Evaluation Method for Concrete Structure Performance of Existing Nuclear Safety-related Buildings

Abstract

The present invention discloses a method for evaluating the concrete structure performance of existing nuclear safety-related plants, which includes the following steps: (1) Divide the existing nuclear safety-related plants into structural areas with different seismic requirements based on the failure safety risk of the plants, and formulate different structural review standard requirements; (2) Conduct durability evaluation and strength analysis on the plants to determine the current mechanical properties and load-bearing capacity of the structural components of the existing plants; (3) Determine the numerical calculation model of the existing nuclear safety-related plants, apply load effects to the model, and then conduct performance simulation calculations; (4) Macroscopically evaluate the overall seismic performance of the existing nuclear safety-related plants according to the results of the performance simulation calculations. The method in the present invention maximally applies the concept of structural performance design, enabling the existing plants to continue to be put into use as much as possible, and playing a promoting role in improving the structural design technology of nuclear safety-related plants. This method is technologically advanced, safe and reliable, and simple to implement.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear safety, and particularly relates to a method for evaluating the concrete structure performance of existing nuclear safety-related plants. Background Art

[0002] Once a plant related to safety in nuclear engineering is damaged, it may cause the nuclear material it contains to reach criticality or leak. These radioactive substances will cause serious environmental pollution and harm to the human body, and the impact is huge. After the Fukushima nuclear accident in Japan, China has carried out a major safety inspection of existing nuclear facilities, and the seismic ground motion levels in some areas where nuclear facilities are located have changed; with the understanding of nuclear facility design in China, the code standards for structural design have changed, and the safety has been gradually improved; China's understanding level of earthquakes is also constantly improving, and the national seismic zoning map has been updated; there are currently a large number of nuclear projects in China. As time goes by, these projects will encounter problems such as critical service life or full service life in the future, and need to be rechecked for life extension. All these factors make our country encounter more and more nuclear engineering safety-related plants that need to be evaluated for structural performance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for evaluating the concrete structure performance of existing nuclear safety-related plants, which has appropriate theoretical support and enables the plant evaluation to be safe and reasonable, aiming at the above deficiencies in the prior art.

[0004] The technical solution adopted to solve the technical problem of the present invention is to provide a method for evaluating the concrete structure performance of existing nuclear safety-related plants, including the following steps:

[0005] (1) Divide the existing nuclear safety-related plant into structural areas with different seismic requirements based on the plant failure safety risk as the judgment point, and formulate different structural recheck standard requirements;

[0006] (2) Conduct durability evaluation and strength analysis on the plant to determine the current mechanical properties and bearing capacity of the existing plant structural members;

[0007] (3) Determine the numerical calculation model of the existing nuclear safety-related plant, apply load effects on the model, and then conduct performance simulation calculation;

[0008] (4) Macroscopically evaluate the overall seismic performance of the existing nuclear safety-related plant according to the results of the performance simulation calculation.

[0009] Preferably, the plant failure safety risks in step (1) include: nuclear critical safety risk, nuclear leakage risk.

[0010] Preferably, step (1) specifically includes:

[0011] Starting from the usage functions of existing nuclear safety-related buildings, the concrete structures of nuclear safety-related buildings are divided into different structural areas;

[0012] Taking the failure safety risk of the building as the evaluation point, the structural areas with different usage functions are divided into structural areas with different seismic requirements;

[0013] For structural areas with different seismic requirements, different structural review standard requirements are formulated.

[0014] Preferably, the step (2) specifically includes:

[0015] Conduct an analysis of the failure mechanism of the concrete structure of the existing nuclear safety-related building;

[0016] Through theoretical model derivation and evaluation, conduct durability evaluation and strength analysis of the building;

[0017] Analyze the raw materials, construction techniques, and construction records of the existing nuclear safety-related building;

[0018] Conduct on-site inspections of the existing facilities in the existing nuclear safety-related building;

[0019] Determine the current mechanical properties and load-bearing capacity of the existing structural components in the existing nuclear safety-related building.

