Guidedwave is employing its patented guided wave phased array (GWPA) technology for the inspection of Hanford double-shell tank (DST) primary liner floors. The GWPA technology utilizes an array of specialized shear ring transducers to perform rapid 360-degree scans of plate-like structures of up to 100 square feet from a single probe position in a matter of seconds. The technique yields easy-to-interpret two-dimensional images for rapid detection and localization of various flaws in both the floor plates and the welds. Guidedwave’s proprietary software includes tools for automatically filtering out imaging artifacts and quickly generating composite images composed of GWPA data from multiple scan locations for even easier data interpretation. The Sensor Effectiveness Testing at PNNL in June 2017 yielded excellent GWPA results. Guidedwave approached the testing by performing GWPA scans on a predetermined sparse grid of data collection locations. The composite GWPA result clearly indicates nearly all the flaws in a single image. On the individual GWPA scans, the average signal-to-noise ratio for the detected flaws was 31 dB. Furthermore, it was demonstrated that surface corrosion and dust contamination had negligible impacts on performance. Potential challenges of robotic GWPA deployment were also considered, including probe size reduction and probe deployment. A dry coupling technique was developed to remove the burden of remotely deploying shear couplant on the test surface. The GWPA probes are rugged and water-resistant, and they do not require magnets, manual rotation, or extensive scanning like many EMAT technologies. The GWPA technology would provide an efficient, accurate, and easy-to-interpret inspection solution for the Hanford DST primary liner floors.
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