Radioactive aerosol integrated measuring device and method

Abstract

The application discloses a radioactive aerosol integrated measuring device and method, and relates to the technical field of radioactive aerosol measurement. The measuring device comprises a shell, filter paper, a first detector, a preamplifier, a second detector and a voltage division amplifier. The inside of the shell is sequentially provided with a first mounting chamber, a supporting chamber and a second mounting chamber from top to bottom. An air inlet is formed in the top of the shell. A channel for gas passing is formed between the inner wall of the shell and the first mounting chamber. The bottom of the first mounting chamber is communicated with the top of the supporting chamber. An air outlet is formed in the side wall of the shell and penetrates through the supporting chamber. The filter paper is arranged in a through groove between the first mounting chamber and the supporting chamber. The first detector is arranged in the first mounting chamber. The input end of the preamplifier is electrically connected with the output end of the first detector. The output end of the preamplifier is electrically connected with the input end of a multichannel and the input end of a coincidence circuit. The application can realize integrated measurement of F-18 nuclear aerosol and other nuclear radioactive aerosol.

Description

Technical Field

[0001] This invention relates to the field of radionuclide detection technology, specifically to an integrated measurement device and method for radioactive aerosols. Background Technology

[0002] During the operation of a nuclear power plant, the primary circuit pressure boundary may be damaged for various reasons. In order to determine whether the level of radioactivity in the environment is normal and whether the primary circuit pressure boundary is leaking, it is necessary to deploy relevant monitoring equipment such as aerosol detection devices and F-18 detection devices outside the primary circuit pressure boundary. By detecting the activity concentration of radionuclides, the level of radioactivity in the environment can be judged, and then it can be determined whether the nuclear power plant has generated radioactive leakage.

[0003] Commonly used aerosol detection devices typically consist of a sampling line, filter paper, a PIPS (Peripherally Passivated Ion Implanted Silicon) detector, a preamplifier, a main amplifier, and a support frame. Radioactive aerosols accumulate at the filter paper via the sampling line, and the PIPS detector detects the radioactive aerosols by detecting the α or β rays produced during their decay.

[0004] A typical F-18 detection device usually consists of a sampling pipeline, filter paper, a sodium iodide detector, a preamplifier, a main amplifier, a coincidence circuit, and a support frame. F-18 is a radioactive nuclide with a half-life of 109.77 minutes. During decay, it produces β-rays with an average energy of approximately 249 keV at a fixed branching ratio. + Particle, when β + After losing energy due to collision, the particle combines with an electron to generate two annihilation photons with opposite directions of motion and an energy of 0.511 MeV. When using the F-18 detector, the F-18 aerosol is enriched at the filter paper through the sampling pipeline. The sodium iodide detector detects the F-18 nuclide by detecting the photons after the annihilation of the β+ particles.

[0005] Because the F-18 detector and other radioactive aerosol detectors are usually designed separately, the overall size of the equipment is large. Due to the space constraints of the nuclear power plant, it is difficult to achieve simultaneous monitoring of multiple nuclides in a limited space. Furthermore, it is impossible to simultaneously measure the activity concentration of F-18 nuclide and other α and β radionuclides on the same filter paper sample. Therefore, how to integrate the aerosol detector and the F-18 detector to reduce the size while still achieving integrated measurement of F-18 nuclide aerosols and other radioactive aerosols has become a problem that needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide an integrated measurement device and method for radioactive aerosols, so as to solve the technical problems in the prior art where the F-18 detector is arranged separately from other nuclide detectors, resulting in large equipment size and difficulty in achieving simultaneous detection of multiple nuclides.

