Feasibility Test of Ultrasonic Waveguide Sensor Assembly for Under-Sodium Viewing in Sodium-cooled Fast Reactor

The visual inspection of reactor internal structures should be applied in accordance with the ASME XI Division 3 which contains the rules and guidelines for an in-service inspection (ISI) of a sodium-cooled fast reactor (SFR). As liquid sodium is opaque to light, a conventional visual inspection can not be used for observing the internal structures under a sodium level. Under-sodium ultrasonic inspection has been widely developed for an in-service inspection of the reactor internal components and structures of SFR. Recently a new ultrasonic waveguide sensor has been developed. The waveguide sensor visualization technology is to have an ultrasonic transducer over the reactor head and a transmission of the ultrasonic waves using some specific waveguides still in the hot sodium. In this study, the ultrasonic waveguide sensor assembly has been designed and manufactured. Propagation characteristics of the ultrasonic wave in the waveguide sensor are evaluated. Under-water C-scan imaging tests are carried out to confirm the feasibility of the ultrasonic waveguide sensor