Method and system for determining control strategy of nuclear power plant under typhoon condition

Abstract

The application discloses a method and system for determining a unit control strategy of a nuclear power plant under a typhoon condition, and the method comprises the following steps: analyzing different operation modes of a nuclear power plant unit; analyzing the influence of a typhoon on the nuclear power plant; determining potential post-withdrawal operation modes and corresponding accident conditions and available safety functions under the influence of the typhoon according to the analysis, taking a power operation condition as an initial condition; performing a deterministic safety analysis on accidents caused by the typhoon according to the accident conditions and the available safety functions under the influence of the typhoon of different post-withdrawal operation modes, so as to evaluate the applicability of different post-withdrawal operation modes under the typhoon condition; performing a probabilistic safety analysis on the accidents caused by the typhoon according to the accident conditions and the available safety functions under the influence of the typhoon of different post-withdrawal operation modes, so as to evaluate the priority of different post-withdrawal operation modes under the typhoon condition; and comprehensively determining the deterministic and probabilistic safety analysis results, so as to determine a typhoon unit control strategy of the power operation initial condition.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant unit operation control technology under typhoon conditions, and in particular to a method and system for determining unit control strategies under typhoon conditions in nuclear power plants. Background Technology

[0002] Located in southeastern Asia, on the western coast of the Pacific Ocean, my country boasts a coastline of over 18,000 kilometers. This unique geographical location makes my country susceptible to frequent and severe typhoon disasters. Along the western Pacific coast, my country is the country most frequently hit by typhoons, with an average of seven typhoons making landfall annually. Coastal provinces from south to north are all potentially affected by typhoons. Most of China's nuclear power plants are located along the southeastern coast, an area severely impacted by typhoons. Therefore, effective typhoon prevention and mitigation measures are crucial for ensuring the safe and stable operation of these units.

[0003] Operational experience shows that super typhoons can easily impact nuclear power plant transmission lines, cooling water pump rooms, and other systems, potentially leading to power outages and heat sink failures. In the face of super typhoon threats, establishing a comprehensive and effective defense-in-depth system is essential, and unit operation control strategies are a crucial component. Currently, in responding to super typhoons, domestic nuclear power plants primarily rely on grid decisions for measures such as power reduction and shutdown, prioritizing grid stability. Numerous nuclear power plants lack mature operational control procedures for proactively reducing power or shutting down units to ensure nuclear safety. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and system for determining the control strategy of a nuclear power plant unit under typhoon conditions, addressing at least one deficiency in the existing technology.

[0005] The technical solution adopted by this invention to solve its technical problem is: to construct a method for determining the unit control strategy of a nuclear power plant under typhoon conditions, including the following steps:

[0006] S1: Analyze different operating modes of nuclear power plant units;

[0007] S2: Analyze the impact of typhoons on nuclear power plants;

[0008] S3: Based on the analysis in steps S1 and S2, taking the power operation condition as the initial condition, determine the potential retreat operation mode and its corresponding accident conditions and available safety functions under the influence of the typhoon.

[0009] S4: Based on the accident conditions and available safety functions of different withdrawal operation modes under the influence of typhoons, conduct deterministic safety analysis on accidents caused by typhoons to assess the applicability of different withdrawal operation modes under typhoon conditions.

[0010] S5: Based on the accident conditions and available safety functions of different retreat operation modes under the influence of typhoons, conduct probabilistic safety analysis on accidents caused by typhoons to assess the priority of different retreat operation modes under typhoon conditions.

[0011] S6: Based on the combined deterministic and probabilistic safety analysis results, determine the typhoon unit control strategy for the initial power operation condition.

[0012] Preferably, in the method for determining the unit control strategy under typhoon conditions in a nuclear power plant according to the present invention, the method further includes:

[0013] S0: Determine the typhoon characteristics of the plant site to be analyzed;

[0014] Accordingly, step S2 includes: analyzing the impact of the typhoon on the nuclear power plant based on the typhoon characteristic information.

[0015] Preferably, in the method for determining the unit control strategy of a nuclear power plant under typhoon conditions described in this invention, step S1 includes: sorting out all possible operating modes of the nuclear power plant, analyzing the standard operating conditions corresponding to different operating modes, and the safety functions available under each operating condition.

[0016] Preferably, in the method for determining the unit control strategy under typhoon conditions in a nuclear power plant according to the present invention, step S2 includes:

[0017] S21: Based on the impact of the typhoon on the structures, systems, and components of the nuclear power plant, analyze the possible initiation events that the typhoon may cause;

[0018] S22: Analyze the safety functions required by the nuclear power plant to mitigate the initiating event;

[0019] S23: Analyze the impact of the typhoon on the safety functions required for the initiating event.