[0007] The technical solution of this invention is: An integrated measurement device for radioactive aerosols includes a housing, filter paper, a first detector, a preamplifier, a second detector, a photomultiplier tube, and a voltage divider amplifier. The housing contains, from top to bottom, a first mounting chamber, a support chamber, and a second mounting chamber. An air inlet is located at the top of the housing. A gas passage is formed between the inner wall of the housing and the first mounting chamber. The bottom of the first mounting chamber communicates with the top of the support chamber. An air outlet is located on the side wall of the housing, extending through the support chamber. The filter paper is disposed within a horizontal groove on the housing, located between the first mounting chamber and the support chamber. The first detector... A preamplifier is disposed within the first mounting chamber and located above the filter paper to detect alpha and beta rays generated by the decay of radioactive nuclides on the filter paper. The input of the preamplifier is electrically connected to the output of the first detector, and the output of the preamplifier is electrically connected to the input of a multichannel circuit and the input of a coincidence circuit. The outputs of the multichannel circuit and the coincidence circuit are electrically connected to a data processing circuit. A second detector is disposed within the second mounting chamber to detect gamma rays generated by the decay of radioactive nuclides on the filter paper. The input of a voltage divider amplifier is electrically connected to the second detector, and the output of the voltage divider amplifier is electrically connected to the input of the coincidence circuit.

[0008] Preferably, as a further improvement of the present invention, the first mounting chamber is mounted and fixed on the inner wall of the housing, the upper side wall of the first mounting chamber is conical and is positioned directly opposite the air inlet, and the lower side wall of the first mounting chamber is cylindrical.

[0009] Preferably, as a further improvement of the present invention, the first detector is a PIPS detector or a β plastic scintillator detector, and the second detector is any one of a sodium iodide crystal detector, a high-purity germanium detector, a zinc cadmium telluride detector, and a lanthanum bromide detector.

[0010] Preferably, as a further improvement of the present invention, the housing is provided with a filter paper replacement mechanism, which includes an active roll, a driven roll, a drive motor, and two tensioning rollers. The active roll and the driven roll are respectively disposed inside the housing and located on both sides of the support cavity. The two ends of the filter paper are respectively wound on the active roll and the driven roll. The output shaft of the drive motor is connected to the active roll and is used to drive the active roll to rotate. The two tensioning rollers are respectively disposed above the active roll and the driven roll, and the two tensioning rollers contact the lower side of the filter paper to change the direction of movement of the filter paper.

[0011] Preferably, as a further improvement of the present invention, the filter paper replacement mechanism includes an active roll, a driven roll, a drive motor, and two tension rollers; the active roll and the driven roll are respectively disposed inside the housing and located on both sides of the support cavity, and the two ends of the filter paper are respectively wound on the active roll and the driven roll; the output shaft of the drive motor is connected to the active roll and is used to drive the active roll to rotate; the two tension rollers are respectively disposed above the active roll and the driven roll, and the two tension rollers contact the lower side of the filter paper to keep the filter paper taut.

[0012] This invention also discloses a method for measuring radioactive aerosols, implemented using the aforementioned integrated radioactive aerosol measuring device, comprising the following steps: The gas sample to be tested is passed through the measuring device and filtered through filter paper, which enriches the radioactive aerosols in the air on the surface of the filter paper to form an aerosol sample. The first detector is used to detect the α and β rays generated by the decay of the aerosol sample and generate a first electrical signal. The first electrical signal is amplified by a preamplifier and sent to the multichannel and coincidence circuits respectively. The second detector is used to detect the γ rays generated by the decay of the aerosol sample and generate a second electrical signal. The second electrical signal is amplified by a voltage divider amplifier and sent to the coincidence circuit. The first electrical signal is processed by the multi-channel system, and the energy spectrum of the rays is formed by distinguishing them according to energy and then transmitted to the data processing circuit. The data processing circuit, based on the energy spectrum of the formed ray and the preset region of interest, distinguishes the total α count, the total β count, and the characteristic counts of radon-thorium progeny Po-218, Po-214, and Po-212. Through the radon-thorium progeny compensation algorithm, it determines the artificial radioactive β nuclide count from the total β count in combination with the characteristic counts of Po-218, Po-214, and Po-212, and determines the artificial radioactive α nuclide count from the total α count. Based on the artificial radioactive α nuclide count and the measurement parameters, it determines the activity concentration information of the artificial radioactive α nuclide in the gas. The measurement parameters include the detector's detection efficiency for the target ray, the measurement period, the filtration efficiency of the filter paper (2), and the sampling volume within the measurement period. The coincidence circuit converts the β generated during the decay of F-18 nuclide + -γ coincidence signal counting determines the F-18 nuclide count and transmits it to the data processing circuit. Based on the F-18 nuclide count and the measurement parameters, the activity concentration of F-18 nuclide in the gas is determined.

