A portable real-time radioactive xenon monitor and monitoring method

Abstract

The present invention discloses a portable real-time radioactive xenon monitor and monitoring method to address the issues of traditional xenon systems taking a long time to process low-activity concentration gas samples and easily causing cross-contamination when processing high-activity concentration gas samples. Specifically, the system comprises an air compressor, a buffer tank, a water phase separator, and a hollow fiber membrane assembly, which are connected in sequence; a radon removal column, an adsorption column, a balance column, and a detector. The sewage discharge ends of the buffer tank and the water phase separator are integrated into an integrated pipeline, which is equipped with a sewage valve. The output end of the hollow fiber membrane assembly is divided into two pipelines. The first pipeline is connected to one end of the adsorption column through the third valve, the balance column, and the seventh valve in sequence, and the second pipeline is connected to the other end of the adsorption column through the first valve, the sixth valve, and the radon removal column in sequence. Branch pipelines are connected in parallel between the sixth valve and both ends of the radon removal column. The adsorption column is bent into a snail shape and placed on the probe of the detector. The detector is used to detect the activity of radioactive xenon adsorbed by the adsorption column.

Description

Technical Field

[0001] The present invention relates to a radioactive xenon monitor, in particular to a portable real-time radioactive xenon monitor and a monitoring method. Background Art

[0002] Radioactive xenon isotopes are characteristic fission products with high yields and moderate half-lives. They can be identified and quantified, and have a sensitive indication and early warning function for understanding abnormal radioactivity in the air. 133 Xe activity concentration increases, for 1Bq / m 3 ~10 2 Bq / m 3 For high-activity samples, measurements can only be performed using a xenon system. However, traditional xenon systems take a long time to provide data results, are not very timely, and cannot respond quickly enough, hindering the timely implementation of emergency response measures by relevant departments. Moreover, traditional xenon systems are prone to cross-contamination when processing high-activity concentration gas samples, which often leads to misjudgment. Therefore, a new method for online, real-time measurement of radioactive xenon is urgently needed. Summary of the Invention

[0003] The purpose of the present invention is to provide a portable real-time radioactive xenon monitor and monitoring method to solve the technical problems that traditional xenon systems take a long time to process low-activity concentration gas samples, cannot respond as soon as possible, and are prone to cross contamination when processing high-activity concentration gas samples, leading to misjudgment.

[0004] In order to achieve the above object, the present invention provides a portable real-time radioactive xenon monitor, which is special in that it includes an air compressor, a buffer tank, a water phase separator, a hollow fiber membrane assembly, a radon removal column, an adsorption column, a balance column and a detector;

[0005] The air compressor is connected to the input end of the water phase separator through a buffer tank;

[0006] The output end of the water phase separator is connected to the input end of the hollow fiber membrane assembly;

[0007] The sewage discharge end of the buffer tank and the water phase separator is integrated into an integrated pipeline, and a sewage discharge valve is provided on the integrated pipeline;

[0008] The output end of the hollow fiber membrane module is divided into two pipelines, the first pipeline is connected to one end of the adsorption column through the third valve, the balance column and the seventh valve in sequence, and the second pipeline is connected to the other end of the adsorption column through the first valve, the sixth valve and the radon removal column in sequence;

[0009] The radon removal column and the balance column have the same size;

[0010] A branch pipeline is connected in parallel to both ends of the sixth valve and the radon removal column, and a first exhaust pipe and a fifth valve are provided on the branch pipeline; the first exhaust pipe is provided on the side of the sixth valve away from the radon removal column; and an eighth valve is provided on the first exhaust pipe;

[0011] A second exhaust pipe is provided on the pipeline between the seventh valve and the adsorption column; a tenth valve is provided on the second exhaust pipe; a third exhaust pipe is provided on the pipeline on the side of the balance column away from the seventh valve; a ninth valve is provided on the third exhaust pipe;

[0012] The adsorption column is bent into a snail shape and placed on the probe of the detector, and the detector is used to detect the activity of the radioactive xenon adsorbed by the adsorption column.

[0013] Furthermore, it also includes a first pipeline filter, a second pipeline filter, a third pipeline filter, a fourth pipeline filter and a fifth pipeline filter;

[0014] The first pipeline filter is installed at the input end of the air compressor;

[0015] The second pipeline filter is installed on the pipeline between the water phase separator and the hollow fiber membrane assembly;

[0016] The third pipe filter is installed at the pipe mouth of the first exhaust pipe;

[0017] The fourth pipe filter is installed at the pipe mouth of the second exhaust pipe;

[0018] The fifth pipe filter is installed at the pipe opening of the third exhaust pipe.

