An analysis method for RPV structural mechanical response under IVR condition considering creep damage

Abstract

The application discloses an RPV structure mechanical response analysis method considering creep damage under IVR conditions, and comprises the following steps: performance test is conducted on RPV material to obtain performance parameters of the RPV material; and a finite element model of the RPV structure is established and simulated; wherein the simulation specifically comprises: executing a loop until the stress field distribution of the RPV structure at a specified creep time t i＝m is obtained. The application combines the creep damage and the elastic-plastic performance, and is favorable for making accurate mechanical response analysis on the RPV structure.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant safety assessment technology, and in particular to a method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions. Background Technology

[0002] In-Vessel Retention (IVR) under severe accident conditions t i During IVR (Indoor Reactor Warp Reduction), the structural integrity of the reactor pressure vessel (RPV) must be ensured. During IVR, the maximum temperature on the inner surface of the RPV may exceed its melting point of 1327°C, and the large temperature difference between the inner and outer walls will subject the RPV to significant thermal stress.

[0003] Under conditions of high temperature difference and high stress gradient, multiple deformation and failure mechanisms exist in RPV (Resin-Plated Veneer). The interaction between these mixed deformation and failure mechanisms must be considered. However, current testing of RPV materials still focuses on single failure modes, using these as the basis for model analysis, lacking elastoplastic constitutive models for RPV materials that consider creep damage. Furthermore, in finite element simulation studies of RPV structures, there is a lack of finite element simulation strategies that can account for the creep-induced effects on the elastoplastic properties of RPV materials.

[0004] Based on the above problems, there is a need for a structural mechanical response analysis method for RPV that considers creep damage under core melting conditions. Summary of the Invention

[0005] To address the technical problems existing in the background art, this invention proposes a method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions.

[0006] This invention proposes a method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions, comprising: Performance tests were conducted on RPV materials to obtain their performance parameters, including elastic-plastic parameters, elastic-plastic parameters after creep, creep damage, elastic-plastic degradation coefficient, and the linear relationship between creep damage and elastic-plastic degradation coefficient. Establish a finite element model of the RPV structure, set initial physical properties, loads and boundary conditions, and simulate the finite element model of the RPV structure; The simulation of the finite element model of the RPV structure specifically includes: Execute the loop until the specified creep time is reached. t i=m Stress field distribution of the RPV structure at that time; The loop body includes: Using the current initial elastoplastic parameters as initial conditions, the steady-state temperature field and creep time of the RPV structure are calculated as follows: t i The stress field distribution at time; where, i=1,2,3,…,m , m It is a positive integer greater than 10; t = t i+1 - t i , t It is a fixed value; Determine creep time t i Has the specified creep time been reached? t i=m ; When creep time t i Reaching the specified creep time t i=m At that time, the stress field distribution of the output RPV structure is displayed. When creep time t i The specified creep time has not been reached. t i=m At that time, based on the performance parameters of RPV material and the creep time... t i The steady-state temperature and stress field distributions of the RPV structure at different temperatures were calculated, and the creep time was obtained as follows: t i The creep-induced elastic-plastic parameters of the RPV structure at that time; The creep time at different temperatures is... t i The creep-induced elastic-plastic parameters of the RPV structure at time t are used as the creep time. t i+1 The initial elastoplastic parameters of the RPV structure at that time.

[0007] Preferably, performance tests are conducted on the RPV material to obtain its performance parameters, specifically including: Tensile tests were conducted on RPV material at different temperatures to obtain tensile curves at different temperatures; and based on the tensile curves at different temperatures, the elastic-plastic parameters of RPV material under different temperature conditions were obtained; among which, the elastic-plastic parameters include yield strength; Creep fracture tests were conducted on RPV materials under different temperatures and stresses to obtain the creep life and creep constitutive parameters of RPV materials. Based on the creep life of RPV material and the preset creep life prediction model, the creep life-temperature-stress relationship of RPV material is established. Creep interruption tensile tests were conducted on RPV materials under different temperatures and stresses to obtain the creep elastoplastic parameters of RPV materials after different creep times; among them, the creep elastoplastic parameters include the creep yield strength; Based on the creep life-temperature-stress relationship of RPV material, the creep damage of RPV material is obtained by the time fraction method. Based on the elastic-plastic parameters and creep-induced elastic-plastic parameters of the RPV material, the elastic-plastic degradation coefficient of the RPV material is obtained. Based on the creep damage and elastoplastic degradation coefficient of RPV material, a linear relationship between creep damage and elastoplastic degradation coefficient is established, that is, an elastoplastic constitutive model of RPV material considering creep damage is established.

