Device and method for detecting heat carrying capacity of residual heat removal system of micro gas-cooled reactor
Through the combination of Breton circulation system and data acquisition control system, different operating states of micro-air cooled reactors are simulated, and the problem of inability to switch states in the prior art is solved, achieving flexibility and accuracy of experiments at high temperatures.
Patent Information
- Application Number
- CN202510175933.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-18
- Publication Date
- 2025-08-22
- Estimated Expiration
- 2045-02-18
AI Technical Summary
The existing technology cannot effectively simulate the scenarios of micro-air-cooled reactors switching in shutdown and start-up states such as micro-air-cooled reactors, and cannot meet the design needs of micro-air-cooled reactors in operating working fluids and temperature ranges, and lacks experimental verification.
A heat-carrying capacity detection device for the waste heat discharge system of a micro-air-cooled reactor is designed. The Breton circulation system is used to simulate normal operating conditions, and combined with the active and non-active waste heat discharge system, the switching of different operating states is achieved through data acquisition and control system, and the high-temperature resistant alloy material and welding connection are used, and the valve is controlled to adjust to achieve switching of different states.
Experimental simulation of micro-air-cooled reactors in different states is realized, which meets the temperature and leakage rate requirements, increases the achievable experimental working conditions, and improves the flexibility and accuracy of the experiment.
Smart Images
Figure CN120032929B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a technology in the field of reactor control, in particular to a device and method for detecting the heat carrying capacity of a residual heat removal system of a micro gas-cooled reactor. Background Art
[0002] The micro gas-cooled reactor based on the Brayton cycle is characterized by its small size, light weight, long endurance, and high power, and can serve as a reliable power source for remote areas. The residual heat removal system is a safety feature that ensures the safety of nuclear power plants during shutdown and accident conditions. Its importance has been widely practiced in third-generation pressurized water reactors. However, the operating working fluid, thermal cycle system composition, and usage scenarios of micro gas-cooled reactors are significantly different from those of pressurized water reactors. At present, domestic and foreign research on the heat transfer and flow performance of micro gas-cooled reactor residual heat removal systems in steady-state, transient, and operating state switching processes remains at the theoretical stage and lacks experimental verification. Summary of the Invention
[0003] In view of the shortcomings of the existing technology, which is limited by the working fluid and cannot simulate the scenarios of active-passive state switching such as shutdown and startup in the micro gas-cooled reactor, and cannot meet the design requirements of the micro gas-cooled reactor in terms of operating working fluid and temperature range, the present invention proposes a heat carrying capacity detection device and method for the residual heat removal system of a micro gas-cooled reactor. The device can flexibly adjust different gas working fluids, different core simulation sections and heat exchangers to simulate the active and passive residual heat removal characteristics under different gas working fluids and different core and heat exchanger configurations, as well as the Brayton cycle state, active residual heat removal state and passive residual heat removal state of the micro gas-cooled reactor, and can realize switching between different operating states.
[0004] The present invention is achieved through the following technical solutions:
[0005] The present invention relates to a heat carrying capacity detection device for a residual heat removal system of a micro gas-cooled reactor, comprising: a Brayton cycle system for simulating the normal operating conditions of a micro gas-cooled reactor, and a data acquisition and control system respectively connected thereto, and a residual heat removal system for simulating the operating states of active and passive residual heat removal systems under shutdown or accident conditions of the micro gas-cooled reactor. When the residual heat removal system is in an active residual heat removal condition, gas flows out from the compressor outlet, passes through a preheater and a core simulation section in sequence, flows to a first heat exchanger, and flows into the compressor again after passing through a second heat exchanger, completing a cycle; when the residual heat removal system is in a passive condition, high-temperature gas flows out from the core simulation section outlet, and under the driving force formed by the density difference, flows through the first heat exchanger and transfers heat to the heat exchanger, the gas temperature drops, the density rises, and after flowing through a natural circulation driving section, flows into the core simulation section again, completing a cycle.
