Equivalent component design method, thermal hydraulic experimental system and simulation experimental method

Abstract

The present application provides an equivalent component design method, a thermal hydraulic experiment system and a simulation experiment method. The equivalent component design method of a core fuel assembly includes obtaining the actual parameters of a first fuel assembly in a core and obtaining the simulation parameters of a second fuel assembly that is set up in a different arrangement mode and an equivalent model device to the core, comparing the simulation parameters and actual parameters of the second fuel assembly in different arrangements, and selecting the second fuel assembly and its arrangement mode with the simulation parameters closest to the actual parameters of the first fuel assembly as the equivalent component of the first fuel assembly, because the actual parameters and the simulation parameters are similar, the second fuel assembly is less affected by the "side wall effect" and the "cold wall effect", and the second fuel assembly has better representativeness.

Description

Technical Field

[0001] The present application relates to the technical field of nuclear devices, and in particular to an equivalent component design method, a thermal hydraulic experiment system and a simulation experiment method. Background Art

[0002] Reactor fuel assembly simulation characteristics are an important research content of fuel assembly performance. The research on the simulation characteristics of fuel assemblies is of great significance to the design demonstration of fuel assemblies and improving the comprehensive performance of assemblies. In order to improve the performance of core fuel assemblies and optimize their design, various countries have carried out simulation analysis and experimental research on this.

[0003] Due to the particularity of reactor fuel assemblies, it is impossible to carry out off-core experiments directly. Therefore, it is necessary to invent a method to determine the typical grid elements of the equivalent structure of the fuel assembly, and to design an equivalent experimental model based on the core assembly structure that can effectively reduce the influence of the "cold wall effect" and "side wall effect" and has good representativeness and economy. Summary of the invention

[0004] In view of the above problems, the present application provides an equivalent component design method, a thermal-hydraulic experimental system and a thermal-hydraulic experimental method to reduce the influence of the "cold wall effect" and "side wall effect" on the equivalent components of the reactor fuel assembly, so that the equivalent components of the reactor fuel assembly have good representativeness.

[0005] In a first aspect, the present application provides an equivalent assembly design method, comprising: obtaining actual parameters of a first fuel assembly in a core, the actual parameters comprising at least one of actual temperature characteristic information and actual flow characteristic information;

[0006] Acquire simulation parameters of a second fuel assembly arranged in an equivalent model device in different arrangements, the simulation parameters including at least one of simulated temperature characteristic information and simulated flow characteristic information, the simulation parameters corresponding to actual parameters, the equivalent model device being an equivalent model of a core, the second fuel assembly being composed of n element rods, n>0, and gaps between the element rods forming channels;

[0007] Screening out the second fuel assembly with simulation parameters whose deviation from the actual parameters is less than or equal to 15% as the target group;

[0008] The second fuel assembly having simulation parameters closest to the actual parameters in the target group and its corresponding arrangement are determined to be equivalent assemblies of the first fuel assembly.

[0009] In some embodiments, the second fuel assembly includes n element rods, n≤100, and the first fuel assembly is a closely arranged fuel assembly arranged side by side.

[0010] In some embodiments, the target group includes a first target group, and in the step of selecting the second fuel assembly having simulation parameters with a deviation of less than or equal to 15% from the actual parameters as the target group, the second fuel assembly that meets the pressure drop deviation range and the temperature drop deviation range specified by formula (1) and formula (2) is selected as the first target group;

[0011]

[0012] Where Δp is the average pressure drop in the channel; T h is the average outlet temperature of the channel; i is the number of element rods in the second fuel assembly.

[0013] In the step of determining the second fuel assembly in the target group having the simulation parameters closest to the actual parameters and the corresponding arrangement thereof as an equivalent assembly of the equivalent assembly of the first fuel assembly,

[0014] The second fuel assembly having simulation parameters closest to the actual parameters in the first target group and its corresponding arrangement are determined to be equivalent assemblies of the first fuel assembly.

[0015] In some embodiments, before determining that the second fuel assembly with simulation parameters closest to the actual parameters in the first target group and its corresponding arrangement method are equivalent components of the first fuel assembly, it also includes: obtaining the first actual parameters of the first fuel assembly in the core, the first actual parameters including at least one of actual geometric characteristic parameters, actual resistance characteristics, actual flow distribution state, actual outlet temperature distribution and actual heat transfer coefficient; obtaining the first simulation parameters of the second fuel assembly arranged in the equivalent model device in different arrangements, the first simulation parameters including at least one of simulated geometric characteristic parameters, simulated resistance characteristics, simulated flow distribution state, simulated outlet temperature distribution and simulated heat transfer coefficient, and the first simulation parameters correspond to the first actual parameters; the step of determining that the second fuel assembly with simulation parameters closest to the actual parameters and its corresponding arrangement method are equivalent components of the equivalent components of the first fuel assembly in the target group includes: performing fluid dynamics numerical simulation calculation and analysis on the second fuel assembly in the first target group; determining that the second fuel assembly with the first simulation parameters closest to the first actual parameters in the first target group and its corresponding arrangement method are equivalent components of the first fuel assembly.

[0016] In some embodiments, the first fuel assembly is a spherical fuel assembly and the second fuel assembly has a porous structure.

[0017] In some embodiments, the target group includes a second target group, and in the step of screening out the second fuel assembly with simulation parameters whose deviation from the actual parameters is less than or equal to 15% as the target group, the second actual parameters of the first fuel assembly in the core are obtained, and the second actual parameters include at least one of the actual volume porosity, the actual hydraulic equivalent diameter and the actual specific surface area; the second simulation parameters of the second fuel assembly arranged in the equivalent model device in different arrangements are obtained, and the second simulation parameters include at least one of the simulated volume porosity, the simulated hydraulic equivalent diameter and the simulated specific surface area, and the second simulation parameters correspond to the second actual parameters; the second fuel assembly with second simulation parameters whose deviation from the second actual parameters is less than or equal to 15% is screened out as the second target group; in the step of determining the second fuel assembly with simulation parameters closest to the actual parameters and its corresponding arrangement as the equivalent assembly of the first fuel assembly, the second fuel assembly with second simulation parameters closest to the second actual parameters in the second target group and its corresponding arrangement are determined as the equivalent assembly of the first fuel assembly.

[0018] In some embodiments, before determining the second fuel assembly with the second simulation parameter closest to the second actual parameter and its corresponding arrangement mode in the second target group as the equivalent assembly of the first fuel assembly, it also includes: selecting the second fuel assembly that meets the heat transfer coefficient deviation range specified by formula (3) in the second target group as the third target group;

[0019]

[0020] Where q is the heat flux density on the outer wall of the channel; T w (z) is the wall temperature of the channel; T f (z) is the fluid temperature; in the step of determining that the second fuel assembly in the second target group having the second simulation parameter closest to the second actual parameter and its corresponding arrangement are equivalent assemblies of the first fuel assembly, the second fuel assembly in the third target group having the simulated heat transfer coefficient information closest to the actual heat transfer coefficient information and its corresponding arrangement are equivalent assemblies of the first fuel assembly.

[0021] In some embodiments, before determining the second fuel assembly with the second simulation parameter closest to the second actual parameter and its corresponding arrangement as the equivalent assembly of the first fuel assembly in the second target group, the method further includes: selecting the second fuel assembly that meets the pressure drop deviation range specified by formula (4) in the second target group as the fourth target group,

[0022]

[0023] Wherein, Δp is the average pressure drop of the channel; i is the number of element rods in the second fuel assembly;

[0024] In the step of determining that the second fuel assembly having the second simulation parameter closest to the second actual parameter and its corresponding arrangement method in the second target group are equivalent to the first fuel assembly, the second fuel assembly having the simulated pressure drop information closest to the actual pressure drop information and its corresponding arrangement method in the fourth target group are equivalent to the first fuel assembly.

[0025] In a second aspect, the present application provides a thermal-hydraulic experimental system for a core, comprising: an equivalent component designed according to the equivalent component design method according to any one of claims 1 to 9; a thermal-hydraulic experimental device for collecting experimental data for thermal-hydraulic experiments applied to the core, the thermal-hydraulic experimental device comprising a pressure-bearing component, an electric heating component, an insulating component and a sealing component, the pressure-bearing component comprising a cylinder extending along a first direction; the electric heating component comprising an equivalent component located in the cylinder, the equivalent component comprising at least one element rod with annular ribs, a first conductive component and a second conductive component being connected at both ends of the cylinder, the equivalent component being electrically connected to the first conductive component and the second conductive component; the insulating component being located between the cylinder and the equivalent component; the sealing component being arranged at one end of the cylinder close to the second conductive component, for achieving sealing of the thermal-hydraulic experimental device, wherein the pressure-bearing component, the electric heating component, the insulating component and the sealing component are detachably assembled together.

