Test platform and test method for research on cross-regional migration characteristics of radioactive aerosol in closed partition of spent fuel reprocessing plant

Abstract

The invention belongs to the technical field of aerosol cross-regional migration parameter measurement and mechanism verification, and aims to solve the problems that an existing device is difficult to be compatible with permeability coefficient measurement and safety pressure gradient measurement, and working condition repeatability and data traceability are insufficient. The invention provides a test platform and a test method for researching the trans-regional migration characteristics of radioactive aerosol in closed partitions of a spent fuel reprocessing plant. The platform comprises a first environment simulation body, a second environment simulation body, a replaceable micro-channel experiment piece assembly, an air distribution and pressure regulation and control system, an aerosol distribution system, a sampling and particle size concentration measurement system and a data acquisition and control system. And negative pressure gradient permeability coefficient measurement and inverse differential pressure diffusion minimum safety pressure gradient determination are realized. The platform has the advantages of modular design, repeatable working conditions and traceable data, migration parameter measurement and mechanism verification can be carried out under controllable conditions, and the platform is also suitable for aerosol cross-region transmission test research of other nuclear facilities or similar complex closed multi-region environments.

Description

Technical Field

[0001] This invention belongs to the field of aerosol cross-regional migration parameter determination and mechanism verification technology, specifically involving an experimental platform and experimental method for studying the cross-regional migration characteristics of radioactive aerosols in closed compartments of spent fuel reprocessing plants. Background Technology

[0002] Spent fuel reprocessing facilities typically employ a zoned sealing and staged differential pressure control nuclear ventilation strategy to confine contaminants and achieve targeted emissions. In actual engineering projects, micro-channels such as penetrations, door gaps, pipes, or structural gaps inevitably exist between adjacent zones. Under the combined effects of differential pressure and concentration differences, aerosols may migrate across zones, increasing the contamination risk in adjacent zones. To address this type of cross-zone migration behavior, experimental studies need to be conducted under controllable differential pressure and concentration conditions to obtain key parameters such as permeability coefficient and critical pressure for reverse diffusion, providing a basis for mechanistic models and engineering risk assessments.

[0003] Existing experimental setups often suffer from deficiencies in terms of controllability of operating conditions, replaceability of microchannels, simultaneous upstream and downstream sampling, and data traceability. In particular, permeability coefficient measurement devices and safety pressure gradient measurement devices are usually constructed separately, resulting in hardware duplication, poor consistency of operating conditions, and difficulty in achieving comparable studies of "negative pressure gradient permeation" and "concentration gradient reverse diffusion criticality" experiments on a unified platform. Therefore, it is necessary to propose a reusable modular experimental platform that can perform both types of experiments on the same hardware by switching operating conditions and connection methods, and achieve synchronous parameter acquisition and closed-loop control. Summary of the Invention

[0004] The purpose of this invention is to provide an experimental platform and method for studying the cross-regional migration characteristics of aerosols in spent fuel reprocessing plants, in order to solve the problems of existing devices being unable to be compatible with permeability coefficient measurement and safety pressure gradient measurement, and lacking repeatability of operating conditions and data traceability.

[0005] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides an experimental platform for studying the cross-regional migration characteristics of radioactive aerosols in a confined compartment of a spent fuel reprocessing plant, the experimental platform comprising: Both are first and second environment simulators, which are enclosed containers. Replaceable microchannel experimental components are used to connect the first environmental simulator and the second environmental simulator to form a cross-regional migration channel; An air delivery and pressure control system is connected to the first and second environmental simulators respectively, and is used to provide clean gas to the environmental simulators and establish, regulate and maintain the pressure difference across the replaceable microchannel experimental component assembly. An aerosol delivery system, connected to the first and second environmental simulators, is used to deliver aerosol particles of a set size and concentration to the selected environmental simulator and form an aerosol dispersion system. The sampling and particle size concentration measurement system is connected to the upstream and downstream sides of the replaceable microchannel experimental component assembly, respectively, and is used to acquire aerosol particle size distribution and concentration data on both sides of the microchannel. The data acquisition and control system is used to acquire at least the status parameters including temperature, humidity, pressure, differential pressure, and flow rate, and to control the electrically controlled valves in the air delivery and pressure regulation system and the aerosol delivery system, so as to realize the setting of test conditions, closed-loop control, and data recording.

