A method for confirming functional restoration guidelines based on the best estimate system procedure

Abstract

The present invention belongs to the technical field of nuclear power plant operation, and relates to a method for confirming functional recovery guidelines based on a best estimate system program. The confirmation method comprises the following steps in sequence: (1) analyzing typical operating conditions for selecting functional recovery guidelines for confirmation; (2) determining monitoring parameters for screening and calculating the best estimate system program; (3) calculating the operating condition characteristics based on the best estimate system program; (4) analyzing the envelope operating conditions for functional recovery guideline confirmation; (5) confirming the functional recovery guideline operation response; (6) formulating a non-conforming item handling plan and performing corresponding processing; (7) modifying the guideline according to the non-conforming item processing results. The functional recovery guideline confirmation method based on the best estimate system program of the present invention can systematically and comprehensively test whether the designed functional recovery guidelines can correctly diagnose and effectively handle all accident conditions that should be considered.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power plant operation, and relates to a function recovery guideline confirmation method based on a best estimation system program. Background Art

[0002] The Nuclear Power Plant Accident Handling Guidelines are the guiding documents for the Accident Handling Procedures (EOPs), which describe the accident handling strategies and the relevant information required for the preparation of accident procedures. Therefore, they are important design documents related to the safety of nuclear power plants.

[0003] In the field of nuclear power, there are three types of accident handling procedures widely used internationally, namely event-oriented method, state-oriented method and symptom-oriented method. Among them, the symptom-oriented method is based on the probability theory method of accident analysis, and uses several safety-related parameters as symptoms to supervise the safety of nuclear power plants. It can effectively handle complex conditions and superimposed accidents, so it is an advanced type of accident handling procedure method in the world. And according to the provisions of my country's nuclear safety guideline HAD103 "Nuclear Power Plant Operation Safety Guidelines", symptom-oriented accident procedures are preferred to handle design basis accidents and design expansion conditions. In order to better reflect the advanced nature and safety, the third-generation nuclear power units independently developed by my country currently use the symptom-oriented method to develop accident handling guidelines and accident handling procedures.

[0004] The development process of symptom-based incident handling guidelines is generally divided into the following stages:

[0005] (1) Accident analysis based on symptom-based accident handling guidelines;

[0006] (2) Design of symptom-based accident handling guidelines;

[0007] (3) Verification of symptom-driven accident handling guidelines;

[0008] (4) Confirmation of symptom-based accident handling guidelines, etc.

[0009] Furthermore, based on the symptom-based accident handling guidelines developed above, combined with human factors engineering requirements and operation organization, the development of symptom-based accident handling procedures used in the main control room of a nuclear power plant was carried out.

[0010] The symptom-oriented accident handling guidelines include the best recovery guidelines and the functional recovery guidelines. The best recovery guidelines directly deal with single accidents with typical event signs or relatively simple multiple accidents, and the functional recovery guidelines are used to deal with complex multiple accidents that threaten safety functions. The functional recovery guidelines are guided by the key function status tree. The key function status tree is designed with red, orange, yellow, and green paths, corresponding to different degrees of critical function (CSF) deterioration. Green means no deterioration of the critical function, and yellow, orange, and red are the increasing degrees of deterioration of the critical function.

[0011] After completing the draft design of the symptom-oriented EOP guidelines for nuclear power plants, it is necessary to further confirm that the goals set at the beginning of the design have been achieved from a perspective closer to the actual comprehensive operational response of the nuclear power plant, that is, to confirm that the SEOP (symptom-oriented accident procedure) guideline system can fully cover all accidents in the SEOP initial event list determined at the beginning of the design, and can successfully handle and mitigate the corresponding accidents. This requires that the SEOP guidelines can be proved through confirmation work to correctly diagnose these accidents and bring the nuclear power plant into a safe state through the strategies in the guidelines.

[0012] However, from a design perspective, the symptom-oriented accident handling guidelines can handle both design basis accidents and a large number of design expansion conditions. Therefore, the list of initiating events determined at the beginning of the design often contains hundreds or even thousands of initiating events. If these initiating events are analyzed and confirmed one by one using a computing platform based on the best estimate program, it will result in an almost unacceptable workload. Therefore, how to correctly diagnose and handle these accidents by systematically and comprehensively verifying the designed symptom-oriented EOP guidelines has become an urgent problem that needs to be solved. Summary of the invention

[0013] The purpose of the present invention is to provide a function recovery guideline confirmation method based on the best estimation system program, so as to be able to systematically and comprehensively check whether the designed function recovery guideline can correctly diagnose and effectively handle all accident conditions that should be considered.

