High-resolution radon, thoron and their daughter nuclides combined measuring device and measuring method thereof

Abstract

The application discloses a high-resolution radon / thorium emanation and daughter combined measuring device and a measuring method thereof, and a radon / thorium emanation and daughter synchronous measuring method, wherein, ① first sampling and emanation measurement: firstly, start the radon / thorium emanation and daughter measuring unit tension motor, open the second and third valves, and close the first valve; ② paper feeding: firstly, start the tension motor, and start the paper feeding motor; ③ sampling, emanation and daughter measurement: carry out synchronous sampling radon / thorium emanation measurement and radon / thorium emanation and daughter measurement, firstly, open the second and third valves, close the first valve, and start the PIPS detector in the radon / thorium emanation and daughter measuring unit to measure the alpha energy spectrum. The application has reasonable structure, novel design, realizes high-resolution, high-response, synchronous, rapid, on-line combined continuous measurement of radon emanation, thorium emanation, radon daughter and thorium emanation daughter at the same sampling point, improves the accuracy of the measurement result, and the sampling and measurement can be carried out synchronously, thereby realizing rapid measurement of the instrument.

Description

Technical Field

[0001] The present invention belongs to the technical field of radon / thoron measurement, in particular to a high-resolution radon, thoron and daughter combined measurement device and a measurement method thereof. Background Art

[0002] Domestic and international research methods for radon, thoron, and their daughters are generally divided into two categories: instantaneous continuous measurement and long-term cumulative measurement. Instantaneous continuous measurement can provide the activity concentration of Rn, Tn, and their daughters at the moment of measurement or within a short period of time, which is convenient and quick. Currently, in the online measurement of radon / thoron, most of them still focus on radon measurement, and very few have achieved simultaneous radon and thoron measurement; in the measurement of daughter concentration, the vast majority measure the daughter potential concentration, and cannot distinguish the concentration of each daughter, and thus cannot specifically analyze the impact of each daughter on the human body; very few instruments can achieve online measurement of radon / thoron and its daughters, among which the invention patent "A system and method for online measurement of radon and thoron and their daughter concentrations, application number: 201510667018.1" is the most representative. The invention patent is analyzed below. The patent mainly consists of a radon and thoron measurement device 100, a radon and thoron daughter measurement device 200, a display terminal 300, and a mobile power supply 400, wherein the display terminal is connected to the device 100 and the device 200. The radon and thoron measurement device 100 includes an electrostatic collection chamber 101, a daughter filter 102, a first air pump 103, a first detector 104, and a first signal and data processing module 106; the radon and thoron daughter measurement device 200 includes a daughter sampling chamber 201, a sampling filter membrane 202, a second air pump 203, a second detector 204, and a second signal and data processing module 205.

[0003] The measurement of radon and thoron is completed by the radon and thoron measuring device 100: the mixed air of radon, thoron and their daughters is filtered out by the daughter filter 102 under the action of the first vacuum pump 103, and then the radon and thoron enter the electrostatic collection chamber 101, in which the radon decay generated is collected. 218 Po particles and thoron decay 216 Po particles, detected by the first detector 104 218 The 6.00 MeV first alpha particle produced by the decay of the Po particle and 216 The 6.78MeV second α particle generated by the decay of the Po particle is detected, and the corresponding first detection signal is output; the first α particle and the second α particle are identified and counted respectively according to the first detection signal, and the concentration values ​​of radon and thoron are calculated and output to the display terminal 300 according to the counting results.

[0004] Daughter measurement is accomplished using a radon and thoron daughter measurement device 200. A second vacuum pump 203 collects radon and thoron daughters from a mixture of radon and thoron air onto a sampling filter 202 in a daughter sampling chamber 201. A second detector 204, located opposite the sampling filter 202, detects the 6.00 MeV third alpha particle, 7.69 MeV fourth alpha particle, and 8.78 MeV fifth alpha particle produced by the decay of the radon and thoron daughters, and outputs corresponding second detection signals. Based on the second detection signals, the third, fourth, and fifth alpha particles are integrated and counted over five time periods. The radon and thoron daughter concentrations are calculated and output to a display terminal based on the counting results.

[0005] This device can achieve simultaneous, rapid, direct, and continuous measurement of radon, thoron, and their daughters. However, it still has the following shortcomings:

[0006] ① The device as a whole adopts a dual-path sampling method, that is, the "radon and thoron measurement device" adopts a separate air inlet sampling port, and the "radon and thoron daughter measurement device" also adopts a separate air inlet sampling port. Therefore, this sampling method cannot obtain the concentration values ​​of radon, thoron and its daughters at the same sampling point. Due to the short half-life of thoron, its concentration value is greatly affected by the spatial position, which will introduce large errors when analyzing parameters such as the environmental balance factor.

[0007] ② The "radon and thoron measurement device" and the "radon and thoron daughter measurement device" are two independently operated devices, which can easily cause the measurement cycles to be out of sync, making it difficult to analyze the concentrations of nuclides at the same time.

[0008] In the "radon and thoron daughter measurement device," alpha rays emitted by the nuclides must pass through a certain distance of air and a filter membrane of a certain thickness before reaching the detector surface. As the alpha rays pass through the air and filter membrane, their energy attenuates, causing energy peak tailing. Although this device uses an overlap factor to address the tailing issue, this method assumes a constant overlap factor, which introduces certain errors at different concentrations.

[0009] ④ If the filter membrane is not replaced for a long time during daughter measurement, the measurement of the current cycle sample will be affected by the previously deposited sample. Even if the radioactive residual deduction is performed in the algorithm, the uncertainty of the daughter measurement result will increase.

