A radon Rn222 measurement chamber for calibrating a radon detector and a test method thereof

Abstract

The present application relates to the field of radon Rn222 measurement, and particularly to a radon measuring instrument calibration radon Rn222 measuring chamber and a testing method thereof. The radon measuring instrument calibration radon Rn222 measuring chamber comprises a sealed chamber, a radium chloride 226 decay chamber arranged in the sealed measuring chamber and provided with a decay chamber to release radon Rn222 by radioactive decay of radium chloride 226, an air inlet hole and an air outlet hole arranged at two ends of the radium chloride 226 decay chamber respectively, a radon measuring instrument assembly arranged at one end of the radium chloride 226 decay chamber and connected with the air outlet hole, the radon measuring instrument assembly being provided with a plurality of radon measuring instruments to measure radon Rn222 released by radioactive decay of radium chloride 226, and an air inlet assembly. The present application realizes functional integration through modular design, solves the problems of dispersed structure and complex operation of traditional calibration equipment, breaks through the bottleneck of single-channel efficiency through parallel measurement of multiple radon measuring instruments, meets the batch calibration demand, and guarantees stable radon concentration through linkage of the air inlet assembly and the decay chamber, thereby laying a foundation for high-precision calibration.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radon Rn222 measurement, in particular to a radon Rn222 measurement room for calibrating a radon detector and a test method thereof. BACKGROUND

[0002] Radon is a gaseous radioactive element, and there are three isotopes of radon in nature: 222Rn, 220Rn and 219Rn. Due to the large difference in half-life, the measurement and protection of radon at present are mainly aimed at 222Rn, and the half-life is 3.825d.

[0003] At present, the calibration of the radon detector mainly depends on the standard radon chamber or radon source device of the professional laboratory. Among them, the standard radon chamber generates a stable concentration of radon gas environment in a closed space to realize the precision verification of the radon detector, and the core principle is to use radium-226 (226Ra) and other radioactive nuclides to produce radon gas, and to maintain the stability of the radon concentration through temperature, humidity and air pressure control modules. In addition, some schemes use small radon sources to generate radon gas with a gas path system, but such devices can usually only support the calibration of a single instrument, and the dynamic range of radon concentration is limited.

[0004] For the above prior art, the inventor found that the existing standard radon chamber relies on precise control equipment and large-area shielding facilities, and the construction cost of a single set is high. The traditional radon chamber adopts an overall space filling mode, and needs to maintain a high-concentration radon gas environment of several cubic meters. The radon gas consumption is large and difficult to recover, which not only increases the cost of radioactive waste treatment, but also has the risk of environmental pollution caused by leakage. The small radon source device is mostly designed as a single channel, and only 1-2 radon detectors can be calibrated at a time, which cannot match the high-efficiency calibration demand in large-scale production. Moreover, some schemes use short half-life radon sources, which need to frequently replace the radon source consumables or rely on a complex gas circulation system to maintain the concentration stability, thereby increasing the long-term operation and maintenance cost. SUMMARY

[0005] Based on the technical problems existing in the prior art, the present application provides a radon Rn222 measurement room for calibrating a radon detector and a test method thereof.

[0006] In a first aspect, the present application provides a radon Rn222 measurement room for calibrating a radon detector, which adopts the following technical scheme:

[0007] A radon Rn222 measurement room for calibrating a radon detector comprises:

[0008] A sealed chamber is provided with a sealed measurement cavity, and one-way valve groups are arranged on both sides of the sealed chamber to adjust the air pressure inside the sealed measurement cavity.

