Method, system and equipment for distributing forced unavailable indexes of unit

Abstract

The invention provides a method, a system and equipment for distributing forced unavailable indexes of a unit. The method comprises the following steps: firstly, identifying and screening out systems possibly causing forced unavailability of a unit; then carrying out preliminary distribution by adopting a probability availability evaluation method; then, evaluating a preliminary distribution result, if a forced unavailable time margin exists, constructing a forced unavailable fault tree model of the unit, calculating a contribution proportion of each to-be-distributed system to a top event, and quantitatively distributing the time margin to each to-be-distributed system according to the proportion; and finally, adding the preliminary distribution value and the margin distribution value to obtain a final index of each system to be distributed. According to the method, a clear quantitative basis is provided for time margin distribution through the fault tree model, and meanwhile, a single fault and multiple faults of the equipment are considered, so that the distribution result better conforms to the actual operation condition of the unit, and the economical efficiency of the unit is optimized on the premise of ensuring the reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear power plant reliability engineering, and in particular to a unit forced unavailability index allocation method, system and device. BACKGROUND

[0002] The availability of a nuclear power unit is a core index for measuring its safety and economy, and the availability directly affects the power generation benefit and market competitiveness of the power plant. The causes of unit unavailability include planned shutdown (such as refueling overhaul and in-service inspection) and unplanned shutdown (i.e. forced shutdown caused by random failure of equipment, human error and other unexpected events). In the design stage of a nuclear power plant, the unavailability index of the unit needs to be allocated in advance to guide the reliability design of each system. Among them, the allocation of forced unavailability time index directly affects the balance between economy and reliability of the unit.

[0003] For the allocation of forced unavailability time index, the probability availability assessment (PAA) method is generally used to preliminarily calculate the forced unavailability time of each system by analyzing single random failure of equipment. However, when the sum of PAA calculation results of each system and the overall target value of the unit exist a difference (i.e. time margin), the allocation of the margin lacks objective quantitative basis, and the subsequent margin allocation is heavily dependent on experience and judgment, which is highly subjective and lacks unified standards, and the design balance is not good. More importantly, the PAA method only considers single independent failure of equipment and cannot represent multiple failure scenarios, resulting in deviation of the analysis results from the complex actual operation conditions of the nuclear power plant, so that the finally allocated index cannot truly reflect the contribution of each system to the unit-level risk. SUMMARY

[0004] The present application provides a unit forced unavailability index allocation method, system and device to solve the technical problems that the allocation of forced unavailability time margin has no basis to follow, it is difficult to accurately reflect the actual contribution of each system to the unavailability event, and the index allocation cannot take into account double or multiple failures of equipment, thereby not meeting the actual operation conditions of the unit.

[0005] The unit forced unavailability index allocation method provided by the present application comprises: identifying and screening out systems to be allocated that may affect the availability of the unit, and preliminarily allocating the forced unavailability index of the unit to each of the systems to be allocated to obtain a preliminary allocation value; accumulating the preliminary allocation values of all the systems to be allocated, judging whether there is a forced unavailability time margin, if yes, constructing a fault tree model of the forced unavailability of the unit, and calculating the contribution proportion of each of the systems to be allocated to the top event based on the fault tree model; allocating the forced unavailability time margin to each of the systems to be allocated according to the contribution proportion to calculate a margin allocation value of each of the systems to be allocated; The final forced unavailability time index of each of the to-be-allocated systems is obtained by adding the preliminary allocation value of each of the to-be-allocated systems to the margin allocation value.

[0006] In an embodiment of the present application, the step of identifying and screening the to-be-allocated systems that may affect the unit availability and preliminarily allocating the forced unavailability index of the unit to each of the to-be-allocated systems to obtain a preliminary allocation value comprises: The preliminary allocation value of each of the to-be-allocated systems is obtained by preliminarily allocating the forced unavailability index of the unit by using a probabilistic availability evaluation method.

[0007] In an embodiment of the present application, the step of adding the preliminary allocation value of all the to-be-allocated systems, determining whether there is a forced unavailability time margin, and if yes, constructing a fault tree model of the forced unavailability of the unit and calculating the contribution proportion of each of the to-be-allocated systems to the top event based on the fault tree model comprises: The preliminary allocation value of all the to-be-allocated systems is added, and it is determined whether the unit availability target is reached; If no, the design scheme is modified in combination with probabilistic safety evaluation analysis; If yes, it is determined whether there is a forced unavailability time margin; If no, the calculation is ended, and the preliminary allocation value is the final forced unavailability time index; If yes, a fault tree model of the forced unavailability of the unit is constructed, and the contribution proportion of each of the to-be-allocated systems to the top event is calculated based on the fault tree model.

[0008] In an embodiment of the present application, the step of constructing the fault tree model of the forced unavailability of the unit comprises: The forced unavailability of the unit is determined as a top event; Automatic shutdown, manual shutdown and power reduction are taken as intermediate events, and are connected to the top event through a logic OR gate; The intermediate events are further decomposed into system failure events; For each system failure event, a subsystem fault tree is constructed with the system failure as a top event, and is decomposed into a device fault mode basic event layer by layer.

[0009] In an embodiment of the present application, the step of calculating the contribution proportion of each of the to-be-allocated systems to the top event based on the fault tree model comprises: All minimal cut sets of the top event in the fault tree model and the probability of each of the minimal cut sets are calculated; The minimal cut sets are screened and classified according to the systems to which they belong; For each system, the Fussel-Veseley importance degree is calculated, and the Fussel-Veseley importance degree is taken as the contribution proportion of each of the to-be-allocated systems to the top event.

[0010] In one embodiment of the present application, the probability of the minimal cut set is the product of the probabilities of all basic events in the cut set, and the minimal cut set includes one or more basic events.

[0011] In one embodiment of the present application, the Fussel-Veseley importance is calculated by the following formula:

[0012] wherein, is the Fussel-Veseley importance of system i, is the sum of the probabilities of all minimal cut sets containing the event of system i, is the total probability of the top event.

[0013] In one embodiment of the present application, the margin allocation value of each of the to-be-allocated systems is calculated according to the contribution ratio by the following formula:

[0014] wherein, is the margin allocation value of system i, is the total forced unavailability time margin, is the contribution ratio of system i to the top event.

