A method for efficient and dynamic coupling analysis of discrete dynamic event trees with nuclear simulation programs

Abstract

The application discloses a kind of discrete dynamic event tree and nuclear simulation program efficient parallel dynamic coupling analysis method, this method includes: constructing discrete dynamic event tree DET simulation model, determine nuclear simulation program simulation time and run, according to nuclear simulation program simulation result analysis obtains the time information of all DET simulation object state transition control TRIP variable change, and according to DET simulation model branch rule obtains the restart time and restart number of nuclear simulation program backtracking restart of all DET simulation objects of current accident sequence, judge whether restart time and parent sequence restart time are identical, update the failure restart file as input, copy necessary restart input file in parent sequence to current folder, according to branch number backtracking executes multi-thread parallel simulation to complete the simulation of all DET failure branches.This method makes up the deficiency of traditional safety analysis method in handling the time sequence dynamic response of nuclear power plant accident process, and multi-thread parallel computing mode also improves the calculation efficiency.

Description

Technical Field

[0001] The technical solution of this application belongs to the field of nuclear science and engineering technology, and in particular, it is a method for efficient and accurate nuclear power plant safety analysis by using discrete dynamic event tree and nuclear simulation program for efficient parallel dynamic coupling calculation when performing safety analysis on the operation of nuclear power facilities (nuclear power plants). That is, a method for efficient parallel dynamic coupling analysis of discrete dynamic event tree and nuclear simulation program. Background Technology

[0002] Nuclear power plant safety is the most critical aspect of its operation. Safety analysis and assessment must be conducted during the design and construction of nuclear power facilities and systems. Common analysis and assessment methods are divided into two types: deterministic safety analysis and probabilistic safety evaluation. Deterministic safety analysis generally employs nuclear simulation software, while probabilistic safety evaluation is based on traditional event tree / fault tree methods. Using only deterministic or probabilistic methods has significant limitations in analyzing the dynamic characteristics of nuclear power plant accidents. To address the shortcomings of traditional deterministic and probabilistic safety analysis methods in time-series dynamic analysis, the Discrete Dynamic Event Tree (DDET) method was proposed and used to simulate the dynamic response process under nuclear power plant accident conditions.

[0003] In deterministic safety analysis of nuclear power plants, the Discrete Dynamic Event Tree (DET) method requires significant computational resources and generates substantial data. Therefore, the traditional method of manually setting boundary conditions is no longer sufficient. Consequently, a nuclear power plant safety analysis method, technical solution, and analytical tool that automatically couples the DET method with deterministic analysis software is needed. This would enable dynamic simulation of the accident evolution process of nuclear power plants under probabilistic conditions, yielding information on the plant's safety redundancy characteristics and safety performance. Existing DET and nuclear accident simulation programs typically employ an iterative approach with specific time steps, i.e., a breadth-first search method. However, inappropriate time step settings can lead to low computational efficiency and large storage requirements. Furthermore, when using the DET method for accident analysis, a detailed DET model is built to comprehensively simulate the changes in the nuclear power plant's state under an accident, resulting in numerous branches. Nuclear simulation programs are typically single-threaded software, allowing only one input file for a single simulation. Simulating multiple accidents requires repeated calls. In the coupled computation process of the kernel simulation program and the DET method, if only single-threaded computation is performed each time, it will result in an unbearable time cost. Therefore, the improvement is to use multi-threaded parallel computation. Simultaneously calling multiple kernel simulation programs can effectively reduce computation time and improve computational efficiency.

[0004] This application proposes an improvement on the nuclear simulation program and DET coupling calculation method based on this, while adopting a parallel mode to improve the efficiency of nuclear power plant safety analysis. Summary of the Invention

[0005] To address the aforementioned issues and overcome the limitations of iterative methods and single-threaded computation, this invention provides an efficient parallel dynamic coupling analysis method based on discrete dynamic event trees and kernel simulation programs. This method employs a parallel analysis approach based on dynamic characteristics, offering greater versatility and wider applicability. It only requires distinguishing between variable-type and logical-type state transitions of the DET simulation object; it eliminates the need for special handling of single or multiple transitions and logical judgments of transition conditions. Furthermore, the calculation utilizes a depth-first approach instead of a breadth-first approach, eliminating iterative backtracking and simplifying the analysis process to improve efficiency.

[0006] This application achieves the above-mentioned objective through the following technical solution: a highly efficient parallel dynamic coupling analysis method based on discrete dynamic event trees and kernel simulation programs, the method comprising the following steps:

[0007] S1. Construct a Discrete Dynamic Event Tree (DET) simulation model. Based on the state transition type of the DET simulation object, modify the TRIP card in the nuclear simulation program input file by adding general auxiliary TRIP variables. These general auxiliary TRIP variables can be variable-type or logic-type. The DET simulation object here represents a nuclear power plant system, equipment, or personnel operation. The state transition of the DET simulation object is controlled by the TRIP variables. The logic values ​​of the TRIP variables are True and False. The space vector of the TRIP variables of the DET simulation object... Where n is the number of DET simulation objects, s i This represents the TRIP logic value corresponding to the i-th DET simulation object; that is...

