Enhanced Flaw Detection by Time-Reversal Auto-Focusing of an Ultrasonic Array

112 Enhanced Flaw Detection by Time-Reversal Auto-Focusing of an Ultrasonic Array--Foster-Miller, Inc., 350 Second Avenue, Waltham, MA 02154-1196; (617) 684-4239 Mr. Curt Brockelman, Principal Investigator Mr. Adi R. Guzdar, Business Official DOE Grant No. DE-FG02-97ER82379 Amount: $74,988 Stress corrosion cracking is a major problem in nuclear powerplants because it affects many components in both pressurized water reactors and boiling water reactors. The very tight cracks associated with stress corrosion cracking have proven very difficult to detect by either eddy current or ultrasonic testing. The time reversal mirror is a novel auto-focusing technique for an ultrasonic phased array, achieved in real time, that can compensate for distortions caused by irregular interfaces and discriminate flaws in speckle noise fields. The effectiveness of this technique has been demonstrated in the laboratory on titanium billets, another difficult inspection task. This project will apply time reversal mirror technology to improve early detection of stress corrosion cracking in the core support structures of boiling water reactor vessels. The project will evaluate the effectiveness of the time reversal process for improving defect detection in core shroud welds H-7, H-8, and H-9, by using mock-ups of a core support plate and a core shroud. The inspection results achieved with an ultrasonic array and the time reversal auto-focusing technique will be compared to those achieved by alternative inspection technologies. In the Phase II project, custom array probes will be developed for field demonstration of reactor vessel inspection and additional inspection tasks in both nuclear and fossil powerplants identified for application of time reversed ultrasonic phased-array techniques Commercial Applications and Other Benefits as described by the awardee: The application of the time reversal mirror technique has the potential to substantially improve inspection quality and to reduce inspection cost. The improved inspection quality will result in more knowledge of the structural integrity of important vessel internal components and critical piping, which will enhance its operational safety margin. The reduced cost will result from the increased inspection speed believed to be attainable with the approach.