CN112730078A - Fracture toughness analysis method for pressure-bearing main equipment of nuclear power plant and pressure-bearing equipment of chemical machinery - Google Patents

Abstract

The invention relates to a fracture toughness analysis method for pressure-bearing main equipment of a nuclear power plant and pressure-bearing equipment of chemical machinery, in particular to a fracture toughness analysis method for pressure-bearing equipment, which belongs to the field of nuclear power and pressure-bearing of chemical machinery and aims to solve the problem that the conventional pressure container fracture prevention method has no clear judgment and calculation method; the method adopts a linear elastic fracture mechanics theory, namely an analysis method for correlating the numerical value and distribution of the stress field near the crack tip of the linear elastic body with the crack with the size of the crack which possibly causes non-ductile failure is the numerical relationship among the fracture toughness, the size of the crack defect and the stress level of the material during crack propagation; the invention can analyze and judge the load at every moment, improve the accuracy of calculation, develop corresponding calculation software and improve the economy and the calculation efficiency.

Description

Fracture toughness analysis method for pressure-bearing main equipment of nuclear power plant and pressure-bearing equipment of chemical machinery

Technical Field

The invention discloses a fracture toughness analysis method for pressure-bearing main equipment of a nuclear power plant and pressure-bearing equipment of chemical machinery, in particular relates to a fracture toughness analysis method for pressure-bearing equipment, and belongs to the field of nuclear power and pressure-bearing of chemical machinery.

Background

For the current method for preventing the pressure container from breaking, no clear judgment and calculation method exists, the method for preventing the low-temperature brittle failure from the aspects of material selection and low-temperature low-stress working condition in GB/T150 is generally adopted in China, and whether the possibility of breaking exists is not judged from the aspect of numerical simulation; in the foreign standards, the failure of the equipment is judged by simply judging whether the crack is expanded or not by providing an inspection result and a load value when a regular inspection is operated, and a suggested result is not considered and provided from a design source.

Based on a method combining theory with foreign standards and design experience, a set of conservative fracture prevention method is researched, and further, a reasonable structural wall thickness can be designed through calculation, so that the structural strength requirement is met, and the brittle fracture prevention can also be met.

The principle is adopted: the method is a linear elastic fracture mechanics theory, namely an analysis method for correlating the value and distribution of the stress field near the crack tip of the linear elastic body with the crack with the size of the crack which can cause non-ductile failure, and is a numerical relation among the fracture toughness, the size of a crack defect and the stress level of a material during crack propagation.

In general, a stress field in the vicinity of a crack can be classified into an open type, a slip type, and a tear type according to the state of deformation of the crack surface in accordance with the relationship between the position of the crack and the stress, and brittle fracture of a pressure vessel is mainly an open type, that is, an object of study of this patent.

Disclosure of Invention

In order to solve the problem that the existing pressure container fracture prevention method has no clear judgment and calculation method, the invention provides a fracture toughness analysis method for pressure-bearing main equipment of a nuclear power plant and pressure-bearing equipment of chemical machinery, which comprises the following specific steps:

extracting coordinate point data of the main wall thickness of a geometric model to be measured, and establishing a finite element model;

step two, extracting and analyzing the boundary mechanical transient load, and judging the boundary temperature transient load;

step three, integrating the data of the extraction analysis result in the step two;

step four, calculating a reference critical stress intensity factor K by adopting a theoretical formula_ICAnd calculating a reference critical stress intensity factor K_IR；

Step five, respectively calculating the tensile stress intensity factors K of the primary film in the axial direction and the circumferential direction_ImAnd judging whether the structure is continuous or not;

step six, calculating a safety factor F according to working conditions, and firstly judging whether the result is less than K_ICThen, whether it is less than K is judged_IRIf so, the structural design wall thickness of the geometric model to be tested is proved to be reasonable;

and step seven, judging that the condition is not met according to the step six, modifying the parameters, returning to the step one, or calculating the allowable defect size, and summarizing the result to a risk assessment report for prompting related personnel to regularly check.

