Safety classification method for control accessories of a nuclear power plant pneumatic control valve

Abstract

The application provides a safety grading method for a control accessory of a nuclear power plant pneumatic control valve, the pneumatic control valve is a main valve, the control accessory is an auxiliary component arranged in a pneumatic control loop of the pneumatic control valve, and the method comprises the following steps: obtaining at least one failure mode of the control accessory and function information of the control accessory in the pneumatic control loop, performing failure influence analysis according to the failure mode and the function information, and obtaining an influence result of the control accessory failure on the execution of a nuclear safety function of the main valve; obtaining nuclear safety data and equipment attribute data of the main valve, determining a safety level, a seismic category and an identification requirement level of the control accessory according to the nuclear safety data, the equipment attribute data and the influence result of the main valve; wherein the nuclear safety data comprises a seismic category and an electrical / instrument control safety level of the main valve; and the equipment attribute data comprises live information and safety function execution information. The safety grading of the control accessory is realized by combining the failure influence analysis with the multi-dimensional attribute data of the equipment.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant equipment safety technology, and more specifically, to a safety classification method for pneumatic control valve accessories in nuclear power plants. Background Technology

[0002] In the safety management of nuclear power plants, to ensure that items reliably perform nuclear safety functions (such as reactivity control, core residual heat removal, and radioactive material containment) under design conditions, and to optimize cost input, it is essential to conduct reasonable safety classifications of systems, components, and structures. In existing technologies, engineering design institutes have established clear classification systems (such as RCC-P, RCC-M, and RCC-E standards) for main equipment in the nuclear island (such as pumps and valve bodies). This system primarily targets pressure-bearing mechanical equipment or electrical / instrumentation control equipment.

[0003] However, existing classification standards for control accessories of pneumatic control valves (such as pressure reducing valves, lubricators, and pneumatic positioners) have significant gaps and difficulties. These accessories are mostly non-pressure-bearing, purely mechanical components, making it impossible to directly apply the safety classifications of mechanical equipment (such as safety levels 1, 2, and 3) or completely equate them to the classifications of electrical / instrumentation control equipment (such as level 1E). This lack of classification results in a lack of unified and scientific basis for field equipment management, procurement, and qualification. Managing all accessories according to the highest safety requirements would significantly increase unnecessary costs; improper management could lead to potential risks, as the failure of critical accessories could affect the nuclear safety functions of the main valve to which they belong. Therefore, the field needs a logically clear and highly operable safety classification method specifically for such control accessories. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a safety classification method for control accessories of pneumatic control valves in nuclear power plants, addressing the aforementioned deficiencies of existing technologies. The technical solution adopted by this invention to solve its technical problem is: to provide a safety classification method for control accessories of pneumatic control valves in nuclear power plants, wherein the pneumatic control valve is the main valve, and the control accessory is an auxiliary component configured in its pneumatic control circuit; the method includes: Step S1: Obtain at least one fault mode of the control accessory and the functional information of the control accessory in the pneumatic control loop; perform fault impact analysis based on the fault mode and the functional information to obtain the impact of the control accessory fault on the main valve's nuclear safety function. Step S2: Obtain the nuclear safety data and equipment attribute data of the main valve. Based on the nuclear safety data of the main valve, the equipment attribute data, and the impact results, determine the safety level, seismic resistance category, and qualification requirement level of the control accessory. The nuclear safety data includes the seismic resistance category and electrical / instrumentation safety level of the main valve. The equipment attribute data includes energized information and execution safety function information used to characterize whether the main valve performs nuclear safety functions.

[0005] Preferably, in step S1, obtaining the fault mode includes: Obtain the type information of the control accessory, and match at least one fault mode corresponding to the control accessory from a preset fault mode database based on the type information; wherein, the type information is used to characterize the device type of the control accessory.

[0006] Preferably, the fault impact analysis includes: Based on the functional information and the at least one fault mode, determine the actual state of the main valve under each fault mode; The actual state is compared with the preset fail-safe position of the main valve; If the actual state is inconsistent with the preset fail-safe position, the result is that the failure of the control accessory will affect the main valve's nuclear safety function. If the actual state is consistent with the preset fail-safe position, then the result is obtained that the failure of the control accessory does not affect the main valve's execution of nuclear safety functions.

