Domestic autonomous novel fuel assembly water loss accident analysis method, system and medium

Abstract

The invention discloses a domestic autonomous novel fuel assembly water loss accident analysis method and system and a medium, and the method comprises the steps: calculating the maximum cladding peak temperature for different life periods, obtaining the life period A corresponding to the maximum cladding peak temperature, calculating the maximum oxidation film thickness for different life periods, and obtaining the life period B corresponding to the maximum oxidation film thickness; taking the life period A as a target life period, and carrying out water loss accident analysis by changing the axial power distribution of the domestic novel fuel assembly to obtain the final maximum cladding peak temperature and the maximum oxidation film thickness; taking the life period B as a target life period, and carrying out water loss accident analysis by changing the axial power distribution of the domestic novel fuel assembly to obtain the maximum oxidation film thickness; and comparing the maximum oxide film thickness with the maximum oxide film thickness, and taking the larger value as the final maximum oxide film thickness. The method is suitable for domestic novel fuel assemblies, and the accuracy and efficiency of fuel assembly water loss accident analysis are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear fuel design, thermal hydraulic and loss of coolant accident analysis, and particularly relates to a loss of coolant accident analysis method, system and medium for a domestic self-innovated new fuel assembly. BACKGROUND

[0002] Under the trend of the state vigorously promoting the research and development of self-controllable key technologies, the research and development of self-innovated fuel assemblies is a core research work in the field of nuclear energy. The research and development of new fuel assemblies involves the breakthrough of multiple technologies, and the behavior characteristics of the fuel assemblies in accident conditions are key indicators related to the safety performance thereof.

[0003] The domestic self-innovated CF series assemblies and foreign fuel assemblies have many differences at present, including material characteristics, mechanical properties, etc. Taking the CF3 assembly as an example, the CF3 assembly adopts an N36 cladding material, so that the CF3 assembly has better mechanical properties. However, under the condition of a severe loss of coolant accident, especially under the condition of a severe loss of coolant accident with a serious loss of liquid in the core and insufficient heat removal, whether the fuel assembly can still maintain integrity, and whether the peak cladding temperature and the maximum oxidation rate in the accident process do not exceed the limit value are matters of concern.

[0004] Therefore, the existing loss of coolant accident analysis method for fuel assemblies is not suitable for the domestic self-innovated new fuel assemblies, and there is a problem of inaccurate and low-efficiency loss of coolant accident analysis.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The technical problem to be solved by the present application is that the existing loss of coolant accident analysis method for fuel assemblies is not suitable for the domestic self-innovated new fuel assemblies, and there is a problem of inaccurate and low-efficiency loss of coolant accident analysis. The present application aims to provide a loss of coolant accident analysis method, system and medium for a domestic self-innovated new fuel assembly, which is suitable for the domestic self-innovated new fuel assembly and improves the accuracy and efficiency of the loss of coolant accident analysis for the fuel assembly, thereby providing technical support for evaluating the safety performance of the fuel assembly under the condition of a loss of coolant accident.

[0007] The present application is realized by the following technical scheme:

[0008] In a first aspect, the present application provides a loss of coolant accident analysis method for a domestic self-innovated new fuel assembly, which comprises the following steps:

[0009] Selecting system parameters and break size of a reactor, calculating the maximum cladding peak temperature for different service lives and obtaining a service life A corresponding to the maximum cladding peak temperature according to the influence of different initial oxidation film thicknesses, initial internal pressures and gap widths and other parameters, and calculating the maximum oxidation film thickness for different service lives and obtaining a service life B corresponding to the maximum oxidation film thickness;

[0010] Take service life A as the target service life, change the axial power distribution of the new domestic fuel assembly to perform the loss of coolant accident analysis, obtain the final maximum cladding peak temperature, and obtain the increased oxide film thickness during the loss of coolant accident process; add the increased oxide film thickness to the initial oxide film thickness of service life A to obtain the maximum oxide film thickness ;

[0011] Take service life B as the target service life, change the axial power distribution of the new domestic fuel assembly to perform the loss of coolant accident analysis, obtain multiple oxide film thicknesses increased during the loss of coolant accident process under different power conditions, and select the maximum one and add the initial oxide film thickness of service life B to obtain the maximum oxide film thickness ;

[0012] Compare the maximum oxide film thickness and the second maximum oxide film thickness , and take the larger one as the final maximum oxide film thickness.

[0013] Further, the method further comprises:

[0014] Compare the final maximum cladding peak temperature and the final maximum oxide film thickness with corresponding preset thresholds, respectively, to analyze whether there is a safety hazard under the loss of coolant accident.

[0015] Further, the new domestic fuel assembly refers to a fuel assembly with a cladding material of N36.

[0016] Further, the maximum cladding peak temperature is calculated for different service lives, and service life A corresponding to the maximum cladding peak temperature is obtained, including:

[0017] The cladding peak temperatures PCT BLX , PCT EOC1 , PCT EOC2 and PCT EOC3 corresponding to the beginning of the service life, the end of the first cycle, the end of the second cycle and the end of the third cycle are calculated in sequence;

[0018] The maximum cladding peak temperature is selected from the cladding peak temperatures PCT BLX , PCT EOC1 , PCT EOC2 and PCT EOC3 as the maximum cladding peak temperature; and

[0019] The service life corresponding to the maximum cladding peak temperature is obtained and taken as service life A.