[0010] ⑤ The measurement and analysis of daughter bodies adopts the method of integral counting in five time periods, namely the five-segment method. The shortest measurement period is 2 hours, which means that the daughter body concentration value within 2 hours cannot be obtained, which is not conducive to the study and analysis of the change law of daughter bodies in a shorter time.

[0011] ⑥ When measuring radon and thoron, drying is not performed. The radon concentration correction curve is corrected according to the established temperature and humidity. However, at high humidity, the instrument has few measurement counts and low response. The temperature and humidity correction will increase the uncertainty of the measurement results. Summary of the Invention

[0012] The object of the present invention is to provide a high-resolution combined measurement device for radon, thoron and their daughters, which has a reasonable structure and novel design. It can achieve high-resolution, high-response, synchronous, rapid, online combined continuous measurement of radon / thoron, radon daughters and thoron daughters at the same sampling point, thereby improving the accuracy of the measurement results. Sampling and measurement can be carried out synchronously, realizing rapid measurement of the instrument.

[0013] Another object of the present invention is to provide a measurement method of a high-resolution radon, thoron and their daughter combined measurement device.

[0014] The object of the present invention is achieved as follows: a high-resolution combined measurement device for radon, thoron and their daughters, wherein a radon thoron daughter measurement unit and a radon thoron measurement unit are arranged in a housing, wherein the structure of the radon thoron daughter measurement unit is that the filter paper of the filter paper roll driven wheel is upwardly connected to the filter paper roll driving wheel driven by the paper feeding motor through two symmetrical steering wheels, an impactor particle size separator with an air inlet and a PIPS detector are fixed above the horizontal section of the filter paper, the air outlet of the impactor particle size separator and the measurement port of the PIPS detector are respectively connected to the filter paper through an annular sealing gasket, and left and right clamping devices corresponding to the impactor particle size separator and the PIPS detector are respectively installed below the horizontal filter paper through a guide support frame, the left and right clamping devices supported by springs are fixedly mounted on a lifting bracket, and the eccentric wheel driven by the tensioning motor is connected to the lifting bracket. To match, upright through-going central air ducts are respectively provided in the left and right pressing devices, and the air inlets of the two central air ducts are respectively matched with the air outlet of the impact-type particle size separator and the air inlet of the vacuum chamber arranged at the upper end of the right pressing device, and the air outlet of the central air duct is connected to the sampling tube and the vacuum tube through a hose, wherein the vacuum tube is connected to the vacuum pump through a pressure sensor, and the sampling tube is connected to the sampling tee of the radon thoron gas measuring unit through a first mass flow meter, wherein one connecting pipe of the tee is connected to the sampling pump through a first valve, and the other connecting pipe is connected to the inlet of the membrane drying module through a second valve, and the outlet pipe of the membrane drying module is connected to the inlet of the gas meter through a second mass flow meter, and the outlet pipe of the gas meter is connected to the backflush inlet of the membrane drying module, and the backflush outlet pipe of the membrane drying module is connected to the sampling pump tube through a third valve.

[0015] A filter paper travel switch is provided on the driven wheel side of the filter paper roll.

[0016] Two symmetrical eccentric wheel travel switches are respectively arranged on both sides of the eccentric wheel.

[0017] A wheel disc is arranged on the outer end surface of the eccentric wheel, the center of the wheel disc is concentric with the axis of the driving motor, and a contact matched with the eccentric wheel travel switch is arranged on the wheel disc surface.

[0018] The structure of the radiance meter is a hemispherical measurement chamber composed of a stainless steel plate fixed on an electrical bakelite board. An isolation cover made of organic glass is arranged outside the measurement chamber. The air inlet interface arranged on the top of the measurement chamber is located outside the isolation cover. A through hole and a detection port are provided on the electrical bakelite board in the measurement chamber. A temperature and humidity sensor is installed on the through hole, and a gold silicon surface barrier detector is installed on the detection port. A high-voltage head is installed on the electrical bakelite board between the measurement chamber and the isolation cover.

[0019] The PIPS detector, gold-silicon surface barrier detector, sampling pump, vacuum pump, paper feed motor, tension motor, filter paper travel switch, eccentric wheel travel switch, temperature and humidity sensors, and pressure sensor are all connected to the control system through wires.

[0020] The spring is composed of a compression spring. The lower ends of the two springs are respectively fixed on the fixed supports, and the upper ends of the two springs are respectively matched with the back sides of the left and right disc-shaped upper pressing platforms of the pressing devices.

[0021] The objectives of the present invention are achieved by providing a high-resolution combined measurement device for radon, thoron, and their daughters, and a radon / thoron daughter measurement method. ① Sampling: First, a tensioning motor is activated to cause a spring-supported compression device to move upward and compress the filter paper below the impact-type particle size separator to prevent air leakage in the sampling pipeline. Then, a first valve is opened, the second and third valves are closed, and a sampling pump is activated to collect aerosol particles with a particle size of less than 1 μm on the filter paper. After sampling is completed, the first valve is closed.

[0022] ②Paper feeding: First, start the tensioning motor to move the pressing device downward to loosen the filter paper. Then, start the paper feeding motor to transfer the filter paper sampling area to the bottom of the PIPS detector and press the filter paper again. The entire paper feeding process is controlled within 1 minute.

[0023] ③Measurement: Control the vacuum pump to evacuate the vacuum chamber, reducing the vacuum degree to less than 1kPa within 30 seconds and maintaining it during the operation of the vacuum pump. Then, carry out α energy spectrum measurement in two time periods. Based on the measured full energy peak counts at 6.0MeV, 7.69MeV, and 8.78MeV, analyze and give the radon daughters 218 Po, 214 Pb, 214 Bi and thoron daughters 212 Pb, 212 After the measurement is completed, the vacuum pump is turned off, and the entire analysis cycle is completed. Repeat all the above actions to start the continuous measurement mode.

