Electromagnetic acoustic transducers for nondestructive inspection of dry storage canisters for used nuclear fuel

Inspection for stress corrosion cracking in stainless steel canisters that store used nuclear fuel must be done within a harsh environment that requires robotic delivery of the sensing system. The system must tolerate high temperatures and radiation and it must operate in constrained spaces. In order to be delivered robotically noncontact transducers are preferred. Electromagnetic acoustic transducers (EMATs) are noncontact transducers that can be made from materials capable of resisting high temperature and radiation and therefore are an excellent choice for this application. This presentation will describe the requirements of the dry storage environment, the ability of compact EMATs to detect cracks oriented both transverse and parallel to the wave vector using shear horizontal guided waves, and the nondestructive inspection methodology developed for full penetration weld regions. Laboratory experiments indicate that the pulse-echo mode is effective at detecting crack-like notches. B-scans constructed from the heat affected zone of welds show both the defects and the welds, which are distinguishable by their time-of-flight.