阅读说明：本技术 一种大破口失水事故分析方法及系统 (Large-break water loss accident analysis method and system ) 是由 黄涛 邓坚 李仲春 丁书华 李庆 冷贵君 刘余 卢宗健 钱立波 吴丹 陈伟 申 于 2021-06-10 设计创作，主要内容包括：本发明涉及反应堆热工水力设计及安全分析技术领域,具体公开了一种大破口失水事故分析方法及系统。选取核电站大破口失水事故相关的指标参数；建立稳态计算模型,对大破口失水事故相关参数进行稳态计算,并进行稳态计算后的参数值校验；构建瞬态计算模型,并对大破口失水事故相关参数进行瞬态计算,并根据计算结果与实际的破口、核电厂外电情况进行对比,并在出现偏离时,重新构建瞬态计算模型并进行瞬态计算；进行安注水扣除,获得液位参数值,并对瞬态模型进行更新后,在稳态计算结果基础上进行再计算,并在完成计算后,进行参数显示及分析。该方法和系统解决了压水堆大破口失水事故分析的工况多、流程繁琐、人因失误率高的难题。(The invention relates to the technical field of reactor thermal hydraulic design and safety analysis, and particularly discloses a large-break water loss accident analysis method and system. Selecting index parameters related to the loss of coolant accident of the large break of the nuclear power station; establishing a steady-state calculation model, performing steady-state calculation on the relevant parameters of the large-break water loss accident, and verifying the parameter values after the steady-state calculation; constructing a transient calculation model, carrying out transient calculation on related parameters of the large-break water loss accident, comparing the calculation result with the actual break and the external electric condition of the nuclear power plant, and reconstructing the transient calculation model and carrying out transient calculation when deviation occurs; and (4) carrying out safety water injection deduction to obtain a liquid level parameter value, updating the transient model, recalculating on the basis of a steady-state calculation result, and carrying out parameter display and analysis after the calculation is finished. The method and the system solve the problems of multiple working conditions, complex flow and high human error rate of analysis of the large-break water loss accident of the pressurized water reactor.)

1. A large-break water loss accident analysis method is characterized by comprising the following steps:

selecting index parameters related to the loss of coolant accident of the large breach of the nuclear power station, sampling each parameter, and then performing parameter distribution inspection to verify the validity of a parameter sample value;

establishing a steady-state calculation model, performing steady-state calculation on the related parameters of the large-break water loss accident, and verifying the parameter values after the steady-state calculation according to whether the deviation value of the steady-state calculation value and the parameter sampling value exceeds a set threshold value;

constructing a transient calculation model, carrying out transient calculation on related parameters of the large-break water loss accident, comparing the calculation result with the actual break and the external electric condition of the nuclear power plant, and reconstructing the transient calculation model and carrying out transient calculation when deviation occurs;

and (4) deducting safety water injection to obtain a liquid level parameter value, updating the transient model, recalculating on the basis of a steady-state calculation result, extracting relevant parameters of the large-break water loss accident after the calculation is finished, and displaying and analyzing the parameters.

2. The analysis method for the large break loss of coolant accident according to claim 1, wherein the index parameters related to the large break loss of coolant accident in the nuclear power plant include index parameter sets consisting of conservative assumptions related to the large break loss of coolant accident in the nuclear power plant, parameters of initial conditions and boundary conditions, parameter ranges and distribution forms.

3. The analysis method for the loss of coolant accident with large breach as claimed in claim 1, wherein the validation of the sampled parameter sample value is performed by checking the parameter distribution after sampling to determine the validity of the sampled parameter sample, wherein the heat flow density heat channel factor FQ and the nuclear enthalpy heat channel factor F_ΔHTwo parameter sampling values need to satisfy normal distribution; the reactor power, the reactor average temperature, the system pressure, the safety injection tank water volume, the safety injection tank pressure, the safety injection tank water temperature, the safety injection water temperature, the reactor core upper part power distribution, the reactor core middle part power distribution, the breach area and whether the power outside the plant is lost or not, and the parameters need to meet the requirement of uniform distribution.

