Anti-accident fuel reactor core melting accident analysis method, computing equipment and storage medium

Abstract

The invention provides an anti-accident fuel reactor core melting accident analysis method, computing equipment and a storage medium, and relates to the technical field of nuclear reactors. The anti-accident fuel reactor core melting accident analysis method comprises the steps of post-accident reactor core temperature rise and oxidation calculation, oxidation layer thinning calculation, fuel cladding damage and fuel collapse calculation, fission product release calculation and molten pool interaction and heat transfer analysis, and the anti-accident fuel safety analysis method in the reactor core melting accident is formed. The safety improvement after the accident-resistant fuel reactor core melting accident is supported and demonstrated, and the research, development and design of the accident-resistant fuel are guided.

Description

Technical Field

[0001] The present application relates to the field of nuclear reactor technology, and in particular to an accident-resistant fuel core melting accident analysis method, computing equipment and storage medium. Background Art

[0002] After the Fukushima nuclear accident in 2011, in order to improve the safety of nuclear power plants to cope with power outages, the international nuclear fuel community proposed the concept of accident-tolerant fuel (ATF) with enhanced accident tolerance. Accident-tolerant fuel is a fuel technology that significantly mitigates the consequences of accidents and delays the progress of accidents while maintaining or improving the fuel performance of normal operation and expected transient conditions.

[0003] The safety analysis method of accident-resistant fuel is an important part of the research and development of accident-resistant fuel. Accident-resistant fuel is different from the uranium dioxide (UO2) pellet-zirconium (Zr) alloy cladding fuel system of traditional nuclear power plants. Its post-accident response is significantly different from that of traditional fuel. Traditional fuel safety assessment methods are not suitable for accident-resistant fuel. Before the commercialization of accident-resistant fuel, a comprehensive safety assessment should be conducted on it. Summary of the invention

[0004] In order to alleviate, mitigate or eliminate the above-mentioned technical problems, the present application provides an accident-resistant fuel core melting accident analysis method, computing equipment and storage medium to solve the problem of lack of accident-resistant fuel core melting accident analysis method in the prior art.

[0005] In a first aspect, the present application provides a method for analyzing an accident-resistant fuel core melt accident, characterized in that it includes:

[0006] Parameter initialization;

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

[0008] Calculation of oxide layer thinning based on the accident-resistant fuel cladding volatilization model;

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

[0010] Calculate the fission product release based on the accident-resistant fuel fission product release model;

[0011] Based on the reaction products and migration process between the accident-resistant fuel cores and cladding and the coolant and reactor internals after the accident, the melt pool interaction and heat transfer analysis is carried out.

[0012] In a 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] Among them, N i are the input factors of the molar numbers of reactants and products, i = 1, 2, 3, …, 6, and Q1 is the heat of reaction of the material.

[0015] In a possible implementation, the kinetic equation of 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 / 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.

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

[0019] M1 shell oxide + M2 H2O = product + M1Q2

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

[0021] In a possible implementation, the volatilization reaction kinetic equation 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 steam velocity, in m / s; ρ2 is the density of the oxide layer, in kg / m 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 a possible implementation, the fission product release calculation based on the accident-resistant fuel fission product release model includes:

[0025] Fission product release calculations are performed based on temperature-dependent diffusion coefficients and release rate equations.

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

[0027]

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

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

[0030]

[0031] Where E is the release rate, A T are the judgment parameters of the piecewise function, and a, A1, B1, C1, A2, B2 and C2 are coefficients.

[0032] In a second aspect, the present application provides a computing device, including:

[0033] at least one processor; and

[0034] At least one memory having instructions stored thereon, which, when executed individually or collectively by the at least one processor, cause the computing device to perform the method according to the first aspect.

[0035] In a third aspect, the present application provides a computer storage medium having instructions stored thereon, which, when executed individually or collectively by at least one processor of a computing device, causes the computing device to execute the method described in the first aspect.

