Experimental device and method for circular tube rupture under internal pressure in nuclear reactor accidents

Abstract

A device and method for testing circular tube rupture under internal pressure in a nuclear reactor accident. The device comprises a circular tube assembly, a cylinder assembly, a gas cylinder, a gas booster, a direct current power supply, a steam generator, and a vacuum pump. The circular tube assembly comprises a metal tube, a core block, a cooling flange, a copper electrode, a ferrule-type reducer, a pressure-inducing tube, a pressure-charging tube, and a pressure transmitter. The metal tube is heated by a direct current power supply and pressurized by the gas cylinder and the gas booster. The cylinder assembly comprises a stainless steel shell, an annular heat shielding layer, an annular tungsten heater, an annular platinum bushing, a cylindrical thermal insulation pad, and a cover. The annular tungsten heater is heated by a direct current power supply and protected from oxidation by air by a vacuum pump. The steam required for the experiment is provided by a steam generator. The device is capable of carrying out transient heating rupture experiments, isothermal creep rupture experiments, and oxidation experiments on the inner surface of the circular tube after rupture under internal pressure. The invention also provides an experimental method.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear reactor structural component performance testing, and in particular to a device and method for testing a circular tube rupture under internal pressure in a nuclear reactor accident. Background Art

[0002] During a nuclear reactor accident, the core loses cooling, causing the core temperature to rise rapidly due to decay heat, heating the cooling water in the core to steam. Consequently, during a nuclear reactor accident, core components are exposed to a high-temperature steam environment. As the temperature rises, the mechanical properties of core components deteriorate, making them more susceptible to deformation and structural damage, impacting the reliability of the core structure. For tubular components subjected to internal pressure (such as fuel element cladding), this process causes the components to expand, and when the stress they are subjected to reaches a limit, they will rupture, thereby losing their containment function. Therefore, studying the rupture behavior of tubular components subjected to internal pressure during nuclear reactor accident conditions is of great significance to the safety design and reliability analysis of nuclear reactors.

[0003] Tube furnaces are currently widely used as heating instruments for experimental studies of the rupture behavior of pipes subjected to internal pressure during nuclear reactor accident conditions. Tube furnaces surround the pipe under investigation with a ceramic tube. Radiation heat transfer from internal heating elements heats the tube first, and then the pipe under investigation, thereby maintaining a uniform temperature field within the pipe. However, when the pipe ruptures, the shockwaves from the released high-pressure gas or the ejection of debris from the pipe's internal filling can easily fracture the tube and even damage the furnace's internal components. Furthermore, due to limitations in the materials used for the heating elements and the ceramic tube, the heating rate of tube furnaces is often limited to ensure long-term operation. For example, a tube furnace using MoSi2 as a heating element typically has a heating rate of no more than 10°C / min, which is insufficient for rapid temperature increases. Furthermore, due to the long heat transfer path, heating the pipe under investigation in a tube furnace is often accompanied by a delay, resulting in a time lag between the temperature response of the pipe under investigation and the power changes of the tube furnace, which presents significant challenges for experimental studies. Summary of the Invention

[0004] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a circular tube rupture test device and method under the action of internal pressure in a nuclear reactor accident, which is used to carry out transient heating rupture tests, isothermal creep rupture tests, and oxidation tests on the inner surface of circular tubes after rupture.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A circular tube rupture experimental device under internal pressure in a nuclear reactor accident includes a circular tube assembly, a cylinder assembly, a gas cylinder 25, a gas booster 26, a first DC power supply 27, a second DC power supply 28, a steam generator 2 and a vacuum pump 1.

[0007] The round tube assembly includes a metal tube 19, an upper cooling flange 7, a lower cooling flange 23, an upper copper electrode 6, a lower copper electrode 22, an upper ferrule reducer 4, a lower ferrule reducer 21, a pressure pipe 5, a pressure charging pipe 20 and a pressure transmitter 3; the metal tube 19 can be filled with a core block 30, there is a gap between the core block 30 and the metal tube 19, and the two end faces of the core block 30 are chamfered; the metal tube 19 is connected to the pressure pipe 5 through the upper ferrule reducer 4, and the other end of the pressure pipe 5 is connected to the pressure transmitter 3; The metal tube 19 is connected to the pressure tube 20 through the lower ferrule reducer 21, the pressure tube 20 is connected to the gas outlet of the gas booster 26, and the gas inlet of the gas booster 26 is connected to the gas cylinder 25; the metal tube 19 is connected to the first DC power supply 27 through the upper copper electrode 6 and the lower copper electrode 22; the upper cooling flange 7 is installed between the upper copper electrode 6 and the upper cover plate 9 of the cylinder assembly, and the lower cooling flange 23 is installed between the lower copper electrode 22 and the lower cover plate 17 of the cylinder assembly.

