A neutron generating device

Abstract

The present application relates to the technical field of neutron irradiation, and provides a neutron generating device, comprising a graphite stack, a neutron source, a shielding shell and a plurality of movable plates, wherein the graphite stack forms a radiation cavity and a detection cavity, the neutron source is arranged in the radiation cavity, the neutron beam emitted by the neutron source is moderated by the graphite stack to form thermal neutrons, and a thermal neutron reference radiation field is generated, the shielding shell forms a accommodating space, the graphite stack is arranged in the accommodating space, the shielding shell is provided with a plurality of beam ports connected to the accommodating space, the plurality of movable plates are movably connected to the shielding shell to selectively open or cover the beam ports, wherein the thermal neutron reference radiation field forms an inner calibration area and an outer calibration area, and detector traceability is achieved by placing a detector in the inner calibration area or the outer calibration area.

Description

Technical Field

[0001] The present application relates to the technical field of neutron irradiation, and in particular to a neutron generating device. Background Art

[0002] In related technologies, based on 6 Li(n,α), 3 He(n,p), 10 B(n,α), 235 Neutron measuring instruments based on the principle of nuclear reaction detection such as U(n,f) and H(n,p) have a large reaction cross section at the thermal neutron energy point. Accurate calibration of measuring instruments requires the use of standard thermal neutron reference radiation fields. Currently, the first-level ionizing radiation station has established a unique national defense 0.1 MeV ~ 20MeV (mega electron volts, 1MeV = 10 6 eV) monoenergetic neutron injection parameter value transfer technology system, and is developing keV (kilo electron volt, 1keV=10 3 There is still a lack of thermal neutron energy point parameters and a lack of thermal neutron energy point reference radiation in China, which makes it difficult to trace the detector. Summary of the Invention

[0003] In view of this, the present application hopes to provide a neutron generating device that can provide a thermal neutron reference radiation field for calibrating detectors and realizing detector traceability.

[0004] The present invention provides a neutron generating device, comprising:

[0005] A graphite stack is formed with a radiation cavity and a detection cavity;

[0006] A neutron source is disposed in the radiation cavity, wherein the neutron beam emitted by the neutron source is moderated by the graphite pile to form thermal neutrons;

[0007] A shielding shell is formed with a receiving space, the graphite stack is arranged in the receiving space, and the shielding shell is provided with a plurality of beam ports communicating with the receiving space;

[0008] A plurality of movable plates are movably connected to the shielding shell to selectively open or cover the beam port, wherein the detector is arranged in the detection cavity or on the propagation path of thermal neutrons emitted from the beam port.

[0009] In some embodiments, the shielding shell includes a fixed frame and a plurality of shielding plates, the fixed frame is formed with a plurality of installation windows, and the shielding plates are connected to the fixed frame and shield the installation windows to jointly define the accommodating space.

[0010] In some embodiments, the fixed frame is formed with a slide groove, and the opposite ends of the movable plate along the first direction are accommodated in the slide groove, so that the movable plate slides along the second direction to open or cover the beam port, wherein the first direction and the second direction are perpendicular to each other.

[0011] In some embodiments, the neutron generating device includes a first protective plate and a second protective plate, wherein the first protective plate is disposed on a side of the movable plate away from the shielding shell, and the second protective plate is disposed on a side of the first protective plate away from the shielding shell.

[0012] In some embodiments, the neutron generating device includes a crucible assembly, the neutron source is placed in the crucible assembly, the graphite stack forms a first socket connected to the radiation cavity, the shielding shell forms a first positioning port connected to the first socket, the crucible assembly enters the radiation cavity through the first positioning port and the first socket, and shields the first socket.

[0013] In some embodiments, the crucible assembly includes:

[0014] The crucible holder is formed with an outer limiting cavity and a first opening communicating with the outer limiting cavity;

[0015] a crucible, entering the outer limiting cavity through the first opening, the crucible forming an inner limiting cavity and a second opening communicating with the inner limiting cavity, the neutron source being disposed in the inner limiting cavity;

[0016] The limiting member includes a rod body, and the rod body enters the inner limiting cavity through the second opening.

