Method for analyzing accident fuel core meltdown accidents, computing device, and storage medium

Abstract

This application provides a method, computing device, and storage medium for analyzing accident-resistant fuel core meltdown accidents, relating to the field of nuclear reactor technology. The method provided includes calculations of post-accident core temperature rise and oxidation, oxide layer thinning, fuel cladding damage and fuel collapse, fission product release, and molten pool interaction and heat transfer. This forms a safety analysis method for accident-resistant fuels in core meltdown accidents, supporting the demonstration of safety improvements after accident-resistant fuel core meltdown accidents and guiding the research and design of accident-resistant fuels.

Description

Technical Field

[0001] This application relates to the field of nuclear reactor technology, and in particular to an accident-resistant fuel core meltdown accident analysis method, computing device and storage medium. Background Technology

[0002] Following the Fukushima nuclear accident in 2011, in order to improve the safety of nuclear power plants and cope with the event of a complete power outage, the international nuclear fuel community proposed the concept of Accident Tolerant Fuel (ATF), which enhances accident resilience. Accident Tolerant Fuel is a fuel technology that significantly mitigates the consequences of an accident and slows down its progression while maintaining or improving fuel performance under normal operation and anticipated transient conditions.

[0003] Accident-resistant fuel safety analysis methods are a crucial component of accident-resistant fuel development. Accident-resistant fuels differ significantly from conventional nuclear power plant uranium dioxide (UO2) pellet-zirconium (Zr) alloy cladding fuel systems; their post-accident response differs markedly from that of conventional fuels. Therefore, conventional fuel safety assessment methods are not applicable to accident-resistant fuels. A comprehensive safety assessment should be conducted on accident-resistant fuels before they can be commercialized. Summary of the Invention

[0004] To alleviate, mitigate, or eliminate the aforementioned technical problems, this application provides a method, computing device, and storage medium for analyzing fuel core meltdown accidents in resistant fuel reactors, thereby solving the problem of the lack of such methods in the prior art.

[0005] In a first aspect, this application provides a method for analyzing fuel core meltdown accidents that are resistant to accidents, characterized by comprising:

[0006] Parameter initialization;

[0007] Calculations on core temperature rise and oxidation after accident based on an accident-resistant fuel oxidation model;

[0008] Oxide layer thinning calculations were performed based on an accident-resistant fuel cladding volatilization model.

[0009] Calculations on fuel cladding damage and fuel collapse based on the mechanism of accident-resistant fuel failure;

[0010] Fission product release was calculated based on an accident-resistant fuel fission product release model.

[0011] Based on the reaction products and migration process between the post-accident anti-accident fuel pellets and cladding and the coolant and reactor internals, we conducted molten pool interaction and heat transfer analysis.

[0012] In one possible implementation, the oxidation reaction equation in the accident-resistant fuel oxidation model is:

[0013] N1 cladding material + N2 H2O = N3 oxidation product + N4CO + N5H2 + N6CO2 + N1Q1;

[0014] Where, N i It is the input factor for the molar number of reactants and products, i=1,2,3,…,6, and Q1 is the heat of reaction of the material.

[0015] In one possible implementation, the kinetic equation for the cladding oxidation reaction in the accident-resistant fuel oxidation model is:

[0016] ;

[0017] Where dl / dt is the oxide layer growth rate, in m / s; ρ1 is the oxide layer density, in kg / m³. 3 T1 is the cladding temperature in K; R is the universal gas constant; f(P) is a function of the reaction pressure; m1 and m2 are coefficients.

[0018] In one possible implementation, the volatilization reaction equation in the accident-resistant fuel cladding volatilization model is:

[0019] M1 coated oxide + M2 H2O = product + M1Q2;

[0020] Among them, M j Q1 is the input factor for the molar number of reactants and products, j=1,2; Q2 is the volatilization reaction energy of the oxide.

[0021] In one possible implementation, the kinetic equation for the volatilization reaction in the accident-resistant fuel cladding volatilization model is:

[0022] ;

[0023] Where dh / dt is the evaporation rate of the oxide layer, in m / s; v is the vapor velocity, in m / s; and ρ2 is the density of the oxide layer, in kg / m³. 3 T2 is the cladding temperature in K; R is the universal gas constant; g(P) is a function of the reaction pressure; k1, k2 and k3 are coefficients.

[0024] In one possible implementation, the fission product release calculation based on the accident-resistant fuel fission product release model includes:

[0025] The release of fission products was calculated based on the temperature-dependent diffusion coefficient and release rate equation.

[0026] In one possible implementation, the diffusion coefficient is in the form of:

[0027] ;

[0028] Where A is the diffusion coefficient, A0 is the diffusion factor specific to the fission product group, Q3 is the activation energy, R is the universal gas constant, and T3 is the cladding temperature.

