Fluid-structure interaction seismic response analysis method for liquid metal reactor

Abstract

The invention belongs to the technical field of reactor system structural mechanics, and particularly relates to a fluid-structure interaction seismic response analysis method for a liquid metal reactor. The method comprises the following steps: S10, establishing a reactor geometric model; s20, performing finite element modeling on the established reactor geometric model; s30, performing fluid-solid coupling setting on the established reactor finite element model; s40, setting boundary conditions for the built reactor finite element model; s50, introducing an asymmetric stiffness matrix into an acoustic fluid unit, and carrying out modal analysis on the reactor finite element model by adopting an asymmetric modal analysis method; and S60, carrying out response spectrum analysis. The liquid metal reactor can be accurately and effectively simulated to consider the liquid shaking effect, the dynamic coupling problem of liquid metal and the structure is solved, and a simple, accurate and reliable analysis method is provided for dynamic analysis of a reactor body considering liquid shaking under earthquake excitation.

Description

Technical Field

[0001] The present invention belongs to the technical field of reactor system structural mechanics, and in particular relates to a fluid-solid coupling seismic response analysis method for a liquid metal reactor. Background Art

[0002] Liquid metal reactors (LMRs) are a fourth-generation reactor type that my country is prioritizing development. Their core is typically designed as a large, thin-walled, pool-like vessel containing a heat exchanger, main pump, reactor core, and a large amount of liquid metal. Under the influence of earthquakes, the liquid metal sloshes, generating hydrodynamic pressure on the vessel walls and potentially damaging the vessel and internal components. Compared to traditional pressurized water reactors (PWRs), LMRs are more susceptible to the dynamic effects of liquid sloshing during earthquakes due to their pool-like design and the much higher density of liquid metal than water. Therefore, to ensure the structural integrity of the reactor, its equipment, and components during earthquakes, and thus ensure reactor safety, research into the seismic resistance of reactors considering liquid sloshing is essential.

[0003] A search of patent literature reveals two current technical approaches to addressing the problem of seismic response analysis considering liquid sloshing: The theoretical approach, based on the Hounser model, divides the liquid within the reactor into a pulse mass that moves with the rigid body of the container and a sloshing mass that oscillates on the free surface. By linearizing the fluid motion equations, the natural frequency, mode shape, and sloshing load of the liquid sloshing can be calculated. This theoretical approach is only applicable to geometrically regular liquid storage containers and is not fully applicable to pool-type reactors with numerous internal components. The computational fluid dynamics approach separates the calculation of sloshing loads from the reactor's seismic dynamic analysis. Using CFD technology, the wave height and load of liquid sloshing under seismic excitation can be obtained. The liquid dynamic load is then applied to the structural wall, and combined with seismic excitation, the reactor's seismic dynamic analysis can be performed. However, the computational fluid dynamics approach takes a long time to calculate and decouples the analysis of liquid sloshing from structural motion. This approach fails to reflect the interaction between structural deformation and liquid sloshing, hinders rapid analysis iterations during the design phase, and fails to effectively guide structural design improvements.

[0004] While existing technologies can theoretically analyze and simulate the effects of liquid sloshing, these analyses are only applicable to geometrically simple liquid storage containers and are not fully applicable to pool-type reactors with complex internal components. Computational fluid dynamics simulations consume significant computing resources and time, and decouple liquid sloshing from structural motion, failing to reflect the interaction between structural deformation and liquid sloshing. Existing technologies are unable to support rapid analysis of the seismic dynamic response of pool-type reactors and provide ineffective guidance for structural design improvements. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a fluid-structure coupling seismic response analysis method for a liquid metal reactor, which can accurately and effectively simulate the liquid metal reactor taking into account the liquid sloshing effect, solve the dynamic coupling problem between liquid metal and structure, and provide a simple, accurate and reliable analysis method for the dynamic analysis of the reactor body taking into account liquid sloshing under seismic excitation.