4. The large breach water loss accident analysis method according to claim 1, wherein the steady state calculation model is constructed by obtaining parameter sampling samples under various working conditions, positioning the keywords by using a python regular expression according to the physical meanings of the parameters, and writing the parameter values obtained under each sampling working condition into the corresponding positions of the input text card.

5. The analysis method for the loss of coolant accident with large breach according to claim 1, wherein the verification of the output file of the steady state calculation is performed by identifying the output file of the steady state calculation and determining whether the ending time of the steady state calculation is the same as the preset time, thereby determining whether the steady state calculation is completed or not for verification, and if the steady state calculation is not completed, returning to modify the information of the text card formed by sampling and performing the steady state calculation again.

6. The analysis method for loss of coolant accident with large breach according to claim 1, wherein the transient calculation model is formed by writing the two-loop steam flow parameter obtained by the steady state calculation, the breach area obtained by sampling and the loss of electricity information outside the plant into a transient card after the steady state calculation is completed.

7. The large breach water loss accident analysis method according to claim 1, wherein the liquid level parameter value is obtained by extracting a boron concentration value in a calculation result after transient calculation is completed, continuously detecting the boron concentration in a lower chamber in a nuclear power plant model, obtaining a water volume difference at the moment when the boron concentration exceeds a set threshold value, calculating the remaining water volume in the safety injection tank at the moment, and converting the water volume to obtain a liquid level value according to the relation between the volume of the spherical safety injection tank and the water level.

8. The method for analyzing the loss of coolant accident of large breach as claimed in claim 1, wherein the transient calculation or the steady state calculation is performed by calling a system program containing an annex K model by using an os module of python.

9. The large breach water loss accident analysis method according to claim 1, wherein after the transient model is updated, when recalculation is performed on the basis of the steady state calculation result, the level value of the safety injection tank is updated in the transient card information of the established model, and recalculation is performed on the basis of the steady state calculation result; the monitoring, displaying and analyzing of the parameters related to the loss of coolant accident of the large breach is realized by extracting the parameters related to the loss of coolant accident of the large breach, utilizing a matplotlib library to finish automatic drawing of a result graph, and automatically generating an analysis report based on a document template.

10. A large-break water loss accident analysis system is characterized by comprising a system parameter sampling module, a steady-state calculation module, a transient calculation module and a boron concentration monitoring module, wherein the parameter sampling module is connected with the steady-state calculation module, and can input acquired parameters related to a large-break water loss accident of a nuclear power station into a steady-state calculation module for steady-state calculation after forming input texts by the parameter sampling module; the steady-state calculation module transmits the steady-state calculation value to the transient calculation modules which are connected with each other for transient calculation; the boron concentration monitoring module is connected with the transient calculation module, and after the boron concentration monitoring module extracts and obtains a liquid level value of the safety injection tank from the transient calculation model, the transient calculation in the transient calculation model is updated and recalculated, and the data display module connected with the transient calculation module is used for displaying and analyzing related parameters.

11. The large breach loss of coolant accident analysis system of claim 10, wherein the parameter sampling module is capable of collecting parameters that have a greater impact on PCT during a loss of coolant accident, including but not limited to reactor power, reactor average temperature, system pressure, safety tank water volume, safety tank pressureWater temperature of safety injection tank, temperature of safety injection water, heat flux density heat channel factor FQ and nuclear enthalpy rise heat channel factor F_ΔHWhether power distribution at the upper part of the reactor core, power distribution at the middle part of the reactor core, the area of a break opening and power outside a plant are lost or not; the parameter sampling module can carry out data verification on the collected sampling parameters, wherein the collected parameters are divided into a heat flow density heat channel factor FQ and a nuclear enthalpy heat channel factor F_ΔHBesides the two parameters are normally distributed, other parameters need to be uniformly distributed, and if a certain parameter does not meet the distribution requirement of the parameter, resampling is needed.

