

[0017] The technical solution is further configured such that the target compartment is provided with a compartment opening on the side corresponding to the target loading assembly and on the side corresponding to the target unloading assembly, and the compartment opening is provided with a compartment door that can rotate relative to the target compartment.

[0018] The beneficial effects of this invention are:

[0019] 1. The target body adopts a stacked target structure composed of multiple target pieces. Coolant can flow between adjacent target pieces to reduce the temperature of the target pieces and facilitate heat dissipation of the target body.

[0020] 2. According to the trend of electron beam energy deposition density in the target, the thickness of the target sheet changes from thin to thick, so that the target sheet with high electron beam energy deposition density can be cooled better, thus protecting the radiation conversion target while ensuring high neutron yield.

[0021] 3. The radiation conversion target is located inside the coolant flow channel. The coolant flows unidirectionally from top to bottom in the gap between the target pieces to cool and soak the bombarded end face of the target piece, ensuring complete cooling of the target piece.

[0022] 4. When the sealing ring rotates under the drive of the sealing cylinder, the wedge block applies force to the sealing disc to improve the sealing performance between the sealing disc and the outer casing and prevent coolant leakage.

[0023] 5. Remote and automated replacement of radiation conversion targets is achieved by using lifting components, target loading components, and target unloading components, avoiding radiation damage to operators from close contact.

[0024] 6. It is applicable to radiation conversion targets of any solid target material, and is also suitable for cooling targets for the production of various radioisotope drugs. It only requires replacing the radiation conversion target in the mounting hole with the raw material target required for the production of radioisotope drugs, making it highly versatile. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 This is a longitudinal sectional view of the overall structure of the present invention;

[0027] Figure 3 This is a schematic diagram of the radiation conversion target in this invention;

[0028] Figure 4 This is a schematic diagram of the target cooling unit in this invention;

[0029] Figure 5 yes Figure 4 Sectional view of AA;

[0030] Figure 6 This is a schematic diagram of the sealing ring in this invention;

[0031] Figure 7 This is a schematic diagram of the inner shell in this invention;

[0032] Figure 8 This is a schematic diagram of the tray in this invention.

[0033] In the attached diagram: 100-Radiation conversion target, 101-Target body, 102-Target plate, 103-Target support, 104-Crimp, 200-Target cooling unit, 201-Outer shell, 202-Inner shell, 203-Sealing retaining ring, 204-Sealing cylinder, 205-Inlet pipe connector, 206-Outlet pipe connector, 207-Coolant injection chamber, 208-Coolant injection flow chamber, 209-Coolant output flow chamber, 210-Coolant output chamber, 211-Second slot, 212-Upper wedge block, 213-Lower wedge block. 214-Sealing disc, 215-First slot, 216-First inlet / outlet liquid sealing disc, 217-Positioning hole, 218-Mounting hole, 300-Lifting element, 400-Pattern, 401-Target unloading assembly, 402-Target loading assembly, 403-Positioning platform, 404-Target chamber, 405-Bed door, 406-Connecting rod, 407-Bed door pushing element, 500-Radiation shielding layer, 501-Electron beam vacuum pipe, 502-Neutron transmission channel, 600-Lifting bracket, 700-Target changing bracket, 800-Shielding layer bracket. Detailed Implementation

[0034] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings; therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0035] Example 1:

[0036] like Figures 1-2 As shown, a target system for a neutron source includes a radiation conversion target 100, a target cooling unit 200, and a target replacement unit. The target cooling unit 200 has a coolant flow channel inside, the radiation conversion target 100 is located inside the coolant flow channel, the radiation conversion target 100 and the target cooling unit 200 are located inside a radiation shielding layer 500, the radiation shielding layer 500 is located above a shielding layer support 800, and the target replacement unit is located above the radiation shielding layer 500 and above a target replacement support 700.

[0037] like Figure 3 As shown, the radiation conversion target 100 includes a target body 101 and a target holder 103. The target body 101 is formed by stacking multiple target plates 102. A target plate gap is formed between adjacent target plates 102 to allow coolant to flow. The coolant can flow between adjacent target plates 102 to reduce the target plate temperature and facilitate heat dissipation of the target body.

[0038] The technical solution is further configured such that, along the direction of electron beam transmission, the thickness of the multiple target sheets 102 varies from thin to thick.