[0020] Preferably, the step (3) specifically includes:

[0021] Establish a three-dimensional finite element numerical calculation model of the existing nuclear safety-related building;

[0022] Apply real loads to the model according to the actual situation, and remove the structural conservatism brought by uncertainties in the design stage;

[0023] Conduct numerical calculations of load combination and performance simulation.

[0024] Preferably, the real loads include any one or several of self-weight, temperature, earthquake, hydrostatic pressure, earth pressure, and fixed equipment load.

[0025] Preferably, after the step (4), it further includes:

[0026] In step (5), propose reinforcement and renovation measures for the components of the existing nuclear safety-related building that do not meet the stress requirements.

[0027] Preferably, the step (5) further includes: evaluating the reinforcement and renovation measures from multiple dimensions of reinforcement scope, engineering quantity, implementation difficulty, construction period, and cost.

[0028] Preferably, after the step (5), it further includes:

[0029] Step (6) avoids the possible risks in the existing nuclear safety-related plant from the perspective of management and operation.

[0030] Preferably, the perspective of management and operation in step (6) includes any one or more of cost, personnel management, and on-site feasibility.

[0031] A method for evaluating the concrete structure performance of an existing nuclear safety-related plant provided by the present invention maximally applies the concept of structural performance design, enables the existing plant to continue to be put into use as much as possible, and promotes the development and improvement of the structural design technology of nuclear safety-related plants. This method is technologically advanced, safe and reliable, simple to implement, and highly feasible. This invention can also be used for the evaluation of the performance of other existing structures with special requirements in nuclear engineering. Brief Description of the Drawings

[0032] Figure 1 It is a schematic plan view of the plant structure in Embodiments 2 and 3 of the present invention;

[0033] Figure 2 It is a schematic sectional view of the plant structure in Embodiments 2 and 3 of the present invention;

[0034] Figure 3 It is a comparison chart of the rare earthquake acceleration response spectrum in the 9-degree area and the earthquake acceleration response spectrum under the ultimate safety earthquake motion level after earthquake review.

[0035] In the figure: 1 - important area related to safety, 2 - first other area, 3 - second other area, 4 - single-slope steel roof truss. Detailed Embodiments

[0036] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0037] The embodiments of the present patent are described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present patent and should not be construed as a limitation to the present patent.

[0038] Embodiment 1

[0039] This embodiment provides a method for evaluating the concrete structure performance of an existing nuclear safety-related plant, including the following steps:

[0040] (1) Taking the failure safety risk of the existing nuclear safety-related plant as the judgment point, dividing it into structural areas with different seismic requirements, and formulating different structural review standard requirements;

[0041] (2) Conduct durability evaluation and strength analysis on the plant building to determine the current mechanical properties and load-bearing capacity of the existing plant building structural components;

[0042] (3) Determine the numerical calculation model of the existing nuclear safety-related plant building, apply load effects to the model, and then conduct performance simulation calculations;

[0043] (4) For the results of the performance simulation calculations, macroscopically evaluate the overall seismic performance of the existing nuclear safety-related plant building structure.

[0044] A method for evaluating the performance of the concrete structure of an existing nuclear safety-related plant building provided in this embodiment maximally applies the concept of structural performance design, enabling the existing plant building to continue to be put into use as much as possible, and playing a promoting role in the development and improvement of the structural design technology of nuclear safety-related plant buildings. This method is technologically advanced, safe and reliable, simple to implement, and highly feasible. This embodiment can also be used in the performance evaluation of other existing structures with special requirements in nuclear engineering.

[0045] Embodiment 2

[0046] As Figure 1 、 2 shown, a method for evaluating the performance of the concrete structure of an existing nuclear safety-related plant building provided in this embodiment includes the following steps:

[0047] (1) Taking the failure safety risk of the existing nuclear safety-related plant building as the judgment point, divide it into structural areas with different seismic requirements, and formulate different structural review standard requirements; among them, the plant building failure safety risks include: nuclear critical safety risk, nuclear leakage risk.

