Corrosion Shape Identification in Nuclear Reactor Tube Using Inverse Applied Electromagnetic Analysis

利用磁测量数据成功地进行了核反应堆管道腐蚀形态识别的研究。结合计算力学反分析的背景知识，提出了适用于核反应堆炉管定量无损评价的估算算法。首先，基于麦克斯韦方程组建立了磁检测过程的精确数学模型。同时，腐蚀形状被归类为一类几何结构，并通过适当的基函数近似。其次，利用非线性优化的思想，包括正则化技术，灵敏度分析和遗传算法等，提出了计算方案来估计样品材料中的腐蚀形状。提出的算法进行了测试与模拟数据和实验室数据。所得结果如下：（1）磁反分析 ...更多信息 L曲线法求解：通过测量磁通密度，本文考虑的反问题旨在恢复涡流矢量势。由于该问题的不适定性，提出了正则化技术，称为L-曲线方法。(2)裂纹深度重构的参数估计：以蒸汽发生器炉管涡流检测为背景，研究了裂纹深度重构方法的反问题。利用有限元-边界元混合方法描述的探头阻抗轨迹可以检测材料缺陷。提出了一种用于裂纹深度形状重建的参数估计方法。实验结果与实验室数据进行了成功的测试。(3)使用遗传算法的材料退化：开发了一种用于估计磁性材料内部空隙的位置和数量的逆计算算法。最后，采用遗传算法验证了该算法的可行性.少

Research has been successfully implemented for corrosion shape identification in nuclear reactor tubes with magnetic measurement data. With the background knowledge of inverse analysis in computational mechanics, feasible estimation algorithms have been proposed for quantitative nondestructive evaluations related to nuclear reactor tubes. First, the magnetic inspection process was described by the precise mathematical model based on Maxwell's equations. Simultaneously, corrosion shapes were categorized into some class of geometrical structures and approximated by appropriate bases functions. Secondly, computational schemes were doveloped for estimating the corrosion shape in sample materials using the ideas of nonlinear optimizations, including the regularization techniques, the sensitivity analysis and the genetic algorithm, etc. Proposed algorithms were tested both with simulation data and with laboratory data. Results obtained here are summarized as follows :(1) Magnetic Inverse Ana … More lysis by L-curve Approach : Measuring magnetic flux densities, the inverse problem considered here was aimed at recovering the eddy current vector potentials. Since this problem becomes ill-posed, the regularization technique which is called L-curve method was proposed.(2) Parameter Estimation for Crack Depth Reconstruction : Motivated by eddy current inspection for steam generator tubes, inverse problems of crack depth reconstruction method were considered. Material flaws can be detected using a probe impedance trajectory which is described by hybrid FEM-BEM scheme. A parameter estimation method was presented for reconstructing the shape of the crack depth. Results of experiments with laboratory data were successfully tested.(3) Material Degradation using Genetic Algorithm : An inverse computational algorithm was developed for estimating the location and number of voids inside magnetic materials. The genetic algorithm was used in order to demonstrate the feasibility of the proposed algorithm. Less