12. The large break loss of coolant accident analysis system of claim 10, wherein the parameter sampling module is capable of collecting sample values of parameters under the operating conditions of the nuclear power plant and forming an input text card; the steady state calculation module writes the parameter values obtained by each sampling working condition into the corresponding positions of the text cards according to the input text cards to form a steady state calculation model; and performing steady-state calculation on the parameters in the text card, verifying the parameters after the steady-state calculation, and sending corresponding parameter resampling request signals to a parameter sampling module when the deviation between the obtained parameter steady-state calculation value and the sampled parameter value is greater than a set threshold value.

13. The large break loss of coolant accident analysis system of claim 12, wherein the steady state calculation module identifies a steady state calculation output file, determines whether steady state calculation is completed according to the consistency between the steady state calculation end time and the preset time, and when steady state calculation is not completed, requests for modifying input text card information are generated to the parameter sampling module, and the steady state calculation module is used for steady state calculation.

14. The large break loss of coolant accident analysis system of claim 10, wherein the transient calculation module inputs the two-loop steam flow parameter values after the steady state calculation by the steady state calculation module, the break area during the steady state calculation, and the off-site power loss information into the transient card, performs the transient calculation, verifies the break area and the off-site power loss information obtained by actual sampling according to the transient calculation result, and if the break area and the off-site power loss information deviate, the transient calculation module sends a request to the steady state calculation module, and continues the transient calculation after the parameters are modified.

15. The large break loss of coolant accident analysis system of claim 10, wherein the boron concentration monitoring module is capable of extracting the boron concentration value calculated by the transient calculation module, obtaining a water volume difference value at the moment when the boron concentration value exceeds a set threshold value, calculating a volume value of residual water in the safety injection tank at a corresponding moment, and obtaining a level value according to a relation between the volume of the spherical safety injection tank and the water level; and transmitting the liquid level value to a transient calculation module, updating transient information in the transient calculation module, and then calculating.

Technical Field

The invention belongs to the technical field of reactor thermal hydraulic design and safety analysis, and particularly relates to a large-break water loss accident analysis method and system.

Background

The large break accident determines one of the most design reference accidents of the nuclear power plant operation power, and the analysis evaluation model can be selected from a conservative evaluation model, a combined evaluation model, an optimal estimation model and a risk guidance evaluation model. These models mainly include four parts, computer program, system component availability assumption, initial conditions and boundary conditions. When a computer program adopts a system program of an annex K model meeting the requirements of regulations, the availability of system components adopts conservative assumptions, and initial conditions and boundary conditions adopt actual data + uncertainty, a combined evaluation model DMRM for the loss of coolant accident is formed, and has the following advantages: 1) the conservative computer program has low development cost, and the conservative property meets the requirements of the regulations; 2) the initial condition and the boundary condition of the actual data + uncertainty release excessive conservative margin, and the allowable upper power limit of the system can be improved under the same system design.

However, by adopting the DMRM combination evaluation model, multi-condition analysis needs to be carried out on uncertainty analysis, the calculation process of each condition comprises multiple processes of parameter sampling, steady-state input card generation, steady-state condition calculation, transient input card modification, transient calculation, safe water injection deduction, restarting calculation, result processing and the like, and the complete analysis of the water loss accident is carried out by a technician, so that the analysis time is consumed, the design progress is delayed, human errors are easily caused, and the technical quality cannot be ensured.

Disclosure of Invention

The invention aims to provide a large-break water loss accident analysis method and system, and solves the problems of low analysis efficiency and human errors in an analysis process of a large-break water loss accident.

