Method for predicting service life of a nuclear power plant reactor pit concrete structure and device therefor

Abstract

The present application relates to the technical field of time limit aging analysis of nuclear power plant reactor pit concrete structure, and provides a service life prediction method and device for nuclear power plant reactor pit concrete structure, aiming at objectively and accurately evaluating the performance degradation and life prediction technology problem of reactor pit concrete structure under the irradiation-heat-force coupling effect, through reactor pit concrete irradiation test research and numerical simulation research, a reactor pit concrete performance degradation and life prediction model under the joint action of multiple phases, multiple scales and multiple factors is established, and based on the service life prediction model of the concrete compressive strength threshold and / or the reactor pit concrete damage depth threshold, the objective accuracy of predicting the service life of the nuclear power plant reactor pit concrete structure is improved.

Description

Technical Field

[0001] This invention belongs to the field of time-limited aging analysis technology for concrete structures in nuclear power plant reactor pits, specifically relating to a method and apparatus for predicting the service life of concrete structures in nuclear power plant reactor pits. Background Technology

[0002] The concrete structure of a nuclear power plant reactor sump serves to support the reactor pressure vessel and shield it from radiation from the reactor core. As a non-replaceable component of the nuclear power plant, the durability of the reactor cavity concrete is a prerequisite for the long-term stable and safe operation of the plant. Under high-temperature, neutron irradiation, and gamma-ray irradiation conditions, the concrete performance of the reactor cavity concrete deteriorates. Therefore, factors affecting the durability of the reactor cavity concrete structure must consider not only these three conditions but also the degradation of its mechanical and shielding properties due to the coupled effects of these conditions. This degradation directly impacts the long-term stable and safe operation of the nuclear power plant. Therefore, in-depth research is needed on the degradation mechanism of reactor cavity concrete performance under these three conditions and their coupled effects, as well as on life prediction technologies, to provide a scientific basis for the long-term stable and safe operation of nuclear power plants.

[0003] Concrete is a multiphase composite material, with its composition ranging from nanoscale / micrometer-scale calcium silicate hydrate (CSH) to millimeter-scale sand and gravel. To investigate the performance degradation mechanism of cavity concrete under high temperature, neutron irradiation, and gamma irradiation, foreign scholars have conducted extensive high-temperature irradiation experiments on concrete. Studies have shown that at temperatures above 90℃ (the service temperature of cavity concrete), even when the concrete is kept at a constant temperature, its performance continues to decline; when the neutron flux is greater than 1×10⁻⁶, the degradation continues. 19 n / cm2 or gamma ray dose greater than 2×10 8 At Gy levels, concrete properties are significantly reduced; therefore, high temperatures, neutron radiation, and gamma irradiation cause irreversible degradation of concrete. However, the experimental conditions used in these studies are not representative and do not align with the service environment of nuclear power plant concrete. Consequently, most experimental studies on high temperatures, neutron radiation, and gamma irradiation are either experimental observations or qualitative descriptions of material properties induced by different levels of irradiation. Relying on existing experimental data makes it difficult to accurately assess the degradation patterns of nuclear power plant sump concrete under high-temperature irradiation.

[0004] In recent years, research institutions in many countries have conducted numerical simulations of concrete irradiation and proposed several numerical models for concrete irradiation. For example, the thermo-hydro-radiation coupled viscoelastic failure model proposed by Pomar et al. in 2011 is one of the earliest models in the field of concrete irradiation numerical simulation; LePape et al. also proposed a micro-mechanical model in 2015. These models can explain some of the behavior of concrete under irradiation, such as the temperature change of concrete samples under irradiation. However, these models have inherent limitations, such as not considering the influence of heterogeneous microstructures, making it difficult to obtain reliable macroscopic bearing capacity responses.

[0005] The technology for predicting the performance degradation and lifespan of nuclear power plant reactor cavity concrete under high temperature, neutron irradiation, and gamma irradiation faces the following challenges:

[0006] (1) Numerical simulation of concrete irradiation in the slab cavity

[0007] The composition of concrete in the crater is complex, consisting of multiple different phases, and the various constituent materials also vary in distribution, size, and shape. The microstructure and mesostructure of concrete are very complex, making it difficult to simulate accurately. At the same time, the damage process of concrete under irradiation is multi-scale in both time and space. Therefore, constructing a multi-scale model of micro-meso-macro to perform multi-scale numerical simulation of concrete irradiation damage is one of the main challenges in numerical simulation of concrete irradiation.

[0008] (2) Model for predicting the performance degradation and lifespan of concrete in sump pits

[0009] The performance degradation of reactor cavity concrete under high-temperature irradiation is the result of multiple factors, including temperature, neutron irradiation, gamma irradiation, creep, humidity, load, and thermal-hydraulic factors. Taking all these factors into account would result in a very large and complex model, requiring extensive computation and proving difficult to implement. Therefore, constructing an easily implementable model for the performance degradation and life prediction of nuclear power plant reactor cavity concrete is one of the main challenges in numerical simulation of concrete irradiation.

[0010] (3) Irradiation test of concrete in the sump

[0011] Currently, it is difficult to accurately assess the performance degradation law of nuclear power plant reactor pit concrete under high-temperature irradiation based on existing experimental data. The performance degradation and life prediction model of nuclear power plant reactor pit concrete obtained based on irradiation numerical simulation cannot be applied to the performance degradation and life prediction of reactor cavity concrete under high-temperature irradiation environment. The lack of experimental data and irradiation numerical models obtained from reactor cavity concrete irradiation tests makes it difficult to accurately evaluate the performance degradation and life prediction of nuclear power plant reactor pit concrete. Therefore, establishing an accurate performance degradation and life prediction model of nuclear power plant reactor pit concrete is one of the industry's challenges in the aging management and life assessment of nuclear power plant reactor pit concrete.

[0012] In summary, there is an urgent need to conduct irradiation tests and numerical simulations of reactor cavity concrete, establish a multi-phase, multi-scale, and multi-factor-dependent model for predicting the performance degradation and lifespan of reactor cavity concrete, and objectively and accurately evaluate the performance degradation and lifespan prediction of nuclear power plant reactor sump concrete in order to solve the industry's challenges in aging management and lifespan assessment of nuclear power plant reactor sump concrete. Summary of the Invention

[0013] One of the objectives of this invention is to provide a method and apparatus, computer program product and computer equipment for predicting the service life of concrete structures in nuclear power plant reactor pits. The service life prediction model based on the concrete compressive strength threshold and / or the service life prediction model based on the damage depth threshold of the reactor pit concrete solves the technical problems of performance degradation and service life prediction of reactor pit concrete structures under high temperature irradiation service environment, and further solves the industry problems of aging management and service life assessment of concrete structures in nuclear power plant reactor pits.

[0014] The second objective of this invention is to provide a method for obtaining a service life prediction model of the concrete structure of a nuclear power plant reactor pit, along with its computer program product and computer equipment. This solves the technical problem of the difficulty in accurately simulating the irradiation of reactor pit concrete; it also solves the technical problem of the complexity of the irradiation-thermal-mechanical coupling effect performance degradation and service life prediction model of reactor pit concrete obtained based on irradiation numerical simulation, which results in a large amount of computation and is difficult to implement; and further solves the technical problem of objectively and accurately evaluating the performance degradation and service life prediction of reactor pit concrete structure under irradiation-thermal-mechanical coupling effect.

