Nuclear power system equipment nuclear safety performance evaluation method

Abstract

The invention relates to a nuclear power system equipment nuclear safety performance evaluation method, which comprises the following steps of: obtaining a complete system list of a power plant, and screening the system list according to a nuclear safety function correlation condition to obtain a function list meeting a nuclear safety function requirement; classifying the function list based on the operation state to obtain a category system classification of the nuclear safety related system equipment meeting the operation state classification standard; performing performance index making according to the category classification to obtain a performance index making result of the nuclear safety related system equipment; and performing nuclear safety performance evaluation on the nuclear safety related equipment in the preset time period according to the performance index formulating result to obtain a nuclear safety performance evaluation result in the preset time. Through systematic equipment screening and classification, scientific and reasonable performance index formulating and dynamic performance evaluation based on actual operation data, the nuclear safety performance of the nuclear safety related equipment in the preset time period is evaluated; and refined evaluation of nuclear power plant system equipment nuclear safety performance is realized.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant system equipment safety management technology, and more specifically, to a method for assessing the nuclear safety performance of nuclear power system equipment. Background Technology

[0002] To effectively evaluate the nuclear safety performance of nuclear power units, 23 performance indicators were developed with reference to the Reactor Oversight Procedure (ROP), including "7000 Critical Hour Unplanned Emergency Shutdown (Manual and Automatic) (IE01)," "7000 Critical Hour Unplanned Nuclear Power Change (IE03)," and "Unplanned Complex Emergency Shutdown (IE04)." However, most of these indicators are at a relatively macro level and are difficult to effectively guide the management of specific systems and equipment in the daily management of nuclear power plants. Furthermore, the National Nuclear Safety Administration currently only sets mitigation system performance indicators for some critical systems, with limited coverage, failing to encompass a large number of general but equally important nuclear safety-related systems and equipment, and thus failing to meet the increasingly sophisticated needs of current nuclear safety management. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for evaluating the nuclear safety performance of nuclear power system equipment, addressing the shortcomings of existing technologies in meeting the requirements of lean management.

[0004] The technical solution adopted by this invention to solve its technical problem is: to construct a method for evaluating the nuclear safety performance of nuclear power system equipment, the method comprising the following steps:

[0005] Step S1: Obtain the complete system list of the power plant, and filter the system list according to the nuclear safety function relevance conditions to obtain a functional list that meets the nuclear safety function requirements;

[0006] Step S2: The function list is classified based on the operating status to obtain the category classification of nuclear safety-related system equipment that conforms to the operating status classification standard;

[0007] Step S3: Based on the category classification, performance indicators are formulated to obtain the performance indicator formulation results for nuclear safety-related system equipment;

[0008] Step S4: Based on the performance index formulation results, evaluate the nuclear safety performance of nuclear safety-related equipment within a preset time period to obtain the nuclear safety performance assessment results within the preset time period.

[0009] In one embodiment, step S1 includes:

[0010] Step S1.1: Based on the nuclear safety function relevance conditions, the system list is filtered to obtain a preliminary nuclear safety function system list;

[0011] Step S1.2: Based on the preliminary nuclear safety function system list, the system list obtained by sorting through the preset control and protection system logic diagram is used to obtain the extended nuclear safety function system list;

[0012] Step S1.3: Integrate and streamline the extended nuclear safety functional system list and the preliminary nuclear safety functional system list to obtain the functional list.

[0013] In one embodiment, in step S1, the nuclear safety function relevance condition includes at least one of the following conditions: 1) the system equipment performs reactivity control functions; 2) the system equipment performs core cooling functions; 3) the system equipment performs radioactive containment functions; 4) the system performs accident mitigation functions; 5) the system equipment provides necessary support for nuclear safety functions.

[0014] In one embodiment, step S1.1 includes:

[0015] By consulting the design manuals of each system to identify its functions, the system equipment responsible for reactivity control, core cooling, and radioactive containment was selected, resulting in the first list.

[0016] By reviewing the accident handling strategies and implementation paths involved in the power plant accident procedures, the system equipment responsible for accident mitigation is selected and added to the first list to obtain the second list;

[0017] A correlation analysis of support and being supported is performed on the systems in the second list, and the supporting or supported systems corresponding to the systems in the second list are added to the second list to obtain a third list, wherein the third list is the preliminary nuclear safety functional system list.

[0018] In one embodiment, step S1.2 includes:

[0019] The power plant's preset control and protection system logic diagram is consulted, and all signals that may trigger reactor protection shutdown and turbine generator tripping, as well as the system equipment that generates these signals, are identified to form a fourth list, which is an extended nuclear safety function system list.

[0020] In one embodiment, step S1.3 includes: integrating and functionally reviewing the extended nuclear safety function system list to obtain the function list, which includes:

[0021] The third and fourth lists are merged and deduplicated to obtain the final system list, wherein;

[0022] For each system in the final system list, add functions to that system to obtain a first function list;

[0023] The first functional list is filtered by preset application criteria to obtain the objects for setting system equipment nuclear safety performance indicators, thus forming the second functional list.

[0024] In one embodiment, in step S1, the step of filtering the first functional list through preset application criteria to obtain the objects for defining system equipment nuclear safety performance indicators and forming a second functional list includes:

[0025] The second functional list is obtained by filtering the contents of the first functional list that meet at least one application criterion, wherein the application criterion includes at least: 1) the equipment is a safety-related system equipment; 2) the equipment can mitigate accidents or transients; 3) the equipment can be used for accident procedures; 4) the equipment will interfere with the performance of safety-related SSCs; 5) the equipment can cause emergency reactor shutdown or safety system action.

[0026] In one embodiment, step S2 includes:

[0027] Step S2.1: Calculate the risk importance of the function using the PSA model to obtain the risk importance result;

[0028] Step S2.2: Obtain the operating status under normal functioning conditions;

[0029] Step S2.3: Classify the second function list according to the risk importance result and the operating status to obtain the category classification.