[0029] In one possible implementation, the release rate equation is:

[0030] ;

[0031] ;

[0032] Where E is the release rate, A T These are the criteria parameters for the piecewise function, and a, A1, B1, C1, A2, B2, and C2 are coefficients.

[0033] Secondly, this application provides a computing device, comprising:

[0034] At least one processor; and

[0035] At least one memory storing instructions that, when executed individually or jointly by the at least one processor, cause the computing device to perform the method according to the first aspect.

[0036] Thirdly, this application provides a computer storage medium storing instructions that, when executed individually or jointly by at least one processor of a computing device, cause the computing device to perform the method according to the first aspect.

[0037] Compared with the prior art, this application has the following advantages:

[0038] The accident analysis method for resistant fuel core meltdown provided in this application includes calculations of core temperature rise and oxidation after the accident, calculations of oxide layer thinning, calculations of fuel cladding damage and fuel collapse, calculations of fission product release, and analysis of molten pool interaction and heat transfer. This forms a safety analysis method for resistant fuel in core meltdown accidents, supports the demonstration of safety improvement after resistant fuel core meltdown accidents, and guides the research and development and design of resistant fuel. Attached Figure Description

[0039] The accompanying drawings are included to provide a further understanding of this application; they are incorporated into and constitute a part of this application. The drawings illustrate embodiments of this application and, together with this specification, serve to explain the principles of this application. In the drawings:

[0040] Figure 1 This is a schematic flowchart of an accident-resistant fuel core meltdown accident analysis method provided in an embodiment of this application;

[0041] Figure 2This is a schematic diagram of the structure of a computing device provided in an embodiment of this application. Detailed Implementation

[0042] The principles of this application will now be described with reference to some embodiments. It should be understood that these embodiments are described for illustrative purposes only and to help those skilled in the art to understand and implement this application, and do not impose any limitation on the scope of this application. The disclosure described herein may be implemented in ways other than those described below.

[0043] In the following description, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0044] References to "an embodiment," "embodiment," "exemplary embodiment," etc., in this application indicate that the described embodiment may include specific features, structures, or characteristics, but not every embodiment needs to include specific features, structures, or characteristics. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in conjunction with an exemplary embodiment, whether explicitly described or not, those skilled in the art will recognize that such a feature, structure, or characteristic affects its association with other embodiments.

[0045] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. The singular forms “a,” “an,” and “the” used herein also include the plural forms unless the context clearly indicates otherwise. The terms “a group of elements” or “a collection of elements” as used herein are intended to include one or more elements. It should also be understood that the terms “comprising,” “including,” “having,” “possessing,” “including,” and / or “comprising,” when used herein, specify the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0046] Furthermore, it should be noted that the use of terms such as "first" and "second" to define the objects is merely for the purpose of distinguishing the corresponding objects. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0047] Flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, various steps can be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0048] Figure 1This is a schematic flowchart of a method for analyzing fuel core meltdown accidents to prevent accidents, provided in an embodiment of this application. Figure 1 As shown, the analysis method for accident-resistant fuel core meltdown accidents includes the following:

[0049] Step 110: Parameter initialization.

[0050] Specifically, the design and physical property parameters of the accident-resistant fuel are obtained, and these parameters are used for parameter initialization. The design parameters of the accident-resistant fuel include the structural dimensions of the pellets and cladding, while the physical property parameters include the density, thermal conductivity, heat capacity, and specific enthalpy of the accident-resistant fuel.

[0051] Step 120: Calculate the core temperature rise and oxidation after the accident based on the accident-resistant fuel oxidation model.

[0052] The general reaction equation for oxidation is:

[0053] N1 cladding material + N2 H2O = N3 oxidation product + N4CO + N5H2 + N6CO2 + N1Q1;

[0054] Where, N i This is an input factor representing the molar numbers of reactants and products, i = 1, 2, 3, ..., 6, where Q1 is the heat of reaction of the material. Different accident-resistant fuels produce different products, including some nitrogen. i It is zero.

[0055] In some embodiments, the kinetic equation for the oxidation reaction of the anti-accident fuel cladding has a typical parabolic function form and a reaction rate constant of the Arrhenius form. The kinetic equation for the cladding oxidation reaction is as follows:

[0056] ;

[0057] Where dl / dt is the oxide layer growth rate, in m / s; ρ1 is the oxide layer density, in kg / m³. 3 T1 is the cladding temperature in K; R is the universal gas constant, specifically 8314.34 J / (kmol·K); f(P) is a function of the reaction pressure; m1 and m2 are coefficients.

[0058] Oxidation exothermics will cause the reactor core temperature to rise. The reactor core temperature rise model can use existing heat transfer equations, which will not be described in detail here.