[0008] The cylinder assembly includes an upper cover plate 9, a stainless steel shell 12, an annular heat shielding layer 13, an annular tungsten heating body 14, an annular platinum bushing 15 and a lower cover plate 17; the annular platinum bushing 15 surrounds the metal tube 19, and there is a gas space between the annular platinum bushing 15 and the metal tube 19; the annular tungsten heating body 14 is nested on the outside of the annular platinum bushing 15 and fits tightly with the annular platinum bushing 15; the annular heat shielding layer 13 is nested on the outside of the annular tungsten heating body 14, and the annular heat shielding layer 13 is wrapped with a stainless steel shell 12, and a pipe joint 11 is welded on the stainless steel shell 12, and the stainless steel shell 12 is connected to the vacuum pump 1 through the pipe joint 11; the upper tungsten electrode 29 and the lower tungsten electrode 24 of the annular tungsten heating body 14 are connected to the second DC power supply 28; the cylindrical upper heat insulation pad 10 Placed on the upper end surface of the annular tungsten heating body 14 and the annular platinum bushing 15, the upper thermal insulation pad 10 has two through holes, which are respectively used to install the metal tube 19 and serve as a water vapor channel; above the upper thermal insulation pad 10 is the upper cover plate 9, and the upper cover plate 9 has two through holes, which are respectively used to install the metal tube 19 and the joint for welding the water vapor outlet 8; the cylindrical lower thermal insulation pad 16 is placed on the lower end surface of the annular tungsten heating body 14 and the annular platinum bushing 15, and the lower thermal insulation pad 16 has two through holes, which are respectively used to install the metal tube 19 and serve as a water vapor channel; below the lower thermal insulation pad 16 is the lower cover plate 17, and the lower cover plate 17 has two through holes, which are respectively used to install the metal tube 19 and the joint for welding the water vapor inlet 18; the steam generator 2 is connected to the joint of the water vapor inlet 18.

[0009] Preferably, graphite packing is used to seal between the upper cover plate 9 and the stainless steel shell 12, and between the upper cover plate 9 and the metal tube 19; graphite packing is used to seal between the lower cover plate 17 and the stainless steel shell 12, and between the lower cover plate 17 and the metal tube 19.

[0010] Preferably, the annular heat shielding layer 13 is made of zirconium dioxide fiber, a high-temperature refractory heat-insulating material.

[0011] Preferably, the core block 30 is cylindrical.

[0012] The circular tube rupture test device under internal pressure in a nuclear reactor accident can carry out transient heating rupture tests, isothermal creep rupture tests, and oxidation tests on the inner surface of the circular tube after rupture, of the circular tube under internal pressure in a nuclear reactor accident.

[0013] The experimental method of the transient heating and rupture experiment of the circular tube under internal pressure under the nuclear reactor accident condition is as follows: complete the installation of the circular tube assembly, start the vacuum pump 1, eliminate the air around the annular tungsten heating body 14, start the first DC power supply 27 and the second DC power supply 28, make the maximum temperature of the annular tungsten heating body 14 and the metal tube 19 reach 300 ° C, start the steam generator 2, after the furnace chamber of the steam generator 2 reaches the target pressure, introduce steam into the cylinder assembly, start the gas cylinder 25 and the gas booster 26, fill the metal tube 19 with gas, monitor the internal pressure of the metal tube 19 through the pressure transmitter 3, and make the internal pressure of the metal tube 19 After the target value is reached and the water vapor in the cylinder assembly flows stably, the heating power of the first DC power supply 27 is increased to heat the metal tube 19 according to the designed temperature change process. When the metal tube 19 ruptures at high temperature, the gas cylinder 25 is closed, the gas booster 26 is closed, the first DC power supply 27 is closed, and the second DC power supply 28 is closed to cool the metal tube 19. After the maximum temperature of the metal tube 19 drops below 400°C, the steam generator 2 is closed and the steam supply is stopped. After the maximum temperature of the annular tungsten heating body 14 drops below 100°C, the vacuum pump 1 is closed. After the temperature of the metal tube 19 drops to room temperature, the round tube assembly is taken out.

