Abstract:Taking an ultra-low background liquid scintillation counter LSC-LB7 as an example, the experimental parameters and measurement methods for measuring tritium activity concentration in environmental water were studied and optimized.The optimized experimental parameters such as dark treatment time and counting window were summarized, which can effectively decrease the detection limit of tritium measurement of water samples by this liquid scintillation counter. The optimized measurements were compared to those with unoptimized parameters, the results showed that biggest relative deviation of 33.87% between the two methods, and that the optimized method was able to reduce the uncertainty of the tritium concentration in water by 50%. With the aim of quenching calibration using the liquid scintillation counter to measure tritium activity concentrations in environmental, a series of self-made standard sources with different degrees of quenching and a consistent tritium activity concentration was counted in a sequence by optimized measuring method, and a quenching calibration curve was created. When the quenching calibration curve was used to measure the environmental water samples and compared with the commercially available standard sources for quenching, it was observed that the actual values were different and the relative deviation is about 11%. Finally, based on the optimized liquid scintillation measurement method and the quenching calibration curve of the self-made standard source, the activity concentration of tritium in the environmental water sample was determined to be (12.21±2.08)Bq/L,k=2.
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