[0020] Further, the maximum oxide film thickness is calculated for different service lives, and service life B corresponding to the maximum oxide film thickness is obtained, including:

[0021] obtaining the hot rod wall temperature at the beginning of the life, the end of the first cycle, the end of the second cycle and the end of the third cycle in sequence;

[0022] taking the hot rod wall temperature as the input of the BAKER-JUST model, and calculating the thickness increase of the oxide film in the process of the loss of coolant accident at the beginning of the life, the end of the first cycle, the end of the second cycle and the end of the third cycle based on the BAKER-JUST model;

[0023] adding the thickness increase of the oxide film of each life to the initial maximum thickness of the oxide film to obtain the thickness of the oxide film of each life;

[0024] selecting the maximum thickness of the oxide film from the thicknesses of the oxide films of the lives as the maximum thickness of the oxide film, obtaining the life corresponding to the maximum thickness of the oxide film and taking the life as the life B.

[0025] Further, taking the life A as the target life, the loss of coolant accident analysis is performed by changing the axial power distribution of the localized new fuel assembly, the final maximum cladding peak temperature is obtained, and the increased thickness of the oxide film in the process of the loss of coolant accident is obtained; the increased thickness of the oxide film is added to the initial thickness of the oxide film of the life A to obtain the maximum thickness of the oxide film , comprising:

[0026] Taking the life A as the target life, the loss of coolant accident analysis is performed by changing the axial power distribution of the localized new fuel assembly; the axial power distribution includes the distribution of different power peak positions and different axial segment power shares;

[0027] obtaining the cladding peak temperature of the life A under different power distribution conditions after the loss of coolant accident analysis, and selecting the maximum cladding peak temperature therefrom as the final maximum cladding peak temperature;

[0028] calculating and obtaining the increased thickness of the oxide film in the process of the loss based on the BAKER-JUST model for the working condition in which the final maximum cladding peak temperature appears;

[0029] adding the increased thickness of the oxide film to the initial thickness of the oxide film of the life A to obtain the maximum thickness of the oxide film .

[0030] Further, taking the life B as the target life, the loss of coolant accident analysis is performed by changing the axial power distribution of the localized new fuel assembly, a plurality of oxide film thicknesses increased in the process of the loss of coolant accident under different power conditions are obtained, and the maximum one is selected and added to the initial thickness of the oxide film of the life B to obtain the maximum thickness of the oxide film , comprising:

[0031] Take the lifetime B as the target lifetime, through changing the axial power distribution of the new type fuel assembly of the domesticization to carry out the loss of coolant accident analysis; the axial power distribution includes different power peak positions, different axial segment power share distributions;

[0032] Based on the calculation of the BAKER-JUST model, the maximum thickness of the increased oxide film in the loss of coolant process under different power conditions is obtained, and the maximum oxide film thickness increase is selected from the maximum oxide film thickness increase and the initial oxide film thickness of the second lifetime to obtain the maximum oxide film thickness .

[0033] Further, the method is based on the existing loss of coolant accident analysis program (for example, ARSAC), based on the cladding design characteristics of the new type fuel assembly of the domesticization and the related experimental results, the newly added expanded cladding material physical property module is established, the solidified fuel assembly inter-radiation heat transfer module is established, the swelling and rupture module suitable for the cladding of the new type fuel assembly of the domesticization is implanted, and the analysis program ARSAC-CF suitable for the loss of coolant accident of the new type fuel assembly of the domesticization is formed.

[0034] In the second aspect, the application further provides a loss of coolant accident analysis system for the new type fuel assembly of the domesticization, and the system comprises:

[0035] The burnup sensitive analysis unit is used for selecting the system parameters of the reactor and the break size, calculating the maximum cladding peak temperature of different lifetimes and obtaining the lifetime A corresponding to the maximum cladding peak temperature according to the influence of different lifetime initial oxide film thicknesses, initial internal pressures and gap widths and other parameters, and calculating the maximum oxide film thickness of different lifetimes and obtaining the lifetime B corresponding to the maximum oxide film thickness.

[0036] The first power distribution sensitive analysis unit is used for taking the lifetime A as the target lifetime, changing the axial power distribution of the new type fuel assembly of the domesticization to carry out the loss of coolant accident analysis, obtaining the final maximum cladding peak temperature, and obtaining the increased oxide film thickness in the loss of coolant accident process; the maximum oxide film thickness is obtained by adding the initial oxide film thickness of the lifetime A to the increased oxide film thickness .

[0037] The second power distribution sensitive analysis unit takes the lifetime B as the target lifetime, changes the axial power distribution of the new type fuel assembly of the domesticization to carry out the loss of coolant accident analysis, obtains multiple oxide film thicknesses increased in the loss of coolant accident process under different power conditions, and obtains the maximum oxide film thickness by adding the initial oxide film thickness of the lifetime B to the maximum oxide film thickness .

[0038] The comparative analysis unit is used for comparing the maximum oxide film thickness and the maximum oxide film thickness , and taking the larger value as the final maximum oxide film thickness.

[0039] Further, the execution process of the first power distribution sensitivity analysis unit is as follows:

[0040] Take the service life A as the target service life, and perform the loss of coolant accident analysis by changing the axial power distribution of the domestic new fuel assembly; the axial power distribution includes the distribution of different power peak positions and different axial segment power shares;

[0041] The peak cladding temperature of the service life A under different power distribution conditions is obtained after the loss of coolant accident analysis, and the maximum peak cladding temperature is selected as the final maximum peak cladding temperature;

[0042] For the working condition where the final maximum peak cladding temperature occurs, the increased oxide film thickness during the loss of coolant process is obtained based on the BAKER-JUST model calculation;

[0043] The increased oxide film thickness is added to the initial oxide film thickness of the service life A to obtain the maximum oxide film thickness .

