CN117687068A - Online monitoring device and online monitoring method for aerosol radioactivity in surrounding environment of nuclear facility - Google Patents

Abstract

The invention relates to an online monitoring device for aerosol radioactivity in the environment around a nuclear facility, which is characterized in that it includes a sampling system, a paper control system, a detection system, a data processing system and a control system; the sampling system is used to collect data from the air Aerosol sample; the paper control system is used to control the transmission of the filter paper; the detection system is used to detect radioactive rays emitted by the aerosol deposited on the surface of the filter paper; the data processing system is used to obtain radioactive signals and measure and calculate the aerosol sample The activity concentration of total α and total β nuclides in . The aerosol continuous monitoring device in the environment around a nuclear facility of the present invention performs continuous sampling, continuous measurement, and online analysis of aerosols. It uses a composite detector to detect total α, total β, and γ nuclides, and compensates the measurement through a coincidence algorithm. The interference of natural nuclides during the process enables real-time, high-precision measurement of the activity concentration of artificial radioactive total α and total β nuclides.

Description

Online monitoring device and online monitoring of aerosol radioactivity in the environment around nuclear facilities method

Technical field

The invention belongs to the technical field of environmental monitoring, and specifically relates to an online monitoring device for aerosol radioactivity in the environment around a nuclear facility and an online monitoring method for aerosol radioactivity based on the online monitoring device.

Background technique

With the widespread use of nuclear energy and nuclear technology, a large amount of artificial radioactive aerosols generated during the production and decommissioning of nuclear facilities will pose a potential threat to the social and ecological environment.

The total α, total β and γ nuclides in the environment mainly come from ²²² Rn and ²²⁰ Rn and their decay products released by the decay of ground radionuclides ²³⁸ U and ²³² Th, while the α nuclides, β nuclides produced by the decay of artificial radionuclides Nuclides and γ nuclides are the objects of our concern. Their activity concentrations are usually very low, and the interference of natural nuclides needs to be subtracted during monitoring.

At present, the sampling flow rate of domestic and foreign aerosol total beta nuclide continuous monitoring equipment does not exceed 25m ³ /h, and the 2-hour measurement detection limit is only 10mBq/m ³ level. In addition, the detectors that have been used are generally composite detectors of plastic scintillator + ZnS (Ag) or directly use PIPS detection. Both types of detectors are unable to achieve consistent discrimination of ²¹² Po and ²¹² Bi, making it impossible to further Lowering the detection limit is not suitable for monitoring aerosol total beta nuclides in the environment around nuclear power plants.

Contents of the invention

The present invention aims to provide a fully automated, real-time and high-precision online radioactive aerosol monitoring device. Through a pair of composite detectors, ²¹² Bi/ ²¹² Po and ²¹⁴ Bi/ ²¹⁴ Po can be individually screened to further compensate for natural radon radiation. It is used to monitor the changing trend of radioactive substances in the atmospheric environment in real time due to the interference of gas and thoron gas. The total beta detection limit is as low as 1Bq/m ³ , meeting the monitoring requirements of aerosol total beta in the environment around nuclear power plants.

In order to achieve the above objects, the technical solutions adopted by the present invention are:

An online monitoring device for aerosol radioactivity in the environment around a nuclear facility, including a sampling system, a paper control system, a detection system, a data processing system and a control system; the sampling system is used to collect aerosol samples from the air; the paper The control system is used to control the transmission of the filter paper; the detection system is used to detect radioactive rays emitted by the aerosol deposited on the surface of the filter paper; the data processing system is used to obtain radioactive signals and measure and calculate the total α and total β in the aerosol sample. The activity concentration of the nuclide.

According to some preferred implementation aspects of the present invention, the sampling system includes:

Filter paper, the filter paper is used to deposit aerosol particles in the air to form an aerosol sample;

Gas channel, the gas channel includes a sampling port, an exhaust port and a gas pipeline;

Sampling motor, the sampling motor is used to drive air from the sampling port into the gas channel to form a negative pressure in the sampling port and discharge it from the exhaust port.

According to some preferred implementation aspects of the present invention, the sampling system includes:

A pressure sensor, the pressure sensor is located on the gas pipeline and is used to monitor the pressure difference in the gas pipeline;

A mass flow meter is located on the gas pipeline and is used to record the air collection volume.

