Method and system for analyzing characteristics of crevasse jet flow of primary loop of reactor

Abstract

The invention relates to the technical field of nuclear reactors, and provides a reactor primary circuit crevasse jet characteristic analysis method and system.The method comprises the following steps that a finite volume method is adopted, and a fluid domain three-dimensional geometric model of a nuclear reactor primary side pipeline, a crevasse flow channel and a jet development area is established; performing grid division on the three-dimensional geometric model of the fluid domain, and dividing computational fluid mechanics grids of the fluid domain; and according to the constructed physical property correction equation of the saturation temperature and the saturated steam pressure of the water and the obtained fluid domain calculation fluid mechanics grid, setting the boundary condition of the fluid domain when the crevasse accident occurs, and iteratively solving the critical temperature of the fluid under different pressures and the saturated steam pressure corresponding to the fluid under different temperatures. According to the method, the jet impact phenomenon along with violent flash evaporation in the high-temperature and high-pressure fluid jet process under the transient condition can be calculated and analyzed, the numerical range of the impact pressure can be provided, and a reference value is provided for selection of structural materials in a reactor.

Description

Technical Field

[0001] The present disclosure relates to the technical field related to nuclear reactors, and in particular to a method and system for analyzing the characteristics of a reactor primary circuit rupture jet. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] The primary loop of a reactor refers to the primary cooling loop in the cooling system of a nuclear reactor. It is the core component of a nuclear power plant reactor and is responsible for transferring the heat generated by the reactor core to the steam generator or heat exchanger through the coolant. In the primary loop, the coolant (usually water or gas) flows through the reactor core at high temperature and pressure, absorbing the heat released by the fission of nuclear fuel; then, the coolant leaves the reactor with the heat.

[0004] Currently, the most widely used reactor type is the pressurized water reactor, whose primary side has extremely high pressure and temperature during normal operation. In the event of a breach, the high-temperature and high-pressure fluid on the primary side will undergo violent flash evaporation during the injection process, generating a large amount of steam and forming a high-temperature and high-pressure jet phenomenon, which has stronger destructive power than a cold jet.

[0005] The inventors found in their research that the existing analysis methods for the characteristics of the reactor primary circuit rupture jet mainly focus on the jet impact analysis of single-phase cold fluids, and usually only consider small-caliber nozzle jets below 10MPa. However, in a nuclear reactor, when a rupture accident occurs in the primary cooling system, the high-temperature and high-pressure fluid ejected will produce a violent flash phenomenon due to the sudden drop in pressure, forming a high-energy, high-temperature, and high-pressure two-phase jet. This jet will have a great impact and destructive force on the internal structure of the reactor (such as exposed pipes, insulation materials, metal connecting hoses and cables). The existing analysis methods do not fully consider the influence of the heat load and flash phenomenon of this high-temperature and high-pressure jet on the stress and strain of the structural materials, especially in more complex two-phase flow conditions. This leads to the inability to obtain sufficiently accurate stress and strain field distributions when designing reactor safety protection measures and material selection, which in turn affects the safety assessment and optimization design of the reactor structure. Summary of the invention

[0006] In order to solve the above problems, the present disclosure proposes a method and system for analyzing the characteristics of a reactor primary loop rupture jet, which can realize the calculation and analysis of the jet impact phenomenon accompanied by violent flash evaporation in the process of high-temperature and high-pressure fluid jet under transient conditions, and can provide a numerical range of impact pressure to provide a reference value for the selection of structural materials in the reactor.

[0007] In order to achieve the above objectives, the present disclosure adopts the following technical solutions:

[0008] One or more embodiments provide a method for analyzing the characteristics of a reactor primary circuit breach jet, comprising the following steps:

[0009] The finite volume method is used to establish the three-dimensional geometric model of the fluid domain of the primary side pipeline, the breach flow channel and the jet development area of ​​the nuclear reactor;

[0010] Meshing the three-dimensional geometric model of the fluid domain and dividing the computational fluid dynamics grid of the fluid domain;

[0011] According to the constructed physical property correction equations of the saturated temperature and saturated vapor pressure of water and the computational fluid dynamics grid of the fluid domain, the boundary conditions of the fluid domain when a breach accident occurs are set, and the critical temperature of the fluid at different pressures and the saturated vapor pressure corresponding to the fluid at different temperatures are iteratively solved.