[0008] Preferably, the parameters are based on the performance parameters of the RPV material and the steady-state temperature field and creep time of the RPV structure. t i The stress field distribution at time t, and the creep time at different temperatures were calculated as follows: t i Creep yield strength of RPV structure at time ， Specifically, it includes: Based on the steady-state temperature field and creep time of the RPV structure... t i The stress field distribution at that time was analyzed to obtain the temperature and stress of each node of the RPV structure. Based on the temperature and stress of each node in the RPV structure and the creep life-temperature-stress relationship of the RPV material, the creep time at different temperatures is obtained as follows: t i The creep lifetime of each node in the RPV structure at that time; Based on the creep time at different temperatures t i The creep lifetime and creep time of each node of the RPV structure at different temperatures were calculated, and the creep time at different temperatures was obtained. t i Creep damage at each node of the RPV structure during time; Based on the linear relationship between creep damage and the elastic-plastic deterioration coefficient, and the creep time at different temperatures, t i The creep damage of each node of the RPV structure at different temperatures was calculated, and the creep time was obtained as follows: t i The yield strength reduction coefficient of each node of the RPV structure at that time; The creep time at different temperatures was selected as follows: ti The maximum value among the yield strength reduction coefficients of each node of the RPV structure at that time; Using the maximum value as the elastoplastic degradation coefficient, and based on the elastoplastic degradation coefficient and the current initial elastoplastic parameters, the creep time at different temperatures is calculated. t i The creep elastic-plastic parameters of the RPV structure at that time are the creep yield strength.

[0009] Preferably, the creep life-temperature-stress relationship of the RPV material is as follows: ; In the formula, T Indicates temperature. t r Indicates creep life, s Indicates stress.

[0010] Preferably, the elastic-plastic degradation coefficient is =s cy / s y ; In the formula, display Elastic-plastic degradation coefficient, s cy Indicates the elastic-plastic parameters after creep. s y This represents the elastic-plastic parameter.

[0011] Preferably, creep damage is d c =t i / t r ； In the formula, d c Indicates creep damage ，t i Indicates creep time ，t r Indicates creep life.

[0012] Preferably, the linear relationship between creep damage and elastoplastic degradation coefficient is as follows: ; In the formula, Indicates the elastic-plastic degradation coefficient. d c Indicates creep damage. t i Indicates creep time ，tr Indicates creep life.

[0013] Preferably, the elastic-plastic parameters of the RPV material at different temperatures are obtained based on the tensile curves at different temperatures, specifically including: The tensile curves at different temperatures were fitted using a pre-defined elastoplastic model to obtain the elastoplastic parameters of the RPV material at different temperatures.

[0014] Preferably, the elastoplastic model includes one of the following: a bilinear isotropic elastoplastic model, an ideal elastoplastic model, and a Ramberg-Osgood elastoplastic model.

[0015] Preferably, the creep life prediction model includes the Larson-Miller model.

[0016] Preferably, the elastoplastic parameter also includes the elastic modulus, and the creep parameter also includes the creep elastic modulus.

[0017] The mechanical response analysis method of RPV structure considering creep damage under IVR conditions proposed in this invention combines creep damage with elastoplastic properties to establish an elastoplastic constitutive model considering creep damage. Applying this elastoplastic constitutive model considering creep damage to the simulation of the finite element model of RPV structure helps to improve the accuracy of the stress field distribution of RPV structure after a specified creep time, better determine the limit state of RPV structure under multiple failure modes, and provide technical support for analyzing the integrity of RPV structure under extreme conditions. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the mechanical response analysis method for RPV structures under IVR conditions considering creep damage in one embodiment of the present invention.

