Non-destructive Evaluation of Nuclear Fuel Rods Using Ultrasonic Resonance Phenomena

摘要

A new technique using the ultrasonic resonance phenomenon has been developed for the detection of the infiltrated water inside failed fuel rods as well as for the determination of oxide layer thickness. The resonance spectrum corresponding to the first order antisymmetric circumferential wave is theoretically analyzed and experimentally measured. In failed fuel rods, the resonance of cladding tubes disappears and the resonance of pellets can be negligible. Analytical results show that the phase velocity of the first order antisymmetric circumferential wave does not change, regardless of the presence of an oxide layer This fact has been experimentally confirmed and applied to the measurement of oxide layer thickness.