[0048] The specific steps of step (1) include:

[0049] (11) Starting from the use function of the existing nuclear safety-related plant building, divide the concrete structure of the nuclear safety-related plant building into different structural areas: safety-related important area 1, first other area 2, second other area 3, single-slope steel roof truss 4;

[0050] (12) Taking the failure safety risk of the plant building as the judgment point, divide the structural areas with different use functions into structural areas with different seismic requirements; there are risks of leakage and criticality in the safety-related important area 1, and it must meet the requirements of the safety-related plant building, and the structure remains elastic or inclusive. There are no direct safety hazards in the first other area 2, the second other area 3, and the single-slope steel roof truss 4, ensuring that this structure will not collapse under earthquake action and affect the safety-related important area 1.

[0051] (13) For the structural areas with different seismic requirements, formulate different structural review standard requirements.

[0052] (2) Conduct durability evaluation and strength analysis on the plant building to determine the current mechanical properties and bearing capacity of the existing structural components of the plant building.

[0053] The specific steps of step (2) include:

[0054] (21) Conduct analysis on the failure mechanism of the concrete structure of the existing nuclear safety-related plant building; specifically, in this embodiment, analyze the environmental effects on the existing building and the corrosion mechanism of the concrete structure.

[0055] (22) Through theoretical model derivation and evaluation, conduct durability evaluation and strength analysis on the plant building; specifically, in this embodiment, establish a durability theoretical model and derive the carbonation depth, chloride ion and sulfate erosion degree.

[0056] (23) Analyze the raw material properties, construction technology and construction records of the existing nuclear safety-related plant building;

[0057] (24) Conduct on-site inspection on the existing facilities of the existing nuclear safety-related plant building;

[0058] (25) Determine the current mechanical properties and bearing capacity of the existing structural components of the existing nuclear safety-related plant building. Specifically, in this embodiment, conduct analysis on the existing bearing capacity of the plant building structural components to determine the selection of the design value for the seismic review work.

[0059] (3) Determine the numerical calculation model of the existing nuclear safety-related plant building, apply load effects on the model, and then conduct performance simulation calculation.

[0060] The specific steps of step (3) include:

[0061] (31) Establish a three-dimensional finite element numerical calculation model of the existing nuclear safety-related plant building;

[0062] (32) Apply real loads to the model according to the actual situation to remove the structural conservatism brought by uncertainties in the design stage; among them, real loads include: any one or several of self-weight, temperature, earthquake, hydrostatic pressure, earth pressure, fixed equipment load. The seismic action adopts the method of seismic margin assessment, fully considering various uncertainties, the median value and plasticity of materials.

[0063] (33) Conduct load combination and performance simulation numerical calculation.

[0064] (4) For the results of performance simulation calculations, macroscopically evaluate the overall seismic performance of the existing nuclear safety-related plant structures. Specifically, in this embodiment, bearing capacity calculations are performed to obtain the reinforcement calculation results of different parts of the plant under the new seismic level, and compare them with the original structure reinforcement to determine whether the actual reinforcement of the structure meets the requirements of the new seismic level. Different evaluation criteria are adopted for different functional areas to evaluate the overall seismic performance of the structure.

[0065] (5) Propose reinforcement and renovation measures for the components of the existing nuclear safety-related plants that do not meet the stress requirements. Evaluate the reinforcement and renovation measures from multiple dimensions including the reinforcement scope, engineering quantity, implementation difficulty, construction period, and cost.

[0066] (6) Avoid the possible risks of the existing nuclear safety-related plants from the perspective of management and operation. Among them, the perspective of management and operation includes any one or several of cost, personnel management, and on-site feasibility.

[0067] The method for evaluating the concrete structure performance of the existing nuclear safety-related plants in this embodiment can truly and reliably evaluate the performance of the existing nuclear safety-related plants through functional area division, load actions such as seismic input, durability and strength evaluation, and establishing a finite element model for numerical analysis.

