Method and system for calculating irradiation performance of braided nuclear fuel cladding tube

Abstract

The application discloses a kind of woven nuclear fuel cladding tube radiation performance calculation method and system.The method is first based on the geometric characteristics of woven structure, using Python script in Texgen software to establish the three-dimensional complex geometric model of woven tube, and it is imported into Abaqus software.Then, by Boolean operation, the single-element layer model of cladding tube is constructed, and the local coordinate system of yarn is defined as the material direction.Adhesion model is used to handle the interlayer action of woven layer and single-element layer.Further, the user subroutine of Abaqus software is written, the material behavior under thermal-mechanical-irradiation conditions is defined, including the variable of fast neutron fluence and irradiation dose changing with time, and the irradiation performance calculation of cladding tube under operating conditions is realized through Fortran subroutine.The system includes model establishment module and calculation and analysis module.The application adjusts the solution parameter to accelerate convergence and ensure calculation accuracy, thereby providing an efficient calculation tool for the radiation performance evaluation of woven nuclear fuel cladding tube.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of advanced accident-tolerant fuel of nuclear reactors, and particularly relates to a method and system for calculating irradiation performance of a braided nuclear fuel cladding tube. BACKGROUND

[0002] To enhance the safety performance of nuclear fuel, accident-tolerant nuclear fuel technology has become a research hotspot in the field of nuclear energy at home and abroad. As the first safety barrier of the nuclear reactor, the cladding is subjected to a series of extreme conditions such as high temperature and irradiation, and therefore a high-reliability cladding design plays a crucial role in the safety of the reactor. The braided layer of the composite material has high fracture toughness and low air tightness, which can improve the overall strength of the cladding tube, but may cause leakage of fission gas released during reactor operation. The monolithic layer generally has good air tightness and low fracture toughness, and therefore the two are generally combined in engineering to form a double-layer or triple-layer braided composite cladding tube, which not only has sufficient fracture toughness but also ensures sufficient air tightness.

[0003] In order to better understand the in-core service performance of the silicon carbide composite cladding tube and optimize the cladding design, it is necessary to develop a high-fidelity numerical simulation method for performance analysis. Due to the complex geometric characteristics of the braided structure, it is difficult to accurately model the thermal-mechanical-radiation behavior of the braided composite cladding tube. Moreover, traditional modeling has less research on the braiding process structure of the preform with complex cross-section, and it is difficult to meet the requirements of current industrial development, so it is a major research trend to increase the research on complex spatial geometric structures and complex preform with complex cross-section. SUMMARY

[0004] The purpose of the application is to conduct a detailed study on the spatial geometric characteristics of the braided tube, to realize the establishment method of the yarn braided tube model with an arbitrary shape cross-section, and to further construct a double-layer composite cladding tube calculation model, while considering the influence of the material properties under the temperature and irradiation during the operation of the reactor, and to provide a method and system for calculating the irradiation performance of the braided nuclear fuel cladding tube.

[0005] To achieve the above purpose, the application adopts the following technical solutions:

[0006] A method for calculating the irradiation performance of a braided nuclear fuel cladding tube, comprising the following steps:

[0007] S1, establishing a general geometric model of the braided nuclear fuel cladding tube;

[0008] S2, assigning material behavior to the established general geometric model of the cladding tube to obtain a preliminary calculation model of the irradiation performance of the cladding tube;

[0009] S3. Based on the preliminary calculation model of cladding tube radiation performance, the calculation conditions are adjusted to increase the convergence of the calculation of the radiation performance of braided nuclear fuel cladding tubes, and the calculation model of the cladding tube radiation performance is obtained;

[0010] S4. Based on the cladding tube radiation performance calculation model, the irradiation performance of the braided nuclear fuel cladding tube is calculated and analyzed.

[0011] A further improvement of the present invention is that, in step S1, establishing the overall geometric model of the braided nuclear fuel cladding tube includes:

[0012] S11. Define spatial fluctuation function r ( θ ), write Python program;

[0013] S12, the geometric parameters of the braided tube, including the radius of the braided tube r 0. Weaving Angle α , yarn quantity n , yarn cross-sectional shape, and weaving pattern are written into Python program;

[0014] S13. Define the clockwise and counterclockwise yarn construction functions respectively f n ( r 0, α , n ), f p ( r 0, α , n ) and yarn cross-section control function V up , V tan Write a Python program;

[0015] S14. Define the angle independent variable θ The domain and number of interpolation points are written into the Python program;

[0016] S15. Run the Python program written in S11-S14 in TexGen software to interpolate the path to obtain continuous clockwise and counterclockwise yarns to form a braided tube geometric model;

[0017] S16, establishing a calculation domain for the established braided tube geometric model, and intercepting a portion used for calculation;

[0018] S17, outputting the divided calculation part as an stp file for subsequent calculation;

[0019] S18. Import the braided tube geometry model stp file into ABAQUS and create a geometric ring tube with the same size as the cladding tube;

[0020] S19, performing Boolean operations on the established geometric ring tube and the braided tube to obtain a geometric model of the single-material layer;

[0021] S110, assembling the braided tube and the single-material layer to obtain a spatial geometric model of the overall cladding tube;

[0022] S111. Add a zero-thickness cohesive layer model on the common surface of the braided tube and the single-substance layer to obtain an overall geometric model of the braided nuclear fuel cladding tube used for calculation. The overall geometric model of the cladding tube includes a braided layer, a cohesive connecting layer, and a single-substance layer arranged in sequence from the inside to the outside.