[0008] S2. Determine the simulation time of the nuclear simulation program and run it until the simulation ends. The simulation file that has been calculated is used as the parent sequence file. At this time, the DET simulation object is the analysis object of the nuclear power plant initiation accident. The initial program input card file for simulating the nuclear power plant accident is programmed according to the deterministic analysis method. The input card file includes the initial input file Root.input and the initial restart calculation file R0.input. Wherein, "Root" represents any file name that meets the program requirements, "R0" represents the file name, and ".i" represents the file type. This part is a necessary part of the coupling between the nuclear simulation program and DET. The TRIP card of the DET simulation object in the Root.input file is modeled in the way of general auxiliary variables, which simplifies its content. The aforementioned initial restart calculation file R0.input includes ① program restart control card; ② program time step control card. This part is a necessary part of the coupling between the nuclear simulation program and DET. The TRIP card of the DET simulation object in the Root.input file needs to be modeled in the way of general auxiliary variables, which simplifies its content.

[0009] S3. Based on the simulation result file currently output by the nuclear simulation program, parse the simulation result file to obtain the time information of the state transition control TRIP variable changes of all DET simulation objects;

[0010] S4. Identify the DET branch times when state transitions of all DET simulation objects occur; the specific method for identifying the DET branch times when state transitions of DET simulation objects occur is as follows: Step ①: Obtain the time information of the change of the TRIP variable controlling the state transition of the DET simulation object according to step S3; Step ②: Obtain the TRIP trigger time of the state transition of all DET simulation objects in the current parent sequence accident by parsing the simulation result file, and then obtain the restart time of the core simulation program corresponding to the number of the backtracking restart information block of the core simulation program according to the branching rules of the DET simulation model; In traditional analysis methods, the core simulation program is an encapsulated tool software that does not interact with the outside world within a simulation time step, so the DET branch nodes can only be determined by parsing each simulation output result and using the above number; This method automatically and accurately identifies the DET branch points and branch times that need to be modified in the output results through the overall simulation to the end time, and generates the TRIP card state transition failure branch through the restart card and auxiliary variables at the corresponding branch time, avoiding the repeated calculation of the successful state transition branch and the backtracking calculation within each step;

[0011] S5. Based on the branching rules of the DET simulation model, obtain the restart time and restart number of the kernel simulation program of all DET simulation objects in the current accident sequence; the method for obtaining the restart time and restart number of the DET simulation object is as follows: Step (1): According to the TRIP trigger time set {TRIPT1, TRIP2, ..., TRIPM obtained at the DET branch time, ... i}, where M i To determine the number of TRIPs required for DET branches in the parent sequence, branch information is obtained sequentially based on trigger time. The trigger time (TRIPTime) and its corresponding TRIP number are identified. Finally, all triggered TRIP numbers and their corresponding trigger times ({TRIPTime1, TRIPTime2, ..., TRIPTimeM) are retrieved from the simulation results. i};

[0012] Step (2): Determine whether the DET simulation object corresponding to TRIPTime is a single state transition type. If so, proceed to step (4); otherwise, proceed to step (3).

[0013] Step (3): The DET simulation object may undergo multiple state transitions. Analyze all restart information blocks in the simulation result file to obtain the time when the DET branch simulation object undergoes its first state transition, and assign it to TRIPTime. Then execute step (4).

[0014] Step (4): Replace {TRIPT1, TRIPT2, ..., TRIPT M} with TRIPTime i Find the corresponding element in}, and then execute step (5);

[0015] Step (5): Calculate the DET backtracking restart information block number BloNum; BloNum is calculated using the following formula:

[0016] Δt = CpuTime max ×ResFre

[0017]

[0018] in:

[0019] BloNum: The number of the kernel simulation program backtracking restart information block calculated based on the TRIP trigger time TRIPTime of the state transition of the DET simulation object.

[0020] CpuTime max The maximum CPU simulation step time is located in the time control card of the nuclear simulation program input card.

[0021] INT[]: Integer function;

[0022] ResFre: Restart frequency of the time control card in the kernel simulation program input card;

[0023] TRIPTime: Trip trigger time for state transition of the DET simulation object in the simulation results;

[0024] △t: The time interval between the two restart information blocks in the time control card of the nuclear simulation program input card;

[0025] After the calculation is completed, obtain the restart numbers {BloNum1, BloNum2, ..., BloNumM} corresponding to all TRIP trigger cards in the current sequence. i};

[0026] Step (6): Perform M on the number of DET branches i In the next loop, corresponding branches are generated sequentially based on the order of TRIP trigger times;

[0027] The above steps can automatically and accurately identify the moment when the state transition of the DET simulation object occurs, thereby determining the restart time of the nuclear simulation program;

