Determination of interphase in refilled columns using radioactive sources

This study consisted in the determination of interphase in a PVC column (φ inner. = 11,5 cm and wall thickness = 7 mm), refilled with material of different densities at different heights. It was placed inside a support PVC pipe of 2 meters length and 16,5 cm of diameter to which a gamma scanning with a source-detector system (Cs-137 of 10 μCi as sealed source and a NaI scintillation detector) moved by a step motor (velocity = 6,6 cm/s) was performed. The refill consisted of sand and gravel, fine gravel, clay, gross gravel, fine sand, air and water. This experience was performed under two conditions: 2 measurements per second and 5 measures per second. It is concluded that the technique applied to estimate bed heights and interfaces in columns by using radioactive sources is very effective and that effectiveness increases as more measures are performed. (orig.)