Ammonium dinitramide (ADN) prills were prepared by emulsion crystallization and characterized by optical microscopic, thermogravimetric
(TG) and differential scanning calorimetric (DSC) techniques. The isothermal and non-isothermal decomposition kinetics of
ADN prills were studied by TG. The differential isoconversional method of Friedman (FR) and integral isoconversional method
of Vyazovkin were used to investigate the dependence of activation energy (Ea) with conversion (α) and the results were compared with literature data. The dependence of activation energy was also derived
from isothermal data. A strong dependence of Ea with α is observed for the ADN prills. All the methods showed an initial increase in Ea up to α=∼0.2 and later decreases over the rest of conversion. The apparent Ea values of FR method are higher than that of Vyazovkin method up to α=∼0.45. The calculated mean Ea values by FR, Vyazovkin and standard isoconversional method for α between 0.05 and 0.95 were 211.0, 203.9 and 156.9 kJ mol−1, respectively.
Authors:P. Govindan, S. Sukumar, K. Vijayan, G. Santhosh Kumar, S. Ganesh, Pradeep Sharma, K. Dhamodharan, R. Subba Rao, M. Venkataraman, and R. Natarajan
A novel method has been developed for recovery of plutonium and uranium from carbonate wash solutions generated during solvent
wash process involved in the reprocessing of high burn up FBTR fuel. The proposed method involves a selective coprecipitation
of Pu and U by adding ammonium hydroxide to the pre acidified carbonate wash solution. Substantial removal of DBP by successive
steps of coprecipitation, completely eliminates the possibility of undesired solid formation which is mainly due to the presence
of high content of DBP. By adopting this method, an excellent decontamination factor for DBP has been achieved without any
crud/solid formation. Phosphate content in the final oxide product meets the product specifications. Flowsheet condition necessary
for the recovery process for plutonium from the aqueous carbonate solution is formulated and adopted in the CORAL facility.