[0015] The present application also provides a unit forced unavailability index allocation system, comprising: a preliminary allocation module, configured to identify and screen to-be-allocated systems that can affect the availability of a unit, and to preliminarily allocate a forced unavailability index of the unit to each of the to-be-allocated systems to obtain a preliminary allocation value; a judgment and evaluation module, configured to accumulate the preliminary allocation values of all to-be-allocated systems, to judge whether there is a forced unavailability time margin, and if so, to construct a fault tree model of the forced unavailability of the unit, and to calculate a contribution ratio of each to-be-allocated system to a top event based on the fault tree model; a margin allocation module, configured to calculate a margin allocation value of each of the to-be-allocated systems according to the contribution ratio of the forced unavailability time margin; a final allocation module, configured to add the preliminary allocation value and the margin allocation value of each to-be-allocated system to obtain a final forced unavailability time index of each of the to-be-allocated systems.

[0016] The present application also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor implements the steps of the unit forced unavailability index allocation method according to any one of the above embodiments when executing the computer program.

[0017] The present application has the following beneficial effects: the unit forced unavailability index allocation method and system provided by the present application introduces a fault tree model and calculates the importance of each to-be-allocated system as an allocation basis, so that the allocation process of the forced unavailability time margin has a clear quantitative basis, the allocation result is traceable, and the overall analysis process and steps are simplified; the fault tree model can identify and calculate the minimum cut set containing multiple basic events, so that not only the single failure of the equipment is considered, but also the influence of double or multiple failures of the equipment on the unit forced unavailability is considered, so that the analysis process is more in line with the actual operation of the unit; by fully and reasonably allocating the forced unavailability time margin to each to-be-allocated system, the unavailability time index allocated to each system is more matched with the actual reliability level and risk contribution of the system, so that the system design can be optimized under the premise of ensuring the overall availability of the unit, the efficiency and accuracy of the index allocation work are improved, the best balance between reliability and economy is achieved, and the market competitiveness of the unit is improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one embodiment consistent with the present application and, together with the description, serve to explain the principles of the application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained from these drawings without creative labor for those skilled in the art.

[0019] In the drawings: Figure 1 A flowchart of a unit forced unavailability index allocation method provided by an embodiment of the present application is shown in the figure. Figure 2 A work flowchart of a unit forced unavailability index allocation method provided by an embodiment of the present application is shown in the figure. Figure 3 A unit forced unavailability top-level fault tree diagram provided by an embodiment of the present application is shown in the figure. Figure 4 A two-loop steam system failure sub-fault tree diagram provided by an embodiment of the present application is shown in the figure. Figure 5 An MSS system nuclear island part A failure sub-fault tree diagram provided by an embodiment of the present application is shown in the figure. Figure 6 An MSS system nuclear island part B failure sub-fault tree diagram provided by an embodiment of the present application is shown in the figure. Figure 7 A failure sub-fault tree diagram of a steam supply pipeline leading to the outside of the plant provided by an embodiment of the present application is shown in the figure. Figure 8 A failure sub-fault tree diagram of a steam supply pipeline leading to the HFS deaerator provided by an embodiment of the present application is shown in the figure. Figure 9 A steam pipeline drain line failure sub-fault tree diagram provided by an embodiment of the present application; Figure 10 A 311TY pipeline isolation valve isolation failure sub-fault tree diagram provided by an embodiment of the present application; Figure 11 A 312TY pipeline isolation valve isolation failure sub-fault tree diagram provided by an embodiment of the present application; Figure 12 A 240TY pipeline isolation valve isolation failure sub-fault tree diagram provided by an embodiment of the present application; Figure 13 An RHR system in a PSA model provided by an embodiment of the present application; Figure 14 An RHR system in a forced shutdown model provided by an embodiment of the present application; Figure 15 A CCW system in a PSA model provided by an embodiment of the present application; Figure 16 A CCW system in a forced shutdown model provided by an embodiment of the present application; Figure 17 A partial minimal cut set of a top event and a probability list representation diagram thereof provided by an embodiment of the present application; Figure 18 A partial minimal cut set of a top event and a probability list representation diagram thereof provided by an embodiment of the present application; Figure 19 A partial minimal cut set of a top event and a probability list representation diagram thereof provided by an embodiment of the present application; Figure 20 A partial minimal cut set of a top event and a probability list representation diagram thereof provided by an embodiment of the present application. DETAILED DESCRIPTION

[0020] The present application is described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0021] It should be noted that the diagrams provided in the following embodiments are merely schematic to illustrate the basic concept of the present application, and the drawings only show the components related to the present application rather than the number, shape and size of the components in actual implementation. The type, number and proportion of the components in actual implementation can be arbitrarily changed, and the layout type of the components can be more complex.

[0022] In the following description, numerous specific details are discussed in order to provide a thorough understanding of the embodiments of the application. However, it will be apparent to one skilled in the art that the embodiments of the application can be practiced without these specific details. In other instances, well-known structures and devices are not described in exhaustive detail in order to avoid obscuring the embodiments of the application.

[0023] In the design and operation of large complex systems such as nuclear power units, scientifically and reasonably allocating the forced outage time index of the unit is the key to balance the reliability and economy of the system. Generally, the index is initially allocated to each system according to empirical data, etc., to just meet the forced outage time index of the unit, and then the index is allocated through PAA calculation. When there is a time margin, a random assignment is often made according to the system safety classification and personal subjective experience judgment. The final index allocation is mainly based on the PAA calculation results and the secondary allocation results, and the initial allocation is taken as a reference to ensure that the re-allocation values of all systems add up to the forced outage index when the allocation is completed, and at the same time, the re-allocation values of each system are as close to the PAA calculation results as possible. This method has obvious defects: first, for the forced outage time margin that may occur after the allocation is completed, there is a lack of clear quantitative allocation basis, and the randomness is strong; second, the probability availability assessment method is based on system failure mode and effect analysis, mainly considering the single random failure of equipment, and cannot effectively reflect the cumulative impact of double or multiple failures of equipment on the operation of the unit, which deviates from the actual operation of the unit; in addition, the initial allocation step in the index allocation process has little significance due to the lack of reliable basis afterwards, and these defects affect the scientificity of the index allocation and the optimization level of the final system design.

