A Rotating Neutron Energy Spectrum On-line Measuring Device

Abstract

The present invention belongs to the technical field of neutron energy spectrum measurement and provides a rotating neutron energy spectrum online measurement device, comprising a bracket, a tray, a Bonner sphere, a rotating platform, and a rotating shaft. Bonner spheres of varying sizes are arranged spirally from top to bottom on the bracket with the tray. The base of the bracket is mounted on the rotating platform, which is driven to rotate at a constant speed by the rotating shaft. Each Bonner sphere is equipped with an independent preamplifier. After synchronous signal acquisition, a multi-channel signal processing unit independently outputs the count rate value of each channel. The online measurement device of the present invention solves the problem of poor isotropy of the energy response of online neutron energy spectra by arranging the Bonner spheres of varying sizes spirally from top to bottom and rotating them at a constant speed in a horizontal plane. Furthermore, a specific energy response algorithm is used to avoid the influence of sphere-sphere interference in the calculation of the energy response function of the neutron spectrometer.

Description

Technical Field

[0001] The invention belongs to the technical field of neutron spectrum measurement, and in particular relates to a rotary neutron spectrum online measurement device. Background Art

[0002] Accurately measuring neutron dose equivalents is crucial for real-time monitoring of radioactive doses in neutron radiation fields and protecting workplace safety. Because neutrons of different energies interact differently with biological tissues, producing distinct biological effects, the neutron dose equivalent per unit dose varies significantly with neutron energy, by as much as a hundredfold. Therefore, neutron spectrum measurement is particularly important for neutron radioactivity monitoring.

[0003] In the field of radiation protection, the Bonner multi-sphere neutron spectrometer is currently the primary method for neutron spectrum measurement. It features high sensitivity, good isotropy, and a wide measurement energy range. Its spectrum measurement device primarily consists of a thermal neutron detector located at the center of the sphere and multiple polyethylene moderator spheres of varying sizes. Neutron spectrum information is obtained by inputting the measurement counts of the thermal neutron detector within the polyethylene moderator spheres of varying sizes into neutron spectrum interpretation software.

[0004] Neutron spectrum measurements using a Bonner multi-sphere neutron spectrometer require rotating Bonner spheres of different sizes to the same measurement location, a complex and time-consuming process. The inability to monitor the neutron spectrum in real time limits the application of Bonner multi-sphere neutron spectrometers in certain situations, such as where it is inconvenient for operators to enter the neutron radiation field to change spheres or where the neutron radiation field changes within a single measurement cycle. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a rotating neutron energy spectrum online measurement device with simple operation, high sensitivity and high measurement accuracy. The measurement device can realize online neutron energy spectrum measurement with high sensitivity and a wide energy range to be measured by synchronously measuring the signals output by multiple Bonner spheres of different sizes. By arranging the Bonner spheres of different sizes in a spiral from top to bottom, isotropic energy response is achieved. Combined with a specific energy response algorithm, online measurement of the neutron energy spectrum is realized.

[0006] The purpose of the present invention is achieved through the following technical measures.

[0007] A rotating neutron energy spectrum online measurement device includes a bracket, a tray, a Bonner ball, a rotating platform, and a rotating shaft. Bonner balls of different sizes are spirally arranged from top to bottom on the bracket with the tray. The base of the bracket is installed on the rotating platform. The rotating platform is driven by the rotating shaft to rotate at a constant speed. Each Bonner ball is equipped with an independent preamplifier. After synchronous signal acquisition, the multi-channel signal processing unit independently outputs the count rate value of each channel.

[0008] In the above technical solution, the Bonner sphere adopts a polyethylene moderation shell with a thermal neutron detector placed in the center.

[0009] In the above technical solution, the Bonner sphere may also be directly used as a bare spherical thermal neutron detector without a moderating shell.

[0010] In order to meet the needs of online measurement, the thermal neutron detector adopts active thermal neutron detector, such as 3 He proportional counter, BF3 proportional counter, or 6 LiI crystal detector, etc.

[0011] In the above technical solution, the rotating platform is driven by a motor control unit to control the rotation axis to rotate, so that the platform rotates horizontally at a uniform speed, and the measurement time can be set to an integer multiple of the horizontal rotation period of the platform.