[0006] Furthermore, the test platform supports at least the following two test modes by setting the pressure difference and aerosol concentration difference between the first and second environmental simulators: Permeability coefficient measurement mode: Under a preset negative pressure gradient condition, the aerosol concentration on both sides of the microchannel is measured simultaneously and the aerosol permeability coefficient is calculated. Safety pressure gradient measurement mode: Under the condition of coexistence of concentration difference and pressure difference, monitor the aerosol concentration in the high-pressure side environment simulation body to determine the minimum safe pressure gradient for aerosol diffusion against pressure difference.

[0007] Furthermore, multiple thermocouple measuring points are arranged vertically within the aforementioned first environmental simulation body, and thermocouple measuring points are also arranged at different radial positions to obtain the spatial temperature distribution; and wall temperature measuring points are set on the inner wall of the container for wall temperature control.

[0008] Furthermore, the aforementioned first environmental simulator is provided with at least one observation window, which is used to observe the internal state of the environmental simulator and to install optical measurement devices.

[0009] Furthermore, an optical measurement system for capturing the trajectory of aerosols is provided at the aforementioned observation window. The optical measurement system includes a light source, a shaping optical component, an imaging component, and a synchronous triggering unit. The shaping optical component is used to shape the light source output into a sheet-like beam or volume illumination to illuminate aerosol particles in a simulated first environment. The imaging component is a high-speed camera and lens used to acquire aerosol scattering image sequences. The synchronous triggering unit is electrically connected to the data acquisition and control system to realize synchronous triggering of the light source and the camera, so as to reconstruct the motion trajectory and velocity field of aerosol particles through particle tracking velocimetry (PTV) or particle image velocimetry (PIV) methods.

[0010] Furthermore, the above-mentioned sampling and particle size concentration measurement system includes an upstream sampling branch, a downstream sampling branch, and a particle size concentration measuring instrument. The upstream sampling branch and the downstream sampling branch are respectively connected to both sides of the microchannel, and the sampling mode is switched through a valve group.

[0011] Furthermore, the aforementioned downstream sampling branch is equipped with a mixing chamber and a makeup gas path. The makeup gas path is used to input makeup gas with a known flow rate into the mixing chamber so that the total flow rate after mixing meets the injection flow rate requirements of the particle size concentration measuring instrument. The dilution ratio is determined based on the makeup gas flow rate and the total mixed flow rate to calculate the downstream true concentration from the downstream measurement results.

[0012] Secondly, the present invention also proposes a method for testing the cross-regional migration characteristics of aerosols based on any of the above-mentioned test platforms, comprising the following steps: S1: Prepare aerosol samples and debug the aerosol delivery system, and replace the input of clean and dry gas into the environmental simulation body; S2: Activate the aerosol delivery system to input aerosols into the first or second environmental simulator and form a stable aerosol field; S3: Establish and maintain a preset pressure difference across the replaceable microchannel experimental component through an air delivery and pressure control system, and establish a preset ventilation flow rate and airflow organization through the air supply and exhaust system of the first environmental simulation body; S4: Samples are taken from both sides of the microchannel using a sampling and particle size concentration measurement system to obtain particle size distribution and concentration; S5: Optionally, the optical measurement system is activated to image the target observation area within the first environmental simulation body to obtain the aerosol motion trajectory and velocity field. S6: Combines the temperature, humidity, pressure, differential pressure and flow parameters recorded by the data acquisition and control system to calculate and output the cross-regional migration characteristics parameters of aerosols.

[0013] Furthermore, when performing the permeability coefficient measurement mode, step S3 is set to different negative pressure gradient conditions; step S4 obtains the upstream and downstream concentrations of the microchannel; step S6 calculates the aerosol permeability coefficient based on the upstream and downstream concentrations and the corresponding pressure difference; and in step S5, the aerosol movement trajectory near the microchannel inlet region in the first environmental simulation body is obtained by the PTV method, which is used to characterize the influence of near-wall backflow, vortex structure or short-circuit flow on permeation behavior.

