Simulation method and simulation equipment for creep failure of heat transfer tube of steam generator of passive nuclear power plant and readable storage medium

Abstract

The invention relates to a simulation method and simulation equipment for creep failure of a heat transfer tube of a steam generator of a passive nuclear power plant and a readable storage medium. The simulation method comprises the following steps: acquiring defect data of creep failure of the heat transfer tube; calculating the maximum defect frequency of the length defect of the heat transfer tube in the defect data and the defect frequency of the depth-to-thickness ratio to form a defect combination of the maximum defect frequency and the defect frequency, and calculating the defect frequency of the defect combination; calculating a stress amplification factor based on the geometric structure and defect combination of the heat transfer tube; selecting a high-pressure melting reactor accident sequence, and extracting time-varying state parameters of a heat transfer tube in the high-pressure melting reactor accident sequence; calculating key parameters of the creep failure model based on the defect frequency, the stress amplification factor and the state parameters; and randomly sampling defect combinations, counting probability failure results through a creep failure model, and calculating the most likely failure time. According to the method, the creep failure probability of the heat transfer tube can be calculated, and the research, development and design safety of a passive nuclear power plant system can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of reactor engineering simulation, and in particular to a simulation method, simulation equipment and readable storage medium for creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant. Background Art

[0002] As a clean, low-carbon, non-fossil energy, nuclear energy is an important option for the country to promote energy structure adjustment and achieve carbon peak and carbon neutrality goals. Compared with the second-generation nuclear power technology, passive nuclear power technology can achieve core cooling under the effect of water density difference and natural circulation of air, reduce the risk of sudden power outages or other natural disasters to the operation of nuclear power plants, and greatly improve the safety of nuclear power plants.

[0003] Safety is an important factor related to the sustainable development of passive nuclear power plants, and severe accident analysis is an important part of nuclear power plant safety analysis. In the severe accident analysis of nuclear power plants, the core of some high-pressure melt sequences is exposed with the loss of coolant, and then a natural circulation of superheated steam (which may contain hydrogen) is formed in the pressure vessel and the primary coolant system, so that the heat of the core can be transferred to the equipment in various areas of the primary natural circulation.

[0004] As the pressure boundary of the first circuit, the heat transfer tube of the steam generator is subjected to a large pressure difference between the first and second circuits. In the case of natural circulation in the first circuit, the heat transfer tube is subjected to continuous high temperature and pressure difference, and the material strain accumulates continuously, which may eventually cause induced rupture, that is, creep failure of the heat transfer tube.

[0005] At present, the research on creep failure in the field of nuclear power mainly focuses on the parameter and strain prediction method of a specific material and the creep failure determination method at the lower head of the reactor pressure vessel, while there are few simulation methods for the creep failure of the steam generator heat transfer tube. When the heat transfer tube creep failure occurs, if the steam generator is not isolated and the main steam isolation valve cannot be closed, it may cause the containment to bypass and cause early release of radioactive materials. Therefore, a simulation method is urgently needed to analyze the creep failure probability of the steam generator heat transfer tube of a passive power plant. Summary of the invention

[0006] In view of the above problems in the prior art, the present invention proposes a simulation method, simulation equipment and readable storage medium for the creep failure of heat transfer tubes of steam generators in passive nuclear power plants, which can calculate the probability of creep failure of heat transfer tubes and are conducive to improving the safety of research and development and design of passive nuclear power plant systems.

[0007] Specifically, the present invention proposes a simulation method for creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant, comprising the steps of:

[0008] Acquiring defect data of creep failure of the heat transfer tube;

[0009] Calculating the maximum defect frequency of the length defect of the heat transfer tube and the defect frequency of the depth-to-thickness ratio in the defect data, forming a defect combination of the maximum defect frequency of the length defect and the defect frequency of the depth-to-thickness ratio, and calculating the defect frequency of the defect combination;

[0010] Calculating a stress amplification factor based on the geometric structure and defect combination of the heat transfer tube;

[0011] Selecting a high-pressure melt reactor accident sequence, and extracting state parameters of the heat transfer tube in the high-pressure melt reactor accident sequence that change with time;

[0012] Calculating key parameters of a creep failure model based on defect frequency, stress amplification factor and state parameters of the defect combination;

[0013] The defect combinations are randomly sampled, probability failure results are statistically analyzed using the creep failure model, and the most likely failure time is calculated.

