A cut set post-processing method for nuclear power plant availability model

Abstract

The present invention relates to a cut set post-processing method for a nuclear power plant availability model, comprising: reading in the cut set results of the nuclear power plant availability model, completing the shutdown frequency calculation; re-encoding and assigning values ​​to the basic events of the power reduction group in the shutdown frequency cut set, calculating the power generation recovery time of each corresponding cut set, and calculating the power generation loss time factor of each corresponding cut set based on the cut set content. The present invention develops a cut set post-processing method for nuclear power plant availability analysis, calculates the repair time and time factor occupied by the fault state affecting the operation of the nuclear power plant, and recalculates the importance and sensitivity of the failure mode of each equipment in the power plant according to the availability of the nuclear power plant, thereby helping relevant staff to analyze the basic events affecting the economy of the power plant from the perspective of availability.

Description

Technical Field

[0001] The invention belongs to nuclear power design technology, and in particular relates to a cut set post-processing method for a nuclear power plant availability model. Background Art

[0002] The availability of nuclear power plants is closely related to the economic efficiency of nuclear power plants. The Unit Capability Factor defined by the World Association of Nuclear Operators (WANO) and other organizations is related to both the design of nuclear power plants and the operation management and organizational performance of the operating unit, and cannot be directly used as a requirement for designers. Therefore, the European Utility Requirements for LWR nuclear power plants (EUR) defines the Design Availability Factor (DAF) to reflect the performance of the systems and equipment designed for nuclear power plants.

[0003] The nuclear power plant availability model reflects the comprehensive effects of nuclear power plant hardware and software such as overall design, equipment reliability and operation management. To a large extent, it serves as a core indicator reflecting the economic efficiency of the unit.

[0004] Based on the characteristics of the availability model, it is necessary not only to calculate the frequency and composition factors of unplanned shutdown events, but also to calculate the shutdown time caused by each event. Therefore, after the shutdown / power reduction model is built, the minimum cut set obtained by the fault tree solution needs to be further processed. Summary of the invention

[0005] The purpose of the present invention is to provide a cut set post-processing method suitable for different nuclear power plant availability models. By pre-given the repair time under each system operating condition and the repair time of the fault mode, the cut set calculation results of the availability model can be combined to calculate the repair time and time factor occupied by the fault state affecting the operating state of the power plant, and the results can be sorted out according to the power plant availability to recalculate the importance and sensitivity of the failure mode of each equipment in the power plant.

[0006] The technical solution of the present invention is as follows: A cut set post-processing method for a nuclear power plant availability model, comprising:

[0007] (1) Read the cut set results of the nuclear power plant availability model and complete the shutdown frequency calculation:

[0008] 1.1) Delete the cut set that only contains the basic events of the demand failure mode in the initial cut set;

[0009] 1.2) Identify the same cut sets that appear in different power reduction groups, retain the cut sets of the power reduction group with a high priority, and delete the same cut sets of other power reduction groups;

[0010] 1.3) Based on the cut set selected in step 1.2), calculate the cut set result after adding the time factor correction;

[0011] 1.4) Give the probability of occurrence of each basic event, and calculate and analyze the importance and sensitivity of each basic event;

[0012] (2) Based on the cut sets selected in step 1.2), the power generation risk calculation for each cut set is completed:

[0013] 2.1) Based on the equipment type, equipment failure mode and power reduction group information in the cut set, calculate the power generation recovery time of each corresponding cut set;

[0014] 2.2) Based on the content of the cut set, calculate the power generation loss time factor of each corresponding cut set.

[0015] Furthermore, in the above-mentioned cut set post-processing method for the nuclear power plant availability model, in step 1.3), different time factor correction methods are used to calculate the number of basic events in different cut sets:

[0016] a) When there is only one basic event of operation failure in the cut set, the basic event "Year" is directly added with a value of 365;

[0017] b) When there are two or more basic events of operation failure in the cut set, in addition to adding the basic event "Year", the operation time correction factor needs to be added. The calculation formula of the operation time correction factor is:

[0018]

[0019] Where T_* is the running time correction factor, MTTR i is the repair time of the corresponding equipment class, and N is the number of basic events of operation failure in the cut set.