[0014] The experimental method of the isothermal creep rupture experiment of the circular tube subjected to internal pressure under the nuclear reactor accident condition is as follows: complete the installation of the circular tube assembly, start the vacuum pump 1, eliminate the air around the annular tungsten heating body 14, start the first DC power supply 27 and the second DC power supply 28, so that the maximum temperature of the annular tungsten heating body 14 and the metal tube 19 both reach 300°C, start the steam generator 2, after the furnace chamber of the steam generator 2 reaches the target pressure, introduce steam into the cylinder assembly, after the water vapor in the cylinder assembly flows stably, increase the heating power of the first DC power supply 27 and the second DC power supply 28 respectively, so that the maximum temperature of the metal tube 19 and the annular tungsten heating body 14 both rise at a rate of 3 to 4°C / s until the maximum temperature of the metal tube 19 reaches the target temperature, adjust the first DC power supply 27 and the second DC power supply 28, and finally increase the maximum temperature of the metal tube 19 and the annular tungsten heating body 14 at a rate of 3 to 4°C / s. The heating power of a DC power supply 27 and a second DC power supply 28 is used to stabilize the maximum temperature of the metal tube 19 at the target temperature. The gas cylinder 25 and the gas booster 26 are turned on to fill the metal tube 19 with gas. The internal pressure of the metal tube 19 is monitored by the pressure transmitter 3 to ensure that the internal pressure of the metal tube 19 reaches the target value. When the metal tube 19 ruptures, the gas cylinder 25 is turned off, the gas booster 26 is turned off, the first DC power supply 27 is turned off, and the second DC power supply 28 is turned off to cool the metal tube 19. When the maximum temperature of the metal tube 19 drops below 400°C, the steam generator 2 is turned off and the steam supply is stopped. When the maximum temperature of the annular tungsten heating body 14 drops below 100°C, the vacuum pump 1 is turned off. When the temperature of the metal tube 19 drops to room temperature, the round tube assembly is taken out.

[0015] The experimental method for the experiment on oxidation of the inner surface of a circular tube after rupture under internal pressure under the said nuclear reactor accident condition is as follows: complete the installation of the circular tube assembly, start the vacuum pump 1, eliminate the air around the annular tungsten heating body 14, start the second DC power supply 28, transfer heat to the metal tube 19 through the annular tungsten heating body 14, so that the maximum temperature of the metal tube 19 reaches 300°C, start the steam generator 2, and after the furnace chamber of the steam generator 2 reaches the target pressure, introduce steam into the barrel assembly to create the required high-temperature oxidizing gas environment to achieve oxidation of the inner surface after the circular tube ruptures, open the gas cylinder 25 and the gas booster 26, fill the metal tube 19 with gas, monitor the internal pressure of the metal tube 19 through the pressure transmitter 3, so that the internal pressure of the metal tube 19 reaches the target value, and after the water vapor in the barrel assembly flows stably, increase the heating of the second DC power supply 28. Power is adjusted to heat the metal tube 19 according to the designed temperature change process. When the metal tube 19 ruptures, the gas cylinder 25 is turned off, the gas booster 26 is turned off, and the heating power of the second DC power supply 28 is adjusted to heat the metal tube 19 according to the designed temperature change process until the maximum temperature of the metal tube 19 reaches the target temperature. The heating power of the second DC power supply 28 is adjusted to stabilize the maximum temperature of the metal tube 19 at the target temperature. Timing starts from the moment when the temperature of the metal tube 19 stabilizes. After the timing reaches the target length, the second DC power supply 28 is turned off to cool the metal tube 19. When the maximum temperature of the metal tube 19 drops below 400°C, the steam generator 2 is turned off, and the steam supply is stopped. When the maximum temperature of the annular tungsten heating body 14 drops below 100°C, the vacuum pump 1 is turned off, and when the temperature of the metal tube 19 drops to room temperature, the round tube assembly is taken out.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The metal tube can be heated directly by a DC power supply or indirectly by a ring-shaped tungsten heater. Various heating modes such as constant rate, stepped power, and user-defined temperature curves can be achieved by adjusting the DC power supply power to meet the needs of various experimental types and experimental conditions.

[0018] 2. The design of an annular tungsten heater, an annular platinum bushing and a vacuum pump can achieve rapid temperature rise and create a high-temperature oxidizing gas environment of at least 1500°C for a long time;

[0019] 3. The inner wall of the cylinder assembly is a nested and fitted annular tungsten heating element and an annular platinum bushing, both of which are made of metal and are not easily damaged by the impact of airflow caused by metal tube rupture or pellet fragments;

[0020] 4. By filling the metal tube with pellets, the effect of the gas volume inside the metal tube on the rupture behavior of the metal tube under the same internal pressure can be studied. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the experimental device for circular tube rupture under internal pressure in a nuclear reactor accident according to the present invention.

