CN116224412A - Laminated composite detector, measuring unit, monitoring device and monitoring method for monitoring total alpha and total beta of aerosol in gaseous effluent - Google Patents

Laminated composite detector, measuring unit, monitoring device and monitoring method for monitoring total alpha and total beta of aerosol in gaseous effluent Download PDF

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CN116224412A
CN116224412A CN202211604123.7A CN202211604123A CN116224412A CN 116224412 A CN116224412 A CN 116224412A CN 202211604123 A CN202211604123 A CN 202211604123A CN 116224412 A CN116224412 A CN 116224412A
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total
beta
signal
alpha
aerosol
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郭贵银
成丰
黄彦君
曾帆
左伟伟
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China General Nuclear Power Corp
CGN Power Co Ltd
Suzhou Nuclear Power Research Institute Co Ltd
Yangjiang Nuclear Power Co Ltd
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China General Nuclear Power Corp
CGN Power Co Ltd
Suzhou Nuclear Power Research Institute Co Ltd
Yangjiang Nuclear Power Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/167—Measuring radioactive content of objects, e.g. contamination
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G01T1/202—Measuring radiation intensity with scintillation detectors the detector being a crystal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G01T1/208—Circuits specially adapted for scintillation detectors, e.g. for the photo-multiplier section
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

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Abstract

The invention relates to a laminated composite detector for monitoring total alpha and total beta of aerosol in gaseous effluent, which sequentially comprises a ZnS scintillator layer for measuring alpha nuclides, a CZT scintillator layer for measuring beta/gamma nuclides, a BGO scintillator for reducing background and SiPM for enhancing signals. According to the laminated composite detector, the total alpha and total beta radioactivity of the aerosol is monitored on line through the detector and a corresponding calculation method, so that the manpower is effectively saved, and the monitoring period is shortened.

Description

Laminated composite detector, measuring unit, monitoring device and monitoring method for monitoring total alpha and total beta of aerosol in gaseous effluent
Technical Field
The invention belongs to the technical field of effluent detection, and particularly relates to a laminated composite detector, a measuring unit, an on-line monitoring device and a monitoring method suitable for monitoring total alpha and total beta nuclides of aerosol in gaseous effluents of a nuclear power plant, a nuclear element plant, a spent fuel plant and the like.
Background
With the utilization of human nuclear facilities and nuclear technology, a large amount of alpha nuclides and beta nuclides are released, and are further discharged into the environment, so that radiation influence is caused on human beings through external irradiation and internal irradiation radiation, and aerosol radioactivity monitoring tends to be normalized.
The total alpha and the total beta in the environment are mainly derived from ground radionuclides 238 U and 232 th decay release 222 Rn and 220 rn and decay subunits thereof. With the development of nuclear power industry in China, nuclear element factories and spent fuel post-treatment factories run to directly and indirectly discharge transuranic into the environment 235 U、 238 U、 239 Pu, etc.) nuclides and artificial radionuclides, resulting in an increase in the total alpha and beta activity concentrations of the natural and artificial radioactivity in the environment.
At present, the common mode at home and abroad is to sample through a filter membrane, send the sample to a laboratory for analysis after the sampling is finished, prepare a liquid or solid sample source through a series of chemical treatments, and measure the sample source by using a liquid flash spectrometer or an alpha counter and a beta counter. The operation is time-consuming and labor-consuming, meanwhile, the activity concentrations of the artificial and natural total alpha and total beta cannot be obtained respectively, and meanwhile, the original method is extremely difficult to realize automatic measurement and analysis and cannot be applied to an effluent online monitoring system.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a laminated composite detector for monitoring total alpha and total beta of aerosol in gaseous effluent and a measuring unit comprising the laminated composite detector.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a stacked composite detector for aerosol total alpha and total beta monitoring in gaseous effluent, comprising in order a ZnS scintillator layer for measuring alpha nuclides, a CZT (cadmium zinc telluride) scintillator layer for measuring beta/gamma nuclides, a BGO (bismuth germanate) scintillator for reducing background, and an SiPM (semiconductor silicon photomultiplier) for signal enhancement.
According to some preferred embodiments of the invention, a laminated composite detector for measuring radioactive rays emitted by aerosols on the surface of filter papers and an electronic signal processing module for acquiring the radioactive signals and calculating the activity concentrations of the total α and the total β of aerosols in gaseous effluents are included in the laminated composite detector according to claim 1.
