A full-scale fuel assembly dynamic characteristic test device and method in flowing water

Abstract

The present invention provides a full-scale fuel assembly dynamic characteristic test device and method in flowing water, which relates to the technical field of nuclear test equipment and solves the technical problem that the existing test device cannot obtain the dynamic characteristics of the fuel assembly under flowing water conditions. The full-scale fuel assembly dynamic characteristic test device in flowing water includes a vibration platform, a device body, a flowing water circulation loop and a measuring mechanism. The device body sequentially includes a water inlet section, a test section and a water return section from bottom to top. The test section includes a core bottom plate, an integral sleeve and a core top plate. The core bottom plate is fixed on the water inlet section, the integral sleeve is connected between the core bottom plate and the core top plate, and the water return section is arranged above the core top plate. The water inlet section and the water return section are respectively communicated with the flowing water circulation loop, and the flowing water circulation loop is used to provide axial water flow to the device body. The present invention is used to provide a full-scale fuel assembly dynamic characteristic test device and method that can be tested under flowing water conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear test equipment, and in particular to a dynamic characteristic test device and method for a full-scale fuel assembly in flowing water. Background Art

[0002] Under the action of an earthquake, the safety of nuclear power plants is an important issue concerned by the nuclear industry and even the whole society. The fuel assembly is a key component of the reactor core of a nuclear power plant, and its seismic safety is particularly important. By using physical test methods to simulate the actual core conditions and obtain the dynamic characteristic parameters of the fuel assembly, it can provide an important reference basis for the reasonable determination of the parameters of the seismic response analysis model of the fuel assembly in the core and the evaluation of the seismic safety margin of the fuel assembly.

[0003] At present, pressurized water reactors (PWRs) are the most widely used and largest-capacity reactor types in nuclear power plants. Pressurized water reactors generally use low-enriched UO2 ceramic fuel, with light water as the neutron moderator and coolant. The high-temperature, high-pressure, and high-flow-rate water body transports the fission energy of nuclear fuel to the steam generator to generate steam, driving the steam turbine to rotate for power generation or serving as a power device to generate driving force. Taking the core structure of a typical pressurized water reactor (PWR) as an example, 177 fuel assemblies are closely arranged with an average gap of about 2 mm. Each fuel assembly consists of a fuel skeleton and 264 fuel rods arranged in a 17×17 square pattern. The fuel skeleton is mainly welded by 24 guide tubes, 1 instrument tube, and 11 grids (8 positioning grids and 3 interspace mixing grids). The 24 guide tubes are fixedly connected to the upper and lower tube seats. The fuel assembly positioning grids clamp the fuel rods to maintain the lateral gap between them and the axial gap with the upper and lower tube seats. The guide tubes are used to accommodate the insertion of control rods and core-related component rods. The instrument tube is located at the center of the assembly and is used to accommodate the insertion of core measurement instruments. In the reactor core, axial water flow (flow velocity of about 5 m / s, pressure of about 15 MPa, Reynolds number Re of about 5×10 5 ) circulates through the fuel assemblies in the primary coolant loop, transferring the heat generated inside the fuel rods and cooling the core fuel assemblies. During an earthquake, it is necessary to ensure the insertability of the control rods in the fuel assemblies to ensure the safe shutdown of the reactor; at the same time, it is also necessary to ensure the geometric shape of the fuel assemblies that can be cooled and have sufficient coolant channels to discharge the waste heat.

[0004] In order to study the seismic safety of fuel assemblies, it is necessary to analyze the collision and impact effects between these closely arranged fuel assemblies and between the fuel assemblies and the core barrel, and evaluate the bending and deformation of the fuel assemblies; at the same time, complex interactions will occur between the high-temperature, high-pressure, and high-flow-rate axial water flow and the fuel assemblies, affecting the dynamic characteristics and seismic response of the fuel assemblies.

[0005] At present, the dynamic characteristics and seismic response analysis and tests of full-scale fuel assemblies are mostly carried out under normal temperature, normal pressure, static water or air conditions. Engineers and designers have not fully understood the coupling mechanism between the high-speed axial water flow and the fuel assembly structure under seismic action. In order to effectively design and maintain the reactor core and ensure that the control rods of a pressurized water reactor (PWR) can freely drop to cool the core during an earthquake, it is necessary to design an effective shaking table test device and method to simulate the movement of the actual high-speed axial water flow in the fuel assembly of the core, study the dynamic characteristics of the full-scale fuel assembly in moving water, and improve and verify the existing calculation models, calculation parameters and analysis methods based on the test results.

[0006] The applicant of the present invention has found that the prior art has at least the following technical problems: The existing test devices cannot obtain the dynamic characteristics of fuel assemblies under moving water conditions. Summary of the Invention

[0007] The purpose of the present invention is to provide a test device and method for the dynamic characteristics of a full-scale fuel assembly in moving water to solve the technical problem that the existing test devices cannot obtain the dynamic characteristics of fuel assemblies under moving water conditions. The many technical effects that can be produced by the preferred technical solutions among the many technical solutions provided by the present invention are described in detail below.

