Thermoluminescence field dosimeter for measuring neutron energy spectrum
By designing a small-sized thermoluminescent field dosimeter and using 6LiF and 7LiF thermoluminescent dosimeters, the problem of inaccurate neutron spectrum measurement in narrow spaces and large neutron gradients has been solved, realizing accurate neutron spectrum measurement in narrow spaces and large-scale spaces. It is suitable for nuclear facilities such as fission reactors, fusion reactors and medical accelerators.
Patent Information
- Application Number
- CN202511506066.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-21
- Publication Date
- 2026-01-16
AI Technical Summary
Existing neutron energy spectrum measurement equipment is inaccurate in confined spaces and in situations with large neutron field gradients, and cannot accurately obtain neutron energy spectrum information at specific locations, especially in nuclear facilities such as fission reactors, fusion reactors, and medical accelerators, where errors exist.
A small-sized thermoluminescent field dosimeter was designed, comprising a front-end component, a central component, and a back-end component. It uses 6LiF and 7LiF thermoluminescent dosimeters and is detachably connected. It is suitable for measurement applications in confined spaces and with large neutron gradients, covering a neutron energy response range of 0.0253eV to 20MeV. It is applicable to nuclear facilities such as fission reactors, fusion reactors, and medical accelerators.
It enables accurate measurement of neutron energy spectrum in narrow spaces and situations with large neutron gradients. It has a wide range of applications and can construct different neutron energy response functions at different locations, reducing counting uncertainty. It is suitable for fine measurement in narrow spaces and large-scale spaces.
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Figure CN121348401A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of neutron measurement technology, and specifically discloses a thermoluminescent field dosimeter for measuring neutron energy spectra. Background Technology
[0002] Nuclear facilities such as fission reactors, fusion reactors, and accelerators continuously produce neutrons, which are used for purposes such as power generation, power supply, isotope production, and medical testing. Specific locations require neutron spectrum information for various applications, including fission reactor fuel irradiation testing, reactor and accelerator isotope production, bioaccelerator-based medical testing (BNCT), fusion reactor diagnostics, and reactor shielding verification. Due to the effects of deep penetration, the calculated neutron spectrum around the reactor core or target material has a certain degree of error, and this error increases with distance from the core or target. Currently, there is no good way to solve this problem. Therefore, it is necessary to obtain neutron spectrum information at specific locations through experimental measurements to further feedback or correct shielding calculations. This information can also provide crucial information (irradiation time or detection time) for fuel irradiation, isotope irradiation, and human detection programs, and can also provide key information on whether a fusion reactor has achieved its expected functional indicators.
[0003] Measuring neutron spectra can provide feedback or correction to shielding calculations, obtain irradiation times of fuel and isotopes, as well as human irradiation times, and provide crucial information for fusion reactor diagnostics. Nuclear facilities such as fission reactors, fusion reactors, and accelerators, especially small nuclear facilities, are compactly arranged with limited space and large radiation field gradients. Existing measurement equipment suffers from inaccurate dose rate measurements under conditions of significant small-scale spatial radiation gradient variations. For example, online neutron spectrometers are relatively large and require a combination of detectors at different locations to complete neutron spectrum measurements. Due to the presence of the moderator layer, the distance between different detectors is considerable, resulting in an average neutron spectrum reading across the area occupied by the measuring equipment, which cannot accurately obtain neutron spectrum information at a specific point. Therefore, the design and development of small-sized neutron detectors is necessary. Summary of the Invention
[0004] This invention provides a thermoluminescent field dosimeter for measuring neutron energy spectra. It has a wide neutron energy response range, covering 0.0253 eV to 20 MeV, and is suitable for neutron energy spectrum measurement in nuclear facilities such as fission reactors, fusion reactors, and medical accelerators. It is especially suitable for measurement in confined spaces and in situations with large neutron field gradients.
