Round tube fracture experimental device and method under internal pressure effect in nuclear reactor accident

Abstract

The invention discloses a device and a method for testing round tube fracture under the action of internal pressure in a nuclear reactor accident. The device comprises a round tube assembly, a barrel assembly, a gas cylinder, a gas supercharger, a direct-current power supply, a steam generator and a vacuum pump, the round pipe assembly comprises a metal pipe, a core block, a cooling flange, a copper electrode, a ferrule type reducer union, a pressure guide pipe, a pressurizing pipe and a pressure transmitter, the metal pipe is heated through a direct-current power supply, and the metal pipe is pressurized through a gas cylinder and a gas supercharger; the barrel assembly comprises a stainless steel shell, an annular heat shielding layer, an annular tungsten heating body, an annular platinum lining, a cylindrical heat insulation pad and a cover plate, the annular tungsten heating body is heated through a direct-current power source, and the annular tungsten heating body is prevented from being oxidized by air through a vacuum pump; the steam generator is used for providing water vapor required by an experiment; the device can be used for carrying out a transient heating fracture experiment, an isothermal creep fracture experiment and a round pipe inner surface oxidation experiment after fracture of the round pipe under the action of internal pressure. The invention further provides an experiment method.

Description

Technical Field

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

[0002] Under the accident conditions of a nuclear reactor, due to the loss of cooling of the core, the core temperature rises rapidly under the action of decay heat, and the cooling water in the core is heated to become water vapor. Therefore, during a nuclear reactor accident, the core structural parts are exposed to a high-temperature water vapor environment. As the temperature rises, the mechanical properties of the core structural parts deteriorate, making them more susceptible to deformation and structural damage, affecting the reliability of the core structure. For tubular structural parts that withstand internal pressure (such as fuel element cladding), this process causes the structural parts to expand, and when the stress they withstand reaches the limit, they will rupture, thereby losing their containment function. Therefore, studying the rupture behavior of pipes that withstand internal pressure under nuclear reactor accident conditions is of great significance to the safety design and reliability analysis of nuclear reactors.

[0003] At present, the experimental study of the rupture behavior of pipes under internal pressure under nuclear reactor accident conditions widely uses a tubular furnace as a heating instrument. The tubular furnace uses a ceramic tube to surround the pipe under study. Through the radiation heat exchange of the internal heating element, the ceramic tube is first heated, and then the pipe under study is heated, so that the pipe has a uniform temperature field. However, when the pipe breaks, the impact of the release of high-pressure gas or the ejection of the filler fragments inside the pipe can easily cause the ceramic tube to break or even damage the internal components of the tubular furnace. In addition, due to the limitations of the materials of the heating elements and ceramic tubes, the heating rate of the tubular furnace is usually limited to ensure long-term use. For example, the heating rate of the tubular furnace using MoSi2 as the heating element is usually no more than 10℃ / min, which cannot meet the experimental requirements under rapid temperature rise. In addition, due to the long heat transfer path, the use of a tubular furnace to heat the pipe under study is usually accompanied by a certain delay. There is a time difference between the temperature response of the pipe under study and the power change of the tubular furnace, which brings inconvenience to the experimental research. 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 experiments, isothermal creep rupture experiments, and oxidation experiments on the inner surface of circular tubes after rupture of circular tubes subjected to internal pressure under nuclear reactor accident conditions.

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

[0006] A round tube rupture experimental device under the action of internal pressure in a nuclear reactor accident comprises a round 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 charging tube 20 through the lower ferrule reducer 21, the pressure charging 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 by the 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 surfaces 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 pipe 19 and serve as a water vapor passage; above the upper thermal insulation pad 10 is the upper cover plate 9, which 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 surfaces 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 thermal insulation pad 16 is the lower cover plate 17, which has two through holes, which are respectively used to install the metal pipe 19 and weld the joint of 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, which is a high-temperature refractory heat-insulating material.

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

[0012] The circular tube rupture test device under the action of internal pressure in a nuclear reactor accident can carry out transient temperature rise 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 under nuclear reactor accident conditions.

[0013] The experimental method of the transient temperature rise rupture experiment of the circular tube under internal pressure under the accident condition of the nuclear reactor 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, 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, and make the internal pressure of the metal tube 19 When 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. 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 heater 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.

[0014] The experimental method of the isothermal creep rupture experiment of the circular tube under internal pressure under the accident condition of the nuclear reactor 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 barrel assembly, after the water vapor in the barrel assembly flows stably, respectively increase the heating power of the first DC power supply 27 and the second DC power supply 28, 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 stabilizes the maximum temperature of the metal tube 19 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, and 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, and when the temperature of the metal tube 19 drops to room temperature, the round tube assembly is taken out.