[0015] Technical solution for achieving one of the objectives of this invention:

[0016] A method for predicting the service life of concrete structures in nuclear power plant reactor pits includes the following steps:

[0017] S1. Obtain the actual fast neutron irradiation dose accumulation rate of the concrete structure of the nuclear power plant crater under real service conditions;

[0018] S2. A service life prediction model based on the concrete compressive strength threshold and / or a service life prediction model based on the crater concrete damage depth threshold, to predict the service life of the concrete structure of the nuclear power plant crater.

[0019] The service life prediction model based on the concrete compressive strength threshold described in step S2 predicts the service life of the concrete structure of the nuclear power plant crater, including the following steps:

[0020] Based on the service life prediction model (1) using the concrete compressive strength threshold, the service life t1 of the concrete structure in the nuclear power plant crater is calculated:

[0021] (1),

[0022] in: The service life is based on the allowable threshold of the compressive strength of concrete structures, and is expressed in years (a). This represents the threshold compressive strength of concrete, expressed in MPa. This represents the compressive strength of concrete before expansion, expressed in MPa. The fast neutron irradiation dose accumulation rate is expressed in n / (cm²). 2 (a); m and n are correlation coefficients.

[0023] The correlation coefficient m ranges from -15 to m to 10; the correlation coefficient n ranges from 80 to n to 100.

[0024] Furthermore, the correlation coefficient m ranges from -10 to m to 0; the correlation coefficient n ranges from 90 to n to 100.

[0025] The service life prediction model based on the concrete structure damage depth threshold described in step S2 predicts the service life of the concrete structure of the nuclear power plant reactor pit, including the following steps:

[0026] Based on the service life prediction model (2) of the concrete damage depth threshold of the nuclear power plant crater, the service life t2 of the concrete structure of the nuclear power plant crater is calculated:

[0027] (2),

[0028] The cumulative fast neutron irradiation dose threshold for the concrete structure of the sump pit in formula (2) :

[0029]

[0030] in: Service life based on concrete damage depth threshold, in years (a). Fast neutron irradiation dose accumulation rate, in units of n / (cm²). 2.a); The cumulative fast neutron radiation dose threshold for the concrete structure of the crater, in units of 10-1. 19 n / cm 2 a, b, and c are correlation coefficients; C is a constant; d t This represents the threshold for the depth of concrete damage in the sump, expressed in mm.

[0031] The correlation coefficient α ranges from 1 to 2; the correlation coefficient b ranges from 20 to 30; the correlation coefficient c ranges from 180 to 200; and the constant C ranges from 420 to 470.

[0032] The correlation coefficient α has a range of 1 ≤ a ≤ 1.5; the correlation coefficient b has a range of 22 ≤ b ≤ 27; the correlation coefficient c has a range of 185 ≤ c ≤ 195; and the constant C has a range of 420 ≤ C ≤ 470.

[0033] Further step S2, using the service life prediction model based on concrete compressive strength threshold and the service life prediction model based on concrete damage depth threshold, predicts the service life of the concrete structure in the nuclear power plant reactor pit, including the following steps:

[0034] A service life prediction model based on concrete strength damage threshold is used to predict the service life t1 of concrete structures in nuclear power plant sump pits.

[0035] Based on the service life prediction model of concrete damage depth threshold, the service life t2 of the concrete structure of nuclear power plant crater is calculated.

[0036] The minimum service life of two types of nuclear power plant reactor pit concrete structures was selected as the service life t of the nuclear power plant reactor pit concrete structure under actual service conditions.

[0037] (3).

[0038] A device for predicting the service life of a concrete structure in a nuclear power plant reactor pit, the device comprising:

[0039] Acquisition module: used to obtain the actual fast neutron irradiation dose accumulation rate of the concrete structure of the nuclear power plant crater under real service conditions;

[0040] Prediction module: Used to predict the service life of concrete structures in nuclear power plant sumps using a service life prediction model based on a concrete compressive strength threshold and / or a service life prediction model based on a sump concrete damage depth threshold.

[0041] A computer program product includes a computer program that, when executed by a processor, implements any of the above-described methods for predicting the service life of concrete structures in nuclear power plant sump pits.

[0042] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described methods for predicting the service life of concrete structures in nuclear power plant sump pits.

[0043] A computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement any of the above-described methods for predicting the service life of concrete structures in nuclear power plant reactor pits.

[0044] Technical solution for achieving the second objective of this invention:

[0045] A method for obtaining a service life prediction model for the concrete structure of a nuclear power plant reactor pit includes the following steps:

[0046] Y1. Obtain concrete material parameters and test conditions;

[0047] Y2. Irradiation numerical simulation,

[0048] A multi-scale model of micro-meso-macro scales was constructed to conduct multi-scale numerical simulation of concrete irradiation damage.

[0049] Y3. Numerical simulation calculation of irradiation

[0050] Numerical simulation calculations of non-uniform temperature and mechanical field irradiation were used to obtain the temperature change curve of concrete material after fast neutron irradiation.

[0051] Y4. Irradiation numerical simulation test

[0052] Simulation tests were conducted on the mechanical properties and volume expansion rate of concrete materials after fast neutron irradiation.

[0053] Y5. Construct a predictive model for the performance degradation and service life of concrete structures under the coupled effects of irradiation, heat, and force, based on numerical simulation of irradiation.

[0054] The simulation data obtained from the above irradiation numerical simulation test were fitted to construct the relationship between irradiation time and aggregate volume expansion rate, the relationship between compressive strength of concrete structure and neutron flux, and the relationship between damage depth of pile pit concrete structure and neutron flux.

[0055] Y6. Construct a predictive model for the performance degradation and service life of concrete structures under irradiation-thermal-mechanical coupling based on experimental data correction.

[0056] Using experimental data, the above-mentioned equations relating irradiation time to aggregate volume expansion rate, compressive strength of concrete pile pits to neutron flux, and damage depth of concrete pile pits to neutron flux were revised.

[0057] The concrete material parameters mentioned in step Y1 include, but are not limited to: concrete sample size; aggregate type, aggregate gradation, and aggregate volume fraction; compressive strength, tensile strength, elastic modulus, thermal expansion coefficient, thermal conductivity, and surface heat dissipation coefficient of mortar and aggregate; and the test conditions include, but are not limited to: fast neutron irradiation dose or fast neutron flux, and volumetric heat flux.

[0058] Step Y2 involves constructing a multi-scale model (micro-meso-macro) to simulate concrete irradiation damage at multiple scales. The model possesses characteristics at three scales: micro, meso, and macro, and these three spatial scales are interconnected. At the micro scale, the properties of each component of the concrete are analyzed from a physical mechanism perspective, and the results serve as input parameters for the mesostructure. At the meso scale, a numerical model of a small concrete sample is established, and its mechanical properties are analyzed to obtain the damage constitutive relationship of the small sample, which serves as input parameters for the macroscopic mechanical property analysis. At the macro scale, the entire concrete pile is modeled and its mechanical properties are analyzed to predict changes in the mechanical properties of the concrete pile over its lifespan.