[0028] S6. Determine if the restart time of the current sequence is the same as the restart time of the parent sequence. If they are different, copy and generate a restart input file for the kernel simulation program to calculate all failed branches in the current accident sequence based on an initial input file containing all the required information for restart calculation. Determine the state transition type of the DET simulation object and update the restart input file for the kernel simulation program. The update of the restart input file here requires performing DET simulation object state transitions for existing DET branches. The update method for the restart file at this time is as follows: Step 1: Update the restart number in the restart input file of the current node kernel simulation program to ResNum. ResNum is the restart number corresponding to the kernel simulation program backtracking restart information block number BloNum; Step 2: The simulation time card information remains unchanged; Step 3: Update the DET simulation object state transition failure control TRIP information; If when The restart time of the preceding sequence is the same as that of the parent sequence. The restart input file of the parent sequence is copied, and the state transition type of the DET simulation object is determined based on this. The restart input file of the kernel simulation program is then updated. In this step, the multi-threaded parallel computation requires the kernel simulation program's restart function. Generally, a kernel simulation program with restart computation function will generate an output file for storing output data after the simulation ends. The restart computation process requires the restart input file and the output file of the parent sequence simulation computation as a basis. The restart input file is generated through a branching process, and the output file is generated by copying the parent sequence output file to each child sequence folder. The kernel simulation program is generally a single-threaded simulation program, that is, each computation can only input one file. By storing the branch file call information in the computation queue, if the computation queue is not empty, the computation is continuously called to achieve the parallel computation function.

[0029] S7. Using the updated failed restart file as input, copy the necessary restart input files from the parent sequence to the current folder, and backtrack according to the number of branches to perform multi-threaded parallel simulation to complete the simulation of all DET failed branches.

[0030] S8. Using the failed branch as the new parent sequence, determine whether a new DET branch is generated based on the simulation results of the failed branch. If so, repeat steps S5-S8. If no new DET branch is generated, the simulation ends.

[0031] The failure branch is the branch where the state transition of the DET object fails, and the success branch is the branch where the state transition of the DET object succeeds.

[0032] The initial parent sequence is the branch of all DET objects that have successfully transitioned to their state. Based on the parent sequence, subsequent failed branches, i.e., sub-sequences, are simulated according to the obtained output information.

[0033] The above technical solution simplifies the setting process and method of DET simulation object state transition TRIP in the nuclear simulation program input file by adding auxiliary TRIP variables and using a depth-first method, thereby reducing complexity, reducing step-by-step iterative steps, and improving analysis efficiency.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) Based on the dynamic coupling of discrete dynamic event tree method and nuclear simulation program, this invention can automatically obtain a large number of nuclear power plant accident simulation results, make up for the shortcomings of traditional safety analysis methods in handling nuclear power plant accidents in terms of time-series dynamic response, thereby obtaining the safety characteristics of nuclear power plant under accident conditions, providing support for risk-guided nuclear power plant design, operation and management decision support, optimizing nuclear power plant design, operation and management, and improving the safety and economy of nuclear power plants;

[0036] (4) Compared with the breadth-first step-by-step backtracking DET branching method, this method adopts the depth-first approach. Each branch simulation ends at the end of the current sequence before generating a new sequence, avoiding repeated calculations within each simulation step and improving computational efficiency.

[0037] (5) Multi-threaded parallel computing improves computational efficiency;

[0038] (6) This method has wide applicability and can simulate the transition of most nuclear power plant systems, equipment, and personnel operating states and the change of system process parameters during nuclear power plant accident analysis.

[0039] (7) This method is highly versatile and can be used for dynamic performance analysis of nuclear power plant accidents and transients. It is also applicable to the performance analysis of other complex systems that can be simulated using nuclear simulation programs. Attached Figure Description

[0040] Figure 1 This is a flowchart of the efficient parallel dynamic coupling analysis method based on discrete dynamic event tree and kernel simulation program in this application;

[0041] Figure 2 A schematic diagram of the DET model structure for the state evolution of a nuclear power plant;

[0042] Figure 3 This is a schematic diagram illustrating the dynamic coupling between DET and the program;

[0043] Figure 4 A schematic diagram of a single state transition for a DET simulation object;

[0044] Figure 5 This is a schematic diagram of multiple state transitions of the DET simulation object. Detailed Implementation

[0045] To more clearly illustrate the security analysis method of this application, the technical solution of this application is described below with reference to the accompanying drawings.

[0046] The dynamic characteristic analysis method based on the coupling of discrete dynamic event tree and kernel simulation program has the following steps: Figure 1 As shown, it includes the following steps:

[0047] S1. Construct a discrete dynamic event tree (DET) simulation model. Based on the state transition type of the DET simulation object, modify the TRIP card in the kernel simulation program input file by adding general auxiliary TRIP variables. The general auxiliary TRIP variables can be either variable type or logical type.

[0048] S2. Determine the simulation time of the kernel simulation program and run it until the simulation ends, using the completed simulation file as the parent sequence file;

[0049] S3. Based on the simulation result file currently output by the nuclear simulation program, parse the result file to obtain the time information of the state transition control TRIP variable changes of all DET simulation objects;

[0050] S4. Identify the DET branch times when state transitions occur for all DET simulation objects;

[0051] S5. Based on the branching rules of the DET simulation model, obtain the restart time and restart number of the kernel simulation program of all DET simulation objects in the current accident sequence.

[0052] S6. Determine whether the restart time of the current sequence is the same as the restart time of the parent sequence. If they are different, use an initial input file containing all the required information for restart calculation as a basis to generate a restart input file for the nuclear simulation program to calculate all failed branches in the current accident sequence. Determine the state transition type of the DET simulation object and update the restart input file for the nuclear simulation program.