[0023] A further improvement of the present invention is that, in step S2, the established overall geometric model of the cladding tube is assigned material behavior to obtain a preliminary calculation model of the cladding tube radiation performance, including:

[0024] S21, selecting a braided yarn for braiding a nuclear fuel cladding tube and discretizing its material direction;

[0025] S22. Select the path curve of the yarn and take the tangent of the curve to obtain the vector e 1;

[0026] S23, select the inner and outer surfaces of the selected yarn, and take their surface normals to obtain e 2, e 3;

[0027] S24, will e 1, e 2, e 3 as the local coordinate system basis vectors at each interpolation point and as the main direction of the subsequent material direction;

[0028] S25. The single-layer in the overall geometric model of the cladding tube is established, and the temperature-related property functions of the single-layer material are added in the UMAT and UMATHT subroutines of the ABAQUS software, including the elastic modulus. E m , Poisson's ratio μ m , thermal conductivity k m , specific heat capacity C pm , irradiation swelling behavior S m , damaging behavior D ;

[0029] S26. Based on the braided layer in the established overall geometric model of the cladding tube, add temperature-dependent property functions of the yarn material, including the elastic modulus, to the UMAT and UMATHT subroutines in the ABAQUS software. E y11 、E y22 、 E y33 、 G y12 、 G y13 、 G y23 , Poisson's ratio μ y12 、 μ y13 、 μ y13 , thermal conductivity k y , specific heat capacity C py , irradiation swelling behavior S y ;

[0030] S27, rewrite the stiffness matrix and heat conduction equation of each material in the corresponding material subroutine according to the defined material property function, and obtain a preliminary calculation model of the irradiation performance of the cladding tube.

[0031] The further improvement of the present application is that, in step S3, based on the preliminary calculation model of the irradiation performance of the cladding tube, the calculation conditions are adjusted to increase the convergence of the irradiation performance calculation of the braided nuclear fuel cladding tube, and a cladding tube irradiation performance calculation model is obtained, comprising:

[0032] S31, respectively, the single element layer, the braided layer and the viscous connection layer are meshed, and the viscous coefficient is added in the ABAQUS material attribute or element attribute;

[0033] S32, reduce the minimum increment step and increase the number of discontinuous iteration trials in ABAQUS;

[0034] S33, change the element type of the viscous connection layer to temperature-displacement coupled viscous element, and obtain a cladding tube irradiation performance calculation model.

[0035] The further improvement of the present application is that, in step S4, based on the cladding tube irradiation performance calculation model, the irradiation performance calculation and analysis of the braided nuclear fuel cladding tube are carried out, comprising:

[0036] S41, based on the cladding tube irradiation performance calculation model, define the equivalent thermal-mechanical load at the inner and outer walls of the braided nuclear fuel cladding tube and the end plug;

[0037] S42, calculate the fast neutron fluence matched with the power according to the thermal load of the inner wall surface Φ ;

[0038] S43, the calculated fast neutron fluence ΦWrite the UMAT and UMATHT subroutines in ABAQUS software to define the radiation dose variables that change with time;

[0039] S44. Rewrite the material properties in the UMAT and UMATHT subroutines into radiation dose related functions;

[0040] S45. Setting boundary conditions of the cladding tube in various directions;

[0041] S46. Import the compiled UMAT and UMATHT subroutines into the ABAQUS software inp file, submit the calculation, and then perform the irradiation performance calculation and analysis of the braided nuclear fuel cladding tube.

[0042] A system for calculating the radiation performance of a braided nuclear fuel cladding tube, comprising:

[0043] The geometric model building module is used to build the overall geometric model of the braided nuclear fuel cladding tube;

[0044] The preliminary calculation model establishment module assigns material behavior to the established overall geometric model of the cladding tube to obtain a preliminary calculation model of the cladding tube's irradiation performance;

[0045] The calculation model establishment module, based on the preliminary calculation model of the cladding tube radiation performance, adjusts the calculation conditions to increase the convergence of the cladding tube radiation performance calculation, and obtains the cladding tube radiation performance calculation model;

[0046] The calculation and analysis module performs irradiation performance calculation and analysis on braided nuclear fuel cladding tubes based on the cladding tube irradiation performance calculation model.

