Authors:V. Bhargava, V. Rao, S. Marathe, S. Sahakundu, and R. Iyer
A radiochemical method is described for the separation of heavier rare earths from the fission of uranium. The method is particularly
suitable for the separation of low yield (10−5%–10−7%), highly asymmetric rare earth fission products viz.179,177Lu,175Yb,173Tm,172,171Er,167Ho and161,160Tb in the neutron induced fission of natural and depleted uranium targets. Additional separation steps have been incorporated
for decontamination from239Np (an activation product) and93-90Y (a high fission-yield product) which show similar chemical behaviour to rare earths. Separation of individual rare earths
is achieved by a cation exchange method performed at 80°C by elution with α-hydroxyisobutyric acid (α-HIBA).
Authors:S. Sahakundu, S. Marathe, V. Rao, V. Bhargava, and R. Iyer
A new method for obtaining radiochemically pure67Cu from highly active fission product solutions is described. The method is based on the solvent extraction of the Cu(II)-diethyldithiocarbamate
complex in n-butyl acetate in the presence of hold-back carriers for Ni, Co, Mn, Mo, rare earths, Cd, Te and Sb, and subsequent
purification steps involving scavengings for Ag, Ba, Sr and Fe followed by an anion-exchange purification step for decontamination
from Te. Copper is finally extracted as the α-benzoin oxime complex in which form it is mounted and counted. The method has
several advantages over other methods in that decontamination is very high and it is sufficiently fast considering the stringent
radiochemical purity achieved. The67Cu separated by this procedure from a one-day-old mixture of fission products arising from 1010 fissions was found to be completely free of any contamination.
Authors:V. Bhargava, G. Chourasiya, D. Ghadse, U. Kasar, and M. Oak
A differential spectrophotometric method has been developed for plutonium in hexavalent state using a double beam spectrophotometer. The absorbance measurements were made at 835 nm in 4M sulfuric acid using a 5 cm cell. In the method developed the absorbance of six Pu(VI) standards, taken in the sample cell, were recorded against a molybdenum blue solution of appropriate intensity in the reference cell. A least-squares fit of data on absorbance and concentration of plutonium standards gave slope F and intercept Co which were used to determine the unknown concentrations using the relationship, C=C0+F·Ar where Ar is the absorbance of a plutonium solution of unknown concentration C mg/g. Various parameters like choice of acid and acidity, slit width, oxidant etc. were studied and the conditions optimized. Plutonium in the concentration range of 0.1–0.3 mg/g could be determined with a precision of ±0.5%. Uranium does not interfere. The method is useful for the analysis of a large number of samples on a routine basis.
Authors:V. Bhargava, G. Chourasiya, D. Ghadse, U. Kasar, M. Mangala, and S. Oak
A differential spectrophotometric method has been developed for uranium in presence of plutonium by making absorbance measurements at 420 nm in 4M H2SO4 using 5 cm cells. The absorbance measurements are made with two independent sets of standards: (1) having uranium only and (2) having uranium and plutonium in a fixed ratio R, against a uranium solution of high absorbance (1A) in the reference beam. A least-squares fit of data on absorbance and uranium concentration in the two cases gave two slopes m1 and m2, which were used to determine the concentration of uranium using the relationship CU=C0+m1·[AT-(1/m2–1/m1) R·CPu] where AT is the relative absorbance of uranium and plutonium at 420 nm and C0 is the intercept corresponding to slope m1 for pure uranium standards and m2 is the slope for mixed uranium and plutonium standards. A knowledge of CPu, the plutonium concentration, is essential and is obtained by differential spectrophotometric measurements at 835 nm by oxidizing plutonium to its hexavalent state. In the same aliquot, plutonium could be determined with a precision of better than ±0.5% and uranium with a precision of better than ±1.0%.