[0020] Preferably, in the method for determining the unit control strategy under typhoon conditions in a nuclear power plant according to the present invention, step S3 includes:

[0021] S31: Based on the analysis in step S1, taking the power operation condition as the initial condition, determine the potential retreat operation mode;

[0022] S32: Based on the analysis in step S2, determine the initiating events and available safety functions corresponding to the potential retreat operation mode under the influence of the typhoon.

[0023] Preferably, in the method for determining the unit control strategy under typhoon conditions in a nuclear power plant according to the present invention, step S4 includes:

[0024] Based on the accident conditions and available safety functions of different withdrawal operation modes under the influence of typhoons, deterministic calculations are carried out to analyze the mitigation of accidents and to assess the applicability of different withdrawal operation modes under typhoon conditions.

[0025] Preferably, in the method for determining the unit control strategy under typhoon conditions in a nuclear power plant according to the present invention, step S5 includes:

[0026] S51: Based on the first-level PSA model of internal events under low power and shutdown conditions of nuclear power plants, determine the correspondence between the operating status of each nuclear power plant and the potential withdrawal operating mode in the PSA model;

[0027] S52: Based on the initial event analyzed in step S2, select the corresponding event tree in the PSA model, and modify the relevant function headers and the corresponding fault trees in the event tree according to the impact of the typhoon on the safety functions.

[0028] S53: For the selected shutdown PSA event tree, calculate the conditional core damage probability corresponding to the potential withdrawal operation mode to evaluate the priority of different withdrawal operation modes under typhoon conditions.

[0029] Preferably, in the method for determining the unit control strategy under typhoon conditions in a nuclear power plant according to the present invention, the method further includes:

[0030] S7: Based on the typhoon generator control strategy under the initial power operation condition, determine the typhoon generator control strategy for other initial operating conditions.

[0031] This invention also constructs a system for determining the control strategy of a nuclear power plant unit under typhoon conditions, comprising:

[0032] The unit operation mode analysis module is used to analyze different operation modes of nuclear power plant units;

[0033] The typhoon impact analysis module is used to analyze the impact of typhoons on nuclear power plants.

[0034] The accident condition and available safety function determination module is used to determine potential retreat operation modes and their corresponding accident conditions and available safety functions under the influence of typhoons, based on the analysis of the unit operation mode analysis module and the typhoon impact analysis module, with the power operation condition as the initial condition.

[0035] The deterministic analysis module is used to perform deterministic safety analysis on typhoon-induced accidents based on the accident conditions and available safety functions of different retreat operation modes under the influence of typhoons, in order to evaluate the applicability of different retreat operation modes under typhoon conditions.

[0036] The probability analysis module is used to perform probabilistic safety analysis on typhoon-induced accidents based on the accident conditions and available safety functions of different retreat operation modes under the influence of typhoons, so as to evaluate the priority of different retreat operation modes under typhoon conditions.

[0037] The strategy determination module is used to integrate the results of deterministic and probabilistic security analysis to determine the control strategy for the typhoon unit under the initial power operation conditions.

[0038] Preferably, in the nuclear power plant unit control strategy determination system under typhoon conditions described in this invention, the system further includes:

[0039] The typhoon characteristic determination module is used to determine the typhoon characteristic information of the site to be analyzed.

[0040] The other strategy determination module is used to determine the typhoon unit control strategy for other initial operating conditions based on the typhoon unit control strategy under the initial power operation condition.

[0041] By implementing this invention, the following beneficial effects are achieved:

[0042] This invention establishes an operational control strategy that conforms to the typhoon impact characteristics of specific plant sites and the actual operation of the units, solving the problem of insufficient unit control actions in domestic nuclear power plants during typhoons. By taking control actions in advance based on typhoon impact conditions, the impact of typhoons on nuclear safety can be effectively reduced, the typhoon-in-depth defense system of nuclear power plants can be improved, and the ability of units to cope with typhoon disasters can be enhanced.

[0043] The system establishes unit control actions for nuclear power plants under typhoon conditions, providing more specific, detailed, and operable unit control methods for nuclear power units. This avoids the problem of insufficient attention to nuclear safety caused by relying solely on grid instructions, as well as the operational pressure and uncertainty risks brought about by relying solely on temporary decisions made by on-duty personnel.

[0044] This method can be extended to the study of unit control strategies under other external disasters affecting nuclear power plants, such as intake blockage events caused by marine organisms. It provides support for establishing systematic and comprehensive unit control actions against external disasters at nuclear power plants, thereby enhancing the ability of nuclear power units to cope with such events. Attached Figure Description

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0046] Figure 1 This is a flowchart illustrating the method for determining the unit control strategy in a nuclear power plant under typhoon conditions according to the present invention. Figure 1 ;

[0047] Figure 2 This is a flowchart illustrating the method for determining the unit control strategy in a nuclear power plant under typhoon conditions according to the present invention. Figure 2 ;

[0048] Figure 3 This is a block diagram of the nuclear power plant unit control strategy determination system under typhoon conditions, as described in this invention. Detailed Implementation

[0049] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0050] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0051] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0052] like Figure 1 As shown, this invention discloses a method for determining the control strategy of a nuclear power plant unit under typhoon conditions, comprising the following steps:

[0053] Step S1: Analyze different operating modes of nuclear power plant units;

[0054] Step S2: Analyze the impact of the typhoon on the nuclear power plant;

[0055] Step S3: Based on the analysis in steps S1 and S2, taking the power operation condition as the initial condition, determine the potential retreat operation mode and its corresponding accident conditions and available safety functions under the influence of the typhoon.