[0008] To achieve the above purpose, the present invention provides the following technical solutions:

[0009] The test device for the dynamic characteristics of a full-scale fuel assembly in moving water provided by the present invention includes a vibration platform, a device body, a dynamic water circulation loop and a measuring mechanism. The device body is arranged on the vibration platform, wherein:

[0010] The device body sequentially includes a water inlet section, a test section and a water return section from bottom to top. The test section includes a core lower plate, an integral sleeve and a core upper plate. The fuel assembly is arranged inside the integral sleeve. The core lower plate is fixed on the water inlet section. The integral sleeve is connected between the core lower plate and the core upper plate. The water return section is arranged above the core upper plate. The water inlet section and the water return section are respectively communicated with the dynamic water circulation loop. The dynamic water circulation loop is used to provide axial water flow to the device body;

[0011] The integral sleeve is enclosed by two groups of X-side enclosing plates and two groups of Y-side enclosing plates. The X-side enclosing plates are arranged along the vibration direction. Positioning grooves adapted to the size of the Y-side enclosing plates are arranged at both ends of the X-side enclosing plates. Partition plates are arranged between the positioning grooves and the Y-side enclosing plates. By setting partition plates with different thicknesses, the gap between the fuel assembly and the integral sleeve in the vibration direction can be adjusted;

[0012] A pre-tightening bracket is arranged above the core upper plate, and a reserved groove is arranged on the core upper plate. The reserved groove and the pre-tightening bracket both correspond to the position of the leaf spring at the top of the fuel assembly. The pre-tightening bracket includes a bracket upper plate, a bracket lower plate, and a first force sensor arranged between the bracket upper plate and the bracket lower plate. The bracket upper plate is connected to the core upper plate through an adjusting bolt, and the adjusting bolt can make the bracket lower plate pass through the reserved groove and press tightly on the leaf spring at the top of the fuel assembly to provide a pre-tightening force;

[0013] The measuring mechanism includes an electromagnetic flowmeter, an acceleration sensor, a differential pressure sensor, a pressure sensor, and a second force sensor.

[0014] As a further improvement of the present invention, the device body further includes a steel support structure. The steel support structure includes a diagonal brace, a cross beam, a reinforcing channel steel, and a support plate. The support plate is welded on the integral sleeve, the diagonal brace is connected to the support plate through the cross beam, and the reinforcing channel steel is connected between the cross beam and the diagonal brace.

[0015] As a further improvement of the present invention, the dynamic water circulation pipeline includes a water storage tank, a centrifugal pump, and pipelines. Both the water inlet section and the water return section are connected to the water storage tank through the pipelines. The centrifugal pump is arranged between the water storage tank and the water inlet section, and the centrifugal pump is used to pump the water in the water storage tank through the water inlet section into the test section and then back to the water storage tank through the water return section.

[0016] As a further improvement of the present invention, the water inlet section includes a bottom seal, a support block, a bottom adapter plate, a water inlet bottom plate, a trapezoidal transition plate, a flared connecting pipe, and an L-shaped connecting pipe. The bottom seal is fixed on the vibration platform, the bottom adapter plate is fixed on the inner wall of the bottom seal through the support block, the bottom of the trapezoidal transition plate is connected to the bottom adapter plate, the top of the trapezoidal transition plate, the water inlet bottom plate, the core lower plate, and the integral sleeve are fixedly connected by bolts, the flared connecting pipe is fixedly connected to the water inlet bottom plate, and the L-shaped connecting pipe is connected to the bottom end of the flared connecting pipe.

[0017] As a further improvement of the present invention, positioning pin holes are arranged on the core upper plate and the core lower plate, and pin tube holes are arranged on both the upper tube seat and the lower tube seat of the fuel assembly. The positioning pin holes and the pin tube holes correspond to each other.

[0018] As a further improvement of the present invention, the electromagnetic flowmeter is arranged at the top and bottom of the integral sleeve, the acceleration sensors are arranged on the upper nozzle, lower nozzle of the fuel assembly and on each positioning grid of the fuel assembly, the differential pressure sensors are arranged on the middle lower part and middle upper part side walls of the integral sleeve, the pressure sensors are arranged at the top and bottom of the integral sleeve, and the second force sensors are arranged at the bottoms of the four legs of the lower nozzle of the fuel assembly.

[0019] A method for testing the dynamic characteristics of a full-scale fuel assembly in flowing water adopts the above-mentioned test device for the dynamic characteristics of a full-scale fuel assembly in flowing water, and the steps are as follows:

[0020] Step 1: Select the fuel assembly to be tested, determine the gap between the fuel assembly and the integral sleeve, and select a suitable partition plate for installing the integral sleeve.

[0021] Step 2: Fix the integral sleeve, the lower core plate and the water inlet section in a connected manner, then fix the fuel assembly into the integral sleeve, and then fix the upper core plate on the integral sleeve.

[0022] Step 3: Install the pre-tightening bracket on the upper core plate to apply a pre-tightening force to the leaf spring at the top of the fuel assembly.

[0023] Step 4: Install the water return section, and connect the water inlet section and the water return section to the dynamic water circulation loop respectively.

[0024] Step 5: Install the steel support structure.

[0025] Step 6: Start the dynamic water circulation loop to provide axial water flow, start the vibration platform, apply white noise and sine sweep waves with different amplitudes to the device body, and measure the dynamic characteristics of the fuel assembly through the measuring mechanism.

[0026] As a further improvement of the present invention, in Step 1, first install the partition plate between the Y-side enclosure plate and the positioning groove, and then anchor and connect the two groups of X-side enclosure plates and the two groups of Y-side enclosure plates through bolts.