[0007] Preferably, determining the actual state of the main valve under each of the fault modes includes: For each of the aforementioned failure modes, based on the functional information and the failure mode, a first impact result of the control accessory itself failing under that failure mode is determined; Based on the first impact result, determine the second impact result of the fault mode on the pneumatic control loop; Based on the second impact result, the final state of the main valve under the fault mode is determined, and the final state is taken as the actual state of the main valve.

[0008] Preferably, in step S2, determining the safety level, seismic resistance category, and assessment requirement level of the control accessory based on the nuclear safety data of the main valve, equipment attribute data, and the impact results includes: Based on the electrical information, determine whether the control accessory is a live device; If the control accessory is an electrical device, then the safety level, seismic resistance category, and assessment requirement level of the control accessory are determined based on the executed safety function information, the impact result, and the nuclear safety data of the main valve. If the control accessory is a non-electrical device, then the safety level, seismic resistance category, and qualification requirement level of the control accessory are determined based on the executed safety function information and the nuclear safety data of the main valve.

[0009] Preferably, if the control accessory is an electrical device, then based on the executed safety function information, the impact result, and the nuclear safety data of the main valve, the safety level, seismic resistance category, and assessment requirement level of the control accessory are determined, including: Based on the information regarding the execution of safety functions, it is determined whether the main valve is performing a nuclear safety function; If the main valve performs nuclear safety functions; When the impact result is that the failure of the control accessory will affect the main valve's nuclear safety function, the safety level of the control accessory is 1E, the seismic resistance category is seismic resistance class 1, and the qualification requirement level is determined according to the electrical / instrumentation qualification level of the main valve; When the effect result is that the failure of the control accessory does not affect the main valve from performing nuclear safety functions, the safety level of the control accessory is NC level, the seismic resistance category is seismic resistance class 1, and the assessment requirement level is determined according to the electrical / instrumentation assessment level of the main valve.

[0010] Preferably, if the control accessory is an electrical device, determining the safety level, seismic resistance category, and assessment requirement level of the control accessory based on the executed safety function information, the impact result, and the nuclear safety data of the main valve further includes: Obtain the execution safety function information, and determine whether the main valve is performing a nuclear safety function based on the execution safety function information; If the main valve does not perform nuclear safety functions: When the effect result is that the failure of the control accessory does not affect the main valve from performing nuclear safety functions, the safety level of the control accessory is NC, the seismic resistance category is NO, and the qualification requirement level is NO; When the impact result is that the failure of the control accessory will affect the main valve's nuclear safety function, then there is no corresponding safety classification.

[0011] Preferably, if the control accessory is a non-electrical device, then based on the executed safety function information, the impact result, and the nuclear safety data of the main valve, the safety level, seismic resistance category, and assessment requirement level of the control accessory are determined, including: Based on the information regarding the execution of safety functions, it is determined whether the main valve is performing a nuclear safety function; If the main valve performs nuclear safety functions, determine whether the seismic resistance category of the main valve is seismic resistance class 1A; When the seismic resistance category of the main valve is seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class 1, the qualification requirement level is NO, and a mechanical qualification test instruction is generated. When the seismic resistance category of the main valve is not seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class NO, and the assessment requirement level is NO.

[0012] Preferably, if the control accessory is a non-electrical device, determining the safety level, seismic resistance category, and assessment requirement level of the control accessory based on the executed safety function information, the impact result, and the nuclear safety data of the main valve further includes: Based on the information regarding the execution of safety functions, it is determined whether the main valve is performing a nuclear safety function; If the main valve does not perform nuclear safety functions, determine whether the seismic resistance category of the main valve is seismic resistance class 1A; When the seismic resistance category of the main valve is seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class 1, the qualification requirement level is NO, and a mechanical qualification test instruction is generated. When the seismic resistance category of the main valve is not seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class NO, and the assessment requirement level is NO.

[0013] Preferably, the mechanical identification test instructions include thermal aging test instructions, mechanical vibration test instructions, and seismic resistance test instructions.