The technical scheme of the invention is as follows: a large-break water loss accident analysis method comprises the following steps:

selecting index parameters related to the loss of coolant accident of the large breach of the nuclear power station, sampling each parameter, and then performing parameter distribution inspection to verify the validity of a parameter sample value;

establishing a steady-state calculation model, performing steady-state calculation on the related parameters of the large-break water loss accident, and verifying the parameter values after the steady-state calculation according to whether the deviation value of the steady-state calculation value and the parameter sampling value exceeds a set threshold value;

constructing a transient calculation model, carrying out transient calculation on related parameters of the large-break water loss accident, comparing the calculation result with the actual break and the external electric condition of the nuclear power plant, and reconstructing the transient calculation model and carrying out transient calculation when deviation occurs;

and (4) deducting safety water injection to obtain a liquid level parameter value, updating the transient model, recalculating on the basis of a steady-state calculation result, extracting relevant parameters of the large-break water loss accident after the calculation is finished, and displaying and analyzing the parameters.

The nuclear power station large break loss of coolant accident related index parameters comprise a nuclear power station large break loss of coolant accident related conservative assumption, initial condition and boundary condition parameters, and an index parameter set consisting of a parameter range and a distribution form;

the verification of the validity of the sampled parameter sample value is to check the parameter distribution after sampling so as to determine the validity of the sampled parameter sample, wherein the heat flow density heat channel factor FQ and the nuclear enthalpy heat channel factor F_ΔHTwo parameter sampling values need to satisfy normal distribution; the reactor power, the reactor average temperature, the system pressure, the safety injection tank water volume, the safety injection tank pressure, the safety injection tank water temperature, the safety injection water temperature, the reactor core upper part power distribution, the reactor core middle part power distribution, the breach area and whether the power outside the plant is lost or not, and the parameters need to meet the requirement of uniform distribution.

The steady-state calculation model is constructed by obtaining parameter sampling samples under various working conditions, positioning the keywords by using a python regular expression according to the physical meanings of the parameters, and writing the parameter values obtained under each sampling working condition into the corresponding positions of the input text card.

And the verification of the steady state calculation output file is realized by identifying the steady state calculation output file and judging whether the steady state calculation ending time is the same as the preset time so as to judge whether the steady state calculation is finished or not for verification, and if the steady state calculation is not finished, returning the text card information formed by modifying the samples and carrying out the steady state calculation again.

And after the steady-state calculation is completed, the transient calculation model is formed by writing the two-loop steam flow parameter values obtained by the steady-state calculation, the sampled breach area and the off-plant power loss condition information into a transient card.

The liquid level parameter value obtaining is that after transient calculation is completed, a boron concentration value in a calculation result is extracted, the boron concentration in a lower cavity in a nuclear power plant model is continuously detected, when the boron concentration exceeds a set threshold value, a water volume difference value at the moment is obtained, so that the residual water volume in the safety injection tank at the moment is calculated, and the water volume is converted to obtain a liquid level value according to the relation between the volume of the spherical safety injection tank and the water level.

And the transient calculation or the steady-state calculation is carried out by calling a system program containing an appendix K model by using an os module of python.

After the transient model is updated, when recalculation is carried out on the basis of a steady-state calculation result, the liquid level value of the safety injection tank is updated in the transient card information of the established model, and recalculation is carried out on the basis of the steady-state calculation result; the monitoring, displaying and analyzing of the parameters related to the loss of coolant accident of the large breach is realized by extracting the parameters related to the loss of coolant accident of the large breach, utilizing a matplotlib library to finish automatic drawing of a result graph, and automatically generating an analysis report based on a document template.

A large break loss of coolant accident analysis system comprises a parameter sampling module, a steady-state calculation module, a transient calculation module and a boron concentration monitoring module, wherein the parameter sampling module is connected with the steady-state calculation module, and can input collected parameters related to the large break loss of coolant accident of a nuclear power station into an input text and then input the input text into the steady-state calculation module for steady-state calculation; the steady-state calculation module transmits the steady-state calculation value to the transient calculation modules which are connected with each other for transient calculation; the boron concentration monitoring module is connected with the transient calculation module, and after the boron concentration monitoring module extracts and obtains a liquid level value of the safety injection tank from the transient calculation model, the transient calculation in the transient calculation model is updated and recalculated, and the data display module connected with the transient calculation module is used for displaying and analyzing related parameters.