[0013] Preferably, as a further improvement of the present invention, the activity concentration information of each nuclide is determined by the following formula: in: Nuclide activity concentration; Nuclide counting; The detector's detection efficiency for nuclides; T Measurement cycle; Filter paper filtration efficiency; The sampling volume within the measurement period.

[0014] Preferably, as a further improvement of the present invention, the process of counting coincidence signals generated during the decay of F-18 nuclides by the coincidence circuit includes the following steps: The coincidence circuit receives the first electrical signal amplified by the preamplifier and the second electrical signal amplified by the voltage divider amplifier, and determines the energy and timing relationship between the two signals. When the following conditions are met simultaneously, it determines it as an F-18 nuclide decay event and generates a coincidence count: a. The energy deposited in the first detector is less than or equal to the β produced by the decay of F-18. + The maximum energy of a particle; b. The energy deposited in the second detector is 0.511 MeV; c. The preamplifier and the voltage divider amplifier simultaneously generate pulse signals.

[0015] Preferably, as a further improvement of the present invention, when the aerosol sample collected on the filter paper at the detection position is detected to exceed a preset limit, the drive motor automatically drives the active drum to rotate, thereby moving the filter paper roll and replacing the filter paper at the detection position.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This design integrates a gas flow channel, filter paper enrichment, α / β detection, and γ detection into a single device. Samples are collected using a single filter paper, and α / β nuclide measurements are performed using a first detector. A second detector and coincidence circuitry are then used to achieve specific identification of F-18. This design solves the problems of separate, bulky multi-nucleus monitoring devices, enabling simultaneous measurement of artificial α, β nuclides and F-18 within a limited space. This improves monitoring efficiency and reliability. Compared to traditional separate aerosol detectors or F-18 detectors, this design achieves miniaturization of the detection device while simultaneously enabling integrated measurement of F-18 nuclide aerosols and other radioactive aerosols. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an integrated radioactive aerosol measuring device according to the present invention.

[0018] Figure 2 This is a schematic diagram illustrating the measurement principle of an integrated radioactive aerosol measuring device according to the present invention.

[0019] Figure 3 This is the energy spectrum of the X-rays. Detailed Implementation

[0020] The following is combined with Figures 1-3 The specific embodiments of the present invention will be described in detail below. In the description of the invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0021] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0022] Example 1 like Figures 1-3As shown, this embodiment of the invention provides an integrated measurement device for radioactive aerosols, including a housing 1, filter paper 2, a first detector 3, a preamplifier 4, a second detector 5, and a voltage divider amplifier 6. The housing 1 has, from top to bottom, a first mounting chamber 11, a support chamber 12, and a second mounting chamber 13. An air inlet 14 is provided at the top of the housing 1. A gas passage is formed between the inner wall of the housing 1 and the first mounting chamber 11. The bottom of the first mounting chamber 11 communicates with the top of the support chamber 12. An air outlet 15 is provided on the side wall of the housing 1, and the air outlet 15 penetrates the support chamber 12. The filter paper 2 is disposed within a through groove, which is horizontally opened on the housing 1 and located between the first mounting chamber 11 and the support chamber 12. The first detector 3... The first detector 3 is located in the first mounting chamber 11 and above the filter paper 2. It is used to detect alpha and beta rays generated by the decay of radioactive nuclides on the filter paper 2. The input of the preamplifier 4 is electrically connected to the output of the first detector 3. The output of the preamplifier 4 is electrically connected to the input of the multichannel circuit and the input of the coincidence circuit. The output of the multichannel circuit and the output of the coincidence circuit are electrically connected to the data processing circuit. The second detector 5 is located in the second mounting chamber 13 and is used to detect gamma rays generated by the decay of radioactive nuclides on the filter paper 2. The voltage divider amplifier 6 is located below the second detector 5. The input of the voltage divider amplifier 6 is electrically connected to the output of the second detector 5. The output of the voltage divider amplifier 6 is electrically connected to the input of the coincidence circuit.

