Device and method for measuring entering rate of radon in air into water surface and entering rate of radon in water into air

Abstract

The invention discloses a device and method for measuring the rate of radon in air entering a water surface and the rate of radon in water entering the air. The device comprises a static floating chamber, an air inlet pipe, an air outlet pipe, a foam plate, a drying bottle, an RAD7 radon measuring instrument and a flow rate controller. The foam board is arranged around the static floating chamber, and the flow rate controller, the drying bottle, the RAD7 emanometer and the static floating chamber are sequentially connected through hoses. The method comprises the following steps: firstly, realizing and recording the radon concentration when the system is balanced through a power-off full-open state of a flow rate controller, then disconnecting the RAD7 radon measuring instrument and a static floating chamber, controlling the normal working state of the flow rate controller, recording the radon concentration when the system is newly balanced, and establishing the radon concentration in water and the rate of radon in water entering air; and calculating the relationship between the radon entering the water surface in the air and the rate of radon entering the air in the water. The device is simple in structure, convenient to operate and short in measurement time, the limitation of a single equilibrium state of a traditional static chamber method is overcome, and key data support is provided for accurate calculation of the bidirectional radon exchange rate.

Description

Technical Field

[0001] The present invention relates to a nuclear radiation detection technology, in particular to a device and method for measuring the rate of radon in air entering water surface and radon in water entering air. Background Art

[0002] As a natural radioactive gas, the exchange process of radon at the water-air interface is an important topic in environmental radiation research. The exchange of radon is a two-way dynamic process, which includes both the dissolution of radon in air into water body and the release of dissolved radon in water into the atmosphere. This exchange process directly affects the distribution and migration of radon in the environment and is of great significance for evaluating radiation exposure risks. At present, the research on the radon exchange process mainly focuses on the radon exhalation, and the understanding of the two-way exchange mechanism is still not deep enough.

[0003] In recent years, the development of isotope tracer technology has provided new ideas for studying the radon exchange process. By using specific isotope labeling, the migration path and exchange rate of radon can be traced more accurately. At the same time, the introduction of micrometeorological methods has also provided a new perspective for understanding the interface exchange mechanism. However, these new technologies still face problems such as insufficient sensitivity and complex operation in practical applications, and need to be further improved and perfected. The latest research shows that by precisely regulating parameters such as temperature and humidity in a static chamber and cooperating with a high-sensitivity online monitoring system, the measurement accuracy can be significantly improved while maintaining the simplicity of the method. Especially the application of new semiconductor detectors makes it possible to continuously monitor the radon concentration in real time, which provides a powerful tool for studying the dynamic process of radon exchange. These technological innovations have laid a foundation for the in-depth application of the static chamber method in environmental radon migration research. However, the above existing technologies have problems of complex calculation or high cost. Therefore, it is very necessary to simply and efficiently obtain the rate of radon in air entering water surface and radon in water entering air. Summary of the Invention

[0004] The object of the present invention is to overcome the above deficiencies of the prior art and provide a device and method for measuring the rate of radon in air entering water surface and radon in water entering air.

[0005] The technical solution of the present invention is: a device for measuring the rate of radon in air entering water surface and radon in water entering air, which includes a static floating chamber, an intake pipe, an outlet pipe, a foam board, a drying bottle, a RAD7 radon detector and a flow rate controller; the foam board is arranged around the static floating chamber and fixedly connected to the static floating chamber, a substance for drying gas is placed in the drying bottle, the intake pipe and the outlet pipe are respectively installed on the static floating chamber, the outlet pipe is connected to the intake end of the flow rate controller through a hose, the outlet end of the flow rate controller is connected to the intake end of the drying bottle, the outlet end of the drying bottle is connected to the intake end of the RAD7 radon detector through a hose, and the outlet end of the RAD7 radon detector is connected to the intake pipe of the static floating chamber through a hose.

[0006] A further technical solution of the present invention is that the substance placed in the drying bottle is calcium chloride powder.

