Collimation system of neutron nondestructive testing equipment

Abstract

The utility model discloses a collimation system of neutron nondestructive testing equipment, and aims to overcome the defects of poor shielding effect on neutron beams and poor scattering limiting effect on neutrons in the conventional collimation system. The utility model comprises: a first collimation body; a plurality of shielding layers are stacked on the first collimation body and the second collimation body to form a multi-layer structure; the neutron channel penetrates through the first collimation body and the second collimation body; one end of the neutron channel is an incident end, the other end of the neutron channel is an emergent end, a first reflecting layer is arranged on the inner wall of the neutron channel, and the first reflecting layer extends from the emergent end to the incident end. According to the collimation system of the neutron nondestructive testing equipment, the shielding effect on neutron beams is improved, neutron scattering is limited, and influences on the environment and personnel of a nondestructive testing site are avoided.

Description

Technical Field

[0001] The utility model relates to a neutron detection device, more specifically, it relates to a neutron nondestructive detection device alignment system. Background Art

[0002] Neutron nondestructive testing refers to a testing method that uses neutron rays to interact with matter without destroying the structure and morphology of the object being tested to obtain the internal microscopic and macroscopic structure and material information of the material, and to evaluate the microscopic and macroscopic defects, geometric characteristics, chemical composition, organizational structure, mechanical properties and changes of materials or parts.

[0003] When it is necessary to inspect objects that are difficult to move, a mobile neutron non-destructive testing device is usually moved to the site for inspection. The mobile neutron non-destructive testing device usually includes small neutron sources such as isotopes, neutron tubes, and small accelerator neutron sources. The structure is relatively compact and flexible. The accelerator neutron source obtains a higher neutron yield by accelerating protons to bombard the target. At the same time, adding a neutron collimator to the neutron source plays an important role in the radiation protection of the entire set of neutron non-destructive testing equipment. The neutron collimator requires sufficient shielding to prevent neutron leakage.

[0004] However, the collimation system in the prior art has poor shielding effect on the neutron beam and poor scattering limiting effect on the neutrons, which results in a high neutron dose leaking into the surrounding environment, which is likely to affect the environment and personnel at the non-destructive testing site, and will also affect the imaging effect at the exit of the neutron channel. Utility Model Content

[0005] In order to overcome the above-mentioned shortcomings, the utility model provides a neutron non-destructive testing equipment collimation system, which improves the shielding effect of the neutron beam, limits the neutron scattering, and avoids the impact on the environment and personnel at the non-destructive testing site.

[0006] In order to solve the above technical problems, the utility model adopts the following technical solutions: a neutron nondestructive testing equipment alignment system, comprising:

[0007] The first collimator;

[0008] The second collimator, the first collimator and the second collimator are both laminated with multiple shielding layers to form a multi-layer structure;

[0009] A neutron channel, the neutron channel runs through the first collimator and the second collimator;

[0010] One end of the neutron channel is the incident end, and the other end is the exit end. A first reflection layer is arranged on the inner wall of the neutron channel, and the first reflection layer extends from the exit end to the incident end.

[0011] The first collimator and the second collimator collimate and reflect the neutron beam. The multilayer structure of the first collimator and the second collimator can shield secondary gamma rays and neutrons, and the first reflective layer can limit neutron scattering in the neutron channel to the maximum extent, reducing the impact on imaging at the end of the second collimator, so that neutron imaging can be achieved at the end of the second collimator, thereby performing non-destructive testing on the object to be inspected through neutron imaging. In addition, the multilayer structure of the first collimator and the second collimator and the first reflective layer can reduce the neutron dose leaking into the surrounding environment, thereby preventing the environment and personnel at the inspection site from being affected.

[0012] Preferably, the multi-layer structure includes a plurality of first shielding layers and a plurality of second shielding layers, and the first shielding layers and the second shielding layers are alternately stacked from outside to inside.

[0013] The secondary gamma rays and neutrons are shielded respectively by the first shielding layer and the second shielding layer, and the first shielding layer and the second shielding layer are alternately stacked from the outside to the inside to form a multi-layer structure, which is beneficial to improving the shielding effect.

