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Solvent extraction studies on the purification of uranium from zirconium rich sodium diuranate (SDU) feed was carried out using n-tri butyl phosphate (TBP) as extractant and n-decanol as phase modifier. The presence of Zr in SDU leached solution leads to the formation of third phase during liquid-liquid extraction of uranium which was successfully prevented by addition of n-decanol in 30% (v/v) TBP/ n-dodecane mixture. A seven stage counter current extraction of SDU feed solution followed by five stage stripping were carried out using optimum concentration of phase modifier 15% n-decanol-30% TBP in n-dodecane as solvent. Based on the findings a process flow-sheet has been developed for the purification of SDU to nuclear grade ammonium diuranate. [ABSTRACT FROM AUTHOR]

Uranium-233 ( t ~ 1.59E5 years) is an artificial, fissile isotope of uranium that has significant importance in nuclear forensics. The isotope provides a unique signature in determining the origin and provenance of uranium-bearing materials and is valuable as a mass spectrometric tracer. Alpha spectrometry was employed in the critical evaluation of a U standard reference material (SRM-995) as a dual tracer system based on the in-growth of Th ( t ~ 7.34E3 years) for ~35 years following radiochemical purification. Preliminary investigations focused on the isotopic analysis of standards and unmodified fractions of SRM-995; all samples were separated and purified using a multi-column anion-exchange scheme. The Th/U atom ratio for SRM-995 was found to be 1.598E−4 (±4.50 %) using recovery-corrected radiochemical methods. Using the Bateman equations and relevant half-lives, this ratio reflects a material that was purified ~36.8 years prior to this analysis. The calculated age is discussed in contrast with both the date of certification and the recorded date of last purification. [ABSTRACT FROM AUTHOR]

In this study we describe a method for uranium dating (i.e. determination of the date of the last chemical purification undergone by the material) by measurement of the Th/U ratio, applicable to sub-microgram quantities. The chosen protocol (AG1x8 resin in hydrochloric acid medium) has been tested on separation microcolumns (100 μl). This 'microchemistry' technique considerably limits the risks of contamination by reagents or the environment. Thorium extraction efficiencies were greater than 90 % and reproducible. The quantities of Th introduced by the chemical purification procedure were negligible. Using an ultra-sensitive inductively coupled plasma mass spectrometry measurement technique, detection limits of the order of femtograms (10 g) of Th were obtained. The complete procedure, chemical separation and isotope measurement, was successfully tested and validated on a few micrograms of uranium. [ABSTRACT FROM AUTHOR]

Separation and purification of133Xe from acidic solution containing uranium,99Mo and131I has been developed. In the first step of this work, uranium pellets were dissolved under pressure (8-15 bar) in 8M nitric acid solution. Then133 Xe and other gases were conducted to activated charcoal cold trap. Final purification of133Xe from impurities such as NO x, radioiodine and krypton was performed by passing through a molecular sieve preparative chromatographic column using helium as mobile phase. The final recovery of133Xe from the separation-purification process was higher than 98%. Adsorption-desorption behavior of radioxenon on the charcoal and molecular sieves have also been studied and discussed. [ABSTRACT FROM AUTHOR]