According to some preferred embodiments of the present invention, the electronic signal processing module includes a signal collector, a pulse amplitude comparator for discriminating alpha/beta species and a pulse width comparator for discriminating beta/gamma species signals. Different types of signals are extracted through a pulse width signal comparator and an amplitude signal comparator, the extracted alpha and beta signals are respectively subjected to coincidence processing, and natural nuclides in the alpha and beta signals are compensated 220 Rn and 222 the Rn daughter and the random interference signal are interfered, and the total alpha and the total beta of the artificial radioactivity are further calculated; the proposed beta and gamma signals are in anti-coincidence treatment, gamma nuclide interference in the beta signals is compensated, and more accurate artificial radioactivity total beta is further calculated; and the gamma signal measured by the CZT scintillator is matched with the gamma signal measured by the BGO, so that the environmental background interference is effectively reduced.
The invention also provides a method for calculating total alpha and total beta of aerosol in gaseous effluent according to the measuring unit, which comprises the following steps: the laminated composite detector receives the radioactive rays emitted by the aerosol, multiplies the radioactive rays by SiPM and outputs the multiplied radioactive rays to the amplitude comparator, and the amplitude comparator is utilizedThe amplitude comparator distinguishes the alpha signal L α The difference of pulse width is obtained by using a pulse width comparator to distinguish beta signal L β And gamma signal, using BGO signal decay time, distinguishing gamma signal L γ And BGO detected gamma signal L B 。
According to some preferred embodiments of the invention, the signal L γ And L is equal to B Anti-coincidence, generation of gamma signal L γk ；L γk AD conversion to count rate n B The signal L β And L is equal to γ Meets the requirement to obtain a pure beta signal L β AD conversion to count rate n β Conforming to the signal and the signal L α Performing two-time delay coincidence to respectively generate radon gas 214 Po accords with signal, thorium gas daughter 212 Po coincidence signal and random coincidence signal are converted into counting rate n by AD Rn 、n Th And n k The signal L α AD conversion to count rate n α 。
Specifically, signal L α 、L β 、L γ And L is equal to B The initial signals are all negative pulse signals, and are converted into positive pulse signals after reverse processing; will L B Signal sum L γ The signals are respectively delayed by 10 mu s and are represented by L γ The falling edge of (2) is the threshold gate, L is found within 10. Mu.s B Delayed signal rejection of signal, recording anti-coincidence signal L γk AD-converted to a count rate n γ (gamma nuclide count rate); positive pulse signal L β Delay of 10 μs, in L β The falling edge of (2) is the threshold gate, L is found within 10. Mu.s γk Delayed signal rejection of signal, recording anti-coincidence signal L γβ AD-converted to a count rate n β (beta nuclide count rate); positive pulse signal L α AD conversion to count rate n α (alpha total nuclide count rate) with a delay of 10 mus, at L α The falling edge of (2) is the threshold gate, L is found within 10. Mu.s γβ The delayed signal of the signal is reserved, and the record coincidence signal is converted into n by AD Th (thorium injection coincidence count rate); the alpha signal L after delay α Delayed by 180 μs again by L α The falling edge of (2) is the threshold gate, found within 180. Mu.sAnticomplement signal L γβ Preserving, recording random coincidence signals L k AD-converted to a count rate n k (random noise count rate); anticomplement signal L γβ Delayed by 180 μs, at L γβ Is the threshold gate, L is found within 180. Mu.s α 180 mus delayed signal retention, recording coincidence signal n Rn (radon emanation meets the count rate).
According to some preferred embodiments of the invention, the natural total activity concentration of radioactivity is calculated according to the following formula:
Figure SMS_1
wherein: a is that α Is the natural total activity concentration of radioactivity; n is n α A total count rate of alpha; n is n Rn The radon gas is in accordance with the counting rate; alpha is a radioactive radon alpha correction factor; n is n Th The counting rate is met for thorium injection; beta is radioactive thorium alpha correction factor epsilon α Is the total alpha detection efficiency; v is the sampling volume.