[0022] Figure 2 The present invention is a schematic structural diagram of a metal tube filled with pellets in a circular tube rupture experimental device under internal pressure in a nuclear reactor accident. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments:

[0024] like Figure 1 As shown, a circular tube rupture experimental device under the action of internal pressure in a nuclear reactor accident includes a circular tube assembly, a cylinder assembly, a gas cylinder 25, a gas booster 26, a first DC power supply 27, a second DC power supply 28, a steam generator 2, and a vacuum pump 1.

[0025] The round tube assembly as described above includes a metal tube 19, an upper cooling flange 7, a lower cooling flange 23, an upper copper electrode 6, a lower copper electrode 22, an upper ferrule reducer 4, a lower ferrule reducer 21, a pressure lead pipe 5, a pressure charging pipe 20, and a pressure transmitter 3. Figure 2As shown, the interior of the metal tube 19 can be filled with cylindrical pellets 30, with a gap between the pellets 30 and the metal tube 19. The two end faces of the pellets 30 are chamfered to facilitate filling into the metal tube 19. The volume of gas within the metal tube 19 can be controlled by adjusting the number of pellets 30. The metal tube 19 is connected to a pressure-inducing pipe 5 via an upper compression-type reducer 4. The other end of the pressure-inducing pipe 5 is connected to a pressure transmitter 3, which measures the internal pressure of the metal tube 19. The metal tube 19 is connected to a charging pipe 20 via a lower compression-type reducer 21. The charging pipe 20 is connected to the gas outlet of a gas booster 26, whose gas inlet is connected to a gas cylinder 25. The gas cylinder 25 provides inert gas. The gas from the cylinder 25 reaches the required pressure after passing through the gas booster 26 and is then filled into the metal tube 19. The metal tube 19 is connected to a first DC power supply 27 via an upper copper electrode 6 and a lower copper electrode 22, forming a current loop. The wire connecting the upper copper electrode 6 and the lower copper electrode 22 to the first DC power supply 27 is made of metallic copper. After the first DC power supply 27 is started, current is generated and passes through the metal tube 19, thereby heating the metal tube 19. Since the resistance of the copper wire, the upper copper electrode 6, and the lower copper electrode 22 is relatively small, the copper wire, the upper copper electrode 6, and the lower copper electrode 22 will not generate significant heat. In order to prevent the metal tube 19 near the upper copper electrode 6 and the lower copper electrode 22 from being too hot, thereby causing the upper copper electrode 6 and the lower copper electrode 22 to oxidize, thereby affecting the heating power, the present invention installs an upper cooling flange 7 between the upper copper electrode 6 and the upper cover plate 9 of the cylinder assembly, and installs a lower cooling flange 23 between the lower copper electrode 22 and the lower cover plate 17 of the cylinder assembly, thereby reducing the temperature at both ends of the metal tube 19.