[0068] The method for evaluating the concrete structure performance of the existing nuclear safety-related plants in this embodiment starts from the use function of the plant, takes the failure safety risk of the plant as the judgment point, and demonstrates reasonable load input and review methods: conduct structural calculations on the parts of the plant directly related to nuclear safety with the requirements of maintaining elasticity or inclusiveness; adopt the concept of construction measures and ductility design for the structural areas that will not directly cause safety accidents to evaluate the structural performance.

[0069] The method for evaluating the concrete structure performance of the existing nuclear safety-related plants in this embodiment can accurately determine the solution according to the required structural review target.

[0070] A method for evaluating the concrete structure performance of the existing nuclear safety-related plants provided in this embodiment maximally applies the concept of structural performance design, enables the existing plants to continue to be put into use as much as possible, and plays a role in promoting the development and improvement of the structural design technology of nuclear safety-related plants. This method is technologically advanced, safe and reliable, simple to implement, and highly feasible. This embodiment can also be used for the performance evaluation of other existing structures with special requirements in nuclear engineering.

[0071] Embodiment 3

[0072] This embodiment provides a method for evaluating the concrete structure performance of the existing nuclear safety-related plants, including the following steps:

[0073] 1. Analyze the building according to the structural layout and functional characteristics of the existing nuclear safety-related project plant, determine the functional area division, and formulate different seismic analysis schemes according to the usage requirements of different functional areas. The plant layout forms are as Figure 1 , 2 shown. The plant is divided into the important safety-related area 1, the first other area 2, the second other area 3, and the single-slope steel roof truss 4.

[0074] From the perspective of building function division, the important safety-related area 1 is the storage pool area. The important safety-related area 1 is the key area and should meet the relevant design concepts of nuclear power plants. Under the conditions of the ultimate safety seismic ground motion, the structural components should remain elastic or have inclusiveness without damage. The first other area 2 is the emergency pool area, the second other area 3 is the auxiliary supporting room, and the first other area 2, the second other area 3, and the single-slope steel roof truss 4 are general areas. The seismic requirements of civil buildings can be referred to, and the concept design is that the structure will not collapse or cause serious damage endangering life under rare earthquakes.

[0075] 2. Determine the current mechanical properties and bearing capacities of the structural components of the existing plant.

[0076] 1. Analysis of environmental effects. Taking the example project as an example, the project is located in the northwest region with dry climate and large temperature difference between day and night2. Saline soil is widely distributed in the shallow layer of the site, and the underground water and soil contain Cl - and SO4 2- and other strongly corrosive ions. Through preliminary on-site exploration, it is initially judged that the on-site environment will affect the mechanical properties and durability of some structural components.

[0077] 2. Durability analysis. Based on Fick's first law and Fick's second law, a diffusion theory model considering mix ratio parameters, environmental temperature, the binding effect of concrete materials on erosion media, the time-dependent diffusion coefficient, the stress state of concrete, and the material deterioration effect is established to analyze and calculate the carbonation depth of concrete and the chloride ion concentration on the surface of steel bars. Taking the example project as an example, the analysis and calculation show that the carbonation depth of concrete is 5.5 mm, and the chloride ion concentration at the surface of steel bars is 0.0030 mas% (the critical chloride ion concentration causing steel bar corrosion is 0.052 mas%). It will not affect the structural durability and no special treatment is required.

[0078] 3. Further analyze the raw material properties, construction technology, and construction records. Taking the example project as an example, the original concrete grade is C20, which is easy to construct; the domestic cement technology (fineness) during the construction period of this project is beneficial to the structural durability, and there is no requirement for increasing the water-cement ratio by pumping as it is now. Therefore, the original concrete of the building is usually denser, which is beneficial to durability. The original design of this project has a waterproof coiled material wrapped around the underground part as a whole. According to the principle of concrete structure durability, additional anti-corrosion measures can extend the service life of the structure.

[0079] 4. Measure the performance of components on-site. While conducting mechanical analysis on the specimens cured under the same conditions on-site, core samples of concrete are taken from typical components for analysis of the mechanical properties of the existing structure.