[0014] Furthermore, when performing the safety pressure gradient measurement mode, a low-pressure, high-concentration aerosol field is formed in the first environmental simulator and a high-pressure environment is formed in the second environmental simulator; the pressure difference is adjusted step by step and the aerosol concentration in the second environmental simulator is monitored. When the concentration in the second environmental simulator meets the preset threshold or reverse pressure diffusion no longer occurs, the corresponding pressure difference is determined as the minimum safety pressure gradient; and in step S5, optical imaging is performed on the aerosol plume and migration path in the first environmental simulator to help determine the spatial location and propagation path of the reverse diffusion.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: (1) Platformization: The permeability coefficient measurement and the safety pressure gradient measurement are converged into the same hardware platform, and the two types of tests are realized by switching operating conditions, which reduces the cost of repeated construction and improves the comparability of tests; (2) Controllable operating conditions: The pressure difference is established and maintained in a closed loop through the air distribution and pressure regulation system, and the boundary conditions such as pressure difference and flow rate can be repeated; (3) Replaceable modules: The microchannel experimental components adopt a quick-change and sealed structure, which makes it easy to replace experimental components with different equivalent diameters or different structural types to realize parameter envelope research. (4) Data traceability: State parameters and particle size concentration data are collected and recorded synchronously, supporting reliable calculation of permeability coefficient and safety pressure gradient; (5) Expandable: The first environment simulation body can be set with an observation window and can be equipped with an optical flow field measurement system to expand flow field measurement and visualization analysis.

[0016] (6) Trajectory visualization: Based on optical full-field measurement and particle tracking methods such as PIV / PTV, aerosol motion trajectories and velocity fields can be captured without disturbing the flow field, directly revealing the spatial path and key flow structure of cross-regional migration.

[0017] This invention is mainly used to determine the parameters and verify the mechanism of aerosol cross-regional transport under controllable pressure and concentration differences; at the same time, this invention is also applicable to aerosol cross-regional transport experimental research in other nuclear facilities or similar complex closed multi-zone environments. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1This is an overall structural diagram of the experimental platform for studying the cross-regional migration characteristics of radioactive aerosols in a closed compartment of a spent fuel reprocessing plant, as described in this invention.

[0020] Among them, 1-first environmental simulation body, 1a-observation window, 1b-air supply outlet, 1c-air exhaust outlet; 2-second environmental simulation body; 3-replaceable microchannel experimental component assembly, 3a-sealed connector, 3b-support shell; 4-air delivery and pressure control system, 4a-differential pressure regulating valve group, 4b-differential pressure sensor; 5-aerosol delivery system, 5a-aerosol generator; 5b-mixing container; 6-sampling and particle size concentration measurement system, 6a-upstream sampling branch, 6b-downstream sampling branch, 6c-particle size concentration measuring instrument; 7-data acquisition and control system; 8-optical measurement system, 8a-light source, 8b-shaping optical component, 8c-imaging component, 8d-synchronous triggering unit. Detailed Implementation

[0021] The following description of the experimental platform and method for studying the cross-regional migration characteristics of radioactive aerosols in a closed compartment of a spent fuel reprocessing plant, including experimental apparatus, operating procedures, data processing steps, and example parameters, is intended to be illustrative rather than limiting, and aims to help those skilled in the art thoroughly understand the principles and implementation of the invention. However, those skilled in the art should understand that these details represent only one feasible embodiment, and the core concept of the invention can be fully realized through other technical means or alternative solutions not described in detail, without departing from its spirit. Furthermore, the omission of details of conventional experimental methods and apparatus known in the art in the specification is to avoid redundant information interfering with the understanding of the innovation, and does not mean that these known technologies are not required during implementation. Those skilled in the art should be able to supplement and apply them based on their professional knowledge.

[0022] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0023] Example 1, Combination Figure 1 This embodiment describes an experimental platform for studying the cross-regional migration characteristics of aerosols in spent fuel reprocessing plants. It addresses the problems of existing devices being unable to accommodate permeability coefficient measurement and safety pressure gradient measurement, as well as insufficient repeatability of operating conditions and data traceability.