[0059] Step 130: Calculate oxide layer thinning based on the accident-resistant fuel cladding volatilization model.

[0060] The general equation for a volatile reaction is:

[0061] M1 coated oxide + M2 H2O = product + M1Q2;

[0062] Among them, M j Q1 is the input factor for the molar number of reactants and products, j=1,2; Q2 is the volatilization reaction energy of the oxide.

[0063] In some embodiments, the rate of oxide layer loss (or thinning) can be calculated using the following kinetic equation for the evaporation reaction of the coating:

[0064] ;

[0065] Where dh / dt is the evaporation rate of the oxide layer, in m / s; v is the vapor velocity, in m / s; and ρ2 is the density of the oxide layer, in kg / m³. 3 T2 is the cladding temperature in K; R is the universal gas constant, specifically 8314.34 J / (kmol·K); g(P) is a function of the reaction pressure; k1, k2, and k3 are coefficients.

[0066] Step 140: Calculate fuel cladding damage and fuel collapse based on the fuel failure mechanism against accidents.

[0067] For accident-resistant fuel materials, based on their properties such as material limits or melting points, criteria for fuel cladding fracture, control rod fracture, and fuel collapse in calculations are determined. For example, cladding and control rod fracture are generally based on temperature criteria determined experimentally, while fuel collapse is generally considered to occur when the node melting point is reached.

[0068] Step 150: Calculate the release of fission products based on the accident-resistant fuel fission product release model.

[0069] For accident-resistant fuel materials, fission product release is calculated based on temperature-dependent diffusion coefficient and release rate equation.

[0070] The temperature-dependent diffusion coefficient is in the form of:

[0071] = ;

[0072] Where A is the temperature-dependent diffusion coefficient, A0 is the diffusion factor specific to the fission product group, Q3 is the activation energy, and Q... f It is Q3 / R for each fission product group, where R is the universal gas constant, specifically 8314.34 J / (kmol·K), and T3 is the cladding temperature.

[0073] Furthermore, the release rate equation is:

[0074] ;

[0075] ;

[0076] Where E is the release rate, A T These are the judgment parameters of the piecewise function. Based on experiments, a, A1, B1, C1, A2, B2, and C2 are coefficients.

[0077] Step 160: Analysis of molten pool interaction and heat transfer.

[0078] Specifically, based on the reaction products and migration processes of the anti-accident fuel pellets and cladding with the coolant and reactor internals after the accident, the layered structure and composition of the molten pool inside the lower head are determined. Based on this, molten pool interaction and heat transfer analysis are performed. The main process includes: determining the migrating components and mass within the molten pool; considering migration transients and inter-component interaction mechanisms, determining the distribution of interlayer components; and based on the layering, determining the distribution of heat sources and hard shell within the molten pool, as well as the cooling conditions of the outer wall surface. Generally, lumped parameter or CFD methods can be used for heat transfer analysis.

[0079] It should be noted that for different types of accident-resistant fuels, the materials and forms of fuel pellets and cladding are different, and the fuel-coolant interaction phenomena after an accident are different. Therefore, the oxidation process, oxide layer thinning, fuel cladding damage and fuel collapse, as well as the molten pool layering structure in the above embodiments may be different.

[0080] Figure 2 This is a schematic diagram of the structure of a computing device provided in an embodiment of this application. Figure 2 As shown, computing device 200 includes one or more processors 210, one or more memories 220 coupled to processor 210, and one or more communication modules 240 coupled to processor 210.

[0081] Communication module 240 is used for bidirectional communication. Communication module 240 has at least one antenna to facilitate communication. The communication interface can represent any interface necessary for communication with other network elements.

[0082] Processor 210 can be of any type suitable for a local technology network, and as a non-limiting example, can include one or more of the following: general-purpose computer, special-purpose computer, microprocessor, digital signal processor (DSP), and processor based on a multi-core processor architecture. Computing device 200 can have multiple processors, such as application-specific integrated circuit (ASIC) chips, which are timely driven to a clock synchronized with the main processor.

[0083] Memory 220 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 224, electrically programmable read-only memory (EPROM), flash memory, hard disk, optical disc (CD), digital video disc (DVD), and other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 222 and other volatile memories that do not persist during power-off periods.

[0084] Computer program 230 includes computer-executable instructions that are executed by the associated processor 210. Program 230 may be stored in ROM 224. Processor 210 may perform any appropriate actions and processes by loading program 230 into RAM 222.

[0085] The embodiments of this application can be implemented by program 230, enabling computing device 200 to execute the reference. Figure 1 Any process disclosed in the discussion. Embodiments of this application may also be implemented by hardware or by a combination of software and hardware.