[0014] The beneficial effect of this invention is that the safety classification method for pneumatic control valve accessories in nuclear power plants includes: Step S1: acquiring at least one fault mode of the control accessory and its functional information in the pneumatic control loop; performing fault impact analysis based on the fault mode and the functional information to obtain the impact result of the control accessory fault on the main valve's nuclear safety function; Step S2: acquiring nuclear safety data and equipment attribute data of the main valve; determining the safety level, seismic resistance category, and qualification requirement level of the control accessory based on the main valve's nuclear safety data, the equipment attribute data, and the impact result; wherein, the nuclear safety data includes the main valve's seismic resistance category and electrical / instrumentation safety level; the equipment attribute data includes energized information and execution safety function information used to characterize whether the main valve performs nuclear safety functions. This invention combines fault impact analysis with multi-dimensional equipment attribute data to achieve safety classification of control accessories. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a logic flowchart of the safety classification method for pneumatic control valve accessories in nuclear power plants; Figure 2 This is a flowchart illustrating the specific judgment logic of the safety classification method for pneumatic control valve accessories in nuclear power plants. Detailed Implementation

[0016] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the invention are now described in detail with reference to the accompanying drawings. In the following description, specific details such as particular structures and techniques are set forth for illustrative purposes and not for limitation, so as to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0017] like Figure 1 As shown, Figure 1 This is a logic flowchart of the safety classification method for pneumatic control valves in nuclear power plants.

[0018] The present invention provides a safety classification method for control accessories of pneumatic control valves in nuclear power plants. The pneumatic control valve is the main valve, and the control accessories are auxiliary components configured in its pneumatic control circuit. The method includes: Step S1: Obtain at least one fault mode of the control accessory and the functional information of the control accessory in the pneumatic control loop. Perform fault impact analysis based on the fault mode and functional information to obtain the impact of the control accessory fault on the main valve's nuclear safety function. In this step, failure modes represent typical failure modes that control accessories may experience, and functional information characterizes the role of the control accessories in the pneumatic control loop. Failure impact analysis can then be performed using the failure modes and functional information to determine the extent to which accessory failure affects the main valve's nuclear safety functions. Failure impact analysis can be implemented using one or more of the following methods: FMEA (Failure Mode and Effects Analysis), RCA (Root Cause Analysis), PSA (Probabilistic Safety Assessment), or FMECA (Failure Mode, Effects, and Criticality Analysis).

[0019] Step S2: Obtain the nuclear safety data and equipment attribute data of the main valve. Based on the nuclear safety data, equipment attribute data, and impact results of the main valve, determine the safety level, seismic resistance category, and qualification requirement level of the control accessories. The nuclear safety data includes the seismic resistance category and electrical / instrumentation safety level of the main valve. The equipment attribute data includes energized information and execution safety function information used to characterize whether the main valve performs nuclear safety functions.

[0020] In this step, it should be noted that the nuclear safety data comes from the official classification document of the main valve, and the equipment attribute data comes from the design document of the main valve. The nuclear safety data includes the main valve's seismic resistance category, electrical / instrumentation safety level, and qualification level; the seismic resistance category includes seismic class 1 or NO, the electrical / instrumentation safety level includes 1E or NC (Non-Safety Class), and the qualification level includes K1, K2, K3, or NO. The energization information in the equipment attribute data is used to distinguish whether the control accessory is energized or non-energized, and the safety function execution information is used to determine whether the main valve performs nuclear safety functions. Based on the combination of nuclear safety data, equipment attribute data, and impact results, and according to the preset classification judgment rules, the safety level, seismic resistance category, and qualification requirement level of the control accessory can be determined.

[0021] Preferably, in step S1, obtaining the fault mode includes: obtaining the type information of the control accessory, and matching at least one fault mode corresponding to the control accessory from a preset fault mode database according to the type information; wherein, the type information is used to characterize the device type of the control accessory.

[0022] It should be noted that the pre-set failure mode database stores typical failure modes corresponding to different types of control accessories. This database can be constructed using the FMEA (Failure Mode and Effects Analysis) method, which systematically identifies the possible failure modes and their causes for each type of control accessory, forming a structured failure mode knowledge base. During the construction process, historical operating data, equipment design documents, and the experience and knowledge of domain experts can be collected as inputs for FMEA analysis. In practice, the failure modes identified by the FMEA method can be supplemented and improved by combining equipment schematic diagrams, manufacturer failure data, power plant experience feedback, operation and maintenance records, etc., to comprehensively list the failure modes.