[0024] like Figure 1 As shown, the test platform includes: Both are enclosed containers; the first environment simulator 1 and the second environment simulator 2. Replaceable microchannel experimental component 3 is used to connect the first environmental simulation body 1 and the second environmental simulation body 2 to form a cross-regional migration channel; The air delivery and pressure control system 4 is connected to the first environmental simulator 1 and the second environmental simulator 2 respectively, and is used to provide clean gas to the environmental simulator and establish, regulate and maintain the pressure difference between the two ends of the microchannel experimental component 3. The aerosol delivery system 5 is connected to the first environmental simulator 1 and the second environmental simulator 2, and is used to deliver aerosol particles of a set particle size and concentration to the selected environmental simulator to form an aerosol dispersion system. The sampling and particle size concentration measurement system 6 is connected to the upstream and downstream sides of the microchannel experimental component 3, respectively, and is used to acquire aerosol particle size distribution and concentration data on both sides of the microchannel. The data acquisition and control system 7 is used to acquire at least the status parameters including temperature, humidity, pressure, pressure difference, and flow rate, and to control the electrically controlled valves in the air delivery and pressure regulation system 4 and the aerosol delivery system 5, so as to realize the setting of test conditions, closed-loop control and data recording.

[0025] Furthermore, the specific structure of the test platform is as follows: In this embodiment, the first environmental simulator 1 and the second environmental simulator 2 include a pressure sensor, a temperature sensor, and a pressure relief valve.

[0026] In this embodiment, multiple thermocouple measuring points are arranged vertically inside the first environmental simulation body 1, and thermocouple measuring points are arranged at different radial positions to obtain the spatial temperature distribution; and wall temperature measuring points are set on the inner wall of the container for wall temperature control.

[0027] In this embodiment, the first environmental simulation body 1 is provided with at least one observation window 1a, which is used to observe the internal state of the environmental simulation body and to install optical measurement devices. An optical measurement system 8 for capturing the motion trajectory of aerosols is provided at the observation window 1a. The optical measurement system 8 includes a light source 8a, a shaping optical component 8b, an imaging component 8c, and a synchronization triggering unit 8d. The shaping optical component 8b is used to shape the output of the light source 8a into a sheet-like beam or volume illumination to illuminate aerosol particles within the first environmental simulation body 1. The imaging component 8c is a high-speed camera and lens used to acquire aerosol scattering image sequences. The synchronization triggering unit 8d is electrically connected to the data acquisition and control system 7 to achieve synchronous triggering of the light source and the camera, so as to reconstruct the motion trajectory and velocity field of aerosol particles using particle tracking velocimetry (PTV) or particle image velocimetry (PIV) methods.

[0028] In this embodiment, a supply and exhaust ventilation system is arranged inside the first environmental simulation body 1. The supply and exhaust ventilation system includes an air supply outlet 1b and an exhaust outlet 1c, and is connected to the air supply branch and exhaust branch of the air distribution and pressure control system 4. A flow regulating valve, a flow stabilizing component, and a diffuser or nozzle assembly are provided before the air supply outlet 1b to form a controllable airflow organization within the first environmental simulation body 1. An exhaust regulating valve, a filter unit, and an exhaust fan are correspondingly provided at the exhaust outlet 1c to maintain a preset ventilation flow rate and pressure boundary while ensuring the clean treatment of the exhaust gas.

[0029] In this embodiment, the replaceable microchannel experimental component assembly 3 is a modular quick-change structure, including a sealing connector 3a and a support housing 3b for mounting the microchannel experimental component, so as to realize the replacement of microchannel experimental components with different equivalent diameters or different structural types. The microchannel experimental component is a capillary or equivalent aperture component.

[0030] In this embodiment, the air delivery and pressure control system 4 includes an air supply branch, an exhaust branch, and a differential pressure regulating valve group 4a. The differential pressure regulating valve group works in conjunction with the differential pressure sensor 4b to perform closed-loop control of the pressure difference at both ends of the microchannel.

