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HJ 1201-2021: (Safety Design Guidelines for the Prevention of Brittle Fracture in the Transport Containers of Radioactive Materials)
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(Safety Design Guidelines for the Prevention of Brittle Fracture in the Transport Containers of Radioactive Materials)
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HJ 1201-2021
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Standard similar to HJ 1201-2021 HJ 1199 HJ 1200 HJ 1198 Basic data | Standard ID | HJ 1201-2021 (HJ1201-2021) | | Description (Translated English) | (Safety Design Guidelines for the Prevention of Brittle Fracture in the Transport Containers of Radioactive Materials) | | Sector / Industry | Environmental Protection Industry Standard | | Word Count Estimation | 12,170 | | Issuing agency(ies) | Ministry of Ecology and Environment | HJ 1201-2021: (Safety Design Guidelines for the Prevention of Brittle Fracture in the Transport Containers of Radioactive Materials)
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(Safety Design Guidelines for the Prevention of Brittle Fracture in the Transport Containers of Radioactive Materials)
National Ecological Environment Standard of the People's Republic of China
Safety of radioactive material transport containers against brittle fracture
Design Guidelines
Guidelines for the safe design of packaging for radioactive material against
brittle fracture
This electronic version is the official standard text, which is reviewed and typeset by the Environmental Standards Institute of the Ministry of Ecology and Environment.
Published on 2021-11-13
2021-12-01 Implementation
Released by the Ministry of Ecology and Environment
directory
Foreword...ii
1 Scope...1
2 Normative references...1
3 Terms and Definitions...1
4 Selection of anti-brittle fracture design method...2
5 Exemption conditions for evaluation of brittle fracture resistance...2
6 Methods for evaluating ferritic steels using material toughness indicators such as non-plastic transition temperature... 2
7 Methods of evaluating fracture resistance using fracture mechanics theory... 6
Guidelines for the safe design of radioactive material transport containers against brittle fracture
1 Scope of application
This standard specifies the safety design evaluation method for brittle fracture prevention of radioactive material transport containers.
This standard applies to radioactive material transport container containment systems made of ferritic steel, austenitic stainless steel, ductile iron and other metal materials
The anti-brittle fracture design of, the anti-brittle fracture design of non-contained system can be implemented by reference.
2 Normative references
This standard refers to the following documents or clauses thereof. For dated references, only the dated version applies to this standard.
For undated references, the latest edition (including all amendments) applies to this standard.
GB 11806 Regulations for Safe Transport of Radioactive Materials
GB 150 Pressure Vessels
GB/T 229 Charpy Pendulum Impact Test Method for Metallic Materials
GB/T 4161 Metallic Materials Plane Strain Fracture Toughness KIC Test Method
GB/T 5482 Dynamic tear test method for metallic materials
GB/T 6803 Drop weight test method for non-plastic transformation temperature of ferritic steel
GB/T 8363 Steel drop test method
GB/T 21143 Unified test method for quasi-static fracture toughness of metallic materials
3 Terms and Definitions
The following terms and definitions apply to this standard.
3.1
nil-ductility transition temperature
When tested according to the standard method of drop weight test, the maximum temperature at which the drop weight specimen breaks, expressed as TNDT.
3.2
fracture toughness
A general term that usually refers to crack propagation resistance under quasi-static single loading conditions, denoted by KIc.
3.3
dynamic fracture toughness
Characterizing the ability of a material to resist crack propagation is a quantitative index to measure the toughness of a material under dynamic loading, expressed by KId.
3.4
stress intensity factor
The magnitude of the ideal crack tip stress field, denoted by K, for a homogeneous linear elastic body under a specific crack propagation type.
3.5
yield strength
When a metallic material exhibits the phenomenon of yielding, the stress at which plastic deformation occurs during a test without an increase in force. A distinction should be made between upper yield strength and
lower yield strength. The upper yield strength is represented by ReL and the lower yield strength is represented by ReH. Yield strength is usually measured at a quasi-static loading rate.
The lower yield strength is obtained.
3.6
dynamic yield strength
Yield strength measured at a dynamic loading rate (eg impact), expressed as σyd.