[0024] Radon / thoron measurement method: ① Sampling: First, start the tensioning motor to make the compression device move upward to compress the filter paper below the impact particle size separator to prevent leakage in the sampling pipeline. Then, open the second and third valves, close the first valve, start the sampling pump, and at the same time, apply a voltage of 2000V to the measuring inner wall of the thoron measuring instrument.

[0025] ②Measurement: When the sampling pump is on, start the radiant gas meter to measure. Set the single measurement and continuous measurement modes according to the measurement needs. After each measurement cycle, the radon and thoron radiant gas activity concentrations are given based on the measured full energy peak count values ​​at 6.0MeV, 6.78MeV, 7.69MeV and 8.7MeV. After all measurements are completed, turn off the sampling pump and close the second and third valves.

[0026] ③ Background cleaning: Outdoors or in places where the radon / thoron activity concentration in the ambient air is low, first start the tensioning motor to make the compression device move upward to compress the filter paper below the impact-type particle size separator, then open the second and third valves, close the first valve, start the sampling pump to allow the air flow to pass through the emanator for 1 hour, then turn off the sampling pump, and repeat the flushing process at least 3 times. During the background cleaning period, no voltage is applied to the inner wall of the measurement chamber of the emanator, and the emanator does not work.

[0027] Method for synchronous measurement of radon / thoron and its daughters: ① Initial sampling and radiant gas measurement: First, start the tensioning motor of the radon / thoron daughter measurement unit, so that the pressing device moves upward to press the filter paper below the impact-type particle size separator to prevent air leakage in the sampling pipeline. Open the second and third valves, close the first valve, start the sampling pump, and collect aerosol particles with a particle size of less than 1 μm on the filter paper. At the same time, apply a voltage of 2000V to the inner wall of the measurement chamber of the radiant gas measuring device, and start the radiant gas measuring device in the radon / thoron measurement unit for measurement. After sampling, turn off the sampling pump, reduce the high pressure in the radiant gas measuring chamber, stop the radiant gas measurement, and close the second and third valves. ② Paper feeding: First, start the tensioning motor to move the pressing device downward to loosen the filter paper. Start the paper feeding motor to transfer the filter paper sampling area to the bottom of the PIPS detector, and press the filter paper again. The entire paper feeding process is controlled within 1 minute.

[0028] ③ Sampling, emanation, and daughter measurement: Conduct simultaneous sampling for radon / thoron measurement and radon / thoron daughter measurement. First, open the second and third valves and close the first valve. Then, control the vacuum pump to evacuate the vacuum chamber of the radon / thoron daughter measurement unit, reducing the vacuum to less than 1 kPa within 30 seconds and maintaining it while the vacuum pump is running. Simultaneously, start the sampling pump and collect aerosol particles with a particle size of less than 1 μm on filter paper. Simultaneously, apply a voltage of 2000 V to the inner wall of the emanation measurement chamber and start the emanation meter in the radon / thoron measurement unit for measurement. Then, start the PIPS detector in the radon / thoron daughter measurement unit to measure the alpha energy spectrum. After sampling, turn off the sampling pump and vacuum pump, reduce the high pressure in the emanation measurement chamber, and stop emanation and daughter measurement. Then, close the second and third valves and repeat steps ② and ③ above to start the simultaneous continuous measurement method of radon / thoron and its daughters.

[0029] The present invention primarily consists of a radon / thoron daughter measurement unit, a radon / thoron measurement unit, and a control system. The radon / thoron daughter measurement unit is deployed at the front end of the system, while the radon / thoron measurement unit is deployed at the rear end. The device has three operating modes: radon / thoron measurement mode, radon / thoron daughter measurement mode, and simultaneous measurement of radon / thoron and its daughters.

[0030] Radon / thoron daughter measurement unit

[0031] The filter paper roll sampling method + PIPS semiconductor detection is adopted, and the sampling port and detector are separated. During sampling, the airflow passes through the impact particle separator to remove aerosols with an aerodynamic diameter greater than 1μm, and the small-sized aerosols are enriched on the filter paper. After sampling, the filter paper rolls, and the filter paper sampling area reaches directly below the detector. The vacuum chamber is evacuated to a vacuum degree of less than 1kPa to ensure high-resolution measurement of the alpha energy spectrum. The detector measures the radon daughters in the filter paper sample. 218 Po emission of 6.0MeV, 214 7.69 MeV α particles and thoron daughters emitted by Po 212 Bi emission of 6.05MeV, 212 The total energy peak count value of 8.78 MeV α particles emitted by Po is used to calculate the radon progeny in the ambient air using a two-stage method. 218 Po, 214 Pb, 214 Bi and thoron daughters 212 Pb, 212 Activity concentration of Bi.