[0014] According to one embodiment of the present invention, after acquiring the defect data and before calculating the maximum defect frequency, abnormal data is eliminated, and the abnormal data includes defect data acquired under normal operating conditions of the nuclear power plant and during maintenance.

[0015] According to one embodiment of the present invention, the maximum defect frequency of the length defect of the heat transfer tube is calculated as follows:

[0016] P c_max (i) = P c (i)∏[1-P c (j)](j>i);

[0017] Among them, P c_max (i) is the defect length i is the frequency of occurrence of the maximum length defect, P c (i) is the frequency of occurrence of defect length i, and j is the number of defect lengths;

[0018] The calculation formula of the depth-to-thickness ratio defect frequency of the heat transfer tube is:

[0019] P a / h (α) = P a / h_integral (α+1)-P a / h_integral (α);

[0020] Among them, P a / h (α) is the frequency of occurrence of defect depth-thickness ratio α, P a / h_integral (α) is the cumulative occurrence frequency of defect depth-to-thickness ratio α;

[0021] The calculation formula for the defect frequency of the defect combination is:

[0022] P(k)=P c_max (i)·P a / h (α);

[0023] Where P(k) is the occurrence frequency of defect combination k.

[0024] According to one embodiment of the present invention, the stress amplification factor m p The calculation formula is:

[0025]

[0026] m=0.614+0.481λ+0.386e -1.25λ ;

[0027] ε=1+0.9(a / h) 2 (1-1 / m);

[0028]

[0029] Among them, λ, m, ε are intermediate variables; a is the depth of the defect crack; c is the length of the defect crack; h is the thickness of the heat transfer tube wall, R o is the outer diameter of the heat transfer tube; R i is the inner diameter of the heat transfer tube.

[0030] According to one embodiment of the present invention, the high-pressure melt reactor accident sequence is analyzed by an integrated severe accident analysis program, and the state parameters are extracted from the analysis results. The state parameters include the internal pressure, external pressure and temperature of the heat transfer tube, heat pipe section and surge tube.

[0031] According to one embodiment of the present invention, calculating the key parameters of the creep failure model comprises the steps of:

[0032] Calculating material stress on a pipeline, wherein the pipeline includes the heat transfer pipe, the heat pipe section and the surge pipe;

[0033] Based on the set confidence interval, the Larson-Miller parameter P of the pipeline material is calculated. lm ;

[0034] calculating a failure time of the pipeline;

[0035] Whether creep failure of the heat transfer tube occurs is determined based on the failure time of the pipeline.

[0036] According to one embodiment of the present invention, the calculation formula for the material stress of the heat pipe section and the surge pipe is:

[0037]

[0038] Among them, Pinner and P outer are the internal pressure and external pressure of the pipeline respectively; R o is the outer diameter of the heat transfer tube; R i is the inner diameter of the heat transfer tube;

[0039] The calculation formula of the material stress of the heat transfer tube is:

[0040]

[0041] Setting parameter P lm 95% confidence interval, calculate the Larson-Miller parameter P of the hot pipe section and surge tube material lm-sur- h l The calculation formula is:

[0042]

[0043] Calculate the Larson-Miller parameter P of the heat transfer tube material lm-SG The calculation formula is:

[0044]

[0045] The calculation formula for the failure time of the pipeline is:

[0046]

[0047] Where T is the temperature to which the material is subjected; C is a constant related to the material, determined by experiment; t r is the failure time; when the pipeline is a hot pipe section or a surge pipe, the Larson-Miller parameter P of the material lm P lm-sur- h l When the pipe is a heat transfer pipe, the Larson-Miller parameter P of the material lm P lm-SG ;

[0048] Define creep fraction per unit time If the unit creep fraction is integrated over time, the sum When it is greater than or equal to 1, the time is defined as the creep failure time of the pipeline;

[0049] Comparison of creep failure time T of hot pipe section hl , Surge tube creep failure time T sur and the creep failure time T of the steam generator heat transfer tube SG , if T SG ≤T hl And T SG ≤T Bur, the heat transfer tube will fail due to creep; if T SG >T hl or T SG >T sur , it is judged that the creep failure of the heat transfer tube does not occur.

