Automated Real-Time Eddy Current Array Inspection of Nuclear Assets

Area of Science:

• Materials Science and Engineering
• Non-Destructive Testing (NDT)
• Robotics and Automation

Background:

• Volumetric NDT methods struggle with surface discontinuities.
• Industry demands reliable surface-defect detection for component longevity and sustainability.
• Industry 4.0 drives the need for robotic NDT solutions.

Purpose of the Study:

• To present the novel implementation of a flexible robotic cell for eddy current testing (ECT).
• To inspect stress corrosion cracking on a nuclear canister using an eddy current array.
• To demonstrate innovative methods for minimizing lift-off variation and enhancing data processing.

Main Methods:

• Utilized a flexible robotic cell to deliver an eddy current array for inspecting a 1.4404 stainless steel nuclear canister.
• Acquired axial and transversal impedance data at multiple frequencies (250-450 kHz) during 180-degree scans.
• Implemented a force-torque sensor, padded array, and PI control to minimize lift-off variation.
• Employed bespoke software for real-time data logging, display, and post-processing including phase rotation and data mixing.

Main Results:

• Successfully inspected stress corrosion cracking on the nuclear canister.
• Phase rotation increased Signal to Noise Ratio (SNR) by an average of 4.53 dB.
• Data mixing techniques further improved SNR by an average of 1.19 dB.
• Demonstrated repeatable and flexible surface inspection capabilities.

Conclusions:

• Robotic delivery of eddy current arrays enables efficient and reliable surface inspection.
• Innovative post-processing techniques significantly enhance defect detection and characterization.
• This approach is suitable for quality-focused industries seeking to improve component integrity and sustainability.