[0047] A further improvement of the present invention is that, in the geometric model establishment module, establishing the overall geometric model of the braided nuclear fuel cladding tube includes:

[0048] Define spatial fluctuation function r ( θ ), write Python program;

[0049] The geometric parameters of the braided tube, including the radius of the braided tube r 0. Weaving Angle α , yarn quantity n , yarn cross-sectional shape, and weaving pattern are written into Python program;

[0050] Define the clockwise and counterclockwise yarn construction functions respectively f n ( r 0, α , n ), f p ( r 0, α ,n ) and yarn cross-section control function V up , V tan Write a Python program;

[0051] Defining the angle argument θ The domain and number of interpolation points are written into the Python program;

[0052] Run the Python program written in S11-S14 in TexGen software to interpolate the path to obtain continuous clockwise and counterclockwise yarns to form a braided tube geometric model;

[0053] Establish a calculation domain for the braided tube geometric model and intercept the part used for calculation;

[0054] Output the divided calculation part as stp file for subsequent calculation;

[0055] Import the braided tube geometry model stp file into ABAQUS and create a geometric ring tube with the same size as the cladding tube;

[0056] Perform Boolean operations on the established geometric ring tube and braided tube to obtain the geometric model of the single-layer;

[0057] Then the braided tube and the single-material layer are assembled and combined to obtain the overall cladding tube spatial geometric model;

[0058] A zero-thickness cohesive layer model is added on the shared surface of the braided tube and the single-substance layer to obtain the overall geometric model of the braided nuclear fuel cladding tube used for calculation. The overall geometric model of the cladding tube includes the braided layer, the cohesive connecting layer and the single-substance layer arranged in sequence from the inside to the outside.

[0059] A further improvement of the present invention is that, in the preliminary calculation model establishment module, the established overall geometric model of the cladding tube is given material behavior to obtain a preliminary calculation model of the cladding tube radiation performance, including:

[0060] Selecting the braiding yarns of the braided nuclear fuel cladding tube and discretizing their material directions;

[0061] Select the path curve of the yarn and take the tangent of the curve to get the vector e 1;

[0062] Select the inner and outer surfaces of the selected yarn and take their surface normals to obtain e 2, e 3;

[0063] Will e 1, e 2, e3 as the local coordinate system basis vectors at each interpolation point and as the main direction of the subsequent material direction;

[0064] The single-layer in the overall geometric model of the cladding tube is established, and the temperature-related property functions of the single-layer material are added in the UMAT and UMATHT subroutines of the ABAQUS software, including the elastic modulus E m , Poisson's ratio μ m , thermal conductivity k m , specific heat capacity C pm , irradiation swelling behavior S m , damaging behavior D ;

[0065] Based on the braided layer in the overall geometric model of the cladding tube, the temperature-dependent property functions of the yarn material, including the elastic modulus, are added to the UMAT and UMATHT subroutines of the ABAQUS software. E y11 、 E y22 、 E y33 、 G y12 、 G y13 、 G y23 , Poisson's ratio μ y12 、 μ y13 、 μ y13 , thermal conductivity k y , specific heat capacity C py , irradiation swelling behavior S y ;

[0066] According to the defined material property functions, the stiffness matrix and heat conduction equation of each material are rewritten in the subroutines of the corresponding materials to obtain a preliminary calculation model for the cladding tube radiation performance.

[0067] A further improvement of the present invention is that, in the calculation model establishment module, based on the preliminary calculation model of the cladding tube radiation performance, the calculation conditions are adjusted to increase the convergence of the calculation of the radiation performance of the braided nuclear fuel cladding tube, and the cladding tube radiation performance calculation model is obtained, including:

[0068] Mesh the single-material layer, braided layer, and viscous connection layer separately, and add the viscosity coefficient in the ABAQUS material properties or element properties;

[0069] Decreasing the minimum incremental step and increasing the number of discontinuous iteration trials in ABAQUS;

[0070] Change the unit type of the viscous connection layer to a temperature-displacement coupled viscous unit to obtain a cladding tube irradiation performance calculation model.

[0071] A computer readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the irradiation performance calculation method of the braided nuclear fuel cladding tube.

[0072] Compared with the prior art, the present application has at least the following beneficial technical effects:

[0073] The present application provides an irradiation performance calculation method and system for braided nuclear fuel cladding tubes. First, based on the geometric characteristics of the braided structure, a Python script is used to establish a three-dimensional complex geometric model of the braided tube in the Texgen software, and it is imported into the Abaqus software for analysis. Then, a single-element layer model of the cladding tube is constructed through Boolean operation, and the local coordinate system of the yarn is defined as the material direction. The cohesive model is used to handle the interlayer action between the braided layer and the single-element layer. Further, a user subroutine of the Abaqus software is written to define the material behavior under thermal-mechanical-irradiation conditions, including the variables of fast neutron fluence and irradiation dose changing with time, and the irradiation performance calculation of the cladding tube under operating conditions is realized through the Fortran subroutine. This method adjusts the solving parameters to accelerate the convergence and ensure the calculation accuracy, thereby providing an efficient calculation tool for the irradiation performance evaluation of braided nuclear fuel cladding tubes. BRIEF DESCRIPTION OF DRAWINGS

[0074] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0075] Figure 1 The flowchart of the irradiation performance calculation method of the braided nuclear fuel cladding tube of the present application;

[0076] Figure 2 Figures (a) and (b) are schematic diagrams of a braided tube structure;

