A LOCA testing device for a nuclear power plant

Abstract

The application relates to a LOCA testing device of a nuclear power plant, which comprises an experiment cabin, a steam supply mechanism and a gas supply mechanism, the steam supply mechanism comprises a steam source and a steam inlet pipe connecting the steam source and the experiment cabin, the gas supply mechanism comprises a gas source and a gas inlet pipe connecting the gas source and the experiment cabin, and a control system is further arranged, a first control valve group is arranged on the steam inlet pipe, a second control valve group is arranged on the gas inlet pipe, the first control valve group and the second control valve group both comprise electromagnetic switch valves and electromagnetic proportional valves which are arranged in parallel, the electromagnetic switch valves and the electromagnetic proportional valves are connected with the control system in control, experiment temperature sensors and experiment pressure sensors for detecting the temperature and the pressure in the cabin are further arranged on the experiment cabin, and the experiment temperature sensors and the experiment pressure sensors are connected with the control system in signal.

Description

Technical Field

[0001] This invention relates to the field of nuclear power safety testing technology, specifically to a LOCA testing device for nuclear power plants. Background Technology

[0002] Currently, most nuclear power plants use light water reactors as the central heat exchange method. The coolant in the primary loop is heated by the reactor core, and the heat is transferred to the water in the secondary or tertiary loops in the steam generator, thus forming steam to drive the turbine generator. The main components of the cooling system are the coolant, the pressure regulation system, and the overpressure protection system. The coolant system mainly includes various connecting pipes between the reactor core and the steam generator. During normal operation, the coolant is injected through pumps, carrying away heat from the reactor core and transferring this heat to the secondary and tertiary loops, where it is converted into steam to drive the turbine. Simultaneously, it cools the reactor, preventing overheating and core meltdown, maintaining reactor core pressure to avoid low pressure causing core boiling or excessive pressure damaging the shell-and-tube material boundary. The coolant also works with controllers within the reactor to regulate the reaction rate, ensuring stable operation of the entire system.

[0003] Loss of Coolant Accident (LOCA) is one of the most critical Design Basis Accidents (DBAs) for light water reactor nuclear power plants. LOCA signifies a deterioration in core cooling conditions, preventing the dissipation of large amounts of accumulated heat and decay heat from fission products. This can lead to the complete loss of function of all four barriers in the light water reactor's defense-in-depth system—the reactor core, cladding, primary pressure boundary, and containment structure. The causes of LOCA are varied, including ruptured conduction pipes, system malfunctions causing deviations from safe operating ranges, and human-caused damage leading to leaks. When a leak occurs, to prevent damage to the containment structure and a potential nuclear accident, the containment structure must be cooled and depressurized. During this process, sprinkler systems are activated to ensure that temperature and pressure remain within acceptable limits, thus maintaining the integrity of the containment structure.

[0004] During LOCA testing, the containment vessel is first subjected to a high-temperature, high-pressure environment, followed by cooling by a spray system. This includes not only cooling with purified water but also neutralizing harmful reaction products through chemical reactions. The reaction process is lengthy and the environment is complex, posing a severe test to the equipment. Therefore, LOCA qualification testing must be performed on nuclear power equipment before it is put into use to ensure that the relevant equipment can continue to perform its intended safety protection functions in the event of a LOCA accident.

[0005] Chinese utility model patent with publication number CN202018832U discloses a nuclear power plant LOCA test device, including a steam boiler, a compressed air storage tank and a steam storage tank, which are connected to the test chamber through fixed pipelines. It can realize LOCA testing of Ap1000 nuclear power plants. However, this design is still insufficient in terms of automation, digitalization and adjustability, and it is difficult to accurately and flexibly simulate the temperature and pressure changes during the LOCA test. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the technical problem to be solved by the present invention is to provide a LOCA testing device for nuclear power plants, which can adjust the pressure and temperature inside the experimental chamber according to different experimental stages, which is conducive to the precise control of experimental parameters and avoids excessive overshoot in the later stages of the experiment from affecting the experimental process.

