CN214844913U - Detection apparatus for special nuclear material - Google Patents
Detection apparatus for special nuclear material Download PDFInfo
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- CN214844913U CN214844913U CN202120543231.2U CN202120543231U CN214844913U CN 214844913 U CN214844913 U CN 214844913U CN 202120543231 U CN202120543231 U CN 202120543231U CN 214844913 U CN214844913 U CN 214844913U
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Abstract
The detection device for the special nuclear material comprises a neutron source and a first detector. The first detector is used for receiving particle beams generated after the neutron beams irradiate the sample to be detected. The neutron beam emitted by the neutron source irradiates on a sample to be detected, and when the sample to be detected contains special nuclear materials, the neutron beam irradiates on the special nuclear materials and causes the special nuclear materials to be fissile, so that new neutrons are generated and form a particle beam which is detected by the first detector. Whether special nuclear materials are contained in a sample to be detected can be judged according to the neutron number detected by the first detector and the neutron attenuation characteristics, the energy range of the neutron beam emitted by the neutron source is narrow, the influence of neutrons with other energies on a detection result is reduced, the detection accuracy is improved, and the special nuclear materials are accurately screened. The detection device for the special nuclear materials provided by the embodiment of the application has the advantage that the special nuclear materials can be accurately discriminated.
Description
Technical Field
The application relates to the technical field of nuclear material detection, in particular to a detection device for special nuclear materials.
Background
Currently, Special Nuclear Materials (SNM) are the core materials for manufacturing simple nuclear devices (IND), terrorists using the simple nuclear devices manufactured by special nuclear materials will bring disastrous consequences to people around the world, and the occurrence of nuclear terrorist attacks is prevented by strengthening the monitoring and detection of the special nuclear materials to prevent the illegal transfer of the nuclear materials.
In the prior art, techniques for detecting a specific nuclear material effectively include two types, a passive detection technique and an active detection technique. Passive detection techniques determine whether to conceal nuclear material by directly detecting neutrons and/or gamma rays emitted by the particular nuclear material itself. Although plutonium (Pu), which is a nuclear material that emits more neutrons and gamma rays, can be detected relatively easily by this technique, it is very difficult to detect directly such nuclear material that emits less gamma rays and has a lower energy, since U-235 emits less gamma rays and is less energetic and is easily shielded. Accordingly, there is a need in the art for a detection device that can accurately discriminate between particular nuclear materials.
SUMMERY OF THE UTILITY MODEL
In view of this, it is desirable to provide a detection apparatus for a special nuclear material to solve the problem that the special nuclear material cannot be accurately discriminated.
To achieve the above object, an embodiment of the present application provides a detection apparatus for a special nuclear material, including:
the neutron source is used for emitting a neutron beam to irradiate a sample to be measured; and
the first detector is arranged at the downstream of the neutron source along the transmission direction of the neutron beam emitted by the neutron source and is used for receiving a particle beam generated after the neutron beam irradiates the sample to be detected.
Further, the neutron source is a pulse neutron source.
Further, the pulsed neutron source is a deuterium-deuterium neutron generator.
Further, the neutron energy of the neutron beam emitted by the pulse neutron source is 2.5 +/-2 MeV, the pulse width is 250 +/-150 mu s, and the period is 3 +/-2 ms.
Further, the first detector is one or more of a plastic scintillator detector, a liquid detector and a He-3 neutron detector.
Furthermore, the distance between the neutron source and the first detector is adjustable, so that different samples to be detected can be detected.
Further, the detection device further comprises a collimator; the collimator is disposed downstream of the neutron source in a direction of propagation of the neutron beam emitted by the neutron source.
Further, the detection device further comprises a collimator; and arranging the collimator at the upstream of the first detector along the transmission direction of the particle beam generated after the neutron beam irradiates the sample to be detected.
Further, the detection device further comprises:
and the second detector is positioned beside the transmission direction of the neutron beam emitted by the neutron source so as to detect the neutron beam emitted by the neutron source.
Further, the second detector is one or more of a plastic scintillator detector, a liquid detector and a He-3 neutron detector.
