الفهرس 
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Abstract
The safe management and disposal of radioactive wastes from the nuclear fuel cycle is increasingly being seen as a necessary condition for the future development of nuclear energy Laboratory experiments and theoretical models were conducted to show that waste disposal methods are safe and that both man and the environment will be adequately protected. The major objective of this work is to study the effect of goethite colloid (a-FeOOH) on the transport of U(VI) in Inshas groundwater (saturated zone) as a part of the performance assessment of Inshas disposal site. The results show that goethite particles are stable in the pH studied range 4.0 - 10.5 and in the Nad ionic strength range 10”4M- 10”’ M and exist in a colloidal form. The species of U(VI) at 25±2°C and 1 atm are UO2/ ,.(UO2)3(OH)5+, U02(OH)2 (aq), (UOjMOIiy, (UO2)2(OH)22\ in addition to other species of negligible concentrations. Speciation of U(VI)/CaCO3 showed that UO22+, (UO2)2COj(OH)”;, and U02(OH) j are the major species. The adsorption of goethite onto wedron-510 sand is controlled by the surface charge of both the two surfaces. The pHPZc of quartz is 2.0 and that of goethite is 6.8 .The surface charge of a-FeOOH is a pH dependent. The isotherms of the adsorption of U(VI) onto wedron-510 sand were found to be fitted as Freundlich. The transport of U(Vl) depends on the hydrology of the system, the speciation of U(Vt), presence or absence of goethite colloid, and the chemical and physical condition of the porous medium. The Darcy’s velocity, permeability and hydraulic conductivity were found to be 1.45xlO’2 cm/s, 4xlO~7 cm2, and 4.4xlO”2 cm/s, respectively. The Peclet number value is 2.92 less than 6 which means that the transport of U(V1) depends on the dispersion as well as the advection in the porous medium. The hydrodynamic dispersion (D) was found to be 7.44xlO”2 cm2/s. The Reynold’s number of the system was found to be 1.03 less than 10. The flow inside the column is laminar and there is no channeling and Darcy’s law is valid for the system. The velocity of the inert KiSO^ tracer was equal to the velocity of the fluid as a result of no sorption during the mass transfer through the saturated column. The velocities of U(V1) and U(V1) /a-FeOOH were less than the velocity of the water in the porous medium as a result of the sorption and retardation in the porous column. It was found that the velocity of U(VI) in Inshas groundwater is higher than that in other.