Quantitative evaluation method and system for health state of nuclear reactor system

Abstract

The invention relates to the technical field of nuclear reactor engineering, in particular to a nuclear reactor system health state quantitative evaluation method and system, and the method comprises the following steps: building a reliability analysis model of a reactor system, and calculating an operation task risk factor of the reactor system; building a reactor system probabilistic safety analysis model, and calculating an operation safety risk factor of the reactor system; and calculating the health degree of the reactor system by taking the operation task risk factor and the operation safety risk factor as quantitative indexes for evaluating the health state of the reactor system. According to the method, the reliability and safety risk combined reactor system health state evaluation index is constructed, the system health degree is obtained through calculation, quantitative evaluation of the reactor system health state is achieved, and support can be provided for a user to more scientifically carry out risk evaluation and operation and maintenance decision making.

Description

Technical Field

[0001] The present invention relates to the field of nuclear reactor engineering technology, and in particular to a method and system for quantitatively evaluating the health status of a nuclear reactor system. Background Art

[0002] Equipment components in a nuclear reactor system may experience performance degradation or failure during operation, affecting the functional implementation of the reactor system and posing a major safety hazard. Timely maintenance and protection are required, but overly frequent maintenance and protection will also affect the availability of the nuclear reactor system and lead to a waste of security resources, seriously affecting the economic viability of nuclear energy applications.

[0003] Accurately assessing the health status of reactor systems and identifying system operational risks are fundamental to effective maintenance and assurance. While numerous quantitative assessment indicators and methods have been developed for the health status of individual equipment components, effective quantitative evaluation methods for nuclear reactor system health are still lacking, making it difficult for users to conduct risk assessments and make operational and maintenance decisions.

[0004] Since a nuclear reactor is a complex system with a large number of equipment types, mutually coupled subsystems and equipment operations, and complex internal logical relationships, how to effectively quantify the health status of the system remains a major challenge. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and system for quantitatively evaluating the health status of a nuclear reactor system based on reliability calculation. By constructing a quantitative indicator for evaluating the health status of a reactor system that combines reliability and safety risk, the system health is calculated and quantitative evaluation of the health status of the reactor system is achieved, so as to solve the technical problem of how to effectively quantitatively evaluate the health status of the system and provide support for users to carry out risk assessment and operation and maintenance decisions more scientifically.

[0006] The present invention is implemented through the following technical solution: A method for quantitatively evaluating the health status of a nuclear reactor system comprises the following steps:

[0007] Build a reactor system reliability analysis model and calculate the operational mission risk factors of the reactor system;

[0008] Build a probabilistic safety analysis model for the reactor system and calculate the operational safety risk factors of the reactor system;

[0009] The operation mission risk factor and the operation safety risk factor are used as quantitative indicators for evaluating the health status of the reactor system, and the health of the reactor system is calculated.

[0010] According to a preferred embodiment, the process of calculating the operational mission risk factor of the reactor system is as follows:

[0011] Determine the reliability and failure rate of each device in the reactor system by performing equipment operation status analysis on each device in the reactor system;

[0012] Based on the reliability and failure rate of each device, the reliability of the reactor system is calculated;

[0013] Based on the reliability of the reactor system, an operation mission risk factor of the reactor system is calculated.

[0014] According to a preferred embodiment, the calculation expression of the reliability is R system (t)=f(R1(t),R2(t),…,R i (t)), where R system (t) represents the reliability of the equipment at time t, represents the reliability of the i-th device in the reactor system at time t, λ i (t) represents the failure rate of the i-th device in the reactor system at time t.

[0015] According to a preferred embodiment, the i (t) Take the reciprocal of the mean time between failures of the equipment, expressed as λ i (t)=1 / MTBF i , where MTBF i It represents the mean time between failures of the i-th device.

[0016] According to a preferred embodiment, the expression of the operation task risk factor is a(t1)=a(t0)·R system (t1) / R system (t0), where a(t1) represents the risk factor of the running task at the current time t1, a(t0) represents the risk factor of the running task at the initial time t0, R system (t1) represents the reliability of the current time t1, R system (t0) represents the reliability at the initial time t0.

