Nondestructive Inspection Results from Mockups of Spent Nuclear Fuel Storage Canisters Using Shear-Horizontal Waves Generated by an Electromagnetic Acoustic Transducer

A robotic nondestructive inspection system developed for stainless steel dry storage canisters containing spent nuclear fuel was tested on a range of mockups in order to assess different aspects of the system. The nondestructive inspection was designed to be able to interrogate 100% of the canister weld lines, even if much of the surface is inaccessible because it uses ultrasonic shear-horizontal waves in what is basically a pulse-echo mode. The guided waves are sent and received by electromagnetic acoustic transducers, which are noncontact as well as tolerant of elevated temperature and gamma radiation. The nondestructive inspection targets stress corrosion cracks in the heat-affected zone of welds. The mockups enable determining the reflection and transmission ratios associated with the welds, the detectability of closed crack-like flaws, the detectability of branched cracks, B-scans along a weld line at elevated temperature, and full robotic system deployment. The test results demonstrate that the robotic system meets its functional requirements.