Sequential Radiochemical Procedure for Isotopic Analysis of Uranium and Thorium in Egyptian Monazite

Gamma and alpha spectrometry techniques were applied to determine the activity concentrations of 238 U and 232 Th (Bq kg –1 ) as well as the 234 U/ 238 U and 230 Th/ 234 U isotopic ratios for commercial grade monazite (purity ≈50%) supplied from the Egypt nuclear materials authority. A method for total dissolution of monazite followed by the sequential radiochemical separation using anion-exchange chromatography is presented. The average activity concentrations of 238 U and 232 Th, measured by α-ray spectrometry, are 2.49 g kg –1 (0.24 wt %) and 30.09 g kg –1 (3.1 wt %), respectively. The calculated 234 U/ 238 U and 230 Th/ 234 U isotopic ratios are close to unity, suggesting closed system equilibrium. The possibility of using leaching of monazite with water at different pH values for gaining information about the masses of uranium and thorium that pass into the solution and remain fixed in the crystal lattice was examined.