[0039] It is worth noting that when a high-power electron beam bombards the target 101, most of its energy is converted into heat and deposited on the target 101, with only a small portion of the energy being transferred away via gamma rays and neutrons. Based on the energy deposition density distribution pattern of the electron beam on the target 101, the electron beam energy deposition density is highest at the front end (the part bombarded by the electron beam first) and gradually decreases at the rear end (the part bombarded by the electron beam later). Dividing the target 101 into sections of different thicknesses and arranging them in ascending order of thickness allows for better cooling of the target sheet 102 with high electron beam energy deposition density, reducing its operating temperature and ensuring a high neutron yield while protecting the radiation conversion target 100. Specifically, the total thickness of the target 101 is determined by the neutron yield calculated by Monte Carlo, and the thickness at which the neutron yield is maximized is the total thickness of the target 101. The thickness of a single target 102 is obtained by iterative optimization of the electron beam energy deposition density distribution calculated by Monte Carlo and the temperature distribution calculated by thermal analysis.

[0040] The technical solution is further configured such that the target sheet 102 is made of tungsten, and the surface of the target sheet 102 is coated with a corrosion-resistant layer, the material of which is Cr-N, Cr-C or Cr-CN.

[0041] It is worth noting that the coolant after being ionized by the electron beam has a certain degree of corrosivity to the target 102. A corrosion-resistant layer is coated on the outer surface of the target 102, thereby improving the corrosion resistance and wear resistance of the target 102 and increasing the service life of the radiation conversion target 100.

[0042] The technical solution is further configured such that the target holder 103 has an internal cavity for loading the target 101, and along the transmission direction of the electron beam, the front end and rear end of the target holder 103 have through holes that communicate with the cavity, so as to ensure that the electron beam is not blocked by the target holder 103.

[0043] This technical solution is further configured such that the cavity wall of the receiving cavity is provided with a plurality of protruding retaining protrusions 104, and adjacent retaining protrusions 104 form retaining grooves for receiving the target piece 102. At the same time, the top of the target holder 103 is provided with an installation opening, and the bottom of the target holder 103 is provided with a coolant flow gap, which is connected to the gap between the target piece.

[0044] In other words, the target holder 103 is open from front to back, open from top to bottom, and closed from left to right. The coolant flows unidirectionally from top to bottom in the gap between the target pieces to cool and soak the bombarded end face of the target piece 102, ensuring that the target piece 102 is completely cooled. The coolant flowing through the bombarded end face of the target piece 102 is discharged from the target holder 103 through the coolant flow gap.

[0045] like Figure 1 and Figure 2 As shown, the radiation shielding layer 500 is provided with an electron beam vacuum channel 501 and a neutron transmission channel 502. The electron beam vacuum channel 501 is set at the front end of the radiation conversion target 100 to ensure that the electron beam is not obstructed, and the neutron transmission channel 502 is set at the rear end of the radiation conversion target 100.

[0046] Specifically, the radiation shielding layer 500 mainly consists of gamma-ray shielding and neutron shielding. The gamma-ray shielding layer is mainly made of cast iron and lead for protection, while the neutron shielding uses boron-containing polyethylene to absorb excess neutrons. The entire radiation shielding layer 500 has a hexagonal shape with a hole cut out in the geometric center to install the target cooling unit 200.

[0047] Example 2:

[0048] like Figure 1 , Figures 4 to 7 As shown, the target cooling unit 200 includes an inner shell 202 and an outer shell 201 with a clearance fit. The interior of the inner shell 202 and the gap between the inner shell 202 and the outer shell 201 constitute the coolant flow channel. The radiation conversion target 100 is located inside the inner shell 202.

[0049] Specifically, the outer shell 201 and the inner shell 202 are fitted together to form a coolant injection chamber 207, a coolant output chamber 210, and a coolant output flow chamber 209. The top of the inner shell 202 communicates with the coolant injection chamber 207, and its interior is the coolant injection flow chamber 208, with the radiation conversion target 100 located at the bottom of the coolant injection flow chamber 208. Meanwhile, the coolant injection chamber 207 and the coolant output chamber 210 are separated, and the coolant output chamber 210 communicates with the coolant injection flow chamber 208 through the coolant output flow chamber 209. In other words, the coolant injection chamber 207, the coolant injection flow chamber 208, the coolant output flow chamber 209, and the coolant output chamber 210 constitute the coolant flow channel.

[0050] This technical solution is further configured such that the inner shell 202 has a closed top and an open bottom structure, with an inlet hole on its side wall communicating with the coolant injection chamber 207, and a mounting hole 218 at its bottom for placing the radiation conversion target 100. Correspondingly, the outer shell 201 has an open top and a closed bottom structure, with an electron beam transmission window on its side wall facing the mounting hole 218. In addition, the outer shell 201 is provided with an inlet pipe connector 205 communicating with the coolant injection chamber 207 and an outlet pipe connector 206 communicating with the coolant output chamber 210.

