New approach for the detection of defects in the core support structure of SFRs using EMAT based on a Halbach magnet

This paper investigated a new method based on a combination of electromagnetic and ultrasonic sensors for inspecting the core support structure of the reactor vessel in sodium-cooled fast reactors from a position located outside of the vessel. Using an electromagnetic acoustic transducer (EMAT) with a Halbach magnet, the feasibility of the detection of the defects in the reactor core support structure was investigated via experimental measurements using a reduced half-scale mock-up model in a sodium-free environment. The amplitude of the signal from various small slits (5 %tw-20 %tw) was enhanced using a combination of EMAT geometry, Halbach magnet configuration, and signal processing methodology in view of increasing the signal-to-noise ratio when the EMAT continuously scanned the area of interest for defects deep inside the metallic structure.