[0009] A radium-226 chloride decay chamber is arranged in the sealed measurement chamber and is provided with a decay chamber to release radon Rn222 by radioactive decay of radium-226 chloride, and an air inlet hole and an air outlet hole are arranged at two ends of the radium-226 chloride decay chamber respectively;

[0010] A radon measurement instrument assembly is arranged at one end of the radium-226 chloride decay chamber and communicates with the air outlet hole, and the radon measurement instrument assembly is provided with a plurality of radon measurement instruments to measure radon Rn222 released by radioactive decay of radium-226 chloride;

[0011] An air inlet assembly is arranged at the other end of the radium-226 chloride decay chamber and communicates with the air inlet hole, and the air inlet assembly is provided with an air inlet fan to introduce air into the radium-226 chloride decay chamber.

[0012] Through the above technical solution, the radon calibration system is constructed by integrating the sealed chamber, the radium-226 chloride decay chamber, the radon measurement instrument assembly and the air inlet assembly. The sealed chamber adjusts the air pressure through the one-way valve group to form a closed measurement environment; the radium-226 chloride decay chamber generates radon gas by using the principle of radioactive decay; the air inlet assembly introduces dry air to drive the flow of radon gas; and the radon measurement instrument assembly realizes parallel measurement through the multi-channel design. The modules work cooperatively to form a closed-loop system of radon gas generation, transmission, measurement and environment control. The modular design realizes functional integration, solves the problems of dispersed structure and complex operation of traditional calibration equipment. The cooperation of the sealed chamber and the one-way valve group ensures that radon gas does not leak, improving safety; the parallel measurement design of multiple radon measurement instruments breaks through the single-channel efficiency bottleneck and meets the batch calibration demand; and the linkage of the air inlet assembly and the decay chamber ensures the stability of radon gas concentration, laying a foundation for high-precision calibration.

[0013] Further, the one-way valve group includes a one-way air inlet valve and a one-way air outlet valve, which are arranged on the outer peripheral surface of the sealed chamber and communicate with the sealed measurement chamber to seal the sealed measurement chamber when the pressure in the sealed measurement chamber is close to the external pressure, the one-way air inlet valve and the one-way air outlet valve adopt a gravity type self-closing structure, and the valve plate of the one-way air inlet valve and the one-way air outlet valve is made of radiation-resistant organic glass material.

[0014] Through the above technical solution, the control system of the traditional electric valve is simplified by the gravity type self-closing structure, reducing the failure rate and energy consumption; the radiation-resistant material prolongs the service life of the valve and avoids the material aging problem in the long-term radiation environment. The independent arrangement of the two-way valve ensures that the sealed chamber can be closed during the calibration stage and can be efficiently ventilated during the exhaust stage, balancing safety and operational convenience.

[0015] Further, the radium-226 chloride decay chamber includes:

[0016] a shell formed as a stainless steel metal piece and provided with a containing cavity;

[0017] a shielding inner layer provided in the containing cavity and connected in abutment with the inner wall surface of the shell, the shielding inner layer being provided with a decay cavity;

[0018] a plurality of filter screen packages, each of the filter screen packages being provided in the decay cavity and formed as a melt-blown cloth filter screen piece, and each of the filter screen packages being wrapped with radium chloride 226;

[0019] Through the above technical solution, the structure of the radium chloride 226 decay chamber is further refined, mechanical support is provided by the stainless steel shell, radiation is blocked by the shielding inner layer, and the radioactive source is packaged by the melt-blown cloth filter screen package. The porous structure of the melt-blown cloth allows radon gas to pass through while trapping radioactive dust; the plurality of filter screen packages are arranged dispersedly to improve the radon gas emanation efficiency. The combination of the shell and the shielding inner layer forms double protection to prevent radiation leakage. The melt-blown cloth filter screen package design solves the problem of low radon gas emanation rate in traditional radioactive source packaging, improving the calibration efficiency; the synergistic effect of the shielding inner layer and the shell ensures that the radiation protection meets the standard, reducing the health risk of the operator; the modular filter screen package is convenient to replace and maintain, avoiding the cost waste caused by the overall replacement of the radioactive source.

[0020] Further, the shielding inner layer material includes a metal lead sheet with a thickness not less than 5 mm.