[0005] This invention is achieved through the following technical solution: A thermoluminescent dosimeter for measuring neutron energy spectrum includes a thermoluminescent dosimeter body, which includes a front-end component, a rear-end component, and a central component located between the front-end component and the rear-end component. The central component and the rear-end component are detachably connected to the front-end component. The distance between the front surface of the central component and the front surface of the front component is 1mm, and the distance between the front surface of the rear component and the front surface of the front component is 7mm. Both the front surfaces of the central component and the rear component are equipped with... 6 LiF thermoluminescent dosing tablets and 7 LiF thermoluminescent dosing tablets. The detachable connection allows for smooth removal of the thermoluminescent dosing tablets without the need for forceful disassembly. 6 LiF- 7 The LiF thermoluminescence dosimeter housing does not exhibit deformation or disassembly difficulties during repeated use.
[0006] The LiF thermoluminescent dosimeters are placed 1 mm and 7 mm from the front surface, with a pair of thermoluminescent dosimeters placed at 1 mm and 7 mm respectively. 6 LiF, 7 LiF thermoluminescent dosimeters were used to compare neutron energy response functions at different depths (1 mm, 3 mm, 5 mm, and 7 mm) using MCNP simulations. The results for 1 mm and 7 mm depths were also compared. 6 The LiF thermoluminescent dosimeter exhibits the greatest difference in neutron energy response, and is significantly different from thermoluminescent dosimeters that place the dosimeter at the same depth.
[0007] In this invention, the main body of the thermoluminescent dosimeter has dimensions of 1.8cm × 1.8cm × 1cm and uses a material with a density of 0.95g / cm³. 3 High-density polyethylene is used as the substrate. The overall size is greatly reduced to the centimeter level, an order of magnitude smaller than existing online neutron spectrometers. This makes it particularly suitable for measurements in confined spaces and with large neutron gradients, and also applicable to neutron energy spectrum measurements in fine-grained environments on large scales. Polyethylene is rich in hydrogen, providing excellent moderation, making it the most ideal detector moderation material currently available.
[0008] In this invention, the dimensions of the front-end component are 1.8cm×1.8cm×0.7cm, the dimensions of the central component are 1cm×1cm×0.6cm, and the dimensions of the rear-end component are 1.8cm×1.8cm×0.3cm.
[0009] In this invention, 6 LiF thermoluminescent dosing tablets and 7 The size of the LiF thermoluminescent dosimeter is Φ4.5mm × 0.8mm.
[0010] In this invention, the front surface of the central component6 LiF thermoluminescent dosing tablets 6 The Li content is 30%, and the front surface of the back-end component is... 6 LiF thermoluminescent dosing tablets 6 The Li content is 90%. The content is 30%. 6 Li content is 90%. 6 The different neutron energy responses of Li allow for the construction of two distinct neutron energy response functions within a spatial range of only 6 mm, satisfying the requirements for neutron spectrum interpretation.
[0011] In this invention, the front surface of the central component and the front surface of the rear component... 7 LiF thermoluminescent dosing tablets 7 The Li content was 99.629% in all samples.
[0012] In this invention, a pair of circular grooves are respectively provided on the front surface of the central component and the front surface of the rear component, and on the same surface... 6 LiF thermoluminescent dosing tablets and 7 The LiF thermoluminescent dosimeters are each placed in a circular groove with dimensions of Φ4.5mm × 0.8mm.
[0013] In this invention, the rear surface of the front-end component is provided with a connection hole and a groove, the central component is installed in the groove, and the front surface of the rear-end component is provided with a connection post, which is adapted to be inserted into the connection hole.
[0014] In this invention, the front-end component has connection holes at the four corners of its rear surface, and the rear-end component has connection posts on its front surface that correspond one-to-one with the connection holes. The size of the connection holes is Φ3mm×3mm.
[0015] The technical solution of the present invention has at least the following advantages and beneficial effects: (1) The thermoluminescence field dosimeter has an overall size of 1.8cm×1.8cm×1cm, which is greatly reduced to the centimeter level. Compared with the existing online neutron spectrometer, the size is reduced by an order of magnitude, making it particularly suitable for measurement in narrow spaces and large neutron gradients. It is also suitable for fine field neutron energy spectrum measurement in large-scale spaces.
