Method for determining the radon emanation of a porous medium
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING RES INST OF URANIUM GEOLOGY
- Filing Date
- 2026-04-01
- Publication Date
- 2026-06-09
Smart Images
Figure CN122172253A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of this application relate to the field of measuring the radioactivity content of an object, and specifically to a method for determining the radon exudation rate of a porous medium. Background Technology
[0002] The statements herein are provided merely as background information in connection with this application and do not necessarily constitute prior art.
[0003] Radon is a colorless, odorless, and tasteless radioactive gas released during the decay of uranium or radium in underground soil, rocks, and building materials. Radon is classified as a Group 1 carcinogen. When radon is inhaled, its decay products (such as polonium-218 and lead-214) release alpha particles, which can cause radiation damage to the human respiratory system and induce lung cancer.
[0004] Therefore, in the process of monitoring underground space and geological environment, detecting radioactivity in building materials, and assessing groundwater pollution, it is necessary to accurately determine the radon release rate of porous media (such as soil, rock, concrete, etc.). However, existing methods for determining the radon release rate of porous media still have shortcomings such as insufficient measurement precision and low accuracy. Summary of the Invention
[0005] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.
[0006] An embodiment of this application provides a method for determining the radon exhalation rate of a porous medium, comprising the following steps: S10: preparing a sample of the porous medium; S20: placing the sample in a constant temperature environment; S30: retaining the exhalation surface of the sample; S40: sealing the constant temperature environment of the sample and measuring the accumulated radon concentration in the constant temperature environment at multiple different times; S50: determining the radon equilibrium concentration of the porous medium sample in the constant temperature environment based on the radon concentration obtained in step S40; S60: determining the radon exhalation rate based on the radon equilibrium concentration.
[0007] The method for determining the radon release rate of porous media provided in the embodiments of this application eliminates the interference of ambient temperature fluctuations on the radon release rate by placing the porous media sample in a constant temperature environment, thereby ensuring the stability and reproducibility of the determined radon release rate. Furthermore, by sealing the sample in the constant temperature environment, the accumulated radon concentration at multiple different times is measured to prevent the escape of released radon gas and reduce errors. Based on this, the radon equilibrium concentration of the porous media sample in the constant temperature environment is determined according to the accumulated radon concentration at multiple different times, so as to determine the accumulated radon equilibrium concentration when reaching equilibrium, and the radon release rate is determined accordingly. Compared with traditional measurement methods, it does not require measuring the amount of radon released per unit time. For low-background porous media with small radon release per unit time, it can avoid the influence of measurement errors on the final determined radon release rate, thereby effectively improving the accuracy and precision of the radon release rate. Attached Figure Description
[0008] Other objects and advantages of this application will become apparent from the following description of embodiments of this application with reference to the accompanying drawings, and will help to provide a comprehensive understanding of this application.
[0009] Figure 1 This is a schematic diagram of the structure of a porous media sample according to an embodiment of this application; Figure 2 This is a schematic diagram of the apparatus used to determine the radon exudation rate of porous media according to an embodiment of this application.
[0010] Explanation of reference numerals in the attached figures: 10. Sample chamber; 20. Pressure control chamber; 30. Constant temperature chamber; 40. Injection assembly; 41. Injection pipeline; 42. Air pump; 50. Radon collection and measurement assembly; 51. Air inlet pipeline; 52. Radon collector; 53. Air pump; 54. Radon measuring device.
[0011] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding. Detailed Implementation
[0012] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.
[0013] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the device structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.
[0014] The inventors of this application have discovered that the methods used in related technologies for determining the radon release rate of porous media typically involve measuring the amount of radon released per unit time. These methods are susceptible to fluctuations in ambient temperature, and some of the released gas can easily escape during the measurement process, resulting in large errors and low accuracy in the determined radon release rate. This is especially true when determining the radon release rate of low-background porous media, where the amount of radon released per unit time is small, and even slight errors in the measurement of the amount of radon released can have a significant impact on the final measurement results, leading to a very large relative error in the determined radon release rate.
[0015] Based on this, embodiments of this application provide a method for determining the radon exhalation rate of a porous medium, comprising the following steps: S10: Sample for preparing porous media.
[0016] S20: Place the sample in a constant temperature environment.
[0017] S30: Preserve the precipitation surface of the sample.
[0018] S40: The isothermal environment of the sealed sample, measuring the cumulative radon concentration in the isothermal environment at multiple different times.
[0019] S50: Based on the radon concentration obtained in step S40, determine the radon equilibrium concentration of the porous medium sample in a constant temperature environment.
[0020] S60: Determine the radon release rate based on the radon equilibrium concentration.