[0021] Through the above technical solution, the shielding inner layer uses a metal lead sheet with a specific thickness, which utilizes the high-density characteristics of lead to attenuate ionizing radiation. The lead sheet is tightly attached to the stainless steel shell to form a continuous shielding layer covering the entire decay cavity, ensuring that the radiation leakage path is blocked from the source. Passive protection is achieved through the physical properties of the material itself, without relying on electronic equipment, which is more reliable. The lead sheet with sufficient thickness ensures that the radiation dose meets the safety standard, providing a basic guarantee for long-term stable operation of the equipment, while simplifying the system design complexity of radiation protection.

[0022] Further, the radon measurement instrument assembly includes:

[0023] a total gas outlet pipe, one end of the total gas outlet pipe being connected in communication with one end of the decay cavity, and the total gas outlet pipe being provided with a dust filter screen to filter the gas discharged through the decay cavity;

[0024] a plurality of branch gas outlet pipes, each of the branch gas outlet pipes being provided at the other end of the total gas outlet pipe and formed as a pipe-shaped piece, and the outer peripheral surface of each of the branch gas outlet pipes being provided with a plurality of radon gas outlet fine holes penetrating along the thickness direction of the pipe wall;

[0025] Multiple radon detectors are provided, each corresponding to a radon outlet orifice, on the branch outlet pipe to calibrate the radon Rn222 contained in the gas.

[0026] Through the aforementioned technical solution, this application constructs a multi-channel gas distribution system using a hierarchical structure of a main outlet pipe, branch outlet pipes, and radon detectors. The main outlet pipe collects radon gas generated in the decay chamber, which, after being purified by a dust filter, is evenly distributed to each radon detector through the fine pores of the branch outlet pipes. The fine pore design controls the radon gas flow rate, ensuring consistent concentration in each channel; multiple radon detectors are calibrated in parallel with a one-to-one correspondence between the fine pores. The multi-branch design overcomes the efficiency limitations of traditional single-channel calibration, significantly improving batch processing capabilities; the dust filter reduces interference from radioactive dust on the radon detectors, ensuring measurement accuracy; the fine pore distribution structure ensures consistency of radon parameters in each channel, avoiding calibration errors caused by flow rate differences and improving the reliability of multi-instrument comparative analysis.

[0027] Furthermore, the intake assembly includes:

[0028] A fan, one end of which is connected to the outside air and is equipped with an air intake filter;

[0029] An air intake pipe, one end of which is connected to the other end of the fan, and the other end of which is connected to the air intake port of the radium-226 chloride decay chamber;

[0030] A drying section is provided on the air intake pipe and contains particulate desiccant to dry the gas sent into the air intake pipe by the fan.

[0031] Through the aforementioned technical solution, this application constructs an air pretreatment system by combining a fan, an air intake duct, and a drying section. External air, after being filtered for dust by the intake filter, is pressurized by the fan and sent into the drying section. Moisture is adsorbed by a particulate desiccant, and the dried air then enters the decay chamber to drive radon gas flow. The drying section cuts off the path of moisture interference with the stability of radon gas concentration. The intake filter and the drying section work together to prevent dust and moisture from entering the decay chamber, preventing filter blockage and radon concentration fluctuations, and extending equipment maintenance cycles. The fan provides stable airflow power, ensuring uniform distribution of radon gas in the gas path and improving the controllability of the calibration environment. The pretreated air reduces interference with the radon detector sensor, indirectly improving the accuracy of measurement data.

[0032] Furthermore, a main inlet valve is provided between the fan and the radium chloride-226 decay chamber, and a main outlet valve is provided between the radium chloride-226 decay chamber and the radon detector assembly. The fan is connected to the main inlet valve and the main outlet valve.

[0033] By the above technical solution, the fan is introduced, and the gas exchange of the sealed chamber is controlled through linkage with the main air inlet valve and the main air outlet valve. The active ventilation mode is more thorough than natural diffusion, and reduces the interference of residual radon gas on subsequent operations.

