The article describes the introduction of highly sensitive methods for determining the activity of radium isotopes in drinking water and an example of using these methods to assess the doses of exposure of Kyiv residents to natural radionuclides in artesian water.

An α/β-liquid scintillation spectrometer and the γ-spectrometer with a semiconductor detector were used to measure ²²⁶Ra, ²²⁸Ra, and the sum of uranium isotopes (∑U). A characteristic feature of the implemented methods is their simplicity – a minimum number of technological operations. Available ion-exchange resins and materials were used to concentrate radium and manufacture the columns. The amount of uranium isotopes was determined by liquid scintillation counting after uranium extraction with a tributyl phosphate solution in ortho-xylene. Dose estimates were made regarding the lifetime dose received, considering age-dependent doses and relevant weighting factors. 

We studied 25 samples of artesian water collected in Kyiv from artesian wells and pump rooms. The specific activity of ²²⁸Ra in the studied samples ranges from 7 mBq/l to 99 mBq/l. These values correspond to an accumulated lifetime dose of 6 μSv to 90 μSv per year, which for different sources can be from 79.2% to 97.5% of the total dose, considering the intake of uranium and radium in drinking water.