[0012] Bonner spheres typically range in size from 5 to 40 cm, depending on the maximum neutron energy. The greater the number of Bonner spheres, the better the energy resolution. Neutrons respond differently to varying degrees of slowing down in Bonner spheres of varying sizes. Neutron energy spectra can be inferred using a spectrum decomposition algorithm based on the response in the neutron field being measured and the neutron energy response function.

[0013] If Bonner spheres of different sizes are placed sequentially at the same location under test, and the neutron radiation field remains constant during the measurement cycle, the neutron energy response is isotropic due to the spherical shape of the individual moderators. The resulting neutron energy spectrum is a neutron fluence distribution that is solely dependent on neutron energy and is independent of the neutron incident direction. However, if multiple Bonner spheres of different sizes are simultaneously placed at the location under test to achieve online neutron spectrum measurement, the entire detection system loses its geometric symmetry, and the energy response is no longer isotropic.

[0014] The present invention addresses the drawback of poor isotropy in the energy response of online neutron spectra by spirally arranging Bonner spheres of varying sizes from top to bottom on a bracket mounted on a rotatable platform that rotates at a constant speed in the horizontal plane. Furthermore, a specific energy response algorithm is employed to avoid the effects of sphere-to-sphere interference in the calculation of the neutron spectrometer's energy response function. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the rotating neutron energy spectrum online measurement device of the present invention.

[0016] Figure 2 This is a top view of the rotating neutron spectrum online measurement device of the present invention.

[0017] Figure 3 This is the electrical connection diagram of the rotating neutron spectrum online measurement device of the present invention.

[0018] Among them: 1. bracket, 2. tray, 3. spherical thermal neutron detector, 4. Bonner sphere, 5. rotating platform, 6. rotating axis. DETAILED DESCRIPTION

[0019] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0020] It should be noted that when an element is referred to as being “fixed to” another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or there may be an intermediate element.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] like Figure 1 As shown, an embodiment of the present invention provides a rotating neutron spectrum online measurement device, including a bracket 1, a tray 2, a spherical thermal neutron detector 3, a Bonner sphere 4, a rotating platform 5, and a rotating shaft 6.

[0023] In the above embodiment, the center of the Bonner sphere is an active thermal neutron detector, which is wrapped with polyethylene moderator shells of different sizes.

[0024] In the above embodiment, the Bonner sphere can directly use a bare spherical thermal neutron detector without adding a moderator shell, such as Figure 1 Spherical thermal neutron detector 3.

[0025] In the above embodiment, Bonner spheres of different sizes are arranged spirally from top to bottom on a bracket with a tray. The spiral arrangement is conducive to isotropic response. The Bonner spheres are placed on the tray of the bracket from bottom to top in order from large to small in size, so that the center of gravity of the detection system is low, the structure is compact, and it is more stable during rotation.

[0026] like Figure 2 As shown, the horizontal distance r between the center of each Bonner sphere and the bracket remains the same. If this distance r is too close, vertically incident neutrons will be significantly interfered with by the spheres. Considering the significant interference between large Bonner spheres, large Bonner spheres should be kept as close to each other as possible from a vertical perspective. If the distance r is too far, the entire system occupies a large space, and the neutron energy spectrum of the measured area may vary spatially, making the measurement inaccurate. The determination of the distance r should be based on actual working conditions.

[0027] The angles between the centers of adjacent Bonner spheres and the bracket are mapped to the horizontal direction and kept as consistent as possible, so that the horizontal geometric center of the detection system is on the bracket.

[0028] In the above embodiment, the base of the bracket is mounted on a rotating platform that rotates horizontally at a constant speed. An integral multiple of the platform's horizontal rotation period can be set as the measurement time.

[0029] like Figure 3 As shown, each Bonner sphere is equipped with an independent preamplifier. After synchronous signal acquisition, the multi-channel signal processing unit independently outputs the count rate value of each channel. The rotating platform is driven by a motor control unit, which controls the rotation axis to rotate the platform horizontally at a uniform speed.

[0030] In the above embodiment, the neutron energy response function needs to be input into the neutron spectrum interpretation software. The entire rotating neutron spectrum measurement device is regarded as a whole. The response of each Bonner sphere is obtained by simulating the irradiation of the entire detection system by a parallel incident neutron source in the upper and lower directions and the four horizontal directions. The response values in the six different directions are then averaged to obtain the energy response of each Bonner sphere.