[0053] S7. If the current sequence restart time is the same as the parent sequence restart time, copy the input file with the parent sequence and write the current branch information on it.

[0054] S8. Using the updated failed restart file as input, copy the necessary restart input files from the parent sequence to the current folder, and backtrack according to the number of branches to perform multi-threaded parallel simulation to complete the simulation of all DET failed branches.

[0055] S9. The failed branch becomes the new parent sequence. Based on the simulation results of the failed branch, it is determined whether a new DET branch is generated. If so, steps S5-S8 are executed repeatedly. If no new DET branch is generated, the simulation ends.

[0056] Based on the above technical solution, the specific implementation principle of step S1 is as follows:

[0057] First, taking the nuclear power plant system, equipment, or personnel operations that need to be simulated as the DET simulation object, the following analysis is performed according to the DET analysis method:

[0058] like Figure 2 As shown in the figure, each node represents a specific state S of a nuclear power plant, which is composed of a combination of DET simulation object states. i The root represents the initial state S0 of the nuclear power plant during the dynamic coupling simulation of DET and the nuclear simulation program. The intermediate nodes represent different combinations of states of the nuclear power plant system and equipment. The terminal node represents a predefined absorption termination state of the nuclear power plant, such as reaching the core damage or stability state of the nuclear power plant.

[0059] When DET is dynamically coupled with the kernel simulation program, it will start from the root node. As time changes, the state of the DET simulation object will undergo random transitions. When the preset branching rule is reached, the "branch" generated at that moment represents a state transition of the simulation object. And the transition from the parent node to the child node represents a state transition of the simulation object.

[0060] When the state transition trigger condition of a DET simulation object is met, the state transition of the DET simulation object can only have two states: successful state transition and failed state transition. Root represents the root node. Starting from Root, the sequence of all DET simulation objects that have successfully transitioned is the initial parent sequence, numbered Root-f. The sub-sequence branches generated based on the initial parent sequence are Root-a1-f, Root-a2-f, and Root-a3-f, representing the initial parent sequence where the first DET simulation object failed to transition and other simulation objects succeeded, the second DET simulation object failed to transition and other simulation objects succeeded, and the third DET simulation object failed to transition and other simulation objects succeeded, respectively. After these three branches are calculated, they form the new parent sequence. With Root-a1-f as the parent sequence, the resulting subsequence branches include Root-a1-b1-f, which represents the first DET simulation object in the simulation result of the Root-a1-f parent sequence failing to transition to the state, while other simulation objects successfully transition to the state, and so on. The terminal node represents the termination of the coupling between DET and the kernel simulation program. The node name is encoded as "sequence name-f", and the system evolution process from the parent sequence to the subsequence is simulated and calculated by the kernel simulation program.

[0061] Based on the above solutions, such as Figure 2As shown, when DET is coupled with the kernel simulation program, calculations are performed between each node. Unlike the traditional event tree method, the timing of node branches in DET is determined by the physical process of the simulation, reducing the reliance on the analyst's experience or conservative engineering judgment in traditional methods.

[0062] Example

[0063] Based on the above technical solution, the specific implementation process of steps S2-S8 is as follows:

[0064] like Figure 3 As shown, the symbols shown in the figure are defined as follows:

[0065] BloNum: The kernel simulation program backtracking and restart information block number calculated based on the TRIP trigger time TRIPTime of the state transition of the DET simulation object.

[0066] CpuTimemax: The maximum CPU simulation step time in the time control card of the kernel simulation program input card;

[0067] ErrNum: The count of abnormal termination of the kernel simulation program;

[0068] MT: State transition task time of the running state transition DET simulation object;

[0069] NorNum: The normal time termination count for the kernel simulation program;

[0070] ResFre: Restart frequency of the time control card in the kernel simulation program input card;

[0071] ResNum: The restart number corresponding to the BloNum block number of the kernel simulation program's backtracking restart information block;

[0072] T: The task time of DET coupled simulation with the kernel simulation program, which is also the simulation termination time when the simulation finally ends;

[0073] TRIPTime: The TRIP trigger time for the state transition of the DET simulation object in the simulation results. It is updated to the TRIP trigger time of the next branch after the current DET branch is generated.

[0074] △t: Restart frequency in the time control card of the nuclear simulation program input card;

[0075] Combination Figure 3 The overall process of dynamic coupling between DET and the nuclear simulation program is explained as follows:

[0076] Step 1: Write the DET and nuclear simulation program coupled simulation accident analysis input file Root.input and the initial restart file R0.input;

[0077] Step 2: Based on the state transition type of the DET simulation object, modify the TRIP information in Root.input by adding auxiliary variables to form a new Root.input input file;

[0078] Step 3: At the DET root node, use the simulation accident analysis input file Root.input as the initial input file and run the program to perform simulation calculations;

[0079] Step 4: After the simulation ends, the generated result file contains all TRIP transfer information and restart information during the run. The calculation result of the Root.input file is the successful branch result where all DET branch states have been transferred normally, and it is also the initial parent sequence branch Root-f; the time information of the DET simulation object state control TRIP variable changes in the parsed result file is also included.