[0027] As a further improvement of the present invention, in Step 2, first anchor and connect the integral sleeve, the lower core plate, the water inlet bottom plate and the trapezoidal transition plate, then lift the fuel assembly into the integral sleeve, connect the bottom of the fuel assembly to the lower core plate, connect the top of the fuel assembly to the upper core plate, and finally connect the integral sleeve to the upper core plate.

[0028] As a further improvement of the present invention, in Step 3, the lower plate of the bracket passes through the reserved groove on the upper core plate and presses on the leaf spring at the top of the fuel assembly, and the lower plate of the bracket applies a pre-tightening force to the leaf spring of the fuel assembly by adjusting the bolts.

[0029] The beneficial effects of the present invention are as follows: The full-scale dynamic characteristic test device for a fuel assembly in flowing water provided by the present invention includes a vibration platform, a device body, a flowing water circulation loop, and a measurement mechanism. The device body is arranged on the vibration platform, and the vibration platform can apply white noise and sine sweep waves with different amplitudes to the device body through earthquake simulation. The device body includes a water inlet section, an integral sleeve, and a water return section. The water inlet section and the water return section are respectively communicated with the flowing water circulation loop. The flowing water circulation loop is used to convey axial water flow into the device body, and the measurement mechanism is used to measure the dynamic characteristics of the fuel assembly when it is subjected to different excitation effects in a flowing water environment;

[0030] The integral sleeve is enclosed by two groups of X-side enclosing plates and two groups of Y-side enclosing plates, and the gap between the fuel assembly and the integral sleeve in the vibration direction can be adjusted by adding partition plates to meet the test requirements for different gaps between the fuel assembly and the enclosing plates along the vibration direction;

[0031] In order to monitor the force condition of the fuel assembly under the action of axial water flow with different flow rates, a leaf spring preloading bracket is designed on the top surface of the upper core plate to apply a pre-static load to the leaf spring of the fuel assembly and monitor the change in the force of the leaf spring of the fuel assembly under the action of axial fluid;

[0032] Water is supplied to the test section through the flowing water circulation loop to fill the test section with water. After closing the flowing water circulation loop, the dynamic characteristic test of the fuel assembly under static water conditions can be carried out. By using the full-scale dynamic characteristic test device for a fuel assembly in flowing water provided by the present invention, the test requirements under static water conditions, flowing water conditions, and different gaps between the fuel assembly and the integral sleeve under flowing water conditions or static water conditions can be realized. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 is a three-dimensional view of the test device of the present invention;

[0035] Figure 2 is a structural schematic diagram of the experimental device of the present invention;

[0036] Figure 3 is a structural schematic diagram of the device body of the present invention;

[0037] Figure 4 is a cross-sectional view (one) of the integral sleeve of the present invention;

[0038] Figure 5 It is the second cross-sectional view of the overall sleeve of the present invention;

[0039] Figure 6 It is the structural schematic diagram of the pre-tightening bracket of the present invention;

[0040] Figure 7 It is the structural schematic diagram of the fuel assembly of the present invention;

[0041] Figure 8 It is the F-F cross-sectional view of the fuel assembly of the present invention;

[0042] Figure 9 It is the G-G cross-sectional view of the fuel assembly of the present invention;

[0043] Figure 10 The schematic diagram of the test device of the present invention.

[0044] In the figure: 1. Vibration platform; 2. Device body; 3. Dynamic water circulation loop; 4. Measuring mechanism; 5. Fuel assembly; 21. Water inlet section; 22. Test section; 23. Water return section; 24. Pre-tightening bracket; 25. Steel support structure; 211. Bottom seal; 212. Support block; 213. Bottom adapter plate; 214. Water inlet bottom plate; 215. Trapezoidal transition plate; 216. Flared nozzle; 217. L-shaped nozzle; 218. Vertical support; 221. Lower core plate; 222. Overall sleeve; 223. Upper core plate; 224. X-side enclosure; 225. Y-side enclosure; 226. Positioning groove; 227. Partition; 241. Bracket upper plate; 242. Bracket lower plate; 243. First force sensor; 244. Adjusting bolt; 251. Diagonal brace; 252. Cross beam; 253. Reinforcing channel steel; 254. Support plate; 31. Water storage tank; 32. Centrifugal pump; 33. Pipeline; 41. Electromagnetic flowmeter; 42. Acceleration sensor; 43. Differential pressure sensor; 44. Pressure sensor; 45. Second force sensor; 51. Lower tube socket; 52. Upper tube socket; 53. Fuel rod; 54. Spacer grid; 55. Leaf spring. Specific embodiments

[0045] The following can refer to the attached drawings Figures 1 to 10Understand the content of the present invention and the differences between the present invention and the prior art in terms of text content. The following further elaborates on the technical solutions (including preferred technical solutions) of the present invention by way of drawings and by listing some alternative embodiments of the present invention. It should be noted that: any technical feature or any technical solution in this embodiment is one or several of a variety of alternative technical features or alternative technical solutions. For the sake of concise description, all alternative technical features and alternative technical solutions of the present invention cannot be exhausted in this document, nor is it convenient to emphasize that each implementation manner of a technical feature is one of the alternative implementation manners. Therefore, those skilled in the art should be aware that: any technical means provided by the present invention can be replaced, or any two or more technical means or technical features provided by the present invention can be combined with each other to obtain a new technical solution. Any technical feature and any technical solution within this embodiment do not limit the protection scope of the present invention. The protection scope of the present invention should include any alternative technical solutions that those skilled in the art can think of without creative labor, and new technical solutions obtained by those skilled in the art by combining any two or more technical means or technical features provided by the present invention with each other.