[0007] Another technical solution provided by the present invention is a method for an apparatus applied to measuring the rate of radon in air entering water surface and the rate of radon in water entering air, including a measurement process and a calculation process. The specific steps are as follows: I. Measurement process A. Place the static floating chamber and the surrounding foam board on the water surface of the water sample to be measured. The flow rate controller is in a power-off and fully open state. Start the pump of the RAD7 radon detector. The radon-containing air in the static floating chamber enters the drying bottle through the outlet pipe under the action of the pump for drying, and then enters the RAD7 radon detector. When the radon concentration data measured by the RAD7 radon detector tends to be stable, that is, when the system reaches equilibrium, record the radon concentration measured in the RAD7 radon detector. c(t) .

[0008] B. Disconnect the hose between the gas outlet end of the RAD7 radon detector and the inlet pipe of the static floating chamber. The flow rate controller is in a normal working state. Start the pump of the RAD7 radon detector. The radon-containing air in the static floating chamber enters the drying bottle through the outlet pipe under the action of the pump for drying, and then enters the RAD7 radon detector. When the radon concentration data measured by the RAD7 radon detector tends to be stable, that is, when the system reaches a new equilibrium state during the operation of the flow rate controller, record the radon concentration measured in the RAD7 radon detector 6. c’(t) .

[0009] C. Take the water on the water surface layer under the static floating chamber and measure the radon concentration and flow rate when the radon concentration reaches equilibrium by the bubbling method.

[0010] II. Calculation process The radon in water mainly comes from the decay of dissolved radium in water. The release of radon in water to the air through the water-air interface is the precipitation of radon on the water surface. Since the water volume is approximately infinite during the measurement process, assuming that the radon concentration in water remains unchanged when measuring the radon precipitation rate on the water surface, the radon concentration in the static floating chamber at this time is expressed by formula (1): (1) Wherein, c(t) represents the radon concentration in the static floating chamber, with the unit of Bq / m 3 ; A 1 represents the rate of radon in air entering the water surface, with the unit of m / s; A 2 represents the rate of radon on the water surface entering the air, with the unit of m / s; c(H 2 o)Indicates the radon concentration in water, with the unit of Bq / m 3 ; V Indicates the volume of the gas path, including the volume of the gas path in the static floating chamber, the volume of the measurement chamber in the RAD7 radon detector, and the volume of the connecting pipeline, with the unit of m 3 ; S Indicates the surface area of the static floating chamber, with the unit of m 2 ; λ Indicates the radon decay constant, λ l Indicates the leakage coefficient.

[0011] When the system reaches equilibrium, the following expression exists: (2) After substituting formula (2) into formula (1), formula (1) is simplified to: (3) According to the literature, the distribution ratio of the gas radon concentration to the water radon concentration can be known X , and is expressed by the following formula: (4) Among them, T Indicates the temperature during measurement. Assuming that the radon concentration in the static floating chamber 1 is uniform and the radon concentration in the water body is uniform, according to formula (3) and formula (4), the following can be obtained: (5) When the surface area of the static floating chamber is very large, the height is very low, and at the same time, good sealing makes the leakage very small, S* A 1 / V Is much larger than λ And λ l At this time, the following expression exists: (6) When the flow rate controller is started and the system reaches a new equilibrium state, the calculation expression for the radon concentration in the static floating chamber is: (7) Among them, c’(t) Indicates the radon concentration in the static floating chamber 1 at the new equilibrium state, with the unit of Bq / m 3 ; c’(H 2 o) Indicates the radon concentration in water at the new equilibrium state; L Is the flow rate of the flow rate controller 7, with the unit of L / m 3 ; V 1Represents the volume of the static floating chamber 1, in m 3 ; c 0 is the radon concentration in the environment, in Bq / m 3 , however, due to the very low radon concentration in the environment, it is basically negligible, and formula (7) can be simplified to: (8) When a new equilibrium state is reached, there is dc’(t) / dt = 0 , and formula (8) can be transformed into: (9) When the flow rate of the flow rate controller 7 is controlled such that L / V 1 is much greater than S*A 1 / V 1 、λ and λ l at this time, formula (9) is transformed into: (10) The radon concentration in water is measured by the bubbling method c’(H 2 o) , substituting the measured radon concentration in water into formula (10) to obtain the rate of radon in water entering the air A 2 , and then substituting A 2 into formula (6) to obtain the rate of radon in the air entering the water surface A 1 .

