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

ハルバッハ磁石配列の電磁超音波探傷による炉心支持構造物の検査に関する提案

山口 智彦 ; Mihalache, O. 

Yamaguchi, Toshihiko; Mihalache, O.

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) sensor 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 was enhanced using a combination of EMAT sensor 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.