[0012] One or more embodiments provide a reactor primary circuit breach jet characteristics analysis system, including:

[0013] Model building module: configured to use the finite volume method to establish a three-dimensional geometric model of the fluid domain of the primary side pipeline, breach flow channel and jet development area of ​​the nuclear reactor;

[0014] A partitioning module: configured to perform mesh partitioning on the three-dimensional geometric model of the fluid domain and partition the computational fluid dynamics mesh of the fluid domain;

[0015] Iterative solution module: It is configured to set the boundary conditions of the fluid domain when a breach accident occurs based on the constructed physical property correction equations of the saturated temperature and saturated vapor pressure of water and the obtained computational fluid dynamics grid of the fluid domain, and iteratively solve the critical temperature of the fluid at different pressures and the saturated vapor pressure corresponding to the fluid at different temperatures.

[0016] An electronic device includes a memory and a processor and computer instructions stored in the memory and running on the processor. When the computer instructions are run by the processor, the steps in the above-mentioned method for analyzing the characteristics of a reactor primary circuit rupture jet are completed.

[0017] A computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the steps in the above-mentioned method for analyzing the characteristics of a reactor primary circuit rupture jet are completed.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention adopts the finite volume method to establish a numerical model of the primary circuit rupture jet impact flow field under high temperature and high pressure jet impact, and uses the CFD calculation method to simulate the primary circuit rupture jet impact flow field characteristics, which can realize the calculation and analysis of the jet impact phenomenon accompanied by violent flash evaporation in the process of high temperature and high pressure fluid jet, and can provide the numerical range of impact pressure, providing a reference value for the selection of structural materials in the reactor;

[0020] The analysis method disclosed in the present invention corrects the changes of the saturated temperature and saturated vapor pressure of water with time and calculation conditions in the computational fluid dynamics solver, thereby realizing the calculation and analysis of the jet impact phenomenon accompanied by violent flash evaporation in the process of high-temperature and high-pressure fluid jet under transient conditions. The jet flow state and the spatial distribution of pressure and temperature at different times can be obtained, and the numerical range of the impact pressure can be provided.

[0021] The advantages of the present disclosure and the advantages of additional aspects will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The exemplary embodiments of the present disclosure and the description thereof are used to explain the present disclosure but do not constitute a limitation of the present disclosure.

[0023] Figure 1 This is a method flow chart of a method for analyzing the characteristics of a reactor primary circuit rupture jet according to Embodiment 1 of the present disclosure;

[0024] Figure 2 It is a schematic diagram of the structure of a three-dimensional geometric model of a fluid domain constructed in Example 1 of the present disclosure;

[0025] Figure 3 is a schematic diagram of the iterative solution process of Embodiment 1 of the present disclosure; DETAILED DESCRIPTION

[0026] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0027] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present disclosure belongs.

[0028] It should be noted that the terms used here are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof. It should be noted that, in the absence of conflict, the various embodiments in the present disclosure and the features in the embodiments can be combined with each other. The embodiments will be described in detail below in conjunction with the accompanying drawings.

[0029] Example 1

[0030] In the technical solutions disclosed in one or more embodiments, Figures 1 to 3 As shown, a method for analyzing the characteristics of a reactor primary circuit break jet comprises the following steps:

[0031] Step 1: Using the finite volume method, a three-dimensional geometric model of the fluid domain of the primary side pipeline, the breach flow channel and the jet development area of ​​the nuclear reactor is established;

[0032] The implementation method of constructing the three-dimensional geometric model of the fluid domain in step 1 includes the following steps:

[0033] Step 1-1: Determine the research object and research area;

[0034] A feasible technical solution is to determine that the research object is the primary side piping system of the nuclear reactor and the fluid injection area in the case of a breach accident; the research area includes the breach site, breach flow channel and jet development area of ​​the primary side piping;

[0035] Specifically, the study area includes the breach diameter, the space through which the jet fluid passes, and the impacted structures that the jet may affect.