[0046] In the description of the present invention, it should be noted that unless otherwise specified, the meaning of "a plurality of" is two or more; the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present invention. In addition, terms such as "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0047] In the description of the present invention, it should also be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] The present invention provides a full-scale fuel assembly dynamic characteristic test device for dynamic characteristics that can be tested under moving water conditions.

[0049] The following combines Figures 1 to 10 to elaborate more details on the technical solutions provided by the present invention.

[0050] The present invention provides a full-scale test device for the dynamic characteristics of a fuel assembly in flowing water, which includes a vibration platform, a device body, a dynamic water circulation loop, and a measurement mechanism. The device body is arranged on the vibration platform, where:

[0051] The device body sequentially includes an inlet section, a test section, and a return section from bottom to top. The test section includes a core bottom plate, an integral sleeve, and a core top plate. The fuel assembly is arranged inside the integral sleeve. The core bottom plate is fixed on the inlet section. The integral sleeve is connected between the core bottom plate and the core top plate. The return section is arranged above the core top plate. The inlet section and the return section are respectively communicated with the dynamic water circulation loop, and the dynamic water circulation loop is used to provide axial water flow to the device body.

[0052] The integral sleeve is enclosed by two groups of X-side enclosing plates and two groups of Y-side enclosing plates. The X-side enclosing plates are arranged along the vibration direction. Positioning grooves adapted to the size of the Y-side enclosing plates are arranged at both ends of the X-side enclosing plates. Partition plates are arranged between the positioning grooves and the Y-side enclosing plates. By setting partition plates with different thicknesses, the gap between the fuel assembly and the integral sleeve in the vibration direction can be adjusted.

[0053] A pre-tightening bracket is arranged above the core top plate. A reserved groove is arranged on the core top plate. Both the reserved groove and the pre-tightening bracket correspond to the position of the leaf spring at the top of the fuel assembly. The pre-tightening bracket includes a bracket top plate, a bracket bottom plate, and a first force sensor arranged between the bracket top plate and the bracket bottom plate. The bracket top plate is connected to the core top plate through an adjusting bolt. The adjusting bolt can make the bracket bottom plate pass through the reserved groove and press tightly on the leaf spring at the top of the fuel assembly to provide a pre-tightening force.

[0054] The measurement mechanism includes an electromagnetic flowmeter, an acceleration sensor, a differential pressure sensor, a pressure sensor, and a second force sensor.

[0055] The full-scale test device for the dynamic characteristics of a fuel assembly in flowing water provided by the present invention includes a vibration platform, a device body, a dynamic water circulation loop, and a measurement mechanism. The device body is arranged on the vibration platform. The vibration platform can apply white noise and sine sweep waves with different amplitudes to the device body through earthquake simulation. The device body includes an inlet section, an integral sleeve, and a return section. The inlet section and the return section are respectively communicated with the dynamic water circulation loop. The dynamic water circulation loop is used to convey axial water flow into the device body. The measurement mechanism is used to measure the dynamic characteristics of the fuel assembly when it is subjected to different excitation effects in a dynamic water environment.

[0056] The integral sleeve is formed by enclosing two groups of X-side enclosing plates and two groups of Y-side enclosing plates, and the gap between the fuel assembly and the integral sleeve in the vibration exciting direction can be adjusted by adding partition plates to meet the test requirements of different gaps between the fuel assembly and the enclosing plates along the vibration exciting direction;

[0057] In order to monitor the force condition of the fuel assembly under the action of axial water flow at different flow rates, a leaf spring preloading bracket is designed on the top surface of the upper core plate to apply a pre-static load to the leaf spring of the fuel assembly and monitor the change of the force on the leaf spring of the fuel assembly under the action of axial fluid;

[0058] Water is supplied to the test section through the dynamic water circulation loop to fill the test section with water, and then the dynamic water circulation loop is closed, and the dynamic characteristic test of the fuel assembly under static water conditions can be carried out; by using the dynamic water full-scale fuel assembly dynamic characteristic test device provided by the present invention, the test requirements under static water conditions, dynamic water conditions and different gaps between the fuel assembly and the integral sleeve under dynamic water conditions or static water conditions can be realized.

[0059] As a further improvement of the present invention, the device body further includes a steel support structure, the steel support structure includes diagonal braces, cross beams, reinforcing channel steels and support plates, the support plates are welded on the integral sleeve, the diagonal braces are connected to the support plates through the cross beams, and the reinforcing channel steels are connected between the cross beams and the diagonal braces.

[0060] The steel support structure is used to improve the overall stiffness of the device body. The diagonal braces are connected to the support plates through the cross beams and enclose the integral sleeve around. The diagonal braces are anchored on the vibration platform by bolts to meet the requirements of carrying out the dynamic characteristic test of the fuel assembly on the vibration platform.

[0061] As a further improvement of the present invention, the dynamic water circulation pipeline includes a water storage tank, a centrifugal pump and pipelines. Both the water inlet section and the water return section are connected to the water storage tank through the pipelines. The centrifugal pump is arranged between the water storage tank and the water inlet section. The centrifugal pump is used to pump the water in the water storage tank through the water inlet section into the test section and then return to the water storage tank through the water return section.