[0006] Technical Effects
[0007] The present invention uses a Brayton cycle system to simulate the normal operating conditions of a micro gas-cooled reactor, and uses a waste heat removal system to simulate the core waste heat removal conditions of a gas-cooled reactor under shutdown and accident conditions. The compressor in the Brayton cycle system is used to drive the working medium in the circuit, and the start and stop and speed of the compressor can be controlled by a data acquisition and control system. A buffer tank is provided before and after the compressor to stabilize the circuit pressure while reducing the flow fluctuation of the circuit. High-temperature resistant alloys are used as the materials for the pipelines, experimental sections and heat exchangers in the circuit, and welding is used to connect each device to the pipeline to achieve high temperature resistance and low gas leakage rate; the valves in the circuit are controlled by the data material and control system, and can be quickly opened and closed and the opening can be adjusted. During the experiment, the switching between different operating states of the circuit can be achieved by controlling the opening and closing of the valves. This design enables the present invention to meet the temperature and leakage rate requirements of the micro gas-cooled reactor, and the types of experimental conditions that can be achieved are greatly increased compared with similar devices. BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Figure 1 It is a schematic diagram of the structure of the present invention;
[0009] In the figure: 1 compressor, 2 first surge tank, 3 regenerator, 4 preheater, 5 core simulation section, 6 first heat exchanger, 7 natural circulation drive section, 8 pressure reducing plate, 9 second heat exchanger, 10 second surge tank, 11 gas collection and analysis device, 12 data acquisition cabinet, 13 control module, V1 to V12 first valve to twelfth valve, M1 to M3 first flow meter to third flow meter, T1 to T12 first temperature measuring mechanism to twelfth temperature measuring mechanism, P1 to P5 first pressure transmitter to fifth pressure transmitter, DP1 to DP3 first differential pressure transmitter to third differential pressure transmitter;
[0010] Figure 2 This is a schematic diagram of the principle of the present invention. DETAILED DESCRIPTION
[0011] like Figure 1 As shown, this embodiment relates to a natural circulation heat carrying capacity detection system for gas in a passive waste heat removal state, including: a Brayton cycle system and a waste heat removal system, a data acquisition system and a control module respectively connected thereto.
[0012] The Brayton cycle system includes: a regenerator 3 for transferring heat from the hot side fluid to the cold side, a second heat exchanger 9 connected in sequence, a second surge tank 10 for reducing fluid and pressure fluctuations in the loop, a compressor 1 for providing driving force for the fluid, a first surge tank 2 for reducing fluid and pressure fluctuations in the loop, and a preheater 4 connected in sequence, a core simulation section 5 for simulating the heat generation power, structure, and physical-thermal coupling properties of a real reactor core and heating the gas, and a pressure reducing plate 8 for simulating a turbine device, wherein: the output of the first surge tank 2 There are a first valve V1 and a second valve V2 between the end and the cold side inlet of the reheater 3 in sequence, the cold side outlet of the reheater 3 is connected to the input end of the preheater 4, the hot side inlet of the reheater 3 is connected to the pressure reducing plate 8, a sixth valve V6 is provided between the hot side outlet of the reheater 3 and the second heat exchanger 9, an eighth valve V8 is provided between the second heat exchanger 9 and the second pressure stabilizing tank 10, a third valve V3 is provided between the input end of the preheater 4 and the second valve V2, a fourth valve V4 is provided between the output end of the preheater 4 and the core simulation section 5, and a fifth valve V5 is provided between the core simulation section 5 and the pressure reducing plate 8.
[0013] The input end of the second pressure stabilizing tank 10 is provided with a ninth valve V9.