[0023] In this embodiment, the structural design of the housing 1, consisting of a first mounting chamber 11, a support chamber 12, and a second mounting chamber 13 arranged sequentially from top to bottom, achieves a reasonable layout of the gas flow channels, allowing the gas sample to flow uniformly across the filter paper surface and improving aerosol enrichment efficiency. By setting an air inlet at the top of the housing 1 and an air outlet 14 on the side wall, with the outlet 14 penetrating the support chamber 12, a top-to-bottom airflow channel is formed, avoiding measurement errors caused by airflow turbulence. The filter paper 2 is positioned between the first mounting chamber 11 and the support chamber 12, serving as an enrichment platform for radioactive aerosols and providing a unified sample basis for subsequent multi-nucleus measurements. The first detector 3 is located within the first mounting chamber 11 and above the filter paper, effectively detecting alpha and beta rays generated by the decay of radioactive nuclides on the filter paper, providing crucial data for the identification and measurement of alpha / beta nuclides. The preamplifier 4 is electrically connected to the first detector and sends the amplified signal to both the multichannel and coincidence circuits, achieving dual utilization of the signal, supporting both energy spectrum analysis and coincidence measurement, thus improving data processing efficiency. The second detector 5 is located within the second mounting chamber 13 and below the filter paper. It detects gamma rays generated by the decay of radioactive nuclides on the filter paper, particularly annihilation photons generated by the decay of F-18, providing a physical basis for the specific identification of F-18 nuclides. A voltage divider amplifier 6 is electrically connected to the second detector 5 and sends the amplified signal to a coincidence circuit for matching with the signal from the preamplifier, achieving accurate identification of F-18 nuclides. Through the synergistic operation of the above structures, this application solves the problem of large equipment size caused by the separate arrangement of the F-18 detection device and other nuclide detection devices in the prior art. It achieves integrated measurement of F-18 nuclides, artificial alpha nuclides, and artificial beta nuclides in the same device, significantly reducing equipment size and improving the comprehensiveness and accuracy of nuclide monitoring. This design not only meets the special requirements of space constraints in nuclear power plants but also achieves simultaneous measurement of multiple nuclides through a single filter paper platform, avoiding redundant configuration of multiple sampling systems, effectively solving the problem of missed detections, and providing reliable technical support for nuclear safety monitoring.

[0024] The specific measurement principle of this device is as follows: The gas sample enters the housing 1 through the inlet 14 under the action of the sampling pump. After being filtered by the filter paper 2 from top to bottom, the gas sample is discharged from the outlet 15. At this time, aerosols in the air accumulate on the surface of the filter paper 2 to form an aerosol sample. The F-18 nuclide accumulated on the filter paper 2 undergoes β⁺ decay. The emitted positrons are slowed down and annihilated with electrons within a few millimeters, producing 0.511 MeV γ photons. The γ photons penetrate downwards through the filter paper 2 and the support cavity 12 and are detected by the second detector 5. Another part of the β⁺ particles or their bremsstrahlung radiation is received by the first detector 3 above. The preamplifier 4 and the voltage divider amplifier 6 output two pulses respectively. The coincidence circuit is based on the energy threshold (β⁺≤635 keV, γ=0.511 MeV) and the time window (≤10). The detector (ns) performs joint identification to detect F-18 decay events. At the same time, all α / β pulses output by the first detector 3 are sent to the multichannel analyzer through the same preamplifier 4 to construct the energy spectrum of the full-energy range of the radiation. After the spectrum is despectrographed by the data processing circuit, the total α count, total β count, and radon progeny characteristic peak count are obtained. Combined with the radon-thorium progeny compensation algorithm, the artificial α nuclide count and artificial β nuclide count are separated. Based on the detector's detection efficiency of the target radiation, the measurement period, the filtration efficiency of the filter paper 2, and the sampling volume within the measurement period, the activity concentration information of artificial radioactive α and β nuclides in the target is detected to determine whether a corresponding radioactive leak has occurred. Because the housing 1 provides a defined airflow path and X-ray transmission space, the filter paper 2, as the sole sampling interface, enables the co-location enrichment of multiple nuclides, avoiding the mechanical actions required by traditional methods of moving samples or switching detection modes. The vertical separation of the first detector 3 and the second detector 5 ensures the separable detection of β⁺ and γ signals. The dual-channel output of the preamplifier 4 allows a single decay event to carry multiple pieces of information. Thus, without increasing the physical volume, the active concentration measurement of multiple nuclides such as artificial α nuclides, artificial β nuclides, and F-18 is achieved simultaneously. This solves the core problems of the discrete devices in the background technology, such as large size, asynchronous multi-nuclides, and low reliability of F-18 identification, achieving the goal of miniaturized, multifunctional, and high-precision integrated measurement of radioactive aerosols.