[0059] Further step Y2 involves constructing a multi-scale model (micro-meso-macro) to perform multi-scale numerical simulations of concrete irradiation damage. The micro-scale model models the atomic composition of concrete aggregates, obtaining the relationship between neutron flux and aggregate swelling rate, and constructing a constitutive model and parameters for the concrete aggregates. The properties of the concrete aggregates under irradiation conditions are used as input parameters for the meso-structure. The meso-scale model models small concrete samples, constructing a meso-scale model of the random aggregates in the small samples. Mechanical property analysis is performed through numerical simulation of uniaxial compression tests on the small samples, thereby obtaining the damage constitutive relationship of the irradiated small samples. This is further compared and verified with typical concrete irradiation experiments and used as input parameters for macro-mechanical property analysis. The macro-scale model models the entire pile pit concrete, performing numerical analysis of the overall mechanical properties of the pile pit concrete through the distribution of neutron and gamma irradiation fluxes, to predict changes in the mechanical properties of the pile pit concrete over its lifespan.

[0060] The temperature change curve of the concrete material after fast neutron irradiation in step Y3 includes, but is not limited to: the temperature distribution curve inside the concrete, the temperature rise curve between the center and the surface of the concrete, and the temperature gradient curve inside the concrete.

[0061] The mechanical property simulation test of concrete material after fast neutron irradiation described in step Y4 involves applying uniaxial compression and tensile loads to the concrete material under different irradiation times to obtain the continuous change curves of ultimate compressive strength, tensile strength, and elastic modulus of the concrete material after different irradiation times.

[0062] The step Y4, which involves simulating the volume expansion rate of concrete material after fast neutron irradiation, involves measuring the volume expansion of the concrete material before and after irradiation and calculating the volume expansion rate of the concrete before and after irradiation.

[0063] The relationship between irradiation time and aggregate volume expansion rate in step Y5 is expressed as equation (4):

[0064] (4),

[0065] In relation (4): K1 and K2 are correlation coefficients. The range of correlation coefficient K1 is 0≤K1≤1, and the range of correlation coefficient K2 is 1≤K2≤5. They are dimensionless quantities. Let be the volumetric expansion rate of the aggregate, be a percentage, and be a dimensionless quantity. Neutron fluence with E > 0.1 MeV, expressed in n / cm². 2 .

[0066] In further step Y5, based on the relationship between irradiation time and aggregate volume expansion rate, the neutron injection is converted into the corresponding aggregate volume expansion rate. The aggregate volume expansion rate reflects the influence of neutron injection on the compressive strength of concrete. The relationship equation (5) between the compressive strength of the concrete structure and the neutron injection is obtained.

[0067] (5),

[0068] In the relational equation (5): m and n are the correlation coefficients. The range of the correlation coefficient m is -15≤m≤10, and the range of the correlation coefficient n is 80≤n≤100. This represents the compressive strength of concrete before expansion, expressed in MPa. The compressive strength of concrete after irradiation swelling is expressed in MPa. Neutron fluence with E > 0.1 MeV, in units of 10-1. 19 n / cm 2 .

[0069] The equation (6) relating the damage depth of the concrete structure in the crater to the neutron flux in step Y5 is as follows:

[0070] C (6),

[0071] In the relational equation (6): a, b, and c are correlation coefficients. The value range of correlation coefficient a is 1 ≤ a ≤ 2, the value range of correlation coefficient b is 20 ≤ b ≤ 30, and the value range of correlation coefficient c is 180 ≤ c ≤ 200; C is a constant, and the value range of constant C is 420 ≤ C ≤ 470; d is the complete damage depth of the concrete in the pit from the inner surface, in mm. Neutron fluence with E > 0.1 MeV, in units of 10-1. 19 n / cm 2 .

[0072] In step Y6, the relationship between irradiation time and aggregate volume expansion rate is corrected using experimental data. After correction using data from irradiation accelerated aging test and high temperature accompanying test, the correlation coefficient K1 ranges from 0 to 0.5, and the correlation coefficient K2 ranges from 1.5 to 2.

[0073] In step Y6, the relationship equation between the compressive strength and neutron flux of the concrete structure of the sump pit is modified using experimental data. After modification based on the data from the accelerated aging test and the high temperature accompanying test, the correlation coefficient m ranges from -10 to m to 0, and the correlation coefficient n ranges from 90 to n to 100.

[0074] In step Y6, the relationship equation between the damage depth and neutron flux of the concrete structure in the crater is corrected using experimental data. Based on the data from the accelerated aging test and the high temperature accompanying test, the correlation coefficient a ranges from 1 to 1.5; the correlation coefficient b ranges from 22 to 27; and the correlation coefficient c ranges from 185 to 195.

[0075] The irradiation accelerated aging test and high-temperature accompanying test data include, but are not limited to: damage and failure modes of concrete under different irradiation times after applying uniaxial compression and tensile loads in a hot chamber environment, and obtaining continuous change curves of ultimate compressive strength, tensile strength and elastic modulus of concrete after different irradiation times; the volume expansion of concrete aggregate after irradiation is tested in a hot chamber environment, and the volume expansion rate of concrete before and after irradiation is calculated in combination with the previously measured concrete aggregate size before irradiation.

[0076] A computer program product includes a computer program that, when executed by a processor, implements the steps of any one of the methods described above for obtaining a service life prediction model of a nuclear power plant reactor pit concrete structure.

[0077] A computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of any one of the methods for obtaining a service life prediction model of a nuclear power plant reactor pit concrete structure.

[0078] A computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement any of the steps of the method described above for obtaining a service life prediction model of a nuclear power plant reactor pit concrete structure.

[0079] The beneficial effects of the technical solution of this invention are as follows:

[0080] (1) This invention uses the actual neutron irradiation dose accumulation rate of the concrete structure of the nuclear power plant reactor pit under real service conditions, and a service life prediction model based on the concrete compressive strength threshold, to predict the service life of the concrete structure of the nuclear power plant reactor pit. The comparison between the irradiation numerical simulation results and the experimental results of the concrete compressive strength after Maruyama neutron irradiation shows that the irradiation numerical simulation results are very close to the experimental results. On the one hand, the overall trend is the same: before the concrete expansion rate is 0.5%, the peak stress decreases rapidly; after the concrete expansion rate is 0.5%, the peak stress decreases very slowly, and the final peak stress tends to stabilize. On the other hand, the values ​​are roughly similar: when the concrete expansion rate is 0.5%, the peak stress decreases by about 30%; when the concrete expansion rate is 2.5%, the peak stress decreases by about 40%. By summarizing and comparing the irradiation numerical simulation prediction results under neutron irradiation and temperature with the corresponding irradiation test results, the reduction rate of compressive strength is obtained as R. 2 =87%>80%, indicating high accuracy.

[0081] (2) This invention uses the actual cumulative rate of neutron irradiation dose of the concrete structure of the nuclear power plant sump under real service conditions, and predicts the service life of the concrete structure of the nuclear power plant sump based on the service life prediction model of the sump concrete damage depth threshold, and learns about the sump concrete damage at different ages: after 15 years of reactor operation, neutron irradiation causes almost no damage to the sump concrete; after 30 years of reactor operation, the concrete near the inner surface of the sump concrete begins to be damaged; after 60 years of reactor operation, the range of severe concrete damage caused by neutron irradiation reaches a depth of about 40 mm from the inner surface. The comparison with the simulation results of Kambayas in 2020 shows that the interconnected cracks generated within 50 mm are roughly the same.

[0082] (3) The service life prediction model based on the concrete compressive strength threshold and the service life prediction model based on the damage depth threshold of the nuclear power plant sump concrete obtained by combining irradiation numerical simulation and irradiation accelerated aging test and high temperature accompanying test, compared with the concrete service life prediction model obtained by single irradiation numerical simulation, improves the accuracy of service life prediction of nuclear power plant sump concrete structure.