[0031] In this embodiment, the aerosol delivery system 5 includes an air compressor, a refrigerated dryer, an air tank, a filter unit, a drying unit, a flow metering unit, an aerosol generator 5a, and a mixing container 5b. The aerosol generated by the aerosol generator is mixed with the carrier gas in the mixing container and then input into the first environmental simulation body 1 and the second environmental simulation body 2.

[0032] In this embodiment, the sampling and particle size concentration measurement system 6 includes an upstream sampling branch 6a, a downstream sampling branch 6b, and a particle size concentration measuring instrument 6c. The upstream and downstream sampling branches are respectively connected to both sides of the microchannel, and the sampling mode is switched through a valve group. The particle size concentration measuring instrument 6c is an optical particle counter or a particle size spectrometer, used to measure the particle size distribution and concentration in the range of 0.2μm to 10μm.

[0033] In this embodiment, the downstream sampling branch 6b is provided with a mixing chamber and a make-up gas flow path. The make-up gas flow path is used to input a make-up gas with a known flow rate into the mixing chamber so that the total flow rate after mixing meets the injection flow rate requirement of the particle size concentration measuring instrument 6c. The dilution ratio is determined based on the make-up gas flow rate and the total mixing flow rate to calculate the downstream true concentration from the downstream measurement results.

[0034] In this embodiment, the data acquisition and control system 7 includes a data acquisition chassis, at least one voltage acquisition card, at least one current acquisition card, and a control board, and realizes data visualization and valve opening control through host computer software.

[0035] In this embodiment, the test platform supports at least the following two test modes by setting the pressure difference and aerosol concentration difference between the first environmental simulator 1 and the second environmental simulator 2: Permeability coefficient measurement mode: Under a preset negative pressure gradient condition, the aerosol concentration on both sides of the microchannel is measured simultaneously and the aerosol permeability coefficient is calculated. Safety pressure gradient measurement mode: Under the condition of coexistence of concentration difference and pressure difference, monitor the aerosol concentration in the high-pressure side environment simulation body to determine the minimum safe pressure gradient for aerosol diffusion against pressure difference.

[0036] Example 2, Combination Figure 1 This embodiment describes in detail the test platform and test method for the permeability measurement mode described in Embodiment 1 above; Permeability coefficient measurement mode (negative pressure gradient trans-regional permeability): like Figure 1 As shown, the experimental platform includes a first environmental simulator 1, a second environmental simulator 2, a replaceable microchannel experimental component assembly 3, an air delivery and pressure control system 4, an aerosol delivery system 5, a sampling and particle size concentration measurement system 6, and a data acquisition and control system 7.

[0037] The first environmental simulation body 1 is preferably a container with the same structure as the actual environment. It can be made of corrosion-resistant materials and equipped with pressure sensors, temperature sensors, pressure relief valves, and drain valves.

[0038] In a preferred embodiment, an air supply vent 1b and an air exhaust vent 1c are provided inside the first environmental simulation body 1. The air supply vent can be connected to a diffuser or nozzle assembly and can be arranged with a rectifier to form a stable and repeatable airflow organization; the air exhaust vent is connected to a filter unit and an exhaust fan / vacuum pump to maintain a preset air exchange flow rate and indoor negative pressure.

[0039] In a preferred embodiment, the first environmental simulator 1 can be a 316L stainless steel square box-shaped container with a wall thickness of, for example, 24 mm, a design pressure of, for example, 2 MPa, and a design temperature of, for example, 200 °C. Its geometric dimensions are, for example, a total height of 5.2 m, an internal cavity cross-section of, for example, length × width = 1.55 m × 1.55 m, or other length-width combinations as required by the test, corresponding to a free space volume of, for example, 12.5 m³. To obtain the spatial temperature distribution, multiple layers of thermocouple measuring points can be arranged vertically inside the first environmental simulator 1, with multiple radial measuring points arranged in each layer; and wall temperature measuring points can be set on the inner wall for wall temperature control. The first environmental simulator 1 can also be equipped with an observation window 1a with pressure-resistant glass for observation or installation of optical measuring devices. The second environmental simulator 2 is a sealed container, the volume and pressure rating of which can be set according to the test requirements, and can be similar to or different from the structure of the first environmental simulator 1.