[0020] Further, in the cut set post-processing method of the nuclear power plant availability model described above, the relevant indicators for importance calculation in step 1.4) include:

[0021] Importance FV,

[0022] Risk increase factor RIF,

[0023] Risk reduction factor RDF,

[0024] Among them, MCS (Minimal Cut Set) is the minimum cut set, i is the basic event, Φ is the total number of cut sets, P (MCS 含部件i ) represents the failure probability of the minimum cut set containing component i, P(Φ) represents the failure probability of the top event, P(Φ Xi＝0 ) means that when the basic event X i The probability of the top event occurring when it is very reliable, P(Φ Xi＝1 ) means that when the basic event X i The probability of the top event occurring at a certain failure time.

[0025] Furthermore, in the above-mentioned cut set post-processing method for the nuclear power plant availability model, the power generation recovery time described in step 2.1) is the repair time corresponding to all basic events in the cut set including the repair time of the power reduction group.

[0026] Further, in the cut set post-processing method of the nuclear power plant availability model described above, the calculation formula of the power generation loss time factor in step 2.2) is as follows:

[0027] When the corresponding power reduction group is DC01, DC02, DC03,

[0028] LT=P×TF×RT×DS

[0029]

[0030] When the corresponding power reduction group is not DC01, DC02, or DC03,

[0031] LT=P×TF×RT

[0032] Among them, DC01 indicates that the power reduction is greater than 75%, DC02 indicates that the power reduction is greater than 25% and less than 50%, DC03 indicates that the power reduction is less than 25%, LT is the power generation loss time factor, P is the failure rate corresponding to the cut set, TF is the time factor corresponding to the cut set, and RT is the repair time corresponding to the cut set.

[0033] The beneficial effects of the present invention are as follows: Based on the cut set results of the nuclear power plant availability model, the present invention analyzes and displays the basic events and fault types that affect the power generation risk of the nuclear power plant from multiple aspects such as time factors and power generation loss frequency, and re-analyzes the importance and sensitivity of each basic event that affects the power generation of the nuclear power plant. Compared with directly analyzing the results of the availability model, further post-processing of the cut set can help power plant staff to screen out the cut sets that do not contain operational failures, and calculate the power generation loss time, power generation loss rate and other information in combination with the repair time of each power reduction group and equipment type given in advance, so as to help nuclear power plant designers have a more comprehensive understanding of the factors affecting the power generation risk of nuclear power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a flowchart of the cut set post-processing method of the nuclear power plant availability model. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] This method develops a cut set post-processing program for the analysis of nuclear power plant availability, calculates the repair time and time factor occupied by the fault state that affects the operation of the nuclear power plant, and sorts out the results according to the availability of the nuclear power plant, and recalculates the importance and sensitivity of the failure mode of each equipment in the nuclear power plant. This helps relevant staff to analyze the basic events that affect the economic efficiency of the power plant from the perspective of availability.

[0037] like Figure 1 As shown, the technical solution adopted by the present invention is a cut set post-processing method for a nuclear power plant availability model, comprising the following steps:

[0038] Step 1: Read the cut set results of the nuclear power plant availability model and complete the shutdown frequency calculation. The shutdown frequency calculation can be divided into the following aspects.

[0039] Step 1.1: Check the "initial cut set" and delete the cut set that only contains the basic events of the required failure mode;

[0040] Step 1.2: Based on step 1.1, identify the same cut sets appearing in different power reduction groups, retain the cut sets of the power reduction group with a high priority, and delete the same cut sets of other power reduction groups;

[0041] Step 1.3: Based on step 1.2, calculate the time factor correction value. The average repair time uses the year as the time interval to calculate the average repair time corresponding to the corresponding cut set each year. For different numbers of basic events in the cut set, different time factor correction methods are used for calculation:

[0042] -When there is only one basic event of operation failure in the cut set, the basic event "Year" is directly added with a value of 365;

[0043] -When there are two or more basic events of operation failure in the cut set, in addition to adding the basic event "Year", the operation time factor needs to be added. The calculation formula of the operation time correction factor is:

[0044]

[0045] Where T_* is the running time correction factor, MTTRi is the repair time of the corresponding equipment class, and N is the number of basic events of operation failure in the cut set.