[0026] In some embodiments, the equivalent component is a rod bundle including 19 element rods, and the rod bundle is arranged from the center to the edge: the first layer is provided with 1 element rod; the second layer is provided with 6 element rods around the first layer; the third layer is provided with 12 element rods around the second layer.

[0027] In some embodiments, a positioning grid is disposed in the cylinder, and 19 positioning holes are opened on the positioning grid, and an element rod is disposed in each positioning hole.

[0028] In some embodiments, the positioning hole is a plum blossom hole, and at least one rib is disposed in the plum blossom hole.

[0029] In some embodiments, a pressure measuring device is also included, which is arranged on one side of the cylinder. The pressure measuring device includes a pressure-leading pipeline, which is connected to the cylinder. The pressure measuring device is used to measure the pressure data of the thermal hydraulic experimental device.

[0030] In some embodiments, a temperature measuring device is also included, which includes a guide tube and a thermocouple. The guide tube passes through the first conductive component and enters the cylinder. The thermocouple is arranged in the guide tube and is used to measure the temperature data of the thermal hydraulic experimental system.

[0031] In some embodiments, the element rod includes a first cold segment element, a hot segment element, and a second cold segment element arranged along a first direction, the first cold segment element is welded to the hot segment element, and the hot segment element is welded to the second cold segment element.

[0032] In some embodiments, the first cold segment element includes a first segment and a second segment connected to each other, the first segment is connected to the hot segment element, the diameter of the first segment is the same as that of the hot segment element, and the second segment is connected to a surface of the first segment facing away from the hot segment element, and the diameter of the second segment is smaller than that of the hot segment element.

[0033] In some embodiments, two temperature measuring holes are opened between adjacent positioning holes, and the temperature measuring holes are used to accommodate a temperature measuring device.

[0034] In some embodiments, a blind hole is opened on the element rod along the extension direction of the element rod, and the temperature measuring device is arranged in the blind hole.

[0035] In some embodiments, it also includes a protective sleeve disposed at the end of the element rod close to the first conductive component, and the portion of the element rod located outside the protective sleeve is placed in a low-temperature medium.

[0036] In a third aspect, the present application provides a simulation experiment method for a nuclear reactor, using any one of the thermal hydraulic experiment systems in the first aspect, including using the thermal hydraulic experiment system of the second aspect, the thermal hydraulic experiment system including a pressure measuring device arranged on one side of the cylinder, the pressure measuring device is used to measure the pressure data of the thermal hydraulic experiment device, the thermal hydraulic experiment system also includes a temperature measuring device, the temperature measuring device includes a guide tube passing through the first conductive component into the cylinder and a thermocouple arranged in the guide tube for measuring the temperature data of the thermal hydraulic experiment system, including:

[0037] S1: Start the thermal hydraulic test system, increase the temperature and pressure of the thermal hydraulic test system, and conduct a thermal balance test of the thermal hydraulic test system until the thermal balance of the thermal hydraulic test system is greater than or equal to 95%;

[0038] S2: Collect thermal parameters of the thermal hydraulic experimental system as control group information;

[0039] S3: changing the state of the thermal hydraulic experiment system and collecting the thermal parameters of the thermal hydraulic experiment system as the experimental group information;

[0040] S4: Analyze the control group information and the experimental group information to obtain the reactor heat transfer characteristic information and the reactor medium flow characteristic information.

[0041] In some embodiments, S1 includes: a heating rate of the thermal hydraulic experiment system is less than or equal to 4°C / s.

[0042] In some embodiments, S4 includes: determining whether the medium in the thermal hydraulic experiment system is a single-phase medium by using formula (5).

[0043]

[0044] Where Z ONBis the starting point of subcooled boiling of the medium in the thermal hydraulic experimental system, G is the mass flow rate of the medium in the thermal hydraulic experimental system, D is the hydraulic equivalent diameter of the thermal hydraulic experimental system, Cp i is the constant pressure specific volume of the medium in the thermal hydraulic experimental system, q is the heat flux density of the thermal hydraulic experimental system, (ΔT sub ) in is the inlet subcooling of the thermal hydraulic experimental system, (ΔT sat ) ONB is the saturation temperature of the subcooled boiling starting point of the thermal hydraulic experimental system, h spi is the heat transfer coefficient of the thermal-hydraulic experimental system.

[0045] In some embodiments, S3 includes: increasing the heating power of the thermal-hydraulic experimental system; S4 includes: when the temperature difference of the equivalent component or the wall temperature difference of the element rod fluctuates continuously and stably and the amplitude of the fluctuation is greater than 5%, it is determined that flow instability occurs in the thermal-hydraulic experimental system.

[0046] In some embodiments, S3 includes: increasing the heating power of the thermal-hydraulic experimental system; S4 includes: when the temperature difference of the equivalent components or the temperature increase of the wall of the element rod is greater than 5°C / s, it is determined that boiling critical phenomenon occurs in the thermal-hydraulic experimental system.

[0047] An embodiment of the present application provides an equivalent component design method for a core fuel assembly, which obtains actual parameters of a first fuel assembly in the core and obtains simulation parameters of a second fuel assembly that is arranged in different arrangements and is an equivalent model device to the core, compares the simulation parameters and actual parameters of the second fuel assemblies in different arrangements, and selects the second fuel assembly and its arrangement method with simulation parameters closest to the actual parameters of the first fuel assembly as the equivalent component of the first fuel assembly. Because the actual parameters and the simulation parameters are similar, the influence of the "side wall effect" and the "cold wall effect" on the second fuel assembly is reduced, and the second fuel assembly has good representativeness.

[0048] An embodiment of the present application provides a thermal-hydraulic experimental system for a core, the thermal-hydraulic experimental system comprising an equivalent component designed according to the equivalent component design method of the first aspect mentioned above, used to simulate a fuel assembly, a thermal-hydraulic experimental device for collecting thermal-hydraulic experimental data, the thermal-hydraulic experimental device comprising a pressure-bearing component for bearing internal and external pressures, an electric heating component for heating the equivalent component, an insulating component for insulating the electric heating component and the pressure-bearing component, and a sealing component for sealing the simulation test system, wherein the pressure-bearing component, the electric heating component, the sealing component and the insulating component are detachably connected together, the thermal-hydraulic experimental system is reasonably designed, easy to use, and highly compatible, and can be well adapted to different thermal-hydraulic experiments.

[0049] The embodiment of the present application provides a simulation experiment method for a nuclear reactor, comprising a thermal-hydraulic experiment system of any embodiment of the second aspect above, the thermal-hydraulic experiment system comprising a pressure measuring device arranged on one side of a cylinder, the pressure measuring device being used to measure pressure data of the thermal-hydraulic experiment system, the thermal-hydraulic experiment system also comprising a temperature measuring device, the temperature measuring device comprising a guide tube passing through a first conductive component and entering the cylinder, and a thermocouple arranged in the guide tube for measuring temperature data of the thermal-hydraulic experiment system, the thermal-hydraulic experiment method comprising starting the thermal-hydraulic experiment system, raising the temperature and pressure of the thermal-hydraulic experiment system, conducting a thermal balance experiment of the thermal-hydraulic experiment system, and finally The thermal balance of the hydraulic experiment system is greater than or equal to 95%, which reduces the problem of reduced accuracy of thermal-hydraulic experiment results caused by excessive heat dissipation of the device; during the experimental stage, the thermal parameters of the thermal-hydraulic experiment system are collected as the control group information, the system state of the thermal-hydraulic experiment device is changed, the thermal parameters of the thermal-hydraulic experiment system are collected as the control group information, the system state of the thermal-hydraulic experiment system is changed, the thermal parameters of the thermal-hydraulic experiment system are collected as the experimental group information, the control group information and the experimental group information are analyzed, and the heat transfer characteristic information of the reactor and the medium flow characteristic information of the reactor are obtained for more accurate structural design and safety analysis of reactor components. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0051] Figure 1 A schematic diagram of a flow chart of an equivalent component design method provided in one embodiment of the present application;

[0052] Figure 2 A schematic diagram of a structure in which a second fuel assembly provided in an embodiment of the present application is arranged in different ways;

[0053] Figure 3 A schematic diagram of a flow chart of an equivalent component design method provided by another embodiment of the present application;

[0054] Figure 4 A schematic diagram of a flow chart of an equivalent component design method provided in yet another embodiment of the present application;

[0055] Figure 5 A schematic diagram of the thermal hydraulic experiment system structure provided in the embodiment of the present application;

[0056] Figure 6 A schematic diagram of the structure of the spacer grid provided in the embodiment of the present application;

[0057] Figure 7 A schematic diagram of the structure of a pressure measuring device provided in an embodiment of the present application;

[0058] Figure 8 A schematic diagram of the structure of a thermal hydraulic experiment system provided in another embodiment of the present application;

[0059] Fig. 9 A schematic diagram of the structure of a temperature measuring device provided in an embodiment of the present application;

[0060] Fig.10 A schematic diagram of the structure of the element rod provided in the embodiment of the present application;

[0061] Fig.11 A schematic diagram of the structure of another element rod provided in an embodiment of the present application;

[0062] Fig.12 for Figure 6 A schematic diagram of the enlarged structure at A in the middle;

[0063] Fig.13 A schematic diagram of the structure of a temperature measuring device provided in another embodiment of the present application;

[0064] Fig.14 A schematic flow chart of a simulation experimental method for a nuclear reactor provided in one embodiment of the present application.