The detection device for the special nuclear material comprises a neutron source and a first detector. The first detector is arranged at the downstream of the neutron source along the transmission direction of the neutron beam emitted by the neutron source and used for receiving the particle beam generated after the neutron beam irradiates the sample to be detected. The neutron beam emitted by the neutron source irradiates on a sample to be detected, and when the sample to be detected contains special nuclear materials, the neutron beam irradiates on the special nuclear materials and causes the special nuclear materials to fission, so that new neutrons are generated and form a particle beam which is detected by a first detector; when the sample to be detected does not contain special nuclear materials, new neutrons cannot be generated when the neutron beams irradiate the sample to be detected. Whether special nuclear materials are contained in a sample to be detected can be judged according to the neutron number detected by the first detector and the neutron attenuation characteristics, the energy range of the neutron beam emitted by the neutron source is narrow, the influence of neutrons with other energies on a detection result is reduced, the detection accuracy is improved, and the special nuclear materials are accurately screened. The detection device for the special nuclear materials provided by the embodiment of the application has the advantage that the special nuclear materials can be accurately discriminated.
Drawings
FIG. 1 is a schematic structural diagram of a special nuclear material detection device according to an embodiment of the present application; and
fig. 2 is a schematic structural diagram of another detection apparatus for a special nuclear material in the embodiment of the present application.
Description of the reference numerals
1. A neutron source; 2. a first detector; 3. a sample to be tested; 4. a second detector; 5. a neutron beam; 6. a particle beam; 31. a special nuclear material; 100. and (4) a detection device.
Detailed Description
It should be noted that, in the present application, technical features in examples and embodiments may be combined with each other without conflict, and the detailed description in the specific embodiment should be understood as an explanation of the gist of the present application and should not be construed as an improper limitation to the present application.
The directional terms used in the description of the present application are intended only to facilitate the description of the application and to simplify the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be considered limiting of the application.
Referring to fig. 1 to 2, an apparatus for detecting a special nuclear material according to an embodiment of the present application includes a neutron source 1 and a first detector 2. The neutron source 1 is used for emitting a neutron beam 5 to irradiate a sample 3 to be detected; the first detector 2 is disposed downstream of the neutron source 1 along a transmission direction of the neutron beam 5 emitted by the neutron source 1, and is used for receiving a particle beam 6 generated after the sample 3 to be measured is irradiated by the neutron beam 5.
According to the detection device for the special nuclear material provided by the embodiment of the application, the first detector 2 is arranged at the downstream of the neutron source 1 along the transmission direction of the neutron beam 5 emitted by the neutron source 1 and is used for receiving the particle beam 6 generated after the neutron beam 5 irradiates the sample 3 to be detected. The neutron beam 5 emitted by the neutron source 1 irradiates on a sample 3 to be detected, and when the sample 3 to be detected contains special nuclear materials 31, the neutron beam 5 irradiates on the special nuclear materials 31 and causes the special nuclear materials 31 to be fissile, so that new neutrons are generated and form a particle beam 6 to be detected by the first detector 2; when the sample 3 to be measured does not contain the special nuclear material 31, new neutrons are not generated when the neutron beam 5 is irradiated on the sample 3 to be measured. Whether the special nuclear materials 31 are contained in the sample 3 to be detected can be judged according to the neutron number detected by the first detector 2 and the neutron attenuation characteristics, the energy range of the neutron beam 5 emitted by the neutron source 1 is narrow, the influence of neutrons with other energies on a detection result is reduced, the detection accuracy is improved, and the special nuclear materials 31 are accurately screened. The detection device for the special nuclear material has the advantage that the special nuclear material 31 can be accurately discriminated.
It should be noted that the detection device for a special nuclear material provided in the embodiments of the present application does not include a photoneutron conversion target. Compared with the neutron beam 5 with a wide energy range generated by the photoneutron conversion target, the energy range of the neutron beam 5 emitted by the neutron source 1 is narrow, the influence of neutrons with other energies on a detection result is reduced, the detection result is easier to analyze, and the detection accuracy is improved. The detection device provided by the embodiment of the application is independent of the existing accelerator X-ray imaging detection device, and can be used as a secondary detection means to perform qualitative detection on suspicious objects which may hide the special nuclear materials 31.