[0034] In a second aspect, the application provides a method for calibrating a radon Rn222 measurement chamber using a radon measurement instrument, which adopts the following technical solution:

[0035] A method for calibrating a radon Rn222 measurement chamber using a radon measurement instrument, comprising the following steps:

[0036] Close the sealed chamber and adjust the one-way valve group to the closed state, start the fan of the air inlet assembly, and make the radium chloride 226 in the radium chloride 226 decay chamber release radon Rn222 through radioactive decay, and after the radon concentration is stable, place the radon measurement instrument in the sealed chamber for calibration;

[0037] After the test is completed, the sealed chamber fan is started, and the radon-containing gas in the sealed measurement chamber is discharged through the sealed chamber air inlet valve and the sealed chamber air outlet valve.

[0038] Through the above technical solution, the application optimizes the determination method into four stages of calibration preparation, concentration stabilization, measurement execution, and exhaust ending. By closing the sealed chamber, starting the air inlet assembly to generate a stable radon gas environment, and opening the fan to discharge the residual gas after calibration, the sequence control of each step ensures that the radon concentration reaches a steady state before measurement, and the exhaust stage prioritizes operation safety.

[0039] In summary, the application has the following beneficial effects:

[0040] First, the application realizes significant improvement in calibration efficiency through systematic structural innovation. First, the radon measurement instrument assembly adopts a hierarchical design of a total air outlet pipe combined with multiple branch air outlet pipes, which enables radon gas to be evenly distributed to multiple radon measurement instruments through fine hole structures, breaking through the limitations of traditional single-channel calibration, supporting parallel measurement of multiple devices, and greatly improving the single calibration throughput. Second, the linkage design of the air inlet assembly and the radium chloride 226 decay chamber optimizes the radon gas generation and transmission path, and the dry air drives the stable flow of radon gas, shortening the waiting time for the concentration to reach a steady state. In addition, the standardized operation process clearly defines the stage control logic of sealing, gas production, calibration, and exhaust, reducing the uncertainty of human operation, improving the consistency and repeatability of batch calibration. This synergistic mechanism of hardware parallelization and process standardization effectively solves the problem of low efficiency and difficulty in matching large-scale production needs in existing solutions, providing an efficient calibration solution for radon measurement instrument manufacturers.

[0041] Second, the application constructs a multi-level security protection system from structural design to control logic. In terms of radiation shielding, the radium chloride 226 decay chamber adopts a double protection structure of a stainless steel shell and a lead sheet shielding inner layer, and the ionizing radiation is attenuated by high-density lead material to reduce the risk of radiation leakage from the source; the packaging design of the melt-blown cloth filter screen package effectively traps radioactive dust to avoid secondary pollution. In terms of radon gas leakage control, the one-way valve group of the sealed chamber adopts a gravity type self-closing structure, which is automatically closed when the pressure is balanced, ensuring the closed nature during the calibration stage; after the test is completed, the sealed chamber fan quickly exhausts the residual radon gas through active ventilation, combined with the directional exhaust design of the one-way air outlet valve, which significantly reduces the indoor radon gas concentration. In addition, the linkage logic of the electrical control system automates the air intake, gas production and exhaust process, reducing the contact time of the operator with the radioactive environment. These designs, through passive protection combined with active control, not only meet the requirements of radiation safety specifications, but also reduce the potential pollution to the environment, achieving double improvement in safety and environmental protection.