[0083] (4) This invention employs a micro-meso-macro multi-scale model for multi-scale numerical simulation of concrete irradiation damage. The constructed model possesses micro-meso-macro multi-scale characteristics and considers the influence of neutron, gamma irradiation, and temperature. Furthermore, the three spatial scale models (micro-meso-macro) are interconnected, improving the accuracy of numerical simulation of concrete irradiation in nuclear power plant craters. This invention selects key factors such as temperature, neutron irradiation, and gamma irradiation to construct a service life prediction model based on the concrete compressive strength threshold and a service life prediction model based on the crater concrete damage depth threshold. These models are simple, practical, computationally efficient, and easy to implement. Attached Figure Description

[0084] Figure 1 A schematic diagram of the process for predicting the performance degradation and lifespan of concrete in a stockpile pit.

[0085] Figure 2 Image of concrete sample;

[0086] Figure 3 Flowchart for multi-scale numerical simulation of concrete irradiation damage;

[0087] Figure 4 Comparison of simulated and experimental results of volume expansion rate;

[0088] Figure 5 A comparison of the numerical simulation results of irradiation with the experimental results of the compressive strength of concrete after Maruyama neutron irradiation;

[0089] Figure 6 R² plot of intensity reduction between numerical simulation predictions and irradiation experiments.

[0090] Figure 7 This invention predicts the concrete damage in sump pits at different ages. Detailed Implementation

[0091] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0092] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products or devices.

[0093] Example 1.

[0094] By obtaining fast neutron irradiation dose from the irradiation dose sensor readings in the concrete area of ​​the nuclear power plant crater, the cumulative rate of fast neutron irradiation dose can be calculated. Combined with the compressive strength threshold and damage depth threshold of the crater concrete structure, the service life of the crater concrete structure under actual service conditions can be calculated, thereby assessing the service status and safety of the crater concrete.

[0095] Based on the compressive strength threshold of the concrete structure of the sump pit, the service life of the concrete structure of the sump pit under actual service conditions is calculated.

[0096] Based on the service life prediction model (1) using the concrete compressive strength threshold, the service life t1 of the concrete structure in the nuclear power plant crater is calculated:

[0097] (1),

[0098] in: The service life is based on the allowable threshold of the compressive strength of concrete structures, and is expressed in years (a). The threshold value for concrete compressive strength, in MPa, is determined by calculation and analysis of the core concrete structure. This represents the compressive strength of concrete before expansion, expressed in MPa. The fast neutron irradiation dose accumulation rate is expressed in n / (cm²). 2 a) Calculated from the radiation dose sensor readings in the concrete area of ​​the sump pit. , where t is the data acquisition time of the radiation dose sensor (in years). The radiation dose sensor acquires the cumulative fast neutron irradiation dose at time t (in n / cm²). 2 ); m and n are the correlation coefficients.

[0099] The correlation coefficient m in the numerical simulation of irradiation has a range of -15 ≤ m ≤ 0; the correlation coefficient n has a range of 90 ≤ n ≤ 100.

[0100] The range of the correlation coefficient m after the experimental data correction is -15 ≤ m ≤ 10; the range of the correlation coefficient n is 80 ≤ n ≤ 100.

[0101] By combining the damage depth threshold of the concrete structure of the sump pit, the service life of the concrete structure of the sump pit under actual service conditions is calculated.

[0102] Based on the service life prediction model (2) of the concrete damage depth threshold of the nuclear power plant crater, the service life t2 of the concrete structure of the nuclear power plant crater is calculated:

[0103] (2),

[0104] The cumulative fast neutron irradiation dose threshold for the concrete structure of the sump pit in formula (2) :

[0105]

[0106] in: Service life based on concrete damage depth threshold, in years (a). Fast neutron irradiation dose accumulation rate, in units of n / (cm²). 2 .a); The cumulative fast neutron radiation dose threshold for the concrete structure of the crater, in units of 10-1. 19 n / cm 2 Calculated from the radiation dose sensor readings in the concrete area of ​​the sump pit. , where t is the data acquisition time of the radiation dose sensor (in years). The radiation dose sensor acquires the cumulative fast neutron irradiation dose at time t (in n / cm²). 2 (a, b, and c are correlation coefficients; C is a constant; d) t This represents the threshold for the depth of concrete damage in the sump, expressed in mm.

[0107] The correlation coefficient α in the numerical simulation of irradiation has a range of 1 ≤ a ≤ 2; the correlation coefficient b has a range of 20 ≤ b ≤ 30; the correlation coefficient c has a range of 180 ≤ c ≤ 200; and the constant C has a range of 420 ≤ C ≤ 470.

[0108] The corrected correlation coefficient α ranges from 1 to 1.5; the correlation coefficient b ranges from 22 to 27; and the correlation coefficient c ranges from 185 to 195.

[0109] According to the acceptance criteria for performance degradation of concrete structures in nuclear power plant sumps, the service life of concrete structures in sumps under actual service conditions can be calculated based on the concrete compressive strength threshold and the concrete damage depth threshold. The service life corresponding to the two acceptance criteria for performance degradation of concrete structures in nuclear power plant sumps can be compared to determine the service life of concrete structures in sumps under actual service conditions.

[0110] (3),

[0111] For the sake of conservative decision-making, the smaller value corresponding to the two nuclear power plant reactor pit concrete structure performance degradation acceptance criteria is taken as the actual service life of the reactor pit concrete structure.

[0112] This invention provides a device for predicting the service life of concrete structures in nuclear power plant reactor pits, the device comprising:

[0113] Acquisition module: used to obtain the actual fast neutron irradiation dose accumulation rate of the concrete structure of the nuclear power plant crater under real service conditions;

[0114] Prediction module: Used to predict the service life of concrete structures in nuclear power plant sumps using a service life prediction model based on a concrete compressive strength threshold and / or a service life prediction model based on a sump concrete damage depth threshold.

[0115] This invention further provides a computer device, which includes a processor, a memory, an input / output interface, a communication interface, a display unit, and an input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor of this computer device provides computing and control capabilities. The memory of this computer device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface of this computer device is used for exchanging information between the processor and external devices. The communication interface of this computer device is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements the steps described in any one of the embodiments of the method for predicting the service life of a nuclear power plant sump concrete structure. The display unit of this computer device is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0116] Example 2:

[0117] A method for obtaining a service life prediction model for the concrete structure of a nuclear power plant reactor pit, such as... Figure 1 As shown, the steps are as follows:

[0118] (1) Obtaining concrete material parameters and test conditions

[0119] The parameters for obtaining concrete materials include: concrete sample size, aggregate type, aggregate gradation, aggregate volume fraction, compressive strength of mortar and aggregate, tensile strength of mortar and aggregate, elastic modulus of mortar and aggregate, coefficient of thermal expansion of mortar and aggregate, thermal conductivity of mortar and aggregate, and surface heat dissipation coefficient of mortar and aggregate.

[0120] Wherein: concrete sample size, such as Figure 2 As shown. Generally, the size of concrete specimens can be determined by the test conditions; standard specimen sizes are typically adopted. 50×50mm, suitable for ordinary concrete; small sample sizes are generally adopted. 25×25mm, suitable for limonite concrete.