[0032] The daughter measurement structure consists of a daughter sampling module and a daughter measurement module. The daughter sampling module consists of a particle size separator, a filter paper conveyor, a paper press, a mass flowmeter, and a sampling pump. The daughter measurement module comprises an alpha spectrometer system and a vacuum system. The alpha spectrometer system includes a PIPS detector and control system, while the vacuum system comprises a vacuum chamber, a vacuum pump, piping, and a pressure sensor. Both the sampling and measurement modules consist of upper and lower parts, mounted on the upper and lower portions of the clamping device support module, respectively. The support module is stationary, while the upper portion of the sampling and measurement modules is fixed, while the lower portion reciprocates up and down under the guidance of the support module, creating two states of compression and release of the filter paper. The filter paper rolls are located on the left and right sides of the clamping device, respectively. The filter paper is wound around these two wheels and passed through the gap between the upper and lower parts of the clamping device. A limit switch controls the movement of the collected daughter filter paper directly below the PIPS detector. The support plate is located at the bottom end of the lower portion of the clamping mechanism, connecting the lower portion of the sampling and measurement module's movable units. An eccentric is located above the support plate. The paper lift limit switch and paper press limit switch are located to the left and right of the eccentric, respectively. When the motor is running, the eccentric rotates with it, causing the support plate, which rests against the eccentric, and the lower portion of the clamping mechanism to reciprocate up and down. When the support plate reaches its lowest point, the paper lift limit switch signals, and the paper feed motor, connected to the drive pulley, rotates the filter paper roll. When the support plate reaches its highest point, the paper press limit switch signals, indicating a distance between the filter paper and the PIPS detector of less than 2 mm. Within 30 seconds of starting the vacuum pump, the vacuum level in the measurement chamber drops below 1 kPa and remains below 1 kPa for the duration of the vacuum pump operation (for more than one hour). The particle size separator and PIPS detector are mounted on the left and right sides of the upper portion of the support module, respectively. The upper and lower portions of the sampling and measurement modules are sealed with annular silicone gaskets. Springs are located on the lower portions of both the sampling and measurement modules.

[0033] Radon / Thoron Measurement Unit

[0034] The method of electrostatic collection + gold silicon surface barrier semiconductor detector measurement is adopted. The air passes through the radon / thoron daughter measurement unit to filter out daughters, dust, etc. and then enters the membrane drying module for dehumidification. When the humidity is above 90%, it can also be reduced to below 30% RH, which can effectively improve the sensitivity of the gas detection; then it enters the high-voltage measurement chamber, and the inner wall of the high-voltage measurement chamber is added with 2000V positive high voltage (0-3kV adjustable). The inner wall of the measurement chamber is insulated from the detector, and the outer surface of the detector is grounded. The inner wall of the measurement chamber and the surface of the detector form a high-voltage electric field, and the first daughter after the decay of radon and thoron is detected by the high-voltage measurement chamber. 218 Po and 216 Po is positively charged and is concentrated on the detector surface under the action of a high voltage electric field. The detector measures the newly formed radon daughters. 218 Po emission of 6.0MeV, 2147.69 MeV α particles and newly formed thoron daughters emitted by Po 216 Po emission of 6.78MeV, 212 Bi emission of 6.05MeV, 212 The total energy peak count value of 8.78 MeVα particles emitted by Po, combined with the preset temperature and humidity correction parameters, gives the radon ( 222 Rn) and thoron ( 220 Then the gas coming out of the high voltage measurement chamber is reversed into the membrane drying module to spray wet water vapor outside the membrane, and the water vapor is discharged directly into the atmosphere so that the measurement process does not affect the humidity parameters of the measurement environment.

[0035] The radon / thoron measurement module utilizes a hemispherical stainless steel chamber with a volume of 0.8L. Because a high voltage of several thousand volts is applied to the hemisphere, it is protected by a transparent plexiglass cover with a diameter of 180mm to prevent direct contact with personnel. The hemisphere is fixed to a board with electrical bakelite and features air inlet and outlet ports and a built-in temperature and humidity sensor. A high-resolution gold-silicon surface barrier detector is mounted at the bottom of the chamber. The preamplifier outputs the signal to a multi-channel module on the mainboard for A / D conversion and spectrum generation. Target nuclides are analyzed using alpha spectrum analysis.

[0036] control system

[0037] The control system is used to control the setting and execution of the sampling process and measurement program, the positioning of the filter paper roll, and the monitoring of the temperature, humidity, pressure and flow status. It consists of an embedded control system, a touch screen display and relays.

[0038] Measurement and control software is configured on the industrial control computer, which is connected to the embedded control board and multi-channel pulse processor via RS485 and USB respectively; the embedded control board is designed with an industrial-grade ARM processor; the motor and pump control interfaces use solid-state relays with load redundancy, and the control circuit and load circuit are optically isolated; the entire system is designed in a modular manner.

[0039] The system's measurement and control software is based on an industrial computer operating system and performs functions such as automatic processes, manual control, controller communication and status display, and multi-channel data acquisition, storage, and analysis. Manual process control is achieved through user message responses, while automatic control processes are implemented through timer messages and preset logical sequences. Status displays and multi-channel data are uploaded from the slave computer to the master computer via COM and USB ports for display and storage. Users can achieve control effects by presetting various parameters.

[0040] Experimental tests on energy resolution, repeatability, volume activity response, and relative inherent error were carried out under ambient temperature of 27°C, relative humidity of 64% RH, and air pressure of 99 kPa.

[0041] 1. Energy resolution

[0042] The energy resolution is expressed as the percentage of the full width at half maximum (FWHM) of the characteristic peak of the α energy spectrum to the peak position. The data are shown in Table 1.

[0043] Table 1 Energy resolution test of radon / thoron and its daughter at different energies

[0044]

[0045] From the data in Table 1, it can be seen that the energy resolution of the energy peaks of interest in the daughter and radium measurement units is less than 0.8% and 3%, respectively, indicating that the present invention can achieve high-resolution measurement of radon / thoron and its daughters.

[0046] 2. Repeatability

[0047] Under different concentrations of radon, thoron and their daughters, repeatability experiments with a measurement period of 30 minutes were carried out, and the repeatability was calculated according to the following formula.

[0048]

[0049] Where: V is repeatability; X i is the i-th measurement value; is the average value of n measurements.

[0050] The data are shown in Tables 2 and 3, respectively. The repeatability deviations for the radon, thoron, radon daughter, and thoron daughter measurements were less than 6.5%, 8.7%, 8.8%, and 11.1%, respectively. According to the requirements of the National Metrology Verification Regulations for Radon Detectors (JJG825-2013), the repeatability of the radon detector is no more than 15%, indicating that the present invention meets the requirements for repeatability of radon measurements in the National Metrology Verification Regulations.