[0044] Further, the execution process of the second power distribution sensitivity analysis unit is as follows:

[0045] Take the service life B as the target service life, and perform the loss of coolant accident analysis by changing the axial power distribution of the domestic new fuel assembly; the axial power distribution includes the distribution of different power peak positions and different axial segment power shares;

[0046] Based on the BAKER-JUST model calculation, a plurality of maximum oxide film thicknesses increased during the loss of coolant process under different power conditions are obtained, and the maximum oxide film thickness increase is selected from them and added to the initial oxide film thickness of the service life B to obtain the maximum oxide film thickness .

[0047] In a third aspect, the present application further provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the above-mentioned loss of coolant accident analysis method for the domestic self-innovated new fuel assembly when executing the computer program.

[0048] In a fourth aspect, the present application further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the above-mentioned loss of coolant accident analysis method for the domestic self-innovated new fuel assembly.

[0049] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0050] The application is applied to the design and engineering application of the self-innovated new fuel assembly. The application specifies the optimization to be performed on the analysis process, mainly including the burnup sensitivity analysis and the power distribution sensitivity analysis, when performing the loss of coolant accident analysis on the self-innovated new fuel assembly, and establishes a method for optimizing three models based on the existing conservative system analysis program to obtain a loss of coolant accident analysis program suitable for the self-innovated new fuel assembly. The application is suitable for the self-innovated new fuel assembly, and improves the accuracy and efficiency of the loss of coolant accident analysis of the fuel assembly, and provides technical support for evaluating the safety performance of the fuel assembly under the loss of coolant accident condition. BRIEF DESCRIPTION OF DRAWINGS

[0051] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0052] Figure 1 The application is applied to the design and engineering application of the self-innovated new fuel assembly. The application specifies the optimization to be performed on the analysis process, mainly including the burnup sensitivity analysis and the power distribution sensitivity analysis, when performing the loss of coolant accident analysis on the self-innovated new fuel assembly, and establishes a method for optimizing three models based on the existing conservative system analysis program to obtain a loss of coolant accident analysis program suitable for the self-innovated new fuel assembly. The application is suitable for the self-innovated new fuel assembly, and improves the accuracy and efficiency of the loss of coolant accident analysis of the fuel assembly, and provides technical support for evaluating the safety performance of the fuel assembly under the loss of coolant accident condition.

[0053] Figure 2 The application is applied to the design and engineering application of the self-innovated new fuel assembly. The application specifies the optimization to be performed on the analysis process, mainly including the burnup sensitivity analysis and the power distribution sensitivity analysis, when performing the loss of coolant accident analysis on the self-innovated new fuel assembly, and establishes a method for optimizing three models based on the existing conservative system analysis program to obtain a loss of coolant accident analysis program suitable for the self-innovated new fuel assembly. The application is suitable for the self-innovated new fuel assembly, and improves the accuracy and efficiency of the loss of coolant accident analysis of the fuel assembly, and provides technical support for evaluating the safety performance of the fuel assembly under the loss of coolant accident condition. DETAILED DESCRIPTION

[0054] In order to make the objects, technical solutions and advantages of the application clearer, the application will be further described in detail below with reference to the embodiments and drawings, and the illustrative embodiments of the application and the description thereof are only used to explain the application, and do not limit the application.

[0055] The existing fuel assembly loss of coolant accident analysis method is not suitable for the self-innovated new fuel assembly, and there are problems of inaccurate loss of coolant accident analysis and low efficiency. The application is suitable for the self-innovated new fuel assembly, and how to obtain a suitable loss of coolant accident analysis program, how to optimize the analysis process based on the existing loss of coolant accident analysis method to obtain the conservative cladding peak temperature, cladding oxidation rate, hydrogen production share, etc., so as to evaluate the safety performance of the self-innovated new fuel assembly under the accident condition.

[0056] Unlike the previous fuel and the fuel assembly developed by the United States, the self-innovated CF series fuel assembly is different in the design of the lower nozzle and the cladding material. On the basis of the conventional large-break loss of coolant accident analysis, the application makes the following optimizations for the self-innovated new fuel assembly:

[0057] (I) Optimization of analysis process

[0058] The research shows that the highest cladding peak temperature PCT appears in different working conditions and the maximum oxidation rate OXI appears in different working conditions in the lifetime of the localized new fuel assembly in the large break loss of water accident, and therefore, the analysis needs to be carried out respectively for the two parameters. The previous loss of water accident analysis process generally includes: system sensitivity analysis, break spectrum sensitivity analysis, burnup sensitivity analysis and power distribution sensitivity analysis. For the localized new fuel assembly, the system sensitivity analysis process and the break spectrum sensitivity analysis process remain the same as those of other fuel assemblies, but the burnup sensitivity analysis process and the power distribution sensitivity analysis process are optimized. That is, the localized new fuel assembly loss of water accident analysis method of the application mainly involves the burnup sensitivity analysis and the power distribution sensitivity analysis.

[0059] (II) Optimization of analysis program and analysis model

[0060] The localized new fuel assembly loss of water accident analysis recommends using a conservative analysis program, for example: ARSAC. Based on this, the application optimizes the program and the key model in combination with the characteristics of the localized new fuel assembly. Specifically, it includes: establishing a new expanded cladding material property module, establishing a solidified fuel assembly inter-radiation heat transfer module, and implanting a cladding swelling and rupture module suitable for the localized new fuel assembly.

