A sampling efficiency test system and method for an airborne radioactive sampling monitoring pipeline

Abstract

The embodiment of the present application provides a kind of sampling efficiency test system and method of airborne radioactive sampling monitoring pipeline, the system includes an aerosol generator for generating test particles, a test pipe section, test pipe section is according to the pipeline construction of airborne radioactive sampling monitoring prototype system, its gas inlet is communicated with aerosol generator by connecting pipeline;An outlet filter, the outlet filter is communicated with the gas outlet of test pipe section by connecting pipeline;Two particle size spectrometers, two particle size spectrometers are respectively arranged at the front side of the gas inlet of test pipe section and the rear side of the gas outlet connecting pipeline;A vacuum pump, the vacuum pump is communicated with the gas outlet of outlet filter by connecting pipeline;A flow meter, the flow meter is arranged on the connecting pipeline between outlet filter and vacuum pump.The embodiment of the present application provides effective support for realizing the accurate measurement of airborne radioactivity, ensuring operation and personnel radiation safety, and ensures the operation safety and personnel radiation safety of system.

Description

Technical Field

[0001] This invention relates to the field of multi-physics coupled radioactive source term analysis technology, and in particular to a sampling efficiency test system and method for an airborne radioactive sampling and monitoring pipeline. Background Technology

[0002] Nuclear energy is a clean, efficient, and sustainable strategic energy source, but it carries potential radioactive risks. An accident could have extremely serious consequences, and nuclear and radiation safety is an important prerequisite for the development of nuclear energy.

[0003] Nuclear power plants typically use pressurized water reactors to generate energy, and the production of radioactive materials is inevitable during operation. Multiple protective barriers are in place to prevent the leakage of radioactive materials from nuclear power plants, primarily including: fuel pellets and cladding, reactor and primary circuit pressure boundaries, and the containment building. Atmospheric radioactivity monitoring is a crucial means of monitoring leaks at the primary circuit pressure boundaries and atmospheric radioactivity levels within the containment building.

[0004] To achieve accurate measurement of airborne radioactivity within the containment and reduce the impact of background radiation on measurements, airborne radioactivity monitoring typically employs a method of "multi-point sampling, integrated monitoring, and external measurement." Due to the large space within the containment and the wide distribution of sampling points, typical locations within the containment must be selected for sampling and measurement to ensure representativeness. This results in complex sampling pipeline setups, which can affect the accuracy of the measurement results. Therefore, a corresponding "sampling efficiency" coefficient must be used to correct the sampling results.

[0005] Regarding the efficiency of airborne radioactive sampling, a computational model is typically used. This model combines empirical formulas for the sampling efficiency of individual components (derived from experimental data on individual component sampling efficiencies) to calculate the aerosol permeability of the entire sampling system. However, determining the sampling efficiency of the entire system using this method has significant uncertainties: First, the model uses empirical formulas for the sampling efficiency of individual components to obtain the sampling efficiency of the sampling pipeline system, without considering the influence between the combinations of components. The sampling efficiency of each component in the sampling pipeline system generally differs from the permeability when the component is used alone, because in a combined system, upstream components can affect downstream components. Second, for simple components such as straight pipes, the efficiency estimation based on empirical formulas is highly accurate, but for complex components such as bends, valves, and flow regulators, the efficiency estimation based on empirical formulas is highly uncertain. Third, the connections and manufacturing defects of components in the sampling pipeline system can affect airflow and thus aerosol permeability, and models based on empirical formulas are difficult to reflect the influence of these factors. Therefore, the results of calculation models based on empirical formulas may differ significantly from reality, making it difficult to guarantee accurate measurement of airborne radioactivity and posing potential risks to system operation safety and personnel radiation safety. Summary of the Invention

[0006] In view of the above-mentioned problems existing in the prior art, the present invention provides a sampling efficiency test system and method for airborne radioactivity sampling and monitoring pipelines, so as to solve the technical problems that exist in the prior art, such as the difficulty in determining the sampling efficiency of complex sampling systems, the difficulty in ensuring the accurate measurement of airborne radioactivity, and the potential hazards to system operation safety and personnel radiation safety.