[0050] According to an embodiment of the present invention, the defect combinations are randomly sampled, calculated through the creep failure model, and the total sampling probability is statistically analyzed and normalized. The calculation formula for the probability of creep failure of the heat transfer tube is:

[0051]

[0052] Among them, P SGTR (k) is the probability of heat transfer tube creep failure for defect combination k; P noSGTR (k) is the probability that the heat transfer tube will not fail due to creep for defect combination k; P SGTR is the total probability of creep failure of the heat transfer tube;

[0053] The most vulnerable failure time is counted and all creep failure times are superimposed on (t i ,t i+1 ) interval, the corresponding calculation formula is:

[0054] Get the creep failure probability in each time period within the total calculation time and obtain the most likely failure time;

[0055] Among them, P SGTR (i,i+1) is the i ,t i+1 ) is the total probability of heat transfer tube creep failure within the time interval.

[0056] The present invention also provides a simulation device for creep failure of heat transfer tubes of steam generators in passive nuclear power plants, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the aforementioned simulation methods when executing the computer program.

[0057] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of any of the above-mentioned simulation methods are implemented.

[0058] The present invention provides a simulation method, simulation equipment and readable storage medium for creep failure of heat transfer tubes of steam generators in passive nuclear power plants, including calculation of defect probability and stress amplification factor of defect combinations, simulation input and data processing of integrated severe accident analysis programs, calculation of key parameters of creep failure models, and further calculation of creep failure probability and most likely failure time, thereby forming a set of creep failure simulation methods suitable for heat transfer tubes in passive nuclear power plants, which is beneficial to improving the safety of research and development and design of passive nuclear power plant systems.

[0059] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings are included to provide further explanation of the present invention, and are incorporated into and constitute a part of this application. The accompanying drawings illustrate embodiments of the present invention and together with the description serve to explain the principle of the present invention.

[0061] In the attached figure:

[0062] Figure 1 A flowchart of a method for simulating creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant according to an embodiment of the present invention is shown.

[0063] Figure 2 A schematic diagram showing the variation of defect frequency of a heat transfer tube with defect length according to an embodiment of the present invention is shown.

[0064] Figure 3 A schematic diagram showing the variation of defect frequency of a heat transfer tube with defect depth-to-thickness ratio according to an embodiment of the present invention is shown.

[0065] Figure 4 A schematic diagram showing data processing of an integrated severe accident analysis program according to an embodiment of the present invention is shown.

[0066] Figure 5 A schematic diagram showing a calculation process of key parameters of creep failure according to an embodiment of the present invention is shown.

[0067] Figure 6 A schematic diagram showing a method for determining creep failure of a heat transfer tube according to an embodiment of the present invention is shown.

[0068] Figure 7 The system block diagram of a simulation device for creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant according to an embodiment of the present invention. DETAILED DESCRIPTION

[0069] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0070] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0071] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0072] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0073] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0074] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0075] Figure 1 A flowchart of a method for simulating creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant according to an embodiment of the present invention is shown. As shown in the figure, a method for simulating creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant comprises the following steps:

[0076] S1, obtain the defect data of creep failure of the heat transfer tube. The defect data mainly includes the geometric structure (dimensional data), material performance data, operating environment data and time-related data of the heat transfer tube.

[0077] S2, calculate the maximum defect frequency of the length defect of the heat transfer tube in the defect data, and the defect frequency of the depth-to-thickness ratio, form a defect combination of the two, and calculate the defect frequency of the defect combination. When the heat transfer tube creep failure occurs, assuming that at the same defect depth, the heat transfer tube always breaks at the longest defect, so it is necessary to determine the frequency distribution of the maximum defect length. At the same time, it is necessary to calculate the defect frequency of the depth-to-thickness ratio. Combine the length defect frequency with the depth-to-thickness ratio defect frequency, and on this basis, further calculate the defect frequency of this defect combination. Through the precise calculation and analysis of these data, we can better understand the defect situation of the heat transfer tube and provide a basis for the subsequent judgment of the creep failure of the heat transfer tube.

