Tritium Concentration in River Water and Groundwater Collected in Rokkasho, Aomori, Japan

In order to study the effect of ³H released from the commercial spent nuclear fuel reprocessing plant on ³H concentration in the local fresh water environment, river water and well water samples were collected at seventeen and nine points, respectively, around the plant. Concentrations of ³H were measured in the samples collected during the period of the final testing using actual spent fuel in the plant. The stable isotope ratios of hydrogen and oxygen in water samples were also measured for a hydrological study around the plant area. Concentrations of ³H in the river water samples were in the background level, and their variation among sampling locations was small. Although well water samples also did not have significantly high ³H concentrations originating from the ³H released from the plant, the variation in ³H concentration among sampling locations was larger than that in the river water samples. Comparison of D and ¹⁸O data with a local meteoric water line suggested that groundwater around the plant area is mainly recharged by precipitation in winter.