Experimental system for generating radionuclide and sampling and measuring and experimental method thereof

Abstract

The invention provides an experimental system for generating radionuclides and sampling and measuring and an experimental method thereof, and belongs to the technical field of nuclear safety. The problems that a radionuclide experiment system is single in simulation environment and insufficient in temperature gradient simulation, and an open sampling system is prone to causing radioactive substance leakage are solved. Comprising a gas phase environment simulation system, a metal high-temperature vaporization reaction system and an aerosol sampling and measuring system, the output end of the gas phase environment simulation system is communicated with the metal high-temperature vaporization reaction system through a conveying pipeline, and the output end of the metal high-temperature vaporization reaction system is communicated with the aerosol sampling and measuring system through an exhaust pipeline; the gas phase environment simulation system is used for simulating a complex gas environment when aerosol is generated, and the metal high-temperature vaporization reaction system is used for creating experimental working conditions with rated pressure and temperature. The device is mainly used for realizing high-precision capture and quantitative analysis of radioactive aerosol and guaranteeing the experiment safety at the same time.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nuclear safety, and particularly relates to an experimental system for generating radioactive nuclides and sampling measurement and an experimental method thereof. BACKGROUND

[0002] The fuel pellets of the reactor core, the zirconium alloy cladding and the control rod material will release radioactive nuclides such as cesium (Cs), iodine (I) and strontium (Sr) in a high-temperature molten state. These nuclides will undergo vaporization, condensation and nucleation processes under conditions of rapid temperature changes, forming radioactive aerosol particles with a particle size range of nanometers to microns. Such aerosols are the main carrier form of radioactive substances released into the environment in severe accidents. Radioactive aerosols have strong followability and, once released from the core to the containment or the atmospheric environment, will diffuse and migrate with the flow of gas-phase fluids and adhere to the surfaces of objects such as the ground, buildings, soil and water sources, continuously generating radiation and posing a long-term hazard to personnel, equipment and the environment. The initial particle size and density of the aerosol directly affect the forces acting on it, such as gravity, Brownian force, thermophoretic force and convective force, thereby determining its diffusion, migration and deposition behavior characteristics.

[0003] Currently, the experimental research on radioactive aerosols has the following technical bottlenecks: Single simulation environment: Traditional experimental devices mostly use resistance furnace heating methods, which can usually only provide a single air atmosphere, making it difficult to achieve precise control of mixed environments with multiple components such as water vapor, inert gases and oxidizing gases, and unable to effectively reproduce the complex mixed gas phase conditions in the containment under severe accidents, for example, the hydrogen-rich environment generated by the reaction of high-temperature steam and zirconium alloy.

[0004] Insufficient temperature gradient simulation: In a nuclear accident, when the core melt contacts the containment bottom plate, a significant axial temperature gradient is generated, for example, a temperature drop from about 1000℃ to room temperature. However, existing experimental devices are mostly in constant temperature heating mode, and cannot simulate the effects of such temperature changes on the nucleation mechanism of aerosols and the characteristics of particulate matter.

[0005] Risk of radioactive contamination and safety hazards: When the resistance heating element directly contacts the sample containing radioactive substances, the heating element is easily contaminated by the radioactive substances, resulting in high costs for subsequent decommissioning of the device. In addition, some devices use open sampling systems, which have potential safety hazards of radioactive substance leakage. SUMMARY

[0006] Therefore, the present application aims to provide an experimental system for generating radioactive nuclides and sampling measurement and an experimental method thereof, to solve the problems of single simulation environment, insufficient temperature gradient simulation and open sampling system causing radioactive substance leakage of existing radioactive nuclide experimental systems.

