Determination of the radiological health indexes of using natural kaolin

Abstract

Kaolin (China clay) is used for various purposes such as in the manufacture of fine porcelain, pottery making, paper industry etc and is thus a valuable geological material. A qualitative and quantitative determination of the natural radionuclides contained in samples obtained from Delta State Nigeria was carried out using a well - calibrated highly efficient NaI(TL) detector. The consequent radiological health indexes were then calculated. The radionuclides detected belong to the ²³⁸U and ²³²Th decay and the non series ⁴⁰K. The mean specific activities of ²²⁶Ra, ²²⁸Ra and ⁴⁰K varied from 95.3 - 96.3, 99.7 – 99.9 and 537.2 – 543.6 Bqkg^-1 respectively. These levels are slightly higher than corresponding values obtained by other investigators elsewhere not in Nigeria. Radium-equivalent activity was found to be 280.3 Bqkg^-1 The external hazard index is 0.76 while the mean annual effective dose equivalent is 0.16 mSvy^-1 . Since the hazard index is less than unity and the determined dose equivalent is below the internationally recommended limit of 1mSvy^-1 for members of the public, it is concluded that the use of natural kaolin of Nigerian origin does not pose any radiological effect of consequence

Keywords: Nigerian kaolin, wide applications, radiologically friendly