[0021] The method for determining the radon release rate of porous media provided in the embodiments of this application eliminates the interference of ambient temperature fluctuations on the radon release rate by placing the porous media sample in a constant temperature environment, thereby ensuring the stability and reproducibility of the determined radon release rate. Furthermore, by sealing the sample in the constant temperature environment, the accumulated radon concentration at multiple different times is measured to prevent the escape of released radon gas and reduce errors. Based on this, the radon equilibrium concentration of the porous media sample in the constant temperature environment is determined according to the accumulated radon concentration at multiple different times, so as to determine the accumulated radon equilibrium concentration when reaching equilibrium, and the radon release rate is determined accordingly. Compared with traditional measurement methods, it does not require measuring the amount of radon released per unit time. For low-background porous media with small radon release per unit time, it can avoid the influence of measurement errors on the final determined radon release rate, thereby effectively improving the accuracy and precision of the radon release rate.
[0022] In some embodiments, in step S40, the accumulated radon concentration in a constant-temperature environment at multiple different times is measured to obtain n sets of measurement data ( , ),in, Indicates different times, Indicates in The radon concentration at time t, i.e., at - The radon concentration accumulated during this period.
[0023] In some embodiments, step S50 may further include the following steps: S51: Determine the moment when the predetermined equilibrium concentration is reached.
[0024] S52: Determine the radon concentration at the time determined in step S51.
[0025] S53: Determine the radon equilibrium concentration based on the time determined in S51 and the radon concentration determined in S52.
[0026] In this embodiment, by determining the moment when the equilibrium concentration reaches a predetermined ratio and determining the radon concentration accumulated in the constant temperature environment at that moment, the radon equilibrium concentration can be accurately determined based on the moment and the radon concentration. That is, the accurate accumulated radon equilibrium concentration when a stable equilibrium state is reached can be determined, thereby helping to ensure the accuracy of the radon release rate measurement.
[0027] In some embodiments, the time at which a predetermined equilibrium concentration is reached, the radon concentration at that time, and the radon equilibrium concentration conform to the following relationship: .
[0028] in, The equilibrium concentration of radon is represented by t, which represents the time when the predetermined equilibrium concentration is reached. This indicates the radon concentration at that moment. This represents the radon decay coefficient.
[0029] In this embodiment, by establishing the relationship between the time when the predetermined equilibrium concentration is reached, the radon concentration at that time, and the radon equilibrium concentration, the radon equilibrium concentration of the porous medium sample in a constant temperature environment can be accurately determined under the condition that the time when the predetermined equilibrium concentration is reached and the radon concentration at that time are determined. This helps to further improve the accuracy of the radon exhalation rate determined based on the radon equilibrium concentration.
[0030] In some embodiments, step S51 may further include the following steps: determining a predetermined proportion of the equilibrium concentration; and determining the time at which the predetermined proportion of the equilibrium concentration is reached based on the predetermined proportion. In this embodiment, by determining a predetermined proportion of the equilibrium concentration, i.e., the proportion of the desired equilibrium concentration, the time at which the equilibrium concentration is reached is determined. Based on this, the radon concentration at that time is determined, thereby determining the radon equilibrium concentration. This reduces the measurement time while minimizing the calculation error of the radon equilibrium concentration, thus balancing the efficiency and accuracy of the radon release rate.
[0031] In some embodiments, the time at which a predetermined equilibrium concentration is reached and the predetermined concentration conform to the following relationship: .
[0032] This indicates the moment when the predetermined equilibrium concentration is reached. denoted by radon decay coefficient, and f represents a predetermined proportion.
[0033] In this embodiment, by establishing the time when a predetermined equilibrium concentration is reached and the relationship between the predetermined concentration and the predetermined concentration, it is possible to accurately determine the time when the equilibrium concentration is reached according to the desired equilibrium concentration ratio, thereby further improving the efficiency and accuracy of the determined radon release rate.
[0034] In some embodiments, a predetermined proportion of the equilibrium concentration can be determined based on the amount of radon exuded from the porous media sample, which helps to reduce the calculation error of the radon equilibrium concentration.
[0035] Specifically, the predetermined ratio f takes values in the range [0, 1), and when f = 0.5, ≈91.7h, approximately 3.8 days, or one half-life; when f=0.25, ≈38.1h; when f=0.1, ≈13.9h; when f=0.01, ≈1.3h. Therefore, the smaller the desired equilibrium concentration ratio, the shorter the time required to reach that equilibrium concentration, i.e., the shorter the cumulative measurement time. While a shorter cumulative measurement time improves measurement efficiency and effectively avoids system instability factors that may be introduced by long-term measurements, such as background drift, unstable radon release rates, and increased backdiffusion effects, for low-background porous media (i.e., porous media with a small radon release per unit time), the accumulated radon concentration may be very low, leading to a poor signal-to-noise ratio and a large relative error. Conversely, a longer cumulative measurement time results in a higher accumulated radon concentration, a higher signal-to-noise ratio, and a smaller error.