[0012] The present invention has the following advantages compared with the prior art: 1. The device for measuring the rate of radon in the air entering the water surface and the rate of radon in the water entering the air provided by the present invention has a simple structure, is easy to operate, and has a short measurement time.

[0013] 2. The present invention adopts an innovative two-stage measurement mode. By controlling the flow rate controller to be in the power-off fully open state until equilibrium is achieved, the radon concentration at the natural equilibrium of the system is obtained; and by controlling the flow rate controller to be in the normal working state to reach a new equilibrium and recording the radon concentration at the new equilibrium state, this two-mode measurement method of the flow rate controller effectively overcomes the limitation of the traditional static chamber method that can only obtain a single equilibrium state, and provides key data support for accurately calculating the bidirectional radon exchange rate.

[0014] The detailed structure of the present invention will be further described below in conjunction with the drawings and specific embodiments. Description of the Drawings

[0015] Figure 1 Schematic structural diagram of a device for measuring the rate at which radon in air enters water and the rate at which radon in water enters air; Figure 2 Top view of a static floating chamber. Detailed implementation manners

[0016] Example 1: As shown in Figure 1 - 2 , a device for measuring the rate at which radon in air enters water and the rate at which radon in water enters air includes a static floating chamber 1, an intake pipe 2, an outlet pipe 3, a foam board 4, a drying bottle 5, a RAD7 radon detector 6, and a flow rate controller 7. The foam board 4 is arranged around the static floating chamber 1 and fixedly connected to the static floating chamber 1, enabling the static floating chamber 1 to float on the water surface to be measured. A substance for drying gas, such as calcium chloride powder, etc., is placed in the drying bottle 5. The intake pipe 2 and the outlet pipe 3 are respectively installed on the static floating chamber 1. The outlet pipe 3 is connected to the intake end of the flow rate controller 7 through a hose. The outlet end of the flow rate controller 7 is connected to the intake end of the drying bottle 5. The outlet end of the drying bottle 5 is connected to the intake end of the RAD7 radon detector 6 through a hose. The outlet end of the RAD7 radon detector 6 is connected to the intake pipe 2 of the static floating chamber 1 through a hose.

[0017] Example 2: A method for applying the device for measuring the rate at which radon in air enters water and the rate at which radon in water enters air in Example 1 includes a measurement process and a calculation process. The specific steps are as follows: I. Measurement process A. Place the static floating chamber 1 and the surrounding foam board 4 on the surface layer of the water sample 8 to be measured. The flow rate controller 7 is in a power-off and fully open state. Start the pump of the RAD7 radon detector 6. The radon-containing air in the static floating chamber 1 enters the drying bottle 5 through the outlet pipe 3 under the action of the pump for drying, and then enters the RAD7 radon detector 6. When the radon concentration data measured by the RAD7 radon detector 6 tends to be stable, that is, when the system reaches equilibrium, record the radon concentration measured in the RAD7 radon detector 6 c(t) .

[0018] Disconnect the hose between the outlet end of the RAD7 radon detector 6 and the intake pipe 2 of the static floating chamber 1. When the flow rate controller 7 is in a normal working state, start the pump of the RAD7 radon detector 6. The radon-containing air in the static floating chamber 1 enters the drying bottle 5 through the outlet pipe 3 under the action of the pump for drying, and then enters the RAD7 radon detector 6. When the radon concentration data measured by the RAD7 radon detector 6 tends to be stable, that is, when the system reaches a new equilibrium state during the operation of the flow rate controller 7, record the radon concentration measured in the RAD7 radon detector 6 c’(t) .

[0019] C. When the surface water of the lower water surface of the static floating chamber 1 is used to measure the radon concentration by the bubbling method until equilibrium is reached, record the radon concentration and flow rate measured by the RAD7 radon detector.

