Irradiation performance calculation method and system for braided nuclear fuel cladding tube

Abstract

The invention discloses a method and a system for calculating irradiation performance of a braided nuclear fuel cladding tube. The method comprises the following steps: firstly, based on geometric characteristics of a braided structure, establishing a three-dimensional complex geometric model of a braided tube in Texgen software by using a Python script, and importing the three-dimensional complex geometric model into Abaqus software; secondly, constructing an elementary substance layer model of the cladding tube through Boolean operation, and defining a local coordinate system of yarns as a material direction; and processing the interlayer action between the braid layer and the elementary substance layer by adopting a cohesive model. Furthermore, a user subprogram of Abaqus software is compiled, material behaviors under the heat-force-irradiation condition are defined, including variables of fast neutron fluence and irradiation dose changing along with time, and irradiation performance calculation of the cladding tube under the operation condition is achieved through a Fortran subprogram. The system comprises a model building module and a calculation and analysis module. According to the method, the convergence is accelerated and the calculation precision is ensured by adjusting the solving parameters, so that an efficient calculation tool is provided for evaluating the irradiation performance of the braided nuclear fuel cladding tube.

Description

Technical Field

[0001] The invention belongs to the technical field of advanced accident-resistant fuel for nuclear reactors, and in particular relates to a method and a system for calculating the radiation performance of a braided nuclear fuel cladding tube. Background Art

[0002] In order to enhance the safety performance of nuclear fuel, accident-resistant nuclear fuel technology has become a research hotspot in the field of nuclear energy at home and abroad. As the first safety barrier of nuclear reactors, the cladding faces a series of extreme conditions such as high temperature and irradiation. Therefore, high-reliability cladding design plays a vital role in reactor safety. The composite material braided layer 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 the reaction operation. The single-layer generally has good air tightness and low fracture toughness. Therefore, the two are generally used in combination in engineering to form a double-layer or three-layer braided composite material cladding tube, which not only makes the cladding tube have sufficient fracture toughness, but also ensures sufficient air tightness.

[0003] In order to better understand the in-pile service performance of silicon carbide composite cladding tubes 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 forming structure, it is difficult to accurately model the thermal-mechanical-irradiation behavior of the braided composite cladding tube. In addition, traditional modeling has little research on the braiding process structure of special-shaped cross-section preforms, which is difficult to meet the requirements of current industrial development. Therefore, increasing research on complex spatial geometric structures and complex special-shaped cross-section preforms is a major research trend today. Summary of the invention

[0004] The purpose of the present invention is to achieve a refined study on the spatial geometric characteristics of the braided tube, to realize a method for establishing a model of a yarn braided tube with an arbitrary cross-section, and to further construct a calculation model for a double-layer composite material cladding tube. At the same time, considering the influence of temperature and radiation on the physical properties of the material during reactor operation, a method and system for calculating the radiation performance of a braided nuclear fuel cladding tube are provided.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: A method for calculating the irradiation performance of a braided nuclear fuel cladding tube comprises the following steps: S1. Establish the overall geometric model of the braided nuclear fuel cladding tube; 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; 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 the braided nuclear fuel cladding tube, and the calculation model of the radiation performance of the cladding tube is obtained; S4. Based on the cladding tube radiation performance calculation model, the cladding tube radiation performance calculation and analysis are performed on the braided nuclear fuel cladding tube.

[0006] 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: S11. Define spatial fluctuation function r ( θ ), write a 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, running 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, output the divided calculation part as an stp file for subsequent calculation; S18. Import the braided tube geometric model stp file into ABAQUS and create a geometric ring tube with the same size as the cladding tube; S19, performing Boolean operation on the established geometric ring tube and the braided tube to obtain a geometric model of a single-layer; S110, assembling and combining 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-material 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-material layer arranged in sequence from the inside to the outside.

[0007] A further improvement of the present invention is that, in step S2, 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: S21, selecting the braiding yarn of the braided 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 principal directions of subsequent material directions; 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 the temperature-related property functions of the yarn material in the UMAT and UMATHT subroutines of the ABAQUS software, including the elastic modulus 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. 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 a preliminary calculation model for the cladding tube radiation performance.

