An experimental device and method for simulating the working conditions of a pressurized water reactor

Abstract

The application relates to a test device and method for simulating the working condition of a pressurized water reactor, belonging to the nuclear power field. The test device for simulating the working condition of the pressurized water reactor comprises a pressure vessel and simulated fuel rods, wherein the pressure vessel comprises nested outer and inner flow channels; the outer and inner flow channels are respectively provided with water inlets and outlets at the first end of the pressure vessel; the outer and inner flow channels are communicated through a reflux section arranged at the second end of the pressure vessel; the inner flow channel is provided with fuel rod interfaces at both ends to allow the simulated fuel rods to pass through; and an insulating sealing device is arranged between the simulated fuel rods and the fuel rod interfaces. The device is simple and reliable in structure, can effectively improve the temperature stability in the pressurized water reactor simulation test process, and improves the test efficiency and accuracy.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power, specifically relating to a test apparatus and method for simulating pressurized water reactor operating conditions. Background Technology

[0002] Research on pressurized water reactors (PWRs) involves conducting a series of experiments under simulated high-temperature and high-pressure conditions to verify and analyze the strength, thermo-hydraulic performance, and other characteristics of the fuel rods. Considering safety and economy, electric heating rods are typically used instead of actual fuel rods in these experiments. However, prolonged exposure of electric heating rods to high temperature and pressure can easily induce leakage risks and galvanic corrosion. Furthermore, poor insulation of the test vessel can lead to uneven heating rod temperatures, affecting the safety and accuracy of the experiments. Therefore, providing a test apparatus that can offer a more stable experimental simulation environment is of positive significance for improving the safety and accuracy of high-temperature and high-pressure simulation experiments. Summary of the Invention

[0003] The purpose of this invention is to provide a test apparatus for simulating pressurized water reactor operating conditions, thereby improving the safety and accuracy of the simulation test. This invention also provides a test method for simulating pressurized water reactor operating conditions.

[0004] According to one aspect of the present invention, a test apparatus for simulating pressurized water reactor operating conditions is provided. The apparatus includes a pressure vessel and simulated fuel rods, wherein:

[0005] The pressure vessel has a cavity formed inside, and the pressure vessel includes an inlet and an outlet to allow the simulated working fluid to flow into the cavity from the inlet and out from the outlet.

[0006] The cavity includes an outer flow channel, an inner flow channel, and a reflux section. The outer flow channel surrounds the outer side of the inner flow channel and is connected to the inner flow channel through the reflux section. The outer flow channel is connected to the inlet, and the inner flow channel is connected to the outlet. The inlet and outlet are located at the first end of the pressure vessel, and the reflux section is located at the second end of the pressure vessel.

[0007] Fuel rod interfaces are provided at both ends of the inner flow channel to allow the simulated fuel rod to pass through the inner flow channel, and an insulating sealing device is provided between the simulated fuel rod and the wall of the fuel rod interface.

[0008] Pressure vessels with a jacket can effectively reduce the impact of heat exchange on the pressure vessel surface on the temperature of the simulated fuel rods, thus improving the stability of test conditions. At the same time, since the simulated fuel rods are only partially installed inside the pressure vessel, the cables and other structures do not need to withstand high temperature and high pressure test conditions for a long time, which can effectively improve the service life and reliability of the simulated fuel rods.

[0009] Furthermore, in some embodiments, the outer flow channel and the inner flow channel are separated by a sandwich wall, and an insulated air chamber is provided in the sandwich wall.

[0010] Insulated air chambers can reduce heat exchange between the outer and inner flow channels, further improving temperature stability.

[0011] Furthermore, in some embodiments, the insulated chamber is filled with helium.

[0012] Adjusting the helium pressure according to the experimental conditions can further improve the structural stability.

[0013] Furthermore, in some embodiments, the surface of the pressure vessel is also provided with a heating device to compensate for heat loss from the surface of the pressure vessel.

[0014] Furthermore, in some embodiments, the insulating sealing device includes a pressure-bearing nut and a sealing ring. The pressure-bearing nut is configured as a ring and is threadedly connected to the pressure vessel, through which the simulated fuel rod passes. The sealing ring is disposed between the simulated fuel rod and the pressure-bearing nut, separating the simulated fuel rod from the pressure-bearing nut.

[0015] Furthermore, in some embodiments, the sealing ring is made of polybenzimidazole.

[0016] Furthermore, in some embodiments, the fuel rod interface is configured as a flared structure.