[0036] Furthermore, boundary conditions are set, which are set according to the type of fluid (such as water vapor, water or two-phase flow) ejected from the breach fluid and its pressure and temperature, and are usually set with high temperature and high pressure parameters during normal operation of the nuclear reactor as initial conditions;

[0037] Step 1-2: Based on the research object and research area boundary determined in step 1-1, use 3D software such as Solidworks to build a model. The diameter of the breach flow channel is the breach diameter, and the length is the primary side pipe wall thickness.

[0038] Optionally, the modeling software may be SolidWorks, ANSYS Design Modeler or other 3D modeling software to construct a 3D geometric model of the primary side pipeline, the breach flow channel and the jet area;

[0039] Specifically, the main function of the primary side pipeline is to transport the coolant to the core, and the model needs to reflect the geometric details of the pipeline; the modeling of the primary side pipeline sets the inner diameter, outer diameter, length and wall thickness of the pipeline according to the actual size of the primary side pipeline of the nuclear reactor;

[0040] Among them, the pipe wall thickness is usually designed according to the actual nuclear reactor, using the pipe thickness value of the nuclear power plant standard;

[0041] Specifically, the modeling of the breach flow channel includes setting the breach diameter and breach length;

[0042] Breach diameter: The diameter of the breach is determined based on the accident assumptions. The breach size is set based on the maximum assumed accident (LOCA) scenario.

[0043] Breach length: The breach length is equal to the wall thickness of the primary side pipe, which is the longitudinal dimension of the breach flow path;

[0044] Specifically, the modeling of the jet area includes preliminary calculations to determine the jet development area and the diffusion angle; the size of the development area can be determined based on preliminary calculations to determine the diffusion angle, velocity, pressure change, etc. of the fluid jet so as to cover the injection area; based on the actual situation of the high-pressure fluid injection in the primary circuit of the nuclear reactor, the diffusion angle of the jet is estimated, and the diffusion angle is generally set to a conical jet.

[0045] Step 2: Use the finite volume method to mesh the three-dimensional geometric model of the fluid domain and divide the computational fluid dynamics grid of the fluid domain;

[0046] Dividing a computational fluid dynamics grid of the fluid domain on the three-dimensional geometric model of the nuclear reactor primary side pipeline, breach flow channel and jet development area in step 1;

[0047] Specifically, the method for dividing the computational fluid dynamics grid of the fluid domain includes the following steps:

[0048] Step 2-1: Import the 3D geometric model created in step 1-2 into other computational fluid dynamics meshing software such as Ansysmesh or Fluentmeshing;

[0049] Step 2-2: Determine the mesh type and mesh size according to the geometry of the model, set the fluid boundary layer and generate the computational mesh;

[0050] In some embodiments, selecting the grid type may be as follows:

[0051] 221. For the breach area and the junction of the pipeline, a tetrahedral grid is used;

[0052] 222. Distinguish between regular and irregular areas of a 3D geometric model, and use hexahedral meshes in regular areas:

[0053] Specifically, hexahedral meshes are used in relatively regular areas such as the primary side pipeline to reduce the computational cost; unstructured meshes are used in areas with complex geometries or mixed irregular shapes, such as the jet area.

[0054] In some embodiments, the determination of the grid size includes the following:

[0055] Step 22.1, Global Grid Size: Set the size of the global grid storage according to the size of the entire geometric model and the computing resources;

[0056] In this embodiment, the global grid size is set based on the computing resources, so that the set grid size can be appropriate, thereby avoiding excessive computing burden.