[0014] The residual heat removal system includes: a fourth differential pressure transmitter DP4, a fifth pressure transmitter DP5, a first heat exchanger 6 for extracting heat under residual heat removal conditions, and a natural circulation drive section 7 for providing driving force for the fluid under passive residual heat removal conditions, wherein: the first heat exchanger 6 is connected to the core simulation section 5 through an eleventh valve V11; the fourth differential pressure transmitter DP4 is connected in parallel with the first heat exchanger 6; the first heat exchanger 6 is connected to the natural circulation drive section 7; the fifth pressure transmitter DP5 is connected in parallel with the natural circulation drive section 7, and the output end of the natural circulation drive section 7 is connected to the second heat exchanger 9 through a twelfth valve V12.
[0015] A tenth valve V10 is provided between the input end of the core simulation section 5 and the output end of the natural circulation driving section 7 .
[0016] The data acquisition and control system includes: a control module 13, a data acquisition cabinet 12, and a gas acquisition and analysis device 11, the first to the twelfth temperature measuring devices T1-T12, the first to the fifth pressure transmitters P1-P5 and the first to the third flow meters M1-M3 respectively connected to the data acquisition cabinet 12, wherein: the gas acquisition and analysis device 11 is arranged at the output end of the second heat exchanger 9; the first to the twelfth temperature measuring devices T1-T12 are respectively arranged at the output end of the compressor 1, the cold side inlet of the regenerator 3, and the cold side outlet of the regenerator 3 , the input end of the preheater 4, the input end and output end of the core simulation section 5, the hot side inlet and outlet of the regenerator 3, the input end and output end of the second heat exchanger 9 and the input end and output end of the first heat exchanger 6; the first to fifth pressure transmitters P1-P5 are respectively arranged at the output end of the compressor 1, the cold side inlet of the regenerator 3, the input end of the core simulation section 5, the hot side outlet of the regenerator 3 and the input end of the compressor 1; the first to third flow meters M1-M3 are respectively arranged at the input end and output end of the second valve V2 and the natural circulation drive section 7.
[0017] The pipeline materials used to connect the equipment of the Brayton cycle system and the waste heat removal system are all high-temperature resistant alloys, and the connection method between the pipelines and the equipment is welding to meet the high-temperature operating environment and low gas leakage rate requirements of the micro gas-cooled reactor.
[0018] The first heat exchanger 6 is located at a higher position, creating a natural circulation pattern by utilizing the height difference and gas temperature difference. To reduce heat leakage, the pipelines in the loop are wrapped with insulation and aluminum foil. The device is suitable for chemically inert gases such as helium and argon, as well as their mixtures.
[0019] like Figure 2 As shown, this embodiment relates to a method for detecting the heat carrying capacity of gas in the residual heat discharge state based on the above system, comprising:
[0020] Step 1) After installing the core simulation section 5 and the first heat exchanger 6 of the micro gas-cooled reactor to be tested, start the data acquisition system to carry out leakage rate detection and stamping test to ensure that the circuit meets the required leakage rate and pressure performance.
[0021] Step 2) Based on the working conditions to be simulated, the data acquisition and control system is used to control the instruments in the loop to achieve the state required to carry out the corresponding experiment, and then the experimental test is carried out.
[0022] The experimental tests include: passive residual heat removal experiment, Brayton cycle steady-state and transient experiment, active residual heat removal steady-state and transient experiment, Brayton cycle-active residual heat removal shutdown experiment, Brayton cycle-passive residual heat removal shutdown experiment, active residual heat removal-passive residual heat removal switching experiment, active residual heat removal-Brayton cycle startup experiment, passive residual heat removal-Brayton cycle startup experiment, and passive-active residual heat removal switching experiment.
[0023] The passive residual heat removal experiment includes:
[0024] i) Ensure that the seventh valve V7 is in the closed state and the other valves are in the open state. After the air in the circuit is extracted through the ninth valve V9, the gas to be tested is injected into the circuit. After the pressure in the circuit reaches the set pressure, the ninth valve V9 is closed and the first heat exchanger 6 and the second heat exchanger 9 are opened.