[0017] Furthermore, in some embodiments, the fuel rod interface protrudes along the axial direction of the pressure vessel, and the outlet is disposed on the sidewall of the fuel rod interface on one side of the first end.

[0018] Furthermore, in some embodiments, the outer flow channel is configured as an integral annular chamber or a spiral pipe surrounding the inner flow channel.

[0019] According to another aspect of the present invention, a test method for simulating pressurized water reactor operating conditions is provided, the method employing the test apparatus for simulating pressurized water reactor operating conditions provided in any of the foregoing embodiments.

[0020] Furthermore, in some embodiments, the test temperature is 300℃-400℃ and the pressure is 10MPa-15.5MPa. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the test apparatus for simulating pressurized water reactor operation in one embodiment.

[0022] Meaning of the reference numerals in the attached figures:

[0023] 1-Pressure vessel; 11-Outer flow channel; 12-Inner flow channel; 13-Cladder wall; 14-Inlet; 15-Outlet; 16-Fuel rod interface; 17-Heater; 18-Gas chamber; 19-Recirculation section; 2-Simulated fuel rod; 21-Pressure bearing nut; 22-Sealing ring.

[0024] The purpose of the above-described drawings is to provide a detailed description of the present invention so that those skilled in the art can understand the technical concept of the invention, and is not intended to limit the invention. For the sake of brevity, the above-described drawings only schematically depict the structures related to the technical features of the present invention, and do not depict the complete structure and all details strictly according to actual scale. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0026] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment herein. The phrase appearing in various places in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive, independent, or alternative embodiments. Those skilled in the art will understand that the embodiments herein can be combined with other embodiments without causing structural conflicts.

[0027] In this description, unless otherwise explicitly specified and limited, the technical terms "installation," "connection," "joining," etc., should be interpreted broadly, for example, referring to movable connections, fixed connections, or integration. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0028] In this description, terms such as "upper," "lower," "left," "right," "lateral," "longitudinal," "height," "length," and "width," which indicate orientation or positional relationships, are intended to accurately describe the embodiments and simplify the description, rather than limiting the parts or structures involved to have a specific orientation, or to be installed or operated in a specific orientation, and should not be construed as limiting the embodiments in this document.

[0029] In this description, terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating relative importance or limiting the number, specific order, or primary / secondary relationship of the described technical features. In this description, "multiple" means at least two.

[0030] During the reactor design phase, simulation devices are needed to conduct various tests simulating real-world high-temperature and high-pressure conditions. These tests simulate the structure, heat transfer properties, and thermal-hydraulic state of the fuel rods under preset operating conditions, providing data support for reactor safety and reliability analysis. Simulation tests typically use electrically heated rods to simulate the heating state of fuel rods under real-world conditions. For example, patent CN109243641A discloses a reactor pressure vessel test simulator, and CN114023471A discloses a pressurized water reactor simulation test bench. However, these test devices are too large and complex, making them unsuitable for small-scale tests on individual simulated fuel rods. Furthermore, if electrically heated simulated fuel rods are subjected to prolonged high-temperature and high-pressure working fluid erosion, there is a risk of electrical leakage. Additionally, the contact between the simulated fuel rods and the pressure vessel shell can easily lead to galvanic corrosion. However, if a small pressure vessel design is used, the test conditions are easily affected by the external environment, and the pressure vessel is prone to heat loss from its surface, resulting in unstable simulated fuel rod test temperatures.

[0031] To address the above problems, one embodiment of the present invention provides a test apparatus for simulating pressurized water reactor operating conditions, the structure of which is as follows: Figure 1 As shown. The test apparatus includes a pressure vessel 1 and a simulated fuel rod 2 inserted inside the pressure vessel 1. An electric heater is installed inside the simulated fuel rod 2, which is powered by an external power source to generate heat to simulate fuel rods under real operating conditions.

[0032] Pressure vessel 1 has a cavity, which includes an outer flow channel 11 and an inner flow channel 12. The outer flow channel 11 surrounds the radially outer side of the inner flow channel 12, and the outer flow channel 11 and the inner flow channel 12 are connected by a reflux section 19 located at the bottom of pressure vessel 1. The top of pressure vessel 1 is provided with an inlet 14 and an outlet 15. The inlet 14 is connected to the outer flow channel 11, and the outlet 15 is connected to the inner flow channel 12. The test working medium flows in from the inlet 14 in the direction shown by arrow A, flows back through the reflux section 19 and enters the inner flow channel 12, and flows out from the outlet 15, completing the circulation.

