Plate-type fuel assembly flow-induced vibration test device

Abstract

A plate-type fuel assembly flow-induced vibration testing device comprises a circulation system and a testing system which are communicated through a flow channel, the circulation system provides coolant circulation power, the testing system comprises a testing pipeline, a testing section and a measuring device, a plate-type fuel assembly is fixedly arranged in the testing section, and the testing section is communicated with the circulation system through a vibration reduction corrugated pipe. The measuring device is used for measuring fluid parameters and vibration parameters of the fuel plate. The test device can effectively isolate the interference of the vibration flow outside the test section to the measurement result of the vibration test, and improves the test precision.

Description

Technical Field

[0001] The present invention belongs to the field of nuclear power, and particularly relates to a flow-induced vibration test device for a plate-type fuel assembly. Background Art

[0002] Plate-type fuel assemblies have been widely used in compact research reactors due to their advantages of high specific heat transfer rate, large heat transfer area, and good heat transfer performance. However, due to the thin fuel plates and small gaps used in plate-type fuel assemblies, flow-induced vibration will occur in a fast-flowing cooling medium. When the flow-induced vibration exceeds a certain limit, it may lead to problems such as stress fatigue of the fuel plates, metallurgical failure, defect propagation, or collision between fuel plates, which will have an adverse impact on the structural integrity of the fuel assembly and endanger the safety of the research reactor. Due to the small gaps between the fuel plates and the fast flow velocity between the plates in the plate-type fuel assembly, it is difficult for conventional equipment to conduct accurate simulation tests, and the measurement of the vibration behavior of the fuel plates is also easily interfered by external vibrations, affecting the test accuracy. At the same time, the end fixing structure of the plate-type fuel assembly is relatively complex, and different flow directions of the cooling medium will have different effects on the fluid behavior, which further increases the difficulty of studying the flow-induced vibration behavior of the plate-type fuel assembly. Therefore, providing a test device that can accurately measure the flow-induced vibration behavior of a plate-type fuel assembly is of positive significance for improving the safety of a research reactor. Summary of the Invention

[0003] The purpose of the present invention is to provide a flow-induced vibration test device for a plate-type fuel assembly to improve the measurement accuracy of the flow-induced vibration characteristics of the plate-type fuel assembly.

[0004] According to an embodiment of the present invention, there is provided a flow-induced vibration test device for a plate-type fuel assembly. The test device includes a circulation system and a test system, and the flow channels of the circulation system and the test system are connected. Among them,

[0005] The circulation system includes a power pump, and the power pump provides the circulation power for the coolant;

[0006] The test system includes a test pipeline, a test section, and a measuring device;

[0007] The test section is connected to the test pipeline through a vibration damping bellows. The test pipeline is connected to the circulation system, and a plate-type fuel assembly is fixedly arranged in the test section;

[0008] The measuring device measures the fluid parameters in the test section and / or the test pipeline, as well as the vibration parameters of the plate-type fuel assembly;

[0009] The circulation system and the test system are arranged on a vibration damping foundation, and a vibration isolation device is arranged between the power pump and the vibration damping foundation.

[0010] By setting the entire test device on a vibration-damping foundation, this plate-type fuel assembly flow-induced vibration test device can effectively reduce the impact of environmental vibration on test accuracy; by setting up a vibration isolation device, the vibration generated during the operation of the power pump can be shielded outside the test section; by setting up bellows, the impact of pressure fluctuations generated by the fluid circulation in the pipeline on the test detection results can be effectively isolated.

[0011] Further, in some embodiments, the test section includes a first interface and a second interface, and the first interface and the second interface are respectively connected to the test pipeline through the vibration-damping bellows;

[0012] The test pipeline includes an inlet end, an outlet end, a first pipeline group, a second pipeline group, a control valve group, a first port and a second port; the coolant is input from the inlet end and output from the outlet end; the first port is connected to the first interface through the vibration-damping bellows, and the second port is connected to the second interface through the vibration-damping bellows; the control valve group allows the test section to be connected to the first pipeline group or the second pipeline group. When the test section is connected to the first pipeline group, the coolant in the test section flows from the first interface to the second interface, and when the test section is connected to the second pipeline group, the coolant in the test section flows from the second interface to the first interface.