[0020] II. Calculation process The radon in water mainly comes from the decay of radium dissolved in water. The radon in water is released into the air through the water-air interface, which is the precipitation of radon on the water surface. Since the volume of water is approximately infinite during the measurement process, assuming that the radon concentration in water remains unchanged when measuring the radon precipitation rate on the water surface, the radon concentration in the static floating chamber 1 is expressed by formula (1): (1) Wherein, c(t) represents the radon concentration in the static floating chamber 1, with the unit of Bq / m 3 ; A 1 represents the rate of radon in the air entering the water surface, with the unit of m / s; A 2 represents the rate of radon on the water surface entering the air, with the unit of m / s; c(H 2 o) represents the radon concentration in water, with the unit of Bq / m 3 ; V represents the volume of the gas path, including the volume of the gas path in the static floating chamber 1, the volume of the measurement chamber in the RAD7 radon detector 6, and the volume of the connecting pipeline, with the unit of m 3 ; S represents the surface area of the static floating chamber 1, with the unit of m 2 ; λ represents the radon decay constant, λ l represents the leakage coefficient.

[0021] When the system reaches equilibrium, there is the following expression: (2) After substituting formula (2) into formula (1), formula (1) is simplified to: (3) According to the literature, the distribution ratio of the gas radon concentration to the water radon concentration X can be expressed by the following formula: (4) Wherein, T represents the temperature during the measurement, which can be obtained through sensors, etc. Assuming that the radon concentration in the static floating chamber 1 is uniform and the radon concentration in the water body is uniform, according to formula (3) and formula (4), we can get: (5) When the surface area of the static floating chamber 1 is very large and the height is very low; and at the same time, the leakage is very small due to good sealing, S* A 1 / V much greater than λ and λ l , there is the following expression at this time: (6) When the flow rate controller 7 is started and the system reaches a new equilibrium state, the calculation expression of the radon concentration in the static floating chamber 1 is: (7) Where, c’(t) represents the radon concentration in the static floating chamber 1 at the new equilibrium state, with the unit of Bq / m 3 ; c’(H 2 o) represents the radon concentration in water at the new equilibrium state; L is the flow rate of the flow rate controller 7, with the unit of L / m 3 ; V 1 represents the volume of the static floating chamber 1, with the unit of m 3 ; c 0 is the radon concentration in the environment, with the unit of Bq / m 3 , however, since the radon concentration in the environment is very low and can be basically ignored, formula (7) can be simplified to: (8) When reaching the new equilibrium state, there is dc’(t) / dt = 0 , formula (8) can be transformed into: (9) When controlling the flow rate of the flow rate controller 7 such that L / V 1 much greater than S*A 1 / V 1 、λ and λ l at this time, formula (9) is transformed into: (10) Measure the radon concentration in water by the bubbling method c’(H 2 o) .

[0022] The measured radon concentration in water c(H 2o) Substituting into formula (10) gives the rate at which radon in water enters the air A 2 , on this basis, the rate at which radon in water enters the air A 2 Substituting into formula (6) gives the rate at which radon in the air enters the water surface A 1 .

Claims

1. A device for measuring the rate at which radon in air enters water and the rate at which radon in water enters air, characterized in that: It includes a static floating chamber, an intake pipe, an outlet pipe, a foam board, a drying bottle, a RAD7 radon detector, and a flow rate controller; the foam board is arranged around the static floating chamber and fixedly connected to the static floating chamber, a substance for drying gas is placed in the drying bottle, the intake pipe and the outlet pipe are respectively installed on the static floating chamber, the outlet pipe is connected to the intake end of the flow rate controller through a hose, the outlet end of the flow rate controller is connected to the intake end of the drying bottle, the outlet end of the drying bottle is connected to the intake end of the RAD7 radon detector through a hose, and the outlet end of the RAD7 radon detector is connected to the intake pipe of the static floating chamber through a hose.

2. The rate device for measuring the rate of radon in air entering the water surface and radon in water entering the air according to claim 1, characterized in that: The substance placed in the drying bottle is calcium chloride powder.