[0030] In one embodiment, step S2.1 includes:

[0031] The process analysis method was used to determine the list of main active equipment for implementing each function in the second functional list;

[0032] Establish a mapping relationship between the basic events in the PSA model and the devices in the main active equipment list;

[0033] The risk is considered high if it falls under at least one of the following three categories; otherwise, it is considered low.

[0034] The FV value of the device is calculated using the PSA model based on the mapping relationship, and the FV value reaches a corresponding preset threshold.

[0035] The RAW value of the device is calculated using the PSA model based on the mapping relationship, and the RAW value reaches a preset threshold.

[0036] The PSA model is used to derive a list of all cut sets, which are then sorted in descending order based on their contribution to the total core melt frequency or the early large-scale radioactive release frequency. The resulting list of cut sets is then selected from those with the highest contribution percentages.

[0037] In one embodiment, calculating the FV value of the device using the PSA model based on the mapping relationship includes:

[0038] In the PSA model, the probability of occurrence of the basic event corresponding to the device is set to 0. The PSA model calculation engine is run to obtain the calculation result Qi. The result Q of the baseline model is subtracted from Qi and then divided by the result Q of the baseline model to obtain the FV value of the device.

[0039] In one embodiment, calculating the RAW value of the device using the PSA model based on the mapping relationship includes:

[0040] In the PSA model, the probability of occurrence of the basic event corresponding to the device is set to 1. The PSA model calculation engine is run to obtain the calculation result Qi. The calculation result Qi is divided by the result Q of the baseline model to obtain the RAW value of the device.

[0041] In one embodiment, the category classification includes: a first category of high risk importance and standby, a second category of high risk importance and operational, a third category of low risk importance and standby, and a fourth category of low risk importance and operational; step S3 includes:

[0042] Step S3.1: Develop reliability indicators based on the system equipment of the first category, the second category, and the third category. The reliability indicators are the total number of failures allowed within a preset period of time.

[0043] Step S3.2: Develop availability metrics based on the first category of system devices and the second category of system devices. The availability metrics are the total number of hours during which the device is allowed to be unavailable within a preset number of years.

[0044] In one embodiment, step S3.1 includes:

[0045] For system equipment of the first category and system equipment of the third category, query the expected start-up failure probability p of the equipment in the power plant PSA model; assume that the number of start-up failures n within a preset period of time; count the number of times N of the standby system needs to be started in the power plant operation program, mainly the periodic test program; calculate the probability of n failures in N demands using a preset first formula, and take the number of failures n corresponding to the probability being greater than the first cutoff value as the reliability index of the equipment.

[0046] For equipment not modeled in the PSA model, the reliability index of the equipment is obtained by multiplying the number of times the backup system needs to be started within a preset period (N) by a preset ratio and taking the integer value.

[0047] In one embodiment, the preset first formula includes:

[0048]

[0049] Where P(n,N,p) is the probability of n failures occurring in N startups, N is the number of startups required for the device within the preset lifespan, n is the number of possible failures within the preset lifespan, and P is the failure probability.

[0050] In one embodiment, step S3.1 further includes:

[0051] For the second category of system equipment, the expected operational failure probability λ of the equipment is queried in the power plant PSA model. Assuming that the equipment will fail n times within a preset period, the probability of it failing n times within the preset period is calculated using the preset operational failure probability formula. At the same time, the number of failures n corresponding to the probability being greater than the second cutoff value is used as the reliability index of the equipment.

[0052] In one embodiment, step S3.2 includes:

[0053] For the equipment already modeled in the power plant PSA model:

[0054] Query the unavailability parameters of this equipment in the power plant PSA model;

[0055] The total available time for the system during the power plant's operation procedures is statistically analyzed.

[0056] The reliability index of the device is obtained by multiplying the unavailability parameter and the total time length.

[0057] Or / and, for unmodeled equipment in the power plant PSA model:

[0058] The total available time for the system during the power plant's operation procedures is statistically analyzed.

[0059] The reliability index of the device is calculated by multiplying the total available time of the system within a preset period by a preset ratio and taking the integer value.

[0060] In one embodiment, step S4 includes:

[0061] Step S4.1: Obtain equipment failure information that occurs within a preset time period, and statistically evaluate the number of functional failures of the equipment. Compare the results using the reliability indicators to obtain the failure count evaluation results. The failure count evaluation results are used to evaluate whether the nuclear safety performance of the equipment meets the standards.

[0062] Step 4.2: Obtain equipment failure information that occurs within a preset time period, statistically analyze and evaluate the equipment downtime, compare it with the availability index, obtain downtime evaluation results, and evaluate whether the nuclear safety performance of the equipment meets the standards based on the downtime evaluation results.

[0063] In one embodiment, step S4.1 includes:

[0064] Obtain equipment failure information that occurred at the power plant in the month to be tested, and classify and organize it systematically based on the list of major active equipment;

[0065] And based on the second list, determine whether the fault has caused the function to fail;

[0066] If it is a functional failure, trace back a preset number of years from the time of equipment failure and count the number of functional failures recorded during the period.

[0067] Compare the number of functional failures with the reliability index;

[0068] If the reliability index is exceeded, a root cause analysis will be performed on the device, and additional measures will be taken, while additional monitoring targets and monitoring cycles will be set.

[0069] If the reliability index is less than the stated reliability index, then the device is considered to require no additional measures.

[0070] In one embodiment, the root cause analysis of the device and the implementation of additional measures, along with the setting of additional monitoring targets and monitoring cycles, include:

[0071] Conduct a root cause analysis of the device to determine the specific cause of the functional failure.

[0072] Based on the results of the root cause analysis, develop and implement additional measures to address the issues leading to functional failure.

