Signal processing for coarse-grained materials: Interim report
Reliable ultrasonic inspection of coarse-grained materials, such as cast stainless steel components in the primary piping loop of pressurized water reactors (PWRs) and dissimilar metal welds, has not been satisfactorily demonstrated to the utilities. The inspection for flaws is difficult because strong reflections from the grain boundaries could mask the flaw signal response: in addition, the ultrasonic beam can be redirected by the ''wave guide'' effect of the grain structure. This report discusses signal processing approaches that may be relevant to inspection of such materials. Specifically, spatial averaging - a proven technique for enhancing signals that exhibit spatial coherency - was found to be useful in enhancing signal-to-noise ratio (SNR) for flaws whose lengths were larger than the average grain size. Three specimens of PWR main coolant piping, each a cast steel elbow welded to forged steel containing fatigue flaws, were examined with a personal computer (PC)- based data acquisition and imaging system developed under EPRI funding. In addition, an axial flaw intentionally placed in the Inconel weld of a nozzle-to-safe-end mockup obtained from the canceled Phipps Bend plant was examined. The PC-based system was modified to include software capabilities to perform signal averaging and filtering. The images produced before and after signal processing showed improvements in flaw detectability.
- Research Organization:
- Jones (J.A.) Applied Research Co., Charlotte, NC (USA); Electric Power Research Inst., Palo Alto, CA (USA)
- OSTI ID:
- 6305020
- Report Number(s):
- EPRI-NP-5329; ON: TI87920531; TRN: 87-029980
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
42 ENGINEERING
36 MATERIALS SCIENCE
AUSTENITIC STEELS
ULTRASONIC TESTING
PWR TYPE REACTORS
PRIMARY COOLANT CIRCUITS
REACTOR COMPONENTS
REACTOR MATERIALS
STAINLESS STEELS
CASTING
METALS
WELDED JOINTS
ACOUSTIC TESTING
ALLOYS
CHROMIUM ALLOYS
COOLING SYSTEMS
CORROSION RESISTANT ALLOYS
ELEMENTS
ENERGY SYSTEMS
FABRICATION
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
MATERIALS
MATERIALS TESTING
NONDESTRUCTIVE TESTING
REACTOR COOLING SYSTEMS
REACTORS
STEELS
TESTING
WATER COOLED REACTORS
WATER MODERATED REACTORS
210200* - Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
420500 - Engineering- Materials Testing
360101 - Metals & Alloys- Preparation & Fabrication