[0007] In order to achieve the above object, the present application adopts the following technical scheme: an experimental system for generating radionuclides and sampling measurement, comprising a gas-phase environment simulation system, a metal high-temperature vaporization reaction system and an aerosol sampling measurement system; the output end of the gas-phase environment simulation system is communicated with the metal high-temperature vaporization reaction system through a conveying pipeline, and the output end of the metal high-temperature vaporization reaction system is communicated with the aerosol sampling measurement system through an exhaust pipeline; the gas-phase environment simulation system comprises an air supply unit, a steam supply unit, an inert gas supply unit and a three-way valve, the air supply unit and the steam supply unit are both communicated with one end of the conveying pipeline, the other end of the conveying pipeline is communicated with the first port of the three-way valve, the second port of the three-way valve is communicated with the inert gas supply unit, and the third port of the three-way valve is communicated with the metal high-temperature vaporization reaction system through a conveying pipeline; the metal high-temperature vaporization reaction system comprises a first reaction container, a second reaction container, a laser heater and a sample carrying assembly, the bottom of the first reaction container is communicated with the conveying pipeline, the first reaction container and the second reaction container are symmetrically arranged and communicated through a pipeline, the bottom center of the second reaction container is provided with the sample carrying assembly, the top center of the second reaction container is provided with the laser heater, the light path of the laser heater passes through the top of the second reaction container and irradiates the sample placed on the sample carrying assembly, the second reaction container is communicated with the aerosol sampling measurement system through the exhaust pipeline, the outer side of the first reaction container and the second reaction container is covered with a container heating system, and the side wall of the first reaction container and the second reaction container is provided with at least three K-type armored thermocouples at equal intervals along the axial direction; the aerosol sampling measurement system comprises a filter membrane, a condensing device and a flow detection unit which are sequentially arranged along the gas flow direction, the filter membrane is communicated with the second reaction container through the exhaust pipeline, and a K-type thermocouple is arranged on the exhaust pipeline and located on the front side of the filter membrane.

[0008] Further, the air supply unit comprises an air compressor for providing air, and a filter, a first regulating valve and a first mass flow meter which are sequentially arranged along the air flow direction, and the output end of the first mass flow meter is communicated with the conveying pipeline.

[0009] Further, the steam supply unit comprises an electric steam boiler for providing steam, and a second regulating valve and a second mass flow meter which are sequentially arranged along the steam flow direction, and the output end of the second mass flow meter is communicated with the conveying pipeline.

[0010] Further, the inert gas supply unit comprises a high-pressure gas cylinder for providing inert gas, and a third regulating valve which is arranged along the inert gas flow direction and communicated with the second port of the three-way valve.

[0011] Further, the conveying pipeline is coated with an electric heating device.

[0012] Further, the first reaction container and the second reaction container are both provided with a hydrophobic valve at the bottom and a pressure sensor at the top, and the top surface and the front surface of the first reaction container and the second reaction container are both provided with an observation sight glass.

[0013] Further, the flow detection unit comprises a flow controller and a gas suction pump arranged along the gas flow direction.

[0014] An experimental method of an experimental system for generating a radionuclide and sampling measurement, comprising the following steps: S1: providing gases to a metal high-temperature vaporization reaction system through an air supply unit, a steam supply unit and an inert gas supply unit of a gas phase environment simulation system, the gases generated by the air supply unit, the steam supply unit and the inert gas supply unit being transported to a first reaction container of the metal high-temperature vaporization reaction system through a conveying pipeline to mix and form a mixed gas; S2: the mixed gas enters a second reaction container, and a sample on a sample carrying assembly in the second reaction container is heated by a laser heater in the metal high-temperature vaporization reaction system, so as to generate an aerosol, and the aerosol enters an aerosol sampling measurement system through an exhaust pipeline; S3: the aerosol is extracted by the aerosol sampling measurement system, so that the aerosol is deposited through a filter membrane, and finally measured by a flow detection unit.

[0015] Further, in S1, the mass of air entering the metal high-temperature vaporization reaction system is controlled by a first regulating valve and a first mass flow meter in the air supply unit, the mass of steam entering the metal high-temperature vaporization reaction system is controlled by a second regulating valve and a second mass flow meter in the steam supply unit, and the mass of inert gas entering the metal high-temperature vaporization reaction system is controlled by a third regulating valve in the inert gas supply unit, so as to control the components of the mixed gas.

[0016] Further, in S3, the temperature of the aerosol is measured by a K-type thermocouple in the aerosol sampling measurement system, the aerosol is cooled by a condensing device, the air flow is measured by a flow controller, and the flow of the mixed gas is inversely deduced according to the proportioning.