[0036] Compared with the prior art, this application has the following advantages:

[0037] The accident analysis method for accident-resistant fuel core melting accidents provided in the present 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 melt pool interaction and heat transfer, forming a safety analysis method for accident-resistant fuel in core melting accidents, supporting the demonstration of safety improvement after accident-resistant fuel core melting accidents, and guiding the research and development and design of accident-resistant fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings are included to provide a further understanding of the present application. They are included and constitute a part of the present application. The accompanying drawings illustrate embodiments of the present application and together with the present specification serve to explain the principles of the present application. In the accompanying drawings:

[0039] Figure 1 It is a schematic flow chart of a method for analyzing an accident-resistant fuel core melting accident provided in an embodiment of the present application;

[0040] Figure 2 It is a structural diagram of a computing device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] The principle of the present application will now be described with reference to some embodiments. It should be understood that the description of these embodiments is only for illustrative purposes, and helps those skilled in the art to understand and implement the present application, without any limitation to the scope of the present application. The disclosure described herein can be implemented in a manner different from that described below.

[0042] In the following description, unless defined otherwise, 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 belongs.

[0043] References in this application to "one embodiment," "an embodiment," "an exemplary embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. In addition, when a particular feature, structure, or characteristic is described in conjunction with an exemplary embodiment, whether or not explicitly described, those skilled in the art will recognize that such feature, structure, or characteristic may affect incorporation into other embodiments.

[0044] The terms used herein are only for describing specific embodiments, rather than for limiting exemplary embodiments. The singular forms "one", "an", and "the" used herein also include plural forms, unless the context clearly indicates otherwise. "A group of elements" or "element set" used herein is intended to include one or more elements. It should also be understood that the terms "include", "comprise", "have", "have", "include" and / or "include", when used herein, specify the presence of the features, elements and / or parts, etc., but do not exclude the presence or addition of one or more other features, elements, parts and / or combinations thereof.

[0045] In addition, it should be noted that the use of words such as "first" and "second" to limit objects is only to facilitate the distinction between corresponding objects. Unless otherwise stated, the above words have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0046] Flowcharts are used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed accurately in order. On the contrary, various steps may be processed in reverse order or simultaneously. At the same time, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0047] Figure 1 1 is a flow chart of a method for analyzing an accident-resistant fuel core melting accident provided in an embodiment of the present application. Figure 1 As shown, the accident analysis method for accident-resistant fuel core melting includes the following contents:

[0048] Step 110: Initialize parameters.

[0049] 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 pellet and the cladding, and the physical property parameters include the density, thermal conductivity, heat capacity, specific enthalpy, etc. of the accident-resistant fuel.

[0050] Step 120: Calculate the core temperature rise and oxidation after the accident based on the accident-resistant fuel oxidation model.

[0051] The general reaction equation for the oxidation reaction is:

[0052] N1 cladding material + N2 H2O = N3 oxidation product + N4CO + N5H2 + N6CO2 + N1Q1

[0053] Among them, N i is the input factor of the number of moles of reactants and products, i = 1, 2, 3, ..., 6, Q1 is the heat of reaction of the material. Different products are generated for different accident-resistant fuels, and some N i is zero.

[0054] In some embodiments, the kinetic equation of the oxidation reaction of the accident-resistant fuel cladding has a typical parabolic function form and a reaction rate constant in the Arrhenius form. The kinetic equation of the oxidation reaction of the cladding is:

[0055]

[0056] Where dl / dt is the oxide layer growth rate in m / s; ρ1 is the oxide layer density in kg / m 3 ; T1 is the cladding temperature, unit is 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.

[0057] Oxidation heat release will cause the core temperature to rise. The core temperature rise model can adopt the existing heat transfer equation, which will not be introduced in detail here.

[0058] Step 130: Calculate the oxide layer thinning based on the accident-resistant fuel cladding volatilization model.

[0059] The volatilization reaction equation is generally:

[0060] M1 shell oxide + M2 H2O = product + M1Q2

[0061] Among them, M j is the input factor of the molar number of reactants and products, j = 1,2; Q2 is the volatilization reaction energy of the oxide.

[0062] In some embodiments, the rate of oxide layer loss (or thinning) may be calculated using the following cladding volatilization reaction kinetic equation:

[0063]

[0064] Where dh / dt is the evaporation rate of the oxide layer, in m / s; v is the steam velocity, in m / s; ρ2 is the density of the oxide layer, in kg / m 3 ; T2 is the cladding temperature, unit is 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.