3.7
net section stress
The mean stress on the net section. The net section is equal to the gross section (gross section) minus the area of the holes in the section.
4 Selection of design method for brittle fracture prevention
4.1 In order to meet the safety requirements for the transport of radioactive materials in the transport container under the normal transport conditions and transport accident conditions specified in GB 11806,
Limit external radiation, ensure containment of radioactive materials, and prevent nuclear criticality, and radioactive materials transport containers should be designed to prevent brittleness
Sexual rupture.
4.2 The designer may use any of the following methods to evaluate the brittle fracture resistance design.
The first method is to exempt the evaluation of anti-brittle fracture by selecting materials, and the exemption condition is to select materials within the required operating temperature range (including
(including as low as -40 °C) can maintain relatively high ductility and toughness materials.
The second method is to evaluate the fracture resistance of ferritic steels by testing material toughness indicators such as the non-plastic transition temperature.
The third method is to use the theory of fracture mechanics to evaluate the fracture resistance of the structure.
The first two methods are guidelines based only on material testing requirements, and it is necessary to demonstrate that certain material parameters (such as impact absorbed energy) are not lower than their allowable limits.
value, the material has good toughness. The third method is based on the fracture mechanics method and is applicable to all materials, requiring justification of calculated transport
There is a sufficient margin between the stress intensity factor of the container containment system and the measured fracture toughness of the material.
4.3 Other alternative methods can be used in actual work, but their rationality should be demonstrated.
5 Exemption conditions for brittle fracture prevention evaluation
5.1 When designing and selecting materials, select them under the normal transport conditions and transport accident conditions specified in GB 11806, and within the required operating temperature range.
Materials capable of maintaining high ductility and toughness in the range (including down to -40 °C), such as austenitic stainless steels, are exempt from brittle fracture evaluation.
5.2 For cast austenitic stainless steel, the evaluation of brittle fracture resistance cannot be exempted, and the mechanical test described in 6.2 shall prove that it has sufficient
ductility and fracture toughness.
6 Method for evaluating ferritic steel by material toughness index such as non-plastic transition temperature
6.1 Overview
The basis for determining the non-plastic transition temperature is to determine a temperature at which the standard drop weight test will not occur at the welded joint.
Brittle fracture. 6.2 provides methods for evaluating ferritic steels based on impact absorbed energy or lateral expansion values, and 6.3 provides methods for evaluating ferritic steels based on nonplastic transformation.
Any method of temperature evaluation of ferritic steel can be used. This method is applicable to the evaluation of base metals for transport containers, as well as welds and thermal
Evaluation of the affected area.
6.2 Evaluation method using impact absorbed energy or lateral expansion value as acceptance index
For ferritic steels (including bolts), a large number of impact absorbed energy (Charpy V-notch impact test) and fracture toughness relationships have been established
database, shock absorption energy can be used as an indirect indicator of material toughness. It is based on the determination of the plastic-free transition temperature method, and the acceptance criteria are
The impact absorbed energy (or lateral expansion value) measured by the Charpy V-notch impact test at the specified temperature is greater than the limit specified in the standard. at low temperature
The impact absorption energy limit below can refer to the corresponding standard, and the temperature should include at least the required operating temperature range (including as low as -40 ℃).
6.3 Evaluation method using plastic-free transition temperature as acceptance index
6.3.1 Evaluation basis
This chapter specifies the fracture toughness evaluation criteria to be met by ferritic steels of different package grades and different section thicknesses. None of the materials required by the guidelines
The minimum temperature difference between the plastic transition temperature and the lowest service temperature (-40 °C) under accident conditions is a function of section thickness. The temperature difference is no
Based on the relationship between plastic transition temperature and fracture toughness. 6.3 Evaluation of brittle fracture resistance applicable to type B package containment systems, type C packages may
The evaluation shall be carried out with reference to the Type B package level I, and other packages other than the Type B or C package may be evaluated with reference to the Type B package level III, or according to
Evaluate according to other standards such as GB 150.The failure theory used for the combined stress of the Class I containment system of the Type B package is the maximum shear stress theory, which controls
The control stress is the stress intensity; the failure theory used for the combined stress of the B-type package Class II and Class III containment system is the maximum stress theory, and the control should be
The force is the first principal stress. The stress analysis in Chapter 7 can be carried out with reference to this article.