[0017] Compared with the prior art, the beneficial effects of the present application are: 1. The air supply unit, the steam supply unit and the inert gas supply unit are arranged in parallel, combined with a three-way valve, to support the arbitrary proportioning mixing of air, steam and inert gas, the gas phase environment simulation system can directly reproduce the complex gas phase environment such as hydrogen-rich steam generated by the zirconium-water reaction in a severe accident, and break through the limitation of the traditional single gas atmosphere; 2、The first reaction container and the second reaction container of the application are coated with a container heating system, which cooperates with K-type thermocouples arranged equidistantly along the axial direction of the first reaction container and the second reaction container to realize real-time monitoring and regulation of the temperature in the first reaction container and the second reaction container; 3、The laser heater of the application directly irradiates the sample on the sample bearing assembly through the observation mirror on the top surface of the second reaction container, thereby realizing non-contact heating of the radioactive material, avoiding contamination of the sample and the second reaction container, and isolating the radioactive material from the heating element, thereby eliminating pollution from the root and reducing the decommissioning cost of the device; 4、The outer surface of the delivery pipeline is coated with an electric heating device to ensure stable delivery of the gas, and the exhaust pipeline is connected with the filter membrane and the condensing device to form a closed gas flow path, which cooperates with the negative pressure extraction of the air pump to realize the whole closed processing of the radioactive aerosol from generation to deposition, thereby eliminating the leakage risk. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which form a part of the present application, are used to provide a further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application, and do not constitute an improper limitation of the present application. In the drawings: Figure 1 A structure schematic view of the experimental system for generating radionuclides and sampling measurement according to the application.

[0019] In the drawings: 1, air compressor; 2, filter; 3, first regulating valve; 4, first mass flowmeter; 5, electric steam boiler; 6, delivery pipeline; 7, electric heating device; 8, high-pressure gas cylinder; 9, three-way valve; 10, second regulating valve; 11, second mass flowmeter; 12, third regulating valve; 13, first reaction container; 14, second reaction container; 15, pressure sensor; 16, K-type armored thermocouple; 17, drain valve; 18, observation mirror; 19, laser heater; 20, exhaust pipeline; 21, sample bearing assembly; 22, container heating system; 23, K-type thermocouple; 24, filter membrane; 25, condensing device; 26, flow controller; 27, air pump. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the application, but not all the embodiments.

