Nuclear power plant DNBR online protection accident analysis method, device, medium and equipment

Abstract

The invention provides a nuclear power plant DNBR online protection accident analysis method and device, a medium and equipment. The method comprises the following steps: determining a DNBR accident type according to an accident initial state and process; for a DNBR online protection accident, determining a setting value according to a preset method, determining a DNBR value through an accident analysis model, and comparing the setting value with the DNBR value to obtain an online protection accident analysis result; if the minimum DNBR value is lower than the design standard, adjusting the setting value and recalculating until the design standard is met; for DNBR on-line monitoring effective accidents, a monitoring setting value is determined, the accident state is adjusted to target power distribution, and transient calculation is performed based on the adjusted state to obtain an on-line monitoring effective accident analysis result; and if the minimum DNBR value is lower than the design standard, adjusting the setting value and adjusting the power distribution for analysis until the design standard is met. According to the invention, the operation flexibility of the online protection nuclear power plant reactor protection system is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of reactor safety analysis, and in particular to a method, device, medium and equipment for analyzing DNBR online protection accidents in a nuclear power plant. Background Art

[0002] In the design of the nuclear island of a pressurized water reactor nuclear power plant, ensuring the safe operation of the reactor is a crucial task. To this end, designers have adopted multiple safety measures to prevent the leakage of radioactive materials, including the setting of three physical safety barriers such as the fuel cladding, the primary circuit pressure boundary and the containment. The purpose of these barriers is to remain intact under most operating limit conditions to ensure the safety and stability of the reactor system.

[0003] The core function of the reactor protection system of a nuclear power plant is to automatically shut down the reactor under operating limit conditions to prevent the nuclear reaction from getting out of control and maintain the integrity of the three safety barriers. In order to achieve this goal, the design usually includes over-temperature and over-power ΔT protection channels. These channels reflect the departure from nucleate boiling ratio (DNBR) and linear power density in the core by monitoring the temperature difference between the inlet and outlet of the reactor.

[0004] However, the current design has some limitations. First, the monitoring method of the overtemperature and overpower ΔT protection channel is relatively indirect, mainly relying on temperature difference changes to estimate the core state, which may introduce certain uncertainties; second, in pursuit of safety, the relevant methods sacrifice reactor efficiency and operational flexibility. Summary of the invention

[0005] The disclosed embodiments at least provide a method, device, medium and equipment for analyzing DNBR online protection accidents in a nuclear power plant. By accurately identifying the accident type and setting DNBR setting values ​​for different accident types, combined with real-time DNBR values ​​and transient calculations, the operational flexibility of the online protection nuclear power plant reactor system is effectively ensured. At the same time, through a cyclic verification and adjustment mechanism, the online protection accident analysis results are ensured to meet the design benchmark requirements, thereby ensuring the safe operation capability and accident prevention capability of the nuclear power plant.

[0006] The present disclosure provides a method for analyzing a DNBR online protection accident in a nuclear power plant, including:

[0007] Determine the type of DNBR online protection accident based on the initial state and progress of the accident;

[0008] In the case where the DNBR online protection accident type is a DNBR online protection triggering accident, the DNBR online protection setting value is determined based on a preset method; and the DNBR value is determined based on an online protection triggering accident analysis model; an online protection accident analysis result is obtained according to the DNBR online protection setting value and the DNBR value; it is determined whether the minimum DNBR value corresponding to the online protection accident analysis result is greater than the DNBR design reference value; if not, the DNBR online protection setting value is adjusted, and the DNBR value is re-determined based on the adjusted DNBR online protection setting value and the online protection accident result is analyzed until the design standard is met, and a target online protection accident analysis result is obtained;

[0009] In the case where the DNBR online protection accident type is a DNBR online monitoring effective accident, the DNBR online monitoring setting value is determined based on a preset method; the power distribution of the initial state of the accident is adjusted to the target power distribution; and transient calculation is performed based on the adjusted initial state of the accident and the accident process to obtain an online monitoring accident analysis result; the target power distribution includes the power distribution corresponding to the case where the minimum DNBR value of the entire core is equal to the DNBR online monitoring setting value; it is determined whether the minimum DNBR value corresponding to the online monitoring accident analysis result is greater than the DNBR design reference value; if not, the DNBR online monitoring setting value is adjusted, and the power distribution of the initial state of the accident is readjusted based on the adjusted DNBR online monitoring setting value, and the online monitoring results are analyzed until the design standard is met to obtain the target online monitoring accident analysis result.

[0010] In some possible embodiments, the DNBR online protection accident type further includes a DNBR online monitoring invalid accident; and determining the DNBR online protection accident type based on the initial state of the accident and the accident process includes:

[0011] Determine whether the situation in which the value of DNBR is less than the preset protection setting value during the accident process is the first protection signal triggered during the accident analysis process; if so, the DNBR online protection accident type is a DNBR online protection triggered accident; if not, the DNBR online protection accident type is a DNBR online protection untriggered accident;

[0012] When the DNBR online protection accident type is a DNBR online protection untriggered accident, determine whether the online monitoring of the nuclear power plant operating conditions corresponding to the initial state of the accident is valid. If so, the DNBR online protection accident type is a DNBR online monitoring valid accident; if not, the DNBR online protection accident type is a DNBR online monitoring invalid accident.

[0013] In some possible embodiments, the DNBR online protection setting value includes a DNBR online protection accident analysis value and a DNBR online protection field setting value; and determining the DNBR online protection setting value based on a preset method includes:

[0014] Determining the DNBR online protection accident analysis value according to the DNBR design basis value and the preset safety margin;

[0015] The DNBR online protection field setting value is determined according to the DNBR online protection accident analysis value and uncertainties; the uncertainties include uncertainties of online measured physical parameters, core flow uncertainties, critical heat flux density relationship uncertainties, fuel rod bending uncertainties, online DNBR calculation model uncertainties, engineering enthalpy rise and hot spot factor uncertainties and calculation program uncertainties.

