Compared with other methods for measuring radioactivity in water, liquid scintillation measurement has the outstanding advantages of fast sample pretreatment, simple measurement method and high detection efficiency. Based on liquid scintillation spectrometer (SIM-MAX LSA3000B), 14C and 90Sr-90Y are selected as typical nuclides to study the change of TDCR quenching correction curve under different activity concentrations, and the basic method for measuring radioactive water samples with different activity concentrations is proposed, which is applied to the measurement of lake water, mountain spring water, tap water, mineral water and rainwater. The measurement results show that the total time of this method is less than 60 minutes, and the measurement error is less than 20%, which is obviously superior to the existing water sample radioactivity measurement method under nuclear emergency conditions.

In this paper, the basic characteristics of the output pulse waveforms of α and β particles from liquid scintillation detection are analyzed, and the basic principles, advantages and disadvantages of the typical waveform discrimination algorithms are also analyzed comparatively. Meanwhile by using of Matlab, the output pulses of α and β particles from liquid scintillation detection are simulated, the α/β waveform discrimination effect of charge comparison method, pulse gradient analysis method, frequency gradient analysis method and discrete Fourier method are studied. From the simulation results in this paper, frequency gradient analysis method has acquired the best discrimination effect and far exceeds the existing discrimination methods, which can provide an important reference for discriminating α and β particles in liquid scintillation detection.