[0021] DETAILED DESCRIPTION: see Figure 1To illustrate the embodiment, an experimental system for generating radionuclides and sampling measurement includes a gas phase environment simulation system, a metal high-temperature vaporization reaction system, and an aerosol sampling measurement system. The gas phase environment simulation system is used to simulate the complex gas environment when the aerosol is generated. The metal high-temperature vaporization reaction system is used to manufacture the experimental working conditions of rated pressure and temperature, and to constrain the produced aerosol particles to prevent the aerosol particles from diffusing into the environment. The aerosol sampling measurement system is used to sample and analyze the generated aerosol, including the analysis of the particle size distribution, morphology, and energy spectrum of the aerosol. The output end of the gas phase environment simulation system is connected to the metal high-temperature vaporization reaction system through a conveying pipeline 6. The conveying pipeline 6 is made of a 8mm stainless steel pipe. The gas generated by the gas phase environment simulation system is transmitted to the metal high-temperature vaporization reaction system through the conveying pipeline 6 to provide a gas environment for the generation of aerosol. The output end of the metal high-temperature vaporization reaction system is connected to the aerosol sampling measurement system through an exhaust pipeline 20. The aerosol generated by the metal high-temperature vaporization reaction system enters the aerosol sampling measurement system through the exhaust pipeline 20. The particle size distribution, morphology, and energy spectrum of the aerosol are analyzed by the aerosol sampling measurement system. The gas phase environment simulation system includes an air supply unit, a steam supply unit, an inert gas supply unit, and a three-way valve 9. The air supply unit is used to provide air. The steam supply unit is used to provide steam. The inert gas supply unit is used to provide inert gas, such as argon and helium. The air supply unit and the steam supply unit are connected to one end of the conveying pipeline 6. The other end of the conveying pipeline 6 is connected to the first port of the three-way valve 9. An adjusting valve is arranged on the conveying pipeline 6 connected to the air supply unit and the steam supply unit of the three-way valve 9. The adjusting valve is used to control the on-off of the air and steam flow path. The second port of the three-way valve 9 is connected to the inert gas supply unit. The third port of the three-way valve 9 is connected to the metal high-temperature vaporization reaction system through the conveying pipeline 6. An adjusting valve is also arranged on the conveying pipeline 6 connected to the metal high-temperature vaporization reaction system of the third port of the three-way valve 9. The adjusting valve is used to control the on-off of the mixed gas generated by the air supply unit, the steam supply unit, and the inert gas supply unit into the metal high-temperature vaporization reaction system flow path. The metal high-temperature vaporization reaction system includes a first reaction container 13, a second reaction container 14, a laser heater 19, and a sample carrying assembly 21. The first reaction container 13 and the second reaction container 14 are used to contain the produced radioactive substances. The closed structure of the first reaction container 13 and the second reaction container 14 prevents the emission of radioactive substances into the environment. The bottom of the first reaction container 13 is connected to the conveying pipeline 6. The mixed gas generated by the air supply unit, the steam supply unit, and the inert gas supply unit enters the first reaction container 13 through the conveying pipeline 6. The quality of the mixed gas in the first reaction container 13 is controlled by the adjusting valve.The first reaction container 13 and the second reaction container 14 are symmetrically arranged and communicated by pipes, the first reaction container 13 and the second reaction container 14 have the same size, the first reaction container 13 and the second reaction container 14 are communicated by 8mm stainless steel pipes, the stainless steel pipes are provided with adjusting valves, the outside of the stainless steel pipes is wrapped with heat preservation cotton, the stainless steel pipes are led out from the side wall of the first reaction container 13 and connected to the bottom flange of the second reaction container 14 to form a mixed flow path, the second reaction container 14 is a place where aerosol is generated, the bottom center of the second reaction container 14 is provided with a sample bearing assembly 21, the sample bearing assembly 21 is a triangular support, the sample bearing assembly 21 is provided with a corundum crucible for bearing the experimental sample, the top center of the second reaction container 14 is provided with a laser heater 19, the light path of the laser heater 19 passes through the top of the second reaction container 14 and irradiates the sample placed on the sample bearing assembly 21, the laser heater 19 adopts a continuous fiber laser with a rated power of 12kW, the wavelength of the laser heater 19 is 1080mm, and the output power can be flexibly controlled through a control system, the laser heater 19 vertically irradiates the sample on the sample bearing assembly 21 through the top of the second reaction container 14 to generate high temperature in a local area, and the highest temperature can reach 1000℃, the second reaction container 14 is communicated with an aerosol sampling and measuring system through an exhaust pipe 20, the exhaust pipe 20 is made of 8mm stainless steel pipe, the exhaust pipe 20 is used for introducing aerosol into the sampling and measuring system, the outside of the first reaction container 13 and the second reaction container 14 is wrapped with a container heating system 22, the container heating system 22 adopts an electric heating mode to heat the first reaction container 13 and the second reaction container 14, the container heating system 22 includes a ceramic electric heating rope, a PID controller and a thermocouple, the ceramic electric heating rope is used as a heating element, the power is adjusted through the signal of the PID controller, the PID controller outputs a control signal according to the deviation between the temperature measured by the thermocouple and the set temperature, so as to realize accurate control of the temperature of the container, and the container can be heated to 1000℃ at most, the side wall of the first reaction container 13 and the second reaction container 14 is provided with at least three K type armored thermocouples 16 at equal intervals along the axial direction, the K type armored thermocouple 16 is used for measuring the temperature gradient in the first reaction container 13 and the second reaction container 14; the aerosol sampling and measuring system includes a filter membrane 24, a condensing device 25 and a flow detection unit arranged in sequence along the gas flow direction, the filter membrane 24 is made of glass fiber material, the condensing device 25 is a cooling refrigerator, the condensing device 25 is used for cooling the aerosol to condense the steam, and the flow detection unit is used for measuring the air flow to inversely deduce the mixed gas flow, the filter membrane 24 is communicated with the second reaction container 14 through the exhaust pipe 20, and the filter membrane 24 is used for depositing the aerosol flowed out of the second reaction container 14,A K-type thermocouple 23 is arranged on the exhaust pipe 20, and the K-type thermocouple 23 is located in front of a filter membrane 24 and is used to monitor the temperature of the aerosol.

[0022] The application provides an experimental system for simulating a radionuclide aerosol generating process, mainly comprising a gas phase environment simulation system, a metal high-temperature vaporization reaction system and an aerosol sampling and measuring system, which can simulate a complex environment with high temperature and different gas components, and can realize sampling and measurement of aerosol particles, the device can control parameters such as temperature, pressure and gas component as variables, realizes radionuclide aerosol generation research under different conditions, and has high experimental measurement precision, good stability and high safety.