[0051] 3. Volume activity and potential concentration response

[0052] Under different concentrations of radon, thoron and their daughters, volume activity response and potential concentration response experiments with a measurement period of 30 minutes were carried out and calculated according to the following formula.

[0053]

[0054] Where: R j is the volume activity response or potential concentration response of the jth concentration measurement point; X j is the average value of the jth concentration measurement point; Q j The agreed true value for the jth concentration measurement point.

[0055] The data are shown in Table 2 and Table 3 respectively. The average values ​​of the volume activity responses of radon and thoron are 1.015 and 1.011 respectively; the average values ​​of the potential concentration responses of radon / thoron daughters are 1.008 and 0.991 respectively, indicating that the measurement results of the present invention are close to the agreed true values.

[0056] 4. Relative inherent error

[0057] The relative inherent error E is calculated from the volume activity response or potential concentration response of each measurement point according to the following formula: j .

[0058]

[0059] The relative inherent errors for a 30-minute measurement period at different radon, thoron, and their daughter concentrations are shown in Tables 2 and 3. The relative inherent errors for radon, thoron, and radon daughters are less than 2.7%, 2.3%, and 3.4%, respectively. According to the National Metrology Verification Regulations for Radon Detectors (JJG825-2013), the relative inherent error of a radon detector should not exceed ±20%, demonstrating that the present invention meets the requirements of the National Metrology Verification Regulations for relative inherent errors in radon measurements.

[0060] Table 2 Performance test of radon thoron at different reference activity concentrations

[0061]

[0062]

[0063] Table 3 Performance test of daughter cells at different reference potential concentrations

[0064]

[0065] (1) The device adopts a single gas sampling method and can measure radon, thoron, and radon daughters at the same sampling point. 218 Po, 214 Pb, 214 Bi and thoron daughters 212 Pb, 212 Activity concentration of Bi.

[0066] (2) The device has three working modes: radon / thoron measurement mode, radon / thoron daughter measurement mode, and radon / thoron and its daughter synchronous measurement mode. The mode can be selected according to the measurement needs. Among them, the radon / thoron measurement mode can measure and give the radon concentration and thoron concentration; the radon / thoron daughter measurement mode can measure and give the radon daughter concentration respectively. 218 Po, 214 Pb, 214 Bi and thoron daughters 212 Pb, 212The activity concentration of Bi can also give the potential concentration of radon daughters and the potential concentration of thoron daughters; the radon / thoron and its daughter synchronous measurement mode can measure and give the radon concentration, thoron concentration, radon daughter 218 Po, 214 Pb, 214 Bi and thoron daughters 212 Activity concentrations of Pb and 212Bi, radon daughter potential concentration, thoron daughter potential concentration, radon balance factor, thoron balance factor, etc. All measurement results since power-on are presented in the form of a data list and a "time-measurement result" graph.

[0067] (3) The radon / thoron daughter measurement unit adopts the filter paper roll feeding mode. The daughter samples are more representative, which solves the problem of the influence of radionuclide residues in the conventional method of not replacing the filter membrane for a long time and improves the accuracy of the measurement results. In this mode, the sampling and measurement of daughters are completed independently, ensuring the continuous monitoring of daughter concentration. The daughter sample sampling interval is the duration of the filter paper roll feeding process (less than 1 minute), which solves the problem of the conventional method of not replacing the filter membrane for a long time where sampling and measurement cannot be carried out simultaneously, resulting in a long sample sampling interval.

[0068] (4) During the measurement of the radon / thoron daughter measurement unit, the vacuum chamber is evacuated, which enables high-energy resolution measurement of the full-energy peaks of radon and thoron daughter nuclides, solves the problem of α energy spectrum tailing in conventional measurements, ensures that the full-energy peaks of radon and thoron daughter nuclides do not interfere with each other, and improves the accuracy of the measurement results.

[0069] (5) A membrane drying module is used for dehumidification in radon / thoron radiant measurement. The humidity of the air entering the radiant measurement chamber is less than 30%, achieving high-response radiant measurement. The moisture dehumidified by the membrane drying module is returned to the atmosphere after back-flushing through the back-flushing air path, without changing the ambient humidity. This solves the problem that conventional desiccant will change the ambient humidity after dehumidification and affect the radiant precipitation rate. The membrane drying module does not need to be replaced for at least 2 years, which solves the problem that conventional desiccant is easy to fail.

[0070] (6) Flexible parameter setting. According to the calibration results of the metering station, basic parameters such as the instrument calibration factor can be flexibly adjusted to ensure that the instrument measurement display value is as close as possible to the agreed true value of the measurement; measurement parameters such as sampling time and measurement time can be flexibly set according to measurement needs, ensuring rapid measurement of the instrument and solving the problems of cumbersome measurement process and long measurement time in the current conventional sub-volume measurement method; automatic operation and manual operation can be set as needed.