[0013] By setting up a pipeline with a reversible flow direction, this device can measure the flow-induced vibration characteristics of the fuel plate under different coolant flow directions without repeatedly disassembling and assembling the fuel plate to be tested, avoiding the impact of accidental errors introduced during the installation and disassembly process on the test results.

[0014] Further, in some embodiments, the control valve group includes a globe valve and a flow regulating valve, and the globe valve and the flow regulating valve are respectively arranged in the first pipeline group and the second pipeline group.

[0015] Further, in some embodiments, the globe valve is arranged upstream of the test section, and the flow regulating valve is arranged downstream of the test section.

[0016] Further, in some embodiments, the fuel plates in the plate-type fuel assembly are arranged parallel to the coolant flow direction.

[0017] Further, in some embodiments, the power pump is configured as a canned motor pump.

[0018] Further, in some embodiments, the circulation system further includes a main water tank, a pressure stabilizing tank, a heater and a cooler. Among them, the main water tank provides water as the coolant, the pressure stabilizing tank stores water and compressed gas for absorbing pressure fluctuations, and the heater and the cooler are used to adjust the water temperature in the circulation system.

[0019] Further, in some embodiments, the vibration isolation device is configured as a vibration damping pad.

[0020] Further, in some embodiments, the measuring device includes a strain gauge and an eddy current displacement sensor. The strain gauge is disposed on the surface of the fuel plate under test for measuring the strain of the fuel plate under test; the eddy current sensor is disposed opposite to the fuel plate under test for measuring the vibration displacement of the fuel plate under test.

[0021] Further, in some embodiments, the measuring device includes temperature sensors, pressure sensors and flow meters disposed in the circulation system and / or the test pipeline. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of a plate-type fuel assembly fluid-induced vibration test device in an embodiment;

[0023] Figure 2 is a schematic partial structural diagram of a test pipeline in an embodiment.

[0024] Meanings of the reference numerals: 1 - test section; 11 - first interface; 12 - second interface; 2 - test pipeline; 21 - inlet end; 22 - outlet end; 231 - upstream pipeline of the first pipeline group; 232 - downstream pipeline of the first pipeline group; 24 - first port; 25 - stop valve; 26 - flow regulating valve; 271 - upstream pipeline of the second pipeline group; 272 - downstream pipeline of the second pipeline group; 28 - second port; 30 - canned motor pump; 31 - pressure stabilizing tank; 311 - sewage pipe; 312 - safety valve; 313 - high-pressure gas cylinder; 32 - plunger pump; 33 - main water tank; 34 - heater; 35 - cooler; 36 - filter; 37 - exhaust valve; 41 - flow meter; 42 - pressure sensor; 43 - temperature sensor.

[0025] The purpose of the above-mentioned drawings is to make a detailed description of the present invention so that those skilled in the art can understand the technical concept of the present invention, rather than aiming to limit the present invention. For the sake of simplicity of expression, the above-mentioned drawings only schematically show the structures related to the technical features of the present invention and do not draw the complete structure and all details strictly according to the actual ratio. Detailed Embodiments

[0026] The present invention will be further described in detail below through specific embodiments in conjunction with the drawings.

[0027] As used herein, the term "embodiment" means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present disclosure. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive separate or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein can be combined with other embodiments without structural conflicts.

[0028] In the description herein, unless otherwise clearly defined and limited, technical terms such as "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it can be a movable connection, a fixed connection, or integrated. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0029] In the description herein, terms indicating orientation or positional relationships such as "upper", "lower", "left", "right", "lateral", "longitudinal", "height", "length", "width", etc. are used to accurately describe the embodiments and simplify the description, rather than to limit that the parts or structures involved must have a specific orientation, be installed or operated in a specific orientation, and should not be construed as a limitation to the embodiments herein.