[0007] To achieve the above objectives, the present invention provides a LOCA testing device for a nuclear power plant, comprising an experimental chamber, a steam supply mechanism, and a gas supply mechanism. The steam supply mechanism includes a steam source and a steam inlet pipe connecting the steam source and the experimental chamber. The gas supply mechanism includes a gas source and a gas inlet pipe connecting the gas source and the experimental chamber. The device also includes a control system. A first control valve group is provided on the steam inlet pipe, and a second control valve group is provided on each of the gas inlet pipes. Both the first and second control valve groups include a parallel electromagnetic switching valve and an electromagnetic proportional valve, both of which are connected to the control system. The experimental chamber is further equipped with an experimental temperature sensor and an experimental pressure sensor for detecting the temperature and pressure inside the chamber, respectively. Both the experimental temperature sensor and the experimental pressure sensor are connected to the control system signal.

[0008] Furthermore, the experimental chamber is provided with multiple steam inlets located at different heights along the height direction, and each steam inlet is connected to a steam inlet pipe.

[0009] Furthermore, the steam source includes a steam storage tank and a gas-fired boiler, the gas-fired boiler being connected to the steam storage tank, and the steam inlet pipe being connected to the steam storage tank.

[0010] Furthermore, the steam storage tank is also equipped with an electric heater, and the control system is connected to the electric heater control.

[0011] Furthermore, the steam source includes multiple steam storage tanks, which are connected in series by a series pipeline, and valves are provided on the series pipeline. The experimental chamber is connected to all the multiple steam storage tanks.

[0012] Furthermore, the gas source includes a gas storage tank and an air compressor. The gas storage tank is connected to a gas inlet pipe, and the air compressor is connected to the gas storage tank for filling the gas storage tank with high-pressure gas.

[0013] Furthermore, it also includes a spraying mechanism, which includes a liquid storage tank, a spray pipe, a spray flow pump, and a flow meter. The spray pipe connects the liquid storage tank and the experimental chamber. The spray flow pump is installed in the spray pipe to provide pumping force. The flow meter is installed in the spray pipe and is connected to the control system signal. The control system is connected to the spray flow pump control.

[0014] Furthermore, it also includes an exhaust mechanism, which includes an exhaust pipe connected to the experimental chamber and a third control valve group disposed on the exhaust pipe. The third control valve group includes a solenoid switch valve and a solenoid proportional valve disposed in parallel, and both the solenoid switch valve and the solenoid proportional valve are connected to the control system.

[0015] Furthermore, the control system includes a host computer main control unit and a slave computer PLC. The host computer main control unit is connected to the slave computer PLC, and the slave computer PLC is connected to the first control valve group, the second control valve group, the experimental temperature sensor, and the experimental pressure sensor, respectively.

[0016] Furthermore, the gas inlet pipe is connected to the top of the experimental chamber.

[0017] As described above, the LOCA testing apparatus of the present invention has the following beneficial effects:

[0018] 1. The steam and gas supply methods have been improved. Two control modes are achieved by using ordinary electromagnetic switching valves and sensitive electromagnetic proportional valves. The steam and gas flow rates at different stages can be adjusted, and the adjustment is made according to the pressure and temperature signals collected by the corresponding sensors. This is conducive to the precise control of experimental parameters and avoids excessive overshoot in the later stages of the experiment, which may affect the experimental process.

[0019] 2. Stable control of spray flow rate: The spray flow pump is controlled by a closed-loop system composed of frequency converters, which can output any value of flow rate, making the flow control more stable and precise.

[0020] 3. Select a method that combines gas boiler and electric heater to heat steam. In the early stage, gas boiler is mainly used to heat the steam to complete the thermal sprint, and in the later stage, electric heater is used to stabilize the system.

[0021] 4. The sensors are arranged reasonably. Considering the heat loss of steam inlet pipes of different lengths, multiple sensors are used to collect the temperature at the steam inlet position in the experimental chamber. The average value is used for feedback control to reduce the oscillation amplitude of system parameters during the experiment.

