Heating system and heating method for simulating water loss accident

Abstract

The invention discloses a heating system and a heating method for simulating a water loss accident, and belongs to the technical field of nuclear fuel circulation and irradiation effect research, the heating system comprises a fuel rod, the fuel rod comprises a fuel cladding and a fuel core body, the fuel rod is arranged in a quartz tube sample cavity, the whole fuel rod is arranged in a reaction furnace body, and an infrared temperature detector monitors the temperature in real time through a peep window; and data is fed back to the processing box to dynamically adjust power output. The fuel rod is used as a resistance material, low-voltage alternating current is applied, self-heating is achieved through the Joule effect, heat transfer lag of a traditional heating mode is eliminated, the infrared temperature detector monitors the temperature in a non-contact mode through the squint window and feeds back the temperature to the processing box in real time to dynamically adjust power output, and closed-loop control is formed. And the ultrafast temperature rise requirement under the water loss accident working condition is accurately simulated.

Description

Technical Field

[0001] This invention relates to the field of nuclear fuel cycle and irradiation effect research technology, specifically to a heating system and heating method for simulating a loss-of-water accident. Background Technology

[0002] A reactor loss-of-coolant accident (LOCA) occurs when the coolant boundary of a nuclear reactor breaks down, causing coolant loss and exposing the reactor core to a steam environment. This drastic change in heat transfer patterns leads to the accumulation of heat from nuclear decay. The key risks of a LOCA lie in the explosive exothermic reaction of the zirconium-water reactor and the core meltdown mechanism. The temperature rise rate can reach hundreds of degrees Celsius per second, causing a sharp increase in internal pressure in the fuel rods, leading to cladding swelling and rupture, hydrogen explosion, and radioactive release. Transient temperature rise is the core factor in core meltdown, and accurate simulation is needed to study the service behavior of fuel rods under transient temperature rise conditions.

[0003] Heating technologies for experimental furnaces are generally classified into resistance heating and induction heating based on their heating principles. Resistance heating works by using current to generate Joule heat through a resistive material (such as gold wire, silicon carbide rod, or silicon molybdenum rod) and then using thermal radiation to heat the sample. This heating mode is suitable for static high-temperature environments, with a heating rate generally not exceeding 20°C / min, and cannot simulate LOCA transient conditions. Induction heating uses an alternating magnetic field to induce eddy currents in a conductor to generate heat, without direct contact, and heats up extremely quickly. However, it suffers from the "skin effect," which may cause overheating of the cladding surface while the core temperature lags behind. In addition, the dense oxide film on the surface of the fuel cladding after irradiation is non-conductive at low temperatures, blocking magnetic field penetration and causing heating failure. Neither of these two methods can meet the requirements of simulating the ultra-fast heating service environment under fuel rod loss-of-water accidents. This invention proposes a new solution to address these problems. Summary of the Invention

[0004] To overcome at least one of the aforementioned drawbacks, this invention provides a heating system and method for simulating a water loss accident. The objective of this invention can be achieved by employing the following technical solution: A first aspect of this application provides a heating system for simulating a water loss accident, comprising: A fuel rod, comprising a fuel casing and a fuel core, wherein the fuel casing is fitted onto a plurality of fuel cores connected end to end, one end of the fuel rod is a positive electrode and the other end of the fuel rod is a negative electrode; A quartz tube, wherein a sample chamber is formed inside the quartz tube, and the fuel rod is placed inside the sample chamber; The reactor body has a reaction chamber formed inside it, the quartz tube is placed inside the reaction chamber, and the reactor body is provided with a viewing window. The temperature control mechanism includes a power supply, a processing box, and an infrared thermometer. The power supply is connected to the positive and negative electrodes of the fuel rod to apply low-voltage alternating current to the fuel rod, causing the fuel rod to generate Joule heat. The infrared thermometer is used to detect the surface temperature of the fuel rod through the viewing window, and the power supply output is dynamically adjusted through the processing box.

[0005] In one possible implementation, the fuel cladding comprises zirconium alloy, binary alloy, high-entropy alloy, or coated zirconium alloy, and the fuel core comprises uranium dioxide or corundum.

[0006] In one possible implementation, the fuel rod is further provided with an upper end plug fixing device and a lower end plug fixing device. The upper end plug fixing device is used to fix one end of the fuel rod, and the lower end plug fixing device is used to fix the other end of the fuel rod. The lower end plug fixing device is provided with a gas passage pipe for adjusting the internal pressure of the fuel rod.