[0073] In one embodiment, step S4.2 includes:

[0074] Obtain information on equipment failures that occurred at the power plant in the month to be tested, and / or system equipment isolation information, and / or test information, and organize them according to system categories;

[0075] And based on the second list, determine whether the corresponding fault, and / or isolation, and / or test has caused functional failure;

[0076] If a function fails, the duration of the failure will be recorded.

[0077] Additionally, it retrieves the time when a device becomes unavailable and traces back a preset number of years to calculate the device's unavailability time.

[0078] Compare the unavailability time with the availability metric;

[0079] If the value exceeds the availability index, a root cause analysis will be performed on the device, and additional measures will be taken, while additional monitoring targets and monitoring cycles will be set.

[0080] If the availability index is less than the stated availability index, then no additional measures are required for the device.

[0081] The beneficial effects of this invention are that this application relates to a method for evaluating the nuclear safety performance of nuclear power system equipment, comprising the following steps: obtaining a complete system list of the power plant, and screening the system list according to nuclear safety functional relevance conditions to obtain a functional list that meets nuclear safety functional requirements; classifying the functional list based on operating status to obtain a category classification of nuclear safety-related system equipment that meets the operating status classification standard; formulating performance indicators based on the category classification to obtain the performance indicator formulation results for nuclear safety-related system equipment; and evaluating the nuclear safety performance of nuclear safety-related equipment within a preset time period based on the performance indicator formulation results to obtain the nuclear safety performance evaluation results within the preset time period. This invention, through systematic equipment screening and classification, scientific and reasonable performance indicator formulation, and dynamic performance evaluation based on actual operating data, achieves refined evaluation of the nuclear safety performance of nuclear power plant system equipment and effectively improves the scientificity and effectiveness of nuclear safety management in nuclear power plants. Attached Figure Description

[0082] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0083] Figure 1 This is a flowchart illustrating the nuclear safety performance evaluation method for nuclear power system equipment according to the present invention;

[0084] Figure 2 This invention provides the criteria and screening process for the nuclear safety performance evaluation method of nuclear power system equipment.

[0085] Figure 3 This is the classification process of the nuclear safety performance evaluation method for nuclear power system equipment of the present invention. Detailed Implementation

[0086] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by related similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0087] like Figure 1 As shown, Figure 1 A flowchart illustrating the nuclear safety performance evaluation method for nuclear power system equipment according to the present invention.

[0088] The technical solution adopted in this invention is: to provide a method for evaluating the nuclear safety performance of nuclear power system equipment, comprising the following steps:

[0089] Step S1: Obtain the complete system list of the power plant, and filter the system list according to the nuclear safety function relevance conditions to obtain a functional list that meets the nuclear safety function requirements;

[0090] In this step, it should be noted that a complete system list of the power plant is obtained through the power plant's operational process management information system. Subsequently, this system list is screened based on nuclear safety function relevance criteria, identifying systems and equipment responsible for nuclear safety functions such as reactivity control, core cooling, radioactive containment, and accident mitigation, forming the first functional list. Further, the first functional list is screened using a criterion-based screening method to obtain the second functional list used for performance indicator formulation.

[0091] Step S2: The function list is classified based on the operating status to obtain the category classification of nuclear safety-related system equipment that conforms to the operating status classification standard;

[0092] In this step, it should be noted that the system devices in the first function are classified according to their status during normal operation (operation or standby) and their risk importance (high or low). This results in four categories of devices. This classification is based on the FV value, RAW value, and cutset contribution calculated using the PSA model, combined with the device's functional role in the system.

[0093] Step S3: Based on the category classification, performance indicators are formulated to obtain the performance indicator formulation results for nuclear safety-related system equipment;

[0094] In this step, differentiated reliability and availability performance indicators are established based on equipment category: Reliability Indicators: Applicable to Class 1, 2, and 3 equipment, representing the number of failures the equipment is allowed to experience within a preset year. For equipment modeled in the PSA model, calculations are based on failure probability and operational requirements; for unmodeled equipment, a preset percentage of the required number of failures or operating time is used as the indicator. This preset percentage can be 5%. Availability Indicators: Applicable to Class 1 and 2 equipment, representing the total time the equipment is allowed to be unavailable within a preset period. For equipment modeled in the PSA model, calculations are based on unavailability and system availability time; for unmodeled equipment, a preset percentage of the required system availability time is used as the indicator.

[0095] Step S4: Based on the performance index formulation results, evaluate the nuclear safety performance of nuclear safety-related equipment within a preset time period to obtain the nuclear safety performance assessment results within the preset time period.

[0096] It should be noted that, within a preset time period (e.g., monthly, quarterly, or annually), information on faults, isolations, and tests of nuclear safety-related equipment is collected to determine whether they have led to functional failure or unavailability. The number of equipment failures and downtime during this period are statistically analyzed and compared with established performance indicators: if the number of failures or downtime is less than the indicator, the equipment performance is considered good; if it exceeds the indicator, root cause analysis is conducted, corrective measures are formulated, and monitoring targets and cycles are set. For equipment with recurring failures, the progress of root cause resolution is closely monitored to ensure risk elimination. Furthermore, a retrospective evaluation is conducted every two years, using the PSA model to calculate indicators such as ΔCDF, ΔLERF, ICCDP, and ICLERP caused by equipment failures or unavailability, and combining this with a maintenance strategy evaluation matrix to optimize power plant operation and maintenance strategies.

[0097] In one embodiment, step S1 includes: step S1.1: filtering the system list according to the nuclear safety function relevance conditions to obtain a preliminary nuclear safety function system list;

[0098] Furthermore, in step S1, the nuclear safety function relevance conditions include at least one of the following conditions: 1) the system equipment performs reactivity control functions; 2) the system equipment performs core cooling functions; 3) the system equipment performs radioactive containment functions; 4) the system performs accident mitigation functions; 5) the system equipment provides necessary support for nuclear safety functions.