Further, in the first step, regarding the main wall thickness data of the geometric model to be measured, data are extracted under a thermal analysis extraction result path, and the specific steps are detailed as follows:

firstly, extracting a thermal analysis calculation result, if a linearization path is consistent with a global coordinate system, extracting under the global coordinate system, otherwise, rotating the coordinate;

and step two, extracting a structure analysis result, and judging whether the coordinate needs to be rotated or not in the same way as the steps one by one.

Further, defining the position width of the geometric model to be detected as T, and extracting data according to the following two conditions:

in the first case, for changing the rotation coordinate, under the new coordinate system:

(1) when T is more than or equal to 100mm and less than or equal to 300mm, the steps are as follows:

step a1, extracting temperature values at the internal and external T/4 positions;

step a2, extracting total stress component values of Z direction and Y direction at least at four pairs of thicknesses in the thickness range less than T/4;

step a3, extracting time values at internal and external T/4 positions;

step a4, linearizing the path width;

step a5, extracting axial and circumferential film stress and bending stress at the inner T/4 part and the outer T/4 part;

(2) when T is more than or equal to 25mm and less than 100mm, the steps a1-a5 are carried out, and T/4 is replaced by 25 mm;

in the second case, without changing the coordinate system:

(1) when T is more than or equal to 100mm and less than or equal to 300mm, the steps are as follows:

step b1, extracting temperature values at the internal and external T/4 positions;

step b2, extracting total stress component values of Z direction and Y direction at least at four pairs of thicknesses within the thickness range less than T/4;

b3, extracting time values at the internal and external T/4 positions;

step b4, linearizing the path width;

b5, extracting axial and circumferential film stress and bending stress at the inner T/4 part and the outer T/4 part;

(2) when T is more than or equal to 25mm and less than 100mm, the steps b1-b5 are carried out, and T/4 is replaced by 25 mm;

further, data are extracted under the thermal analysis extraction result path, wherein the specific operation steps of extracting the structure temperature result of the structure continuous area are as follows:

in the first case, with respect to changing the rotation coordinate, under the new coordinate system:

(1) when T is more than or equal to 100mm, the steps are as follows:

step c1, extracting Z-direction and Y-direction film stress values at the T/4 position of the inner and outer surfaces;

step c2, extracting time values at the internal and external T/4 positions;

step c3, linearizing the path width;

(2) when T is more than or equal to 25mm and less than 100mm, the steps are as follows:

d1, extracting stress values of the films in the Z direction and the Y direction at the positions of 25mm on the inner surface and the outer surface;

step d2, extracting time values at the positions of 25mm inside and outside;

step d3, linearizing the path width;

in the second case, without changing the coordinate system:

(1) when T is more than or equal to 100mm, the steps are as follows:

step e1, extracting Z-direction and Y-direction film stress values at the T/4 position of the inner and outer surfaces;

step e2, extracting time values at the internal and external T/4 positions;

step e3, linearizing the path width;

(2) when 63mm < T <100mm, then the steps are:

f1, extracting stress values of the films in the Z direction and the Y direction at the positions of 25mm on the inner surface and the outer surface;

step f2, extracting time values at the positions of 25mm inside and outside;

step f3, linearizing the path width;

further, data are extracted under the thermal analysis extraction result path, wherein the specific operation steps of extracting the temperature result of the structural discontinuous region are as follows:

(1) when T is more than or equal to 100mm, the steps are as follows:

step g1, extracting Z-direction and Y-direction film stress values at the T/4 position of the inner and outer surfaces;

step g2, extracting time values at the internal and external T/4 positions;

step g3, linearizing the path width;

(2) when 63mm < T <100mm, then the steps are:

h1, extracting stress values of the films in the Z direction and the Y direction at the positions of 25mm on the inner surface and the outer surface;

step h2, extracting time values at the positions of 25mm inside and outside;

step h3, linearizes the path width.