[0071] The present invention can achieve high-resolution, high-response, synchronous, rapid, online, combined and continuous measurement of radon, thoron, radon daughters, and thoron daughters at the same sampling point, improving the accuracy of the measurement results. Sampling and measurement are carried out synchronously, enabling rapid measurement by the instrument. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The present invention will be further described below with reference to the accompanying drawings. Figure 1 It is a structural schematic diagram of the present invention, Figure 2 This is a schematic diagram of the cross-sectional structure of the emanator. Figure 3 This is a signal transmission relationship diagram of the radon / thoron and its daughter combined measurement system of the present invention. Figure 4 It is a system software block diagram of the present invention. DETAILED DESCRIPTION

[0073] A high-resolution combined measurement device for radon, thoron and their daughters, such as Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 As shown, a radon thoron daughter measuring unit 1 and a radon thoron measuring unit 2 are arranged in the casing, wherein the structure of the radon thoron daughter measuring unit 1 is that the filter paper of the filter paper roll driven wheel 3 is upwardly connected to the filter paper roll driving wheel 5 driven by the paper feeding motor through two symmetrical steering wheels 4. An impact particle size separator 7 and a PIPS detector 8 with an air inlet 6 are fixed above the horizontal section of the filter paper. The air outlet of the impact particle size separator 7 and the measuring port of the PIPS detector 8 are respectively corresponding to the filter paper through an annular sealing gasket 9. Left and right clamping devices 10 and 11 corresponding to the impact particle size separator 7 and the PIPS detector 8 are respectively installed below the horizontal filter paper through a guide support frame. The left and right clamping devices 10 and 11 supported by a spring 12 are fixed on a lifting bracket 13. The eccentric wheel 14 driven by the tensioning motor cooperates with the lifting bracket 13. The left and right clamping devices 10 and 11 are respectively provided with The central air duct 15 is vertically connected, and the air inlets of the two central air ducts 15 are respectively matched with the air outlet of the impact-type particle size separator 7 and the air inlet of the vacuum chamber 18 arranged at the upper end of the right pressing device 11. The air outlet of the central air duct 15 is connected to the sampling tube and the vacuum tube through a hose, wherein the vacuum tube is connected to the vacuum pump 21 through a pressure sensor 20, and the sampling tube is connected to the sampling tee of the radon and thoron gas measuring unit through a first mass flowmeter 19, wherein one connecting pipe of the tee is connected to the sampling pump 27 through a first valve 22, and the other connecting pipe is connected to the inlet of the membrane drying module 25 through a second valve 23, and the outlet pipe of the membrane drying module 25 is connected to the inlet of the gas meter 28 through a second mass flowmeter 26, and the outlet pipe of the gas meter 28 is connected to the backflush inlet of the membrane drying module 25, and the backflush outlet pipe of the membrane drying module 25 is connected to the sampling pump tube through a third valve 24.

[0074] A measurement method of a high-resolution radon, thoron and their daughter combined measurement device, such as Figure 1 、 Figure 2 、 Figure 3 、 Figure 4As shown, it has three working modes: radon / thoron measurement method, radon / thoron daughter measurement method, and radon / thoron and daughter synchronous measurement method. The working process of each mode is as follows:

[0075] 1. Radon / thoron daughter measurement method:

[0076] ① Sampling: First, start the paper lifting and pressing stepper motor to make the pressing device press the filter paper under the impact particle size separator 7 to prevent air leakage in the sampling pipeline; then, open the first valve 22, and close the second valve 23 and the third valve 24; then, start the sampling pump 27 to collect aerosol particles with a particle size of less than 1 μm on the filter paper; finally, after sampling is completed, turn off the sampling pump 27 and close the first valve 22.

[0077] ② Paper feeding: First, the paper lifting and pressing stepper motor is activated to release the filter paper. Then, the stepper motor is activated to move the filter paper sampling area directly below the PIP detector 8. Finally, the filter paper is pressed again. The entire paper feeding process is controlled within 1 minute.

[0078] ③ Measurement: First, control the vacuum pump 21 to evacuate the vacuum chamber 18, reducing the vacuum degree to less than 1kPa within 30 seconds and maintaining it while the vacuum pump 21 is running; then, perform α energy spectrum measurement in two time periods, and analyze the radon daughters based on the measured full energy peak counts at 6.0MeV, 7.69MeV, and 8.78MeV. 218 Po, 214 Pb, 214 Bi and thoron daughters 212 Pb, 212 After the measurement is completed, the vacuum pump 21 is turned off, thus completing the entire analysis cycle.

[0079] Repeat all the above steps to start the continuous measurement mode.

[0080] 2. Radon / thoron measurement method:

[0081] ① Sampling: First, start the radon / thoron daughter measurement unit paper lifting and pressing stepper motor, so that the pressing device presses the filter paper below the impact particle size separator 7 to prevent leakage in the sampling pipeline; then, open the second valve 23 and the third valve 24, and close the first valve 22; start the sampling pump 27, and at the same time, apply a voltage of 2000V to the inner wall of the measurement chamber.

[0082] ② Measurement: While the sampling pump is on, the radiant gas meter 28 is started for measurement. Depending on the measurement needs, single measurement and continuous measurement modes can be set. After each measurement cycle, the radon and thoron radiant gas activity concentrations are given based on the measured full-energy peak count values ​​at 6.0MeV, 6.78MeV, 7.69MeV and 8.78MeV. After all measurements are completed, the sampling pump 27 is turned off, and then the second valve 23 and the third valve 24 are closed.

[0083] ③ Background Cleaning: Outdoors or in a location with low radon / thoron activity, first activate the radon / thoron daughter measurement unit's paper lift and press stepper motor, causing the pressing device to compress the filter paper beneath the impactor particle size separator 7. Next, open the second and third valves 23 and 24, and close the first valve 22. Start the sampling pump 27 to allow air to flow through the measurement chamber for one hour, then shut off the sampling pump 27. Repeat this cleaning process at least three times. During the background cleaning, no voltage is applied to the measurement chamber's inner wall, and the radiant meter 28 is inoperative.

[0084] 3. Synchronous measurement method of radon / thoron and its daughters:

[0085] ① First sampling and emanation measurement: First, start the radon / thoron emanation daughter measurement unit paper lifting and pressing stepper motor, so that the pressing device presses the filter paper under the impact particle size separator 7 to prevent leakage in the sampling pipeline; then, open the second valve 23 and the third valve 24, and close the first valve 22; start the sampling pump 27 to collect aerosol particles with a particle size of less than 1 μm on the filter paper, and at the same time apply a voltage of 2000V to the inner wall of the emanation measurement chamber, and start the emanation meter 28 in the radon / thoron emanation measurement unit for measurement; after sampling, turn off the sampling pump 27, reduce the high pressure in the emanation measurement chamber, stop the emanation measurement, and then close the second valve 23 and the third valve 24.