[0017] According to a preferred embodiment, the process of calculating the operational safety risk factor of the reactor system is as follows:

[0018] Calculating the cumulative failure probability of each device based on the reliability;

[0019] Calculating the core damage frequency based on the cumulative failure probability of each device;

[0020] Based on the core damage frequency, an operational safety risk factor of the reactor system is calculated.

[0021] According to a preferred embodiment, the calculation expression of the core damage frequency is P CDF (t)=f(P1(t),P2(t),…,P i (t)), where P CDF (t) represents the damage frequency of the core in the reactor system at time t, P i (t) = 1 - R i (t), represents the cumulative failure probability of the i-th device in the reactor system at time t.

[0022] According to a preferred embodiment, the expression of the operational safety risk factor is β(t1)=β(t0)·log 10 P CDF (t1) / P CDF (t0), where β(t1) represents the operational safety risk factor at the current time t1, β(t0) represents the operational safety risk factor at the initial time t0, P CDF (t1) represents the core damage frequency at the current time t1, P CDF (t0) represents the core damage frequency at the initial time t0.

[0023] According to a preferred embodiment, the health expression of the reactor system is H(t1)=H(t0)·a(t1)·β(t1), where H(t1) represents the health of the reactor system at the current time t1.

[0024] The present invention also provides a nuclear reactor system health status quantitative assessment system, which is applied to the above-mentioned method, and the system includes:

[0025] The first calculation module is used to build a reactor system reliability analysis model and calculate the operational mission risk factor of the reactor system;

[0026] The second calculation module is used to build a probabilistic safety analysis model for the reactor system and calculate the operational safety risk factor of the reactor system;

[0027] The evaluation module is used to use the operation mission risk factor and the operation safety risk factor as quantitative indicators for evaluating the health status of the reactor system to calculate the health of the reactor system.

[0028] The technical solution of a method and system for quantitatively assessing the health status of a nuclear reactor system provided by the present invention has at least the following advantages and beneficial effects: the present invention constructs a quantitative indicator for assessing the health status of a reactor system that combines reliability and safety risk, calculates the system health, and realizes a quantitative evaluation of the health status of the reactor system, which can provide support for users to carry out risk assessment and operation and maintenance decisions more scientifically. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic flow chart of a method for quantitatively assessing the health status of a nuclear reactor system provided in Example 1 of the present invention;

[0030] Figure 2 A simplified flow chart of a nuclear reactor system provided in Example 1 of the present invention;

[0031] Figure 3 This is a functional block diagram of the reactor system provided in Example 1 of the present invention;

[0032] Figure 4 A block diagram of the reactor coolant subsystem mission reliability analysis provided in Example 1 of the present invention;

[0033] Figure 5 This is a block diagram of the equipment cooling water subsystem task reliability analysis provided in Example 1 of the present invention;

[0034] Figure 6 The fault tree analysis model of the safety injection subsystem provided in Example 1 of the present invention;

[0035] Figure 7 This is the event tree for the large LOCA of the reactor system provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0037] Example 1

[0038] In order to effectively perform quantitative evaluation on the health status of the system, the present invention proposes a quantitative evaluation method for the health status of a nuclear reactor system based on reliability calculation.

[0039] The nuclear reactor system health status quantitative assessment method based on reliability calculation in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0040] Step 1: Build a reactor system reliability analysis model and calculate the operational mission risk factor of the reactor system;

[0041] Step 2: Build a probabilistic safety analysis model for the reactor system and calculate the operational safety risk factors of the reactor system;

[0042] Step 3: Using the operation mission risk factor and the operation safety risk factor as quantitative indicators for evaluating the health status of the reactor system, the health of the reactor system is calculated.

[0043] Furthermore, the process of calculating the operational mission risk factor of the reactor system in step 1 is as follows:

[0044] Step 1.1. Determine the reliability and failure rate of each device in the reactor system by performing an equipment operating status analysis on each device in the reactor system. It should be noted that reliability refers to the ability of a device to complete a specified function under specified conditions within a specified period of time, and failure rate refers to the probability that a device that has not failed at time t will fail within a unit time after time t.

