Dept. of Nuclear Engineering, Chosun University, Seosuk-Dong, Kwangiu, Republic of Korea

Beta radiation is measured for an environmental monitoring purpose or for an internal radiation exposure monitoring of nuclear power plant’s workers. In Korea, strontium-89 and strontium-90 is measured for an environmental monitoring purpose. Also tritium and carbon-14 contained in urine are measured for an internal radiation exposure monitoring of nuclear power plant’s worker.

Because above mentioned isotopes emit low energy beta rays having a wide range spectrum shape, very complicated isotope separation preprocess is needed, Up to now, strontium-89 and strontium-90 is separated using a series of complicated chemical processes. In case of tritium and carbon-14 in urine, discrimination window is used to determine the existence of carbon-14 in urine. If there exists meaningful amount of carbon-14 in urine, a complicated separation process is used to separate tritium and carbon-14.

In this study, two mixed beta emitting isotopes are measured simultaneously using a liquid scintillation counter(LSC) and analyzed by a statistical method using reference spectrum. Least square method is used to analyze the mixed spectrum, and c ² test is used to determine the good fitness of the separated spectrum to reference spectrum. Some test results show that the developed procedure can be very useful for analyzing a mixed beta emitting isotopes sample.