[0078] S3, calculate the stress amplification factor based on the geometric structure and defect combination of the heat transfer tube. Since the heat transfer tube may be damaged by wear during the manufacturing and operation process, and the diameter of the heat transfer tube is relatively small, the impact of defects is large, so it is necessary to analyze the impact of defects. The calculation of the stress amplification factor requires comprehensive consideration of the stress of the heat transfer tube under different working conditions, as well as the impact of the defect combination on the stress distribution of the heat transfer tube, so as to better understand the stress state of the heat transfer tube when defects exist.

[0079] S4, select the high-pressure melt reactor accident sequence and extract the state parameters of the heat transfer tube in the high-pressure melt reactor accident sequence that change with time. The high-pressure melt reactor sequence is a specific process or phenomenon sequence in a severe accident of a nuclear reactor, which is of great significance for understanding and assessing the consequences and risks of nuclear accidents. Through in-depth research on the high-pressure melt reactor sequence, we can better understand the behavioral characteristics of the heat transfer tube under severe accidents.

[0080] S5, based on the defect frequency, stress amplification factor and state parameters of the defect combination, calculate the key parameters of the creep failure model. Specifically, the defect frequency reflects the possibility of defects in the heat transfer tube, and the stress amplification factor reflects the degree of influence of the defect on the stress distribution. In addition, state parameters, including operating state factors such as temperature and pressure, must also be considered. By combining these factors, the key parameters of the creep failure model can be accurately determined. These key parameters are crucial for the subsequent evaluation of the creep failure risk of the heat transfer tube.

[0081] S6, randomly sample defect combinations, statistically analyze the probability failure results through the creep failure model, and calculate the most likely failure time. This step helps to improve the safety and reliability of heat transfer tubes and ensure the stable operation of related facilities such as nuclear power plants.

[0082] In some examples, after obtaining the defect data of creep failure of the heat transfer tube and before calculating the maximum defect frequency and the defect frequency of the depth-to-thickness ratio, the abnormal data in the defect data are eliminated. The abnormal data includes defect data obtained under normal operating conditions of the nuclear power plant and during maintenance. Because the data obtained during normal operation and maintenance may be interfered by various factors, it cannot truly reflect the defect situation caused by creep failure of the heat transfer tube under specific conditions. By eliminating these abnormal data, the reliability of subsequent analysis and calculation can be improved.

[0083] In some examples, the defect length occurrence frequency of the entire passive nuclear power plant follows the Gamma distribution, and the maximum defect frequency of the length defect of the heat transfer tube is calculated as follows:

[0084] P c_max (i) = P c (i)∏[1-P c (j)](j>i);

[0085] Among them, P c_max (i) is the defect length i is the frequency of occurrence of the maximum length defect, P c (i) is the frequency of occurrence of defect length i, and j is the number of defect lengths. Figure 2 A schematic diagram showing the variation of the defect frequency of a heat transfer tube with the defect length according to an embodiment of the present invention is shown. As shown in the figure, the horizontal axis represents the maximum defect length, and the vertical axis represents the occurrence frequency of the defect length.

[0086] Assuming that there is no correlation between the length and depth of the heat transfer tube defect, and the cumulative share of the depth-to-thickness ratio also obeys the Gamma distribution, the calculation formula for the depth-to-thickness ratio defect frequency of the heat transfer tube is:

[0087] P a / h (α) = P a / h_integral (α+1)-P a / h_integral (α);

[0088] Among them, P a / h (α) is the frequency of occurrence of defect depth-thickness ratio α, P a / h_integral (α) is the cumulative occurrence frequency of defect depth-to-thickness ratio α. Figure 3 A schematic diagram showing the variation of the defect frequency of a heat transfer tube according to an embodiment of the present invention with the defect depth-to-thickness ratio is shown. As shown in the figure, the horizontal axis represents the defect depth-to-thickness ratio, and the vertical axis represents the occurrence frequency of the defect depth-to-thickness ratio.