[0019] Furthermore, it also includes a mass flow meter, a first mass flow controller and a second mass flow controller;

[0020] The mass flow meter is arranged on the pipeline between the water phase separator and the hollow fiber membrane assembly;

[0021] The first mass flow controller is disposed on the first pipeline and is located between the third valve and the third exhaust pipe;

[0022] The second mass flow controller is disposed on the second pipeline and located between the sixth valve and the first valve.

[0023] Furthermore, it also includes a temperature sensor, a first pressure sensor, a second pressure sensor and a third pressure sensor;

[0024] The temperature sensor is arranged close to the adsorption column and is used to monitor the temperature of the adsorption column in real time;

[0025] The first pressure sensor is arranged on the pipeline at the output end of the hollow fiber membrane module;

[0026] The second pressure sensor is arranged on the pipeline between the mass flow meter and the input end of the hollow fiber membrane module;

[0027] The third pressure sensor is arranged on the pipeline between the seventh valve and the adsorption column.

[0028] Furthermore, it also includes a second valve and a fourth valve;

[0029] The second valve is disposed on the second pipeline and is located on a side of the second mass flow controller away from the first valve;

[0030] The fourth valve is disposed on the first pipeline and located between the first mass flow controller and the third exhaust pipe.

[0031] Further, it also includes a control mechanism;

[0032] The first to tenth valves and the drain valve are all solenoid valves;

[0033] The air compressor, the first valve to the tenth valve, the drain valve, the temperature sensor, the first pressure sensor to the third pressure sensor, the mass flow meter, the first mass flow controller, the second mass flow controller and the detector are all electrically connected to the control mechanism.

[0034] Furthermore, the adsorption column, radon removal column and equilibrium column are all filled with the same type of carbon molecular sieve adsorbent.

[0035] Furthermore, the adsorption column, radon removal column and equilibrium column are all made of a copolymer of perfluoropropyl perfluorovinyl ether and polytetrafluoroethylene;

[0036] The hollow fiber membrane assembly includes four hollow fiber membrane columns connected in series;

[0037] The detector is a cadmium zinc telluride detector.

[0038] The present invention also provides a method for monitoring radioactive xenon, based on the above-mentioned portable real-time radioactive xenon monitor, for monitoring surface gas, which is special in that it includes the following steps:

[0039] Step 1: Close the third valve, the sixth valve, the seventh valve, and the eighth valve; open the first valve, the fifth valve, and the tenth valve;

[0040] Step 2: Surface gas is sucked in by an air compressor and passes through a buffer tank, a water phase separator, and a hollow fiber membrane module for dust removal, water removal, and removal of impurities. It then passes through a fifth valve and enters an adsorption column, where xenon components are concentrated. Other gases are discharged through a second exhaust pipe.

[0041] Step 3: The detector detects the radioactivity of the xenon component enriched on the adsorption column in real time.

[0042] The present invention also provides another method for monitoring radioactive xenon, based on the above-mentioned portable real-time radioactive xenon monitor, for monitoring subsurface gas, which is special in that it includes the following steps:

[0043] Step 1: Close the third valve, the fifth valve, the eighth valve, and the tenth valve, and open the first valve, the sixth valve, the seventh valve, and the ninth valve;

[0044] Step 2: Subsurface gas is sucked in by an air compressor and passes through a buffer tank, a water phase separator, and a hollow fiber membrane module for dust removal, water removal, and removal of impurities. It then passes through a radon removal column to remove radon before entering an adsorption column where xenon components are concentrated. Other gases enter a balance column, which is activated and regenerated before being discharged from a third exhaust pipe.

[0045] Step 3: When the radon removal column is saturated with radon gas, the first valve, the fifth valve, the ninth valve, and the tenth valve are closed, and the third valve, the seventh valve, the sixth valve, and the eighth valve are opened; the gas output from the hollow fiber membrane module passes through the balance column to remove radon gas, and then enters the adsorption column, where the xenon component is enriched. The remaining gas enters the radon removal column to activate and regenerate the radon removal column, and is then discharged from the first exhaust pipe;

[0046] Step 4: When the equilibrium column is saturated with radon gas, repeat steps 1 to 3. At the same time, the detector detects the radioactivity of the xenon component enriched on the adsorption column in real time.