[0019] Figure 2 This represents the linear relationship between creep damage and elastoplastic degradation coefficients in one embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of a finite element model in one embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the stress distribution on the RPV wall surface under different creep times in one embodiment of the present invention. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] Reference Figure 1-4 The present invention proposes a method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions, comprising: Performance tests were conducted on RPV materials to obtain their performance parameters, including elastic-plastic parameters, elastic-plastic parameters after creep, creep damage, elastic-plastic degradation coefficient, and the linear relationship between creep damage and elastic-plastic degradation coefficient. Establish a finite element model of the RPV structure, set initial physical properties, loads and boundary conditions, and simulate the finite element model of the RPV structure; The simulation of the finite element model of the RPV structure specifically includes: Execute the loop until the specified creep time is reached. t i=m Stress field distribution of the RPV structure at that time; The loop body includes: Using the current initial elastoplastic parameters as initial conditions, the steady-state temperature field and creep time of the RPV structure are calculated as follows: t i The stress field distribution at time; where, i=1,2,3,…,m , m It is a positive integer greater than 10; t = t i+1 - t i , t It is a fixed value; Determine creep time t i Has the specified creep time been reached? t i=m ; When creep time t i Reaching the specified creep time t i=m At that time, the stress field distribution of the output RPV structure is displayed. When creep time t i The specified creep time has not been reached. t i=m At that time, based on the performance parameters of RPV material and the creep time... t i The steady-state temperature and stress field distributions of the RPV structure at different temperatures were calculated, and the creep time was obtained as follows: t i The creep-induced elastic-plastic parameters of the RPV structure at that time; The creep time at different temperatures is... t iThe creep-induced elastic-plastic parameters of the RPV structure at time t are used as the creep time. t i+1 The initial elastoplastic parameters of the RPV structure at that time.

[0024] This invention first conducts performance tests on the reactor pressure vessel (RPV) material to obtain its performance parameters. These parameters include elastoplastic parameters, elastoplastic parameters after creep, creep damage, elastoplastic degradation coefficient, and the linear relationship between creep damage and the elastoplastic degradation coefficient—that is, an elastoplastic constitutive model considering creep damage. These creep-informed performance parameters are then applied to the finite element model simulation of the RPV structure to obtain the performance parameters at a specified time. t i=m Stress field distribution of the RPV structure.

[0025] This invention combines creep damage with elastoplastic properties to establish an elastoplastic constitutive model that considers creep damage. Applying this elastoplastic constitutive model to the simulation of the finite element model of the RPV structure improves the accuracy of the stress field distribution of the RPV structure after a specified creep time, better determines the limit state of the RPV structure under multiple failure modes, and provides technical support for analyzing the integrity of the RPV structure under extreme conditions.

[0026] In this embodiment, the load and constraint boundary conditions include temperature and internal pressure.

[0027] In this embodiment, the initial physical properties include: density, specific heat capacity, thermal conductivity, coefficient of linear expansion, Poisson's ratio, creep life, creep constitutive parameters, and elastoplastic parameters.

[0028] In this embodiment, the elastoplastic parameter includes the yield strength, and the creep-induced elastoplastic parameter includes the creep-induced yield strength. Among them, based on the performance parameters of RPV material and the steady-state temperature field and creep time of RPV structure, t i The stress field distribution at time t, and the creep time at different temperatures were calculated as follows: t i Creep yield strength of RPV structure at time ， Specifically, it includes: Based on the steady-state temperature field and creep time of the RPV structure... t i The stress field distribution at time was obtained, and the temperature and stress of each node of the RPV structure were obtained. Based on the temperature of each node in the RPV structure T The creep life-temperature-stress relationship of RPV material, stress, and creep time at different temperatures were obtained. t iThe creep lifetime of each node in the RPV structure at that time; Based on the creep time at different temperatures t i The creep lifetime and creep time of each node of the RPV structure at different temperatures were calculated, and the creep time at different temperatures was obtained. t i Creep damage at each node of the RPV structure during time; Based on the linear relationship between creep damage and the elastic-plastic deterioration coefficient, and the creep time at different temperatures, t i The creep damage of each node of the RPV structure at different temperatures was calculated, and the creep time was obtained as follows: t i The yield strength reduction factor of each node of the RPV structure at that time; The creep time at different temperatures was selected as follows t i The maximum value among the yield strength reduction coefficients of each node of the RPV structure at that time; Using the maximum value as the elastoplastic degradation coefficient, and based on the elastoplastic degradation coefficient and the current initial elastoplastic parameters, the creep time at different temperatures is calculated. t i The creep elastic-plastic parameters of the RPV structure at that time are the creep yield strength.