[0008] A further improvement of the present invention is that, 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: S31. Mesh the single-material layer, woven layer and viscous connection layer respectively, and add the viscosity coefficient in the ABAQUS material properties or unit properties; S32. Reduce the minimum incremental step and increase the number of discontinuous iterations in ABAQUS; S33. Change the unit type of the viscous connection layer to a temperature-displacement coupled viscous unit to obtain a calculation model for the radiation performance of the cladding tube.

[0009] A further improvement of the present invention is that, in step S4, based on the cladding tube radiation performance calculation model, the cladding tube radiation performance calculation analysis is performed on the braided nuclear fuel cladding tube, 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, the calculated fast neutron flux Φ Write the UMAT and UMATHT subroutines of the ABAQUS software to define the radiation dose variables that vary with time; S44, rewriting the material properties in the UMAT and UMATHT subroutines into radiation dose related functions; S45. Setting boundary conditions of the cladding tube in various directions; S46. Import the written 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.

[0010] A system for calculating the irradiation performance of a braided nuclear fuel cladding tube, comprising: The geometric model building module builds the overall geometric model of the braided nuclear fuel cladding tube; The module for establishing a preliminary calculation model assigns material behavior to the overall geometric model of the cladding tube to obtain a preliminary calculation model for the irradiation performance of the cladding tube; The calculation model building module adjusts the calculation conditions to increase the calculation convergence of the irradiation performance of the braided nuclear fuel cladding tube based on the preliminary calculation model of the irradiation performance of the cladding tube, and obtains the calculation model of the irradiation performance of the cladding tube; The calculation and analysis module performs irradiation performance calculation and analysis on the braided nuclear fuel cladding tube based on the cladding tube irradiation performance calculation model.

[0011] A further improvement of the present invention is that, in the geometric model building module, building the overall geometric model of the braided nuclear fuel cladding tube includes: Define the spatial fluctuation function r ( θ ), write a 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 variable 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 geometry model; Establish a calculation domain for the established 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 spatial geometric model of the overall cladding tube; A zero-thickness cohesive layer model is added on the common surface of the braided tube and the single-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 viscous connection layer and the single-layer arranged in sequence from the inside to the outside.

[0012] A further improvement of the present invention is that, in the preliminary calculation model establishment module, the material behavior is assigned to the established overall geometric model of the cladding tube to obtain a preliminary calculation model of the cladding tube radiation 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 principal directions of subsequent material directions; 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 ky , specific heat capacity C py , irradiation swelling behavior S y ; 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 irradiation performance of the cladding tube.

[0013] 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 calculation convergence of the cladding tube radiation performance, and the cladding tube radiation performance calculation model is obtained, including: Mesh the single-particle layer, woven layer, and viscous connection layer separately, and add the viscosity coefficient in the ABAQUS material properties or unit properties; Reduce the minimum incremental step and increase the number of discontinuous iteration trials in ABAQUS; The unit type of the viscous connection layer is changed to a temperature-displacement coupled viscous unit, and the calculation model of the cladding tube radiation performance is obtained.

[0014] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for calculating the irradiation performance of a braided nuclear fuel cladding tube.

[0015] Compared with the prior art, the present invention has at least the following beneficial technical effects: The present invention provides a method and system for calculating the irradiation performance of a braided nuclear fuel cladding tube. The present invention first uses a Python script to establish a three-dimensional complex geometric model of the braided tube in Texgen software based on the geometric characteristics of the braided structure, and imports it into the Abaqus software for analysis. Then, a single-layer model of the cladding tube is constructed through Boolean operations, and the local coordinate system of the yarn is defined as the material direction. The cohesion model is used to process the interlayer interaction between the braided layer and the single-layer. Furthermore, 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 injection and irradiation dose that change with time, and the irradiation performance calculation of the cladding tube under operating conditions is realized through a Fortran subroutine. The method adjusts the solution parameters to accelerate convergence and ensure calculation accuracy, thereby providing an efficient calculation tool for the irradiation performance evaluation of braided nuclear fuel cladding tubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a flow chart of a method for calculating the irradiation performance of a braided nuclear fuel cladding tube according to the present invention; Figure 2 (a) and (b) are schematic diagrams of a braided tube structure; Figure 3 (a) and (b) are schematic diagrams of a braided tube structure; Figure 4 (a) and (b) are schematic diagrams of the overall calculation model of the nuclear fuel cladding tube; Figure 5 Schematic diagram of the local coordinate system at the yarn interpolation point in the embodiment; Figure 6 (a) to (c) are stress and temperature cloud diagrams calculated in the embodiment; Figure 7 The present invention is a structural block diagram of a system for calculating the irradiation performance of a braided nuclear fuel cladding tube. DETAILED DESCRIPTION

[0018] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0019] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0020] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0021] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0022] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0023] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0024] 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 structures.