[0030] In the description herein, terms such as "first" and "second" are only used to distinguish different objects, and should not be construed as indicating relative importance or limiting the quantity, specific order, or primary-secondary relationship of the described technical features. In the description herein, the meaning of "a plurality of" is at least two.

[0031] The plate-type fuel assembly is composed of several stacked fuel plates. Compared with the traditional rod bundle-type fuel assembly, the unique structural form of the plate-type fuel assembly enables more fuel plates to be arranged in the same core volume, thereby increasing the heat transfer area. At the same time, the plate-type fuel assembly also has advantages such as a high specific heat ratio and good heat transfer performance. Therefore, it has been widely used in compact reactors and research reactors.

[0032] The vibration of fuel elements caused by the axial (longitudinal) flow of coolant - flow-induced vibration has always been one of the important research topics in nuclear reactor engineering. The fuel plates of the plate-type fuel assembly are very thin, the adjacent flow channel gaps are small, and the flow velocity between the plates is high, so there are also relatively prominent flow-induced vibration problems. The vibration of reactor fuel elements will cause local dynamic changes in the coolant flow channels, which not only may cause mutual collisions between fuel plates, but also has a greater impact on the life of fuel elements. Flow-induced vibration may cause damages or injuries such as impact damage, baffle damage, joint leakage, stress fatigue, metallurgical failure, and material defect expansion, affecting the structural integrity of the fuel assembly and endangering the core thermal-hydraulic safety.

[0033] At present, most of the flow-induced vibration tests for fuel assemblies are experimental studies on rod bundle type fuel assemblies. There are few studies on the flow-induced vibration phenomenon of plate type fuel assemblies, and the mechanism of flow-induced vibration of plate type fuel elements is not yet clear. There are many differences between plate type fuel reactors and typical rod bundle type reactors. For example, there are cases of flow direction changes in plate type fuel reactors, while most of the existing flow-induced vibration test rigs are for rod bundle type fuel assemblies and have only one flow direction, so they cannot be directly applied to plate type fuel assemblies.

[0034] Therefore, it is necessary to establish a flow-induced vibration test rig suitable for plate type fuel assemblies, conduct flow-induced vibration tests on plate type fuel assemblies, obtain the flow-induced vibration responses and pulsating pressure states of fuel assemblies under different working conditions, provide inputs for the cladding stress analysis of fuel elements, verify the structural integrity and reliability of fuel assemblies under operating conditions, and provide support for the application of plate type fuel assemblies.

[0035] To solve the above problems, an embodiment of the present invention provides a flow-induced vibration test device for a plate type fuel assembly. The structure of the device is as Figure 1 shown, including a circulation system and a test system. The flow channels of the circulation system and the test system are connected. Among them, the test system includes a test section 1, a test pipeline 2 and a measuring device.

[0036] Combined with Figure 2 , the test section 1 is an overall closed pressure vessel, having a first interface 11 and a second interface 12. The coolant can flow in from one of the interfaces and flow out from the other interface to form a flow field in the test section 1. A plate type fuel assembly is fixedly arranged in the test section 1. The plate type fuel assembly includes single or multiple test fuel plates, and the flow-induced vibration of the test fuel plates is excited by the flow field formed in the test section 1. In a preferred embodiment, the direction of the plate type fuel assembly is set so that the fuel plates are arranged parallel to the coolant flow direction.

