Abstract

This paper presents the study of natural radioactivity in Tanzania Portland cements and their raw materials. Samples collected as raw materials were pozzolan, sandstone, limestone, clay, gypsum and cement as finished products. The natural radioactivity due to the presence of radium ²²⁶Ra, thorium ²³²Th and potassium ⁴⁰K were measured by means of gamma spectrometer coupled with HPGe detector. The mean measured activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the raw materials range from 2.6 to 93.2, 1.3 to 172.8 and 6.3 to 997 Bq/kg, respectively with higher activity concentrations in pozzolan and lower in gypsum. Activity concentrations of natural radionuclides in raw materials (excluding some materials from Songwe deposits in Mbeya region) are comparative with the worldwide average concentrations of these radionuclides in soil. The average activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in the cements are 46, 28 and 228 Bq/kg, respectively. The calculated values of radiological indices are below 60% of the upper recommended values for building materials. The average annual effective dose to an occupant from use of these materials equals to 0.45 mSv. Average activity concentrations of the mentioned radionuclides in Tanzania cements are in the middle of the variability interval of the national averages.

Keywords:

Annual effective dose, building materials, gamma-ray spectrometry, radium equivalent, radiation hazard,

References

Competing interests

The authors have no competing interests.

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The authors have no competing interests.