[0025] At present, the establishment of braided structure models mostly selects the cross-section of the braided yarn as a circular cross-section, and there is a lack of research on braided tubes with yarns of special cross-sections.

[0026] Example 1 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: S1. Establish the overall geometric model of the braided nuclear fuel cladding tube; 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; 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 the braided nuclear fuel cladding tube, and the calculation model of the radiation performance of the cladding tube is obtained; S4. Based on the cladding tube radiation performance calculation model, the cladding tube radiation performance calculation and analysis are performed on the braided nuclear fuel cladding tube.

[0027] In this embodiment, in step S1, establishing the overall geometric model of the braided nuclear fuel cladding tube includes: S11. Define spatial fluctuation function r ( θ ), write a 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, running 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, output the divided calculation part as an stp file for subsequent calculation; S18. Import the braided tube geometric model stp file into ABAQUS and create a geometric ring tube with the same size as the cladding tube; S19, performing Boolean operation on the established geometric ring tube and the braided tube to obtain a geometric model of a single-layer; S110, assembling and combining 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-material 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-material layer arranged in sequence from the inside to the outside.

[0028] In this embodiment, in step S2, the material behavior is assigned to the established overall geometric model of the cladding tube to obtain a preliminary calculation model of the irradiation performance of the cladding tube, including: S21, selecting the braiding yarn of the braided 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 principal directions of subsequent material directions; 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 the temperature-related property functions of the yarn material in the UMAT and UMATHT subroutines of the ABAQUS software, including the elastic modulus 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. 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 a preliminary calculation model for the cladding tube radiation performance.

[0029] In this embodiment, in step 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 the braided nuclear fuel cladding tube, and the calculation model of the radiation performance of the cladding tube is obtained, including: S31. Mesh the single-material layer, woven layer and viscous connection layer respectively, and add the viscosity coefficient in the ABAQUS material properties or unit properties; S32. Reduce the minimum incremental step and increase the number of discontinuous iterations in ABAQUS; S33. Change the unit type of the viscous connection layer to a temperature-displacement coupled viscous unit to obtain a calculation model for the radiation performance of the cladding tube.

[0030] In this embodiment, in step S4, based on the cladding tube radiation performance calculation model, the cladding tube radiation performance calculation analysis is performed on the braided nuclear fuel cladding tube, 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, the calculated fast neutron flux Φ Write the UMAT and UMATHT subroutines of the ABAQUS software to define the radiation dose variables that vary with time; S44, rewriting the material properties in the UMAT and UMATHT subroutines into radiation dose related functions; S45. Setting boundary conditions of the cladding tube in various directions; S46. Import the written 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.

[0031] Example 2 The present invention provides a method for calculating the radiation performance of a braided nuclear fuel cladding tube, comprising the following steps: S1. Establish the spatial geometric model of braided nuclear fuel cladding tubes; The above step S1 includes the following sub-steps: It should be noted that the braided tube structure of circular cross-section yarn does not need to consider the torsion of the yarn, and the cross-sectional posture at each interpolation point of the yarn has no effect on the model establishment result. However, the cross-sectional posture at each interpolation point of the yarn with a special cross-section needs to be considered. This embodiment models the braided tube structure of the yarn with a special cross-section.

[0032] S11. Define spatial fluctuation function r ( θ ); 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: (1) 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; The selected r 0 is 5mm, α is 45°, n The cross-sectional shape is oval and the weaving pattern is diamond weave.

[0033] 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; It should be noted that the two space vectors defined in S13 are used to restrict the spatial posture of the yarn with heterogeneous cross-section. The components of the two space vectors can be obtained by fitting the curve of the yarn's spatial path: L ( r 0, α , n , r ( θ )) is obtained by differential calculation. Take a counterclockwise braided yarn in this embodiment as an example: (2) (3) S14. Define the angle independent variable θ The domain and number of interpolation points are written into the Python program; S15, running the Python program in the TexGen software to interpolate the path to obtain continuous clockwise and counterclockwise yarns to form a braided tube geometric model; 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.