[0056] Step S4: Based on the accident conditions and available safety functions of different withdrawal operation modes under the influence of typhoons, conduct deterministic safety analysis on accidents caused by typhoons to assess the applicability of different withdrawal operation modes under typhoon conditions.

[0057] Step S5: Based on the accident conditions and available safety functions of different retreat operation modes under the influence of typhoons, conduct probabilistic safety analysis on accidents caused by typhoons to assess the priority of different retreat operation modes under typhoon conditions.

[0058] Step S6: Based on the combined deterministic and probabilistic safety analysis results, determine the typhoon generator control strategy for the initial power operation condition.

[0059] In some embodiments, step S0 is included before step S1: determining typhoon characteristic information of the site to be analyzed. Accordingly, step S2 includes: analyzing the impact of the typhoon on the nuclear power plant based on the typhoon characteristic information.

[0060] Specifically, different countries and regions have different classifications and definitions of typhoons, resulting in significant differences in typhoon wind speeds, air pressures, and warning signals. Developing unit control strategies during typhoons first requires clarifying the typhoon characteristics of the nuclear power plant site to be analyzed. This involves determining the correspondence between different typhoon parameters and actual wind speeds at the site, so as to obtain the input conditions for unit control actions based on meteorological forecasts and on-site monitoring results. The typhoon characteristics include the definitions of typhoon, severe typhoon, and super typhoon, as well as the definitions of different typhoon levels.

[0061] The typhoon classification for nuclear power plants in my country is shown in Table 1 below:

[0062] Table 1

[0063] Typhoon level Typhoon range Wind speed (m / s) 12 typhoon 32.7-36.9 13 typhoon 37.0-41.4 14 strong typhoon 41.5-46.1 15 strong typhoon 46.2-50.9 16 Super Typhoon 51.0-56.0 17 Super Typhoon 56.1-61.2 Level 17 and above Super Typhoon ≥61.3

[0064] In this embodiment, step S1: Analyze different operating modes of nuclear power plant units, which further includes: sorting out all possible operating modes of nuclear power plants, analyzing the standard operating conditions corresponding to different operating modes, and the safety functions available under each operating condition.

[0065] Specifically, based on different values ​​of parameters such as nuclear power, primary coolant charge, primary coolant pressure, primary coolant average temperature, and primary coolant boron concentration, nuclear power units will have different standard operating conditions during the design phase. In typhoon conditions, the unit's early power reduction and shutdown operations need to be carried out based on these standard operating conditions. This step outlines all possible operating modes of the nuclear power plant and analyzes the corresponding standard operating conditions for different modes. Each standard operating condition corresponds to different primary coolant status parameters, available safety functions, and operational technical specifications. These primary coolant status parameters include primary coolant pressure, temperature, and water level.

[0066] The implementation of this step can refer to the operating technical specifications of nuclear power plants. Taking a certain type of nuclear power unit in China as an example, its standard operating conditions are shown in Table 2 below:

[0067] Table 2

[0068]

[0069] In this embodiment, step S2: analyzing the impact of the typhoon on the nuclear power plant, further includes:

[0070] Step S21: Based on the impact of the typhoon on the nuclear power plant's structures, systems, and components (SSCs), analyze the potential initiating events, i.e., accident scenarios, that the typhoon may cause. Note that different typhoon classes may result in different potential initiating events.

[0071] Step S22: Analyze the safety functions required by the nuclear power plant to mitigate initiating events. Safety functions are the means designed by the nuclear power plant to mitigate accidents; different accidents require different mitigation measures.

[0072] Step S23: Analyze the impact of the typhoon on the safety functions required for the initiating event.

[0073] During the implementation of this step, the impact of the initiating event and safety functions can be referenced from the nuclear power plant's Final Safety Analysis (FSAR) report, Probabilistic Safety Assessment (PSA) report, SSC wind resistance assessment report, and other information on the nuclear power plant's typhoon protection design and modifications.

[0074] Typically, typhoon-induced events at nuclear power plants include loss of external power (LOOP) and loss of heat sink (LUHS). Because transmission lines and related suspended substations (SSCs) are mostly exposed, they are susceptible to wind pressure and wind-blown debris. Typhoons can also easily cause debris to clog the nuclear power plant's intake. Domestic and international experience in nuclear power plant operation also shows that LOOP and LUHS accidents are the main accidental impacts of typhoons on nuclear power plants.