6.3.2 Evaluation criteria for ferritic steels with nominal wall thickness less than 100 mm
Type B packages are classified according to the different activity levels of the radioactive contents in the package. The classification principles are shown in Table 1.Level I requires
Each sample of the containment system shall be subjected to a fracture toughness test, and the evaluation results shall meet the evaluation criteria of grade I, see Table 2; grades II and III can be
Carry out the test or refer to the corresponding standard data, and the evaluation results should meet the evaluation criteria of the corresponding level, see Table 3 and Table 4.The key components are
Refers to a component that penetrates or ruptures the containment system of a shipping container due to fracture failure.
6.3.3 Evaluation criteria for ferritic steels with a nominal wall thickness of 100 mm to 300 mm
Under the required service temperature (including as low as -40 ℃), the non-plastic transformation temperature TNDT of ferritic steel measured according to GB/T 6803
Should not exceed the limits determined in Table 5.
7 Methods of evaluating fracture resistance using fracture mechanics theory
7.1 Overview
The method is based on linear elastic fracture mechanics and is applicable to all engineering materials. Linear elastic fracture mechanics is the use of the linear theory of elasticity to
The cracked parts are subjected to mechanical analysis, and the characteristic parameters such as stress intensity factor are obtained as evaluation indicators to judge whether the component fails.
7.2 Calculation of stress intensity factor
The calculation formula of stress intensity factor based on linear elastic fracture mechanics is.
7.3 Criteria for brittle fracture prevention
The brittle fracture prevention criterion based on linear elastic fracture mechanics is.
Under normal transportation conditions, the safety factor should be √10; under the condition of transportation accident, the safety factor should be √2.The minimum security in formula (2)
The full factor should use the load parameters and assume an upper limit for defect size and a lower limit for fracture toughness. The safety factor should be selected and justified by the package designer
is reasonable, and the package designer should consider confirming the confidence level of stress analysis methods (such as finite element analysis procedures), dispersion of material properties
The safety factor should be accepted by the competent authority.
7.4 Evaluation Process
7.4.1 General steps
The evaluation process proceeds as follows.
a) assume a reference defect at the critical part of the transport container and in the direction perpendicular to the maximum principal stress;
b) Calculate the stress of the transport container in the mechanical test under the normal transport conditions and transport accident conditions specified in GB 11806, and ensure that
The various load combinations required have been considered;
c) Calculate the stress intensity factor of the reference crack tip;
d) determine the lower limit of the fracture toughness of the material at the loading rate that the transport container may be subjected to;
e) under the relevant loading conditions, calculate the ratio of the applied net section stress to the yield strength;
f) The safety margin between the stress intensity factor and the fracture toughness of the material, as well as the safety margin between the applied stress and the yield strength, shall be
Ensure that unstable crack propagation or brittle fracture will not be caused by the mechanical tests specified in GB 11806.
Steps b) and f) can also be verified by mechanical tests.
7.4.2 Considerations
7.4.2.1 Defect assumptions
Three different defect sizes are mentioned in this standard. "reference defect size" is the assumed defect size used for analysis; "rejection defect size"
inch" is the defect size found in pre-service inspection that does not meet the quality control requirements; "critical defect size" refers to the design basis load condition
The size of the defect that would cause a potentially unstable expansion.
Whether it is analytical demonstration or experimental verification, the reference defect should be set on the surface of the containment system of the shipping container, where the stress is
The largest on the inclusive system. If the shipping container is subjected to cyclic or pulsating loads, the possibility of in-service fatigue crack propagation should be considered. when the most
When the location of the large stress is uncertain, multiple arguments are required. The orientation of the reference defect shall be such that the maximum surface stress determined by calculation or experimental test
The components are perpendicular to the plane of the defect. Reference defect size should be related to volumetric inspection sensitivity, inspection uncertainty, reject defect size, and critical
Defect size is adapted.