[0045] In this embodiment, the reliability of the i-th device in the reactor system at time t is defined as R i (t), the failure rate of the i-th device at time t is λ i (t); Considering that the reliability and failure rate of the equipment vary with time, this embodiment determines the reliability and failure rate by performing equipment operating status analysis; in some embodiments, the equipment reliability can be calculated by assuming that it satisfies common models such as exponential distribution and Weibull distribution; in other embodiments, based on the concept of equipment health assessment of the operating status, the special signals such as equipment vibration and acoustic emission monitored at the current moment can be deeply analyzed to provide a predictive assessment result of the reliability and failure rate of the equipment.

[0046] Step 1.2: Based on the reliability and failure rate of each device, calculate the reliability of the reactor system. It should be noted that reliability refers to the probability that a device can complete a specified function under specified conditions and within a specified time.

[0047] In this embodiment, the calculation expression of the reliability is:

[0048] R system (t)=f(R1(t),R2(t),…,R i (t))

[0049]

[0050] In the above formula, R system (t) represents the reliability of the equipment at time t, R i (t) represents the reliability of the i-th device in the reactor system at time t, λ i (t) represents the failure rate of the i-th device in the reactor system at time t; preferably, the λ i (t) Take the reciprocal of the mean time between failures of the equipment, expressed as λ i(t)=1 / MTBF i , where MTBF i It represents the mean time between failures of the i-th device.

[0051] Step 1.3: Based on the reliability of the reactor system, calculate the operational mission risk factor of the reactor system.

[0052] In this embodiment, the expression of the running task risk factor is:

[0053] a(t1)=a(t0)·R system (t1) / R system (t0)

[0054] In the above formula, a(t1) represents the risk factor of the running task at the current time t1, a(t0) represents the risk factor of the running task at the initial time t0, R system (t1) represents the reliability of the current time t1, R system (t0) represents the reliability at the initial time t0.

[0055] Furthermore, the process of calculating the operational mission risk factor of the reactor system in step 2 is as follows:

[0056] Step 2.1. Calculate the core damage frequency based on the cumulative failure probability of each device. It should be noted that the cumulative failure probability refers to unreliability, that is, the probability of a device failing under specified conditions and within a specified time. The core damage frequency is one of the core indicators of probabilistic safety analysis and is used to quantify the probability of severe core damage (such as fuel cladding failure, fuel matrix melting, or core structure damage) caused by the development of an accident sequence within a specific operating cycle of the reactor.

[0057] In this embodiment, the calculation expression of the core damage frequency is:

[0058] P CDF (t)=f(P1(t),P2(t),…,P i (t))

[0059] P i (t)=1-R i (t)

[0060] In the above formula, P CDF (t) represents the damage frequency of the core in the reactor system at time t, P i (t) represents the cumulative failure probability of the i-th device in the reactor system at time t.

[0061] Step 2.2: Based on the core damage frequency, calculate the operational safety risk factor of the reactor system.

[0062] In this embodiment, the expression of the operation safety risk factor is:

[0063] β(t1)=β(t0)·log 10 P CDF (t1) / P CDF (t0)

[0064] In the above formula, β(t1) represents the operational safety risk factor at the current time t1, β(t0) represents the operational safety risk factor at the initial time t0, and P CDF (t1) represents the core damage frequency at the current time t1, P CDF (t0) represents the core damage frequency at the initial time t0.

[0065] Furthermore, the calculation formula used in step 3 to calculate the health of the reactor system is as follows:

[0066] H(t1)=H(t0)·a(t1)·β(t1)

[0067] In the above formula, H(t1) represents the health of the reactor system at the current time t1.

[0068] The following uses a simplified nuclear reactor system as an example to illustrate the method for quantitatively assessing the health status of a nuclear reactor system provided in this embodiment:

[0069] See also Figure 2 As shown in the figure, the nuclear reactor system includes the reactor coolant subsystem, the equipment cooling water subsystem and the safety injection subsystem; the reliability of the i-th equipment in the nuclear reactor system is defined as R i (t), the cumulative failure probability is P i (t), where the values ​​of i are shown in Table 1 below:

[0070]

[0071] Table 1. Device numbers

[0072] The mean time between failures of each device is shown in Table 2 below:

[0073] Device number i 1 2 3 4 5 6 <![CDATA[MTBF i ]]> 10000h 20000h 20000h 10000h 10000h 20000h Device number i 7 8 9 10 11 12 <![CDATA[MTBF i ]]> 2000 times 5000h 5000h 2000 times 2000 times 100000h