[0061] Embodiment 1

[0062] As shown in Figure 1 , the localized new fuel assembly loss of water accident analysis method of the application, the method includes:

[0063] Step 1: Select the system parameters and the break size of the reactor, calculate the maximum cladding peak temperature for different lifetimes according to the influence of different lifetime initial oxidation film thickness, initial internal pressure and gap width and other parameters, and obtain the lifetime A corresponding to the maximum cladding peak temperature, at the same time, calculate the maximum oxidation film thickness for different lifetimes, and obtain the lifetime B corresponding to the maximum oxidation film thickness;

[0064] Step 2: Take the lifetime A as the target lifetime, change the axial power distribution of the localized new fuel assembly to perform the loss of water accident analysis, obtain the final maximum cladding peak temperature, and obtain the increased oxidation film thickness in the loss of water accident process; add the increased oxidation film thickness to the initial oxidation film thickness of the lifetime A to obtain the maximum oxidation film thickness ;

[0065] Step 3: Take the lifetime B as the target lifetime, change the axial power distribution of the localized new fuel assembly to perform the loss of water accident analysis, obtain multiple oxidation film thicknesses increased in the loss of water accident process under different power conditions, and select the maximum one from them and add the initial oxidation film thickness of the lifetime B to obtain the maximum oxidation film thickness ;

[0066] Step 4, comparing the maximum oxide film thickness and the maximum oxide film thickness , taking the larger value as the final maximum oxide film thickness;

[0067] Step 5, comparing the final maximum cladding peak temperature and the final maximum oxide film thickness with the corresponding preset threshold values respectively, and analyzing whether there is a safety hazard under the loss of coolant accident.

[0068] In this embodiment, step 1 is mainly aimed at the new domestic fuel assembly to carry out burnup sensitivity analysis on the highest cladding peak temperature PCT parameter and to carry out burnup sensitivity analysis on the maximum oxide film thickness OXI. Among them, the new domestic fuel assembly refers to the fuel assembly with N36 cladding material.

[0069] Specifically, the system parameters of the reactor refer to the parameters with relatively high average temperature, relatively high pressure and relatively low pressurizer water level.

[0070] Specifically, step 1 includes:

[0071] Step 11, calculating the maximum cladding peak temperature for different service lives and obtaining the service life A corresponding to the maximum cladding peak temperature, including:

[0072] calculating the cladding peak temperature PCTBLX corresponding to the initial service life BLX, the cladding peak temperature PCTEOC1 corresponding to the end of the first cycle EOC1, the cladding peak temperature PCTEOC2 corresponding to the end of the second cycle EOC2 and the cladding peak temperature PCTEOC3 corresponding to the end of the third cycle EOC3 in turn;

[0073] selecting the maximum cladding peak temperature from the cladding peak temperature PCTBLX, the cladding peak temperature PCTEOC1, the cladding peak temperature PCTEOC2 and the cladding peak temperature PCTEOC3 as the maximum cladding peak temperature; and obtaining the service life corresponding to the maximum cladding peak temperature and taking it as the service life A.

[0074] Step 12, calculating the maximum oxide film thickness for different service lives and obtaining the service life B corresponding to the maximum oxide film thickness, including:

[0075] obtaining the hot rod wall temperature of the initial service life BLX, the end of the first cycle EOC1, the end of the second cycle EOC2 and the end of the third cycle EOC3 in turn, because the hot rod wall temperature changes with time;

[0076] The hot rod wall temperature is taken as the input of the BAKER-JUST model, and the oxide film thickness increase at the hot spot position of the hot rod during the loss of coolant accident process is calculated based on the BAKER-JUST model at four service lives (service life initial BLX, first cycle end EOC1, second cycle end EOC2, and third cycle end EOC3), respectively: ΔσBLX, ΔσEOC1, ΔσEOC2, and ΔσEOC3.

[0077] The oxide film thickness of each service life is added to the corresponding initial oxide film maximum thickness (assuming that the initial oxide film maximum thicknesses of the four service lives BLX, EOC1, EOC2, and EOC3 at the beginning of the loss of coolant accident are 0, σEOC1, σEOC2, and σEOC3, respectively), to obtain the oxide film thickness of each service life, respectively: σBLX'=ΔσBLX, σEOC1'=σEOC1+ΔσEOC1, σEOC2'=σEOC2+ΔσEOC2, and σEOC3'=σEOC3+ΔσEOC3.

[0078] The maximum oxide film thickness is selected from the oxide film thicknesses of the service lives, and the service life corresponding to the maximum oxide film thickness is obtained and taken as the service life B.

[0079] In this embodiment, step 2 specifically includes:

[0080] Step 21, taking service life A as the target service life, changing the axial power distribution of the localized new fuel assembly (different power peak positions, different axial segment power distribution) to perform the loss of coolant accident analysis.

[0081] Step 22, obtaining the cladding peak temperatures PCT1, PCT2, PCT3,..., PCTN of service life A under different power distributions after the loss of coolant accident analysis, and selecting the maximum cladding peak temperature as the final maximum cladding peak temperature PCTMAX.

[0082] Step 23, based on the BAKER-JUST model, the oxide film thickness increased during the loss of coolant process is calculated for the working condition where the final maximum cladding peak temperature appears.

[0083] Step 24, adding the increased oxide film thickness to the initial oxide film thickness of the first service life to obtain the first maximum oxide film thickness .