[0029] In this embodiment, performance tests are conducted on the RPV material to obtain its performance parameters, specifically including: Tensile tests were conducted on RPV material at different temperatures to obtain tensile curves at different temperatures; and based on the tensile curves at different temperatures, the elastic-plastic parameters of RPV material under different temperature conditions were obtained; among which, the elastic-plastic parameters include yield strength; Creep fracture tests were conducted on RPV materials under different temperatures and stresses to obtain the creep life and creep constitutive parameters of RPV materials. Based on the creep life of RPV material and a pre-defined creep life prediction model, the creep life-temperature-stress relationship of RPV material is established. t r - T - s relation; Creep interruption tensile tests were conducted on RPV materials under different temperatures and stresses to obtain the creep elastoplastic parameters of RPV materials after different creep times; among them, the creep elastoplastic parameters include the creep yield strength. Based on the creep life-temperature-stress relationship of RPV material, the creep damage of RPV material is obtained by the time fraction method. Based on the elastic-plastic parameters and creep-induced elastic-plastic parameters of the RPV material, the elastic-plastic degradation coefficient of the RPV material is obtained. Based on the creep damage and elastoplastic degradation coefficient of RPV material, a linear relationship between creep damage and elastoplastic degradation coefficient is established, that is, an elastoplastic constitutive model of RPV material considering creep damage is established.

[0030] In this embodiment, the creep life-temperature-stress relationship of the RPV material is... t r - T - s Relationship, for ; In the formula, T Indicates temperature. t r Indicates creep life, s Indicates stress.

[0031] In this embodiment, the elastic-plastic degradation coefficient is =s cy / s y ; In the formula, display Elastic-plastic degradation coefficient, s cy Indicates the elastic-plastic parameters after creep. s y This represents the elastic-plastic parameter.

[0032] In this embodiment, creep damage is d c =t i / t r ； In the formula, d c Indicates creep damage ，t i Indicates creep time ，t r Indicates creep life.

[0033] In this embodiment, the linear relationship between creep damage and the elastoplastic degradation coefficient is as follows: ; In the formula, Indicates the elastic-plastic degradation coefficient. d c Indicates creep damage. ti Indicates creep time ，t r Indicates creep life.

[0034] In this embodiment, the elastic-plastic parameters of the RPV material at different temperatures are obtained based on the tensile curves at different temperatures, specifically including: The tensile curves at different temperatures were fitted using a pre-defined elastoplastic model to obtain the elastoplastic parameters of the RPV material at different temperatures.

[0035] In a further embodiment, the elastoplastic model includes one of a bilinear isotropic elastoplastic model, an ideal elastoplastic model, and a Ramberg-Osgood elastoplastic model.

[0036] In this embodiment, the creep life prediction model includes, but is not limited to, the Larson-Miller model.

[0037] In a further specific embodiment, based on a preset creep life prediction model and the creep life and creep constitutive parameters of the RPV material, the creep life-temperature-stress relationship of the RPV material is established, specifically including: Utilizing different temperatures T and stress s Creep life of RPV materials under certain conditions t r , fitting The parameters in the formula are obtained respectively. k 0 and k 1 .

[0038] In this embodiment, the elastoplastic parameter also includes the elastic modulus, and the creep parameter also includes the creep elastic modulus. Therefore, it can be seen that for the elastic modulus... E RPV materials, which are also significantly affected by creep, will have a lower elastic modulus. E Adding it as another parameter to this mechanical response analysis method makes the mechanical response analysis results more accurate.

[0039] The following description will be based on a specific embodiment.