[0051] The technical solution is further configured such that a sealing disk 214 is provided on the top of the inner shell 202, and a plurality of first slots 215 spaced apart are provided on the outer circumference of the sealing disk 214. A sealing ring 203 is fitted on the outer shell 201, and a second slot 211 spaced apart is provided on the inner circumference of the sealing ring 203. A wedge block is provided between adjacent second slots 211. Specifically, the wedge block includes an upper wedge block 212 and a lower wedge block 213. The distance between two adjacent first slots 215 is less than the length of the second slot 211.

[0052] The technical solution is further configured such that the outer shell 201 is provided with a sealing cylinder 204 that drives the sealing ring 203 to rotate along the central axis of the outer shell 201.

[0053] It is worth noting that when the sealing ring 203 rotates under the drive of the sealing cylinder 204, the upper wedge block 212 and the lower wedge block 213 rotate under the drive of the sealing ring 203 and apply force to the sealing disc 214 to improve the sealing performance between the sealing disc 214 and the outer shell 201, prevent coolant leakage, and achieve the purpose of water circuit sealing.

[0054] This technical solution is further configured such that the inner housing 202 is also provided with a first inlet / outlet sealing plate 216, and the first inlet / outlet sealing plate 216 is located below the liquid inlet hole. The first inlet / outlet sealing plate 216 is provided with a positioning hole 217. Correspondingly, the inner wall of the outer housing 201 is provided with a second inlet / outlet sealing plate for supporting the first inlet / outlet sealing plate 216. The second inlet / outlet sealing plate is provided with a positioning pin that is embedded in the positioning hole 217. That is to say, the first inlet / outlet sealing plate 216 and the second inlet / outlet sealing plate cooperate to separate the coolant injection chamber 207 and the coolant output chamber 210.

[0055] In use, the inner housing 202 is inserted coaxially downwards from the top of the outer housing 201. When the positioning pin is inserted into the positioning hole 217, the inner housing 202 is precisely positioned on the axis of the outer housing 201. The sealing cylinder 204 is activated, and under the drive of the sealing cylinder 204, the sealing ring 203 rotates, thereby sealing the water inlet passage. At the same time, coolant is injected into the coolant injection chamber 207 through the inlet pipe connector 205, and flows into the coolant injection flow chamber 208 through the inlet hole. The coolant in the coolant injection flow chamber 208 is squeezed into the gap between the target plates, and the heat deposited on the radiation conversion target 100 is carried away by the coolant. The coolant flowing out from the gap between the target plates is injected into the outer housing 201, and then flows into the coolant output chamber 210 through the coolant output flow chamber 209, and flows out through the outlet pipe connector 206, thereby forming the cooling water passage of the radiation conversion target 100.

[0056] Example 3:

[0057] like Figure 1 , Figure 5 as well as Figure 8 As shown, the target replacement unit moves the radiation conversion target 100 in the coolant flow channel to the positioning platform 403. The positioning platform 403 is provided with a target loading assembly 402 and a target unloading assembly 401 on both sides. The target unloading assembly 401 is used to disassemble the radiation conversion target before replacement, and the target loading assembly 402 is used to install the radiation conversion target after replacement.

[0058] This technical solution is further configured such that the target changing unit also includes a lifting element 300, which is connected to the inner shell 202 and is used to lift or lower the radiation conversion target 100. Simultaneously, the lifting element 300 is mounted on a lifting bracket 600, which in turn is mounted on a target changing bracket 700.

[0059] This technical solution is further configured such that the target loading assembly 402, the target unloading assembly 401, and the positioning platform 403 are collinearly arranged on the movable tray 400. Specifically, the target changing bracket 700 is provided with a moving guide rail, and the tray 400 moves along the moving guide rail under the drive of a moving cylinder. Preferably, multiple target loading assemblies 402, target unloading assemblies 401, and positioning platforms 403 are provided.

[0060] The technical solution is further configured such that a target chamber 404 is provided between the target loading assembly 402 and the positioning platform 403. The target chamber 404 has a chamber opening on the side corresponding to the target loading assembly 402 and the side corresponding to the target unloading assembly 401. A chamber door 405 that can rotate relative to the target chamber 404 is provided at the chamber opening.

[0061] It is worth noting that the target unloading assembly 401 uses a target unloading cylinder. When the target unloading cylinder extends, it can push the radiation conversion target before replacement from the mounting hole 218 into the target chamber 404. Correspondingly, the target loading assembly 402 uses a target loading cylinder. When the target loading cylinder extends, it can push the replaced radiation conversion target from the other target chamber 404 into the mounting hole 218.

[0062] The technical solution is further configured such that the pallet 400 is also provided with a door pushing element 407, and the door pushing element 407 is connected to the door 405 through a connecting rod 406.