[0014] Preferably, the neutron channel gradually becomes larger from the incident end to the exit end.

[0015] The neutron channel gradually expands from the incident end to the exit end to form a tapered structure that is small at the top and large at the bottom, which is beneficial for guiding the neutron beam to exit for neutron imaging.

[0016] Preferably, the first collimator is in a hemispherical structure, and the second collimator is in a truncated cone structure.

[0017] The first collimator and the second collimator of this structure can uniformly shield the neutron beam from secondary gamma rays and neutrons.

[0018] Preferably, the first reflective layer is disposed in the second collimating body.

[0019] The first reflection layer is arranged in the second collimator to limit neutron scattering in the neutron channel and reduce the influence on imaging at the end of the second collimator.

[0020] Preferably, the first collimator is connected to a neutron source, a proton channel and a reaction chamber that are interconnected are provided in the neutron source, an inclined target is provided in the reaction chamber, and an incident end of the neutron channel is connected to the reaction chamber.

[0021] The proton beam accelerated by the vehicle-mounted accelerator is transmitted into the reaction chamber in the proton channel and bombards the target to generate neutrons, which are then ejected through the neutron channel. In the process of being ejected through the neutron channel, the neutron beam is collimated and reflected by the first collimator and the second collimator, and the secondary gamma (γ) rays and neutrons are respectively shielded by the first shielding layer and the second shielding layer. The first reflecting layer can limit the neutron scattering in the neutron channel to the maximum extent, reduce the influence on the imaging at the end of the second collimator, so as to realize neutron imaging at the end of the second collimator, and perform non-destructive testing on the object to be inspected through neutron imaging.

[0022] Preferably, a second reflective layer is provided on the inner wall of the reaction chamber.

[0023] The second reflection layer can reduce the leakage of neutrons, and the neutrons leaked from the target body can be scattered back to the target body through collision in the second reflection layer, so as to fully reflect the neutrons generated by the target body.

[0024] Preferably, the target is arranged along the axial direction of the neutron channel, the axis of the neutron channel incident end is laterally offset forward from the center of the target, and the neutron channel incident end is longitudinally offset downward from the target.

[0025] This structural arrangement is beneficial to improving the uniformity of the neutron beam and the neutron injection rate when the neutron beam is emitted to the imaging position through the neutron channel.

[0026] Preferably, a collimating inner layer is provided on the inner wall of the neutron channel, and the collimating inner layer extends from the incident end toward the exit end.

[0027] The setting of the collimating inner layer reduces the energy loss of higher energy neutrons after scattering, and ensures as much as possible that the loss of high energy components of the neutron beam is small and the penetration is strong.

[0028] Compared with the prior art, the beneficial effects of the utility model are as follows: (1) the neutron beam is collimated and reflected by the first collimator and the second collimator, and the secondary gamma rays and neutrons are respectively shielded by the first shielding layer and the second shielding layer, and the neutron scattering in the neutron channel can be limited to the maximum extent by the first reflecting layer, reducing the influence on the imaging at the end of the second collimator, so as to realize neutron imaging at the end of the second collimator, thereby performing non-destructive testing on the object to be inspected by neutron imaging, and the neutron dose leaked into the surrounding environment can be reduced by the first shielding layer, the second shielding layer and the first reflecting layer, so as to prevent the environment and personnel at the detection site from being affected; (2) the second reflecting layer arranged in the reaction chamber can reduce the leakage of neutrons, and can return the neutrons leaked from the target body to the target body after collision scattering in the second reflecting layer, so as to fully reflect the neutrons generated by the target body. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the utility model;

[0030] Figure 2 This utility model Figure 1 A cross-sectional view of the first collimator at AA in FIG.

[0031] Figure 3 This utility model Figure 1 A cross-sectional view of the second collimator at position BB in FIG.