[0022] 5. By using multiple steam storage tanks connected in series, different exhaust rates can be designed for steam storage tanks in different locations, while also taking into account the pressure and temperature requirements of the experiment. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the LOCA testing device of the present invention.

[0024] Explanation of icon numbers

[0025] 1 Experimental Module

[0026] 11 Experimental Temperature Sensor

[0027] 12 Experimental pressure sensor

[0028] 13 Sewage pipes

[0029] 2. Steam supply mechanism

[0030] 21 Steam Inlet Pipe

[0031] 22 First control valve group

[0032] 23 Steam storage tank

[0033] 231 Steam Temperature Sensor

[0034] 232 Steam Pressure Sensor

[0035] 24 Gas-fired boilers

[0036] 241 Boiler Temperature Sensor

[0037] 242 Boiler Pressure Sensor

[0038] 25 Steam delivery pipe

[0039] 26 One-way solenoid valve

[0040] 27 Gas-liquid separator

[0041] 28 Electric heater

[0042] 29 Series piping

[0043] 3. Gas supply organization

[0044] 31 Gas Inlet Pipe

[0045] 32 Second control valve group

[0046] 33 Gas storage tanks

[0047] 34 Air compressor

[0048] 35 Gas Temperature Sensor

[0049] 36 Gas pressure sensor

[0050] 4. Spraying mechanism

[0051] 41 Liquid storage tanks

[0052] 42 Spray pipe

[0053] 43 Spray flow pump

[0054] 44 Flowmeter

[0055] 45 Pump body cooling fan

[0056] 46 Closed-loop return pipe

[0057] 47 Spray liquid temperature sensor

[0058] 48 Spray liquid pressure sensor

[0059] 5. Exhaust Mechanism

[0060] 51 Exhaust Pipeline

[0061] 52 Third control valve group

[0062] 6 Control System

[0063] 61 Host Computer Main Control Unit

[0064] 62 Lower-level PLC

[0065] 63 Connection Line Detailed Implementation

[0066] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0067] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0068] See Figure 1This invention provides a LOCA testing device for a nuclear power plant, including an experimental chamber 1, a steam supply mechanism 2, and a gas supply mechanism 3. The steam supply mechanism 2 includes a steam source and a steam inlet pipe 21 connecting the steam source and the experimental chamber 1. The gas supply mechanism 3 includes a gas source and a gas inlet pipe 31 connecting the gas source and the experimental chamber 1. It also includes a control system 6. A first control valve group 22 is provided on the steam inlet pipe 21 to control the steam entering the experimental chamber 1. A second control valve group 32 is provided on the gas inlet pipe 31 to control the gas entering the experimental chamber 1. Both the first control valve group 22 and the second control valve group 32 include a solenoid switch valve and a solenoid proportional valve connected in parallel. That is, the 6 can select either the solenoid switch valve or the solenoid proportional valve to control the opening and closing. The two operate independently. Both the solenoid switch valve and the solenoid proportional valve are connected to the control system 6 and their actions are controlled by the control system 6. The experimental chamber 1 is also equipped with an experimental temperature sensor 11 and an experimental pressure sensor 12 for detecting the temperature and pressure inside the chamber, respectively. Both the experimental temperature sensor 11 and the experimental pressure sensor 12 are connected to the control system 6.

