Evaluation of U, Th, K and emanated radon in some NORM and TENORM samples

Abstract

Activity concentrations of 226Ra (of U-series), 228Ra (of Th-series) and potassium ( 40K) in some heavy minerals and building materials were determined and evaluated in some selected heavy mineral sands and building materials. Three heavy mineral sands (monazite, zircon and black sand) of industrial interest were used. Building materials used here include phosphogypsum (PG) wastes, natural gypsum, ceramics, granite, marble, cement and iron slag wastes associated with iron and steel production. The measurements were carried out using γ -ray spectrometry. The activity concentrations varied widely depending on sample origin. The results indicated that the high activity levels, radium equivalent activity, absorbed-gamma dose rate and effective annual dose rate were found in monazite, zircon and PG wastes as compared to the other materials. The mean activity concentrations in monazite were 40580 ± 1370 , 182425 ± 9870 and 11300 ± 9570 Bq kg - 1 for 238U, 232Th and 40K, respectively. This activity is equivalent to 0.39, 5.1 and 4.5 wt% for uranium as U 3 O 8 , thorium as ThO 2 and potassium-40 as K 2 O , respectively. The radium equivalent activity, absorbed-gamma dose rate and effective annual dose rate in monazite were 3.0 × 10 5 Bq kg - 1 , 1.3 × 10 5 nGy h - 1 and 163 mSv yr - 1 , respectively. The emanation coefficient (EC) of 222Rn was less than 20%. The average Rn EC was 18% for cement samples and ∼ 14 % for granite and ceramic samples. It concluded that the Rosetta beach could be considered a valuable source for some metallurgical processes of industrial interest, but with special precautions. Most of the studied building materials can be used without restrictions except PG wastes, granite and ceramic.