[0084] In this embodiment, step 3 specifically includes:

[0085] Step 31, taking the service life B as a target service life, performing a loss of coolant accident analysis by changing the axial power distribution (different power peak positions, different axial segment power share distributions) of the localized new fuel assembly; the axial power distribution includes different power peak positions and different axial segment power share distributions;

[0086] Step 32, based on the BAKER-JUST model calculation, obtaining a plurality of maximum oxidation film thicknesses increased during the loss of coolant process under different power conditions, respectively Δσ1, Δσ2, Δσ3,..., ΔσN; and selecting the maximum oxidation film thickness from them and adding the initial oxidation film thickness of the service life B to obtain the maximum oxidation film thickness .

[0087] In this embodiment, since the target service life A and the target service life B obtained in step 1 are generally different, the maximum oxidation film thickness is not equal to . Finally, for the localized new fuel assembly, the highest PCT is PCTMAX obtained in step 2, by comparing the values of the first maximum oxidation film thickness and the second maximum oxidation film thickness, and taking the larger value as the final maximum oxidation film thickness max 、 ).

[0088] In this embodiment, step 5 compares the final maximum cladding peak temperature and the final maximum oxidation film thickness with the corresponding preset threshold values, respectively. If at least one of them exceeds the corresponding preset threshold value, it means that there is a safety hazard under the loss of coolant accident; otherwise, there is no safety hazard under the loss of coolant accident.

[0089] Embodiment 2

[0090] The difference between this embodiment and embodiment 1 is that the method of the application is based on the design characteristics of the localized new fuel assembly cladding and related experimental results, on the basis of the existing loss of coolant accident analysis program (for example, ARSAC), to establish a new expanded cladding material property module, a solidified fuel assembly inter-radiation heat transfer module and a fuel assembly cladding swelling and rupture module, and to form an analysis program ARSAC-CF suitable for the localized new fuel assembly loss of coolant accident.

[0091] First, the expanded cladding material property module

[0092] Since the localized new fuel cladding is different from the traditional M5, ZR4, etc., for example, the N36 cladding adopts a zirconium-tin-niobium alloy, therefore, the material property module should be increased in combination with the experimental results of the material properties of the localized new fuel cladding. The functions performed by the material property module are as follows:

[0093] (1) It can calculate the thermal conductivity k of the new cladding at different temperatures;

[0094] (2) Can calculate the new type of cladding specific heat capacity pCp at different temperatures;

[0095] (3) Can calculate the emissivity of the new type of cladding under the condition of oxidation film and without oxidation film.

[0096] The above property modules should strictly refer to experimental results, and the temperature range of the cladding thermal conductivity and the cladding specific heat capacity should cover the temperature range of the cladding during the loss of coolant accident; The oxidation rate range obtained by converting the dependent variable oxidation film thickness in the emissivity calculation should cover the range of 0~17%.

[0097] In the above technical solution, the newly added expanded cladding material property module is for the new type of domestic fuel assembly, and the difference between the existing ARSAC and the corresponding property module for other fuel assemblies is that the density, thermal expansion coefficient, thermal conductivity, specific heat capacity, emissivity, and Poisson ratio are all functions of temperature.

[0098] Second, establish the solidified fuel assembly inter-radiation heat transfer module

[0099] Currently, the system analysis program at home and abroad is inefficient in calculating the inter-radiation heat transfer of the assembly, mainly reflected in that the user needs to carry out a lot of geometric customization, emissivity setting, and View Fator setting work when modeling.

[0100] For the new type of domestic fuel assembly, a relatively solidified fuel assembly inter-radiation heat transfer module is newly established in the conservative loss of coolant accident analysis program thermal component module. The core elements of this analysis module are as follows:

[0101] (1) According to the design features of the new type of domestic fuel assembly and the modeling requirements of the loss of coolant accident, four independent arrays with consistent dimensions are formed: Array 1 is the heat rod radiation heat transfer array, which stores the radiation heat transfer amount of the heat rod at each axial position and the heat assembly; Array 2 is the heat assembly radiation heat transfer amount 1, which stores the radiation heat transfer amount of the heat assembly at each axial position and the heat rod; Array 3 is the heat assembly radiation heat transfer amount 2, which stores the radiation heat transfer amount of the heat assembly at each axial position and the average assembly; Array 4 is the average assembly radiation heat transfer amount, which stores the radiation heat transfer amount of the average assembly at each axial position and the heat assembly;

[0102] (2) Core calculation module. Determine the oxidation state of the cladding surface according to the life state, and then determine the emissivity; determine the View Fator of each axial position of the thermal rod and each axial position of the thermal assembly, the View Fator of each axial position of the thermal assembly and each axial position of the thermal rod, the View Fator of each axial position of the thermal assembly and the average assembly, and the View Fator of each axial position of the average assembly and each axial position of the thermal assembly according to the user modeling data characteristics; obtain the difference between the fourth powers of the wall surface temperatures of the thermal rod, the thermal assembly, and the average assembly obtained by the last time step loss-of-coolant accident analysis. The radiation heat transfer amount between different axial positions calculated by the above three factors (emissivity, View Fator, and temperature fourth power difference) is stored in the array in the last core element;

[0103] (3) Activation module. For new fuel assemblies, whether to consider the inter-assembly radiation heat transfer at the current axial position needs to be determined by the void fraction size at this axial position. Only when the void fraction is greater than 0.8 and the cladding surface temperature is greater than 600°C, the module is activated;

[0104] (4) Data interaction module. The data transmission between the new module and other modules of the system program mainly includes: the new module needs to transfer the calculated radiation heat transfer amount to the thermal component module, the heat transfer amount of array 1 is included in the total heat transfer amount of the thermal rod, the heat transfer amount of array 2 and array 3 is included in the total heat transfer amount of the thermal assembly, and the heat transfer amount of array 4 is included in the total heat transfer amount of the average assembly. The new module needs to read the cladding wall surface temperature information and the oxidation film thickness information from the thermal component module of the system program at the last time step, and read the void fraction information from the system hydraulics module at the last time step.