[0040] An optical measurement system 8 can be installed at the observation window 1a. During the experiment, the light source 8a forms a sheet-like beam through the shaping optical component 8b to illuminate the target observation area. The high-speed camera 8c acquires a sequence of aerosol scattering images and synchronizes them with the data acquisition system via the synchronization trigger unit 8d. Based on the image sequence, particle tracking can be performed on aerosol particles to obtain the motion trajectory PTV, and further related algorithms can be used to obtain the velocity vector field PIV.

[0041] The replaceable microchannel experimental component 3 is located at the connection point between the two environmental simulation bodies, and includes a sealing connector 3a and a supporting shell 3b. The microchannel experimental component can be a capillary or an equivalent micropore, and different equivalent diameters can be replaced to cover engineering uncertainties. Sampling interfaces are provided at both ends of the microchannel, and differential pressure sensors 4b are configured to measure the pressure difference between the two ends of the microchannel.

[0042] The air distribution and pressure control system 4 includes a supply branch, an exhaust branch, a flow metering unit, and a differential pressure regulating valve group 4a. The supply branch provides clean and dry gas to the first environmental simulator 1 and the second environmental simulator 2 for replacement; the exhaust branch is used to control the exhaust volume and establish a differential pressure; the differential pressure regulating valve group works with the differential pressure sensor to achieve differential pressure closed-loop control.

[0043] The aerosol delivery system 5 includes an air compressor, a refrigerated dryer, an air tank, a filter unit, a drying unit, a flow metering unit, an aerosol generator 5a, and a mixing container 5b. The aerosol generator produces powdered aerosols, which are then thoroughly mixed with the carrier gas in the mixing container before entering the first environmental simulation body 1 to form a stable aerosol dispersion system. The aerosol concentration can be adjusted by regulating the carrier gas flow rate or the rotation speed of the delivery components of the aerosol generator.

[0044] The sampling and particle size concentration measurement system 6 includes an upstream sampling branch 6a, a downstream sampling branch 6b, and a particle size concentration measuring instrument 6c. The upstream sampling branch is connected to the upstream side of the microchannel, and the downstream sampling branch is connected to the downstream side of the microchannel. The sampling mode is switched through a valve group to adapt to the differences in thermal and pressure conditions on both sides. The particle size concentration measuring instrument is used to obtain particle size distribution and concentration.

[0045] Because the equivalent size of the microchannel experimental piece is small, the gas flow rate leaking downstream may not be sufficient to meet the injection flow rate requirements of the particle size distribution analyzer. To ensure the feasibility of downstream measurements, a mixing chamber can be provided in the downstream sampling branch 6b, and a makeup gas path can be provided to input a known flow rate of high-purity inert gas into the mixing chamber as makeup gas, so that the total flow rate after mixing meets the instrument requirements; the measured downstream concentration is converted according to the dilution ratio to obtain the true downstream concentration.

[0046] The data acquisition and control system 7 is used to acquire and store signals such as temperature, pressure, differential pressure, and flow rate, and to regulate the opening degree of the electrically controlled valves; the host computer software visualizes and processes the acquired data.

[0047] The experimental methods for measuring permeability based on the above platform include: S1: Dry and sieve the aerosol samples before the experiment; start the air delivery and pressure control system to replace the two environmental simulators with clean gas and establish the initial pressure conditions; S2: Start the aerosol delivery system to input aerosols into the first environmental simulator and stabilize them to the target concentration; S3: Set different negative pressure gradient conditions through the differential pressure regulating valve group and maintain them in a closed loop; S4: Samples are taken from both sides of the microchannel to obtain the upstream and downstream particle size distribution and concentration; S5: Calculate the aerosol permeability coefficient of different microchannel experimental pieces under different operating conditions by combining parameters such as pressure difference, flow rate, temperature and humidity.

