Calibration and measurement of 210Pb using two independent techniques

An experimental procedure has been developed for a rapid and accurate determination of the activity concentration of 210Pb in sediments by liquid scintillation counting (LSC). Additionally, an alternative technique using γ-spectrometry and Monte Carlo simulation has been developed. A radiochemical procedure, based on radium and barium sulphates co-precipitation have been applied to isolate the Pb-isotopes. 210Pb activity measurements were done in a low background scintillation spectrometer Quantulus 1220. A calibration of the liquid scintillation spectrometer, including its α/β discrimination system, has been made, in order to minimize background and, additionally, some improvements are suggested for the calculation of the 210Pb activity concentration, taking into account that 210Pb counting efficiency cannot be accurately determined. Therefore, the use of an effective radiochemical yield, which can be empirically evaluated, is proposed. 210Pb activity concentration in riverbed sediments from an area affected by NORM wastes has been determined using both the proposed method. Results using γ-spectrometry and LSC are compared to the results obtained following indirect α-spectrometry (210Po) method