[0006] The technical solution adopted in the present invention is:

[0007] A fluid-solid coupling seismic response analysis method for a liquid metal reactor comprises the following steps:

[0008] S10: Establishing a reactor geometric model; S20: Performing finite element modeling on the reactor geometric model established in step S10; S30: Performing fluid-solid coupling setting on the reactor finite element model established in step S20; S40: Setting boundary conditions on the reactor finite element model established in step S20; S50: Introducing an asymmetric stiffness matrix into the acoustic fluid unit, and performing modal analysis on the reactor finite element model using an asymmetric modal analysis method; S60: Performing response spectrum analysis.

[0009] The step of establishing the reactor geometric model comprises the following steps:

[0010] S101. Establish a geometric model of the reactor vessel; S102. Establish a geometric model of the internal components; S103. Determine whether the liquid metal inside the reactor participates in sloshing based on whether there is a free liquid surface in the metal fluid of each component; S104. Establish a geometric model of the liquid metal participating in sloshing.

[0011] The method of establishing a geometric model of the reactor vessel comprises the following steps: first, based on the specific structure of the reactor vessel, after simplifying the local details of threads and chamfers, a simplified solid model of the reactor vessel is established at a 1:1 ratio using structural modeling software, which must include at least the reactor vessel wall and top cover assembly; then, a mid-surface extraction operation is used to create an intermediate surface of the solid surface, thereby obtaining a surface geometric model of the reactor vessel; and gaps generated by the mid-surface extraction are eliminated through move and stretch operations.

[0012] The geometric model of the internal component is established as follows: first, based on the specific structure of the internal component, after simplifying the local details of the thread and chamfer, a simplified solid model of the internal component is established at a 1:1 ratio using structural modeling software, which must include at least the hanging basket cylinder, the upper diverter plate, and the lower diverter plate; then, a mid-surface extraction operation is used to create the middle surface of the solid surface, thereby obtaining the surface geometric model of the internal component, and through moving and stretching operations, the gaps caused by the mid-surface extraction are eliminated.

[0013] The geometric model of the liquid metal involved in the sloshing is established as follows: according to the liquid metal determined in step S103, a cylinder of corresponding position and height is established; based on the geometric models of the reactor vessel and internal components established in steps S101 and S102, the geometric models of the reactor vessel and internal components are cut from the cylinder using Boolean operations, and the remaining part is the geometric model of the liquid metal involved in the sloshing.

[0014] The finite element modeling of the established reactor geometric model comprises the following steps:

[0015] S201. Structural unit mesh division; S202. Structural unit material parameter assignment; S203. Fluid unit mesh division; S204. Fluid unit material parameter assignment; S205. Structural density adjustment; S206. Additional density setting of metal fluid.

[0016] The structural unit meshing: For structures with a wall thickness / diameter less than 10, the surface geometric model of the reactor vessel and internal components obtained in step S10 is meshed using shell elements to obtain structural units, and the mesh size is set to 0.5 to 0.8 times the structural wall thickness; the shell elements are assigned corresponding cross-sectional parameters according to the structural wall thickness.

[0017] The structural unit material parameter assignment: assigning material parameters of different structures to the structural unit obtained in step S201 according to material properties, including density, elastic modulus and Poisson's ratio.

[0018] The fluid unit mesh division: for the liquid metal geometric model obtained in step S10, acoustic fluid units are used to divide the mesh to obtain acoustic fluid units, and the mesh size is the same as the surface mesh size.

[0019] The fluid unit material parameter assignment: assigning the acoustic fluid unit obtained in step S203 material parameters of the metal fluid, including density and sound velocity.

[0020] The structural density adjustment is to ensure that the weight and center of gravity of each component and the overall finite element model of the reactor are consistent with the specific structure, and to adjust the structural density of the finite element model.

[0021] The additional density of the metal fluid is set as follows: for the metal fluid that does not participate in the shaking, its total weight is divided by the unit volume of the reactor container at the corresponding position to obtain the additional density, and the additional density is added to the raw material density to obtain the material density of the reactor container at the corresponding position.