[0065] The reference numerals in the specific implementation manner are as follows:

[0066] 100. Thermal hydraulic experimental system; 200. Second fuel assembly;

[0067] 1. Thermal hydraulic experimental device; 2. Equivalent components; 3. Pressure measuring device; 4. Temperature measuring device; 5. Pressure bearing component; 6. Electric heating component; 7. Insulation component; 8. Sealing component; 9. Positioning grid;

[0068] 21. Component rod;

[0069] 31. O-type sealing ring; 32. Pressure-leading pipeline; 33. Sealing ring; 34. Pressure-leading nozzle; 35. Second compression nut; 36. Pressure-leading nozzle; 37. Sealing ring seat;

[0070] 41. Thermocouple; 42. Guide tube; 43. First cold section element; 44. Second cold section element; 45. Hot section element; 431. First section; 432. Second section; 46. Insulating sleeve; 47. Blind hole; 48. Protective sleeve;

[0071] 51. Upper cylinder; 52. Lower cylinder; 53. Upper groove surface flange; 54. Lower groove surface flange; 55. Inlet pipe; 56. Outlet pipe; 57. Lower tenon surface flange; 58. Upper flange cover; 59. Support assembly;

[0072] 61. upper conductive plate; 62. upper conductive copper plate; 63. lower conductive component; 64. lower conductive copper head; 65. copper braid; 66. lower conductive connector; 67. first conductive component; 68. second conductive component;

[0073] 71. Insulating gasket; 72. Insulating sheet;

[0074] 81. first compression nut; 82. compression ring; 83. sealing ring; 84. upper end fastening assembly; 85. lower end fastening assembly;

[0075] 91. Positioning hole; 92. Temperature measuring hole; 93. Rib. DETAILED DESCRIPTION

[0076] The following embodiments of the technical solution of the present application will be described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0077] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the embodiments of the present application should have the common meanings understood by technicians in the field to which the embodiments of the present application belong.

[0078] Reactor fuel assembly simulation characteristics are an important research content of fuel assembly performance. The research on the simulation characteristics of fuel assemblies is of great significance to the design demonstration of fuel assemblies and improving the comprehensive performance of assemblies. In order to improve the performance of core fuel assemblies and optimize their design, various countries have carried out simulation analysis and experimental research on this.

[0079] The inventors found that due to the particularity of reactor fuel assemblies, it is impossible to conduct off-pile experiments directly. Therefore, it is necessary to invent a method for determining typical grid elements of the equivalent structure of fuel assemblies.

[0080] Based on the above problems discovered by the inventors, in order to design an equivalent component that can effectively reduce the influence of the "cold wall effect" and the "side wall effect" and has good representativeness and economy, the inventors designed an equivalent component design method for core fuel assemblies.

[0081] See also Figure 1 and Figure 2 , Figure 1 A flowchart of an equivalent component design method provided in an embodiment of the present application is shown in FIG. Figure 2 This is a schematic diagram of the structure of the second fuel assembly 200 provided in one embodiment of the present application arranged in different ways.

[0082] In some optional embodiments, for example Figure 1 and Figure 2As shown, an equivalent assembly design method for a core fuel assembly includes:

[0083] S01: Acquire actual parameters of a first fuel assembly in a core, where the actual parameters include at least one of actual temperature characteristic information and actual flow characteristic information.

[0084] S02: Acquire simulation parameters of the second fuel assembly 200 arranged in different arrangements in an equivalent model device, the simulation parameters including at least one of simulated temperature characteristic information and simulated flow characteristic information, the simulation parameters correspond to actual parameters, the equivalent model device is an equivalent model of the core, the second fuel assembly 200 is composed of n element rods, n>0, and the gaps between the element rods form channels.

[0085] S03: Determine that the second fuel assembly 200 having simulation parameters closest to the actual parameters and its corresponding arrangement are equivalent assemblies of the first fuel assembly.

[0086] The first fuel assembly refers to the fuel assembly in the core, and the second fuel assembly 200 is an equivalent assembly of the first fuel assembly. The second fuel assembly 200 is arranged in a different manner. Figure 2 2 shows the second fuel assembly 200 arranged in three different ways. The different arrangements include using different numbers of element rods, which are substitutes for fuel rods, and using the element rods to arrange into different three-dimensional structures.

[0087] The rod bundle structure is widely used in the design of fuel assemblies for water-cooled reactors. A typical pressurized water reactor fuel assembly consists of a number of fuel rods, which are arranged in a certain manner and positioned in the assembly by a grid. Due to the presence of guide tubes, the fuel assembly contains two characteristic grid elements: typical grid elements (all composed of fuel rods) and guide tube grid elements (composed of fuel rods and guide tubes). When the reactor is running, the cold wall effect caused by the lack of heat in the guide tubes will make the simulated characteristics of the guide tube grid elements significantly different from those of the typical grid elements. In the present application, by screening out the second fuel assembly 200 and its arrangement method with the simulated temperature characteristic information closest to the actual temperature characteristic information of the first fuel assembly during the design process as an equivalent assembly of the first fuel assembly, the influence of the cold wall effect in the design process of the equivalent assembly can be effectively reduced, and the representativeness of the equivalent assembly can be improved.

[0088] In the equivalent component design method provided in the embodiment of the present application, the actual parameters of the first fuel assembly in the core are obtained, and the simulation parameters of the second fuel assembly 200 which is arranged in different arrangements and is equivalent to the core model device are obtained, the simulation parameters and actual parameters of the second fuel assemblies 200 with different arrangements are compared, and the second fuel assembly 200 and its arrangement with the simulation parameters closest to the actual parameters of the first fuel assembly are screened out as the equivalent assembly of the first fuel assembly. Because the actual temperature characteristic information and the simulated temperature characteristic information are similar, the influence of the "cold wall effect" and the "side wall effect" on the second fuel assembly 200 is reduced, making the second fuel assembly 200 well representative.

[0089] In the technical solutions of some optional embodiments, the second fuel assembly includes n element rods, n≤100, and the first fuel assembly is a closely arranged fuel assembly arranged side by side.

[0090] The second fuel assembly includes a structure composed of a plurality of different numbers of element rods. Optionally, the second fuel assembly includes different rod bundle sizes such as 3 element rods, 7 element rods, 19 element rods, and 37 element rods.

[0091] The first fuel assembly is a closely arranged fuel assembly arranged side by side, which means that the first fuel assembly adopts a dense arrangement of fuel elements to form a honeycomb core in which the fuel elements are arranged in triangles and hexagons. The dense grid fuel assembly reduces the spacing between the fuel element grids, reduces the core volume, improves the core conversion ratio, and increases the burnup depth, thereby achieving the purpose of extending the burnup life, realizing long cycle operation, and effectively utilizing uranium resources.

[0092] In these optional embodiments, the second fuel assembly includes different cases of n element rods, which improves the accuracy of the equivalent assembly design method.

[0093] In the technical solutions of some optional embodiments, before step S03, the following steps are further included:

[0094] Selecting the second fuel assemblies that meet the pressure drop deviation range and the temperature drop deviation range specified by formula (1) and formula (2) as the first target group;

[0095]

[0096] Where Δp is the average pressure drop in the channel; T h is the average outlet temperature of the channel; i is the number of element rods in the second fuel assembly.

[0097] Then in step S03, the second fuel assembly having simulation parameters closest to the actual parameters in the first target group and its corresponding arrangement are determined as equivalent assemblies of the first fuel assembly.

[0098] In these optional embodiments, the second fuel assembly that meets the pressure drop deviation range and temperature drop deviation range specified by formula (1) (2) is further screened out as the first target group, and the second fuel assembly with simulation parameters closest to the actual parameters and its corresponding arrangement are screened out in the first target group as the equivalent assembly of the first fuel assembly, thereby improving the simplicity and accuracy of the equivalent assembly design process.

[0099] See also Figure 3 , Figure 3 A flowchart of an equivalent component design method provided in yet another embodiment of the present application.

[0100] In some optional embodiments, for example Figure 3 As shown, before step S03, it also includes:

[0101] S011: Acquire first actual parameters of the first fuel assembly in the core, the first actual parameters including at least one of actual geometric characteristic parameters, actual resistance characteristics, actual flow distribution state, actual outlet temperature distribution and actual heat transfer coefficient.

