System and method for testing sampling efficiency of airborne radioactive sampling monitoring pipeline

Abstract

The embodiment of the invention provides a sampling efficiency test system and method for an airborne radioactivity sampling monitoring pipeline, and the system comprises an aerosol generator used for generating test particles, and a test tube section which is constructed according to an airborne radioactivity sampling monitoring prototype system pipeline. The air inlet is communicated with the aerosol generator through a connecting pipeline; the outlet filter is communicated with the air outlet of the test tube section through a connecting pipeline; the two particle size spectrometers are respectively arranged at the connecting pipelines at the front side of the air inlet and the rear side of the air outlet of the test tube section; the vacuum pump is communicated with the air outlet of the outlet filter through a connecting pipeline; and the flowmeter is arranged on a connecting pipeline between the outlet filter and the vacuum pump. According to the embodiment of the invention, effective support is provided for realizing accurate measurement of airborne radioactivity, ensuring operation and personnel radiation safety and the like, and the operation safety of the system and the personnel radiation safety are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of multi-physical field coupling radioactive source term analysis, and particularly relates to a sampling efficiency test system and method for a gas-borne radioactive sampling monitoring pipeline. BACKGROUND

[0002] Nuclear energy is a clean and efficient high-tech strategic energy that can realize sustainable power supply, but it has potential radioactive risks, and once an accident occurs, it will have extremely serious consequences. Nuclear and radiation safety is an important prerequisite for the development of nuclear energy.

[0003] Nuclear power plants usually use pressurized water reactors to generate energy, and inevitably produce radioactive substances during operation. To prevent the leakage of radioactive substances produced by nuclear power plants, multiple protective barriers are set, mainly including fuel pellets and cladding, reactor and primary circuit pressure boundary, and containment. Airborne radioactive monitoring is an important means to monitor the leakage of the primary circuit pressure boundary and the atmospheric radioactivity level of the containment.

[0004] To achieve accurate measurement of airborne radioactivity in the containment and reduce the influence of the background of the radiation environment in the containment on the measurement, airborne radioactive monitoring usually uses the method of "multi-point sampling, integrated monitoring, and out-of-shell measurement" for measurement. Due to the large space of the containment and the wide distribution of the sampling points, to ensure the representativeness of the sampling process, typical parts in the containment need to be selected for sampling measurement, which leads to the complexity of the setting of the sampling pipeline for monitoring and has a certain influence on the accuracy of the measurement results, so the corresponding "sampling efficiency" coefficient must be used to correct the sampling results.

[0005] Regarding the sampling efficiency of airborne radioactivity, a calculation model is usually used to obtain the aerosol transmission rate of the entire sampling system by combining empirical formulas of the sampling efficiency of individual components (empirical formulas of the sampling efficiency of individual components are obtained from experiments on the sampling efficiency of individual components). However, there are great uncertainties in determining the sampling efficiency of the sampling system in this way: first, the model uses empirical formulas of the sampling efficiency of individual components to obtain the sampling efficiency of the sampling pipeline system, without considering the influence of the combination of components. The sampling efficiency of each component in the sampling pipeline system is generally different from the transmission rate when the component is used alone, because the upstream component will have an influence on the downstream component in the system combination state. Second, for simple components such as straight pipelines, the accuracy of efficiency estimation based on empirical formulas is high, but for complex components such as elbow pipes, valves, and flow regulators, the uncertainty of efficiency estimation using empirical formulas is large. Third, the connection of components in the sampling pipeline system and manufacturing defects can affect the airflow and in turn affect the aerosol transmission rate, and the model based on empirical formulas is difficult to reflect the influence of these factors. Therefore, the results of the calculation model based on empirical formulas can be significantly different from the actual situation, making it difficult to ensure accurate measurement of airborne radioactivity, which poses a risk to the safe operation of the system and the radiation safety of personnel. SUMMARY

[0006] In view of the above problems existing in the prior art, the embodiments of the present application provide a sampling efficiency test system and method for a sampling monitoring pipeline of airborne radioactivity to solve the technical problems that the sampling efficiency of a complex sampling system is difficult to determine in the prior art, accurate measurement of airborne radioactivity is difficult to ensure, and risks exist in the safe operation of the system and the radiation safety of personnel.

