الفهرس 
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Abstract
This study is aimed to evaluate the activity concentrations and assessment of radiation hazard indices and excess lifetime cancer risk (ELCR), and to examine the mobility of uranium, thorium and their isotopes and daughters during the acid leaching. In the same context the study of the daughter / parent ratios in the three phases, original sample, leach liquor and residue which gave a complete picture about the behavior during weathering and alterations in twenty one sedimentary rock samples obtained from three different localities named Wadi Nasab, Wadi Sad El Banat and Wadi Um Hamd, southwestern Sinai, Egypt.
In the first stage; the natural radionuclides in the original samples have been measured by using HPGe detector with a specially designed shield. The work showed that the activity concentrations of 238U, 226R, 232Th and 40K were higher than the world’s average. The activity ratios 234U/238U, 230Th/238U, 230Th/234U, 226Ra/238U, 238U/235U and 234U/235U were studied to estimate the radioactive equilibrium / disequilibrium in the three localities.
In the present work, the radium equivalent (Raeq) in Bq/Kg, external hazard index (Hex), radioactivity level index (I γ), the absorbed dose rate (D) and the annual effective dose (AED) in an outdoor environment were estimated. The excess lifetime cancer risk (ELCR) was found to be high for all samples due to high natural radioactivity concentrations in the area under investigation which represent radiological risk for the health of population.
The radon emanation factor and the radon mass exhalation rate have been calculated for the three localities by using HPGe detector.
In the second stage; the behavior of the different radionuclides were studied during the hydrometallurgical phases on five choiced samples. The hydrometallurgical phases led to obtain two products; the pregnant solutions (contains dissolved U) and residuals (waste) from the leaching processes. The activity ratios are also studied for these two products especially 226Ra/238U and 234U/238U.
The behavior of radionuclides (238U, 235U, 234U, 226Ra, 214Pb, 214Bi, 232Th and 40K) was studied during the acid leaching process. The nuclides before 226Ra in the 238U decay series are easily released in the pregnant solutions than the 226Ra itself and the nuclides after it (214Pb and 214Bi), these are concentrated in the residuals. The 235U has nearly the same leachability as 238U, while 232Th is immobile except in the presence of organic matters.
The hazard indices in the residuals are higher than the worldwide limits in all parameters. But in the pregnant solutions all the parameters are higher than the world average except two samples.
In the third stage; the five selected samples were treated by the analytical technique XRF, to measure the concentration of the major and trace elements. The samples contain high concentrations of Cu, Mn, Zn, Pb, Sr, V, Cr, REEs, and U. which can separate and use in different important industries.