[0022] The fluid-solid coupling setting for the established reactor finite element model includes the following steps: according to the contact relationship between the liquid metal fluid and the structure, the interface between the fluid and the reactor vessel and the internal structure is set as a fluid-solid coupling surface, so that load and deformation can be transferred between the structure and the fluid; when setting the fluid-solid coupling, it is necessary to ensure that the fluid grid and the structural grid at the interface share nodes.

[0023] The boundary condition setting for the established reactor finite element model includes the following steps: designating the top surface of the liquid metal unit grid as the free liquid surface and setting the gravity acceleration vertically downward; and setting appropriate boundaries based on the connection relationship between the reactor and the civil structure and the connection relationship between the various components in the reactor.

[0024] The modal analysis comprises the following steps:

[0025] S501. Focus on low frequencies and use asymmetric modal analysis to calculate multi-order modal frequencies and vibration shapes of the reactor finite element model;

[0026] S502. Focus on medium and high frequencies and use asymmetric modal analysis to calculate multi-order modal frequencies and vibration shapes for the reactor finite element model;

[0027] S503. The total modal participation factor of the two-step modal analysis should be no less than 80%.

[0028] The response spectrum analysis comprises the following steps:

[0029] S601: Calculate the 100th mode with a starting frequency of 0.1 Hz. Use the floor response spectrum at the pressure vessel support as input. Perform response spectrum analysis in the three orthogonal directions (X, Y, and Z) using the single-point response spectrum method. Calculate the model response separately. Then, use the square root sum method to combine the responses in the three directions to obtain the dynamic response of the reactor structure. The result is recorded as SL2_0.1.

[0030] S602. Calculate the 100th mode with a starting frequency of 5 Hz. Use the floor response spectrum at the pressure vessel support as input and perform response spectrum analysis in the three orthogonal directions (X, Y, and Z) using the single-point response spectrum method. Calculate the model response separately. Then, use the square sum square root method to combine the responses in the three directions to obtain the dynamic response of the reactor structure. The result is recorded as SL2_5.

[0031] S603. Combine the results of SL2_0.1 and SL2_5 to finally obtain the results of earthquake dynamic analysis.

[0032] Beneficial effects of the present invention:

[0033] (1) The present invention provides a fluid-solid coupling seismic response analysis method for liquid metal reactors, which provides a highly accurate and widely applicable simulation method for the engineering problem of seismic dynamic response analysis of liquid metal reactors taking into account liquid sloshing.

[0034] (2) The present invention provides a fluid-solid coupling seismic response analysis method for liquid metal reactors. It uses acoustic fluid units to quickly, efficiently and accurately simulate the dynamic characteristics of metal fluids and is applicable to fluid arrangements in reactors of any shape.

[0035] (3) The present invention provides a fluid-structure coupling seismic response analysis method for liquid metal reactors. The fluid-structure coupling method is used to simulate the interaction between the metal fluid and the reactor structure, providing a more accurate analysis method for the dynamic response of the reactor considering liquid sloshing.

[0036] (4) The present invention provides a fluid-solid coupling seismic response analysis method for liquid metal reactors, which can realistically and effectively simulate the fluid sloshing characteristics of any shape and realize the interaction between the metal fluid sloshing and the reactor structure through fluid-solid coupling, thereby obtaining more accurate seismic dynamic responses for engineering applications and being more suitable for actual engineering use. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] To more clearly illustrate the embodiments of the present invention, the following briefly describes the drawings required for describing the embodiments of the present invention. Obviously, the drawings described below are only some of the embodiments described in the present invention. Those skilled in the art can derive other drawings based on the following drawings without inventive effort.

[0038] Figure 1 Schematic diagram of the reactor geometric model;

[0039] Figure 2 is a schematic diagram of the finite element model;

[0040] Figure 3 It is a finite element model diagram of liquid metal fluid;

[0041] Figure 4 is a schematic diagram of the fluid-structure interaction setup;

[0042] Figure 5 This is a schematic diagram of stress intensity under reactor earthquake conditions. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., referring to orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, removable, or integral connections; mechanical or electrical connections; direct or through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0046] The present invention provides a fluid-solid coupling seismic response analysis method for a liquid metal reactor, comprising the following steps:

[0047] S10: Build the reactor geometry model

[0048] S101. Establish a geometric model of the reactor vessel: First, based on the specific structure of the reactor vessel, simplify local details such as threads and chamfers, and then use structural modeling software to establish a simplified solid model of the reactor vessel at a 1:1 ratio, which must include at least the reactor vessel wall and top cover assembly; then use the mid-surface extraction operation to create the middle surface of the solid surface, and then obtain the surface geometric model of the reactor vessel, and eliminate the gaps caused by the mid-surface extraction through move and stretch operations.

