Study for differential pressure measurement by dip-tubes. 1. Bubble formation and analysis method of differential pressure data

The experimental facility including the mock-up input accountancy tank for Rokkasho reprocessing plant has been under construction at the Nuclear Material Control Center. The Preliminary experiments related to bubble formation and differential pressure waveform on the dip-tubes have been investigating by means of simple bubble-probe system. Based upon pressure balance at a phase boundary between air and solution, the mathematical bubble formation model was employed considering the dip-tube's tip shape, solution density, surface tension and contact angle of dip-tube and solution. The results from the numerical solution of the model agreed well with differential pressure waveform measured experimentally. Hence, the model is suitable to simulate a bubble formation process and to predict a differential pressure waveform on a dip-tube in a solution. Furthermore, various kinds of experiments, such as the evaluation of dip-tube's tip level and the effect of dip-tube tilt in a solution, were conducted; the results suggest that the measured differential pressure value must be corrected considering the property of the solution and the state of the dip-tube in order to obtain the true level of the solution. (author)