[0057] Step 22.2, local mesh refinement: identify key areas and perform local mesh refinement so that the key areas can have a sufficiently high mesh density and thus a higher resolution to accurately capture the jet flow of high temperature and high pressure fluid;

[0058] Specifically, the critical areas may include the vicinity of the breach, the starting area of ​​the fluid jet, the boundary layer, and the impacted area;

[0059] In some embodiments, a fluid boundary layer is set, and the boundary layer grid is set as follows:

[0060] Step 22-1. Set the boundary layer mesh size: The boundary layer is the area of ​​the fluid layer near the wall in the fluid flow. The velocity gradient and temperature gradient of the fluid are very high, so a finer mesh is required to resolve these changes;

[0061] Step 22-2, set up layered grids: In the area near the pipe wall and the breach flow channel, multiple boundary layer grids (usually 2-5 layers) need to be generated, and the thickness of each layer gradually increases from the wall to the inside of the fluid. This can capture the wall effect and ensure the accuracy of the numerical calculation.

[0062] Step 22-3, the boundary layer growth ratio is set between 1.1 and 1.2, that is, the thickness of each layer increases by 10% to 20% relative to the previous layer, ensuring that the grid within the boundary layer is fine enough to resolve the velocity and temperature gradients.

[0063] Furthermore, mesh transition processing is performed during the mesh division process, specifically, as follows:

[0064] 1) Adopt the transition from fine grid to coarse grid, use the set size of fine grid in the key area, and use the set size of coarse grid in the non-key area;

[0065] This embodiment adopts the transition from fine grid to coarse grid. In order to maintain the calculation accuracy without increasing the amount of calculation, fine grid is used in the key area, and coarser grid is used in places far away from the breach flow channel and the core area of ​​the jet. The transition area is used to achieve a smooth transition from fine grid to coarse grid to avoid numerical instability at the boundary.

[0066] 2) Automatically adjust the density of local grids according to the geometric complexity. Automatically refine the grid in the breach area and jet development area. This function can improve the accuracy of the model.

[0067] After completing the above steps, the computational mesh is generated according to the set mesh type, size, boundary layer and transition area.

[0068] Step 3: According to the constructed physical property correction equations of the saturated temperature and saturated vapor pressure of water and the obtained computational fluid dynamics grid of the fluid domain, the boundary conditions of the fluid domain when the breach accident occurs are set, and the critical temperature of the fluid at different pressures and the saturated vapor pressure corresponding to the fluid at different temperatures are iteratively solved;

[0069] Specifically, import the computational fluid dynamics grid of the fluid domain of the nuclear reactor primary side pipeline, breach flow channel and jet development area divided in step 2 into the computational fluid dynamics solver, and set the boundary conditions of the fluid domain when the breach accident occurs. Add the equations for the change of the saturated temperature and saturated vapor pressure of water to the computational fluid dynamics solver, so that the computational fluid dynamics solver can iteratively solve the critical temperature of the fluid at different pressures, and the corresponding saturated vapor pressure of the fluid at different temperatures. Run the computational fluid dynamics solver to obtain the jet state and the spatial distribution of pressure and temperature at different times. The specific steps are as follows:

[0070] Step 3-1: Import the fluid domain computational fluid dynamics mesh of the nuclear reactor primary side pipeline, breach flow channel and jet development area divided in step 2 into the transient solver of the computational fluid dynamics software, set one end of the primary side pipeline as the inlet of the fluid computational domain, and the other end as the wall surface, and set the side of the jet development area away from the breach of the pipe wall as the outlet of the fluid computational domain;

[0071] Step 3-2: Set the fluid in the fluid calculation domain to water and water vapor, and set the density of water as a parameter that changes with temperature through physical property settings;

[0072] Step 3-3: Set the boundary conditions of the fluid calculation domain, set the inlet boundary to pressure inlet and temperature, and set the outlet boundary to pressure outlet;

[0073] Step 3-4: Use the Mixture multiphase flow model, combined with the evaporation-condensation model and the cavitation model to correct the state of water and water vapor. Based on the equation of the saturated temperature and saturated vapor pressure of water, use the CFD calculation method to iteratively solve the fluid state at different pressures and temperatures;

[0074] Specifically, the Mixture multiphase flow model is selected, the evaporation-condensation model and the cavitation model are enabled in the mass transfer module, and the physical property correction equations of the saturated temperature and saturated vapor pressure of water are written into the mass transfer model through the expression definition function of the CFD calculation program or the compilation function of the subroutine, and the fluid state at different times is corrected to obtain a more accurate two-phase state of the fluid at each time;