[0080] Step 5: Obtain all DET branch information of the parent sequence branch Root-f, and sort them according to the DET branch trigger time;

[0081] Step 6: Obtain the state transitions of all DET simulation objects {TRIP1, TRIP2...TRIPM} by parsing the parent sequence result file. i Trigger time {TRIPTime1, TRIPTime2, ..., TRIPTimeM} i Then, according to the rules, the kernel simulation program backtracks and restarts with the numbers {ResNum1, ResNum...ResNumM}. i};

[0082] Step 7: Based on the state transition category of the DET simulation object, update R0.input and generate the restart input files R0-a1.input, R0-a2.input, and R0-a3.input for all DET failed branches;

[0083] Step 8: Using the failed branch restart files R0-a1.input, R0-a2.input, and R0-a3.input, as well as the result file Root.output of the parent sequence Root-f, as input, perform parallel restart calculations for the failed branches. All failed branches are simultaneously called for parallel calculation. The sequence Root-a1-f is the branch where all other nodes have succeeded after the calculation of node R0-a1. Similarly, the sequence Root-a2-f is the result after the calculation of node R0-a2, and the sequence Root-a3-f is the result after the calculation of node R0-a3. The node output file names of DET are updated according to the rules.

[0084] Step 9: Using the generated failed branches Root-a1-f, Root-a2-f, and Root-a3-f as the new parent sequence, determine whether there is new DET branch information based on the simulation results of the failed branches. If there is, repeat steps 5 to 8. If no new branches are generated, end the simulation.

[0085] Based on the above scheme, in step 1, the analysis object of the nuclear power plant initiation accident is determined, and the initial nuclear simulation program input card file for simulating the nuclear power plant accident is programmed according to the deterministic analysis method. The input card file includes the initial input and output files Root.input, Root.output and the initial restart calculation file R0.input; where "Root" represents any file name that meets the requirements of the nuclear simulation program, "R0" represents the file name, and ".input" and ".output" represent the file type; and the initiation accident simulation model needs to be debugged and stabilized, and the analysis results of typical accident sequences should meet expectations.

[0086] In step 1, the nuclear simulation initial restart calculation file R0.input includes ① the nuclear simulation program restart control card; ② the nuclear simulation program time step control card; ③ other necessary information to ensure the normal operation of the restart file; specifically, as Figure 2 Combination Figure 3 Taking the first DET branch of the middle root node as an example:

[0087] Step 1: Obtain the time information of the change of the TRIP variable for the state transition control of the DET simulation object based on Step 4;

[0088] Step 2: Obtain the TRIP trigger time of the DET simulation object state transition by parsing the simulation result file, and then obtain the restart number corresponding to the backtracking restart information block number according to the branching rules of the DET simulation model.

[0089] Based on the above scheme, in step 2, the TRIP card information is modified using the auxiliary variable method for demand-type branches to achieve DET branch state transition; for operation-type branches, the time information in the original TRIP logic is replaced with task time MT.

[0090] Based on the above plan, Figure 2 Combination Figure 3 The first branch of the CNNC simulation program output file, which is the branch at time t1, illustrates the DET backtracking restart number identification method as follows:

[0091] Step (1): Based on the TRIP trigger time set {TRIPT1, TRIPT2, ..., TRIPTM} obtained from the DET branch time. i} where M is the number of TRIP cards that need to perform DET branches in the parent sequence. Based on the trigger time, branch information is obtained sequentially, identifying its trigger time TRIPTime and the corresponding TRIP number. All triggered TRIP numbers and their corresponding trigger times {TRIPTime1, TRIPTime2, ..., TRIPTimeM} are obtained from the simulation results. i};

[0092] Step (2): Determine whether the DET simulation object corresponding to TRIPTime is a single state transition type. If so, proceed to step (4); otherwise, proceed to step (3).

[0093] Step (3): The DET simulation object may undergo multiple state transitions. Analyze all restart information blocks in the simulation result file to obtain the time when the DET branch simulation object undergoes its first state transition, and assign it to TRIPTime. Then execute step (4).

[0094] Step (4): Replace {TRIPT1, TRIPT2, ..., TRIPTM} with TRIPTime i Find the corresponding element in} and then execute step (5).

[0095] Step (5): Calculate the DET backtracking restart information block number BloNum.

[0096] Based on the above scheme, BloNum is calculated using the following formula:

[0097] Δt = CpuTime max ×ResFre

[0098]

[0099] in:

[0100] BloNum: The backtracking restart information block number calculated based on the TRIP trigger time TRIPTime of the DET simulation object's state transition.

[0101] CpuTimemax: The maximum CPU simulation step time in the time control card of the kernel simulation program input card;

[0102] INT[]: Integer function;

[0103] ResFre: Restart frequency of the time control card in the kernel simulation program input card;

[0104] TRIPTime: The minimum TRIP trigger time for the state transition of the DET simulation object in the simulation calculation results of the kernel simulation program. It is updated to the TRIP trigger time of the next branch after the current DET branch is generated.

[0105] △t: The time interval between the two restart information blocks in the time control card of the nuclear simulation program input card.

