September-October 2018 NPJ

Nuclear Plant Journal, September-October 2018 NuclearPlantJournal.com 49 (Continued on page 50) acoustic transmission and receipt of ultrasonic shear waves with linear polarization. Each of the tool’s transducer assemblies consists of a rare-earth magnet, whose magnetic field is perpendicular to the substrate surface, and a shear wave induction coil to initiate the Eddy current perpendicular to the substrate surface. The permanent magnet applies a baseline magnetic field to the induction coil and substrate. The transducer assembly induces ultrasonic waves into the substrate via high- power eddy currents applied to the radio- frequency (RF) coils on the substrate side of the magnet. The elastic forces applied parallel to the material surface initiate shear waves at a specific angle into the substrate. The ultrasonic waves reflect off features and substrate material changes, alerting the inspector to inner diameter (ID) and outer diameter (OD) anomalies as well as mid- wall manufacturing defects. Implementation Preparation for implementation of these inspections began in Winter 2016. The inspection team consisted of the North Anna Underground Pipe and Tank Integrity team members and Diakont field robotics and NDE teammembers. The project represented Diakont’s first service water pipeline inspection at a nuclear facility. Because of the nature of the exams, Dominion Energy and Diakont completed mockup training and EMAT evaluations under the review of one of the station’s NDE Level III engineers at the Diakont facility in San Diego, CA. The Diakont inspection robot is compact enough that North Anna personnel could provide access to each pipeline by removing valves in the valve pit at the end of the cased sections. This ability to enter via existing fixtures relieved North Anna personnel of safety risks inherent to creating pipe entry points (e.g., cutting pipe, shoring digs). North Anna personnel were also able to coordinate Diakont inspection services with planned maintenance on the removed valve assemblies, significantly reducing risks associated with crane and rigging usage. Both inspections finished on time and full volumetric inspections of these sleeved lines permitted 100% coverage for the sleeved portions without the need to perform full pipe excavations. Typically, an inspection of a buried pipe will only excavate and uncover a small sample of the total pipe length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which may miss localized degradation or inadequate installation conditions. Excavations also raise the risk of damaging the buried piping as the piping is exposed for examination. The Diakont EMAT inspection module is installed on one of Diakont’s pipe inspection robots; therefore, no personnel enter the pipe. This eliminates a significant safety concern of having personnel inside the pipe for visual inspections. Innovation The use of the new-to-nuclear EMAT technology mounted on a pipe inspection robot permitted 100% volumetric inspection of these sleeved pipe segments. These volumetric inspections did not require the protective coatings to be removed, nor did the inspections require a couplant. Access to the pipe line is all that was required, and that was done by removing a valve and a spool piece. These two seemingly uninspectable lines were easily examined with a high degree of accuracy utilizing Diakont’s high resolution EMAT probe Site Engineering engaged fossil fuel and natural gas providers in pursuit of a non-destructive