Window multi-frequency ECT for multi-coils in a RFEC system for FBR SG tubes

Mihalache, O. ; 山口 智彦 ; 白濱 卓馬; 上田 雅司 

Mihalache, O.; Yamaguchi, Toshihiko; Shirahama, Takuma; Ueda, Masashi

The paper presents applications of window multi-frequency algorithms using eddy currents to the in-service inspection of fast breeder reactor (FBR) steam generator (SG) tubes in the presence or absence of sodium. Detection of defects filled with sodium in various percentages are investigated based on three dimensional (3D) finite element (FEM) simulations, using an in-house developed code, of remote field eddy current (RFEC) multi-coil sensors system. Various sources of noises (sodium percentage, sensors lift-off and speed and others) and their impact on the algorithms accuracy is compared with the application to previous measured data of SG tubes in mock-up tanks before and after several sodium draining.