[0077] Figure 3 Figures (a) and (b) are schematic diagrams of a braided tube structure;

[0078] Figure 4(a) and (b) are schematic diagrams of the overall calculation model of the nuclear fuel cladding tube;

[0079] Figure 5 Schematic diagram of the local coordinate system at the yarn interpolation point in the embodiment;

[0080] Figure 6 (a) to (c) are stress and temperature cloud diagrams calculated in the embodiment;

[0081] Figure 7 This is a structural block diagram of a system for calculating the radiation performance of a braided nuclear fuel cladding tube according to the present invention. DETAILED DESCRIPTION

[0082] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0083] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0084] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0085] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0086] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0087] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0088] Most of the current literature simplifies the braided layer of silicon carbide cladding tubes into a uniform medium for analysis, and lacks numerical analysis research on cladding tubes with detailed braided structure.

[0089] Currently, when establishing braided structure models, the cross-section of the braided yarn is mostly selected as a circular cross-section, and there is a lack of research on braided tubes with yarns of special cross-sections.

[0090] Example 1

[0091] like Figure 1 As shown, the present invention provides a method for calculating the irradiation performance of a braided nuclear fuel cladding tube, comprising the following steps:

[0092] S1. Establish the overall geometric model of the braided nuclear fuel cladding tube;

[0093] S2. Assign material behavior to the established overall geometric model of the cladding tube to obtain a preliminary calculation model for the irradiation performance of the cladding tube;

[0094] S3. Based on the preliminary calculation model of cladding tube radiation performance, the calculation conditions are adjusted to increase the convergence of the calculation of the radiation performance of braided nuclear fuel cladding tubes, and the calculation model of the cladding tube radiation performance is obtained;

[0095] S4. Based on the cladding tube radiation performance calculation model, the irradiation performance of the braided nuclear fuel cladding tube is calculated and analyzed.

[0096] In this embodiment, in step S1, establishing the overall geometric model of the braided nuclear fuel cladding tube includes:

[0097] S11. Define spatial fluctuation function r ( θ ), write Python program;

[0098] S12, the geometric parameters of the braided tube, including the radius of the braided tube r 0. Weaving Angle α , yarn quantity n , yarn cross-sectional shape, and weaving pattern are written into Python program;

[0099] S13. Define the clockwise and counterclockwise yarn construction functions respectively f n ( r 0, α , n ), f p ( r 0, α , n ) and yarn cross-section control function V up , V tanWrite the Python program;

[0100] S14, define the corner independent variable θ The domain of definition and the number of interpolation points are written into the Python program;

[0101] S15, run the Python program written in S11-S14 in TexGen software to interpolate the path to obtain continuous clockwise and counterclockwise yarns, which constitute the braided tube geometric model;

[0102] S16, establish a calculation domain for the established braided tube geometric model, and cut off the part used for calculation;

[0103] S17, output the divided calculation part as a stp file for subsequent calculation;

[0104] S18, import the braided tube geometric model stp file into ABAQUS and establish a geometric ring tube with the same size as the cladding tube;

[0105] S19, perform Boolean operation on the established geometric ring tube and braided tube to obtain a single-element layer geometric model;

[0106] S110, assemble the braided tube and the single-element layer to obtain the overall cladding tube spatial geometric model;

[0107] S111, add a zero-thickness cohesive layer model on the common surface of the braided tube and the single-element layer to obtain the overall braided nuclear fuel cladding tube geometric model for calculation, which includes the braided layer, the cohesive connection layer and the single-element layer arranged from inside to outside.

[0108] In this embodiment, in step S2, the overall braided nuclear fuel cladding tube geometric model is given a material behavior to obtain a preliminary calculation model of the braided nuclear fuel cladding tube, which includes:

[0109] S21, select the braided yarn of the braided nuclear fuel cladding tube and disperse its material direction;

[0110] S22, select the path curve of the yarn, and take the curve tangent to obtain the vector e 1;

[0111] S23, select the inner and outer surfaces of the selected yarn, and take the surface normal to obtain e 2, e 3;

[0112] S24, take e 1, e 2, e 3 as the local coordinate system basis vector at each interpolation point, and as the main direction of the subsequent material direction;

[0113] S25. The single-layer in the overall geometric model of the cladding tube is established, and the temperature-related property functions of the single-layer material are added in the UMAT and UMATHT subroutines of the ABAQUS software, including the elastic modulus. E m , Poisson's ratio μ m , thermal conductivity k m , specific heat capacity C pm , irradiation swelling behavior S m , damaging behavior D ;

[0114] S26. Based on the braided layer in the established overall geometric model of the cladding tube, add temperature-dependent property functions of the yarn material, including the elastic modulus, to the UMAT and UMATHT subroutines in the ABAQUS software. E y11 、 E y22 、 E y33 、 G y12 、 G y13 、 G y23 , Poisson's ratio μ y12 、 μ y13 、 μ y13 , thermal conductivity k y , specific heat capacity C py , irradiation swelling behavior S y ;

[0115] S27. According to the defined material property function, rewrite the stiffness matrix and heat conduction equation of each material in the subroutine of the corresponding material to obtain a preliminary calculation model for the cladding tube radiation performance.