[0007] This invention provides a sampling efficiency testing system for airborne radioactive sampling monitoring pipelines, comprising:

[0008] An aerosol generator, wherein the aerosol generator has a built-in generating solution of a certain concentration for generating experimental particles;

[0009] A test tube section, which is constructed according to the pipeline of the prototype system for airborne radioactive sampling and monitoring, is used to simulate the impact of the pipeline of the prototype system for airborne radioactive sampling and monitoring on the sampling efficiency of airborne radioactive monitoring. Its air inlet is connected to the aerosol generator through a connecting pipeline.

[0010] An outlet filter is connected to the air outlet of the test tube section via a connecting pipe;

[0011] Two particle size spectrometers are installed at the connection pipes at the front of the air inlet and the rear of the air outlet of the test tube section, respectively, to measure the particle size distribution and aerosol concentration at the inlet and outlet of the test tube section.

[0012] A vacuum pump, which is connected to the outlet of the outlet filter via a connecting pipeline, is used to provide a power source for aerosol sampling in a prototype system for simulating airborne radioactive sampling and monitoring.

[0013] A flow meter is installed on the connecting pipeline between the outlet filter and the vacuum pump to measure the aerosol sampling flow rate.

[0014] In one embodiment, a particle concentration adjustment device is also included.

[0015] In one embodiment, the particle concentration adjustment device includes,

[0016] A gas holder is provided, which is located between the aerosol generator and the test tube section, and the particle size analyzer is located downstream of the gas holder.

[0017] An induced draft fan is installed on the gas holder, and a particulate filter is installed at its air inlet. The induced draft fan is used to exhaust excess air in the gas holder, and the particulate filter is used to limit the escape of test particles from the air outlet of the induced draft fan, so as to achieve the adjustment of aerosol concentration in the gas holder.

[0018] In one embodiment, a valve is also included, which is disposed on the connecting pipeline between the outlet filter and the vacuum pump.

[0019] In one embodiment, the test tube section is constructed after simplification based on the prototype system pipeline for airborne radioactive sampling and monitoring. The simplification principle is that bends, valves, and flow meters in the prototype system pipeline are constructed according to the prototype system pipeline, and longer straight pipes in the prototype system pipeline are constructed according to the scaled-down length.

[0020] In one embodiment, the principle of scaling down the straight pipe is that the length of the straight pipe connected to the bend is not less than 10 times the diameter of the bend.

[0021] In addition, embodiments of the present invention also provide a sampling efficiency test method for a gaseous radioactive sampling and monitoring pipeline. A sampling efficiency test system for a gaseous radioactive sampling and monitoring pipeline, based on any embodiment of the present invention, includes the following steps:

[0022] Step S1: Simplify the pipeline of the airborne radioactive sampling and monitoring prototype system and construct the sampling and monitoring test system pipeline as the test section;

[0023] Step S2: Connect one of the test branches of the test tube section to the sampling efficiency test system;

[0024] Step S3: A standard particle size aerosol is generated using an aerosol generator;

[0025] Step S4: Aerosol measurement and sampling simulation. After confirming that the generated standard particles meet the requirements for particle size and particle concentration, start the vacuum pump to sample the constructed pipeline at the required flow rate.

[0026] Step S5: Measurement of aerosol particle size, concentration, and flow rate at the inlet and outlet. Sampling tubes are placed at the inlet and outlet of the test tube section and connected to the particle size analyzer. The particle size analyzer extracts gas at a constant flow rate and then measures the aerosol particle concentration.

[0027] Step S6: Repeat steps S2 to S5 until all branches to be tested in the test tube section are tested.

[0028] Step S7: Based on the obtained test data, perform test data processing and analysis to determine the sampling efficiency of each branch of the test tube section.

