A method and system for evaluating the safety of a nuclear power plant gate O-ring under aging conditions

Abstract

The application belongs to the technical field of nuclear power, and discloses a kind of aging condition nuclear power gate O-ring safety evaluation method and system, numerical test method allows researcher to obtain permanent compression rate at the same time, the change rule of contact stress and contact width with time is obtained. In this way, combined with the accurate interface leakage rate model, the change rule of interface leakage rate with time can be predicted. For the nuclear power gate with strict leakage rate control requirements, it is not difficult to obtain the corresponding permanent compression rate through the maximum allowable leakage rate based on the above method. The permanent compression rate life criterion obtained by the method has clear physical meaning, and can quickly and conveniently guide the gate safety design and reliability evaluation through aging research. The application establishes the relationship between permanent compression rate and dimensionless contact stress based on the finite element method, which can assist experimental research and expand the application of experimental results.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power technology, and in particular relates to a method and system for safety assessment of O-rings of nuclear power plant gates under aging conditions. Background Technology

[0002] Large-diameter gates, such as personnel and equipment gates, provide access for personnel and equipment to and from the containment building and are an important component of the containment's radioactive containment. They are typically sealed using rubber O-rings. However, rubber materials are prone to aging under high temperatures and radiation conditions, leading to a degradation in sealing performance and posing potential safety risks. Therefore, personnel and equipment gates have always been a key focus in containment sealing and integrity studies.

[0003] Sandia Laboratories conducted severe accident tests on personnel and equipment gates. The results showed that significant leakage occurred when the rubber compression rebound could not compensate for the flange face separation displacement. Kulak et al. conducted a finite element study on the leakage rate of a gate, concluding that the permanent compression ratio—a physical quantity reflecting the compression rebound characteristics of rubber materials—is a significant influencing factor on the leakage rate. By definition, when the permanent compression ratio is 100%, the rubber seal completely loses its resilience and ceases to have sealing capability. Nakano et al., in evaluating the performance of irradiated rubber seals, set a compression ratio of 90% as the failure limit for irradiated aging rubber materials. Domestically, to allow sufficient tolerance, a very low permanent compression ratio is usually selected as the life criterion for rubber O-rings. For example, GB / T 20028-2005 stipulates that a 50% change in physical properties after rubber aging is the critical value for seal failure, and CN201611174320 proposes that a permanent compression ratio ε≥40% be used as the critical standard for seal failure. It can be seen that permanent compression ratio, as an indicator of the compression and rebound characteristics of rubber materials, has significant advantages in assessing the long-term service life of O-rings, and there are already mature testing methods and numerous research results. However, because it cannot be directly linked to sealing performance, establishing quantitative service life criteria based on permanent compression ratio has limitations; too high a value implies insufficient safety, while too low a value implies reduced economic efficiency.

[0004] Leakage rate can intuitively evaluate the safety performance of nuclear power plant gate sealing structures. It is related to various factors such as sealing medium, contact stress, and aging characteristics of sealing materials. CN204944760U proposes a personnel gate overall sealing performance test device that can simulate LOCA accidents or pressure tests. It achieves rapid and accurate online detection of the overall sealing performance of personnel gates through a gas path connection method with separate pressure charging / depressurization and pressure measurement points and dedicated leakage rate measurement software. (Change reference) However, this method cannot be combined with permanent compression ratio and cannot reflect the aging performance of rubber. Wang Lina et al. used permanent compression ratio as an aging evaluation index and adopted a combination of experimental and theoretical methods to study the influence of relaxation effect and average sealing force. They further established the relationship between average sealing force and leakage rate through sealing experiments under different compression ratios, and finally obtained a semi-empirical life assessment model based on leakage rate. However, this model requires the use of experimental empirical parameters, which limits its application and promotion.

[0005] Based on the above analysis, the problems and defects of the existing technology are as follows: Existing large-diameter gates usually use rubber O-rings for sealing. Under high temperature and irradiation conditions, rubber materials are prone to aging, which leads to a degradation of sealing performance and brings potential safety risks. Summary of the Invention

[0006] To address the problems of existing technologies, this invention proposes a method for establishing a quantitative relationship between permanent compressibility and leakage rate based on numerical experiments. The numerical experimental method allows researchers to obtain the permanent compressibility while simultaneously determining the changes in contact stress and contact width over time. Thus, combined with an accurate interface leakage rate model, the change in interface leakage rate over time can be predicted. For nuclear power plant gates with strict leakage rate control requirements, it is not difficult to determine the corresponding permanent compressibility from the maximum allowable leakage rate. The permanent compressibility lifetime criterion obtained based on this invention has clear physical meaning and can quickly and conveniently guide gate safety design and reliability assessment through aging studies.

[0007] The essential technical feature of this solution lies in providing a systematic method for evaluating the safety of O-rings for nuclear power plant valves under aging conditions. This method first obtains the thermophysical properties and stress relaxation parameters of the O-ring rubber material through experimental measurements. Then, it establishes a hyperelastic constitutive equation and a viscoelastic model to describe the deformation and aging creep characteristics of the rubber. Next, it conducts permanent deformation simulation experiments using the finite element method, and verifies the accuracy of the simulation model through actual compression deformation test results. Furthermore, this method involves extensive numerical simulations of permanent compression deformation, as well as establishing a permanent compression ratio function based on the initial compression ratio, aging temperature, and aging time. Finally, through comprehensive analysis and data fitting, the relationship between the permanent compression ratio and the leakage rate is established, providing a scientific basis for the safety assessment of nuclear power plant valve O-rings under different aging conditions.

[0008] This invention is implemented as follows: a method for safety assessment of O-rings on nuclear power plant valves under aging conditions, comprising:

[0009] S1. Based on the experimental measurement of the thermophysical parameters and stress relaxation parameters of rubber materials, a hyperelastic constitutive equation describing the deformation characteristics of rubber under thermo-mechanical coupling conditions and a viscoelastic model reflecting the aging and creep characteristics of rubber are established. On this basis, the finite element analysis method is applied to carry out simulation experiments of permanent deformation of O-rings. The simulation experiments are compared with the actual compression deformation test results to verify the accuracy of the finite element analysis method.

[0010] S2, based on the finite element analysis process of S1, continuously changes the initial compression ratio C. i Aging temperature T and aging time τ are used to obtain sufficient permanent compressibility (CS) data. CS is set as the aging evaluation index, and based on the aging kinetic equation and Aronius formula, different initial compressibility values ​​(CS) are established. i Below, the functional relationship between the CS of the O-ring and the aging temperature T and aging time τ is: CS = f(T, τ);

[0011] S3, based on the finite element analysis process of S1, simultaneously outputs different initial compression ratios C. i The contact stress S at aging temperature T and aging time τ = 0 G0 And the contact width B, and fit their relationship: S G0 = f(C i , T) and B = f(C) i ,T);

[0012] S4, based on the finite element analysis process of S1, simultaneously outputs different initial compression ratios C. i The average contact stress S at the O-ring contact interface under different aging temperatures T G The variation law of aging time; with the initial contact stress S G0 Contact stress S G Dimensionless transformation, establishing dimensionless contact stress S G / S G0 With initial compression ratio C i The functional relationship between aging temperature T and aging time τ;

[0013] S5, organize the data obtained from S2-S4, and apply the initial compression ratio C. i The relationship between aging temperature T and aging time τ was established, and the relationship between permanent compressibility CS and dimensionless contact stress S was established. G / S G0 The correspondence between the two is fitted using the following transformation formula: CS = f(S) G / SG0 );

[0014] S6 simulates the flow in rough leakage channels with different roughnesses and heights at the mesoscale through interface leakage flow simulation. It fits the relationships between roughness flow factor and surface condition of the rough channel, and between height flow rate and leakage channel height. Then, based on the calculation formula for smooth leakage channels, it connects the flow factor at the mesoscale with the leakage rate at the macroscale. Simultaneously, based on microscopic contact analysis, it establishes the relationship between leakage channel height and contact stress. Finally, by combining the fitted equations, it establishes the relationship between the gate O-ring leakage rate Q and contact stress S under the specified operating conditions. G Relationship: Q = f(S) G );

[0015] S7, with average contact stress S G Using the intermediate variable, establish the relationship between the permanent compressibility CS and the leakage rate Q: CS = f(Q);

[0016] S8, Safety Assessment: Given operating conditions (initial compression rate C) i The permanent compressibility of the gate is calculated using S1-S6 (pressure P, temperature T, and aging time τ) or by directly measuring the permanent compressibility of the O-ring after use. The maximum permissible permanent compressibility is calculated based on the allowable leakage rate of the containment gate, and this is used as a safety criterion to assess the safety of the gate under accident conditions.