[0025] In other embodiments of the present invention, such as Figure 1 As shown, the first mounting chamber 11 is mounted and fixed on the inner wall of the housing 1. The upper side wall of the first mounting chamber 11 is conical and is positioned directly opposite the air inlet 14. The lower side wall of the first mounting chamber 11 is cylindrical. Through the above arrangement, the outer wall of the first mounting chamber 11 and the housing 1 form a gas delivery channel. Moreover, the streamlined surface of the housing 1 can reduce the deposition of aerosols in the sampling pipeline.

[0026] In another embodiment of the present invention, the type selection and parameter settings of the first detector 3 and the second detector 5 are adapted to the short-range characteristics of α / β / β⁺ particles and the penetrating characteristics of γ rays, respectively, to avoid crosstalk between detectors. The first detector 3 can be a PIPS detector or an α / β plastic scintillator detector, and the second detector 5 can be any one of a second detector, a scintillator detector such as a lanthanum bromide detector, or a semiconductor detector such as a high-purity germanium detector or a zinc cadmium telluride detector.

[0027] In another embodiment of the present invention, in order to prevent the sample collected by the filter paper 2 in the area facing the first detector 3 from exceeding the limit, a filter paper replacement mechanism is provided on the outside of the housing 1. The filter paper replacement mechanism is used to replace the filter area when the sample collected by the filter paper 2 exceeds the limit.

[0028] Specifically, the filter paper replacement mechanism includes an active roller 21, a driven roller 22, a drive motor, and two tension rollers 23. The active roller 21 and the driven roller 22 are respectively disposed inside the housing 1 and located on both sides of the support cavity 12. The two ends of the filter paper 2 are respectively wound on the active roller 21 and the driven roller 22. The output shaft of the drive motor is connected to the active roller 21 and is used to drive the active roller 21 to rotate. The two tension rollers 23 are respectively disposed above the active roller 21 and the driven roller 22. The two tension rollers 23 are in contact with the lower side of the filter paper 2 to keep the filter paper 2 taut. When the filter paper 2 is replaced by the filter paper replacement mechanism, the drive motor drives the active roller 21 to rotate, and the active roller 21 winds and pulls the filter paper 2 to move, thereby adjusting the filter paper 2 to face the detection area of ​​the first detector 3.

[0029] Example 2 Based on Example 1, this embodiment discloses a method for measuring radioactive aerosols, which is implemented using the aforementioned integrated radioactive aerosol measuring device and includes the following steps: S1: The gas sample to be tested flows through the measuring device and is filtered through filter paper 2, so that radioactive aerosols in the air are enriched on the surface of filter paper 2 to form an aerosol sample.

[0030] S2: The first detector 3 detects the α and β rays generated by the decay of the aerosol sample and generates a first electrical signal. This first electrical signal is amplified by a preamplifier and then sent to the multichannel and coincidence circuits. The second detector 5 detects the γ rays generated by the decay of the aerosol sample. The coincidence event between the γ rays and the β rays from the PIPS is used to identify the F-18 nuclide. F-18 is a representative nuclide of primary loop leakage in nuclear power plants and can provide a quantitative assessment of the primary loop leakage rate. Compared to a single sodium iodide detector determining activity through counting in a specific energy range, the accuracy of coincidence signal identification is greatly improved, effectively reducing false alarms during use. A second electrical signal is generated and amplified by a voltage divider amplifier 6 before being sent to the coincidence circuit.