[0029] In one embodiment, step S3 further includes adjusting the standard particle size aerosol particle size and particle concentration to meet the requirements.

[0030] In one embodiment, step S2 further includes installing a particulate filter in the branch of the test tube section that is not connected to the sampling efficiency test system and connecting it to the atmospheric environment.

[0031] Compared with the prior art, the beneficial effects of the sampling efficiency test system and method for airborne radioactivity sampling and monitoring pipeline provided by the embodiments of the present invention are as follows: The embodiments of the present invention propose a practical sampling efficiency test system and method that can be applied to airborne radioactivity monitoring in land-based nuclear power plants and floating nuclear power units, providing effective support for accurate measurement of airborne radioactivity and ensuring operational and personnel radiation safety, thus ensuring the operational safety of the system and the radiation safety of personnel. Attached Figure Description

[0032] Figure 1 A schematic diagram of the sampling efficiency test system for an airborne radioactive sampling and monitoring pipeline provided in an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of a typical airborne radioactive sampling and monitoring prototype system pipeline involved in a sampling efficiency test system for an airborne radioactive sampling and monitoring pipeline provided in an embodiment of the present invention.

[0034] Figure 3 This is a schematic diagram of the sampling efficiency test system pipeline for an airborne radioactive sampling and monitoring pipeline provided in an embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Various embodiments and features of this application are described herein with reference to the accompanying drawings.

[0037] These and other features of this application will become apparent from the following description of preferred forms of embodiments given as non-limiting examples, with reference to the accompanying drawings.

[0038] It should also be understood that although this application has been described with reference to some specific examples, those skilled in the art can certainly implement many other equivalent forms of this application, which have the features described in the claims and are therefore all within the scope of protection defined herein.

[0039] The above and other aspects, features and advantages of this application will become more apparent when taken in conjunction with the accompanying drawings and in view of the following detailed description.

[0040] Specific embodiments of this application are described below with reference to the accompanying drawings; however, it should be understood that the claimed embodiments are merely examples of this application, which can be implemented in various ways. Well-known and / or repeated functions and structures are not described in detail to ascertain the true intent based on the user's historical operations, and to avoid unnecessary or redundant details that would obscure this application. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but merely serve as the basis and representative basis for the claims to teach those skilled in the art to use this application in various ways with substantially any suitable detailed structure.

[0041] This specification may use the phrases “in one embodiment,” “in another embodiment,” “in yet another embodiment,” or “in other embodiments,” all of which may refer to one or more of the same or different embodiments according to this application.

[0042] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments described are for illustrative purposes only and are not intended to limit the scope of the invention. The following description, in conjunction with... Figure 1-3 The preferred embodiments of the present invention will be described in further detail below:

[0043] like Figure 2-3As shown, this embodiment of the invention proposes principles and methods for determining the sampling and monitoring test system pipeline for a typical airborne radioactive sampling and monitoring system in a reactor compartment. The sampling and monitoring system pipeline needs to be configured with sampling points based on typical radioactive leakage-prone locations within the containment. The large number of sampling points required results in a large span and complex layout of the pipeline. Therefore, when conducting sampling efficiency tests on the sampling and monitoring system pipeline, it is necessary to simplify the pipeline. The main simplification principles are as follows: 1) For components that significantly affect sampling efficiency, such as bends, valves, and flow meters, the test system pipeline should be constructed according to the prototype system pipeline; 2) For longer straight pipes, the sampling and monitoring test system pipeline should be constructed on a scaled-down basis, with the scaling-down principle being: the length of the straight pipe connected to the bend should not be less than 10 times the diameter of the bend.

[0044] like Figure 1 As shown, to address the sampling efficiency testing requirements under different operating conditions such as temperature and humidity, this embodiment of the invention provides a sampling efficiency testing system for an airborne radioactive sampling monitoring pipeline, comprising:

[0045] An aerosol generator (particle generator) has a built-in generating solution of a certain concentration for generating experimental particles to simulate the generation of radioactive aerosols.