[0017] In some embodiments, the limiting member includes a protective sleeve, and the protective sleeve is wrapped around the outer surface of the rod body.

[0018] In some embodiments, the protective sleeve is formed with a first wiring groove extending along the axial direction of the crucible.

[0019] In some embodiments, the shielding shell includes a fixing frame and a first positioning plate, and the first positioning plate is detachably connected to the fixing frame to open or cover the first positioning opening.

[0020] In some embodiments, the neutron generating device includes a container, the detector is placed in the container, the graphite stack forms a second socket connected to the detection cavity, the shielding shell forms a second positioning port connected to the second socket, and the container can be pulled in and out of the detection cavity along the horizontal direction through the second positioning port and the second socket.

[0021] In some embodiments, the container is formed with a storage cavity and a second wiring groove communicating with the storage cavity, and the detector is disposed in the storage cavity.

[0022] In some embodiments, the shielding shell includes a fixing frame and a second positioning plate, and the second positioning plate is detachably connected to the fixing frame to open or cover the second positioning opening.

[0023] In some embodiments, the graphite stack is hexahedral, and the neutron source is disposed at the geometric center of the graphite stack.

[0024] In some embodiments, the graphite stack includes multiple graphite blocks, each of which is hexahedral. Multiple graphite blocks are arranged in the left-right direction to form a first unit, multiple first units are arranged in the front-back direction to form a second unit, and multiple second units are stacked in the top-bottom direction to form the graphite stack.

[0025] The neutron generator provided in the embodiments of the present application utilizes a graphite stack formed by stacking graphite, with a neutron source placed within the stack. Graphite has a high scattering cross section and a low absorption cross section for neutron beams, and is less contaminated by other radiation, enabling the formation of a more stable thermal neutron reference radiation field compared to related technologies. The thermal neutron reference radiation field forms an internal calibration region within the detection cavity and an external calibration region along the propagation path of thermal neutrons passing through the beam port. Detector traceability is achieved by placing detectors in either the internal or external calibration region for measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of a portion of a neutron generating device according to some embodiments of the present application;

[0027] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0028] Figure 3 for Figure 1 Enlarged view of point B in the middle;

[0029] Figure 4 A schematic structural diagram of the beam port shielding of a shielding shell in some embodiments of the present application;

[0030] Figure 5 A schematic structural diagram of a shielding shell with a beam port opened in some embodiments of the present application;

[0031] Figure 6 Schematic diagram of a thermal neutron reference radiation field in some embodiments of the present application, where the dashed line represents the neutron beam, the circular dashed box represents the inner calibration area, and the quadrilateral dashed box represents the outer calibration area;

[0032] Figure 7A schematic structural diagram of the connection between the crucible holder and the crucible in some embodiments of the present application;

[0033] Figure 8 A schematic structural diagram of the connection between the crucible and the limiting member in some embodiments of the present application;

[0034] Figure 9 Schematic diagram of the structure of the graphite stack in some embodiments of the present application;

[0035] Figure 10 Schematic diagram of the structure of the connection between the container and the locking member in some embodiments of the present application.

[0036] Description of Reference Numerals

[0037] Neutron generator 100; graphite stack 10; radiation cavity 10a; detection cavity 10b; first socket 10c; second socket 10d; avoidance space 10e; locking member 11; graphite block 12; first unit 13; second unit 14; neutron source 20; shielding shell 30; accommodating space 30a; beam port 30b; first positioning port 30c; second positioning port 30d; fixing frame 31; installation window 31a; shielding plate 32; first positioning plate 33; second positioning plate 34; Second positioning plate 34; movable plate 40; first protective plate 50; second protective plate 60; crucible assembly 70; crucible support 71; outer limiting cavity 71a; first opening 71b; first limiting platform 711; crucible 72; inner limiting cavity 72a; second opening 72b; flange 721; second limiting platform 722; limiting member 73; rod body 731; top cover 733; container 80; storage cavity 80a; second wiring groove 80b; gripping member 90; connecting member 91. DETAILED DESCRIPTION