[0047] Beneficial effects of the present invention:

[0048] 1. The present invention uses an adsorption column to adsorb xenon components. The adsorption column is arranged in a snail shape and placed on the detection surface of the detector. The detector measures the radioactivity of the xenon component in real time. It has strong timeliness and can respond promptly when the radioactivity of the xenon component exceeds the threshold. At the same time, a radon removal column and a balance column are used to remove radioactive radon gas from the gas, thereby preventing the influence of radioactive radon gas on the measurement of the radioactivity of the xenon component and thus avoiding misjudgment of the measurement results.

[0049] 2. The present invention arranges the radon removal column and the balance column on both sides of the adsorption column. The gas flow direction can be controlled by each solenoid valve. After the radon removal column and the balance column are saturated with radon gas, they can be activated and regenerated to achieve continuous real-time monitoring of the radioactivity of the xenon component.

[0050] 3. The present invention fills the gap between the activity concentration of radioactive xenon isotopes and the range of 1 to 10 2 Bq / m 3 The gap in real-time monitoring within.

[0051] 4. The portable real-time radioactive xenon monitor provided by the present invention has a simple structure, few modules, plug-and-play, easy operation, simple maintenance, light weight (less than 50 kg), and strong field adaptability.

[0052] 5. The portable real-time radioactive xenon monitor of the present invention is also provided with a mass flow meter, a mass flow controller, a pressure sensor and a temperature sensor, which can adjust the entire device according to the external environment and the detection results of the detector to improve its adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The figure is a schematic structural diagram of an embodiment of a portable real-time radioactive xenon monitor of the present invention.

[0054] Figure Number:

[0055] 1-air compressor, 2-buffer tank, 3-water phase separator, 4-hollow fiber membrane assembly, 5-radon removal column, 6-adsorption column, 7-balance column, 8-detector, 9-first exhaust pipe, 10-second exhaust pipe, 11-third exhaust pipe, 12-first pipeline filter, 13-second pipeline filter, 14-third pipeline filter, 15-fourth pipeline filter, 16-fifth pipeline filter, 17-mass flow meter, 18-first mass flow controller, 19-second mass flow controller, 20-temperature sensor, 21-first pressure sensor, 22-second pressure sensor, 23-third pressure sensor, 24-control mechanism;

[0056] 01-first valve, 02-second valve, 03-third valve, 04-fourth valve, 05-fifth valve, 06-sixth valve, 07-seventh valve, 08-eighth valve, 09-ninth valve, 010-tenth valve, 011-drain valve. DETAILED DESCRIPTION

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0058] The principles of the present invention are as follows:

[0059] For radioactive xenon isotope activity concentration monitoring equipment, in order to determine its applicable range, its characterization parameter is the minimum detectable activity concentration (MDC). MDC is a comprehensive system performance indicator, which is related to the minimum detectable activity (MDA) of the monitoring equipment, the recovery rate and the sampling volume. The calculation formula is as follows:

[0060]

[0061] Wherein, R is the recovery rate of the whole process of the equipment (unit is %); V F is the sampling (or raw gas) volume (unit: m 3 ), V P The volume of the measured (or product gas) (in L or m 3 ), E m is the membrane enrichment factor. In formula (1), the sampling volume is determined by the sampling flow rate and time, the MDA is determined by the performance of the radioactivity measurement device and the radon removal coefficient in the xenon system, the recovery rate and the measurement (or product gas) volume are determined by the separation performance of the hollow fiber membrane, the amount of carbon molecular sieve is determined by the measurement (or product gas) volume, and the radon removal coefficient is determined by the hollow fiber membrane assembly and the radon removal column.

[0062] (1) Hollow fiber membrane separation technology

[0063] The basic principle of membrane separation is that the transmission rate of each component in the mixed gas through the membrane is different under the pressure, so as to achieve the purpose of component separation. After the gas passes through the hollow fiber membrane, the feed gas flow rate or volume (F F or V F ) is equal to the permeate flow rate or volume (F E or V E ) and product gas flow or volume (F P or V P )The sum of the two, that is, (F F =F P +F E or V F =V P +V E The ratio of product gas to feed gas flow rate or volume is defined as membrane enrichment multiple (E m ), the calculation formula is:

[0064]

[0065] Recovery rate (R i ) can be used to comprehensively reflect the yield and loss of xenon (and radon) components in the process of hollow fiber membrane gas separation. The calculation formula is:

[0066]

[0067] Where C Piand C Fi are the concentrations of component i in the product gas and raw gas, respectively.

