Abstract
The contents of natural radionuclides (Ra-226, Th-232 and K-40) were measured in investigated samples (granite Gabal Ras Barud, Eastern Desert in Egypt) by using gamma spectrometry (NaI (Tl) 3 '' x 3 ''). The activities of Ra-226, Th-232 series and K-40 are between (3.8+/-0.5 and 172.8+/-1135.1+/-56.8 8.6), (2.3+/-0.3 and 103.8+/-5.2) and (53.1+/-2.7 and 1135.1+/-56.8) Bq kg(-1), respectively. With average total annual dose being only 67.2 mSv y(-1), this value is about 6.72 % of the 1.0 mSv y(-1) recommended by the International Commission on Radiological Protection (ICRP-60, 1990) as the maximum annual dose to members of the public. Geochemical studies revealed that Gabal Ras Barud is formed from a highly fractionated biotite granite, with SiO2 > 75 % and generally enriched in alkali with K/Na > 8 %.