[0074] Table 2. MTBF i Value

[0075] Assuming t0 = 100h, valves A, B, and C have been operated 20 times, the low-pressure injection pump has been running for 5h, H(t0) = 1, a(t0) = 1, β(t0) = 1, then the reliability of each device at time t0 is shown in Table 3 below:

[0076] Device number i 1 2 3 4 5 6 <![CDATA[R i (t0)]]> 0.99 0.995 0.995 0.99 0.99 0.995 Device number i 7 8 9 10 11 12 <![CDATA[R i (t0)]]> 0.99 0.999 0.999 0.99 0.99 0.999

[0077] Table 3. R i (t0) value

[0078] Calculate t1 = 1000h. Assume that valves A, B, and C have been operated 200 times, the two low-pressure injection pumps have been running for 50h, and the other equipment have been running for 1000h. The cumulative failure probability of each equipment is shown in Table 4 below:

[0079] Device number i 1 2 3 4 5 6 <![CDATA[P i (t1)]]> 0.794 0.89 0.89 0.794 0.794 0.89 Device number i 7 8 9 10 11 12 <![CDATA[P i (t1)]]> 0.905 0.99 0.99 0.905 0.905 0.99

[0080] Table 4.P i (t1) value

[0081] Furthermore, considering that the basic function of the reactor system is to transfer the heat of the reactor nuclear fission reaction to the secondary circuit, in order to achieve this function, the reactor coolant system needs to operate reliably for a long time, and the equipment cooling water system (providing cooling water for the main pump) needs to operate reliably for a long time. Figures 3 to 5 The reactor system functional block diagram and the mission reliability analysis block diagram of each subsystem are shown.

[0082] Depend on Figures 3 to 5 The block diagram shown in the figure can be used to calculate the reliability:

[0083] R system (t)=R1(t)·R2(t)·R3(t)·R6(t)·(1-R4(t)·R5(t))·R7(t)

[0084] From this we can calculate R system (t0)≈0.97, R system (t1)≈0.545.

[0085] Furthermore, at the current time t1, according to the calculation formula of a(t1), we can obtain:

[0086] a(t1)=a(t0)·R system (t1) / R system (t0)≈0.562.

[0087] See also Figure 6 The figure shows the fault tree model of the safety injection subsystem. The event tree model is shown in Figure 7 shown.

[0088] Depend on Figure 6 and Figure 7 As shown in Figure 2, according to the probabilistic safety analysis model, the calculation formula for the core damage frequency is:

[0089] P cDF(t) = 1-(1-P 12 (t))·(1-P ESI (t))·(1-P sign (t))

[0090] Among them, P sign (t) is the probability of failure of the injection signal, which is set to a constant of 10 -3 , P ESI (t) is the probability of failure of the injection driver, which can be calculated by the following formula:

[0091] P ESI (t) = P ESI_A (t)+P ESI_B (t)-P ESI_A (t)·P ESI_B (t)

[0092] P ESI_A (t) = P8(t) + P 10 (t)-P8(t)·P 10 (t)

[0093] P ESI_B (t) = P9(t) + P 11 (t)-P9(t)·P 11 (t)

[0094] From this we can calculate P CDF (t0)≈0.042, P CDF (t1)≈0.21.

[0095] Furthermore, at the current time t1, according to the calculation formula of β(t1), we can obtain:

[0096] β(t1)=β(t0)·log 10 P CDF (t1) / P CDF (t0)≈0.51

[0097] Furthermore, based on the above modeling and calculation results, the health of the nuclear reactor system at the current time t1 can be calculated by the calculation formula H(t1) as follows:

[0098] H(t1)=H(t0)·a(t1)·β(t1)≈0.285

[0099] In summary, the method for quantitatively evaluating the health status of a nuclear reactor system based on reliability calculation provided in this embodiment constructs a quantitative indicator for evaluating the health status of a reactor system that combines reliability and safety risk, calculates the system health, and realizes a quantitative evaluation of the health status of the reactor system.

[0100] Example 2

[0101] This embodiment, based on the technical solution provided in Example 1, provides a nuclear reactor system health status quantitative assessment system, which is applied to the method described in Example 1. The system includes a first calculation module, a second calculation module, and an assessment module.