[0026] The cylinder assembly as described above includes an upper cover plate 9, a stainless steel shell 12, an annular heat shielding layer 13, an annular tungsten heater 14, an annular platinum bushing 15 and a lower cover plate 17. The annular platinum bushing 15 surrounds the metal tube 19, and there is a gas space between the annular platinum bushing 15 and the metal tube 19. The annular tungsten heater 14 is nested on the outside of the annular platinum bushing 15 and fits tightly with the annular platinum bushing 15. Metal platinum has excellent antioxidant properties and can prevent the annular tungsten heater 14 from being oxidized by high-temperature water vapor during the experiment. The annular heat shielding layer 13 is nested on the outside of the annular tungsten heater 14. The annular heat shielding layer 13 is made of zirconium dioxide fiber, a high-temperature refractory insulation material, and has a high thermal resistance. It can reduce the outer surface temperature of the cylinder assembly and ensure the safety of the experimenters. The annular heat shielding layer 13 is wrapped with a stainless steel shell 12, and a pipe joint 11 is welded to the stainless steel shell 12. The stainless steel shell 12 is connected to the vacuum pump 1 through the pipe joint 11. The function of the vacuum pump 1 is to evacuate the annular space formed by the annular platinum bushing 15 and the stainless steel shell 12 during the experiment to prevent the annular tungsten heater 14 from being oxidized by air. The upper tungsten electrode 29 and the lower tungsten electrode 24 of the annular tungsten heater 14 are connected to the second DC power supply 28 via copper wires to form a current loop. After the second DC power supply 28 is started, a current is generated through the annular tungsten heater 14, causing the annular tungsten heater 14 to generate heat. The function of the annular tungsten heater 14 is to prevent water vapor from condensing during the experiment. At the same time, the annular tungsten heater 14 generates heat more uniformly in the circumferential direction. By transferring heat to the metal tube 19, the circumferential temperature difference of the metal tube 19 can be reduced. A cylindrical upper thermal insulation pad 10 is placed on the upper end surface of the annular tungsten heater 14 and the annular platinum bushing 15. The upper thermal insulation pad 10 has two through holes, one for installing the metal tube 19 and the other as a water vapor channel. Above the upper thermal insulation pad 10 is the upper cover plate 9 of the cylinder assembly. The upper cover plate 9 has two through holes, which are used to install the metal tube 19 and the joint for welding the water vapor outlet 8. The upper thermal insulation pad 10 can prevent the upper cover plate 9 from overheating and ensure the safety of the experimenters. Through the compression fit of the upper cover plate 9, the upper end faces of the annular tungsten heating element 14 and the annular platinum bushing 15 can be sealed. Graphite packing is used for sealing between the upper cover plate 9 and the stainless steel shell 12, and between the upper cover plate 9 and the metal tube 19. It can work stably for a long time in a high-temperature environment, maintain stable physical properties, and will not age, deform or fail. It can also withstand greater pressure in a high-pressure environment without leakage, ensuring the sealing and work safety of the system. A cylindrical lower thermal insulation pad 16 is placed on the lower end faces of the annular tungsten heating element 14 and the annular platinum bushing 15. The lower thermal insulation pad 16 has two through holes, which are used to install the metal tube 19 and serve as a water vapor channel. Below the lower heat-insulating pad 16 is the lower cover plate 17 of the cylinder assembly. The lower cover plate 17 has two through holes, which are used to install the metal pipe 19 and weld the joint of the water vapor inlet 18 respectively.The lower thermal insulation pad 16 can prevent the temperature of the lower cover plate 17 from being too high, ensuring the safety of the experimenters. The lower end surface of the annular tungsten heating element 14 and the annular platinum bushing 15 can be sealed by the compression fit of the lower cover plate 17. Graphite packing is used for sealing between the lower cover plate 17 and the stainless steel shell 12, and between the lower cover plate 17 and the metal tube 19. It can work stably for a long time in a high-temperature environment, maintain stable physical properties, and will not age, deform or fail. It can also withstand greater pressure in a high-pressure environment without leakage, ensuring the sealing and working safety of the system. The steam generator 2 is connected to the joint of the water vapor inlet 18 through a pipeline. The steam generator 2 can provide the water vapor required for the experimental process.

[0027] The circular tube rupture test device under internal pressure in a nuclear reactor accident can carry out transient heating rupture tests, isothermal creep rupture tests, and oxidation tests on the inner surface of the circular tube after rupture, of the circular tube under internal pressure in a nuclear reactor accident.

[0028] The experimental method of the transient heating and rupture experiment of the circular tube under internal pressure under the nuclear reactor accident condition is as follows: complete the installation of the circular tube assembly, start the vacuum pump 1, eliminate the air around the annular tungsten heating body 14, start the first DC power supply 27 and the second DC power supply 28, make the maximum temperature of the annular tungsten heating body 14 and the metal tube 19 reach 300 ° C, start the steam generator 2, after the furnace chamber of the steam generator 2 reaches the target pressure, introduce steam into the cylinder assembly, start the gas cylinder 25 and the gas booster 26, fill the metal tube 19 with gas, monitor the internal pressure of the metal tube 19 through the pressure transmitter 3, and make the internal pressure of the metal tube 19 After the target value is reached and the water vapor in the cylinder assembly flows stably, the heating power of the first DC power supply 27 is increased to heat the metal tube 19 according to the designed temperature change process. When the metal tube 19 ruptures at high temperature, the gas cylinder 25 is closed, the gas booster 26 is closed, the first DC power supply 27 is closed, and the second DC power supply 28 is closed to cool the metal tube 19. After the maximum temperature of the metal tube 19 drops below 400°C, the steam generator 2 is closed and the steam supply is stopped. After the maximum temperature of the annular tungsten heating body 14 drops below 100°C, the vacuum pump 1 is closed. After the temperature of the metal tube 19 drops to room temperature, the round tube assembly is taken out.