[0105] After the fuel assembly inter-radiation heat transfer module is enabled, the four-dimensional independent arrays described in (1) are first generated, then the cladding wall surface temperature information and the oxidation film thickness information at the last time step are read from the thermal component module of the system program through the data interaction module of (4), the void fraction information at the last time step is read from the system hydraulics module, the condition of whether the void fraction is greater than 0.8 and the cladding surface temperature is greater than 600°C is determined by the activation module (3), when the condition is met, the core calculation module (2) is enabled to calculate the radiation heat transfer amount, and the radiation heat transfer amount is stored in the array established in (1), finally the stored radiation heat transfer amount is transmitted to the thermal component module of the system analysis program through the data interaction module (4).

[0106] Third, implanting a new fuel assembly cladding swelling and rupture model

[0107] The swelling and rupture model is used to estimate the time of fuel failure and the blockage effect on the flow channel after the failure. Since the strain rate of the new fuel assembly is a function of temperature, which is obtained from the strain rate experiment between 500℃ and 1000℃, the swelling and rupture model should be optimized by the fitting results. The strain rate of the new fuel assembly is an exponential function of temperature, and the exponential interpolation method is used to obtain the strain rate at different temperatures.

[0108] The data transfer relationship between the model and the original system analysis program is that the original system analysis program transfers the fuel cladding temperature, fuel rod internal pressure, fluid temperature and pressure, etc. to the new swelling and rupture model. The burst time and blockage rate calculated by the new swelling and rupture model are transferred to the hydraulic calculation module and the thermal component calculation module of the original system analysis program.

[0109] When the fuel swells and ruptures, on the one hand, the flow resistance will increase due to the blockage of the flow channel, and on the other hand, the heat transfer effect will be enhanced due to the change of the flow channel shape. Currently, there is no experimental study on the change of the heat transfer enhancement effect with the blockage rate. If the heat transfer enhancement factor is obtained in the future research, it can be supplemented to the swelling and rupture module as a method of safety margin for loss of coolant accident analysis.

[0110] In specific implementation, the specific operation process of the loss of coolant accident analysis of the new domestic fuel assembly is as follows:

[0111] Based on the conservative loss of coolant accident analysis program ARSAC, combined with the design characteristics of the new domestic fuel assembly cladding and the related experimental results, the new physical property module is established, the solidified assembly radiation heat transfer module is established, and the new fuel cladding swelling and rupture module is established. Form the loss of coolant accident analysis program ARSAC-CF suitable for domestic self-reliance fuel;

[0112] The ARSAC-CF program is tested and verified in all directions, including the functions of the three new modules, the data transfer function between the new modules and the original program, and the improved ability of the program to simulate the loss of coolant accident;

[0113] The optimized program is used to carry out the loss of coolant accident analysis for the new domestic self-reliance fuel assembly. The specific steps are as follows:

[0114] (1) Carry out system sensitivity analysis;

[0115] (2) Carry out break spectrum sensitivity analysis;

[0116] (3) Carry out burnup sensitivity analysis for the maximum cladding peak temperature parameter and the maximum cladding oxidation rate parameter, respectively;

[0117] (4) Perform power distribution sensitivity analysis for the maximum cladding peak temperature parameter and the maximum cladding oxidation rate parameter, respectively. Finally, select the maximum cladding peak temperature and the maximum cladding oxidation rate according to the requirements.

[0118] Embodiment 3

[0119] As shown in Figure 2 , the difference between this embodiment and embodiment 1 is that the application further provides a domestic self-determined type fuel assembly loss of coolant accident analysis system, which corresponds to the domestic self-determined new type fuel assembly loss of coolant accident analysis method of embodiment 1; the system comprises:

[0120] a burnup sensitivity analysis unit for selecting system parameters and break size of the reactor, calculating the maximum cladding peak temperature for different service lives according to the influence of different parameters such as initial oxidation film thickness, initial internal pressure and gap width, and obtaining the service life A corresponding to the maximum cladding peak temperature, and calculating the maximum oxidation film thickness for different service lives and obtaining the service life B corresponding to the maximum oxidation film thickness;

[0121] a first power distribution sensitivity analysis unit for taking the service life A as the target service life, performing loss of coolant accident analysis by changing the axial power distribution of the domestic new type fuel assembly, obtaining the final maximum cladding peak temperature, and obtaining the increased oxidation film thickness during the loss of coolant accident process; adding the increased oxidation film thickness to the initial oxidation film thickness of the service life A to obtain the maximum oxidation film thickness ;

[0122] a second power distribution sensitivity analysis unit for taking the service life B as the target service life, performing loss of coolant accident analysis by changing the axial power distribution of the domestic new type fuel assembly, obtaining multiple oxidation film thicknesses increased during the loss of coolant accident process under different power conditions, and selecting the maximum one and adding the initial oxidation film thickness of the service life B to obtain the maximum oxidation film thickness ;

[0123] a comparative analysis unit for comparing the maximum oxidation film thickness and the maximum oxidation film thickness , and taking the larger value as the final maximum oxidation film thickness.