[0031] S3: The multichannel processor processes the first electrical signal and divides it into energy spectra of the rays, which are then transmitted to the data processing circuit.

[0032] The multichannel pulse amplitude analyzer features baseline recovery, pulse shaping (trapezoidal or Gaussian filtering), dead-time correction, and automatic peak stabilization. Its input is the voltage pulse output from preamplifier 4, which, after analog-to-digital conversion, is distributed to the corresponding channel address according to amplitude, forming an energy spectrum containing the α peak, β continuous spectrum, and characteristic sub-peaks. The horizontal axis of the energy spectrum represents the channel address (corresponding to energy, in keV), and the vertical axis represents the count. The "data processing circuit" is an embedded ARM architecture system that executes the energy spectrum analysis algorithm. After receiving the raw energy spectrum data, this circuit performs energy scaling (using a 2²... 4 ¹Am、²³ 9 Pu、 90 Sr / 90 Operations include standard source calibration (such as Y), peak fitting, and region of interest (ROI) integration.

[0033] S4: The data processing circuit, based on the energy spectrum of the generated ray and the preset region of interest, distinguishes the total α count, total β count, and characteristic counts of radon-thorium progeny Po-218, Po-214, and Po-212. Through the radon-thorium progeny compensation algorithm, it determines the artificial radioactive β nuclide count from the total β count combined with the characteristic counts of Po-218, Po-214, and Po-212, and determines the artificial radioactive α nuclide count from the total α count. Based on the artificial radioactive β nuclide count and measurement parameters, it determines the activity concentration information of artificial radioactive β nuclides in the gas. Based on the artificial radioactive α nuclide count and measurement parameters, it determines the activity concentration information of artificial radioactive α nuclides in the gas. The measurement parameters include the detector's detection efficiency for the target ray, the measurement period, the filtration efficiency of filter paper 2, and the sampling volume within the measurement period.

[0034] Specifically, by calculating Figure 3The area of ​​each region of interest in the energy spectrum yields the total α count, total β count, and characteristic counts of radon-thorium progeny Po-218, Po-214, and Po-212. The activity concentration can be determined by combining the counts with the filtration efficiency and sampling volume.

[0035] The sampling volume refers to the cumulative volume of the air sample that has passed through the current sampling filter paper.

[0036] The radon-thorium progeny compensation algorithm is detailed in the applicant's patent application, CN120577841A, entitled "A Radon-Thorium Progeny Compensation Method Based on Genetic Algorithm." This method utilizes the characteristic that radon-thorium progeny simultaneously emits characteristic α and β particles during decay. By measuring the counts of specific progeny particles (Po-218, Po-214, Po-212) in the α energy spectrum, a universal radon-thorium progeny compensation coefficient is adaptively optimized and calculated from a large amount of environmental data using a genetic algorithm. The compensation coefficient is then used to calculate the artificial β count rate in the aerosols of the area under test.

[0037] Furthermore, based on the peak position reference peak position-energy scale relationship diagram of α nuclides, the specific types of α nuclides can be obtained by inferring their characteristic energies.

[0038] Regarding the determination of nuclide types: First, the peak position is identified using a peak-finding algorithm. By combining the peak position with the pre-stored peak position-energy correspondence in the device, the energy represented by this peak position can be determined. Then, by searching the pre-stored nuclide library in the device (which contains nuclide names and corresponding nuclide energies), the nuclide name can be determined by the nuclide energy.

[0039] S5: The coincidence circuit converts the β generated during the decay of F-18 nuclide. + -γ coincidence signal counting determines the F-18 nuclide technology and is transmitted to the data processing circuit, where β + The signal originates from the β generated during the decay of the F-18. + Interacting with the first detector 3, the γ signal originates from the β generated during the decay of F-18. + The gamma rays generated during annihilation interact with the second detector 5, and the activity concentration of F-18 nuclides in the gas is determined based on the F-18 nuclide count and measurement parameters.