[0102] S012: Obtain first simulation parameters of a second fuel assembly arranged in an equivalent model device in different arrangements, the first simulation parameters including at least one of simulated geometric characteristic parameters, simulated resistance characteristics, simulated flow distribution state, simulated outlet temperature distribution and simulated heat transfer coefficient, and the first simulation information corresponds to the first actual information.

[0103] Then in step S03, the second fuel assembly in the first target group whose simulation parameters are closest to the actual parameters and its corresponding arrangement are determined to be equivalent to the first fuel assembly, and the second fuel assembly in the first target group is subjected to fluid dynamics numerical simulation calculation and analysis; the second fuel assembly in the first target group whose first simulation parameters are closest to the first actual parameters and its corresponding arrangement are determined to be equivalent to the first fuel assembly.

[0104] The correspondence between the first simulation information and the first actual information means that the first simulation information and the first actual information are essentially the same. For example, when the first actual information is actual geometric characteristic parameters, the corresponding first simulation information is simulated geometric characteristic parameters. Similarly, when the first actual information is actual resistance characteristics, the corresponding first simulation information is simulated resistance characteristics. When the first actual information is actual flow distribution state, the corresponding first simulation information is simulated flow distribution state.

[0105] In these optional embodiments, the first actual parameters and the first simulation parameters of the first fuel assembly and the second fuel assembly are obtained, and the second fuel assemblies in the first target group are further screened out to find the second fuel assemblies with the first simulation parameters closest to the first actual parameters and their corresponding arrangements as equivalent assemblies to the first fuel assemblies. This improves the simplicity of the equivalent assembly design method and reduces the time for obtaining information on the first fuel assembly and the second fuel assembly; and improves the accuracy of the equivalent assembly design method by introducing two evaluation units, the first actual parameter and the first simulation parameter.

[0106] In the technical solutions of some optional embodiments, the first fuel assembly is a spherical fuel assembly, and the second fuel assembly has a porous structure.

[0107] The spherical fuel assembly includes a shell without fuel and a core containing fuel covered by the shell, wherein the core is seamlessly connected to the shell to form an integral unit, wherein the fuel is uniformly distributed in the core of the sphere in the form of coated fuel particles or fuel microspheres.

[0108] In these optional embodiments, the first fuel assembly is a spherical fuel assembly, and the second fuel assembly has a porous structure similar to that of the first fuel assembly, thereby improving the accuracy of the equivalent assembly design method.

[0109] See also Figure 4 , Figure 4 A flowchart of an equivalent component design method provided in yet another embodiment of the present application.

[0110] In some optional embodiments, for example Figure 4 As shown, before step S03, it also includes:

[0111] S021: Obtaining a second actual parameter of the first fuel assembly in the core, the second actual parameter comprising at least one of an actual volume porosity, an actual hydraulic equivalent diameter, and an actual specific surface area.

[0112] S022: Obtain second simulation parameters of a second fuel assembly arranged in an equivalent model device in a different arrangement, the second simulation parameters including at least one of a simulated volume porosity, a simulated hydraulic equivalent diameter and a simulated specific surface area, and the second simulation parameters correspond to the first simulation parameters.

[0113] S023: Select the second fuel assembly with the second simulation parameter whose deviation from the first actual parameter is less than or equal to 15% as the second target group.

[0114] In step S03, the second fuel assembly having the second simulation parameter closest to the second actual parameter in the second target group and its corresponding arrangement are determined as equivalent assemblies of the first fuel assembly.

[0115] The actual hydraulic equivalent, i.e., the actual specific surface area, can be obtained by formulas (11) and (12):

[0116]

[0117] Among them, de is the actual hydraulic equivalent diameter, ε is the actual volume porosity, ds is the actual sphere diameter, and Ω is the actual specific surface area.

[0118] The correspondence between the second simulation parameter and the second actual parameter means that the second simulation information and the second actual information are essentially the same. For example, when the second actual information is the actual volume porosity, the corresponding second simulation information is the simulated volume porosity. Similarly, when the second actual parameter is the actual hydraulic equivalent diameter, the corresponding second simulation information is the simulated hydraulic equivalent diameter. When the second actual information is the specific surface area, the corresponding second simulation information is the simulated specific surface area.

[0119] In these optional embodiments, the second actual parameters and the second simulation parameters of the first fuel assembly and the second fuel assembly are obtained, and the second target group is screened out by the second actual parameters and the second simulation parameters. The second fuel assembly with the second simulation parameter close to the second actual parameter and the corresponding arrangement mode are further screened out in the second target group as the equivalent assembly of the first fuel assembly. By introducing the two evaluation units of the second actual parameter and the second simulation parameter, the principle of similar geometric structures of the first fuel assembly and the second fuel assembly is met, and the accuracy of the equivalent assembly design method is improved.

[0120] In the technical solutions of some optional embodiments, before the step of determining that the second fuel assembly with the second simulation parameter closest to the second actual parameter in the second target group and its corresponding arrangement are equivalent assemblies of the first fuel assembly, the step further includes:

[0121] The second fuel assembly that meets the heat transfer coefficient deviation range specified by formula (3) is selected from the second target group as the third target group;

[0122]

[0123] Where q is the heat flux density on the outer wall of the channel; T w (z) is the wall temperature of the channel; T f (z) is the fluid temperature.

[0124] Then, in the step of determining that the second fuel assembly in the second target group having the second simulation parameter closest to the second actual parameter and its corresponding arrangement method are equivalent components of the first fuel assembly, the second fuel assembly in the third target group having the simulated heat transfer coefficient information closest to the actual heat transfer coefficient information and its corresponding arrangement method are equivalent components of the first fuel assembly.

[0125] In these optional embodiments, the second fuel assembly that meets the formula (3) is selected from the second target group to form the third target group, and the second fuel assembly having the simulated heat transfer coefficient information closest to the actual heat transfer coefficient information and the corresponding arrangement mode are further selected from the third target group as the equivalent assembly of the first fuel assembly. By introducing the evaluation unit of the heat transfer coefficient, the accuracy of the equivalent assembly design method is further improved.

[0126] In the technical solutions of some optional embodiments, before the step of determining that the second fuel assembly with the second simulation parameter closest to the second actual parameter in the second target group and its corresponding arrangement are equivalent assemblies of the first fuel assembly, it also includes.

[0127] The second fuel assembly that meets the pressure drop deviation range specified by formula (4) is selected from the second target group as the fourth target group.

[0128]

[0129] Wherein, Δp is the average pressure drop of the channel; i is the number of element rods in the second fuel assembly.

[0130] Then, in the step of determining the second fuel assembly in the second target group whose second simulation parameter is closest to the second actual parameter and its corresponding arrangement method as an equivalent assembly of the first fuel assembly, determine the second fuel assembly in the fourth target group whose simulated pressure drop information is closest to the actual pressure drop information and its corresponding arrangement method as an equivalent assembly of the first fuel assembly.

[0131] In these optional embodiments, the second fuel assembly that meets the formula (4) is selected from the second target group to form a third target group, and the second fuel assembly with simulated pressure drop information closest to the actual pressure drop information and its corresponding arrangement mode are further selected from the third target group as an equivalent assembly of the first fuel assembly. By introducing the pressure drop evaluation unit, the accuracy of the equivalent assembly design method is further improved.

[0132] See also Figure 5 , Figure 5 A schematic diagram of the structure of a thermal hydraulic experiment system 100 provided in an embodiment of the present application.

[0133] The present application also provides a thermal hydraulic experiment system. Figure 5As shown, the thermal-hydraulic experimental system includes a thermal-hydraulic experimental device 1 and an equivalent component 2 designed according to the equivalent component design method provided in the above embodiment. The thermal-hydraulic experimental device 1 is used to collect experimental data of thermal-hydraulic experiments applied to nuclear reactors. The thermal-hydraulic experimental device 1 includes a pressure-bearing component 5, an electric heating component 6, an insulating component 7 and a sealing component 8. The pressure-bearing component 5 includes a cylinder extending along a first direction X; the electric heating component 6 includes an equivalent component 2 located in the cylinder, the equivalent component 2 includes at least one element rod 21 with an annular rib, and a first conductive component 67 and a second conductive component 68 are connected at both ends of the cylinder, and the equivalent component 2 is electrically connected to the first conductive component 67 and the second conductive component 68; the insulating component 7 is located between the cylinder and the equivalent component 2; the sealing component 8 is arranged at one end of the cylinder close to the second conductive component 68, and is used to achieve the sealing of the thermal-hydraulic experimental device 1, wherein the pressure-bearing component 5, the electric heating component 6, the insulating component 7 and the sealing component 8 are detachably assembled together.