[0106] After the calculation is completed, obtain the restart numbers {BloNum1, BloNum2, ..., BloNumMi} corresponding to all TRIP trigger cards in the current sequence.

[0107] Step (6): Perform M calculations based on the number of DET branches in the parent sequence. i In the next loop, corresponding branches are generated sequentially based on the order in which the TRIP is triggered.

[0108] Based on the above scheme, in step 7, the method for updating the nuclear simulation program restart file is to generate the failure branch of the state transition and the success branch of the original state at the branch node after the simulation ends. The success branch has been calculated, and only the restart file of the failure branch needs to be generated.

[0109] Specifically, regarding the state transition of the DET simulation object in the DET branch, the kernel simulation program restarts the file update method as follows:

[0110] Step 1: Update the restart number in the current node kernel simulation program restart input file to ResNum;

[0111] Step 2: The simulation time card information remains unchanged;

[0112] Step 3: Update the TRIP information for state transition failure control of the DET simulation object.

[0113] Based on the above scheme, for the general TRIP variables of demand-oriented branches, set them as variable or logical variables, and the specific settings are as follows:

[0114] If the DET simulation object's state transition control TRIP is of variable type, then the TRIP information is updated as follows:

[0115] CC1 controls the state transition judgment logic of the DET simulation object.

[0116] 1. If CC1 is detected as True and its state is about to change, the branching logic is as follows:

[0117] State unchanged: CC1 eternal truth logic

[0118] State transition: CC1 inherits the initial TRIP logic

[0119] All successful branches of state transitions do not need to be recalculated by generating a restart file by backtracking the restart number at branch time; the simulation result of the parent sequence is the successful branch of that node.

[0120] 2. If CC1 is detected to be False and the state is about to change, the branching logic is as follows:

[0121] State unchanged: CC1 perpetually false logic

[0122] State transition: CC1 inherits the initial TRIP logic

[0123] If the initial state of the DET simulation object is identified as true, the files for both branches will be updated as follows:

[0124] Previous branch (success branch, state transition branch): The parent sequence of the current branch node. It does not need to be calculated separately. Each generation of the parent sequence contains information about other successful branches.

[0125] Next branch (failed branch, non-transition branch): The subsequence generated by the current node branch, and add a line of TRIP information to the restart file according to the kernel simulation program rules.

[0126] CC1 controls the state transition judgment logic of the DET simulation object.

[0127] CC1 is the TRIP number for the initial DET simulation object's state transition control.

[0128] If the DET simulation object's state transition control TRIP is of logical type, then the TRIP information is updated as follows:

[0129] Auxiliary TRIP variable 1: Its logical value is a "true" constant;

[0130] Auxiliary TRIP variable 2: Its logical value is a "false" constant;

[0131] The TRIP logic of the CC1 single-demand state transition DET simulation object

[0132] Auxiliary TRIP variable 3: Original CC1 TRIP logic

[0133] 1. If CC1 is detected as True and its state is about to change, the branching logic is as follows:

[0134] State unchanged: CC1 auxiliary TRIP variable 3 or auxiliary TRIP variable 1

[0135] State transition: CC1 inherits the initial TRIP logic

[0136] 2. If CC1 is detected to be False and the state is about to change, the branching logic is as follows:

[0137] State unchanged: CC1 auxiliary TRIP variable 3 and auxiliary TRIP variable 2

[0138] State transition: CC1 inherits the initial TRIP logic

[0139] If the initial state of the DET simulation object is identified as true, the files for both branches will be updated as follows:

[0140] Previous branch (success branch, state transition branch): The parent sequence of the current branch node. It does not need to be calculated separately. Each generation of the parent sequence contains information about other successful branches.

[0141] Next branch (failed branch, non-transition branch): The subsequence generated by the current node branch, and add a line of TRIP information to the restart file according to the kernel simulation program rules.

[0142] CC1 auxiliary TRIP variable 3 or auxiliary TRIP variable 1

[0143] in

[0144] CC1: is the TRIP number for the initial DET simulation object's state transition control;

[0145] Auxiliary TRIP variable 3: Any auxiliary TRIP number that meets the requirements of the nuclear simulation program and satisfies independence and uniqueness.

[0146] Auxiliary TRIP variable 1: Auxiliary variable TRIP number, its logical value is always "true".

[0147] If the initial state of the DET simulation object is identified as false, the files for both branches will be updated as follows upon restart:

[0148] Previous branch (success branch, state transition branch): The parent sequence of the current branch node. It does not need to be calculated separately. Each generation of the parent sequence contains information about other successful branches.

[0149] Next branch (failed branch, non-transition branch): The subsequence generated by the current node branch, and add a line of TRIP information to the restart file according to the kernel simulation program rules.

[0150] CC1 auxiliary TRIP variable 3 and auxiliary TRIP variable 2

[0151] CC1: is the TRIP number for the initial DET simulation object's state transition control;

[0152] Auxiliary TRIP variable 3: Any auxiliary TRIP number that meets the requirements of the nuclear simulation program and satisfies independence and uniqueness.

[0153] Auxiliary TRIP variable 2: Auxiliary variable TRIP number, with a logical value that is always "false".

