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Abstract  

Acetohydroxamic acid (AHA) is an important complexant/reductant for Pu(IV) in the UREX process. It decomposes in the presence of nitric acid. In literature, its decomposition kinetics in nitric acid is traditionally reported as pseudo-first order reaction. In this study, new experimental data were reported for kinetics experiments under wide consecration conditions. It was found that the decomposition reaction was first order with respect to both the components hence overall second order.

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Abstract  

Urea-adduct process is commercially used to selectively separate n-alkanes from industrial hydrocarbon mixtures. Authors have explored application of this method for recovery of n-alkane based diluents from spent PUREX/UREX solvent. Traditionally this separation is performed by vacuum distillation, an energy-intensive process. The proposed method is simple and does not involve either exotic chemicals or complex processing steps. Application of urea-adduct process for recovery of diluent from spent solvent is reported here possibly first time in literature. Physical properties such as densities, viscosities and vapour pressure for irradiated organic solutions were also measured and reported.

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Abstract  

Hydroxyurea and its derivatives are important nonsalt forming reductants in partitioning of uranium and plutonium in the nuclear fuel reprocessing operations. There is no experimental data available in open literature describing pressurization due to the thermal decomposition of aqueous and nitric solutions of hydroxyurea at elevated temperatures. Authors studied thermal decomposition of hydroxyurea-nitric acid system and resultant pressurization at various concentrations of nitric acid in an adiabatic calorimeter in closed-vent conditions. During these experiments, pressurization was observed. In this paper, results of these experiments have been discussed.

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Abstract  

Reversed TALSPEAK (RT) Solvent [0.3 M di-(2-ethyl hexyl) phosphoric acid or D2EPHA in 0.2 M TBP in normal paraffinic diluent] is used as extractant in partitioning of lanthanides and actinides in post-UREX process flow sheets. There is no experimental data available in literature describing pressurization either due to the thermal decomposition or the reaction of RT solvent with nitric acid at elevated temperatures. Experiments were conducted for heating of RT solvent and acid equilibrated RT solvent under closed-vent adiabatic conditions. During these experiments, considerable pressurization was observed. In this paper, results of these experiments are discussed in detail.

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Abstract  

Phenyl trifluoromethyl sulfone (FS-13) is an inert diluent used in HCCD/PEG process for isolation and recovery of cesium and strontium from highly radioactive raffinate waste. There is no experimental data available in open literature describing pressurization due to the thermal decomposition of FS-13 at elevated temperatures. Experiments were conducted for determination of flash point and heating of FS-13 under pressurized closed-vent conditions in an adiabatic calorimeter. During adiabatic experiments, negligible pressurization was observed.

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Abstract  

Formation and thermal decomposition of red-oil during unit operations of nuclear fuel cycle process flowsheets is a severe risk. In the literature, red-oil formation has been investigated thoroughly in general and in detail after Tomsk-7 incident on 6th April 1993. However there is no information on the thermal decomposition of formed red-oil. In this work, results of unique experiments on adiabatic thermal decomposition of red-oil, red-oil equilibrated with excess of 4N nitric acid and 100% TBP equilibrated with excess of 4N nitric acid have been discussed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Shekhar Kumar
,
S. Balasubramonian
,
Pranay Sinha
,
D. Sivakumar
,
U. Kamachi Mudali
, and
R. Natarajan

Abstract  

Thermophysical properties of reversed TALSPEAK extractant (0.3 M D2EPHA/0.2 M TBP/n-dodecane) were not available in literature. Authors have experimentally measured and correlated several thermophysical properties of RT solvent like density, viscosity, refractive index, acid uptake and flash point. In this paper, results of these studies will be discussed in detail.

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