3. A method applied to the device for measuring the rate of radon in air entering the water surface and radon in water entering the air as described in claim 1 or 2, characterized in that: It includes a measurement process and a calculation process, and the specific steps are as follows. I. Measurement process A. Place the static floating chamber and the foam board around it on the water surface of the water sample to be measured. The flow rate controller is in the power-off and fully open state. Start the pump of the RAD7 radon detector. The radon-containing air in the static floating chamber enters the drying bottle through the outlet pipe under the action of the pump for drying, and then enters the RAD7 radon detector. When the radon concentration data measured by the RAD7 radon detector tend to be stable, that is, when the system reaches equilibrium, record the radon concentration measured in the RAD7 radon detector c(t) ; B. Disconnect the hose between the gas outlet end of the RAD7 radon detector and the intake pipe of the static floating chamber. With the flow rate controller in normal working condition, start the pump of the RAD7 radon detector. The radon-containing air in the static floating chamber enters the drying bottle through the outlet pipe under the action of the pump for drying, and then enters the RAD7 radon detector. When the radon concentration data measured by the RAD7 radon detector tends to be stable, that is, the system reaches a new equilibrium state when the flow rate controller is working, record the radon concentration measured in the RAD7 radon detector 6 c’ (t) ; C. When the radon concentration reaches equilibrium by using the bubbling method to measure the surface water of the lower water surface of the static floating chamber, record the radon concentration and flow rate measured by the RAD7 radon detector. II. Calculation process The radon in water mainly comes from the decay of radium dissolved in water. The radon in water is released into the air through the water-air interface, which is the precipitation of radon on the water surface. Since the water volume is approximately infinite during the measurement process, assuming that the radon concentration in water remains unchanged when measuring the radon precipitation rate on the water surface, the radon concentration in the static floating chamber is expressed by formula (1) at this time: （1） Among them, c(t) represents the radon concentration in the static floating chamber, with the unit of Bq / m 3 ; A 1 represents the rate at which radon in the air enters the water surface, with the unit of m / s; A 2 represents the rate at which radon in the water surface enters the air, with the unit of m / s; c(H 2 o) represents the radon concentration in the water, with the unit of Bq / m 3 ; V represents the volume of the gas path, including the volume of the gas path in the static floating chamber, the volume of the measurement chamber in the RAD7 radon detector, and the volume of the connecting pipeline, with the unit of m 3 ; S represents the surface area of the static floating chamber, with the unit of m 2 ; λ represents the radon decay constant, λ l represents the leakage coefficient; When the system reaches equilibrium, there is the following expression: （2） After substituting formula (2) into formula (1), formula (1) is simplified to: （3） According to the literature, the distribution ratio of the gas radon concentration to the water radon concentration can be known X , which is expressed by the following formula: （4） Among them, T represents the temperature during measurement. Assuming that the radon concentration in the static floating chamber 1 is uniform and the radon concentration in the water body is uniform, the following can be obtained according to Formula (3) and Formula (4): （5） When the surface area of the static floating chamber is very large, the height is very low, and it is well sealed so that the leakage is very small, S*A 1 / V much greater than λ and λ l , there is the following expression at this time: （6） When the flow rate controller is started and the system reaches a new equilibrium state, the calculation expression for the radon concentration in the static floating chamber is: （7） Wherein, c’(t) represents the radon concentration in the static floating chamber 1 at the new equilibrium state, with the unit of Bq / m 3 ; c’(H 2 o) represents the radon concentration in water at the new equilibrium state; L is the flow rate of the flow rate controller 7, with the unit of L / m 3 ; V 1 represents the volume of the static floating chamber 1, with the unit of m 3 ; c 0 is the radon concentration in the environment, with the unit of Bq / m 3 , however, since the radon concentration in the environment is very low and can be basically ignored, the formula (7) can be simplified to: （8） When a new equilibrium state is reached, there exists dc’(t) / dt = 0 , and Equation (8) can be transformed into: （9） When the flow rate of the control flow rate controller 7 makes L / V 1 much greater than S*A 1 / V 1 , λ and λ l at that time, formula (9) is transformed into: （10） The radon concentration in water is measured by the bubbling method c’(H 2 o) , and the measured radon concentration in water is substituted into formula (10) to obtain the rate of radon in water entering the air A 2 , and then A 2 is substituted into formula (6) to obtain the rate of radon in the air entering the water surface A 1 .

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