[0040] The activity concentration information of each nuclide is determined by the following formula: In the formula: Indicates the activity concentration of a nuclide. x It represents different types of nuclides, and can be an artificial radioactive alpha nuclide, an artificial radioactive beta nuclide, or an F-18 nuclide.

[0041] This indicates the nuclide count, the source of which varies depending on the type of nuclide. x It represents different types of nuclides, and can be an artificial radioactive alpha nuclide, an artificial radioactive beta nuclide, or an F-18 nuclide.

[0042] The detection efficiency of the detector refers to the count rate response of the first detector 3 or the second detector 5 to the radioactivity of a specific nuclide on the filter paper 2 sample.

[0043] T The measurement cycle refers to the continuous time from the start of aerosol enrichment to the completion of a full energy spectrum acquisition and compliance determination, typically ranging from 30 minutes to 1 hour.

[0044] This indicates the filtration efficiency of the filter paper.

[0045] This indicates the sampling volume within the measurement period.

[0046] The process of counting coincidence signals generated during the decay of F-18 nuclides by the coincidence circuit includes the following steps: The coincidence circuit receives the first electrical signal amplified by the preamplifier and the second electrical signal amplified by the voltage divider amplifier 6. It then determines the energy and timing relationship between the two signals. When the following conditions are simultaneously met, it identifies an F-18 nuclide decay event and generates a coincidence count (β). + -γ coincidence method): a. The energy deposited in the first detector 3 is less than or equal to the β produced by the decay of F-18. + The maximum energy of a particle; b. The energy deposited in the second detector 5 is 0.511 MeV; c. The preamplifier 4 and the voltage divider amplifier 6 simultaneously generate pulse signals.

[0047] By subtracting the F-18 concentration from the concentration of artificial β-nuclides in the gas, the concentrations of other β-nuclides in the gas can be obtained.

[0048] As an optimization of the above solution, to avoid the problem of reduced filtration efficiency of filter paper 2 due to exceeding preset limits, an automatic replacement step for the detection area of ​​filter paper 2 is also included. When the aerosol sample collected on filter paper 2 at the detection position is detected to exceed the preset limit, the drive motor automatically drives the active roller 21 to rotate, moving the filter paper roll and replacing the measurement area of ​​filter paper 2 at the detection position, thus avoiding the problem of reduced filtration efficiency due to exceeding the preset limit. The preset limit is measured by differential pressure gauges installed at the upper and lower ends of the sampling pipeline of the detection device. Typical values ​​are: upper limit of differential pressure: 35 kPa, lower limit of differential pressure: 3 kPa.

[0049] The above-disclosed embodiments are merely preferred embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An integrated measurement device for radioactive aerosols, characterized in that, include: The housing has a first mounting chamber, a support chamber, and a second mounting chamber arranged sequentially from top to bottom inside. The top of the housing has an air inlet. The inner wall of the housing forms a channel for gas passage between the first mounting chamber and the bottom of the first mounting chamber. The top of the support chamber is connected to the bottom of the first mounting chamber. The side wall of the housing has an air outlet that passes through the support chamber. Filter paper is disposed in a through groove, which is horizontally opened on the housing and located between the first mounting chamber and the support chamber; The first detector is installed in the first mounting chamber and is used to detect alpha and beta rays produced by the decay of radioactive nuclides on the filter paper. The preamplifier has its input terminal electrically connected to the output terminal of the first detector, and its output terminal electrically connected to the input terminal of the multichannel and the input terminal of the coincidence circuit, respectively. The output terminal of the multichannel and the output terminal of the coincidence circuit are respectively electrically connected to the data processing circuit. The second detector, located in the second mounting chamber, is used to detect gamma rays produced by the decay of radioactive nuclides on the filter paper. The voltage divider amplifier has its input terminal electrically connected to the second detector and its output terminal electrically connected to the input terminal of the coincidence circuit.

2. The integrated radioactive aerosol measuring device according to claim 1, characterized in that, The first mounting chamber is mounted and fixed on the inner wall of the housing. The upper side wall of the first mounting chamber is conical and is positioned directly opposite the air inlet. The lower side wall of the first mounting chamber is cylindrical.