[0031] When the rotating neutron online neutron energy spectrum measurement device is in operation, the motor control unit is first used to drive the motor to make the platform rotate horizontally at a uniform speed, and then the power of the Bonner multi-ball detection system is turned on. The synchronously measured neutron response data (count rate data of a group of different Bonner balls) is input into the neutron energy spectrum decomposition software integrated with the simulated neutron energy response to obtain real-time neutron energy spectrum information.

[0032] In summary, the present invention mainly solves the problem that the existing Bonner multi-sphere neutron spectrometer cannot perform online measurements, and the problem that the energy response is not isotropic after online measurement of the neutron energy spectrum using multiple Bonner spheres for synchronous measurement, so as to achieve the purpose of accurately obtaining real-time neutron energy spectrum information.

[0033] The rotating neutron spectrum online measuring device of the present invention arranges Bonner spheres of different sizes in a spiral arrangement from top to bottom, which is conducive to isotropic response. The size of the Bonner sphere can refer to the spherical size of the Bonner multi-sphere neutron spectrometer, and a bare spherical thermal neutron detector (such as a spherical neutron detector) can also be used. 3 Because the central detector of each Bonner sphere can be a highly sensitive thermal neutron detector, the measurement cumulative count is high, the statistical error is small, and the measurement accuracy is high. The energy response of this rotating neutron energy spectrum online measurement device can be approximately isotropic.

[0034] The energy response function (ERF) of the Bonner multi-sphere neutron spectrometer system is calculated by simulating the number of responses to irradiation of individual Bonner spheres of varying sizes by monoenergetic parallel neutron sources of varying energies. To account for interference between Bonner spheres in the rotating neutron spectrum online measurement device, the rotating neutron spectrum detection system is treated as a single entity. The energy response values of each Bonner sphere are calculated by simulating irradiation from parallel neutron sources in six directions (four mutually perpendicular horizontal directions and two vertical directions, respectively) to obtain the energy response function for each sphere. The energy response function for each sphere is then averaged across these six directions. This energy response function calculation method accounts for the effects of sphere-to-sphere interference within the entire detection system, eliminating the need for energy response corrections due to sphere-to-sphere interference when calculating the energy response of a single Bonner sphere. This results in more accurate energy response function calculations and improves the accuracy of online neutron spectrum measurements.

[0035] The present invention provides a new research and development direction for the neutron energy spectrum online measurement technology, which enables the neutron energy spectrum online monitor to take a step further towards engineering application.

[0036] The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0037] The specific implementation methods described above are merely specific illustrations of the purpose, technical solutions and beneficial effects of the present invention, and do not limit the form of display and protection scope of the present invention. Any modifications, equivalent substitutions, deformation improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A rotating neutron spectrum online measurement device, characterized in that: The system includes a bracket, a tray, a Bonner ball, a rotating platform, and a rotating axis. Bonner balls of different sizes are spirally arranged from top to bottom on the bracket with the tray. The base of the bracket is installed on the rotating platform, which is driven by the rotating axis to rotate at a constant speed. Each Bonner ball is equipped with an independent preamplifier. After synchronous signal acquisition, the multi-channel signal processing unit independently outputs the count rate value of each channel.

2. The rotary neutron spectrum online measuring device according to claim 1, characterized in that: The Bonner sphere adopts a polyethylene moderation shell, and a thermal neutron detector is placed in the center.

3. The rotary neutron spectrum online measuring device according to claim 1, characterized in that: The Bonner sphere adopts a bare spherical thermal neutron detector without a moderating shell.

4. The rotary neutron spectrum online measuring device according to claim 2 or 3, characterized in that: The thermal neutron detector uses an active thermal neutron detector, including 3 He proportional counter, BF3 proportional counter, or 6 LiI crystal detector.

5. The rotary neutron spectrum online measuring device according to claim 1, characterized in that: The Bonner balls are placed on the tray of the bracket in order from large to small in size from bottom to top.

6. The rotary neutron spectrum online measuring device according to claim 1, characterized in that: The horizontal distance between the center of each Bonner ball and the bracket is the same.

7. The rotary neutron spectrum online measuring device according to claim 1, characterized in that: The rotating platform is driven by a motor control unit to control the rotation axis to rotate, so that the platform rotates horizontally at a uniform speed.

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