Study of Well Waters from High-Level Natural Radiation Areas in Northern Vietnam

The determination of natural radionuclide concentrations plays an important role for assuring public health and in the estimation of the radiological hazards. This is especially true for high level radiation areas. In this study, ²²⁶Ra, ²²⁸Ra and ²³⁸U concentrations were measured in well waters surrounding eight of the high-level natural radiation areas in northern Vietnam. The ²²⁶Ra, ²²⁸Ra and ²³⁸U activity concentrations vary from <1.2 × 10^-3-2.7 (0.46), <2.6 × 10^-3-0.43 (0.07) and <38 × 10^-3-5.32 Bq/L (0.50 of median), respectively. ²²⁶Ra and ²³⁸U isotopes in most areas are in equilibrium, except for the DT-Thai Nguyen area. The calculated radiological hazard indices are generally higher than WHO (World Health Organization) recommendations. Average annual effective dose and excess lifetime cancer risk values due to drinking well water range from to 130 to 540 μSv/year and 7.4 × 10^-6 to 3.1 × 10^-5, respectively.