[0086] ② Paper feeding: First, the paper lifting and pressing stepper motor is activated to release the filter paper. Then, the stepper motor is activated to move the filter paper sampling area directly below the detector 8. Finally, the filter paper is pressed again. The entire paper feeding process is controlled within 1 minute.

[0087] ③ Sampling, emanation, and daughter measurement: Sampling, radon / thoron measurement, and radon / thoron daughter measurement are performed simultaneously. First, open the second valve 23 and the third valve 24, and close the first valve 22. Then, control the vacuum pump 21 to evacuate the measurement chamber of the radon / thoron daughter measurement unit, reducing the vacuum to less than 1 kPa within 30 seconds and maintaining it while the vacuum pump 21 is running. Simultaneously, start the sampling pump 27 to collect aerosol particles with a particle size less than 1 μm on filter paper. Simultaneously, apply a voltage of 2000 V to the inner wall of the emanation measurement chamber, and start the PIP detector in the radon / thoron measurement unit to measure the alpha spectrometer. Then, start the alpha energy spectrum in the radon / thoron daughter measurement unit to measure. After sampling, close the sampling pump 27 and the vacuum pump 21, reduce the pressure in the emanation measurement chamber, stop the emanation and daughter measurement, and then close the second valve 23 and the third valve 24.

[0088] Repeat steps 2) and 3) above to start the synchronous continuous measurement mode of radon / thoron and its daughters.

Claims

1. A high-resolution combined measurement device for radon, thoron and their daughters, characterized by: A radon thoron daughter measuring unit (1) and a radon thoron measuring unit (2) are arranged in the housing. The structure of the radon thoron daughter measuring unit (1) is that the filter paper of the filter paper roll driven wheel (3) is upwardly connected to the filter paper roll driving wheel (5) driven by the paper feeding motor through two symmetrical steering wheels (4). An impact type particle size separator (7) with an air inlet (6) and a PIPS detector (8) are fixed above the horizontal section of the filter paper. The air outlet of the impact type particle size separator (7) and the PIPS detector (8) are fixed above the horizontal section of the filter paper. The measuring ports are respectively connected to the filter paper through an annular sealing gasket (9). The left and right pressing devices (10, 11) corresponding to the impact particle size separator (7) and the PIPS detector (8) are respectively installed below the horizontal filter paper through a guide support frame. The left and right pressing devices (10, 11) supported by a spring (12) are fixed on a lifting bracket (13). The eccentric wheel (14) driven by the tensioning motor cooperates with the lifting bracket (13). The left and right pressing devices (10, 11) are respectively provided with straight The central airway (15) is vertically connected, and the air inlets of the two central airways (15) are respectively matched with the air outlet of the impact type particle size separator (7) and the air inlet of the vacuum chamber (18) provided at the upper end of the right pressing device (11). The air outlet of the central airway (15) is connected to the sampling tube and the vacuum tube through a hose, wherein the vacuum tube is connected to the vacuum pump (21) through a pressure sensor (20), and the sampling tube is connected to the sampling tee of the radon thoron measurement unit through a first mass flow meter (19), wherein One connecting pipe of the three-way pipe is connected to the sampling pump (27) through the first valve (22), and the other connecting pipe is connected to the inlet of the membrane drying module (25) through the second valve (23). The outlet pipe of the membrane drying module (25) is connected to the inlet of the emanation meter (28) through the second mass flow meter (26). The outlet pipe of the emanation meter (28) is connected to the backflush inlet of the membrane drying module (25). The backflush outlet pipe of the membrane drying module (25) is connected to the sampling pump pipe through the third valve (24).

2. The measurement method of the high-resolution radon, thoron and their daughter combined measurement device according to claim 1, characterized in that: Radon / thoron daughter measurement method, ① sampling: first start the tension motor to make the compression device supported by the spring (12) press the filter paper below the impact type particle size separator (7) upward to prevent air leakage in the sampling pipeline, then open the first valve (22), close the second and third valves (23, 24), start the sampling pump (27), collect aerosol particles with a particle size of less than 1 μm on the filter paper, and after the sampling is completed, close the first valve (22); ② Paper feeding: First, start the tensioning motor to move the pressing device downward to loosen the filter paper. Then, start the paper feeding motor to transfer the filter paper sampling area to the bottom of the PIPS detector (8) and press the filter paper again. The entire paper feeding process is controlled within 1 minute. ③ Measurement: Control the vacuum pump (21) to evacuate the vacuum chamber (18) to a vacuum degree of less than 1 kPa within 30 seconds, and maintain the vacuum degree during the operation of the vacuum pump (21). Then, carry out α spectrum measurement in two time periods, and analyze and give the radon daughters based on the measured full energy peak count values ​​at 6.0 MeV, 7.69 MeV and 8.78 MeV. 218 Po, 214 Pb, 214 Bi and thoron daughters 212 Pb, 212 After the activity concentration of Bi is measured, the vacuum pump (21) is turned off, and the entire analysis cycle is completed. All the above actions are repeated to start the continuous measurement mode.