[0023] The air supply unit comprises an air compressor 1 for providing air, a filter 2 for filtering the air generated by the air compressor 1, a first regulating valve 3 and a first mass flow meter 4 arranged in sequence along the air flow direction, and the output end of the first mass flow meter 4 is communicated with the conveying pipeline 6, the air compressor 1 is used for providing air, the filter 2 is used for filtering the air generated by the air compressor 1, and the air quality of the metal high-temperature vaporization reaction system is precisely controlled through the opening degree of the first regulating valve 3 and the first mass flow meter 4, so that the air quality in the experimental tank of the metal high-temperature vaporization reaction system is adjusted, and the proportion of air in the mixed gas can be calculated.

[0024] The steam supply unit comprises an electric steam boiler 5 for providing steam, a second regulating valve 10 and a second mass flow meter 11 arranged in sequence along the steam flow direction, and the output end of the second mass flow meter 11 is communicated with the conveying pipeline 6, the output end of the electric steam boiler 5 is connected with a 8mm stainless steel pipe, the second regulating valve 10 and the second mass flow meter 11 are arranged on the steel pipe, the electric steam boiler 5 is used for providing steam, the second regulating valve 10 and the second mass flow meter 11 are used for adjusting the steam quality input into the metal high-temperature vaporization reaction system, so that the steam quality in the experimental tank of the metal high-temperature vaporization reaction system is adjusted, and the proportion of steam in the mixed gas can be calculated.

[0025] The inert gas supply unit comprises a high-pressure gas cylinder 8 for providing inert gas and a third regulating valve 12 arranged along the inert gas flow direction, the third regulating valve 12 is communicated with the second port of the three-way valve 9, the quality of the inert gas input into the metal high-temperature vaporization reaction system is mainly adjusted through the cooperation of the third regulating valve 12 and the pressure sensor 15, and the proportion of the inert gas in the mixed gas can be calculated.

[0026] The conveying pipeline 6 is coated with an electric heating device 7, the electric heating device 7 warms up the conveying pipeline 6 through electric heating to prevent steam condensation, and preheats the air and inert gas.

[0027] The first reaction container 13 and the second reaction container 14 are both provided with a hydrophobic valve 17 at the bottom and a pressure sensor 15 at the top, the two hydrophobic valves 17 are welded to the first reaction container 13 and the second reaction container 14 respectively, the hydrophobic valve 17 is used to discharge the condensed water generated by the first reaction container 13 and the second reaction container 14, the pressure sensor 15 is used to detect the pressure in the first reaction container 13 and the second reaction container 14, the pressure sensor 15 can cooperate with the first regulating valve 3 and the first mass flow meter 4 to control the air fraction entering the first reaction container 13, the pressure sensor 15 can also cooperate with the second regulating valve 10 and the second mass flow meter 9 to control the steam fraction entering the first reaction container 13, and the pressure sensor 15 can also cooperate with the third regulating valve 12 to adjust the fraction of inert gas entering the first reaction container 13, the top surface and the front surface of the first reaction container 13 and the second reaction container 14 are both provided with an observation mirror 18, the observation mirror 18 is made of high-temperature-resistant glass, the observation mirror 18 on the front surface of the first reaction container 13 and the second reaction container 14 is used to observe the process of aerosol generation, and the observation mirror 18 on the top surface of the first reaction container 13 and the second reaction container 14 is used to introduce a laser light path.

[0028] The flow detection unit includes a flow controller 26 and a suction pump 27 arranged along the gas flow direction, the suction pump 27 provides negative pressure power, and the mixed gas containing aerosol generated by the second reaction container 14 is sucked into the measurement system through the pipeline, the mixed gas passes through the filter membrane 24 to make the aerosol in the mixed gas deposit on the filter membrane 24, the mixed gas filtered through the filter membrane 24 passes through the condensing device 25 to condense the steam in the mixed gas, and the remaining air and inert gas are measured by the flow controller 26, and the flow of the mixed gas is deduced according to the ratio of the mixed gas set at the beginning of the experiment.