[0032] In the figure: 11, first collimator, 12, second collimator, 20, neutron source, 21, target, 22, second reflecting layer, 101, first shielding layer, 102, second shielding layer, 103, first reflecting layer, 201, neutron channel, 202, reaction chamber, 203, proton channel, 301, collimating inner layer, 2011, incident end, 2012, exit end. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0034] Embodiment: A neutron nondestructive testing equipment alignment system (see attached Figure 1 , Attachment Figure 2 , Attachment Figure 3 ),include:

[0035] A first collimator 11;

[0036] The second collimator 12, the first collimator 11 and the second collimator 12 are stacked with multiple shielding layers to form a multi-layer structure; the first collimator 11 is axially ( Figure 1 The direction indicated by the central axis Z) is arranged on the upper part of the second collimator 12;

[0037] A neutron channel 201, which runs through the first collimator 11 and the second collimator 12; the neutron channel 201 gradually becomes larger from the incident end 2011 to the exit end 2012, thereby forming a tapered structure with a small top and a large bottom, which is conducive to guiding the neutron beam to exit for neutron imaging;

[0038] One end of the neutron channel 201 is the incident end 2011, and the other end is the exit end 2012. The incident end 2011 is placed at the upper end of the first collimator 11, and the exit end 2012 is placed at the lower end of the second collimator 12. A first reflection layer 103 is arranged on the inner wall of the neutron channel 201. The first reflection layer 103 is arranged in the second collimator 12, and the first reflection layer 103 extends from the exit end 2012 to the incident end 2011. The first reflection layer 103 is arranged on the inner wall of the neutron channel 201 where the second collimator 12 is located. The first reflection layer 103 extends from the second collimator 12 along the Figure 1The end in the direction indicated by the middle arrow C extends toward the direction of the first collimator 11 on the inner circumference of the second collimator 12 to limit the neutron scattering in the neutron channel 201 and reduce the influence on the imaging of the end of the second collimator 12 .

[0039] The multilayer structure of the first collimator 11 and the second collimator 12 includes a plurality of first shielding layers 101 and a plurality of second shielding layers 102. The first shielding layers 101 and the second shielding layers 102 are alternately stacked from outside to inside. Figure 1 During the emission in the direction indicated by the middle arrow C, the neutron beam is collimated and reflected by the first collimator 11 and the second collimator 12, and the secondary gamma (γ) rays and neutrons are respectively shielded by the first shielding layer 101 and the second shielding layer 102, and the neutron scattering in the neutron channel 201 can be limited to the maximum extent by the first reflecting layer 103, and the influence on the imaging at the end of the second collimator 12 is reduced, so that neutron imaging can be realized at the end of the second collimator 12, thereby performing non-destructive testing on the object to be inspected (not shown) through neutron imaging, and the first shielding layer 101, the second shielding layer 102 and the first reflecting layer 103 can reduce the neutron dose leaking into the surrounding environment, so as to prevent the environment and personnel at the detection site from being affected. It should be noted that the inventors have found through experiments that, compared with the case where the first reflection layer 103 is not provided, the neutron flux at the exit of the collimation system of the neutron non-destructive testing equipment with the first reflection layer 103 (i.e., the exit end 2012 of the neutron channel 201 formed at the end of the second collimator 12) can be increased by nearly 40%, and the gamma flux can be reduced by nearly 20%.

[0040] Specifically, the first reflective layer 103 is configured as a beryllium layer, and the material of the first reflective layer 103 is preferably beryllium (Be), which has a larger scattering cross section and a smaller absorption cross section, thus having a better neutron reflection effect. It should be noted that the inventors have found through experiments that by setting the thickness of the first reflective layer 103 to 3 cm and the length of the first reflective layer 103 along the axial direction to 80 cm, neutrons can be reflected to the maximum extent.

[0041] like Figure 1 and Figure 2As shown, the first collimator 11 is configured as a multilayer structure formed by the first shielding layer 101 and the second shielding layer 102 stacked from the outside to the inside, which is an even number of layers and at least four layers; the second collimator 12 is configured as a multilayer structure formed by the first shielding layer 101 and the second shielding layer 102 stacked from the outside to the inside, which is an even number of layers and at least four layers. Optionally, the first collimator 11 is configured as a structure of at least four layers formed by the first shielding layer 101 and the second shielding layer 102 stacked from the outside to the inside along the radial direction through the axis Z, and the second collimator 12 is configured as a structure of at least four layers formed by the first shielding layer 101 and the second shielding layer 102 stacked from the outside to the inside along the radial direction through the axis Z, or an even number of layers greater than four layers. In this embodiment, a four-layer structure is preferably used. The material of the first shielding layer 101 is preferably lead (Pb), which can be used to shield secondary gamma rays. The material of the second shielding layer 102 is preferably boron polyethylene, which can be used to shield neutrons.