The parameter sampling module can acquire parameters which have great influence on the PCT under the water loss accident, and the parameters include but are not limited to reactor power, reactor average temperature, system pressure, safety injection tank water volume, safety injection tank pressure, safety injection tank water temperature, safety injection water temperature, heat flux density heat channel factor FQ and nuclear enthalpy heat rising channel factor F_ΔHWhether power distribution at the upper part of the reactor core, power distribution at the middle part of the reactor core, the area of a break opening and power outside a plant are lost or not; said parameterThe sampling module can carry out data verification on the collected sampling parameters, wherein the collected parameters are divided into a heat flow density heat channel factor FQ and a nuclear enthalpy heat rising channel factor F_ΔHBesides the two parameters are normally distributed, other parameters need to be uniformly distributed, and if a certain parameter does not meet the distribution requirement of the parameter, resampling is needed.

The parameter sampling module can collect various parameter sample values under the working condition of the nuclear power plant and form an input text card; the steady state calculation module writes the parameter values obtained by each sampling working condition into the corresponding positions of the text cards according to the input text cards to form a steady state calculation model; and performing steady-state calculation on the parameters in the text card, verifying the parameters after the steady-state calculation, and sending corresponding parameter resampling request signals to a parameter sampling module when the deviation between the obtained parameter steady-state calculation value and the sampled parameter value is greater than a set threshold value.

The steady state calculation module identifies the output file of the steady state calculation, judges whether the steady state calculation is finished according to the consistency of the end time of the steady state calculation and the preset time, and generates request information for modifying the input text card information to the parameter sampling module when the steady state calculation is not finished, and utilizes the steady state calculation module to carry out the steady state calculation.

And the transient calculation module inputs the two-loop steam flow parameter values after the steady state calculation by the steady state calculation module, the breach area during the steady state calculation and the off-site electricity loss condition information into a transient card, performs transient calculation, verifies the transient calculation result and the breach and off-site electricity loss condition information obtained by actual sampling, sends a request to the steady state calculation module if the deviation occurs, and continues the transient calculation after parameter modification.

The boron concentration monitoring module can extract the boron concentration value calculated by the transient calculation module, obtain the water volume difference value when the boron concentration value exceeds a set threshold value, calculate the volume value of the residual water in the safety injection tank at the corresponding moment, and obtain a liquid level value according to the relation between the volume of the spherical safety injection tank and the water level; and transmitting the liquid level value to a transient calculation module, updating transient information in the transient calculation module, and then calculating.

The invention has the following remarkable effects: the large-break water loss accident analysis method and system provided by the invention solve the problems of multiple working conditions, complicated flow and high human error rate of the large-break water loss accident analysis of the pressurized water reactor. By utilizing the method, the analysis efficiency of the large-break water loss accident of the pressurized water reactor nuclear power plant can be remarkably improved, the evaluation period of the large-break water loss accident is shortened, the human error rate is reduced, and the rationality of the evaluation result is ensured. The method can be used for analyzing the large-break water loss accidents of Hualong I nuclear power plants and subsequent power plants in the third generation of autonomy in China, can also be used for analyzing small-break water loss accidents and analyzing certain accidents requiring a large amount of sensitivity researches, is beneficial to improving the efficiency of safety analysis, and ensures the correctness of parameter processing transmission in the analysis process.