[0068] (2) Carbon molecular sieve adsorption separation technology

[0069] The xenon component in the hollow fiber membrane product gas is further enriched after adsorption on the carbon molecular sieve to prepare a sample for measurement. Dynamic adsorption coefficient (k d ) is used to characterize the adsorption efficiency of the adsorbate (xenon) on the adsorbent (carbon molecular sieve). The calculation formula is as follows:

[0070]

[0071] Where, W is the mass of carbon molecular sieve, g; t is the adsorption or sampling time, in min; V F and V p They are sampling volume and adsorption (product gas volume) volume respectively, and the unit is L.

[0072] Pre-test the dynamic adsorption coefficient k by experiment d , according to the mass W of the carbon molecular sieve and the membrane enrichment multiple E m And the sampling (raw gas) flow rate F during equipment operation F Determine the sampling time t and sampling volume V F and adsorption (product gas volume) volume V p , used for activity concentration result calculation.

[0073] (3) Total enrichment multiples of the equipment

[0074] The total enrichment factor of the device is the product of the membrane and adsorption enrichment factors. m Use formula (2) to calculate. The carbon molecular sieve is packed in the adsorption column. The column is usually made of 1 / 4" diameter or other types of pipes. The adsorption volume (product gas volume) V p The ratio of the volume of the adsorption column is called the adsorption enrichment factor.

[0075] (4) Cadmium zinc telluride (CdZnTe / CZT) detector measurement technology

[0076] CZT detectors have a high average atomic number and are highly efficient at detecting low-energy X-rays and gamma rays. The energy of Xe and its isotope decay radiation is primarily concentrated below 300 keV. These detectors require no cooling, are relatively simple to shield, and are lightweight and portable. We designed and fabricated a cadmium zinc telluride (CZT) array detector to measure the activity of radioactive xenon isotopes. We measured the energy and efficiency calibration of the xenon isotopes to determine the mean average density (MDA) and obtain the system's mean density (MDC).

[0077] The calculation formula for minimum detectable activity (MDA) is:

[0078]

[0079] L D N is the detection limit of counts at 95% confidence level. b is the background area of ​​the background energy region of interest within the measurement time Δt, in counts; ε is the detection efficiency of the instrument measuring the sample; P γ is the branching ratio of gamma rays, corresponding to the four xenon isotopes 131m Xe (29.7keV), 133m Xe (29.7keV), 133 Xe(81.0keV) and 135 For Xe (249.8 keV), the values ​​are 43.9%, 45.7%, 37% and 90.1% respectively; Δt is the time it takes for the γ spectrometer to measure the sample, in seconds.

[0080] The embodiment of the present invention provides a portable real-time radioactive xenon monitor and monitoring method for monitoring low-level radioactive xenon isotopes ( 131m,133m,133,135 Xe) activity concentration. Figure 1 As shown, it includes an air compressor 1, a buffer tank 2, a water phase separator 3, a hollow fiber membrane assembly 4, a radon removal column 5, an adsorption column 6, a balance column 7, a detector 8, a first mass flow controller 18, a second mass flow controller 19, a first pressure sensor 21, a second pressure sensor 22, a third pressure sensor 23, a temperature sensor 20 and a control mechanism 24; wherein the hollow fiber membrane assembly 4 includes four hollow fiber membrane columns connected in series; the detector 8 is a cadmium zinc telluride detector.

[0081] The air compressor 1 is connected to the input end of the water phase separator 3 through the buffer tank 2; a first pipeline filter 12 is installed at the input end of the air compressor 1; the output end of the water phase separator 3 is connected to the input end of the hollow fiber membrane assembly 4; a second pipeline filter 13 and a mass flow meter 17 are installed on the pipeline between the water phase separator 3 and the hollow fiber membrane assembly 4; the sewage discharge end of the buffer tank 2 and the water phase separator 3 are combined into an integrated pipeline, and a sewage valve 011 is provided on the integrated pipeline; the output end of the hollow fiber membrane assembly 4 is divided into two pipelines, the first pipeline is connected to one end of the adsorption column 6 through the third valve 03, the balance column 7 and the seventh valve 07 in sequence, and the second pipeline is connected to the other end of the adsorption column 6 through the first valve 01, the sixth valve 06 and the radon removal column 5 in sequence;

[0082] The radon removal column 5 and the balance column 7 are identical in size; the adsorption column 6, radon removal column 5, and balance column 7 are all loaded with the same type of carbon molecular sieve adsorbent. Based on the ratio of the dynamic adsorption coefficients of xenon and radon (1 / 3) and the adsorption column loading (see below), the radon removal column (balance column) loading is calculated to be 4.2 g, corresponding to a volume of 10 mL. To achieve a specific column length, a 1 / 4" polytetrafluoroethylene (PTFE) or a copolymer of perfluoropropyl perfluorovinyl ether and PTFE (PFA tubing) with an inner diameter of 4.78 mm and a height of 56 cm is selected. There are no specific requirements for the shape of the radon removal column and balance column.

