Sequential determination of uranium (IV), free acidity and hydrazine in a single aliquot S. Ganesh • Fahmida Khan • M. K. Ahmed • Shashikrishna Pandey Received: 18 February 2010 / Published online: 2 July 2010 Ó Akade ´miai Kiado ´, Budapest, Hungary 2010 Abstract A simple analytical procedure for the sequen- tial determination of uranium (IV), free acidity and hydrazine in presence of hydrolysable ions is developed and described. In this method, first, uranium (IV) is determined using fiber optic aided spectrophotometry then same solution is used for determination of free acidity and hydrazine. Free acid is titrated with standard sodium car- bonate solution after uranium (IV) is masked with EDTA. Once the end point for the free acid is determined at pH 3.0, an aliquot of formaldehyde is added to liberate the acid equivalent to hydrazine which is then titrated with the same standard sodium carbonate solution using an automatic titration system. The described method is simple, accurate and reproducible. The overall recovery of uranium (IV), nitric acid and hydrazine is 98% with 3% relative standard deviation respectively. The major advantage of the method is that it uses sodium carbonate a primary standard as titrant and generation of corrosive analytical wastes con- taining oxalate or sulphate is avoided. Valuable metals like uranium and plutonium can easily be recovered from analytical waste before final disposal. Keywords Uranium (IV)  Free acidity  Hydrazine  Single aliquote  pH 3.0  HCHO Introduction Separation of uranium and plutonium (partitioning) is an important step in the reprocessing of spent nuclear fuel by PUREX process [1]. In the partitioning step, low distri- bution ratio [2] of Pu (III) has been utilized for the sepa- ration of uranium from plutonium. Plutonium is selectively stripped to the aqueous phase by reducing the oxidation state of plutonium (IV) to Pu (III). In Conventional meth- ods chemical reductants like ferrous sulphamate, hydroxyl ammonium nitrate and hydrazine stabilized uranous nitrate etc. are used. Compared to other reducing agents hydrazine stabilized U (IV) [1, 3] is better suited for (a) avoidance of non-evaporable substance in the plant effluent, (b) extractability of U (IV) by TBP enabling easy removal from the plutonium steam while uranium stream is free from plutonium contamination, (c) virtual irreversibility of the redox reaction. On the flip side its reaction with Pu (IV) is slow and hence to overcome this difficulty large excess of U (IV) is added. Presence of large quantity of externally generated uranous is not feasible option as it poses prob- lems like criticality and related vessel size limitations [4]. Hydrazine destroys HNO 2 formed in the nitric acid med- ium and prevents re-oxidation of Pu (III) to Pu (IV) that inhibits partitioning. Important aspects [5] to be considered while selecting the methods for the determination of vari- ous constituents in the fuel reprocessing streams are (1) the aliquot required for the analysis should be small to over- come the difficulties of handling radioactivity, (2) the analytical wastes generated should be low to minimize the waste and finally (3) recovery of fissile material from analytical waste should not be difficult. From the plant operation point of view, it is necessary to develop rapid and simple analytical methods with reasonable accuracy and precision taking into account the above mentioned aspects. S. Ganesh  M. K. Ahmed Reprocessing Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, India F. Khan (&)  S. Pandey Department of Chemistry, National Institute of Technology, Raipur 492010, India e-mail: fkhan.chy@nitrr.ac.in 123 J Radioanal Nucl Chem (2010) 286:33–37 DOI 10.1007/s10967-010-0663-9