[0007] The embodiments of the present application provide a sampling efficiency test system for a sampling monitoring pipeline of airborne radioactivity, comprising:

[0008] An aerosol generator, the aerosol generator is built-in with a solution of a certain concentration, and is used to generate particles for testing;

[0009] A test pipe section, the test pipe section is constructed according to the pipeline of a prototype system for monitoring airborne radioactivity, and is used to simulate the influence of the pipeline of the prototype system for monitoring airborne radioactivity on the sampling efficiency of airborne radioactivity monitoring, and the air inlet thereof is communicated with the aerosol generator through a connecting pipeline;

[0010] An outlet filter, the outlet filter is communicated with the air outlet of the test pipe section through a connecting pipeline;

[0011] Two particle size spectrometers, the two particle size spectrometers are respectively arranged at the connecting pipelines before the air inlet and after the air outlet of the test pipe section, and are used to measure the particle size distribution and aerosol concentration at the inlet and outlet of the test pipe section;

[0012] a vacuum pump, which is communicated with the outlet filter gas outlet through a connecting pipeline, and is used for providing a power source for aerosol sampling of the prototype system pipeline of the airborne radioactive sampling and monitoring system;

[0013] a flow meter, which is arranged on the connecting pipeline between the outlet filter and the vacuum pump, and is used for measuring the aerosol sampling flow.

[0014] In an embodiment, a particle concentration adjusting device is further included.

[0015] In an embodiment, the particle concentration adjusting device includes,

[0016] a gas cabinet, which is arranged between the aerosol generator and the test tube section, and the particle size spectrometer is located downstream of the gas cabinet;

[0017] an air induction fan, which is arranged on the gas cabinet, and a particle filter is arranged at an air inlet of the air induction fan, the air induction fan is used for discharging excess air in the gas cabinet, and the particle filter is used for limiting the test particles in the gas cabinet from escaping from an air outlet of the air induction fan, so as to realize the aerosol concentration adjustment in the gas cabinet.

[0018] In an embodiment, a valve is further included, which is arranged on the connecting pipeline between the outlet filter and the vacuum pump.

[0019] In an embodiment, the test tube section is constructed according to the simplified prototype system pipeline, and the simplification principle is that, for the elbow, valve and flow meter in the prototype system pipeline, the prototype system pipeline is constructed, and for the longer straight pipeline in the prototype system pipeline, the length is constructed according to the scaled length.

[0020] In an embodiment, the scaling principle of the straight pipeline is that, the length of the straight pipeline connected with the elbow is not less than 10 times of the diameter of the elbow.

[0021] In addition, the embodiment of the present application further provides a sampling efficiency test method of the airborne radioactive sampling and monitoring pipeline, which is based on the sampling efficiency test system of the airborne radioactive sampling and monitoring pipeline according to any embodiment of the present application, and includes the following steps:

[0022] Step S1, the sampling monitoring test system pipeline is constructed as the test tube section according to the simplified prototype system pipeline of the airborne radioactive sampling and monitoring system;

[0023] Step S2, one to-be-measured branch of the test tube section is connected to the sampling efficiency test system;

[0024] Step S3, the standard particle size aerosol is generated through the aerosol generator;

[0025] Step S4, aerosol measurement sampling simulation, after confirming that the generated standard particles meet the particle size and particle concentration requirements, start the vacuum pump to test the required flow rate on the built pipeline for sampling;

[0026] Step S5, inlet and outlet aerosol particle size and solubility, flow measurement, respectively, arrange sampling tubes at the inlet and outlet of the test pipe section connected to the particle size spectrometer, and measure the aerosol particle concentration after the particle size spectrometer extracts gas at a constant flow rate;

[0027] Step S6, repeat steps S2 to S5 until all branches of the test pipe section to be tested are tested;

[0028] Step S7, according to the obtained test data, perform test data processing and analysis to determine the sampling efficiency of each branch of the test pipe section.

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

[0030] In an embodiment, the step S2 further comprises setting a particle filter in the branch of the test pipe section not connected to the sampling efficiency test system and connecting it to the atmospheric environment.