[0124] As a further implementation, the execution process of the first power distribution sensitivity analysis unit is as follows:

[0125] taking the service life A as the target service life, performing loss of coolant accident analysis by changing the axial power distribution of the domestic new type fuel assembly; the axial power distribution includes different power peak positions and different axial segment power distribution;

[0126] The peak cladding temperature of the life A under different power distribution conditions is obtained after the loss of coolant accident analysis, and the maximum peak cladding temperature is selected as the final maximum peak cladding temperature;

[0127] The oxide film thickness increased in the loss of coolant process is obtained based on the BAKER-JUST model calculation under the working condition of the final maximum peak cladding temperature;

[0128] The maximum oxide film thickness is obtained by adding the initial oxide film thickness of the life A to the increased oxide film thickness .

[0129] As a further implementation, the execution process of the second power distribution sensitivity analysis unit is:

[0130] The loss of coolant accident analysis is performed by changing the axial power distribution of the localized new fuel assembly with the life B as the target life; the axial power distribution includes different power peak positions and different axial segment power distribution proportions;

[0131] The maximum oxide film thickness is obtained by adding the initial oxide film thickness of the life B to the maximum oxide film thickness increased in the loss of coolant process under different power conditions based on the BAKER-JUST model calculation .

[0132] The execution process of each unit can be performed according to the flow steps of the loss of coolant accident analysis method of the localized new fuel assembly in Embodiment 1, and the detailed description is not repeated in this embodiment.

[0133] The system of the application is a loss of coolant accident analysis system suitable for the CF series fuel designed independently by China. The analysis system specifies the optimization means that should be adopted in the analysis process and analysis program for the localized new fuel, and further establishes a complete set of loss of coolant accident analysis system reflecting the characteristics of the new fuel element and meeting the requirements of international regulations.

[0134] Meanwhile, the application further provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the localized new fuel assembly loss of coolant accident analysis method when executing the computer program.

[0135] Meanwhile, the application further provides a computer readable storage medium, which stores a computer program, and the computer program is executable on the processor to implement the localized new fuel assembly loss of coolant accident analysis method.

[0136] Those skilled in the art will appreciate that embodiments of the application can be readily used as software, hardware, or a combination of software and hardware. In one

[0137] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks in the flowcharts and / or a combination thereof. These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 an apparatus to perform the functions specified in the flowchart block or blocks.

[0138] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks in the flowcharts and / or a combination thereof. These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 an apparatus to perform the functions specified in the flowchart block or blocks.

[0139] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks in the flowcharts and / or a combination thereof. These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 an apparatus to perform the functions specified in the flowchart block or blocks.

[0140] The above description is only specific embodiments of the present application, and is not intended to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A new type of fuel assembly domestic self-determination loss of coolant accident analysis method, characterized in that, The method comprises: selecting system parameters and break size of the reactor, calculating maximum cladding peak temperature for different service lives according to different initial oxide film thicknesses, initial internal pressures and gap widths, and obtaining service life A corresponding to the maximum cladding peak temperature, and calculating maximum oxide film thickness for different service lives and obtaining service life B corresponding to the maximum oxide film thickness; taking the service life A as a target service life, performing loss of coolant accident analysis by changing axial power distribution of the localized new fuel assembly to obtain a final maximum cladding peak temperature and an increased oxide film thickness in the loss of coolant accident process, adding the increased oxide film thickness to the initial oxide film thickness of the service life A to obtain the maximum oxide film thickness of the service life A; taking the service life B as a target service life, performing loss of coolant accident analysis by changing axial power distribution of the localized new fuel assembly to obtain multiple oxide film thicknesses increased in the loss of coolant accident process under different power conditions, and selecting the maximum one and adding the initial oxide film thickness of the service life B to obtain the maximum oxide film thickness of the service life B; comparing the maximum oxide film thickness of the service life A and the maximum oxide film thickness of the service life B, and taking the larger one as a final maximum oxide film thickness.