[0049] S102. Establish a geometric model of the internal components: First, based on the specific structure of the internal components, simplify the local details such as threads and chamfers, and then use structural modeling software to establish a simplified solid model of the internal components at a 1:1 ratio, which must include at least the hanging basket cylinder, upper diverter plate, and lower diverter plate; then use the mid-surface extraction operation to create the middle surface of the solid surface, and then obtain the surface geometric model of the internal components, and eliminate the gaps caused by the mid-surface extraction through move and stretch operations.

[0050] S103. Determine whether the liquid metal inside the reactor participates in sloshing based on whether the metal fluid of each component has a free liquid surface. For example, in this embodiment, the metal fluid below the upper manifold does not participate in sloshing because there is no free liquid surface, while the metal fluid above the upper manifold does participate in sloshing because there is a free liquid surface.

[0051] S104. Establish a geometric model of the liquid metal involved in the sloshing: According to the liquid metal determined in step S103, establish a cylinder of corresponding position and height. Based on the geometric models of the reactor vessel and internal components established in steps S101 and S102, use Boolean operations to cut the geometric models of the reactor vessel and internal components from the cylinder. The remaining part is the geometric model of the liquid metal involved in the sloshing.

[0052] S105. Through the above operations, the reactor geometric model is obtained, such as Figure 1 shown.

[0053] S20: Perform finite element modeling on the reactor geometry model established in step S10

[0054] S201. Structural unit meshing: For structures with a wall thickness / diameter less than 10 (such as reactor vessels and hanging basket cylinders), use shell elements (SHELL181 elements) to mesh the surface geometric model of the reactor vessel and internal components obtained in step S10 to obtain structural units. The mesh size is set to 0.5 to 0.8 times the structural wall thickness; the shell elements are assigned corresponding cross-sectional parameters based on the structural wall thickness.

[0055] S202, assigning material parameters to the structural units: assigning material parameters of different structures to the structural units obtained in step S201 according to the material properties, including density, elastic modulus and Poisson's ratio.

[0056] S203, fluid unit meshing: For the liquid metal geometric model obtained in step S10, acoustic fluid unit (Fluid220 unit) is used to mesh and obtain acoustic fluid unit. The mesh size is the same as the surface mesh size. The liquid metal fluid finite element model is as follows: Figure 3 shown.

[0057] S204, assigning material parameters to the fluid unit: assigning material parameters of the metal fluid to the acoustic fluid unit obtained in step S203, including density and sound velocity.

[0058] S205, structural density adjustment: ensure that the weight and center of gravity of each component and the overall finite element model of the reactor are consistent with the specific structure, and adjust the structural density of the finite element model. Take the hanging basket cylinder as an example: the hanging basket cylinder is made of metal material, and its initial density is set to 7800kg / m 3 The finite element model of the hanging basket cylinder is divided into three sections: upper, middle and lower according to the elevation. The weight and center of gravity of the three sections are obtained by ANSYS calculation. The density of the three sections is adjusted respectively so that the total weight and total weight moment (weight × center of gravity height) of the three sections are consistent with the specific structure, that is, the weight and center of gravity of the finite element model are consistent with the specific structure.

[0059] S206. Additive density setting for metal fluid: For metal fluid that does not participate in sloshing, divide its total weight by the unit volume of the reactor vessel at the corresponding location to obtain the added density. Add the added density to the raw material density to obtain the material density of the reactor vessel at the corresponding location. In this embodiment, the metal fluid below the upper manifold does not participate in sloshing and is simulated using the added density. Its total weight is A kg, and the total volume of the reactor vessel below the upper manifold is B m 3 , then the additional density is A / Bkg / m 3 The original density of the reactor vessel below the upper manifold is c kg / m 3 , the density after considering the additional density of the metal fluid is (c+A / B)kg / m 3 .