[0075] Because outdoor maintenance work cannot be effectively carried out during typhoons, emergency mitigation measures for restoring external power are unavailable. Furthermore, typhoons can affect multiple units at the site simultaneously, rendering emergency mitigation measures provided by adjacent units ineffective.

[0076] In this embodiment, step S3: Based on the analysis in steps S1 and S2, taking the power operation condition as the initial operating condition, determine the potential retreat operation mode and its corresponding accident conditions and available safety functions under the influence of a typhoon, further including:

[0077] Step S31: Based on the analysis in step S1, take the power operation condition as the initial condition and determine the potential retreat operation mode.

[0078] Step S32: Based on the analysis in step S2, determine the initiating events and available safety functions corresponding to the potential retreat operation mode under the influence of the typhoon.

[0079] Specifically, during typhoon conditions, the unit control strategy uses the power operating condition as the initial condition. The core of unit control is determining whether to implement power reduction, shutdown, or reactor shutdown operations as a retreat measure, and to which operating mode to retreat to. Based on the analysis in step S1, this step uses the power operating condition as the initial condition to determine potential retreat operating modes. Furthermore, based on the analysis in S2, it determines the initiating events and available safety functions corresponding to these potential retreat operating modes under typhoon influence.

[0080] The analysis for this step is recorded in Table 3 below.

[0081] Table 3

[0082]

[0083] In this embodiment, step S4: Based on the accident conditions and available safety functions of different withdrawal operation modes under the influence of typhoons, a deterministic safety analysis is performed on accidents caused by typhoons to evaluate the applicability of different withdrawal operation modes under typhoon conditions, further including:

[0084] Based on the accident conditions and available safety functions of different evacuation operation modes under typhoon impact, deterministic calculations are conducted to analyze the mitigation of accidents and assess the applicability of different evacuation operation modes under typhoon conditions. Mitigation refers to whether the accident can be effectively mitigated, the longest time required for mitigation, and the resources consumed (such as auxiliary water supply).

[0085] Specifically, the potential withdrawal operation mode in step S3 is used as the starting point for deterministic accident analysis, and the final state of accident development (unit safety and stability or core damage) is used as the endpoint. The analysis is conducted on the initiating event identified in step S2. By calculating whether the typhoon-induced accident can be effectively mitigated under different withdrawal operation modes and different safety function availability conditions, as well as the longest time required for accident mitigation and the resources consumed (such as auxiliary feedwater volume), the applicable withdrawal operation modes under different accident conditions are evaluated.

[0086] In this embodiment, step S5, based on the accident conditions and available safety functions of different retreat operation modes under the influence of typhoons, performs a probabilistic safety analysis on accidents caused by typhoons to assess the priority of different retreat operation modes under typhoon conditions, and further includes:

[0087] Step S51: Based on the Level 1 PSA model of internal events under low power and shutdown conditions of nuclear power plants, determine the correspondence between each nuclear power plant operating state (POS) in the PSA model and potential retreat operation modes. Here, POS is a unit configuration with relatively constant operating parameters, generally corresponding to the unit's standard operating condition. Typically, each potential retreat operation mode can correspond to a POS in the PSA model; otherwise, the PSA model needs to be modified to meet the requirements for determining the unit control strategy.

[0088] Step S52: Based on the initial event analyzed in Step S2, select the corresponding event tree in the PSA model. According to the impact of the typhoon on safety functions, modify the relevant function headers and corresponding fault trees in the event tree to reflect the actual impact of the typhoon, such as setting the power restoration function to be unavailable. The function headers represent the safety functions required to mitigate the initial event; the input to the function headers is primarily the fault tree, used to calculate the failure probability of the safety functions required to mitigate the initial event.

[0089] Step S53: For the selected shutdown PSA event tree, calculate the conditional core damage probability (CCDP) corresponding to the potential retreat operation mode to evaluate the priority of different retreat operation modes under typhoon conditions.

[0090] CCDP represents the probability of core damage caused by an accident under a given unit state and safety function configuration. For a given initiating event, it can be used to assess the risk magnitude of different retreat operation modes. For the selected shutdown PSA event tree, the CCDP corresponding to each potential retreat operation mode is calculated. A lower CCDP indicates a stronger ability to withstand typhoon accident risks. Based on the quantitative risk results of each potential retreat operation mode under different typhoon accident scenarios, the optimal retreat operation mode under different accident scenarios is evaluated.

[0091] In this embodiment, step S6: Based on the combined deterministic and probabilistic security analysis results, determine the typhoon generator control strategy for the initial power operation condition. This typhoon generator control strategy involves retrenching the generator to an operating mode starting a preset time before the expected typhoon conditions. Specifically:

[0092] Based on the combined deterministic and probabilistic analyses, for specific typhoon accident scenarios, the applicability of different relocation operation modes is primarily determined by deterministic results, while the priority of different relocation operation modes is compared primarily by probabilistic results. If multiple relocation operation modes are applicable and have the same priority, the mode with the higher safety margin is conservatively selected based on factors such as technical specifications, the time required for relocation, and the resources needed for accident mitigation.