According to some preferred implementation aspects of the present invention, the paper control system includes:

A transfer module including a first end and a second end, the transfer module being capable of transferring the filter paper from the first end to the second end;

Stepper motor, the stepper motor is used to control the operation of the transmission module.

According to some preferred implementation aspects of the present invention, the first end of the transfer module includes a first transfer roller, a paper feed roller, a first stretch reel and a second stretch reel, and the second end of the transfer module includes a second Transport roller, third stretch reel, fourth stretch reel and take-up reel.

According to some preferred implementation aspects of the present invention, the filter paper is transported to the first stretching reel and the second stretching reel via the paper supply wheel, and then is transported to the sampling port via the first transport roller, and then It is transported to the third stretching reel and the fourth stretching reel via the second conveying roller, and finally reaches the delivery wheel and is recovered.

According to some preferred implementation aspects of the present invention, the detection system includes:

Composite detector, the composite detector includes LaBr ₃ scintillator, ZnS (Ag) coating and BC-408 scintillator; the LaBr ₃ scintillator is used to detect gamma nuclides; the BC-408 scintillator is used Used to detect total β and total γ nuclides; the ZnS (Ag) coating is used to detect total α nuclides;

Photomultiplier tube, the photomultiplier tube is used for signal enhancement.

According to some preferred implementation aspects of the present invention, the LaBr ₃ scintillator and the ZnS (Ag) coating are located above the filter paper, and the BC-480 scintillator is located below the filter paper; the ZnS (Ag) coating is On the side of the LaBr ₃ scintillator close to the filter paper; there are two photomultiplier tubes, one is located above the LaBr ₃ scintillator, and the other is located below the BC-480 scintillator.

According to some preferred implementation aspects of the present invention, the detection system includes a shielding body disposed on the outermost side, the shielding body includes an upper shielding body and a lower shielding body, and the filter paper is passed between the upper shielding body and the lower shielding body. Then, the LaBr ₃ scintillator, ZnS (Ag) coating and one of the photomultiplier tubes are contained in the upper shielding body, and the BC-480 scintillator and the other photomultiplier tube are contained in the lower shielding body.

According to some preferred implementation aspects of the present invention, the data processing system includes:

Data acquisition module, the data acquisition module includes a signal collector, a signal converter, and a logic electronics circuit;

Data processing module, the data processing module includes a program software module and an automatic alarm module;

The data processing system mainly completes the logical functions of sampling, measurement, data processing, and control alarms to ensure the automatic and continuous normal operation of the online system.

According to some preferred implementation aspects of the present invention, the data processing module processes and calculates the signal output by the detection system to obtain the artificial total α and total β nuclide activities. When the monitoring result exceeds the preset alarm threshold, trigger Automatic alarm module to alarm.

The invention also provides an online monitoring method for aerosol radioactivity in the environment around a nuclear facility using the above-mentioned online monitoring device, which includes the following steps:

The control system generates a sampling signal based on the trigger signal. The sampling system starts in response to the sampling signal and deposits aerosols in the air on the surface of the filter paper;

The control system generates a transmission signal based on the sampling feedback signal. The paper control system responds to the transmission signal and transmits the sampling area of the sampling filter paper to the detection area of the detection system for detection;

The control system generates a detection start signal based on the transmission feedback signal output by the paper control system. The detection system detects the sampling area of the sampling filter paper after starting in response to the detection start signal;

The data processing system amplifies, shapes, and converts the detection information output by the detection system and then outputs a standard pulse signal. After counting and processing the standard pulse signal, the artificial total α and total β nuclide activities in the air are obtained.

According to some preferred implementation aspects of the present invention, before carrying out detection, a calibration source filter paper is made using sampling filter paper containing known α, β and γ nuclide activities (the shape, size, etc. are consistent with the size of the filter paper to be measured), and placed separately Start measurement in the detection area. When the measurement count rate reaches 10,000, stop measurement and counting. Based on the measurement count and the activity of α, β and γ nuclides in the known calibration source, the total α detection efficiency ε _α and the total β detection efficiency are calculated respectively. Efficiency ε _β and γ nuclide detection efficiency ε _γ .