[0025] ii) Close the fourth valve V4, the fifth valve V5, and the twelfth valve V12, start the core simulation section 5, gradually increase its electric heating power to the set value, ensure that the tenth valve V10 and the eleventh valve V11 are fully open, and then carry out the passive residual heat removal experiment.
[0026] In the Brayton cycle steady-state and transient experimental method, after step i), the third valve V3, the tenth valve V10, the eleventh valve V11, and the twelfth valve V12 are closed, and a series of devices in the Brayton cycle system are started. At this time, the system reaches the Brayton cycle state.
[0027] In the steady-state and transient experimental method for active residual heat removal, after step i), the fifth valve V5, the sixth valve V6, and the tenth valve V10 are closed, and the compressor 1 and the core simulation section 5 are opened. At this time, the system reaches the active residual heat removal state.
[0028] The Brayton cycle-active residual heat removal shutdown test method involves first closing the third valve V3, the tenth valve V10, the eleventh valve V11, and the twelfth valve V12 after step i), starting the series of equipment in the Brayton cycle system to achieve Brayton cycle steady-state and transient test conditions. Subsequently, the device operating state is switched from Brayton cycle to active residual heat removal by opening the eleventh valve V11 and the twelfth valve V12 while simultaneously closing the fifth valve V5 and the sixth valve V6.
[0029] The Brayton cycle-passive residual heat removal shutdown test method involves first closing the third valve V3, the tenth valve V10, the eleventh valve V11, and the twelfth valve V12 after step i), starting the series of equipment in the Brayton cycle system to achieve Brayton cycle steady-state and transient test conditions. Subsequently, the tenth valve V10 is opened, compressor 1 is shut down, the eleventh valve V11 is opened, and the fifth valve V5 is closed, switching the system's operating state from Brayton cycle to passive residual heat removal.
[0030] The active-to-passive residual heat removal switching experimental method involves closing the fifth, sixth, and tenth valves V5, V6, and V10 after step i), opening compressor 1 and core simulation section 5, and achieving active residual heat removal. Subsequently, compressor 1 is sequentially closed, the tenth valve V10 is opened, and the twelfth valve V12 is closed, switching the device's operating state from active to passive residual heat removal.
[0031] The active residual heat removal-Brayton cycle startup experimental method involves closing the fifth valve V5, the sixth valve V6, and the tenth valve V10 after step i), and opening the compressor 1 and the core simulation section 5 to achieve the active residual heat removal state. Subsequently, the fifth valve V5 and the sixth valve V6 are opened in sequence, and the eleventh valve V11 and the twelfth valve V12 are closed, switching the device operating state from the active residual heat removal state to the Brayton cycle state.
[0032] The passive residual heat removal-Brayton cycle startup experimental method involves closing the fourth valve V4, the fifth valve V5, and the twelfth valve V12 after step i), starting the core simulation section 5, and achieving the passive residual heat removal state. Subsequently, the fifth valve V5 is opened, the compressor 1 is started, and the tenth valve V10 and the eleventh valve V11 are closed, switching the device's operating state from the passive residual heat removal state to the Brayton cycle.
[0033] In the passive-to-active residual heat removal switching experimental method, after step i), the fourth valve V4, the fifth valve V5, and the twelfth valve V12 are closed, and the core simulation section 5 is started to achieve the passive residual heat removal state. Subsequently, the fourth valve V4 and the twelfth valve V12 are opened in sequence, the compressor 1 is started, and the tenth valve V10 is closed, switching the device operating state from the passive residual heat removal state to the active residual heat removal state.
[0034] Step 3) When the data acquisition and control system monitors that the flow rate of the loop changes by less than 5% within 2000 seconds and the temperature change at the outlet of the experimental section is less than 5% of the total temperature rise, the flow and heat exchange are considered to have reached a stable state. The data at this time is recorded using the data acquisition and control system to obtain the loop operating parameters under this operating condition.
[0035] Step 4) After data recording is completed, the core simulation section 5 is closed. After the temperatures measured by all temperature measuring mechanisms drop below 100° C., the first heat exchanger 6 and the second heat exchanger 9 are closed, and the test is completed.