[0089] The calculation formula for the defect frequency of all heat transfer tube defect combinations is:

[0090] P(k)=P c_max (i)·P a / h (α);

[0091] Where P(k) is the occurrence frequency of defect combination k.

[0092] In some examples, setting reasonable confidence intervals, the stress amplification factor m p The calculation formula is:

[0093]

[0094] m=0.614+0.481λ+0.386e -1.25λ ;

[0095] ε=1+0.9(a / h) 2 (1-1 / m);

[0096]

[0097] Among them, λ, m, ε are intermediate variables; a is the depth of the defect crack, unit is mm; c is the length of the defect crack, unit is mm; h is the thickness of the heat transfer tube wall, unit is mm, R o is the outer diameter of the heat transfer tube, in mm; R i is the inner diameter of the heat transfer tube, in mm.

[0098] Preferably, a 95% confidence interval is given to calculate the stress amplification factor m p .

[0099] In some examples, it also includes analyzing the high-pressure melt reactor accident sequence through an integrated severe accident analysis program, and extracting state parameters from the analysis results, the state parameters including the time-varying internal and external pressures and temperatures of the heat transfer tubes, heat pipe sections and surge tubes. Since the reactor primary loop system is in a continuous high-pressure state in a high-pressure melt reactor accident, the steam generator heat transfer tubes are more susceptible to creep failure under the action of long-term large pressure and temperature differences, so the high-pressure melt reactor accident sequence (such as loss of main feed water, etc.) is selected as a typical operating condition.

[0100] In some examples, since the time intervals of parameters directly output by the integrated severe accident analysis program are inconsistent, the data needs to be processed to facilitate subsequent processing and calculation. Figure 4 FIG. 1 is a schematic diagram showing data processing of an integrated severe accident analysis program according to an embodiment of the present invention. As shown in the figure, if t j In the results of the integrated severe accident analysis program (t i ,t i+1 ) time interval, t i The corresponding parameters (P inner (i),P outer (i),T(i)) is assigned to t j Corresponding parameter, t j Accumulate equal time intervals Δt for cyclic calculation and judge t j Is it greater than the total time T total , until a sequence of results with equal time intervals is obtained (t j ,P inner (j),P outer (j),T(j)). Among them, P inner (i) is t i The pressure inside the heat transfer tube at the moment, P outer (i) is t i The external pressure of the heat transfer tube at time t i The temperature of the heat transfer tube at all times.

[0101] Figure 5 A schematic diagram of a creep failure key parameter calculation process according to an embodiment of the present invention is shown. As shown in the figure, calculating the key parameters of the creep failure model includes the following steps:

[0102] S51, calculate the material stress of the pipeline, which includes heat transfer pipes, heat pipe sections and surge pipes. Because in the case of natural circulation in one loop, the heat pipe sections and surge pipes of the pipeline will also be affected by high-temperature steam and induce rupture, and there is a mutually exclusive effect between the rupture of the heat pipe sections, surge pipes and heat transfer pipes (that is, after an induced rupture occurs at any position, it will cause the reactor coolant system to depressurize and the stress at other positions to decrease, so that no induced rupture will occur). Therefore, it is necessary to perform creep model calculations on the heat pipe sections, surge pipes and steam generator heat transfer pipes respectively.

[0103] S52, calculate the Larson-Miller parameter P of the pipeline material based on the set confidence interval lm ;

[0104] S53, calculating the failure time of the pipeline;

[0105] S54, judging whether creep failure of the heat transfer tube occurs according to the failure time of the tube.