According to some preferred implementation aspects of the present invention, the composite detector receives radioactive rays emitted by aerosols, the ZnS (Ag) coating receives alpha rays, the LaBr ₃ scintillator receives gamma rays, and the BC-480 scintillator Receive β rays and γ rays, and after being multiplied by the photomultiplier tube and output, the α signal S _α detected by ZnS (Ag), the γ signal S _γ-L detected by the LaBr ₃ scintillator, and the BC-480 scintillator detection are obtained. β signal and γ signal S _β&γ .

According to some preferred implementation aspects of the present invention, the LaBr ₃ scintillator is used as the main detector, and the BC-480 scintillator is an anti-coherence detector, and the signals S _γ-L and S _β&γ are anti-coherent to generate γ signals S _γ , S _γ are converted into count rates n _γ' by AD; using the BC-480 scintillator as the main detector and the LaBr ₃ scintillator as the anti-coincidence detector, the signal S _γ-L Perform anti-coherence with S _{β & γ} to generate β signal S _β , S _β is converted into a count rate n _β by AD; the α signal S _α is converted into a count rate n _α by AD;

According to some preferred implementation aspects of the present invention, the γ signal S _γ and the α signal S _α are screened by signal waveforms and energy amplitudes to generate the screened γ signal S _γ' and α signal S _α' respectively, which are The γ signal S _γ' and the α signal S _α' are subjected to two delayed coincidences, respectively generating a radon gas daughter ²¹⁴ Po coincidence signal, a random coincidence signal and a thoron gas daughter ²¹² Po coincidence signal, which are converted into counts by AD. The rates are n _Rn' , n _k and n _Th' ; the radon gas progeny ²¹⁴ Po coincidence signal and the random coincidence signal are counter-cohered to generate the radon gas progeny ²¹⁴ Po signal minus the random coincidence, which is converted into a counting rate by AD. n _Rn ; the thoronium gas daughter ²¹² Po coincidence signal and the random coincidence signal are counter-cohered to generate a thoronium gas daughter ²¹² Po signal minus the random coincidence, which is converted into a count rate n _Rn by AD.

The n _α , n _Rn and n _Th are processed and calculated to obtain the artificial radioactive total α activity concentration A(α); the n _Rn , n _Th and n _β are processed and calculated to obtain the artificial radioactive total β activity. Concentration A(β). Specifically, the total α activity concentration of artificial radioactivity is calculated by the following formula:

In the formula: A(α) is the total α activity concentration of artificial radioactivity; n _α is the total α count rate; n _Rn is the radon gas daughter ²¹⁴ Po count rate; n _Th is the thoron gas daughter ²¹² Po count rate; a' is the radioactive radon α correction factor; b' is the radioactive thorium α correction factor; n _k is the random noise count rate; ε _α is the total α detection efficiency; ε _β is the total β detection efficiency; ε _γ is the total γ detection efficiency; V is the sampling volume.

The total beta activity concentration of artificial radioactivity is calculated by the following formula:

In the formula: A(β) is the total β activity concentration of artificial radioactivity; n _β is the total β count rate; n _Rn is the radon gas daughter ²¹⁴ Po count rate; n _Th is the thoron gas daughter ²¹² Po count rate; a is the radioactive radon β correction factor; b is the radioactive thorium β correction factor; n _k is the random noise count rate; ε _α is the total α detection efficiency; ε _β is the total β detection efficiency; ε _γ is the total γ detection efficiency; V is Sampling volume.

Due to the implementation of the above technical solutions, the present invention has the following advantages compared with the prior art:

1. The detection system of the present invention adopts a composite detector and uses ²¹² Bi and plastic scintillator to perform α/γ coincidence, which can effectively quantify the activity of ²¹² Po and effectively reduce the interference of Th emission to the background;

2. The data processing system of the present invention first uses the difference in signal waveforms and the discrimination of energy amplitude to distinguish the α and γ signals, and then uses the coincidence algorithm to perform multiple coincidence and anti-coherence calculations on the α, β and γ signals, and at the same time Two coincidence calculations are performed for ²¹⁴ Po and ²¹² Po respectively, which increases the detection efficiency and effectively reduces the influence of natural background.