[0024] Referring to Figures 1 to 20 The application provides a forced outage index allocation method of a unit, which comprises the following steps: S100, identifying and screening out to-be-allocated systems that may affect the availability of the unit, and preliminarily allocating the forced outage index of the unit to each to-be-allocated system to obtain a preliminary allocation value; S200, adding up the preliminary allocation values of all to-be-allocated systems, judging whether there is a forced outage time margin, if yes, constructing a fault tree model of the forced outage of the unit, and calculating the contribution proportion of each to-be-allocated system to the top event based on the fault tree model; S300, calculating the margin allocation value of each to-be-allocated system according to the contribution proportion of the forced outage time margin; S400, adding the preliminary allocation value and the margin allocation value of each to-be-allocated system to obtain the final forced outage time index of each to-be-allocated system.

[0025] Referring to Figures 1 to 2In an embodiment of the present application, step S100 comprises: The probability availability assessment method is used to preliminarily allocate the forced unavailability indexes of the unit, and a preliminary allocation value of each to-be-allocated system is obtained.

[0026] It should be noted that the PAA (probability availability assessment) method can preliminarily obtain the forced unavailability time of the unit caused by failure of each to-be-allocated system through simple analysis and calculation, and can also reflect the maintenance unavailability of the equipment, but has the defects of being unable to quantitatively allocate the margin of the forced unavailability time and being unable to take into account the double or multiple faults of the equipment; the fault tree model can make the allocation of the margin of the forced unavailability time have a quantitative basis through simple importance analysis, and can also take into account the double or multiple faults of the equipment, but the introduction of the time factor (such as the maintenance unavailability time) in the model will greatly increase the complexity of the cut set processing. Therefore, in the present application, the forced unavailability indexes of the unit are allocated by combining the respective advantages of the PAA method and the fault tree model, and a PAA calculation superimposed fault tree modeling method is used to achieve the best allocation of the forced unavailability indexes of the unit. The PAA calculation is mainly to reasonably allocate most of the forced unavailability time, fully reflect the time contribution of the maintenance unavailability, and make the allocation process more practical; the fault tree model is to allocate the remaining small part of the forced unavailability time according to the importance of the system, and realize the full use of the forced unavailability indexes. Although the fault tree model cannot reflect the time contribution of the maintenance unavailability, since the remaining small part of the time is relatively short, the influence of the maintenance unavailability can be ignored, and it will not cause a large deviation in the final calculation result.

[0027] The forced unavailability index allocation method of the unit of the present application realizes the quantitative allocation of the margin of the forced unavailability time through the collaborative application of the probability availability assessment and the fault tree model, makes the allocation result have a basis, and simultaneously takes into account the single fault and the multiple faults of the equipment, so that the index allocation process is more scientific, the allocation result is more in line with the actual operation risk of the unit, and ultimately helps to achieve the best balance between reliability and economy.

[0028] Please refer to Figures 1 to 2In one embodiment of the present invention, in step S100, the system identification process is based on system failure mode identification and unit operation impact analysis. The purpose of this step is to identify and eliminate systems that will not cause forced unit unavailability, while retaining systems that may affect unit availability for subsequent PAA calculations. Specifically, for example, a comprehensive review of all unit systems can be conducted to analyze the function of each system and its potential impact on the unit's operating status after failure. This allows for the elimination of systems that, even if they fail, will not trigger forced unavailability events such as unit shutdown or power reduction, such as some auxiliary, non-critical support systems. Simultaneously, all systems that may directly or indirectly cause forced unit unavailability, such as systems involving critical functions like reactor control, residual heat removal, and main steam supply, are accurately retained as systems to be allocated for subsequent analysis and calculations. This step, as a preprocessing stage of the entire allocation process, focuses analytical resources on critical systems, avoiding unnecessary analysis of non-contributing systems in subsequent calculations, significantly improving the efficiency and relevance of the entire allocation method.

[0029] Please see Figures 1 to 2 In one embodiment of the present invention, in step S100, a probabilistic availability assessment (PAA) calculation method is used for preliminary allocation. The purpose of this step is to quantitatively assess the unit downtime that may be caused by random equipment failures by identifying important equipment within the system that may affect unit availability and their failure modes, thereby obtaining an initial, macroscopic index allocation scheme. Specifically, for example, based on the results of system failure mode and impact analysis (FMEA), single failure modes that may force unit downtime for each important piece of equipment within the system can be identified; using probabilistic methods, combined with equipment reliability data, such as failure rate and mean time to repair, the unit downtime that may be caused by each single equipment failure mode is quantitatively assessed; and the downtime caused by all identified equipment failure modes is reasonably accumulated to obtain the preliminary allocation value of the system. This step utilizes a mature probabilistic availability assessment method to provide a relatively macroscopic and realistic initial allocation scheme based on historical data and probability models for most forced downtime, especially considering the equipment maintenance downtime, making the allocation closer to engineering practice. Due to the limitations of the FMEA methodology, this step only identifies a single failure mode that forces the unit to become unavailable, and cannot account for situations involving dual or multiple equipment failures.

[0030] Please see Figures 1 to 2 In one embodiment of the present invention, step S200 includes: Accumulate the initial allocation values ​​of all systems to be allocated to determine whether the unit availability target has been achieved. If not, then modify the design scheme based on probabilistic safety evaluation and analysis; If so, determine whether there is a forced unavailability time margin; If not, the calculation ends, and the preliminary allocation value is the final forced unavailability time index; If so, a fault tree model for the forced unavailability of the unit is constructed, and the contribution ratio of each system to be assigned to the top event is calculated based on the fault tree model.

[0031] Please see Figures 1 to 2 In one embodiment of the present invention, after the initial allocation is completed, the availability of the entire unit is evaluated. The indicators of the initial allocation are summarized and compared with the preset unit availability target to confirm whether the initial allocation can meet the overall availability target of the unit. If, after evaluation, the unit availability target is met and there is a margin (i.e., the actual availability is higher than the target availability, that is, the allocated unavailable time is lower than the total allowed unavailable time), this part of the "forced unavailable time margin" is identified. The purpose is to find the "additional" unavailable time that can be allocated more finely, i.e., the forced unavailable time margin.

