Screening LSC method for monitoring 14C activity in water samples

This paper explores the possibility of a direct measurement of 14C activity concentration in water samples without chemical pretreatment of samples. A method via Liquid Scintillation Counting (LSC) technique has been implemented and optimized. The method assumes mixing of water sample with a scintillation cocktail. Permafluor E+ and Ultima Gold AB cocktails were tested. Polyethylene vials were selected since they induce lower background count rate than glass vials. Measurements were performed on Ultra Low Level LSC Quantulus 1220. Optimization of the method included optimar water:cocktail volume ratio and optimal coounting window selection as well as PAC parameter adjustment, based on the highest FOM value achieved. Quench level parameter has been monitored for all samples while counting. Detection efficiency and detection limit were determined as the main parameters for method's evaluation. The presented method is ultrafast, simple and inexpensive test for the efficient screening of water samples that could be used for 14C monitoring purposes in the case of nuclear emergency. Its application is limited to samples with much higher 14C activities than those of the environmental surface and ground waters.