[0121] Among them: aggregate gradation and aggregate volume fraction can be determined by Fuller gradation curve; aggregate volume fraction can be determined by concrete mix proportion; aggregate type in the experiment is determined according to concrete mix proportion; in numerical analysis, for coarse aggregate with a particle size greater than 5mm, under the same gradation and volume fraction conditions, it can be set as a random aggregate model of circle, ellipse, or polygon. Among them: compressive strength, tensile strength, and elastic modulus of mortar and aggregate can be determined by uniaxial compression and tensile material property tests; thermal expansion coefficient of mortar and aggregate can be measured by the indirect method of the push rod, the direct reading method of the telescope, or the laser method; thermal conductivity of mortar and aggregate can be measured by the hot wire method; surface heat dissipation coefficient of mortar and aggregate can be determined by the convective heat transfer coefficient table.

[0122] The aforementioned experimental conditions typically include: fast neutron irradiation dose (also known as fast neutron flux) and volumetric heat flux. Specifically, the neutron irradiation dose and volumetric heat flux can be obtained by reading the irradiation dose sensor inside the nuclear reactor.

[0123] (2) Numerical simulation of irradiation

[0124] Based on the aforementioned concrete material parameters and experimental conditions, a multi-scale model (micro-meso-macro) was constructed using ABAQUS finite element software to conduct multi-scale numerical simulations of concrete irradiation damage. The three spatial scales of the model—micro-meso-macro—are interconnected. The micro-scale model analyzes the properties of each component of concrete from a physical mechanism perspective, and the results can be used as input parameters for the mesoscopic structure. The mesoscale model establishes numerical models of small concrete samples, analyzes their mechanical properties to obtain the damage constitutive relationship of the small samples, and uses this as input parameters for the macroscopic mechanical property analysis. The macroscopic scale model and mechanical property analysis of the entire concrete pile in the sump are used to predict changes in the mechanical properties of the concrete pile over its lifespan.

[0125] Flowchart of multi-scale numerical simulation of concrete irradiation damage, as shown Figure 3 As shown, the constructed micro-meso-macro multi-scale model possesses characteristics of three spatial scales: micro, meso, and macro, and considers the influence of three conditions: neutron, gamma irradiation, and temperature. Furthermore, the three spatial scale models are interconnected. The micro-scale model models the atomic composition of concrete aggregates, obtains the relationship between neutron flux and aggregate swelling rate, constructs a constitutive model and parameters for concrete aggregates, and uses the properties of concrete aggregates under irradiation conditions as input parameters for the meso-structure. The meso-scale model models small concrete samples, constructing a meso-scale model of random aggregates in the small concrete samples. Mechanical property analysis is performed through numerical simulation of uniaxial compression tests on small samples, thereby obtaining the damage constitutive relationship of the irradiated small samples. This is further compared and verified with typical concrete irradiation experiments and used as input parameters for macro-mechanical property analysis. The macro-scale model models the entire pile pit concrete, performing numerical analysis of the overall mechanical properties of the pile pit concrete based on the neutron and gamma irradiation flux distribution to predict changes in mechanical properties over the lifespan of the pile pit concrete.

[0126] (3) Accelerated aging test by irradiation

[0127] In conjunction with core loading, a suitable test channel is selected, and an irradiation test apparatus is designed based on the channel structure dimensions and physical and thermal parameters. After the irradiation apparatus is fabricated, the irradiation sample is assembled and placed into the irradiation channel for irradiation testing. When the irradiation test reaches the physically calculated irradiation time, the apparatus is removed from the reactor, and the performance of the irradiation sample is tested.

[0128] (4) High temperature accompanying test

[0129] Concrete materials often experience temperature increases under radiation. Studies have shown that some irradiated concrete can reach temperatures as high as 250°C. At this temperature, even without further irradiation, concrete properties will significantly degrade. When conducting high-volume concrete irradiation tests using a fast neutron reactor, the low thermal conductivity of concrete, coupled with the confined space in the reactor core and the inability to install necessary cooling measures, can result in concrete specimen temperatures reaching 300-400°C at the center. Therefore, high-temperature single-factor tests are necessary to investigate the effects of ambient temperatures of 80°C, 300°C, and 400°C on concrete performance degradation, in order to mitigate the additional effects of excessively high in-reactor irradiation temperatures.

[0130] (5) Numerical simulation calculation of irradiation

[0131] Calculations were performed on the non-uniform temperature and mechanical fields to obtain the temperature change curves of concrete after fast neutron irradiation, including the internal temperature distribution of the concrete, the temperature rise curves at the center and surface of the concrete, and the internal temperature gradient curve of the concrete. This allowed for the determination of the damage development law within the concrete material as the fast neutron irradiation time changed. The results provide a realistic and continuous demonstration of the damage development within the concrete under fast neutron irradiation.

[0132] (6) Irradiation numerical simulation test

[0133] Mechanical property testing after irradiation numerical simulation: Damage and failure modes of concrete under different irradiation times after applying uniaxial compression and tensile loads, and continuous variation curves of ultimate compressive strength, tensile strength and elastic modulus of concrete after different irradiation times were obtained.

[0134] Volume expansion rate test after irradiation numerical simulation: The volume expansion of concrete aggregate before and after irradiation is measured. Combined with the previously measured dimensions of concrete aggregate before irradiation, the volume expansion rate of concrete before and after irradiation is calculated.

[0135] (7) Actual testing after accelerated aging test by irradiation

[0136] Dimensional testing of concrete after irradiation accelerated aging test: Damage and failure modes of concrete under different irradiation times after uniaxial compression and tensile loads are applied in a hot chamber environment. At the same time, the continuous change curves of ultimate compressive strength, tensile strength and elastic modulus of concrete after different irradiation times are obtained.

[0137] Mechanical property testing of concrete after irradiation accelerated aging test: The volume expansion of concrete aggregate after irradiation is tested in a hot chamber environment. Combined with the previously measured concrete aggregate size before irradiation, the volume expansion rate of concrete before and after irradiation is calculated.

[0138] (8) Actual test after high temperature accompaniment test

[0139] Dimensional testing of concrete after irradiation accelerated aging test: Damage and failure modes of concrete at different temperatures and times after applying uniaxial compression and tensile loads in a hot chamber environment, and continuous change curves of ultimate compressive strength, tensile strength and elastic modulus of concrete after different temperatures and times.

[0140] Mechanical property testing of concrete after irradiation accelerated aging test: The volume expansion of concrete aggregate before and after high temperature is tested in a hot chamber environment, and the volume expansion rate of concrete before and after high temperature is calculated.

[0141] (9) Construct a model for predicting the performance degradation and service life of concrete structures under the coupled action of irradiation-thermal-mechanical interaction based on irradiation numerical simulation.

[0142] Curve fitting was performed on the simulation data points obtained from the numerical simulation of irradiation to obtain the relationship between the quartz volume swelling rate and the neutron flux (4):

[0143] (4),

[0144] In relation (4), K1 and K2 are correlation coefficients. The range of K1 is 0 ≤ K1 ≤ 1; the range of K2 is 1 ≤ K2 ≤ 5. The volumetric swelling rate of quartz; Neutron fluence with E > 0.1 MeV (unit: n / cm) 2 ).

[0145] Comparison of numerical simulation data and experimental results of irradiation, such as Figure 4 As shown in the figure, the horizontal axis is uniformly logarithmic log10(x). In both the numerical simulation and the experiment, the relationship between the volume swelling rate of quartz and the neutron flux shows a trend of first increasing and then stabilizing ("S"-shaped curve). The neutron flux thresholds at which the volume swelling rate reaches its peak are very close. However, in the simulation, the neutron flux threshold at which volume swelling begins is lower than the experimental value, and the final volume swelling rate is also higher than the experimental value.