[0017] Furthermore, S1 represents the measured material parameters. A finite element analysis model is established and compared with experimental results to verify the model's effectiveness. This process includes the following steps:

[0018] S101. Obtain the material parameters of the rubber O-ring through experimental measurement. The specific methods are as follows: (1) Obtain the physical property parameters such as thermal expansion coefficient, thermal conductivity, density, and specific heat capacity that change with time by experiment; (2) Conduct uniaxial tensile test to monitor the hyperelasticity of the material, select a suitable constitutive equation to fit the experimental data, and obtain the hyperelastic parameters; (3) Use the DMA method to obtain the viscoelastic data of the material, and fit the experimental data according to the Prony series to obtain the viscoelastic parameters.

[0019] S102. Establish a finite element model and obtain the permanent compressibility CS data of the O-ring through both finite element method and experimental method. Verify the effectiveness of the model by comparing the two. The specific methods are as follows: (1) Establish a finite element analysis model of the sealing structure; (2) Input the material parameters of the O-ring, including physical property parameters and hyperelastic and viscoelastic parameters; (3) Achieve the initial compressibility C of the finite element analysis by applying displacement. i(3) Set the ambient temperature T to simulate the working temperature of the O-ring, and set the aging time τ of multiple O-rings; (4) According to the set working conditions, perform stress relaxation finite element analysis on the O-ring to obtain the permanent compression ratio CS of the O-ring; (5) Change the temperature T and repeat the above steps to obtain multiple sets of corresponding values ​​of CS and aging time τ; (6) Under the set working conditions of the finite element analysis, conduct actual compression permanent deformation experiments to obtain real permanent compression ratio data, and compare it with the finite element analysis data to verify the accuracy of the finite element method; (7) When the data has a large deviation, adjust the model settings and boundary conditions of the finite element analysis, repeat (1)-(6), and correct the finite element method.

[0020] Furthermore, S2 establishes a functional relationship between the permanent compression ratio CS of the O-ring and the aging temperature and aging time, based on a large amount of numerical simulation data on permanent compression deformation, given an initial compression ratio. Specifically, this includes the following steps:

[0021] S201. Based on the finite element analysis process of S1, the initial compression ratio C is set. i The permanent compressibility CS data is obtained based on finite element analysis. The specific method is as follows: (1) Select multiple working conditions according to actual needs and set different initial compressibility CS. i (1) Aging temperature T and aging time τ; (2) According to the set working conditions, perform stress relaxation finite element analysis on the O-ring to obtain the permanent compression ratio CS of the O-ring;

[0022] S202. Based on the aging kinetic equation and the Arrhenius formula, different initial compression ratios C are fitted. i The relationship between the permanent compressibility CS of the O-ring and temperature T and aging time τ is: CS = f(T, τ).

[0023] Furthermore, S3 represents the initial contact stress S of the O-ring at the initial moment (before stress relaxation begins), obtained from a permanent compression deformation simulation experiment. G0 And the contact width B, and establish the relationship between the two with respect to the initial compression ratio C. i The functional relationship between the aging temperature T and the aging temperature includes the following steps: (1) Select multiple working conditions according to actual needs and set different initial compression ratios C. i 1. Aging temperature T; (2) According to the set working conditions, perform finite element analysis of S1 for the O-ring; (3) Before performing relaxation analysis on the material, i.e. when the aging time τ = 0, record the initial contact stress S at different temperatures. G0 and contact width B; (4) Select an appropriate function form and fit S respectively G0 and B and C i Relationship with T: S G0 = f(C i, T) and B = f(C) i , T).

[0024] Furthermore, S4 is the dimensionless contact stress S during the permanent deformation process of the O-ring, established using the finite element analysis method of S1. G / S G0 The functional relationship is expressed by the following steps:

[0025] (1) Select multiple working conditions according to actual needs and set different initial compression ratios C. i 1. Aging temperature T; (2) According to the set working conditions, perform finite element analysis of S1 for the O-ring; (3) Output different initial compression ratios C i S under different aging temperatures T and different aging times τ G (4) Initial contact stress S corresponding to the same compression ratio and the same aging temperature G0 Let the dimensionless contact stress S be defined as a characteristic quantity. G / S G0 (5) Place S G / S G0 As an indicator of aging performance, S is established using the aging kinetic equation and the Aronius formula. G / S G0 The functional form of aging temperature T and aging time τ; (6) The S obtained from S3 G0 =f(C i , T) and S G / S G0 By combining f(T, τ) with the thermo-mechanical coupling, S can be obtained. G Calculation formula: .

[0026] Furthermore, S5 represents the fitting of the permanent compressibility CS and the dimensionless contact stress S. G / S G0 The relationship between them includes the following steps:

[0027] (1) Given an initial compression ratio C i The permanent compressibility CS and dimensionless contact stress S obtained from S1 and S4 G / S G0 Relationship between CS and S G / S G0 The correspondence between the two was found to be linearly correlated; (2) the initial compression ratio C was changed. i Multiple sets of different C were obtained. i CS and S G / S G0 The corresponding data. C was found. iThe influence on the relationship between the two can be ignored. (3) Based on the numerical results, fit CS and S. G / S G0 The relation is: CS = f(S) G / S G0 ).

[0028] Furthermore, S6 establishes the relationship between the gate O-ring leakage rate Q and the contact stress S based on the interface leakage mechanism. G The relationship specifically includes the following steps:

[0029] S601. Based on interface leakage flow simulation, establish the relationship between leakage rate Q and geometric parameters, operating parameters, surface roughness, and actual height of the leakage channel: The specific method is as follows: (1) Obtain rough surface characteristic parameters, such as roughness σ and autocorrelation length A, by performing microscopic morphology analysis on the machined surface. T (2) Establish a rough leakage channel with a height of h0 composed of multiple surfaces with different roughness characteristics, and perform numerical simulation of interface leakage flow; (3) Simulate the flow conditions of the leakage channel and fit the roughness flow factor Φ. σ With σ and A T (3) Obtain the relationship between surface roughness and flow characteristics of sealing interface; (4) Establish rough leakage channels with different separation heights h composed of multiple surfaces with the same roughness characteristics; (5) Simulate the flow conditions of leakage channels and fit the height flow factor Φ. h (6) Establish the formula for calculating the leakage rate of the sealing interface: Q=Φ σ ×Φ h ×Q p Q p For a leakage channel with a height of h0 (the channel height corresponding to zero contact stress) formed by a smooth surface, the formula can be extended from the mesoscopic to the macroscopic level; for O-rings, Q p Poiseuille's law, which describes the flow between parallel plates, can be used for calculation. In this case, the geometry of the leakage channel is the O-ring contact width B and average circumference L, and the pressure difference is the pressure difference P between the inside and outside of the O-ring. Finally, we can obtain: Q = f(B, P, σ, A) T , h);

[0030] S602. Based on the microscopic characteristics of the rough surface, establish an n×n rough peak model, with a rough peak radius of σ and a rough peak spacing of A. T Based on the microscopic contact mechanics method, the microscopic contact of a rough surface is simulated, and the relationship between the actual height h of the leakage channel and the contact stress S is established. G Relationship: h = f(S) G );

[0031] S603. By combining the formulas obtained from steps S601-S602, establish the relationship between the gate O-ring leakage rate Q and the contact stress S under the specified operating conditions. G Relationship: Q = f(S) G ).