[0038] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0039] The various specific technical features and embodiments described in the specific implementation methods can be combined in any suitable manner unless there is any contradiction. For example, different implementation methods can be formed by combining different specific technical features / embodiments. In order to avoid unnecessary repetition, the various possible combinations of the specific technical features / embodiments in this application will not be described separately.

[0040] This application provides a neutron generating device 100, please refer to Figures 1 to 6, including a graphite stack 10, a neutron source 20, a shielding shell 30 and a plurality of movable plates 40, the graphite stack 10 forms a radiation cavity 10a and a detection cavity 10b, the neutron source 20 is arranged in the radiation cavity 10a, the neutron beam emitted by the neutron source 20 is slowed down by the graphite stack 10 to form thermal neutrons, the shielding shell 30 forms a accommodating space 30a, the graphite stack 10 is arranged in the accommodating space 30a, the shielding shell 30 is provided with a plurality of beam ports 30b connected to the accommodating space 30a, the plurality of movable plates 40 are movably connected to the shielding shell 30 to selectively open or cover the beam ports 30b, wherein the detector is arranged in the detection cavity 10b or on the propagation path of the thermal neutrons emitted from the beam port 30b.

[0041] Graphite has a good slowing effect on neutron beams and can weaken interfering rays such as γ The influence of radiation, etc.

[0042] The neutron generator 100 provided in the embodiments of the present application comprises a graphite stack 10 formed by stacking graphite, with a neutron source 20 placed within the stack. Graphite has a high scattering cross section and a low absorption cross section for neutron beams, and is less contaminated by other radiation, enabling the formation of a more stable thermal neutron reference radiation field compared to related technologies. The thermal neutron reference radiation field forms an internal calibration region within the detection cavity 10b and an external calibration region along the propagation path of thermal neutrons passing through the beam port 30b. Detectors are placed in either the internal or external calibration region for measurement, enabling detector traceability.

[0043] It should be noted that from the perspective of thermal neutron fluence rate measurement principle, thermal neutron fluence rate measurement is based on 197 Au(n,γ) 198 The standard cross section method for Au nuclear reactions is calculated by measuring the activity of gold activated sheets using an appropriate radioactivity measurement device. The relevant physical quantities other than the physical constants are: 197 The number of Au nuclei, the measurement time at each stage of the experiment, and the activity of the gold activated film. 197 The number of Au nuclei is calculated from the mass of the gold activation sheet, which is measured using a certified 1 / 1000000 balance. Each measurement time is determined by the instrument's built-in crystal oscillator (the electronics system time is measured using a high-stability quartz crystal oscillator that has passed net metrological verification). The activity of the gold activation sheet after exposure to the thermal neutron radiation field is measured using a radioactivity standard. Therefore, the measurement results of the neutron generator 100 of the present embodiment can be traced back to mass, time, and activity.

[0044] Exemplarily, the boron content of the graphite stack 10 is less than 1 ppm (part per million) to increase the scattering cross section for thermal neutrons.

[0045] For example, see Figure 6When the detector is located in the inner calibration area, the single detection time is set to 100s (seconds), the test is repeated 6 times, and the full spectrum effect count of the detector is recorded. Furthermore, the outer surface of the detector is wrapped with a cadmium sleeve, the single detection time is set to 100s, the test is repeated 6 times, and the full spectrum effect count of the detector is recorded. The calculation formula for the thermal neutron dose response of the detector is

[0046] ,

[0047] in, is the average value of full spectrum effect counts of the detector without cadmium cover; is the attenuation correction factor for neutrons above 0.51 eV (electron volts) in a cadmium sheath; is the average value of full spectrum effect counts of the detector wrapped in cadmium sleeve; is the conventional true value of the thermal neutron fluence rate in the inner calibration area, in cm -2 s -1 When the detector is located in the outer calibration area, the detection process and calculation method are the same as above.