[0134] Optionally, the pressure-bearing component 5 includes an upper cylinder 51 and a lower cylinder 52, the electric heating component 6 includes an equivalent component 2 and a first conductive component 67 and a second conductive component 68, the first conductive component 67 includes an upper conductive copper disc 62 and an upper conductive plate 61, and the second conductive component 68 includes a lower conductive joint 66, a lower conductive component 63, a lower conductive copper head 64 and a copper braid 65. The insulating component 7 includes an insulating sheet 72. The sealing component 8 includes a sealing ring 83, a clamping ring 82 and a first clamping nut 81.

[0135] The specific connection relationship of each part is as follows: the upper cylinder 51 is a cavity structure with two upper and lower open ends, and its internal cavity forms a cylindrical structure. An upper groove surface flange 53 is arranged at the upper open end of the upper cylinder 51. The upper cylinder 51 and the upper groove surface flange 53 are welded together. An upper conductive copper disk 62 is arranged on the end surface of the upper groove surface flange 53. The upper groove surface flange 53 and the upper conductive copper disk 62 are provided with insulating gaskets 71. An outlet pipe 56 is arranged on the side of the upper groove surface flange 53. An upper conductive plate 61 is installed on the upper conductive copper disk 62. An upper flange cover 58 is placed on the upper end of the upper conductive plate 61. The upper flange cover 58 is connected to the upper groove surface flange 53 through an upper end fastening component 84, and the upper conductive plate 61 and the upper conductive copper disk 62 are clamped between the upper flange cover 58 and the upper groove surface flange 53.

[0136] A lower tenon flange 57 is installed at the lower open end of the upper cylinder 51, an inlet pipe 55 is arranged on the side of the lower tenon flange 57, and a lower groove flange 54 is connected to the lower end of the lower tenon flange 57. The lower tenon flange 57 and the lower groove flange 54 are connected by a lower end fastening component 85, and the lower cylinder 52 is welded to the lower end of the lower groove flange 54; a lower conductive joint 66 is installed in the lower groove flange 54, and the lower conductive joint 66 is cylindrical as a whole, with one end open and the other end closed, and a cylinder is mounted inside it, and the cylinder is connected to the closed end surface inside it; a plurality of element rods 21 with annular ribs are installed between the upper conductive copper disk 62 and the lower conductive joint 66, and the element rods 21 with annular ribs are made of stainless steel and are provided with evenly distributed annular ribs. The upper end of the equivalent component 2 is inserted into the upper conductive copper disk 62. The upper end of the equivalent component 2 with annular fins passes through the positioning grid 9. The positioning grid 9 is in the shape of a circular plate as a whole, with one end being a plane and the other end protruding outward to form a cone. A plurality of positioning holes 91 are provided on the positioning grid. The positioning holes 91 connect the two end faces of the positioning grid 9 and are parallel to each other. The element rod 21 with annular fins is guided by the cone surface of the positioning grid 9 and penetrates into the positioning holes 91. The penetration sequence is from the center to the surroundings. When one end of the equivalent component 2 is completely penetrated into the positioning grid, the above process is repeated for the other end. After both ends are penetrated, one end of the equivalent component 2 is calibrated and flushed to ensure the uniformity of the fin arrangement in the axial direction. The upper end of the equivalent component 2 is inserted into the upper conductive copper disk for silver brazing, and the lower end is placed as a whole in the cylinder of the lower conductive joint 66 for silver brazing.

[0137] A lower conductive component 63 is installed inside the lower cylinder 52, and the lower conductive component 63 and the lower conductive joint 66 are softly connected through a copper braid 65; the lower conductive component 63 is connected to a clamping ring 82, which passes through the end surface of the lower cylinder 52, and the two ends of the clamping ring 82 are respectively connected to the lower conductive component 63 and the lower conductive copper head 64, and a through hole is opened on the lower cylinder 52, and the clamping ring 82 cooperates with the lower cylinder 52 to seal, and a sealing ring is provided on the side wall of the through hole of the lower cylinder 52 83, a first clamping nut 81 for clamping the sealing ring 83 is provided on one side of the sealing ring; a support assembly 59 is provided on the outer surface of the upper cylinder 51 and / or the lower cylinder 52; an insulating assembly 7 is installed inside the upper cylinder 51, and the insulating assembly 7 is a regular hexagonal structure composed of 6 ceramic or quartz glass insulating sheets 72 of the same specifications, and the cross-section of the insulating sheet 72 is an isosceles trapezoid. The 6 insulating sheets 72 are connected to form a cavity structure with regular hexagonal columns inside and outside, and the inside of the cavity is a chamber.

[0138] In some embodiments, the thermal-hydraulic experiment system 100 includes an equivalent component 2 designed according to the equivalent component 2 design method of the first aspect above, which is used to simulate a fuel assembly, and a thermal-hydraulic experiment device 1 is used to collect thermal-hydraulic experiment data. The thermal-hydraulic experiment device 1 includes a pressure-bearing component 5 for bearing internal and external pressures, an electric heating component 6 for heating the equivalent component 2, and an insulating component 7 for insulating the electric heating component 6 and the pressure-bearing component 5, and a sealing component 8 for sealing the simulation test system, wherein the pressure-bearing component 5, the electric heating component 6, the sealing component 8 and the insulating component 7 are detachably connected together. The thermal-hydraulic experiment system 100 is reasonably designed, easy to use, and highly compatible, and can be well adapted to different thermal-hydraulic experiments.

[0139] In the technical solutions of some optional embodiments, the equivalent component 2 is a rod bundle including 19 element rods 21, and the rod bundle is arranged with a first layer, a second layer and a third layer from the center to the edge, the first layer is arranged with 1 element rod 21; the second layer is arranged with 6 element rods 21 surrounding the first layer; the third layer is arranged with 12 element rods 21 surrounding the second layer.

[0140] In these optional embodiments, the equivalent assembly 2 is a rod bundle including 19 element rods 21. On the one hand, it can improve the problem that when the scale is large, the number of element rods 21 of the equivalent assembly 2 is large, which makes the structure of the experimental system complicated, increases the difficulty of experimental system design and measurement point arrangement, and increases the experimental cost. On the other hand, it can improve the problem that when the scale of the element rods 21 is small, the "cold wall effect" and "side wall effect" are increased, which have an increased impact on the thermal-hydraulic characteristics of the fuel assembly and cannot well reflect the thermal-hydraulic performance of the prototype core assembly.

[0141] See also Figure 6 , Figure 6 A schematic diagram of the structure of a positioning grid provided in an embodiment of the present application.

[0142] In some optional embodiments, for example Figure 6 As shown, a positioning grid 9 is provided in the cylinder, and 19 positioning holes 91 are opened on the positioning grid 9. An element rod 21 is arranged in each positioning hole 91.

[0143] Optionally, the spacer grid 9 has a thickness of 0.5 mm and a material of 0Cr18Ni10Ti.

[0144] In these optional embodiments, the spacer grid 9 is used to provide positioning for the element rod 21.

[0145] In the technical solutions of some optional embodiments, the positioning hole 91 is a plum blossom hole, and at least one rib 93 is arranged in the plum blossom hole.

[0146] Optionally, the rib 93 has a thickness of 0.25 mm.

[0147] Optionally, the arc diameter of the plum blossom hole is 0.75 mm.

[0148] In these optional embodiments, the positioning hole 91 is a plum blossom hole, which can provide a better limiting effect for the element rod 21.

[0149] See also Figure 7 , Figure 7 A schematic diagram of the structure of a pressure measuring device provided in an embodiment of the present application.

[0150] In some optional embodiments, for example Figure 6 and Figure 7 As shown, the thermal hydraulic experiment system further includes a pressure measuring device 3 arranged on one side of the cylinder, the pressure measuring device 3 includes a pressure-leading pipeline 32, the pressure-leading pipeline 32 is connected to the cylinder, and the pressure measuring device 3 is used to measure the pressure data of the thermal hydraulic experiment device 1.

[0151] The pressure measuring device 3 is located on the side wall of the upper cylinder 51, and an opening is provided on one of the insulating sheets 72. The opening penetrates the insulating sheet 72 and extends through the side wall of the upper cylinder 51 to connect the chamber with the outside of the upper cylinder 51. The pressure measuring device 3 is connected to the side wall of the upper cylinder 51 at the position of the opening. The pressure measuring device 3 includes a pressure lead nozzle 36. The pressure lead nozzle 36 is cylindrical as a whole, and its end is connected to a second clamping nut 35 by threading. The second clamping nut 35 has an opening on the axis. A pressure lead nozzle 34 is installed between the second clamping nut 35 and the top of the pressure lead nozzle 36, and a sealing ring 33 is also provided between the pressure lead nozzle 34 and the end surface of the pressure lead nozzle 36; a pressure lead pipeline 32 is installed in the pressure lead nozzle 34, the end of the pressure lead pipeline 32 is located in the hole of the insulating sheet 72, and a sealing ring seat 37 is mounted thereon, and a groove is provided on the sealing ring seat 37, and an O-ring 31 is installed in the groove.