[0023] In one embodiment, the typical failure modes corresponding to different types of control accessories include, but are not limited to: electrical failure modes (coil open circuit, coil short circuit, loose wiring, power loss), mechanical failure modes (jamming, wear, blockage), pneumatic / hydraulic failure modes (internal leakage, external leakage, diaphragm rupture, spring failure), and signal failure modes (feedback error, signal drift, false triggering, failure to trigger). Since typical failure modes covering multiple dimensions such as electrical, mechanical, pneumatic, and signal are preset, this method can effectively cover various potential failure scenarios of nuclear power plant control accessories under long-term service and harsh operating conditions.

[0024] Preferably, the fault impact analysis includes: determining the actual state of the main valve under each fault mode based on functional information and at least one fault mode; and comparing the actual state with the preset fault-safe position of the main valve. If the actual state is inconsistent with the preset fail-safe position, the result is that the failure of the control accessory will affect the main valve's nuclear safety function; if the actual state is consistent with the preset fail-safe position, the result is that the failure of the control accessory will not affect the main valve's nuclear safety function.

[0025] It should be noted that the preset fail-safe position is the safe state that the main valve should be in when performing nuclear safety functions, as determined during the design phase, including failure to open or failure to close. The actual state is the final physical state of the main valve under a certain failure mode, including fully open, fully closed, intermediate position, or uncontrollable fluctuation. By comparing the two, it can be determined whether the failure of the accessory will cause the main valve to be unable to perform the intended nuclear safety functions. If the two are inconsistent, the failure of the accessory will affect the nuclear safety functions; if the two are consistent, the failure of the accessory will not affect the nuclear safety functions. This step directly compares the actual state after the failure with the safety position required by the design, establishing a direct mathematical / physical judgment threshold between accessory failure and loss of nuclear safety functions. This specific and quantifiable comparison rule transforms the originally vague safety impact assessment into a logical judgment, effectively avoiding the subjectivity of human experience judgment.

[0026] Preferably, determining the actual state of the main valve under each fault mode includes: for each fault mode, determining the first impact result of the failure of the control accessory itself under the fault mode based on the functional information and the fault mode; determining the second impact result of the fault mode on the pneumatic control circuit based on the first impact result; determining the final state of the main valve under the fault mode based on the second impact result, and taking the final state as the actual state of the main valve.

[0027] It should be noted that the failure of the control accessory itself refers to the malfunction of its internal critical components (such as the coil and valve core of a solenoid valve, or the diaphragm and spring of a pressure reducing valve). The first impact result is the direct manifestation of the accessory's own failure, such as "the solenoid valve coil being open-circuited, causing the valve core to be unable to switch"; the second impact result is the effect of the accessory failure on the pneumatic control circuit or logic circuit, such as "loss of pressure in the control air circuit"; the final state is the final physical state of the main valve after the accessory failure, such as "the main valve returning to the fail-safe position (fully closed) under air loss due to the spring". Therefore, starting from the accessory's own failure, its impact on the control circuit and the main valve is deduced layer by layer, forming a complete causal chain, ensuring the completeness and accuracy of the impact analysis. Through the above layer-by-layer deduction from the first impact result to the second impact result and then to the final state, the actual state of the main valve under each failure mode can be determined, providing a basis for subsequent comparison of the actual state with the preset fail-safe position.

[0028] like Figure 2 As shown, preferably, in step S2, the safety level, seismic resistance category, and qualification requirement level of the control accessory are determined based on the nuclear safety data of the main valve, the equipment attribute data, and the impact results. This includes: determining whether the control accessory is a live device based on the energized information; if the control accessory is an energized device, then the safety level, seismic resistance category, and qualification requirement level of the control accessory are determined based on the executed safety function information, the impact results, and the nuclear safety data of the main valve; if the control accessory is a non-energized device, then the safety level, seismic resistance category, and qualification requirement level of the control accessory are determined based on the executed safety function information and the nuclear safety data of the main valve.

[0029] Specifically, the above-mentioned determination process first categorizes control accessories into two main types based on energized information: energized equipment and non-energized equipment, and then executes different classification logics for each category. Energized equipment, which includes electrical instrumentation accessories (such as solenoid valves, positioners, and limit switches), requires comprehensive consideration of the executed safety function information and the impact on the outcome. Non-energized equipment, which includes mechanical accessories (such as pressure reducing valves, airlocks, lubricators, and filters), is primarily classified based on the executed safety function information and the seismic resistance category in the nuclear safety data. Through these two parallel paths, the safety level, seismic resistance category, and assessment requirement level of accessories with different attributes are determined respectively.

