Achievement of RFEC effects in the nuclear fuel rod inspection by using shielded encircling coils

摘要

Au encircling remote field eddy current (RFEC) probe is designed to inspect the nuclear fuel rod. The exciter coil is shielded to force the electromagnetic energy to penetrate into the rod, and the sensor coil is also shielded to avoid direct influence from exciter fields. The operating frequency and effects of shielding are studied by the finite element analysis and the location for the sensor coil is decided. Numerical simulation with the designed probe shows similar signal characteristics to those of inner diameter RFEC probe. The signals show almost equal sensitivity to inner diameter and outer diameter defects, and the linear relationship between phase signal strength and defect depth is observed.