[0075] In this embodiment, the equations for the changes of the saturated temperature and saturated vapor pressure of water with time and calculation conditions are added to the computational fluid dynamics solver, so that the computational fluid dynamics solver can iteratively solve the critical temperature of the fluid at different pressures and the cavitation pressure corresponding to the fluid at different temperatures, thereby improving the numerical model solution process under variable physical property conditions, so that it can realize the computational analysis of the jet impact phenomenon accompanied by violent flash evaporation in the high-temperature and high-pressure fluid jet process under transient conditions.

[0076] Specifically, the physical property correction equations of water saturation temperature and saturated vapor pressure are as follows:

[0077]

[0078] Where:

[0079] T sat Indicates the saturation temperature of water at the corresponding pressure, °C;

[0080] P represents the water pressure, kPa;

[0081] P sat Indicates the saturated vapor pressure of water, kPa;

[0082] H vap It represents the evaporation enthalpy of water at different temperatures, kJ / kg;

[0083] R represents the gas constant;

[0084] T is the temperature of water, °C.

[0085] Furthermore, the k-ε turbulence model is selected in the transient solver, the fluid calculation domain is initialized, and the initial temperature and pressure conditions are set for the fluid calculation domain. After the settings are completed, the calculation is performed.

[0086] Furthermore, in step 3-4, the CFD calculation method is used to iteratively solve the fluid state at different pressures and temperatures, and the solution process is:

[0087] 341. First, initialize the parameters;

[0088] The initialization parameters include:

[0089] 4.1) Initial values ​​of field variables such as pressure, velocity, and temperature;

[0090] 4.2) Boundary conditions, including inlet pressure, inlet temperature, outlet pressure, etc.;

[0091] 4.3) Fluid properties, including density, viscosity, specific heat capacity, etc. of water and water vapor, which will change with temperature or pressure;

[0092] 342. In each iteration, the mass equation and momentum equation must first be solved simultaneously to update the pressure field and velocity field of the fluid;

[0093] The mass equation, based on the conservation of mass, describes the rate at which a fluid flows through a control volume;

[0094] Momentum equation (Navier-Stokes equation): used to describe the momentum change of the fluid, including the effects of viscous forces and pressure gradients;

[0095] 343. Solve the energy equation to obtain temperature data, and calculate the new temperature distribution through the current fluid velocity, pressure, temperature and physical parameters;

[0096] Among them, the energy equation is used to describe the energy conservation relationship of the fluid, which mainly includes convection, heat conduction and the phase change effect;

[0097] 344. According to the calculated new temperature distribution, based on the physical property correction equation of the saturated temperature and saturated vapor pressure of water, the physical property parameters of the fluid are updated; it is determined whether the error of each field variable is less than the set error range. If the error meets the convergence standard, the iteration process ends; if not, the iteration continues and step 342 is executed.

[0098] Specifically, field variables include data such as pressure, velocity, and temperature;

[0099] After obtaining a new temperature field, the physical properties of the fluid (such as density, viscosity, specific heat capacity, etc.) will usually change. At this time, it is necessary to use a predefined physical property correction equation based on the new temperature data to update the physical properties of the fluid.

[0100] In this embodiment, the iterative solution process combines the mass equation, momentum equation and energy equation, and obtains the convergent solution of the fluid pressure, velocity, temperature and other field variables through step-by-step iteration. In each iteration, the new temperature value will cause the change of the fluid physical parameters, and finally the two-phase state distribution of the fluid at different times, pressures and temperatures under the breach accident is obtained through CFD solution.

[0101] The analysis method of this embodiment corrects the changes of the saturated temperature and saturated vapor pressure of water with time and calculation conditions in the computational fluid dynamics solver, thereby realizing the calculation and analysis of the jet impact phenomenon accompanied by violent flash vaporization in the process of high-temperature and high-pressure fluid jet under transient conditions. The jet flow state and the spatial distribution of pressure and temperature at different times can be obtained, and the numerical range of the impact pressure can be provided.

