Determination of 222Rn by liquid scintillation counter combined with p-xylene extraction technique

222Rn Determination method by liquid scintillation counter after extracting 222Rn with p-xylene was studied. It was confirmed that extraction of 222Rn with p-xylene proceeds quantitatively. Several experimental conditions for the counting such as scintillator content in p-xylene, the quencher effect, the zero level extrapolation method and 3-channel counting method were examined. The recommended procedures were successfully applied to measure 222Rn content in one of the natural water. It was noticed that we should pay attention to 220Rn (Tn) which is simultaneously extracted with 222Rn in case of p-xylene extraction.