The development of liquid surface visualization and void detection system for sodium; Imaging characteristic examination of sound propagation simulation and underwater basic test

Hayashida, Hitoshi ; Hirabayashi, Masaru

On the FBR plant, it is necessary that cover gas would not involve in the primary coolant, and especially the measures is very important in order to compact the reactor on the design of DFBR. Thus the behavior of free liquid surface must be evaluated in sodium pool tests at the design phase. And also from the viewpoint of safety analyses, the void detection system which measure the void in the reactor vessel inlet piping is also developed as a measurement system for confirming that the void has not been entrapped in the coolant. Then on the liquid surface visualization system which image the behavior of liquid sodium surface and the void detection system which image the detected void using the ultrasonic wave, the sound propagation simulations and the underwater basic tests were carried out to obtain a knowledge on the basic imaging characteristics. As a first step, the sound propagation simulations were carried out to evaluate the imaging characteristics of the vortex model. As the next step, the measurement system was produced tentatively in order to image the fluctuating liquid surface and the rising void in the underwater basic tests. The signals from some ultrasonic transducers to image them were processed by the cross correlation method and the aperture synthesis method. However the imaging processed in off-line because of the limitation of thc signal processing ability. As the results, it was confirmed that the vortex model could be imaged by the sound propagation simulations. And the fluctuating liquid surface and the rising void could be also imaged by the measurement system in the underwater basic tests. However since the slope of vortex can't be imaged well, the most suitable arrangement of the transducers will be examined to image the slope. And it will be necessary for the measurement system to confirm that the size and shape of void can be imaged accurately.