Abstract
An inspection of a flaw of a helical heating tube installed in a fast breeder reactor MONJU in Japan is operated by a feeding of an eddy current testing (ECT) probe with magnetic sensor into the tube. An undesirable vibration of the ECT probe always happens under a certain condition and makes the inspection difficult. Several characteristics of the vibration have been clear through some experiments by using a mock-up. However, an essential factor of the vibration is still unclear. In this paper, the motion of the probe is described in a polar coordinate along the helical tube and a numerical simulation of the vibration is implemented on the assumption that the vibration is caused by the Coulomb's friction. The results of simulation qualitatively agree well with the experimental results. It confirms the validity of the assumption that the vibration is caused by the Coulomb's friction.
