Measurement of 90Sr in aqueous samples using liquid scintillation counting with full spectrum DPM method

90Sr activity was measured with the full spectrum DPM (FS-DPM) counting method after plotting the quench correction curves of 90Sr and 90Y, and the FS-DPM method was applied to determine the 90Sr in liquid waste samples. The optimum regions of 90Sr and 90Y were set for measuring 90Sr with the dual label DPM (DL-DPM) method. The direct measurement of purified 90Sr with spectrum unfolding techniques could overcome the disadvantages of the DL-DPM method. The activities of 90Sr in the 90Sr/90Y standardized solution measured with the FS-DPM protocols were close to the true activity. The concentrations of 90Sr in the liquid waste samples measured with the FS-DPM counting method were compared with those obtained with conventional methods.