[0016] (2) The thermoluminescent dosimeter has a wide neutron energy response range, covering 0.0253 eV-20 MeV, making it suitable for neutron energy spectrum measurements in nuclear facilities such as fission reactors, fusion reactors, and medical accelerators. It also has a wide applicable neutron fluence rate range, from 1 to 1 × 10⁻⁶ eV. 8 n / (cm 2 ·s).
[0017] (3) The γ energy range of the thermoluminescent dosimeter is 15 keV-4.5 MeV. Within a given energy range, when the intensity of γ relative to neutrons is less than 10, it can enable the two... 6 The proportion of gamma response in the total response of a LiF thermoluminescent dosimeter should not exceed 6%, which helps reduce the uncertainty of neutron counting in the thermoluminometer. The suitable gamma fluence rate range is 231–1.08 × 10⁻⁶. 8 γ·cm -2 ·s -1 . Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the structure of a thermoluminescence field dosimeter for measuring neutron energy spectra provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the front-end component provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the central component provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the backend component provided in an embodiment of the present invention; Figure 5 The thermoluminescent dosimeter provided in this embodiment of the invention uses thermoluminescent dosimeters at different distances. 6 Schematic diagram of neutron energy response function for Li content; Figure 6 A schematic diagram of the neutron fluence energy response function of a thermoluminescent field dosimeter provided in an embodiment of the present invention; Figure 7 A schematic diagram of the γ-flux energy response function of a thermoluminescent field dosimeter provided in an embodiment of the present invention.
[0019] Reference numerals: 1-Front-end component, 2-Central component, 3-Rear-end component, 4-Circular groove, 11-Connecting hole, 12-Groove, 31-Connecting post. Detailed Implementation
[0020] The following is a detailed description of the implementation method in conjunction with the accompanying drawings.
[0021] Example 1 Reference Figures 1-4 As shown, this embodiment provides a thermoluminescent field dosimeter for measuring neutron energy spectrum, including a thermoluminescent field dosimeter body. The thermoluminescent field dosimeter body includes a front end component 1, a rear end component 3, and a central component 2 located between the front end component 1 and the rear end component 3. The central component 2 and the rear end component 3 are detachably connected to the front end component 1. The distance between the front surface of the central component 2 and the front surface of the front component 1 is 1mm, and the distance between the front surface of the rear component 3 and the front surface of the front component 1 is 7mm. Both the front surfaces of the central component 2 and the rear component 3 are provided with... 6 LiF thermoluminescent dosing tablets and 7 LiF thermoluminescent dosing tablets.
[0022] In a preferred embodiment, the thermoluminescence field dosimeter body has dimensions of 1.8cm × 1.8cm × 1cm and uses a material with a density of 0.95g / cm³. 3 High-density polyethylene is used as the base material.
[0023] In a preferred embodiment, the front-end component 1 has a size of 1.8cm × 1.8cm × 0.7cm, the center component 2 has a size of 1cm × 1cm × 0.6cm, and the rear-end component 3 has a size of 1.8cm × 1.8cm × 0.3cm.
[0024] In the preferred embodiment, 6 LiF thermoluminescent dosing tablets and 7 The size of the LiF thermoluminescent dosimeter is Φ4.5mm × 0.8mm.
[0025] In a preferred embodiment, the front surface of the central component 2 6 LiF thermoluminescent dosing tablets 6 The Li content is 30%, and the front surface of the back-end component 3 is... 6 LiF thermoluminescent dosing tablets 6 The Li content is 90%.
[0026] In a preferred embodiment, the front surface of the central component 2 and the front surface of the rear component 3 are... 7 LiF thermoluminescent dosing tablets 7 The Li content was 99.629% in all samples.
[0027] In a preferred embodiment, the front surface of the central component 2 and the front surface of the rear component 3 are each provided with a pair of circular grooves 4, and the grooves on the same surface are... 6 LiF thermoluminescent dosing tablets and 7 LiF thermoluminescent dosimeters are respectively placed in a circular groove 4, the dimensions of which are Φ4.5mm×0.8mm.