[0036] After computational fluid dynamics simulation, based on the above passive waste heat removal experiment, with helium as the working fluid, the above device was operated with the parameters in Table 1, and the data that can be obtained are shown in Table 2.
[0037] Table 1. Experimental parameter settings
[0038]
[0039] Table 2. Experimental device operating parameters
[0040]
[0041] The results in Table 2 show that, driven solely by the density difference, helium can remove heat from the core simulation section. The maximum temperature of the gas is 698.1°C, and the maximum temperature of the structural material is 732.3°C, both within the applicable temperature range of the high-temperature-resistant Inconel 625 alloy. Therefore, the waste heat removal system based on this alloy has a good heat-carrying capacity and can achieve long-term stable heat output.
[0042] Compared to existing technologies, the present invention uses a Brayton cycle system to simulate the normal operating conditions of a micro gas-cooled reactor and a residual heat removal system to simulate the core residual heat removal conditions of a gas-cooled reactor during shutdown and accident conditions. The compressor in the Brayton cycle system drives the working fluid in the circuit, and its start, stop, and speed are controlled by a data acquisition and control system. A buffer tank is placed before and after the compressor to stabilize the circuit pressure and reduce flow fluctuations. High-temperature resistant alloys are used for the circuit pipelines, experimental sections, and heat exchangers, and welded connections are used between each component and the pipeline to achieve high temperature resistance and low gas leakage rates. Valves in the circuit are controlled by the data acquisition and control system, allowing for rapid opening and closing and adjustment of opening. During experiments, switching between different operating states of the circuit can be achieved by controlling the opening and closing of the valves. This design enables the present invention to meet the temperature and leakage rate requirements of micro gas-cooled reactors and significantly expands the range of experimental conditions compared to similar devices.
[0043] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principles and purpose of the present invention. The scope of protection of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. All implementation schemes within its scope shall be subject to the constraints of the present invention.
Claims
1. A device for detecting heat carrying capacity of a residual heat removal system of a micro gas-cooled reactor, characterized in that: include: A Brayton cycle system for simulating the normal operating conditions of a micro gas-cooled reactor, and a data acquisition and control system respectively connected thereto, and a residual heat removal system for simulating the operating states of active and passive residual heat removal systems under shutdown or accident conditions of the micro gas-cooled reactor; The residual heat removal system includes: a fourth differential pressure transmitter, a fifth pressure transmitter, a first heat exchanger for removing heat under residual heat removal conditions, and a natural circulation drive section for providing driving force for the fluid under passive residual heat removal conditions, wherein: the first heat exchanger is connected to the core simulation section via an eleventh valve; the fourth differential pressure transmitter is connected in parallel with the first heat exchanger; the first heat exchanger is connected to the natural circulation drive section; the fifth pressure transmitter is connected in parallel with the natural circulation drive section, and the output end of the natural circulation drive section is connected to the second heat exchanger via a twelfth valve; When the residual heat removal system is in the active residual heat removal condition, the gas flows out from the compressor outlet, passes through the preheater and the core simulation section in sequence, flows to the first heat exchanger, and then flows into the compressor again after passing through the second heat exchanger, completing a cycle; when the residual heat removal system is in the passive condition, the high-temperature gas flows out from the core simulation section outlet, and under the driving force formed by the density difference, flows through the first heat exchanger and transfers heat to the heat exchanger. The gas temperature drops and the density increases. After flowing through the natural circulation driving section, it flows into the core simulation section again, completing the cycle; The Brayton cycle system includes: a regenerator for transferring heat from its hot-side fluid to the cold-side, a second heat exchanger connected in series, a second surge tank for reducing fluid and pressure fluctuations within the loop, a compressor for providing driving force for the fluid, a first surge tank for reducing fluid and pressure fluctuations within the loop, and a preheater connected in series, a core simulation section for simulating the heat generation power, structure, and physical-thermal coupling properties of a real reactor core and heating the gas, and a pressure reducing plate for simulating a turbine device, wherein: a first valve and a second valve are connected in series between the output end of the first surge tank and the cold-side inlet of the regenerator, the cold-side outlet of the regenerator is connected to the input end of the preheater, the hot-side inlet of the regenerator is connected to the pressure reducing plate, a sixth valve is provided between the hot-side outlet of the regenerator and the second heat exchanger, an eighth valve is provided between the second heat exchanger and the second surge tank, a third valve is provided between the input end of the preheater and the second valve, a fourth valve is provided between the output end of the preheater and the core simulation section, and a fifth valve is provided between the core simulation section and the pressure reducing plate; The input end of the second pressure stabilizing tank is provided with a ninth valve; A tenth valve is provided between the input end of the core simulation section and the output end of the natural circulation driving section.