[0069] The LOCA testing device of the present invention, when in use, is supplied with steam and high-pressure gas by steam supply mechanism 2 and gas supply mechanism 3 respectively. When the steam is controlled by the first control valve group 22, two modes can be selected: electromagnetic switch valve control or electromagnetic proportional valve control. The gas intake control is similar. In this invention, different control modes can be adopted according to different experimental stages to achieve precise control during the experimental process. Specifically, the pressure and temperature inside the experimental chamber 1 are detected by the experimental pressure sensor 12 and the experimental temperature sensor 11, and the signals are transmitted to the control system 6. The control system 6 controls the action of the first control valve group 22. When the parameters change significantly in the initial stage of the experiment, the steam supply mechanism 2 selects the electromagnetic switch valve in the first control valve group 22 to control the air intake and allow for rapid air intake. When the experiment reaches the stable holding stage, the electromagnetic switch valve is closed, and the electromagnetic proportional valve is used for regulation. Furthermore, the steam intake rate is adjusted in a timely and flexible manner according to the pressure and temperature signals inside the experimental chamber 1 to achieve precise control of the steam intake rate, maintain temperature stability, ensure that the system will not have a large overshoot due to sensor lag, ensure that the experimental data completely encloses the identification curve, meet the control requirements, and improve the accuracy of parameter control. The main function of the gas supply mechanism 3 is to regulate the standard pressure required by the experimental chamber 1. The standard pressure regulation has two stages. The first is in the early stage of the experiment, when a large amount of air is needed to meet the large pressure value changes of the identification curve. At this time, the control system 6 controls the electromagnetic switch valve in the second control valve group 32 to work. The electromagnetic switch valve is used to control the air injection, and the air intake speed is fast enough. The second is after the system completes the peak test and the system enters the stable maintenance stage. At this time, the air injection volume needs to be precisely controlled. The control system 6 controls the electromagnetic switch valve to close, selects the electromagnetic proportional valve to control the air injection, and makes timely and flexible adjustments based on the temperature and pressure signals inside the chamber to achieve precise control of the pressure of the experimental chamber 1.

[0070] See Figure 1 In this embodiment, as a preferred design, the experimental chamber 1 is provided with multiple steam inlets at different heights along the height direction. The steam inlets are preferably located on the same side, and each steam inlet is connected to a steam inlet pipe 21. This ensures more uniform steam filling of the experimental chamber 1, guaranteeing a stable temperature rise within the chamber and preventing fluctuations in temperature and pressure control during the experiment. Preferably, multiple experimental temperature sensors 11 are located at different positions on the experimental chamber 1 to better reflect the actual temperature within the chamber, preventing erroneous temperature information that could lead to an imbalance between temperature and pressure and subsequent oscillations. When two experimental temperature sensors 11 are used, they are placed opposite each other, installed on opposite sides of the experimental chamber 1 at the same height. The installation method and principle of the experimental pressure sensor 12 are the same as those of the experimental temperature sensor 11.

[0071] In this embodiment, the steam source includes a steam storage tank 23 and a gas-fired boiler 24. The gas-fired boiler 24 and the steam storage tank 23 are connected by a steam delivery pipe 25. A steam inlet pipe 21 is connected to the steam storage tank 23. A one-way solenoid valve 26 and a gas-liquid separator 27 are also provided on the steam delivery pipe 25. The gas-fired boiler 24 heats pure water under pressure to generate high-temperature steam. At this time, the pressure inside the boiler is higher than the maximum required pressure of the experimental chamber 1, ensuring sufficient pressure when the steam is transferred to the storage tank. The pressure and temperature inside the gas-fired boiler 24 are detected by a boiler temperature sensor 241 and a boiler pressure sensor 242 on the gas-fired boiler 24, and the signals are transmitted to the control system 6. The high-temperature steam generated by the gas-fired boiler 24 is transported through the steam delivery pipe 25, and after the water is separated by the gas-liquid separator 27, it is transported to the steam storage tank 23 for storage.

[0072] In this embodiment, see Figure 1 Preferably, an electric heater 28 is also provided in the steam storage tank 23, and a steam temperature sensor 231 and a steam pressure sensor 232 are also provided on the steam storage tank 23 to detect the pressure and temperature inside the steam storage tank 23 and transmit the signals to the control system 6 through the line. According to the temperature inside the steam storage tank 23, the electric heater 28 is selected to heat the steam, so that the actual temperature of the steam exceeds the maximum experimental steam temperature. The combination of the two heating methods is beneficial to the gas boiler 24 to achieve maximum efficiency and overcomes the disadvantage of slow speed of pure electric heating.