[0015] The experimental method of the experiment on the oxidation of the inner surface of a circular tube after the rupture of a circular tube subjected to internal pressure under the accident condition of a nuclear reactor is as follows: the installation of the circular tube assembly is completed, the vacuum pump 1 is started, the air around the annular tungsten heating body 14 is eliminated, the second DC power supply 28 is started, heat is transferred 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, the steam generator 2 is started, and after the furnace chamber of the steam generator 2 reaches the target pressure, steam is introduced 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, the gas cylinder 25 and the gas booster 26 are opened, 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, and after the water vapor in the barrel assembly flows stably, the heating of the second DC power supply 28 is increased. The 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. The timing starts from the moment when the temperature of the metal tube 19 stabilizes. After the timing reaches the target duration, 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, step power, and user-defined temperature curve can be achieved by adjusting the power of the DC power supply to meet the needs of various experimental types and experimental conditions;

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

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

[0020] 4. By filling the metal tube with pellets, the effect of the gas volume in 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 the rupture of a circular tube under the action of 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 round tube rupture test device under internal pressure in a nuclear reactor accident. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with 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 pipe 5, a pressure charging pipe 20, and a pressure transmitter 3. Figure 2As shown, the inside of the metal tube 19 can be filled with a cylindrical pellet 30, and there is a gap between the pellet 30 and the metal tube 19. The two end faces of the pellet 30 are processed with chamfers to facilitate filling into the metal tube 19. The volume of gas in the metal tube 19 can be controlled by the number of pellets 30. The metal tube 19 is connected to the pressure-inducing pipe 5 through the upper ferrule-type reducer 4, and the other end of the pressure-inducing pipe 5 is connected to the pressure transmitter 3, which is used to measure the internal pressure of the metal tube 19. The metal tube 19 is connected to the pressure-charging pipe 20 through the lower ferrule-type reducer 21, and 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 gas cylinder 25 can provide inert gas. The gas provided by the gas cylinder 25 reaches the pressure required for the experiment after passing through the gas booster 26, and then is filled into the metal tube 19. 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 to form a current loop. The wire material 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 starting the first DC power supply 27, current is generated to pass 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 barrel assembly, and installs a lower cooling flange 23 between the lower copper electrode 22 and the lower cover plate 17 of the barrel assembly, thereby reducing the temperature at both ends of the metal tube 19.

[0026] The barrel assembly as described above 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. Metal platinum has excellent antioxidant properties and can prevent the annular tungsten heating body 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 heating body 14. The annular heat shielding layer 13 is made of high-temperature refractory insulation material zirconium dioxide fiber, which has a high thermal resistance and can reduce the outer surface temperature of the barrel assembly to ensure the safety of the experimenter. 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. 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 heating body 14 from being oxidized by air. 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 through a copper wire to form a current loop. After the second DC power supply 28 is started, a current is generated through the annular tungsten heating body 14, causing the annular tungsten heating body 14 to generate heat. The function of the annular tungsten heating body 14 is to prevent the condensation of water vapor during the experiment. At the same time, the annular tungsten heating body 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. 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. There are two through holes on the upper thermal insulation pad 10, which are used to install the metal tube 19 and as a water vapor channel respectively. Above the upper insulation pad 10 is the upper cover plate 9 of the cylinder assembly, and there are two through holes on the upper cover plate 9, which are respectively used to install the metal pipe 19 and the joint for welding the water vapor outlet 8. The upper insulation pad 10 can prevent the temperature of the upper cover plate 9 from being too high, and ensure the safety of the experimenters. Through the compression fit of the upper cover plate 9, the upper end surface of the annular tungsten heating body 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 pipe 19. It can work stably for a long time in a high temperature environment, maintain stable physical properties, will not age, deform or fail, and can withstand greater pressure in a high pressure environment without leakage, ensuring the sealing and working safety of the system. The cylindrical lower insulation pad 16 is placed on the lower end surface of the annular tungsten heating body 14 and the annular platinum bushing 15. There are two through holes on the lower insulation pad 16, which are respectively used to install the metal pipe 19 and as a water vapor channel. Below the lower heat insulation 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 heat 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 body 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 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 the action of internal pressure in a nuclear reactor accident can carry out transient temperature rise 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 under nuclear reactor accident conditions.

[0028] The experimental method of the transient temperature rise rupture experiment of the circular tube under internal pressure under the accident condition of the nuclear reactor 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, 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, and make the internal pressure of the metal tube 19 When 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. 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 heater 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.

