A CFD-based approach to optimize operating parameters of a flow-through scintillation cell for measurement of 220 Rn in indoor environments

The measurements and monitoring of 222 Rn/ 220 Rn have been of emerging interest in occupational environments particularly in radium/thorium handling facilities and environments with monazite deposits for the inhalation dosimetry. The performance of a flow-through Lucas scintillation cell (LSC) for long run 220 Rn measurements, depends upon the exact distribution pattern of 220 Rn and its decay products in the LSC which can vary with the design of inlet path and flow rates. In this work, the CFD technique has been used to study the concentration profiles of 220 Rn and its decay products in LSC for varying flow rates and inlet needle lengths. The variation of alpha production efficiency ( η α ) is computed and analyzed for each case; aiming to select the best operating range of parameters for the optimum performance of LSC for 220 Rn measurements. It is seen that LSC can be operated in the flow rate ranging from 0.6 to 1 lpm with inlet needle length varying from 22.5 to 45 mm for improved sensitivity.