Fast Three-dimensional Finite Element Simulation In Eddy Current Testing Of Defects In Steam Generator Tubes

Nuclear energy is accepted as safe clean efficient sources of energy. So nuclear power plant is popular in an increasing number of countries. Steam generator is an important component of the nuclear power plant. Because of the existence of defects in tube, nuclear power plant is often shut down in order to maintain it. Sometimes defects lead to nuclear power plant accident. Therefore, it is very meaningful and necessary to study the flaws in tube.These defects are usually very small. If finite element method is only used, the model must be meshed enough, considering the skin effect and In order to achieve engineering precision. It will spend a huge amount of calculation and a considerable computing time. Sometimes general computer simply can not complete it. So, in this paper the use of the finite element method and analytical method are combined with. The field is first calculated when no flaws exist. Then a three-dimensional perturbation model, including defects and a part of tube and air. The conversion value of the field when no flaws exist is loaded as a source to the perturbation model. Cycle control and data interchange are implemented by using APDL. Finally, the coil impedance is calculated, through the use of Superposition method. The simulation result shows that the method in this paper is correct.The relationships among the coil impedance, phase angle and the diameter, depth of the defects, as well as factors such as the frequency of the detection, are analyzed in this paper. These contribute to the identification of defects.