[0029] The experimental method of the isothermal creep rupture experiment of the circular tube under internal pressure under the accident condition of the nuclear reactor 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, after the water vapor in the cylinder assembly flows stably, respectively increase the heating power of the first DC power supply 27 and the second DC power supply 28, make the maximum temperature of the metal tube 19 and the annular tungsten heating body 14 rise at a rate of 3-4°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 3-4°C / s. 28 of 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 is stopped, the steam generator 2 is turned off, the steam is stopped, and 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 and the round tube assembly is taken out.

[0030] The experimental method of the experiment of oxidation of the inner surface of a circular tube after the rupture of a circular tube under internal pressure under the accident condition of a nuclear reactor 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 second DC power supply 28, and 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. Since the metal tube 19 will produce a large loss due to the oxidation reaction in this experiment, the first DC power supply 27 is not used to heat the metal tube 19 to avoid the difficulty in adjusting the heating power due to the change of resistance. Start the steam generator 2. 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 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. Monitor the internal pressure of the metal tube 19 through the pressure transmitter 3 to make the internal pressure of the metal tube 19 reach the target value. After the water vapor in the barrel assembly flows stably, increase the heating power of the second DC power supply 28 to make the metal tube 19 heat up with the designed temperature change process. When the metal tube 19 ruptures, turn off the gas cylinder 25 and the gas booster 26, and 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 with 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 when the temperature of the metal tube 19 is stable, and after the timing reaches the target duration, turn off the second DC power supply 28 to cool the metal tube 19, wait for the maximum temperature of the metal tube 19 to drop below 400°C, 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°C, 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 round tube rupture under internal pressure in 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 direct current power supply (27), a second direct current 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 lead 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 metal tube (19) through 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 ferrule 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 by 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 a vacuum pump (1) through the pipe joint (11); the upper tungsten of the annular tungsten heating body (14) is The electrode (29) and the lower tungsten electrode (24) are connected to a second DC power supply (28); a 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; an upper cover plate (9) is located above the upper thermal insulation pad (10), 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); a 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), and 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); the steam generator (2) is connected to the joint of the water vapor inlet (18).

2. The device 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 housing (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 housing (12), and between the lower cover plate (17) and the metal tube (19).

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

5. The experimental method of the circular tube rupture experimental device under the action of 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 test, isothermal creep rupture test and oxidation test of the inner surface of the circular tube after rupture for circular tubes under internal pressure under nuclear reactor accident conditions. The experimental method of the transient temperature rise rupture experiment of a circular tube under internal pressure under the working condition of a nuclear reactor accident is as follows: the installation of the circular tube assembly is completed, the vacuum pump (1) is started, the air around the annular tungsten heating body (14) is eliminated, the first direct current power supply (27) and the second direct current power supply (28) are started, the maximum temperature of the annular tungsten heating body (14) and the metal tube (19) are both made to reach 300°C, the steam generator (2) is started, and after the furnace chamber of the steam generator (2) reaches the target pressure, steam is introduced into the cylinder assembly, the gas cylinder (25) and the gas booster (26) are turned on, the gas is filled into the metal tube (19), the internal pressure of the metal tube (19) is monitored by the pressure transmitter (3), and the internal pressure of the metal tube (19) is made to reach When the water vapor in the cylinder assembly reaches the target value, the heating power of the first DC power supply (27) is increased to increase the temperature of 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). 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: 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), making the maximum temperature of the annular tungsten heating body (14) and the metal tube (19) both 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) both rise at a rate of 3-4°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). 7) and the heating power of the second DC power supply (28) to stabilize the maximum temperature of the metal tube (19) at the target temperature, 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), and make the internal pressure of the metal tube (19) reach the target value. When the metal tube (19) ruptures, close the gas cylinder (25), close the gas booster (26), close the first DC power supply (27), close the second DC power supply (28), and cool the metal tube (19). When the maximum temperature of the metal tube (19) drops below 400° C., close the steam generator (2), stop introducing steam, and when the maximum temperature of the annular tungsten heating body (14) drops below 100° C., close the vacuum pump (1), and when the temperature of the metal tube (19) drops to room temperature, take out the round tube assembly; The experimental method of the experiment on the oxidation of the inner surface of a circular tube after the rupture of a circular tube under internal pressure under the accident condition of a nuclear reactor 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 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 to achieve oxidation of the inner surface after the circular tube ruptures, starting 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). , the metal tube (19) is heated up 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, the heating power of the second DC power supply (28) is adjusted, and 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. The heating power of the second DC power supply (28) is adjusted so that the maximum temperature of the metal tube (19) is stabilized at the target temperature. The timing starts from the moment when the temperature of the metal tube (19) is stabilized. After the timing reaches the target time, the second DC power supply (28) is closed to cool the metal tube (19). When the maximum temperature of the metal tube (19) drops below 400° C., the steam generator (2) is closed, and the steam is stopped from being introduced. 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.

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