[0007] In one possible implementation, the furnace wall of the reaction furnace body has a multi-layer structure, and the furnace wall includes an inner furnace wall, a heat insulation layer, a reflective layer, an insulating layer and an outer furnace wall arranged sequentially from the inside to the outside.

[0008] In one possible implementation, the heat insulation layer has a plurality of spaced-apart elongated protrusions, and a gap is formed between the protrusions and the reflective layer to allow airflow to pass through. A swirling airflow channel is formed between adjacent protrusions so that the airflow generated by thermal expansion and contraction can vortex within the swirling airflow channel; and / or, The reflective layer comprises 310s stainless steel; and / or, The insulating layer comprises at least 95% ceramic material; and / or, The outer wall of the furnace body is made of 304 stainless steel.

[0009] In one possible embodiment, the quartz tube includes a tube body and a first sealing cap, the first sealing cap being used to cover the open end of the tube body, and the boat body is made of gas-fired quartz glass material. The reactor body includes a furnace body and a second sealing cover, the second sealing cover being used to cover the open end of the furnace body; Both the first sealing cover and the second sealing cover are provided with electrode lead-out mechanisms for leading out electrodes.

[0010] In one possible implementation, the reactor body is provided with an auxiliary heating mechanism, which includes heating elements disposed at both ends of the reactor body along the axis. The two heating elements are respectively located at both ends of the fuel rod. The heating elements are high-quality silicon molybdenum rods, and a number of high-quality silicon molybdenum rods are distributed circumferentially on the inner wall of the reactor body.

[0011] In one possible implementation, a remote control system is also included. One end of the power supply is connected to the positive electrode of the fuel rod via a first connecting line, and the other end of the power supply is connected to the negative electrode of the fuel rod via a second connecting line. The infrared thermometer, the processing box, the power supply, and the remote control system form a signal transmission network.

[0012] In one possible implementation, the infrared thermometer is connected to the processing box via a third connecting line, the processing box is connected to the power supply via a fourth connecting line, the power supply is connected to the remote control system via a fifth connecting line, and the processing box is connected to the remote control system via a sixth connecting line.

[0013] A second aspect of this application provides a heating method for simulating a water loss accident, applied to the heating system for simulating a water loss accident as described in any one of the first aspects, wherein the heating method includes the following steps: The positive and negative electrodes of the fuel rod, which consists of a fuel cladding and a fuel core, are connected to a power source. Low-voltage AC power is applied to make the fuel rod self-heat, achieving a controllable heating rate of 1℃ / s-200℃ / s. The infrared thermometer monitors the fuel rod temperature in real time through a viewing window, and the power output is controlled by the processing box.

[0014] In one possible implementation, the power supply uses an IGBT digital power module, combined with a waterless power transmission structure, for low-voltage, high-current output.

[0015] The beneficial technical effects of this invention are as follows: According to this disclosure, the heating system for simulating a loss-of-coolant accident simulates a real nuclear fuel rod through a combination structure of fuel cladding and fuel core. The fuel rod is used as a resistive material, and low-voltage alternating current is applied to the electrodes at both ends of the fuel rod. The Joule effect is used to make the fuel rod heat up rapidly, avoiding the heat transfer lag problem of traditional resistance heating or induction heating. An infrared thermometer monitors the surface temperature of the fuel rod non-contactly through a viewing window and feeds the data back to the processing box. The power supply output current is dynamically adjusted to form a fast-response closed-loop control, which meets the ultra-fast heating service environment under a simulated fuel rod loss-of-coolant accident. Attached Figure Description

[0016] The following are given by way of example and without limitation in the accompanying drawings: Figure 1 A schematic diagram of the overall structure provided by an embodiment of the present invention is shown; Figure 2 A schematic diagram of the fuel rod structure provided in an embodiment of the present invention is shown; Figure 3 A schematic diagram of the internal structure of the furnace wall of the reactor body provided in an embodiment of the present invention is shown; Figure 4An enlarged schematic diagram of the internal structure of the furnace wall provided in an embodiment of the present invention is shown.