[0036] Therefore, for low-background porous media, i.e., porous media with a small amount of radon released per unit time, a predetermined ratio of a relatively high equilibrium concentration can be determined, such as 0.5 or 0.25; for high-background porous media, i.e. porous media with a high amount of radon released per unit time, a predetermined ratio of a relatively low equilibrium concentration can be determined, such as 0.01 or 0.1.
[0037] In some embodiments, step S60 may further include the following steps: determining the volume of the isothermal environment and the volume of the sample; determining the area of the precipitation surface of the sample; and determining the radon emission rate based on the radon equilibrium concentration, the volume of the isothermal environment, the volume of the sample, and the area of the precipitation surface of the sample. In this embodiment, by considering the volume of the isothermal environment, the volume of the sample, and the area of the precipitation surface of the sample, and combining this with the radon equilibrium concentration determined in step S50, the radon emission rate is determined. This eliminates the error caused by the volume of the isothermal environment on the radon emission measurement results and eliminates the influence of size effects on radon emission, thereby improving the accuracy and precision of the determined radon emission rate.
[0038] In some embodiments, the radon equilibrium concentration, the volume of the isothermal environment, the volume of the sample, the area of the precipitation surface of the sample, and the radon precipitation rate conform to the following relationship: .
[0039] in, Indicates the radon equilibrium concentration. This represents the volume of a constant-temperature environment. S represents the volume of the sample, S represents the area of the precipitation surface of the sample, and J represents the radon precipitation rate. This represents the radon decay coefficient.
[0040] In this embodiment, the relationship between radon equilibrium concentration, the volume of the isothermal environment, the volume of the sample, the area of the precipitation surface of the sample, and the radon release rate is established. The difference between the volume of the isothermal environment and the volume of the sample is calculated to eliminate the error caused by the volume of the isothermal environment on the radon release measurement results. Thus, given the radon equilibrium concentration, the volume of the isothermal environment, the volume of the sample, and the area of the precipitation surface of the sample, it is easy to accurately determine the radon release rate of the porous medium.
[0041] In some embodiments, the porous medium sample can be a cylinder with a height-to-diameter ratio of not less than 2, in order to eliminate the influence of size effect on the radon precipitation path and improve the accuracy of the determined radon precipitation rate. For example, the porous medium sample can be a cylinder with a diameter of 50 mm and a height of 100 mm, with a flat bottom and smooth surface. Figure 1 As shown, Figure 1 A schematic diagram of the structure of a porous media sample according to an embodiment of this application is shown.
[0042] like Figure 2As shown, Figure 2 This diagram illustrates the structure of an apparatus used to determine the radon exhalation rate of porous media according to an embodiment of this application. In some embodiments, the constant temperature environment may include a sample chamber 10, a pressure control chamber 20, and a constant temperature chamber 30. The sample chamber 10 is disposed within the pressure control chamber 20, which is disposed within the constant temperature chamber 30. The sample is disposed within the sample chamber 10. The pressure control chamber 20 can use external pressure to make the sample adhere to the walls of the sample chamber 10, thereby sealing the exhalation surface around the sample and ensuring that radon can only be exhaled from the top exhalation surface of the sample. This facilitates accurate determination of the area of the exhalation surface of the porous media sample and improves the accuracy of the determined radon exhalation rate of the porous media.
[0043] In some embodiments, the constant temperature chamber 30 can be heated by an oil bath, water bath, or air bath to maintain the constant temperature state of the sample chamber 10, the pressure control chamber 20, and the constant temperature chamber 30, thereby eliminating the interference of ambient temperature fluctuations on the measurement results of the radon concentration released from the sample.
[0044] In some embodiments, the injection assembly 40 is configured to apply pressure to the pressure control chamber 20 so that the sample fits against the walls of the sample chamber 10.
[0045] In some embodiments, the injection assembly 40 may include an injection line 41 and an air pump 42. The injection line 41 is in fluid communication with the pressure control chamber 20, and the air pump 42 injects gas at a predetermined pressure into the pressure control chamber 20 through the injection line 41, so that the sample and the sample chamber 10 are in contact with the surrounding walls.
[0046] In some embodiments, the wall of the sample chamber 10 is made of a soft material that does not have radon adsorption characteristics, so as to avoid the adsorption of radon released from the sample, which would lead to a large error in the determination of radon concentration and thus affect the accuracy of the determined radon release rate.
[0047] In some embodiments, a radon collection and measurement component 50 may be provided to collect radon precipitated from the sample and measure the radon concentration. The radon collection and measurement component 50 is configured to communicate with the top of the sample chamber 10 so that all radon precipitated from the sample in the sample chamber 10 is collected into the radon collection and measurement component 50, which helps to improve the accuracy of radon concentration measurement.