3. The measurement method of the high-resolution radon, thoron and their daughter combined measurement device according to claim 1, characterized in that: Method for measuring radon / thoron gas: ① Sampling: First, start the tensioning motor to make the compression device move upward to compress the filter paper below the impact-type particle size separator (7) to prevent leakage of the sampling pipeline. Then, open the second and third valves (23, 24), close the first valve (22), start the sampling pump (27), and at the same time apply a voltage of 2000V to the measuring inner wall of the gas meter (28); ② Measurement: While the sampling pump is on, the radiant gas measuring device (28) is started for measurement. According to the measurement requirements, the single measurement mode and the continuous measurement mode are set. After each measurement cycle, the radon and thoron activity concentrations are given based on the full energy peak count values ​​at 6.0 MeV, 6.78 MeV, 7.69 MeV and 8.7 MeV obtained by measurement. After all measurements are completed, the sampling pump (27) is turned off and the second and third valves (23, 24) are closed. ③ Background cleaning: Outdoors or in a place where the radon / thoron activity concentration in the ambient air is low, first start the tensioning motor to make the pressing device move upward to press the filter paper below the impact particle size separator (7), then open the second and third valves (23, 24), close the first valve (22), start the sampling pump (27) to allow the air flow to pass through the emanator (28), and continue for 1 hour, then turn off the sampling pump (27), and repeat the flushing process for no less than 3 times. During the background cleaning period, no voltage is applied to the inner wall of the measuring chamber of the emanator (28), and the emanator (28) does not work.

4. The measurement method of the high-resolution radon, thoron and their daughter combined measurement device according to claim 1 is characterized by: Method for synchronous measurement of radon / thoron and its daughters: ① first sampling and radium measurement: first start the tension motor of the radon / thoron daughter measurement unit, so that the compression device moves upward to compress the filter paper below the impact particle size separator (7) to prevent leakage of the sampling pipeline, open the second and third valves (23, 24), close the first valve (22), start the sampling pump (27), collect aerosol particles with a particle size of less than 1 μm on the filter paper, and at the same time add a voltage of 2000V to the inner wall of the measurement chamber of the radium meter (28), and start the radium meter (28) in the radon / thoron measurement unit to measure. After the sampling is completed, turn off the sampling pump (27), reduce the high pressure in the radium measurement chamber, stop the radium measurement, and close the second and third valves (23, 24); ② Paper feeding: First, start the tensioning motor to move the pressing device downward, loosen the filter paper, start the paper feeding motor to transfer the filter paper sampling area to the bottom of the PIPS detector (8), and press the filter paper again. The entire paper feeding process is controlled within 1 minute; ③ Sampling, emanation and daughter measurement: carry out synchronous sampling radon / thoron measurement and radon / thoron daughter measurement, first open the second and third valves (23, 24), close the first valve (22), then control the vacuum pump (21) to evacuate the vacuum chamber of the radon / thoron daughter measurement unit, make the vacuum degree less than 1kPa within 30 seconds, and maintain it during the operation of the vacuum pump (21), synchronously start the sampling pump (27), collect aerosol particles with a particle size of less than 1μm on the filter paper, and synchronously start the sampling pump (27) to collect aerosol particles with a particle size of less than 1μm on the emanation measurement unit. A voltage of 2000V is applied to the inner wall of the measuring chamber, and the radiant meter (28) in the radon / thoron measuring unit is started for measurement. Then, the PIPS detector in the radon / thoron daughter measuring unit is started to measure the α energy spectrum. After sampling, the sampling pump (27) and the vacuum pump (21) are turned off, the high pressure in the radiant measuring chamber is reduced, and the radiant and daughter measurements are stopped. Then, the second and third valves (23, 24) are closed, and the above steps ② and ③ are repeated to start the synchronous continuous measurement method of radon / thoron and its daughters.

5. The high-resolution combined measurement device for radon, thoron and their daughters according to claim 1 is characterized by: A filter paper travel switch (17) is provided on the side of the filter paper roll driven wheel (3).

6. The high-resolution combined measurement device for radon, thoron and their daughters according to claim 1 is characterized by: Two symmetrical eccentric wheel travel switches (16) are respectively arranged on both sides of the eccentric wheel (14).

7. The high-resolution combined measurement device for radon, thoron and their daughters according to claim 1 is characterized in that: The outer end surface of the eccentric wheel (14) is provided with a wheel disc (31), the center of which is concentric with the axis of the driving motor, and a contact matched with the eccentric wheel travel switch (16) is provided on the surface of the wheel disc (31).

8. The high-resolution combined measurement device for radon, thoron and their daughters according to claim 1 is characterized by: The structure of the emanation meter (28) is that a hemispherical measuring chamber (32) is formed by a stainless steel plate and fixedly connected to an electrical bakelite board (36); an isolation cover (33) made of organic glass is arranged outside the measuring chamber (32); an air inlet (34) interface arranged at the top of the measuring chamber (32) is located outside the isolation cover (33); a through hole and a detection port are arranged on the electrical bakelite board (36) located in the measuring chamber (32); a temperature and humidity sensor (35) is installed on the through hole; a gold silicon surface barrier detector (29) is installed on the detection port; and a high voltage head (37) is installed on the electrical bakelite board (36) located between the measuring chamber (32) and the isolation cover (33).

9. The high-resolution combined measurement device for radon, thoron and their daughters according to claim 1, 5, 6, 7 or 8, characterized in that: PI The PS detector (8), the gold silicon surface barrier detector (29), the sampling pump (27), the vacuum pump (21), the paper feeding motor, the tensioning motor, the filter paper travel switch (17), the eccentric wheel travel switch (16), the temperature and humidity sensor (35), and the pressure sensor (20) are all connected to the control system (30) through wires.

10. The high-resolution combined measurement device for radon, thoron and their daughters according to claim 1 is characterized by: The spring (12) is composed of a compression spring. The lower ends of the two springs (12) are respectively fixed on the fixed support. The upper ends of the two springs (12) are respectively matched with the back sides of the disc-shaped upper pressing platforms of the left and right pressing devices (10, 11).

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