Radioactivity Concentrations of ³H and ¹³⁷Cs in Coastal Groundwater in Korea

Abstract The activities of tritium (³H) and cesium-137 (¹³⁷Cs) were measured in coastal brine groundwater and groundwater in the Republic of Korea to establish baseline data relevant to evaluating potential effects associated with the discharge of ALPS-treated water from the Fukushima Daiichi Nuclear Power Station. Tritium activities in the brine groundwater samples ranged from 1.29 to 9.05 TU (0.15–1.07 Bq/L), whereas ¹³⁷Cs activities were below the sample-specific detection limits (1.82–2.86 mBq/L). The low ¹³⁷Cs activities are consistent with the potential retention of cesium by soil and rock during seawater infiltration; however, the present data do not independently quantify the extent of this retention. These measurements provide baseline data for future monitoring.