[0031] Compared with the prior art, the sampling efficiency test system and method for airborne radioactive sampling monitoring pipeline provided by the embodiment of the present application has the beneficial effects that the embodiment of the present application provides a practical sampling efficiency test system and method, which can be applied to airborne radioactive monitoring in land-based nuclear power plants and floating nuclear power devices, provides effective support for accurate measurement of airborne radioactivity, ensures operation and personnel radiation safety, and ensures the operation safety and personnel radiation safety of the system. BRIEF DESCRIPTION OF DRAWINGS

[0032] Fig. 1 The structure diagram of the sampling efficiency test system for airborne radioactive sampling monitoring pipeline provided by the embodiment of the present application;

[0033] Fig. 2 The schematic diagram of the typical airborne radioactive sampling monitoring prototype system pipeline involved in the sampling efficiency test system for airborne radioactive sampling monitoring pipeline provided by the embodiment of the present application;

[0034] Fig. 3 The schematic diagram of the sampling monitoring test system pipeline involved in the sampling efficiency test system for airborne radioactive sampling monitoring pipeline provided by the embodiment of the present application. DETAILED DESCRIPTION

[0035] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be described in detail below in combination with the drawings and specific embodiments.

[0036] Various aspects and features of the present application are described herein with reference to the drawings.

[0037] These and other characteristics of the present application will become apparent from the following description of the preferred forms given, by way of non-limiting example only, with reference to the attached drawings.

[0038] It is also to be understood that even though a number of examples of aspects of this application have been described herein, the application covers all possible combinations and sub-combinations of the various features and characteristics described herein.

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

[0040] Specific embodiments of the present application are described hereinafter; however, it is to be understood that the application is not limited to the particular embodiments described and that the application can be practiced with modification and alteration, and is capable of being practiced by other than the particular embodiments described herein. Accordingly, the specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present application.

[0041] The specification can use phrases such as "in one embodiment", "in another embodiment", "in yet another embodiment", or "in other embodiments", which can refer to one or more of the same or different embodiments of the application.

[0042] The principles and advantages of the present application will be described in the following detailed description of the application, in conjunction with the accompanying drawings, in which: Figs. 1-3 The preferred embodiments of the present application will be further described in detail with reference to the following examples:

[0043] As Figs. 2-3As shown, the embodiment of the present application proposes a determination principle and method for the sampling monitoring test system pipeline of the typical stack cabin airborne radioactive sampling monitoring system. The sampling monitoring system pipeline needs to set sampling points according to the typical radioactive leakage-prone parts in the containment, and the sampling point parts need to be set, which leads to large span and complex arrangement of the sampling monitoring system pipeline. Therefore, when the sampling efficiency test of the sampling monitoring system pipeline is carried out, the sampling monitoring system pipeline needs to be simplified. The main simplification principles are as follows: 1) for the components such as bend pipe, valve and flow meter which have greater influence on sampling efficiency, the test system pipeline is constructed according to the prototype system pipeline; 2) for the long straight pipe, the sampling monitoring test system pipeline is constructed by scaling, and the scaling principle is that the length of the straight pipe connected with the bend pipe is not less than 10 times the diameter of the bend pipe.

[0044] As shown in Fig. 1 , for the sampling efficiency test requirements under different temperature and humidity conditions, the embodiment of the present application provides a sampling efficiency test system for the airborne radioactive sampling monitoring pipeline, which comprises:

[0045] An aerosol generator, the aerosol generator (particle generator) is built-in with a certain concentration of generating solution, which is used to generate test particles to simulate the generation of radioactive aerosol;

[0046] A test pipe section, the test pipe section is constructed according to the airborne radioactive sampling monitoring prototype system pipeline, which is used to simulate the influence of the airborne radioactive sampling monitoring prototype system pipeline on the sampling efficiency of the airborne radioactive monitoring, and the air inlet thereof is communicated with the aerosol generator through a connecting pipeline;

[0047] An outlet filter, the outlet filter is communicated with the air outlet of the test pipe section through a connecting pipeline, and the outlet filter is used to filter and adsorb excess aerosol to avoid pollution of the environment;

[0048] Two particle size spectrometers, the two particle size spectrometers are respectively arranged at the front side of the air inlet of the test pipe section and the rear side of the air outlet of the test pipe section, and are arranged at the connecting pipeline, which are used to measure the particle size distribution and aerosol concentration at the inlet and outlet of the test pipe section, and determine the sampling efficiency of the sampling monitoring system pipeline according to the measurement results;

[0049] A vacuum pump, the vacuum pump is communicated with the air outlet of the outlet filter through a connecting pipeline, which is used to simulate the power source of the aerosol sampling of the airborne radioactive sampling monitoring prototype system pipeline;

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

[0051] In an embodiment, the sampling efficiency test requirements of aerosols with different particle sizes and different concentrations also include a particle concentration adjusting device. Specifically, in an embodiment, the particle concentration adjusting device includes,

[0052] A gas cabinet is arranged between the aerosol generator and the test tube section, and the particle size spectrometer is located downstream of the gas cabinet.