[0060] S207: Through the above operations, a reactor finite element model is obtained, such as Figure 2 shown.

[0061] S30: Perform fluid-solid coupling settings on the reactor finite element model established in step S20

[0062] According to the contact relationship between the liquid metal fluid and the structure, the interface between the fluid and the reactor container and the internal structure is set as a fluid-solid coupling surface, so that loads and deformations can be transferred between the structure and the fluid. When setting up the fluid-solid coupling, it is necessary to ensure that the fluid grid and the structural grid at the interface share common nodes. In this embodiment, the outer surface (interface with the reactor container), the internal hole surface (interface with the main pump, evaporator and hanging basket) and the lower surface (interface with the upper manifold) of the liquid metal fluid unit are specified as fluid-solid coupling surfaces through the (SFA,n,FSI) command, where n is the surface number to be specified as the fluid-solid coupling surface. The schematic diagram of the fluid-solid coupling setting is shown in Figure 4 .

[0063] S40: Setting boundary conditions for the reactor finite element model established in step S20

[0064] When simulating the free sloshing of liquid, the acoustic fluid unit must specify the direction of the free liquid surface and the gravitational acceleration, specify the top surface of the liquid metal unit grid as the free liquid surface, and set the gravitational acceleration vertically downward; at the same time, in order to carry out the seismic dynamic analysis of the reactor, it is necessary to set appropriate boundaries based on the connection relationship between the reactor and the civil structure and the connection relationship between the various components in the reactor. In this embodiment, the upper surface of the metal fluid unit is set as the free liquid surface through the (SFA,n,FREE) command, where n is the number of the surface to be designated as the free liquid surface. According to the specific structure, the UZ degree of freedom of the nodes of the lower bottom surface and the upper top surface of the support in contact with the civil structure is constrained, and the UY degree of freedom of the side nodes of the support in the cylindrical coordinate system is constrained, and a Z direction of 9.81m / s is applied. 2 The acceleration of gravity.

[0065] S50: Modal analysis: The asymmetric stiffness matrix is ​​introduced into the acoustic fluid unit, and the modal analysis of the reactor finite element model is performed using the unsymmetric modal analysis method (UNSYM)

[0066] S501. Focus on low frequencies (0-5 Hz) and use the unsymmetrical modal analysis method (UNSYM) to calculate the multi-order modal frequencies and vibration shapes of the reactor finite element model, which mainly reflects the sloshing mode of the liquid metal in the reactor. In this embodiment, 0.1 Hz is used as the starting frequency to calculate the 100th-order modal frequency and vibration shape.

[0067] S502. Focus on medium and high frequencies (5 to 500 Hz), and use the unsymmetrical modal analysis method (UNSYM) to calculate the multi-order modal frequencies and vibration shapes of the reactor finite element model, which mainly reflects the structural natural frequencies and vibration shapes of the reactor body and internal structure. In this embodiment, 5 Hz is used as the starting frequency to calculate the 100th-order modal frequency and vibration shape.

[0068] S503: The total modal participation coefficient of the two-step modal analysis should be no less than 80%. In this embodiment, the total modal participation coefficient of the two-step modal analysis is greater than 88%.

[0069] S60: Performing a response spectrum analysis

[0070] S601: Calculate the 100th mode with a starting frequency of 0.1 Hz. Use the floor response spectrum at the pressure vessel support as input. Use the single-point response spectrum method to perform response spectrum analysis in the three orthogonal directions (X, Y, and Z). Calculate the model response separately. Then, use the square root sum square method (SRSS) to combine the responses in the three directions to obtain the dynamic response of the reactor structure. The result is recorded as SL2_0.1.