[0017] In the diagram: 1. Fuel rod; 2. Positive electrode; 3. Negative electrode; 4. Upper end plug fixing device; 5. Lower end plug fixing device; 6. Quartz tube; 7. Reactor body; 8. First sealing cover; 9. Second sealing cover; 10. Viewing window; 11. Infrared thermometer; 12. Processing box; 13. Power supply; 14. Remote control system; 15. First connecting line; 16. Second connecting line; 17. Third connecting line; 18. Fourth connecting line; 19. Fifth connecting line; 20. Sixth connecting line; 21. Fuel cladding; 22. Fuel core; 23. Heat insulation layer; 24. Reflective layer; 25. Insulating layer; 26. Outer wall of the furnace body. Detailed Implementation

[0018] In the following detailed disclosure, these embodiments are fully described with reference to the accompanying drawings. In order to enable those skilled in the art to understand and clarify the technical solution of the present invention more clearly, the embodiments described below are not limited thereto. The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings.

[0019] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0020] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0021] The first aspect of this application, as Figures 1-4As shown, a heating system for simulating a water loss accident is provided, including a fuel rod 1, a quartz tube 6, a reactor body 7, and a temperature control mechanism. The fuel rod 1 includes a fuel cladding 21 and a fuel core 22. The fuel cladding 21 is fitted onto a plurality of fuel cores 22 connected end to end. One end of the fuel rod 1 is a positive electrode 2, and the other end is a negative electrode 3. A sample chamber is formed inside the quartz tube 6, and the fuel rod 1 is placed inside the sample chamber. A reaction chamber is formed inside the reactor body 7, and the quartz tube 6 is placed inside the reaction chamber. A viewing window 10 is provided on the reactor body 7. The temperature control mechanism includes a power supply 13, a processing box 12, and an infrared thermometer 11. The power supply 13 is connected to the positive electrode 2 and the negative electrode 3 of the fuel rod 1 to apply low-voltage alternating current to the fuel rod 1, causing the fuel rod 1 to generate Joule heat. The infrared thermometer 11 is used to detect the surface temperature of the fuel rod 1 through the viewing window 10, and the output of the power supply 13 is dynamically adjusted by the processing box 12.

[0022] The heating system for simulating a loss-of-water accident provided in this embodiment simulates a real nuclear fuel rod 1 through a combination structure of fuel cladding 21 and fuel core 22. The fuel rod 1 is used as a resistive material, and low-voltage alternating current is applied to the electrodes at both ends of the fuel rod 1. The Joule effect is used to make the fuel rod 1 heat up rapidly, avoiding the heat transfer lag problem of traditional resistance heating or induction heating. The infrared thermometer 11 monitors the surface temperature of the fuel rod 1 non-contactly through the viewing window 10 and feeds the data back to the processing box 12. The output current of the power supply 13 is dynamically adjusted to form a fast-response closed-loop control. The heating rate of this heating method can be controlled from 1℃ / s to 200℃ / s, which meets the ultra-fast heating service environment under the simulation of a loss-of-water accident of the fuel rod 1.

[0023] The viewing window 10 can be made of gas-fired quartz glass, which is not easily discolored at high temperatures. The infrared thermometer 11 can monitor the surface temperature of the fuel rod 1 sample through the viewing window 10.

[0024] Among them, the infrared thermometer 11 is movable, and multiple temperature measuring points support full rod temperature field monitoring, ensuring accurate and controllable heating rate.

[0025] Furthermore, the infrared temperature measurement system can employ multiple infrared thermometers 11. One infrared thermometer 11 measures the temperature at the very center of the tube and, together with the processing box 12, controls the temperature of the fuel rod 1. The other two infrared thermometers are used only for temperature measurement on both sides. The measuring points of these two infrared thermometers can move along the axial direction of the tube to measure the temperature at different locations along the entire fuel rod 1. The central infrared thermometer 11 and the processing box 12 form a feedback closed-loop control, which can adjust the heating power and heating time in real time to stabilize the sample surface temperature within the required temperature range. During the heating process, the heating rate is controlled by the infrared temperature measurement system in conjunction with the power supply 13 and the processing box 12 to form a rapid closed-loop control. The central infrared micrometer measures the target temperature and feeds it back to the processing box 12. The processing box 12 processes the signal according to the input heating rate and transmits the signal to the high-power power supply 13. The high-power power supply 13 outputs a corresponding current, thus forming a closed-loop system to precisely control the temperature of the sample tube.

