Kinetics of Np(VI) Reduction with Butanal Oxime

Reduction of Np(VI) to Np(V) with butanal oxime in the presence of excess reductant is presumably described by the equation 4NpO₂ ²⁺ + 2C₃H₇CHNOH + H₂O = 4NpO₂ ⁺ + 2C₃H₇CHO + N₂O + 4H⁺, and the reaction rate, by the equation -d[Np(VI)]/dt = k[Np(VI)][C₃H₇CHNOH]/[H⁺], with k = 230±15 min^-1 at 25°C and the ionic strength of the solution = 2. This equation holds for solutions with different values of the ionic strength and HNO₃ concentration. The activation energy is 69.4±12.4 kJ mol^-1.     

Kinetics and Mechanism of Pu(VI) Reduction with Acetaldoxime in Nitric Acid Solution

Reduction of Pu(VI) to Pu(III) with acetaldoxime (CH₃CHNOH) in an HNO₃ solution involves three consecutive steps Pu(VI) → Pu(V) → Pu(IV) → Pu(III), and also reproportionation of Pu(IV). Complete kinetics equations of these steps were derived and the rate constants and activation energies of these steps were determined by computer treatment of the experimental kinetic data for all Pu valence forms. The mechanisms of these reaction steps based on the experimental results were discussed.__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 67–71.Original Russian Text Copyright © 2005 by V. Koltunov, Pastushchak, Mezhov, G. Koltunov.     

Study of Extraction of Palladium from Nitric Acid Solutions with Nitrogen-Containing Compounds,as Applied to Recovery of Fission Palladium from Spent Nuclear Fuel of Nuclear Power Plants: 1. Extraction and Backwashing Conditions

Extractive power of high-molecular-weight amines and quarternary ammonium bases (QABs) of various structures in various aliphatic and aromatic diluents is studied with respect to recovery of palladium nitrate complexes from nitric acid solutions. The effects of pH of the aqueous phase, the contact time, and temperature on the extraction parameters were studied with selected (optimal) extractants (tri-n-octylamine and tricaprylmethylammonium nitrate) in benzene. The composition of extracted complexes was determined to be a monosolvate in the case of the QAB and a disolvate for the tertiary amine. Palladium is efficiently backwashed with concentrated HNO₃ and aminoacetic acid at elevated temperature. The solubility of amines and QABs in aqueous solutions is briefly reviewed.     

Kinetics of Reactions of Np and Pu Ions with Hydrazine Derivatives: XVII. Reaction of Pu(VI) with Hydroxyethylhydrazine

Reduction of Pu(VI) to Pu(III) with hydroxyethylhydrazine (HOC₂H₄N₂H₃) in HNO₃ solutions involves the following consecutive steps²: Pu(VI) + HOC₂H₄N₂H₄ Pu(V) + ...; Pu(V) + HOC₂H₄N₂H₄ ⁺ Pu(IV) + ...; Pu(V) + Pu(III) 2Pu(IV); and Pu(IV) + HOC_2H4N₂H₄ ⁺ Pu(III) + .... The overall kinetic equations of these steps were suggested, and their rate constants and activation energies were determined. The mechanisms of the four reaction steps, consistent with the experimental kinetic data, are discussed.     

Parameter Calculation and Investigation of a MIS Varicap with Charge Transfer for L-Range Microwave Devices

The characteristics of a MIS varicap with charge transfer designed for control microwave devices are analyzed. The limiting frequency of the device is shown to be at least twice as high as that of the standard MIS varicap based on a MIS system with a thicker dielectric in the varicap with charge transfer. A method for parameter measurements in the microwave range is developed. Some device samples are fabricated based on thin substrates of monocrystalline silicon with epitaxial layers. The correspondence between the theoretical and experimental characteristics of the varicap is established.     

Study of Extraction of Palladium from Nitric Acid Solutions with Nitrogen-Containing Compounds,as Applied to Recovery of Fission Palladium from Spent Nuclear Fuel of Nuclear Power Plants: 3. Optimization of Extraction Process for Palladium Recovery and Refining

An extraction process for recovery of fission Pd is proposed. The process parameters are optimized with simulated high-level liquid radioactive waste from nuclear power plants using tri-n-octylamine (TOA) and tricaprylmethylammonium nitrate (Aliquat 336 nitrate) as extractants. The degree of Pd decontamination from fission and corrosion products is estimated and the major interfering components are determined.     

Study of Extraction of Palladium from Nitric Acid Solutions with Nitrogen-Containing Compounds,as Applied to Recovery of Fission Palladium from Spent Nuclear Fuel of Nuclear Power Plants: 2. Effect of Radiation on Palladium Recovery and Condition of Extraction Systems

Extraction of palladium nitrate complexes from 1-3 M HNO₃ with tri-n-octylamine (TOA) and tricaprylmethylammonium nitrate (Aliquat 336 nitrate) in diethylbenzene under irradiation at a dose of up to 100 W h l^{- 1} is studied. In irradiated extraction systems, the acidity of the aqueous and organic phases decreases and HNO₂ is formed. With increasing radiation dose the degree of Pd recovery decreases by virtue of partial degradation of the organic phase. The radiation effects on the condition of extraction systems are discussed.