2. The heat carrying capacity detection device for the residual heat removal system of a micro gas-cooled reactor according to claim 1 is characterized in that: The data acquisition and control system includes: a control module, a data acquisition cabinet and a gas acquisition and analysis device respectively connected to the data acquisition cabinet, the first to the twelfth temperature measuring mechanism, the first to the fifth pressure transmitter and the first to the third flow meter, wherein: the gas acquisition and analysis device is arranged at the output end of the second heat exchanger; the first to the twelfth temperature measuring mechanism are respectively arranged at the output end of the compressor, the cold side inlet of the regenerator, the cold side outlet of the regenerator, the input end of the preheater, the input end and output end of the core simulation section, the hot side inlet and outlet of the regenerator, the input end and output end of the second heat exchanger and the input end and output end of the first heat exchanger; the first to the fifth pressure transmitters are respectively arranged at the output end of the compressor, the cold side inlet of the regenerator, the input end of the core simulation section, the hot side outlet of the regenerator and the input end of the compressor; the first to the third flow meter are respectively arranged at the input end and the output end of the second valve and the natural circulation drive section.
3. The heat carrying capacity detection device for the residual heat removal system of a micro gas-cooled reactor according to claim 1 is characterized in that: The pipeline materials used to connect the equipment of the Brayton cycle system and the waste heat removal system are all high-temperature resistant alloys, and the connection method between the pipelines and the equipment is welding to meet the high-temperature operating environment and low gas leakage rate requirements of the micro gas-cooled reactor.
4. The heat carrying capacity detection device for the residual heat removal system of a micro gas-cooled reactor according to claim 1 is characterized in that: There is a height difference between the first heat exchanger and the core simulation section, and the first heat exchanger is located at a higher position to form a natural circulation through the height difference and the gas temperature difference. In order to reduce heat leakage, the pipelines in the loop are wrapped with insulation cotton and aluminum foil materials.
5. A method for detecting the heat carrying capacity of gas in the residual heat discharge state based on the system according to any one of claims 1 to 4, characterized in that: include: Step 1) After installing the core simulation section and the first heat exchanger of the micro gas-cooled reactor to be tested, start the data acquisition system to conduct leakage rate detection and pressure testing to ensure that the circuit meets the required leakage rate and pressure performance; Step 2) Based on the desired simulated working conditions, the data acquisition and control system is used to control the instruments in the control loop to achieve the required state for conducting the corresponding experiment, and then the experimental test is carried out; Step 3) When the flow rate of the loop is monitored by the data acquisition and control system and the change in the temperature at the outlet of the experimental section is less than 5% within 2000 seconds and the change in the total temperature rise is less than 5%, the flow and heat exchange are considered to have reached a stable state. The data at this time is recorded by the data acquisition and control system to obtain the loop operating parameters under this working condition; Step 4) After data recording is completed, the core simulation section is closed. After the temperatures measured by all temperature measuring devices drop below 100° C., the first heat exchanger and the second heat exchanger are closed, and the test is completed.