[0029] An experimental method of an experimental system for generating radionuclides and sampling measurement, comprising the following steps: S1: Before the experimental system is started, check the air tightness of the gas phase environment simulation system, confirm the water level of the electric steam boiler 5 and the pressure state of the high-pressure gas cylinder 8, place the radionuclide sample on the sample bearing support 21, ensure that the light path of the laser heater 19 is aligned with the sample, ensure that all regulating valves are in the closed state, start the container heating system 22 to preheat the first reaction container 13 and the second reaction container 14 to the base temperature, detect the temperature gradient in the container through the K-type armored thermocouple, provide gas to the metal high-temperature vaporization reaction system through the air supply unit, steam supply unit and inert gas supply unit of the gas phase environment simulation system, start the air compressor 1, the impurities in the air pass through the filter 2, ensure that the input air is clean and free of dust particles, the air filtered by the filter 2 is adjusted in mass through the linkage of the first regulating valve 3, the first mass flow meter 4 and the pressure sensor 15 at the top of the first reaction container 13, ensure that the mass of the air entering the metal high-temperature vaporization reaction system meets the needs of the nuclear accident simulation environment, the steam generated by the electric steam boiler 5 is adjusted and controlled through the linkage of the second regulating valve 10, the second mass flow meter 11 and the pressure sensor 15 at the top of the first reaction container 13, ensure that the mass of the steam entering the metal high-temperature vaporization reaction system meets the needs of the nuclear accident simulation environment, inert gas such as argon or helium is delivered to the metal high-temperature vaporization reaction system through the high-pressure gas cylinder 8, and the flow is controlled through the third regulating valve 12 in cooperation with the pressure sensor 15 at the top of the first reaction container 13, ensure that the mass of the inert gas entering the metal high-temperature vaporization reaction system meets the needs of the nuclear accident simulation environment, the three-way valve 9 is connected to the pipelines of air, steam and inert gas through three ports, and the on-off of the mixed gas into the metal high-temperature vaporization reaction system is controlled by switching the open-closed state of the regulating valves on the pipelines connected by the three ports, the gases generated by the air supply unit, steam supply unit and inert gas supply unit are delivered to the first reaction container 13 of the metal high-temperature vaporization reaction system through the delivery pipeline 6 for mixing to form mixed gas, the electric heating device 7 wrapped outside the delivery pipeline 6 continuously heats the pipeline, which can not only prevent the condensation of steam, but also preheat the gas to maintain the stability of the gas temperature, the container heating system 22 on the outer wall of the second reaction container 12 is constructed by the ceramic electric heating cord in cooperation with the PID controller and the three K-type armored thermocouples 16 arranged axially, to build a controllable temperature gradient from 1000℃ to room temperature, the hydrophobic valve 17 at the bottom of the first reaction container 13 periodically discharges condensed water to maintain the purity of the gas phase environment, the pressure sensor 15 at the top of the first reaction container 13 detects the pressure in the first reaction container 13 in real time, and cooperates with the third regulating valve 12 to control the flow of air, steam and inert gas; S2: The mixed gas enters the second reaction container 14 through the stainless steel pipe coated with thermal insulation cotton on the outside. The second reaction container 14 is the core reaction zone of the experimental system. The center of the bottom of the second reaction container 14 is provided with a sample carrying assembly 21, and a sample is placed on the sample carrying assembly 21. The sample on the sample carrying assembly 21 in the second reaction container 14 is heated by a laser heater 19 in the metal high-temperature vaporization reaction system, thereby generating an aerosol. The laser heater 19 irradiates the sample from the observation mirror 18 at the top of the second reaction container 14, avoiding radioactive contamination through non-contact heating. The laser heater 19 generates an instantaneous high temperature through irradiation, causing the sample to vaporize and condense in the mixed gas to form an aerosol. The container heating system 22 on the outer wall of the second reaction container 14 is equipped with a PID controller and three K-type armored thermocouples 16 arranged axially to create a controllable temperature gradient from 1000℃ to room temperature, accurately simulating the temperature shock effect in a nuclear accident. The hydrophobic valve 17 at the bottom of the second reaction container 14 periodically discharges condensed water. The aerosol generation state is monitored in real time through the side wall observation mirror 18. The aerosol enters the aerosol sampling and measurement system through the exhaust pipe 20. S3: The aerosol is extracted through the aerosol sampling and measurement system, and the aerosol is deposited through the filter membrane 24. The mixed gas containing the aerosol generated in the second reaction container 14 is sucked into the measurement system through the pipeline by the air pump 27, so that the aerosol passes through the filter membrane 24 made of glass fiber, and the aerosol particles are deposited on the filter membrane 24 for subsequent analysis of the particle size distribution, morphology, and energy spectrum of the aerosol. Finally, the flow detection unit is measured. The air pump 27 in the flow detection unit provides negative pressure for the entire sampling process, ensuring the directional flow of the aerosol to the aerosol sampling and measurement system. The dry gas is condensed through the condensing device 25, and then the flow of the dry gas is measured through the flow controller 26. According to the proportion, the flow of the mixed gas is inversely calculated. After the experiment, the filter membrane 24 is transferred for disposal. The hydrophobic valve 17 at the bottom of the first reaction container 13 and the second reaction container 14 is used to empty the residual liquid. The sealed structure of the first reaction container 13 and the second reaction container 14 can prevent radioactive leakage throughout the process.