[0032] Specifically, please refer to Figure 2After the PAA calculation completes the initial allocation, the initial allocation values ​​of all systems (usually in hours) are first accumulated and compared with the forced unavailability target of the units. If the accumulated value is not greater than the forced unavailability target of the units, it is determined that the unit availability target has been achieved; otherwise, it indicates that the availability target has not been achieved. If the accumulated initial allocation values ​​of all systems do not reach the unit availability target, the design scheme is modified based on the analysis results and recommendations of the Probabilistic Safety Assessment (PSA). For example, the system design is modified, and the allocation values ​​of planned and unplanned unavailability indicators are modified. The initial allocation in step S100 is then re-executed according to the new design scheme until the target is reached. That is, the system PAA calculation is re-performed, the calculation results are updated, and then the forced unavailability target of the units is re-evaluated. This process is iterated until the result meets the target requirements. If the initial allocation values ​​of all systems reach the unit availability target, then it is determined whether there is a forced unavailability time margin. If there is no forced unavailability time margin, then the initial allocation value is the final forced unavailability time index. That is, when the cumulative value of the PAA calculation results of each system to be allocated is exactly equal to the forced unavailability time index of the unit, no further analysis is needed, and the result of the quantitative evaluation calculation of PAA for each system to be allocated is output as the final result. If the initial allocation values ​​of all systems reach the forced unavailability target of the unit and there is a forced unavailability time margin, then the subsequent steps are executed to allocate the forced unavailability time margin (based on the fault tree model), and the final allocation is achieved by combining the PAA calculation results. This step constructs a closed-loop, iterative evaluation and decision-making mechanism. When the target is not achieved, it drives design improvement to ensure that the final solution can meet the overall unit availability requirements. When the target is exactly achieved, the result can be directly output, making the process efficient. And when there is a margin, it provides a clear object and entry point for subsequent more refined margin allocation, ensuring that the forced unavailability index can be fully and reasonably utilized.

[0033] Please see Figures 1 to 16 In one embodiment of the present invention, in step S200, a fault tree model of forced unit unavailability is constructed to analyze the contribution of each system to the forced unit unavailability, providing a systematic tool to identify and quantify all fault combinations leading to forced unavailability, particularly capable of reflecting multiple failures. It should be noted that when constructing the fault tree model, "forced unit unavailability" is the top event, and the model must cover all possible fault paths, including single failures and multiple failures, and ultimately decompose them into basic events.

[0034] Please see Figures 1 to 16 In one embodiment of the present invention, in step S200, constructing a fault tree model for forced unit unavailability includes: Determining forced unavailability of the unit as the top event; Automatic shutdown, manual shutdown, and power reduction are used as intermediate events, and are connected to the top event via a logic OR gate. The intermediate events are further decomposed into individual system failure events; For each system failure event, a subsystem fault tree is constructed with the system failure as the top event, and then decomposed layer by layer to the basic events of the equipment failure mode.

[0035] Please see Figures 1 to 12 In one embodiment of the present invention, the direct causes of forced unit unavailability mainly include reactor shutdown and power reduction, with the ultimate cause being equipment failure. Therefore, the top event of the fault tree is forced unit unavailability, intermediate events (second level) include automatic reactor shutdown, manual reactor shutdown, and power reduction, and intermediate events (third level) include failures of various systems. It should be noted that through multi-level decomposition of intermediate events, the final decomposition is reduced to the bottom event. The bottom event is various modes of equipment failure that may affect unit operation, which are used as basic events for subsequent calculations.

[0036] Please see Figures 1 to 12 In one embodiment of the present invention, Figure 3 This is a Fault Tree Analysis (FTA) diagram used to systematically identify and analyze all possible combinations of causes leading to the "top event." The topmost rectangle, "Unit Forced Unavailability (UNIT_FUA)," is the top event in the entire fault tree, meaning that all causes leading to the unit being forced to stop operating or malfunctioning are being analyzed. The top event is decomposed through an OR gate into three main causes: "Automatic Shutdown," "Manual Shutdown," and "Power Reduction," which are intermediate events (Level 2). This means that if any of these three occurs, the unit will be forced unavailable. The intermediate events (Level 2) are further decomposed into multiple main causes, progressively breaking down to the various system failures. Specifically, for example, automatic shutdown (UNIT_FUA-1) is decomposed into automatic shutdown to hot shutdown (AS01) and automatic shutdown to cold shutdown (AS02) through an OR gate. AS01 and AS02 are further connected to more specific system faults through OR gates. "@!!UNIT_FUA-1" under AS01 means "system fault caused automatic shutdown to hot shutdown of the unit", and its specific cause is connected to the sub-event control bar hydraulic drive system failure (RHD0001) and power condition waste heat removal failure (RHR0000) through an OR gate.

[0037] Please see Figures 4 to 12Furthermore, system models are constructed, with system failure as the top event. The causes of each system failure are further decomposed until they are finally broken down into specific equipment failure modes (such as valve leakage, accidental closure, accidental opening, and operational failure) or power supply failures. It can be understood that in the fault tree model of each system failure event and its sub-events, the top event is associated with the upper-level fault tree through a transfer gate. This transfer gate effectively manages the complexity of the fault tree, avoiding excessive detail in a single diagram, making each diagram relatively clear and readable, while maintaining the logical integrity of the entire fault tree. A series of fault tree diagrams provides a systematic and structured method for understanding and analyzing the potential failure modes and causes of the unit, which is crucial for improving system safety and reliability.

[0038] Please see Figures 1 to 12 In one embodiment of the present invention, under the top event "forced unit unavailability," three intermediate events—"automatic shutdown," "manual shutdown," and "power reduction"—are connected by an OR gate. This means that the occurrence of any one of these events will lead to the top event. Furthermore, automatic shutdown can be decomposed into more specific events such as automatic shutdown to hot shutdown and automatic shutdown to cold shutdown, ultimately relating to system-level events such as control rod hydraulic drive system failure and residual heat removal system failure. For each system-level event, a subtree is constructed with it as the top event, decomposing it layer by layer until the final basic event, such as electric valve leakage, electric valve malfunction, and pneumatic valve malfunction—specific equipment failure modes. This structured and hierarchical modeling method can systematically and comprehensively identify all fault paths that may lead to forced unit unavailability, with clear logic. Because the fault tree model contains a large number of AND and OR gates, it can naturally express scenarios where multiple equipment failures (i.e., multiple failures) lead to system failure, thus overcoming the limitation of probabilistic availability assessment methods that only consider single failures, making the model more reflective of complex actual operating conditions.