[0152] In these optional embodiments, the thermal-hydraulic experiment system further includes a pressure measuring device 3, which is used to measure pressure data of the thermal-hydraulic experiment device 1, so that the thermal-hydraulic experiment system can adapt to a variety of different experimental contents, thereby improving the compatibility of the thermal-hydraulic experiment system.

[0153] See also Figure 8 and Fig. 9 , Figure 8 This is a schematic diagram of the structure of the thermal hydraulic experiment system 100 provided in the embodiment of the present application. Fig. 9 This is a schematic diagram of the structure of the temperature measuring device 4 provided in an embodiment of the present application.

[0154] In some optional embodiments, for example Figure 8 and Fig. 9As shown, the thermal-hydraulic experimental system 100 also includes a temperature measuring device 4, which includes a guide tube 42 and a thermocouple 41. The guide tube 42 passes through the first conductive component 67 and enters the cylinder; the thermocouple 41 is arranged in the guide tube 42 to measure the temperature data of the thermal-hydraulic experimental system 100.

[0155] Optionally, the thermocouple 41 is a Φ0.8 mm N-type armored thermocouple with a bottom insulation, and the thermocouple 41 is directly inserted into the guide tube 42 for temperature measurement, so that the thermocouple 41 can be easily disassembled and assembled.

[0156] Optionally, since the outer shell of the thermocouple 41 is charged, the tail of the thermocouple 41 and the compensation wire are ensured to be suspended in the test to prevent the negative pole of the thermocouple 41 from being connected to the ground.

[0157] Optionally, the guide tube 42 is made of a Φ1.5×0.2 mm stainless steel tube, the bottom of which is sealed by argon arc welding with a penetration depth of 1.5 mm to 2.0 mm.

[0158] Optionally, the distance between the bottom end of the guide tube 42 and the second conductive component 68 is no more than 15 mm.

[0159] In these optional embodiments, the thermal-hydraulic experimental system 100 further includes a temperature measuring device 4, which is used to measure the temperature data of the thermal-hydraulic experimental system 1, so that the thermal-hydraulic experimental system 100 can adapt to a variety of different experimental schemes, thereby improving the compatibility of the thermal-hydraulic experimental system 100.

[0160] See also Fig.10 and Fig.11 , Fig.10 This is a schematic diagram of the structure of the element rod provided in the embodiment of the present application. Fig.11 A schematic diagram of the structure of another element rod provided in an embodiment of the present application.

[0161] In some optional embodiments, for example Fig.10 and Fig.11 As shown, the element rod 21 includes a first cold segment element 43, a hot segment element 45 and a second cold segment element 44 arranged along a first direction X. The first cold segment element 43 is welded to the hot segment element 45, and the hot segment element 45 is welded to the second cold segment element 44.

[0162] Optionally, the first cold segment element 43 and the second cold segment element 44 are copper rods, and the hot segment element 45 is a stainless steel rod or a stainless steel tube.

[0163] In these optional embodiments, the element rod 21 is divided into sections, the two ends of the element rod 21 are used as conductive ends, and the element rod 21 itself is connected in series in the corresponding circuit, and is configured to include a first cold section element 43, a hot section element 45 and a second cold section element 44. During use, since the resistance of the cold section element is smaller than that of the hot section element 45, when the element rod 21 is working, the first cold section element 43 and the second cold section element 44 can be understood as only serving as conductor segments, and the hot section element 45 is used to generate heat. At the same time, the position where the element rod 21 releases heat in the flow channel is closer to the position of the fuel assembly in a first loop when the reactor is working, thereby achieving accurate simulation of the heat release of the element rod 21, so as to facilitate accurate thermal-hydraulic experimental research.

[0164] In some optional embodiments, for example Fig.10 and Fig.11 As shown, the first cold segment element 43 includes a first segment 431 and a second segment 432 connected to each other, the first segment 431 is connected to the hot segment element 45, the diameter of the first segment 431 is the same as that of the hot segment element 45, and the second segment 432 is connected to the surface of the first segment 431 away from the hot segment element 45, and the diameter of the second segment 432 is smaller than that of the hot segment element 45.

[0165] Optionally, the first section 431 is a H96 rod with an outer diameter of Φ4 mm, and the second section 432 is a T2 rod with an outer diameter of Φ6 mm.

[0166] In these optional embodiments, the first cold section element 43 is necked, which ensures the overall strength of the element rod 21 and facilitates the insertion of the temperature measuring component, thereby facilitating the temperature measurement step in the thermal hydraulic experiment.

[0167] See also Fig.12 , Fig.12 for Figure 6 Schematic diagram of the enlarged structure at point A in the middle.

[0168] In some optional embodiments, for example Fig.12 As shown, two temperature measuring holes 92 are provided between adjacent positioning holes 91 , and the temperature measuring holes 92 are used to accommodate a temperature measuring device.

[0169] Optionally, 36 circular holes with a diameter of Φ1.5 mm are opened on the spacer grid 9 as temperature measuring holes 92 .

[0170] In these optional embodiments, a temperature measuring hole 92 is provided on the positioning grid 9 to serve to position the temperature measuring device.

[0171] See also Fig.13 , Fig.13 This is a schematic structural diagram of a temperature measuring device 4 provided in another embodiment of the present application.

[0172] In some optional embodiments, for example Fig.13 As shown, a blind hole 47 is opened on the element rod 21 along the extending direction of the element rod 21 , and the temperature measuring device 4 is arranged in the blind hole 47 .

[0173] Optionally, the thermocouple 41 is a T-type thermocouple with a diameter of 0.8 mm.

[0174] Optionally, the thermocouple 41 is placed in an insulating sleeve 46, and the insulating sleeve 46 isolates the thermocouple 41 from the element rod 21. Optionally, the insulating sleeve 46 is a polytetrafluoroethylene tube with an outer diameter of 1 mm.

[0175] In these optional embodiments, the temperature measuring device 4 is disposed in the blind hole 47 of the element rod 21, and the wall temperature of the element rod 21 can be measured, so that the thermal-hydraulic experimental system can adapt to a variety of different experimental conditions, thereby improving the compatibility of the thermal-hydraulic experimental system.

[0176] In some optional embodiments, for example Fig.13 As shown, it also includes a protective sleeve 48 disposed at the end of the element rod 21 close to the first conductive component 67, and the part of the element rod 21 located outside the protective sleeve 48 is placed in a low-temperature medium.

[0177] Optionally, the thermocouple 41 is passed through the first conductive component 67 and the blind hole 47 of the element rod 21 that needs to be measured temperature in turn, and fill welding is performed from the side circular hole. After welding, the other element rods 21 are passed through the first conductive component 67, and then the other ends of all the element rods 21 are fixed on the second conductive component 68, and a protective cover 48 is added to the end of the element rod 21. The lower part of the element rod 21 is immersed in cold water as a whole, the first conductive component 67 and each element rod 21 are silver-brazed, and finally the second conductive component 68 is welded.

[0178] In these optional embodiments, part of the element rod 21 outside the protective sleeve 48 is placed in a low-temperature medium, so that the heat released by the element rod 21 is transferred to the medium, thereby improving the safety of the thermal hydraulic experimental device.

[0179] See also Fig.14 , Fig.14 A schematic flow chart of a simulation experimental method for a nuclear reactor provided in one embodiment of the present application.

[0180] The present application also provides a simulation experiment method for a nuclear reactor. Fig.14As shown, the thermal hydraulic experiment system using the above embodiment includes the thermal hydraulic experiment system using the above second embodiment, the thermal hydraulic experiment system includes a temperature measuring device arranged on one side of the cylinder, the pressure measuring device is used to measure the pressure data of the thermal hydraulic experiment device, the thermal hydraulic experiment system also includes a temperature measuring device, the temperature measuring device includes a guide tube passing through the first conductive component and entering the cylinder, and a thermocouple arranged in the guide tube for measuring the temperature data of the thermal hydraulic experiment system, and the simulation experiment method of the nuclear reactor includes:

[0181] S1: Start the thermal hydraulic experiment system, increase the temperature and pressure of the thermal hydraulic experiment system, and conduct a thermal balance experiment on the thermal hydraulic experiment system until the thermal balance of the thermal hydraulic experiment system is greater than or equal to 95%.

[0182] S2: Collect thermal parameters of the thermal hydraulic experimental system as control group information.

[0183] S3: Change the state of the thermal hydraulic experiment system and collect thermal parameters of the thermal hydraulic experiment system as experimental group information.

