Results of Blind Testing for the Program to Assess the Reliability of Emerging Nondestructive Techniques (NUREG/CR-7235)
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Manuscript Completed: February 2016
Date Published: June 2017
R. M. Meyer and P. G. Heasler
Pacific Northwest National Laboratory
P.O. Box 999
Richland, WA 99352
I. Prokofiev and B. Lin, NRC Project Managers
NRC Job Code V6286
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington DC 20555-0001
The U.S. Nuclear Regulatory Commission (NRC) has established the Program to Assess the Reliability of Emerging Nondestructive Techniques (PARENT) whose goal was to investigate the performance of current emerging and perspective novel nondestructive examination (NDE) procedures and techniques to find flaws in nickel-alloy welds and base materials. This was performed by conducting a series of open and blind international round-robin tests on a set of nickel alloy piping components that include large-bore dissimilar metal welds (LBDMW), small-bore dissimilar metal welds (SBDMW), and bottom-mounted instrumentation (BMI) penetration welds. The project was divided into open and blind testing portions for the purpose of separating the evaluation of novel techniques that are at a stage of relative immaturity for field testing and which were implemented by teams that may not have significant experience in conducting field examinations (open testing) from the evaluation of more established techniques implemented by commercial inspection vendors (blind testing). The objective of blind testing was to address a cross-cutting need identified as a goal by all international collaborators of PARENT to obtain quantitative estimates of the performance of the latest nondestructive evaluation inspection techniques used commercially in the field for detection and accurate sizing of primary water stress corrosion cracks (PWSCC) or interdendritic stress corrosion cracks (IDSCC). The data generated by this effort provides empirical bases that can support regulatory positions and which can inform analyses of the effectiveness of NDE and in-service inspection, more generally, by each country based on each country's specific laws, codes, standards, and regulations.
PARENT was a follow-on to the Program for Inspection of Nickel Alloy Components (PINC), which was based on the Bilateral International Agreements with participants and the in-kind contribution of resources from organizations of Finland, Japan, Republic of Korea, Sweden, and the United States of America to evaluate several nondestructive techniques for detection and characterization of PWSCC and IDSCC in SBDMW and BMI components. In February 2012, the NRC conducted new agreements with VTT Technical Research Centre of Finland, Nuclear Regulation Authority of Japan, Korea Institute of Nuclear Safety, Swedish Radiation Safety Authority, and Swiss Federal Nuclear Safety Inspectorate to establish PARENT to conduct a series of round-robin tests on SBDMWs, BMIs, and LBDMWs. In PARENT blind testing, inspections were performed on two SBDMWs, six LBDMWs, five BMIs, and one weld overlay test block. All of the simulated flaws in SBDMWs and LBDMWs were cracks; mostly tightened solidification cracks and a few laboratory-grown SCC flaws. The inspection procedures employed in blind testing included combinations and variations of conventional ultrasonic testing (UT), phased-array UT (PAUT), UT time-of-flight diffraction (TOFD), and eddy current testing techniques.
Round-robin testing was performed in PARENT to build on the experience in PINC. Whereas PINC obtained data for SBDMW components, PARENT obtained data from both SBDMW and LBDMW components so that an estimate in the difference in performance for each type of component could be obtained and to obtain estimates of performance for techniques applied to the inner diameter (I.D.) and outer diameter (O.D.) surfaces of LBDMWs. In PARENT, LBDMW and SBDMW test blocks had near ideal surface conditions. Thus, the results obtained from these test blocks provide a quantitative measure of performance that can be achieved by I.D. access of components with I.D. surface preparation, relative to performance that can be achieved by O.D. surface access.
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