[0030] In S1, the mass of air entering the metal high-temperature vaporization reaction system is controlled by the first adjusting valve 3 and the first mass flow meter 4 in the air supply unit. The mass of steam entering the metal high-temperature vaporization reaction system is controlled by the second adjusting valve 10 and the second mass flow meter 11 in the steam supply unit. The mass of inert gas entering the metal high-temperature vaporization reaction system is controlled by the third adjusting valve 12 in the inert gas supply unit. According to the mass of air, steam, and inert gas, the corresponding proportion is calculated to control the composition of the mixed gas.

[0031] In S3, the temperature of the aerosol is measured by the K-type thermocouple 23 in the aerosol sampling measurement system to avoid the influence of temperature anomalies on the subsequent detection accuracy, and the condensing device 25 is used to cool the aerosol to remove the vapor components therein. After the mixed gas enters the condensing device 25, the vapor components in the mixed gas are condensed and separated, and the remaining dry gas passes through the flow controller 26 to measure the air flow. According to the initial gas ratio, the flow of the mixed gas is back calculated, and the air volume flow is measured The mass flow of air is calculated , wherein is the density of air under the environment, is the molar mass of air; according to the molar fraction of steam and the molar flow of air The molar flow of the mixed gas can be calculated The volume flow of the mixed gas can be calculated by the ideal gas state equation , wherein is the gas constant; is the temperature of the mixed gas, measured by the K-type thermocouple 23, is the pressure of the mixed gas, measured by the pressure sensor 15.

[0032] The present application provides an experimental method for generating radionuclides and sampling measurement of an experimental system. The above method can create a high-temperature and complex environment with different gas components, and can also realize sampling measurement of aerosol particles. The above experimental system and experimental method can simulate complex scenarios such as severe accidents by taking temperature, pressure, and gas components as variables, and realize the generation of radionuclide aerosol under different conditions.

[0033] The above disclosed embodiments of the present application are only used to help explain the present application. The embodiments do not describe all the details, nor limit the application to the described embodiments. According to the content of the present application, many modifications and changes can be made. The present application selects and describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application.

Claims

1. An experimental system for generating and sampling radionuclides, characterized in that: The system includes a gas phase environment simulation system, a metal high-temperature vaporization reaction system, and an aerosol sampling and measurement system. The output of the gas phase environment simulation system is connected to the metal high-temperature vaporization reaction system via a delivery pipe (6), and the output of the metal high-temperature vaporization reaction system is connected to the aerosol sampling and measurement system via an exhaust pipe (20). The gas phase environment simulation system includes an air supply unit, a steam supply unit, an inert gas supply unit, and a three-way valve (9). The air supply unit and the steam supply unit are both connected to one end of the delivery pipe (6), and the other end of the delivery pipe (6) is connected to the first port of the three-way valve (9). The second port of the three-way valve (9) is connected to the inert gas supply unit, and the third port of the three-way valve (9) is connected to the metal high-temperature vaporization reaction system via the delivery pipe (6). The metal high-temperature vaporization reaction system includes a first reaction vessel (13), a second reaction vessel (14), a laser heater (19), and a sample carrier assembly (21). The bottom of the first reaction vessel (13) is connected to the delivery pipe (6), and the first reaction vessel (13) and the second reaction vessel (14) are connected to each other. 4) Symmetrically arranged and connected by pipes, the bottom center of the second reaction container (14) is provided with a sample carrier assembly, and the top center of the second reaction container (14) is provided with a laser heater (19). The light path of the laser heater (19) passes through the top of the second reaction container (14) and shines on the sample placed on the sample carrier assembly (21). The second reaction container (14) is connected to the aerosol sampling and measurement system through an exhaust pipe (20). The outer sides of the first reaction container (13) and the second reaction container (14) are covered with a container. The heating system (22) is provided with at least three K-type armored thermocouples (16) evenly spaced along the axial direction on the side walls of the first reaction vessel (13) and the second reaction vessel (14). The aerosol sampling and measurement system includes a filter membrane (24), a condenser (25) and a flow detection unit arranged sequentially along the gas flow direction. The filter membrane (24) is connected to the second reaction vessel (14) through an exhaust pipe (20). A K-type thermocouple (23) is provided on the exhaust pipe (20) and is located in front of the filter membrane (24).