[0063] It is worth noting that the door pushing element 407 is a door pushing cylinder. The cylinder body of the door pushing cylinder is connected to the tray 400, and its piston end is connected to the connecting rod 406 through a connector. The connecting rod 406 extends along the direction of movement of the tray 400. At the same time, a U-shaped mounting port is opened on the connecting rod 406, and the door 405 is installed in the U-shaped mounting port through a handle. Specifically, the door 405, the connection point between the door 405 and the target compartment 404, and the connection point between the connecting rod 406 and the door 405 constitute a lever structure, and the connection point between the door 405 and the target compartment 404 serves as the fulcrum of the lever structure.

[0064] In use, the lifting element 300 is activated to lift the inner housing 202, and the door pushing element 407 is activated to open the door 405. The pallet 400 is moved to align the radiation conversion target 100 in the mounting hole 218 with the idle target compartment 404. The target unloading assembly 401 is activated to push the radiation conversion target before replacement into the target compartment 404, and then the unloading assembly 401 is reset. The pallet 400 is moved again to align the mounting hole 218 with the target compartment 404 containing the replaced radiation conversion target. The target loading assembly 402 is activated to push the replaced radiation conversion target into the mounting hole 218, and then the loading assembly 402 is reset. With the pallet 400 reset, the lifting element 300 lifts the inner housing 202 and the replaced radiation conversion target back to their original positions and then installs them inside the outer housing 201. The door pushing element 407 is activated to close the door 405, completing the entire target replacement process.

[0065] The present invention has been described in detail above. The above description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of this application should still fall within the scope of the present invention.

Claims

1. A target system for a neutron source, characterized in that, include: The radiation conversion target is composed of multiple target plates stacked together, with gaps between adjacent target plates forming a channel for coolant flow. The target cooling unit has a coolant flow channel inside, and the radiation conversion target is located inside the coolant flow channel. The target cooling unit includes an inner shell and an outer shell with a clearance fit. The outer shell and the inner shell are clearance fit to form a coolant injection chamber, a coolant output chamber, and a coolant output flow chamber. The top of the inner shell is connected to the coolant injection chamber, and its interior is the coolant injection flow chamber. The radiation conversion target is located at the bottom of the coolant injection flow chamber. The coolant flows unidirectionally from top to bottom in the gap between the target plates. The coolant injection chamber and the coolant output chamber are separated. The coolant output chamber is connected to the coolant injection flow chamber through the coolant output flow chamber. The inner shell has a closed top and an open bottom structure. Its side wall has a liquid inlet hole that communicates with the coolant injection chamber. Its bottom has a mounting hole for placing the radiation conversion target. The outer shell has an open top and a closed bottom structure. Its side wall has an electron beam transmission window facing the mounting hole. The system also includes a target replacement unit, which moves the radiation conversion target in the coolant flow channel to the positioning platform. The target replacement unit also includes a lifting element connected to the inner shell for lifting or lowering the radiation conversion target. The positioning platform is equipped with a target loading assembly and a target unloading assembly on both sides. The target unloading assembly is used to disassemble the radiation conversion target before replacement, and the target loading assembly is used to install the replaced radiation conversion target.

2. The target system for a neutron source according to claim 1, characterized in that, It also includes a radiation shielding layer, with the radiation conversion target and the target cooling unit located inside the radiation shielding layer, and the target replacement unit located above the radiation shielding layer.

3. A target system for a neutron source according to claim 2, characterized in that, The radiation shielding layer is provided with an electron beam vacuum channel and a neutron transmission channel. The electron beam vacuum channel is set at the front end of the radiation conversion target, and the neutron transmission channel is set at the rear end of the radiation conversion target.

4. A target system for a neutron source according to claim 1, characterized in that, Along the direction of electron beam propagation, the thickness of multiple target sheets varies from thin to thick.

5. A target system for a neutron source according to claim 1, characterized in that, The inner shell is provided with a sealing disc at the top, and the outer circumference of the sealing disc is provided with a plurality of spaced first slots. The outer shell is fitted with a sealing ring, and the inner circumference of the sealing ring is provided with spaced second slots. A wedge block is provided between adjacent second slots, and the distance between two adjacent first slots is less than the length of the second slot.

6. A target system for a neutron source according to claim 5, characterized in that, The outer casing is equipped with a sealing cylinder that drives the sealing ring to rotate along the central axis of the outer casing.

7. A target system for a neutron source according to claim 1, characterized in that, The target loading assembly, the target unloading assembly, and the positioning platform are arranged in a straight line on a movable tray, and a target compartment is provided between the target loading assembly and the positioning platform.

8. A target system for a neutron source according to claim 7, characterized in that, The target compartment is provided with an opening on the side corresponding to the target loading assembly and the side corresponding to the target unloading assembly, and the opening is provided with a door that can rotate relative to the target compartment.

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