[0016] In some possible embodiments, the online protection triggering accident analysis model adopts the same online DNBR calculation model as the DNBR online protection software of the nuclear power plant; the DNBR value is determined based on the online protection triggering accident analysis model; and the online protection analysis result is obtained according to the DNBR online protection setting value and the DNBR value, including:

[0017] Calculating the DNBR value in the case of a DNBR online protection triggering accident type based on the online DNBR calculation model, and determining whether the calculated DNBR value is less than the DNBR online protection accident analysis value;

[0018] When the calculated DNBR value is less than the DNBR online protection accident analysis value, the reactor is shut down and shutdown reactivity is introduced;

[0019] The minimum DNBR value of the reactor after the shutdown reactivity is introduced is obtained, and the online protection accident analysis result is obtained based on the minimum DNBR value.

[0020] In some possible embodiments, adjusting the DNBR online protection setting value includes:

[0021] Adjusting the preset safety margin according to the online protection accident analysis result, and using the adjusted preset safety margin as a new preset safety margin;

[0022] According to the new preset safety margin, the DNBR online protection setting value is determined based on a preset method.

[0023] In some possible embodiments, the DNBR online monitoring setting value includes a DNBR online monitoring accident analysis value and a DNBR online monitoring field setting value; and determining the DNBR online monitoring setting value based on a preset method includes:

[0024] Determine the DNBR online monitoring accident analysis value according to the DNBR design benchmark value and the preset accident safety margin;

[0025] Determine the DNBR online monitoring field setting value according to the DNBR online monitoring accident analysis value and uncertain factors;

[0026] Accordingly, the target power distribution includes the power distribution corresponding to the case where the minimum DNBR value of the whole core is equal to the DNBR online monitoring accident analysis value. In some possible embodiments,

[0027] In some possible embodiments, adjusting the DNBR online monitoring set value includes:

[0028] Adjusting the preset accident safety margin according to the online monitoring and analysis results, and using the adjusted preset accident safety margin as a new preset accident safety margin;

[0029] According to the new preset accident safety margin, the DNBR online monitoring setting value is determined based on a preset method.

[0030] The embodiment of the present disclosure provides a DNBR online protection accident analysis device for a nuclear power plant, comprising:

[0031] The accident type judgment module is used to determine the DNBR online protection accident type based on the initial state of the accident and the accident process;

[0032] A protection result analysis module is used to determine the DNBR online protection setting value based on a preset method when the DNBR online protection accident type is a DNBR online protection triggering accident; and determine the DNBR value based on an online protection triggering accident analysis model; obtain an online protection accident analysis result according to the DNBR online protection setting value and the DNBR value; determine whether the minimum DNBR value corresponding to the online protection accident analysis result is greater than the DNBR design reference value; if not, adjust the DNBR online protection setting value, and re-determine the DNBR value based on the adjusted DNBR online protection setting value and analyze the online protection accident result until the design standard is met to obtain a target online protection accident analysis result;

[0033] A monitoring result analysis module is used to determine the DNBR online monitoring setting value based on a preset method when the DNBR online protection accident type is a DNBR online monitoring effective accident; adjust the power distribution of the initial state of the accident to the target power distribution; and perform transient calculation according to the adjusted initial state of the accident and the accident process to obtain an online monitoring accident analysis result; the target power distribution includes the power distribution corresponding to the case where the minimum DNBR value of the whole core is equal to the DNBR online monitoring setting value; determine whether the minimum DNBR value corresponding to the online monitoring analysis result is greater than the DNBR design reference value; if not, adjust the DNBR online monitoring setting value, and readjust the power distribution of the initial state of the accident based on the adjusted DNBR online monitoring setting value and analyze the online monitoring accident result until the design standard is met to obtain the target online monitoring accident analysis result.

[0034] In some possible embodiments, the DNBR online protection accident type also includes a DNBR online monitoring invalid accident; and the accident type judgment module is specifically used for:

[0035] Determine whether the situation in which the value of DNBR is less than the preset protection setting value during the accident process is the first protection signal triggered during the accident analysis process; if so, the DNBR online protection accident type is a DNBR online protection triggered accident; if not, the DNBR online protection accident type is a DNBR online protection untriggered accident;

[0036] When the DNBR online protection accident type is a DNBR online protection untriggered accident, it is determined whether the online monitoring of the nuclear power plant operating conditions in the initial state of the accident is valid. If so, the DNBR online protection accident type is a DNBR online monitoring valid accident; if not, the DNBR online protection accident type is a DNBR online monitoring invalid accident.

[0037] In some possible embodiments, the DNBR online protection setting value includes a DNBR online protection accident analysis value and a DNBR online protection field setting value; the protection result analysis module is specifically used for:

[0038] Determining the DNBR online protection accident analysis value according to the DNBR design basis value and the preset safety margin;

[0039] The DNBR online protection field setting value is determined according to the DNBR online protection accident analysis value and uncertainties; the uncertainties include uncertainties of online measured physical parameters, core flow uncertainties, critical heat flux density relationship uncertainties, fuel rod bending uncertainties, online DNBR calculation model uncertainties, engineering enthalpy rise and hot spot factor uncertainties and calculation program uncertainties.

[0040] In some possible embodiments, the online protection triggering accident analysis model adopts the same online DNBR calculation model as the DNBR online protection software of the nuclear power plant; the protection result analysis module is specifically used for:

[0041] Calculating the DNBR value in the case of a DNBR online protection triggering accident type based on the online DNBR calculation model, and determining whether the calculated DNBR value is less than the DNBR online protection accident analysis value;

[0042] When the calculated DNBR value is less than the DNBR online protection accident analysis value, the reactor is shut down and shutdown reactivity is introduced;

[0043] The minimum DNBR value of the reactor after the shutdown reactivity is introduced is obtained, and the online protection accident analysis result is obtained based on the minimum DNBR value.

[0044] In some possible embodiments, the protection result analysis module is specifically used to:

[0045] Adjusting the preset safety margin according to the online protection accident analysis result, and using the adjusted preset safety margin as a new preset safety margin;

[0046] According to the new preset safety margin, the DNBR online protection setting value is determined based on a preset method.