[0034] S16, establishing a calculation domain for the established braided tube geometric model, and intercepting a portion used for calculation; S17, output the divided calculation part as an stp file for subsequent calculation; S18. Import the braided tube geometric model stp file into ABAQUS and create a geometric ring tube with the same size as the cladding tube; S19, performing Boolean operation on the established geometric ring tube and the braided tube to obtain a geometric model of a single-layer; S110, assembling and combining the braided tube and the single-material layer to obtain a spatial geometric model of the overall cladding tube; 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; The overall geometric model of the cladding tube obtained in S111 is shown in FIG4 , which is composed of a braided tube structure and a single-material layer.

[0035] S2. Assigning a material behavior model to the established cladding tube space geometry model; The above step S2 includes the following sub-steps: S21, selecting the braiding yarn of the braided 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 principal directions of subsequent material directions; The local coordinate system at the yarn interpolation point in the above step S24 is shown in FIG. 5 .

[0036] 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 .

[0037] 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.

[0038] S26. Add temperature-dependent property functions of yarn materials, including elastic modulus, to the UMAT and UMATHT subroutines of the ABAQUS software E y11 , E y22 , Ey33 , 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 .

[0039] 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.

[0040] S27. Rewrite the stiffness matrix and heat conduction equation of each material in the subroutine according to the defined material property function.

[0041] In the above step S27, the mechanical behavior of the material is defined in the UMAT subroutine of the ABAQUS software, and the thermal behavior is defined in the UMATHT subroutine of the ABAQUS software.

[0042] S3. Adjust the calculation conditions to increase the convergence of the irradiation performance calculation of braided nuclear fuel cladding tubes; The above step S3 includes the following sub-steps: S31. Add viscosity coefficient in material properties or element properties; It should be noted that the viscosity coefficient added in the above step S31 is to accelerate the convergence of the viscosity behavior in the finite element calculation process, and it has no physical meaning. Its value is generally 10 -5 ~10 -4 .

[0043] S32, reducing the minimum incremental step and increasing the number of discontinuous iterative trials; It should be noted that the above step S32 is to reduce the instability in the iterative process and reduce the risk of non-convergence of calculation.

[0044] S33, changing the unit type of the zero-thickness cohesive layer model established in step S111 to a temperature-displacement coupled viscous unit; In this embodiment, the failure criterion of the viscous unit in the above step S33 is: (4) σ0 n ,、 τ0 s and τ0 s is the stress in three directions.

[0045] S4. Calculate and analyze the irradiation performance of the braided nuclear fuel cladding tube based on the method described; The above step S4 includes the following sub-steps: S41. 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, the fast neutron fluence calculated in step S43 Φ Write the UMAT and UMATHT subroutines of the ABAQUS software to define the radiation dose variables that vary with time; S44, adding the material properties in step S25 and step S26 as a radiation dose related function; In this embodiment, after step S44 is implemented, all the physical properties described in steps S25 and S26 are functions of temperature and irradiation dose.

[0046] S45. Setting boundary conditions of the cladding tube in various directions; S46. Import the written 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.

[0047] In this embodiment, after implementing 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.

[0048] Example 3 like Figure 7 As shown, the present invention provides a system for calculating the radiation performance of a braided nuclear fuel cladding tube, comprising: The geometric model building module builds the overall geometric model of the braided nuclear fuel cladding tube; The module for establishing a preliminary calculation model assigns material behavior to the overall geometric model of the cladding tube to obtain a preliminary calculation model for the irradiation performance of the cladding tube; The calculation model building module adjusts the calculation conditions to increase the calculation convergence of the irradiation performance of the braided nuclear fuel cladding tube based on the preliminary calculation model of the irradiation performance of the cladding tube, and obtains the calculation model of the irradiation performance of the cladding tube; The calculation and analysis module performs irradiation performance calculation and analysis on the braided nuclear fuel cladding tube based on the cladding tube irradiation performance calculation model.

[0049] Example 4 The present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps of the method for calculating the irradiation performance of a braided nuclear fuel cladding tube are implemented.

[0050] 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 adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0051] 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 the 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 generate 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 multiple boxes.

[0052] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate 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 A function specified in one or more boxes.

[0053] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0054] 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 the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0055] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

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. Establish the overall geometric model of the braided nuclear fuel cladding tube; 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; 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 the braided nuclear fuel cladding tube, and the calculation model of the radiation performance of the cladding tube is obtained; 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 a 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, running 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, output 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 operation on the established geometric ring tube and the braided tube to obtain a geometric model of a single-layer; S110, assembling and combining 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-material 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-material layer arranged in sequence from the inside to the outside.