The detection device provided by the embodiment of the application has the advantages that each part is adjustable, the large truck and the box body can be detected, the small package can be detected, the structure is simple and convenient, and the use is more convenient. Specifically, the distance between the neutron source 1 and the first detector 2 is adjustable, so as to detect different samples 3 to be detected. The interval between neutron source 1 and first detector 2 is adjustable, can be according to the size of 3 volumes of the sample that awaits measuring, and the interval between adjustment neutron source 1 and first detector 2 can detect large-scale freight train and box, also can detect small-size parcel, and simple structure is convenient, and it is more convenient to use.
It is easy to understand that the distance between the neutron source 1 and the sample 3 to be measured can be determined according to actual conditions, and when the distance between the neutron source 1 and the sample 3 to be measured is too large, the distance between the neutron source 1 and the sample 3 to be measured can be reduced, or the number of neutron beams 5 can be increased. When the distance between the neutron source 1 and the sample 3 to be measured is too small, the distance between the neutron source 1 and the sample 3 to be measured can be increased, or the number of neutron beams 5 can be reduced.
In one embodiment, the number of the neutron sources 1 is one or more, and a plurality of the neutron sources 1 emit the neutron beams 5 to the sample to be detected simultaneously, so that the coverage of the neutron beams 5 is increased, and the detection efficiency is improved. Preferably, the number of the neutron sources 1 in one detection device 100 is one, so that the cost of the detection device 100 is reduced.
In one embodiment, the number of the first detectors 2 is one or more, and the plurality of first detectors 2 simultaneously receive the particle beam 6 generated after the neutron beam 5 irradiates the sample 3 to be detected, so that the detection range is increased, and the detection efficiency and the detection accuracy are improved. Preferably, the number of the first probes 2 in one detection device 100 is one, so that the cost of the detection device 100 is reduced.
The detection device provided by the embodiment of the application can judge whether the sample to be detected 3 contains the special nuclear material 31 or not by analyzing the neutron attenuation tendency characteristics.
In one embodiment, the neutron source 1 is a pulsed neutron source. When the sample 3 to be detected does not contain the special nuclear material 31, the neutron beam 5 enters the sample 3 to be detected during the period that the pulse neutron source emits the neutron beam 5, the numbers of fast neutrons and epithermal neutrons are gradually increased and reach peak values; after the emission of the pulse neutron source is finished, neutrons are accompanied by scattering and escape phenomena, the number of fast neutrons and epithermal neutrons is E exponential attenuation, meanwhile, the number of thermal neutrons in the sample 3 to be detected is rapidly increased in a certain time along with the phenomenon of fast neutron thermalization, and when the thermal neutrons are absorbed or escape, the number of neutrons is obviously reduced. After a certain time, fast neutrons and epithermal neutrons do not exist in the sample 3 to be detected. If the sample 3 to be tested contains a certain amount of special nuclear materials 31, the number of thermal neutrons still decays, but the thermal neutrons further react with the special nuclear materials 31 to cause the special nuclear materials 31 to have fission reaction, and new fast neutrons are generated. The number of fast neutrons produced during fission is directly proportional to the number of thermal neutrons that react with the particular nuclear material 31. Fast neutrons generated by fission reaction of the special nuclear material 31 are thermalized to form thermal neutrons, so that the number of the thermal neutrons is increased, and the decay speed of the thermal neutrons in the neutron beam 5 is reduced. Therefore, after the pulsed neutron source emits the neutron beam 5, the attenuation characteristic of the number of thermal neutrons detected by the first detector 2 can be used for judging whether the special nuclear material 31 exists in the sample 3 to be detected. When the special nuclear material 31 is present in the sample 3 to be measured, the thermal neutron quantity decays relatively slowly.
The neutron source 1 is a pulse neutron source, and after the pulse neutron source emits the neutron beam 5, the neutrons can be attenuated, so that whether the special nuclear material 31 exists in the sample 3 to be detected can be judged conveniently according to the attenuation characteristics of the number of the neutrons in one period, and compared with the neutron beam 5 which is emitted continuously, the attenuation characteristics of the pulse neutron beam 5 are more visual.
