Real-time imaging of immersed fuel-sub assemblies using multi-channel ultrasonic camera

The novel circular-array based real-time ultrasonic imaging technique using an ultrasonic camera has been proposed in this paper for imaging of a fuel sub-assembly (FSA) of a fast breeder reactor. The developed ultrasonic camera-based system provides real-time images of the top-head region of the FSA in a high-temperature environment. For the circular-array based ultrasonic imaging, the entire circular-array has been divided into the various arcs, and the address-based analog multiplexing scheme has been proposed in such a way that all channels of the specific arc are selected concurrently (transducer excitation, data acquisition, and data processing and transferring). Various data processing algorithms are proposed and implemented for multi-channel ultrasonic data processing in real-time. For the experimentation, the complete 18-channel ultrasonic camera system has been designed, developed, and evaluated in the laboratory. The performance evaluation of the developed circular-array based ultrasonic camera has been shown by acquiring the real-time images of the water-immersed dummy FSA in elevated temperature. Furthermore, both qualitative visualization and quantitative measurements of growth and bowing of the FSA top-head are presented.