[0080] 5. Based on the above research, determine the selection of design values adopted in the seismic review work to truly reflect the mechanical properties and bearing capacity of the existing buildings to the greatest extent.

[0081] III. Determine the numerical calculation model, reasonable load actions and simulation calculation for the existing nuclear safety-related plants.

[0082] 1. Model establishment. According to the design drawings, use the powerful general finite element software ANSYS and the special structural design software PKPM for seismic performance evaluation. The example project is a completed project. During the establishment of the calculation model, fully consider its own characteristics and the actual situation of the project, different from the normal structural design stage, reasonably reduce the calculation conservatism, and strive to make the calculation analysis results a true reflection of the structural stress situation, so as to achieve a fair evaluation of the structural seismic performance. For the seismic joints, adopt the method of establishing rigid domains to simplify the force model, rationalize the stiffness matrix, and improve the stability of the calculation analysis.

[0083] 2. Load input. Apply loads such as self-weight, temperature, earthquake, hydrostatic pressure, earth pressure, fixed equipment loads, etc. The earthquake action adopts the method of seismic margin assessment, fully considering various uncertainties, the median and plasticity of materials, etc.

[0084] Load combination, with a total of three working conditions. Among them, the normal operation condition includes: ① 1.4D + 1.7L, ② 1.05D + 1.3L + 1.05T0; the normal operation plus extreme environment condition: ③ D + L + T0 + E2. Among them,

[0085] D, permanent load, including structural self-weight, hydrostatic pressure, earth pressure, fixed equipment loads, etc.;

[0086] L, live load, including movable equipment loads and other variable loads (such as personnel weight, temporary loads during maintenance, etc.);

[0087] T0, temperature action during normal operation or shutdown;

[0088] E2, earthquake action generated by the ultimate safety seismic motion, including the earthquake action of pipelines and equipment caused by the ultimate safety seismic motion.

[0089] 3. Simulation calculation. Taking the example project as an example, the response spectrum analysis method is used for seismic calculation, and the seismic spectra in three directions (two horizontal components and one vertical component) are respectively input at the bottom of the factory building model. When using the response spectrum method for analysis, the total mass participation coefficient of each vibration mode should be controlled to reach more than 90%. In the response spectrum and equivalent static analysis, the combination of the three components of ground motion adopts the following method: in the response spectrum analysis, the responses of each mode in the three seismic directions are combined by the CQC method; the seismic results in the three directions are combined by the NEWMARK criterion.

[0090] IV. Evaluate the overall seismic performance of the structure.

[0091] Carry out bearing capacity calculation to obtain the reinforcement calculation results of different parts of the factory building under the new seismic level, compare them with the original structure reinforcement, and judge whether the actual reinforcement of the structure meets the requirements of the new seismic level. Different evaluation criteria are adopted for different functional areas to evaluate the overall seismic performance of the structure. Taking the example project as an example, the analysis is as follows:

[0092] 1. Example of the underground part of the factory building. Select typical wall panels of the structure, list the calculation results and the comparison with the original structure reinforcement, as shown in Table 1.

[0093] The results of seismic review calculation show that: in the storage pool area, the actual reinforcement amounts of the pool walls around the storage pool and the pool bottom slab can meet the requirements of the new seismic level, and the wall and slab components of the storage pool remain elastic and do not fail; the foundation slab and some walls at the leak detection room can also meet the requirements of the new seismic level; the reinforcement amounts of the remaining components in this area do not meet the requirements of the new seismic level, such as JLQ1 in Table 1. In the emergency pool area and the process supporting factory building area, except for a few individual walls whose reinforcement can meet the requirements of the new seismic level, the reinforcement amounts of the vast majority of walls and slabs do not meet the requirements.