Description of the drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of a continuous monitoring device in a preferred embodiment of the present invention;

Figure 2 is a schematic diagram of the principle of coincidence calculation in the continuous monitoring method in the preferred embodiment of the present invention;

In the drawing: 11. Filter paper, 12. Gas collection port, 131. First pressure sensor, 14. Exhaust fan, 15. Mass flow meter, 132. Second pressure sensor, 16, exhaust port; 211. First transmission Roller, 212, second conveying roller, 221, first stretching reel, 222, second stretching reel, 223, third stretching reel, 224, fourth stretching reel, 231, paper supply wheel, 232, take-up reel Paper wheel; 311. ZnS (Ag) coating; 312. LaBr ₃ scintillator, 313. BC-408 scintillator, 321. First photomultiplier tube, 322. Second photomultiplier tube, 331. First shielding body, 332 , the second shielding body.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described implementation The examples are only part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the scope of protection of the present invention.

Example 1 Online monitoring device for aerosol radioactivity in the environment around nuclear facilities

As shown in Figures 1 and 2, the online monitoring device for aerosol radioactivity in the environment around the nuclear facility in this embodiment includes a sampling system, a paper control system, a detection system, a data processing system and a control system. Among them, the sampling system is used to collect aerosol samples from the air; the paper control system is used to control the transmission of filter paper; the detection system is used to detect radioactive rays emitted by the aerosol deposited on the surface of the filter paper; the data processing system is used to obtain radioactive signals and measure and calculate the activity concentration of total α and total β nuclides in the aerosol; the control system is used to control each system to perform actions.

The following details the specific structure of each system:

The sampling system includes filter paper 11, a gas pipeline and an aerosol sampling port 12 located on the gas pipeline in sequence, a first pressure sensor 131, an exhaust fan 14, a mass flow meter 15, a second pressure sensor 132, and an exhaust port 16 and alarm. The sampling system drives the air through the exhaust fan 14, and the aerosols in the air are deposited on the surface of the filter paper 11 under the action of the exhaust fan 14, and the gas is discharged through the exhaust port 16; the first pressure sensor 131 in the gas pipeline is used to record the gas. The second pressure sensor 132 is used to record the pressure difference at the outlet of the gas pipeline, and the mass flow meter 15 is used to feedback control the gas collection flow and record the air collection volume. When the sampling flow rate does not meet the program setting, the alarm will be triggered. When the air sampling volume reaches the set sampling volume or the sampling time reaches the set sampling time, the paper control system will transfer the collected aerosol sample filter paper to the detection system. Perform testing.

The paper control system includes a transport roller 21 , a stretching roller 22 , a paper supply roller 231 and a delivery roller 232 . Both ends of the filter paper 11 are respectively wound on the paper supply wheel 231 and the paper delivery wheel 232. The first stretching reel 221 and the third stretching reel 223 transport the filter paper 11 from the paper supply wheel 231 to the first conveying roller 211. The filter paper belt between the first transfer roller 211 and the second transfer roller 212 is kept in a horizontal state for collecting aerosol samples. The second transfer roller 212 transfers the collected and measured aerosol samples to the second stretching reel 222 and The fourth stretching reel 224 is then sent to the take-up wheel 232 to save the filter paper 11 from which the sample has been collected, thereby realizing the continuous and cumulative collection of aerosol samples in the air as well as the collection of aerosol samples and subsequent replacement of the filter paper 11 .

The detection system includes composite detectors, photomultiplier tubes and shields. The composite detector includes ZnS (Ag) coating 311, LaBr ₃ scintillator 312 and BC-408 scintillator 313, which is used to measure the total α, total β and γ nuclides of the aerosol; the photomultiplier tube includes the first photomultiplier tube 321 and The second photomultiplier tube 322 is used for signal enhancement; the shielding body includes a first shielding body 331 and a second shielding body 332, used for reducing the background; the ZnS (Ag) coating 311 and the LaBr ₃ scintillator 312 are located above the filter paper 11, The BC-480 scintillator 313 is located below the filter paper 11; the ZnS (Ag) coating 311 is located on the LaBr ₃ scintillator 312 on the side close to the filter paper 11; the first photomultiplier tube 321 is located above the LaBr ₃ scintillator 312, and the second photomultiplier tube 322 Located below the BC-480 scintillator 313; the first shielding body 331 is located above the filter paper 11, and the second shielding body 332 is located below the filter paper 11. The combination of the first shielding body 331 and the second shielding body 332 is used to reduce the environmental background and reduce the environmental impact. The influence of background on artificial aerosol radioactivity detection, the shielding body is a lead layer with a thickness of 5cm. The detection system outputs the detected signal to the data processing system.