[0086] In some embodiments, program 230 may be tangibly contained in a computer-readable medium, which may be contained in computing device 200 (e.g., memory 220) or other storage device accessible to computing device 200. Computing device 200 may load program 230 from the computer-readable medium into RAM 222 for execution. The computer-readable medium may include any type of tangible non-volatile memory, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. Program 230 is stored on the computer-readable medium.

[0087] Generally, the various embodiments of this application can be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while others may be implemented in firmware or software, which may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of this application are shown and described as block diagrams, flowcharts, or other graphical representations, it should be understood that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0088] This application also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in a program module, which execute in a device on a target real or virtual processor to perform the aforementioned references. Figure 1The method described herein. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of a program module can be combined or separated among program modules as needed. The machine-executable instructions used in the program module can execute on a local or distributed device. In a distributed device, the program module can reside on both local and remote storage media.

[0089] The program code used to perform the methods of this application can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when the program code is executed by the processor or controller, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The program code can be executed entirely on a machine, partially on a machine, partially on a remote machine, partially on a remote machine, or entirely on a remote machine or server as a standalone software package.

[0090] In the context of this application, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, etc.

[0091] Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable media can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or apparatuses, or any suitable combination thereof. More specific examples of computer-readable storage media include electrical connections having one or more wires, portable computer floppy disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0092] Furthermore, although the operations are described in a specific order, this should not be construed as requiring that these operations be performed in the specific order or sequence shown, or that all of the operations shown be performed to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the foregoing discussion, these details should not be construed as limiting the scope of this application, but rather as descriptions of features specific to particular embodiments. Certain features described in the context of a single embodiment may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0093] Although this application has been described in language specific to structural features and / or methodological behavior, it should be understood that the application as defined in the appended claims is not necessarily limited to the specific features or behaviors described above. Rather, the specific features and actions described above are disclosed as exemplary forms for implementing the claims.

Claims

1. A method for analyzing fuel core meltdown accidents in reactors, characterized in that, include: Parameter initialization; Calculations on core temperature rise and oxidation after accident based on an accident-resistant fuel oxidation model; Oxide layer thinning calculations were performed based on an accident-resistant fuel cladding volatilization model. Calculations on fuel cladding damage and fuel collapse based on the mechanism of accident-resistant fuel failure; Fission product release was calculated based on an accident-resistant fuel fission product release model. Based on the reaction products and migration process of post-accident anti-accident fuel pellets and cladding with coolant and reactor internals, we conduct molten pool interaction and heat transfer analysis. The kinetic equation for the cladding oxidation reaction in the accident-resistant fuel oxidation model is as follows: ； wherein dl / dt is the oxide layer growth rate in m / s; pi is the oxide layer density in kg / m 3 ; T1 is the cladding temperature in K; R is the universal gas constant; f(P) is a function of the reaction pressure; m1 and m2 are coefficients; The kinetic equation for the volatilization reaction in the anti-accident fuel cladding volatilization model is as follows: ； Where dh / dt is the evaporation rate of the oxide layer, in m / s; v is the vapor velocity, in m / s; and ρ2 is the density of the oxide layer, in kg / m³. 3 T2 is the cladding temperature in Kelvin; R is the universal gas constant; g(P) is a function of the reaction pressure; k1, k2, and k3 are coefficients. The fission product release calculation based on the accident-resistant fuel fission product release model includes: fission product release calculation based on temperature-dependent diffusion coefficient and release rate equation; wherein the diffusion coefficient is in the form of: ； Where A is the diffusion coefficient, A0 is the diffusion factor specific to the fission product group, Q3 is the activation energy, R is the universal gas constant, and T3 is the cladding temperature; The release rate equation is: ； ； Where E is the release rate, A T These are the criteria parameters for the piecewise function, and a, A1, B1, C1, A2, B2, and C2 are coefficients.

2. The method as described in claim 1, characterized in that, The oxidation reaction equation in the accident-resistant fuel oxidation model is: N1 cladding material + N2 H2O = N3 oxidation product + N4CO + N5H2 + N6CO2 + N1Q1; Where, N i It is the input factor for the molar number of reactants and products, i=1,2,3,…,6, and Q1 is the heat of reaction of the material.

3. The method as described in claim 1, characterized in that, The volatilization reaction equation in the anti-accident fuel cladding volatilization model is as follows: M1 coated oxide + M2 H2O = product + M1Q2; Among them, M j Q1 is the input factor for the molar number of reactants and products, j=1,2; Q2 is the volatilization reaction energy of the oxide.

4. A computing device, characterized in that, include: At least one processor; as well as At least one memory storing instructions that, when executed individually or jointly by the at least one processor, cause the computing device to perform the method according to any one of claims 1-3.

5. A computer storage medium, characterized in that, The computer storage medium stores instructions that, when executed individually or jointly by at least one processor of the computing device, cause the computing device to perform the method according to any one of claims 1-3.

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