The invention has the beneficial effects that:

the method adopts a linear elastic fracture mechanics theory, namely an analysis method for correlating the numerical value and distribution of a stress field near the crack tip of the linear elastic body with the crack with the size of the crack which possibly causes non-ductile failure, and is a numerical relation among fracture toughness, crack defect size and stress level of the material during crack propagation;

firstly, a relatively conservative calculation structure is used for judging whether the structure has cracks or crack propagation under the combined action of an alternating temperature transient load and an alternating mechanical transient load;

secondly, designing a reasonable and economic structure size on the basis of market economic benefits and cost, and prejudging the position and the size of the position which are likely to have cracks to a user in advance to remind the user to carry out regular inspection;

thirdly, for high-pressure low-temperature important equipment, according to the safety level and the hazard degree, a reasonable structure and wall thickness are provided from the fracture toughness direction;

and fourthly, for low-pressure high-temperature equipment, the wall thickness of a local structure can be reduced under the condition of meeting the basic strength, so that secondary stress components are reduced, and the occurrence of fracture is prevented (the wall thickness is increased, and the probability of the occurrence of fracture is also improved).

And fifthly, the load at every moment can be analyzed and judged, the calculation accuracy is improved, corresponding calculation software is developed, and the economy and the calculation efficiency are improved.

Drawings

FIG. 1 is a schematic flow chart of a fracture toughness analysis method for a pressure-bearing main device of a nuclear power plant and a pressure-bearing device of chemical machinery;

FIG. 2 is a plot of hypothetical defect depth versus interface size;

FIG. 3 is a schematic diagram of a virtual defect in practical use;

wherein, part A is a defect in a YZ plane, the stress takes the X direction (circumferential defect), part B is a defect in an XY plane, and the stress takes the Z direction (axial defect);

FIG. 4 is a schematic diagram of a thermal analysis extraction result path;

FIG. 5 is a schematic diagram of a temperature result extraction path for a structural discontinuity zone;

FIG. 6 is a schematic diagram of a structure analysis result extraction path at a structure continuation;

FIG. 7 is a schematic diagram of a structure analysis result extraction path of a structural discontinuity area;

FIG. 8 is a critical stress intensity factor limit graph;

FIG. 9 is a graph of the critical stress intensity factor KIC versus Kia;

FIG. 10 is an analysis chart of the solution algorithm of KIt.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings:

the specific implementation mode is as follows: according to the requirements of the virtual defects, for the section with the thickness of 100mm to 300mm, the depth (a) of the virtual defects is 1/4 of the section thickness, the length (2c) is 1.5 times of the section thickness, namely, the length-depth ratio is (2 c/a) ═ 6:1, and the defects are assumed to be arranged on the inner surface and the outer surface; for sections greater than 300mm thick, a hypothetical defect of 300mm thick section is employed; for sections less than 100mm thick, conservative readings assume a defect depth of 25 mm. The combined path P01 has a cross-sectional dimension of 80.4mm, less than 100mm, so an imaginary maximum defect depth is taken at 25mm from the inner and outer surfaces, i.e. surface cracking refers to a cross-sectional thickness of less than 0.7 times the crack depth (a); a deep-buried crack refers to a crack having a depth (2a) less than 0.7 times the cross-sectional thickness, otherwise a through-crack, where the cracks studied by specification are long surface cracks and the cracks studied by specification are elliptical flaky surface cracks, with an aspect ratio (2 c/a) of 6: 1.

1. Device fracture mechanics assessment data extraction

When fracture mechanics is evaluated, the extraction requirement of data is divided into two steps; firstly, extracting a thermal analysis calculation result, and firstly, if a linearization path is consistent with a global coordinate system, extracting under the global coordinate system, otherwise, rotating the coordinate is needed, as shown in a P02 path in FIG. 4, and the specific data is required as shown in the graph 1. The second step, extracting the structure analysis result, as in the first step, judging whether the coordinates need to be rotated, and then performing the data request in fig. 4.

