Automated Non-Destructive Corrosion Detection for Savy Container Surveillance

SAVY containers are prone to interior corrosion while in use. Non-destructive testing (NDT) for corrosion within SAVY containers will augment current container monitoring procedures. Ultrasonic wall-thickness testing (UT) and eddy current array (ECA) flaw detection were chosen following a feasibility study and consultation with industry experts. UT testing can measure loss in wall thickness as well as signal attenuation due to pitting. ECA uses electromagnetic induction to detect surface and subsurface flaws.

To understand the capabilities and instrumental response of each technology, several test samples were created using 316L stainless steel plates with the same thickness as SAVY containers. In a collaboration with New Mexico Tech, 316L plates were corroded to varying degrees with HCl and FeCl3 in controlled conditions. A custom calibration plate was machined with indentations of varying diameters and depths to simulate different levels of pitting corrosion. Finally, two corroded SAVY containers and a control were made available for testing by the container management team in NPI-2. Each of these different samples were used to determine the accuracy of UT wall thickness measurements, the smallest pit detectable by UT and ECA analysis, and the limitations of each technology.

UT and ECA testing will complement each other in an automated inspection system to generate a color-coded plots of the interior of each container. This data will enable rapid visual inspection and flaw detection, with each container serving as its own control. An automated NDT system will reduce the amount of time workers are in radiation areas, increasing worker safety as well as surveillance cycle efficiency. More frequent surveillance of at-risk containers, creation of a detailed record of each container, and long-term data collection for lifetime certifications will be possible.