[0032] Furthermore, S7 combines the formulas from S1 to S5 to establish the relationship between the permanent compressibility CS and the leakage rate Q: CS = f(Q);

[0033] Furthermore, S8 assesses the safety performance of the containment gate under accident conditions using the allowable leakage rate as a safety criterion. This includes the following steps:

[0034] S801. According to international or industry standards, the maximum permissible leakage rate specified in the standard shall be used as the leakage rate limit Q of the gate O-ring. lim Based on the relationship between leakage rate Q and permanent compression ratio CS in S6, a long-term sealing performance evaluation criterion is proposed: CS ≤ CS lim ;

[0035] S802. Based on the measured permanent compression ratio CS, the safety performance of the O-ring is judged according to the evaluation criteria. The specific method is as follows: (1) Given the initial compression ratio C of the gate O-ring. i (2) Using the obtained relationship, establish the relationship between the permanent compressibility CS and the leakage rate Q of the gate O-ring; lim Convert to permanent compression ratio limit CS lim (3) Calculate its permanent compressibility CS by actual measurement or based on operating conditions; (4) According to the evaluation criterion CS ≤ CS lim Determine the safety status of the O-ring.

[0036] Another object of the present invention is to provide a safety assessment system for O-rings of nuclear power plant valves under aging conditions, which applies the aforementioned safety assessment method for O-rings of nuclear power plant valves under aging conditions, comprising:

[0037] The finite element analysis module is used to establish a hyperelastic constitutive equation describing the deformation characteristics of rubber under thermo-mechanical coupling conditions and a viscoelastic model reflecting the aging and creep characteristics of rubber based on experimental measurements of the thermophysical properties and stress relaxation parameters of rubber materials. On this basis, the finite element analysis method is applied to carry out simulation experiments of permanent deformation of O-rings. The simulation experiments are compared with the actual compression deformation test results to verify the accuracy of the finite element analysis method.

[0038] The permanent compressibility data acquisition module is used to continuously change the initial compressibility C based on the finite element analysis process. iAging temperature T and aging time τ are used to obtain sufficient permanent compressibility data; CS is set as the aging evaluation index, and different initial compressibility values ​​C are established according to the aging kinetic equation and Aronius formula. i Below, the functional relationship between the CS of the O-ring and the aging temperature T and aging time τ is: CS = f(T, τ);

[0039] The relational fitting module is used to simultaneously output different initial compression ratios C based on the finite element analysis process. i The contact stress S at aging temperature T and aging time τ = 0 G0 And the contact width B, and fit their relationship: S G0 = f(C i , T) and B = f(C) i , T);

[0040] The relation establishment module is used to simultaneously output different initial compression ratios C based on the finite element analysis process. i The average contact stress S at the O-ring contact interface under different aging temperatures T G The variation law of aging time; with the initial contact stress S G0 Contact stress S G Dimensionless transformation, establishing dimensionless contact stress S G / S G0 With initial compression ratio C i The functional relationship between aging temperature T and aging time τ;

[0041] The conversion formula fitting module is used to process the obtained data and apply it to the initial compression ratio C. i The relationship between aging temperature T and aging time τ was established, and the relationship between permanent compressibility CS and dimensionless contact stress S was established. G / S G0 The correspondence between the two is fitted using the following conversion formula: CS = f(S G / S G0 );

[0042] The relational equation module is used to simulate the flow in rough leakage channels with different roughnesses and heights at the mesoscale through interface leakage flow simulation. It fits the relationships between roughness flow factor and surface condition of rough channels, and between height flow rate and leakage channel height. Then, based on the calculation formula for smooth leakage channels, it links the mesoscale flow factor with the macroscale leakage rate. Simultaneously, based on microscopic contact analysis, it establishes the relationship between leakage channel height and contact stress. Finally, by combining the fitted equations, it establishes the relationship between the gate O-ring leakage rate Q and contact stress S under specified operating conditions. G Relationship: Q = f(S) G );

[0043] The safety assessment module is used for a given operating condition (initial compression rate C). i The permanent compressibility of the gate is calculated using S1-S6 (pressure P, temperature T, and aging time τ) or by directly measuring the permanent compressibility of the O-ring after use. The maximum permissible permanent compressibility is calculated based on the allowable leakage rate of the containment gate, and this is used as a safety criterion to assess the safety of the gate under accident conditions.

[0044] Another object of the present invention is to provide a computer device, the computer device including a memory and a processor, the memory storing a computer program, which, when executed by the processor, causes the processor to perform the steps of the method for safety assessment of nuclear power plant gate O-rings under aging conditions.

[0045] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the nuclear power plant gate O-ring safety assessment method under aging conditions.

[0046] Another objective of this invention is to provide an information data processing terminal for implementing the aforementioned safety assessment system for nuclear power plant gate O-rings under aging conditions.

[0047] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0048] First, this invention proposes a method that combines numerical research on permanent compression ratio and leakage rate, and establishes a quantitative relationship between leakage rate and permanent compression ratio under aging conditions, thus solving the problem that permanent compression ratio cannot be used to quantitatively guide the assessment of seal life.

[0049] Based on the quantitative relationship established by this invention, the maximum permissible permanent compressibility can be calculated using the maximum permissible leakage rate as a basis. This serves as a safety evaluation index, directly linked to the nuclear power plant containment design guidelines, significantly improving the accuracy of safety assessments.

[0050] Secondly, the safety assessment method proposed in this invention links the aging of materials with sealing performance, and can quickly and accurately determine the safety status at this time according to the criteria, which is more conducive to revealing the influence of various factors; at the same time, it can also provide guidance for improving the safety design of sealing structures.

[0051] The relational fitting module and relational establishment module proposed in this invention are based on theoretical models incorporating multiple physical mechanisms, effectively revealing the quantitative relationships between physical quantities, and are the key technologies of this invention. Based on this key technology, for a given sealing structure and sealing material, the model can be directly applied to calculate the impact of high-temperature aging on the leakage rate and determine safety, without the need for repeated numerical calculations.

[0052] Third, the expected benefits and commercial value of the technical solution of this invention after its transformation are as follows: Predicting sealing performance under aging conditions is of great significance to nuclear safety. Safety has historically been ensured at the expense of economic efficiency and shortened service life. After the technical solution of this invention is transformed, the service life of O-rings can be assessed more accurately, potentially improving the economics of gate sealing design. Simultaneously, theoretical guidance for experiments can reduce the number of tests or maximize the application scope of the test results.

[0053] The technical solution of this invention solves a long-standing but unresolved technical problem: it addresses the inability to quantify the use of permanent compressibility to guide the assessment of seal life. The proposed approach, combining numerical methods for permanent compressibility and leakage rate, links material aging with sealing performance. This not only guides the selection of sealing structures and determines the safety status of seals under accident conditions based on nuclear power plant containment design guidelines, but also reveals the influence patterns of various factors.

[0054] Fourth, the significant technological advancements of the nuclear power plant gate O-ring safety assessment method under aging conditions provided by this invention are reflected in the following aspects:

[0055] 1) Enhanced model accuracy:

[0056] By combining experimental measurements and finite element analysis, this method can more accurately simulate and predict the behavior of O-rings under actual working conditions. This combination of experimentation and simulation improves the accuracy of predicting O-ring performance, especially under complex aging conditions.

[0057] 2) Comprehensive assessment of the effects of aging:

[0058] This method, using aging kinetic equations and the Arrhenius formula, can systematically evaluate the effects of aging temperature and time on O-ring performance. This provides an important tool for understanding and predicting the aging behavior of materials during long-term operation.

[0059] 3) Improved security assessment:

[0060] By comprehensively analyzing the permanent compressibility and leakage rate of O-rings, this method can provide a more complete safety assessment. This is crucial for ensuring the reliability and safety of nuclear power plant gates under extreme conditions.

[0061] 4) Detailed parameter analysis capabilities:

[0062] The method allows for detailed analysis of different initial compression ratios, aging temperatures, and aging times, thereby enabling a more precise determination of the specific impact of these parameters on O-ring performance.

[0063] 5) Optimized structural design guidance:

[0064] By deeply analyzing the behavior of O-rings under different conditions, this method is not only applicable to safety assessments, but also provides a scientific basis for the structural design and material selection of O-rings for nuclear power plant gates, thereby optimizing their performance.

[0065] The safety assessment method for nuclear power plant gate O-rings under aging conditions provided by this invention has brought significant technological progress in improving assessment accuracy, comprehensively understanding the impact of material aging, and strengthening the safety assurance of nuclear power plants. Attached Figure Description

[0066] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0067] Figure 1 This is a flowchart illustrating the implementation of the nuclear power plant gate O-ring safety assessment method based on permanent compressibility provided in this embodiment of the invention.