[0146] The neutron injection is converted into the corresponding aggregate volume expansion rate. The aggregate volume expansion rate reflects the influence of neutron injection on the concrete compressive strength. The corresponding relationship between relative compressive strength and neutron injection is obtained. The relationship between relative compressive strength and neutron injection is curve fitted. The relationship (5) is as follows:

[0147] (5),

[0148] In relation (5), m and n are correlation coefficients. The range of the correlation coefficient m is -15≤m≤10; the range of the correlation coefficient n is 80≤n≤100. It represents the compressive strength of concrete before expansion (in MPa), i.e., the peak stress under uniaxial compression before expansion. The compressive strength (in MPa) of concrete after irradiation and swelling during simulation or testing, i.e., the peak stress of uniaxial compression after expansion; Neutron fluence with E > 0.1 MeV (in units of 10-1). 19 n / cm 2 ).

[0149] In the simulation and analysis of the effect of neutron irradiation on the uniaxial compressive strength of concrete, the neutron injection is converted into the corresponding aggregate volume expansion rate and input into the calculation model.

[0150] That is, the neutron injection in relation (4) is reflected in the aggregate volume expansion rate in relation (5) in the simulation analysis of the effect of neutron injection on the compressive strength of concrete.

[0151] The numerical simulation results of irradiation and the experimental results of the compressive strength of concrete after Maruyama neutron irradiation are as follows: Figure 5 As shown. The experimental results published by the Maruyama research group in Japan in 2017 are summarized in... Figure 5 In comparison with the simulation results, it can be seen that the simulated results of neutron irradiation are very close to the experimental results, specifically in the following two aspects:

[0152] The overall trend is the same: before the concrete expansion rate is 0.5%, the peak stress decreases rapidly; after the concrete expansion rate is 0.5%, the peak stress decreases very slowly, and eventually the peak stress tends to stabilize.

[0153] The values ​​are roughly similar: when the concrete expansion rate is 0.5%, the peak stress decreases by about 30%; when the concrete expansion rate is 2.5%, the peak stress decreases by about 40%.

[0154] The R² graph showing the reduction in compressive strength between the irradiation numerical simulation prediction results and the experimental results is shown below. Figure 6 As shown, the numerical simulation predictions of irradiation under neutron irradiation and temperature effects are compared with the corresponding irradiation test results, and the reduction rate of compressive strength is summarized and plotted as a simulation-experiment graph, and compared with... Curve comparison, such as Figure 6 As shown. (The result is...) It has high accuracy.

[0155] By performing curve fitting on the relationship between the damage depth of the concrete in the sump and the neutron injection rate, the following relationship (6) is obtained:

[0156] (6),

[0157] In relation (6), a, b, and c are correlation coefficients. The value of a is 1≤a≤2; the value of b is 20≤b≤30; the value of c is 180≤c≤200; C is a constant with a value range of 420≤C≤470; and d is the complete damage depth of the concrete in the pit from the inner surface (in mm). Neutron fluence with E > 0.1 MeV (in units of 10-1). 19 n / cm 2 ).

[0158] Because the neutron flux decays rapidly within the crater concrete, the damage caused by changes in aggregate volumetric expansion, elastic modulus, compressive strength, and tensile strength primarily occurs near the inner surface of the crater concrete close to the reactor. When a mesh exceeds its set concrete compressibility, it can no longer bear the load. The analysis involves gradually applying the load in incremental steps (a term used in ABAQUS software for step-by-step loading) until the total aggregate volumetric expansion over a certain number of years is achieved, at which point the approximate depth of damage in the crater concrete can be obtained.

[0159] Compared with the simulation results of Kambayash in 2020, as shown Figure 7 As shown. After 15 years of reactor operation, neutron irradiation caused almost no damage to the crater concrete; after 30 years of operation, the concrete near the inner surface of the crater began to show damage; after 60 years of operation, the severe damage to the concrete caused by neutron irradiation reached a depth of approximately 40 mm from the inner surface. This is consistent with the simulation results from Kambayash in 2020, which showed that interconnected cracks were generated within approximately 50 mm.

[0160] (10) Construct a prediction model for the performance degradation and service life of concrete structures under irradiation-thermal-mechanical coupling based on experimental data correction.

[0161] Based on concrete size test data, the numerical simulation formula was corrected to obtain the relationship between quartz volume swelling rate and neutron flux:

[0162] (7),

[0163] In the formula, K3 and K4 are correlation coefficients, K3 = K1 + C1, K4 = K2 + C2, and C1 and C2 are correction constants for revising the numerical simulation relationship based on experimental data. The correction constants C1 and C2 are obtained through irradiation accelerated aging tests and high-temperature accompaniment tests. The volumetric swelling rate of quartz; Neutron fluence with E > 0.1 MeV (unit: n / cm) 2 ).

[0164] After correction of the data from the accelerated aging test and the high temperature test, the correlation coefficient K3 ranges from 0 to 0.5; the correlation coefficient K4 ranges from 1 to 3.

[0165] The volumetric expansion rate of concrete obtained from irradiation tests and high-temperature accompanying tests was correlated with its neutron injection rate, and the numerical simulation relationship for irradiation was corrected as follows:

[0166] (8),

[0167] In the formula, m1 and n1 are correlation coefficients, m1 = m + C3, n1 = n + C4, and C3 and C4 are correction constants for revising the numerical simulation relationship based on irradiation test data. It represents the compressive strength of concrete before expansion (in MPa), i.e., the peak stress under uniaxial compression before expansion. The compressive strength (in MPa) of concrete after irradiation swelling during numerical simulation or irradiation test, i.e., the peak stress of uniaxial compression after expansion; Neutron fluence with E > 0.1 MeV (in units of 10-1). 19 n / cm 2 ).

[0168] After correction of the data from the accelerated aging test and the high temperature accompanying test, the correlation coefficient m0 ​​ranges from -10 to m1 to 0; the correlation coefficient n1 ranges from 90 to n to 100.

[0169] The numerical simulation fitting equation was corrected based on the relationship between the measured damage depth of the concrete in the sump and the neutron injection rate, and the following equation was obtained:

[0170] (9),

[0171] In the formula, a1, b1, and c1 are correlation coefficients, a1=a+C5, b1=b+C6, c1=c+C7, C5, C6, and C7 are correction constants for the numerical simulation relationship based on experimental data, C is a constant, and d is the complete damage depth of the concrete in the pit from the inner surface (in mm). Neutron fluence with E > 0.1 MeV (in units of 10-1). 19 n / cm 2 ).

[0172] Among them, after correction of the data from the accelerated aging test and the high temperature accompanying test, the correlation coefficient a1 ranges from 1 to 1.5; the correlation coefficient b1 ranges from 22 to 27; and the correlation coefficient c1 ranges from 185 to 195.

[0173] The present invention also provides a computer device, which differs from the computer device described in Embodiment 1 in that: when the computer program is executed by a processor, it implements any of the steps in the above-described method for obtaining a service life prediction model of a nuclear power plant sump concrete structure.

[0174] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatuses disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant details can be found in the method section. Those skilled in the art will further recognize that the methods and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented in computer software, electronic hardware, or a combination of both. Whether these functions are implemented in software or hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention. The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly in hardware, software modules executed by a processor, or a combination of both. Software modules can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art.

