Year
1998
Abstract
Tanks in nuclear facilities are typically equipped with bubbler probe systems to measure liquid content. When gas is forced through the probe until bubbling occurs, the height of liquid in the tank above the tip of the probe can be determined from the pressure it exerts at the tip, by means of the Archimedean Principle. Pressure is measured at a gauge which is generally located some distance above the tip of the probe, and therefore the measured pressure differs somewhat from the tip pressure. Other factors that result in differences between the measured pressure and the actual pressure at the tip of the probe include temperature changes, air buoyancy, the mass of gas in the probe lines, flow resistance, and the effects of bubble formation and release at the tip of the probe. Although each factor contributes to the uncertainty of a particular height determination, there has been no comprehensive study of the relative magnitudes of these contributions. In this paper, we present the results of a systematic simulation study conducted to provide this information. The plant operator or inspector can use these results to make informed decisions about which factors contribute enough to overall uncertainty to justify their measurement.