[0037] The test pipeline 2 has an inlet end 21 and an outlet end 22. The coolant output by the circulation system flows into the test pipeline 2 from the inlet end 21 and flows back to the pipeline of the circulation system through the outlet end 22. The test pipeline 2 has a first port 24 and a second port 28. The first port 24 is connected to the first interface 11 through a vibration damping bellows (the vibration damping bellows is not shown in the figure, and the first port 24 and the first interface 11 are marked as the same point), and the second port 28 is connected to the second interface 12 through a vibration damping bellows (the vibration damping bellows is not shown in the figure, and the second port 28 and the second interface 12 are marked as the same point). The fluid vibration generated in the circulation system and the test pipeline 2 can be isolated by the bellows, avoiding affecting the flow-induced vibration behavior of the test fuel plates and improving the test accuracy.

[0038] In a preferred embodiment, the test pipeline 2 further includes two different flow channels: a first pipeline group including an upstream pipeline 231 of the first pipeline group and a downstream pipeline 232 of the first pipeline group, and a second pipeline group including an upstream pipeline 271 of the second pipeline group and a downstream pipeline 272 of the second pipeline group. Among them, stop valves 25 are respectively arranged on the upstream pipeline 231 of the first pipeline group and the upstream pipeline 271 of the second pipeline group, and flow regulating valves 26 are respectively arranged on the downstream pipeline 232 of the first pipeline group and the downstream pipeline 272 of the second pipeline group. Among them, the two stop valves 25 are interrelated, and when one is opened, the other is closed. By controlling the stop valves 25, the test section 1 can be connected to the first pipeline group or the second pipeline group respectively.

[0039] Specifically, when the test section 1 is connected to the first pipeline group, the coolant flows into the test section 1 from the upstream pipeline 231 of the first pipeline group through the first interface 11 and flows out to the downstream pipeline 232 of the first pipeline group through the second interface 12; when the test section 1 is connected to the second pipeline group, the coolant flows into the test section 1 from the upstream pipeline 271 of the second pipeline group through the second interface 12 and flows out to the downstream pipeline 272 of the second pipeline group through the first interface 11. Thus, after the fuel plate under test is installed, the reversal of the flow field direction in the test section 1 can be realized without reinstalling and disassembling, and the flow-induced vibration behavior under different coolant flow directions can be tested, effectively avoiding accidental errors introduced by installation and disassembly and improving the test accuracy and efficiency.

[0040] In a preferred embodiment, one or more flow meters 41 are arranged in the test pipeline 2 to detect the coolant flow rate during the test. In other embodiments, temperature sensors, pressure sensors, etc. can also be arranged to monitor the temperature and pressure of the coolant.

[0041] The circulation system includes a canned motor pump 30 as a power pump. The canned motor pump 30 pumps the coolant out to the inlet end 21 of the test pipeline 2, and the returned coolant flows back to the circulation system from the outlet end 22. Upstream of the inlet end 21, a heater 34 is arranged in the pipeline of the circulation system; downstream of the outlet end 22, a cooler 35 is arranged in the pipeline of the circulation system; the heater 34 and the cooler 35 jointly regulate the temperature of the coolant in the pipeline to ensure the stability of the flow-induced vibration test temperature.

[0042] The circulation system is also provided with a main water tank 33, and the main water tank 33 stores cooling water as the coolant. A plunger pump 32 can pump the water in the main water tank 33 into the circulation pipeline of the circulation system to supplement the coolant. A filter 36 is arranged between the plunger pump 32 and the main water tank 33 to filter out impurities and pollutants in the cooling water and avoid corrosion of the test pipeline 2. An exhaust valve 37 is arranged on the main water tank 33 to keep the pressure balance between the main water tank 33 and the outside.

[0043] In a preferred embodiment, in order to absorb the pressure fluctuations in the pipeline and maintain stable pressure, the test device is further provided with a pressure stabilizing tank 31, and an exhaust valve 37 is provided in the pipeline of the circulation system. A certain amount of water and compressed gas are stored in the pressure stabilizing tank 31. The high-pressure gas cylinder 313 is connected to the pressure stabilizing tank 31 through a pressure reducing valve to maintain the air pressure and gas volume in the pressure stabilizing tank 31. A safety valve 312 is provided at the top of the pressure stabilizing tank 31. When violent pressure fluctuations occur in the pipeline of the circulation system, since the gas volume in the pressure stabilizing tank 31 can be compressed, the pressure fluctuations can be absorbed by the pressure stabilizing tank 31, thereby maintaining the stability of the system pressure. A sewage discharge pipe 311 is provided at the bottom of the pressure stabilizing tank 31 for discharging the sewage in the tank.