[0046] Step 1.4: Based on the results generated in step 1.2, i.e., the shutdown frequency cut set, complete the statistics of available results, importance, and sensitivity calculations for each basic event, including:

[0047] -Provide the probability of occurrence of each basic event (events related to human error are calculated using the human reliability method, and events related to random equipment failure are obtained using statistical methods);

[0048] - Calculate the results of FV (Fussel-Vessely factor), RDF (Risk Decrease Factor), and RIF (Risk Increase Factor) for each basic event;

[0049] The shutdown frequency cut set is obtained by constructing a shutdown logic model. The shutdown logic model can be constructed by the fault tree method. The fault tree method is a mature analysis method. The specific approach can refer to GJB / Z768A-98 "Fault Tree Analysis Guidelines" and NB / T20558-2019 "Nuclear Power Plant Fault Tree Analysis Guidelines".

[0050] Importance and sensitivity analysis help to understand and interpret the calculation results. They are particularly important for the application of nuclear power availability analysis. For example, they can identify weak links in design or operation and provide suggestions for design improvements or operation management improvements of nuclear power plants. The description of importance related indicators is shown in Table 1.

[0051] Table 1 Description of importance related indicators

[0052]

[0053] Note: MCS (Minimal Cut Set) is the minimum cut set, i is the basic event, Φ is the total number of cut sets, P (MCS 含部件i ) represents the failure probability of the minimum cut set containing component i, P(Φ) represents the failure probability of the top event, P(Φ Xi＝0 ) means that when the basic event X i The probability of the top event occurring when it is very reliable, P(Φ Xi＝1 ) means that when the basic event X i The probability of the top event occurring at a certain failure time.

[0054] The purpose of sensitivity analysis is to identify basic events that have a potentially significant impact on the results and their sensitivity, and to analyze their "potential" importance, such as whether the overall risk will increase significantly if the probability of a basic event increases 10 times.

[0055] Step 2: Based on the cut sets selected in step 1.2, complete the power generation risk calculation for each cut set. The specific calculation content is divided into the following aspects.

[0056] Step 2.1: Based on the equipment type, equipment failure mode and power reduction group information in the cut set, calculate the power generation recovery time (including equipment failure time and equipment repair time) of each corresponding cut set. The power generation recovery time is the repair time corresponding to all basic events in the cut set, including the repair time of the power reduction group. The time factor frequency is the product of the time factor and the failure rate of the corresponding cut set, which aims to reflect the importance of the corresponding cut set in terms of repair time.

[0057] Step 2.2: Based on the cut set content, calculate the power generation loss time factor of each corresponding cut set.

[0058] The power generation loss time reflects the power generation loss time corresponding to each cut set when the cut set failure rate is taken into account. The calculation formula is:

[0059] When the corresponding power reduction group is DC01, DC02, DC03,

[0060] LT=P×TF×RT×DS

[0061]

[0062] When the power reduction group is not DC01, DC02, or DC03,

[0063] LT=P×TF×RT

[0064] Among them, DC01 indicates that the power reduction is greater than 75%, DC02 indicates that the power reduction is greater than 25% and less than 50%, DC03 indicates that the power reduction is less than 25%, LT is the power generation loss time factor, P is the failure rate corresponding to the cut set, TF is the time factor corresponding to the cut set, and RT is the repair time corresponding to the cut set.

[0065] Step 2.3: Based on the “power generation risk cut set”, complete the importance and sensitivity calculation.

[0066] Example

[0067] The minimum cut set of system failure of the availability of a domestic nuclear power unit is shown in Table 1, in which only some cut set results are excerpted for example.

[0068] Table 1 Cut set results of availability model of a domestic nuclear power unit

[0069]

[0070]

[0071] In the process of modeling the availability model, the basic events of operation failure and demand failure are pre-set, as shown in Table 2, which are used as the basis for cut set screening.

[0072] Table 2 Operation / demand failure label categories

[0073]

[0074]

[0075] Step 1.1: Delete the basic events that do not contain operational failures in the cut set, as shown in Table 3.

[0076] Table 3 does not include the cut set of operation failure

[0077] No. Probability ％ Event 1 Event 2 Event 3 13 6.312E-05 1.54 AS01 RNI01 23 2.784E-05 0.68 AS01 WA×_FW 25 2.694E-05 0.66 AS01 RPA-T3-F RPA-T3-Q 81 5.976E-06 0.15 AS01 TFM244VLA_FC 82 5.976E-06 0.15 MS02 RCV061VPA-FC 83 5.976E-06 0.15 AS01 TFM243VLA_FC 84 5.976E-06 0.15 AS01 RCV-HE02 RCV046VPA-FC 85 5.976E-06 0.15 AS01 TFM031VLA_FC 86 5.976E-06 0.15 AS01 TFM032VLA_FC 87 5.976E-06 0.15 AS01 TFM242VLA_FC 88 5.976E-06 0.15 AS01 TFM033VLA_FC 89 5.808E-06 0.14 MS01 RCS021VPE-UV 90 5.808E-06 0.14 MS01 RCS022VPE-UV 91 5.808E-06 0.14 MS01 RCS020VPE-UV

[0078] Step 1.2: The importance ranking of the unit power reduction groups is shown in Table 4. According to the order of importance of the codes in the power reduction, the corresponding cut sets with high importance are retained first.