[0065] Step 140: Calculate fuel cladding damage and fuel collapse based on the accident-resistant fuel failure mechanism.

[0066] For accident-resistant fuel materials, combined with the performance of accident-resistant fuel materials, such as material limits or melting points, the criteria for fuel cladding rupture, control rod rupture and fuel collapse in the calculation are determined. For example, the cladding and control rod ruptures generally use temperature criteria, and according to experimental determination, fuel collapse is generally considered to reach the node melting point.

[0067] Step 150: Calculate the fission product release based on the accident-resistant fuel fission product release model.

[0068] For accident-resistant fuel materials, fission product release calculations are performed based on temperature-dependent diffusion coefficients and release rate equations.

[0069] where the temperature-dependent diffusion coefficient has the form:

[0070]

[0071] where A is the temperature-dependent diffusion coefficient, A0 is the fission product group-specific diffusion factor, Q3 is the activation energy, and Q f is Q3 / R for each fission product group, R is the universal gas constant, specifically 8314.34 J / (kmol·K), and T3 is the cladding temperature.

[0072] Furthermore, the release rate equation is:

[0073]

[0074] Where E is the release rate, A T are the judgment parameters of the piecewise function, determined by experiments, and a, A1, B1, C1, A2, B2 and C2 are coefficients.

[0075] Step 160: melt pool interaction and heat transfer analysis.

[0076] Specifically, based on the reaction products and migration process of the accident-resistant fuel cores and cladding with the coolant and the internal components after the accident, the layered structure and composition of the molten pool in the lower head are determined, and the molten pool interaction and heat transfer analysis are carried out on this basis. The main process includes: determining the migration components and mass in the molten pool, considering the transient migration and interaction mechanism between components, and determining the distribution of interlayer components; according to the layered situation, determining the heat source distribution and hard shell distribution of the molten pool, as well as the cooling conditions of the outer wall, generally, the lumped parameter or CFD method can be used to carry out heat transfer analysis.

[0077] It should be noted that for different types of accident-resistant fuels, the materials and forms of the fuel cores and cladding are different, and the fuel-coolant interaction phenomena after the accident are different. The oxidation process, oxide layer thinning, fuel cladding damage and fuel collapse, and molten pool layered structure in the above embodiments may be different accordingly.

[0078] Figure 2 Schematic diagram of a computing device provided in an embodiment of the present 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 .

[0079] The communication module 240 is used for two-way communication. The communication module 240 has at least one antenna to facilitate communication. The communication interface may represent any interface necessary for communicating with other network elements.

[0080] Processor 210 may be of any type suitable for the local technology network, and may include, as non-limiting examples, one or more of: a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Computing device 200 may have multiple processors, such as application specific integrated circuit chips, which are driven in time to a clock that synchronizes a master processor.

[0081] The 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, compact disk (CD), digital video disk (DVD), and other magnetic and / or optical memories. Examples of volatile memories include, but are not limited to, random access memory (RAM) 222 and other volatile memories that do not persist during the duration of a power outage.

[0082] The computer program 230 includes computer executable instructions that are executed by the associated processor 210. The program 230 may be stored in the ROM 224. The processor 210 may perform any suitable actions and processes by loading the program 230 into the RAM 222.

[0083] The embodiment of the present application can be implemented by the program 230, so that the computing device 200 can execute the reference Figure 1 Any process disclosed in the discussion. The embodiments of the present application may also be implemented by hardware or by a combination of software and hardware.

[0084] In some embodiments, the program 230 may be tangibly contained in a computer-readable medium, which may be contained in the computing device 200 (e.g., memory 220) or other storage device accessible to the computing device 200. The computing device 200 may load the program 230 from the computer-readable medium to the 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. The computer-readable medium has the program 230 stored thereon.

[0085] Generally, various embodiments of the present application may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Certain aspects may be implemented in hardware, while other aspects may be implemented in firmware or software, which may be performed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present application are shown and described as block diagrams, flow charts, or using some 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 circuits or logic, general hardware or controllers or other computing devices, or some combination thereof.