[0083] A branch pipeline is connected in parallel to both ends of the sixth valve 06 and the radon removal column 5. The branch pipeline is provided with a first exhaust pipe 9 and a fifth valve 05. The first exhaust pipe 9 is provided on the side of the sixth valve 06 away from the radon removal column 5. An eighth valve 08 is provided on the first exhaust pipe 9. A third pipe filter 14 is installed at the mouth of the first exhaust pipe 9 to prevent external impurity gases from entering the monitor and affecting the monitoring results.

[0084] A second exhaust pipe 10 is provided on the pipeline between the seventh valve 07 and the adsorption column 6; a tenth valve 010 is provided on the second exhaust pipe 10; a fourth pipe filter 15 is installed at the pipe mouth of the second exhaust pipe 10, which is also used to prevent external impurities from entering the monitor and affecting the monitoring results;

[0085] A third exhaust pipe 11 is provided on the pipeline on the side of the balance column 7 away from the seventh valve 07; a ninth valve 09 is provided on the third exhaust pipe 11; and a fifth pipe filter 16 is installed at the mouth of the third exhaust pipe 11 to prevent foreign gases from entering the monitor and affecting the monitoring results.

[0086] Adsorption column 6 is made of a copolymer of perfluoropropyl perfluorovinyl ether and polytetrafluoroethylene (PFA tubing), a flexible material filled with carbon molecular sieve. Bendable into a snail shape, it is placed on the probe of detector 8, which detects the activity of radioactive xenon adsorbed by column 6. For an 80 mm diameter probe, 3 / 8" PFA tubing (9.525 mm outer diameter, 1.575 mm wall thickness) is used. The inner and outer coils are formed into four turns, with curving diameters of 75, 60, 40, and 25 mm, respectively. The total length is approximately (75 + 60 + 40 + 25) mm × 3.14 = 63 cm, with a volume of approximately 31 mL. With an adsorbent packing density of approximately 0.40 g / mL, the calculated loading is approximately 12.5 g.

[0087] The temperature sensor 20 is provided near the adsorption column 6 and is used to monitor the temperature of the adsorption column 6 in real time;

[0088] The first mass flow controller 18 is provided on the first pipeline and is located between the third valve 03 and the third exhaust pipe 11; the second mass flow controller 19 is provided on the second pipeline and is located between the sixth valve 06 and the first valve 01. The first pressure sensor 21 is provided on the pipeline at the output end of the hollow fiber membrane assembly 4; the second pressure sensor 22 is provided on the pipeline between the mass flow meter 17 and the input end of the hollow fiber membrane assembly 4; the third pressure sensor 23 is provided on the pipeline between the seventh valve 07 and the adsorption column 6. A fourth valve 04 is also provided on the first pipeline, and the fourth valve 04 is located between the first mass flow controller 18 and the third exhaust pipe 11. A second valve 02 is also provided on the second pipeline, and the second valve 02 is located on the side of the second mass flow controller 19 away from the first valve 01;

[0089] The first to tenth valves and the drain valve are all solenoid valves; the first valve 01 to the tenth valve 010, the drain valve 011, the air compressor 1, the temperature sensor 20, the first pressure sensor 21 to the third pressure sensor 23, the mass flow meter 17, the first mass flow controller 18, the second mass flow controller 19 and the detector 8 are all electrically connected to the control mechanism 24.

[0090] The portable real-time radioxenon monitor provided by an embodiment of the present invention can be divided into three units: processing, measurement, and control. The processing unit primarily consists of an air compressor 1, a buffer tank 2, an aqueous phase separator 3, a mass flow meter 17, a hollow fiber membrane assembly 4, a second pressure sensor 22, a first mass flow controller 18, a second mass flow controller 19, a radon removal column 5, a balance column 7, an adsorption column 6, and associated valves. The measurement unit comprises a cadmium zinc telluride detector 8 and a temperature sensor 20, and the control mechanism primarily includes a display screen, a programmable logic controller (PLC), and a printer. The monitor comprises two modules, all of which are integrated into a single module, except for the 1kW battery, which is a separate module. The display screen and printer are mounted on the front panel, the hollow fiber membrane is mounted within the housing near the rear panel, the detector and control PLC are mounted on the right front of the housing, and the air compressor and buffer tank are mounted on the left front of the housing. Components and valves can be mounted above these. A fan is installed on each of the four sides of the housing, and the housing is hollowed out. The monitor continuously enriches the xenon components in a certain volume of gas through hollow fiber membranes and carbon molecular sieves, and uses a cadmium zinc telluride detector for real-time measurement, achieving the purpose of rapid response and real-time monitoring of radioactive xenon isotopes in the ambient air. It improves the detection limit and sensitivity of the cadmium zinc telluride detector when used alone, and has strong environmental adaptability.