[0046] A test tube section, which is constructed according to the pipeline of the prototype system for airborne radioactive sampling and monitoring, is used to simulate the impact of the pipeline of the prototype system for airborne radioactive sampling and monitoring on the sampling efficiency of airborne radioactive monitoring. Its air inlet is connected to the aerosol generator through a connecting pipeline.

[0047] An outlet filter is provided, which is connected to the air outlet of the test tube section via a connecting pipe. The outlet filter is used to filter and adsorb excess aerosols to prevent them from polluting the environment.

[0048] Two particle size spectrometers are installed at the connection points of the air inlet and outlet of the test tube section, respectively, to measure the particle size distribution and aerosol concentration at the inlet and outlet of the test tube section, and to determine the sampling efficiency of the sampling monitoring system pipeline accordingly.

[0049] A vacuum pump, which is connected to the outlet of the outlet filter via a connecting pipeline, is used to provide a power source for aerosol sampling in a prototype system for simulating airborne radioactive sampling and monitoring.

[0050] A flow meter is installed on the connecting pipeline between the outlet filter and the vacuum pump to measure the aerosol sampling flow rate, so as to ensure that the sampling flow rate of the sampling monitoring test system is consistent with that of the sampling monitoring prototype system.

[0051] In one embodiment, to meet the sampling efficiency testing requirements for aerosols of different particle sizes and concentrations, a particle concentration adjustment device is further included. Specifically, in one embodiment, the particle concentration adjustment device includes...

[0052] A gas holder is provided, which is located between the aerosol generator and the test tube section, and the particle size analyzer is located downstream of the gas holder.

[0053] An induced draft fan is installed on the gas holder, and a particulate filter is installed at its air inlet. The induced draft fan is used to exhaust excess air in the gas holder, and the particulate filter is used to limit the escape of test particles from the air outlet of the induced draft fan in order to achieve the adjustment of aerosol concentration in the gas holder.

[0054] In this embodiment, the induced draft fan and the gas holder also serve to transport aerosols and maintain their concentration stably.

[0055] In one embodiment, a valve is also included, which is disposed on the connecting pipeline between the outlet filter and the vacuum pump. By adding the valve, the safety of the entire test system can be improved and the pipeline on / off control can be better realized.

[0056] In one embodiment, the test tube section is constructed after simplification based on the pipeline of the prototype airborne radioactive sampling and monitoring system. The simplification principle is that bends, valves, and flow meters in the prototype system pipeline are constructed according to the prototype system pipeline, and longer straight pipes in the prototype system pipeline are constructed according to the scaled-down length. Specifically, in one embodiment, the scaling-down principle of the straight pipe is that the length of the straight pipe connected to the bend is not less than 10 times the diameter of the bend.

[0057] In addition, embodiments of the present invention also provide a sampling efficiency test method for a gaseous radioactive sampling and monitoring pipeline. A sampling efficiency test system for a gaseous radioactive sampling and monitoring pipeline, based on any embodiment of the present invention, includes the following steps:

[0058] Step S1: Simplify the pipeline of the airborne radioactive sampling and monitoring prototype system and construct the sampling and monitoring test system pipeline as the test section;

[0059] Step S2: Connect one of the test branches of the test tube section to the sampling efficiency test system, and at the same time, connect the remaining branches that are not connected to the sampling efficiency test system to the atmospheric environment by setting particulate filters.

[0060] Step S3: A standard particle size aerosol is generated by an aerosol generator, and the particle size and concentration of the standard particle size aerosol are adjusted to meet the requirements. The test particles are generated by the aerosol generator (particle generator). During normal operation, the particle number concentration needs to be controlled within a reasonable range to eliminate the possibility of agglomeration due to excessive particle number concentration. Under the condition that the concentration of the generating solution and the generator parameters remain unchanged, the particle size of the generated particles does not change much.