[0062] The centrifugal pump is a vertical pipeline pump controlled by a variable frequency motor, and the pipeline flow can be continuously adjusted; the pipeline is processed by high-pressure water pipes, and high-pressure hoses, high-pressure rigid pipes, elbow sections and flanges are respectively used for connection at different parts of the loop. A regulating valve, a ball valve, etc. are arranged in the dynamic water circulation loop for opening and closing the dynamic water circulation channel. The return water pipeline is vertically supported by the dynamic water pipeline vertical support.

[0063] As a further improvement of the present invention, the water inlet section includes a bottom seal, support blocks, a bottom adapter plate, a water inlet bottom plate, a trapezoidal transition plate, a flared connecting pipe, and an L-shaped connecting pipe. The bottom seal is fixed on the vibration platform. The bottom adapter plate is fixed on the inner wall of the bottom seal through the support blocks. The bottom of the trapezoidal transition plate is connected to the bottom adapter plate. The top of the trapezoidal transition plate, the water inlet bottom plate, the lower core plate, and the integral sleeve are fixedly connected by bolts. The flared connecting pipe is fixedly connected to the water inlet bottom plate. The L-shaped connecting pipe is connected to the bottom end of the flared connecting pipe.

[0064] The water inlet section serves as the vertical load-bearing structure of the test section. The L-shaped connecting pipe welded to the bottom seal is connected to the dynamic water circulation loop, horizontally introducing water flow into the water inlet section. Through the L-shaped connecting pipe and the flared connecting pipe, the water flow is converted into axial water flow. The top of the trapezoidal transition plate, the water inlet bottom plate, the lower core plate, and the integral sleeve are fixedly connected by bolts to ensure the connection strength between the water inlet section and the test section.

[0065] The water inlet bottom plate is connected to the flared connecting pipe. Four water inlet holes are reserved on the water inlet bottom plate. The aperture and position simulate the actual core, ensuring that water flow is evenly injected into the integral sleeve of the test section through the four water inlet holes. In addition, the bottom seal also serves as the vertical load-bearing structure of the integral sleeve and the fuel assembly (including water). Six stiffening plates are evenly welded along the bottom circumference of the outer circle of the bottom seal to locally strengthen the bottom seal.

[0066] As a further improvement of the present invention, positioning pin holes are provided on the upper core plate and the lower core plate. Pin holes are provided on both the upper tube seat and the lower tube seat of the fuel assembly. The positioning pin holes and the pin holes are corresponding to each other.

[0067] When hoisting the fuel assembly, a lower pin is installed in the positioning pin hole of the lower core plate. The fuel assembly is vertically hoisted in, and the lower pin is inserted into the pin hole of the lower tube seat of the fuel assembly to complete the positioning of the fuel assembly and the lower core plate. An upper pin is installed in the positioning pin hole of the upper core plate. The upper core plate is vertically pressed above the fuel assembly, and the upper pin is inserted into the pin hole of the upper tube seat of the fuel assembly. Then, the integral sleeve is anchored to the upper core plate to complete the installation of the fuel assembly.

[0068] As a further improvement of the present invention, the electromagnetic flowmeter is arranged at the top and bottom of the integral sleeve, the acceleration sensors are arranged on the upper tube seat, the lower tube seat of the fuel assembly, and each positioning grid of the fuel assembly. The differential pressure sensors are arranged on the middle lower part and the middle upper part side walls of the integral sleeve. The pressure sensors are arranged at the top and bottom of the integral sleeve. The second force sensors are arranged at the bottoms of the four legs of the lower tube seat of the fuel assembly.

[0069] Pitot tubes are installed on the upper-middle and middle-lower side walls of the overall sleeve and are equipped with differential pressure sensors to monitor the fluid velocity in the test section; pressure sensors are installed on the bottom and top side walls of the overall sleeve to monitor the head loss of the fuel assembly; at the same time, acceleration sensors are arranged on the upper and lower tube seats of the fuel assembly, and acceleration sensors are buried in the guide tubes at the corresponding heights of each grid to measure the motion acceleration of the fuel assembly for the analysis of the dynamic characteristics of the fuel assembly under different clearances and different dynamic water flow velocities. The second force sensor is used to monitor the change of the force exerted by the fuel assembly on the lower core plate under the action of axial fluid.

[0070] A full-scale fuel assembly dynamic characteristic test method in dynamic water uses the full-scale fuel assembly dynamic characteristic test device described above, and its steps are as follows:

[0071] Step 1: Select the fuel assembly to be tested, determine the clearance between the fuel assembly and the overall sleeve, and select a suitable partition to install the overall sleeve.

[0072] Step 2: Fix the overall sleeve, the lower core plate and the water inlet section in a connected manner, then fix the fuel assembly in the overall sleeve, and then fix the upper core plate on the overall sleeve.

[0073] Step 3: Install the pre-tightening bracket on the upper core plate to apply a pre-tightening force to the leaf spring at the top of the fuel assembly.

[0074] Step 4: Install the return water section, and connect the water inlet section and the return water section to the dynamic water circulation loop respectively.

[0075] Step 5: Install the steel support structure.

[0076] Step 6: Start the dynamic water circulation loop to provide axial water flow, start the vibration platform, apply white noise and sine sweep waves with different amplitudes to the device body, and measure the dynamic characteristics of the fuel assembly through the measuring mechanism.

[0077] As a further improvement of the present invention, in step 1, first install the partition between the Y-side enclosure and the positioning groove, and then anchor and connect the two groups of X-side enclosures and the two groups of Y-side enclosures through bolts.