[0116] In this embodiment, in step S3, based on the preliminary calculation model of the radiation performance of the cladding tube, the calculation conditions are adjusted to increase the convergence of the calculation of the radiation performance of the braided nuclear fuel cladding tube, and the calculation model of the radiation performance of the cladding tube is obtained, including:

[0117] S31. Mesh the single-layer, braided layer, and viscous connection layer separately, and add the viscosity coefficient in the ABAQUS material properties or element properties;

[0118] S32. Reduce the minimum incremental step and increase the number of discontinuous iterations in ABAQUS;

[0119] S33, change the unit type of the viscous connection layer to a temperature-displacement coupled viscous unit to obtain a cladding tube irradiation performance calculation model.

[0120] In the embodiment, in step S4, based on the cladding tube irradiation performance calculation model, irradiation performance calculation analysis is performed on the braided nuclear fuel cladding tube, including:

[0121] S41, based on the cladding tube irradiation performance calculation model, defining the equivalent thermal-mechanical load at the inner and outer walls of the braided nuclear fuel cladding tube and the end plug;

[0122] S42, calculating the fast neutron fluence matched with the power according to the thermal load of the inner wall surface Φ ;

[0123] S43, writing the calculated fast neutron fluence Φ into the UMAT and UMATHT subprograms of ABAQUS software to define the time-varying irradiation dose variable;

[0124] S44, rewriting the material properties in the UMAT and UMATHT subprograms as irradiation dose related functions;

[0125] S45, setting the boundary conditions of the cladding tube in each direction;

[0126] S46, importing the completed UMAT and UMATHT subprograms into the inp file of ABAQUS software, submitting calculation and performing irradiation performance calculation analysis of the braided nuclear fuel cladding tube.

[0127] Embodiment 2

[0128] The present application provides a kind of braided nuclear fuel cladding tube irradiation performance calculation method, including the following steps:

[0129] S1, establish braided nuclear fuel cladding tube space geometric model;

[0130] The above step S1 includes the following sub-steps:

[0131] It should be noted that the braided tube structure of the circular cross-section yarn does not need to consider the torsion of the yarn, and the cross-section posture of the yarn at each interpolation point has no effect on the model establishment result, while the cross-section posture of the shaped cross-section yarn at each interpolation point needs to be considered, and the braided tube structure of the shaped cross-section yarn is modeled in the embodiment.

[0132] S11, define space fluctuation function r ( θ );

[0133] The function of the spatial fluctuation function is to construct a space in space to accommodate yarns in opposite directions. In this embodiment, a sine function is selected as the spatial fluctuation function:

[0134] (1)

[0135] S12, the geometric parameters of the braided tube, including the braided tube radius r 0, braiding angle α , the number of yarns n , yarn cross-sectional shape, braiding mode are written into the Python program;

[0136] The selected r 0 in this embodiment is 5mm, α is 45°, n is 12, the cross-sectional shape is elliptical, and the braiding mode is diamond braiding.

[0137] S13, define clockwise and counterclockwise yarn construction functions respectively f n ( r 0, α , n ), f p ( r 0, α , n ) and yarn cross-sectional control function V up , V tan are written into the Python program;

[0138] It should be noted that the two spatial vectors defined in S13 are to limit the attitude of the anisotropic cross-section yarn in space. The components of the two spatial vectors can be obtained by differential calculation of the spatial path fitting curve L ( r 0, α , n , r ( θ )) of the yarn. Taking a counterclockwise braided yarn in this embodiment as an example:

[0139] (2)

[0140] (3)

[0141] S14, define the rotation angle independent variable θ The domain of definition and the number of interpolation points are written into the Python program;

[0142] S15. Run the Python program in TexGen software to interpolate the path to obtain continuous clockwise and counterclockwise yarns to form a braided tube geometric model;

[0143] The geometric model of the three-dimensional braided tube established in this embodiment is shown in FIG2. The braiding model in S12 can also be selected as conventional braiding, such as Figure 3 shown.

[0144] S16, establishing a calculation domain for the established braided tube geometric model, and intercepting a portion used for calculation;

[0145] S17, outputting the divided calculation part as an stp file for subsequent calculation;

[0146] S18. Import the braided tube geometry model stp file into ABAQUS and create a geometric ring tube with the same size as the cladding tube;

[0147] S19, performing Boolean operations on the established geometric ring tube and the braided tube to obtain a geometric model of the single-material layer;

[0148] S110, assembling the braided tube and the single-material layer to obtain a spatial geometric model of the overall cladding tube;

[0149] S111. Adding a zero-thickness cohesive layer model on the common surface of the braided tube and the single-material layer to obtain an overall geometric model of the cladding tube for calculation;

[0150] The overall geometric model of the cladding tube obtained in S111 is shown in Figure 4, which consists of a braided tube structure and a single layer.

