Assessment of the activity of radionuclides and radiological impacts of consuming underground water in Kumasi, Ghana

Abstract

The gross α–β activities of ²²⁶Ra, ²³²Th and ⁴⁰K in underground water samples were determined and γ spectroscopy measurements made as well. The gross α–β concentrations were measured using a low background gasless automatic α–β counting system calibrated with ²⁴¹Am and ⁹⁰Sr standards for α and β, respectively, while γ analyses were carried out using γ spectrometry system coupled to a NaI (TI) detector and measuring assembly. Gross α activities in the water samples varied from 15.7 to 142.7 mBq/L, registering an average value of 40.7 ± 12 mBq/L, whereas gross β activities ranged from 89.3 to 400 mBq/L. The activities of ²²⁶Ra, ²³²Th and ⁴⁰K were 22.41 ± 6.07, 114.62 ± 13.01 and 227.38 ± 12.16 mBq/L, respectively. The mean annual effective dose due to water consumption was determined to be 7.00 ± 0.86 µSv/year per inhabitant. The gross α–β levels, the activities obtained for the three radionuclides and the annual effective dose were all within the WHO safe limits. This study indicates that underground water in the areas sampled is radiologically safe for consumption.