Year
1996
Abstract
A Large Scale Tank Calibration (LASTAC) facility, which has an experimental tank with the same volume and structure as the input accountancy tank of the Rokkasho Reprocessing Plant, has been constructed at the Nuclear Material Control Center. Fundamental studies examining dip-tube bubble formation were carried out using a small-sized dMerential pressure measurement unit. It is well known that the pressure waveform from a dip-tube depends on the shape of the dip-tube, the density and the surface tension of the solution, and the contact angle between the dip-tube and the solution. Based on the pressure balance at the air-solution phase boundary, a mathematical bubble formation model was established. The dip-tube pressure waveform can be obtained by continuously solving the model while increasing the purge air volume to the dip-tube. The numerical solution of the model was found to agree well with the differential pressure waveform measured experimentally. Thus, the model is suitable to simulate the bubble formation process and to predict the differential pressure waveform for a dip-tube in a solution. Experiments that varied the purge air flow rate, the dip-tube tilt, and so on, were also conducted. The results suggest that the measured differential pressure value must be corrected to include the properties of the solution and the characteristics and orientation of the dip-tube to obtain the true level of the solution.