[0184] S4: Analyze the control group information and the experimental group information to obtain the reactor heat transfer characteristic information and the reactor medium flow characteristic information.

[0185] Thermal balance refers to the ratio of the heat absorbed by the test fluid in the test device during thermal hydraulic tests to the heating power of the test section. The larger the value, the smaller the heat dissipation of the device.

[0186] In these embodiments, the simulation experiment method includes starting the thermal-hydraulic experiment system, increasing the temperature and pressure of the thermal-hydraulic experiment system, and performing a thermal balance experiment on the thermal-hydraulic experiment system until the thermal balance of the thermal-hydraulic experiment system is greater than or equal to 95%, thereby reducing the problem of reduced accuracy of the thermal-hydraulic experiment results caused by excessive heat dissipation of the device; during the experimental stage, the thermal parameters of the thermal-hydraulic experiment system are collected as control group information, the system state of the thermal-hydraulic experiment device is changed, the thermal parameters of the thermal-hydraulic experiment system are collected as control group information, the state of the thermal-hydraulic experiment system is changed, the thermal parameters of the thermal-hydraulic experiment system are collected as experimental group information, the control group information and the experimental group information are analyzed, and the heat transfer characteristic information of the reactor and the medium flow characteristic information of the reactor are obtained for more accurate structural design and safety analysis of reactor components.

[0187] In the technical solutions of some optional embodiments, step S1 includes: the heating rate of the thermal hydraulic experimental system is less than or equal to 4° C. / s.

[0188] In these embodiments, the heating rate of the thermal hydraulic experiment system is less than or equal to 4°C / s, which improves the problem of experimental data fluctuation, reduced accuracy of experimental results and damage to experimental equipment caused by excessively high heating rate in the thermal hydraulic experiment system.

[0189] In the technical solutions of some optional embodiments, step S4 includes: determining whether the medium in the thermal hydraulic test system is a single-phase medium by formula (5).

[0190]

[0191] Where Z ONB is the starting point of subcooled boiling of the medium in the thermal hydraulic experimental system, G is the mass flow rate of the medium in the thermal hydraulic experimental system, D is the hydraulic equivalent diameter of the thermal hydraulic experimental system, Cp i is the constant pressure specific volume of the medium in the thermal hydraulic experimental system, q is the heat flux density of the thermal hydraulic experimental system, (ΔT sub ) in is the inlet subcooling of the thermal hydraulic experimental system, (ΔT sat ) ONB is the saturation temperature of the subcooled boiling starting point of the thermal hydraulic experimental system, h spi is the heat transfer coefficient of the thermal-hydraulic experimental system.

[0192] In order to accurately measure the fluid temperature in the test system, it is necessary to determine the state of the fluid in the thermal test system. The single-phase or two-phase boundary point of the channel fluid in the component is related to the position of the boiling starting point. When the length of the heating section is less than the boiling starting point, the fluid in the flow channel is considered to be single-phase, otherwise it is two-phase.

[0193] In these embodiments, the state of the fluid in the thermal hydraulic experimental system is determined by formula (5), the temperature data of the thermal hydraulic experimental system is collected, the thermal hydraulic test data is further improved, and the rationality and accuracy of the simulation experimental method are improved.

[0194] In the technical solutions of some optional embodiments, step S3 includes increasing the heating power of the thermal hydraulic experimental system.

[0195] Step S4 includes: when the temperature difference of the equivalent component or the wall temperature difference of the element rod fluctuates continuously and stably and the amplitude of the fluctuation is greater than 5%, it is determined that flow instability occurs in the thermal hydraulic experiment system.

[0196] In these embodiments, by observing the temperature difference of equivalent components in the thermal-hydraulic system or the wall temperature difference of the element rod, which fluctuates continuously and stably and the amplitude of the fluctuation, it is determined whether flow instability occurs in the thermal-hydraulic experimental system. When flow instability occurs, the experimental parameters are collected, the thermal-hydraulic test data is further improved, and the rationality and accuracy of the simulation experimental method are improved.

[0197] In some optional embodiments of the technical solutions, step S3 includes:

[0198] Increase the heating power of the thermal hydraulic experiment system;

[0199] Step S4 includes: when the temperature difference of the equivalent component or the temperature rise of the wall of the element rod is greater than 5°C / s, it is determined that the boiling critical phenomenon occurs in the simulation system.

[0200] In these embodiments, by observing the temperature difference of equivalent components in the thermal-hydraulic system or the temperature rise of the wall of the element rod, it is determined whether the boiling critical phenomenon occurs in the thermal-hydraulic system. When the boiling critical phenomenon occurs, the experimental parameters are collected to further improve the thermal-hydraulic test data, thereby improving the rationality and accuracy of the simulation experimental method.

[0201] Those skilled in the art should understand that the above embodiments are exemplary rather than restrictive. Different technical features appearing in different embodiments can be combined to achieve beneficial effects. Based on the study of the drawings, the specification and the claims, those skilled in the art should be able to understand and implement other variations of the disclosed embodiments. In the claims, the term "comprising" does not exclude other devices or steps; the indefinite article "a" does not exclude a plurality; the terms "first" and "second" are used to indicate names rather than to indicate any specific order. Any figure marks in the claims should not be understood as limiting the scope of protection. The functions of multiple parts appearing in the claims can be implemented by a single hardware or software module. The appearance of certain technical features in different dependent claims does not mean that these technical features cannot be combined to achieve beneficial effects.

Claims

1. A method for designing an equivalent assembly of a core fuel assembly, characterized in that: include: Acquiring actual parameters of the first fuel assembly in the core, the actual parameters comprising at least one of actual temperature characteristic information and actual flow characteristic information; Acquire simulation parameters of a second fuel assembly arranged in an equivalent model device in different arrangements, the simulation parameters including at least one of simulated temperature characteristic information and simulated flow characteristic information, the simulation parameters corresponding to the actual parameters, the equivalent model device being an equivalent model of the core, the second fuel assembly being composed of n element rods, n>0, and gaps between the element rods forming channels; Screening out the second fuel assemblies whose simulation parameters have a deviation from the actual parameters of less than or equal to 15% as a target group; Determine that the second fuel assembly having the simulation parameters closest to the actual parameters in the target group and its corresponding arrangement are equivalent assemblies of the first fuel assembly.

2. The equivalent component design method according to claim 1, characterized in that: In the second fuel assembly, n≤100, and the first fuel assembly is a closely arranged fuel assembly arranged side by side.

3. The equivalent component design method according to claim 2, characterized in that: The target group includes a first target group, and in the step of selecting the second fuel assembly having the simulation parameter whose deviation from the actual parameter is less than or equal to 15% as the target group, Selecting the second fuel assemblies that meet the pressure drop deviation range and the temperature drop deviation range specified by formula (1) and formula (2) as the first target group; Wherein, Δp is the average pressure drop of the channel; T h is the average outlet temperature of the channel; i is the number of element rods in the second fuel assembly.

4. The equivalent component design method according to claim 3, characterized in that: In the step of determining the second fuel assembly having the simulation parameters closest to the actual parameters in the target group and the corresponding arrangement mode thereof as an equivalent assembly of the first fuel assembly, Determine in the first target group that the second fuel assembly having the simulation parameters closest to the actual parameters and its corresponding arrangement are equivalent assemblies of the first fuel assembly.

5. The equivalent component design method according to claim 4, characterized in that: Before determining that the second fuel assembly having the simulation parameter closest to the actual parameter in the first target group and the corresponding arrangement mode thereof are equivalent assemblies of the first fuel assembly, the method further includes: Acquiring first actual parameters of the first fuel assembly in the core, the first actual parameters comprising at least one of actual geometric characteristic parameters, actual resistance characteristics, actual flow distribution state, actual outlet temperature distribution, and actual heat transfer coefficient; Acquiring first simulation parameters of second fuel assemblies arranged in different arrangements in an equivalent model device, wherein the first simulation parameters include at least one of simulated geometric characteristic parameters, simulated resistance characteristics, simulated flow distribution state, simulated outlet temperature distribution, and simulated heat transfer coefficient, and the first simulation parameters correspond to the first actual parameters; The step of determining that the second fuel assembly having the simulation parameters closest to the actual parameters in the target group and the corresponding arrangement mode thereof are equivalent assemblies of the first fuel assembly includes: performing fluid dynamics numerical simulation calculation analysis on the second fuel assembly in the first target group; Determine in the first target group that the second fuel assembly having the first simulation parameter closest to the first actual parameter and its corresponding arrangement are equivalent assemblies of the first fuel assembly.

6. The equivalent component design method according to claim 1, characterized in that: The first fuel assembly is a spherical fuel assembly, and the second fuel assembly has a porous structure.