[0014] To achieve this object, in a basic implementation scheme, the present invention provides a method for confirming a functional recovery guideline based on a best estimate system program, wherein the confirmation method comprises the following steps in sequence:

[0015] (1) Analyze the typical operating conditions confirmed by the selected functional recovery guidelines;

[0016] (2) determine the monitoring parameters for the best estimate system program screening calculations;

[0017] (3) Calculation of operating characteristics based on the best estimation system procedure;

[0018] (4) Analyze the envelope conditions confirmed by the functional recovery guidelines;

[0019] (5) Functional recovery guideline operation response confirmation;

[0020] (6) Develop a plan to handle non-conformities and handle them accordingly;

[0021] (7) Modify the guidelines based on the results of handling non-conformities.

[0022] In a preferred embodiment, the present invention provides a method for confirming functional recovery guidelines based on a best estimate system program, wherein in step (1), a list of operating conditions that need to be covered by integrity confirmation is defined based on the design basis of the nuclear power plant and relevant operating experience, and unnecessary operating conditions are eliminated based on the scope of application of the accident handling guidelines.

[0023] In a more preferred embodiment, the present invention provides a method for confirming functional recovery guidelines based on a best estimation system program, wherein in step (2), the parameters to be monitored during the working condition calculation process of step (1) are determined.

[0024] In a preferred embodiment, the present invention provides a method for confirming functional recovery guidelines based on a best estimate system program, wherein step (3) includes basic operating condition calculations for non-multiple accidents and multiple accident calculations for superimposed faults.

[0025] In a preferred embodiment, the present invention provides a method for confirming functional recovery guidelines based on a best estimation system program, wherein in step (4), in the diagnostic result list, the initial events covered by the guidelines are grouped; after grouping, envelope analysis and envelope working condition selection are performed on the events within the group based on the calculated curve.

[0026] In a more preferred embodiment, the present invention provides a method for confirming a function recovery guideline based on a best estimation system program, wherein the principle for selecting the envelope working condition is:

[0027] The specific initial events and initial plant states that have the greatest impact on process system disruption;

[0028] The most restrictive combination of device failures in responding to a challenge.

[0029] In a preferred embodiment, the present invention provides a method for confirming function recovery guidelines based on a best estimation system program, wherein in step (5), the correctness and availability of the working condition selected in step (4) are confirmed according to the function recovery guidelines.

[0030] In a preferred embodiment, the present invention provides a method for confirming functional restoration guidelines based on a best estimate system program, wherein step (5) uses a computing platform based on a best estimate thermal-hydraulic analysis program.

[0031] In a preferred embodiment, the present invention provides a method for confirming functional recovery guidelines based on a best estimate system program, wherein in step (7), the guideline document is modified based on the non-conformities finally determined to be found in all confirmation work and the solutions determined after the analysis of the non-conformities.

[0032] The beneficial effect of the present invention is that, by using the function recovery guideline confirmation method based on the best estimation system program of the present invention, it is possible to systematically and comprehensively check whether the designed function recovery guideline can correctly diagnose and effectively handle all accident conditions that should be considered.

[0033] The beneficial effects of the present invention are specifically embodied in:

[0034] (1) The method of the present invention can confirm the integrity of the operating conditions covered by the symptom-oriented EOP guidelines, and first confirm that a large number (hundreds or even thousands) of initiating events in the initiating event list can be successfully diagnosed.

[0035] (2) The method of the present invention can confirm the correctness of the technical content of the symptom-oriented EOP guidelines. By applying the processing strategy in the guidelines to the envelope operating conditions, it is confirmed that all groups of initiating events (dozens or even hundreds) that can be covered by the envelope operating conditions can be successfully processed.

[0036] (3) The preconditions on which the method of the present invention is based are all technical conditions that can be met by current technical means, and the best estimation procedure is relatively mature. The design basis of the symptom-oriented EOP guidelines is that the accident handling strategy can be based on symptoms without paying attention to the initial event.

[0037] (4) Through the method of the present invention, a large amount of computational analysis and confirmation work can be reduced to the analysis and confirmation work of the envelope conditions whose symptoms are representative. The method of the present invention is a general method for analyzing symptom-oriented EOP design initiating events. Through the method of the present invention, it can be proved that the operations in the recovery guidelines can handle all initiating events that are not as severe as the envelope conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The flowchart of the function recovery guideline confirmation method based on the best estimation system program of the present invention is exemplified. DETAILED DESCRIPTION

[0039] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings.