2. The experimental system for generating and sampling radionuclides according to claim 1, characterized in that: The air supply unit includes an air compressor (1) that provides air and a filter (2), a first regulating valve (3) and a first mass flow meter (4) arranged sequentially along the air flow direction. The output end of the first mass flow meter (4) is connected to the delivery pipe (6).

3. The experimental system for generating and sampling radionuclides according to claim 1, characterized in that: The steam supply unit includes an electric steam boiler (5) that provides steam and a second regulating valve (10) and a second mass flow meter (11) arranged sequentially along the steam flow direction. The output end of the second mass flow meter (11) is connected to the conveying pipeline (6).

4. The experimental system for generating and sampling radionuclides according to claim 1, characterized in that: The inert gas supply unit includes a high-pressure gas cylinder (8) for supplying inert gas and a third regulating valve (12) arranged along the inert gas flow direction, wherein the third regulating valve (12) is connected to the second port of a three-way valve (9).

5. The experimental system for generating and sampling radionuclides according to claim 1, characterized in that: The conveying pipeline (6) is covered with an electric heating device (7).

6. The experimental system for generating and sampling radionuclides according to claim 1, characterized in that: The first reaction vessel (13) and the second reaction vessel (14) are each equipped with a drain valve (17) at the bottom and a pressure sensor (15) at the top. The first reaction vessel (13) and the second reaction vessel (14) are each equipped with an observation mirror (18) on the top and front surfaces.

7. The experimental system for generating and sampling radionuclides according to claim 1, characterized in that: The flow detection unit includes a flow controller (26) and a vacuum pump (27) arranged along the gas flow direction.

8. An experimental method for an experimental system for generating and sampling radionuclides as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Gas is supplied to the metal high-temperature vaporization reaction system through the air supply unit, steam supply unit and inert gas supply unit of the gas phase environment simulation system. The gas generated by the air supply unit, steam supply unit and inert gas supply unit is transported to the first reaction vessel (13) of the metal high-temperature vaporization reaction system through the delivery pipe (6) for mixing to form a mixed gas. S2: The mixed gas enters the second reaction vessel (14) and heats the sample on the sample carrier component (21) in the second reaction vessel (14) by the laser heater (19) in the metal high temperature vaporization reaction system, thereby generating aerosol. The aerosol enters the aerosol sampling and measurement system through the exhaust pipe (20). S3: Aerosols are extracted by the aerosol sampling and measurement system, and the aerosols are deposited through the filter membrane (24). Finally, the flow rate is measured by the flow detection unit.

9. The experimental method of the experimental system for generating and sampling radionuclides according to claim 8, characterized in that: In S1, the air quality entering the metal high-temperature vaporization reaction system is controlled by the first regulating valve (3) and the first mass flow meter (4) in the air supply unit, the steam quality entering the metal high-temperature vaporization reaction system is controlled by the second regulating valve (10) and the second mass flow meter (11) in the steam supply unit, and the inert gas quality entering the metal high-temperature vaporization reaction system is controlled by the third regulating valve (12) in the inert gas supply unit, thereby controlling the composition of the mixed gas.

10. The experimental method of the experimental system for generating and sampling radionuclides according to claim 8, characterized in that: In S3, the temperature of the aerosol is measured by the K-type thermocouple (23) in the aerosol sampling and measurement system, and the aerosol is cooled by the condenser (25). The air flow rate is measured by the flow controller (26), and the flow rate of the mixed gas is deduced from the ratio.

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