6. The heat carrying capacity detection method according to claim 5, characterized in that: The experimental tests include: passive residual heat removal experiment, Brayton cycle steady-state and transient experiment, active residual heat removal steady-state and transient experiment, Brayton cycle-active residual heat removal shutdown experiment, Brayton cycle-passive residual heat removal shutdown experiment, active residual heat removal-passive residual heat removal switching experiment, active residual heat removal-Brayton cycle startup experiment, passive residual heat removal-Brayton cycle startup experiment, and passive-active residual heat removal switching experiment.
7. The heat carrying capacity detection method according to claim 6, characterized in that: The passive residual heat removal experiment includes: i) Ensure that the seventh valve is closed and the other valves are open. After the air in the circuit is extracted through the ninth valve, gas is injected into the circuit. After the pressure in the circuit reaches the set pressure, the ninth valve is closed and the first and second heat exchangers are opened; ii) Close the fourth, fifth, and twelfth valves, start the core simulation section, gradually increase its electric heating power to the set value, and ensure that the tenth and eleventh valves are fully open. Then, the passive residual heat removal experiment can be carried out; The Brayton cycle steady-state and transient experimental method is as follows: after step i), the third valve, the tenth valve, the eleventh valve, and the twelfth valve are closed, and the series of devices in the Brayton cycle system are started, and the system reaches the Brayton cycle state; In the steady-state and transient experimental methods for active residual heat removal, after step i), the fifth, sixth, and tenth valves are closed, and the compressor and the core simulation section are opened, at which point the system reaches an active residual heat removal state; The Brayton cycle-active residual heat removal shutdown experimental method comprises the following steps: first, after step i), closing the third valve, the tenth valve, the eleventh valve, and the twelfth valve, and starting the series of equipment in the Brayton cycle system to achieve the Brayton cycle steady-state and transient experimental state; then, by opening the eleventh valve and the twelfth valve and simultaneously closing the fifth valve and the sixth valve, the operating state of the device is switched from the Brayton cycle to the active residual heat removal state; The Brayton cycle-passive residual heat removal shutdown experimental method comprises the following steps: first, after step i), closing the third valve, the tenth valve, the eleventh valve, and the twelfth valve, starting the series of equipment in the Brayton cycle system, and achieving the Brayton cycle steady-state and transient experimental state; then, sequentially opening the tenth valve, shutting down the compressor, opening the eleventh valve, and closing the fifth valve, switching the device operating state from the Brayton cycle to the passive residual heat removal state; The active residual heat removal-passive residual heat removal switching experimental method is as follows: after step i), the fifth valve, the sixth valve, and the tenth valve are closed, and the compressor and the core simulation section are opened to achieve the active residual heat removal state; then, the compressor is closed, the tenth valve is opened, and the twelfth valve is closed in sequence to switch the device operating state from the active residual heat removal state to the passive residual heat removal state; The active residual heat removal-Brayton cycle startup experimental method comprises the following steps: after step i), the fifth valve, the sixth valve, and the tenth valve are closed, and the compressor and the core simulation section are opened to achieve the active residual heat removal state; then, the fifth valve and the sixth valve are opened in sequence, and the eleventh valve and the twelfth valve are closed to switch the device operation state from the active residual heat removal state to the Brayton cycle state; The passive residual heat removal-Brayton cycle startup experimental method comprises the following steps: after step i), the fourth valve, the fifth valve, and the twelfth valve are closed, the core simulation section is started, and the passive residual heat removal state is achieved; then, the fifth valve is opened in sequence, the compressor is started, and the tenth and eleventh valves are closed, switching the device operation state from the passive residual heat removal state to the Brayton cycle state; The passive-active residual heat removal switching experimental method is as follows: after step i), the fourth valve, the fifth valve, and the twelfth valve are closed, and the core simulation section is started to reach the passive residual heat removal state; then the fourth valve and the twelfth valve are opened in sequence, the compressor is started, and the tenth valve is closed to change the operating state of the device from the passive residual heat removal state to the active residual heat removal state.