[0048] In some embodiments, the number of beam ports 30b may be 2, 3, or 4, etc.

[0049] The position of the beam port 30b is not limited. For example, see Figure 4 and Figure 5 The shielding shell 30 may be roughly a hexahedral structure, and two adjacent end surfaces of the shielding shell 30 may respectively form a beam port 30 b.

[0050] For example, see Figures 4 to 6 A neutron source is formed inside the graphite stack 10, i.e., the location of the neutron source 20. An inner calibration area is formed on the right side of the neutron source. The shielding shell 30 is formed with beam ports 30b on the front and left sides, respectively, to form two outer calibration areas. The thermal neutron flux in the inner calibration area is higher, so that the detector captures more thermal neutrons (compared to the outer calibration area), which can be used to calibrate small neutron detectors such as the SP9 spherical detector. 3 He proportional counter, etc.; the neutron beam in the outer calibration area has been sufficiently slowed down, so that the thermal neutrons propagate in a parallel beam. The uniformity of the thermal neutron reference radiation field is better (compared to the inner calibration area), and it can be used to calibrate large-volume neutron metering instruments such as neutron patrol meters, etc.

[0051] Furthermore, either or both beam ports 30b can be opened simultaneously to calibrate multiple detectors, thereby improving the operating efficiency of the neutron generator 100. Furthermore, by changing the neutron source 20 to adjust the neutron fluence rate, the neutron metrology technology system within the energy range of 0.025 eV to 100 MeV can be further expanded and improved.

[0052] It should be noted that, in this application, down refers to the direction toward the ground, and up is the direction opposite to down; front refers to the direction toward the user, and back is the direction opposite to front; left refers to the side where the left hand of the user is located when the user is in front of the neutron generator 100, and right is the direction opposite to left; the front-back direction, left-right direction, and up-down direction are perpendicular to each other, and together constitute a three-dimensional vertical coordinate system.

[0053] For some examples, see Figure 4~Figure 5 The shielding shell 30 includes a fixed frame 31 and multiple shielding plates 32. The fixed frame 31 is formed with multiple installation windows 31a. The shielding plates 32 are connected to the fixed frame 31 and cover the installation windows 31a, thereby defining a receiving space 30a. The fixed frame 31 securely connects the multiple shielding plates 32, thereby improving the overall structural stability of the shielding shell 30 and enhancing the ease of assembly and disassembly of the shielding shell 30.

[0054] The fixing frame 31 can be made of an aluminum alloy to reduce interference with the neutron generator 100, and it has high strength and is easy to process. The shielding plate 32 must be made of a material that strongly absorbs neutrons and is unlikely to produce interfering radiation. For example, it can be made of a material such as boron-containing polyethylene. This allows the shielding plate 32 to be manufactured with a high boron content, thereby enhancing the radiation protection performance of the neutron generator 100.

[0055] In some embodiments, the movable plate 40 may be slidably connected to the shielding shell 30 or rotatably connected to the shielding shell 30 .

[0056] For some examples, see Figure 4 and Figure 5 The fixed frame 31 is formed with a slide groove, and the opposite ends of the movable plate 40 along the first direction are accommodated in the slide groove, so that the movable plate 40 slides along the second direction to open or cover the beam port 30b, wherein the first direction and the second direction are perpendicular to each other.

[0057] For example, please refer to Figure 4 and Figure 5 The fixed frame 31 is formed with a sliding groove along the vertical direction, so that the movable plate 40 can open or cover the beam port 30b by simply moving parallel to the movable plate 40, thereby facilitating the manipulation of the movable plate 40. In this embodiment, the first direction may be the vertical direction, and the second direction may be the left-right direction or the front-back direction.