Drawings

Fig. 1 is a schematic structural diagram of a large-break water loss accident analysis system according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

A large-break water loss accident analysis method specifically comprises the following steps:

s1, selecting index parameters related to the large-break water loss accident of the nuclear power station, sampling each parameter, and then performing parameter distribution inspection to verify the validity of a parameter sample value;

analyzing parameters, parameter ranges and distribution forms of conservative assumptions, initial conditions and boundary conditions related to the nuclear power station large-break-opening loss of coolant accident, and inputting the information into a formulated input text in a JSON format, wherein the formulated sampling parameters in the input text comprise parameters which have large influence on PCT under the loss of coolant accident, and the parameters include but are not limited to reactor power, reactor average temperature, system pressure, safety injection tank water volume, safety injection tank pressure, safety injection tank water temperature, safety injection water temperature, heat flux density heat channel factor FQ and nuclear enthalpy heat channel factor F_ΔHUpper core power distribution, in corePartial power distribution, break area, loss of power, heat flow density, heat channel factor FQ, and heat channel factor F_ΔHTwo parameters are normally distributed, and other parameters need to be uniformly distributed;

sampling the parameters to obtain sample values of the parameters, and outputting the sample values according to working conditions; checking the parameter distribution under each working condition, and if any parameter does not meet the distribution requirement, resampling is needed;

s2, establishing a steady-state calculation model, performing steady-state calculation on the parameters related to the large-break-opening water loss accident, and verifying the parameter values after the steady-state calculation according to whether the deviation value of the steady-state calculation value and the parameter sampling value exceeds a set threshold value;

s2.1, constructing a steady-state calculation model;

aiming at the obtained parameter sampling samples under various working conditions, positioning the keywords by using a python regular expression according to the physical meaning of each parameter, and writing the parameter values obtained under each sampling working condition into the corresponding positions of the input text card to complete the construction of a steady-state calculation model;

s2.2, performing steady-state calculation under each working condition, and switching to the step S1 for resampling after the deviation between the calculated steady-state calculation value of a certain parameter and the parameter value obtained by sampling is larger than a set threshold value;

calling a system program containing an annex K model by using an os module of python, performing steady-state calculation on parameters in the input text card, mainly verifying the parameters after the steady-state calculation is completed, and returning to the step S1 if the deviation between the calculated steady-state calculation value of the parameters and the sampled parameter values is greater than a set threshold value;

s2.3, verifying the steady-state calculation output file, and judging whether the steady-state calculation is finished in real time;

identifying the output file of the steady state calculation, judging whether the end time of the steady state calculation is equal to the preset time or not, thereby judging whether the steady state calculation is successful or completed, if the steady state calculation is not completed, returning to modify the information of the input text card, and carrying out the steady state calculation again;

s3, constructing a transient calculation model, carrying out transient calculation on the relevant parameters of the large-break water loss accident, comparing the calculation result with the actual break and the external power condition of the nuclear power plant, and reconstructing the transient calculation model and carrying out transient calculation when deviation occurs;

s3.1, after the steady-state calculation is completed, writing parameters obtained by the steady-state calculation into a transient card, and establishing a transient calculation model;

after the steady-state calculation is judged to be completed, writing the two-loop steam flow parameter values obtained by the steady-state calculation into a transient model, and writing the sampled breach area and the external power loss condition of the nuclear power plant into a transient card to form a transient calculation model;

s3.2, performing transient calculation, and verifying a transient calculation result;

calling a system program containing an annex K model by using an os module of python, performing transient calculation, verifying a transient calculation result with a real sampled breach and an external power condition of the nuclear power plant, and continuing to perform transient model construction and transient calculation if deviation occurs;

s4, carrying out safety water injection deduction to obtain a liquid level parameter value, updating the transient model, recalculating on the basis of a steady-state calculation result, extracting relevant parameters of the large-break water loss accident after calculation, and carrying out parameter display and analysis;

s4.1, after the transient calculation is completed, obtaining a liquid level value of the safety injection box by using the obtained boron concentration value;

after transient calculation is finished, extracting a boron concentration value in a calculation result, continuously detecting the boron concentration in a lower cavity in a nuclear power plant model, and obtaining a water volume difference value at the moment when the boron concentration exceeds a set threshold value so as to calculate the volume of residual water in the safety injection tank at the moment, and converting the water volume to obtain a liquid level value according to the relation between the volume of the spherical safety injection tank and the water level;