[0030] Preferably, if the control accessory is an electrical device, the safety level, seismic resistance category, and qualification requirement level of the control accessory are determined based on the executed safety function information, the impact result, and the nuclear safety data of the main valve. This includes: determining whether the main valve is performing a nuclear safety function based on the executed safety function information; if the main valve is performing a nuclear safety function; when the impact result is that the failure of the control accessory will affect the main valve's execution of a nuclear safety function, the safety level of the control accessory is 1E, the seismic resistance category is seismic resistance class 1, and the qualification requirement level is determined based on the main valve's electrical / instrumentation qualification level; when the impact result is that the failure of the control accessory does not affect the main valve's execution of a nuclear safety function, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class 1, and the qualification requirement level is determined based on the main valve's electrical / instrumentation qualification level.

[0031] Specifically, when the main valve served by the energized equipment performs nuclear safety functions, it indicates that the main valve belongs to nuclear safety-related equipment. In this case, if the failure of an accessory affects the main valve's performance of nuclear safety functions, the accessory must be managed according to the nuclear safety level, with a safety level of 1E and a seismic resistance category of seismic resistance category 1. The assessment requirements inherit the main valve's electrical / instrumentation assessment level (K1 / K2 / K3). If the failure of the accessory does not affect the main valve's performance of nuclear safety functions, the safety level can be downgraded to NC (nuclear island plant) / NA (non-nuclear island plant), where NA indicates Not Applicable. However, the seismic resistance category must still remain at seismic resistance category 1 to ensure the overall functional integrity of the main valve under seismic conditions. The assessment requirements level is determined based on the main valve's electrical / instrumentation assessment level. The above judgment rules ensure that accessories that do not affect safety functions are reasonably downgraded while ensuring nuclear safety, avoiding unnecessary cost investment.

[0032] Preferably, if the control accessory is an electrical device, the safety level, seismic resistance category, and qualification requirement level of the control accessory are determined based on the executed safety function information, the impact result, and the nuclear safety data of the main valve. This also includes: obtaining the executed safety function information and determining whether the main valve is performing a nuclear safety function based on the executed safety function information; if the main valve is not performing a nuclear safety function: when the impact result is that the failure of the control accessory does not affect the main valve's execution of a nuclear safety function, the safety level of the control accessory is NC, the seismic resistance category is NO, and the qualification requirement level is NO; when the impact result is that the failure of the control accessory will affect the main valve's execution of a nuclear safety function, then there is no corresponding safety classification.

[0033] Specifically, when the main valve served by the energized equipment does not perform nuclear safety functions, the main valve itself belongs to the non-safety class. If the failure of the accessory does not affect the main valve's performance of nuclear safety functions, the accessory can be managed as conventional equipment, with a safety level of NC, a seismic resistance category of NO, and an assessment requirement level of NO. If the failure of the accessory affects the main valve's performance of nuclear safety functions, since the main valve itself does not undertake nuclear safety functions, this situation should not occur in actual engineering. If it occurs, it indicates that the main valve should actually be classified as nuclear safety-related equipment. In this case, the initial classification of the main valve should be reviewed. Therefore, this scenario is defined as "no corresponding safety classification exists".

[0034] Preferably, if the control accessory is a non-energized device, the safety level, seismic resistance category, and qualification requirement level of the control accessory are determined based on the executed safety function information, the impact results, and the nuclear safety data of the main valve. This includes: determining whether the main valve is performing a nuclear safety function based on the executed safety function information; if the main valve is performing a nuclear safety function, determining whether the seismic resistance category of the main valve is seismic resistance class 1A; when the seismic resistance category of the main valve is seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class 1, and the qualification requirement level is NO, and a mechanical qualification test instruction is generated; when the seismic resistance category of the main valve is not seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class NO, and the qualification requirement level is NO.

[0035] Specifically, when the main valve served by non-electrical equipment performs nuclear safety functions and the seismic resistance category of the main valve is Class 1A, the safety level of the valve accessories is NC (nuclear island plant) / NA (non-nuclear island plant), seismic resistance category 1, and qualification level NO. However, it is necessary to ensure that the RCCE "Code for Design and Construction of Electrical Equipment in Nuclear Island" is completed and the K1 / K2 / K3 qualification tests are completed, that is, to complete the tests related to mechanical spare parts in RCCE K1 / K2 / K3 (determined according to the electrical instrumentation classification list). When the seismic resistance category of the main valve is not Class 1A, the safety level of the control accessories is NC, the seismic resistance category is seismic resistance category NO, and the qualification requirement level is NO.