[0079] Table 4 Importance ranking of different power reduction groups

[0080]

[0081]

[0082] Table 5 shows an example of deleting cut sets with the same cut sets but different power reduction groups.

[0083] Table 5 Examples of the same cut sets in different power reduction groups

[0084]

[0085] ╳:Delete ○:Retain

[0086] Step 1.3: In order to calculate the time correction factor of the corresponding cut set, the repair time of each equipment class needs to be given in advance. Examples of the repair time of some equipment classes in the unit are shown in Table 6.

[0087] Table 6 Repair time of some equipment types

[0088] Equipment Label describe Average repair time (h / year) RHR Residual Pump 48 WCC Equipment cooling water pump 38 WES Plant water pump 31 RFT PTR Pump 98 EMP / EMQ Emergency Diesel Generators 43 ZV Fan 15 EXX / RFE / RFX Heat Exchanger 12

[0089] According to the calculation method described in step 1.3 of the previous technical solution, the cut set results after adding the time factor correction are obtained, as shown in Table 7.

[0090] Table 7 Calculation of cut set time factors

[0091] No. Probability Event 1 Event 2 Event 3 Event 4 Event 5 Event 6 Time Factor 5140 2.663E-12 AS01 EDA016JAX_SA EDA017JAX_SA T_004900 1332 5141 2.663E-12 MS02 EDA017JAX-SAT EDA016JAX-SAT T_004901 1332 5142 2.656E-12 AS01 C3WCCJAX1-RTC-ALL WES001POM_FW WES003POM_UV T_004902 333 5143 2.655E-12 DC03 EDA001RDX-FWR EEA001TBB-FWR TFE301POM-FS T_004903 499.5 5144 2.655E-12 DC03 EDA002RDX-FWR ERE001TBB-FWR TFE301POM-FS T_004904 499.5 5145 2.655E-12 DC03 EDA001RDX-FWR EMA001TBB-FWR TFE301POM-FS T_004905 499.5 5146 2.655E-12 DC03 EDA002RDX-FWR ESC001TBB-FWR TFE301POM-FS T_004906 499.5 5147 2.653E-12 AS01 WES001POM_FW WES002FIW_PG WES003POM_FW T_004907 3538.13 5148 2.653E-12 AS01 WES001FIW_PG WES002POM_FW WES004POM_FW T_004908 3538.13 5149 2.573E-12 MS02 ESBSWITCH_FD MOPCON_FW EMA002JAX-RTC RCV002POM-FDR T_004909 1332 5150 2.573E-12 MS02 ESBSWITCH_FD MOPCON_FW EMA001JAX-RTO RCV002POM-FDR T_004910 1332 5151 2.566E-12 MS02 ESC001JAX-RTO MOPCON_FW EMQ001APX_FW VEC101ZKX-FWR T_004911 3288.38 5152 2.566E-12 MS02 ESC001JAX-RTO MOPCON_FW EMQ001APX_FW VEC301ZKX-FWR T_004912 3288.38 5153 2.566E-12 MS02 ESB001JAX-RTO MOPCON_FW EMP001APX_FW VEC102ZKX-FWR T_004913 3288.38 5154 2.566E-12 MS02 ESB001JAX-RTO MOPCON_FW EMP001APX_FW VCL002ZKX-FWR T_004914 3787.88 5155 2.566E-12 MS02 ESB001JAX-RTO MOPCON_FW EMP001APX_FW VEC302ZKX-FWR T_004915 3288.38 5161 2.566E-12 MS02 ESC002JAX-RTC MOPCON_FW EMQ001APX_FW VEC301ZKX-FWR T_004921 3288.38 5162 2.566E-12 MS02 ESC001JAX-RTO MOPCON_FW EMQ001APX_FW VCL001ZKX-FWR T_004922 3787.88 5163 2.548E-12 MS02 EMA001JAX-RTO MOPCON_FW AOPBUS_UV VEC302ZKX-FWR T_004923 1623.38 5164 2.548E-12 MS02 EMA001JAX-RTO MOPCON_FW AOPBUS_UV VEC102ZKX-FWR T_004924 1623.38 5165 2.548E-12 MS02 EMB002JAX-RTC MOPCON_FW AOPBUS_UV VEC101ZKX-FWR T_004925 2497.5