[0040] Example 1 The mechanical response analysis method includes: S1. Conduct tensile tests on RPV materials at different temperatures to obtain tensile curves; fit the curves using a bilinear isotropic elastoplastic model to obtain the tensile curves at different temperatures. T Elastic-plastic parameters (yield strength) of RPV material under certain conditions s y In this embodiment, the RPV material is SA508-3 steel. S2, Conduct different temperatures T ,stress s Creep life of SA508-3 steel was obtained by horizontal creep rupture test. t r And creep constitutive parameters, and based on the Larson-Miller creep model, establish the material's... t r - T - s relation( t r = f ( T, s )),Right now ; S3. Conduct the same temperature test as in step S2, comparing the creep rupture test conditions. T and stress s Creep interruption tensile test was conducted to obtain different creep times. t i Elastic-plastic properties of post-RPV materials (yield strength after creep) s cy )； S4. Determine creep damage in creep interruption tests based on the time fraction method. d c ( d c = t i / t r ); S5. Based on the data obtained in steps S1 and S3, obtain different temperatures. T ,stress s Creep time t i The elastic-plastic degradation coefficient of the lower RPV material ( = s cy / s y ); S6. Based on steps S4 and S5, establish creep damage. d c and elastic-plastic degradation coefficient The linear relationship, that is , specifically Figure 2 As shown; S7. Based on steps S1 and S2, input the initial physical property parameters of the RPV material in ABAQUS, specifically including density, specific heat capacity, thermal conductivity, coefficient of linear expansion, elastic modulus, Poisson's ratio, creep life, creep constitutive parameters, and plasticity parameters. Establish an axisymmetric finite element model of the RPV structure, such as Figure 3 As shown; temperature boundary conditions are applied to the inner and outer surfaces of the cylinder, i.e., the inner surface, due to the action of the core melt, is assumed to have a temperature of 1500℃, and the outer surface, due to the heat transfer from the core pool boiling of the reactor cavity water, is assumed to have a temperature of 150℃; simultaneously, axial displacement constraints are applied to the upper end face of the cylinder, i.e. U When z=0, a tangential displacement constraint is applied to the left end face of the lower head, i.e. Ux =0, calculate the steady-state temperature field and creep time of the RPV structure. t i=1 =Stress field distribution at 1 hour; S8. Export the nodes of the RPV structure obtained in step S7. n temperature T ,stress s data; S9. Move the nodes from step S8. n temperature T ,stress s Substitute the data into step S2 to obtain the 1-hour time node. n Corresponding creep life t r ; S10. Based on the creep life obtained in step S9 t r ,make t i=1 =1 hour, substitute into step S4 to determine the 1-hour time node. n creep damage d ci ; S11, the result obtained in step S10 d ci Substitute into step S6 to obtain the 1-hour time node. n Yield strength weakening coefficient ; S12, Select those with the same temperature T Yield strength reduction coefficient of each node maximum value ,Will Substitute into step S5 to obtain the different temperatures over 1 hour. T Yield strength after creep s cyi ; S13, Measure different temperatures over 1 hour T Yield strength after creep s cyi Update the initial elastoplastic parameters in step S7, let t i+1 = ti+ t , t = 1 hour, repeat steps S7-S12 until the specified calculation time is 60 hours, i.e. t i=60 Finally, the stress distribution of the RPV structure at a specified time is obtained, and the stress distribution on the RPV wall at the specified time is as follows: Figure 4 As shown.