[0033] Fuel rod interfaces 16 are provided at both ends of the inner flow channel 12. The simulated fuel rod 2 passes through the fuel rod interfaces 16 and comes into contact with the test working medium. An insulating sealing device is provided between the simulated fuel rod 2 and the wall of the fuel rod interface 16 to prevent leakage of the test working medium under high temperature and high pressure, and at the same time to avoid direct contact between the simulated fuel rod 2 and the wall of the pressure vessel 1 to induce galvanic corrosion.

[0034] In a preferred embodiment, the fuel rod interface 16 protrudes outward along the axial direction of the pressure vessel 1, wherein the outlet 15 is disposed on the side wall of the fuel rod interface 16 at the top of the pressure vessel 1.

[0035] Since the inner flow channel 12 is surrounded by the outer flow channel 11, the inner flow channel 12 can avoid direct heat exchange with the external environment, thereby improving the uniformity and stability of the axial temperature of the simulated fuel rod 2.

[0036] In a preferred embodiment, the wall separating the outer flow channel 11 and the inner flow channel 12 is configured as a sandwich wall 13, which extends axially along the pressure vessel 1 and has an annular gas cavity 18 inside. The sandwich wall 13 can further reduce heat exchange between the inner flow channel 12 and the outer flow channel 11, and further improve the temperature stability within the inner flow channel 12. In a preferred embodiment, the gas cavity 18 is filled with high-pressure helium gas, and the pressure of the helium gas is adapted to the test conditions to further improve the structural stability of the sandwich wall 13.

[0037] A heater 17 is provided on the surface of the pressure vessel 1. The heater 17 is configured as an electric heating wire wound on the surface of the pressure vessel 1. The heater 17 is used to compensate for the heat loss of the test working fluid during the flow through the outer flow channel 11, so as to further improve the stability of the test temperature.

[0038] The insulating sealing device includes a pressure-bearing nut 21 and a sealing ring 22. The pressure-bearing nut 21 is annular with external threads on its outer periphery, and is fixedly connected to the fuel rod interface 16 via these threads. The sealing ring 22 is fitted onto the simulated fuel rod 2, separating it from the pressure-bearing nut 21 and forming a seal, preventing direct contact between the pressure-bearing nut 21 and the simulated fuel rod 2 to prevent leakage and galvanic corrosion. Specifically, the sealing ring 22 is made of polybenzimidazole, which has good resistance to high temperature and high pressure.

[0039] In a preferred embodiment, the inner diameter of the sealing ring 22 is set to 9.5 mm to match the support of a conventional fuel rod; the inner diameter of the pressure nut 21 is 10 mm, so that the sealing ring 22 can be stably engaged between the pressure nut 21 and the simulated fuel rod 2.

[0040] In a preferred embodiment, the fuel rod interface 16 is configured as a flared shape with a gradually widening opening, which facilitates the limiting of the sealing ring 22.

[0041] In different embodiments, the outer flow channel 11 can adopt different geometric structures depending on the test conditions and design requirements. In some embodiments, the outer flow channel 11 can be configured as an integral annular chamber, fitted around the inner flow channel 12 in a structure similar to a water jacket. In other embodiments, the outer flow channel 11 can also be configured as a spiral pipe surrounding the inner flow channel 12 to ensure sufficient flow of the test working medium in the outer flow channel 11 and avoid dead zones.

[0042] According to another aspect of the present invention, a test method for simulating pressurized water reactor operating conditions is provided, the method employing the test apparatus for simulating pressurized water reactor operating conditions provided in any of the foregoing embodiments.

[0043] Specifically, the method includes the following steps:

[0044] First, assemble the test apparatus. Place the sealing ring 22 onto the simulated fuel rod 2, where the outer diameter of the simulated fuel rod 2 is 9.5 mm and the inner diameter of the sealing ring 22 is 9.5 mm. The sealing ring 22 is made of PBI (polybenzimidazole). Insert the simulated fuel rod 2 into the fuel rod interface 16. Then, simultaneously screw the pressure nut 21 onto the simulated fuel rod 2 and into the fuel rod interface 16, compressing the sealing ring 22 so that it fills the gap between the pressure nut 21 and the simulated fuel rod 2. Perform a leak test on the test apparatus to confirm there are no leaks.

[0045] Next, cooling water is introduced into the pressure vessel, causing the simulated cooling water to flow from the inlet 14 into the outer flow channel 11 in the direction shown by arrow A, then back into the inner flow channel 12 via the return section 19, and finally out through the outlet 15. The device is then checked for leaks. Pressurized helium is then introduced into the air chamber 18 of the sandwich wall 13 to balance the pressure.