[0068] Figure 2 This is a schematic diagram of a rough channel provided in an embodiment of the present invention; wherein, (a) the same height but different roughness, and (b) the same roughness but different height;

[0069] Figure 3 This is a schematic diagram of an ideal leakage path for an O-ring provided in an embodiment of the present invention;

[0070] Figure 4 This is a schematic diagram of the long-term relaxation characteristic analysis step settings provided in the embodiment of the present invention; wherein, (a) combination, (b) compression, (c) heating, (d) relaxation, and (e) unloading;

[0071] Figure 5 This is a comparison chart of simulation and experiment provided in the embodiments of the present invention;

[0072] Figure 6 This is a schematic diagram illustrating the relationship between permanent compression ratio and temperature and aging time provided in an embodiment of the present invention;

[0073] Figure 7 The different C provided in the embodiments of the present inventioni S below G0 A diagram showing the data corresponding to T;

[0074] Figure 8 The embodiments of the present invention provide S at different temperatures G Schematic diagram showing the variation with τ;

[0075] Figure 9 This is the S provided in the embodiments of the present invention. G / S G0 - A graph showing the relationship between T and τ;

[0076] Figure 10 The embodiments of the present invention provide CS and S under different compression ratios. G / S G0 A unified diagram illustrating the relationships between them;

[0077] Figure 11 This is a roughness flow factor fitting curve provided in an embodiment of the present invention;

[0078] Figure 12 This is a height flow factor fitting curve provided in an embodiment of the present invention;

[0079] Figure 13 This is a diagram showing the simulation results of microscopic contact mechanics provided in the embodiments of the present invention;

[0080] Figure 14 This is a schematic diagram illustrating the safety assessment under different factors provided in the embodiments of the present invention;

[0081] Figure 15 This is a structural diagram of the nuclear power plant gate O-ring safety assessment system under aging conditions provided in an embodiment of the present invention. Detailed Implementation

[0082] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0083] To address the problems existing in the prior art, this invention provides a method and system for safety assessment of O-rings on nuclear power plant gates under aging conditions. The invention will now be described in detail with reference to the accompanying drawings.

[0084] The following are two specific application examples and their implementation schemes of the safety assessment method for nuclear power plant gate O-rings under aging conditions provided by the present invention:

[0085] Example 1: Safety assessment of O-rings under conventional operating conditions of nuclear power plants

[0086] 1) Parameter measurement: Under the normal operating conditions of the nuclear power plant, the thermophysical parameters and stress relaxation parameters of the O-ring rubber material are measured, including the coefficient of thermal expansion, thermal conductivity, density, specific heat capacity, etc.

[0087] 2) Finite element simulation: Based on the measured parameters, the hyperelastic constitutive equation and viscoelastic model of the O-ring are established, and finite element analysis is performed to simulate the permanent deformation of the O-ring under the normal operating conditions of the nuclear power plant.

[0088] 3) Data analysis: The accuracy of the simulation model is verified by comparing the simulation results with the actual compression deformation test results.

[0089] 4) Safety Assessment: Based on the aging kinetic equation and the Arrhenius equation, assess the permanent compressibility of the O-ring at a given initial compressibility, aging temperature, and aging time. Then, calculate the leakage rate based on the obtained permanent compressibility and use this as a safety criterion to assess the safety of the O-ring.

[0090] Example 2: Safety assessment of O-rings under nuclear power plant accident conditions

[0091] 1) Parameter measurement: Under simulated nuclear power plant accident conditions (such as high temperature and high pressure), the relevant parameters of the O-ring rubber material are measured.

[0092] 2) Finite element simulation: The finite element analysis method is used to simulate the permanent deformation behavior of O-rings under accident conditions, including the effects of aging temperature and time on O-ring performance.

[0093] 3) Contact stress and width analysis: Calculate the initial contact stress and contact width of the O-ring under accident conditions, and fit their relationship with the initial compression ratio and aging temperature.

[0094] 4) Leakage rate assessment: Based on contact stress and width data under accident conditions, simulate leakage flow at the mesoscale and calculate the leakage rate.

[0095] 5) Safety assessment: Combining data on leakage rate and permanent compression rate, a comprehensive assessment of the safety of the gate under accident conditions is conducted.

[0096] These two examples cover the safety assessment of O-rings under both routine operation and accident conditions at nuclear power plants, providing a complete process from experimental measurements to data analysis and safety assessment, ensuring that the safety performance of O-rings under different operating conditions is effectively evaluated. Figure 1 This is a schematic diagram illustrating the steps of an embodiment of this application. The leakage rate calculation of this structure includes the following steps:

[0097] Step S1: Measure material parameters, establish a finite element analysis model and compare it with experimental results to verify the effectiveness of the model.

[0098] 1.1 Finite element model for calculating permanent compressibility.

[0099] The permanent deformation analysis consists of five steps: In the assembly step, the upper and lower rigid body surfaces are combined with the rubber model to establish the contact state; in the compression step, the upper flange is controlled to achieve a compression ratio of the set value C. i The model's temperature is raised to the target temperature T during the heating step by applying boundary conditions; during the relaxation step, C is maintained. i With T constant, relax the O-ring stress to the target aging time τ; finally, control the upper flange to return to its original position and remove the load. Figure 4 This is a schematic diagram illustrating the analysis steps for the permanent deformation characteristics in this embodiment.

[0100] 1.2 Verification of the Finite Element Method

[0101] Under the same initial compression ratio and temperature, the permanent compression ratio of the O-ring was obtained by experimental research method and finite element method, respectively. Figure 5 The scatter plots represent experimental results, while the curve is a fitted curve obtained from simulation calculations. Figure 5 As can be seen, the simulation results and experimental results are in excellent agreement, both in terms of numerical values ​​and trends. This demonstrates that the applied simulation method can accurately predict the permanent deformation characteristics of O-rings.

[0102] Step S2: Establish different initial compression ratios C i The functional relationship between the CS of the O-ring and the aging temperature T and aging time τ is: CS = f(T, τ).

[0103] 2.1 Calculation of Permanent Compression Ratio

[0104] This embodiment uses an initial compression ratio C. i Taking 25% as an example, based on the finite element analysis steps established in step S1, different temperatures T1, T2, T3, T4, and T5 are selected to obtain the CS results for aging times τ1, τ2, τ3, τ4, τ5, τ6, τ7, and τ8, respectively. Figure 6 The scatter plot is shown in the image.

[0105] 2.2 Laws governing the permanent deformation characteristics of O-rings

[0106] In this embodiment, the permanent deformation characteristics of the material can be selected by establishing a fitting function based on the aging kinetics equation and the Arrhenius equation. The Arrhenius equation is as follows:

[0107] (1)

[0108] Where T is temperature; A is a constant independent of both temperature and aging time; E and R are the activation energy and molar gas constant, respectively. k is the reaction rate constant.

[0109] The aging kinetic equation takes the following form:

[0110] (2)

[0111] In the above formula, f = 1-CS. B0 and α are constants independent of temperature, and τ is the aging time.

[0112] Combining the two equations above, we get the following equation:

[0113] (3)

[0114] In the formula, B1 =αln(A), B2 = -αE / R, B3 = α.

[0115] In summary, the coefficients B0, B1, B2, and B3 are all independent of the independent variables temperature T and aging time τ. The undetermined coefficients in the above formula were obtained by fitting the calculated data.

[0116] according to Figure 7 The scattered data in the equation are used to establish the relationship between CS and temperature T and aging time τ in the form of equation (3), and the regression coefficients B0, B1, B2, B3 are obtained. The expression is established as shown in equation (4), and the graph is plotted. Figure 6 The curve in the image.

[0117] (4)

[0118] In this embodiment, the fitting parameters for the permanent compression ratio CS are: B0 = 0.872674, B1 = 1.360025, B2 = -818.367155, B3 = 1.152684.

[0119] Step S3: Based on the permanent deformation analysis under the set working conditions in Step S2, before performing relaxation analysis on the material, directly output the mechanical properties of the gate O-ring and record the initial contact stress S. G0 .