[0093] The typhoon generator unit operation control strategy needs to consider not only the unit's retrenchment status but also the retrenchment time, i.e., how far in advance the retrenchment should begin. The unit retrenchment time is determined by the following formula:

[0094] T 后撤 =max{T 技术规范允许时间 T 后事故缓解所需最长时间}+T 安全裕量

[0095] This means that, under the condition of meeting the technical specifications, a certain safety margin is added to the maximum time required for accident mitigation; otherwise, the time allowed by the technical specifications is added to the safety margin. The safety margin is generally taken as 2 hours.

[0096] The typhoon generator control strategy includes the following content, as shown in the table below. Taking number 1 as an example, the corresponding typhoon generator control strategy is as follows: Before the wind force at the nuclear power plant site reaches L1, the generator will be moved back to platform 1 starting at time T1, as shown in Table 4 below:

[0097] Table 4

[0098]

[0099]

[0100] In some embodiments, such as Figure 2 As shown, this method also includes:

[0101] Step S7: Based on the typhoon generator control strategy under the initial power operation condition, determine the typhoon generator control strategy for other initial operating conditions.

[0102] For the initial operating condition of the unit that is not operating at power, based on the analysis results of steps S4 and S5, the reversal operating mode of the initial operating condition of power operation determined in step S6 is compared, and the operating condition with lower risk in the case of typhoon accident is selected as the reversal operating mode.

[0103] In this case, the time for the unit to begin its retreat ahead of schedule is the retreat time for the initial power operation condition determined in step S6 minus the time for transitioning from the initial power operation condition to the initial non-power operation condition.

[0104] The final unit operation control strategies for nuclear power plants under typhoon conditions, including different initial operating conditions, are shown in Table 5 below:

[0105] Table 5

[0106]

[0107] like Figure 3 As shown, the present invention also discloses a system for determining the control strategy of a nuclear power plant unit under typhoon conditions, comprising:

[0108] The unit operation mode analysis module is used to analyze different operation modes of nuclear power plant units;

[0109] The typhoon impact analysis module is used to analyze the impact of typhoons on nuclear power plants.

[0110] The accident condition and available safety function determination module is used to determine potential retreat operation modes and their corresponding accident conditions and available safety functions under the influence of typhoons, based on the analysis of the unit operation mode analysis module and the typhoon impact analysis module, with the power operation condition as the initial condition.

[0111] The deterministic analysis module is used to perform deterministic safety analysis on typhoon-induced accidents based on the accident conditions and available safety functions of different retreat operation modes under the influence of typhoons, in order to evaluate the applicability of different retreat operation modes under typhoon conditions.

[0112] The probability analysis module is used to perform probabilistic safety analysis on typhoon-induced accidents based on the accident conditions and available safety functions of different retreat operation modes under the influence of typhoons, so as to evaluate the priority of different retreat operation modes under typhoon conditions.

[0113] The strategy determination module is used to integrate the results of deterministic and probabilistic security analysis to determine the control strategy for the typhoon unit under the initial power operation conditions.

[0114] In some embodiments, the system further includes a typhoon characteristic determination module, used to determine typhoon characteristic information of the site to be analyzed. Accordingly, the typhoon impact analysis module is further used to: analyze the impact of the typhoon on the nuclear power plant based on the typhoon characteristic information.

[0115] Specifically, different countries and regions have different classifications and definitions of typhoons, resulting in significant differences in typhoon wind speeds, air pressures, and warning signals. Developing unit control strategies during typhoons first requires clarifying the typhoon characteristics of the nuclear power plant site to be analyzed. This involves determining the correspondence between different typhoon parameters and actual wind speeds at the site, so as to obtain the input conditions for unit control actions based on meteorological forecasts and on-site monitoring results. The typhoon characteristics include the definitions of typhoon, severe typhoon, and super typhoon, as well as the definitions of different typhoon levels.

[0116] The typhoon classification for nuclear power plants in my country is shown in Table 1 below:

[0117] Table 1

[0118] Typhoon level Typhoon range Wind speed (m / s) 12 typhoon 32.7-36.9 13 typhoon 37.0-41.4 14 strong typhoon 41.5-46.1 15 strong typhoon 46.2-50.9 16 Super Typhoon 51.0-56.0 17 Super Typhoon 56.1-61.2 Level 17 and above Super Typhoon ≥61.3

[0119] In this embodiment, the unit operation mode analysis module is further used to sort out all possible operation modes of the nuclear power plant, analyze the standard operating conditions corresponding to different operation modes, and the safety functions available under each operating condition.

