Sampling and Determination of ~(14)C in Air

摘要

The sampling and monitoring of ~(14)C activity in air is usually performed in common mode; a catalyst converter which insures that the ~(14)C in forms other than CO_2 in sampling air flow is oxidized to ~(14)CO_2 , followed by a capture device based on solid ascarite media or liquid NaOH alkaili solution. For LS counting, the sample preparation is complicated and consume-time through acidification of the ascarite media sample and cocktail absorption. For capture of CO_2 in NaOH solution, The method for counting ~(14)C as CaCO_3 in a liquid scintillator is widely used in environment monitoring, because the procedure for sample preparation is rather simple and requires no expensive equipment. Though general method of counting solid in a liquid scintillator is know to be very accurate, This method shows his good long term stability and reproducibility of different samples in addition to satisfactory counting efficiency and large sample quantity. Based on these considerations, a simple sampling and determination method of ~(14)C in air is developed by CIRP and applied to monitor ~(14)C activity in air around nuclear facilities in China.