[0120] Under nuclear power plant accident conditions, sealing materials are subjected to the combined effects of temperature, medium pressure, compressibility, and contact surfaces, leading to rubber aging and changes in mechanical properties. Therefore, the contact stress of the seal is an important indicator of changes in the performance of the sealing material.

[0121] 3.1 Initial contact stress S of the O-ring under specified operating conditions G0 With compression ratio C i The relationship with temperature T.

[0122] This embodiment considers the combined effects of temperature and stress. In this embodiment, the following parameters are considered: the O-ring wire diameter is d, the inner diameter is D, and the compression ratio is C. i .

[0123] Mechanical analysis involves only three steps, two fewer than permanent deformation analysis. The contact stress obtained at this point is denoted as the initial contact stress S. G0 Before performing relaxation analysis on the material, the initial contact stress S of the O-ring at different temperatures T was recorded. G0 A set of S was obtained. G0 The corresponding data for T; then change the initial compression ratio C. i Under subsequent permanent deformation analysis, S was recorded at different temperatures T. G0 To obtain different C i S below G0 Data corresponding to T. Results are as follows: Figure 7 As shown.

[0124] The final fit yields S G0 With C i The relationship with T is:

[0125] (5)

[0126] Where α0, β0, α r ,β r The parameters to be fitted are α1 = 0.92903, β1 = 0.00175, α2 = 0.30542, and β2 = 0.2064.

[0127] 3.2 Contact Width Calculation Data

[0128] While outputting the initial deformation characteristics in 3.1, it can also output the contact width B of the O-ring under different temperatures and compression rates.

[0129] Step S4: Based on the permanent deformation analysis under the set working conditions in step S2, before performing relaxation analysis on the material, directly output the contact stress of the gate O-ring and fit the relationship between the contact stress and temperature and aging time.

[0130] 4.1 Changes in contact stress over aging time.

[0131] The specific finite element model establishment method and load application process are consistent with step S2. The same temperatures T1, T2, T3, T4, and T5 as in step S2 are selected, and the contact stress S is recorded at the same times τ1, τ2, τ3, τ4, τ5, τ6, τ7, and τ8. G Data, such as Figure 8Shown as scattered points.

[0132] 4.2 Calculation of dimensionless contact stress

[0133] Based on the operating parameters in 4.1, record the initial contact stress S. G0 And based on S G0 S in 4.1 G Dimensionless data is obtained as S G / S G0 The result is as follows Figure 9 As shown in the scatter plot.

[0134] Similarly, S can be established. G / S G0 The relationship between temperature T and time τ yields regression coefficients B0, B1, B2, and B3, expressed as follows:

[0135] (6)

[0136] In this embodiment, the dimensionless contact stress S G / S G0 The fitting parameters are: B0 = 0.947350, B1 = -0.047785, B2 = -496.510752, B3 = 0.818283. The fitted curve is shown below. Figure 9 As shown by the curve.

[0137] Step S5: Based on the obtained data, fit the permanent compressibility CS with the dimensionless contact stress S. G / S G0 The relationship between them.

[0138] Change the parameters and select different initial compression ratios C. i At temperature T and aging time τ, simulated permanent compressibility CS and contact stress S G The value; and according to C i The initial contact stress S is obtained from T. G0 The contact stress S G Dimensionless conversion yields the permanent compressibility CS and the dimensionless contact stress S. G / S G0 The correspondence is as follows Figure 10 The scatter plots show a linear relationship between the two, which is consistent with C. i Since T and τ are independent, the transformation relationship between them can be fitted based on the data as follows:

[0139] (7)

[0140] In this embodiment, α0 and β0 are the fitting coefficients to be determined. In this embodiment, α0 = 101.1311 and β0 = 0.8568.

[0141] Step S6: Based on the interface leakage model, establish the relationship between the gate O-ring leakage rate Q and the sealing contact stress S under the specified operating conditions. G The relation is: Q = f(S) G ).

[0142] First, based on the microscopic morphology measurement or machining parameters of the sealing surface, parameters reflecting the surface condition, such as roughness σ and autocorrelation length A, must be obtained. T This allows for the establishment of a micro-contact analysis model for rough surfaces.

[0143] 6.1 Formula for calculating leakage rate of rough channel without applied sealing force.

[0144] Define roughness flow factor Φ σ This is used to characterize the influence of rough surface conditions on flow. Based on the leakage mechanism, numerical simulations are performed on interfacial leakage flow with height h0 formed by surfaces with different roughness characteristics. The simulation results show that Φ σ It is a dimensionless roughness σ * (σ) * = σ / A T A single-valued function of can have its functional relationship obtained through numerical calculation. In this embodiment, such as Figure 11 As shown, the fitting calculation results are as follows:

[0145] (8)

[0146] In this embodiment, A σ = 1.02876, B σ = -1.67792.

[0147] 6.2 Formula for calculating the leakage rate of rough channel after applying sealing force.

[0148] Define the height flow factor Φ h This study aims to characterize the effect of changes in gap height on flow in rough leakage channels. Based on the leakage mechanism, numerical simulations were performed on interfacial leakage flow with different separation heights h, formed by surfaces with the same roughness. The simulation results show that Φ... h It is the dimensionless height h * (h * A single-valued function (= h / h0) can have its functional relationship obtained through numerical calculation. In this embodiment, as... Figure 12 As shown, the fitting is based on the calculation results:

[0149] (9)

[0150] In this embodiment, A h = 0.03021, B h = 3.556.

[0151] 6.3 Formula for calculating leakage rate of smooth parallel channel.

[0152] Based on the established gap flow analysis model, the flow state of the leaking medium is simulated. In this implementation example, the contact area can be considered as a ring, the width of the leakage channel (average circumference of the O-ring) is L, and the length of the flow channel (contact width) is B, as follows... Figure 3 As shown.

[0153] When the internal and external pressures of the medium are p1 and p2 respectively, the viscosity coefficient of the medium is μ, and the initial channel height is h0, the expression for the leakage rate based on Poiseuille's cubic flow formula is as follows:

[0154] (10)

[0155] 6.4 Functional relationship between contact gap height and contact stress.

[0156] Hertz's elastic contact theory gives the relationship between h and contact stress S. G The functional form between them. Define the dimensionless gap height h. * =h / h0, and dimensionless stress S G * =S G / E. Based on the rough peak matrix microindentation test verification, h * and S G * The relationship between them is independent of the elastic modulus and the height of the roughness peaks, therefore h can be fitted. * and S G * The relationship is as follows:

[0157] (11)

[0158] The relationship between the calculated points and the fitted formula obtained for different roughnesses is as follows: Figure 13 As shown. In this embodiment, a h = 0.99229, b h = 1.25309, c h = 0.64259.

[0159] 6.5 Leakage rate Q and average sealing contact stress S G The relationship. Combining equations (8)-(11), we can obtain the result based on the average contact stress S. G Formula for calculating leakage rate Q:

[0160] (12)

[0161] 6.6 Further, by combining equations (7)-(12), the relationship between the permanent compressibility CS and the leakage rate Q can be obtained: CS = f(Q).

[0162] Step S7: Security Assessment

[0163] Combining steps S2 to S6, when the maximum allowable leakage rate Q lim Given the operating conditions of the O-ring, the maximum permissible permanent compression ratio CS can be calculated based on the above expression. lim In this embodiment, the leakage rate at different times is calculated as follows: Figure 14 As shown, CS lim The following sealing conditions are all acceptable, indicating that the safety of the sealing structure can be guaranteed.

[0164] Select different medium pressures P1, P2, P3, and P4, determine other parameters, and calculate the permanent compressibility and the maximum permissible permanent compressibility CS under different aging times. lim And then compare the two.

[0165] Select different temperatures T1, T2, T3, T4, and T5, and determine other parameters. Calculate the permanent compressibility and the maximum permissible permanent compressibility CS at different aging times. lim And then compare the two.

[0166] like Figure 1 As shown in the embodiment of the present invention, the method for safety assessment of nuclear power plant valve O-rings under aging conditions includes:

[0167] S1. Based on the experimental measurement of the thermophysical parameters and stress relaxation parameters of rubber materials, a hyperelastic constitutive equation describing the deformation characteristics of rubber under thermo-mechanical coupling conditions and a viscoelastic model reflecting the aging and creep characteristics of rubber are established. On this basis, the finite element analysis method is applied to carry out simulation experiments of permanent deformation of O-rings. The simulation experiments are compared with the actual compression deformation test results to verify the accuracy of the finite element analysis method.