The data processing system amplifies, shapes, and converts the detection information output by the detection system and then outputs a standard pulse signal. After counting and processing the standard pulse signal, the artificial total α and total β nuclide activities in the air are obtained.

In this embodiment, an industrial computer is used as the host computer to realize the functions of the control system and is used to control the entire program, including sampling system, paper control system and detection system control. At the same time, the control system also completes final calculation, storage and other functions.

Example 2 Online monitoring method for aerosol radioactivity in the environment around nuclear facilities

As shown in Figure 1-2, this embodiment provides a method for continuous monitoring of aerosol artificial radioactive total α and total β nuclides in the environment around a nuclear facility based on the continuous monitoring device in Example 1, combined with the method in Example 1 Continuous monitoring device, the continuous monitoring method of this embodiment includes the following steps:

Step 1), sampling

The control system generates a sampling signal according to the trigger signal, and the sampling system starts in response to the sampling signal and deposits aerosols in the air on the surface of the filter paper 11 .

Step 2), transmission

The control system generates a transmission signal according to the sampling feedback signal, and the paper control system responds to the transmission signal and transmits the sampling area of the sampling filter paper 11 to the detection area of the detection system.

Step 3), efficiency scale and detection

The control system generates a detection start signal according to the transmission feedback signal output by the paper control system. The detection system starts in response to the detection start signal and detects the sampling area of the sampling filter paper 11 to obtain the detection signal.

Before starting the detection, use sampling filter paper containing known α, β and γ nuclide activities (the shape, size, etc. are consistent with the size of the filter paper to be measured) to make calibration source filter paper, place them in the detection area, start measurement, and measure and count. When the rate reaches 10,000, stop measuring and counting, and calculate the total α detection efficiency ε _α , the total β detection efficiency ε β and the γ nuclide detection efficiency respectively according to the measurement count and the activity of α, _β and γ nuclide in the known calibration source. ε _γ .

Step 4), calculation

The data processing system amplifies, shapes, and converts the detection information output by the detection system and then outputs a standard pulse signal. After counting and processing the standard pulse signal, the artificial total α and total β nuclide activities in the air are obtained.

During detection and calculation, the signal is processed as follows: the composite detector receives the radioactive rays emitted by the aerosol, the ZnS (Ag) coating 311 receives α rays, the LaBr ₃ scintillator 312 receives γ rays, and the BC-480 scintillator 313 receives β rays. and γ rays, which are multiplied by the photomultiplier tube 32 and then output to obtain the α signal S _α detected by ZnS (Ag) 311, the γ signal S _γ-L detected by the LaBr ₃ scintillator 312, and the BC-480 scintillator 313. The β signal and γ signal S _β&γ .

The initial signals of the signals S _α , S _γ-L and S _β&γ are all negative pulse signals, which are converted into positive pulse signals after reverse processing; the S _γ-L signal and the S _β&γ signal are delayed by 10 μs respectively, and the S _γ-L signal is The falling edge is the threshold. If the delayed signal of S _{β & γ} signal is found within 10 μs, the delayed signal is excluded, and the anti-coincidence signal S _γ is recorded. S _γ is converted into a count rate n _γ' (γ nuclide count rate) by AD; convert S _γ-L The signal and the S _β&γ signal are delayed by 10 μs respectively. The falling edge of S _β&γ is used as the threshold. If the delayed signal of the S _γ-L signal is found within 10 μs, the delayed signal of the S γ-L signal is excluded. The anti-coincidence signal S _β is recorded. S _β is converted into a count rate n by AD. _β (β nuclide count rate); the positive pulse signal S _α is converted into a count rate n _α (α nuclide count rate) by AD.