[0039] Please see Figures 3 to 12 Specifically, taking the secondary steam system MSS as an example, Figure 4 This is a sub-fault tree constructed with the secondary loop steam system failure (MSS001) as the top event, indicating that all possible causes leading to the malfunction of the entire secondary loop steam system are being analyzed. The transfer gates (!UNIT_FUA, !HFS0001) next to the top event (secondary loop steam system failure) indicate that the event "secondary loop steam system failure (MSS0001)" is related to other fault trees (e.g., Figure 3The input event in the UNIT_FUA fault tree means that its occurrence will affect these upper-level systems. The top event "Secondary loop steam system failure (MSS0001)" is decomposed into two main causes through an OR gate: nuclear island partial failure (@!MSS0001-1) and heat island partial failure (@!MSS0001-2), that is, a partial failure of the secondary loop steam system in the nuclear island region and a partial failure of the secondary loop steam system in the heat island (conventional island) region. Further decomposition reveals that the nuclear island failure (@!MSS0001-1) is further decomposed through an OR gate into failures in column A of the MSS system nuclear island (MSSH1000_FR) and failures in column B of the MSS system nuclear island (MSSH2000_FR), meaning that the failure of the secondary loop steam system in the nuclear island may be caused by a failure in either column A or column B; the thermal island failure (@!MSS0001-2) is further decomposed through an OR gate into failures in the steam supply pipeline leading to the plant area (MSSR1000-FR), the steam supply pipeline leading to the HFS deaerator (MSSR2000-FR), and the steam pipeline drainage pipeline (MSSR3000-FR). Figures 4 to 12 The process involves further decomposing each sub-event layer by layer until it is finally reduced to a specific equipment failure mode. These are then treated as bottom events and no longer decomposed. Bottom events are the root causes of higher-level events and are usually assigned a failure probability for subsequent calculations. The fault tree model shows that the bottom events of the secondary steam system include several basic events such as electric valves (external leakage, accidental closure, refusal to open), manual valves (external leakage), pneumatic valves (malfunction, jamming during operation, external leakage), and pipeline failures.

[0040] It should be noted that the PAA allocation method is mainly based on Failure Mode and Effects Analysis (FMEA), considering only a single equipment failure. The impact on unit operation is also based on this single failure, failing to reflect multiple failures and lacking quantitative basis for time margin allocation. Furthermore, the proportional allocation method cannot reflect differences between systems or the causes of system failures. Taking ICS as an example, the consequences of a single column failure and the failure of both columns are different. A single column failure leads to a 50% power reduction, while the failure of both columns leads to automatic cold shutdown. Such complex consequences cannot be obtained through qualitative PAA analysis combined with simple quantitative calculations, but fault tree models can analyze such complex situations. Figure 3 This scenario is modeled at the lowest level. Furthermore, in Figures 3 to 12 In this context, considering multiple failure modes simultaneously for a certain device reflects multiple faults. For example... Figure 5 Misoperation and external leakage of electric valves. Figure 11 and Figure 12This illustrates the situation where different failure modes of electric valves and different failure modes of manual valves fail simultaneously.

[0041] Please see Figures 1 to 16 In one embodiment of the present invention, the step of constructing a subsystem fault tree includes reusing a probabilistic safety assessment model, which includes directly calling or modifying the system fault tree in the probabilistic safety assessment model. The forced unavailability fault tree model should include all possible causes of unit unavailability, and the model construction approach is consistent with the PSA fault tree modeling approach. Since the PSA model is a detailed fault tree model constructed to assess the risks of nuclear power plants, its coverage largely overlaps with forced unavailability analysis. Existing PSA models can be imported or loaded into the Risk-Spectrum software. The fault trees contained in the model describe in detail the failure modes of various systems and components. These fault trees can be directly used as assessment models for margin allocation, or modified and improved as necessary according to the specific requirements of this allocation. After the model update is completed, subsequent calculations can be performed through the fault tree analysis function.

[0042] Please see Figures 13 to 16 In practical implementation, for some support systems, such as equipment cooling water systems and electrical systems, the failure logic in the forced unavailability model is consistent with the impact logic on safety functions in the probabilistic safety assessment model. Therefore, the original model can be directly called, which greatly reduces the modeling workload. For other systems, such as the RHR system (Passive Residual Heat Removal System), the RHR system's volume compensator is used to maintain pressure and volume fluctuations in the ICS (Intermediate Circuit System). Its failure will lead to automatic unit shutdown, thus affecting unit operation. Simultaneously, the RHR system is also a post-accident mitigation system, belonging to the safety system category. That is, the RHR has both operational and safety functions. The probabilistic safety assessment model models both its operational and safety functions, while the forced unavailability model only needs to focus on its operational functions. In this case, the probabilistic safety assessment model needs to be modified, deleting the valve actions or system response logic related to safety functions, and retaining only the operational functions that lead to unit shutdown or power reduction. This reuse strategy makes full use of existing, validated model resources, avoids a lot of repetitive work in building fault trees from scratch, significantly improves the engineering applicability and efficiency of the method, and at the same time ensures the quality and reliability of the constructed fault tree model.

[0043] Please see Figures 1 to 20 In one embodiment of the present invention, calculating the contribution ratio of each system to the top event based on the fault tree model includes: Calculate all minimum cut sets of the top event in the fault tree model and the probability of each minimum cut set; Filter and classify the minimal cut sets according to their respective systems; For each system, its Fussel-Veseley importance is calculated, and the Fussel-Veseley importance is used as the contribution ratio of each system to be assigned to the top event.