3. The integrated radioactive aerosol measuring device according to claim 1, characterized in that, The first detector is a PIPS detector or a plastic scintillator detector, and the second detector is any one of a sodium iodide detector, a lanthanum bromide detector, a high-purity germanium detector, and a zinc cadmium telluride detector.

4. The integrated radioactive aerosol measuring device according to claim 1, characterized in that, The housing is provided with a filter paper replacement mechanism, which includes: The active roll and the driven roll are respectively disposed inside the housing and located on both sides of the support cavity, and the two ends of the filter paper are respectively wound on the active roll and the driven roll; A drive motor, the output shaft of which is connected to the active drum, is used to drive the active drum to rotate; Two tensioning rollers are respectively positioned above the driving drum and the driven drum. The two tensioning rollers contact the lower side of the filter paper to change the direction of movement of the filter paper.

5. A method for measuring radioactive aerosols, implemented using the integrated radioactive aerosol measuring device as described in any one of claims 1 to 4, characterized in that, Includes the following steps: The gas sample to be tested is passed through the measuring device and filtered through filter paper, which enriches the radioactive aerosols in the air on the surface of the filter paper to form an aerosol sample. The first detector is used to detect the α and β rays generated by the decay of the aerosol sample and generate a first electrical signal. The first electrical signal is amplified by a preamplifier and sent to the multichannel and coincidence circuits respectively. The second detector is used to detect the γ rays generated by the decay of the aerosol sample and generate a second electrical signal. The second electrical signal is amplified by a voltage divider amplifier and sent to the coincidence circuit. The first electrical signal is processed by the multi-channel system, and the energy spectrum of the rays is formed by distinguishing them according to energy and then transmitted to the data processing circuit. The data processing circuit, based on the energy spectrum of the generated ray and a preset region of interest, distinguishes the total α count, total β count, and characteristic counts of radon-thorium progeny Po-218, Po-214, and Po-212. Using a radon-thorium progeny compensation algorithm, it determines the artificial radioactive β nuclide count from the total β count combined with the characteristic counts of Po-218, Po-214, and Po-212. It also determines the artificial radioactive α nuclide count from the total α count. Based on the artificial radioactive β nuclide count and measurement parameters, it determines the activity concentration information of the artificial radioactive β nuclide in the gas. Finally, it determines the activity concentration information of the artificial radioactive α nuclide in the gas based on the artificial radioactive α nuclide count and measurement parameters. The measurement parameters include the detector's detection efficiency for the target ray, the measurement period, the filter paper's filtration efficiency, and the sampling volume within the measurement period. The coincidence circuit converts the β generated during the decay of F-18 nuclide + -γ coincidence signal counting determines the F-18 nuclide count and transmits it to the data processing circuit. Based on the F-18 nuclide count and the measurement parameters, the activity concentration of F-18 nuclide in the gas is determined.

6. The method for measuring radioactive aerosols according to claim 5, characterized in that, The activity concentration information of each nuclide is determined by the following formula: in: Nuclide activity concentration; Nuclide counting; The detector's detection efficiency for nuclides; T Measurement cycle; Filter paper filtration efficiency; The sampling volume within the measurement period.

7. The method for measuring radioactive aerosols according to claim 5, characterized in that, The process of counting coincidence signals generated during the decay of F-18 nuclide by the coincidence circuit includes the following steps: The coincidence circuit receives the first electrical signal amplified by the preamplifier and the second electrical signal amplified by the voltage divider amplifier, and determines the energy and timing relationship between the two signals. When the following conditions are met simultaneously, it determines it as an F-18 nuclide decay event and generates a coincidence count: a. The energy deposited in the first detector is less than or equal to the β produced by the decay of F-18. + The maximum energy of a particle; b. The energy deposited in the second detector is 0.511 MeV; c. The preamplifier and the voltage divider amplifier simultaneously generate pulse signals.

8. The method for measuring radioactive aerosols according to claim 5, characterized in that, When the aerosol sample collected on the filter paper at the detection location exceeds the preset limit, the drive motor automatically drives the active drum to rotate, moving the filter paper roll and replacing the filter paper at the detection location.

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