According to some preferred embodiments of the invention, the natural total activity concentration of radioactivity is calculated according to the following formula:
Figure SMS_2
wherein A is β Is the natural total activity concentration of radioactive beta; n is n β Is beta count rate; alpha' is a radioactive radon beta correction factor; beta' is a radioactive thorium beta correction factor; epsilon β Is the total beta detection efficiency; v is the sampling volume.
The invention also provides on-line monitoring equipment for the total alpha and the total beta of the aerosol in the gaseous effluent, which comprises an acquisition unit, a driving unit and the measuring unit; the collecting unit is used for collecting aerosol in the air; the driving unit is used for driving the filter paper to move so as to realize continuous measurement.
According to some preferred embodiments of the present invention, the collecting unit includes a gas path pipe, a gas collecting port located at one end of the gas path pipe, a mass flowmeter for recording the collection amount of air, and a fan for forming negative pressure in the gas collecting port, where the gas collecting port is located near the filter paper and at one side of the filter paper. The collecting unit deposits aerosol on the surface of filter paper under the action of the air extraction fan, gas is discharged through a mass flowmeter for quantitative measurement, the gas flow is controlled through feedback of the mass flowmeter, meanwhile, the air collecting quantity is accumulated and recorded, and after the air collecting quantity reaches a set sampling volume or the sampling time reaches a set sampling time, the driving unit transfers the collected aerosol sample to the measuring unit.
In some embodiments, the collecting unit comprises two gas collecting ports which are one by one, a three-way valve is arranged on a gas path pipeline, and the on-line monitoring and sampling of the air aerosol are realized by switching the three-way ball valve, and the sampling flow is realized by 0-200 m 3 And/h is adjustable.
The first region of interest (filter paper effective area above the first sampling port) of the filter paper is driven by the power scroll to move to the position above the first gas-collecting port, aerosol is collected, after collection is completed, the first region of interest of the filter paper is driven by the power scroll to the measuring area, the three-way ball valve is switched, aerosol samples are collected through the second region of interest (filter paper effective area above the second sampling port) of the filter paper above the second gas-collecting port, after measurement is completed on the sample of the first region of interest, the first region of interest is driven by the power scroll to the position above the first gas-collecting port, second sampling is started, aerosol on the second region of interest enters the measuring area for measurement, continuous sampling measurement of the aerosol is further realized, and further through periodic repeated collection and measurement on the first region of interest and the second region of interest of the filter paper, the monitoring data reporting frequency is improved, and the monitoring is similar to real-time online monitoring.
According to some preferred embodiments of the invention, the cross-sectional area of the gas-extraction port is 200cm 3 ～500cm 3 Preferably, the area of the gas extraction opening is 400cm 3 The accumulated sampling volume can reach 10000m by matching with filter paper for sampling 3 。
According to some preferred embodiments of the invention, the filter paper for sampling is designed as rectangular roll paper, and the whole length is more than 20 meters, so that the filter paper can be used continuously for a long time (one year).
According to some preferred implementation aspects of the invention, the online monitoring device comprises a two-dimensional code generator for identifying sampling filter paper and storing relevant information in sampling and measuring processes, wherein the relevant information comprises filter paper numbers, nth sampling time, nth sampling volume, nth measuring activity concentration and the like.
According to some preferred embodiments of the present invention, the driving unit includes a first power reel and a second power reel, two ends of the filter paper are respectively wound on the first power reel and the second power reel, and the first power reel and the second power reel are mutually matched to drive the filter paper to move, so as to realize clockwise and anticlockwise rotation of the filter paper, and further realize continuous and cumulative collection of the air aerosol sample. In some embodiments, the drive unit further comprises a meter that is attached to the powered spool.
The invention also provides a method for on-line monitoring the total alpha and total beta of aerosol in gaseous effluent by adopting the monitoring equipment, which comprises the following steps: and depositing the aerosol in the air on the surface of the filter paper under the action of the acquisition unit, measuring the total alpha and total beta activity concentration in the aerosol by using a laminated composite detector in the measurement unit, acquiring signals by using an electronic signal processing module, processing and analyzing, and calculating to obtain the artificial and natural total alpha and total beta activity concentration in the air.