The positive pulse signal S _α and the anti-coincidence signal S _γ are screened through the signal waveform and energy amplitude to generate α signal S _α' and γ signal S _γ' respectively, and the positive pulse signal S _α' and γ signal _{S γ'} are respectively delayed. 10μs, with the falling edge of S _α' as the threshold, the delayed signal of the S _γ' signal found within 10 μs is retained, and the coincidence signal S _Rn is recorded and converted to n _Rn' (radon gas coincidence count rate) by AD; the delay signal is The subsequent α signal S _α' is delayed for another 180 μs, and the falling edge of S _α' is used as the threshold. The anti-coincidence signal S _γ' is found to be retained within 180 μs, and the random coincidence signal S _k is recorded and converted to a count rate n _k (random) by AD. Noise count rate); delay the anti-coincidence signal S _γ' by 180 μs, use the falling edge of S _γ' as the threshold, and retain the delayed signal of the S _α' signal found within 180 μs, and record the coincidence signal S _Th and convert it to n by AD _Th' (thoron coincidence count rate).

Delay the coincidence signal S _Rn and the random coincidence signal _Sk by 10 μs respectively. The falling edge of S _Rn is used as the threshold. If the delayed signal of the _Sk signal is found within 10 μs, the delayed signal of the Sk signal is excluded. The anti-coincidence signal S _Rn' is recorded and converted by AD to Count rate n _Rn (radon gas progeny ²¹⁴ Po counting rate); delay the coincidence signal S _Th and the random coincidence signal _Sk by 10 μs respectively, use the falling edge of S _Th as the threshold, and find the delay of the _Sk signal within 10 μs The signal is eliminated, and the anti-coincidence signal S _Th' is recorded, which is converted into a count rate n _Th (count rate of thoronium gas daughter ²¹² Po) by AD;

Process and calculate n _α , n _Rn and n _Th to obtain the artificial radioactive total α activity concentration A(α); process and calculate n _Rn , n _Th and n _β to obtain the artificial radioactive total β activity concentration A (β ).

Calculate the total α and total β activity concentrations of artificial radioactivity through formula (1) and formula (2) respectively:

In the formula: A(α) is the total α activity concentration of artificial radioactivity; n _α is the total α count rate; n _Rn is the radon gas daughter ²¹⁴ Po count rate; n _Th is the thoron gas daughter ²¹² Po count rate; a' is the radioactive radon α correction factor; b' is the radioactive thorium α correction factor; n _k is the random noise count rate; ε _α is the total α detection efficiency; ε _β is the total β detection efficiency; ε _γ is the total γ detection efficiency; V is the sampling volume.

In the formula: A(β) is the total β activity concentration of artificial radioactivity; n _β is the total β count rate; n _Rn is the radon gas daughter ²¹⁴ Po count rate; n _Th is the thoron gas daughter ²¹² Po count rate; a is the radioactive radon β correction factor; b is the radioactive thorium β correction factor; n _k is the random noise count rate; ε _α is the total α detection efficiency; ε _β is the total β detection efficiency; ε _γ is the total γ detection efficiency; V is Sampling volume.

The online monitoring device for aerosol radioactivity in the environment around a nuclear facility of the present invention includes a sampling system, a paper control system, a detection system, and a data processing system; the sampling system is used to collect aerosol samples from the air; the paper control system is used It is used to control the transmission of filter paper; the detection system is used to measure the radioactive rays emitted by the aerosol deposited on the surface of the filter paper; the data processing system is used to collect and analyze the electronic signals output by the detection system to achieve ²¹² Bi/ ²¹² Po and ²¹⁴ Bi / ²¹⁴ Po respectively meets the screening function, and further calculates the activity concentration of total α and total β nuclides in the aerosol, and the detection limit of total β is as low as 1Bq/m ³ . The continuous monitoring device for aerosols in the environment around nuclear facilities of the present invention performs continuous sampling, continuous measurement, and online analysis of aerosols. It uses a composite detector to detect total α and total β nuclides, and compensates for the interference in the measurement process through a coincidence algorithm. The interference of natural nuclides enables real-time, high-precision measurement of the activity concentration of artificial radioactive total α and total β nuclides.

The above embodiments are only for illustrating the technical concepts and characteristics of the present invention. Their purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly. They cannot thereby limit the scope of protection of the present invention. Equivalent changes or modifications in spirit shall be included in the protection scope of the present invention.