[0120] Specifically, based on different values ​​of parameters such as nuclear power, primary coolant charge, primary coolant pressure, primary coolant average temperature, and primary coolant boron concentration, nuclear power units will have different standard operating conditions during the design phase. In typhoon conditions, the unit's early power reduction and shutdown operations must be carried out based on these standard operating conditions. This module outlines all possible operating modes of a nuclear power plant and analyzes the corresponding standard operating conditions for different modes. Each standard operating condition corresponds to different primary coolant status parameters, available safety functions, and operational technical specifications. These primary coolant status parameters include primary coolant pressure, temperature, and water level.

[0121] The implementation of this module can refer to the operating technical specifications of nuclear power plants. Taking a certain type of nuclear power unit in China as an example, its standard operating conditions are shown in Table 2 below:

[0122] Table 2

[0123]

[0124]

[0125] In this embodiment, the typhoon impact analysis module includes:

[0126] The initiating event module is used to analyze the potential initiating events, i.e., accident scenarios, that may result from typhoons affecting the structures, systems, and components (SSCs) of nuclear power plants. Different typhoon severity levels may lead to different initiating events.

[0127] The safety function module analyzes the safety functions required by a nuclear power plant to mitigate initiating events. These safety functions are the means by which a nuclear power plant is designed to mitigate accidents; different accidents require different mitigation measures.

[0128] The impact module is used to analyze the impact of typhoons on the safety functions required for the initiating event.

[0129] During the implementation of this typhoon impact analysis module, the impact of the initiating event and safety functions can be referenced from the nuclear power plant's Final Safety Analysis Report (FSAR), Probabilistic Safety Assessment (PSA) report, SSC wind resistance assessment report, and other information on nuclear power plant typhoon prevention design and modification.

[0130] Typically, typhoon-induced events at nuclear power plants include loss of external power (LOOP) and loss of heat sink (LUHS). Because transmission lines and related suspended substations (SSCs) are mostly exposed, they are susceptible to wind pressure and wind-blown debris. Typhoons can also easily cause debris to clog the nuclear power plant's intake. Domestic and international experience in nuclear power plant operation also shows that LOOP and LUHS accidents are the main accidental impacts of typhoons on nuclear power plants.

[0131] Because outdoor maintenance work cannot be effectively carried out during typhoons, emergency mitigation measures for restoring external power are unavailable. Furthermore, typhoons can affect multiple units at the site simultaneously, rendering emergency mitigation measures provided by adjacent units ineffective.

[0132] In this embodiment, the accident condition and available safety function determination module is further used to determine potential retreat operation modes based on the analysis of the unit operation mode analysis module, taking the power operation condition as the initial condition; and to determine the initiating event and available safety functions corresponding to the potential retreat operation modes under the influence of a typhoon based on the analysis of the typhoon impact analysis module.

[0133] Specifically, during typhoon conditions, the unit control strategy uses the power operating condition as the initial condition. The core of unit control is determining whether to implement power reduction, shutdown, or reactor shutdown operations as a retreat measure, and to which operating mode to retreat to. Based on the analysis from the unit operating mode analysis module, this module uses the power operating condition as the initial condition to determine potential retreat operating modes. Furthermore, based on the analysis from the typhoon impact analysis module, it determines the initiating events and available safety functions corresponding to these potential retreat operating modes under typhoon influence.

[0134] The analysis for this module is recorded in the form of Table 3 below.

[0135] Table 3

[0136]

[0137]

[0138] In this embodiment, the deterministic analysis module is further used to perform deterministic calculations based on the accident conditions and available safety functions under the influence of typhoons for different withdrawal operation modes, and to analyze the mitigation of the accident in order to evaluate the applicability of different withdrawal operation modes under typhoon conditions. The mitigation situation refers to whether the accident can be effectively mitigated, the longest time required for accident mitigation, and the resources required for mitigation (such as auxiliary water supply).

[0139] Specifically, the analysis uses the potential retreat operation modes identified in the accident condition and available safety functions determination module as the starting point for deterministic accident analysis, and the final state of accident development (unit safety and stability or core damage) as the endpoint. The analysis focuses on the initiating event identified in the typhoon impact analysis module. By calculating whether typhoon-induced accidents can be effectively mitigated under different retreat operation modes and different safety function availability conditions, as well as the longest time required for accident mitigation and the resources consumed (such as auxiliary feedwater), the applicable retreat operation modes under different accident conditions are evaluated.