Due to the implementation of the technical scheme, compared with the prior art, the invention has the following advantages: according to the laminated composite detector, the total alpha and total beta radioactivity of the aerosol is monitored on line through the detector and a corresponding calculation method, so that the manpower is effectively saved, and the monitoring period is shortened.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an on-line monitoring device in accordance with a preferred embodiment of the present invention;
FIG. 2 is a schematic diagram of a laminated composite detector in accordance with a preferred embodiment of the present invention;
FIG. 3 is a schematic diagram of the method for monitoring coincidence and anti-coincidence in a preferred embodiment of the present invention;
in the accompanying drawings: 111. the device comprises a first gas extraction port, 112, a second gas extraction port, 12, an electric three-way valve, 13, a gas extraction fan, 14, a mass flowmeter, 211, a first power reel, 212, a second power reel, 221, a first meter, 222, a second meter, 23, filter paper, 24, a two-dimensional code generator, 3, a laminated composite detector, 31, znS scintillators, 32, CZT scintillators, 33, BGO scintillators, 34 and SiPM.
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
Example 1 on-line monitoring device
As shown in fig. 1 and 2, the online monitoring apparatus for aerosol radioactivity in the effluent in the present embodiment includes an acquisition unit, a driving unit, first and second measurement units, and a two-dimensional code generator 24. Wherein the collecting unit is used for quantitatively/regularly collecting aerosol in the air; the driving unit is used for driving the filter paper 23 to move; the measuring unit comprises a laminated composite detector 4 and an electronic signal processing module, wherein the laminated composite detector 4 is used for measuring radioactive rays emitted by aerosol on the surface of the filter paper 23, and the electronic signal processing module is used for acquiring the radioactive signals and calculating the activity concentration of total alpha and total beta in the aerosol by combining the deposition efficiency of the aerosol.
The specific structure of each unit is described in detail below:
the acquisition unit comprises a gas path pipeline, a first gas extraction port 111 (or a second gas extraction port 112), an electric three-way ball valve 12, a gas extraction fan 13 and a mass flowmeter 14, wherein the first gas extraction port 111 (or the second gas extraction port 112) is sequentially arranged on the gas path pipeline and used for aerosol acquisition. The acquisition unit comprises two gas extraction ports which are one by one, and is switched through the three-way valve 12 to realize the on-line monitoring and sampling of the aerosol, and the sampling flow is 0-200 m 3 And/h is adjustable. The collecting unit deposits aerosol on the surface of the filter paper 23 under the action of the air extraction fan 13, the air is discharged through the mass flowmeter 14 for quantitative measurement, the air flow is controlled through the feedback of the mass flowmeter 14, meanwhile, the mass flowmeter 14 accumulates and records the air collecting quantity, and after the air collecting quantity reaches the set sampling volume or the sampling time reaches the set sampling time, the driving unit transfers the collected aerosol sample to the measuring unit. The area of the gas extraction opening in this embodiment is 400cm 3 The accumulated sampling volume can reach 10000m by matching with the filter paper 23 for sampling 3 。
The driving unit comprises a first power scroll 211 and a second power scroll 212, two ends of the filter paper 23 are respectively wound on the first power scroll 211 and the second power scroll 212, and the first power scroll 211 and the second power scroll 212 are mutually matched to drive the filter paper 23 to move so as to realize clockwise and anticlockwise rotation of the filter paper 23, further realize continuous and accumulated collection of air aerosol samples and realize replacement of aerosol samples. In this embodiment, the driving unit further includes a meter attached to the power reel (first meter 221, second meter 222), and the filter paper 23 is moved under the driving of the power reel, and the movement distance is recorded by the meter and fed back to the power reel, so as to realize the positioning movement of the filter paper 23.
The filter paper 23 for sampling in this embodiment is a rectangular roll paper, and the overall length is over 20 meters, so that the continuous operation for a long time (one year) is satisfied. The first region of interest of the filter paper 23 is driven by the first power scroll 211 to move downwards to the position above the first gas-collecting port 111 to collect aerosol, after the collection is completed, the first region of interest of the filter paper 23 is driven by the second power scroll 212 to the measuring region, the three-way ball valve 12 is switched, aerosol samples are collected through the second region of interest of the filter paper 23 above the second gas-collecting port 112, meanwhile, after the measurement is completed on the samples of the first region of interest, the first power scroll 211 drives the first region of interest to the position above the first gas-collecting port 111 to start the second sampling, and meanwhile, the aerosol on the second region of interest enters the measuring region to be measured, so that continuous sampling measurement of the aerosol is further realized, and the report frequency of monitoring data is improved by periodically repeating the collection and measurement on the first region of interest and the second region of interest of the filter paper 23, which is similar to real-time online monitoring.