[0073] In this embodiment, see Figure 1 The steam source includes multiple steam storage tanks 23, which are connected by a series pipeline 29 equipped with valves. Each steam storage tank 23 is connected to the experimental chamber 1 via a steam inlet pipe 21 and a first control valve group 22. Because the existing method uses a single storage tank, local pressure drops and steam flow fluctuations occur when the steam discharge rate is high, affecting temperature and pressure control during experiments. By adopting the above method, the valves on the series pipeline 29 can be opened as needed to connect multiple steam storage tanks 23, allowing for different discharge rates to be designed for different tanks. Simultaneously, steam can be added to one experimental chamber 1, ensuring even steam input and meeting the pressure and temperature requirements of the experiment. Furthermore, the LOCA testing device of a nuclear power plant can also have multiple experimental chambers 1, each connected to all steam storage tanks 23. Then, according to experimental needs, one or more steam storage tanks 23 can be selected to fill the experimental chamber 1 with steam, making it more flexible and convenient.

[0074] In this embodiment, see Figure 1As a preferred design, the gas supply mechanism 3 includes a gas storage tank 33 and an air compressor 34 as its gas source. The gas storage tank 33 is connected to a gas inlet pipe 31, and the air compressor 34 is connected to the gas storage tank 33 to fill it with high-pressure gas. The gas storage tank 33 is also equipped with a gas temperature sensor 35 and a gas pressure sensor 36 to measure the temperature and pressure of the gas inside the tank and transmit the temperature and pressure signals to the control system 6. The control system 6 then controls the air compressor 34 to ensure that the gas in the gas storage tank 33 meets the requirements. Preferably, the gas inlet pipe 31 is connected to the top of the experimental chamber 1. When air is injected, it sinks inside the experimental chamber 1, which facilitates heat exchange with the steam, thereby helping to maintain a uniform and stable temperature inside the experimental chamber 1.

[0075] In this embodiment, see Figure 1 As a preferred design, a spray mechanism 4 is also included. The spray mechanism 4 includes a liquid storage tank 41, a spray pipe 42, a spray flow pump 43, and a flow meter 44. The spray pipe 42 connects the liquid storage tank 41 to the experimental chamber 1. The spray flow pump 43 is installed in the spray pipe 42 to provide pumping force. The flow meter 44 is installed in the spray pipe 42 to detect the flow rate inside the pipe. The flow meter 44 is connected to the control system 6, and the control system 6 is connected to the spray flow pump 43 for control. The control system 6 uses a frequency converter to control the pumping flow rate of the spray flow pump 43. The spray mechanism 4 is used to spray the experimental reagent into the experimental chamber 1. The liquid storage tank 41 is used to store the experimental reagent during the spraying process. The main component of the reagent is boric acid. The liquid storage tank 41 is made of an acid-resistant material. During the spraying process, the flow rate needs to be kept constant as required. However, the pressure in the experimental chamber 1 is constantly changing. The real-time flow rate value is collected by the flow meter 44 and transmitted to the control system 6. The control system 6 changes the frequency of the frequency converter to regulate the pumping flow rate of the spray flow pump 43, ensuring a stable spray flow rate value under changing pressure. Preferably, the liquid storage tank 41 is also equipped with a spray liquid temperature sensor 47 and a spray liquid pressure sensor 48 to detect the temperature and pressure of the experimental reagent in the tank and transmit the information to the control system 6. In this embodiment, a pump cooling fan 45 is also provided to cool the spray flow pump 43. The control system 6 is connected to the pump cooling fan 45. Preferably, the bottom of the experimental chamber 1 is connected to the liquid storage tank 41 through a closed-loop return pipe 46. Under pressure equilibrium, the experimental drug solution in the experimental chamber 1 can be recycled back into the liquid storage tank 41 through the closed-loop return pipe 46.