[0040] Confirmation of accident handling guidelines, especially functional recovery guidelines, includes operating condition selection analysis, best estimation system program platform setting, best estimation system program platform operation calculation (operational intervention according to accident handling guidelines), data observation and screening, data processing and analysis, and confirmation result evaluation.

[0041] The method route of the present invention is as follows:

[0042] According to the objectives of the aforementioned confirmation work, in order to ensure the completeness of the coverage of the guidelines, it is necessary to ensure the applicability and diagnosability of all accidents in the SEOP initiating event list and confirm the effectiveness of the functional recovery guidelines.

[0043] The process of the exemplary function recovery guideline confirmation method based on the best estimation system program of the present invention is as follows: Figure 1 As shown, the following steps are included in sequence.

[0044] 1. Analyze the typical working conditions confirmed by the selected functional recovery guidelines

[0045] Based on the design basis of the nuclear power plant and relevant operating experience, a list of operating conditions that need to be covered by integrity confirmation is defined, and unnecessary operating conditions are eliminated based on an analysis of the scope of application of the accident handling guidelines.

[0046] 2. Determine the monitoring parameters for the best estimation system program screening calculation

[0047] Determine the parameters that need to be monitored during the working condition calculation in step 1. In order to meet the purpose of the confirmation work in this stage, the parameters that need to be monitored in the integrity confirmation stage are mainly CSF parameters.

[0048] After that, the following step 3 shall be performed for all events in the load condition list of step 1. Among them, step 3.1 is applicable to the design basis accident load condition in the load condition list that can be covered by the best recovery guidelines; step 3.2 is applicable to the design extension load condition other than the event of executing step 3.1.

[0049] 3. Calculation of operating characteristics based on the best estimation system program

[0050] 3.1 Basic working condition calculation without multiple accidents

[0051] The calculation steps for the basic operating condition without multiple accidents are as follows:

[0052] (1) Design basis accident conditions in the list of conditions in step 1;

[0053] (2) The automatic action system responds without damage and there is no operator operation;

[0054] (3) performing calculations using a computing platform based on the Best Estimation System program;

[0055] (4) Record the changes in the CSF parameters determined in step 2. The calculation results are used to apply the diagnostic guidelines in the functional recovery guidelines to confirm the green path of the critical safety state tree.

[0056] 3.2 Multiple Accident Calculation of Superimposed Faults

[0057] The characteristics of multiple accident calculations for superimposed faults are as follows:

[0058] (1) Design expansion conditions other than the design basis accident conditions in the list of conditions in step 1;

[0059] (2) No operator intervention;

[0060] (3) performing calculations using a computing platform based on the Best Estimation System program;

[0061] (4) The calculation process continues until the loss of critical safety functions and / or FPB (fission product barrier) damage occurs;

[0062] (5) Record changes in CSF parameters identified in step 2 to diagnose events and / or identify loss of critical safety functions;

[0063] (6) Apply the diagnostic guidelines in the functional restoration guidelines to confirm the entry criteria for the red, orange, and yellow paths of the CSF response tree.

[0064] After completing the above work, a complete list of diagnostic results for all events in the functional recovery guidelines will be obtained.

[0065] 4. Analyze the envelope conditions confirmed by the functional recovery guidelines

[0066] In the diagnostic result list, the initial events covered by the functional recovery guidelines are grouped; after grouping, envelope analysis and envelope working condition selection are performed on the events in the group based on the calculated curve.

[0067] The selection principles of the above enveloping working conditions are as follows:

[0068] (1) The specific initial events and initial plant states that have the greatest impact on the process system;

[0069] (2) The most restrictive combination of device failures in response to the above challenges.

[0070] 5. Functional recovery guidelines and operational response confirmation

[0071] For the envelope conditions selected in step 4, confirm the correctness and availability according to the functional recovery guidelines.

[0072] (1) Use a computing platform based on a best estimate thermal-hydraulic analysis program;

[0073] (2) Operation envelope calculations, taking into account operator actions according to functional recovery guidelines, to confirm that these actions can restore critical safety functions and ultimately prevent FPB damage;

[0074] (3) Comparison with the corresponding failure situation in step 3.2, including: successful recovery of key symptoms; reaching the parameter value that returns to the normal procedure;

[0075] (4) Determine the effectiveness of functional recovery strategies to avoid FPB damage.