[0099] Step S1.1 includes: by querying the description of the system function in the design manual of each system, the system equipment responsible for reactivity control, core cooling and radioactive containment is screened out to obtain a first list; the accident handling strategies and implementation paths involved in the power plant accident procedures are sorted out, the system equipment responsible for accident mitigation is screened out and added to the first list to obtain a second list;

[0100] A correlation analysis of support and being supported is performed on the systems in the second list, and the supporting or supported systems corresponding to the systems in the second list are added to the second list to obtain a third list, wherein the third list is the preliminary nuclear safety functional system list.

[0101] It should be noted that the specific screening process is as follows: The design manuals of each system are consulted to identify systems and equipment responsible for reactivity control, core cooling, and radioactive containment, forming the first list; The accident handling strategies and implementation paths involved in the power plant's accident procedures are reviewed to identify systems and equipment responsible for accident mitigation functions, which are then added to the first list, forming the second list; Correlation analysis of support and supported systems is conducted on the systems in the second list to identify and provide key support functions such as water, gas, and power sources, which are then added to the second list, forming the third list, i.e., the preliminary nuclear safety functional system list.

[0102] Step S1.2: Based on the preliminary nuclear safety function system list, the system list obtained by sorting through the preset control and protection system logic diagram is used to obtain the extended nuclear safety function system list;

[0103] Step S1.2 includes: querying the power plant's preset control and protection system logic diagram, sorting out all signals that may trigger reactor protection shutdown and turbine generator tripping, as well as the system equipment that generates these signals, to form a fourth list, wherein the fourth list is an extended nuclear safety function system list.

[0104] It should be noted that, based on the preliminary list of nuclear safety functional systems, the power plant's control and protection system logic diagrams are further consulted to identify all signals that could potentially trigger reactor protection shutdowns and turbine generator trips, along with their source systems, forming a fourth list, namely the expanded list of nuclear safety functional systems.

[0105] Step S1.3: Integrate and streamline the extended nuclear safety functional system list and the preliminary nuclear safety functional system list to obtain the functional list.

[0106] Step S1.3 includes: integrating and sorting out the functions of the extended nuclear safety function system list to obtain the function list includes: merging and deduplicating the third list and the fourth list to obtain the final system list, wherein: for the systems in the final system list, adding functions for the system to obtain the first function list; filtering the first function list through preset application criteria to obtain the objects for the formulation of nuclear safety performance indicators of system equipment, forming the second function list.

[0107] like Figure 2 As shown, further, in step S1, the step of filtering the first functional list by preset application criteria to obtain the objects for the system equipment nuclear safety performance indicators and forming the second functional list includes: filtering the contents of the list that meet at least one application criterion from the first functional list to obtain the second functional list, wherein the application criteria include at least: 1) the equipment is a safety-related system equipment, 2) the equipment can mitigate accidents or transients, 3) the equipment can be used for accident procedures, 4) the equipment will hinder the execution of safety-related SSCs, and 5) the equipment can cause emergency reactor shutdown or safety system action.

[0108] It should be noted that the third list (preliminary list of nuclear safety functional systems) and the fourth list (extended list of nuclear safety functional systems) are merged and deduplicated to obtain the final system list. Subsequently, the main functions of each system in the final system list are listed in detail to form the first functional list.

[0109] like Figure 2 As shown, the first functional list is screened according to preset application criteria, and system equipment that meets at least one of the following conditions is selected as the object of nuclear safety performance index formulation, forming the second functional list (i.e., the final functional list): the equipment is a safety-related system equipment; the equipment can mitigate accidents or transients; the equipment is used in accident procedures; the failure of the equipment would prevent safety-related systems, structures, or components (SSCs) from performing their safety functions; the failure or malfunction of the equipment may cause an emergency shutdown, shutdown, or trigger safety system actions. This invention comprehensively identifies nuclear safety-related system equipment through a multi-dimensional screening mechanism, ensuring that the screening process is systematic, scientific, and traceable, providing a solid foundation for equipment classification and performance evaluation, improving the pertinence and effectiveness of nuclear safety management, and supporting the quantification and transparency of supervision.

[0110] In one embodiment, step S2: the function list is classified based on the operating status to obtain the category classification of nuclear safety related system equipment that conforms to the operating status classification standard;

[0111] It should be noted that step S2 includes:

[0112] Step S2.1: Calculate the risk importance of the function using the PSA model to obtain the risk importance result;

[0113] Step S2.2: Obtain the operating status under normal functioning conditions;

[0114] Step S2.3: Classify the second function list according to the risk importance result and the operating status to obtain the category classification.

[0115] In one embodiment, step S2.1 includes: applying process analysis to determine a list of main active equipment that implements each function in the second functional list; establishing a mapping relationship between basic events in the PSA model and equipment in the list of main active equipment; if at least one of the following three conditions is met, the risk importance is high; otherwise, the risk importance is low: calculating the FV value of the equipment using the PSA model based on the mapping relationship, and the FV value reaches a corresponding preset threshold; calculating the RAW value of the equipment using the PSA model based on the mapping relationship, and the RAW value reaches a preset threshold.

[0116] The PSA model is used to derive a list of all cut sets, which are then sorted in descending order based on their contribution to the total core melt frequency or the early large-scale radioactive release frequency. The resulting list of cut sets is then selected from those with the highest contribution percentages.

[0117] Furthermore, the step of calculating the FV value of the device using the PSA model based on the mapping relationship includes:

[0118] In the PSA model, the probability of occurrence of the basic event corresponding to the device is set to 0. The PSA model calculation engine is run to obtain the calculation result Qi. The result Q of the baseline model is subtracted from Qi and then divided by the result Q of the baseline model to obtain the FV value of the device.

