Radioactivity in local and imported kaolin types used in Egypt.

Natural radioactive materials are present in all geological rocks in varying amounts, they are easily mobilized in the environment, and can reach hazardous radiological levels under certain conditions, requiring precautions to be taken. The present study deals with 50 geological samples of local (Tushki and Kalabsha in upper Egypt) and imported (southeast Asia and Turkey) kaolin types. The samples were analyzed by gamma-ray spectroscopy using a HPGe detector. The activity concentrations of 232Th and 238U series and 40K and the contents (in ppm) are given. The radium equivalent activity varied from 187.8 to 10185.19 Bq/kg. 137Cs was found in a range of 0.23-8.5 Bq/kg, for the local samples. The kaolin in Tushki area was suitable for industrial use.