[0053] An air induction fan is arranged on the gas cabinet, and a particle filter is arranged at the air inlet of the air induction fan. The air induction fan is used to exhaust excess air in the gas cabinet, and the particle filter is used to limit the test particles in the gas cabinet from escaping from the air outlet of the air induction fan, so as to adjust the aerosol concentration in the gas cabinet.

[0054] In this embodiment, the air induction fan and the gas cabinet also have the function of transporting aerosols and maintaining the stability of the aerosol concentration.

[0055] In an embodiment, a valve is arranged 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 achieved.

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

[0057] In addition, the embodiment of the present application also provides a sampling efficiency test method of an airborne radioactive sampling and monitoring pipeline, based on the sampling efficiency test system of the airborne radioactive sampling and monitoring pipeline according to any embodiment of the present application, including the following steps:

[0058] Step S1: constructing the sampling monitoring test system pipeline as the test tube section according to the simplified pipeline of the airborne radioactive sampling and monitoring prototype system;

[0059] Step S2: connecting one to-be-measured branch of the test tube section to the sampling efficiency test system, and arranging particle filters on the remaining branches not connected to the sampling efficiency test system and connecting them to the atmospheric environment;

[0060] Step S3, a standard particle size aerosol is generated by the aerosol generator, and the standard particle size aerosol particle size and particle concentration are adjusted to meet the requirements. The test particles are generated by the aerosol generator (particle generator). When working normally, the particle number concentration needs to be controlled within a reasonable range to exclude the possibility of coagulation due to excessively high particle number concentration. Under the condition that the solution concentration and the generator parameters remain unchanged, the particle size of the generated particles does not change substantially.

[0061] Step S4, aerosol measurement sampling simulation. After confirming that the generated standard particles meet the particle size and particle concentration requirements, start the vacuum pump to sample the pipeline at the required flow rate. The sampling frequency is determined by the size of the generated particles and the accuracy of the subsequent mass analysis measurement. To improve the accuracy of mass analysis measurement, the sampling frequency should be as high as possible in principle.

[0062] Step S5, inlet and outlet aerosol particle size and solubility, flow measurement. Sampling tubes are arranged at the inlet and outlet of the test pipe section and connected to the particle size spectrometer. The particle size spectrometer measures the aerosol particle concentration at a constant flow rate. The measured aerosol concentrations at the inlet and outlet are C in and C out , respectively, and the flow rates are q i and q0, respectively. For multi-pipeline sampling efficiency testing, the branch to be tested is connected to the aerosol generation system, while the other branches are set with filters connected to the atmospheric environment to obtain the aerosol concentrations (C in and C out ) and flow rates (q i and q0), respectively.

[0063] Step S6, repeat steps S2 to S5 until all test branches of the test pipe 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 pipe section.

[0065] Wherein, the sampling efficiency of a single sampling circuit can be obtained using formula 1.

[0066] For a straight pipeline, the aerosol sampling efficiency follows an exponential law with the pipeline length, as shown in formula 2.

[0067] The total sampling efficiency of multiple sampling pipelines when sampling simultaneously can be obtained using formula 3.

[0068]

[0069] In the formula,

[0070] P is the sampling efficiency of a single sampling circuit, dimensionless.

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

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

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

[0074] In the formula:

[0075] L is the length of the sampling straight pipe, unit: m;

[0076] P L is the sampling efficiency of the sampling straight pipe with length L, dimensionless;

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

[0078] K is a constant related to the sampling flow rate, pipe inner diameter and other parameters, when the sampling flow rate and pipe inner diameter are constant, K is a certain constant. The sampling efficiency results of straight pipes with different lengths are fitted by the above formula to determine the empirical formula of the long straight pipe penetration coefficient, which can be used for the calculation of sampling efficiency of other lengths or the accuracy correction reference of test results.