[0076] In this embodiment, see Figure 1As a preferred design, the system also includes an exhaust mechanism 5. The exhaust mechanism includes an exhaust pipe 51 connected to the experimental chamber 1 and a third control valve group 52 mounted on the exhaust pipe 51. The third control valve group 52 includes a parallel electromagnetic switch valve and an electromagnetic proportional valve, both of which are connected to the control system 6. The working principle of the third control valve group 52 is the same as that of the first control valve group 22. The exhaust mechanism 5 is used to discharge gas or steam from the experimental chamber 1 to regulate the chamber pressure. The exhaust control mode of the exhaust pipe 51 is selected based on the experimental stage. The selection principle is similar to that of injecting steam into the steam storage tank 23 and injecting air into the gas storage tank 33. These modes work in conjunction with each other in different experimental stages. The electromagnetic switch valve or electromagnetic proportional valve in the third control valve group 52 is selected to control the exhaust, preventing sudden pressure drops that could cause the experiment to go out of control. For example, after completing the peak-raising stage test, the system enters a stable holding stage. While adjusting the injected steam and gas, the control system 6 selects to control the electromagnetic proportional valve to adjust the chamber pressure by controlling the exhaust. The exhaust pipe 51 is preferably connected to the lower end of the experimental chamber 1 and is higher than the connection point of the closed-loop return pipe 46. This can prevent the liquid medicine from flowing into the exhaust pipe 51 and causing liquid medicine loss and environmental pollution.

[0077] In this invention, the experimental chamber 1 is the most important core equipment, connecting the steam supply mechanism, gas supply mechanism, spraying mechanism, and exhaust mechanism. The size of the experimental chamber 1 is selected according to the size of the equipment being tested, and the material must be resistant to the corrosion of the high-temperature and high-pressure boric acid liquid during the spraying stage. A drain pipe 13 is also connected to the bottom edge of the experimental chamber 1. After the experiment is completed, the liquid in the experimental chamber 1 is harmlessly discharged through the drain pipe 13.

[0078] In this embodiment, see Figure 1As a preferred design, the control system 6 includes a host computer main control unit 61 and a slave PLC 62. The slave PLC 62 is connected to various functional components and measuring instruments via connecting lines 63. Specifically, the slave PLC 62 is connected to various valves such as the first control valve group 22 and the second control valve group 32, as well as other functional mechanical components such as the spray flow pump 43, controlling the operation of these functional components. The slave PLC 62 is also connected to various measuring instruments such as the experimental temperature sensor 11 and the experimental pressure sensor 12, collecting the measurement data from these instruments. The host computer main control unit 61 has functions such as data acquisition and calculation, parameter setting, command issuance, and interface display. It obtains the collected control quantity information from the slave PLC 62, makes judgments, and issues relevant control commands. The functions of the experimental control system 6 can be modified and control parameters optimized through the control unit. The slave PLC 62 executes the control commands issued by the host computer main control unit 61 and controls the corresponding functional components to continue to work accordingly. The signal transmission and control between the host computer main control unit 61 and the slave PLC 62, as well as between the slave PLC 62 and various measuring instruments and functional components, can all adopt existing communication control technologies.

[0079] Taking the LOCA testing device in this embodiment as an example, the process of conducting an experimental test is as follows:

[0080] First, turn on the gas boiler 24 and air compressor 34 to start working. At the same time, configure the hardware equipment, add the prepared medicine to the liquid storage tank 41, complete the wiring of all electrical equipment in the control system 6, and then turn on the power to start the control system 6 and wait for the execution command.

[0081] The LOCA testing device is turned on and initialized. First, a communication test is performed via connection line 63 to check the working status of all devices. After all devices successfully communicate, the initialization work is completed. The parameters of various field temperature and pressure sensors are configured, mainly including experimental temperature sensor 11 and experimental pressure sensor 12. The device begins to receive real-time temperature and pressure information returned by the sensors. It waits for the gas boiler 24 to generate steam at the required pressure. Then, the condensate is returned through the gas-liquid separator 27, and the steam is injected into the steam storage tank 23 through the steam inlet pipe 21. The electric heater 28 then heats the steam to the required temperature. At the same time, the air compressor 34 continues to work and stores the air required for the experiment in the gas storage tank 33. The liquid in the liquid storage tank 41 is heated to the specified temperature and maintained at the required pressure. When the temperature and pressure reach the experimental requirements at the same time, the experiment begins.

