Investigation of bubble size and mass transfer rate in a scrubbing solution used for iodine removal

A Nuclear Power Plant has major concern of ensuring its safety in terms of release of radioactivity into the atmosphere. Over-pressurization caused by decay heat generation in a core melt accident might damage the reactor containment. Filtered Containment Venting System (FCVS) is being introduced which meets the main requirements of limiting the excessive pressure buildup in the containment, maintaining the structural integrity of the containment and retaining the activity present in gas that is vented into the atmosphere. The iodine laden containment air is vented through the scrubber, where it is treated with caustic soda and other additives. The vented air is bubbled through the solution and the reaction of the iodine and the solution takes place on the bubble surface. For having larger decontamination factors, bubble dynamics is extremely important in scrubber type FCVS design. The present study includes the use of video imaging to measure bubble size in a specially designed scrubbing column which is used for supporting the results obtained by using correlations developed by different researchers in their studies and hence finding the mass transfer rates. It is deduced that the transfer rate is more in case of concentrated solution and mass transfer rate increases with the increase in head of the scrubbing solution. It can be seen in all cases that the transfer rate curves converge towards equilibrium as the solution gets saturated.