Research On Computed Radiography Technology Using Ir192 Radioactive Source

In order to ensure manufacturing quality and safety of nuclear facilities, radiographic testing is absolutely necessary in every stage of nuclear power station construction, such as manufacturing, installation, pre-service and in-service inspection. Welding is an important method for the construction of a nuclear facility and the quality of welded joints has a significant impact on the quality and reliability of nuclear facilities construction and installation. In today’s nuclear power construction process, the conventional radiography is still a main method to test weld quality.Computed radiography(CR) technology is a kind of digital acquisition technology of radiographed image. It is a non-film digital radiography technology, which has been developed rapidly in recent years. Compared with conventional radiographic testing technology, CR technology stores images by fluorescent imaging plate(IP) instead of film, realizing the digitization of radiographic image and embodying the characteristics of digital radiography testing.Based on the practical application of radiographic testing using Ir192(Iridium) radioactive source in nuclear power station construction, the feasibility of application of computer radiography technology in nuclear power station construction was surveyed. Darkness is a particularly important parameter in the radiographic testing, but in the digital film image, traditional darkness is replaced by the gray-scale value. In this paper, the validation block was designed and the best darkness scope was studied, which laid a foundation for following study. Sensitivity is the most important technical index of radiographic image quality. In order to determine the influence of various parameters on the sensitivity, experimental research was conducted respectively on exposure, scanning precision, and intensity of photomultiplier tube. The best value ranges of the above parameters were obtained by experiment, which provide a basis for digital radiography inspection process.Lastly, after working out the digital radiographic testing process, the selected block containing defects was tested by conventional radiographic testing using isotope source and digital radiographic technology respectively. The test results were compared, and it was concluded that the digital radiographic testing technology is feasible and can satisfy the existing nuclear testing standards, providing a basis for the field application of the digital radiographic technology.