[0058] In one embodiment, the neutron generating device 100 includes a controller, and the movable plate 40 is electrically connected to the controller. When the neutron generating device 100 is in operation, the movable plate 40 can be remotely driven to slide by the controller to improve the safety of the neutron generating device 100.

[0059] For some examples, see Figure 4The neutron generating device 100 includes a first protective plate 50 and a second protective plate 60 . The first protective plate 50 is arranged on a side of the movable plate 40 close to the shielding shell 30 , and the second protective plate 60 is arranged on a side of the first protective plate 50 close to the shielding shell 30 .

[0060] Exemplarily, the first protective plate 50 is detachably connected to the shielding shell 30, and the second protective plate 60 is detachably connected to the shielding shell 30. By adding the first protective plate 50, shielding of gamma rays is achieved, and by adding the second protective plate 60, shielding of neutrons with energy below 0.5eV is achieved.

[0061] The first shield 50 needs to have a strong absorption effect on gamma rays and generate less interference radiation, such as lead. The second shield 60 needs to have a strong absorption effect on neutrons and generate less interference radiation, such as cadmium, to absorb neutrons with energy below 0.5 eV.

[0062] For some examples, see Figures 7 to 9 The neutron generating device 100 includes a crucible assembly 70, with a neutron source 20 placed within the crucible assembly 70. The graphite stack 10 is formed with a first insertion port 10c communicating with the emission cavity 10a. The shielding shell 30 is formed with a first positioning port 30c communicating with the first insertion port 10c. The crucible assembly 70 enters the emission cavity 10a through the first positioning port 30c and the first insertion port 10c, shielding the first insertion port 10c. In other words, placing the neutron source 20 within the crucible assembly 70 and then placing the crucible assembly 70 within the emission cavity 10a facilitates positioning of the neutron source 20 within the graphite stack 10. Furthermore, direct contact between the operator and the neutron source 20 is reduced during loading and unloading, thereby improving safety.

[0063] For example, see Figure 5 and Figure 9 A first socket 10c is provided on the top of the graphite stack 10, and a first positioning port 30c is provided on the top of the shielding shell 30, and the first positioning port 30c is opposite to the first socket 10c. In this way, the crucible assembly 70 is placed in the radiation cavity 10a from top to bottom, which improves the convenience of loading and unloading the crucible assembly 70.

[0064] The crucible assembly 70 may be made of graphite, which has a good moderation effect on neutrons, is not easily absorbed, and generates less interfering radiation.

[0065] For some examples, see Figure 7 and Figure 8Crucible assembly 70 includes a crucible holder 71, a crucible 72, and a retaining member 73. Crucible holder 71 defines an outer retaining cavity 71a and a first opening 71b communicating with the outer retaining cavity 71a. Crucible 72 enters the outer retaining cavity 71a through the first opening 71b. Crucible 72 also defines an inner retaining cavity 72a and a second opening 72b communicating with the inner retaining cavity 72a. Neutron source 20 is disposed within the inner retaining cavity 72a. Retaining member 73 includes a rod 731, which enters the inner retaining cavity 72a through the second opening 72b. This allows neutron source 20 to be replaced quickly and conveniently by simply removing crucible 72 (not shown).

[0066] For example, see Figure 7 The outer surface of the crucible 72 cooperates with the wall of the outer limiting cavity 71a, and the outer surface of the rod body 731 cooperates with the wall of the inner limiting cavity 72a. In other words, the crucible support 71 wraps the outer surface of the crucible 72, and the crucible 72 wraps the outer surface of the rod body 731. In this way, the stability of the crucible assembly 70 is enhanced.

[0067] In one embodiment, please refer to Figure 7 The inner surface of the crucible holder 71 is formed with a first limiting platform 711, and the outer surface of the crucible 72 is provided with a flange 721, which abuts against the first limiting platform 711 and covers the first opening 71b. In this way, the stability of the crucible holder 71 and the crucible 72 is enhanced.