[0106] In some examples, in step S51, the calculation formula for the material stress of the hot pipe section and the surge pipe is:

[0107]

[0108] Among them, P inner and P outer are the internal pressure and external pressure of the pipeline, respectively, in ksi; R o is the outer diameter of the heat transfer tube, in mm; R i is the inner diameter of the heat transfer tube, in mm;

[0109] Heat transfer tubes need to consider the stress amplification factor m p , the calculation formula of the material stress of the heat transfer tube is:

[0110]

[0111] In step S52, set the parameter P lm 95% confidence interval for calculating the Larson-Miller parameter P for the hot section and surge tube materials lm-sur- h l The calculation formula is:

[0112]

[0113] Calculate the Larson-Miller parameter P of the heat transfer tube material lm-SG The calculation formula is:

[0114]

[0115] In step S53, the calculation formula of the pipeline failure time is:

[0116]

[0117] Where T is the temperature to which the material is subjected, in K; C is a material-related constant, determined by experiment; t r is the failure time, in h; when the pipeline is a hot pipe section or a surge pipe, the Larson-Miller parameter P of the material lm Plm-sur- h l ; When the pipe is a heat transfer pipe, the Larson-Miller parameter P of the material lm P lm-SG ;

[0118] In step S54, reference Figure 5 In fact, after a serious accident, all the temperature and pressure in the pipeline are constantly changing. The creep fraction per unit time is defined as Assuming that the temperature and pressure of the pipeline are constant per unit time, the unit creep fraction is integrated over time, t j Accumulate equal time intervals Δt for cyclic calculation and judge t j Is it greater than the total time T total , if the sum When it is greater than or equal to 1, the time is defined as the creep failure time of the pipeline; if the sum If it is less than 1, it is judged that no creep failure occurs.

[0119] Figure 6 The schematic diagram of a heat transfer tube creep failure determination method according to an embodiment of the present invention is shown. As shown in the figure, the creep failure time T of the heat transfer tube segment is calculated. hl , Surge tube creep failure time T sur and the creep failure time T of the steam generator heat transfer tube SG , and compare the three. If T SG ≤T hl And T SG ≤T sur , it is judged that the heat transfer tube has failed due to creep; if T SG >T hl or T SG >T sur , it is judged that the creep failure of the heat transfer tube does not occur.

[0120] In some examples, the random sampling defect combination is calculated through the creep failure model, the total sampling probability is statistically analyzed and normalized, and the calculation formula for the probability of creep failure of the heat transfer tube is:

[0121]

[0122] Among them, P SGTR (k) is the probability of heat transfer tube creep failure for defect combination k; P noSGTR (k) is the probability that the heat transfer tube will not fail due to creep for defect combination k; P SGTR is the total probability of creep failure of the heat transfer tube;

[0123] The most vulnerable failure time is counted and all creep failure times are superimposed on (t i ,t i+1) interval, the corresponding calculation formula is:

[0124]

[0125] Get the creep failure probability in each time period within the total calculation time and obtain the most likely failure time;

[0126] Among them, P SGTR (i,i+1) is the i ,t i+1 ) is the total probability of heat transfer tube creep failure within the time interval.

[0127] Figure 7 This is a system block diagram of a simulation device for creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant according to an embodiment of the present invention. Figure 7 As shown, the simulation device 700 may include an internal communication bus 701, a processor 702, a read-only memory (ROM) 703, a random access memory (RAM) 704, and a communication port 705. When applied on a personal computer, the simulation device 700 may also include a hard disk 706. The internal communication bus 701 can realize data communication between the components of the simulation device 700. The processor 702 can make judgments and issue prompts. In some embodiments, the processor 702 can be composed of one or more processors. The communication port 705 can realize data communication between the simulation device 700 and the outside. In some embodiments, the simulation device 700 can send and receive information and data from the network through the communication port 705. The simulation device 700 may also include a program storage unit and a data storage unit in different forms, such as a hard disk 706, a read-only memory (ROM) 703 and a random access memory (RAM) 704, which can store various data files used for computer processing and / or communication, and possible program instructions executed by the processor 702. The processor 702 executes these instructions to implement the main part of the method. The processing result of the processor 702 is transmitted to the user equipment through the communication port 705 and displayed on the user interface.

[0128] The above-mentioned simulation method can be implemented as a computer program, stored in the hard disk 706, and loaded into the processor 702 for execution to implement the simulation method of the present application.

[0129] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the aforementioned methods for simulating creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant.

[0130] Among them, the specific implementation methods and technical effects of the simulation equipment and computer-readable storage medium for the creep failure of the steam generator heat transfer tube of a passive nuclear power plant can be referred to the embodiment of the simulation method for the creep failure of the steam generator heat transfer tube of a passive nuclear power plant provided by the present invention, which will not be repeated here.