[0026] In one possible implementation, such as Figure 2 As shown, the fuel cladding 21 includes zirconium alloy, binary alloy, high entropy alloy, and coated zirconium alloy, and the fuel core 22 includes uranium dioxide or corundum.

[0027] By short-circuiting the fuel rod 1 through the positive electrode 2 and the negative electrode 3, and applying low-voltage alternating current to the fuel rod 1, Joule heat can be generated through the Joule effect, avoiding the energy loss of traditional resistance heating or induction heating, resulting in higher thermal efficiency. Moreover, the heat is generated directly from inside the fuel rod 1, which is closer to the self-heating state of the fuel rod 1 in actual loss-of-water accidents.

[0028] The electrodes are generally made of metal materials with good electrical conductivity. In addition, they can also serve to fix the fuel rod 1. Copper electrodes are generally selected because they have good electrical conductivity and low processing cost.

[0029] In one possible implementation, such as Figure 1 As shown, the heating system also includes an upper end plug fixing device 4 and a lower end plug fixing device 5. The upper end plug fixing device 4 is used to fix one end of the fuel rod 1, and the lower end plug fixing device 5 is used to fix the other end of the fuel rod 1. The lower end plug fixing device 5 is provided with a gas passage pipe for adjusting the internal pressure of the fuel rod 1.

[0030] Among them, the upper end plug fixing device 4 and the end plug fixing device are clamping fixtures for fixing the fuel rod 1. They can be made of copper and have both electrode function and mechanical clamping function. By contacting both ends of the fuel rod 1, they can achieve stable transmission of low-voltage AC power and ensure the physical fixation of the fuel rod 1 in high-temperature experiments, avoiding displacement deviation.

[0031] Furthermore, an air pipeline can be added to the lower end plug fixing device 5 to connect to an external air source system, dynamically adjust the internal pressure of the fuel rod 1, simulate the swelling and rupture of the casing in a loss-of-water accident, and enhance the diversity of experimental scenarios.

[0032] In one possible implementation, such as Figure 3 and Figure 4 As shown, the furnace wall of the reactor body 7 has a multi-layer structure, which includes an inner furnace wall, a heat insulation layer 23, a reflective layer 24, an insulating layer 25 and an outer furnace wall 26 arranged sequentially from the inside to the outside.

[0033] The inner wall of the furnace, which directly contacts the high-temperature reaction environment, is made of high-temperature resistant alloys or ceramic materials to effectively resist thermal shock and chemical corrosion, ensuring structural integrity. The insulation layer 23 slows heat transfer to the outside, reducing energy loss. The reflective layer 24 (metal reflector) reflects some heat radiation back into the furnace, improving thermal energy utilization and preventing localized overheating. The insulation layer 25 prevents the furnace body from becoming electrically charged, ensuring operational safety, especially suitable for electrothermal experimental environments. The outer wall 26, through mechanical support and sealing design, maintains overall structural strength and adapts to the influence of the external environment.

[0034] Among them, such as Figure 4 As shown, the heat insulation layer 23 has several elongated protrusions arranged at intervals. A gap is formed between the protrusions and the reflective layer 24 to allow airflow to pass through. A swirling air channel is formed between adjacent protrusions so that the airflow generated by thermal expansion and contraction can swirl in the swirling air channel.

[0035] During the heating process, the air expands and contracts due to heat, forming a reciprocating flow in the swirling air duct. The hot air circulates along the swirling air duct under the action of expansion thrust. The convex structure of the insulation layer 23 can effectively slow down the air flow rate, providing sufficient time for heat to fully exchange with the inner wall of the furnace, reducing heat loss, thereby improving the heating rate. It can also avoid the disturbance of the atmosphere inside the furnace caused by rapid air flow, thus ensuring the purity of the atmosphere inside the furnace.

[0036] The gap between the elongated protrusions and the reflective layer 24 forms a directional airflow channel, while the swirling air ducts between adjacent protrusions extend the airflow path through the vortex effect, causing hot air to circulate under the thrust of expansion, thus slowing down the airflow velocity. This also improves the utilization rate of thermal energy within the furnace by extending the heat exchange time, shortening the heating time, and maintaining the stability of the furnace temperature.

[0037] The reflective layer 24 is made of 310s stainless steel, which can maintain its structural integrity at high temperatures (up to 1150℃). The dense Cr2O3 oxide film formed on its surface can effectively reflect heat radiation, reduce heat loss, and improve the utilization rate of thermal energy.

