Abstract: A submerged ultrasonic viewer for use in a liquid metal cooled fast reactor vessel to detect floated reactor core components. The viewer, which includes an ultrasonic transducer, a transducer scanning drive mechanism and a related electrical control circuit, an image display circuit, and a reflecting surface, i.e. a handling head of a core element or a reflecting plate, is improved to enhance image accuracy by providing the reflecting surface with at least one continuously curved surface having a convex or a concave contour, or plural continuously curved surfaces with concave and convex contours.