[0119] Furthermore, the step of calculating the RAW value of the device using the PSA model based on the mapping relationship includes:

[0120] In the PSA model, the probability of occurrence of the basic event corresponding to the device is set to 1. The PSA model calculation engine is run to obtain the calculation result Qi. The calculation result Qi is divided by the result Q of the baseline model to obtain the RAW value of the device.

[0121] Furthermore, the category classification includes: the first category is high risk importance and standby, the second category is high risk importance and in operation, the third category is low risk importance and standby, and the fourth category is low risk importance and in operation;

[0122] like Figure 3As shown, in a specific embodiment, the invention utilizes a power plant probabilistic risk analysis model (PSA model) to systematically assess the risk importance of equipment. Existing PSA models for power plants include internal event level 1 / 2 PSA models under power and shutdown conditions, and PSA models for internal fire, earthquake, flooding, and strong winds under power conditions. To improve computational efficiency, the cutoff value selected during calculation is at least 5 orders of magnitude lower than the baseline PSA model result to reduce the number of minimum cut sets and basic events. The specific calculation process is as follows: First, the main active equipment implementing each function in Function List B is determined using process analysis, forming Equipment List 1; second, a mapping relationship is established between the basic events in the PSA model and the equipment in Equipment List 1; then, the Fussell-Vesely value (FV value) and RiskAchievementWorth value (RAW value) of the equipment are calculated respectively: For the FV value, the probability of occurrence of the corresponding basic event for that equipment is set to 0, the PSA model is run to obtain the result Qi, and (Q-Qi) / Q is calculated. If the FV value is greater than 0.005, then... This device is classified as a high-risk importance device. For the RAW value, the probability of the basic event corresponding to this device is set to 1. The PSA model is run to obtain Qi, and Qi / Q is calculated. If the RAW value is greater than 2, the device is considered a high-risk importance device. Next, all cut sets are exported and sorted according to their contribution to the core meltdown frequency (CDF) or early large radioactive release frequency (LERF). Devices included in the top 90% of contributing cut sets are also identified as high-risk importance devices. Finally, the device lists obtained above are merged to form a high-risk importance device list, and the remaining devices are low-risk importance devices. Based on this, all functions in Function List B, such as... Figure 3 As shown, the analysis is conducted from two dimensions: first, the level of risk importance of the function (high or low); and second, whether the function is in an operational or standby state during normal operation. Based on these two dimensions, functions are divided into four categories: Category 1: high risk importance and standby; Category 2: high risk importance and operational; Category 3: high risk importance and operational; and Category 4: low risk importance and operational. This method achieves a scientific classification of the risk importance of nuclear safety-related equipment, providing a reliable basis for subsequent performance indicator development and nuclear safety performance evaluation.

[0123] Step S3: Formulate performance indicators according to the category classification to obtain the performance indicator formulation results of nuclear safety related system equipment; Step S3 includes: Step S3.1: Formulate reliability indicators based on the first category, the second category and the third category of system equipment, wherein the reliability indicator is the total number of failures allowed within a preset period of time.

[0124] Further, step S3.1 includes: for the first category of system equipment and the third category of system equipment, querying the expected start-up failure probability p of the equipment in the power plant PSA model; assuming that the number of start-up failures n will occur within a preset period; statistically analyzing the number N of start-up requirements for the backup system in the power plant operation program, mainly the periodic test program; calculating the probability of n failures in N requirements using a preset first formula, and using the number of failures n corresponding to the probability being greater than a first cutoff value as the reliability index of the equipment; for equipment not modeled in the PSA model, multiplying the number of start-up requirements N of the backup system within the preset period by a preset ratio, and taking the integer as the reliability index of the equipment.

[0125] Furthermore, the preset first formula includes:

[0126]

[0127] Where P(n,N,p) is the probability of n failures occurring in N startups, N is the number of startups required for the device within the preset lifespan, n is the number of possible failures within the preset lifespan, and P is the failure probability.

[0128] Furthermore, step S3.1 also includes:

[0129] For the second category of system equipment, the expected operational failure probability λ of the equipment is queried in the power plant PSA model. Assuming that the equipment will fail n times within a preset period, the probability of it failing n times within the preset period is calculated using the preset operational failure probability formula. At the same time, the number of failures n corresponding to the probability being greater than the second cutoff value is used as the reliability index of the equipment.

[0130] Furthermore, the preset operational failure probability formula includes:

[0131]

[0132] Where P(n) is the probability of operational failure, n is the number of possible failures within the preset time limit, and λ is the expected startup failure probability.

[0133] Step S3.2: Develop availability metrics based on the first category of system devices and the second category of system devices. The availability metrics are the total number of hours during which the device is allowed to be unavailable within a preset number of years.

[0134] Furthermore, step S3.2 includes: for equipment already modeled in the power plant PSA model: querying the unavailability parameter of the equipment in the power plant PSA model; calculating the total available time for the system in the power plant operation program; multiplying the unavailability parameter and the total available time to obtain the reliability index of the equipment; or / and, for equipment not modeled in the power plant PSA model: calculating the total available time for the system in the power plant operation program; multiplying the total available time required by the system within a preset period by a preset ratio, and taking the integer as the reliability index of the equipment.

[0135] In one specific embodiment, differentiated performance indicators are formulated for four types of equipment. Specifically, for Class 1 (high risk importance and standby) and Class 2 (high risk importance and operational) equipment, two types of performance indicators are formulated: reliability and availability. For Class 3 (low risk importance and standby) equipment, only reliability indicators are formulated, and availability indicators are not formulated. For Class 4 (low risk importance and operational) equipment, no additional reliability or availability indicators are formulated.

