Assessment of the natural radioactivity and its radiological hazards in some Egyptian rock phosphates

Radioactivity of terrestrial radionuclides Ra-226, Th-212 and K-40 in phosphate rock samples has been measured using gamma ray spectrometry system with an HPGe detector. The samples showed fairly high mean concentrations, 410 39 Bq.kg(-1) of Ra-216, 7.9 +/- 0.95 of Th-232 and 37.6 +/- 4 of K-40. Mean absorbed gamma dose rate of 181.9 +/- 20 nGy.h(-1) was measured in air. Assessment of radiological hazards was made by calculating radium equivalent activities with external and internal hazard indices. The calculations showed radium equivalent activity ranging from 317 to 520 Bq.kg-1. External and internal hazard indices ranging from 0.4 to 0.7 and 0.1 to 0.4, respectively. The results of the analysis have been found to be in a good agreement with the data obtained by others.