[0168] S2, based on the finite element analysis process of S1, continuously changes the initial compression ratio C. i Aging temperature T and aging time τ are used to obtain sufficient permanent compressibility data; CS is set as the aging evaluation index, and different initial compressibility values ​​C are established according to the aging kinetic equation and Aronius formula. i Below, the functional relationship between the CS of the O-ring and the aging temperature T and aging time τ is: CS = f(T,τ);

[0169] S3, based on the finite element analysis process of S1, simultaneously outputs different initial compression ratios C. i The contact stress S at aging temperature T and aging time τ = 0 G0 And the contact width B, and fit their relationship: S G0 = f(C i , T) and B = f(C) i ,T);

[0170] S4, based on the finite element analysis process of S1, simultaneously outputs different initial compression ratios C. i The average contact stress S at the O-ring contact interface under different aging temperatures T G The variation law of aging time; with the initial contact stress S G0 Contact stress S G Dimensionless transformation, establishing dimensionless contact stress S G / S G0 With initial compression ratio C i The functional relationship between aging temperature T and aging time τ;

[0171] S5, organize the data obtained from S2-S4, and apply the initial compression ratio C. i The relationship between aging temperature T and aging time τ was established, and the relationship between permanent compressibility CS and dimensionless contact stress S was established. G / S G0 The correspondence between the two is fitted using the following transformation formula: CS = f(S) G / S G0 );

[0172] S6 simulates the flow in rough leakage channels with different roughnesses and heights at the mesoscale through interface leakage flow simulation. It fits the relationships between roughness flow factor and surface condition of the rough channel, and between height flow rate and leakage channel height. Then, based on the calculation formula for smooth leakage channels, it connects the flow factor at the mesoscale with the leakage rate at the macroscale. Simultaneously, based on microscopic contact analysis, it establishes the relationship between leakage channel height and contact stress. Finally, by combining the fitted equations, it establishes the relationship between the gate O-ring leakage rate Q and contact stress S under the specified operating conditions. G Relationship: Q = f(S) G );

[0173] S7, with average contact stress S G Using the intermediate variable, establish the relationship between the permanent compressibility CS and the leakage rate Q: CS = f(Q);

[0174] S8, Safety Assessment: Given operating conditions (initial compression rate C) iThe permanent compressibility of the gate is calculated using S1-S6 (pressure P, temperature T, and aging time τ) or by directly measuring the permanent compressibility of the O-ring after use. The maximum permissible permanent compressibility is calculated based on the allowable leakage rate of the containment gate, and this is used as a safety criterion to assess the safety of the gate under accident conditions.

[0175] like Figure 15 As shown in the embodiment of the present invention, the safety assessment system for nuclear power plant gate O-rings under aging conditions includes:

[0176] The finite element analysis module is used to establish a hyperelastic constitutive equation describing the deformation characteristics of rubber under thermo-mechanical coupling conditions and a viscoelastic model reflecting the aging and creep characteristics of rubber based on experimental measurements of the thermophysical properties and stress relaxation parameters of rubber materials. On this basis, the finite element analysis method is applied to carry out simulation experiments of permanent deformation of O-rings. The simulation experiments are compared with the actual compression deformation test results to verify the accuracy of the finite element analysis method.

[0177] The permanent compressibility data acquisition module is used to continuously change the initial compressibility C based on the finite element analysis process. i Aging temperature T and aging time τ are used to obtain sufficient permanent compressibility data; CS is set as the aging evaluation index, and different initial compressibility values ​​C are established according to the aging kinetic equation and Aronius formula. i Below, the functional relationship between the CS of the O-ring and the aging temperature T and aging time τ is: CS = f(T, τ);

[0178] The relational fitting module is used to simultaneously output different initial compression ratios C based on the finite element analysis process. i The contact stress S at aging temperature T and aging time τ = 0 G0 And the contact width B, and fit their relationship: S G0 = f(C i , T) and B = f(C) i , T);

[0179] The relation establishment module is used to simultaneously output different initial compression ratios C based on the finite element analysis process. i The average contact stress S at the O-ring contact interface under different aging temperatures T G The variation law of aging time; with the initial contact stress S G0 Contact stress S G Dimensionless transformation, establishing dimensionless contact stress S G / S G0 With initial compression ratio C i The functional relationship between aging temperature T and aging time τ;

[0180] The conversion formula fitting module is used to process the obtained data and apply it to the initial compression ratio C. i The relationship between aging temperature T and aging time τ was established, and the relationship between permanent compressibility CS and dimensionless contact stress S was established. G / S G0 The correspondence between the two is fitted using the following transformation formula: CS = f(S G / S G0 );

[0181] The relational equation module is used to simulate the flow in rough leakage channels with different roughnesses and heights at the mesoscale through interface leakage flow simulation. It fits the relationships between roughness flow factor and surface condition of rough channels, and between height flow rate and leakage channel height. Then, based on the calculation formula for smooth leakage channels, it links the mesoscale flow factor with the macroscale leakage rate. Simultaneously, based on microscopic contact analysis, it establishes the relationship between leakage channel height and contact stress. Finally, by combining the fitted equations, it establishes the relationship between the gate O-ring leakage rate Q and contact stress S under specified operating conditions. G Relationship: Q = f(S) G );

[0182] The safety assessment module is used for a given operating condition (initial compression rate C). i The permanent compressibility of the gate is calculated using S1-S6 (pressure P, temperature T, and aging time τ) or by directly measuring the permanent compressibility of the O-ring after use. The maximum permissible permanent compressibility is calculated based on the allowable leakage rate of the containment gate, and this is used as a safety criterion to assess the safety of the gate under accident conditions.

[0183] An application embodiment of the present invention provides a computer device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor performs the steps of a method for safety assessment of nuclear power plant gate O-rings under aging conditions.

[0184] An application embodiment of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of a method for safety assessment of nuclear power plant gate O-rings under aging conditions.

[0185] An application embodiment of the present invention provides an information data processing terminal, which is used to implement a safety assessment system for O-rings of nuclear power plant gates under aging conditions.

[0186] At the initial compression ratio C i = 25%, and at a temperature T = 120 ℃, calculate the safe state of the O-ring under a certain medium pressure P.

[0187] When the aging time τ = 1 day, according to equation (4), the permanent compression ratio CS can be obtained to indicate the safe state of the O-ring at this time:

[0188]

[0189] According to nuclear power safety standards, the maximum permissible leakage rate Q is... lim = 4.1229×10 -8 kg / s.

[0190] The characteristic parameters of a rough surface include σ = 1 μm and A. T = 0.07 μm, which yields the dimensionless roughness σ * = σ / A T =1 / 0.07 = 14.2857. According to equation (8), we get:

[0191]

[0192] Choose P = 0.7 MPa, atmospheric pressure is P b Taking 0.1 MPa as an example, the finite element analysis results show that the current flow channel length (contact width) B = 0.004341 m, the leakage channel width (average circumference of the O-ring) L = 0.6283 m, and the initial height of the leakage channel h0 = 3σ. The calculated dynamic viscosity of the medium μ = 2.19787 × 10⁻⁶. -5 Pa·s, density ρ = 6.67554 kg / m³ 3 At this time, we get

[0193]

[0194] By combining equations (8), (9), and (10), the maximum allowable leakage rate Q can be calculated. lim The corresponding dimensionless height h * lim (h * =h / h0):

[0195]

[0196] The elastic modulus of the material used was measured to be E = 10.05782 MPa. According to equation (11), the maximum allowable leakage rate Q at this moment can be obtained. lim Corresponding contact stress S Glim for:

[0197]

[0198] The initial contact stress is obtained according to equation (5):

[0199]

[0200] Therefore, the maximum allowable leakage rate Q can be obtained according to equation (7). lim The corresponding maximum allowable permanent compression ratio:

[0201]

[0202] Based on security guidelines The service status of the O-ring at this time is judged to be safe.

[0203] To verify the effectiveness of the finite element analysis method for the long-term behavior of O-rings under thermo-coupling conditions, a simulation experiment was conducted to determine the permanent compressibility of the O-rings. The displacement and temperature loading processes in the simulation experiment were exactly the same as those in the literature for permanent compressibility testing.