[0078] As a further improvement of the present invention, in step 2, first anchor and connect the overall sleeve, the lower core plate, the water inlet bottom plate and the trapezoidal transition plate, then lift the fuel assembly into the overall sleeve, connect the bottom of the fuel assembly to the lower core plate, connect the top of the fuel assembly to the upper core plate, and finally connect the overall sleeve to the upper core plate.

[0079] As a further improvement of the present invention, in step 3, the lower bracket plate passes through the reserved groove on the upper core plate and presses on the leaf spring at the top of the fuel assembly, and the lower bracket plate applies a pre-tightening force to the leaf spring of the fuel assembly by adjusting the bolts.

[0080] Example 1:

[0081] A full-scale dynamic characteristic test device for a fuel assembly in moving water provided by the present invention includes a vibration platform 1, a device body 2, a moving water circulation loop 3 and a measuring mechanism 4. The device body 2 is arranged on the vibration platform 1.

[0082] The device body 2 sequentially includes a water inlet section 21, a test section 22 and a water return section 23 from bottom to top. The moving water circulation loop 3 includes a water storage tank 31, a centrifugal pump 32 and a pipeline 33. Both the water inlet section 21 and the water return section 23 are connected to the water storage tank 31 through the pipeline 33. The centrifugal pump 32 is arranged between the water storage tank 31 and the water inlet section 21. The centrifugal pump 32 is used to pump the water in the water storage tank 31 into the test section 22 through the water inlet section 21 to provide axial water flow into the test section 22, and then it flows back to the water storage tank 31 through the water return section 23.

[0083] Specifically, the centrifugal pump 32 is a vertical pipeline pump controlled by a variable-frequency motor, and the flow rate of the pipeline 33 can be continuously adjusted. The pipeline 33 is processed by high-pressure water pipes, and high-pressure hoses, high-pressure rigid pipes, elbow sections and flanges are respectively used for connection at different parts of the loop. A regulating valve, a ball valve, etc. are arranged in the moving water circulation loop 3 for opening and closing the moving water circulation channel. The vertical support of the moving water pipeline is used for vertically supporting the water return pipeline.

[0084] The test section 22 includes a core lower plate 221, an integral sleeve 222 and a core upper plate 223. The integral sleeve 222 is connected between the core lower plate 221 and the core upper plate 223. The fuel assembly 5 is arranged in the integral sleeve 222. The integral sleeve 222 is surrounded by two groups of X-side enclosing plates 224 and two groups of Y-side enclosing plates 225. The X-side enclosing plates 224 are arranged along the vibration direction. Positioning grooves 226 adapted to the size of the Y-side enclosing plates 225 are arranged at both ends of the X-side enclosing plates 224. A partition plate 227 is arranged between the positioning grooves 226 and the Y-side enclosing plates 225. By setting partition plates 227 with different thicknesses, the gap between the fuel assembly 5 and the integral sleeve 222 in the vibration direction can be adjusted.

[0085] Specifically, the fuel assembly 5 includes a lower tube seat 51, an upper tube seat 52, fuel rods 53, a positioning grid 54 and leaf springs 55. The fuel rods 53 are fixed between the lower tube seat 51 and the upper tube seat 52 and are clamped by the positioning grid 54. The leaf springs 55 are arranged on the lower tube seat 51.

[0086] The water inlet section 21 includes a bottom seal 211, a support block 212, a bottom adapter plate 213, a water inlet bottom plate 214, a trapezoidal transition plate 215, a trumpet-shaped connecting pipe 216, and an L-shaped connecting pipe 217. The bottom seal 211 is fixed on the vibration platform 1. The bottom adapter plate 213 is fixed on the inner wall of the bottom seal 211 through the support block 212. The bottom of the trapezoidal transition plate 215 is connected to the bottom adapter plate 213. The top of the trapezoidal transition plate 215, the water inlet bottom plate 214, the lower core plate 221, and the integral sleeve 222 are fixedly connected by bolts. The trumpet-shaped connecting pipe 216 is fixedly connected to the water inlet bottom plate 214. The L-shaped connecting pipe 217 is connected to the bottom end of the trumpet-shaped connecting pipe 216. Additionally, a vertical support 218 is provided at the bottom of the L-shaped connecting pipe 217, and the vertical support 218 is fixed to the bottom of the bottom seal 211 to support the L-shaped connecting pipe 217.

[0087] Positioning pin holes are provided on the upper core plate 223 and the lower core plate 221. Pin holes are provided on both the lower socket 51 and the upper socket 52 of the fuel assembly 5, and the positioning pin holes and the pin holes correspond to each other. When hoisting the fuel assembly 5, a lower pin is installed in the positioning pin hole of the lower core plate 221, the fuel assembly 5 is vertically hoisted in, and the lower pin is inserted into the pin hole of the upper socket 52 of the fuel assembly 5 to complete the positioning of the fuel assembly 5 and the lower core plate 221. An upper pin is installed in the positioning pin hole of the upper core plate 223, the upper core plate 223 is vertically pressed above the fuel assembly 5, the upper pin is inserted into the pin hole of the lower socket 51 of the fuel assembly 5, and then the integral sleeve 222 is anchored to the upper core plate 223 to complete the installation of the fuel assembly 5.