[0092] Step 1.4: Based on the results generated in step 1.2, complete the statistics of available results, importance, and sensitivity calculations for each basic event. The calculation formula is as described in the specific method of step 1.4 in the technical solution above. The results are shown in Table 8.

[0093] Table 8 Importance and sensitivity analysis of some basic events

[0094]

[0095]

[0096] Step 2: Based on the cut sets screened in step 1.2, the repair time of different power reduction groups and the repair time of each equipment type, the power generation loss time and power generation recovery time are calculated according to the method of step 2 in the above technical solution. The calculation results are shown in Table 9.

[0097] Table 9 Calculation results of partial cut-set generation risk

[0098]

[0099] It will be apparent to those skilled in the art that the inventive method is not limited to the details of the exemplary embodiments described above and that the inventive method can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the inventive method is defined by the appended claims rather than the above description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the inventive method. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0100] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A cut set post-processing method for a nuclear power plant availability model, comprising: (1) Read the cut set results of the nuclear power plant availability model and complete the shutdown frequency calculation: 1.1) Delete the cut set that only contains the basic events of the demand failure mode in the initial cut set; 1.2) Identify the same cut sets that appear in different power reduction groups, retain the cut sets of the power reduction group with a high priority, and delete the same cut sets of other power reduction groups; 1.3) Based on the cut sets selected in step 1.2), calculate the cut set results after adding the time factor correction; for different numbers of basic events in the cut sets, use different time factor correction methods for calculation: a) When there is only one basic event of operation failure in the cut set, the basic event "Year" is directly added with a value of 365; b) When there are two or more basic events of operation failure in the cut set, in addition to adding the basic event "Year", the operation time correction factor needs to be added. The calculation formula of the operation time correction factor is: in, T_* is the running time correction factor, MTTR i is the repair time of the corresponding equipment class, N is the number of basic events of operation failure in the cut set; 1.4) Give the probability of occurrence of each basic event, and calculate and analyze the importance and sensitivity of each basic event; (2) Based on the cut sets selected in step 1.2), the power generation risk calculation for each cut set is completed: 2.1) Based on the equipment type, equipment failure mode and power reduction group information in the cut set, calculate the power generation recovery time of each corresponding cut set; 2.2) Based on the content of the cut set, calculate the power generation loss time factor of each corresponding cut set.

2. The cut set post-processing method for the nuclear power plant availability model according to claim 1, characterized in that: The relevant indicators for importance calculation in step 1.4) include: Importance FV, Risk increase factor RIF, Risk reduction factor RDF, Where MCS is the minimum cut set, i is the basic event, Φ is the total number of cut sets, P(MCS 含部件i ) represents the failure probability of the minimum cut set containing component i, P(Φ) represents the failure probability of the top event, P(Φ Xi＝0 ) means that when the basic event X i The probability of the top event occurring when it is very reliable, P(Φ Xi＝1 ) means that when the basic event X i The probability of the top event occurring at a certain failure time.

3. The cut set post-processing method for the nuclear power plant availability model according to claim 1, characterized in that: The power generation recovery time described in step 2.1) is the repair time corresponding to all basic events in the cut set including the repair time of the power reduction group.

4. The cut set post-processing method for the nuclear power plant availability model according to claim 1, characterized in that: The calculation formula of the power generation loss time factor in step 2.2) is as follows: When the corresponding power reduction group is DC01, DC02, DC03, LT=P×TF×RT×DS When the corresponding power reduction group is not DC01, DC02, or DC03, LT=P×TF×RT Among them, DC01 indicates that the power reduction is greater than 75%, DC02 indicates that the power reduction is greater than 25% and less than 50%, DC03 indicates that the power reduction is less than 25%, LT is the power generation loss time factor, P is the failure rate corresponding to the cut set, TF is the time factor corresponding to the cut set, RT is the repair time corresponding to the cut set, and DS is the power reduction coefficient corresponding to different power reduction groups.

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