Claims

1. A method of predicting the service life of a containment concrete structure of a nuclear power plant, characterized by, The method comprises the following steps in sequence: S1. obtaining the actual fast neutron irradiation dose accumulation rate of the nuclear power plant reactor pit concrete structure under real service conditions; S2. predicting the service life of the nuclear power plant reactor pit concrete structure based on a service life prediction model based on a concrete compressive strength threshold and / or a service life prediction model based on a reactor pit concrete damage depth threshold; In step S2, the service life of the nuclear power plant reactor pit concrete structure is predicted based on the service life prediction model based on the concrete compressive strength threshold, comprising the following steps: The service life t1 of the nuclear power plant reactor pit concrete structure is calculated based on the service life prediction model based on the concrete compressive strength threshold: ， Wherein: is the service life based on the allowable threshold of the compressive strength of the concrete structure, and the unit is a; is the threshold of the compressive strength of the concrete, and the unit is MPa; is the compressive strength of the concrete when not expanded, and the unit is MPa; is the fast neutron irradiation dose accumulation rate, and the unit is n / (cm 2 .a); m, n are correlation coefficients, the value range of the correlation coefficient m is -15≤m≤10; the value range of the correlation coefficient n is 80≤n≤100; In step S2, the service life of the nuclear power plant reactor pit concrete structure is predicted based on the service life prediction model based on the concrete damage depth threshold, comprising the following steps: The service life t2 of the nuclear power plant reactor pit concrete structure is calculated based on the service life prediction model based on the concrete damage depth threshold: ， wherein is the cumulative fast neutron irradiation dose threshold for the pile concrete structure: ， wherein: is the service life based on the concrete damage depth threshold, in a; is the fast neutron irradiation dose accumulation rate, in n / (cm 2 . is the cumulative fast neutron irradiation dose threshold of the reactor pit concrete structure, in 10 19 n / cm 2 ; a, b, c are correlation coefficients; C is a constant; d t is the reactor pit concrete damage depth threshold, in mm, the value range of the correlation coefficient a is 1≤a≤2; the value range of the correlation coefficient b is 20≤b≤30; the value range of the correlation coefficient c is 180≤c≤200; the value range of the constant C is 420≤C≤470.

2. The method of predicting the service life of a nuclear power plant reactor pit concrete structure according to claim 1, characterized by, The value range of the correlation coefficient m is -10≤m≤0; the value range of the correlation coefficient n is 90≤n≤100.

3. The method of claim 1, wherein the method further comprises: determining a time-dependent change in the elastic modulus of the concrete structure; and determining a time-dependent change in the creep modulus of the concrete structure. The value range of the correlation coefficient a is 1≤a≤1.5; the value range of the correlation coefficient b is 22≤b≤27; the value range of the correlation coefficient c is 185≤c≤195; the value range of the constant C is 420≤C≤470.

4. The method of claim 1, wherein the method further comprises: determining a time-dependent change in the elastic modulus of the concrete structure; and determining a time-dependent change in the creep modulus of the concrete structure. In step S2, the service life of the nuclear power plant reactor pit concrete structure is predicted based on the service life prediction model based on the concrete compressive strength threshold and the service life prediction model based on the concrete damage depth threshold, comprising the following steps: The service life t1 of the nuclear power plant reactor pit concrete structure is predicted based on the service life prediction model based on the concrete strength damage threshold; The service life t2 of the nuclear power plant reactor pit concrete structure is calculated based on the service life prediction model based on the concrete damage depth threshold; The minimum value of the service life of the two nuclear power plant reactor pit concrete structures is selected as the service life t of the nuclear power plant reactor pit concrete structure under real service conditions, 。 5. A method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant, characterized in that, The service life prediction model is applied to the service life prediction method of the nuclear power plant reactor pit concrete structure according to any one of claims 1 to 4, wherein the method for obtaining the service life prediction model of the nuclear power plant reactor pit concrete structure comprises the following steps in sequence: Y1. Obtain the concrete material parameters and test conditions; Y2. Irradiation numerical simulation, Construct a micro-meso-macro multi-scale model to perform multi-scale numerical simulation of concrete irradiation damage; Y3. Irradiation numerical simulation calculation, Non-uniform temperature field and mechanical field irradiation numerical simulation calculation to obtain the temperature change curve of the concrete material after fast neutron irradiation; Y4. Irradiation numerical simulation test, Perform mechanical property and volume expansion rate simulation tests on the concrete material after fast neutron irradiation; Y5. Construct a concrete structure performance degradation and service life prediction model under irradiation-thermal-mechanical coupling based on irradiation numerical simulation, The simulation data obtained by the above irradiation numerical simulation test are fitted to build a relationship between irradiation time and aggregate volume expansion rate, a relationship equation between compressive strength of concrete structure and neutron fluence, and a relationship equation between damage depth of the concrete structure of the pile pit and neutron fluence; Y6. Construct a concrete structure performance degradation and service life prediction model under irradiation-heat-force coupling based on test data correction, The relationship between irradiation time and aggregate volume expansion rate, the relationship equation between compressive strength of the concrete structure of the pile pit and neutron fluence, and the relationship equation between damage depth of the concrete structure of the pile pit and neutron fluence are corrected by using test data.

6. A method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant according to claim 5, characterized in that, In step Y1, the concrete material parameters include concrete sample size, aggregate type, aggregate gradation, aggregate volume fraction, compressive strength of mortar and aggregate, tensile strength of mortar and aggregate, elastic modulus of mortar and aggregate, thermal expansion coefficient of mortar and aggregate, thermal conductivity of mortar and aggregate, and surface heat dissipation coefficient of mortar and aggregate; and the test conditions include fast neutron irradiation dose or fast neutron fluence and body heat flux.

7. The method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant according to claim 5, characterized in that, In step Y2, a micro-meso-macro multi-scale model is constructed for concrete irradiation damage multi-scale numerical simulation, and neutron, gamma irradiation and temperature are considered, and the three spatial scales of micro scale, meso scale and macro scale are correlated; the micro scale is to analyze the properties of each component of concrete from the physical mechanism, and the results are used as input parameters of the meso structure; the meso scale is to establish a numerical model of a small concrete sample, and the damage constitutive relationship of the small sample is obtained by analyzing the mechanical properties, and is used as an input parameter for macro mechanical property analysis; and the macro scale is to model and analyze the mechanical properties of the whole concrete of the pile pit to predict the change of the mechanical properties during the service life of the concrete of the pile pit.

8. A method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant according to claim 5 or 7, characterized in that, In step Y2, a micro-meso-macro multi-scale model is constructed for concrete irradiation damage multi-scale numerical simulation, wherein the micro scale model is established for the atomic composition of the concrete aggregate to obtain the relationship between neutron fluence and aggregate swelling rate, build the concrete aggregate constitutive model and parameters, and the properties of the concrete aggregate under irradiation are used as input parameters of the meso structure; the meso scale model is established for a small concrete sample to build a meso model of the random aggregate of the small concrete sample, and the damage constitutive relationship of the irradiated small sample is obtained by analyzing the mechanical properties through numerical simulation of the uniaxial compression test of the small sample, which is further compared and verified with typical concrete irradiation experiments, and is used as an input parameter for macro mechanical property analysis; and the macro scale model is established for the whole concrete of the pile pit, and the mechanical properties of the whole concrete of the pile pit are numerically analyzed by the neutron and gamma irradiation fluence distribution of the concrete of the pile pit to predict the change of the mechanical properties during the service life of the concrete of the pile pit.