[0047] In some possible embodiments, the DNBR online monitoring setting value includes a DNBR online monitoring accident analysis value and a DNBR online monitoring field setting value; the monitoring result analysis model is specifically used for:

[0048] Determine the DNBR online monitoring accident analysis value according to the DNBR design benchmark value and the preset accident safety margin;

[0049] Determine the DNBR online monitoring field setting value according to the DNBR online monitoring accident analysis value and uncertain factors;

[0050] Accordingly, the target power distribution includes the power distribution corresponding to the case where the minimum DNBR value of the entire core is equal to the DNBR online monitoring accident analysis value.

[0051] In some possible embodiments, the monitoring result analysis model is specifically used for:

[0052] Adjusting the preset accident safety margin according to the online monitoring and analysis results, and using the adjusted preset accident safety margin as a new preset accident safety margin;

[0053] According to the new preset accident safety margin, the DNBR online monitoring setting value is determined based on a preset method.

[0054] An embodiment of the present disclosure provides a computer device, including: a processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the computer device is running, the processor communicates with the memory via the bus, and when the machine-readable instructions are executed by the processor, the nuclear power plant DNBR online protection accident analysis method as described in any possible implementation manner described above is performed.

[0055] An embodiment of the present disclosure provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for analyzing an online DNBR protection accident of a nuclear power plant as described in any of the above possible implementation modes is implemented.

[0056] The nuclear power plant DNBR online protection accident analysis method, device, medium and equipment provided in the embodiments of the present disclosure effectively ensure the operational flexibility of the online protection nuclear power plant reactor system by accurately identifying the accident type and setting the DNBR setting value for different accident types, combining the real-time DNBR value and transient calculation. At the same time, through the cyclic verification and adjustment mechanism, it is ensured that the online protection analysis results meet the design benchmark requirements, thereby ensuring the safe operation capability and accident prevention capability of the nuclear power plant.

[0057] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required to be cited in the embodiments. The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present disclosure and are used together with the specification to illustrate the technical solutions of the present disclosure. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0059] Figure 1 A flow chart of a method for analyzing a DNBR online protection accident in a nuclear power plant provided by an embodiment of the present disclosure is shown;

[0060] Figure 2 A flow chart showing a method for determining an online protection analysis result in a method for analyzing a DNBR online protection accident in a nuclear power plant provided by an embodiment of the present disclosure is shown;

[0061] Figure 3 A schematic structural diagram of a DNBR online protection accident analysis device for a nuclear power plant provided by an embodiment of the present disclosure is shown;

[0062] Figure 4 A schematic diagram of the structure of a computer device provided by an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical scheme and advantages of the embodiments of the present disclosure clearer, the technical scheme in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. The components of the embodiments of the present disclosure generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the present disclosure for protection, but merely represents the selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present disclosure.

[0064] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0065] The term "and / or" herein only describes an association relationship, indicating that three relationships may exist. For example, A and / or B may represent the following three situations: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" herein represents any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C may represent including any one or more elements selected from the set consisting of A, B, and C.

[0066] In the design of the nuclear island of a pressurized water reactor nuclear power plant, multiple safety measures have been considered to prevent the leakage of radioactive materials, namely the setting of three physical safety barriers: fuel cladding, primary circuit pressure boundary and containment. The main function of the nuclear power plant reactor protection system is to automatically shut down the reactor when the operating conditions of the nuclear power plant reach the operating limit, so as to protect the integrity of the three barriers and ensure the safety of the reactor.

[0067] According to research, in order to prevent the core from deviating from nucleate boiling and the melting of fuel elements, the relevant technology is generally achieved by setting up an over-temperature and over-power ΔT protection channel, which reflects the departure from nucleate boiling ratio (DNBR) and linear power density in the core by monitoring the temperature difference between the inlet and outlet of the reactor. However, this protection channel monitoring method is relatively indirect, mainly relying on the change in temperature difference to estimate the core state, which may introduce certain uncertainties; secondly, in order to pursue safety, the relevant method sacrifices a lot of reactor efficiency and operational flexibility.

[0068] Based on the above research, the disclosed embodiments provide a method, device, medium and equipment for analyzing DNBR online protection accidents in nuclear power plants. First, the type of DNBR protection accident is determined according to the initial state and process of the accident. If it is a DNBR online protection triggering accident, the protection setting value is determined by a preset method, and the DNBR value is calculated based on the online protection triggering accident analysis model, and the protection analysis result is obtained by comparing it with the setting value. If the minimum DNBR value corresponding to the result does not meet the design benchmark, the setting value is adjusted and re-analyzed until the standard is met to obtain the target online protection accident analysis result. If it is an effective accident for online monitoring, the monitoring setting value is determined, the power distribution of the initial state of the accident is adjusted to the target power distribution, and a transient calculation is performed to obtain the effective accident result for online monitoring; similarly, if the design benchmark is not met, the monitoring setting value is adjusted and re-analyzed until the standard is met to obtain the target monitoring accident analysis result.

[0069] In the disclosed embodiment, by accurately identifying the accident type and setting the DNBR setting value for different accident types, combined with the real-time analysis and transient calculation methods, the operational flexibility of the online protection nuclear power plant reactor system is effectively ensured. At the same time, through the cyclic verification and adjustment mechanism, it is ensured that the online protection accident analysis results meet the design benchmark requirements, thereby ensuring the safe operation capability and accident prevention capability of the nuclear power plant.

[0070] To facilitate understanding of this embodiment, firstly, the execution subject of the nuclear power plant DNBR online protection accident analysis method provided by the embodiment of the present disclosure is introduced in detail.

[0071] The execution subject of the nuclear power plant DNBR online protection accident analysis method provided by the embodiment of the present disclosure is a computer device. The computer device can be a server. The server can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud storage, big data and artificial intelligence platforms.

[0072] The following is a detailed description of the DNBR online protection accident analysis method for a nuclear power plant provided by the embodiment of the present application in conjunction with the accompanying drawings. Figure 1 As shown, it is a flow chart of a method for analyzing a DNBR online protection accident of a nuclear power plant provided by an embodiment of the present disclosure, and the method includes the following S101 to S103:

[0073] S101, determining the DNBR online protection accident type based on the accident initial state and accident process.