[0154] Among them, Auxiliary TRIP variable 1 is the number of a logical TRIP in the kernel simulation program. It is an additional auxiliary variable added to facilitate the dynamic coupling between DET and the kernel simulation program, and its logical pointer is always "true". In practical applications, any logical variable number that meets the requirements of uniqueness and independence can be used as needed, provided it meets the requirements of the kernel simulation program.

[0155] Auxiliary TRIP variable 2 is the number of a logical TRIP in the kernel simulation program. It is an additional auxiliary variable added to facilitate dynamic coupling between DET and the kernel simulation program, and its logical value is always "false". In practical applications, any logical variable number that meets the requirements of uniqueness and independence, as long as it satisfies the requirements of the kernel simulation program, can be used.

[0156] For runtime branches, replace the time information in the original TRIP logic with the task time (MT). The specific settings are as follows:

[0157] CC1 controls the state transition judgment logic of the DET simulation object.

[0158] 1. If it is detected that CC1 is about to change state, the branch logic is as follows:

[0159] Branch 1: CC1 inherits the initial TRIP logic

[0160] Branch 2: Change the CC1 task time to MT

[0161] Based on the number of task times (MT), multiple runtime failure branches can be generated.

[0162] Effect Example

[0163] Based on the accident characteristics and simulation computing resource conditions, initialize the relevant parameters for dynamic coupling between DET and the kernel simulation program, including:

[0164] BloNum: The number of the backtracking restart information block calculated based on the TRIP trigger time TRIPTime of the state transition of the DET simulation object, with an initial value of 0;

[0165] CpuTimemax: The maximum CPU simulation step time in the time control card of the core simulation program input card. The initial value is user-defined.

[0166] ErrNum: The count for abnormal termination of the kernel simulation program, with an initial value of 0;

[0167] MT: The state transition task time of the running state transition DET simulation object. The number of task time random variables required is determined according to the number of running state transition objects involved, and each task time random variable is discretized according to the user-defined discretization method to obtain a discrete task time series.

[0168] NorNum: The normal time termination counter for the kernel simulation program, with an initial value of 0;

[0169] ResFre: Restart frequency of the time control card in the kernel simulation program input card, user-defined;

[0170] ResNum: The restart number corresponding to the backtracking restart information block number BloNum, with an initial value of 0;

[0171] T: The task time of DET coupled simulation with the kernel simulation program, which is also the simulation termination time. The initial value is user-defined.

[0172] TRIPTime: The TRIP trigger time for the state transition of the DET simulation object in the simulation results. The initial value is 0, and it is updated to the TRIP trigger time of the next branch after the current DET branch is generated.

[0173] △t: Restart frequency in the time control card of the nuclear simulation program input card; initial value is user-defined.

[0174] like Figure 3 As shown, the specific dynamic coupling process between DET and the kernel simulation program is as follows:

[0175] Step 1: Place the initial kernel simulation program input file Root.input and the initial restart file R0.input of the DET root node as a pair of files into the calculation queue;

[0176] Step 2: Determine if the kernel simulation program input file exists in the calculation queue. If the kernel simulation program input file exists, determine the number of input files in the calculation queue, and perform multi-threaded parallel calculations according to the "last-in, first-out" principle to obtain the output result file; if the kernel simulation program input file does not exist in the calculation queue, proceed to Step 4.

[0177] Step 3: Based on the DET simulation object category, generate a restart file for the failed DET branch according to the restart file update method, name it *-1.input, and combine it with the output of the kernel simulation program to form a calculation case and put it into the calculation queue, and then execute Step 2;

[0178] Step 4: Once each DET branch reaches the user-specified simulation task time or simulation termination condition, the dynamic coupling between DET and the kernel simulation program ends.

[0179] In summary, after DET is dynamically coupled with the nuclear simulation program, the physical characteristics of nuclear power plants in different branch sequences can be extracted by parsing the input files of each branch node and the terminal node; and the safety characteristics of nuclear power plants can be obtained through statistical analysis, cluster analysis, etc.

[0180] The specific embodiments described in this invention are merely illustrative of the invention and are not intended to limit it. Those skilled in the art can make modifications to these embodiments without contributing any inventive step after reading this specification, but such modifications are protected by patent law as long as they fall within the scope of the claims of this invention.