[0038] The insulating layer 25 includes at least 95% ceramic material. High-purity alumina ceramic has extremely low dielectric loss and high resistivity, which can effectively block current leakage. The material maintains structural stability at high temperatures (long-term operating temperature can reach 1600℃) and has both heat dissipation and thermal shock resistance.

[0039] The outer wall 26 of the furnace body is made of 304 stainless steel, which meets the mechanical strength requirements under high temperature conditions. It can also be welded with multiple reinforcing ribs to improve structural stability and extend service life.

[0040] In one possible implementation, such as Figure 1 As shown, the quartz tube 6 includes a tube body and a first sealing cap 8, which is used to cover the open end of the tube body. The boat body is made of gas-refined quartz glass. The reactor body 7 includes a furnace body and a second sealing cap 9, which is used to cover the open end of the furnace body. Both the first sealing cap 8 and the second sealing cap 9 are provided with electrode lead-out mechanisms for leading out electrodes.

[0041] The first sealing cover 8 and the second sealing cover 9 are usually made of heat-resistant 310s stainless steel. The middle electrode lead-out device is made of copper electrode and the insulation structure is made of alumina ceramic, which can prevent the electrode from burning out due to short circuit caused by material volatilization during heat treatment.

[0042] The entire heating process of fuel rod 1 is carried out in the sample chamber of quartz tube 6. Quartz tube 6 is made of gas-refined quartz glass, which has higher purity and quartz crystals as the main structure, making it harder, denser, wear-resistant, pressure-resistant, high-temperature resistant, corrosion-resistant, and impermeable.

[0043] Among them, the sample chamber and viewing window 10 made of gas-refined quartz glass have high light transmittance and high temperature resistance, which can not only observe the experimental process in real time, but also prevent the material from volatilizing and polluting at high temperatures.

[0044] In one possible implementation, the reactor body 7 is provided with an auxiliary heating mechanism, which includes heating elements located at both ends of the reactor body 7 along the axis. The two heating elements are located at both ends of the fuel rod 1, and the heating elements are high-quality silicon molybdenum rods. Several high-quality silicon molybdenum rods are distributed circumferentially on the inner wall of the reactor body.

[0045] Because the fuel rod 1 is connected to connectors and pipes at both ends, the fuel rod 1 dissipates heat faster at both ends, resulting in a higher temperature in the middle and lower temperature at both ends of the test tube. Therefore, heating elements are installed at both ends of the fuel rod 1 to balance the temperature difference between the middle and both ends of the test tube and to balance the axial temperature difference of the fuel rod 1.

[0046] The auxiliary heating device is installed on the inner wall of the reactor body 7. By symmetrically arranging silicon molybdenum rod heating elements at both ends of the reactor body 7 axis, the two ends of the fuel rod 1 are directly heated locally, which effectively offsets the heat loss caused by joints and pipelines, and makes the axial temperature distribution of the fuel rod 1 more uniform.

[0047] The silicon molybdenum rods are evenly distributed circumferentially along the inner wall of the furnace, forming a surrounding heating field. This reduces the radial thermal gradient of the furnace, avoids localized overheating or cold zones, and improves the stability of the reaction environment. In one possible implementation, such as Figure 1 As shown, the heating system also includes a remote control system 14. One end of the power supply 13 is connected to the positive electrode 2 of the fuel rod 1 via a first connecting line 15, and the other end of the power supply 13 is connected to the negative electrode 3 of the fuel rod 1 via a second connecting line 16. The infrared thermometer 11, the processing box 12, the power supply 13 and the remote control system 14 form a signal transmission network.

[0048] The infrared thermometer 11 monitors the temperature of the fuel rod 1 in real time and feeds the data back to the processing box 12 through the signal transmission network. After analysis, the processing box 12 sends an adjustment command to the power supply 13 to achieve dynamic power output and ensure that the temperature is stable within the target range.

[0049] The remote control system 14 supports centralized display and remote adjustment of multiple parameters (such as temperature and current). Operators can intervene in the experimental process in real time through the interface, and the system also has an alarm function for abnormalities.