[0061] Step S4, aerosol measurement sampling simulation: After confirming that the generated standard particles meet the requirements for particle size and particle concentration, start the vacuum pump to sample the built pipeline at the required flow rate. The number of samplings depends on the size of the generated particles and the accuracy of the subsequent mass analysis measurement. In principle, the number of samplings should be as many as possible to improve the accuracy of the mass analysis measurement.

[0062] Step S5: Measure the inlet and outlet aerosol particle size, concentration, and flow rate. Sampling tubes are placed at the inlet and outlet of the test tube section and connected to a particle size analyzer. The particle size analyzer extracts gas at a constant flow rate and then measures the aerosol particle concentration. The aerosol concentrations measured at the inlet and outlet are C0 and C1, respectively. in C out The flow rates are q i For multi-pipe sampling efficiency tests, the branch to be tested is connected to the aerosol generation system, while other branches are connected to the atmospheric environment with filters. The aerosol concentration (C) of each branch is then obtained. in C out ) and flow rate (q) i 、q0);

[0063] Step S6: Repeat steps S2 to S5 until all branches to be tested in the test tube section are tested.

[0064] Step S7: Based on the obtained test data, perform test data processing and analysis to determine the sampling efficiency of each branch of the test tube section.

[0065] The sampling efficiency of a single sampling loop can be obtained using Formula 1.

[0066] For straight pipelines, the aerosol sampling efficiency follows an exponential relationship with the pipeline length, as shown in Formula 2.

[0067] Formula 3 can be used to obtain the total sampling efficiency when multiple sampling pipelines are sampling simultaneously.

[0068]

[0069] In the formula,

[0070] P is the sampling efficiency for a single sampling loop, which is dimensionless.

[0071] Ci Aerosol concentration at the sampling inlet, unit: n / cm³ 3 ;

[0072] C o aerosol concentration at the sampling outlet, unit: n / cm³ 3 .

[0073] P L =P0e -kL (Equation 2)

[0074] In the formula:

[0075] L is the length of the sampling straight pipeline, in meters;

[0076] P L The sampling efficiency is given by a straight pipe of length L, and is dimensionless.

[0077] P0 is the sampling efficiency per unit length of the straight pipe, which is dimensionless.

[0078] K is a constant related to parameters such as sampling flow rate and pipe inner diameter. When the sampling flow rate and pipe inner diameter are constant, K is a definite constant. By fitting the sampling efficiency results of straight pipes of different lengths using the above form, an empirical formula for the penetration coefficient of long straight pipes can be determined. This formula can be used as a reference for the accuracy correction of sampling efficiency calculations or test results for other lengths.

[0079] The sampling efficiency of multi-branch sampling pipelines is calculated according to Formula 3:

[0080]

[0081] In the formula:

[0082] P is the total sampling efficiency when multiple sampling pipelines sample simultaneously, which is dimensionless.

[0083] C0 represents the aerosol concentration at the sampling outlet, in units of n / cm³. 3 ;

[0084] q0 is the flow rate at the sampling outlet, in cm³. 3 / min;

[0085] C i Here is the aerosol concentration at the sampling inlet of branch i, where i is the branch number, and the unit is n / cm. 3 ;

[0086] q i Here is the flow rate at the sampling inlet of branch i, where i is the branch number, and the unit is cm. 3 / min;

[0087]

