摘要
Chinese regulatory authorities are placing increasing emphasis on radiation safety at prospective nuclear power plants (NPPs) throughout their operational lifetimes. Therefore, investigating source-term migration and the resulting impact following a potential breach of a long-distance liquid effluent discharge pipeline during the site selection phase is imperative. In this study, soil samples collected from 4.85 to 5.00 m depth in three boreholes near a proposed NPP site were utilized to examine diffusion behavior under variable environmental conditions and to simulate solute transport of 90 Sr and 60 Co. The results revealed that decreasing initial source-term concentrations and increasing groundwater ionic strength both reduce the capacity factor ( alpha ) and the effective diffusion coefficient ( De ). Sr(II) and SO 42- tend to form surface complexes and accumulate at the albite-water interface, whereas Co(II) can diffuse through pores and interlayer spaces of montmorillonite. Kd values derived from diffusion experiment fittings do not reflect actual adsorption capacities, rendering them unsuitable as input parameters for solute transport models. Hence, Kd values obtained from adsorption experiments and De values from through-diffusion experiments were used to predict the migration of Sr(II) and Co(II). The study indicates that the radiological impact of 90 Sr and 60 Co on groundwater will remain below World Health Organization (WHO) drinking-water quality standards provided that pipeline repair is implemented within 60 days of a leakage incident. This research provides critical data for long-term risk management at the proposed nuclear power plant and for the protection of the surrounding environment in China.