[0091] After a nuclear power plant accident or nuclear incident, the inert gas xenon isotopes produced by fission are easy to diffuse and leak, resulting in an increase in activity concentration in the environment. Different radioactive xenon isotope activity concentrations require different monitoring equipment and measurement methods, including aviation, vehicle-mounted, on-site, OSI xenon systems, and station-based xenon systems. 133 The minimum detectable concentration (MDC) of Xe is 10 4 ~10 5 Bq / m 3 , 10 3 Bq / m 3 , 10 2 Bq / m 3 , 10 -3 Bq / m 3 and 10 -4 Bq / m 3 The first three devices can realize real-time measurement of samples, while the latter two devices cannot realize real-time measurement. The monitor provided by the present invention fills the range of radioactive xenon isotope activity concentration of 1 to 10 2 Bq / m 3 Real-time monitoring gaps.

[0092] The operation process is as follows:

[0093] For gases from two different sources, surface gas and subsurface gas, there are two process operation modes: no radon removal and radon removal.

[0094] Operation without radon removal process:

[0095] For surface gas, the radon activity concentration is relatively low, so there is no need to use a radon removal column or equilibrium column. After separation by the hollow fiber membrane module, the product gas directly enters the adsorption column to achieve continuous measurement. The specific operation steps are as follows:

[0096] Step 1: Power on the monitor, close the third valve 03, the fourth valve 04, the sixth valve 06, the seventh valve 07, the eighth valve 08, and the ninth valve 09 through the control mechanism, and open the air compressor 1, the first valve 01, the second valve 02, the fifth valve 05, and the tenth valve 010;

[0097] Step 2: Surface gas is sucked in by the air compressor 1, passes through the buffer tank 2 and the water phase separator 3 to remove most of the dust and water, and then passes through the second pipeline filter 13 to remove dust again. After the gas flow rate is recorded by the mass flow meter 17, it passes through the hollow fiber membrane module to separate and remove a large amount of impurity gases (O2, N2, CO2, and H2O). Then, it passes through the fifth valve 05 and enters the adsorption column 6. The xenon component with strong adsorption capacity is enriched in the adsorption column 6, and other constant components with weak adsorption capacity (N2 and O2) are discharged through the second exhaust pipe 10.

[0098] Step 3: Detector 8 monitors the radioactivity of the xenon component accumulated on adsorption column 6 in real time. Measurement stops and the result is displayed after the xenon penetrates the adsorption column. Temperature sensor 20 records the adsorption column temperature, while first, second, and third pressure sensors 21, 22, and 23 record the gas pressure at different locations in the pipeline.

[0099] Radon removal process operation:

[0100] For underground gas, the radon activity concentration is very high, and radon removal columns and balance columns are required. The operation mode can be divided into measurement and regeneration alternating operation modes. The specific operation steps are as follows:

[0101] Step 1: Power on the monitor, close the third valve 03, the fourth valve 04, the fifth valve 05, the eighth valve 08, and the tenth valve 010 through the control mechanism, and open the air compressor 1, the first valve 01, the second valve 02, the sixth valve 06, the seventh valve 07, and the ninth valve 09;

[0102] Step 2: Subsurface gas is sucked in by air compressor 1, passes through buffer tank 2 and water phase separator 3 to remove most of the dust and water, then enters hollow fiber membrane module 4 to remove a large amount of impurity gases (O2, N2, CO2 and H2O), then passes through radon removal column 5 to remove radon, and then enters adsorption column 6. Xenon components are enriched in adsorption column 6, and other constant components (N2 and O2) enter balance column 7. After activation and regeneration of balance column 7, the gas is discharged from third exhaust pipe 11.