2. Evaluating the required thermal analysis result data, and setting T (mm) as the width of the part to be detected;

for the structural continuous area, from the result of calculating the temperature distribution,

(1) when T is more than or equal to 100mm and less than or equal to 300mm, the steps are as follows:

step a1, extracting temperature values at the internal and external T/4 positions;

step a2, extracting total stress component values of Z direction and Y direction at least at four pairs of thicknesses in the thickness range less than T/4;

step a3, extracting time values at internal and external T/4 positions;

step a4, linearizing the path width;

step a5, extracting axial and circumferential film stress and bending stress at the inner T/4 part and the outer T/4 part;

(2) when T is more than or equal to 25mm and less than 100mm, the steps a1-a5 are carried out, and T/4 is replaced by 25 mm;

secondly, on the premise of not changing the coordinate system:

(1) when T is more than or equal to 100mm and less than or equal to 300mm, the steps are as follows:

step b1, extracting temperature values at the internal and external T/4 positions;

step b2, extracting total stress component values of Z direction and Y direction at least at four pairs of thicknesses within the thickness range less than T/4;

b3, extracting time values at the internal and external T/4 positions;

step b4, linearizing the path width;

b5, extracting axial and circumferential film stress and bending stress at the inner T/4 part and the outer T/4 part;

(2) when T is more than or equal to 25mm and less than 100mm, the steps b1-b5 are carried out, and T/4 is replaced by 25 mm;

the extraction in the thermal analysis results is shown in FIG. 4;

secondly, for the structural discontinuous area, from the result of calculating the temperature distribution,

(1) when T is more than or equal to 100mm, the steps are as follows:

step c1, extracting Z-direction and Y-direction film stress values at the T/4 position of the inner and outer surfaces;

step c2, extracting time values at the internal and external T/4 positions;

step c3, linearizing the path width;

(2) when T is more than or equal to 25mm and less than 100mm, the steps are as follows:

d1, extracting stress values of the films in the Z direction and the Y direction at the positions of 25mm on the inner surface and the outer surface;

step d2, extracting time values at the positions of 25mm inside and outside;

step d3, linearizing the path width;

FIG. 5 is extracted from the results of the thermal analysis;

3. structural analysis result data required for evaluation

Firstly, for the structural continuous region, from the result of calculating structural analysis,

one, regarding changing the rotation coordinate, under the new coordinate system:

(1) when T is more than or equal to 100mm, the steps are as follows:

step e1, extracting Z-direction and Y-direction film stress values at the T/4 position of the inner and outer surfaces;

step e2, extracting time values at the internal and external T/4 positions;

step e3, linearizing the path width;

(2) when T is more than or equal to 25mm and less than 100mm, the steps are as follows:

f1, extracting stress values of the films in the Z direction and the Y direction at the positions of 25mm on the inner surface and the outer surface;

step f2, extracting time values at the positions of 25mm inside and outside;

step f3, linearizing the path width;

secondly, on the premise of not changing the coordinate system:

(1) when T is more than or equal to 100mm, the steps are as follows:

step g1, extracting Z-direction and Y-direction film stress values at the T/4 position of the inner and outer surfaces;

step g2, extracting time values at the internal and external T/4 positions;

step g3, linearizing the path width;

(2) when 63mm < T <100mm, then the steps are:

h1, extracting stress values of the films in the Z direction and the Y direction at the positions of 25mm on the inner surface and the outer surface;

step h2, extracting time values at the positions of 25mm inside and outside;

step h3, linearizing the path width;

the extraction is shown in FIG. 6;

secondly, for the structural discontinuous area, from the result of calculating the structure,

on the premise of not changing the coordinate system:

(1) when T is more than or equal to 100mm, the steps are as follows:

step i1, extracting Z-direction and Y-direction film stress values at the T/4 position of the inner and outer surfaces;

step i2, extracting time values at internal and external T/4 positions;

step i3, linearizing the path width;

(2) when 63mm < T <100mm, then the steps are:

step j1, extracting Z-direction and Y-direction film stress values at 25mm positions of the inner and outer surfaces;

step j2, extracting time values at the positions of 25mm inside and outside;

step j3, linearizes the path width.

