GB/T 34641-2017 in English
VALIDNon-destructive testing - Test method for determining image quality in direct thermal neutron radiographic examination
- Issued on:2017-09-29
- Implemented on:2018-04-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$156.00
《GB/T 34641-2017无损检测 直接热中子照相检测的像质测定方法》由TC56（全国无损检测标准化技术委员会）归口，主管部门为国家标准化管理委员会。
Introduction
1. Background and significance of the standard
GB/T 34641-2017 "Image Quality Determination Method for Direct Thermal Neutron Radiography for Nondestructive Testing" is a standard proposed and managed by the National Technical Committee for Standardization of Nondestructive Testing. The main drafting units include the Institute of Nuclear Physics and Chemistry of the China Academy of Engineering Physics, Beijing Institute of Aeronautical Materials and other authoritative institutions. The formulation of this standard aims to standardize the technical requirements of direct thermal neutron radiography testing, ensure the consistency and accuracy of the test results, and provide a reliable basis for quality control in related industries.
2. Overview of the main contents of the standard
| Chapter | Main Content |
|---|---|
| Chapter 1 | Scope: Specifies the image quality determination method for direct thermal neutron radiography testing, including the method overview, significance and purpose. |
| Chapter 2 | Normative References: Lists relevant standards that must be referenced, such as GB/T 12604.8 and GB/T 31362. |
| Chapter 3 | Terms and Definitions: Detailed explanation of key terms such as Image Quality Indicator (IQI), Beam Purity Indicator (BPI) and Sensitivity Indicator (SI). |
| Chapter 4 | Method Summary: Introduces the basic process of direct thermal neutron radiography detection, including the use of image quality indicators and image analysis methods. |
3. Core Technical Indicators and Requirements
Beam Purity Indicator (BPI): Used to quantitatively evaluate the quality of neutron beams, including polytetrafluoroethylene blocks, boron nitride discs, lead discs and cadmium rods. By measuring the optical density, parameters such as effective thermal neutron content and scattered neutron content can be obtained.
Sensitivity Indicator (SI): Used to measure the detail sensitivity of neutron radiographic images, it is composed of a stepped wedge containing holes and gaps of known size. The minimum detectable aperture and gap can be determined by visual analysis.
4. Detection Process and Quality Assessment
| Detection Steps and Requirements | |
|---|---|
| The direction of the beam | should be perpendicular to the film surface to ensure image clarity. |
| The image quality meter is placed | to be exposed together with the object being tested, with an edge distance of no less than 25mm to avoid image overlap. |
| Optical density measurement | Use an optical densitometer, and the black meter reading error should be less than ±0.02 density units. |
| Image quality level | Determine the classification according to Table 4, with priority given to the contrast evaluation results. |
5. Implementation suggestions and precautions
Implementation suggestions:
- Strictly follow the test process specified in the standard to ensure that the equipment and environmental conditions meet the requirements.
- Regularly calibrate the instrument and equipment to ensure measurement accuracy.
- Record and save the test results for at least three years or as specified in the contract.
Notes:
- In special cases (such as when the sample is too large), alternative methods can be used and ensure consistency with the standard.
- If abnormal results are found during the test, the cause should be analyzed in time and corrective measures should be taken.
- Pay attention to the measurement of the uniformity of the beam and ensure that the optical density range meets the requirements.
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