[0028] In a preferred embodiment, the rear surface of the front component 1 is provided with a connection hole 11 and a groove 12, the central component 2 is installed in the groove 12, and the front surface of the rear component 3 is provided with a connection post 31, which is adapted to be inserted into the connection hole 11.
[0029] In a preferred embodiment, the front end component 1 has connection holes 11 at the four corners of its rear surface, and the rear end component 3 has connection posts 31 on its front surface that correspond one-to-one with the connection holes 11. The size of the connection holes 11 is Φ3mm×3mm.
[0030] The measurement method for thermoluminescence field dosimeters is as follows: 1) Reference Figure 1 Assemble the thermoluminescent field dosimeter, place it in the tooling, and place it in a specific location of a nuclear facility (such as a fission reactor, fusion reactor, or medical accelerator) for a certain period of time for irradiation. 2) After irradiation, transfer the tooling to the laboratory and remove the thermoluminescent dosimeter. 3) Measure the reading of the thermoluminescent dosimeter on the thermoluminescent dosimeter. The specific steps are as follows: a) Open the thermoluminescent dosimeter's measurement drawer, place one detector piece from the dosimeter flat in the center of the heating plate, and slowly push the measurement drawer back; b) Press the measurement button, and the dosimeter will automatically heat and measure the detector. Once the measurement is complete, the final result displayed on the dosimeter is the measured value of the detector. c) Once the heating temperature drops below 100℃, open the measurement drawer, remove the tested detector, and place it in a dedicated collection container. Record the relevant measurement data, dosimeter information, testing equipment information, and testing environmental conditions in the thermoluminescent dosimeter testing record sheet.
[0031] d) Calculate the neutron thermoluminescence dose rate according to the following formula.
[0032] (1) In the formula: H—neutron dose equivalent, mSv; -neutron( 6 Li) The net value of the average readings of the sensitive element under neutron irradiation; —Photon ( 7 Li) The net value of the average readings of the sensitive element under neutron irradiation; — Neutron-sensitive element reading (net value) under a fixed dose (e.g., 2 mSv) of photon irradiation; —The reading (net value) of the photon-sensitive element under a fixed dose (e.g., 2 mSv) of photon irradiation.
[0033] N—calibration factor, mSv.
[0034] (2) In the formula: — Neutron dose equivalent rate, mSv / h; H—neutron dose equivalent, mSv; t—Irradiation time, h.
[0035] 4) Based on the known neutron energy response function, the neutron energy spectrum at the test location is solved using neutron spectrum analysis software.
[0036] Reference Figure 5 Through simulation calculations, different sizes of objects placed at the same locations (1mm, 3mm, 5mm, and 7mm) were compared. 6 The neutron energy response functions of Li-containing compounds have different numerical values but similar shapes, with 30% being a different case. 6 Li neutron energy response function, 50% 6 Li neutron energy response function, 70% 6 Li neutron energy response function, 90% 6 The Li neutron energy response function increases sequentially. Significant differences exist in the neutron energy response function at different locations; the difference becomes more pronounced with increasing distance. For example, at a distance of 1 mm, the difference is 30%. 6 LiF thermoluminescent dosing spectrometer placed at 7mm with 90% of its length. 6 The neutron energy response function of LiF thermoluminescent dosimeters showed the greatest difference.
[0037] Reference Figure 6 Placed at 1mm 6 LiF thermoluminescent dosing tablets 6 The Li content is 30%, and it is placed at a depth of 7mm. 6 LiF thermoluminescent dosing tablets 6 The Li content is 90%, and the content is 30%. 6 Li content is 90%. 6 The neutron energy responses of Li exhibit significant differences, allowing for the construction of two distinct neutron energy response functions within a mere 6 mm spatial range, thus satisfying the requirements for neutron spectrum interpretation. The thermoluminescent dosimeter of this invention covers an energy response range of 0.0253 eV–20 MeV, with a neutron fluence applicable range of 1–1 × 10⁻⁶. 8 n / (cm 2 ·s).