[0068] Exemplarily, taking the plane perpendicular to the axial direction of the crucible 72 as the cross section, the cross sections of the flange 721 and the first opening 71b are both circular, wherein the diameter R1 of the cross section of the flange 721 is 170 mm (millimeter), and the diameter R2 of the cross section of the first opening 71b is 170 mm, that is, R1=R2. In this way, the gap between the flange 721 and the first opening 71b is reduced, and the influence of the gap on the moderation effect of the neutron generating device 100 is reduced.

[0069] In one embodiment, please refer to Figure 8 The retaining member 73 includes a top cover 733, which is disposed on the side of the rod 731 opposite the neutron source 20. A second retaining platform 722 is formed on the inner surface of the crucible 72. The top cover 733 abuts against the second retaining platform 722 and covers the second opening 72b. This enhances the stability of both the crucible 72 and the retaining member 73.

[0070] For example, taking the plane perpendicular to the axial direction of the crucible 72 as the cross section, the cross sections of the top cover 733 and the second opening 72b are both circular, wherein the diameter R3 of the cross section of the top cover 733 is 100 mm, and the diameter R4 of the cross section of the second opening 72b is 100 mm, that is, R3=R4. In this way, the gap between the top cover 733 and the second opening 72b is reduced, and the influence of the gap on the slowing down effect of the neutron generating device 100 is reduced.

[0071] For example, see Figure 2 The neutron generating device 100 includes a holding member 90 , and both the flange 721 and the top cover 733 are provided with the holding member 90 , which improves the convenience of loading and unloading the crucible 72 and the limiting member 73 .

[0072] In some embodiments, the stopper 73 includes a protective sleeve that surrounds the outer surface of the rod 731. When the rod 731 is inserted into and removed from the inner limiting cavity 72a, the protective sleeve prevents the rod 731 from breaking due to friction, thereby preventing graphite residue from remaining in the inner limiting cavity 72a and making it impossible to remove the neutron source 20.

[0073] In some embodiments, the protective sleeve is formed with a first wiring groove extending along the axial direction of the crucible 72 , which is used to place the pulling wire of the neutron source 20 .

[0074] For some examples, see Figure 4 and Figure 5 The shielding shell 30 includes a fixed frame 31 and a first positioning plate 33. The first positioning plate 33 is detachably connected to the fixed frame 31 to open or block the first positioning opening 30c. Thus, when the neutron generator 100 is in operation, the first positioning plate 33 blocks the first positioning opening 30c, preventing part of the neutron beam from being emitted through the first positioning opening 30c. This improves the calibration accuracy and radiation protection performance of the neutron generator 100.

[0075] Exemplarily, the fasteners are detachably provided on the fixing frame 31 and the first positioning plate 33. For example, the fasteners are provided from top to bottom on the first positioning plate 33 and the fixing frame 31. The fasteners enhance the connection stability between the two, making it difficult for the first positioning plate 33 to loosen, while also facilitating the installation and removal of the first positioning plate 33.

[0076] Fasteners include but are not limited to screws or bolts, etc.

[0077] For some examples, see Figure 5 、 Figure 9 and Figure 10The neutron generator 100 includes a container 80, a detector placed within the container 80, a second socket 10d formed in communication with the detection cavity 10b on the graphite stack 10, and a second positioning opening 30d formed in communication with the second socket 10d on the shielding shell 30. The container 80 can be pulled horizontally into and out of the detection cavity 10b via the second positioning opening 30d and the second socket 10d. In other words, placing the detector within the container 80 and then within the detection cavity 10b facilitates positioning the detector within the graphite stack 10, allowing the detector to be accurately positioned within the internal calibration zone, thereby improving the calibration accuracy of the neutron generator 100. Furthermore, the detector can be quickly replaced by simply removing the container 80 from the detection cavity 10b, making operation convenient and improving operational efficiency.

