Evaluation of SAFT/T-SAFT Technology for the Inspection of Hanford's Double Shell Waste Tank Knuckle Regions

Abstract

Priated in the UNted States of America.--.-.- PNNL-13321 Summary 'The need to examine the knuckle region of Hanford's double shell tanks has received considerable attention over the last few months. Commercial, off-the-shelf systems to examine the knuckle are not available. Preliminary tests at the Pacific Northwest National Laboratory (PNNL) in FY 1999 indicated that a technology utilizing ultrasonics could provide a solution to the knuckle examination problem. In FY 2000 PNNL embarked on a study to provide evidence that the ultrasonic technology had the capability to detect and size stress corrosion cracks in the knuckle region of the double shell tanks.Analysis of the examination results conducted at PNNL provide engineering data strongly supporting a proof-of-principle concept for utilizing a combination of pulse-echo Synthetic Aperture Focusing Technique (SAFT) and tandem-SAIT (T-SAFT) inspection methodologies. These methods can be applied to the problem of flaw detection, localization, and sizing in Hanford's double shell waste tank knuckle region and beyond.The work described in this report includes a successful demonstration of the 70°shear wave inspection technique for detection and localization of reflectors in two different geometrical cases. In the first case, that of a flat plate, results showed that the inspection protocol on a 25.4-mm thick carbon steel plate over distances ranging from approximately 889 mm to 1067 mm provided an effective method for examination. In the second case, that of a mockup of the double shell tank knuckle region, results clearly indicate that the inspection protocol was capable of detecting, localizing and sizing of machined reflectors under more realistic conditions.In the case of the flat plate, signal response amplitudes varied with the addition of weldment geometry between the transmitting transducer and machined reflectors. Enhancements provided by SAFT processing appear to provide an effective means for analyzing those signal response amplitudes and developing an optimized inspection protocol for the knuckle region and beyond. Data acquired from examinations in the laboratory show that the inspection technique is capable of detecting and localizing machined reflectors of the order of 5.1 mm deep, from long path lengths and through a weld.In the case of the mock-up examinations, data clearly indicated the successful demonstration of the 70°she&wave inspection technique for detection and localization of reflectors in a more realistic configuration. Once again, signal response amplitudes . varied with the addition of the knuckle geometry curvature between the transmitting transducer and machined reflectors; however, enhancements provided by SAFI' processing provided the means to compensate for these adverse conditions. The additional capability of utilizing T-SAFI' for improved depth sizing of the machined reflectors was shown in this work as well.. . . 111-.-----. PNNL-13321The examination frequency of 3.5 megahertz (MHz) provided good resolution and suitable penetra...

Development of a Remotely Operated NDE System for Inspection of Hanford's Double Shell Waste Tank Knuckle Regions

“…Test results from the new RONDE mockups are reported in Section 9 of this document. The imaging software was tested on raw and PNNL-13682 focused files that were collected in PNNL's preliminary testing stage [Pardini 2000] and are discussed in sections 8.3 and 8.4. The focusing code takes as its input, a raw data file in the SAFT-99 format.…”