Progress in developments of an EMAT based on a Halbach magnet system for FBR vessel

Article type: Research Article

Authors: Yamaguchi, Toshihiko^a; | Mihalache, Ovidiu^a | Ueda, Masashi^a

Affiliations: [a] Japan Atomic Energy Agency, Sector of Fast Reactor Research and Development, Tsuruga-shi, Fukui-ken, Japan

Correspondence: [*] Corresponding author: Toshihiko Yamaguchi, Japan Atomic Energy Agency, Sector of Fast Reactor Research and Development, 1 Shiraki, Tsuruga-shi, Fukui-ken, 919-1279, Japan. Tel.: +81 (0) 770 39 1031; E-mail: yamaguchi.toshihiko@jaea.go.jp

Abstract: The paper presents the progress in the developments of an electro-magnetic acoustic transducer (EMAT) based on a Halbach magnet system optimized for detection of defects in thick plates with application to the inspection of fast breeder reactors (FBR) vessel. The defects are located either far or near weld lines in austenitic stainless steel plates (50 mm thick), on the opposite plate side where are located the EMAT sensors. Performance of single or double units EMATs are investigated for working in industrial conditions with very long cables (up to 45 m). Experimental measurements are focused on an increased signal/noise ratio for detection of signal from defects located near weld lines of FBR vessel. A fast and novel way of EMAT measurements and signal processing (named dynamic scanning) is introduced and its performance is confirmed for austenitic stainless steel plate defects with depths ranging from 5% to 50% from the plate thickness.

Keywords: Fast breeder reactor vessel, austenitic steel, EMAT, welds, C-scan

DOI: 10.3233/JAE-171226

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1469-1477, 2019