[0088] A pre-tightening bracket 24 is provided on the upper core plate 223. A reserved groove is provided on the upper core plate 223. The reserved groove and the pre-tightening bracket 24 both correspond to the position of the leaf spring 55 at the top of the fuel assembly 5. The pre-tightening bracket 24 includes an upper bracket plate 241, a lower bracket plate 242, and a first force sensor 243 provided between the upper bracket plate 241 and the lower bracket plate 242. The upper bracket plate 241 is connected to the upper core plate 223 through an adjusting bolt 244. The adjusting bolt 244 can make the lower bracket plate 242 pass through the reserved groove and press tightly on the leaf spring 55 at the top of the fuel assembly 5 to provide a pre-tightening force.

[0089] Further, four vertical pressing blocks are designed on the lower plate 242 of the support, and their planar positions correspond to the planar positions of the leaf springs 55 of the lower nozzle 51 of the fuel assembly 5; two first force sensors 243 are installed and anchored between the upper plate 241 and the lower plate 242 of the support; the pre-tightening support 24 is installed on the upper plate 223 of the reactor core, and the vertical pressing blocks on the lower plate 242 of the support just pass through the reserved slots on the upper plate 223 of the reactor core and contact the leaf springs 55; the adjusting bolt 244 applies a downward load to the whole pre-tightening support 24 to realize the pre-tightening of the leaf springs 55 of the fuel assembly 5, and the pre-tightening force is picked up by the first force sensor 243; when the pre-tightening force reaches the specified load, the loading is stopped, and the pre-tightening support 24 is fixed on the upper plate 223 of the reactor core through the adjusting bolt 244. In addition, four second force sensors 45 are arranged at the bottoms of the four legs of the upper nozzle 52 of the fuel assembly 5 to monitor the change of the force exerted by the fuel assembly 5 on the lower plate 221 of the reactor core under the action of axial fluid.

[0090] The device body 2 further includes a steel support structure 25 for improving the overall stiffness of the device body 2. The steel support structure 25 includes diagonal braces 251, cross beams 252, reinforcing channel steels 253 and support plates 254. The support plates 254 are welded on the integral sleeve 222. The diagonal braces 251 are connected to the support plates 254 through the cross beams 252, and the reinforcing channel steels 253 are connected between the cross beams 252 and the diagonal braces 251.

[0091] The measuring mechanism 4 includes an electromagnetic flowmeter 41, an acceleration sensor 42, a differential pressure sensor 43, a pressure sensor 44 and a second force sensor 45. The electromagnetic flowmeter 41 is arranged at the top and bottom of the integral sleeve 222, the acceleration sensor 42 is arranged on the lower nozzle 51 and the upper nozzle 52 of the fuel assembly 5, and the acceleration sensor 42 is arranged on each layer of positioning grid 54. The differential pressure sensor 43 is arranged on the middle-lower and middle-upper side walls of the integral sleeve 222, the pressure sensor 44 is arranged at the top and bottom of the integral sleeve 222, and the second force sensor 45 is arranged at the bottoms of the four legs of the upper nozzle 52 of the fuel assembly 5.

[0092] A full-scale fuel assembly dynamic characteristic test method in flowing water uses the full-scale fuel assembly dynamic characteristic test device in flowing water as described above, and the steps are as follows:

[0093] Step 1: Select the fuel assembly 5 to be tested, determine the gap between the fuel assembly 5 and the integral sleeve 222, select a suitable partition plate 227, first install the partition plate 227 between the Y-side enclosure plate 225 and the positioning groove 226, and then anchor and connect the two groups of X-side enclosure plates 224 and the two groups of Y-side enclosure plates 225 through bolts to install the integral sleeve 222;

[0094] Step 2: First, anchor and connect the integral sleeve 222, the core lower plate 221, the water inlet bottom plate 214 and the trapezoidal transition plate 215. Then, lift the fuel assembly 5 into the integral sleeve 222. Install lower pins in the positioning pin holes of the core lower plate 221. Vertically lift the fuel assembly 5, and insert the lower pins into the pin holes of the upper nozzle 52 of the fuel assembly 5 to complete the positioning of the fuel assembly 5 and the core lower plate 221. Install upper pins in the positioning pin holes of the core upper plate 223. Vertically press the core upper plate 223 above the fuel assembly 5, and insert the upper pins into the pin holes of the lower nozzle 51 of the fuel assembly 5 to anchor the integral sleeve 222 and the core upper plate 223.

[0095] Step 3: Install the pre-tightening bracket 24 on the core upper plate 223 to apply a pre-tightening force to the leaf spring 55 at the top of the fuel assembly 5.

[0096] Step 4: Install the return water section 23, and connect the water inlet section 21 and the return water section 23 to the dynamic water circulation loop 3 respectively.

[0097] Step 5: Install the steel support structure 25.

[0098] Step 6: Start the dynamic water circulation loop 3 to provide axial water flow. Start the vibration platform 1, apply white noise and sine sweep waves with different amplitudes to the device body 2, and measure the dynamic characteristics of the fuel assembly 5 through the measuring mechanism 4.