[0048] In some embodiments, the radon collection and measurement assembly 50 may include an air inlet pipe 51, a radon collector 52, a vacuum pump 53, and a radon measuring device 54. The air inlet pipe 51 is in fluid communication with the top of the sample chamber 10 and the radon collector 52. The vacuum pump 53 draws radon precipitated from the sample in the sample chamber 10 into the radon collector 52 via the air inlet pipe 51. The radon measuring device 54 is disposed in the radon collector 52 to measure the radon concentration in the radon collector 52.
[0049] The following shows the results of determining the radon exhalation rate of two porous media samples using the method provided in the embodiments of this application, wherein Table 1 shows the measured radon concentration values of the two samples at the time when they reach equilibrium concentrations of different proportions, and Table 2 shows the radon equilibrium concentration and radon exhalation rate of the two samples determined according to the measurement results in Table 1.
[0050] Table 1. Radon Concentration Measurement Values Table 2. Results of Radon Emission Rate Measurement As shown in Table 2, the background radon concentrations of the two samples are different, meaning the radon release amounts are different. Therefore, the predetermined ratios of the equilibrium concentrations selected are different. According to Table 1, the background radon concentration of the first sample is higher, and the predetermined ratio f is determined to be 0.01, 0.05, 0.1, and 0.25. The background radon concentration of the second sample is lower, and the predetermined ratio f is determined to be 0.05, 0.1, 0.25, and 0.5.
[0051] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.
[0052] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.
Claims
1. A method for determining the radon exhalation rate of a porous medium, characterized in that, It includes the following steps: S10: Prepare a sample of the porous medium; S20: Place the sample in a constant temperature environment; S30: Retain the precipitation surface of the sample; S40: Seal the isothermal environment of the sample and measure the cumulative radon concentration in the isothermal environment at multiple different times; S50: Determine the radon equilibrium concentration of the porous medium sample in the constant temperature environment based on the radon concentration obtained in step S40. S60: Determine the radon release rate based on the radon equilibrium concentration.
2. The method according to claim 1, characterized in that, Step S50 also includes the following steps: S51: Determine the moment when the predetermined equilibrium concentration is reached; S52: Determine the radon concentration at the time determined in step S51; S53: Determine the radon equilibrium concentration based on the time determined in S51 and the radon concentration determined in S52.
3. The method according to claim 2, characterized in that, The time when the predetermined equilibrium concentration is reached, the radon concentration at that time, and the radon equilibrium concentration conform to the following relationship: ， in, The radon equilibrium concentration is represented by t, and t represents the time when the predetermined equilibrium concentration is reached. This indicates the radon concentration at that specific moment. This represents the radon decay coefficient.
4. The method according to claim 1, characterized in that, Step S60 also includes the following steps: Determine the volume of the constant temperature environment and the volume of the sample; Determine the area of the precipitation surface of the sample; The radon emission rate is determined based on the radon equilibrium concentration, the volume of the isothermal environment, the volume of the sample, and the area of the precipitation surface of the sample.
5. The method according to claim 4, characterized in that, The radon equilibrium concentration, the volume of the isothermal environment, the volume of the sample, the area of the precipitation surface of the sample, and the radon precipitation rate conform to the following relationship: ， in, This indicates the radon equilibrium concentration. This indicates the volume of the constant temperature environment. S represents the volume of the sample, S represents the area of the precipitation surface of the sample, and J represents the radon precipitation rate. This represents the radon decay coefficient.
6. The method according to claim 2, characterized in that, Step S51 also includes the following steps: Determine the predetermined proportion of the equilibrium concentration; The time when the equilibrium concentration reaches the predetermined ratio is determined based on the predetermined ratio.
7. The method according to claim 6, characterized in that, The time at which the predetermined equilibrium concentration is reached and the predetermined concentration conform to the following relationship: ， This indicates the moment when the predetermined equilibrium concentration is reached. denoted by radon decay coefficient, and f represents the predetermined ratio.
8. The method according to any one of claims 1-7, characterized in that, The sample is a cylinder with a height-to-diameter ratio of not less than 2.
9. The method according to any one of claims 1-7, characterized in that, The constant temperature environment includes a sample chamber, a pressure control chamber, and a constant temperature chamber. The sample chamber is located inside the pressure control chamber, and the pressure control chamber is located inside the constant temperature chamber. The sample is placed inside the sample chamber, and the pressure control chamber can use external pressure to make the sample fit against the walls of the sample chamber.
10. The method according to claim 9, characterized in that, The walls of the sample chamber are made of a soft material that does not have radon adsorption characteristics.