[0140] In this embodiment, the probabilistic analysis module is further used to determine the correspondence between the operating status (POS) of each nuclear power plant and potential retreat operation modes in the PSA model based on the internal event level-one PSA model of the nuclear power plant under low power and shutdown conditions; combined with the initiating event analyzed by the typhoon impact analysis module, the corresponding event tree is selected in the PSA model, and the relevant function headers and corresponding fault trees in the event tree are modified according to the impact of the typhoon on safety functions; and, for the selected shutdown PSA event trees, the conditional core damage probability (CCDP) corresponding to the potential retreat operation modes is calculated to evaluate the priority of different retreat operation modes under typhoon conditions. Here, the function header represents the safety function required to mitigate the initiating event; the input of the function header is mainly the fault tree, used to calculate the failure probability of the safety function required to mitigate the initiating event.

[0141] CCDP represents the probability of core damage caused by an accident under a given unit state and safety function configuration. For a given initiating event, it can be used to assess the risk magnitude of different retreat operation modes. For the selected shutdown PSA event tree, the CCDP corresponding to each potential retreat operation mode is calculated. A lower CCDP indicates a stronger ability to withstand typhoon accident risks. Based on the quantitative risk results of each potential retreat operation mode under different typhoon accident scenarios, the optimal retreat operation mode under different accident scenarios is evaluated.

[0142] In this embodiment, the strategy determination module is used to determine the typhoon generator control strategy based on the combined deterministic and probabilistic security analysis results. The typhoon generator control strategy is to retreat the generator to an operating mode at a preset time before the expected typhoon conditions.

[0143] Based on the combined deterministic and probabilistic analyses, for specific typhoon accident scenarios, the applicability of different relocation operation modes is primarily determined by deterministic results, while the priority of different relocation operation modes is compared primarily by probabilistic results. If multiple relocation operation modes are applicable and have the same priority, the mode with the higher safety margin is conservatively selected based on factors such as technical specifications, the time required for relocation, and the resources needed for accident mitigation.

[0144] The typhoon generator unit operation control strategy needs to consider not only the unit's retrenchment status but also the retrenchment time, i.e., how far in advance the retrenchment should begin. The unit retrenchment time is determined by the following formula:

[0145] T 后撤 =max{T 技术规范允许时间 T 后事故缓解所需最长时间}+T 安全裕量

[0146] This means that, under the condition of meeting the technical specifications, a certain safety margin is added to the maximum time required for accident mitigation; otherwise, the time allowed by the technical specifications is added to the safety margin. The safety margin is generally taken as 2 hours.

[0147] The typhoon generator control strategy includes the following content, as shown in the table below. Taking number 1 as an example, the corresponding typhoon generator control strategy is as follows: Before the wind force at the nuclear power plant site reaches L1, the generator will be moved back to platform 1 starting at time T1, as shown in Table 4 below:

[0148] Table 4

[0149]

[0150] In some embodiments, the system further includes:

[0151] The other strategy determination module is used to determine the typhoon unit control strategy for other initial operating conditions based on the typhoon unit control strategy under the initial power operation condition.

[0152] For the initial operating condition of the unit that is not operating at power, the analysis results of the deterministic analysis module and the probabilistic analysis module are compared with the retreat operation mode of the initial operating condition of power operation determined by the strategy determination module. The operating condition with lower risk in the case of typhoon accident is selected as the retreat operation mode.

[0153] In this case, the time for the unit to begin its early retreat is the retreat time for the initial power operation condition determined by the strategy determination module minus the time for transitioning from the initial power operation condition to the non-power operation initial condition.

[0154] The final unit operation control strategies for nuclear power plants under typhoon conditions, including different initial operating conditions, are shown in Table 5 below:

[0155] Table 5

[0156]

[0157]

[0158] By implementing this invention, the following beneficial effects are achieved:

[0159] This invention establishes an operational control strategy that conforms to the typhoon impact characteristics of specific plant sites and the actual operation of the units, solving the problem of insufficient unit control actions in domestic nuclear power plants during typhoons. By taking control actions in advance based on typhoon impact conditions, the impact of typhoons on nuclear safety can be effectively reduced, the typhoon-in-depth defense system of nuclear power plants can be improved, and the ability of units to cope with typhoon disasters can be enhanced.

[0160] The system establishes unit control actions for nuclear power plants under typhoon conditions, providing more specific, detailed, and operable unit control methods for nuclear power units. This avoids the problem of insufficient attention to nuclear safety caused by relying solely on grid instructions, as well as the operational pressure and uncertainty risks brought about by relying solely on temporary decisions made by on-duty personnel.

[0161] This method can be extended to the study of unit control strategies under other external disasters affecting nuclear power plants, such as intake blockage events caused by marine organisms. It provides support for establishing systematic and comprehensive unit control actions against external disasters at nuclear power plants, thereby enhancing the ability of nuclear power units to cope with such events.