[0044] Furthermore, the circulation system and the test system are integrally arranged on a vibration damping foundation to further isolate environmental vibrations through the vibration damping foundation and reduce the influence of environmental factors on the flow-induced vibration behavior of the fuel plate under test. A vibration isolation device is provided between the canned motor pump 30 and the vibration damping foundation, which is configured as a vibration damping pad in a preferred embodiment to further isolate the working vibration generated by the canned motor pump 30 from the test section 1.

[0045] The measuring device in the test device is used to measure the pipeline fluid parameters and the vibration parameters of the fuel plate under test. Specifically, a flowmeter 41 is arranged in the pipeline for flow measurement, a pressure sensor 42 arranged in the pipeline of the circulation system is used for coolant pressure measurement, and a temperature sensor 43 arranged in the pipeline of the circulation system is used for coolant temperature measurement. Among them, the flowmeter can adopt an orifice flowmeter. In different embodiments, according to the different specific pipeline structures, the flowmeter 41, the pressure sensor 42, and the temperature sensor 43 can be set to one or multiple, and can be arranged in the pipeline of the circulation system or in the test pipeline 2, and can also be respectively arranged at multiple positions for multi-point measurement and monitoring.

[0046] The vibration parameters of the fuel plate under test that need to be measured mainly include the strain and vibration displacement of the fuel plate under test. Among them, the strain is measured by strain gauges arranged on the surface of the fuel plate under test, and the vibration displacement is measured by eddy current sensors arranged opposite to the surface of the fuel plate under test.

[0047] The measurement parameters in the test are all synchronously collected by a data acquisition system, and then subjected to analog-to-digital (A / D) conversion and input into a computer for real-time display, calculation, and storage. The measurement and control system uses two data acquisition devices: a fluid signal acquisition system and a dynamic signal test and analysis system.

[0048] Among them, the fluid signal acquisition system can be directly connected to the sensor, and the signal is transmitted to the working computer through Ethernet. Therefore, it is convenient for wiring, making the acquisition device closer to the acquisition signal and reducing interference. The main measurement signals of the fluid signal acquisition system are parameters such as loop temperature, pressure, and flow rate.

[0049] The dynamic signal test and analysis system uses Gigabit Ethernet communication and is extended through a switch. A single computer can achieve multi-channel dynamic signal parallel synchronous testing and analysis. The dynamic signal test and analysis system mainly measures the vibration signals at various parts of the test loop, and through data processing and analysis, obtains the response characteristics such as the amplitude and frequency of the flow-induced vibration of the fuel plate.

[0050] The specific method for conducting the flow-induced vibration test using the flow-induced vibration test device for the plate-type fuel assembly provided by the above embodiment is as follows:

[0051] First, before the test starts, check the test device to ensure that the test device can operate normally and the water supply and power supply meet the test requirements; assemble and fix the plate-type fuel assembly. After filling the entire circulation loop with water through the main water tank 33 and the plunger pump 32, cut off the water source, close the exhaust valve, and check the tightness of the flow path.

[0052] Next, start the canned motor pump 30 to make the cooling water circulate in the test device. According to the test design requirements, adjust the valve group in the test pipeline 2 so that the cooling water in the test section 1 flows in the direction required by the test design. Open the valve connecting the pressure stabilizing tank 31 and the circulation system to make the main loop reach a stable operating state.

[0053] Finally, according to the required test conditions, start the heater 34 and the cooler 35 to adjust the cooling water in the flow path to the test required conditions. Use the measuring device to measure the temperature, pressure, flow rate of the cooling water, as well as the strain and vibration displacement of the fuel plate. Calculate the flow-induced vibration data such as the amplitude and frequency of the flow-induced vibration of the tested fuel plate.