[0204] Experimental tests show that the simulation results of this invention are in good agreement with the actual test results, both in terms of numerical values ​​and trends. The simulation method used can accurately predict the long-term mechanical behavior of O-rings under thermo-mechanical coupling.

[0205] However, experimental testing, compared to the finite element analysis method proposed in this paper, requires a significant amount of time and expense, and necessitates multiple repetitions. Even then, it cannot directly determine the sealing state of the O-ring. In contrast, data obtained through finite element analysis, after establishing a complete set of calculation formulas, can be directly used for leakage rate assessment, demonstrating the advantages of the method proposed in this paper.

[0206] It should be noted that embodiments of the present invention can be implemented in hardware, software, or a combination of both. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated-design hardware. Those skilled in the art will understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuitry such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field-programmable gate arrays, programmable logic devices, etc., or by software executed by various types of processors, or by a combination of the above-described hardware circuitry and software, such as firmware.

[0207] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for safety assessment of O-rings on nuclear power plant valves under aging conditions, characterized in that, First, the thermophysical parameters and stress relaxation parameters of the O-ring rubber material were obtained through experimental measurement. Then, a hyperelastic constitutive equation and a viscoelastic model were established to describe the deformation and aging creep characteristics of the rubber. A permanent deformation simulation experiment was conducted using the finite element analysis method, and the accuracy of the simulation model was verified by the results of actual compression deformation tests. This method also utilizes numerical simulation of permanent compression deformation and a permanent compression ratio function based on the initial compression ratio, aging temperature, and aging time. Through comprehensive analysis and data fitting, the relationship between permanent compression ratio and leakage rate was established. The method for safety assessment of nuclear power plant valve O-rings under aging conditions includes: S1. Based on the experimental measurement of the thermophysical parameters and stress relaxation parameters of rubber materials, a hyperelastic constitutive equation describing the deformation characteristics of rubber under thermo-mechanical coupling conditions and a viscoelastic model reflecting the aging and creep characteristics of rubber are established. On this basis, the finite element analysis method is applied to carry out simulation experiments of permanent deformation of O-rings. The simulation experiments are compared with the actual compression deformation test results to verify the accuracy of the finite element analysis method. S2, based on the finite element analysis process of S1, continuously changes the initial compression ratio C. i Aging temperature T and aging time τ are used to obtain sufficient permanent compressibility data; CS is set as the aging evaluation index, and different initial compressibility values ​​C are established according to the aging kinetic equation and Aronius formula. i Below, the functional relationship between the CS of the O-ring and the aging temperature T and aging time τ is: CS = f(T, τ); S3, based on the finite element analysis process of S1, simultaneously outputs different initial compression ratios C. i Contact stress S at aging temperature T and aging time τ = 0 G0 And the contact width B, and fit their relationship: S G0 = f(C i , T) and B = f(C) i , T); S4, based on the finite element analysis process of S1, simultaneously outputs different initial compression ratios C. i The average contact stress S at the O-ring contact interface under different aging temperatures T G The variation law of aging time; with the initial contact stress S G0 Contact stress S G Dimensionless transformation, establishing dimensionless contact stress S G / S G0 With initial compression ratio C i The functional relationship between aging temperature T and aging time τ; S5, organize the data obtained from S2-S4, and apply the initial compression ratio C. i The relationship between aging temperature T and aging time τ was established, and the relationship between permanent compressibility CS and dimensionless contact stress S was established. G / S G0 The correspondence between the two is fitted using the following transformation formula: CS = f(S G / S G0 ); S6 simulates the flow in rough leakage channels with different roughnesses and heights at the mesoscale through interface leakage flow simulation. It fits the relationships between roughness flow factor and surface condition of the rough channel, and between height flow rate and leakage channel height. Then, based on the calculation formula for smooth leakage channels, it connects the flow factor at the mesoscale with the leakage rate at the macroscale. Simultaneously, based on microscopic contact analysis, it establishes the relationship between leakage channel height and contact stress. Finally, by combining the fitted equations, it establishes the relationship between the gate O-ring leakage rate Q and contact stress S under the specified operating conditions. G Relationship: Q = f(S) G ); S7, with average contact stress S G Using the permanent compressibility CS as an intermediate variable, establish the relationship between the leakage rate Q: CS = f(Q); S8, Safety Assessment: Given operating conditions, including initial compression ratio C i Pressure P, temperature T, and aging time τ are used to calculate the permanent compressibility of the gate through S1-S6 or to directly measure the permanent compressibility of the O-ring after use. The maximum permissible permanent compressibility is calculated based on the allowable leakage rate of the containment gate, and this is used as a safety criterion to assess the safety of the gate under accident conditions.

2. The method for safety assessment of nuclear power plant valve O-rings under aging conditions as described in claim 1, characterized in that, S1 represents the measured material parameters. A finite element analysis model is established and compared with experimental results to verify the model's effectiveness. This process includes the following steps: S101. The material parameters of the rubber O-ring are obtained through experimental measurement. The specific methods are as follows: (1) The physical property parameters of the coefficient of thermal expansion, thermal conductivity, density and specific heat capacity as a function of time are obtained by experiment; (2) Uniaxial tensile test is carried out to monitor the hyperelasticity of the material, and the experimental data are fitted with a suitable constitutive equation to obtain the hyperelastic parameters; (3) Viscoelastic data of the material are obtained by using the DMA method, and the experimental data are fitted with the Prony series to obtain the viscoelastic parameters. S102. Establish a finite element model and obtain the permanent compressibility CS data of the O-ring through both finite element method and experimental method. Verify the effectiveness of the model by comparing the two. The specific methods are as follows: (1) Establish a finite element analysis model of the sealing structure; (2) Input the material parameters of the O-ring, including physical property parameters and hyperelastic and viscoelastic parameters; (3) Achieve the initial compressibility C of the finite element analysis by applying displacement. i (3) Set the ambient temperature T to simulate the working temperature of the O-ring, and set the aging time τ of multiple O-rings; (4) According to the set working conditions, perform stress relaxation finite element analysis on the O-ring to obtain the permanent compression ratio CS of the O-ring; (5) Change the temperature T and repeat the above steps to obtain multiple sets of corresponding values ​​of CS and aging time τ; (6) Under the set working conditions of the finite element analysis, conduct actual compression permanent deformation experiments to obtain real permanent compression ratio data, and compare it with the finite element analysis data to verify the accuracy of the finite element method; (7) When the data has a large deviation, adjust the model settings and boundary conditions of the finite element analysis, repeat (1)-(6), and correct the finite element method.

3. The method for safety assessment of nuclear power plant valve O-rings under aging conditions as described in claim 1, characterized in that, S2 establishes a functional relationship between the permanent compression ratio CS of the O-ring and aging temperature and aging time, based on a large amount of numerical simulation data on permanent compression deformation, under a given initial compression ratio. Specifically, it includes the following steps: S201. Based on the finite element analysis process of S1, the initial compression ratio C is set. i The permanent compressibility CS data is obtained based on finite element analysis. The specific method is as follows: (1) Select multiple working conditions according to actual needs and set different initial compressibility CS. i (1) Aging temperature T and aging time τ; (2) According to the set working conditions, perform stress relaxation finite element analysis on the O-ring to obtain the permanent compression ratio CS of the O-ring; S202. Based on the aging kinetic equation and Arrhenius formula, fitting different initial compression ratios C. i The relationship between the permanent compressibility CS of the O-ring and temperature T and aging time τ is: CS = f(T, τ).

4. The method for safety assessment of nuclear power plant valve O-rings under aging conditions as described in claim 1, characterized in that, S3 represents the initial contact stress S of the O-ring at the initial moment, obtained from a simulation experiment of permanent compression deformation. G0 And the contact width B, and establish the relationship between the two with respect to the initial compression ratio C. i The functional relationship between the aging temperature T and the aging temperature includes the following steps: (1) Select multiple working conditions according to actual needs and set different initial compression ratios C. i Aging temperature T; (2) Based on the set working conditions, perform finite element analysis of S1 for the O-ring; (3) Before performing relaxation analysis on the material, i.e. when the aging time τ = 0, record the initial contact stress S at different temperatures. G0 and contact width B; (4) Select appropriate function forms and fit S respectively. G0 and B and C i Relationship with T: S G0 = f(C i , T) and B = f(C) i ,T).