[0151] S2. Assigning a material behavior model to the established cladding tube space geometry model;

[0152] The above step S2 includes the following sub-steps:

[0153] S21, selecting a braided yarn for braiding a nuclear fuel cladding tube and discretizing its material direction;

[0154] S22. Select the path curve of the yarn and take the tangent of the curve to obtain the vector e 1;

[0155] S23, select the inner and outer surfaces of the selected yarn, and take their surface normals to obtain e 2, e 3;

[0156] S24, will e 1, e 2, e 3 as the local coordinate system basis vectors at each interpolation point and as the main direction of the subsequent material direction;

[0157] The local coordinate system at the yarn interpolation point in the above step S24 is shown in FIG5 .

[0158] S25. Add temperature-dependent property functions of single-layer materials, including elastic modulus, to the UMAT and UMATHT subroutines of the ABAQUS software. E m , Poisson's ratio μ m , thermal conductivity k m , specific heat capacity C pm , irradiation swelling behavior S m , damaging behavior D .

[0159] In this embodiment, the single-layer material is considered to be an isotropic brittle material, and all the physical properties described in the above step S25 are functions of temperature.

[0160] S26. Add temperature-dependent property functions of yarn materials, including elastic modulus, to the UMAT and UMATHT subroutines in ABAQUS software. E y11 、 E y22 、 E y33 、 G y12 、 G y13 、 G y23 , Poisson's ratio μ y12 、 μ y13 、 μ y13 , thermal conductivity k y , specific heat capacity C py , irradiation swelling behavior S y .

[0161] In this embodiment, the single-layer material is considered to be an anisotropic material, and all the physical properties described in the above step S26 are functions of temperature.

[0162] S27. Rewrite the stiffness matrix and heat conduction equation of each material in the subroutine according to the defined material property function.

[0163] The mechanical behavior of the material in the above step S27 is defined in the UMAT subroutine of the ABAQUS software, and the thermal behavior is defined in the UMATHT subroutine of the ABAQUS software.

[0164] S3. Adjust the calculation conditions to improve the convergence of the irradiation performance calculation of braided nuclear fuel cladding tubes;

[0165] The above step S3 includes the following sub-steps:

[0166] S31. Add viscosity coefficient to material properties or element properties;

[0167] It should be noted that the viscosity coefficient added in step S31 is to accelerate the convergence of viscosity behavior in the finite element calculation process and has no physical meaning. Its value is generally 10 -5 ~10 -4 .

[0168] S32, reduce the minimum incremental step and increase the number of discontinuous iterative trials;

[0169] It should be noted that the above step S32 is intended to reduce instability during the iteration process and lower the risk of non-convergence of the calculation.

[0170] S33, changing the unit type of the zero-thickness cohesive layer model established in step S111 to a temperature-displacement coupled viscous unit;

[0171] In this embodiment, the failure criterion of the viscous unit in the above step S33 is:

[0172] (4)

[0173] σ0 n ,、 τ0 s and τ0 s is the stress in three directions.

[0174] S4. Calculating and analyzing the irradiation performance of the braided nuclear fuel cladding tube based on the method described;

[0175] The above step S4 includes the following sub-steps:

[0176] S41. Define the equivalent thermal-mechanical loads on the inner and outer walls of the braided nuclear fuel cladding tube and the end plug;

[0177] S42. Calculate the fast neutron flux that matches the power based on the heat load on the inner wall. Φ ;

[0178] S43, the fast neutron fluence calculated in step S43 Φ Write the UMAT and UMATHT subroutines in ABAQUS software to define the radiation dose variables that change with time;

[0179] S44, adding the material properties in step S25 and step S26 as a radiation dose related function;

[0180] In this embodiment, after step S44 is implemented, all physical properties described in steps S25 and S26 are functions of temperature and irradiation dose.

[0181] S45. Setting boundary conditions of the cladding tube in various directions;

[0182] S46. Import the compiled UMAT and UMATHT subroutines into the ABAQUS software inp file, submit the calculation, and then perform the irradiation performance calculation and analysis of the braided nuclear fuel cladding tube.

[0183] In this embodiment, after executing the above step S46, a result cloud diagram of the embodiment can be obtained. The stress and temperature cloud diagram calculated in this embodiment is as follows: Figure 6 shown.

[0184] Example 3

[0185] like Figure 7 As shown, the present invention provides a system for calculating the radiation performance of a braided nuclear fuel cladding tube, comprising:

[0186] The geometric model building module is used to build the overall geometric model of the braided nuclear fuel cladding tube;

[0187] The preliminary calculation model establishment module assigns material behavior to the established overall geometric model of the cladding tube to obtain a preliminary calculation model of the cladding tube's irradiation performance;

[0188] The calculation model establishment module, based on the preliminary calculation model of the cladding tube radiation performance, adjusts the calculation conditions to increase the convergence of the cladding tube radiation performance calculation, and obtains the cladding tube radiation performance calculation model;

[0189] The calculation and analysis module performs irradiation performance calculation and analysis on braided nuclear fuel cladding tubes based on the cladding tube irradiation performance calculation model.

[0190] Example 4

[0191] The present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the steps of the method for calculating the radiation performance of a braided nuclear fuel cladding tube.