In one embodiment, the pulsed neutron source is a deuterium-deuterium neutron generator. The deuterium neutron generator generates neutrons with energy of about 2.5MeV and a narrow energy range, and neutrons with low energy react with the special nuclear material 31 more easily, so that the special nuclear material 31 generates fission reaction. Therefore, the neutron beam 5 emitted by the deuterium neutron generator has more neutrons to act on the special nuclear materials 31 and generate new fast neutrons, the attenuation speed of the thermal neutrons in the neutron beam 5 is finally slowed down, the attenuation characteristic of the neutron quantity of the sample 3 to be detected without the special nuclear materials 31 is more obviously compared, and the detection accuracy is improved.
In one embodiment, the neutron beam 5 emitted by the pulsed neutron source has a neutron energy of 2.5 + -2 MeV, a pulse width of 250 + -150 μ s, and a period of 3 + -2 ms. Specifically, the neutron energy of the neutron beam 5 emitted by the pulse neutron source is 2.5MeV, the pulse width is 250 mus, and the period is 3 ms.
In an embodiment, the first detector 2 is one or more of a plastic scintillator detector, a liquid detector, and a He-3 neutron detector. Preferably, the first detector 2 is a He-3 neutron detector. The He-3 neutron detector is not sensitive to gamma rays, so that accurate detection of neutrons is facilitated.
It should be explained that the first detector 2 receives the particle beam 6 generated by the irradiation of the sample 3 to be measured with the neutron beam 5. The particle beam 6 generated after the neutron beam 5 irradiates the sample 3 to be measured includes the neutron beam 5 generated by the fission reaction of the neutron beam 5 on the special nuclear material 31 and the neutron beam 5 scattered on other special nuclear materials 31.
He-3 neutron detector data acquisition is synchronized with the deuterium neutron generator, with the first time-track of the data corresponding to the start time of the deuterium neutron generator. And analyzing the attenuation trend characteristic of thermal neutrons by utilizing neutron time spectrum information recorded by the He-3 neutron detector after the deuterium-deuterium neutron generator stops emitting neutrons, and judging whether the special nuclear materials 31 exist in the detection area. The method can be used for detecting the special nuclear materials 31 in the containers such as vehicles, packages and the like, so as to strengthen the monitoring and detection of the special nuclear materials 31 and effectively prevent the illegal transfer of the special nuclear materials 31.
In an embodiment, the detection apparatus 100 further comprises a collimator disposed downstream of the neutron source 1 along the transport direction of the neutron beam 5 emitted by the neutron source 1. The collimator is arranged at the downstream of the neutron source 1, and the collimator forms constraint on the neutron beam 5 emitted by the neutron source 1, so that interference is reduced, and the detection accuracy is improved.
In one embodiment, the detection apparatus 100 further comprises a collimator disposed upstream of the first detector 2 along a transport direction of the particle beam 6 generated after the neutron beam 5 irradiates the sample 3 to be measured. The collimator is arranged at the upstream of the first detector 2, and the collimator forms restraint on the particle beam 6, so that interference is reduced, and the detection accuracy is improved.
Referring to fig. 2, in one embodiment, the detecting device 100 further comprises a second detector 4. The second detector 4 is located beside the transmission direction of the neutron beam 5 emitted by the neutron source 1 to detect the neutron beam 5 emitted by the neutron source 1. The second detector 4 is used for detecting the initial intensity of the neutron beam 5 emitted by the neutron source 1, and preventing the initial intensity of the neutron beam 5 from changing due to the fact that the neutron source 1 emits neutrons for a long time in the detection process, and if the initial intensities of the neutron beam 5 emitted by the neutron source 1 are different, the detection result is affected, and the detection accuracy is affected. It will be appreciated that the number of second detectors 4 may be plural, increasing the accuracy of detection.
In one embodiment, the second detector 4 is one or more of a plastic scintillator detector, a liquid detector, and a He-3 neutron detector. Preferably, the second detector 4 and the first detector 2 are of the same type and are He-3 neutron detectors, and the types of the second detector and the He-3 neutron detectors are the same, so that the detection results can be conveniently compared. The He-3 neutron detector is not sensitive to gamma rays, so that accurate detection of neutrons is facilitated.