[0102] In this embodiment, the first calculation module is used to build a reactor system reliability analysis model and calculate the operating mission risk factor of the reactor system; the second calculation module is used to build a reactor system probabilistic safety analysis model and calculate the operating safety risk factor of the reactor system; the evaluation module is used to use the operating mission risk factor and the operating safety risk factor as quantitative indicators for evaluating the health status of the reactor system to calculate the health of the reactor system.

[0103] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for quantitatively assessing the health status of a nuclear reactor system, characterized in that: The steps include: Build a reactor system reliability analysis model and calculate the operational mission risk factors of the reactor system; Build a probabilistic safety analysis model for the reactor system and calculate the operational safety risk factors of the reactor system; The operation mission risk factor and the operation safety risk factor are used as quantitative indicators for evaluating the health status of the reactor system, and the health of the reactor system is calculated.

2. The method for quantitatively assessing the health status of a nuclear reactor system according to claim 1, wherein: The process of calculating the operational mission risk factor of the reactor system is as follows: Determine the reliability and failure rate of each device in the reactor system by performing equipment operation status analysis on each device in the reactor system; Based on the reliability and failure rate of each device, the reliability of the reactor system is calculated; Based on the reliability of the reactor system, an operation mission risk factor of the reactor system is calculated.

3. The method for quantitatively assessing the health status of a nuclear reactor system according to claim 2, wherein: The calculation expression of the reliability is R system (t)=f(R1(t),R2(t),…,R i (t)), where R system (t) represents the reliability of the equipment at time t, represents the reliability of the i-th device in the reactor system at time t, λ i (t) represents the failure rate of the i-th device in the reactor system at time t.

4. The method for quantitatively assessing the health status of a nuclear reactor system according to claim 3, wherein: The λ i (t) Take the reciprocal of the mean time between failures of the equipment, expressed as λ i (t)=1 / MTBF i , where MTBF i It represents the mean time between failures of the i-th device.

5. The method for quantitatively assessing the health status of a nuclear reactor system according to claim 3, wherein: The expression of the operation task risk factor is a(t1)=a(t0)·R system (t1) / R system (t0), where a(t1) represents the risk factor of the running task at the current time t1, a(t0) represents the risk factor of the running task at the initial time t0, R system (t1) represents the reliability of the current time t1, R system (t0) represents the reliability at the initial time t0.

6. The method for quantitatively assessing the health status of a nuclear reactor system according to claim 5, wherein: The process of calculating the operational safety risk factor of the reactor system is as follows: Calculating the cumulative failure probability of each device based on the reliability; Calculating the core damage frequency based on the cumulative failure probability of each device; Based on the core damage frequency, an operational safety risk factor of the reactor system is calculated.

7. The method for quantitatively assessing the health status of a nuclear reactor system according to claim 6, wherein: The calculation expression of the core damage frequency is P CDF (t)=f(P1(t),P2(t),…,P i (t)), where P CDF (t) represents the damage frequency of the core in the reactor system at time t, P i (t)=1-R i (t), represents the cumulative failure probability of the i-th device in the reactor system at time t.

8. The method for quantitatively assessing the health status of a nuclear reactor system according to claim 7, wherein: The expression of the operational safety risk factor is β(t1)=β(t0)·log 10 P CDF (t1) / P CDF (t0), where β(t1) represents the operational safety risk factor at the current time t1, β(t0) represents the operational safety risk factor at the initial time t0, P CDF (t1) represents the core damage frequency at the current time t1, P CDF (t0) represents the core damage frequency at the initial time t0.

9. The method for quantitatively assessing the health status of a nuclear reactor system according to claim 8, wherein: The health expression of the reactor system is H(t1)=H(t0)·a(t1)·β(t1), where H(t1) represents the health of the reactor system at the current time t1.

10. A nuclear reactor system health status quantitative assessment system, characterized in that: Applied to the method according to any one of claims 1 to 9, the system comprises: The first calculation module is used to build a reactor system reliability analysis model and calculate the operational mission risk factor of the reactor system; The second calculation module is used to build a probabilistic safety analysis model for the reactor system and calculate the operational safety risk factor of the reactor system; The evaluation module is used to use the operation mission risk factor and the operation safety risk factor as quantitative indicators for evaluating the health status of the reactor system to calculate the health of the reactor system.

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