[0131] The present invention provides a simulation method for creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant, a simulation device for creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant, and a readable storage medium, which have the following beneficial effects:

[0132] (1) It covers the calculation of combined defect frequency and stress amplification factor of heat transfer tubes, simulation input and data processing of integrated severe accident analysis program, calculation of key parameters of creep failure model, statistics of creep failure probability and most likely failure time, forming a set of creep failure simulation methods suitable for heat transfer tubes in passive nuclear power plants, effectively supporting the research and development and design of passive nuclear power plant systems;

[0133] (2) The proposed calculation of the combined defect frequency and stress amplification factor of the heat transfer tube is performed. The defect frequency under different combinations is obtained by randomly combining the maximum defect length and the depth-to-thickness ratio. The wear of the heat transfer tube during manufacturing and transportation is considered, and the stress amplification factor is used to more realistically simulate the impact of defects.

[0134] (3) A method for calculating the key parameters of the creep failure model is proposed. First, the material stress is calculated, and then the Larson-Miller parameters are obtained. Considering the pressure difference and temperature changes of the pipeline, the creep failure share per unit time is determined, and it is integrated over the calculation time to simulate whether creep failure occurs.

[0135] (4) A method for calculating the probability of creep failure and the most likely failure time of heat transfer tubes is proposed. First, the creep failure times of the heat pipe section, the surge tube, and the steam generator heat transfer tube are compared to determine whether creep failure of the heat transfer tube occurs. Second, the sampling probability is normalized to obtain the creep failure probability after considering the defect frequency of the heat transfer tube. Finally, the total calculation time is divided into intervals, and the failure probability in each interval is counted to obtain the most likely failure time of the heat transfer tube.

[0136] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0137] The various illustrative logic modules and circuits described in conjunction with the embodiments disclosed herein may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of emulated devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in cooperation with a DSP core, or any other such configuration.

[0138] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in a user terminal as discrete components.

[0139] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented as a computer program product in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Storage media may be any available medium that can be accessed by a computer. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, a server, or other remote source using a coaxial cable, a fiber optic cable, a twisted pair, a digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of the medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein disk often reproduces data magnetically, while disc reproduces data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0140] It will be apparent to those skilled in the art that various modifications and variations may be made to the above exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention covers modifications and variations of the present invention that fall within the scope of the appended claims and their equivalent technical solutions.

Claims

1. A simulation method for creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant, comprising the steps of: Acquiring defect data of creep failure of the heat transfer tube; Calculating the maximum defect frequency of the length defect of the heat transfer tube and the defect frequency of the depth-to-thickness ratio in the defect data, forming a defect combination of the maximum defect frequency of the length defect and the defect frequency of the depth-to-thickness ratio, and calculating the defect frequency of the defect combination; Calculating a stress amplification factor based on the geometric structure and defect combination of the heat transfer tube; Selecting a high-pressure melt reactor accident sequence, and extracting state parameters of the heat transfer tube in the high-pressure melt reactor accident sequence that change with time; Calculating key parameters of a creep failure model based on defect frequency, stress amplification factor and state parameters of the defect combination; The defect combinations are randomly sampled, probability failure results are statistically analyzed using the creep failure model, and the most likely failure time is calculated.

2. The simulation method according to claim 1, characterized in that: It also includes eliminating abnormal data after obtaining the defect data and before calculating the maximum defect frequency, wherein the abnormal data includes defect data obtained under normal operating conditions of the nuclear power plant and during maintenance.

3. The simulation method according to claim 1, characterized in that: The calculation formula for the maximum defect frequency of the length defect of the heat transfer tube is: P c_max (i)=P c (i)∏[1-P c (j)](j>i); Among them, P c_max (i) is the defect length i is the frequency of occurrence of the maximum length defect, P c (i) is the frequency of occurrence of defect length i, and j is the number of defect lengths; The calculation formula of the depth-to-thickness ratio defect frequency of the heat transfer tube is: P a / h (a)=P a / h_integral (α+1)-P a / h_integral (a); Among them, P a / h (α) is the frequency of occurrence of defect depth-thickness ratio α, P a / h_integral (α) is the cumulative occurrence frequency of defect depth-to-thickness ratio α; The calculation formula for the defect frequency of the defect combination is: P(k)DP c_max (i)·P a / h (α) Where P(k) is the occurrence frequency of defect combination k.