[0036] It should also be noted that when the main valve served by non-energized equipment does not perform nuclear safety functions, if the main valve's seismic resistance category is Class 1A, the valve accessory safety level is NC (nuclear island plant) / NA (non-nuclear island plant), seismic resistance is Class 1, and the qualification level is NO, but it is necessary to ensure that the RCCE "Code for Design and Construction of Electrical Equipment in Nuclear Island" completes the full K1 / K2 / K3 qualification test, that is, complete the mechanical spare parts related tests in RCCE K1 / K2 / K3 (determined according to the electrical instrumentation classification list); if the main valve's seismic resistance category is not Class 1A, the valve accessory safety level is NC (nuclear island plant) / NA (non-nuclear island plant), seismic resistance is NO, and the qualification level is NO.

[0037] Preferably, if the control accessory is a non-energized device, the safety level, seismic resistance category, and qualification requirement level of the control accessory are determined based on the executed safety function information, the impact results, and the nuclear safety data of the main valve. This further includes: determining whether the main valve is performing a nuclear safety function based on the executed safety function information; if the main valve is not performing a nuclear safety function, determining whether the seismic resistance category of the main valve is seismic resistance class 1A; when the seismic resistance category of the main valve is seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class 1, and the qualification requirement level is NO, and a mechanical qualification test instruction is generated; when the seismic resistance category of the main valve is not seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class NO, and the qualification requirement level is NO.

[0038] Specifically, when the main valve served by non-electrical equipment does not perform nuclear safety functions, if the main valve's seismic resistance category is Class 1A, the valve accessory safety level is NC (nuclear island plant) / NA (non-nuclear island plant), seismic resistance is Class 1, and qualification level is NO, but it is necessary to ensure that the RCCE "Code for Design and Construction of Electrical Equipment in Nuclear Island" completes the full K1 / K2 / K3 qualification test, that is, complete the mechanical spare parts related tests in RCCE K1 / K2 / K3 (determined according to the electrical instrumentation classification list); if the main valve's seismic resistance category is not Class 1A, the valve accessory safety level is NC, seismic resistance is NO, and qualification level is NO.

[0039] Preferably, the mechanical qualification test instructions include thermal aging test instructions, mechanical vibration test instructions, and seismic resistance test instructions.

[0040] For mechanical accessories with a safety class of NC but a seismic category of 1, their qualification level is NA (Not Applicable), meaning that conventional electrical / instrumentation qualification standards do not apply, but mechanical qualification tests corresponding to the main valve's operating conditions must be completed. Mechanical qualification tests include, but are not limited to, thermal aging tests, mechanical vibration tests, and seismic tests. These tests aim to verify the mechanical integrity and operability of the accessories under normal operating conditions and seismic loads, ensuring that they maintain overall functional integrity after an earthquake.

[0041] The aforementioned mechanical qualification tests ensure the reliability of these accessories under nuclear power plant operating conditions and seismic conditions, thereby avoiding unnecessary electrical / instrumentation qualification requirements while ensuring nuclear safety, and achieving a balance between safety and economy.

[0042] In one embodiment, taking the main valve of the containment isolation valve of a nuclear power plant as an example, the filter pressure reducing valve that is matched with it is determined by the above method to be of safety level NC and seismic resistance category 1. Then, according to the above mechanical identification test instructions, thermal aging test, mechanical vibration test and seismic test are performed to verify that it can still maintain the integrity of its overall function after an earthquake.

[0043] It should be added that the complete definition of nuclear safety data in this invention includes three core classification attributes of the main valve: mechanical safety level (such as safety level 1, 2, 3, LS, or NC), seismic resistance category (such as seismic resistance class 1, which can be further subdivided into class 1I, class 1F, class 1A, or NO), and electrical / instrumentation safety level and qualification level (such as 1E corresponding to qualification levels K1, K2, K3, and NC corresponding to qualification level NO). In the failure impact analysis, the analysis is based on the nuclear power plant's Safety Analysis Report (SAR) and System Design Manual (SDM), and the preset fail-safe position is derived from the above documents. The safety level, seismic resistance category, and qualification requirement level of the control accessories obtained from the above determination are summarized to generate a classification report, which can be directly used as the basis for subsequent procurement, quality assessment, inventory management, and maintenance strategy formulation for the accessories.