[0074] It is understandable that in the operation of nuclear power plants, DNBR is a crucial safety parameter used to evaluate the thermal-hydraulic state of the coolant in the core and ensure the safe operation of the reactor. The initial state of the accident refers to the state of the reactor before the accident, which can include key parameters such as reactor power, coolant flow, core temperature and pressure. Changes in these parameters will directly affect the value of DNBR. The accident process refers to the process of changes in the reactor state over time after the accident. In this change process, the change trend and amplitude of DNBR are used to determine the type of accident.

[0075] Here, the DNBR online protection accident type includes a DNBR online protection triggered accident and a DNBR online protection untriggered accident, wherein the DNBR online protection untriggered accident includes a DNBR online monitoring effective accident and a DNBR online monitoring invalid accident. Exemplarily, when determining the DNBR online protection accident type based on the accident initial state and the accident process, the following (1) to (2) may be included:

[0076] (1) determining whether the situation in which the value of DNBR is less than the preset protection setting value during the accident process is the first protection signal triggered during the accident analysis process; if so, the DNBR online protection accident type is a DNBR online protection triggered accident; if not, the DNBR online protection accident type is a DNBR online protection untriggered accident;

[0077] (2) When the DNBR online protection accident type is a DNBR online protection untriggered accident, determine whether the online monitoring of the nuclear power plant operating conditions corresponding to the initial state of the accident is valid. If so, the DNBR online protection accident type is a DNBR online monitoring valid accident; if not, the DNBR online protection accident type is a DNBR online monitoring invalid accident.

[0078] Specifically, the preset protection setting value is set by professionals based on reactor design, safety guidelines and historical operating experience. If the DNBR value is less than the preset protection setting value during the accident process, and the situation where it is less than the preset protection setting value is the first protection signal triggered during the accident analysis process, the accident type is classified as a "DNBR online protection triggering accident". In this case, the system may need to introduce a DNBR online protection mechanism (such as emergency shutdown, etc.) to restore the reactor to a safe state. In addition, since the triggering conditions for the DNBR online protection triggering accident (i.e., the DNBR preset protection setting value) are fixed, there are no special requirements for the initial power distribution when analyzing such accidents.

[0079] On the other hand, if the DNBR value is not less than the preset protection setting value during the accident process or the DNBR value is less than the preset protection setting value and is not the first protection signal triggered in the analyzed accident process, the accident type is classified as "DNBR online protection untriggered accident". At this time, after determining that the accident type belongs to the DNBR online protection untriggered accident, it is necessary to judge whether the online monitoring of the nuclear power plant operating conditions corresponding to the initial state of the accident is effective, that is, whether the system can accurately capture the changes in the DNBR value and feedback to the relevant operators. If the online monitoring of the DNBR value corresponding to the initial state of the accident is effective, the DNBR online protection accident type is a DNBR online monitoring effective accident, and the system can continue to operate according to the established monitoring and emergency procedures. However, if the DNBR online monitoring corresponding to the initial state of the accident is invalid due to reasons such as the low initial power level, the DNBR online protection accident type is a DNBR online monitoring invalid accident. Therefore, in this type of accident, other measures need to be taken to ensure the safety of the reactor.

[0080] S102, when the DNBR online protection accident type is a DNBR online protection triggering accident, determining the DNBR online protection setting value based on a preset method; and determining the DNBR numerical value based on an online protection triggering accident analysis model; obtaining an online protection accident analysis result according to the DNBR online protection setting value and the DNBR numerical value; judging whether the minimum DNBR numerical value corresponding to the online protection accident analysis result is greater than the DNBR design reference numerical value; if not, adjusting the DNBR online protection setting value, and re-determining the DNBR numerical value based on the adjusted DNBR online protection setting value and analyzing the online protection accident result, until the design standard is met, and obtaining the target online protection accident analysis result.

[0081] Here, the DNBR online protection setting value includes the DNBR online protection accident analysis value and the DNBR online protection field setting value. Among them, the DNBR online protection accident analysis value is the value obtained by the staff after considering the preset safety margin on the basis of the DNBR design benchmark value (theoretical value is 1.0). For example, if the design benchmark is 1.0, then the accident analysis value may be set to 1.1 or higher to ensure sufficient redundancy. Among them, the setting of the preset safety margin needs to ensure that after the DNBR online protection triggers an accident, the minimum value of the DNBR value drop will not be lower than the DNBR design benchmark. In the embodiment of the present disclosure, at the beginning of the accident analysis, the staff can temporarily set a preset safety margin (such as 0.2 or 0.5) based on historical experience. After conducting the accident analysis, the preset safety margin can be adjusted according to the analysis results. In some other embodiments, the setting of the DNBR online protection accident analysis value can also take into account other factors such as the performance of the fuel elements and the design characteristics of the reactor, which are not specifically limited here.

[0082] For example, there are various uncertainties in the actual operation of nuclear power plants, such as uncertainties of online measured physical parameters, core flow uncertainties, critical heat flux relationship uncertainties, fuel rod bending uncertainties, online DNBR calculation model uncertainties, engineering enthalpy rise and hot spot factor uncertainties, and calculation program uncertainties. Therefore, in the calculation process of the DNBR online protection field setting value, it is necessary to consider various uncertainties on the basis of the DNBR online protection accident analysis value. Here, when calculating the DNBR setting value, the uncertainties that have been considered when the nuclear power plant DNBR online protection software calculates the DNBR real-time data are no longer considered repeatedly.

[0083] It is understood that after determining the DNBR online protection accident analysis value and the DNBR online protection on-site setting value in the case of a DNBR online protection triggering accident, Figure 2 As shown, when the DNBR value is determined based on the online protection triggering accident analysis model, and the online protection analysis result is obtained according to the DNBR value and the DNBR online protection setting value, the following S1021 to S1023 may be included:

[0084] S1021, calculating the DNBR value in the case of a DNBR online protection triggering accident type based on the online DNBR calculation model, and determining whether the calculated DNBR value is less than the DNBR online protection accident analysis value.