The extraction is shown in FIG. 7.

4.0 calculation of the Critical stress Strength factor: (

MPa as the unit of the formula

4.1 calculation formula:

t is the temperature at the defect, DEG C;

RT_NDT: reference non-ductile transition temperature, deg.C;

K_Ic: plane strain fracture toughness by stress intensity factor K_IMeasured material toughness, which will result in no ductile crack propagation;

K_I: in linear elastomers, when the deformation separates the crack planes, the normal to the crack plane (type I) approachesA measure of the stress field strength of the ideal crack tip;

4.2 calculation formula:

t is the temperature at the defect, DEG C;

RT_NDT: reference non-ductile transition temperature, deg.C;

K_Ia: crack arrest fracture toughness, stress intensity factor K to crack arrest of defects_IA critical value of (a), i.e., less than a value at which the crack does not propagate, and greater than or equal to a value at which the crack propagates;

K_Ic: crack fracture toughness, critical value for defect crack initiation, i.e. above which the crack completely initiates:

4.3 alternative calculation formula:

english system;

metric system;

t temperature at defect, F/° C;

RT_NDT: reference non-ductile transition temperature, F/° C;

K_IR: crack propagationSpreading resistance, take K_IaAnd K_ICThe smaller value of (d);

5.0 method for solving the stress intensity factor of the primary film and the radial gradient in different areas:

5.1 areas away from the discontinuity:

for the evaluation of the structure continuous area, according to the thickness of the path and the assumed defect position, the axial direction and the annular direction are respectively evaluated, the stress is the stress vertical to the defect direction, namely the annular stress is extracted from the axial defect, the axial stress is extracted from the annular defect, and the annular direction and the axial direction at the moment are relative to a local coordinate system of the path instead of a modeling global coordinate system.

Evaluating the requirements according to the shell and the seal head area at the continuous position of the geometric shape; the sum of the following must be less than K_IC；

(1)2K_Im1And for the primary film stress intensity factor,

given by;

(2)K_It(ii) a The radial temperature gradient stress intensity factor is determined,

the following formula is obtained;

for internal surface defects during cool down:

for external surface defects during temperature rise:

the coefficients C0, C1, C2, and C3 are determined as follows for the thermal stress distribution during the ramp up and ramp down at any given time:

σ(x)＝C₀+C₁(x/a)+C₂(x/a)²+C₃(x/a)³

x: is a virtual variable representing the radial distance (0. ltoreq. x/a. ltoreq.1) from a suitable surface, such as an inner or outer wall, m

a: maximum crack depth, m

σ (x): when the axial defect (corresponding to a local coordinate system) is evaluated, at least 4 stress components are taken along the section, wherein the stress components include the inner surface and the outer surface and the inner thickness and the outer thickness of T/4, and the stress components are MPa

The calculation result satisfies 2K_Im1+K_It＜K_ICThe evaluation of a plurality of the samples is qualified,

5.2 housing region adjacent to the discontinuity

Assessment of the shell area adjacent to the geometric discontinuity requires areas of relatively complex stress distribution.

(a) For normal operating conditions, the sum of the following must be less than K_IC；

(1)2K_Im1Primary film stress;

(2)2K_Ib1primary bending stress;

(3)K_Im2secondary film stress;

(4)K_Ib2secondary bending stress;

namely: 2K_Im1+2K_Ib1+K_Im2+K_Ib2＜K_IC

(b) For the hydraulic test working condition, the sum of the following items is required to be less than KIC;

(1)1.5K_Im1primary film stress;

(2)1.5K_Ib1primary bending stress;

(3)K_Im2secondary film stress;

(4)K_Ib2secondary bending stress;

namely: 1.5K_Im1+1.5K_Ib1+K_Im2+K_Ib2＜K_IC

(c) For other working conditions, the working condition is a hypothetical working condition with low probability, and the sum of the following items is necessarily less than KIC during calculation;

(1)K_Im1primary film stress;

(2)K_Ib1primary bending stress;