[0042] Third, the application significantly reduces the total life cycle cost of the equipment through modular and integrated design. In terms of core components, the radium chloride 226 decay chamber adopts a detachable melt-blown cloth filter screen package structure, which only needs to replace the filter screen package when the activity of the radioactive source decays, without the need to replace the entire decay chamber, greatly reducing the cost of consumables; the granular desiccant of the drying part adopts an independent filling design, which facilitates quick replacement during regular maintenance, avoiding complex system disassembly. In terms of system integration, the compact layout of the sealed chamber, decay chamber and gas path components reduces space occupation, reducing installation and transportation costs; the gravity type structure of the one-way valve group eliminates the complex control system of traditional electric valves, reducing failure rate and energy consumption. Independent fan control and standardized process simplify the operation steps, effectively solving the problems of complex maintenance and high long-term operation and maintenance cost in existing solutions, improving the economic efficiency and market applicability of the equipment. BRIEF DESCRIPTION OF DRAWINGS

[0043] Fig. 1 FIG. 1 is a structural schematic diagram of a radium chloride 226 decay chamber in an embodiment of the application;

[0044] Fig. 2 FIG. 4 is a structural schematic diagram of an air intake and exhaust device in an embodiment of the application.

[0045] Wherein, 1, sealed chamber; 11, one-way air inlet valve; 12, one-way air outlet valve; 13, air exhaust device; 131, sealed chamber fan; 132, sealed chamber air inlet valve; 133, sealed chamber air outlet valve; 2, radium chloride 226 decay chamber; 21, shell; 22, shielding inner layer; 23, filter screen package; 24, air inlet hole; 25, air outlet hole; 3, radon meter assembly; 31, total air outlet pipe; 32, branch air outlet pipe; 33, radon air outlet fine hole; 4, air intake assembly; 41, fan; 42, air intake pipeline; 43, drying part. DETAILED DESCRIPTION

[0046] The application is further described in detail below in conjunction with the embodiments.

[0047] The application discloses a radon Rn222 measuring chamber for calibrating a radon detector.

[0048] Reference Figs. 1-2 The radon Rn222 measuring chamber for calibrating the radon detector comprises a sealed chamber 1 which is a closed cavity structure made of glass. The sealed chamber 1 has an independent sealed measuring cavity inside. The main frame of the sealed chamber 1 is made of metal, and the outside is covered with shielding material to reduce external environmental interference. A one-way valve group is embedded on the outer walls of the adjacent two sides of the sealed chamber 1. The one-way valve group comprises a one-way air inlet valve 11 and a one-way air outlet valve 12, both of which are directly communicated with the sealed measuring cavity. The one-way air inlet valve 11 is used for the one-way inflow of external air, and the one-way air outlet valve 12 is used for the one-way discharge of internal gas. The sealed chamber 1 is also provided with an exhaust device 13 at the top. The one-way air inlet valve 11 and the one-way air outlet valve 12 are connected with the air inlet and the air outlet of the sealed measuring cavity respectively. The one-way air inlet valve 11 and the one-way air outlet valve 12 are both gravity type self-closing structures. The valve plate is made of radiation-resistant organic glass, and the automatic closure when pressure balance is achieved through the self-weight.

[0049] Inside the sealed chamber 1, a radium226 chloride decay chamber 2 is horizontally arranged. Air inlet holes 24 and air outlet holes 25 are respectively arranged on the end faces of the two ends of the radium226 chloride decay chamber 2. The radium226 chloride decay chamber 2 is a cylindrical metal piece. A shell 21 made of stainless steel metal material is arranged outside the radium226 chloride decay chamber 2. An accommodating cavity is processed inside the shell 21. A shielding inner layer 22 made of metal lead sheet is tightly attached to the inner wall of the accommodating cavity, and forms a decay cavity matched with the shape of the shell 21. A plurality of filter screen bags 23 made of melt-blown cloth material are evenly distributed in the decay cavity, and the radium226 chloride powder is wrapped inside the filter screen bags 23.

[0050] On one side of the air outlet hole 25 of the radium226 chloride decay chamber 2, a radon detector assembly 3 is fixedly connected. The radon detector assembly 3 comprises a total air outlet pipe 31 which is a hard pipe. The total air outlet pipe 31 is provided with a dust filter screen at one end, and is branched into a plurality of branch air outlet pipes 32 through a multi-way joint at the other end. The branch air outlet pipe 32 is an elongated pipe type piece. A plurality of radon air outlet fine holes 33 are evenly distributed on the outer circumferential surface of the branch air outlet pipe 32 in the axial direction. The branch air outlet pipe 32 extends radially or in parallel from the end of the total air outlet pipe 31, and is located in the upper or middle region of the sealed measuring cavity. A radon detector probe is arranged at the end of each radon air outlet fine hole 33, and is connected with the radon air outlet fine hole 33 in a one-to-one correspondence.