[0192] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0193] The present application is described with reference to the flowcharts and / or block diagrams of the methods, systems, and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A system that specifies the functions of a box or boxes.

[0194] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0195] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0196] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0197] Furthermore, it should be understood that although the specification is described in terms of embodiments, each of which contains only one independent technical solution, the specification is described in this way only for the sake of clarity, and the skilled person should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that the skilled person can understand. The above is only to illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made on the basis of the technical solutions according to the technical idea of the present application falls within the protection scope of the claims of the present application.

Claims

1. A method for calculating the irradiation performance of a braided nuclear fuel cladding tube, characterized in that: The following steps are involved: S1. Establishing an overall geometric model of a braided nuclear fuel cladding tube, the overall geometric model of the braided nuclear fuel cladding tube includes a braided layer, a viscous connecting layer, and a single-substance layer arranged in sequence from the inside to the outside, and adding a zero-thickness cohesive layer model on the common surface of the braided tube and the single-substance layer; S2. Assign material behavior to the established overall geometric model of the cladding tube to obtain a preliminary calculation model for the cladding tube's irradiation performance, including: S21, selecting a braided yarn for braiding a nuclear fuel cladding tube and discretizing its material direction; S22. Select the path curve of the yarn and take the tangent of the curve to obtain the vector e 1; S23, select the inner and outer surfaces of the selected yarn, and take their surface normals to obtain e 2, e 3; S24, will e 1, e 2, e 3 as the local coordinate system basis vectors at each interpolation point and as the main direction of the subsequent material direction; S25. The single-layer in the overall geometric model of the cladding tube is established, and the temperature-related property functions of the single-layer material are added in the UMAT and UMATHT subroutines of the ABAQUS software, including the elastic modulus. E m , Poisson's ratio μ m , thermal conductivity k m , specific heat capacity C pm , irradiation swelling behavior S m , damaging behavior D ; S26. Based on the braided layer in the established overall geometric model of the cladding tube, add temperature-dependent property functions of the yarn material, including the elastic modulus, to the UMAT and UMATHT subroutines in the ABAQUS software. E y11 、 E y22 、 E y33 、 G y12 、 G y13 、 G y23 , Poisson's ratio μ y12 、 μ y13 、 μ y13 , thermal conductivity k y , specific heat capacity C py , irradiation swelling behavior S y ; S27. Rewrite the stiffness matrix and heat conduction equation of each material in the subroutine of the corresponding material according to the defined material property function to obtain a preliminary calculation model for the cladding tube radiation performance; S3. Based on the preliminary calculation model of cladding tube radiation performance, the calculation conditions are adjusted to increase the convergence of the calculation of the radiation performance of braided nuclear fuel cladding tubes. The calculation model of cladding tube radiation performance is obtained, including: S31. Mesh the single-layer, braided layer, and viscous connection layer separately, and add the viscosity coefficient in the ABAQUS material properties or element properties; S32. Reduce the minimum incremental step and increase the number of discontinuous iterations in ABAQUS; S33, changing the unit type of the viscous connection layer to a temperature-displacement coupled viscous unit, and obtaining a calculation model for the radiation performance of the cladding tube; S4. Based on the cladding tube radiation performance calculation model, the irradiation performance of the braided nuclear fuel cladding tube is calculated and analyzed.

2. The method for calculating the radiation performance of a braided nuclear fuel cladding tube according to claim 1, characterized in that: In step S1, establishing the overall geometric model of the braided nuclear fuel cladding tube includes: S11. Define spatial fluctuation function r ( θ ), write Python program; S12, the geometric parameters of the braided tube, including the radius of the braided tube r 0. Weaving Angle α , yarn quantity n , yarn cross-sectional shape, and weaving pattern are written into Python program; S13. Define the clockwise and counterclockwise yarn construction functions respectively f n ( r 0, α , n ), f p ( r 0, α , n ) and yarn cross-section control function V up , V tan Write a Python program; S14. Define the angle independent variable θ The domain and number of interpolation points are written into the Python program; S15. Run the Python program written in S11-S14 in TexGen software to interpolate the path to obtain continuous clockwise and counterclockwise yarns to form a braided tube geometric model; S16, establishing a calculation domain for the established braided tube geometric model, and intercepting a portion used for calculation; S17, outputting the divided calculation part as an stp file for subsequent calculation; S18. Import the braided tube geometry model stp file into ABAQUS and create a geometric ring tube with the same size as the cladding tube; S19, performing Boolean operations on the established geometric ring tube and the braided tube to obtain a geometric model of the single-layer; S110, assembling the braided tube and the single-material layer to obtain a spatial geometric model of the overall cladding tube; S111. Add a zero-thickness cohesive layer model on the common surface of the braided tube and the single-substance layer to obtain the overall geometric model of the braided nuclear fuel cladding tube used for calculation.