(3)K_Im2secondary film stress;

(4)K_Ib2secondary bending stress;

namely: k_Im1+K_Ib1+K_Im2+K_Ib2＜K_IC

In the formula:

K_Im1: primary film stress intensity factor, K_Im1＝M_m×σ_m；

M_m: a correction factor;

σ_m(ii) a Primary film stress; MPa;

K_Ib1: primary bending stress intensity factor, K_Ib1＝M_b×σ_b；

M_b: correction factor, M_b＝2×M_m/3；

σ_b: primary bending stress; MPa;

K_Im2: secondary film stress intensity factor, K_Im2＝M_m×σ_M；

σ_M: secondary film stress; MPa;

K_Ib2: secondary bending stress intensity factor, K_Ib2＝M_b×σ_B；

σ_B: secondary bending stress; MPa;

the second embodiment is as follows: according to the description of the calculation step of embodiment 4.2, the following alternative calculation method can be used for the calculation step:

english system;

metric system;

t temperature at defect, F/° C;

RT_NDTreference non-ductile transition temperature, F/° C;

K_IR: crack propagation resistance, take K_IaAnd K_ICThe smaller value of (d);

the third concrete implementation mode: according to the description of the calculation step of the first embodiment 5.2, the following alternative calculation method can be used for the calculation step: :

the method is based on a strength factor generated by mechanical load, and for the tensile stress strength factor generated by the mechanical load, the method comprises the following steps:

bending stress intensity factor for mechanical load:

M_k: a film stress correction factor; m_B: a bending stress correction coefficient; a: depth of defect; m; q: a plastic zone defect shape correction factor;

σ_m: primary film stress; mpa (Mpa)

σ_b: primary bending stress; mpa (Mpa)

The corrected total stress intensity factor after considering the thermal stress effect:

σ_M: secondary film stress; MPa of

σ_B: secondary bending stress; MPa of

F: the safety factor is 2.0 for operation; 1.0 for the others; take 1.5 for the hydrostatic test.

When the calculation is failed, the alpha value is calculated according to the deformation formula of the formula, namely KIa-KI, and the limit depth of the defect is calculated.

The defect length should be detectable by non-destructive inspection and within a controllable range.

While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims; therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (5)

1. A fracture toughness analysis method for pressure-bearing main equipment of a nuclear power plant and pressure-bearing equipment of chemical machinery is characterized by comprising the following steps: the method comprises the following specific steps:

extracting coordinate point data of the main wall thickness of a geometric model to be measured, and establishing a finite element model;

step two, extracting and analyzing the boundary mechanical transient load, and judging the boundary temperature transient load;

step three, integrating the data of the extraction analysis result in the step two;

step four, calculating a reference critical stress intensity factor K by adopting a theoretical formula_ICAnd calculating a reference critical stress intensity factor K_IR；

Step five, respectively calculating the tensile stress intensity factors K of the primary film in the axial direction and the circumferential direction_ImAnd judging whether the structure is continuous or not;

step six, calculating a safety factor F according to working conditions, and firstly judging whether the result is less than K_ICThen, whether it is less than K is judged_IRIf so, the structural design wall thickness of the geometric model to be tested is proved to be reasonable;

and step seven, judging that the condition is not met according to the step six, modifying the parameters, returning to the step one, or calculating the allowable defect size, and summarizing the result to a risk assessment report for prompting related personnel to regularly check.

2. The method for analyzing the fracture toughness of the pressure-bearing main equipment of the nuclear power plant and the pressure-bearing equipment of the chemical machinery according to claim 1, is characterized in that: in the first step, regarding the main wall thickness data of the geometric model to be measured, data are extracted under a thermal analysis extraction result path, and the specific steps are detailed as follows:

firstly, extracting a thermal analysis calculation result, if a linearization path is consistent with a global coordinate system, extracting under the global coordinate system, otherwise, rotating the coordinate;

and step two, extracting a structure analysis result, and judging whether the coordinate needs to be rotated or not in the same way as the steps one by one.