[0044] Please see Figures 17 to 20 In one embodiment of the present invention, the minimum cut set (MCS) and its probability are first calculated: all minimum cut sets of the top event are calculated using fault tree analysis software, and the probability of occurrence of each cut set is calculated. The purpose is to transform the complex fault tree into a series of specific fault scenarios and their probabilities of occurrence. The failure probability of the basic event can be obtained by consulting a database, and the cut set probability is calculated using the failure probability of the basic event. Depending on the availability of the data source, the failure probability of the basic event can be based on historical operating data of nuclear power plants, internationally and domestically used reliability databases, etc. Specifically, for example, equipment reliability data is preferentially adopted from the "China Nuclear Power Plant Equipment Reliability Data Report". If there is no applicable data in this report, relevant data in NUREG / CR 6928-2015 is referred to. For example, data on external leakage of electric valves, manual valves, and pneumatic valves are all referred to from NUREG / CR 6928-2015, while other equipment failure data are referred to from the "China Nuclear Power Plant Equipment Reliability Data Report".

[0045] It should be noted that a minimal cut set includes one or more basic events. For a cut set containing only one basic event (i.e., a single failure), its probability is the probability of that basic event occurring itself. For a cut set containing multiple basic events, without considering common cause failure (CCF), each basic event is considered statistically independent in fault tree analysis. The probability of the minimal cut set is the product of the probabilities of all basic events in the cut set. Subsequently, the total probability of the top event is obtained by summing these cut set probabilities, and the contribution of each subsystem is calculated. Furthermore, common-cause failures can be considered to achieve more accurate calculations. Specifically, for example, a common-cause failure parameter can be introduced to decompose the total failure probability of a component into independent failure probabilities and common-cause failure event probabilities. In the fault tree model, not only are the basic independent failure events of each component included, but also the basic common-cause failure events need to be introduced to represent the risk of multiple components being affected by common causes simultaneously. When identifying the minimum cut set, pure independent failure cut sets and cut sets containing common-cause failures are obtained. When calculating the cut set probability, the probability of an independent failure cut set is still the product of the probabilities of each independent failure event within it, while the probability of a cut set containing common-cause failures is directly taken from the probability of the corresponding common-cause failure event. Finally, the contribution calculation will comprehensively reflect the contribution of independent failures and common-cause failures to the system risk, thereby affecting the subsequent margin allocation.

[0046] Please see Figures 17 to 20In one embodiment of the present invention, after the minimum cut set (MCS) and probability calculation are completed, the minimum cut sets are filtered and classified according to their respective systems. The MCS of the top event is exported, and MCSs with a 0% probability of occurrence (where the cut set accounts for 0% of the top event's occurrence probability) are deleted to focus on more important fault scenarios. The remaining MCSs are then filtered and classified according to system. During the filtering process, the system code is included in the custom event code. Based on the system code contained in the basic event code, the remaining MCSs are classified and assigned to the corresponding system. This process organizes and simplifies the MCS data, preparing for subsequent FV importance calculation and enabling fault analysis at the system level.

[0047] Please see Figures 17 to 20 In one embodiment of the present invention, for each system to be assigned, its Fussel-Veseley importance is calculated, and the Fussel-Veseley importance is used as the contribution ratio of each system to the top event. For each system, the proportions of each MCS are summed to obtain the proportion of the probability of the top event occurring in that system, which is the FV importance. The definition of Fussel-Veseley importance: The FV importance of basic event i is the ratio of the sum of the minimum cut sets including basic event i to the sum of all minimum cut sets. In this embodiment, the Fussel-Veseley importance is calculated by the following formula (1): (1) in, For the Fussel-Veseley importance of system i, It is the sum of probabilities of all minimal cut sets containing system event i. The total probability of the top event.

[0048] For each system i to be assigned, find all minimal cut sets containing events of that system, sum the probabilities of these cut sets, and calculate the contribution ratio of each system to the total probability of the top event using the formula (1) above. This step quantifies the contribution of each system to the total probability of forced unavailability of the unit, reflecting system differences. In this embodiment, Figures 17 to 20This is a list of minimum cut sets (MCS) for the top event "forced unit unavailability". MCSs numbered 1-23 each contain only one basic event; MCSs numbered 85-101 each contain two basic events; MCSs numbered 900-903 each contain three basic events; and MCSs numbered 4562-4576 each contain six basic events. This reflects the multiple faults in the fault tree model. In this embodiment, there are a total of 4576 MCSs. Cut sets numbered 102 and later have a 0% probability of occurring as the top event, so they are deleted. The remaining 101 MCSs are then categorized and calculated by system, and the resulting proportions are shown in Table 1. This calculation process provides a precise quantitative indicator to measure the relative importance of each system to the total risk of forced unit unavailability. Since this importance calculation is derived from a fault tree model that includes all single and multiple fault scenarios, its allocation basis is comprehensive and objective. It should be noted that the list of minimum cut sets and their probabilities are analyzed and calculated based on the actual design of the unit. The attached figures and the table below show only partial data of one embodiment. For different unit designs, the list of minimum cut sets and probabilities obtained by software analysis and calculation will also be different.

[0049] Table 1 shows the distribution and percentage of MCSs contributing to the top event.

[0050] Please see Figures 1 to 20 In one embodiment of the present invention, in step S300, the margin allocation value of each system to be allocated is calculated according to the contribution ratio using the following formula (2): (2) in, Assign a value to the margin of system i. For the total forced unavailability time margin, This represents the contribution ratio of system i to the top event.

[0051] This allocation is primarily based on systems that contribute significantly to forced unavailability of the unit. Their failures typically have a substantial impact on unit operation. Therefore, allocating them with longer forced unavailability margins aligns with practical logic and ensures reasonable utilization of the margins, balancing unit economics. Fully utilizing the forced unavailability time margin allows for a reduction in the reliability requirements of some systems, achieving an optimal balance between economy and reliability in system design. This step enables precise quantitative allocation of the forced unavailability time margin. This allocation method reflects multiple failures, ensuring that multiple failures (typically with extremely low probability but identifiable by fault trees) are represented in the allocation. It also reflects system differences, allocating margins differently based on the actual contribution (FV importance) of each system to the top event, making the allocation results more consistent with the actual risk of the system. It ensures that a relatively small proportion of the forced unavailability time margin is accurately and reasonably allocated to systems contributing to risk (including those contributing through low-probability multiple failure events). Thus, the final allocation result fully utilizes the margins and accurately reflects the actual risk level of each system, providing a reliable and economical basis for system design.