[0076] 6. Develop a solution for the non-conformities found in step 5 and handle them accordingly

[0077] 7. Modify the guidelines based on the results of non-conformance handling

[0078] The guidance document will be modified based on the final non-conformities identified and the solutions determined after the non-conformities are analyzed.

[0079] The application of the above exemplary method for confirming the function recovery guideline based on the best estimation system program of the present invention is exemplified as follows (taking the confirmation process of the secondary side heat sink loss guideline FR-H.1 as an example).

[0080] Step 1: Prepare the analysis and select the typical operating conditions confirmed by the functional restoration guidelines as follows:

[0081]

[0082] Step 2: Determine the best estimate for the conditions prepared in the previous step System procedure screens the calculated monitoring parameters

[0083] Step 3: Perform calculations on the verification platform until the critical safety functions are lost and / or FPB (fission product barrier) damage occurs. After the diagnosis of the diagnostic procedure, the following list of diagnostic results is obtained:

[0084]

[0085] Step 4: Analyze the envelope conditions confirmed by the functional restoration guidelines

[0086] Grouping by diagnosis:

[0087] FR-H.1 Group:

[0088]

[0089]

[0090] FR-C.1 Group…

[0091] E-3 Group…

[0092] Based on the calculated curve, envelope analysis is performed on the events within the group.

[0093] The selection principles of the enveloping working condition are as follows:

[0094] (1) The specific initial events and initial plant states that have the greatest impact on the process system;

[0095] (2) The most restrictive combination of device failures in response to the above challenges.

[0096] After analysis, the following list of envelope conditions is obtained, one envelope condition for each group:

[0097] Serial number Envelope Events Group 1 The main water supply is lost and the auxiliary water supply is unavailable at the same time FR-H.1 2 Large LOCA superimposed injection is not available FR-C.1 3 … …

[0098] Step 5: Perform operator operation suitability confirmation for the envelope condition, and record the confirmation results and various data calculated during the confirmation process.

[0099] Step 6: Develop a plan to handle non-conformities and handle them accordingly

[0100] Step 7: Modify the guidelines based on the results of the non-conformance handling

[0101] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and variations. The above-mentioned embodiments are merely illustrative of the present invention, and the present invention may also be implemented in other specific ways or other specific forms without departing from the gist or essential features of the present invention. Therefore, the described embodiments should be considered illustrative rather than restrictive in any respect. The scope of the present invention shall be described by the appended claims, and any changes equivalent to the intent and scope of the claims shall also be included within the scope of the present invention.

Claims

1. A method for confirming functional recovery guidelines based on a best estimate system procedure, characterized in that: The confirmation method comprises the following steps in sequence: (1) Analyze the typical operating conditions confirmed by the selected functional recovery guidelines; (2) determine the monitoring parameters for the best estimate system program screening calculations; (3) Calculation of operating characteristics based on the best estimation system procedure; (4) Analyze the envelope working conditions confirmed by the functional recovery guidelines. In the diagnostic result list, group the initial events covered by the guidelines. After grouping, perform envelope analysis and envelope working condition selection on the events in the group according to the calculated curve. The principle of envelope working condition selection is: The specific initial events and initial plant states that have the greatest impact on process system disruption; The most limiting combination of equipment failures in responding to a challenge; (5) Functional recovery guideline operation response confirmation: for the selected working conditions, correctness and availability are confirmed according to the functional recovery guideline; (6) Develop a plan to handle non-conformities and handle them accordingly; (7) Modify the guidelines based on the results of handling non-conformities.

2. The confirmation method according to claim 1, characterized in that: In step (1), a list of operating conditions to be covered by integrity confirmation is defined based on the design basis of the nuclear power plant and relevant operating experience, and unnecessary operating conditions are eliminated based on the scope of application of the accident handling guidelines.

3. The confirmation method according to claim 2, characterized in that: In step (2), the parameters to be monitored during the working condition calculation process of step (1) are determined.

4. The confirmation method according to claim 1, characterized in that: Step (3) includes the basic operating condition calculation of non-multiple accidents and the multiple accident calculation of superimposed faults.

5. The confirmation method according to claim 1, characterized in that: Step (5) uses a computing platform based on a best estimate thermal-hydraulic analysis program.

6. The confirmation method according to claim 1, characterized in that: In step (7), the guideline document is modified based on the non-conformities found in all the confirmation work and the solutions determined after the analysis of the non-conformities.

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