[0029] The experimental method for the isothermal creep rupture experiment of a circular tube subjected to internal pressure under the nuclear reactor accident condition is as follows: after completing the installation of the circular tube assembly, starting the vacuum pump 1, eliminating the air around the annular tungsten heating body 14, starting the first DC power supply 27 and the second DC power supply 28, causing the maximum temperature of the annular tungsten heating body 14 and the metal tube 19 to reach 300°C, starting the steam generator 2, and after the furnace chamber of the steam generator 2 reaches the target pressure, introducing steam into the cylinder assembly, and after the water vapor in the cylinder assembly flows stably, respectively increasing the heating power of the first DC power supply 27 and the second DC power supply 28, causing the maximum temperature of the metal tube 19 and the annular tungsten heating body 14 to rise at a rate of 3 to 4°C / s until the maximum temperature of the metal tube 19 reaches the target temperature, adjusting the first DC power supply 27 and the second DC power supply 28. 28 heating power, so that the maximum temperature of the metal tube 19 is stabilized at the target temperature, the gas cylinder 25 and the gas booster 26 are turned on, and the gas is filled into the metal tube 19. The internal pressure of the metal tube 19 is monitored by the pressure transmitter 3, so that the internal pressure of the metal tube 19 reaches the target value. The metal tube 19 creeps and expands under the action of the internal and external pressure difference. When the metal tube 19 ruptures, the gas cylinder 25 is turned off, the gas booster 26 is turned off, the first DC power supply 27 is turned off, and the second DC power supply 28 is turned off to cool the metal tube 19. When the maximum temperature of the metal tube 19 drops below 400°C, the steam supply is stopped, the steam generator 2 is turned off, and the steam supply is stopped. When the maximum temperature of the annular tungsten heating body 14 drops below 100°C, the vacuum pump 1 is turned off, and the temperature of the metal tube 19 drops to room temperature, the round tube assembly is taken out.

[0030] The experimental method for the post-rupture oxidation experiment on the inner surface of a circular tube subjected to internal pressure under nuclear reactor accident conditions is as follows: after completing the installation of the circular tube assembly, start the vacuum pump 1 to eliminate the air surrounding the annular tungsten heater 14, start the second DC power supply 28, and transfer heat from the annular tungsten heater 14 to the metal tube 19, causing the maximum temperature of the metal tube 19 to reach 300°C. Because the metal tube 19 would experience significant losses due to the oxidation reaction in this experiment, the first DC power supply 27 was not used to heat the metal tube 19 to avoid difficulty in adjusting the heating power due to resistance changes. Start the steam generator 2. After the furnace chamber of the steam generator 2 reaches the target pressure, introduce steam into the cylinder assembly to create the required high-temperature oxidizing gas environment and realize oxidation of the inner surface of the round tube after it ruptures. Turn on the gas cylinder 25 and the gas booster 26 to fill the metal tube 19 with gas. The internal pressure of the metal tube 19 is monitored by the pressure transmitter 3 to make the internal pressure of the metal tube 19 reach the target value. After the water vapor in the cylinder assembly flows stably, increase the heating power of the second DC power supply 28 to make the metal tube 19 heat up according to the designed temperature change process. When the metal tube 19 ruptures, turn off the gas cylinder 25 and the gas booster 26. The water vapor can pass through the rupture of the metal tube 19 and oxidize to the inside of the metal tube 19. Surface contact, adjust the heating power of the second DC power supply 28, so that the metal tube 19 continues to heat up according to the designed temperature change process until the maximum temperature of the metal tube 19 reaches the target temperature, adjust the heating power of the second DC power supply 28, so that the maximum temperature of the metal tube 19 is stabilized at the target temperature, start timing from the moment the temperature of the metal tube 19 is stable, after the timing reaches the target length, turn off the second DC power supply 28, and cool the metal tube 19, wait for the maximum temperature of the metal tube 19 to drop below 400 ℃, turn off the steam generator 2, stop supplying steam, wait for the maximum temperature of the annular tungsten heating body 14 to drop below 100 ℃, turn off the vacuum pump 1, wait for the temperature of the metal tube 19 to drop to room temperature, and take out the round tube assembly.

[0031] The above content is a further detailed description of the present invention in combination with specific principles. It cannot be determined that the specific implementation scheme of the present invention is limited to this. For practitioners to whom the present invention belongs, simple deductions or replacements made without departing from the concept of the present invention should be within the scope of protection of the present invention.