[0042] The first collimator 11 is connected to the neutron source 20, which is connected to the upper part of the first collimator 11. The neutron source 20 is provided with a proton channel 203 and a reaction chamber 202 which are interconnected. The reaction chamber 202 is provided with an inclined target 21, and the incident end 2011 of the neutron channel 201 is connected to the reaction chamber 202. A second reflective layer 22 is provided on the inner wall of the reaction chamber 202. The target 21 is arranged along the axial direction of the neutron channel 201, and the axis of the incident end 2011 of the neutron channel 201 deviates from the center of the target 21 laterally and forwardly, and the incident end 2011 of the neutron channel 201 deviates from the target 21 longitudinally and downwardly.

[0043] Target 21 and Figure 1 The horizontal plane indicated by the dashed line S forms an angle α, which is 45°. The neutron source 20 is connected to the first collimator 11 along the axial direction opposite to the side of the second collimator 12, and the neutron channel 201 is integrally constructed inside the neutron source 20, the first collimator 11 and the second collimator 12. The inner diameter of the neutron incident end 2011 formed by the neutron channel 201 extending into the reaction chamber 202 is 10 cm, and the inner diameter of the neutron exit end 2012 formed by the neutron channel 201 at the end of the second collimator 12 is 30 cm. The shape of the neutron channel 201 is conical, so as to be used for Figure 1 The neutron beam is guided in the direction indicated by the arrow C to perform neutron imaging.

[0044] The proton beam accelerated by the vehicle-mounted accelerator (not shown) travels along the proton channel 203. Figure 1The direction indicated by the middle arrow R is transmitted into the reaction chamber 202 and bombards the target 21 (the material of the target 21 is preferably a lithium target) to generate neutrons, and the neutrons are emitted through the neutron channel 201. In the process of neutron beam being emitted through the neutron channel 201, the neutron beam is collimated and reflected by the first collimator 11 and the second collimator 12, and the secondary gamma (γ) rays and neutrons are respectively shielded by the first shielding layer 101 and the second shielding layer 102, and the neutron scattering in the neutron channel 201 can be limited to the maximum extent by the first reflecting layer 103, and the influence on the imaging at the end of the second collimator 12 is reduced, so as to realize neutron imaging at the end of the second collimator 12, so as to perform non-destructive detection on the object to be inspected (not shown) through neutron imaging. It should be noted that the inventors have found through experiments that when the target 21 is set in the reaction chamber 202 at an angle α of 45° with the horizontal direction, the non-uniformity of the neutron beam on both sides parallel to the proton incidence direction at the exit of the neutron channel 201 is only 2.65%, and the non-uniformity of the neutron beam on both sides perpendicular to the proton incidence direction is only 0.54%, thereby improving the neutron beam uniformity and neutron injection rate of the neutron beam emitted from the neutron channel 201 to the imaging position. Compared with the neutron collimation device in the prior art for collimating the neutrons emitted from the neutron source 20 to constrain the longitudinal and lateral angle divergence of the neutrons along the expected direction to form a neutron beam, the collimation system of the neutron non-destructive testing equipment can not only collimate the neutrons emitted from the neutron source 20, but also can collimate the neutrons emitted from the neutron source 20 through the target 21 and the horizontal direction. Figure 1 The horizontal plane shown by the dotted line S forms an angle α of 45°, and the neutron channel 201 is perpendicular to the proton incidence direction in the proton channel 203 and is axially aligned with the position of the target 21. It can also improve the neutron beam uniformity and neutron injection rate of the neutron beam emitted to the imaging position through the neutron channel 201, so that more neutrons can be reflected to the imaging position, thereby improving the neutron imaging effect.