[0048] Example 3, Combination Figure 1 This embodiment describes in detail the test platform and test method for the safety pressure gradient measurement mode described in Embodiment 1 above. Safety pressure gradient measurement mode (critical reverse diffusion where concentration gradient and pressure gradient coexist): like Figure 1 As shown, the platform hardware remains unchanged, only the operating conditions and measurement targets are changed. The first environmental simulator 1 is set as a low-pressure, high-aerosol-concentration environment simulator, and the second environmental simulator 2 is set as a high-pressure environment simulator. The two are connected via a replaceable microchannel experimental component 3. Air inlets and outlets can be installed at the top and bottom of the first environmental simulator 1 to achieve stable ventilation boundaries. An optional optical flow field measurement system can be used through the observation window 1a to measure the three-dimensional velocity field in space, assisting in the analysis of the coupling mechanism between the indoor flow field and cross-regional migration. During the experiment, the pressure difference between the two environmental simulators is adjusted step-by-step using a differential pressure regulating valve group, and the aerosol concentration change is continuously monitored in the second environmental simulator 2. When the concentration in the second environmental simulator meets a preset threshold or the reverse pressure diffusion phenomenon no longer occurs, the corresponding pressure difference is determined as the minimum safe pressure gradient. The above method can obtain the critical parameters for reverse diffusion on a unified platform and form a comparable dataset with the permeability coefficient results of Example 2.

[0049] In this mode, the first environmental simulation body 1 forms a controllable aerosol plume and spatial concentration distribution through the supply and exhaust ventilation system; at the same time, the optical measurement system 8 is activated to perform sheet illumination and high-speed imaging near the microchannel and in the key recirculation area to reconstruct the aerosol motion trajectory, which is used to help identify the starting position, propagation path and coupling relationship with the airflow organization of the reverse pressure difference diffusion.

[0050] In the above description, it should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0051] It should also be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0052] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0053] The above description of the technical solution provided by the present invention through several specific embodiments is intended to highlight the advantages and benefits of the technical solution provided by the present invention. However, the above-described specific embodiments are not intended to limit the present invention. Any reasonable modifications and improvements to the present invention, reasonable combinations of implementation methods and equivalent substitutions based on the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An experimental platform for studying the cross-regional migration characteristics of radioactive aerosols in confined areas of spent fuel reprocessing plants, characterized in that, include: Both are closed containers, including the first environment simulator (1) and the second environment simulator (2). Replaceable microchannel experimental component (3) is used to connect the first environmental simulator (1) and the second environmental simulator (2) to form a cross-regional migration channel; An air delivery and pressure control system (4) is connected to the first environmental simulator (1) and the second environmental simulator (2) respectively, and is used to provide clean gas to the environmental simulator and establish, regulate and maintain the pressure difference between the two ends of the replaceable microchannel experimental component assembly (3); The aerosol delivery system (5) is connected to the first environmental simulation body (1) and the second environmental simulation body (2) and is used to deliver aerosol particles of a set particle size and concentration to the selected environmental simulation body to form an aerosol dispersion system. The sampling and particle size concentration measurement system (6) is connected to the upstream and downstream sides of the replaceable microchannel experimental component assembly (3) respectively, and is used to obtain aerosol particle size distribution and concentration data on both sides of the microchannel; The data acquisition and control system (7) is used to acquire at least the status parameters including temperature, humidity, pressure, pressure difference and flow rate, and control the electrically controlled valves in the air delivery and pressure regulation system (4) and the aerosol delivery system (5) to realize the setting of test conditions, closed-loop regulation and data recording.

2. The test platform according to claim 1, characterized in that, The test platform supports at least the following two test modes by setting the pressure difference and aerosol concentration difference between the first environmental simulator (1) and the second environmental simulator (2): Permeability coefficient measurement mode: Under a preset negative pressure gradient condition, the aerosol concentration on both sides of the microchannel is measured simultaneously and the aerosol permeability coefficient is calculated. Safety pressure gradient measurement mode: Under the condition of coexistence of concentration difference and pressure difference, monitor the aerosol concentration in the high-pressure side environment simulation body to determine the minimum safe pressure gradient for aerosol diffusion against pressure difference.

3. The test platform according to claim 1, characterized in that, The first environmental simulation body (1) has multiple thermocouple measuring points set along the vertical direction and thermocouple measuring points arranged at different radial positions to obtain the spatial temperature distribution; and wall temperature measuring points are set on the inner wall of the container for wall temperature control.

