| Nuclear power is one of the cleanest energy sources recognized by the industry in the world.Compared with traditional thermal power,nuclear power does not cause SO2,NO,NO2 and other greenhouse gases,which is of great significance for reducing acid rain and the greenhouse effect in nature.Nuclear fuel rods are the main components in nuclear reactors and their performance is directly related to the safety of nuclear power plants.Normally,the nuclear fuel rods need to be placed in service under conditions of high temperature,high pressure,and strong neutrons,and their quality will directly affect the safe operation of nuclear reactors.After the reform and opening up,the processing and manufacturing processes of nuclear fuel rods developed rapidly.However,there are still many imperfections.Nuclear fuel rods manufactured and produced still exhibit common defects such as pits,wrinkles,pores,and inclusions with a small probability.In ensuring all the properties of the nuclear fuel rod,the weld between the cladding and the end plug is the most vulnerable part of the entire nuclear fuel rod structure,and the detection of its common defects needs to be the most stringent.Non-destructive testing is one of the most commonly used methods for quality evaluation.Ultrasonic testing,as an important member of non-destructive testing,has high detection accuracy,strong detection capability,and low cost,and can help inspecting personnel to identify nuclear fuel rods through ultrasonic imaging.The defect size,defect location,in addition,the image processing can be used to comprehensively evaluate the nuclear fuel rod mechanical properties and surface quality.This subject adopts the ultrasonic detection method,which can realize the qualitative analysis and quantitative analysis of the common defects of the end plug welding of nuclear fuel rods,and can provide constructive guidance for the improvement of the processing technology of nuclear fuel rods.This project was developed under the national key R&D project(2016YFF0203000),the National Natural Science Foundation of China(No.51675258,51261024),and the Jiangxi Provincial Department of Education Science andTechnology Research Project(GJJ150699),to address the common defects of end plug welds on nuclear fuel rods.A multi-angle ultrasonic probe imaging system for multiple probe detection of nuclear fuel rods.The system analyzes and processes multi-channel detection of full-wave train signals and visualizes the quality of end plug welds of nuclear fuel rods through intuitive feature maps.The software system can form an inspection image with the amplitude or phase as the characteristic parameters in an intuitive manner,and help the inspection personnel to accurately evaluate the quality of the end plug weld of the nuclear fuel rod.The quantitative accuracy of the detection system can reach 0.2mm,and the resolution can reach 0.01 mm.The detection system has a detection equivalent of ?0.2mm for holes and 3% of wall thickness for cracks.Such detection capability is due to the independent research and development of high-performance ultrasonic probe holders and high-precision mechanical scanning systems to ensure the stability and accuracy of detection.The paper is mainly divided into three parts.The first part mainly discusses the detection features and detection scheme of the ultrasonic feature scanning of the end plug welds of nuclear fuel rods,and develops corresponding high-performance ultrasonics for the detection of defects in the weld region of nuclear fuel rod end plugs.Transducer.First,in order to achieve the purpose of detection,the overall scheme of the system is proposed,including the mechatronics scheme and the ultrasonic excitation receiving scheme.Secondly,the conventional parameters of ultrasonic testing are designed according to the structural characteristics and detection requirements of the workpiece,the transverse wave detection is selected,and the spherical wafer is selected.The manufactured geometric focusing probe was used for detection and other important parameters such as the incident angle were also designed.The detection scheme of the artificial defect test block was proposed later;the specific ultrasonic transducer was developed and tested for the program.The test result was Satisfaction,sensitivity and GE probe difference is only 2dB.In the second part,the design of the mechanical system of the detection system and the electrical system and software system of the ultrasonic detection system are described in detail,which help to complete the automatic detection of nuclear fuel rod ultrasonic imaging.This part of the design and production of a plug end seam ultrasound scanning imaging system,mainly from the mechanical design point of view,the overall mechanical device to do a program;In order to reduce the interference ofelectrical signals,the device uses pneumatic transmission,can be completed Each action,from the point of view of the power source and based on the scanning characteristics,designs the three transmission circulatory systems of the horizontal,vertical and rotational directions.In addition,in order to ensure the coaxiality of the nuclear fuel rods in the inspection process,a clamping device needs to be designed;The interference of the detection system is relatively large.This system uses a specially designed coupling liquid circulation system;finally,for common defects of the end plug weld,the probe needs to be arranged at different incident angles,and then a high-precision adjustable probe head is developed.Detect defects more effectively to prevent missed detection and false detection.The third part is mainly the experimental results and analysis.By testing the manufactured standard test bars with artificial defects,the test system's detection ability and detection accuracy are verified.This section tests the nuclear fuel rod end plug weld man-made defects;first prepare the artificial defect test block for testing,use different electrodes for different defect types to prepare;follow-up inspection of artificial defects of girth welding and seal welding,The detection image is saved after detection,and the feature scanning and imaging tomography technology is used for analysis and processing.The detection result is ideal and the system basically meets the detection requirements. |
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