[0085] Here, the online protection triggering accident analysis model is established based on the thermal hydraulic characteristics of the reactor, the parameter changes (coolant flow, core temperature, pressure, etc.) of various accident types (such as an accident in which a group of control rods are pulled out out of control during power operation, etc.), and the procedures used for various accident analyses; and the online protection triggering accident analysis model uses the same online DNBR calculation model as the DNBR online protection software of the nuclear power plant. For the DNBR online protection triggering accident type, the online DNBR calculation model in the online protection triggering accident analysis model is used for simulation to calculate the online DNBR value during the accident process, which may specifically involve a comprehensive evaluation of the thermal hydraulic parameters at the hot spots in the core, including coolant temperature, heat flux density, etc., to ensure the accuracy and reliability of the calculation results. Then, the calculated DNBR value is compared with the aforementioned DNBR online protection accident analysis value. To determine whether the reactor is in a safe operating state.

[0086] S1022: When the calculated DNBR value is less than the DNBR online protection accident analysis value, the reactor is shut down and shutdown reactivity is introduced.

[0087] It is understandable that when the calculated DNBR value is less than the DNBR online protection accident analysis value, it indicates that the cooling capacity of the reactor may be insufficient to maintain safe operation and protective measures need to be taken. The core goal of these protective measures is to quickly reduce the power level of the reactor and reduce heat generation to prevent overheating of the fuel elements.

[0088] Among them, the protection measure adopted by the present disclosure is to shut down the reactor. This is usually achieved by inserting control rods into the reactor core, which can absorb neutrons, thereby quickly reducing the speed of the chain reaction and causing the power level of the reactor to drop rapidly. This step is the key to preventing the reactor from further heating up. At the same time, in order to further illustrate the simulation of reactor shutdown, the present disclosure also proposes the introduction of simulated shutdown reactivity. Here, shutdown reactivity refers to the change in nuclear reactivity that can reduce the reactor power or shut down the reactor to further reduce the power level of the reactor and ensure that the fuel elements are fully cooled. In this way, it can be ensured that the system can respond quickly and accurately in an emergency to ensure the safe and stable operation of the reactor.

[0089] S1023, obtaining a minimum DNBR value of the reactor after the shutdown reactivity is introduced, and obtaining an online protection accident analysis result based on the minimum DNBR value.

[0090] Specifically, since the power level of the reactor will drop rapidly after the reactor is shut down and the shutdown reactivity is introduced, its DNBR value will also change accordingly, so the system needs to continue to monitor the cooling status and DNBR value of the reactor. At this time, it is necessary to record and obtain the minimum DNBR value of the reactor after the shutdown reactivity is introduced, and relevant technical personnel use professional nuclear reactor safety analysis software (such as RELAP5, TRANTH, etc.) to conduct more in-depth accident simulation and safety assessment based on the minimum DNBR value to obtain online protection analysis results.

[0091] Exemplarily, after obtaining the online protection accident analysis results, the minimum DNBR value corresponding to the online protection analysis results is compared with the DNBR design benchmark value of the reactor to evaluate whether the response of the online protection system is timely and effective. If the minimum DNBR value remains above the DNBR design benchmark value, it means that the online protection system has successfully prevented the occurrence of serious accidents and the system can operate stably; if it is lower than the DNBR design benchmark value, it is necessary to further adjust the DNBR online protection setting value to ensure that it is more in line with the actual operating conditions of the reactor. Here, the preset safety margin can be adjusted according to the online protection analysis results. For example, if the evaluation results show that the current minimum DNBR value is lower than the DNBR design benchmark value and there is a large safety risk, it is possible to consider increasing the preset safety margin. The adjusted preset safety margin is used as the new preset safety margin, and then the DNBR online protection setting value is re-determined based on the preset method according to the new preset safety margin. The DNBR value is re-simulated and determined according to the adjusted DNBR online protection setting value, and the online protection accident results are analyzed to ensure the safe operation of the reactor. This process may require multiple iterations until the design standard is met, that is, to ensure that the minimum DNBR value remains above the DNBR design benchmark value, and to determine the optimal DNBR online protection setting value, and then use the online protection accident analysis result corresponding to the optimal DNBR online protection setting value as the target online protection accident analysis result.

[0092] S103, when the DNBR online protection accident type is a DNBR online monitoring effective accident, determine the DNBR online monitoring setting value based on a preset method; adjust the power distribution of the initial state of the accident to the target power distribution; and perform transient calculation according to the adjusted initial state of the accident and the accident process to obtain an online monitoring accident analysis result; the target power distribution includes the power distribution corresponding to the case where the minimum DNBR value of the whole core is equal to the DNBR online monitoring setting value; determine whether the minimum DNBR value corresponding to the online monitoring accident analysis result is greater than the DNBR design reference value; if not, adjust the DNBR online monitoring setting value, and readjust the power distribution of the initial state of the accident based on the adjusted DNBR online monitoring setting value and analyze the online monitoring result until the design standard is met to obtain the target online monitoring accident analysis result.

[0093] It is understandable that the DNBR online monitoring setting value includes the DNBR online monitoring accident analysis value and the DNBR online monitoring field setting value. Among them, the DNBR online monitoring accident analysis value is the value obtained by the staff after considering the preset accident safety margin on the basis of the DNBR design benchmark value (theoretical value is 1.0). For example, if the design benchmark is 1.0, then the DNBR online monitoring accident analysis value may be set to 1.2 or higher to ensure sufficient redundancy. Among them, the setting of the preset accident safety margin needs to ensure that the minimum value of the transient DNBR value drop after the occurrence of an effective accident in the DNBR online monitoring will not be lower than the DNBR design benchmark. In the embodiment of the present disclosure, at the beginning of the accident analysis, the staff can temporarily set a preset accident safety margin (such as 0.2 or 0.5) based on historical experience. After conducting the accident analysis, the preset accident safety margin can be adjusted according to the analysis results.