[0136] Regarding the formulation of reliability performance indicators, for Category 1 (high risk importance and standby), Category 2 (high risk importance and operational), and Category 3 (low risk importance and standby) equipment, a maximum number of failures allowed to occur within two years is set. The specific method is as follows:

[0137] For Class 1 and Class 3 standby equipment, firstly, the expected start-up failure probability p of the equipment is queried in the power plant PSA model. Assuming the number of start-up failures n within two years is 0, 1, 2, 3, or 4, the number of times the equipment needs to be started during periodic testing and other operational procedures, N, is counted. The probability P of n failures occurring in N demand scenarios is calculated using a preset first formula, where the preset first formula is the preset start-up failure probability formula. A cutoff value of 10% is set, meaning the largest n value where P(n) is greater than 10% is selected as the reliability performance index of the equipment. For equipment not modeled in the PSA model, 5% (rounded to the nearest integer) of the number of times the equipment needs to be started N within two years is used as its reliability index. The categories can also be classified according to actual conditions, with the number of categories potentially being 4, 5, or 6, etc. The cutoff value can be set according to actual conditions, such as 10%, 20%, or other reasonable values, which will not be elaborated further below.

[0138] For the second type of operating equipment, query the expected failure probability λ of the equipment in the PSA model. Assuming that the number of failures n within two years is 0, 1, 2, 3, or 4, calculate the probability P of n failures within two years using the preset failure probability formula. Similarly, set a 10% cutoff value and select the largest n value where P(n) is greater than 10% as the reliability performance index.

[0139] Regarding the establishment of availability performance metrics, for both Category 1 and Category 2 devices, a total allowable downtime (in hours) over two years is defined. The specific method is as follows:

[0140] For devices that have been modeled in the PSA model, query the unavailability parameter of the device and calculate the total time required for system availability. Multiply the two together to obtain the availability performance index.

[0141] For devices not modeled in the PSA model, the statistical system requires the total available time and uses 5% of that time (rounded to the nearest integer) as the availability performance metric.

[0142] Through the above methods, this invention enables the differentiation, quantification, and scientific formulation of performance indicators for equipment of different importance, providing a reliable basis for subsequent nuclear safety performance evaluation and improving the pertinence and effectiveness of nuclear power plant equipment management.

[0143] Step S4: Based on the performance index formulation results, evaluate the nuclear safety performance of nuclear safety-related equipment within a preset time period to obtain the nuclear safety performance assessment results within the preset time period.

[0144] Step S4 includes: Step S4.1: Obtain equipment failure information that occurs within a preset time period, and statistically evaluate the number of functional failures of the equipment, compare them using the reliability index, obtain the failure number evaluation result, and use the failure number evaluation result to evaluate whether the nuclear safety performance of the equipment meets the standard.

[0145] Furthermore, in one embodiment, step S4.1 includes: acquiring equipment failure information of the power plant in the month to be tested, and classifying and organizing it systematically based on the list of major active equipment; determining whether the failure has caused functional failure based on the second list; if it is a functional failure, counting back a preset number of years from the time of the equipment failure, and counting the number of functional failures recorded during the period; comparing the number of functional failures with the reliability index; if it is greater than the reliability index, performing a root cause analysis on the equipment and taking additional measures, while setting additional monitoring targets and monitoring cycles; if it is less than the reliability index, considering that the equipment does not require additional measures.

[0146] Furthermore, the root cause analysis of the device and the implementation of additional measures, along with the setting of additional monitoring targets and monitoring cycles, include: conducting a root cause analysis of the device to determine the specific causes of functional failure; and, based on the results of the root cause analysis, formulating and implementing additional measures to resolve the problems leading to functional failure.

[0147] Step 4.2: Obtain equipment failure information that occurs within a preset time period, statistically analyze and evaluate the equipment downtime, compare it with the availability index, obtain downtime evaluation results, and evaluate whether the nuclear safety performance of the equipment meets the standards based on the downtime evaluation results.

[0148] Furthermore, step S4.2 includes:

[0149] Acquire equipment failure information, and / or system equipment isolation information, and / or test information that occurred at the power plant in the month to be tested, and organize them according to system classification; and determine whether the corresponding failure, and / or isolation, and / or test caused functional failure based on the second list; if it is a functional failure, then calculate the duration of this functional failure; and, obtain the equipment unavailability point and trace back a preset number of years to calculate the equipment unavailability time; compare the unavailability time with the availability index; if it is greater than the availability index, then perform root cause analysis on the equipment and take additional measures, while setting additional monitoring targets and monitoring cycles; if it is less than the availability index, then it is considered that no additional measures need to be taken for the equipment.

[0150] In a specific embodiment, firstly, for the equipment in the first list of key active equipment, monthly information on equipment failures, isolations, and tests occurring during power plant operation is collected and categorized by system. Then, based on the system function requirements of the second functional list, it is determined whether the aforementioned failures, isolations, or tests have led to functional failure. If a functional failure is determined, a functional failure event is recorded, and the number of functional failures A of the equipment during this period is counted two years prior to the time of the failure. A is compared with the equipment's reliability performance indicators: if A is less than the indicator, it indicates that the equipment performance is good and no additional measures are needed; if A is greater than the indicator, it is considered that the equipment performance does not meet the requirements, and a root cause analysis needs to be conducted (refer to the Nuclear Power Plant Event Root Cause Analysis Guidelines issued by the National Nuclear Safety Administration), and corrective measures are formulated, while monitoring targets and cycles are set. Within the monitoring cycle, if the equipment's operating status meets the targets, it can be removed from the key monitoring items and routine monitoring resumes; if the root cause analysis shows that the equipment failure is recurring, it indicates that the root cause of the failure has not been completely eliminated, posing a greater potential risk, and the progress of the handling should be closely monitored to eliminate the hidden danger as soon as possible.