[0041] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for analyzing the mechanical response of an RPV structure considering creep damage under IVR conditions, characterized in that, include: Performance tests were conducted on RPV materials to obtain their performance parameters, including elastic-plastic parameters, elastic-plastic parameters after creep, creep damage, elastic-plastic degradation coefficient, and the linear relationship between creep damage and elastic-plastic degradation coefficient. Establish a finite element model of the RPV structure, set initial physical properties, loads and boundary conditions, and simulate the finite element model of the RPV structure; The simulation of the finite element model of the RPV structure specifically includes: Execute the loop until the specified creep time is reached. t i=m Stress field distribution of the RPV structure at that time; The loop body includes: Using the current initial elastoplastic parameters as initial conditions, the creep time is calculated as follows: t i The steady-state temperature and stress field distributions of the RPV structure at that time; among which, i=1,2,3,…,m , m It is a positive integer greater than 10; t = t i+1 - t i , t It is a fixed value; Determine creep time t i Has the specified creep time been reached? t i=m ; When creep time t i Reaching the specified creep time t i=m At that time, the stress field distribution of the output RPV structure is displayed. When creep time t i The specified creep time has not been reached. t i=m At that time, based on the performance parameters of RPV material and the creep time... t i The steady-state temperature and stress field distributions of the RPV structure at different temperatures were calculated, and the creep time was obtained as follows: t i The creep-induced elastic-plastic parameters of the RPV structure at that time; The creep time at different temperatures is... t i The creep-induced elastic-plastic parameters of the RPV structure at time t are used as the creep time. t i+1 The initial elastoplastic parameters of the RPV structure at that time; The performance testing process includes: Tensile tests were conducted on RPV materials at different temperatures to obtain tensile curves at different temperatures. Based on the tensile curves at different temperatures, the elastoplastic parameters of RPV materials under different temperature conditions were obtained. Among them, the elastoplastic parameters include yield strength. Creep fracture tests were conducted on RPV materials under different temperatures and stresses to obtain the creep life and creep constitutive parameters of RPV materials. Based on the creep life of RPV material and a pre-defined creep life prediction model, the creep life-temperature-stress relationship of RPV material is established. Creep-interrupted tensile tests are conducted on RPV material at different temperatures and stresses to obtain the post-creep elastoplastic parameters of RPV material after different creep times. These post-creep elastoplastic parameters include the post-creep yield strength. Based on the creep life-temperature-stress relationship of RPV material, the creep damage of RPV material is obtained using the time fraction method. Based on the elastoplastic parameters of RPV material and the post-creep elastoplastic parameters, the elastoplastic degradation coefficient of RPV material is obtained. Based on the creep damage and the elastoplastic degradation coefficient of RPV material, a linear relationship between creep damage and the elastoplastic degradation coefficient is established, i.e., an elastoplastic constitutive model of RPV material considering creep damage is established. The calculation process for the elastic-plastic parameters after creep includes: Based on the steady-state temperature field and creep time of the RPV structure... t i The stress field distribution at different temperatures was analyzed to obtain the temperature and stress at each node of the RPV structure. Based on the temperature and stress at each node of the RPV structure and the creep life-temperature-stress relationship of the RPV material, the creep time at different temperatures was obtained. t i The creep lifetime of each node of the RPV structure at different temperatures; the creep time is based on the creep time at different temperatures. t i The creep lifetime and creep time of each node of the RPV structure at different temperatures were calculated, and the creep time at different temperatures was obtained. t i Creep damage at each node of the RPV structure during time; Based on the linear relationship between creep damage and the elastic-plastic deterioration coefficient, and the creep time at different temperatures, t i The creep damage of each node of the RPV structure at different temperatures was calculated, and the creep time was obtained as follows: t i The yield strength attenuation coefficient of each node in the RPV structure at different temperatures was determined; the creep time at different temperatures was selected. t i The maximum value among the yield strength reduction coefficients of each node of the RPV structure at that time is used as the elastic-plastic degradation coefficient. Based on the elastic-plastic degradation coefficient and the current initial elastic-plastic parameters, the creep time at different temperatures is calculated. t i The creep-induced elastic-plastic parameters of the RPV structure at that time.

2. The method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions according to claim 1, characterized in that, The creep life-temperature-stress relationship of RPV materials is as follows: ； In the formula, T Indicates temperature. t r Indicates creep life, σ Indicates stress.

3. The method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions according to claim 1, characterized in that, The elastic-plastic degradation coefficient is =σ cy / σ y ； In the formula, express Elastic-plastic degradation coefficient, σ cy Indicates the elastic-plastic parameters after creep. σ y This represents the elastic-plastic parameter.

4. The method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions according to claim 1, characterized in that, Creep damage is d c =t i / t r ； In the formula, d c Indicates creep damage ，t i Indicates creep time ，t r Indicates creep life.

5. The method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions according to claim 1, characterized in that, The linear relationship between creep damage and elastoplastic degradation coefficient is as follows: ； In the formula, Indicates the elastic-plastic degradation coefficient. d c Indicates creep damage. t i Indicates creep time ，t r Indicates creep life.

6. The method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions according to claim 1, characterized in that, Based on the tensile curves at different temperatures, the elastic-plastic parameters of the RPV material at different temperatures were obtained, specifically including: The tensile curves at different temperatures were fitted using a pre-defined elastoplastic model to obtain the elastoplastic parameters of the RPV material at different temperatures. The elastoplastic model included one of the following: a bilinear isotropic elastoplastic model, an ideal elastoplastic model, and a Ramberg-Osgood elastoplastic model.

7. The method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions according to claim 1, characterized in that, Creep life prediction models include the Larson-Miller model.

8. The method for analyzing the mechanical response of RPV structures considering creep damage under IVR conditions according to claim 1, characterized in that, Elastic-plastic parameters also include the elastic modulus, and creep parameters also include the creep elastic modulus.

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