面向核容器及管路的不锈钢内壁缺陷涡流检测工艺

Eddy Current Testing Technology for Inner Wall Defects of StainlessSteel for Nuclear Vessel and Pipeline

针对大厚度不锈钢核容器及管路在放射环境下易从内壁产生腐蚀缺陷,并向外壁扩展直至产生表面泄漏的问题,需要采用适合的无损检测手段进行在役监测,保证服役安全。涡流检测方法具有不引入额外介质、易于实现自动化等优点,可满足典型核容器的特殊检测要求。为更好地检测核容器内壁缺陷,设计了专用涡流检测装置,搭建了以机器人为载体的涡流自动检测系统,通过提取阻抗图幅值、相位、包络面积及与x轴交点最大值作为表征涡流检测阻抗图的几何特征参数,开展了不同缺陷深度的模拟试样涡流检测研究。结果表明:设计的系统能对距上表面6 mm以内的缺陷做出有效响应;幅值、包络面积、与x轴交点最大值三个特征参数能很好地反应缺陷深度信息,而相位特征参数随深度增大呈无规律变化。

In view of the problem that the large thickness stainless steel nuclear vessel and pipeline are easy to produce corrosion defects from the inner wall and expand to the outer wall until surface leakage in the radiation environment,suitable nondestructive testing means should be used for in-service monitoring to ensure service safety.The eddy current testing method has the advantages of no additional medium,easy to realize automation,and etc.,which can meet the special testing requirements of typical nuclear vessels.In order to better detect the inner wall defects of the nuclear container,a special eddy current detection device is designed,and an eddy current automatic detection system based on robot is built.By extracting the amplitude,phase,the envelope area and the maximum value of the intersection with the x-axis are used as the geometric characteristic parameters of the eddy current testing impedance diagram and the eddy current testing of simulated samples with different defect depths is carried out.The results show that:the designed experimental system can effectively respond to defects within 6mm from the upper surface;the three characteristic parameters of amplitude,envelope area and the maximum value of intersection with x-axis can well reflect the defect depth information,while the phase characteristic parameters change irregularly with the increase of depth.