[0052] Please see Figures 1 to 20 In one embodiment of the present invention, in step S400, the final forced unavailability time index of each system to be allocated is obtained by adding the preliminary allocation value and the margin allocation value of each system to be allocated. Based on the PAA calculation result and the secondary allocation result, the optimal allocation of the forced unavailability index can be achieved. Specifically, the contribution ratio of system i to the top event is denoted as A. i Let B be the forced unavailability time margin, let Ci be the forced unavailability time allocated to system i based on the forced unavailability time margin (i.e., the margin allocation value), and let D be the forced unavailability time calculated by system i through PAA. i The forced unavailability time ultimately allocated to system i is denoted as E. i Then C i =B×A i E i =C i +D i , i=1, 2, 3…n. Specifically, assuming a margin B=5 hours, the calculation results are shown in Table 2.

[0053] Table 2. Forced Unavailability Time Margin Allocation Table for Each System to be Assigned

[0054] Understandably, a single failure refers to an independent failure of a single device or system. Its probability of occurrence is relatively high, and it is the most common and primary cause of forced unit shutdown or functional loss. Multiple failures refer to the simultaneous or sequential failure of two or more independent devices or systems. According to reliability theory, the probability of independent events occurring simultaneously is the product of the probabilities of each event; therefore, its probability is usually extremely low, belonging to low-probability events, and its contribution to forced unit unavailability is relatively small. Figures 17 to 20 It can also be seen that multiple failures contribute relatively little to the top event. Since one of the advantages of fault tree models is their ability to represent multiple failures, and the forced unavailability time margin of the unit is relatively small relative to the total forced unavailability time, this precisely demonstrates the rationality of allocating the smaller proportion of forced unavailability time margin using fault tree models. Specifically, the smaller proportion of forced unavailability time margin is allocated to multiple failures (including minimal cut sets composed of individual failures) that contribute less to the top event. For the larger proportion of forced unavailability time, the PAA method is used to fully leverage its advantages. This method can consider both unit unavailability caused by random single equipment failures and dual or multiple equipment failures; it ensures a reasonable balance between the forced unavailability of the unit and the design of each system to be allocated, and it makes the system's forced unavailability time requirements conform to the actual reliability level of the system, thereby improving the unit's economy. In practical implementation, the fault tree model can borrow the PSA model, and the FMEA analysis process is also readily available (a result of PAA), which greatly reduces the workload of fault tree modeling. The calculation process of importance is also relatively simple. For the allocation of forced unavailable time margin, the workload is not large and quantitative allocation data can be obtained. Accurate and effective secondary allocation can be achieved through simple steps and calculations.

[0055] Please see Figures 1 to 20This invention also proposes a forced unavailability index allocation system for generating units, including a preliminary allocation module, a judgment and evaluation module, a margin allocation module, and a final allocation module. The preliminary allocation module identifies and filters out systems that may affect unit availability and initially allocates the forced unavailability index to each system to obtain preliminary allocation values. The judgment and evaluation module accumulates the preliminary allocation values ​​of all systems to determine if there is a forced unavailability time margin. If so, it constructs a fault tree model of forced unavailability and calculates the contribution ratio of each system to the top event based on the fault tree model. The margin allocation module calculates the margin allocation value for each system based on the contribution ratio of the forced unavailability time margin. The final allocation module adds the preliminary allocation value and the margin allocation value of each system to obtain the final forced unavailability time index for each system. This system materializes the above process into a series of functional modules, achieving standardization, automation, and systematization of forced unavailability index allocation. Each module has a clear division of labor and works collaboratively, ensuring the accuracy and consistency of the method execution, significantly improving the efficiency of allocation work, and reducing uncertainty and errors caused by human factors.

[0056] Please see Figures 1 to 20 The present invention also proposes an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the unit forced unavailability index allocation method as described in any of the above embodiments.

[0057] In summary, the forced unavailability index allocation method, system, and equipment of this invention combine the macro-level preliminary allocation capability of PAA with the refined advantages of FTA in identifying and quantifying multiple failures. PAA is used to handle the larger proportion of forced unavailability time, while FTA, combined with FV importance, is used to handle and quantify the smaller proportion of forced unavailability time margin. It can clearly reflect multiple failure paths, allocating the forced unavailability time margin to these low-probability but potentially existing fault combinations, reflecting the rationality and refinement of the allocation. The allocation is more comprehensive and in-depth, and more in line with the actual operating conditions of the unit. FV importance directly quantifies the contribution ratio of each system to the probability of the top event, providing a solid quantitative basis for allocation and ensuring that the allocation results can truly reflect the differences and criticality between systems, making resource allocation more targeted. Through the construction of fault trees and the calculation of minimum cut sets and FV importance, a complete process from qualitatively identifying fault modes to quantitatively assessing their impact is realized, making allocation decisions more scientific and data-driven. This method has a clear process and sufficient evidence. It not only simplifies the analysis steps, but also guides the system design to achieve the best balance between reliability and economy through the precise allocation of indicators, thereby effectively improving the overall competitiveness and operational efficiency of the unit.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

[0059] Throughout this description, numerous specific details, such as examples of components and / or methods, are provided to provide a complete understanding of embodiments of the invention. However, those skilled in the art will recognize that embodiments of the invention may be practiced without one or more of these specific details or by other devices, systems, components, methods, parts, materials, components, etc. In other instances, well-known structures, materials, or operations have not been specifically shown or described in detail to avoid obscuring aspects of embodiments of the invention.

[0060] Throughout this specification, the terms "an embodiment," "embodiment," or "specific embodiment" refer to a particular feature, structure, or characteristic described in connection with an embodiment that is included in at least one embodiment of the invention, but not necessarily in all embodiments. Therefore, the various representations of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different places throughout the specification do not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic of any specific embodiment of the invention can be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein may be based on the teachings herein and will be considered part of the spirit and scope of the invention.

[0061] It should also be understood that one or more of the elements shown in the figures may be implemented in a more separate or more integrated manner, or may even be removed because they are inoperable in certain circumstances or provided because they may be useful for a particular application.

[0062] Furthermore, unless otherwise expressly stated, any arrows in the accompanying drawings should be considered illustrative only and not limiting. Additionally, unless otherwise stated, the term "or" as used herein is generally intended to mean "and / or". Where a term is anticipated to provide a separation or combination capability that is unclear, a combination of components or steps will also be considered as indicated.