[0045] It should be noted that the inventors have found through experiments that the shape of the first collimator 11 is preferably a hemispherical structure, and the radius of the first collimator 11 is preferably 40 cm, and the thickness of the first shielding layer 101 and the second shielding layer 102 stacked from the outside to the inside are preferably 1 cm, 14 cm, 1.5 cm and 23.5 cm respectively; the shape of the second collimator 12 is preferably a truncated cone structure, and the radial wall thickness of the second collimator 12 is preferably 20 cm, and the thickness of the first shielding layer 101 and the second shielding layer 102 stacked from the outside to the inside are preferably 0.5 cm, 1 0.5cm, 0.5cm and 8.5cm; the total axial length of the first collimator 11 and the second collimator 12 is preferably 160cm; thereby, the weight and volume of the first collimator 11 and the second collimator 12 can be reduced as much as possible, so that the first collimator 11 can still have a good shielding effect on the neutrons in the neutron channel 201, and the weight of the neutron non-destructive testing equipment alignment system that does not include the neutron source 20 is only 0.85 tons, so that the neutron non-destructive testing equipment alignment system that does not include the neutron source 20 can be carried on a vehicle through a carrier (not shown). Exemplarily, the shape of the first collimator 11 may also be a regular pyramid, such as a truncated pyramid, and is connected to the neutron source 20 through the regular polygonal base of the regular pyramid; the shape of the second collimator 12 may also be cylindrical, prism-shaped or truncated pyramid-shaped. In the present embodiment, the shape of the first collimator 11 is preferably hemispherical, and the shape of the second collimator 12 is preferably truncated cone-shaped. The advantage of such a construction is that it can uniformly shield the neutron beam from secondary gamma rays and neutrons.

[0046] Furthermore, the reaction chamber 202 is provided with a second reflective layer 22 surrounding the target 21, and the second reflective layer 22 is configured as a graphite reflective layer. It should be noted that the material of the second reflective layer 22 is preferably a graphite reflector, which can reduce the leakage of neutrons, and can return the neutrons leaked from the target 21 to the target 21 after collision scattering in the second reflective layer 22, so as to fully reflect the neutrons generated by the target 21.

[0047] like Figures 1 to 3 As shown, the neutron yield of the portable isotope neutron source 20 and the neutron tube generator in the prior art is usually low. The neutron yield of the isotope neutron source 20 is generally 1×10 5 n / s, neutron generators are generally less than 1×10 8n / s, which cannot meet the needs of industrial nondestructive testing. Before the actual use of the neutron nondestructive testing equipment alignment system, optionally, by adjusting the neutron incident end 2011 of the neutron channel 201 to a position 2 cm forward along the horizontal plane S from the center point of the target body 21, and 3 cm downward along the axial direction, and then with the angle α formed by the target body 21 and the horizontal direction being 45° and set in the reaction chamber 202, the proton beam accelerated by the vehicle-mounted accelerator (not shown) is transmitted through the proton channel 203 to bombard the target body 21 (the material of the target body 21 is preferably a lithium target) to generate neutrons, and the second reflection layer 22 can reduce the leakage of neutrons, and the neutrons leaked from the target body 21 can be scattered by collision in the second reflection layer 22 and then returned to the target body 21, and the neutrons generated by the target body 21 are fully reflected by the second reflection layer 22 and then emitted through the neutron channel 201, at this time, the neutron exit end The non-uniformity of the neutron beam on both sides parallel to the proton incident direction at position 2012 is only 2.65%, and the non-uniformity of the neutron beam on both sides perpendicular to the proton incident direction is only 0.54%, thereby improving the neutron beam uniformity and neutron flux rate of the neutron beam emitted to the imaging position through the neutron channel 201. At the same time, by the first reflection layer 103 arranged on the inner circumferential surface of the second collimator 12, the first reflection layer 103 extends from the end of the second collimator 12 to the direction where the first collimator 11 is located to form at least a part of the circumferential surrounding neutron channel 201, and the first reflection layer 103 is preferably 80 cm long and 3 cm thick along the axial direction, so that the neutrons scattered in the neutron channel 201 can be reflected to the maximum extent, and the neutron flux can be increased, so that the neutron flux at the neutron exit end 2012 of the neutron channel 201 can reach 7.6×10 5n / s, thereby meeting the needs of industrial non-destructive testing and ensuring the neutron imaging effect. And through the first collimator 11 and the second collimator 12 of the four-layer structure formed by the first shielding layer 101 and the second shielding layer 102 stacked from the outside to the inside, the neutrons and secondary gamma rays formed under high neutron yield can be shielded, and the first reflective layer 103 is used to reduce the neutron dose leaking into the surrounding environment to prevent the environment and personnel at the detection site from being affected. At the same time, since the carrier used for the movable neutron non-destructive testing device in the prior art takes into account the mobility requirement of the neutron source 20, the weight and volume of the neutron non-destructive testing equipment alignment system are limited. In the present application, the shapes of the first collimator 11 and the second collimator 12 are preferably hemispherical and truncated cone, respectively, and the radial wall thickness of the second collimator 12 is preferably 20 cm, the radius of the first collimator 11 is preferably 40 cm, and the total length of the first collimator 11 and the second collimator 12 along the axial direction is preferably 160 cm. The inventors have found through experiments that the weight of the neutron non-destructive testing equipment alignment system that does not include the neutron source 20 is only 0.85 tons (T), so that the neutron non-destructive testing equipment alignment system can be carried on a vehicle. Therefore, the collimation system of the neutron nondestructive testing equipment solves the problem of how to simultaneously improve the neutron injection rate and beam uniformity at the collimator exit position, and limit the neutron dose leaking into the surrounding environment to prevent the environment and personnel at the testing site from being affected, under the condition that the weight and volume are limited. In addition, a collimation inner layer 301, preferably made of iron, is provided on the inner wall of the neutron channel 201, which is not included in the first reflection layer 103, and the collimation inner layer 301 extends from the incident end 2011 to the exit end 2012.