[0050] In one possible implementation, such as Figure 1 As shown, the infrared thermometer 11 is connected to the processing box 12 via the third connecting line 17, the processing box 12 is connected to the power supply 13 via the fourth connecting line 18, the power supply 13 is connected to the remote control system 14 via the fifth connecting line 19, and the processing box 12 is connected to the remote control system 14 via the sixth connecting line 20.

[0051] In this system, the infrared thermometer 11 transmits temperature data in real time to the processing box 12 via the third connecting line 17. The processing box 12 sends power adjustment commands to the power supply 13 via the fourth connecting line 18, and simultaneously synchronizes data with the remote control system 14 via the sixth connecting line 20, forming a two-way communication link. The power supply 13 receives commands from the remote control system 14 via the fifth connecting line 19, and the processing box 12 provides real-time status feedback via the sixth connecting line 20, achieving hierarchical control and rapid response.

[0052] The second aspect of this application provides a heating method for simulating a loss-of-water accident, applicable to the heating system for simulating a loss-of-water accident in any of the first aspects. The heating method includes the following steps: connecting the positive electrode 2 and negative electrode 3 of the fuel rod 1, which is composed of a fuel casing 21 and a fuel core 22, to a power supply 13, applying low-voltage alternating current to make the fuel rod 1 self-heat, achieving a controllable heating rate of 1℃ / s-200℃ / s; an infrared thermometer 11 monitors the temperature of the fuel rod 1 in real time through a viewing window 10, and controls the output of the power supply 13 via a processing box 12.

[0053] The heating method for simulating a loss-of-coolant accident provided in this embodiment directly applies low-voltage AC power to the electrodes of fuel rod 1, utilizing the Joule heating effect to achieve self-heating of fuel rod 1. The heating rate can be precisely controlled by adjusting the voltage / current within the range of 1℃ / s-200℃ / s, simulating the extreme condition of rapid core temperature rise during a loss-of-coolant accident. The infrared thermometer 11 monitors the surface temperature of fuel rod 1 non-contactly through the viewing window 10, avoiding interference from the installation of traditional thermocouples. After the data is processed by the processing box 12, the output of the power supply 13 is dynamically adjusted to form a closed-loop control, ensuring that the temperature curve matches the preset model.

[0054] Among these features, low-voltage AC power reduces the risk of short circuits and prevents high-voltage breakdown of the casing material. The self-heating mode of fuel rod 1 more closely resembles the localized overheating behavior of fuel elements caused by coolant loss in actual accidents.

[0055] In one possible implementation, the power supply 13 uses an IGBT digital power module, combined with a waterless power transmission structure, for low-voltage, high-current output.

[0056] Among them, the high-power power supply 13 can use IGBTs as digital power modules and ultra-microcrystalline soft magnetic alloy material as the transformer core, equipped with automatic voltage and current feedback and system fault diagnosis and protection functions. The use of high-frequency, high-power IGBT modules allows the current to instantly increase to hundreds or thousands of amperes, ensuring rapid material heating; low-voltage, high-current heating is employed, and high-strength, low-resistance feed electrode materials are used for electrodes, transmission cables, materials, and structural materials. The water-free power transmission method enables faster heating under the same current.

[0057] The remote control system 14 is a control system that sets the heating rate, the maximum temperature, and records the heating and cooling curves. The remote control system 14 can convert the heating rate, target temperature, etc., into electrical signals that match the high-power power supply 13 and input them into the high-power power supply 13.

[0058] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0060] In view of the detailed description above, these and other changes can be made to these embodiments, and this written description includes embodiments of the best mode that disclose the invention. The patent scope of the invention is defined by the claims, which are not limited by this disclosure. The scope of protection of the invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the invention disclosed herein, based on the technical solutions and concepts of the invention, are within the scope of protection of the invention.

Claims

1. A heating system for simulating a water loss accident, characterized in that, include: Fuel rod (1), the fuel rod (1) includes a fuel shell (21) and a fuel core (22), the fuel shell (21) is sleeved on a plurality of fuel cores (22) connected end to end, one end of the fuel rod (1) is a positive electrode (2) and the other end of the fuel rod (1) is a negative electrode (3). A quartz tube (6) is formed inside the quartz tube (6), and the fuel rod (1) is placed inside the sample cavity; The reactor body (7) forms a reaction chamber, the quartz tube (6) is placed in the reaction chamber, and the reactor body (7) is provided with a viewing window (10). The temperature control mechanism includes a power supply (13), a processing box (12), and an infrared thermometer (11). The power supply (13) is connected to the positive electrode (2) and negative electrode (3) of the fuel rod (1) to apply low-voltage AC power to the fuel rod (1) to generate Joule heat. The infrared thermometer (11) is used to detect the surface temperature of the fuel rod (1) through the viewing window (10). The output of the power supply (13) is dynamically adjusted through the processing box (12).

