VOID-FRACTION MEASUREMENTS IN A STEADY-STATE MERCURY-NITROGEN FLOW LOOP

A steady-state vertical mercury-nitrogen flow system has been investig ated using three tomographic algorithms. Void-fraction profiles have b een reconstructed by the data collected by a 60 mCi gamma-ray source a nd a single Na(Tl) detector. The results indicate excellent agreement (within +/-1%) between the least-squares-solution and the chord-segmen t-inversion algorithms. The data-collection time for each data-ray was varied so that in each case 3000 counts could be collected to reduce the detrimental effect of Poisson statistics in the reconstructed prof iles. Eleven sets of data have been collected for nitrogen flow-rates between 0.00123 and 0.00884 kg/s. The mercury flow-rates were between 17.6 and 34.1kg/s. The resulting cross-sectional average void varied b etween 0.10 and 0.38.