Claims

1. A test device for detecting the rupture of a circular tube under internal pressure during a nuclear reactor accident, characterized by: The invention comprises a round tube assembly, a barrel assembly, a gas cylinder (25), a gas booster (26), a first DC power supply (27), a second DC power supply (28), a steam generator (2) and a vacuum pump (1); the round tube assembly comprises a metal tube (19), an upper cooling flange (7), a lower cooling flange (23), an upper copper electrode (6), a lower copper electrode (22), an upper ferrule-type reducer (4), a lower ferrule-type reducer (21), a pressure-inducing pipe (5), a pressure-charging pipe (20) and a pressure transmitter (3); a core block (30) is filled inside the metal tube (19), a gap exists between the core block (30) and the metal tube (19), and two end faces of the core block (30) are processed with chamfers; the metal tube (19) is connected to the upper ferrule-type reducer ( 4) is connected to the pressure-inducing pipe (5), and the other end of the pressure-inducing pipe (5) is connected to the pressure transmitter (3); the metal pipe (19) is connected to the pressure-charging pipe (20) through the lower sleeve-type reducer (21), the pressure-charging pipe (20) is connected to the gas outlet of the gas booster (26), and the gas inlet of the gas booster (26) is connected to the gas cylinder (25); the metal pipe (19) is connected to the first DC power supply (27) through the upper copper electrode (6) and the lower copper electrode (22); an upper cooling flange (7) is installed between the upper copper electrode (6) and the upper cover plate (9) of the barrel assembly, and a lower cooling flange (23) is installed between the lower copper electrode (22) and the lower cover plate (17) of the barrel assembly; the barrel assembly includes an upper cover plate (9), a non- The invention relates to a stainless steel shell (12), an annular heat shielding layer (13), an annular tungsten heating body (14), an annular platinum bushing (15) and a lower cover plate (17); the annular platinum bushing (15) surrounds the metal tube (19), and a gas space is formed between the annular platinum bushing (15) and the metal tube (19); the annular tungsten heating body (14) is nested on the outside of the annular platinum bushing (15) and fits tightly with the annular platinum bushing (15); the annular heat shielding layer (13) is nested on the outside of the annular tungsten heating body (14), and the annular heat shielding layer (13) is wrapped with a stainless steel shell (12); a pipe joint (11) is welded on the stainless steel shell (12), and the stainless steel shell (12) is connected to the vacuum pump (1) through the pipe joint (11); the upper tungsten of the annular tungsten heating body (14 ... The electrode (29) and the lower tungsten electrode (24) are connected to the second DC power supply (28); the cylindrical upper thermal insulation pad (10) is placed on the upper end surface of the annular tungsten heating body (14) and the annular platinum bushing (15), and the upper thermal insulation pad (10) has two through holes, which are respectively used to install the metal pipe (19) and serve as a water vapor passage; the upper part of the upper thermal insulation pad (10) is provided with an upper cover plate (9), and the upper cover plate (9) has two through holes, which are respectively used to install the metal pipe (19) and weld the joint of the water vapor outlet (8); the cylindrical lower thermal insulation pad (16) is placed on the lower end surface of the annular tungsten heating body (14) and the annular platinum bushing (15), and the lower thermal insulation pad (16) has two through holes, which are respectively used to install the metal pipe (19) and serve as a water vapor passage;Below the lower heat insulation pad (16) is a lower cover plate (17), which has two through holes for installing a metal pipe (19) and welding a joint of a water vapor inlet (18), respectively; the steam generator (2) is connected to the joint of the water vapor inlet (18).

2. The apparatus for testing the rupture of a circular tube under internal pressure in a nuclear reactor accident according to claim 1, characterized in that: Graphite packing is used to seal between the upper cover plate (9) and the stainless steel shell (12), and between the upper cover plate (9) and the metal tube (19); and graphite packing is used to seal between the lower cover plate (17) and the stainless steel shell (12), and between the lower cover plate (17) and the metal tube (19).

3. The apparatus for testing the rupture of a circular tube under internal pressure in a nuclear reactor accident according to claim 1, characterized in that: The annular heat shielding layer (13) is made of high-temperature fire-resistant heat-insulating material zirconium dioxide fiber.

4. The apparatus for testing the rupture of a circular tube under internal pressure during a nuclear reactor accident according to claim 1, characterized in that: The core block (30) is cylindrical.