The two-dimensional code generator 24 is used for identifying the sampling filter paper 23 and storing relevant information in the sampling and measuring processes, including the number of the filter paper 23, the nth sampling time, the nth sampling volume, the nth measuring activity concentration and the like, and when the two-dimensional code generator is used, a matched two-dimensional code scanner (or a mobile phone and other terminals) can be adopted to read the two-dimensional code generated on the filter paper 23 so as to load all information of the filter paper 23 stored by an upper computer.
The laminated composite detector of the measuring unit is arranged above the filter paper 23 and is used for measuring total alpha, total beta and gamma nuclides of aerosol, and is matched with the acquisition and the rear-end processing of the high-speed signal acquisition device to effectively compensate the interference of natural nuclides, and the high-precision manual and natural radioactive total alpha and total beta activity concentration is further calculated. Specifically, the laminated composite detector 4 includes, in order, a ZnS scintillator layer for α -nuclide measurement, a CZT scintillator layer for β/γ -nuclide measurement, a BGO scintillator for background reduction, and SiPM for signal enhancement. The effective detection area of the laminated composite detector 4 is 200cm 2 ～400cm 2 。
The electronic signal processing module of the second measuring unit comprises a signal collector, a pulse amplitude comparator for alpha/beta nuclide distinction and a pulse width comparator for beta/gamma nuclide signal distinction. Different types of signals are extracted through the signal pulse width signal comparator and the amplitude signal comparator, the extracted alpha and beta signals are respectively subjected to coincidence processing, and natural nuclides in the alpha and beta signals are compensated 220 Rn and 222 rn daughter and random interference signal interference, furtherStep one, calculating to obtain artificial radioactivity total alpha and total beta; the proposed beta and gamma signals are in anti-coincidence treatment, gamma nuclide interference in the beta signals is compensated, and more accurate artificial radioactivity total beta is further calculated; and the gamma signal measured by CZT is matched with the gamma signal measured by BGO, so that the environmental background interference is effectively reduced, and the gamma nuclide detection limit is further reduced.
The output end of the measuring unit in the embodiment is connected with the industrial personal computer as an upper computer, and is used for whole program control, and the upper computer also completes functions of final calculation, storage and the like.
Example 2 monitoring method
As shown in fig. 1-3, the present embodiment provides a method for monitoring total α and total β of aerosol radioactivity in air based on the monitoring apparatus in embodiment 1, and in combination with the monitoring apparatus in embodiment 1, the monitoring method includes the following steps:
the sampling unit is started, aerosol in the air enters the device and is deposited on the surface of the filter paper 23, gas enters the first gas extraction port 111 (or the second gas extraction port 112) and enters the air extraction fan 13 through the electric three-way ball valve 12, and the gas is discharged to the environment through the gas mass flowmeter 14 after the gas exits from the gas outlet.
The aerosol sample is further transferred to a second measuring unit, namely the lower end of a laminated composite detector 4, the laminated composite detector receives the radioactive rays emitted by the aerosol, the radioactive rays are multiplied by SiPM and then output to an amplitude comparator, and an alpha signal L is resolved by the amplitude comparator α By utilizing the difference of pulse width, the beta signal L is resolved β And gamma signal, distinguishing gamma signal L detected by CZT by utilizing signal attenuation time of BGO γ And BGO detected gamma signal L B 。
Signal L α 、L β 、L γ And L is equal to B The initial signals are all negative pulse signals, and are converted into positive pulse signals after reverse processing; will L B Signal sum L γ The signals are respectively delayed by 10 mu s and are represented by L γ The falling edge of (2) is the threshold gate, L is found within 10. Mu.s B Delayed signal rejection of signal, recording anti-coincidence signal L γk AD-converted to a count rate n γ (gamma nuclide count rate); positive pulse signal L β Delay of 10 μs, in L β The falling edge of (2) is the threshold gate, L is found within 10. Mu.s γk Delayed signal rejection of signal, recording anti-coincidence signal L γβ AD-converted to a count rate n β (beta nuclide count rate); positive pulse signal L α AD conversion to count rate n α (alpha total nuclide count rate) with a delay of 10 mus, at L α The falling edge of (2) is the threshold gate, L is found within 10. Mu.s γβ The delayed signal of the signal is reserved, and the record coincidence signal is converted into n by AD Th (thorium injection coincidence count rate); the alpha signal L after delay α Delayed by 180 μs again by L α Is the threshold gate, and an anti-coincidence signal L is found within 180 mu s γβ Preserving, recording random coincidence signals L k AD-converted to a count rate n k (random noise count rate); anticomplement signal L γβ Delayed by 180 μs, at L γβ Is the threshold gate, L is found within 180. Mu.s α 180 mus delayed signal retention, recording coincidence signal n Rn (radon emanation meets the count rate).