[0102] Example 2

[0103] Based on Example 1, this embodiment provides a reactor primary circuit breach jet characteristics analysis system, including:

[0104] Model building module: configured to use the finite volume method to establish a three-dimensional geometric model of the fluid domain of the primary side pipeline, breach flow channel and jet development area of ​​the nuclear reactor;

[0105] A partitioning module: configured to perform mesh partitioning on the three-dimensional geometric model of the fluid domain and partition the computational fluid dynamics mesh of the fluid domain;

[0106] Iterative solution module: It is configured to set the boundary conditions of the fluid domain when a breach accident occurs based on the constructed physical property correction equations of the saturated temperature and saturated vapor pressure of water and the obtained computational fluid dynamics grid of the fluid domain, and iteratively solve the critical temperature of the fluid at different pressures and the saturated vapor pressure corresponding to the fluid at different temperatures.

[0107] Example 3

[0108] Based on Example 1, an electronic device is provided in this embodiment, including a memory and a processor, and computer instructions stored in the memory and running on the processor. When the computer instructions are executed by the processor, the steps in the method for analyzing the characteristics of a reactor primary loop rupture jet described in Example 1 are completed.

[0109] Example 4

[0110] Based on Example 1, a computer-readable storage medium is provided in this embodiment for storing computer instructions. When the computer instructions are executed by a processor, the steps in the method for analyzing the characteristics of a reactor primary circuit breach jet described in Example 1 are completed.

[0111] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

[0112] Although the above describes the specific implementation methods of the present disclosure in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present disclosure. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present disclosure, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present disclosure.

Claims

1. A method for analyzing the characteristics of a reactor primary circuit rupture jet, characterized in that: The steps include: The finite volume method is used to establish the three-dimensional geometric model of the fluid domain of the primary side pipeline, the breach flow channel and the jet development area of ​​the nuclear reactor; Meshing the three-dimensional geometric model of the fluid domain and dividing the computational fluid dynamics grid of the fluid domain; According to the constructed physical property correction equations of the saturated temperature and saturated vapor pressure of water and the computational fluid dynamics grid of the fluid domain, the boundary conditions of the fluid domain when a breach accident occurs are set, and the critical temperature of the fluid at different pressures and the saturated vapor pressure corresponding to the fluid at different temperatures are iteratively solved.

2. A method for analyzing the characteristics of a reactor primary circuit rupture jet according to claim 1, characterized in that: The method for constructing a three-dimensional geometric model of a fluid domain includes the following steps: Determine the research object and research area; determine that the research object is the primary side piping system of the nuclear reactor and the fluid injection area in the case of a breach accident; the research area includes the breach site, breach flow channel and jet development area of ​​the primary side piping; Modeling is performed based on the determined research object and research area boundary. The diameter of the breach flow channel is the breach diameter, and the length is the thickness of the primary side pipe wall. The modeling of the jet area includes preliminary calculations to determine the jet development area and the diffusion angle.

3. A method for analyzing the characteristics of a reactor primary circuit break jet according to claim 1, characterized in that: A method for dividing a computational fluid dynamics grid of a fluid domain comprises the following steps: Import the established three-dimensional geometric model into computational fluid dynamics meshing software; According to the shape of the geometric model, determine the mesh type and mesh size, set the fluid boundary layer and generate the computational mesh.

4. A method for analyzing the characteristics of a reactor primary circuit break jet according to claim 3, characterized in that: Select the mesh type as follows: For the breach area and the pipe junction, a tetrahedral mesh is used; Distinguish between regular and irregular areas of a 3D geometric model, and use hexahedral meshes in regular areas; Alternatively, the mesh size may be determined as follows: Set the size of the global grid storage according to the size of the entire geometric model and the computing resources; Identify key areas and perform local mesh refinement to ensure that the key areas have a sufficiently high mesh density; Alternatively, mesh transition processing is performed during mesh division, specifically as follows: Adopting a transition from fine grid to coarse grid, using a set size of fine grid in critical areas and a set size of coarse grid in non-critical areas; Automatic mesh refinement automatically adjusts the density of local meshes according to geometric complexity, and performs automatic mesh refinement in the breach area and jet development area.