[0071] S602. Calculate the 100th mode with a starting frequency of 5 Hz. Use the floor response spectrum at the pressure vessel support as input. Perform response spectrum analysis in the three orthogonal directions (X, Y, and Z) using the single-point response spectrum method. Calculate the model response separately. Then, use the square root sum of squares (SRSS) method to combine the responses in the three directions to obtain the dynamic response of the reactor structure. Record the result as SL2_5.

[0072] S603, combine the results of SL2_0.1 with the results of SL2_5 (LCOPER, ADD), and finally obtain the results of earthquake dynamic analysis. Figure 5 shown.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description. It is intended that all variations within the meaning and range of equivalents of the claims be embraced herein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0074] In addition, it should be understood that although the present invention is described according to implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A fluid-solid coupling seismic response analysis method for a liquid metal reactor, characterized in that: The steps include: S10: Establishing a reactor geometric model; S20: Performing finite element modeling on the reactor geometric model established in step S10; S30: Performing fluid-solid coupling setting on the reactor finite element model established in step S20; S40: Setting boundary conditions on the reactor finite element model established in step S20; S50: Introducing an asymmetric stiffness matrix into the acoustic fluid unit, and performing modal analysis on the reactor finite element model using an asymmetric modal analysis method; S60: Performing response spectrum analysis.

2. The fluid-solid coupling seismic response analysis method for a liquid metal reactor according to claim 1, characterized in that: The step of establishing the reactor geometric model comprises the following steps: S101. Establish a geometric model of the reactor vessel; S102. Establish a geometric model of the internal components; S103. Determine whether the liquid metal inside the reactor participates in sloshing based on whether there is a free liquid surface in the metal fluid of each component; S104. Establish a geometric model of the liquid metal participating in sloshing.

3. The fluid-solid coupling seismic response analysis method for a liquid metal reactor according to claim 2, characterized in that: The method of establishing a geometric model of the reactor vessel comprises the following steps: first, based on the specific structure of the reactor vessel, after simplifying the local details of threads and chamfers, a simplified solid model of the reactor vessel is established at a 1:1 ratio using structural modeling software, which must include at least the reactor vessel wall and top cover assembly; then, a mid-surface extraction operation is used to create an intermediate surface of the solid surface, thereby obtaining a surface geometric model of the reactor vessel; and gaps generated by the mid-surface extraction are eliminated through move and stretch operations.

4. The fluid-solid coupling seismic response analysis method for a liquid metal reactor according to claim 3, characterized in that: The geometric model of the internal component is established as follows: first, based on the specific structure of the internal component, after simplifying the local details of the thread and chamfer, a simplified solid model of the internal component is established at a 1:1 ratio using structural modeling software, which must include at least the hanging basket cylinder, the upper diverter plate, and the lower diverter plate; then, a mid-surface extraction operation is used to create the middle surface of the solid surface, thereby obtaining the surface geometric model of the internal component, and through moving and stretching operations, the gaps caused by the mid-surface extraction are eliminated.

5. The fluid-solid coupling seismic response analysis method for a liquid metal reactor according to claim 4, characterized in that: The geometric model of the liquid metal involved in the sloshing is established as follows: according to the liquid metal determined in step S103, a cylinder of corresponding position and height is established; based on the geometric models of the reactor vessel and internal components established in steps S101 and S102, the geometric models of the reactor vessel and internal components are cut from the cylinder using Boolean operations, and the remaining part is the geometric model of the liquid metal involved in the sloshing.

6. The fluid-solid coupling seismic response analysis method for a liquid metal reactor according to claim 5, characterized in that: The finite element modeling of the established reactor geometric model comprises the following steps: S201. Structural unit mesh division; S202. Structural unit material parameter assignment; S203. Fluid unit mesh division; S204. Fluid unit material parameter assignment; S205. Structural density adjustment; S206. Additional density setting of metal fluid.

7. The fluid-structure coupling seismic response analysis method for a liquid metal reactor according to claim 6, characterized in that: The structural unit meshing: For structures with a wall thickness / diameter less than 10, the surface geometric model of the reactor vessel and internal components obtained in step S10 is meshed using shell elements to obtain structural units, and the mesh size is set to 0.5 to 0.8 times the structural wall thickness; the shell elements are assigned corresponding cross-sectional parameters according to the structural wall thickness.