[0078] In one embodiment, please refer to Figure 10 The graphite stack 10 includes a locking member 11, which is disposed in the avoidance space 10e defined by the graphite stack 10 and forms a detection cavity 10b and a second insertion port 10d. Thus, the stability of the container 80 can be improved.

[0079] For example, please refer to Figure 10 The locking member 11 is U-shaped and is detachably disposed in the avoidance space 10e (not shown). Thus, by replacing the locking member 11, the space size of the detection cavity 10b can be adapted to containers 80 of different sizes, that is, suitable for detectors of different sizes.

[0080] In one embodiment, please refer to Figure 3 The neutron generator 100 includes a gripping member 90. The container 80 and the locking member 11 are each provided with a gripping member 90, so that the container 80 and / or the locking member 11 can be withdrawn from the detection cavity 10b. This improves the convenience of loading and unloading the container 80 and the locking member 11.

[0081] The material of the locking member 11 can be graphite, which has a good moderation effect on neutrons, is not easily absorbed and generates less interfering rays.

[0082] For some examples, see Figure 10 Container 80 is formed with a storage cavity 80a and a second wiring groove 80b communicating with storage cavity 80a. The detector is disposed within storage cavity 80a. Thus, the position of the detector within storage cavity 80a can be used to precisely locate the detector within the inner calibration area. Furthermore, second wiring groove 80b is used to house wiring electrically connected to the detector.

[0083] For some examples, see Figure 4 and Figure 5The shielding shell 30 includes a fixed frame 31 and a second positioning plate 34. The second positioning plate 34 is detachably connected to the fixed frame 31 to open or block the second positioning opening 30d. Thus, when the neutron generator 100 is in operation, the second positioning plate 34 blocks the second positioning opening 30d, preventing part of the neutron beam from being emitted through the second positioning opening 30d. This improves the calibration accuracy and radiation protection performance of the neutron generator 100.

[0084] For example, the fasteners are detachably provided on the fixed frame 31 and the second positioning plate 34. For example, the fasteners are provided horizontally on the second positioning plate 34 and the fixed frame 31. The fasteners enhance the connection between the two, making it difficult for the second positioning plate 34 to become loose, while also facilitating the installation and removal of the second positioning plate 34.

[0085] Fasteners include but are not limited to screws or bolts, etc.

[0086] For some examples, see Figure 9 The graphite stack 10 is in a hexahedral shape, and the neutron source 20 is arranged at the geometric center of the graphite stack 10 .

[0087] For some examples, see Figure 9 The graphite stack 10 includes a plurality of hexahedral graphite blocks 12. The graphite blocks 12 are arranged in a left-right direction to form a first unit 13. The first units 13 are arranged in a right-left direction to form a second unit 14. The second units 14 are stacked in a top-to-bottom direction to form the graphite stack 10. This facilitates assembly of the graphite blocks 12 to form the graphite stack 10. Furthermore, the hexahedral graphite blocks 12 have smooth outer surfaces, making them easy to fit together and reducing gaps within the graphite stack 10.

[0088] For example, see Figure 9 Each graphite block 12 is provided with a number, thus improving the assembly efficiency of the graphite blocks 12.

[0089] In one embodiment, a fastener is passed through two adjacent graphite blocks 12 in the vertical direction to enhance the stability of the graphite stack 10 .

[0090] Further, see Figure 9 The neutron generator includes a connector. In the same horizontal plane, at least two adjacent graphite blocks 12 are connected by the connector. The fasteners are horizontally passed through the connector and the graphite blocks 12, thereby further enhancing the stability of the graphite stack 10.

[0091] It should be noted that no connectors are used to connect the graphite blocks 12 on both sides of the locking member 11 in the horizontal direction, so as to facilitate replacement of the locking member 11 .

[0092] In the description of this specification, the reference terms "some embodiments", "one embodiment" and "exemplarily" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0093] The various embodiments / implementations provided in this application can be combined with each other without causing any contradiction. The above description is only a preferred embodiment of this application and is not intended to limit this application. For those skilled in the art, this application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application shall be included in the scope of protection of this application.