[0094] Table 1 Reinforcement results of walls and slabs in the underground storage pool area

[0095]

[0096]

[0097] 2. Example of the above-ground part of the factory building. The original design adopted a single-slope steel roof truss and a precast concrete roof beam respectively. Color steel plates were laid on the single-slope steel roof truss, and large concrete roof slabs were laid on the concrete roof beam. The span of the above-ground structure of the storage pool part is 17m, which is a non-standard span. The steel roof truss originally designed was modified from the steel roof truss applicable to the 9-degree area in "Trapezoidal Steel Roof Truss" (05G511). The connection between the single-slope steel roof truss and the top of the bent column, and the upper and lower chord bracings of the single-slope steel roof truss all adopt the 9-degree structure in 05G511. The self-weight of the color steel plates on the steel roof truss is small, and the connection with the steel roof truss mainly considers the reliability under the designed wind load.

[0098] The span of the process supporting building is 12m. The precast concrete roof beams are selected from the roof beams in the "Reinforced Concrete Roof Beams" (G353-3) atlas applicable to the 9-degree zone, and the large roof slabs are selected from the "1.5m x 6.0m Prestressed Concrete Roof Slabs" (G410). The connections between the roof beams and the bent columns and between the roof slabs and the roof beams both adopt the structural details in the corresponding atlas for the 9-degree zone. Therefore, the steel roof trusses and precast concrete roof beams in this project meet the structural design requirements for the 9-degree seismic fortification intensity zone for civil buildings, that is, they meet the design performance objectives of "elastic under minor earthquakes, repairable under moderate earthquakes, and not collapsing under major earthquakes" corresponding to the 9-degree zone.

[0099] According to the "Code for Seismic Design of Buildings" (GB50011-2010), the zero-period acceleration of the horizontal seismic response spectrum in the 9-degree zone under rare earthquakes is 0.63g. The acceleration response spectrum of the site under rare earthquakes is shown in Table 2.

[0100] Table 2 Acceleration Response Spectrum of Rare Earthquakes in the 9-degree Zone

[0101] Period (s) 0 0.1 0.4 2 6 Acceleration (g) 0.63 1.4 1.4 0.33 0.21

[0102] Comparison of the acceleration response spectrum of rare earthquakes in the 9-degree zone and the acceleration response spectrum under the ultimate safety seismic ground motion level after seismic review is as Figure 3 shown.

[0103] As can be seen from Table 2 and Figure 3 it can be seen that the acceleration response spectrum of rare earthquakes at the 9-degree level can basically cover the acceleration response spectrum at the ground surface of the site. The civil code system in our country requires that the structure does not collapse or suffer serious damage endangering life under rare earthquakes. The steel roof trusses and precast concrete roof beams in this project meet the structural design requirements for the 9-degree seismic fortification intensity zone for civil buildings. Therefore, it can be considered that the original design can achieve "not collapsing under major earthquakes" for the roof system under the action of the new seismic level, and it will not endanger the safety functions of the radiochemical safety-class items of this project.

[0104] V. Reinforcement and renovation.

[0105] Reinforcement and renovation measures are proposed for the components of the existing nuclear safety-related buildings that do not meet the stress requirements. The reinforcement and renovation measures are evaluated from multiple dimensions such as the reinforcement scope, engineering quantity, implementation difficulty, construction period, and cost. Taking the example project as an example, the reinforcement and renovation suggestions are as follows.

[0106] 1. The project structure belongs to seismic category I structures. At present, there is a lack of relevant code standards for the reinforcement and renovation of nuclear safety-related structures at home and abroad, and there is no similar engineering practice experience. Therefore, an expert demonstration meeting should be held for the reinforcement and renovation plan, and it can only be implemented after sufficient demonstration.

[0107] 2. The scope of reinforcement and renovation of the project structure is large and involves a large number of components. There will be certain differences in the mechanical properties of the structure after reinforcement and renovation compared with the original structure, which may lead to changes in the floor response spectrum and affect the seismic analysis of pipelines, equipment, etc. in related specialties. It is necessary to re-conduct the seismic analysis of the floor response spectrum and pipelines and equipment according to the reinforcement plan.