3. The method for calculating the radiation performance of a braided nuclear fuel cladding tube according to claim 2, characterized in that: In step S4, based on the cladding tube radiation performance calculation model, the irradiation performance calculation analysis of the braided nuclear fuel cladding tube is performed, including: S41. Based on the cladding tube irradiation performance calculation model, define the equivalent thermal-mechanical loads on the inner and outer walls of the braided nuclear fuel cladding tube and the end plug; S42. Calculate the fast neutron flux that matches the power based on the heat load on the inner wall. Φ ; S43, calculate the fast neutron flux Φ Write the UMAT and UMATHT subroutines in ABAQUS software to define the radiation dose variables that change with time; S44. Rewrite the material properties in the UMAT and UMATHT subroutines into radiation dose-related functions; S45. Setting boundary conditions of the cladding tube in all directions; S46. Import the compiled UMAT and UMATHT subroutines into the ABAQUS software inp file, submit the calculation, and then perform the irradiation performance calculation and analysis of the braided nuclear fuel cladding tube.

4. A system for calculating the radiation performance of a braided nuclear fuel cladding tube, characterized in that: include: A geometric model building module is used to build an overall geometric model of the braided nuclear fuel cladding tube. The overall geometric model of the braided nuclear fuel cladding tube includes a braided layer, a viscous connection layer, and a single-substance layer arranged in sequence from the inside to the outside, and a zero-thickness cohesive layer model is added to the common surface of the braided tube and the single-substance layer; The preliminary calculation model establishment module assigns material behavior to the established overall geometric model of the cladding tube to obtain a preliminary calculation model of the cladding tube's irradiation performance, including: Selecting the braiding yarns of the braided nuclear fuel cladding tube and discretizing their material directions; Select the path curve of the yarn and take the tangent of the curve to get the vector e 1; Select the inner and outer surfaces of the selected yarn and take their surface normals to obtain e 2, e 3; Will e 1, e 2, e 3 as the local coordinate system basis vectors at each interpolation point and as the main direction of the subsequent material direction; The single-layer in the overall geometric model of the cladding tube is established, and the temperature-related property functions of the single-layer material are added in the UMAT and UMATHT subroutines of the ABAQUS software, including the elastic modulus E m , Poisson's ratio μ m , thermal conductivity k m , specific heat capacity C pm , irradiation swelling behavior S m , damaging behavior D ; Based on the braided layer in the overall geometric model of the cladding tube, the temperature-dependent property functions of the yarn material, including the elastic modulus, are added to the UMAT and UMATHT subroutines of the ABAQUS software. E y11 、 E y22 、 E y33 、 G y12 、 G y13 、 G y23 , Poisson's ratio μ y12 、 μ y13 、 μ y13 , thermal conductivity k y , specific heat capacity C py , irradiation swelling behavior S y ; According to the defined material property function, the stiffness matrix and heat conduction equation of each material are rewritten in the subroutine of the corresponding material to obtain the preliminary calculation model of the cladding tube radiation performance; The calculation model establishment module, based on the preliminary calculation model of cladding tube radiation performance, adjusts the calculation conditions to increase the convergence of the cladding tube radiation performance calculation, and obtains the cladding tube radiation performance calculation model, including: Mesh the single-material layer, braided layer, and viscous connection layer separately, and add the viscosity coefficient in the ABAQUS material properties or element properties; Reduce the minimum incremental step and increase the number of discontinuous iterations in ABAQUS; The unit type of the viscous connection layer is changed to a temperature-displacement coupled viscous unit, and the cladding tube radiation performance calculation model is obtained; The calculation and analysis module performs irradiation performance calculation and analysis on braided nuclear fuel cladding tubes based on the cladding tube irradiation performance calculation model.

5. The radiation performance calculation system for braided nuclear fuel cladding tubes according to claim 4, characterized in that: In the geometric model building module, the overall geometric model of the braided nuclear fuel cladding tube is established, including: Define spatial fluctuation function r ( θ ), write Python program; The geometric parameters of the braided tube, including the radius of the braided tube r 0. Weaving Angle α , yarn quantity n , yarn cross-sectional shape, and weaving pattern are written into Python program; Define the clockwise and counterclockwise yarn construction functions respectively f n ( r 0, α , n ), f p ( r 0, α , n ) and yarn cross-section control function V up , V tan Write a Python program; Defining the angle argument θ The domain and number of interpolation points are written into the Python program; Run the Python program written in S11-S14 in TexGen software to interpolate the path to obtain continuous clockwise and counterclockwise yarns to form a braided tube geometric model; Establish a calculation domain for the braided tube geometric model and intercept the part used for calculation; Output the divided calculation part as stp file for subsequent calculation; Import the braided tube geometry model stp file into ABAQUS and create a geometric ring tube with the same size as the cladding tube; Perform Boolean operations on the established geometric ring tube and braided tube to obtain the geometric model of the single-layer; Then the braided tube and the single-material layer are assembled and combined to obtain the overall cladding tube spatial geometric model; A zero-thickness cohesive layer model is added on the shared surface of the braided tube and the single-substance layer to obtain the overall geometric model of the braided nuclear fuel cladding tube used for calculation.

6. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the method for calculating the irradiation performance of a braided nuclear fuel cladding tube according to any one of claims 1 to 3.

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