[0079] For the sampling efficiency of the multi-branch sampling pipe, the sampling efficiency calculation is carried out according to Formula 3:

[0080]

[0081] In the formula:

[0082] P is the total sampling efficiency when the multi-branch sampling pipe is simultaneously sampled, dimensionless;

[0083] C0 is the aerosol concentration at the sampling outlet, unit: n / cm 3 ;

[0084] q0 is the flow rate at the sampling outlet, unit: cm 3 / min;

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

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

[0087]

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

Claims

1. A sampling efficiency test system for an airborne radioactivity sampling monitoring pipeline, characterized in that: include: an aerosol generator containing a generating solution of a certain concentration for generating test particles; a test tube section, constructed according to the pipeline of the prototype system for sampling and monitoring airborne radioactivity, used to simulate the effect of the pipeline of the prototype system for sampling and monitoring airborne radioactivity on the sampling efficiency of airborne radioactivity monitoring, and wherein the air inlet of the test tube section is connected to the aerosol generator via a connecting pipeline; an outlet filter, the outlet filter being connected to the air outlet of the test tube section through a connecting pipeline; Two particle size spectrometers are respectively arranged at the connecting pipes in front of the air inlet and at the rear of the air outlet of the test tube section, and are used to measure the particle size distribution and aerosol concentration at the inlet and outlet of the test tube section; a vacuum pump, the vacuum pump being connected to the air outlet of the outlet filter through a connecting pipeline, and being used to simulate the pipeline of the prototype system for sampling and monitoring airborne radioactivity to provide a power source for aerosol sampling; A flow meter is provided on the connecting pipeline between the outlet filter and the vacuum pump, and is used to measure the aerosol sampling flow rate.

2. The sampling efficiency test system for an airborne radioactivity sampling monitoring pipeline according to claim 1, characterized in that: The invention also includes a particle concentration regulating device.

3. The sampling efficiency test system for an airborne radioactivity sampling monitoring pipeline according to claim 2, characterized in that: The particle concentration regulating device comprises: a gas cabinet, wherein the gas cabinet is arranged between the aerosol generator and the test tube section, and the particle size spectrometer is located downstream of the gas cabinet; An induced draft fan is installed on the gas cabinet, and a particle filter is provided at its air inlet. The induced draft fan is used to exhaust excess air in the gas cabinet, and the particle filter is used to limit the test particles in the gas cabinet from escaping from the induced draft fan outlet to achieve aerosol concentration regulation in the gas cabinet.

4. The sampling efficiency test system for an airborne radioactivity sampling monitoring pipeline according to claim 1, characterized in that: The device also includes a valve, which is arranged on the connecting pipeline between the outlet filter and the vacuum pump.

5. The sampling efficiency test system for an airborne radioactivity sampling monitoring pipeline according to claim 1, characterized in that: The test pipe section is constructed after simplifying the pipeline of the prototype system for sampling and monitoring airborne radioactivity. The simplification principle is that the bends, valves and flow meters in the prototype system pipeline are constructed according to the prototype system pipeline, and the longer straight pipes in the prototype system pipeline are constructed according to the scaled-down length.

6. The sampling efficiency test system for an airborne radioactivity sampling monitoring pipeline according to claim 5, characterized in that: The scaling principle of the straight pipe is that the length of the straight pipe connected to the elbow is not less than 10 times the diameter of the elbow.

7. A sampling efficiency test method for an airborne radioactivity sampling and monitoring pipeline, based on a sampling efficiency test system for an airborne radioactivity sampling and monitoring pipeline according to any one of claims 1 to 6, characterized in that: The steps include: Step S1, constructing a sampling and monitoring test system pipeline as a test section after simplifying the pipeline of the prototype system for sampling and monitoring airborne radioactivity; Step S2, connecting one of the branches to be tested in the test pipe section to the sampling efficiency test system; Step S3, generating an aerosol of standard particle size by an aerosol generator; Step S4: aerosol measurement sampling simulation. After confirming that the generated standard particles meet the particle size and particle concentration requirements, the vacuum pump is started to sample the constructed pipeline at the flow rate required by the test; Step S5: measuring the aerosol particle size, solubility, and flow rate at the inlet and outlet. Sampling tubes are placed at the inlet and outlet of the test tube section, respectively, and connected to a particle size spectrometer. The particle size spectrometer extracts gas at a constant flow rate and measures the aerosol particle concentration. Step S6, repeating steps S2 to S5 until all branches to be tested in the tested pipe section are tested; Step S7: Process and analyze the acquired test data to determine the sampling efficiency of each branch of the test pipe section.

8. The sampling efficiency test method for an airborne radioactivity sampling and monitoring pipeline according to claim 7, characterized in that: The step S3 also includes adjusting the particle size and particle concentration of the standard particle aerosol to meet the requirements.

9. The sampling efficiency test method for an airborne radioactivity sampling and monitoring pipeline according to claim 7, characterized in that: The step S2 further includes setting a particle filter on the branch of the test pipe section that is not connected to the sampling efficiency test system and connecting it to the atmospheric environment.

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