[0103] Step 3: When the radon removal column 5 is saturated with radon gas, close the first valve 01, the second valve 02, the fifth valve 05, the ninth valve 09, and the tenth valve 010, and open the third valve 03, the fourth valve 04, the seventh valve 07, the sixth valve 06, and the eighth valve 08; the gas output from the hollow fiber membrane assembly 4 is removed from the radon gas through the balance column 7, and then enters the adsorption column 6, where the xenon component is enriched. The other gases enter the radon removal column 5 to activate and regenerate the radon removal column 5, and are then discharged from the first exhaust pipe 9; the air flow rate can be increased in the regeneration mode;

[0104] Step 4: When equilibrium column 7 is saturated with radon gas, alternating testing and regeneration are achieved. Steps 1 through 3 are repeated. Simultaneously, detector 8 detects the radioactivity of the xenon component accumulated on adsorption column 8 in real time. Measurement ceases after the xenon penetrates the column, and the result is transmitted to the control mechanism for display on the control mechanism's screen. Simultaneously, temperature sensor 20 records the adsorption column temperature, and first, second, and third pressure sensors 21, 22, and 23 record the gas pressure at various locations in the pipeline.

[0105] This monitoring method is based on the design of a continuous measurement process mode and fully utilizes the advantages of hollow fiber membrane columns and carbon molecular sieves in xenon separation and enrichment, which can achieve a xenon enrichment factor of 10. 3 At the same time, the better energy resolution and environmental adaptability of the CdZnTe detector can realize real-time monitoring of radioactive xenon activity concentration. It is expected that the minimum detectable activity concentration (MDC) of the entire device can reach 1Bq / m 3 The device has low power consumption, is lightweight, easy to use and operate, and has strong field adaptability. It is very suitable for monitoring radioactive xenon isotopes in environments such as inside and around nuclear power plants, after nuclear accidents, and during on-site inspections. It has a broad application market and prospects.

[0106] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention shall be covered by the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A portable real-time radioxenon monitor, characterized by: It comprises an air compressor (1), a buffer tank (2), a water phase separator (3), a hollow fiber membrane assembly (4), a radon removal column (5), an adsorption column (6), a balance column (7), and a detector (8); The air compressor (1) is connected to the input end of the water phase separator (3) via a buffer tank (2); The output end of the water phase separator (3) is connected to the input end of the hollow fiber membrane assembly (4); The sewage discharge ends of the buffer tank (2) and the water phase separator (3) are combined into an integrated pipeline, and a sewage discharge valve (011) is provided on the integrated pipeline; The output end of the hollow fiber membrane assembly (4) is divided into two pipelines, the first pipeline is connected to one end of the adsorption column (6) through the third valve (03), the balance column (7) and the seventh valve (07) in sequence, and the second pipeline is connected to the other end of the adsorption column (6) through the first valve (01), the sixth valve (06) and the radon removal column (5) in sequence; The radon removal column (5) and the balance column (7) have the same size; A branch pipeline is connected in parallel to both ends of the sixth valve (06) and the radon removal column (5), and a first exhaust pipe (9) and a fifth valve (05) are provided on the branch pipeline; the first exhaust pipe (9) is provided on a side of the sixth valve (06) away from the radon removal column (5); and an eighth valve (08) is provided on the first exhaust pipe (9); A second exhaust pipe (10) is provided on the pipeline between the seventh valve (07) and the adsorption column (6); a tenth valve (010) is provided on the second exhaust pipe (10); a third exhaust pipe (11) is provided on the pipeline on the side of the balance column (7) away from the seventh valve (07); a ninth valve (09) is provided on the third exhaust pipe (11); The adsorption column (6) is bent into a snail shape and placed on the probe of the detector (8), and the detector (8) is used to detect the activity of the radioactive xenon adsorbed by the adsorption column (6); The adsorption column (6), radon removal column (5) and balance column (7) are all made of a copolymer of perfluoropropyl perfluorovinyl ether and polytetrafluoroethylene; The hollow fiber membrane assembly (4) comprises four hollow fiber membrane columns connected in series; The detector (8) is a cadmium zinc telluride detector.

2. The portable real-time radioxenon monitor according to claim 1, characterized in that: It also includes a first pipeline filter (12), a second pipeline filter (13), a third pipeline filter (14), a fourth pipeline filter (15) and a fifth pipeline filter (16); The first pipeline filter (12) is installed at the input end of the air compressor (1); The second pipeline filter (13) is installed on the pipeline between the water phase separator (3) and the hollow fiber membrane assembly (4); The third pipe filter (14) is installed at the pipe opening of the first exhaust pipe (9); The fourth pipe filter (15) is installed at the pipe opening of the second exhaust pipe (10); The fifth pipe filter (16) is installed at the pipe opening of the third exhaust pipe (11).