[0151] Simultaneously, a similar evaluation is conducted for equipment unavailability: monthly data on equipment failures, isolation, and testing is collected to determine if they lead to functional malfunctions. If a malfunction occurs, the duration of unavailability is recorded, and the cumulative unavailability time B is calculated two years prior to that point. B is then compared to the equipment's availability performance index: if B is less than the index, the equipment performance is good; if B is greater than the index, root cause analysis is required, corrective measures are developed, and monitoring targets and cycles are set. If the equipment status meets the standards during the monitoring period, normal monitoring can be resumed; if malfunctions recur, close attention and expedited handling are necessary.

[0152] In addition to monthly safety assessments and corrective actions, this methodology includes a retrospective overall assessment every two years. Specifically, for the equipment in the first list, the PSA model is used to calculate the core damage frequency increment (ΔCDF) and early large radioactive release frequency increment (ΔLERF) caused by functional failure and unavailability. Combined with the duration of failure / unavailability, the cumulative core damage probability increment (ICCDP) and cumulative early large radioactive release probability increment (ICLERP) are calculated. The above risk calculation results are combined with the following evaluation matrix table to guide the adjustment of power plant operation and maintenance strategies:

[0153]

[0154]

[0155] The nuclear safety performance evaluation method for nuclear power system equipment provided by this invention can effectively and accurately evaluate the nuclear safety performance level of nuclear power plant system equipment. It can be applied to nuclear safety supervision, equipment management, and maintenance effectiveness evaluation in nuclear power plants. Based on the results of this evaluation and analysis method, power plants can identify weaknesses, formulate targeted corrective actions, rationally allocate resources, and improve the overall nuclear safety level of the nuclear power plant.

[0156] 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 for those skilled in the art, free combinations of the above technical features and various modifications and improvements can be made without departing from the concept of the present invention, and these all 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 evaluating the nuclear safety performance of nuclear power system equipment, characterized in that, The method includes the following steps: Step S1: Obtain the complete system list of the power plant, and filter the system list according to the nuclear safety function relevance conditions to obtain a functional list that meets the nuclear safety function requirements; Step S2: The function list is classified based on the operating status to obtain the category classification of nuclear safety-related system equipment that conforms to the operating status classification standard; Step S3: Based on the category classification, performance indicators are formulated to obtain the performance indicator formulation results for nuclear safety-related system equipment; Step S4: Based on the performance index formulation results, evaluate the nuclear safety performance of nuclear safety-related equipment within a preset time period to obtain the nuclear safety performance assessment results within the preset time period.

2. The method for assessing the nuclear safety performance of nuclear power system equipment according to claim 1, characterized in that, Step S1 includes: Step S1.1: Based on the nuclear safety function relevance conditions, the system list is filtered to obtain a preliminary nuclear safety function system list; Step S1.2: Based on the preliminary nuclear safety function system list, the system list obtained by sorting through the preset control and protection system logic diagram is used to obtain the extended nuclear safety function system list; Step S1.3: Integrate and streamline the extended nuclear safety functional system list and the preliminary nuclear safety functional system list to obtain the functional list.

3. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 2, characterized in that, In step S1, the nuclear safety function relevance conditions include at least one of the following conditions: 1) the system equipment undertakes reactivity control functions; 2) the system equipment undertakes core cooling functions; 3) the system equipment undertakes radioactive containment functions; 4) the system undertakes accident mitigation functions; 5) the system equipment provides necessary support for nuclear safety functions.

4. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 3, characterized in that, Step S1.1 includes: By consulting the design manuals of each system to identify its functions, the system equipment responsible for reactivity control, core cooling, and radioactive containment was selected, resulting in the first list. By reviewing the accident handling strategies and implementation paths involved in the power plant accident procedures, the system equipment responsible for accident mitigation is selected and added to the first list to obtain the second list; A correlation analysis of support and being supported is performed on the systems in the second list, and the supporting or supported systems corresponding to the systems in the second list are added to the second list to obtain a third list, wherein the third list is the preliminary nuclear safety functional system list.

5. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 4, characterized in that, Step S1.2 includes: The power plant's preset control and protection system logic diagram is consulted, and all signals that may trigger reactor protection shutdown and turbine generator tripping, as well as the system equipment that generates these signals, are identified to form a fourth list, which is an extended nuclear safety function system list.

6. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 5, characterized in that, In step S1.3, the integration and functional review of the extended nuclear safety function system list yields the following functional list: The third and fourth lists are merged and deduplicated to obtain the final system list, wherein; For each system in the final system list, add functions to that system to obtain a first function list; The first functional list is filtered by preset application criteria to obtain the objects for setting system equipment nuclear safety performance indicators, thus forming the second functional list.

7. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 6, characterized in that, In step S1, the process of filtering the first functional list using preset application criteria to obtain the objects for defining the system equipment nuclear safety performance indicators and forming the second functional list includes: The second functional list is obtained by filtering the contents of the first functional list that meet at least one application criterion, wherein the application criterion includes at least: 1) the equipment is a safety-related system equipment; 2) the equipment can mitigate accidents or transients; 3) the equipment can be used for accident procedures; 4) the equipment will interfere with the performance of safety-related SSCs; 5) the equipment can cause emergency reactor shutdown or safety system action.

8. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 7, characterized in that, Step S2 includes: Step S2.1: Calculate the risk importance of the function using the PSA model to obtain the risk importance result; Step S2.2: Obtain the operating status under normal functioning conditions; Step S2.3: Classify the second function list according to the risk importance result and the operating status to obtain the category classification.

9. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 8, characterized in that, Step S2.1 includes: The process analysis method was used to determine the list of main active equipment for implementing each function in the second functional list; Establish a mapping relationship between the basic events in the PSA model and the devices in the main active equipment list; The risk is considered high if it falls under at least one of the following three categories; otherwise, it is considered low. The FV value of the device is calculated using the PSA model based on the mapping relationship, and the FV value reaches a corresponding preset threshold. The RAW value of the device is calculated using the PSA model based on the mapping relationship, and the RAW value reaches a preset threshold. The PSA model is used to derive a list of all cut sets, which are then sorted in descending order based on their contribution to the total core melt frequency or the early large-scale radioactive release frequency. The resulting list of cut sets is then selected from those with the highest contribution percentages.

10. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 9, characterized in that, The step of calculating the FV value of the device using the PSA model based on the mapping relationship includes: In the PSA model, the probability of the occurrence of the basic event corresponding to this device is set to 0. Running the PSA model calculation engine yields the calculation result Q. i Subtract Q from the result Q of the baseline model. i Then divide by the result Q of the benchmark model to obtain the FV value of the device.

11. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 9, characterized in that, The step of calculating the device's RAW value using the PSA model based on the mapping relationship includes: In the PSA model, the probability of the occurrence of the basic event corresponding to this device is set to 1. Running the PSA model calculation engine yields the calculation result Q. i The calculation result Q i Divide the result Q from the baseline model to obtain the RAW value of the device.

12. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 9, characterized in that, The category classification includes: Category 1: High risk importance and on standby; Category 2: High risk importance and in operation; Category 3: Low risk importance and on standby; Category 4: Low risk importance and in operation; Step S3 includes: Step S3.1: Develop reliability indicators based on the system equipment of the first category, the second category, and the third category. The reliability indicators are the total number of failures allowed within a preset period of time. Step S3.2: Develop availability metrics based on the first category of system devices and the second category of system devices. The availability metrics are the total number of hours during which the device is allowed to be unavailable within a preset number of years.

13. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 12, characterized in that, Step S3.1 includes: For system equipment of the first category and system equipment of the third category, the expected start-up failure probability p of the equipment is queried in the power plant PSA model; it is assumed that the number of start-up failures n within a preset period is n; the number of times the backup system needs to be started in the power plant operation program, mainly the periodic test program, is N; the probability P(n,N,p) of n failures in N demands is calculated using a preset first formula, and the number of failures n corresponding to the probability P(n,N,p) being greater than the first cutoff value is taken as the reliability index of the equipment; For equipment not modeled in the PSA model, the reliability index of the equipment is obtained by multiplying the number of times the backup system needs to be started within a preset period (N) by a preset ratio and taking the integer value.

14. The method for assessing the nuclear safety performance of nuclear power system equipment according to claim 12, characterized in that, The preset first formula includes: Where P(n,N,p) is the probability of n failures occurring in N startups, N is the number of startups required for the device within the preset lifespan, n is the number of possible failures within the preset lifespan, and P is the failure probability.

15. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 13, characterized in that, Step S3.1 further includes: For the second category of system equipment, the expected operational failure probability λ of the equipment is queried in the power plant PSA model. Assuming that the equipment will fail n times within a preset period, the probability P(n) of the equipment failing n times within the preset period is calculated using the preset operational failure probability formula. At the same time, the probability P(n) is greater than the number of failures n corresponding to the second cutoff value, which is taken as the reliability index of the equipment.

16. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 12, characterized in that, Step S3.2 includes: For the equipment already modeled in the power plant PSA model: Query the unavailability parameters of this equipment in the power plant PSA model; The total available time for the system during the power plant's operation procedures is statistically analyzed. The reliability index of the device is obtained by multiplying the unavailability parameter and the total time length. Or / and, for unmodeled equipment in the power plant PSA model: The total available time for the system during the power plant's operation procedures is statistically analyzed. The reliability index of the device is calculated by multiplying the total available time of the system within a preset period by a preset ratio and taking the integer value.

17. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 12, characterized in that, Step S4 includes: Step S4.1: Obtain equipment failure information that occurs within a preset time period, and statistically evaluate the number of functional failures of the equipment. Compare the results using the reliability indicators to obtain the failure count evaluation results. The failure count evaluation results are used to evaluate whether the nuclear safety performance of the equipment meets the standards. Step 4.2: Obtain equipment failure information that occurs within a preset time period, statistically analyze and evaluate the equipment downtime, compare it with the availability index, obtain downtime evaluation results, and evaluate whether the nuclear safety performance of the equipment meets the standards based on the downtime evaluation results.

18. The method for assessing the nuclear safety performance of nuclear power system equipment according to claim 17, characterized in that, Step S4.1 includes: Obtain equipment failure information that occurred at the power plant in the month to be tested, and classify and organize it systematically based on the list of major active equipment; And based on the second list, determine whether the fault has caused the function to fail; If it is a functional failure, trace back a preset number of years from the time of equipment failure and count the number of functional failures recorded during the period. Compare the number of functional failures with the reliability index; If the reliability index is exceeded, a root cause analysis will be performed on the device, and additional measures will be taken, while additional monitoring targets and monitoring cycles will be set. If the reliability index is less than the stated reliability index, then the device is considered to require no additional measures.

19. The method for assessing the nuclear safety performance of nuclear power system equipment according to claim 18, characterized in that, The root cause analysis of the device and the implementation of additional measures, along with the setting of additional monitoring targets and monitoring cycles, include: Conduct a root cause analysis of the device to determine the specific cause of the functional failure. Based on the results of the root cause analysis, develop and implement additional measures to address the issues leading to functional failure.

20. The method for evaluating the nuclear safety performance of nuclear power system equipment according to claim 17, characterized in that, Step S4.2 includes: Obtain information on equipment failures that occurred at the power plant in the month to be tested, and / or system equipment isolation information, and / or test information, and organize them according to system categories; And based on the second list, determine whether the corresponding fault, and / or isolation, and / or test has caused functional failure; If a function fails, the duration of the failure will be recorded. Additionally, it retrieves the time when a device becomes unavailable and traces back a preset number of years to calculate the device's unavailability time. Compare the unavailability time with the availability metric; If the value exceeds the availability index, a root cause analysis will be performed on the device, and additional measures will be taken, while additional monitoring targets and monitoring cycles will be set. If the availability index is less than the stated availability index, then no additional measures are required for the device.

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