7. The equivalent component design method according to claim 6, characterized in that: The target group includes a second target group, and in the step of selecting the second fuel assembly having the simulation parameter whose deviation from the actual parameter is less than or equal to 15% as the target group, Acquiring a second actual parameter of the first fuel assembly in the core, the second actual parameter comprising at least one of an actual volume porosity, an actual hydraulic equivalent diameter, and an actual specific surface area; Acquiring second simulation parameters of a second fuel assembly arranged in an equivalent model device in different arrangements, the second simulation parameters comprising at least one of a simulated volume porosity, a simulated hydraulic equivalent diameter, and a simulated specific surface area, the second simulation parameters corresponding to the second actual parameters; Screening out the second fuel assemblies having second simulation parameters with a deviation from the second actual parameters of less than or equal to 15% as the second target group; In the step of determining the second fuel assembly having the simulation parameters closest to the actual parameters and the corresponding arrangement thereof as an equivalent assembly of the first fuel assembly, Determine in the second target group that the second fuel assembly having the second simulation parameter closest to the second actual parameter and its corresponding arrangement are equivalent assemblies of the first fuel assembly.

8. The equivalent component design method according to claim 7, characterized in that: Before determining that the second fuel assembly having the second simulation parameter closest to the second actual parameter in the second target group and the corresponding arrangement mode are equivalent assemblies of the first fuel assembly, the method further includes: The second fuel assemblies that meet the heat transfer coefficient deviation range specified by formula (3) are selected from the second target group as the third target group; Where q is the heat flux density of the outer wall of the channel; T w (z) is the wall temperature of the channel; T f (z) is the fluid temperature; In the step of determining that the second fuel assembly and the corresponding arrangement of the second simulation parameter closest to the second actual parameter in the second target group are equivalent assemblies of the first fuel assembly, Determine that the second fuel assembly in the third target group having simulated heat transfer coefficient information closest to the actual heat transfer coefficient information and its corresponding arrangement are equivalent assemblies of the first fuel assembly.

9. The equivalent component design method according to claim 8, characterized in that: Before determining that the second fuel assembly having the second simulation parameter closest to the second actual parameter in the second target group and the corresponding arrangement mode are equivalent assemblies of the first fuel assembly, the method further includes: The second fuel assemblies that meet the pressure drop deviation range specified by formula (4) are selected from the second target group as the fourth target group. Wherein, Δp is the average pressure drop of the channel; i is the number of the element rods in the second fuel assembly; In the step of determining that the second fuel assembly and the corresponding arrangement of the second simulation parameter closest to the second actual parameter in the second target group are equivalent assemblies of the first fuel assembly, Determine that the second fuel assembly having simulated pressure drop information closest to the actual pressure drop information in the fourth target group and its corresponding arrangement are equivalent assemblies of the first fuel assembly.

10. A core thermal hydraulic experimental system, characterized in that: include: An equivalent component designed by the equivalent component design method according to any one of claims 1 to 9; The thermal hydraulic experiment device is used to collect experimental data of the thermal hydraulic experiment applied to the core, and the thermal hydraulic experiment device includes a pressure-bearing component, an electric heating component, an insulating component and a sealing component. The pressure-bearing assembly includes a cylinder extending along a first direction; The electric heating component includes the equivalent component located in the cylinder, the equivalent component includes at least one element rod with an annular fin, the first conductive component and the second conductive component are connected to both ends of the cylinder, and the equivalent component is electrically connected to the first conductive component and the second conductive component; The insulating component is located between the cylinder and the equivalent component; The sealing component is arranged at one end of the cylinder close to the second conductive component, and is used to achieve the sealing of the thermal hydraulic experimental device.

11. The thermal hydraulic test system according to claim 10, characterized in that: The equivalent assembly is a rod bundle comprising 19 element rods, and the rod bundle is arranged from the center to the edge: The first layer is provided with 1 element rod; The second layer has six element rods arranged around the first layer; The third layer is provided with 12 element rods surrounding the second layer.

12. The thermal hydraulic test system according to claim 11, characterized in that: A positioning grid is arranged in the cylinder body, and 19 positioning holes are opened on the positioning grid. One element rod is arranged in each positioning hole.

13. The thermal hydraulic test system according to claim 12, characterized in that: The positioning hole is a plum blossom hole, and at least one rib is arranged in the plum blossom hole.

14. The thermal hydraulic test system according to claim 10, characterized in that: Also includes A pressure measuring device is arranged on one side of the cylinder, the pressure measuring device comprises a pressure-leading pipeline, the pressure-leading pipeline is connected to the cylinder, and the pressure measuring device is used to measure the pressure data of the thermal hydraulic experimental device.

15. The thermal hydraulic test system according to claim 12, characterized in that: It also includes a temperature measuring device, the temperature measuring device comprising: A guide tube, passing through the first conductive component and entering the cylinder; A thermocouple is arranged in the guide tube and is used to measure the temperature data of the thermal hydraulic experimental system.

16. The thermal hydraulic test system according to claim 15, characterized in that: The element rod comprises a first cold segment element, a hot segment element and a second cold segment element arranged along a first direction, the first cold segment element is connected to the hot segment element by welding, and the hot segment element is connected to the second cold segment element by welding.

17. The thermal hydraulic test system according to claim 16, characterized in that: The first cold segment element comprises a first segment and a second segment connected to each other, the first segment is connected to the hot segment element, the diameter of the first segment is the same as that of the hot segment element, and the second segment is connected to a surface of the first segment facing away from the hot segment element, the diameter of the second segment is smaller than that of the hot segment element.

18. The thermal hydraulic test system according to claim 15, characterized in that: Two temperature measuring holes are arranged between adjacent positioning holes, and the temperature measuring holes are used to accommodate the temperature measuring device.

19. The thermal hydraulic test system according to claim 15, characterized in that: The element rod is provided with a blind hole along the extending direction of the element rod, and the temperature measuring device is arranged in the blind hole.

20. The thermal hydraulic test system according to claim 19, characterized in that: Also includes: A protective sleeve is arranged at the end of the element rod close to the first conductive component, and the part of the element rod outside the protective sleeve is placed in a low-temperature medium.

21. A simulation test method for a nuclear reactor, using any one of the thermal hydraulic test systems of claims 10-20, wherein the thermal hydraulic test system comprises a pressure measuring device disposed on one side of the cylinder, the pressure measuring device is used to measure pressure data of the thermal hydraulic test system, the thermal hydraulic test system further comprises a temperature measuring device, the temperature measuring device comprises a guide tube passing through the first conductive component and entering the cylinder, and a thermocouple disposed in the guide tube and used to measure temperature data of the thermal hydraulic test system, characterized in that: include: S1: Start the thermal hydraulic test system, increase the temperature and pressure of the thermal hydraulic test system, and conduct a thermal balance test on the thermal hydraulic test system until the thermal balance of the thermal hydraulic test system is greater than or equal to T S2: Collect thermal parameters of the thermal hydraulic experimental system as control group information; S3: changing the state of the thermal hydraulic experiment system and collecting the thermal parameters of the thermal hydraulic experiment system as the experimental group information; S4: Analyze the control group information and the experimental group information to obtain the heat transfer characteristic information of the reactor and the medium flow characteristic information of the reactor.

22. The simulation experiment method according to claim 21, characterized in that: The S1 includes: The heating rate of the thermal hydraulic experimental system is less than or equal to 4°C / s.

23. The simulation experiment method according to claim 21, characterized in that: Included in S4: Formula (5) is used to determine whether the medium in the thermal hydraulic experimental system is a single-phase medium. Where Z ONB is the starting point of supercooled boiling of the medium in the thermal hydraulic experimental system, G is the mass flow rate of the medium in the thermal hydraulic experimental system, D is the hydraulic equivalent diameter of the thermal hydraulic experimental system, Cp i is the constant pressure specific volume of the medium in the thermal hydraulic experimental system, q is the heat flux density of the thermal hydraulic experimental system, (ΔT sub ) in is the inlet subcooling degree of the thermal hydraulic experimental system, (ΔT sat ) ONB is the saturation temperature of the subcooled boiling starting point of the thermal hydraulic experimental system, h spi is the heat transfer coefficient of the thermal-hydraulic experimental system.

24. The simulation experiment method according to claim 21, characterized in that: Included in S3: Increasing the heating power of the thermal hydraulic experimental system; Included in S4: When the temperature difference of the equivalent component or the wall temperature difference of the element rod fluctuates continuously and stably and the amplitude of the fluctuation is greater than 5%, it is determined that flow instability occurs in the thermal-hydraulic experimental system.

25. The simulation experiment method according to claim 21, characterized in that: Included in S3: Increasing the heating power of the thermal hydraulic experimental system; Included in S4: When the temperature difference of the equivalent components or the temperature rise of the wall surface of the element rod is greater than 5°C / s, it is determined that the boiling critical phenomenon occurs in the thermal hydraulic experimental system.

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