The natural total alpha activity concentration is calculated through a formula (1), the natural total beta activity concentration is calculated through a formula (2), the artificial radioactivity total alpha activity concentration in the aerosol is calculated through a formula (3), and the total beta activity concentration is calculated through a formula (4).
Figure SMS_3
Wherein: a is that α Is the natural total activity concentration of radioactivity; n is n α A total count rate of alpha; n is n Rn The radon gas is in accordance with the counting rate; alpha is a radioactive radon alpha correction factor; n is n Th The counting rate is met for thorium injection; beta is radioactive thorium alpha correction factor epsilon α Is the total alpha detection efficiency; v is the sampling volume.
Figure SMS_4
Wherein A is β Is concentrated in natural radioactivity total beta activityA degree; n is n β Is beta count rate; alpha' is a radioactive radon beta correction factor; beta' is a radioactive thorium beta correction factor; epsilon β Is the total beta detection efficiency; v is the sampling volume.
Figure SMS_5
Wherein: a is that αm : artificial radioactivity total alpha activity concentration; n is n α : alpha total nuclide count rate; n is n Rn : radon emanation meets the counting rate; alpha: a radioactive radon alpha correction factor; n is n Th : thorium injection accords with the counting rate; beta: a radioactive thorium alpha correction factor; n is n k : random noise count rate; k: an alpha random noise correction factor; b (B) α : alpha background count rate; epsilon α : total alpha detection efficiency; v: sampling volume.
Figure SMS_6
Wherein: a is that βm : artificial radioactivity total beta activity concentration; n is n β : beta nuclide count rate; alpha': a radioactive radon beta correction factor; n is n Rn : radon emanation meets the counting rate; beta': a radioactive thorium beta correction factor; n is n Th : thorium injection accords with the counting rate; k': a beta random noise correction factor; n is n k : random noise count rate; f (F) α : a channel factor; n is n α : alpha total count rate; b (B) β : beta background count rate; epsilon β : total beta detection efficiency; v: sampling volume.
The air aerosol online monitoring equipment can realize continuous sampling monitoring of aerosol, realizes accurate measurement of aerosol deposition efficiency through the photometric measurement unit, effectively improves measurement accuracy, adopts a laminated composite detector for measurement, is provided with a high-speed signal collector, eliminates interference of natural nuclides in the measurement process by combining a calculation method of the aerosol deposition efficiency, and measures total alpha and total beta activity concentrations of artificial and natural radioactivity with high accuracy. The on-line monitoring equipment for aerosol in air is characterized in that the air is driven by an air suction fan to be 0-200 m 3 The method comprises the steps that/h flow rate enters equipment, aerosol is deposited on the surface of filter paper, gas is discharged through a gas-collecting port, a gas-extracting fan and a mass flowmeter, the filter paper is driven to a first measuring unit through a power scroll, a beam emitter emits beams with the same intensity at two positions, two photometric detectors receive measurement, aerosol deposition efficiency is calculated, the aerosol deposition efficiency is more than 95%, the aerosol is further moved to the lower end of a second measuring unit, a laminated composite detector measures radioactivity of the aerosol, a high-speed signal collector collects measurement signals, and total alpha and total beta activity concentrations of artificial and natural radioactivity in the aerosol are calculated through coincidence and anti-coincidence measuring means. The monitoring equipment provided by the invention has the advantages of reasonable structural design and high detection accuracy, can realize one-key operation through the cooperation control of a system program, is unattended, stable and reliable, and is suitable for online monitoring of total alpha and total beta of aerosol in air.
The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the present invention and to implement the same, but are not intended to limit the scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of the present invention.