[0051] On one side of the air inlet hole 24 of the radium chloride 226 decay chamber 2, an air inlet assembly 4 is connected, which includes a fan 41, one end of which is connected with a flexible air inlet pipeline 42, and a drying part 43 is installed on the air inlet pipeline 42, the inside of the drying part 43 is filled with granular desiccant, and both ends are provided with air-permeable partitions.

[0052] A method for calibrating a radon Rn222 measuring chamber by using a radon measuring instrument, comprising the following steps:

[0053] 1. Check the appearance of the sealed chamber 1 to ensure that the glass cavity is not damaged, the metal frame and the shielding material are tightly connected, the gravity self-closing valve plate of the one-way air inlet valve 11 and the one-way air outlet valve 12 is in a natural closed state, and the rad-hard organic glass valve plate is free of cracks or deformation;

[0054] Check the radium chloride 226 decay chamber 2: confirm that the stainless steel shell 21 is tightly attached to the shielding inner layer 22, and the melt-blown cloth filter screen package 23 is evenly distributed in the decay chamber without damage or displacement; the connection flanges of the air inlet hole 24 and the air outlet hole 25 are sealed well;

[0055] The dust filter screen on the total air outlet pipe 31 is installed in place, the radon outlet fine holes 33 of the branch air outlet pipe 32 are not blocked, and the connection interface between the radon measuring instrument probe and the fine holes is clean and free of foreign matter;

[0056] Check the air inlet assembly 4: the drying part 43 at the air inlet end of the fan 41 has been filled with granular desiccant, the air inlet filter screen has no dust accumulation, and the flexible air inlet pipeline 42 has no bending or leakage;

[0057] Open the exhaust device 13 at the top of the sealed chamber 1, confirm that the pipeline connection is normal, and prepare for the subsequent air exchange operation.

[0058] 2. Close the one-way air inlet valve 11 and the one-way air outlet valve 12, start the sealed chamber fan 131, open the sealed chamber air inlet valve 132 and the sealed chamber air outlet valve 133, so that the external fresh air enters the sealed measuring chamber through the air inlet valve and is then discharged through the air outlet valve, and the air exchange is continued for 10-15 min to remove the residual gas in the chamber;

[0059] Close the sealed chamber fan 131 and the corresponding air inlet valve and air outlet valve, and stand still for 5 min, so that the sealed measuring chamber is balanced with the external air pressure through the gravity self-closing structure of the one-way valve group, and the initial sealing is ensured;

[0060] Connect each radon measuring instrument probe with the radon outlet fine holes 33 of the branch air outlet pipe 32 one by one, turn on the power of the radon measuring instrument, preheat it, and ensure that the equipment is in normal working condition.

[0061] 3. Start the fan 41 of the air intake assembly 4, and the external air is filtered by the air intake filter screen, dried by the drying part 43, and then enters the air inlet hole 24 of the radium chloride 226 decay chamber 2 through the flexible air intake pipeline 42 to drive the air flow in the decay chamber; ensure that the dried air uniformly passes through the melt-blown cloth filter screen package 23, and carries the radon Rn222 gas generated by the radium chloride 226 decay to the air outlet hole 25 direction for transmission;

[0062] The radon gas enters the total air outlet pipe 31 through the air outlet hole 25 of the decay chamber, is filtered by the dust filter screen to remove radioactive dust, is branched to the multiple branch air outlet pipes 32, and finally contacts the radon detector probe through the radon air outlet fine hole 33;

[0063] Keep the air intake fan 41 running continuously to make the radon gas circulate in the sealed measurement chamber until the concentration reaches a dynamic balance.