[0044] The present invention has the following beneficial effects: First, since step S1 of the present invention does not simply identify equipment attributes, but rather conducts a fault impact analysis by acquiring accessory failure modes and pneumatic circuit function information, and deducing the failure consequences of accessories layer by layer (i.e., deducing from the first impact result, the second impact result to the final state of the main valve), and compares and judges this with the preset fault safety position, it fills the gap of the long-term lack of safety classification standards for pneumatic control valve accessories in nuclear power plants, and provides a unified and scientific technical basis for on-site equipment management, procurement and appraisal; it avoids the misconception of judging solely based on equipment type in traditional methods, and fundamentally ensures that the classification conclusion strictly corresponds to nuclear safety risks. Secondly, since step S2 of this invention does not simply apply the main valve classification data to the accessories, but introduces the equipment's attribute data (such as whether it is energized or whether it performs safety functions) as classification conditions, a multi-condition branch logical judgment model is constructed. This method establishes a functional correlation analysis model between the main valve and the accessories, and directly links the classification results with nuclear safety risks through fault impact analysis, making it logically rigorous and scientifically sound. Thirdly, since this method breaks down the complex nuclear safety classification judgment into two clear and executable steps: fault impact analysis and multi-dimensional attribute data joint judgment, and directly provides clear level correspondence conclusions under different branches (such as energized / non-energized, performing / non-performing safety functions), this invention provides clear and step-by-step operational guidance. Engineering technicians can quickly and accurately classify various control accessories based on this method, making it highly operable. This invention avoids the high costs of managing all accessories with the highest safety requirements in a "one-size-fits-all" manner, implements strict control over key accessories, and reasonably reduces requirements for non-key accessories, achieving the best balance between safety and economy while ensuring nuclear safety, and effectively optimizing the management cost of the entire equipment life cycle.

[0045] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A safety classification method for control accessories of a pneumatic control valve in a nuclear power plant, wherein the pneumatic control valve is a main valve and the control accessory is an auxiliary component configured in its pneumatic control circuit, characterized in that... include: Step S1: Obtain at least one fault mode of the control accessory and the functional information of the control accessory in the pneumatic control loop; perform fault impact analysis based on the fault mode and the functional information to obtain the impact of the control accessory fault on the main valve's nuclear safety function. Step S2: Obtain the nuclear safety data and equipment attribute data of the main valve. Based on the nuclear safety data of the main valve, the equipment attribute data, and the impact results, determine the safety level, seismic resistance category, and qualification requirement level of the control accessory. The nuclear safety data includes the seismic resistance category and electrical / instrumentation safety level of the main valve. The equipment attribute data includes energized information and execution safety function information used to characterize whether the main valve performs nuclear safety functions.

2. The safety classification method for pneumatic control valve accessories in nuclear power plants according to claim 1, characterized in that, In step S1, obtaining the fault mode includes: Obtain the type information of the control accessory, and match at least one fault mode corresponding to the control accessory from a preset fault mode database based on the type information; wherein, the type information is used to characterize the device type of the control accessory.

3. The safety classification method for pneumatic control valve accessories in nuclear power plants according to claim 1, characterized in that, The fault impact analysis includes: Based on the functional information and the at least one fault mode, determine the actual state of the main valve under each fault mode; The actual state is compared with the preset fail-safe position of the main valve; If the actual state is inconsistent with the preset fail-safe position, the result is that the failure of the control accessory will affect the main valve's nuclear safety function. If the actual state is consistent with the preset fail-safe position, then the result is obtained that the failure of the control accessory does not affect the main valve's execution of nuclear safety functions.

4. The safety classification method for pneumatic control valve accessories in nuclear power plants according to claim 3, characterized in that, Determining the actual state of the main valve under each of the aforementioned fault modes includes: For each of the aforementioned failure modes, based on the functional information and the failure mode, a first impact result of the control accessory itself failing under that failure mode is determined; Based on the first impact result, determine the second impact result of the fault mode on the pneumatic control loop; Based on the second impact result, the final state of the main valve under the fault mode is determined, and the final state is taken as the actual state of the main valve.