[0162] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for determining a control strategy of a nuclear power plant under typhoon conditions, characterized in that, The method comprises the following steps: S1: analyzing different operation modes of a nuclear power plant unit; S2: analyzing the influence of a typhoon on the nuclear power plant; S3: determining potential retreat operation modes and corresponding accident conditions and available safety functions under the influence of a typhoon according to the analysis of steps S1 and S2, with a power operation condition as an initial condition; S4: performing a deterministic safety analysis on an accident caused by a typhoon according to the accident conditions and available safety functions of different retreat operation modes under the influence of a typhoon, to evaluate the applicability of different retreat operation modes under the condition of a typhoon; S5: performing a probabilistic safety analysis on an accident caused by a typhoon according to the accident conditions and available safety functions of different retreat operation modes under the influence of a typhoon, to evaluate the priority of different retreat operation modes under the condition of a typhoon; S6: comprehensively determining the results of the deterministic and probabilistic safety analyses to determine a typhoon unit control strategy for a power operation initial condition; wherein step S2 comprises: S21: analyzing a possible initiating event caused by a typhoon according to the influence of a typhoon on the structures, systems and components of a nuclear power plant; S22: analyzing safety functions required for the nuclear power plant to mitigate the initiating event; S23: analyzing the influence of a typhoon on the safety functions required for the initiating event.

2. The method of claim 1, wherein, The method further comprises: S0: determining typhoon characteristic information of a plant site to be analyzed; Correspondingly, step S2 comprises: analyzing the influence of a typhoon on a nuclear power plant according to the typhoon characteristic information.

3. The method of claim 1, wherein, Step S1 comprises: analyzing all possible operation modes of a nuclear power plant, analyzing standard operation conditions corresponding to different operation modes, and analyzing available safety functions under each operation condition.

4. The method for determining a control strategy of a nuclear power plant during a typhoon according to claim 3, wherein, Step S3 comprises: S31: determining potential retreat operation modes according to the analysis of step S1, with a power operation condition as an initial condition; S32: determining corresponding initiating events and available safety functions of potential retreat operation modes under the influence of a typhoon according to the analysis of step S2.

5. The method for determining the control strategy of the nuclear power plant under typhoon conditions according to claim 4, characterized in that, Step S4 comprises: According to the accident conditions and available safety functions of different retreat operation modes under the influence of a typhoon, performing a deterministic calculation to analyze the mitigation of the accident, to evaluate the applicability of different retreat operation modes under the condition of a typhoon.

6. The method of claim 3, wherein, Step S5 comprises: S51: determining the correspondence between each operation state of a nuclear power plant and potential retreat operation modes in a PSA model based on an internal event level 1 PSA model of a nuclear power plant in a low-power and shutdown condition; S52: selecting a corresponding event tree in the PSA model in combination with the initiating events analyzed in step S2, modifying related function headers in the event tree and the fault trees corresponding to the function headers according to the influence of a typhoon on safety functions; S53: calculating the conditional core damage probability corresponding to the potential retreat operation modes for the selected shutdown PSA event tree, to evaluate the priority of different retreat operation modes under the condition of a typhoon.

7. The method for determining a control strategy of a nuclear power plant during a typhoon according to claim 1, wherein, The method further comprises: S7: determining typhoon unit control strategies for other initial conditions according to the typhoon unit control strategy for a power operation initial condition.

8. A system for determining the control strategy of a nuclear power plant unit under typhoon conditions, characterized in that, It comprises: a unit operation mode analysis module for analyzing different operation modes of a nuclear power plant unit; a typhoon influence analysis module for analyzing the influence of a typhoon on a nuclear power plant; An accident condition and available safety function determination module is configured to determine potential post-retrieval operation modes and their corresponding accident conditions and available safety functions under typhoon influence based on the analysis of the unit operation mode analysis module and the typhoon influence analysis module, with a power operation condition as an initial condition; A determinism analysis module is configured to perform a determinism safety analysis on accidents caused by typhoons based on the accident conditions and available safety functions of different post-retrieval operation modes under typhoon influence, so as to evaluate the applicability of different post-retrieval operation modes under typhoon conditions; A probability analysis module is configured to perform a probability safety analysis on accidents caused by typhoons based on the accident conditions and available safety functions of different post-retrieval operation modes under typhoon influence, so as to evaluate the priority of different post-retrieval operation modes under typhoon conditions; A strategy determination module is configured to determine a typhoon unit control strategy for a power operation initial condition based on the results of the determinism and probability safety analyses; The typhoon influence analysis module includes: An initiating event module is configured to analyze possible initiating events caused by typhoons based on the influence of typhoons on the structures, systems and components of a nuclear power plant; A safety function module is configured to analyze safety functions required by the nuclear power plant to mitigate the initiating events; An influence module is configured to analyze the influence of typhoons on the safety functions required by the initiating events.

9. The nuclear power plant system for determining a control strategy of a nuclear power plant in a typhoon according to claim 8, wherein, The system further includes: A typhoon feature determination module is configured to determine typhoon feature information of a plant site to be analyzed; An other strategy determination module is configured to determine typhoon unit control strategies for other initial conditions based on the typhoon unit control strategy for the power operation initial condition.

Images