9. The method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant of claim 5, characterized in that, In step Y3, the temperature change curve of the concrete material after fast neutron irradiation includes: a temperature distribution curve in the concrete, a temperature rise curve of the center and the surface of the concrete, and a temperature gradient curve in the concrete.

10. The method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant of claim 5, characterized in that, The mechanical property simulation test of the concrete material after the fast neutron irradiation in step Y4 is to apply uniaxial compression and tensile load to the concrete material under different irradiation times to obtain the limit compression continuous change curve, the tensile strength continuous change curve and the elastic modulus continuous change curve of the concrete material after different irradiation times.

11. The method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant of claim 5, characterized in that, The volume expansion rate simulation test of the concrete material after the fast neutron irradiation in step Y4 is to measure the volume expansion amount of the concrete material before and after irradiation and to calculate the volume expansion rate of the concrete before and after irradiation.

12. The method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant of claim 5, characterized in that, The relationship between the irradiation time and the aggregate volume expansion rate in step Y5 is: ， Wherein: K1, K2 are correlation coefficients, the value range of correlation coefficient K1 is 0≤K1≤1, the value range of correlation coefficient K2 is 1≤K2≤5, and is a dimensionless quantity; is the volume expansion rate of the aggregate, is a percentage, and is a dimensionless quantity; is the neutron fluence of E>0.1 MeV, in units of n / cm 2 .

13. A method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant according to claim 12, characterized in that, The relationship between the irradiation time and the aggregate volume expansion rate based on claim 12 in step Y5 converts the neutron fluence into the corresponding aggregate volume expansion rate, and the aggregate volume expansion rate reflects the influence of the neutron fluence on the compression strength of the concrete, and the relationship equation between the compression strength of the concrete structure and the neutron fluence is obtained: ， Wherein: m, n is the correlation coefficient, the value range of correlation coefficient m is -15≤m≤10, the value range of correlation coefficient n is 80≤n≤100; is the compressive strength of the concrete when not expanded, and the unit is MPa; is the compressive strength of the concrete after irradiation swelling, and the unit is MPa; is the neutron fluence of E>0.1 MeV, and the unit is 10 19 n / cm 2 .

14. The method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant of claim 5, characterized in that, The relationship equation between the damage depth of the pit concrete structure and the neutron fluence in step Y5 is: C ， Wherein: a, b, c are correlation coefficients, the value range of correlation coefficient a is 1≤a≤2, the value range of correlation coefficient b is 20≤b≤30, the value range of correlation coefficient c is 180≤c≤200; C is a constant, the value range of constant C is 420≤C≤470; d is the complete damage depth of the inner surface of the pit concrete, the unit is mm; For neutron flux of E>0.1 MeV, unit is 10 19 n / cm 2 .

15. The method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant of claim 12, wherein, In step Y6, the relationship equation between the irradiation time and the aggregate volume expansion rate is corrected by using the test data, including: The relationship between the irradiation time and the aggregate volume expansion rate is corrected by using the test data, and after the correction of the irradiation accelerated aging test and the high temperature accompanying test data, the value range of the correlation coefficient K1 is 0≤K1≤0.5; the value range of the correlation coefficient K2 is 1.5≤K2≤2.

16. The method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant of claim 13, wherein, In step Y6, the relationship equation between the compression strength of the pit concrete structure and the neutron fluence is corrected by using the test data, including: The relationship equation between the compression strength of the pit concrete structure and the neutron fluence is corrected by using the test data, and after the correction of the irradiation accelerated aging test and the high temperature accompanying test data, the value range of the correlation coefficient m is -10≤m≤0; the value range of the correlation coefficient n is 90≤n≤100.

17. A method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant according to claim 14, characterized in that, In step Y6, the relationship equation between the damage depth of the pit concrete structure and the neutron fluence is corrected by using the test data, including: The relationship equation between the damage depth of the pit concrete structure and the neutron fluence is corrected by using the test data, and after the correction of the irradiation accelerated aging test and the high temperature accompanying test data, the value range of the correlation coefficient a is 1≤a≤1.5; the value range of the correlation coefficient b is 22≤b≤27; the value range of the correlation coefficient c is 185≤c≤195.

18. A method of obtaining a service life prediction model of a containment concrete structure of a nuclear power plant according to any one of claims 15 to 17, characterized in that, The irradiation accelerated aging test and the high temperature accompanying test data include: the damage failure mode of the concrete under different irradiation times after the application of uniaxial compression and tensile load in the hot chamber environment, and the limit compression, tensile strength and elastic modulus continuous change curves of the concrete after different irradiation times are obtained; the volume expansion amount of the concrete aggregate after irradiation is tested in the hot chamber environment, and the volume expansion rate of the concrete before and after irradiation is calculated by combining the size of the concrete aggregate measured before irradiation.

19. An apparatus for predicting the service life of a containment concrete structure of a nuclear power plant, characterized by Including: The acquisition module is used to acquire the actual fast neutron irradiation dose accumulation rate of the pit concrete structure of the nuclear power plant under the real service working condition; The prediction module is configured to predict the service life of the nuclear power plant reactor pit concrete structure by using a service life prediction model based on a concrete compressive strength threshold and / or a service life prediction model based on a reactor pit concrete damage depth threshold. The service life prediction model based on the concrete compressive strength threshold comprises the following steps: The service life prediction model based on the concrete compressive strength threshold comprises the following steps: ， Wherein: is the service life based on the allowable threshold of the compressive strength of the concrete structure, and the unit is a; is the threshold of the compressive strength of the concrete, and the unit is MPa; is the compressive strength of the concrete when not expanded, and the unit is MPa; is the fast neutron irradiation dose accumulation rate, and the unit is n / (cm 2 .a); m and n are correlation coefficients, the value range of the correlation coefficient m is -15≤m≤10, and the value range of the correlation coefficient n is 80≤n≤100. The service life prediction model based on the concrete compressive strength threshold comprises the following steps: The service life prediction model based on the concrete compressive strength threshold comprises the following steps: ， wherein is the cumulative fast neutron fluence threshold for the concrete structure of the reactor pit: ， wherein: is the service life based on the concrete damage depth threshold, in a; is the fast neutron irradiation dose accumulation rate, in n / (cm 2 .a is the cumulative fast neutron irradiation dose threshold of the reactor pit concrete structure, in 10 19 n / cm 2 ; a, b, c are correlation coefficients; C is a constant; d t is the reactor pit concrete damage depth threshold, in mm, the value range of the correlation coefficient a is 1≤a≤2; the value range of the correlation coefficient b is 20≤b≤30; the value range of the correlation coefficient c is 180≤c≤200; the value range of the constant C is 420≤C≤470.

20. A computer program product comprising a computer program, characterized in that, The service life prediction model based on the concrete compressive strength threshold comprises the following steps:

21. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the method for predicting the service life of the nuclear power plant reactor pit concrete structure according to any one of claims 1 to 4, or the method for obtaining the service life prediction model of the nuclear power plant reactor pit concrete structure according to any one of claims 5 to 18. 22.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-21. The computer program is executed by the processor to implement the method for predicting the service life of the nuclear power plant reactor pit concrete structure according to any one of claims 1 to 4, or the method for obtaining the service life prediction model of the nuclear power plant reactor pit concrete structure according to any one of claims 5 to 18. The computer program is executed by the processor to implement the method for predicting the service life of the nuclear power plant reactor pit concrete structure according to any one of claims 1 to 4, or the method for obtaining the service life prediction model of the nuclear power plant reactor pit concrete structure according to any one of claims 5 to 18.

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