[0038] The thermoluminescence local dosimeter and placement of the present invention 6 LiF thermoluminescent dosing plate, Cu sheet shielding 7 LiF thermoluminescent dosing plate, without Cu sheet obstruction. 7 The neutron personal dosimeters based on LiF thermoluminescent dosimeters differ significantly. This invention provides a neutron energy spectrum and allows for placement... 6LiF thermoluminescent dosing plate, Cu sheet shielding 7 LiF thermoluminescent dosing plate, without Cu sheet obstruction. 7 Personal dosimeters using LiF thermoluminescent dosimeters cannot distinguish neutron energy spectra; they can only measure thermal neutron doses. They are also affected by Cu plates that provide shielding. 7 LiF thermoluminescent dosing plate and without Cu sheet shielding 7 LiF thermoluminescent dosimeters can be used to determine the energy of gamma rays.
[0039] Reference Figure 7 The thermoluminescent dosimeter of this invention has a γ energy range of 15 keV-4.5 MeV. Within a given energy range, when the intensity of γ relative to neutrons is less than 10, it can enable two... 6 The proportion of γ response in the total response of LiF thermoluminescence dosimeter is no higher than 6%, which helps to reduce the uncertainty of neutron counting in thermoluminescence meter.
[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A thermoluminescence field dosimeter for measuring a neutron energy spectrum, characterized in that The thermoluminescence dosimeter body comprises a front end assembly, a rear end assembly and a center assembly between the front end assembly and the rear end assembly, and the center assembly and the rear end assembly are detachably connected with the front end assembly respectively. The distance between the front surface of the center component and the front surface of the front end component is 1 mm, the distance between the front surface of the rear end component and the front surface of the front end component is 7 mm, and the front surfaces of the center component and the rear end component are provided with 6 LiF thermoluminescence dosimetry 7 LiF thermoluminescence dosimetry 2. The thermoluminescence dosimeter for measuring the neutron energy spectrum according to claim 1, characterized in that, The size of the thermoluminescence field dose meter body is 1.8 cm x 1.8 cm x 1 cm, and high-density polyethylene with a density of 0.95 g / cm 3 is used as the base material.
3. The thermoluminescence dosimeter for measuring the neutron energy spectrum according to claim 1, wherein The size of the front end assembly is 1.8cm*1.8cm*0.7cm, the size of the center assembly is 1cm*1cm*0.6cm, and the size of the rear end assembly is 1.8cm*1.8cm*0.3cm.
4. The thermoluminescence dosimeter for measuring a neutron energy spectrum according to claim 1, wherein 6 LiF thermoluminescence dosimeter sheet and 7 The size of the LiF thermoluminescence dosimeter sheet was Φ4.5 mm x 0.8 mm.
5. The thermoluminescence dosimeter for measuring the neutron energy spectrum according to claim 1, wherein the front surface of the center assembly 6 LiF thermoluminescence dosimeter 6 Li content of 30%, the front surface of the back end assembly 6 LiF thermoluminescence dosimeter 6 Li content of 90%.
6. The thermoluminescence dosimeter for measuring the neutron energy spectrum according to claim 1, wherein, the front surface of the central assembly and the front surface of the rear end assembly 7 LiF thermoluminescence dosimeter 7 The Li percentage content was 99.629% in each.
7. The thermoluminescence dosimeter for measuring the neutron energy spectrum according to claim 1, wherein, The front surface of the central component and the front surface of the rear end component are respectively provided with a pair of circular grooves 6 LiF thermoluminescence dosimeter sheet 7 The LiF thermoluminescence dosimeter sheet is arranged in a circular groove, and the size of the circular groove is Φ4.5mm×0.8mm.
8. The thermoluminescence dosimeter for measuring the neutron energy spectrum according to claim 1, wherein, The rear surface of the front end assembly is provided with connecting holes and a groove, the center assembly is installed in the groove, and the front surface of the rear end assembly is provided with connecting columns which are adaptively inserted into the connecting holes.
9. The thermoluminescence dosimeter for measuring the energy spectrum of neutrons according to claim 8, characterized in that, The four corners of the rear surface of the front end assembly are provided with connecting holes, the front surface of the rear end assembly is provided with connecting columns corresponding to the connecting holes one by one, and the size of the connecting holes is Φ3mm*3mm.