[0094] For example, since there are various uncertain factors in the actual operation of a nuclear power plant (please refer to step S102 for details), in the calculation process of the DNBR online monitoring site setting value, it is also necessary to consider various uncertain factors on the basis of the DNBR online monitoring accident analysis value. Here, when calculating the DNBR online monitoring site setting value, the uncertain factors that have been considered when the DNBR online protection software of the nuclear power plant calculates the DNBR are no longer considered again.

[0095] It is understandable that, since it is necessary to consider the characteristics of various accidents and the operating conditions corresponding to the characteristics of various accidents (such as full power conditions, low power conditions, etc.) when analyzing accidents, after determining the DNBR online monitoring accident analysis value and the DNBR online monitoring field setting value, the present disclosure adjusts the power distribution of the initial state of the accident to the most unfavorable power distribution, that is, the power distribution of the initial state of the accident is adjusted to the power distribution corresponding to the case where the minimum DNBR value of the whole core is equal to the DNBR online monitoring accident analysis value, so as to ensure that the system can fully consider all potential risks and uncertainties in actual operation, thereby providing more reliable protection measures. In this way, it is ensured that the system can still operate safely even under the most severe working conditions. After adjusting the power distribution of the initial state of the accident, transient calculations are performed according to the adjusted initial state of the accident and the accident process, usually including the use of thermal hydraulic simulation software, such as RELAP5, TRANTH or other suitable tools. In the transient calculation process, various stages of the accident development will be simulated, including the accident start-up, development and stabilization stages. Then, the changes and values ​​of DNBR are extracted from the transient calculation results to evaluate whether the system can maintain safe operation under the adjusted power distribution and obtain the online monitoring accident analysis results.

[0096] Exemplarily, after obtaining the online monitoring accident analysis results, the minimum DNBR value corresponding to the online monitoring accident analysis results is compared with the DNBR design reference value to determine whether it meets the safety requirements. If it does not meet the requirements, that is, the minimum DNBR value is not greater than the DNBR design reference value, the DNBR online monitoring setting value is adjusted. Specifically, the preset accident safety margin can be adjusted according to the online monitoring accident analysis results, and the adjusted preset accident safety margin is used as the new preset accident safety margin; then, according to the new preset accident safety margin, the DBNR online monitoring setting value is determined based on the preset method. Then, according to the adjusted DNBR online monitoring setting value, the power distribution of the initial state of the accident is readjusted, and the online monitoring accident results are analyzed until the design standards are met, and the target online monitoring accident analysis results are obtained. In this way, by continuously adjusting the DNBR online monitoring setting value and analyzing the results, it is possible to ensure that the nuclear reactor is maintained in a suitable working state to ensure the safety and stability of the reactor system.

[0097] The nuclear power plant DNBR online protection accident analysis method, device, medium and equipment provided in the embodiments of the present disclosure effectively ensure the operational flexibility of the online protection nuclear power plant reactor system by accurately identifying the accident type and setting the DNBR setting value for different accident types, combining the real-time analysis and transient calculation methods. At the same time, through the cyclic verification and adjustment mechanism, it is ensured that the online protection analysis results meet the design benchmark requirements, thereby ensuring the safe operation capability and accident prevention capability of the nuclear power plant.

[0098] Those skilled in the art will appreciate that, in the above method of specific implementation, the order in which the steps are written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of the steps should be determined by their functions and possible internal logic.

[0099] Based on the same inventive concept, the embodiment of the present disclosure also provides a nuclear power plant DNBR online protection accident analysis device corresponding to the nuclear power plant DNBR online protection accident analysis method. Since the principle of solving the problem by the device in the embodiment of the present disclosure is similar to the above-mentioned nuclear power plant DNBR online protection accident analysis method in the embodiment of the present disclosure, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be repeated.

[0100] Reference Figure 3 FIG. 1 is a schematic diagram of a DNBR online protection accident analysis device 300 for a nuclear power plant provided by an embodiment of the present disclosure, wherein the device comprises:

[0101] The accident type determination module 301 is used to determine the DNBR online protection accident type based on the accident initial state and the accident process;

[0102] The protection result analysis module 302 is used to determine the DNBR online protection setting value based on a preset method when the DNBR online protection accident type is a DNBR online protection triggering accident; and determine the DNBR value based on the online protection triggering accident analysis model; obtain the online protection accident analysis result according to the DNBR online protection setting value and the DNBR value; determine whether the minimum DNBR value corresponding to the online protection analysis result is greater than the DNBR design reference value; if not, adjust the DNBR online protection setting value, and re-determine the DNBR value based on the adjusted DNBR online protection setting value and analyze the online protection accident result until the design standard is met to obtain the target online protection accident analysis result;

[0103] The monitoring result analysis module 303 is used to determine the DNBR online monitoring setting value based on a preset method when the DNBR online protection accident type is a DNBR online monitoring effective accident; adjust the power distribution of the initial state of the accident to the target power distribution; and perform transient calculations based on the adjusted initial state of the accident and the accident process to obtain online monitoring analysis results; the target power distribution includes the power distribution corresponding to the case where the minimum DNBR value of the entire core is equal to the DNBR online monitoring setting value; determine whether the minimum DNBR value corresponding to the online monitoring accident analysis result is greater than the DNBR design reference value; if not, adjust the DNBR online monitoring setting value, and readjust the power distribution of the initial state of the accident based on the adjusted DNBR online monitoring setting value and analyze the online monitoring accident results until the design standard is met to obtain the target online monitoring accident analysis results.

[0104] In some possible embodiments, the DNBR online protection accident type also includes a DNBR online monitoring invalid accident; the accident type judgment module 301 is specifically used for:

[0105] Determine whether the situation in which the value of DNBR is less than the preset protection setting value during the accident process is the first protection signal triggered during the accident analysis process; if so, the DNBR online protection accident type is a DNBR online protection triggered accident; if not, the DNBR online protection accident type is a DNBR online protection untriggered accident;

[0106] When the DNBR online protection accident type is a DNBR online protection untriggered accident, determine whether the online monitoring of the nuclear power plant operating conditions corresponding to the initial state of the accident is valid. If so, the DNBR online protection accident type is a DNBR online monitoring valid accident; if not, the DNBR online protection accident type is a DNBR online monitoring invalid accident.

