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

Abstract

The need to examine the knuckle region of Hanford's double shell tanks (DSTs) has received considerable attention over the past couple of years. 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 unique 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 DSTs. Analysis of the examination results conducted at PNNL in FY2000 provided engineering data strongly supporting a proof-of-principle concept for utilizing a combination of pulseecho Synthetic Aperture Focusing Technique (SAFT) and tandem-SAFT (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.

High Frequency Guided Wave Virtual Array SAFT

“…Results similar to Fig. (12) are reported in [4] using a single transducer positioned at a distance of 72 inches.…”

“…In work reported last year, a computational model was developed to predict and explain the complex signal features displayed by the signals received in this measurement. [1,2] In that work, it was seen that the signals consist of numerous discrete components, corresponding to varying numbers of multiple reflections between the shell walls. It was also seen how shell curvature complicates signal interpretation by introducing tangential incidence shadow boundaries, and focusing caustics due to "whispering gallery" modes of propagation at near-grazing incidence.…”

RONDE Ultrasonic Examination of Double-Shell Tank 241-AP-101 Knuckle Region Examination Completed April 2003

“…COGEMA Engineering Corporation (COGEMA), under a contract from CH2M Hill Hanford Group (CH2M Hill), has performed an ultrasonic examination (UT) of selected portions of Double-Shell Tank (DST) 241-AP-101 utilizing the Remotely Operated Nondestructive Examination (RONDE) system (also known as the SAFT/TSAFT system) (Pardini et al 2001). The purpose of this examination was to provide information that could be used to evaluate the integrity of the knuckle region of the DST.…”

Ultrasonic Examination of Double-Shell Tank 214-AW-102 Knuckle Region. Examination completed February 2003

“…COGEMA Engineering Corporation (COGEMA), under a contract from CH2M Hill Hanford Group (CH2M Hill), has performed an ultrasonic examination (UT) of selected portions of Double-Shell Tank (DST) 241-AW-102 utilizing the Remotely Operated Nondestructive Examination (RONDE) system (also known as the SAFT/TSAFT system) (Pardini et al 2001). The purpose of this examination was to provide information that could be used to evaluate the integrity of the knuckle region of the DST.…”