5. The method for safety assessment of nuclear power plant valve O-rings under aging conditions as described in claim 1, characterized in that, S4 is the dimensionless contact stress S during the permanent deformation process of the O-ring, established using the finite element analysis method in S1. G / S G0 The functional relationship is expressed by the following steps: (1) Select multiple working conditions according to actual needs and set different initial compression ratios C. i Aging temperature T; (2) Based on the set working conditions, perform finite element analysis of S1 for the O-ring; (3) Output different initial compression ratios C i S under different aging temperatures T and different aging times τ G ; (4) Initial contact stress S corresponding to the same compression ratio and the same aging temperature G0 Let the dimensionless contact stress S be defined as a characteristic quantity. G / S G0 ; (5) S G / S G0 As an indicator of aging performance, S is established using the aging kinetic equation and the Aronius formula. G / S G0 The function of aging temperature T and aging time τ; (6) The S obtained from S3 G0 = f(C i , T) and S G / S G0 By combining f(T, τ) with the thermo-mechanical coupling, S can be obtained. G Calculation formula: .

6. The method for safety assessment of nuclear power plant valve O-rings under aging conditions as described in claim 1, characterized in that, S5 represents the fitting relationship between the permanent compressibility CS and the dimensionless contact stress S. G / S G0 The relationship between them includes the following steps: (1) Given an initial compression ratio C i The permanent compressibility CS and dimensionless contact stress S obtained from S1 and S4 G / S G0 Relationship between CS and S G / S G0 The correspondence; (2) Change the initial compression ratio C i Multiple sets of different C were obtained. i CS and S G / S G0 The corresponding data; (3) Based on the numerical results, fit CS and S G / S G0 The relation is: CS = f(S) G / S G0 ).

7. The method for safety assessment of nuclear power plant valve O-rings under aging conditions as described in claim 1, characterized in that, S6 establishes the relationship between the gate O-ring leakage rate Q and contact stress S based on the interface leakage mechanism. G The relationship specifically includes the following steps: S601. Based on interface leakage flow simulation, establish the relationship between leakage rate Q and geometric parameters, operating parameters, surface roughness, and actual height of the leakage channel: The specific method is as follows: (1) Obtain rough surface characteristic parameters, such as roughness σ and autocorrelation length A, by performing microscopic morphology analysis on the machined surface. T (2) Establish a rough leakage channel with a height of h0 composed of multiple surfaces with different roughness characteristics, and perform numerical simulation of interface leakage flow; (3) Simulate the flow conditions of the leakage channel and fit the roughness flow factor Φ. σ With σ and A T (3) Obtain the relationship between surface roughness and flow characteristics of sealing interface; (4) Establish rough leakage channels with different separation heights h composed of multiple surfaces with the same roughness characteristics; (5) Simulate the flow conditions of leakage channels and fit the height flow factor Φ. h (6) Establish the formula for calculating the leakage rate of the sealing interface: Q=Φ σ ×Φ h ×Q p Q p Let Q be the leakage rate of a leakage channel of height h0 formed by a smooth surface, where h0 is the channel height corresponding to zero contact stress. This formula can be extended from the mesoscopic to the macroscopic level. For O-rings, Q p Poiseuille's law, which describes the flow between parallel plates, can be used for calculation. In this case, the geometry of the leakage channel is the O-ring contact width B and average circumference L, and the pressure difference is the pressure difference P between the inside and outside of the O-ring. Finally, we can obtain: Q = f(B, P, σ, A) T , h); S602. Based on the microscopic characteristics of the rough surface, establish an n×n rough peak model, with a rough peak radius of σ and a rough peak spacing of A. T Based on the microscopic contact mechanics method, the microscopic contact of a rough surface is simulated, and the relationship between the actual height h of the leakage channel and the contact stress S is established. G Relationship: h = f(S) G ); S603. By combining the formulas obtained from steps S601-S602, establish the relationship between the gate O-ring leakage rate Q and the contact stress S under the specified operating conditions. G Relationship: Q = f(S) G ).

8. The method for safety assessment of nuclear power plant valve O-rings under aging conditions as described in claim 1, characterized in that, S7 is to combine the formulas of S1-S5 to establish the relationship between the permanent compressibility CS and the leakage rate Q: CS = f(Q); S8 assesses the safety performance of a containment gate under accident conditions based on the allowable leakage rate of the gate as a safety criterion; specifically, it includes the following steps: S801, Set the leakage rate limit Q of the gate O-ring. lim Based on the relationship between leakage rate Q and permanent compression ratio CS in S6, a long-term sealing performance evaluation criterion is proposed: CS ≤ CS lim ; S802. Based on the measured permanent compression ratio CS, the safety performance of the O-ring is judged according to the evaluation criteria. The specific method is as follows: (1) Given the initial compression ratio C of the gate O-ring i (2) Using the obtained relationship, establish the relationship between the permanent compressibility CS and the leakage rate Q of the gate O-ring; lim Convert to permanent compression ratio limit CS lim ; ( 3) Calculate its permanent compressibility CS by actual measurement or based on operating conditions; (4) According to the evaluation criterion CS ≤ CS lim Determine the safety status of the O-ring.

9. A safety assessment system for O-rings of nuclear power plant valves under aging conditions, applying the safety assessment method for O-rings of nuclear power plant valves under aging conditions as described in any one of claims 1 to 8, characterized in that, include: The finite element analysis module is used to establish a hyperelastic constitutive equation describing the deformation characteristics of rubber under thermo-mechanical coupling conditions and a viscoelastic model reflecting the aging and creep characteristics of rubber based on experimental measurements of the thermophysical properties and stress relaxation parameters of rubber materials. On this basis, the finite element analysis method is applied to carry out simulation experiments of permanent deformation of O-rings. The simulation experiments are compared with the actual compression deformation test results to verify the accuracy of the finite element analysis method. The permanent compressibility data acquisition module is used to continuously change the initial compressibility C based on the finite element analysis process. i Aging temperature T and aging time τ are used to obtain sufficient permanent compressibility data; CS is set as the aging evaluation index, and different initial compressibility values ​​C are established according to the aging kinetic equation and Aronius formula. i Below, the functional relationship between the CS of the O-ring and the aging temperature T and aging time τ is: CS = f(T, τ); The relational fitting module is used to simultaneously output different initial compression ratios C based on the finite element analysis process. i The contact stress S at aging temperature T and aging time τ = 0 G0 And the contact width B, and fit their relationship: S G0 = f(C i , T) and B =f(C i , T); The relation establishment module is used to simultaneously output different initial compression ratios C based on the finite element analysis process. i The average contact stress S at the O-ring contact interface under different aging temperatures T G The variation law of aging time; with the initial contact stress S G0 Contact stress S G Dimensionless transformation, establishing dimensionless contact stress S G / S G0 With initial compression ratio C i The functional relationship between aging temperature T and aging time τ; The conversion formula fitting module is used to process the obtained data and apply it to the initial compression ratio C. i The relationship between aging temperature T and aging time τ was established, and the relationship between permanent compressibility CS and dimensionless contact stress S was established. G / S G0 The correspondence between the two is fitted using the following transformation formula: CS = f(S G / S G0 ); The relational equation module is used to simulate the flow in rough leakage channels with different roughnesses and heights at the mesoscale through interface leakage flow simulation. It fits the relationships between roughness flow factor and surface condition of rough channels, and between height flow rate and leakage channel height. Then, based on the calculation formula for smooth leakage channels, it links the mesoscale flow factor with the macroscale leakage rate. Simultaneously, based on microscopic contact analysis, it establishes the relationship between leakage channel height and contact stress. Finally, by combining the fitted equations, it establishes the relationship between the gate O-ring leakage rate Q and contact stress S under specified operating conditions. G Relationship: Q = f(S) G ); The safety assessment module is used to calculate the permanent compressibility of the gate through S1-S6 or directly measure the permanent compressibility of the O-ring after use under given operating conditions. The maximum permissible permanent compressibility is calculated based on the allowable leakage rate of the containment gate, and this is used as a safety criterion to assess the safety of the gate under accident conditions.

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