[0082] After adjusting the automatic test control strategy table and confirming the automatic control parameters, the automatic test switch is turned on. The system first performs the peak-raising phase in experimental chamber 1. At this time, the system uses three steam storage tanks 23 to supply steam and water. The gas storage tank 33 and the exhaust pipe 51 select electromagnetic switching valves to control air injection and exhaust. After the system completes the peak-raising phase test, it enters the stable holding phase. At this time, the first control valve group 22, the second control valve group 32, and the third control valve group 52 all select electromagnetic proportional valves to operate. That is, the injection of steam and air, as well as the exhaust, are all controlled by electromagnetic proportional valves. After a period of stable holding, the experimental process proceeds... During the spraying phase, the spray flow pump 43, which is waiting to start, is turned on, and the pump cooling fan 45 is turned on simultaneously. The flow meter 44 begins to return the current flow value. The host computer main control unit 61 controls the slave PLC 62 through feedback, and controls the flow change by adjusting the working frequency of the frequency converter. The condensate in the experimental chamber 1 flows back to the liquid storage tank 41 through the closed-loop return pipe 46. After the spraying phase is completed, the spray flow pump 43 and the pump cooling fan 45 are turned off, and the flow meter 44 no longer returns the flow value. At this time, the LOCA test device returns to the working state before the spraying was turned on and continues to maintain the required temperature and pressure until the entire experiment is completed.

[0083] After the experiment is completed, the gas boiler 24 and air compressor 34 are turned off. The liquid in the liquid storage tank 41 and the experimental chamber 1 are emptied through the drain pipe 13. The steam in the steam storage tank 23 and the air in the gas storage tank 33 in the experimental chamber 1 are emptied. The steam storage tank 23 is allowed to cool down to room temperature. After the emptying and cooling are completed, the relevant equipment is adjusted to the designated safe position in the control system 6. Then the host computer main control unit 61 and the slave computer PLC 62 are turned off. After the power is cut off to the electrical control unit, the relevant valves are manually closed. The experiment ends and the test system is completed.

[0084] As can be seen from the above, the LOCA testing device of the present invention has the following technical effects:

[0085] 1. The steam and gas supply methods have been improved. Two control modes are achieved by using ordinary electromagnetic switching valves and sensitive electromagnetic proportional valves. The steam and gas flow rates at different stages can be adjusted, and the adjustment is made according to the pressure and temperature signals collected by the corresponding sensors. This is conducive to the precise control of experimental parameters and avoids excessive overshoot in the later stages of the experiment, which may affect the experimental process.

[0086] 2. Stable control of spray flow rate: The spray flow pump 43 is controlled by a closed-loop system composed of frequency converter, which can output any value of flow rate, making the flow control more stable and precise.

[0087] 3. The gas boiler 24 and electric heater 28 are selected to heat the steam together. In the early stage, the gas boiler 24 is mainly used to heat the steam to complete the thermal sprint, and in the later stage, electric heating is used to stabilize the system.

[0088] 4. The sensors are arranged reasonably. Considering the heat loss of steam inlet pipes 21 of different lengths, multiple sensors are used to collect the temperature at the steam entry point of experimental chamber 1. The average value is used for feedback control to reduce the oscillation amplitude of system parameters during the experiment.

[0089] 5. By using multiple steam storage tanks 23 connected in series, different exhaust rates can be designed for steam storage tanks 23 in different locations, while also taking into account the pressure and temperature requirements of the experiment.

[0090] 6. It can fully enclose and precisely control the AP1000 standard qualification curve, and quickly adjust the temperature-pressure data in experimental chamber 1. It has the characteristics of good dynamic performance, is not affected by the spray flow rate, has low energy consumption in long-term experiments, and has excellent system performance.