2. The heating system for simulating a water loss accident according to claim 1, characterized in that, The fuel cladding (21) includes zirconium alloy, binary alloy, high entropy alloy, and coated zirconium alloy, and the fuel core (22) includes uranium dioxide or corundum.

3. The heating system for simulating a water loss accident according to claim 1 or 2, characterized in that, It also includes an upper end plug fixing device (4) and a lower end plug fixing device (5). The upper end plug fixing device (4) is used to fix one end of the fuel rod (1), and the lower end plug fixing device (5) is used to fix the other end of the fuel rod (1). The lower end plug fixing device (5) is provided with a gas passage pipe for adjusting the internal pressure of the fuel rod (1).

4. The heating system for simulating a water loss accident according to claim 1, characterized in that, The furnace wall of the reaction furnace body (7) has a multi-layer structure, which includes an inner furnace wall, a heat insulation layer (23), a reflective layer (24), an insulating layer (25), and an outer furnace wall (26) arranged sequentially from the inside to the outside.

5. The heating system for simulating a water loss accident according to claim 4, characterized in that, The heat insulation layer (23) has a plurality of spaced elongated protrusions, and a gap is formed between the protrusions and the reflective layer (24) to allow airflow to pass through. A swirling air channel is formed between adjacent protrusions so that the airflow generated by thermal expansion and contraction can vortex within the swirling air channel; and / or, The reflective layer (24) comprises 310s stainless steel; and / or, The insulating layer (25) comprises at least 95% ceramic material; and / or, The outer wall (26) of the furnace body is made of 304 stainless steel.

6. The heating system for simulating a water loss accident according to claim 1, characterized in that, The quartz tube (6) includes a tube body and a first sealing cap (8), the first sealing cap (8) is used to cover the open end of the tube body, and the boat body is made of gas-fired quartz glass material; The reactor body (7) includes a furnace body and a second sealing cover (9), the second sealing cover (9) being used to cover the open end of the furnace body; Both the first sealing cover (8) and the second sealing cover (9) are provided with electrode lead-out mechanisms for leading out electrodes.

7. The heating system for simulating a water loss accident according to claim 6, characterized in that, The reactor body (7) is provided with an auxiliary heating mechanism. The auxiliary heating mechanism includes heating elements that are distributed at both ends of the reactor body (7) along the axis. The two heating elements are located at both ends of the fuel rod (1). The heating elements are high-quality silicon molybdenum rods, and several high-quality silicon molybdenum rods are distributed circumferentially on the inner wall of the reactor body.

8. The heating system for simulating a water loss accident according to claim 1, characterized in that, It also includes a remote control system (14). One end of the power supply (13) is connected to the positive electrode (2) of the fuel rod (1) via a first connecting line (15), and the other end of the power supply (13) is connected to the negative electrode (3) of the fuel rod (1) via a second connecting line (16). The infrared thermometer (11), the processing box (12), the power supply (13) and the remote control system (14) form a signal transmission network. The infrared thermometer (11) is connected to the processing box (12) via a third connecting line (17). The processing box (12) is connected to the power supply (13) via a fourth connecting line (18). The power supply (13) is connected to the remote control system (14) via a fifth connecting line (19). The processing box (12) is connected to the remote control system (14) via a sixth connecting line (20).

9. A method for raising the temperature to simulate a water loss accident, characterized in that, The heating method, applied to a heating system simulating a water loss accident as described in any one of claims 1-8, comprises the following steps: The positive and negative electrodes of the fuel rod, which consists of a fuel cladding and a fuel core, are connected to a power source. Low-voltage AC power is applied to make the fuel rod self-heat, achieving a controllable heating rate of 1℃ / s-200℃ / s. The infrared thermometer monitors the fuel rod temperature in real time through a viewing window, and the power output is controlled by the processing box.

10. The method for raising the temperature to simulate a water loss accident according to claim 9, characterized in that, The power supply uses IGBT digital power modules and a waterless power transmission structure for low-voltage, high-current output.

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