Under sodium imaging of SFR internals - Simulation studies in water

Under sodium viewing at high temperatures is an important requirement in sodium cooled fast reactors (SFR) for navigation during structural inspection. USV is also needed to locate and identify loose parts under sodium, when required. Conventionally, ultrasonic imaging is done using XY raster scanning method. However, due to space constraints within the reactor, it may pose limitations. As an alternative, θ-Z scanning can be used. Ultrasonic image of a typical tool, namely pliers, is obtained using both XY raster scan and θ-Z approaches. Specific software with time of flight correction is developed in LabVIEW for θ-Z based imaging. Comparable images were obtained by both the approaches. CIVA simulation study has also been carried out on a specially designed specimen that simulates various geometries present inside a reactor.