4. The simulation method according to claim 3, characterized in that: The stress amplification factor m p The calculation formula is: m=0.614+0.481λ+0.386e -1.25λ ; ε=1+0.9(a / h) 2 (1-1 / m); Among them, λ, m, ε are intermediate variables; a is the depth of the defect crack; c is the length of the defect crack; h is the thickness of the heat transfer tube wall, R o is the outer diameter of the heat transfer tube; R i is the inner diameter of the heat transfer tube.

5. The simulation method according to claim 4, characterized in that: It also includes analyzing the high-pressure melt reactor accident sequence through an integrated severe accident analysis program, and extracting the state parameters from the analysis results, wherein the state parameters include the internal pressure, external pressure and temperature of the heat transfer tube, heat pipe section and surge tube.

6. The simulation method according to claim 1, characterized in that: Calculating the key parameters of the creep failure model includes the steps of: Calculating material stress on a pipeline, wherein the pipeline includes the heat transfer pipe, the heat pipe section and the surge pipe; Based on the set confidence interval, the Larson-Miller parameter P of the pipeline material is calculated. lm ; calculating a failure time of the pipeline; Whether creep failure of the heat transfer tube occurs is determined based on the failure time of the pipeline.

7. The simulation method according to claim 6, characterized in that: The calculation formula for the material stress of the heat pipe section and the surge pipe is: Among them, P inner and P outer are the internal pressure and external pressure of the pipeline respectively; R o is the outer diameter of the heat transfer tube; R i is the inner diameter of the heat transfer tube; The calculation formula of the material stress of the heat transfer tube is: Setting parameter P lm 95% confidence interval, calculate the Larson-Miller parameter P of the hot pipe section and surge tube material lm-sur- h l The calculation formula is: Calculate the Larson-Miller parameter P of the heat transfer tube material lm-SG The calculation formula is: The calculation formula for the failure time of the pipeline is: Where T is the temperature to which the material is subjected; C is a constant related to the material, determined by experiment; t r is the failure time; when the pipeline is a hot pipe section or a surge pipe, the Larson-Miller parameter P of the material lm P lm-sur- h l When the pipe is a heat transfer pipe, the Larson-Miller parameter P of the material lm P lm-SG ; Define creep fraction per unit time If the unit creep fraction is integrated over time, the sum When it is greater than or equal to 1, the time is defined as the creep failure time of the pipeline; Comparison of creep failure time T of hot pipe section hl , Surge tube creep failure time T sur and creep failure time T of steam generator heat transfer tube SG , if T SG ≤T hl And T SG ≤T sur , the heat transfer tube will fail due to creep; if T SG >T hl or T SG >T sur , it is judged that the creep failure of the heat transfer tube does not occur.

8. The simulation method according to claim 1, characterized in that: The method also includes randomly sampling the defect combination, calculating through the creep failure model, statistically analyzing the total probability of sampling and normalizing it. The calculation formula for the probability of creep failure of the heat transfer tube is: Among them, P SGTR (k) is the probability of heat transfer tube creep failure for defect combination k; P noSGTR (k) is the probability that the heat transfer tube will not fail due to creep for defect combination k; P SGTR is the total probability of creep failure of the heat transfer tube; The most vulnerable failure time is counted and all creep failure times are superimposed on (t i ,t i+1 ) interval, the corresponding calculation formula is: Get the creep failure probability in each time period within the total calculation time and obtain the most likely failure time; Among them, P SGTR (i,i+1) is the i ,t i+1 ) is the total probability of heat transfer tube creep failure within the time interval.

9. A simulation device for creep failure of a heat transfer tube of a steam generator in a passive nuclear power plant, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the simulation method according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the simulation method according to any one of claims 1 to 8 are implemented.

Images