[0046] Start the heater and use the external heating device and booster pump to heat and pressurize the cooling water until the temperature and pressure of the cooling water reach the test design requirements. Then start the heating device in the simulated fuel rod 2. Detect the temperature, pressure and water chemistry conditions in the inner flow channel 12. After reaching 400℃ and 15.5MPa, carry out the simulation test.

[0047] During the test, because the inner flow channel 12 is surrounded by the outer flow channel 11, and the sandwich wall 13 provides thermal insulation, the heat loss of the inner flow channel 12 is negligible, and the test temperature can be kept stable. The heater 17 provides temperature compensation for the cooling water in the outer flow channel from outside the pressure vessel, preventing the cooling water flowing into the inner flow channel 12 from being too cold. During the test, the insulating sealing ring 22 separates the simulated fuel rod 2 and the pressure-bearing nut 21, preventing the risk of leakage and avoiding chemical corrosion caused by the potential difference between the simulated fuel rod 2 and the pressure-bearing nut 21, effectively improving the reliability and service life of the test device. After the test has progressed to a certain stage, the simulated fuel rod 2 can be quickly replaced by removing the pressure-bearing nut 21 after depressurization and cooling, without the need for complex processing such as cutting and welding, effectively improving the test efficiency.

[0048] The purpose of the above embodiments is to provide a more detailed description of the present invention in conjunction with the accompanying drawings, so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, optimization or equivalent substitution of the involved part structures and method steps, as well as combination of implementation methods in different embodiments without causing structural and principle conflicts, all fall within the protection scope of the present invention.

Claims

1. A test apparatus for simulating pressurized water reactor operating conditions, characterized in that, Includes a pressure vessel and simulated fuel rods, wherein: The pressure vessel has a cavity formed inside, and the pressure vessel includes an inlet and an outlet to allow the simulated working fluid to flow into the cavity from the inlet and out from the outlet. The cavity includes an outer flow channel, an inner flow channel, and a reflux section. The outer flow channel surrounds the outer side of the inner flow channel and is connected to the inner flow channel through the reflux section. The outer flow channel is connected to the inlet, and the inner flow channel is connected to the outlet. The inlet and outlet are located at the first end of the pressure vessel, and the reflux section is located at the second end of the pressure vessel. Fuel rod interfaces are provided at both ends of the inner flow channel to allow the simulated fuel rod to pass through the inner flow channel. The fuel rod interfaces protrude along the axial direction of the pressure vessel. The outlet is located on the side wall of the fuel rod interface on one side of the first end. An insulating sealing device is provided between the simulated fuel rod and the wall of the fuel rod interface. The insulating sealing device includes a pressure-bearing nut and a sealing ring. The pressure-bearing nut is configured as an annular shape and is threadedly connected to the pressure vessel. The simulated fuel rod passes through the pressure-bearing nut. The sealing ring is located between the simulated fuel rod and the pressure-bearing nut to isolate the simulated fuel rod from the pressure-bearing nut.

2. The test apparatus for simulating pressurized water reactor operating conditions according to claim 1, characterized in that, The outer flow channel and the inner flow channel are separated by a sandwich wall, and an insulated air chamber is provided in the sandwich wall.

3. The test apparatus for simulating pressurized water reactor operating conditions according to claim 2, characterized in that, The insulated chamber is filled with helium.

4. The test apparatus for simulating pressurized water reactor operating conditions according to claim 1, characterized in that, The pressure vessel surface is also equipped with a heating device to compensate for heat loss from the pressure vessel surface.

5. The test apparatus for simulating pressurized water reactor operating conditions according to claim 1, characterized in that, The sealing ring is made of polybenzimidazole.

6. The test apparatus for simulating pressurized water reactor operating conditions according to claim 1 or 5, characterized in that, The fuel rod interface is configured with a flared shape.

7. The test apparatus for simulating pressurized water reactor operating conditions according to claim 1, characterized in that, The outer flow channel is configured as an integral annular chamber or a spiral pipe surrounding the inner flow channel.

8. A test method simulating pressurized water reactor operating conditions, characterized in that, The test apparatus used is the same as any one of claims 1 to 7 for simulating pressurized water reactor conditions.

9. The test method for simulating pressurized water reactor operating conditions according to claim 8, characterized in that, The test temperature was 300℃-400℃, and the pressure was 10MPa-15.5MPa.

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