s4.2, updating the transient model, recalculating on the basis of the steady-state calculation result, monitoring relevant parameters of the large-break water loss accident, and displaying and analyzing;

updating the existing transient model in the transient card information of the established model according to the obtained safety injection tank level value, and recalculating on the basis of a steady-state calculation result;

monitoring the calculated value of the relevant parameters of the large-break loss-of-coolant accident in real time, extracting result parameters such as reactor power, pressure of a voltage stabilizer, reactor core water level, safety injection flow, break flow, cladding peak temperature and the like, completing automatic drawing of a result graph by using a matplotlib library, and automatically generating an analysis report based on a document template.

As shown in fig. 1, a large-break water loss accident analysis system includes a parameter sampling module, a steady-state calculation module, a transient calculation module, and a boron concentration monitoring module, wherein the parameter sampling module is connected to the steady-state calculation module, and can input collected parameters related to a large-break water loss accident of a nuclear power station into the steady-state calculation module to perform steady-state calculation after forming input texts on the collected parameters related to the large-break water loss accident by the parameter sampling module, wherein the parameter sampling module can collect parameters that have a large influence on PCT under the water loss accident, including but not limited to reactor power, reactor average temperature, system pressure, safety injection tank water volume, safety injection tank pressure, safety injection tank water temperature, safety injection water temperature, heat flux density heat channel factor FQ, and nuclear enthalpy heat rising channel factor F_ΔHRelevant parameters such as power distribution of the upper part of the reactor core, power distribution of the middle part of the reactor core, the area of a break, whether the power outside the plant is lost and the like; meanwhile, the parameter sampling module can carry out data verification on the acquired parameters, wherein the acquired parameters are divided into a heat flow density heat channel factor FQ and a nuclear enthalpy heat channel factor F_ΔHIf a certain parameter does not meet the distribution requirement of the parameter, resampling is needed; sampling the parameters, obtaining sample values of the parameters, and outputting the sample values according to working conditions to form an input text;

the steady state calculation module writes the parameter values obtained by each sampling working condition into the corresponding positions of the text cards according to the input texts containing the parameter values transmitted by the parameter sampling module and the physical meanings of each parameter to form a steady state calculation model; performing steady-state calculation on parameters in the text card, verifying the parameters after the steady-state calculation, and sending corresponding parameter resampling request signals to a parameter sampling module when the deviation between the obtained parameter steady-state calculation value and the sampled parameter value is larger than a set threshold value; the steady state calculation module identifies the output file of the steady state calculation, judges whether the steady state calculation is finished according to the consistency of the end time of the steady state calculation and the preset time, and when the steady state calculation is not finished, requests for modifying the input text card information are sent to the parameter sampling module, and the steady state calculation module is used for carrying out the steady state calculation;

the steady-state calculation module is also connected with the transient calculation module, after the steady-state calculation module completes the steady calculation, the two-loop steam flow parameter values obtained by the steady calculation, the breach area during the steady calculation and the off-plant electricity loss condition information are transmitted to the transient calculation module, the transient calculation is carried out, the verification is carried out according to the transient calculation result and the breach and off-plant point condition information obtained by actual sampling, if deviation occurs, the transient calculation module sends a request to the steady-state calculation module, and after parameter modification, the transient calculation is continued;

the boron concentration monitoring module is connected with the transient calculation module, the boron concentration value calculated by the transient calculation module is extracted by the boron concentration monitoring module, when the boron concentration value exceeds a set threshold value, the water volume difference value at the moment is obtained, the volume value of the residual water in the safety injection tank at the corresponding moment is calculated, and the liquid level value is obtained according to the relation between the volume of the spherical safety injection tank and the water level; transmitting the level value to a transient calculation module, updating transient information in the transient calculation module, and then calculating; the data display module is connected with the transient calculation module, and can display the parameter values related to the large-break water loss accident of the nuclear power plant transmitted to the data display module through the data display module, and directly introduce the obtained parameters into a generated analysis report by utilizing a document template library.