Claims (15)

1. The on-line monitoring device for the radioactivity of the aerosol in the surrounding environment of the nuclear facility is characterized by comprising a sampling system, a paper control system, a detection system, a data processing system and a control system; the sampling system is used for collecting aerosol samples from air; the paper control system is used for controlling the filter paper to be conveyed; the detection system is used for detecting radioactive rays emitted by aerosol deposited on the surface of the filter paper; the data processing system is used for acquiring the radioactive signals and measuring and calculating the activity concentration of the total alpha and total beta nuclides in the aerosol sample.

2. The on-line monitoring device of aerosol radioactivity in an environment surrounding a nuclear facility of claim 1, wherein the sampling system comprises:

a filter paper for depositing aerosol particles in air to form an aerosol sample;

the gas channel comprises a sampling port, an exhaust port and a gas path pipeline;

and the sampling motor is used for driving air to enter the gas channel from the sampling port so that the sampling port forms negative pressure and is discharged from the exhaust port.

3. The aerosol radioactivity online monitoring device of claim 2, wherein the sampling system comprises:

the pressure sensor is positioned on the gas path pipeline and is used for monitoring the pressure difference in the gas path pipeline;

and the mass flowmeter is positioned on the gas path pipeline and is used for recording the air collection quantity.

4. The aerosol radioactivity online monitoring device of claim 1, wherein the paper control system comprises:

a transfer module comprising a first end and a second end, the transfer module being capable of transferring the filter paper from the first end to the second end;

and the stepping motor is used for controlling the operation of the transmission module.

5. The online monitoring device for aerosol radioactivity of claim 4, wherein: the first end of the conveying module comprises a first conveying roller, a paper feeding wheel, a first stretching scroll and a second stretching scroll, and the second end of the conveying module comprises a second conveying roller, a third stretching scroll, a fourth stretching scroll and a paper collecting wheel.

6. The online monitoring device for aerosol radioactivity of claim 5, wherein: the filter paper is conveyed to the first stretching scroll and the second stretching scroll through the paper feeding wheel, conveyed to the sampling port through the first conveying roller, conveyed to the third stretching scroll and the fourth stretching scroll through the second conveying roller, and finally reaches the paper collecting wheel to be recovered.

7. The aerosol radioactivity online monitoring device of claim 1, wherein the detection system comprises:

a composite detector comprising LaBr ₃ Scintillators, znS (Ag) coatings, and BC-408 scintillators; the LaBr ₃ The scintillator is used for detecting gamma nuclides; the BC-408 scintillator is used for detecting total beta and total gamma nuclides; the ZnS (Ag) coating is used for detecting total alpha nuclides;

a photomultiplier tube for signal enhancement.

8. The aerosol radioactivity online monitoring device of claim 7, wherein: the LaBr ₃ A scintillator and the ZnS (Ag) coating are located above the filter paper, and the BC-480 scintillator is located below the filter paper; the ZnS (Ag) coating is coated on the LaBr ₃ One side of the scintillator, which is close to the filter paper; two of the photomultiplier tubes, one located at the LaBr ₃ The other is located below the BC-480 scintillator.

9. The aerosol radioactivity online monitoring device of claim 7, wherein: the detection system comprises a shielding body arranged at the outermost side, wherein the shielding body comprises an upper shielding body and a lower shielding body, the filter paper passes through the space between the upper shielding body and the lower shielding body, and the LaBr ₃ A scintillator, znS (Ag) plating, and one of the photomultiplier tubes are housed within the upper shield, and the BC-480 scintillator and the other photomultiplier tube are housed within the lower shield.

10. An on-line monitoring method of aerosol radioactivity in the surrounding environment of a nuclear facility using an on-line monitoring device according to any one of claims 1 to 9, comprising the steps of:

the control system generates a sampling signal according to the trigger signal, and the sampling system is started after responding to the sampling signal to deposit aerosol in the air on the surface of the filter paper;

the control system generates a transmission signal according to the sampling feedback signal, and the paper control system transmits a sampling area of the sampling filter paper to a detection area of the detection system for detection after responding to the transmission signal;

the control system generates a detection starting signal according to a transmission feedback signal output by the paper control system, and the detection system responds to the detection starting signal and detects a sampling area of the sampling filter paper after the detection starting signal is started;

the data processing system amplifies, forms and converts the detection information output by the detection system and outputs a standard pulse signal, and the standard pulse signal is counted and processed to obtain the artificial total alpha and total beta nuclide activity in the air.