[0088] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. A sampling efficiency testing system for an airborne radioactive sampling and monitoring pipeline, characterized in that, include: An aerosol generator, wherein the aerosol generator has a built-in generating solution of a certain concentration for generating experimental particles; A test tube section, which is constructed according to the pipeline of the prototype system for airborne radioactive sampling and monitoring, is used to simulate the impact of the pipeline of the prototype system for airborne radioactive sampling and monitoring on the sampling efficiency of airborne radioactive monitoring. Its air inlet is connected to the aerosol generator through a connecting pipeline. An outlet filter is connected to the air outlet of the test tube section via a connecting pipe; Two particle size spectrometers are installed at the connection pipes at the front of the air inlet and the rear of the air outlet of the test tube section, respectively, to measure the particle size distribution and aerosol concentration at the inlet and outlet of the test tube section. A vacuum pump, which is connected to the outlet of the outlet filter via a connecting pipeline, is used to provide a power source for aerosol sampling in a prototype system for simulating airborne radioactive sampling and monitoring. A flow meter is installed on the connecting pipeline between the outlet filter and the vacuum pump to measure the aerosol sampling flow rate.

2. The sampling efficiency testing system for a gaseous radioactive sampling and monitoring pipeline according to claim 1, characterized in that: It also includes a particle concentration adjustment device.

3. The sampling efficiency testing system for a gaseous radioactive sampling and monitoring pipeline according to claim 2, characterized in that: The particle concentration adjustment device includes, A gas holder is provided, which is located between the aerosol generator and the test tube section, and the particle size analyzer is located downstream of the gas holder. An induced draft fan is installed on the gas holder, and a particulate filter is installed at its air inlet. The induced draft fan is used to exhaust excess air in the gas holder, and the particulate filter is used to limit the escape of test particles from the air outlet of the induced draft fan, so as to achieve the adjustment of aerosol concentration in the gas holder.

4. The sampling efficiency testing system for a gaseous radioactive sampling and monitoring pipeline according to claim 1, characterized in that: It also includes a valve, which is located on the connecting pipe between the outlet filter and the vacuum pump.

5. The sampling efficiency testing system for a gaseous radioactive sampling and monitoring pipeline according to claim 1, characterized in that: The test tube section was constructed after simplification based on the prototype system pipeline for airborne radioactive sampling and monitoring. The simplification principle was that bends, valves, and flow meters in the prototype system pipeline were constructed according to the prototype system pipeline, and longer straight pipes in the prototype system pipeline were constructed according to the scaled-down length.

6. The sampling efficiency testing system for a gaseous radioactive sampling and monitoring pipeline according to claim 5, characterized in that: The principle for scaling down straight pipes is that the length of the straight pipe connected to the bend should not be less than 10 times the diameter of the bend.

7. A method for testing the sampling efficiency of a gaseous radioactive sampling and monitoring pipeline, based on the sampling efficiency testing system for a gaseous radioactive sampling and monitoring pipeline as described in any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Simplify the pipeline of the airborne radioactive sampling and monitoring prototype system and construct the sampling and monitoring test system pipeline as the test section; Step S2: Connect one of the test branches of the test tube section to the sampling efficiency test system; Step S3: A standard particle size aerosol is generated using an aerosol generator; Step S4: Aerosol measurement and sampling simulation. After confirming that the generated standard particles meet the requirements for particle size and particle concentration, start the vacuum pump to sample the constructed pipeline at the required flow rate. Step S5: Measurement of aerosol particle size, concentration, and flow rate at the inlet and outlet. Sampling tubes are placed at the inlet and outlet of the test tube section and connected to the particle size analyzer. The particle size analyzer extracts gas at a constant flow rate and then measures the aerosol particle concentration. Step S6: Repeat steps S2 to S5 until all branches to be tested in the test tube section are tested. Step S7: Based on the obtained test data, perform test data processing and analysis to determine the sampling efficiency of each branch of the test tube section.

8. The sampling efficiency test method for a gaseous radioactive sampling and monitoring pipeline according to claim 7, characterized in that: Step S3 further includes adjusting the standard particle size aerosol particle size and particle concentration to meet the requirements.

9. The sampling efficiency test method for a gaseous radioactive sampling and monitoring pipeline according to claim 7, characterized in that: Step S2 further includes installing a particulate filter on the branch of the test tube section that is not connected to the sampling efficiency test system and connecting it to the atmospheric environment.

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