An approach to develop real-time in-situ underwater monitoring system based on integrated beta and gamma detection

Abstract

A real-time in-situ monitoring system for detecting beta and gamma nuclides underwater was proposed, and basic characteristic experiments were conducted. The current radiation monitoring system in Korea for lowenergy beta nuclides uses liquid scintillation counting (LSC), which is time consuming and not recommended for rapid responses to uncontrolled releases. An integrated monitoring system comprising two scintillators (NaI(Tl) and plastic) was proposed and analyzed. This system exhibited gamma and beta detection efficiencies of 2.51 +/- 0.025 % and 8.00 +/- 0.08 %, respectively, for the 137Cs and 90Sr disk sources. The coincidence net count rates of 90Sr from 90Sr + 137Cs were 578.00 +/- 0.58 and 577.06 +/- 0.77 cps, respectively. The system revealed a relative difference of 0.40 %, which eliminated the effect of gamma nuclide, thus providing a methodological basis for distinguishing between underwater beta and gamma nuclides. The results indicated that the present approach could be usefully applied to establish a real-time beta and gamma monitoring system for underwater environments, such as groundwater at decommissioning sites.