5. The safety classification method for pneumatic control valve accessories in nuclear power plants according to claim 1, characterized in that, In step S2, determining the safety level, seismic resistance category, and assessment requirement level of the control accessory based on the nuclear safety data of the main valve, equipment attribute data, and the impact results includes: Based on the electrical information, determine whether the control accessory is a live device; If the control accessory is an electrical device, then the safety level, seismic resistance category, and assessment requirement level of the control accessory are determined based on the executed safety function information, the impact result, and the nuclear safety data of the main valve. If the control accessory is a non-electrical device, then the safety level, seismic resistance category, and qualification requirement level of the control accessory are determined based on the executed safety function information and the nuclear safety data of the main valve.

6. The safety classification method for pneumatic control valve accessories in nuclear power plants according to claim 5, characterized in that, If the control accessory is an electrical device, then based on the executed safety function information, the impact result, and the nuclear safety data of the main valve, the safety level, seismic resistance category, and assessment requirement level of the control accessory are determined, including: Based on the information regarding the execution of safety functions, it is determined whether the main valve is performing a nuclear safety function; If the main valve performs nuclear safety functions; When the impact result is that the failure of the control accessory will affect the main valve's nuclear safety function, the safety level of the control accessory is 1E, the seismic resistance category is seismic resistance class 1, and the qualification requirement level is determined according to the electrical / instrumentation qualification level of the main valve; When the effect result is that the failure of the control accessory does not affect the main valve from performing nuclear safety functions, the safety level of the control accessory is NC level, the seismic resistance category is seismic resistance class 1, and the assessment requirement level is determined according to the electrical / instrumentation assessment level of the main valve.

7. The safety classification method for pneumatic control valve accessories in nuclear power plants according to claim 5, characterized in that, If the control accessory is an electrical device, then based on the executed safety function information, the impact result, and the nuclear safety data of the main valve, the safety level, seismic resistance category, and assessment requirement level of the control accessory are determined, further including: Obtain the execution safety function information, and determine whether the main valve is performing a nuclear safety function based on the execution safety function information; If the main valve does not perform nuclear safety functions: When the effect result is that the failure of the control accessory does not affect the main valve from performing nuclear safety functions, the safety level of the control accessory is NC, the seismic resistance category is NO, and the qualification requirement level is NO; When the impact result is that the failure of the control accessory will affect the main valve's nuclear safety function, then there is no corresponding safety classification.

8. The safety classification method for pneumatic control valve accessories in nuclear power plants according to claim 5, characterized in that, If the control accessory is a non-electrical device, then based on the executed safety function information, the impact result, and the nuclear safety data of the main valve, the safety level, seismic resistance category, and assessment requirement level of the control accessory are determined, including: Based on the information regarding the execution of safety functions, it is determined whether the main valve is performing a nuclear safety function; If the main valve performs nuclear safety functions, determine whether the seismic resistance category of the main valve is seismic resistance class 1A; When the seismic resistance category of the main valve is seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class 1, the qualification requirement level is NO, and a mechanical qualification test instruction is generated. When the seismic resistance category of the main valve is not seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class NO, and the assessment requirement level is NO.

9. The safety classification method for pneumatic control valve accessories in nuclear power plants according to claim 5, characterized in that, If the control accessory is a non-electrical device, then based on the executed safety function information, the impact result, and the nuclear safety data of the main valve, the safety level, seismic resistance category, and assessment requirement level of the control accessory are determined, further including: Based on the information regarding the execution of safety functions, it is determined whether the main valve is performing a nuclear safety function; If the main valve does not perform nuclear safety functions, determine whether the seismic resistance category of the main valve is seismic resistance class 1A; When the seismic resistance category of the main valve is seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class 1, the qualification requirement level is NO, and a mechanical qualification test instruction is generated. When the seismic resistance category of the main valve is not seismic resistance class 1A, the safety level of the control accessory is NC, the seismic resistance category is seismic resistance class NO, and the assessment requirement level is NO.

10. The safety classification method for pneumatic control valve accessories in nuclear power plants according to claim 8, characterized in that, The mechanical identification test instructions include thermal aging test instructions, mechanical vibration test instructions, and seismic resistance test instructions.

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