8. The fluid-solid coupling seismic response analysis method for a liquid metal reactor according to claim 7, characterized in that: The structural unit material parameter assignment: assigning material parameters of different structures to the structural unit obtained in step S201 according to material properties, including density, elastic modulus and Poisson's ratio.

9. The fluid-solid coupling seismic response analysis method for a liquid metal reactor according to claim 8, characterized in that: The fluid unit mesh division: for the liquid metal geometric model obtained in step S10, acoustic fluid units are used to divide the mesh to obtain acoustic fluid units, and the mesh size is the same as the surface mesh size.

10. The fluid-solid coupling seismic response analysis method for a liquid metal reactor according to claim 9, characterized in that: The fluid unit material parameter assignment: assigning the acoustic fluid unit obtained in step S203 material parameters of the metal fluid, including density and sound velocity.

11. The fluid-structure coupling seismic response analysis method for a liquid metal reactor according to claim 10, characterized in that: The structural density adjustment is to ensure that the weight and center of gravity of each component and the overall finite element model of the reactor are consistent with the specific structure, and to adjust the structural density of the finite element model.

12. The fluid-structure coupling seismic response analysis method for a liquid metal reactor according to claim 11, characterized in that: The additional density of the metal fluid is set as follows: for the metal fluid that does not participate in the shaking, its total weight is divided by the unit volume of the reactor container at the corresponding position to obtain the additional density, and the additional density is added to the raw material density to obtain the material density of the reactor container at the corresponding position.

13. The fluid-structure coupling seismic response analysis method for a liquid metal reactor according to claim 12, characterized in that: The fluid-solid coupling setting for the established reactor finite element model includes the following steps: according to the contact relationship between the liquid metal fluid and the structure, the interface between the fluid and the reactor vessel and the internal structure is set as a fluid-solid coupling surface, so that load and deformation can be transferred between the structure and the fluid; when setting the fluid-solid coupling, it is necessary to ensure that the fluid grid and the structural grid at the interface share nodes.

14. The fluid-structure coupling seismic response analysis method for a liquid metal reactor according to claim 13, characterized in that: The boundary condition setting for the established reactor finite element model includes the following steps: designating the top surface of the liquid metal unit grid as the free liquid surface and setting the gravity acceleration vertically downward; and setting appropriate boundaries based on the connection relationship between the reactor and the civil structure and the connection relationship between the various components in the reactor.

15. The fluid-structure coupling seismic response analysis method for a liquid metal reactor according to claim 14, characterized in that: The modal analysis comprises the following steps: S501. Focus on low frequencies and use asymmetric modal analysis to calculate multi-order modal frequencies and vibration shapes of the reactor finite element model; S502. Focus on medium and high frequencies and use asymmetric modal analysis to calculate multi-order modal frequencies and vibration shapes for the reactor finite element model; S503. The total modal participation factor of the two-step modal analysis should be no less than 80%.

16. The fluid-structure coupling seismic response analysis method for a liquid metal reactor according to claim 15, characterized in that: The response spectrum analysis comprises the following steps: S601: Calculate the 100th mode with a starting frequency of 0.1 Hz. Use the floor response spectrum at the pressure vessel support as input. Perform response spectrum analysis in the three orthogonal directions (X, Y, and Z) using the single-point response spectrum method. Calculate the model response separately. Then, use the square root sum method to combine the responses in the three directions to obtain the dynamic response of the reactor structure. The result is recorded as SL2_0.

1. S602. Calculate the 100th mode with a starting frequency of 5 Hz. Use the floor response spectrum at the pressure vessel support as input and perform response spectrum analysis in the three orthogonal directions (X, Y, and Z) using the single-point response spectrum method. Calculate the model response separately. Then, use the square sum square root method to combine the responses in the three directions to obtain the dynamic response of the reactor structure. The result is recorded as SL2_5. S603. Combine the results of SL2_0.1 and SL2_5 to finally obtain the results of earthquake dynamic analysis.

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