3. The method for analyzing the fracture toughness of the pressure-bearing main equipment of the nuclear power plant and the pressure-bearing equipment of the chemical machinery according to claim 2, is characterized in that: defining the position width of the geometric model to be detected as T, and extracting data according to the following two conditions:

in the first case, for changing the rotation coordinate, under the new coordinate system:

(1) when T is more than or equal to 100mm and less than or equal to 300mm, the steps are as follows:

step a1, extracting temperature values at the internal and external T/4 positions;

step a2, extracting total stress component values of Z direction and Y direction at least at four pairs of thicknesses in the thickness range less than T/4;

step a3, extracting time values at internal and external T/4 positions;

step a4, linearizing the path width;

step a5, extracting axial and circumferential film stress and bending stress at the inner T/4 part and the outer T/4 part;

(2) when T is more than or equal to 25mm and less than 100mm, the steps a1-a5 are carried out, and T/4 is replaced by 25 mm;

in the second case, without changing the coordinate system:

(1) when T is more than or equal to 100mm and less than or equal to 300mm, the steps are as follows:

step b1, extracting temperature values at the internal and external T/4 positions;

step b2, extracting total stress component values of Z direction and Y direction at least at four pairs of thicknesses within the thickness range less than T/4;

b3, extracting time values at the internal and external T/4 positions;

step b4, linearizing the path width;

b5, extracting axial and circumferential film stress and bending stress at the inner T/4 part and the outer T/4 part;

(2) when T <100mm is less than or equal to 25mm, the same procedure is followed as in steps b1-b5, replacing T/4 with 25 mm.

4. The method for analyzing the fracture toughness of the pressure-bearing main equipment of the nuclear power plant and the pressure-bearing equipment of the chemical machinery according to claim 2 or 3, is characterized in that: and extracting data under the thermal analysis extraction result path, wherein the specific operation steps of extracting the structure temperature result of the structure continuous area are as follows:

in the first case, with respect to changing the rotation coordinate, under the new coordinate system:

(1) when T is more than or equal to 100mm, the steps are as follows:

step c1, extracting Z-direction and Y-direction film stress values at the T/4 position of the inner and outer surfaces;

step c2, extracting time values at the internal and external T/4 positions;

step c3, linearizing the path width;

(2) when T is more than or equal to 25mm and less than 100mm, the steps are as follows:

d1, extracting stress values of the films in the Z direction and the Y direction at the positions of 25mm on the inner surface and the outer surface;

step d2, extracting time values at the positions of 25mm inside and outside;

step d3, linearizing the path width;

in the second case, without changing the coordinate system:

(1) when T is more than or equal to 100mm, the steps are as follows:

step e1, extracting Z-direction and Y-direction film stress values at the T/4 position of the inner and outer surfaces;

step e2, extracting time values at the internal and external T/4 positions;

step e3, linearizing the path width;

(2) when 63mm < T <100mm, then the steps are:

f1, extracting stress values of the films in the Z direction and the Y direction at the positions of 25mm on the inner surface and the outer surface;

step f2, extracting time values at the positions of 25mm inside and outside;

step f3, linearizes the path width.

5. The method for analyzing the fracture toughness of the pressure-bearing main equipment of the nuclear power plant and the pressure-bearing equipment of the chemical machinery according to claim 4, is characterized in that: and extracting data under the thermal analysis extraction result path, wherein the specific operation steps of extracting the temperature result of the structural discontinuous region are as follows:

(1) when T is more than or equal to 100mm, the steps are as follows:

step g1, extracting Z-direction and Y-direction film stress values at the T/4 position of the inner and outer surfaces;

step g2, extracting time values at the internal and external T/4 positions;

step g3, linearizing the path width;

(2) when 63mm < T <100mm, then the steps are:

h1, extracting stress values of the films in the Z direction and the Y direction at the positions of 25mm on the inner surface and the outer surface;

step h2, extracting time values at the positions of 25mm inside and outside;

step h3, linearizes the path width.

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