The reference defect shape should be a semi-elliptical shape with an aspect ratio (ie length to depth) of 6.1 or greater. Reference defect at maximum stress
The projected area of the direction shall be greater than the limit for rejection or repair of typical defects in the vessel wall during pre-service inspection. When artificial defects are used for experimental verification
When possible, the tip of the artificial defect shall be as crack-like as possible and have a reference crack confirmed by the designer of the transport container and accepted by the competent authority.
The sharpness of the tip of the pattern. For ductile iron, it is recommended that the radius of the fillet of the crack tip be no greater than 0.1 mm.
Reference defect sizes for ferritic steels are shown in Table 6.Under the premise of ensuring that the defect can be detected and guaranteeing a certain safety margin, it can be assumed that a smaller
Defect size is used for evaluation.
7.4.2.2 NDT
Appropriate non-destructive testing methods should be selected in the design of shipping containers, and surface and volumetric testing should be carried out in accordance with standard procedures. surface inspection
Magnetic particle inspection, liquid penetrant inspection or eddy current inspection can be used; radiographic inspection or ultrasonic inspection can be used for volume inspection. If using the reference
concept and methods based on fracture mechanics, the designer of the transport container must demonstrate that the prescribed nondestructive testing method is sufficiently sensitive,
to ensure that any such defects can be detected.
The designer should consider the possibility of defect initiation or propagation and the possible degradation of in-service material to determine the requirement for periodic non-destructive testing.
7.4.2.3 Stress calculation or testing
The calculation of the stress intensity factor for the tip of the reference defect shall be based on the maximum tensile stress in the critical component. Stress should be transported through to defect-free
Container calculation to determine. The stress is the stress caused by the external force at the defect position in the defect-free shipping container, and is called the nominal stress.
If the finite element analysis method is used, the finite element model must be adjusted to give accurate results for every detection point and attitude in the critical area.
When the stress field is inferred from a surface strain test (scale model or performance test of a full-scale shipping container), the inferred stress field
It should also be justified. When the strain tester is used in the stress-concentrated area, the error of measuring point arrangement or the influence of the length of the strain gauge should be considered.
can cause measurement errors.
Using dynamic finite element analysis should meet the following conditions.
a) a computer program capable of analyzing shock events;
b) use reliable or conservative mechanical property parameters;
c) The model is accurate or conservatively simplified.
When deriving stress from test results, the tester characteristics, test location, and rationale for data conversion should be considered.
Stress evaluation also needs to consider the dynamic and structural properties of the material.
7.4.2.4 Determination of fracture toughness
The method for determining the fracture toughness of the material shall be selected from the three options shown in Figure 4.
Option 1 shall be the minimum value determined by testing the fracture toughness of the specific material at -40°C. It represents a limited number of supplies from material suppliers
Quantities of samples were obtained and a statistically significant set of data was obtained under appropriate loading rates and geometric constraints. For a particular shipping container, the sample should be
when representative.
Option 2 shall be determined according to the lower limit of the fracture toughness of the material. As a limit case, this option includes the ferritic steels specified in the standard
Fracture toughness test. The lower limit can be based on synthetic data on static, dynamic and arrest fracture toughness. By referring to the lower limit
(or near the lower limit) curve to simplify the testing procedure for the material. The appropriate number of data points should be sufficient to demonstrate that the curve is
Applicability of batch numbers.
Option 3 shall be based on the statistical fracture toughness data of static loading rate and crack tip restraint meeting the requirements of the GB/T 4161 standard.
Small value, or test fracture toughness based on elastic-plastic method (GB/T 21143 can be used). Linear elastic breaking force according to GB/T 4161
The test temperature for the chemical test should be at least -40 °C, but a lower temperature can also be selected to meet the test conditions of GB/T 4161.use bombs
Fracture toughness testing by plastic fracture mechanics should be performed at the lowest service temperature.
The first two options should include materials representing the loading rate or strain rate, temperature, and constraints (such as thickness) applied to the actual shipping package
fracture toughness. For plane strain conditions, statically loaded fracture toughness KIC or JIC is suitable for many Type B packages of large thickness. also,
The dynamic fracture toughness KId at high loading rates or impact conditions may, for some materials, be significantly lower than the corresponding values at the same temperature
Static fracture toughness KIC.
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