[0107] In some possible embodiments, the DNBR online protection setting value includes a DNBR online protection accident analysis value and a DNBR online protection field setting value; the protection result analysis module 302 is specifically used for:

[0108] Determining the DNBR online protection accident analysis value according to the DNBR design basis value and the preset safety margin;

[0109] The DNBR online protection field setting value is determined according to the DNBR online protection accident analysis value and uncertainties; the uncertainties include uncertainties of online measured physical parameters, core flow uncertainties, critical heat flux density relationship uncertainties, fuel rod bending uncertainties, online DNBR calculation model uncertainties, engineering enthalpy rise and hot spot factor uncertainties and calculation program uncertainties.

[0110] In some possible embodiments, the online protection triggering accident analysis model adopts the same online DNBR calculation model as the DNBR online protection software of the nuclear power plant; the protection result analysis module 302 is specifically used for:

[0111] Calculating the DNBR value in the case of a DNBR online protection triggering accident type based on the online DNBR calculation model, and determining whether the calculated DNBR value is less than the DNBR online protection accident analysis value;

[0112] When the calculated DNBR value is less than the DNBR online protection accident analysis value, the reactor is shut down and shutdown reactivity is introduced;

[0113] The minimum DNBR value of the reactor after the shutdown reactivity is introduced is obtained, and the online protection accident analysis result is obtained based on the minimum DNBR value.

[0114] In some possible embodiments, the protection result analysis module 302 is specifically used to:

[0115] Adjusting the preset safety margin according to the online protection accident analysis result, and using the adjusted preset safety margin as a new preset safety margin;

[0116] According to the new preset safety margin, the DNBR online protection setting value is determined based on a preset method.

[0117] In some possible embodiments, the DNBR online monitoring setting value includes a DNBR online monitoring accident analysis value and a DNBR online monitoring field setting value; the monitoring result analysis model 303 is specifically used for:

[0118] Determine the DNBR online monitoring accident analysis value according to the DNBR design benchmark value and the preset accident safety margin;

[0119] Determine the DNBR online monitoring field setting value according to the DNBR online monitoring accident analysis value and uncertain factors;

[0120] Accordingly, the target power distribution includes the power distribution corresponding to the case where the minimum DNBR value of the entire core is equal to the DNBR online monitoring accident analysis value.

[0121] In some possible embodiments, the monitoring result analysis model 303 is specifically used for:

[0122] Adjusting the preset accident safety margin according to the online monitoring and analysis results, and using the adjusted preset accident safety margin as a new preset accident safety margin;

[0123] According to the new preset accident safety margin, the DNBR online monitoring setting value is determined based on a preset method.

[0124] Based on the same technical concept, the embodiment of the present disclosure also provides a computer device. Figure 4 4 is a schematic diagram of the structure of a computer device 400 provided in an embodiment of the present disclosure, including a processor 401, a memory 402, and a bus 403. The memory 402 is used to store execution instructions, including a memory 4021 and an external memory 4022; the memory 4021 is also called an internal memory, which is used to temporarily store the operation data in the processor 401 and the data exchanged with the external memory 4022 such as a hard disk. The processor 401 exchanges data with the external memory 4022 through the memory 4021.

[0125] In the embodiment of the present application, the memory 402 is specifically used to store the application code for executing the solution of the present application, and the execution is controlled by the processor 401. That is, when the computer device 400 is running, the processor 401 communicates with the memory 402 through the bus 403, so that the processor 401 executes the application code stored in the memory 402, and then executes the method described in any of the above embodiments.

[0126] Among them, the memory 402 can be, but is not limited to, random access memory (Random Access Memory, RAM), read only memory (Read Only Memory, ROM), programmable read-only memory (Programmable Read-Only Memory, PROM), erasable programmable read-only memory (Erasable Programmable Read-Only Memory, EPROM), electrically erasable read-only memory (Electric Erasable Programmable Read-Only Memory, EEPROM), etc.

[0127] Processor 401 may be an integrated circuit chip with signal processing capabilities. The above-mentioned processor may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The disclosed methods, steps and logic block diagrams in the embodiments of the present invention may be implemented or executed. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0128] It is to be understood that the structure illustrated in the embodiment of the present application does not constitute a specific limitation on the computer device 400. In other embodiments of the present application, the computer device 400 may include more or fewer components than shown in the figure, or combine some components, or split some components, or arrange the components differently. The components shown in the figure may be implemented in hardware, software, or a combination of software and hardware.

[0129] The present disclosure also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the nuclear power plant DNBR online protection accident analysis method described in the above method embodiment are executed. The storage medium can be a volatile or non-volatile computer-readable storage medium.

[0130] The embodiments of the present disclosure also provide a computer program product, which carries a program code. The instructions included in the program code can be used to execute the steps of the nuclear power plant DNBR online protection accident analysis method described in the above method embodiment. For details, please refer to the above method embodiment, which will not be repeated here.

[0131] The computer program product may be implemented in hardware, software or a combination thereof. In one optional embodiment, the computer program product is implemented as a computer storage medium. In another optional embodiment, the computer program product is implemented as a software product, such as a software development kit (SDK).

[0132] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. In the several embodiments provided in the present disclosure, it should be understood that the disclosed system and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0133] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0134] In addition, each functional unit in each embodiment of the present disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0135] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present disclosure, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present disclosure. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0136] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present disclosure, which are used to illustrate the technical solutions of the present disclosure, rather than to limit them. The protection scope of the present disclosure is not limited thereto. Although the present disclosure is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed in the present disclosure, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for analyzing DNBR online protection accidents in a nuclear power plant, characterized in that: include: Determine the type of DNBR online protection accident based on the initial state and progress of the accident; In the case where the DNBR online protection accident type is a DNBR online protection triggering accident, determining the DNBR online protection setting value based on a preset method; and determining the DNBR value based on an online protection triggering accident analysis model; and obtaining an online protection accident analysis result based on the DNBR online protection setting value and the DNBR value; Determine whether the minimum DNBR value corresponding to the online protection accident analysis result is greater than the DNBR design reference value; if not, adjust the DNBR online protection setting value, and re-determine the DNBR value based on the adjusted DNBR online protection setting value and analyze the online protection accident result until the design standard is met to obtain the target online protection analysis accident result; In the case where the DNBR online protection accident type is a DNBR online monitoring effective accident, the DNBR online monitoring setting value is determined based on a preset method; the power distribution of the initial state of the accident is adjusted to the target power distribution; and transient calculation is performed based on the adjusted initial state of the accident and the accident process to obtain an online monitoring accident analysis result; the target power distribution includes the power distribution corresponding to the case where the minimum DNBR value of the entire core is equal to the DNBR online monitoring setting value; it is determined whether the minimum DNBR value corresponding to the online monitoring accident analysis result is greater than the DNBR design reference value; if not, the DNBR online monitoring setting value is adjusted, and the power distribution of the initial state of the accident is readjusted based on the adjusted DNBR online monitoring setting value, and the online monitoring results are analyzed until the design standard is met to obtain the target online monitoring accident analysis result.