3. The method for calculating the radiation performance of a braided nuclear fuel cladding tube according to claim 2, characterized in that: In step S2, the material behavior is assigned to the established overall geometric model of the cladding tube to obtain a preliminary calculation model of the cladding tube radiation performance, including: S21, selecting the braiding yarn of the braided 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 principal directions of subsequent material directions; 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 the temperature-related property functions of the yarn material in the UMAT and UMATHT subroutines of the ABAQUS software, including the elastic modulus 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. 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 a preliminary calculation model for the cladding tube radiation performance.

4. The method for calculating the radiation performance of a braided nuclear fuel cladding tube according to claim 3, characterized in that: In step S3, 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 calculation model of the cladding tube radiation performance is obtained, including: S31. Mesh the single-material layer, woven layer and viscous connection layer respectively, and add the viscosity coefficient in the ABAQUS material properties or unit properties; S32. Reduce the minimum incremental step and increase the number of discontinuous iterations in ABAQUS; S33. Change the unit type of the viscous connection layer to a temperature-displacement coupled viscous unit to obtain a calculation model for the radiation performance of the cladding tube.

5. The method for calculating the radiation performance of a braided nuclear fuel cladding tube according to claim 4, characterized in that: In step S4, based on the cladding tube radiation performance calculation model, the cladding tube radiation performance calculation analysis is performed on the braided nuclear fuel cladding tube, 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, the calculated fast neutron flux Φ Write the UMAT and UMATHT subroutines of the ABAQUS software to define the radiation dose variables that vary with time; S44, rewriting the material properties in the UMAT and UMATHT subroutines into radiation dose related functions; S45. Setting boundary conditions of the cladding tube in various directions; S46. Import the written 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.

6. A system for calculating the radiation performance of a braided nuclear fuel cladding tube, characterized in that: include: The geometric model building module builds the overall geometric model of the braided nuclear fuel cladding tube; The module for establishing a preliminary calculation model assigns material behavior to the overall geometric model of the cladding tube to obtain a preliminary calculation model for the irradiation performance of the cladding tube; The calculation model building module adjusts the calculation conditions to increase the calculation convergence of the irradiation performance of the braided nuclear fuel cladding tube based on the preliminary calculation model of the irradiation performance of the cladding tube, and obtains the calculation model of the irradiation performance of the cladding tube; The calculation and analysis module performs irradiation performance calculation and analysis on the braided nuclear fuel cladding tube based on the cladding tube irradiation performance calculation model.

7. The radiation performance calculation system of a braided nuclear fuel cladding tube according to claim 6, characterized in that: In the geometric model building module, the overall geometric model of the braided nuclear fuel cladding tube is established, including: Define the spatial fluctuation function r ( θ ), write a 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 variable 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 geometry model; Establish a calculation domain for the established 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 spatial geometric model of the overall cladding tube; A zero-thickness cohesive layer model is added on the common surface of the braided tube and the single-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 viscous connection layer and the single-layer arranged in sequence from the inside to the outside.

8. The radiation performance calculation system of a braided nuclear fuel cladding tube according to claim 7, characterized in that: In the preliminary calculation model establishment module, the material behavior is assigned to the established overall geometric model of the cladding tube to obtain the preliminary calculation model of the cladding tube 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 principal directions of subsequent material directions; 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 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 irradiation performance of the cladding tube.

9. The radiation performance calculation system of a braided nuclear fuel cladding tube according to claim 8, characterized in that: In the calculation model establishment module, based on the preliminary calculation model of cladding tube irradiation performance, the calculation conditions are adjusted to increase the calculation convergence of the irradiation performance of braided nuclear fuel cladding tubes, and the calculation model of cladding tube irradiation performance is obtained, including: Mesh the single-particle layer, woven layer, and viscous connection layer separately, and add the viscosity coefficient in the ABAQUS material properties or unit properties; Reduce the minimum incremental step and increase the number of discontinuous iteration trials in ABAQUS; The unit type of the viscous connection layer is changed to a temperature-displacement coupled viscous unit, and the calculation model of the cladding tube radiation performance is obtained.

10. 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 a method for calculating the irradiation performance of a braided nuclear fuel cladding tube according to any one of claims 1 to 5.

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