[0063] As used herein and throughout the claims below, unless otherwise specified, “a” and “the” include the plural references. Similarly, as used herein and throughout the claims below, unless otherwise specified, “in” means “in” and “on”.

[0064] The above description of the embodiments shown in this invention (including the content set forth in the abstract of the specification) is not intended to be an exhaustive enumeration or to limit the invention to the precise forms disclosed herein. Although specific embodiments and examples of the invention have been described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the invention, as will be recognized and understood by those skilled in the art. As indicated, these modifications can be made to the invention in accordance with the above description of the embodiments described herein, and such modifications will be within the spirit and scope of the invention.

[0065] This document has generally described the systems and methods in detail to aid in understanding the invention. Furthermore, various specific details have been set forth to provide a general understanding of embodiments of the invention. However, those skilled in the art will recognize that embodiments of the invention can be practiced without one or more specific details, or using other means, systems, accessories, methods, components, materials, parts, etc. In other instances, well-known structures, materials, and / or operations have not been specifically shown or described in detail to avoid obscuring aspects of embodiments of the invention.

[0066] Therefore, although the invention has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are also within the scope of the foregoing disclosure, and it should be understood that in some cases, certain features of the invention may be adopted without departing from the scope and spirit of the invention and without corresponding use of other features. Thus, many modifications can be made to adapt a particular environment or material to the essential scope and spirit of the invention. The invention is not intended to be limited to the specific terminology used in the following claims and / or the specific embodiments disclosed as the best mode for carrying out the invention, but the invention will include any and all embodiments and equivalents falling within the scope of the appended claims. Therefore, the scope of the invention will be defined only by the appended claims.

Claims

1. A method for allocating forced unavailability indicators for generating units, characterized in that, include: Identify and filter out the systems to be allocated that may affect the availability of the unit, and initially allocate the forced unavailability index of the unit to each of the systems to be allocated to obtain an initial allocation value. Accumulate the initial allocation values ​​of all systems to be allocated, determine whether there is a forced unavailability time margin, and if so, construct a fault tree model of forced unavailability of the unit, and calculate the contribution ratio of each system to be allocated to the top event based on the fault tree model. The forced unavailability time margin is used to calculate the margin allocation value for each of the systems to be allocated based on the contribution ratio. The final forced unavailability time index of each system to be allocated is obtained by adding the initial allocation value and the margin allocation value of each system to be allocated.

2. The method for allocating forced unavailability indicators for generating units according to claim 1, characterized in that, The process of identifying and filtering out systems that may affect unit availability and initially allocating the forced unavailability index of the unit to each of the systems to obtain an initial allocation value includes: The forced unavailability index of the units is initially allocated using a probabilistic availability assessment method to obtain the initial allocation value of each of the systems to be allocated.

3. The method for allocating forced unavailability indicators for generating units according to claim 1, characterized in that, The steps of accumulating the preliminary allocation values ​​of all systems to be allocated, determining whether there is a forced unavailability time margin, and if so, constructing a fault tree model for forced unit unavailability, and calculating the contribution ratio of each system to be allocated to the top event based on the fault tree model include: Accumulate the initial allocation values ​​of all systems to be allocated to determine whether the unit availability target has been achieved. If not, then modify the design scheme based on probabilistic safety evaluation and analysis; If so, determine whether there is a forced unavailability time margin; If not, the calculation ends, and the preliminary allocation value is the final forced unavailability time indicator; If so, a fault tree model for the forced unavailability of the unit is constructed, and the contribution ratio of each system to be assigned to the top event is calculated based on the fault tree model.

4. The method for allocating forced unavailability indicators for generating units according to claim 1, characterized in that, The fault tree model for forcing the unit to become unavailable includes: Determining forced unavailability of the unit as the top event; Automatic shutdown, manual shutdown, and power reduction are used as intermediate events, and are connected to the top event via a logic OR gate. The intermediate events are further decomposed into individual system failure events; For each system failure event, a subsystem fault tree is constructed with the system failure as the top event, and then decomposed layer by layer to the basic events of the equipment failure mode.

5. The method for allocating forced unavailability indicators for generating units according to claim 1, characterized in that, The calculation of the contribution ratio of each system to the top event based on the fault tree model includes: Calculate all minimum cut sets of the top event in the fault tree model and the probability of each minimum cut set; The minimum cut sets are then filtered and classified according to their respective systems; For each system, its Fussel-Veseley importance is calculated, and the Fussel-Veseley importance is used as the contribution ratio of each system to be assigned to the top event.

6. The method for allocating forced unavailability indicators for generating units according to claim 5, characterized in that, The probability of the minimal cut set is the product of the probabilities of all basic events occurring in the cut set, and the minimal cut set includes one or more basic events.

7. The method for allocating forced unavailability indicators for generating units according to claim 5, characterized in that, The Fussel-Veseley importance is calculated using the following formula: in, For the Fussel-Veseley importance of system i, It is the sum of probabilities of all minimal cut sets containing system event i. The total probability of the top event.

8. The method for allocating forced unavailability indicators for generating units according to claim 1, characterized in that, The margin allocation value for each of the systems to be allocated is calculated based on the contribution ratio using the following formula: in, Assign a value to the margin of system i. For the total forced unavailability time margin, This represents the contribution ratio of system i to the top event.

9. A forced unavailability index allocation system for generating units, characterized in that, include: The preliminary allocation module is used to identify and filter out the systems to be allocated that may affect the availability of the unit, and to initially allocate the forced unavailability index of the unit to each of the systems to be allocated to obtain a preliminary allocation value. The judgment and evaluation module is used to accumulate the preliminary allocation values ​​of all systems to be allocated, determine whether there is a forced unavailability time margin, and if so, construct a fault tree model of forced unavailability of the unit, and calculate the contribution ratio of each system to be allocated to the top event based on the fault tree model. The margin allocation module is used to calculate the margin allocation value for each of the systems to be allocated based on the contribution ratio of the forced unavailability time margin. The final allocation module is used to add the initial allocation value and the margin allocation value of each system to be allocated to obtain the final forced unavailability time index of each system to be allocated.

10. An electronic device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the unit forced unavailability index allocation method as described in any one of claims 1 to 9.

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