5. The experimental method of the apparatus for testing the rupture of a circular tube under internal pressure in a nuclear reactor accident according to any one of claims 1 to 4, characterized in that: The experimental device can carry out transient heating rupture tests, isothermal creep rupture tests, and oxidation tests on the inner surface of circular tubes after rupture, under nuclear reactor accident conditions. The experimental method of the transient heating rupture experiment of a circular tube under internal pressure under the working condition of a nuclear reactor accident is as follows: completing the installation of the circular tube assembly, starting the vacuum pump (1), eliminating the air around the annular tungsten heating body (14), starting the first DC power supply (27) and the second DC power supply (28), making the maximum temperature of the annular tungsten heating body (14) and the metal tube (19) reach 300°C, starting the steam generator (2), and after the furnace chamber of the steam generator (2) reaches the target pressure, introducing steam into the cylinder assembly, opening the gas cylinder (25) and the gas booster (26), filling the metal tube (19) with gas, monitoring the internal pressure of the metal tube (19) through the pressure transmitter (3), and making the internal pressure of the metal tube (19) reach 300°C. When the water vapor in the cylinder assembly reaches the target value and flows stably, the heating power of the first DC power supply (27) is increased to heat the metal tube (19) according to the designed temperature change process. When the metal tube (19) ruptures at high temperature, the gas cylinder (25) is closed, the gas booster (26) is closed, the first DC power supply (27) is closed, the second DC power supply (28) is closed, and the metal tube (19) is cooled. When the maximum temperature of the metal tube (19) drops below 400°C, the steam generator (2) is closed, and the steam supply is stopped. When the maximum temperature of the annular tungsten heating body (14) drops below 100°C, the vacuum pump (1) is closed, and when the temperature of the metal tube (19) drops to room temperature, the round tube assembly is taken out. The experimental method of the isothermal creep rupture experiment of the circular tube under internal pressure under the nuclear reactor accident condition is as follows: completing the installation of the circular tube assembly, starting the vacuum pump (1), eliminating the air around the annular tungsten heating body (14), starting the first DC power supply (27) and the second DC power supply (28), making the maximum temperature of the annular tungsten heating body (14) and the metal tube (19) reach 300°C, starting the steam generator (2), after the furnace chamber of the steam generator (2) reaches the target pressure, introducing steam into the barrel assembly, after the water vapor in the barrel assembly flows stably, respectively increasing the heating power of the first DC power supply (27) and the second DC power supply (28), making the maximum temperature of the metal tube (19) and the annular tungsten heating body (14) rise at a rate of 3 to 4°C / s, until the maximum temperature of the metal tube (19) reaches the target temperature, adjusting the first DC power supply (27) and the second DC power supply (28), and finally increasing the heating power of the first DC power supply (27) and the second DC power supply (28). 7) and the heating power of the second DC power supply (28), so that the maximum temperature of the metal tube (19) is stabilized at the target temperature, the gas cylinder (25) and the gas booster (26) are turned on, and the gas is filled into the metal tube (19). The internal pressure of the metal tube (19) is monitored by the pressure transmitter (3), so that the internal pressure of the metal tube (19) reaches the target value. When the metal tube (19) ruptures, the gas cylinder (25) is turned off, the gas booster (26) is turned off, the first DC power supply (27) is turned off, the second DC power supply (28) is turned off, and the metal tube (19) is cooled. When the maximum temperature of the metal tube (19) is reduced to below 400°C, the steam generator (2) is turned off, and the steam is stopped from being introduced. When the maximum temperature of the annular tungsten heating body (14) is reduced to below 100°C, the vacuum pump (1) is turned off, and when the temperature of the metal tube (19) is reduced to room temperature, the round tube assembly is taken out; The experimental method of the experiment on the oxidation of the inner surface of a circular tube after the rupture of the circular tube under internal pressure under the accident working condition of the nuclear reactor is as follows: completing the installation of the circular tube assembly, starting the vacuum pump (1), eliminating the air around the annular tungsten heating body (14), starting the second DC power supply (28), transferring heat to the metal tube (19) through the annular tungsten heating body (14), so that the maximum temperature of the metal tube (19) reaches 300°C, starting the steam generator (2), and after the furnace chamber of the steam generator (2) reaches the target pressure, introducing steam into the barrel assembly to create the required high-temperature oxidizing gas environment and realize the oxidation of the inner surface after the circular tube ruptures, opening the gas cylinder (25) and the gas booster (26), filling the metal tube (19) with gas, monitoring the internal pressure of the metal tube (19) through the pressure transmitter (3), so that the internal pressure of the metal tube (19) reaches the target value, and after the water vapor in the barrel assembly flows stably, increasing the heating power of the second DC power supply (28). , so that the metal tube (19) is heated according to the designed temperature change process. When the metal tube (19) ruptures, the gas cylinder (25) is closed, the gas booster (26) is closed, and the heating power of the second DC power supply (28) is adjusted to make the metal tube (19) continue to heat according to the designed temperature change process until the maximum temperature of the metal tube (19) reaches the target temperature. The heating power of the second DC power supply (28) is adjusted to make the maximum temperature of the metal tube (19) stabilize at the target temperature. The timing starts from the moment when the temperature of the metal tube (19) stabilizes. After the timing reaches the target time, the second DC power supply (28) is turned off to cool the metal tube (19). When the maximum temperature of the metal tube (19) drops below 400°C, the steam generator (2) is turned off and the steam is stopped. When the maximum temperature of the annular tungsten heating body (14) drops below 100°C, the vacuum pump (1) is turned off. When the temperature of the metal tube (19) drops to room temperature, the round tube assembly is taken out.

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