Radium activity and radon exhalation rates from phosphate ores using CR-39 on-line with an electronic radon gas analyzer ``Alpha GUARD{''

Nuclear track detectors (NTDs) have seen a major expansion in application to general physical and geological problems reflecting its advances in understanding the exhalation dependence of radon as well as radon and radium concentration distributions in the earth's crust. However, considerable uncertainties still persist, in particular, concerning the detection efficiency of track detectors which are not calibrated precisely to a standard method or an active detector of a unique efficiency. In this investigation, CR-39 NTDs and an electronic radon gas analyzer ``Alpha GUARD{''} were used for the measurement of radon exhalation rate and radium concentration in phosphate samples collected from two different mines of El-Sobaeya and El-Suez, Egypt. The phosphate sample was loaded into an emanation container (Genitron Instruments GmbH) equipped with a PC-based radon gas analyzer. The CR-39 track detectors were mounted inside a diffusion cup used simultaneously with the Alpha GUARD radon gas analyzer. Radium activity in phosphate samples was found to vary from 1.8 to 361.3 kBq kg(-1). The radon exhalation rates in these samples were found to vary from 0.020 (0.003) to 4.125 Bq m(-2) h(-1) (0.658 Bq kg(-1) h(-1)). (C) 2008 Elsevier Ltd. All rights reserved.