In one embodiment, referring to FIG. 1, a sample 3 to be tested is placed in the detection zone of the detection device, and the deuterium neutron generator and first detector 2 are turned on. At this time, the deuterium-deuterium neutron generator starts to emit a neutron beam 5, the neutron beam 5 enters the sample 3 to be detected, the first detector 2 detects a particle beam 6 generated after the neutron beam 5 irradiates the sample 3 to be detected, data acquisition of the first detector 2 is synchronous with the deuterium-deuterium neutron generator, and a first time channel of the data of the first detector 2 corresponds to the starting time of the deuterium-deuterium neutron generator. And analyzing the attenuation trend characteristic of thermal neutrons by utilizing neutron time spectrum information recorded by the first detector 2 after the deuterium-deuterium neutron generator stops emitting the neutron beam 5, and judging whether the special nuclear material 31 exists in the sample 3 to be detected.
In one embodiment, referring to FIG. 2, the sample 3 to be tested is placed in the detection zone of the detection device, and the deuterium neutron generator, the first detector 2, and the second detector 4 are turned on. At this time, the deuterium-deuterium neutron generator starts to emit a neutron beam 5, the neutron beam 5 enters the sample 3 to be detected and can be detected by the second detector 4, the second detector 4 detects the initial intensity of the neutron beam 5 emitted by the neutron source 1, the initial intensity of the neutron beam 5 emitted by the neutron source 1 is changed too much, and the neutron source 1 is adjusted to ensure the initial intensity of the neutron beam 5 in order to prevent the detection accuracy from being affected. The first detector 2 detects a particle beam 6 generated after the neutron beam 5 irradiates a sample 3 to be detected, the data acquisition of the first detector 2 is synchronous with the deuterium neutron generator, and a first time channel of the data of the first detector 2 corresponds to the starting time of the deuterium neutron generator. And analyzing the attenuation trend characteristic of thermal neutrons by utilizing neutron time spectrum information recorded by the first detector 2 after the deuterium-deuterium neutron generator stops emitting the neutron beam 5, and judging whether the special nuclear material 31 exists in the sample 3 to be detected.
The various embodiments/implementations provided herein may be combined with each other without contradiction.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (9)
1. A special nuclear material detection device, comprising:
the neutron source (1), the said neutron source (1) is used for launching the neutron beam (5) in order to illuminate the sample (3) to be measured; and
a first detector (2), wherein the first detector (2) is arranged at the downstream of the neutron source (1) along the transmission direction of the neutron beam (5) emitted by the neutron source (1) and is used for receiving a particle beam (6) generated after the neutron beam (5) irradiates the sample (3) to be measured.
2. Detection apparatus according to claim 1, characterized in that said neutron source (1) is a pulsed neutron source.
3. The detection apparatus of claim 2, wherein the pulsed neutron source is a deuterium neutron generator.
4. The detection apparatus according to claim 2, wherein the neutron beam (5) emitted by the pulsed neutron source has a neutron energy of 2.5 ± 2MeV, a pulse width of 250 ± 150 μ s, and a period of 3 ± 2 ms.
5. A detection arrangement according to claim 1, characterized in that the first detector (2) is one or more of a plastic scintillator detector, a liquid detector and a He-3 neutron detector.
6. The apparatus according to claim 1, wherein the distance between the neutron source (1) and the first detector (2) is adjustable to detect different samples (3) to be detected.
7. The detection apparatus according to claim 1, wherein the detection apparatus (100) further comprises a collimator:
-arranging said collimator downstream of said neutron source (1) along the direction of transmission of said neutron beam (5) emitted by said neutron source (1); and/or the presence of a gas in the gas,
and the collimator is arranged at the upstream of the first detector (2) along the transmission direction of a particle beam (6) generated after the neutron beam (5) irradiates the sample (3) to be detected.
8. The detection apparatus according to claim 1, wherein the detection apparatus (100) further comprises:
and the second detector (4) is positioned beside the transmission direction of the neutron beam (5) emitted by the neutron source (1) so as to detect the neutron beam (5) emitted by the neutron source (1).
9. A detection arrangement according to claim 8, characterized in that the second detector (4) is one or more of a plastic scintillator detector, a liquid detector and a He-3 neutron detector.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202120543231.2U CN214844913U (en) | 2021-03-16 | 2021-03-16 | Detection apparatus for special nuclear material |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202120543231.2U CN214844913U (en) | 2021-03-16 | 2021-03-16 | Detection apparatus for special nuclear material |
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| CN214844913U true CN214844913U (en) | 2021-11-23 |
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