Claims

1. A neutron generating device, characterized in that: include: A graphite stack is formed with a radiation cavity and a detection cavity; A neutron source is disposed in the radiation cavity, wherein the neutron beam emitted by the neutron source is moderated by the graphite pile to form thermal neutrons; A shielding shell is formed with a receiving space, the graphite stack is arranged in the receiving space, and the shielding shell is provided with a plurality of beam ports communicating with the receiving space; a plurality of movable plates, the plurality of movable plates being movably connected to the shielding shell to selectively open or cover the beam port, wherein the detector is disposed in the detection cavity or on a propagation path of thermal neutrons emitted from the beam port; a crucible assembly, wherein the neutron source is placed in the crucible assembly, the graphite stack is formed with a first socket communicating with the radiation cavity, the shielding shell is formed with a first positioning port communicating with the first socket, the crucible assembly enters the radiation cavity through the first positioning port and the first socket, and shields the first socket; The crucible assembly comprises: The crucible holder is formed with an outer limiting cavity and a first opening communicating with the outer limiting cavity; a crucible, entering the outer limiting cavity through the first opening, the crucible forming an inner limiting cavity and a second opening communicating with the inner limiting cavity, the neutron source being disposed in the inner limiting cavity; A limiting member, comprising a rod body, wherein the rod body enters the inner limiting cavity through the second opening; The neutron generating device includes a container, the detector is placed in the container, the graphite stack is formed with a second socket connected to the detection cavity, the shielding shell is formed with a second positioning port connected to the second socket, and the container can be pulled in and out of the detection cavity along the horizontal direction through the second positioning port and the second socket.

2. The neutron generator according to claim 1, characterized in that The shielding shell includes a fixing frame and a plurality of shielding plates. The fixing frame is formed with a plurality of installation windows. The shielding plates are connected to the fixing frame and shield the installation windows to jointly define the accommodation space.

3. The neutron generator according to claim 2, characterized in that: The fixed frame is formed with a slide groove, and the opposite ends of the movable plate along the first direction are accommodated in the slide groove, so that the movable plate slides along the second direction to open or cover the beam port, wherein the first direction and the second direction are perpendicular to each other.

4. The neutron generator according to claim 1, characterized in that: The neutron generating device includes a first protective plate and a second protective plate. The first protective plate is arranged on a side of the movable plate away from the shielding shell, and the second protective plate is arranged on a side of the first protective plate away from the shielding shell.

5. The neutron generator according to claim 1, characterized in that: The limiting member includes a protective sleeve, and the protective sleeve is wrapped around the outer surface of the rod body.

6. The neutron generating device according to claim 5, characterized in that: The protective sleeve is formed with a first wiring groove extending along the axial direction of the crucible.

7. The neutron generator according to claim 1, characterized in that: The shielding shell includes a fixing frame and a first positioning plate. The first positioning plate is detachably connected to the fixing frame to open or cover the first positioning opening.

8. The neutron generator according to claim 1, characterized in that: The container is formed with a storage cavity and a second wiring groove communicated with the storage cavity, and the detector is arranged in the storage cavity.

9. The neutron generator according to claim 1, characterized in that: The shielding shell includes a fixing frame and a second positioning plate, and the second positioning plate is detachably connected to the fixing frame to open or cover the second positioning opening.

10. The neutron generating device according to claim 1, characterized in that: The graphite stack is in a hexahedral shape, and the neutron source is arranged at the geometric center of the graphite stack.

11. The neutron generator according to claim 1, characterized in that: The graphite stack includes multiple graphite blocks, each of which is hexahedral. Multiple graphite blocks are arranged in the left-right direction to form a first unit, multiple first units are arranged in the front-back direction to form a second unit, and multiple second units are stacked in the top-bottom direction to form the graphite stack.

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