2. The method according to claim 1, characterized in that The DNBR online protection accident type also includes DNBR online monitoring invalid accident; the DNBR online protection accident type determined based on the initial state of the accident and the accident process includes: Determine whether the situation in which the value of DNBR is less than the preset protection setting value during the accident process is the first protection signal triggered during the accident analysis process; if so, the DNBR online protection accident type is a DNBR online protection triggered accident; if not, the DNBR online protection accident type is a DNBR online protection untriggered accident; When the DNBR online protection accident type is a DNBR online protection untriggered accident, determine whether the online monitoring of the nuclear power plant operating conditions corresponding to the initial state of the accident is valid. If so, the DNBR online protection accident type is a DNBR online monitoring valid accident; if not, the DNBR online protection accident type is a DNBR online monitoring invalid accident.

3. The method according to claim 1, characterized in that: The DNBR online protection setting value includes a DNBR online protection accident analysis value and a DNBR online protection field setting value; the DNBR online protection setting value is determined based on a preset method, including: Determining the DNBR online protection accident analysis value according to the DNBR design basis value and the preset safety margin; The DNBR online protection field setting value is determined according to the DNBR online protection accident analysis value and uncertainties; the uncertainties include uncertainties of online measured physical parameters, core flow uncertainties, critical heat flux density relationship uncertainties, fuel rod bending uncertainties, online DNBR calculation model uncertainties, engineering enthalpy rise and hot spot factor uncertainties and calculation program uncertainties.

4. The method according to claim 3, characterized in that The online protection triggering accident analysis model adopts the same online DNBR calculation model as the DNBR online protection software of the nuclear power plant; the DNBR value is determined based on the online protection triggering accident analysis model; The online protection analysis result is obtained according to the DNBR online protection setting value and the DNBR value, including: Calculating the DNBR value in the case of a DNBR online protection triggering accident type based on the online DNBR calculation model, and determining whether the calculated DNBR value is less than the DNBR online protection accident analysis value; When the calculated DNBR value is less than the DNBR online protection accident analysis value, the reactor is shut down and shutdown reactivity is introduced; The minimum DNBR value of the reactor after the shutdown reactivity is introduced is obtained, and an online protection accident analysis result is obtained based on the minimum DNBR value.

5. The method according to claim 3, characterized in that: The adjusting the DNBR online protection setting value comprises: Adjusting the preset safety margin according to the online protection accident analysis result, and using the adjusted preset safety margin as a new preset safety margin; According to the new preset safety margin, the DNBR online protection setting value is determined based on a preset method.

6. The method according to claim 1, characterized in that The DNBR online monitoring setting value includes a DNBR online monitoring accident analysis value and a DNBR online monitoring field setting value; the DNBR online monitoring setting value is determined based on a preset method, including: Determine the DNBR online monitoring accident analysis value according to the DNBR design benchmark value and the preset accident safety margin; Determine the DNBR online monitoring field setting value according to the DNBR online monitoring accident analysis value and uncertain factors; Accordingly, the target power distribution includes the power distribution corresponding to the case where the minimum DNBR value of the entire core is equal to the DNBR online monitoring accident analysis value.

7. The method according to claim 6, characterized in that The adjusting of the DNBR online monitoring setting value comprises: Adjusting the preset accident safety margin according to the online monitoring and analysis results, and using the adjusted preset accident safety margin as a new preset accident safety margin; According to the new preset accident safety margin, the DNBR online monitoring setting value is determined based on a preset method.

8. A DNBR online protection accident analysis device for a nuclear power plant, characterized in that: include: The accident type judgment module is used to determine the DNBR online protection accident type based on the initial state of the accident and the accident process; A protection result analysis module, used for determining the DNBR online protection setting value based on a preset method when the DNBR online protection accident type is a DNBR online protection triggering accident; and determining the DNBR value based on an online protection triggering accident analysis model; obtaining an online protection analysis accident result according to the DNBR online protection setting value and the DNBR value; judging whether the minimum DNBR value corresponding to the online protection accident analysis result is greater than the DNBR design reference value; if not, adjusting the DNBR online protection setting value, and re-determining the DNBR value based on the adjusted DNBR online protection setting value and analyzing the online protection accident result, until the design standard is met, and obtaining a target online protection accident analysis result; A monitoring result analysis module is used to determine the DNBR online monitoring setting value based on a preset method when the DNBR online protection accident type is a DNBR online monitoring effective accident; adjust the power distribution of the initial state of the accident to the target power distribution; and perform transient calculation according to the adjusted initial state of the accident and the accident process to obtain an online monitoring accident analysis result; the target power distribution includes the power distribution corresponding to the case where the minimum DNBR value of the whole core is equal to the DNBR online monitoring setting value; determine whether the minimum DNBR value corresponding to the online monitoring analysis result is greater than the DNBR design reference value; if not, adjust the DNBR online monitoring setting value, and readjust the power distribution of the initial state of the accident based on the adjusted DNBR online monitoring setting value and analyze the online monitoring accident result until the design standard is met to obtain the target online monitoring accident analysis result.

9. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

10. A computer device comprising a storage medium, a processor, and a computer program stored in the storage medium and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

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