[0086] The present 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 program modules, which are executed in a device on a target real or virtual processor to perform the above-mentioned reference Figure 1 The method described. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of program modules can be combined or separated between program modules as needed. Machine executable instructions for program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in local and remote storage media.

[0087] The program code for executing the method of the present application can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing equipment so that when the program code is executed by the processor or controller, the function / operation specified in the flow chart and / or the block diagram is realized. The program code can be executed completely on the machine as an independent software package, partially on the machine, partially on the machine, partially on a remote machine, partially on a remote machine, or all on a remote machine or server.

[0088] In the context of this application, computer program codes or related data may be carried by any appropriate carrier to enable a device, apparatus or processor to perform various processes and operations as described above. Examples of carriers include signals, computer readable media, etc.

[0089] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or apparatuses, or any suitable combination of the foregoing. More specific examples of computer readable storage media include an electrical connection with one or more wires, a portable computer floppy disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0090] In addition, although the operations are described in a specific order, this should not be construed as requiring to perform these operations in the specific order or sequence shown, or to perform all the operations shown, to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these details should not be interpreted as limiting the scope of the application, but can be interpreted as a description of the specific features of a particular embodiment. Some of the features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0091] Although the present application has been described in language specific to structural features and / or methodological acts, it should be understood that the present application defined in the appended claims is not necessarily limited to the specific features or acts described above. Instead, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method for analyzing an accident-resistant fuel core melting accident, characterized in that: include: Parameter initialization; Calculate the core temperature rise and oxidation after an accident based on the accident-resistant fuel oxidation model; Calculation of oxide layer thinning based on the accident-resistant fuel cladding volatilization model; Calculate fuel cladding damage and fuel collapse based on the accident-resistant fuel failure mechanism; Calculate the fission product release based on the accident-resistant fuel fission product release model; Based on the reaction products and migration process between the accident-resistant fuel cores and cladding and the coolant and reactor internals after the accident, the melt pool interaction and heat transfer analysis is carried out.

2. The method according to 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 Among them, N i are the input factors of the molar numbers of reactants and products, i = 1, 2, 3, …, 6, and Q1 is the heat of reaction of the material.

3. The method according to claim 1 or 2, characterized in that The kinetic equation of the cladding oxidation reaction in the accident-resistant fuel oxidation model is: Where dl / dt is the oxide layer growth rate in m / s; ρ1 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.

4. The method according to claim 1, characterized in that The volatilization reaction equation in the accident-resistant fuel cladding volatilization model is: M1 shell oxide + M2 H2O = product + M1Q2 Among them, M j is the input factor of the molar number of reactants and products, j = 1,2; Q2 is the volatilization reaction energy of the oxide.

5. The method according to claim 1 or 4, characterized in that The volatilization reaction kinetic equation in the accident-resistant fuel cladding volatilization model is: Where dh / dt is the evaporation rate of the oxide layer, in m / s; v is the steam velocity, in m / s; ρ2 is the density of the oxide layer, in kg / m 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.

6. The method according to claim 1, characterized in that The fission product release calculation based on the accident-resistant fuel fission product release model includes: Fission product release calculations are performed based on temperature-dependent diffusion coefficients and release rate equations.

7. The method according to claim 6, characterized in that The diffusion coefficient is of the form: Where A is the diffusion coefficient, A0 is the fission product group-specific diffusion factor, Q3 is the activation energy, R is the universal gas constant, and T3 is the cladding temperature.

8. The method according to claim 7, characterized in that The release rate equation is: Where E is the release rate, A T are the judgment parameters of the piecewise function, and a, A1, B1, C1, A2, B2 and C2 are coefficients.

9. A computing device, characterized in that include: at least one processor; as well as At least one memory having instructions stored thereon, which, when executed individually or collectively by the at least one processor, cause the computing device to perform the method according to any one of claims 1-8.

10. A computer storage medium, characterized in that: The computer storage medium stores instructions, which, when executed individually or collectively by at least one processor of a computing device, cause the computing device to perform the method according to any one of claims 1-8.

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