[0064] 4. After the radon gas concentration is stable, start the measurement program of all radon detectors synchronously, and record the initial reading.

[0065] Record the measurement values of each radon detector at a preset time interval, continuously collect at least 3 groups of data, and ensure that the data repeatability meets the requirements.

[0066] If calibration at different concentration points is needed, the radon gas concentration can be changed by adjusting the rotating speed of the air intake fan 41, and the above stable and measurement steps are repeated;

[0067] Compare the measurement results of each radon detector, calculate the relative deviation, and eliminate abnormal values; if the deviation exceeds the allowed range, check whether the radon air outlet fine hole 33 of the corresponding branch air outlet pipe 32 is blocked or the radon detector probe connection is loose, and then re-measure after troubleshooting.

[0068] 5. Radon gas discharge and sealing chamber 1 purification

[0069] After calibration is completed, the fan 41 of the air intake assembly 4 is turned off, the connection between the radon detector probe and the branch air outlet pipe 32 is disconnected, the probe is removed from the sealed measurement chamber, the sealing chamber fan 131, the sealing chamber air inlet valve 132 and the sealing chamber air outlet valve 133 are opened, the radon-containing gas in the sealed measurement chamber is forced to be discharged to the designated radioactive waste gas treatment system through the one-way air outlet valve 12, and the air exchange is continued for more than 30 min until the radon concentration in the chamber is reduced to below the safety limit;

[0070] Turn off all valves and fans 41, check whether the one-way valve group returns to the self-closing state, clean the radon detector probe, and properly store it.

[0071] 6. Replace the particulate desiccant in the drying part 43 and the dust filter screen on the total air outlet pipe 31, and check whether the melt-blown cloth filter screen package 23 of the radium chloride 226 decay chamber 2 needs to be replaced;

[0072] The glass cavity and metal frame of the sealed chamber 1 are cleaned to ensure that there is no radioactive contamination left, and the calibration process is completed.

[0073] The present application has been described in detail by combining the specific embodiments and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that various equivalent replacements, modifications or improvements can be made to the technical solutions and embodiments of the present application without departing from the spirit and scope of the present application, and these all fall within the scope of the present application. The protection scope of the present application is subject to the appended claims.

[0074] All publications, patent applications, patents and other references mentioned in the specification are hereby incorporated by reference. Unless otherwise defined, all technical and scientific terms used in the specification have the meaning commonly understood by one of ordinary skill in the art. In case of conflict, the definitions in the specification prevail.

[0075] When the specification derives materials, substances, methods, steps, devices or components, etc. with the word head "known to those skilled in the art", "prior art" or similar terms, the objects derived by the word head cover those commonly used in the art at the time of the present application, but also include those which are not commonly used at present, but will become recognized as suitable for similar purposes in the art.

[0076] In the context of the specification, except for the explicitly stated content, any matters or items not mentioned are directly applicable to those known in the art without any change.

Claims

1. A radon Rn222 measurement chamber for use in the calibration of a radon meter, characterized in that, It comprises: a sealed chamber (1) provided with a sealed measuring chamber, two sides of the sealed chamber (1) are provided with a one-way valve group to adjust the air pressure inside the sealed measuring chamber; a radium chloride 226 decay chamber (2) provided in the sealed measuring chamber and provided with a decay chamber to release radon Rn222 by radium chloride 226 radioactive decay, two ends of the radium chloride 226 decay chamber (2) are respectively provided with an air inlet hole (24) and an air outlet hole (25); a radon detector assembly (3) provided at one end of the radium chloride 226 decay chamber (2) and connected with the air outlet hole (25), the radon detector assembly (3) is provided with a plurality of radon detectors to measure the radon Rn222 released by radium chloride 226 radioactive decay; an air inlet assembly (4) provided at the other end of the radium chloride 226 decay chamber (2) and connected with the air inlet hole (24), the air inlet assembly (4) is provided with an air inlet fan (41) to introduce air into the radium chloride 226 decay chamber (2); The radium chloride 226 decay chamber (2) comprises: a shell (21) formed of stainless steel metal and provided with a containing chamber; a shielding inner layer (22) provided in the containing chamber and connected with the inner wall surface of the shell (21), the shielding inner layer (22) is provided with a decay chamber; a plurality of filter screen packages (23), each of the filter screen packages (23) is provided in the decay chamber and formed of a melt-blown cloth filter screen piece, and each of the filter screen packages (23) is wrapped with radium chloride 226 powder.