Claims

1. A method for efficient and dynamic coupling analysis of discrete dynamic event trees with nuclear simulation programs, characterized in that, The method comprises the following steps: S1, a DET simulation model of a discrete dynamic event tree is constructed, and a TRIP card of an input file of a nuclear simulation program is modified by adding a general auxiliary TRIP variable according to a state transition type of a DET simulation object; the general auxiliary TRIP variable is a variable type or a logic type; the DET simulation object is a nuclear power plant system, equipment or personnel operation, and a state transition of the DET simulation object is controlled by a TRIP variable in the nuclear simulation program; a logic value of the TRIP variable is divided into true True and false False; a space vector of the TRIP variable of the DET simulation object is wherein n is a number of the DET simulation objects, s i represents a TRIP logic value corresponding to the ith DET simulation object; that is S2, determining the simulation time of the nuclear simulation program and running to the end of the simulation, and the simulation file calculated is taken as a parent sequence file; at this time, the DET simulation object is an analysis object of an initiating accident of a nuclear power plant, an initial nuclear simulation program input card file is programmed and simulated according to a deterministic analysis method, the input card file comprises an initial input file Root.input and an initial restart calculation file R0.input; wherein "Root" represents an arbitrary file name meeting the requirements of the nuclear simulation program, "R0" represents a file name, and ".i" represents a file type; S3, according to the simulation result file output by the current parent sequence of the nuclear simulation program, analyzing the result file to obtain time information of changes of a state transition control TRIP variable of all DET simulation objects; S4, identifying a DET branch time at which a state transition of the DET simulation object occurs; the specific method of identifying the DET branch time at which the state transition of the DET simulation object occurs is as follows: first, obtaining the time information of changes of the state transition control TRIP variable of the DET simulation object according to step S3; second, obtaining a state transition TRIP trigger time of all DET simulation objects in the current parent sequence accident by analyzing the simulation result file, and obtaining a nuclear simulation program restart time corresponding to a nuclear simulation program backtracking restart information block number according to a branch rule of the DET simulation model; S5, obtaining a restart time and a restart number of nuclear simulation program backtracking restart of all DET simulation objects of the current parent sequence accident sequence according to the branch rule of the DET simulation model; the method of the restart time and the restart number of the DET simulation object backtracking restart is as follows: Step (1): Based on the TRIP trigger time set {TRIPT1, TRIPT2, ..., TRIPTM} obtained from the DET branch time. i }, where M i To determine the number of TRIPs required for DET branches in the parent sequence, the branches are sorted by trigger time, and their trigger times (TRIPTime and corresponding TRIP numbers) are identified. Finally, all triggered TRIP numbers and their corresponding trigger times ({TRIPTime1, TRIPTime2, ..., TRIPTimeM) are retrieved from the simulation results. i }; Step (2), judging whether the DET simulation object corresponding to the TRIPTime is a single state transition type, if yes, executing step (4); otherwise, executing step (3); Step (3), the DET simulation object may have multiple state transitions, analyzing all restart information block information in the simulation result file to obtain a time at which the multiple transition DET branch simulation object has a state transition for the first time, and assigning the time to TRIPTime, and then executing step (4); Step (4): Replace the corresponding elements in {TRIPT1, TRIPT2,..., TRIPTM} with TRIPTime, and then perform Step (5); i} with TRIPTime, and then perform Step (5); Step (5), calculating a DET backtracking restart information block number BloNum; BloNum is calculated by using the following formula: Δt = CpuTime max x ResFre Wherein: BloNum: a nuclear simulation program backtracking restart information block number calculated according to the TRIP trigger time TRIPTime of the state transition of the DET simulation object; CpuTime max : CPU maximum emulation step time in the time control card in the core emulation program input card; INT[]: an integer function; ResFre: a restart frequency of a time control card in the nuclear simulation program input card; TRIPTime: a state transition TRIP trigger time of the DET simulation object in the simulation calculation result; △t: a time interval of two restart information blocks in the time control card in the nuclear simulation program input card; After the calculation, the re-start numbers corresponding to all TRIP trigger cards under the current sequence {BloNum1, BloNum2,...BloNumM} are obtained i}; Step (6): M i sub-cycles according to the TRIP trigger time sequence to generate the corresponding branches in turn; S6, judging whether the current sequence restart time is same as the parent sequence restart time, if not, generating the restart input file for the nuclear simulation program calculation of all failed branches in the current accident sequence based on an initial input file containing restart calculation of all demand information, determining the DET simulation object state transition type, updating the restart input file for the nuclear simulation program calculation, the update of the restart input file here needs to be aimed at the DET simulation object state transition of the existing DET branch, the restart file update method at this time is: step 1: updating the restart number in the current node nuclear simulation program restart input file to ResNum, ResNum is the restart number corresponding to the BloNum of the nuclear simulation program backtracking restart information block; step 2: the simulation time card information is unchanged; step 3: updating the DET simulation object state transition failure control TRIP information; if the current sequence restart time is same as the parent sequence restart time, copying the parent sequence restart input file, and determining the DET simulation object state transition type on this basis, updating the restart input file for the nuclear simulation program calculation; S7, taking the updated failed restart file as input, copying the necessary restart input file in the parent sequence to the current folder, executing multi-thread parallel simulation according to the branch number backtracking, and completing the simulation of all DET failed branches; S8, taking the failed branch as a new parent sequence, judging whether there is a new DET branch generated according to the simulation result of the failed branch, if yes, executing steps S5-S8 cyclically, if not, the simulation is ended; The failed branch is the branch of DET object state transition failure, the successful branch is the branch of DET object state transition success; the above initial parent sequence is all DET object state transition successful branches, and the subsequent failed branch, i.e. the child sequence, is simulated based on the parent sequence according to the obtained output information.

2. The method of claim 1, wherein the discrete dynamic event tree and core simulator efficient and dynamic coupled analysis method is characterized by, In step S2, the initial restart calculation file R0.input file includes ① program restart control card; ② program time step control card.

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