Natural Radioactivity of Some Selected Economic Minerals from Quarry Sites in Igarra Area, Edo State, Nigeria

Abstract

Activity concentrations of radionuclides in rocks and minerals are of vital importance in geosciences and health physics especially that primordial radionuclides 226Ra, 232Th and 40K constitute the main source of radiation exposure risks externally in soil, rocks and minerals.In this study, activity concentrations of 226Ra, 232Th and 40K in three economic minerals were evaluated using gamma ray spectrometric technique. Mean activity concentrations of 226Ra, 232Th and 40K were 3.15, 1.85, 291.59Bq/kg in dolomite, 1.01, 0.78, 197.89Bq/kg in feldspar and 5.41, 4.02, 427.03Bq/kg in calcite respectively. Computed average absorbed dose rate at 1m above ground and annual effective dose equivalent were 14.73, 9.19, 22.73nGy/h and 0.02, 0.01, 0.03mSv/y respectively for dolomite, feldspar and calcite. Other computed hazard indices for the studied economic minerals were below their respective safety limits stipulated in the UNSCEAR report.