[0048] The neutron non-destructive testing equipment alignment system can be detachably arranged on the carrier. When it needs to be moved to the site for testing, the neutron non-destructive testing equipment alignment system including the neutron source 20 can be moved by the carrier.

[0049] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A neutron nondestructive testing equipment alignment system, characterized in that: include: The first collimator; The second collimator, the first collimator and the second collimator are both laminated with multiple shielding layers to form a multi-layer structure; A neutron channel, the neutron channel runs through the first collimator and the second collimator; One end of the neutron channel is the incident end, and the other end is the exit end. A first reflection layer is arranged on the inner wall of the neutron channel, and the first reflection layer extends from the exit end to the incident end.

2. A neutron nondestructive testing equipment alignment system according to claim 1, characterized in that: The multi-layer structure comprises a plurality of first shielding layers and a plurality of second shielding layers, wherein the first shielding layers and the second shielding layers are alternately stacked from outside to inside.

3. The neutron nondestructive testing equipment alignment system according to claim 1, characterized in that: The neutron channel gradually becomes larger from the incident end to the exit end.

4. The neutron nondestructive testing equipment alignment system according to claim 1, characterized in that: The first collimator is in a hemispherical structure.

5. The neutron nondestructive testing equipment alignment system according to claim 1, characterized in that: The second collimator is in a truncated cone structure.

6. The neutron nondestructive testing equipment alignment system according to claim 1, characterized in that: The first reflective layer is disposed in the second collimating body.

7. A neutron nondestructive testing equipment alignment system according to any one of claims 1 to 6, characterized in that: The first collimator is connected to the neutron source. A proton channel and a reaction chamber that are interconnected are arranged in the neutron source. An inclined target is arranged in the reaction chamber. The incident end of the neutron channel is connected to the reaction chamber.

8. The neutron nondestructive testing equipment alignment system according to claim 7, characterized in that: A second reflective layer is arranged on the inner wall of the reaction chamber.

9. The neutron nondestructive testing equipment alignment system according to claim 7, characterized in that: The target body is arranged along the axial direction of the neutron channel, the axis of the incident end of the neutron channel deviates from the center of the target body laterally and forwardly, and the incident end of the neutron channel deviates from the target body longitudinally and downwardly.

10. A neutron non-destructive testing equipment alignment system according to any one of claims 1 to 6, characterized in that: A collimating inner layer is arranged on the inner wall of the neutron channel, and the collimating inner layer extends from the incident end to the exit end.

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