5. A method for analyzing the characteristics of a reactor primary circuit rupture jet according to claim 1, characterized in that: According to the constructed physical property correction equation of water saturation temperature and saturation vapor pressure, and the obtained fluid domain computational fluid dynamics grid, the boundary conditions of the fluid domain when the breach accident occurs are set, and the critical temperature of the fluid under different pressures and the saturated vapor pressure corresponding to the fluid at different temperatures are iteratively solved, including the following steps: Import the divided fluid domain computational fluid dynamics grid into the transient solver of the computational fluid dynamics software, set one end of the primary side pipe as the inlet of the fluid computational domain, and the other end as the wall surface, and set the side of the jet development area away from the pipe wall rupture as the outlet of the fluid computational domain; Set the fluids in the fluid calculation domain to water and water vapor, and set the water density as a parameter that changes with temperature through physical property settings; Set the boundary conditions of the fluid calculation domain, the inlet boundary is set to pressure inlet and temperature, and the outlet boundary is set to pressure outlet; The Mixture multiphase flow model is used in combination with the evaporation-condensation model and the cavitation model to correct the state of water and water vapor. Based on the equation of the change of the saturated temperature and saturated vapor pressure of water, the CFD calculation method is used to iteratively solve the fluid state at different pressures and temperatures.

6. A method for analyzing the characteristics of a reactor primary circuit break jet according to claim 5, characterized in that: The physical property correction equation of water saturation temperature and saturated vapor pressure is as follows: Where: T sat It indicates the saturation temperature of water at the corresponding pressure; P represents the pressure of water; P sat Indicates the saturated vapor pressure of water; H vap It represents the enthalpy of evaporation of water at different temperatures; R represents the gas constant; T represents the temperature of water.

7. A method for analyzing the characteristics of a reactor primary circuit rupture jet according to claim 5, characterized in that: The CFD calculation method is used to iteratively solve the fluid state under different pressures and temperatures. The solution process is: Step 341, first initialize the parameters; Step 342, in each iteration, firstly, the mass equation and the momentum equation are solved simultaneously to update the pressure field and velocity field of the fluid; Step 343: Solve the energy equation to obtain temperature data, and calculate a new temperature distribution through the current fluid velocity, pressure, temperature and physical parameters; Step 344: update the physical property parameters of the fluid according to the calculated new temperature distribution and the physical property correction equation based on the saturated temperature and saturated vapor pressure of water; determine whether the error of each field variable is less than the set error range; if the error meets the convergence standard, the iterative process ends; if not, execute step 342 to continue the iteration.

8. A reactor primary circuit rupture jet characteristics analysis system, characterized in that: include: Model building module: configured to use the finite volume method to establish a three-dimensional geometric model of the fluid domain of the primary side pipeline, breach flow channel and jet development area of ​​the nuclear reactor; A partitioning module: configured to perform mesh partitioning on the three-dimensional geometric model of the fluid domain and partition the computational fluid dynamics mesh of the fluid domain; Iterative solution module: It is configured to set the boundary conditions of the fluid domain when a breach accident occurs based on the constructed physical property correction equations of the saturated temperature and saturated vapor pressure of water and the obtained computational fluid dynamics grid of the fluid domain, and iteratively solve the critical temperature of the fluid at different pressures and the saturated vapor pressure corresponding to the fluid at different temperatures.

9. An electronic device, characterized in that: The method comprises a memory and a processor and computer instructions stored in the memory and executed on the processor. When the computer instructions are executed by the processor, the steps in the method for analyzing the characteristics of a reactor primary circuit rupture jet as described in any one of claims 1 to 7 are completed.

10. A computer-readable storage medium, characterized in that: Used to store computer instructions, which, when executed by a processor, complete the steps of a method for analyzing the characteristics of a reactor primary circuit rupture jet as described in any one of claims 1 to 7.

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