[0054] The purpose of the above embodiment is to make a further detailed description of the present invention in combination with the drawings, so that those skilled in the art can understand the technical concept of the present invention. Based on the disclosed content of the present invention, optimizing or equivalently replacing the involved part structures, and combining the implementation manners in different embodiments without conflict in structure and principle all fall within the protection scope of the present invention.

Claims

1. A plate-type fuel assembly flow-induced vibration test device, characterized in that: It includes a circulation system and a test system, wherein the flow channels of the circulation system and the test system are connected, wherein: The circulation system includes a power pump, which provides circulation power for the coolant; The test system includes a test pipeline, a test section and a measuring device; The test section is connected to the test pipeline through a vibration-damping bellows, the test pipeline is connected to the circulation system, and a plate-type fuel assembly is fixedly arranged in the test section; The measuring device measures the fluid parameters in the test section and / or the test pipeline, and the vibration parameters of the plate-type fuel assembly; The circulation system and the test system are arranged on a vibration-damping foundation, and a vibration isolation device is arranged between the power pump and the vibration-damping foundation.

2. The plate-type fuel assembly flow-induced vibration test device according to claim 1, characterized in that: The test section comprises a first interface and a second interface, and the first interface and the second interface are respectively connected to the test pipeline through the vibration-damping bellows; The test pipeline includes an inlet end, an outlet end, a first pipeline group, a second pipeline group, a control valve group, a first port and a second port; the coolant is input from the inlet end and output from the outlet end; the first port is connected to the first interface through the vibration-damping bellows, and the second port is connected to the second interface through the vibration-damping bellows; the control valve group allows the test section to be connected to the first pipeline group or the second pipeline group, and when the test section is connected to the first pipeline group, the coolant in the test section flows from the first interface to the second interface, and when the test section is connected to the second pipeline group, the coolant in the test section flows from the second interface to the first interface.

3. The plate-type fuel assembly flow-induced vibration test device according to claim 2, characterized in that: The control valve group includes a stop valve and a flow regulating valve, and the first pipeline group and the second pipeline group are respectively provided with the stop valve and the flow regulating valve.

4. The plate-type fuel assembly flow-induced vibration test device according to claim 3, characterized in that: The stop valve is arranged upstream of the test section, and the flow regulating valve is arranged downstream of the test section.

5. The plate-type fuel assembly flow-induced vibration test device according to any one of claims 1 to 4, characterized in that: The fuel plates in the plate-type fuel assembly are arranged parallel to the coolant flow direction.

6. The plate-type fuel assembly flow-induced vibration test device according to any one of claims 1 to 4, characterized in that: The power pump is configured as a shielded pump.

7. The plate-type fuel assembly flow-induced vibration test device according to any one of claims 1 to 4, characterized in that: The circulation system further includes a main water tank, a surge tank, a heater and a cooler, wherein the main water tank provides water as a coolant, the surge tank stores water and compressed gas for absorbing pressure fluctuations, and the heater and the cooler are used to adjust the water temperature in the circulation system.

8. The plate-type fuel assembly flow-induced vibration test device according to any one of claims 1 to 4, characterized in that: The vibration isolation device is configured as a vibration-damping pad.

9. The plate-type fuel assembly flow-induced vibration test device according to claim 1, characterized in that: The measuring device includes a strain gauge and an eddy current displacement sensor. The strain gauge is arranged on the surface of the tested fuel plate and is used to measure the strain of the tested fuel plate; the eddy current sensor is arranged opposite to the tested fuel plate and is used to measure the vibration displacement of the tested fuel plate.

10. The plate-type fuel assembly flow-induced vibration test device according to claim 1 or 9, characterized in that: The measuring device comprises a temperature sensor, a pressure sensor and a flow meter which are arranged in the circulation system and / or the test pipeline.

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