3. The portable real-time radioxenon monitor according to claim 1 or 2, characterized in that: Also includes a mass flow meter (17), a first mass flow controller (18) and a second mass flow controller (19); The mass flow meter (17) is arranged on the pipeline between the water phase separator (3) and the hollow fiber membrane assembly (4); The first mass flow controller (18) is arranged on the first pipeline and is located between the third valve (03) and the third exhaust pipe (11); The second mass flow controller (19) is arranged on the second pipeline and is located between the sixth valve (06) and the first valve (01).

4. The portable real-time radioxenon monitor according to claim 3, characterized in that: It also includes a temperature sensor (20), a first pressure sensor (21), a second pressure sensor (22), and a third pressure sensor (23); The temperature sensor (20) is arranged close to the adsorption column (6) and is used to monitor the temperature of the adsorption column (6) in real time; The first pressure sensor (21) is arranged on the pipeline at the output end of the hollow fiber membrane assembly (4); The second pressure sensor (22) is arranged on a pipeline between the mass flow meter (17) and the input end of the hollow fiber membrane assembly (4); The third pressure sensor (23) is arranged on the pipeline between the seventh valve (07) and the adsorption column (6).

5. The portable real-time radioxenon monitor according to claim 4, characterized in that: Also includes a second valve (02) and a fourth valve (04); The second valve (02) is arranged on the second pipeline and is located on a side of the second mass flow controller (19) away from the first valve (01); The fourth valve (04) is arranged on the first pipeline and is located between the first mass flow controller (18) and the third exhaust pipe (11).

6. The portable real-time radioxenon monitor according to claim 5, characterized in that: Also included is a control mechanism (24); The first valve (01) to the tenth valve (010) and the drain valve (011) are all solenoid valves; The air compressor (1), the first valve (01) to the tenth valve (010), the drain valve (011), the temperature sensor (20), the first pressure sensor (21) to the third pressure sensor (23), the mass flow meter (17), the first mass flow controller (18), the second mass flow controller (19) and the detector (8) are all electrically connected to the control mechanism (24).

7. A method for monitoring radioactive xenon, based on the portable real-time radioactive xenon monitor according to any one of claims 1 to 6, for monitoring surface gas, characterized in that: The following steps are involved: Step 1: Close the third valve (03), the sixth valve (06), the seventh valve (07), and the eighth valve (08); and open the first valve (01), the fifth valve (05), and the tenth valve (010); Step 2: Surface gas is sucked in by the air compressor (1), and sequentially passes through the buffer tank (2), the water phase separator (3), and the hollow fiber membrane assembly (4) for dust removal, water removal, and removal of impurity gases. The gas then passes through the fifth valve (05) and enters the adsorption column (6). The xenon component is concentrated on the adsorption column (6), and the other gases are discharged through the second exhaust pipe (10); Step 3: The detector (8) detects the radioactivity of the xenon component enriched on the adsorption column (6) in real time.

8. A method for monitoring radioactive xenon, based on the portable real-time radioactive xenon monitor according to any one of claims 1 to 6, for monitoring subsurface gas, characterized in that: The following steps are involved: Step 1: Close the third valve (03), the fifth valve (05), the eighth valve (08) and the tenth valve (010), and open the first valve (01), the sixth valve (06), the seventh valve (07) and the ninth valve (09); Step 2: Subsurface gas is sucked in by an air compressor (1), and sequentially passes through a buffer tank (2), a water phase separator (3), and a hollow fiber membrane assembly (4) for dust removal, water removal, and removal of impurity gases. The gas then passes through a radon removal column (5) to remove radon gas, and then enters an adsorption column (6). Xenon components are concentrated on the adsorption column (6), and other gases enter a balance column (7). The balance column (7) is activated and regenerated, and then discharged from a third exhaust pipe (11); Step 3: When the radon removal column (5) is saturated with adsorbed radon gas, the first valve (01), the fifth valve (05), the ninth valve (09), and the tenth valve (010) are closed, and the third valve (03), the seventh valve (07), the sixth valve (06), and the eighth valve (08) are opened; the gas output from the hollow fiber membrane assembly (4) is removed from the radon gas by the balance column (7), and then enters the adsorption column (6), and the xenon component is enriched on the adsorption column (6); the other gases enter the radon removal column (5), activate and regenerate the radon removal column (5), and are then discharged from the first exhaust pipe (9); Step 4: When the equilibrium column (7) is saturated with radon gas, steps 1 to 3 are repeated. Meanwhile, the detector (8) detects the radioactivity of the xenon component accumulated on the adsorption column (6) in real time.

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