[0108] A method for evaluating the concrete structure performance of existing nuclear safety-related plants provided in this embodiment maximally applies the concept of structural performance design, enabling the existing plants to continue to be put into use as much as possible, and playing a promoting role in the development and improvement of the structural design technology of nuclear safety-related plants. This method is technologically advanced, safe and reliable, simple to implement, and highly feasible. This embodiment can also be used in the evaluation of the performance of other existing structures with special requirements in nuclear engineering.

[0109] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A method for evaluating the performance of concrete structures in nuclear safety-related plants, characterized in that, It includes the following steps: (1) Taking the failure safety risk of the existing nuclear safety-related plant as the evaluation point, dividing it into structural areas with different seismic requirements, and formulating different structural review standard requirements; (2) Conducting durability evaluation and strength analysis of the plant to determine the current mechanical properties and bearing capacity of the existing structural components of the plant, conducting analysis on the existing bearing capacity of the plant's structural components, and determining the selection of the design value for seismic review work; (3) Determining the numerical calculation model of the existing nuclear safety-related plant, applying load effects to the model, and then conducting performance simulation calculations; (4) Macroscopically evaluating the overall seismic performance of the existing nuclear safety-related plant according to the results of performance simulation calculations.

2. The method for evaluating the performance of the concrete structure of the existing nuclear safety-related buildings according to claim 1, wherein, The failure safety risks of the plant in step (1) include: nuclear critical safety risk, nuclear leakage risk.

3. The method for evaluating the performance of the concrete structure of the existing nuclear safety-related plant according to claim 1 or 2, characterized in that Step (1) specifically includes: Starting from the service function of the existing nuclear safety-related plant, dividing the concrete structure of the nuclear safety-related plant into different structural areas; Taking the failure safety risk of the plant as the evaluation point, dividing the structural areas with different service functions into structural areas with different seismic requirements; Formulating different structural review standard requirements for structural areas with different seismic requirements.

4. The method for evaluating the performance of the concrete structure of the existing nuclear safety-related plant according to claim 1, wherein, Step (2) specifically includes: Conducting analysis on the failure mechanism of the concrete structure of the existing nuclear safety-related plant; Conducting durability evaluation and strength analysis of the plant through theoretical model derivation and evaluation; Analyzing the raw materials, construction technology and construction records of the existing nuclear safety-related plant; Conducting on-site inspection of the existing facilities of the existing nuclear safety-related plant; Determining the current mechanical properties and bearing capacity of the existing structural components of the existing nuclear safety-related plant.

5. The method for evaluating the performance of the concrete structure of the existing nuclear safety-related plant according to claim 1, wherein Step (3) specifically includes: Establishing a three-dimensional finite element numerical calculation model of the existing nuclear safety-related plant; Applying real loads to the model according to the actual situation, and removing the structural conservatism brought by uncertainties in the design stage; Conducting load combination and performance simulation numerical calculations.

6. The method for evaluating the performance of the concrete structure of the existing nuclear safety-related plant according to claim 5, characterized in that, Real loads include any one or more of self-weight, temperature, earthquake, hydrostatic pressure, earth pressure, and fixed equipment load.

7. The method for evaluating the performance of the concrete structure of the existing nuclear safety-related plant according to any one of claims 1, 2, 4 to 6, characterized in that After step (4), it further includes: Step (5) Proposing reinforcement and renovation measures for the components of the existing nuclear safety-related plant that do not meet the force requirements.

8. The method for evaluating the performance of the concrete structure of the existing nuclear safety-related plant according to claim 7, characterized in that, Step (5) also includes: Evaluating the reinforcement and renovation measures from multiple dimensions including reinforcement scope, engineering quantity, implementation difficulty, construction period, and cost.

9. The method for evaluating the performance of the concrete structure of the existing nuclear safety-related plant according to claim 7, wherein After step (5), it further includes: Step (6) Avoiding the possible risks of the existing nuclear safety-related plant from the perspective of management and operation.

10. The method for evaluating the performance of the concrete structure of the existing nuclear safety-related plant according to claim 9, wherein The perspective of management and operation in step (6) includes any one or more of cost, personnel management, and on-site feasibility.

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