4. The test platform according to claim 1, characterized in that, The first environmental simulator (1) is provided with at least one observation window (1a), which is used to observe the internal state of the environmental simulator and to install optical measurement devices.

5. The test platform according to claim 3 or 4, characterized in that, An optical measurement system (8) for capturing the trajectory of aerosols is provided at the observation window (1a). The optical measurement system (8) includes a light source (8a), a shaping optical component (8b), an imaging component (8c), and a synchronous triggering unit (8d). The shaping optical component (8b) is used to shape the output of the light source (8a) into a sheet-like beam or volume illumination to illuminate aerosol particles in the first environmental simulation body (1). The imaging component (8c) is a high-speed camera and lens used to acquire aerosol scattering image sequences. The synchronous triggering unit (8d) is electrically connected to the data acquisition and control system (7) to realize the synchronous triggering of the light source and the camera, so as to reconstruct the motion trajectory and velocity field of aerosol particles by particle tracking velocimetry (PTV) or particle image velocimetry (PIV) methods.

6. The test platform according to claim 1, characterized in that, The sampling and particle size concentration measurement system (6) includes an upstream sampling branch (6a), a downstream sampling branch (6b), and a particle size concentration measuring instrument (6c). The upstream and downstream sampling branches are respectively connected to both sides of the microchannel and the sampling mode is switched through a valve group.

7. The test platform according to claim 6, characterized in that, The downstream sampling branch (6b) is provided with a mixing chamber and a make-up gas flow path. The make-up gas flow path is used to input a known flow rate of make-up gas into the mixing chamber so that the total flow rate after mixing meets the injection flow rate requirements of the particle size concentration measuring instrument (6c). The dilution ratio is determined based on the make-up gas flow rate and the total mixing flow rate to calculate the downstream true concentration from the downstream measurement results.

8. A method for testing the transregional migration characteristics of aerosols based on the test platform described in any one of claims 1-7, characterized in that, The method includes the following steps: S1: Prepare aerosol samples and debug the aerosol delivery system (5) to replace and input clean and dry gas into the environmental simulation body; S2: Start the aerosol delivery system (5) to input aerosols into the first environmental simulator (1) or the second environmental simulator (2) and form a stable aerosol field; S3: Establish and maintain a preset pressure difference between the two ends of the replaceable microchannel experimental component (3) through the air delivery and pressure control system (4), and establish a preset air exchange flow rate and airflow organization through the air supply and exhaust system of the first environmental simulation body; S4: The particle size distribution and concentration are obtained by sampling and measuring both sides of the microchannel through the sampling and particle size concentration measurement system (6); S5: Optionally, the optical measurement system (8) is activated to image the target observation area within the first environmental simulation body (1) to obtain the aerosol motion trajectory and velocity field; S6: Combine the temperature, humidity, pressure, differential pressure and flow parameters recorded by the data acquisition and control system (7) to calculate and output the aerosol cross-regional migration characteristic parameters.

9. The test method according to claim 8, characterized in that, When performing the permeability coefficient measurement mode, step S3 is set to different negative pressure gradient conditions; step S4 obtains the upstream and downstream concentrations of the microchannel; step S6 calculates the aerosol permeability coefficient based on the upstream and downstream concentrations and the corresponding pressure difference. Furthermore, in step S5, the aerosol motion trajectory near the microchannel inlet region within the first environmental simulation body (1) is obtained using the PTV method, which is used to characterize the influence of near-wall backflow, vortex structure, or short-circuit flow on permeation behavior.

10. The test method according to claim 8, characterized in that, When performing the safety pressure gradient measurement mode, the first environmental simulator (1) is made to form a low-pressure high-concentration aerosol field and the second environmental simulator (2) is made to form a high-pressure environment; the pressure difference is adjusted step by step and the aerosol concentration in the second environmental simulator (2) is monitored. When the concentration of the second environmental simulator (2) meets the preset threshold or reverse pressure difference diffusion no longer occurs, the corresponding pressure difference is determined as the minimum safety pressure gradient. Furthermore, in step S5, optical imaging is performed on the aerosol plume and migration path within the first environmental simulation body (1) to assist in determining the spatial location and propagation path of the reverse diffusion.

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