2. A radon Rn 222 measurement chamber for use in the calibration of a radon measurement instrument according to claim 1, characterised in that, The one-way valve group comprises a one-way air inlet valve (11) and a one-way air outlet valve (12), the one-way air inlet valve (11) and the one-way air outlet valve (12) are respectively provided on the outer peripheral surface of the sealed chamber (1) and are connected with the sealed measuring chamber, so as to seal the sealed measuring chamber when the sealed measuring chamber is close to the external pressure, the one-way air inlet valve (11) and the one-way air outlet valve (12) adopt a gravity type self-closing structure, and the valve sheet materials of the one-way air inlet valve (11) and the one-way air outlet valve (12) are all radiation-resistant organic glass materials.

3. A radon Rn 222 measurement chamber for use in the calibration of a radon measurement instrument according to claim 1, characterized in that The shielding inner layer (22) is made of metal lead sheet with a thickness not less than 5mm.

4. The radon Rn 222 measurement chamber for calibrating a radon meter according to claim 1, wherein, The radon detector assembly (3) comprises: a total air outlet pipe (31) connected with one end of the decay chamber, the total air outlet pipe (31) is provided with a dust filter screen to filter the gas discharged from the decay chamber; a plurality of branch air outlet pipes (32), each of the branch air outlet pipes (32) is provided at the other end of the total air outlet pipe (31) and formed of a pipe type piece, and the outer peripheral surface of each of the branch air outlet pipes (32) is provided with a plurality of radon outlet fine holes (33) penetrating along the thickness direction of the pipe wall; a plurality of radon detectors, each of the radon detectors is provided on the branch air outlet pipe (32) corresponding to each of the radon outlet fine holes (33) to calibrate the radon Rn222 contained in the gas.

5. A radon Rn 222 measurement chamber for use in the calibration of a radon measurement instrument according to claim 1, characterized in that The air inlet assembly (4) comprises: A fan (41) has one end communicating with external air and is provided with an air inlet filter screen; An air inlet duct (42) has one end communicating with the other end of the fan (41) and the other end communicating with the air inlet hole (24) of the radium226 chloride decay chamber (2); A drying part (43) is arranged on the air inlet duct (42) and is internally provided with a granular desiccant to dry the gas sent into the air inlet duct (42) by the fan (41).

6. A radon Rn 222 measurement chamber for use in the calibration of a radon measurement instrument according to claim 1, characterized in that A main air inlet valve is arranged between the fan (41) and the radium226 chloride decay chamber (2), and a main air outlet valve is arranged between the radium226 chloride decay chamber (2) and the radon meter assembly (3), and the fan (41) communicates with the main air inlet valve and the main air outlet valve.

7. A method for the calibration of a radon Rn222 measurement chamber for the calibration of a radon Rn222 measurement chamber according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: Close the sealed chamber (1) and adjust the one-way valve group to the closed state, start the fan (41) of the air inlet assembly (4), and release radon Rn222 from the radium226 chloride in the radium226 chloride decay chamber (2) by radioactive decay, after the radon concentration is stable, place the radon meter in the sealed chamber (1) for calibration; After the test is completed, open the sealed chamber fan (131) and discharge the radon-containing gas in the sealed measurement chamber through the sealed chamber air inlet valve (132) and the sealed chamber air outlet valve (133).

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