[0091] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0092] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A LOCA testing device for a nuclear power plant, comprising an experimental chamber (1), a steam supply mechanism (2), and a gas supply mechanism (3), wherein the steam supply mechanism (2) comprises a steam source and a steam inlet pipe (21) connecting the steam source and the experimental chamber (1), and the gas supply mechanism (3) comprises a gas source and a gas inlet pipe (31) connecting the gas source and the experimental chamber (1), characterized in that: It also includes a control system (6), on which a first control valve group (22) is provided on the steam inlet pipe (21), and on which a second control valve group (32) is provided on the gas inlet pipe (31). The first control valve group (22) and the second control valve group (32) both include a solenoid switch valve and a solenoid proportional valve connected in parallel, and the solenoid switch valve and the solenoid proportional valve are both connected to the control system (6). The experimental chamber (1) is also provided with an experimental temperature sensor (11) and an experimental pressure sensor (12) for detecting the temperature and pressure inside the chamber, respectively. The experimental temperature sensor (11) and the experimental pressure sensor (12) are both connected to the control system (6) by signal. It also includes an exhaust mechanism (5), which includes an exhaust pipe (51) connected to the experimental chamber (1) and a third control valve group (52) provided on the exhaust pipe (51). The third control valve group (52) includes a solenoid switch valve and a solenoid proportional valve connected in parallel. The system includes a magnetic switch valve and an electromagnetic proportional valve, both of which are connected to the control system (6). When the parameters change significantly in the initial stage of the experiment, the steam supply mechanism (2) selects the electromagnetic switch valve in the first control valve group (22) to control the air intake, and the second control valve group (32) uses an electromagnetic switch to control the air injection. When the experiment reaches the stable holding stage, the control system (6) controls the first control valve group (22) to close the electromagnetic switch valve, uses the electromagnetic proportional valve for regulation, and adjusts the steam entry rate according to the pressure and temperature signals in the experimental chamber (1). The control system (6) controls the electromagnetic switch valve in the second control valve group (32) to close, selects the electromagnetic proportional valve to control the air injection, and adjusts the air entry rate according to the temperature and pressure signals in the chamber. The control system (6) selects the electromagnetic proportional valve in the third control valve group (52) to work, and adjusts the pressure in the experimental chamber (1) by controlling the exhaust.

2. The LOCA testing apparatus according to claim 1, characterized in that: The experimental chamber (1) has multiple steam inlets located at different heights along the height direction, and each steam inlet is connected to a steam inlet pipe (21).

3. The LOCA testing apparatus according to claim 1, characterized in that: The steam source includes a steam storage tank (23) and a gas boiler (24), the gas boiler (24) being connected to the steam storage tank (23), and the steam inlet pipe (21) being connected to the steam storage tank (23).

4. The LOCA testing apparatus according to claim 3, characterized in that: The steam storage tank (23) is also equipped with an electric heater (28), and the control system (6) is connected to the electric heater (28) for control.

5. The LOCA testing apparatus according to claim 3, characterized in that: The steam source includes multiple steam storage tanks (23), which are connected by a series pipeline (29) and a valve is provided on the series pipeline (29). The experimental chamber (1) is connected to the multiple steam storage tanks (23).

6. The LOCA testing apparatus according to claim 1, characterized in that: The gas source includes a gas storage tank (33) and an air compressor (34). The gas storage tank (33) is connected to a gas inlet pipe (31), and the air compressor (34) is connected to the gas storage tank (33) for filling the gas storage tank (33) with high-pressure gas.

7. The LOCA testing apparatus according to claim 1, characterized in that: It also includes a spraying mechanism (4), which includes a liquid storage tank (41), a spray pipe (42), a spray flow pump (43) and a flow meter (44). The spray pipe (42) connects the liquid storage tank (41) and the experimental chamber (1). The spray flow pump (43) is installed in the spray pipe (42) to provide pumping force. The flow meter (44) is installed in the spray pipe (42) and is connected to the control system (6) via signal. The control system (6) is connected to the spray flow pump (43) via control.

8. The LOCA testing apparatus according to claim 1, characterized in that: The control system (6) includes a host computer main control unit (61) and a slave computer PLC (62). The host computer main control unit (61) is connected to the slave computer PLC (62). The slave computer PLC (62) is connected to the first control valve group (22), the second control valve group (32), the experimental temperature sensor (11), and the experimental pressure sensor (12), respectively.

9. The LOCA testing apparatus according to claim 1, characterized in that: The gas inlet pipe (31) is connected to the top of the experimental chamber (1).

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