Vincent Mulwa^1,, J.M Linturi¹, Martin Riara¹

Cements contain traces of natural radionuclides because the raw materials originate from the earth’s crust. Elevated levels of natural radioactivity can have harmful health effects on living tissues. This study aimed at establishing the radiological safety of cements used in Kenya by quantifying gamma ray-emitting natural radionuclides present in the cements. A Sodium Iodide Thallium-doped gamma ray spectrometer was used in counting gamma rays emitted by ⁴⁰K and progenies of ²³⁸U and ²³²Th in the selected cement brands. The average activity concentrations and radiation safety indicators of selected cement brands were determined and compared with global averages. The activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K were estimated using gamma-ray photopeak energies of ²¹⁴Pb at 352 KeV, ²¹²Pb at 239KeV and 1460 KeV respectively. The average activity concentrations ²³²Th, ²³⁸U, and ⁴⁰K were found to be 52.70±3.3, 35.88±4.3, and 432.31±50.7 BqKg^-1. The absorbed dose rate of most cement samples was higher than the world average of 59nGhy^-1. Cement class and clinker content determined the amounts of primordial radionuclides. Values of indoor and outdoor hazard indices, annual effective dose rates and radium equivalent activity were within stipulated safety limits. These metrics of radiation hazard indicators were within safety limits, and therefore, there is no significant radiation risk linked to the use and handling of the cements used in Kenya.

gamma rays, radionuclides, radiation safety, activity concentration, cement, absorbed dose, hazard indices