S.K. Aggarwal

Gas phase reactions of uranyl with α-hydroxyisobutyric acid using electrospray ionization mass spectrometry and density functional theory

Electrospray ionization mass spectrometry (ESI-MS) technique was used to find out the type of species of uranyl with α-hydroxyisobutyric acid in positive and negative ion modes. It was found that the singly charged monomeric and doubly charged dimeric species were present in soft ionization conditions. The molecular level understanding on the structures and energetics were investigated using density functional theory based calculations. It was found that ML3, the most intense species observed in ESI-MS were energetically more favorable as compared to ML1 and ML2.

Determining the age and history of plutonium using isotope correlations and experimentally determined data on isotopic abundances of plutonium and 241Am

Linear correlations using a data set of nominally cooled samples of Pu formed in Indian PHWRs using experimentally determined 241Pu/239Pu versus 240Pu/239Pu and 241Am/239Pu versus 240Pu/239Pu isotope ratios have been developed which can be used for determining the age of Pu. By correlating both Pu and Am isotopic information, an understanding of how the material was processed, when chemical separations occurred to remove 241Am as well as the true age of the Pu in sample can be obtained. Two actual samples from a PHWR with unknown origin were analyzed as a part of case study for application of this new methodology.

Development of gamma spectrometric method for the determination of thorium in phosphoric acid solution

Abstract Gamma spectrometric determination of thorium in sintered thoria dissolved in strong phosphoric acid was studied using a high purity germanium (HPGe) detector. 232Th was determined using the highly abundant (27%) gamma ray (911.4 keV) emitted by its daughter 228Ac. The count rates in peak regions were plotted against the amount of thorium present in thorium nitrate working standard solution to obtain a calibration curve and the extent of thoria dissolved in 88% phosphoric acid was determined. Further studies on determination of thorium were carried out using thorium phosphate solutions, instead of using thorium nitrate working standard solutions. The solution of thorium phosphate obtained after quantitative dissolution of thoria in 88% phosphoric acid was also found to give a linear calibration curve at 911.4 keV. Using the calibration curves, expected count rates for thorium in sintered thoria dissolved in 88% phosphoric acid were calculated and were in good agreement (±3%) with the observed count rates.