Claims (10)

1. A laminated composite detector for monitoring total alpha and total beta of aerosols in gaseous effluents, characterized by: the laminated composite detector comprises a ZnS scintillator layer for measuring alpha nuclides, a CZT scintillator layer for measuring beta/gamma nuclides, a BGO scintillator for reducing background and SiPM for enhancing signals in sequence.
2. A measurement unit, characterized in that: comprising a laminated composite detector for measuring radioactive rays emitted by an aerosol on a surface of a filter paper as defined in claim 1, and an electronic signal processing module for acquiring the radioactive signals and calculating the total alpha and beta activity concentrations of the aerosol in the gaseous effluent of a nuclear power plant.
3. The measurement unit according to claim 2, characterized in that: the electronic signal processing module comprises a signal collector, a pulse amplitude comparator for distinguishing alpha/beta nuclides and a pulse width comparator for distinguishing beta/gamma nuclide signals.
4. A method according to claim 2 or 3 for calculating the total α and total β of aerosols in gaseous effluents by means of a measuring unit, comprising the steps of: the laminated composite detector receives the radioactive rays emitted by the aerosol, multiplies the radioactive rays by SiPM and outputs the multiplied radioactive rays to the amplitude comparator, and the alpha signal L is resolved by the amplitude comparator α The difference of pulse width is obtained by using a pulse width comparator to distinguish beta signal L β Distinguishing gamma signals L detected by a CZT scintillator by utilizing signal decay time of BGO γ And BGO detected gamma signal L B 。
5. The computing method according to claim 4, wherein: the signal L γ And L is equal to B Anti-coincidence, generation of gamma signal L γk ；L γk AD conversion to count rate n B The signal L β And L is equal to γ Meets the requirement to obtain a pure beta signal L β AD conversion to count rate n β Conforming to the signal and the signal L α Performing two-time delay coincidence to respectively generate radon gas 214 Po accords with signal, thorium gas daughter 212 Po coincidence signal and random coincidence signal are converted into counting rate n by AD Rn 、n Th And n k The signal L α AD conversion to count rate n α 。
6. The computing method according to claim 5, wherein: the total natural radioactivity concentration of α is calculated according to the following formula:
Figure FDA0003996695990000011
wherein: a is that α Is the natural total activity concentration of radioactivity; n is n Rn The radon gas is in accordance with the counting rate; alpha is a radioactive radon alpha correction factor; n is n Th The counting rate is met for thorium injection; beta is a radioactive thorium alpha correction factor; epsilon α Is the total alpha detection efficiency; v is the sampling volume.
7. The computing method according to claim 5, wherein: the activity concentration of the natural radioactive total beta nuclide is calculated according to the following formula:
Figure FDA0003996695990000021
wherein A is β Is the natural total activity concentration of radioactive beta; n is n β Is beta count rate; alpha' is a radioactive radon beta correction factor; beta' is a radioactive thorium beta correction factor; epsilon β Is the total beta detection efficiency; v is the sampling volume.
8. An on-line monitoring device for total alpha and total beta of aerosols in gaseous effluents, characterized in that: comprising an acquisition unit, a drive unit and a measurement unit as claimed in claim 2 or 3; the collecting unit is used for collecting aerosol in the air; the driving unit is used for driving the filter paper to move so as to realize continuous measurement.
9. The monitoring device of claim 8, wherein: the collection unit comprises a gas circuit pipeline, a gas-collecting port located at one end of the gas circuit pipeline, a mass flowmeter for recording air collection quantity and a fan for forming negative pressure in the gas-collecting port, wherein the gas-collecting port is close to the filter paper and located at one side of the filter paper.
10. A method of on-line monitoring of total α and total β aerosols in a gaseous effluent using the monitoring device of claim 8 or 9, comprising the steps of: and depositing the aerosol in the air on the surface of filter paper under the action of an acquisition unit, measuring the total alpha and total beta radioactivity in the aerosol by using a laminated composite detector in a measurement unit, acquiring signals by using an electronic signal processing module, processing and analyzing, and calculating to obtain the artificial and natural total alpha and total beta activity concentration in the gaseous effluent.
CN202211604123.7A 2022-12-13 2022-12-13 Laminated composite detector, measuring unit, monitoring device and monitoring method for monitoring total alpha and total beta of aerosol in gaseous effluent Pending CN116224412A (en)

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