[0099] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A dynamic characteristics test device for full-scale fuel assemblies in moving water, It is characterized in that It includes a vibration platform, a device body, a dynamic water circulation loop and a measuring mechanism, wherein the device body is arranged on the vibration platform, wherein: The device body includes a water inlet section, a test section and a water return section from the bottom to the top, the test section includes a core lower plate, an integral sleeve and a core upper plate, the fuel assembly is arranged in the integral sleeve, the core lower plate is fixed on the water inlet section, the integral sleeve is connected between the core lower plate and the core upper plate, the water return section is arranged above the core upper plate, the water inlet section and the water return section are respectively connected to the dynamic water circulation loop, and the dynamic water circulation loop is used to provide axial water flow to the device body; The integral sleeve is formed by enclosing two groups of X side panels and two groups of Y side panels, the X side panels are arranged along the vibration direction, positioning grooves matching the size of the Y side panels are arranged at both ends of the X side panels, and a partition is arranged between the positioning groove and the Y side panels. The gap between the fuel assembly and the integral sleeve in the vibration direction can be adjusted by arranging partitions of different thicknesses; The measuring mechanism includes an electromagnetic flowmeter, an acceleration sensor, a differential pressure sensor, a pressure sensor, and a second force sensor; A pre-tightening bracket is arranged above the upper plate of the core, and a reserved groove is arranged on the upper plate of the core. The reserved groove and the pre-tightening bracket both correspond to the position of the leaf spring on the top of the fuel assembly. The pre-tightening bracket includes an upper plate of the bracket, a lower plate of the bracket and a first force sensor arranged between the upper plate of the bracket and the lower plate of the bracket. The upper plate of the bracket is connected to the upper plate of the core by adjusting bolts. The adjusting bolts can make the lower plate of the bracket pass through the reserved groove and tighten against the leaf spring on the top of the fuel assembly to provide a pre-tightening force.

2. The dynamic characteristics test device for full-scale fuel assemblies in moving water according to claim 1, It is characterized in that The device body also includes a steel support structure, which includes a diagonal brace, a cross beam, a reinforcing channel steel and a support plate. The support plate is welded to the integral sleeve, the diagonal brace is connected to the support plate through the cross beam, and the reinforcing channel steel is connected between the cross beam and the diagonal brace.

3. The dynamic characteristics test device for full-scale fuel assemblies in moving water according to claim 2, It is characterized in that The water inlet section includes a bottom cover, a support block, a bottom adapter plate, a water inlet bottom plate, a trapezoidal transition plate, a trumpet-shaped pipe and an L-shaped pipe. The bottom cover is fixed to the vibration platform, the bottom adapter plate is fixed to the inner wall of the bottom cover through the support block, the bottom of the trapezoidal transition plate is connected to the bottom adapter plate, the top of the trapezoidal transition plate, the water inlet bottom plate, the core lower plate and the integral sleeve are fixedly connected by bolts, the trumpet-shaped pipe is fixedly connected to the water inlet bottom plate, and the L-shaped pipe is connected to the bottom end of the trumpet-shaped pipe.

4. The dynamic characteristics test device for full-scale fuel assemblies in moving water according to claim 3, It is characterized in that Positioning pin holes are provided on the upper core plate and the lower core plate, and pin tube holes are provided on both the upper nozzle and the lower nozzle of the fuel assembly. The positioning pin holes and the pin tube holes correspond to each other.

5. The full-scale fuel assembly dynamic characteristic test device in flowing water according to claim 4, characterized in that the flowing water circulation pipeline includes a water storage tank, a centrifugal pump and pipelines. Both the water inlet section and the water return section are connected to the water storage tank through the pipelines. The centrifugal pump is arranged between the water storage tank and the water inlet section. The centrifugal pump is used to pump the water in the water storage tank through the water inlet section into the test section and then back to the water storage tank through the water return section.

6. The full-scale fuel assembly dynamic characteristic test device in flowing water according to claim 1, characterized in that the electromagnetic flowmeter is arranged at the top and bottom of the integral sleeve, the acceleration sensors are arranged on the upper nozzle, the lower nozzle of the fuel assembly and each positioning grid of the fuel assembly, the differential pressure sensors are arranged on the middle lower part and the middle upper part side walls of the integral sleeve, the pressure sensors are arranged at the top and bottom of the integral sleeve, and the second force sensors are arranged at the bottoms of the four legs of the lower nozzle of the fuel assembly.

7. A method for testing the dynamic characteristics of a full-scale fuel assembly in flowing water, characterized in that using the full-scale fuel assembly dynamic characteristic test device in flowing water according to claim 4, and the steps are as follows: Step 1: Select the fuel assembly to be tested, determine the gap between the fuel assembly and the integral sleeve, select a suitable partition plate, first install the partition plate between the Y-side enclosure plate and the positioning groove, and then anchor and connect the two groups of X-side enclosure plates and the two groups of Y-side enclosure plates by bolts to install the integral sleeve; Step 2: First anchor and connect the integral sleeve, the lower core plate, the water inlet bottom plate and the trapezoidal transition plate. Install a lower pin in the positioning pin hole of the lower core plate, and then lift the fuel assembly into the integral sleeve. The fuel assembly is vertically lifted, and the lower pin is inserted into the pin tube hole of the lower nozzle of the fuel assembly to complete the positioning of the fuel assembly and the lower core plate; install an upper pin in the positioning pin hole of the upper core plate, the upper core plate is vertically pressed above the fuel assembly, and the upper pin is inserted into the pin tube hole of the upper nozzle of the fuel assembly to anchor the integral sleeve and the upper core plate; Step 3: Install the pre-tightening bracket on the upper core plate to apply a pre-tightening force to the leaf spring at the top of the fuel assembly; Step 4: Install the water return section and connect the water inlet section and the water return section to the flowing water circulation loop respectively; Step 5: Install the steel support structure; Step 6: Open the flowing water circulation loop to provide axial water flow, start the vibration platform, apply white noise and sine sweep waves with different amplitudes to the device body, and measure the dynamic characteristics of the fuel assembly through the measuring mechanism.

Images