2. The method of claim 1, wherein the method is characterized by, The method further comprises: comparing the final maximum cladding peak temperature and the final maximum oxide film thickness with corresponding preset thresholds respectively, and analyzing whether there is a safety hazard under the loss of coolant accident. 3.The method according to claim 1, wherein, The localized new fuel assembly refers to a fuel assembly with N36 cladding material. 4.The method according to claim 1, wherein, The calculation of the maximum cladding peak temperature for different service lives and the obtaining of service life A corresponding to the maximum cladding peak temperature comprise: The cladding peak temperature PCT corresponding to the initial stage, the end of the first cycle, the end of the second cycle and the end of the third cycle respectively are calculated in sequence BLX , the cladding peak temperature PCT EOC1 , the cladding peak temperature PCT EOC2 and the cladding peak temperature PCT EOC3 ; selecting the maximum cladding peak temperature from the cladding peak temperatures PCT BLX , the cladding peak temperature PCT EOC1 , the cladding peak temperature PCT EOC2 , and the cladding peak temperature PCT EOC3 as a maximum cladding peak temperature; and obtaining the service life corresponding to the maximum cladding peak temperature and taking it as the service life A. 5.The method of claim 1, wherein the method is characterized by, The calculation of the maximum oxide film thickness for different service lives and the obtaining of service life B corresponding to the maximum oxide film thickness comprise: obtaining thermal rod wall surface temperatures at the beginning of the service life, the end of the first cycle, the end of the second cycle and the end of the third cycle in sequence; taking the thermal rod wall surface temperatures as BAKER-JUST model inputs, calculating oxide film thickness increases in the loss of coolant accident process at the beginning of the service life, the end of the first cycle, the end of the second cycle and the end of the third cycle based on the BAKER-JUST model respectively; adding the oxide film thickness of each service life to the corresponding initial maximum oxide film thickness to obtain the oxide film thickness of each service life; selecting the maximum oxide film thickness from the oxide film thicknesses of the service lives as the maximum oxide film thickness, obtaining the service life corresponding to the maximum oxide film thickness and taking it as the service life B. 6.The method of claim 1, wherein, With the service life A as a target service life, through changing the axial power distribution of the localized new fuel assembly, a loss of coolant accident is analyzed, a final maximum cladding peak temperature is obtained, and an increased oxide film thickness during the loss of coolant accident is obtained; the increased oxide film thickness is added to an initial oxide film thickness of the service life A to obtain a maximum oxide film thickness , comprising: The loss of coolant accident analysis is performed by changing the axial power distribution of the localized new fuel assembly with the service life A as the target service life; the axial power distribution comprises distribution of different power peak positions and different axial segment power shares; the cladding peak temperature of the service life A under different power distribution conditions is obtained after the loss of coolant accident analysis, and the maximum cladding peak temperature is selected therefrom as a final maximum cladding peak temperature; the oxide film thickness increased in the loss of coolant process is calculated based on the BAKER-JUST model for the working condition where the final maximum cladding peak temperature appears; The increased oxide film thickness is added to the initial oxide film thickness of the service life A to obtain a maximum oxide film thickness . 7.The method of claim 1, wherein the method is characterized by, With the service life B as a target service life, by changing the axial power distribution of the localized new fuel assembly, a loss of coolant accident analysis is performed, a plurality of increased oxide film thicknesses in the loss of coolant accident process under different power conditions are obtained, and the maximum one is selected and added to the initial oxide film thickness of the service life B to obtain a maximum oxide film thickness comprising: The life period B is taken as a target life period, and a loss of coolant accident analysis is performed by changing an axial power distribution of the localized new fuel assembly; the axial power distribution includes different power peak positions and different axial segment power share distributions; Based on the calculation of the BAKER-JUST model, a plurality of maximum thicknesses of the oxide film increased during the water loss process under different power conditions are obtained, and the maximum thickness of the oxide film increased is selected from the plurality of maximum thicknesses of the oxide film increased, and the initial thickness of the oxide film of the service life B is added to obtain a maximum thickness of the oxide film . 8.The method of claim 1, wherein the method is characterized by, The method is based on an existing loss of coolant accident analysis program, and based on cladding design features of the localized new fuel assembly and related experimental results, a new expanded cladding material physical property module is established, a solidified fuel assembly inter-radiation heat exchange module is established, and a cladding swelling and rupture module suitable for the localized new fuel assembly is implanted, so that an analysis program suitable for the localized new fuel assembly loss of coolant accident is formed.

9. A new type of fuel assembly loss of coolant accident analysis system of domestic self-determination, characterized in that, The system comprises: The burnup sensitive analysis unit is configured to select system parameters and break size of the reactor, calculate maximum cladding peak temperature and obtain life period A corresponding to the maximum cladding peak temperature according to initial oxide film thickness, initial internal pressure and gap width of different life periods, and calculate maximum oxide film thickness and obtain life period B corresponding to the maximum oxide film thickness; a first power distribution sensitivity analysis unit, configured to take the service life A as a target service life, perform a loss of coolant accident analysis by changing an axial power distribution of the localized new fuel assembly, obtain a final maximum cladding peak temperature, and obtain an increased oxide film thickness during the loss of coolant accident; and add the increased oxide film thickness to an initial oxide film thickness of the service life A to obtain a maximum oxide film thickness ​ A second power distribution sensitivity analysis unit, taking the service life B as the target service life, changes the axial power distribution of the localized new fuel assembly to perform a loss of coolant accident analysis, obtains a plurality of increased oxide film thicknesses in the loss of coolant accident process under different power conditions, and selects the maximum one from them to add the initial oxide film thickness of the service life B to obtain the maximum oxide film thickness ; a comparative analysis unit for comparing the maximum oxide film thickness and the maximum oxide film thickness and the maximum oxide film thickness 10.The domestically self-developed new-type fuel assembly LOCA analysis system according to claim 9, characterized in that, The execution process of the first power distribution sensitive analysis unit is as follows: The life period A is taken as a target life period, and a loss of coolant accident analysis is performed by changing an axial power distribution of the localized new fuel assembly; the axial power distribution includes different power peak positions and different axial segment power share distributions; After the loss of coolant accident analysis, the cladding peak temperature of the life period A under different power distribution conditions is obtained, and the maximum cladding peak temperature is selected as the final maximum cladding peak temperature; For the working condition in which the final maximum cladding peak temperature appears, the increased oxide film thickness during the loss of coolant process is calculated based on the BAKER-JUST model. The increased oxide film thickness is added to the initial oxide film thickness of the service life A to obtain a maximum oxide film thickness .

11. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program to implement the localized new fuel assembly loss of coolant accident analysis method according to any one of claims 1 to 8.

12. A computer-readable storage medium, the computer-readable storage medium storing a computer program, characterized in that, The computer program is executed by the processor to implement the localized new fuel assembly loss of coolant accident analysis method according to any one of claims 1 to 8.

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