11. The on-line monitoring method of claim 10, wherein: the composite detector receives the radioactive rays emitted by the aerosol, the ZnS (Ag) coating is used for receiving alpha rays, and the LaBr ₃ The scintillator is used for receiving gamma rays, the BC-480 scintillator is used for receiving beta rays and gamma rays, and the beta rays are multiplied by the photomultiplier tube and then output to obtain an alpha signal S detected by ZnS (Ag) _α ，LaBr ₃ Gamma signal S of scintillator detection _γ-L And the beta signal and gamma signal S detected by BC-480 scintillator _β&γ 。

12. The on-line monitoring method of claim 11, wherein: the LaBr ₃ The scintillator is a main detector, the BC-480 scintillator is an anti-coincidence detector, and the signal S _γ-L And S is _β&γ Performing inverse fitting to generate gamma signal S _γ ，S _γ AD conversion to count rate n _γ' The method comprises the steps of carrying out a first treatment on the surface of the The BC-480 scintillator is taken as a main detector, and the LaBr ₃ The scintillator is an anti-coincidence detector, for the signal S _γ-L And S is _β&γ Performing inverse fitting to generate beta signal S _β ，S _β AD conversion to count rate n _β The method comprises the steps of carrying out a first treatment on the surface of the The alpha signal S _α AD conversion to count rate n _α 。

13. The on-line monitoring method of claim 12, wherein: the gamma signal S _γ And the alpha signal S _α The discrimination of the signal waveform and the energy amplitude is adopted to respectively generate the discriminated gamma signals S _γ’ And alpha signal S _α’ The gamma signal S _γ’ And alpha signal S _α’ Performing two-time delay coincidence to respectively generate radon gas ²¹⁴ Po coincidence signal, random coincidence signal and thorium gas body ²¹² Po accords with the signal, and is converted into a counting rate n through AD respectively _Rn' 、n _k And n _Th' The method comprises the steps of carrying out a first treatment on the surface of the The radon gas daughter ²¹⁴ Po coincidence signal and random coincidence signal for inverseCoincidence produces radon emanator with a deduction of random coincidence ²¹⁴ Po signal, AD converted into count rate n _Rn The method comprises the steps of carrying out a first treatment on the surface of the The thorium gas body ²¹² Performing anti-coincidence on Po coincidence signal and random coincidence signal to generate thorium gas body deducting random coincidence ²¹² Po signal, AD converted into count rate n _Th 。

14. The on-line monitoring method according to claims 11-13, characterized in that: for said n _α 、n _Rn And n _Th Processing calculation is carried out to obtain the artificial radioactivity total alpha activity concentration A (alpha), and the artificial radioactivity total alpha activity concentration A (alpha) is obtained through calculation according to the following formula:

wherein: a (α) is the total activity concentration of artificial radioactivity; n is n _α A total count rate of alpha; n is n _Rn Is radon gas ²¹⁴ Po count rate; n is n _Th Is a thorium gas body ²¹² Po count rate; a' is a radioactive radon alpha correction factor; b' is a radioactive thorium alpha correction factor; n is n _k Is the random noise count rate; epsilon _α Is the total alpha detection efficiency; epsilon _β Is the total beta detection efficiency; epsilon _γ Is the total gamma detection efficiency; v is the sampling volume.

15. The on-line monitoring method according to claims 11-13, characterized in that: for said n _Rn 、n _Th And n _β Processing calculation is carried out to obtain the artificial radioactivity total beta activity concentration A (beta), and the artificial radioactivity total beta activity concentration A (beta) is obtained through calculation according to the following formula:

wherein: a (β) is the total activity concentration of artificial radioactivity; n is n _β Is beta total count rate; n is n _Rn Is radon gas ²¹⁴ Po count rate; n is n _Th Is a thorium gas body ²¹² Po count rate; a is a radioactive radon beta correction factor; b is a radioactive thorium beta correction factor; n is n _k Is the random noise count rate; epsilon _α Is the total alpha detection efficiency; epsilon _β Is the total beta detection efficiency; epsilon _γ Is the total gamma detection efficiency; v is the sampling volume.