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Abstract  

The first empirical method for preparing a plutonium predominance-region diagram used horizontal lines to locate the boundaries of the regions of forbidden, unique, and ambiguous oxidation-state distributions. A second approach changes the procedure by using vertical lines to illustrate these regions. In both cases, the boundary lines are determined by the Pu oxidation number and the equilibrium fraction of one oxidation state.

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Abstract  

The spent fuel from Fast Breeder Test Reactor of various burnups from 25 to 155 GWd/te is being reprocessed in CORAL (COmpact Reprocessing of Advanced fuels in Lead shielded cell) using a modified PUREX (Plutonium Uranium Recovery by EXtraction) process. Total plutonium (Pu238, 239, 240, 241 & 242) concentration in the sample is analysed by HTTA (Thenoyl Trifluoro Acetone) extraction method wherever interference from other alpha emitting nuclides (Raffinate) and bulk natural uranium (uranium products) are present "as reported by Milyukov et al. (Analytical chemistry of plutonium, <cite>1967</cite>) and Natarajan and Subba Rao (BARC, pp. 38–43, <cite>2007</cite>)". This method requires the addition of corrosive reagents such as NH2OH.HCl which is a problem in waste disposal for reduction. A salt-free reagent such as Hydroxyurea is studied as a reducing agent which has the ability to reduce both Pu(VI) and Pu(IV) to Pu(III) "as reported by Zhaowu (260(3):601–606, <cite>2004</cite>) and Zhaowu (262(3):707–711, <cite>2004</cite>)". Pu(III) thus formed can be easily oxidised to Pu(IV) by NaNO2 for the extraction of Pu by HTTA.

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Abstract  

The one-oxidation-state method is used to estimate the equilibrium constant of the first hydrolysis reaction of tetravalent plutonium. The analysis of the properties of plutonium near a triple point is an alternative approach to the estimation of the hydrolysis constant.

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Abstract  

Six discrete formulas are used to estimate the equilibrium constant of the first hydrolysis reaction of tetravalent plutonium. They apply the pH, the oxidation number, one equilibrium constant, and fractions of two of the plutonium oxidation states. The new formulas are not restricted to the equilibrium condition.

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Abstract  

Four new formulas for estimating the first hydrolysis constant of tetravalent plutonium are illustrated. They can be applied with or without an independent estimate of the Pu oxidation number.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Svetlana Ovsiannikova, Maryna Papenia, Katsiaryna Voinikava, Justin Brown, Lindys Skipperud, Galina Sokolik, and Sergey Svirschevsky

Abstract  

The physicochemical forms of radionuclides in soils determine the processes of their entry into the soil solutions, redistribution in the soil profile, soil–plant and soil–ground or surface waters transfer as well as spreading outside the contaminated area. The vertical distribution of plutonium and americium and their physicochemical forms in soils of Polessie State Radiation-Ecological Reserve (PSRER) were studied with the aim of establishing the potential for radionuclide migration. Samples of alluvial soddy-podzolic and peaty soils with a low (1–3%) and relatively high (~80% of dry sample mass) content of organic matter have been selected for investigation. A method employing sequential selective extraction has been used for analysis of radionuclide physicochemical forms in the soils. Activity concentrations of 238Pu, 239,240Pu and 241Am in the samples were determined via radiochemical analysis with alpha-spectrometric identification of radionuclides. The results indicate that the main proportion of plutonium and americium remains in the 0–20 cm soil layer. The inventories of mobile and biologically available forms of plutonium and americium, expressed as a percentage of the total radionuclide content in soil, lie in the ranges of 1.1–9.4 and 2.7–29% respectively. Greater proportions of mobile and biologically available forms of radionuclides appear to be associated with mineral soil as compared to organic soil. In both mineral and organic soils, the portion of mobile americium is higher than plutonium. The inventories of mobile forms of plutonium and americium increase with the depth of soils.

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Abstract  

A new method for estimating the numerical value of the first hydrolysis constant of tetravalent plutonium is illustrated by examples. It uses the pH and the equilibrium fractions of two of the Pu oxidation states. They are substituted into one or more of a choice of formulas that render explicit estimates of the hydrolysis constant.

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Abstract  

Glass or silicon substrates functionalized with a monolayer of carbamoylmethylphosphonate (CMP) ligands effectively bind tetravalent actinides from optimized mineral acid solutions to enable rapid, high quality radiometric assay by alpha spectrometry. The observed alpha spectra compare favorably with the highest quality electroplated samples. The CMP-functionalized surfaces have been used to develop simplified analytical methods to determine plutonium from complex mixtures.

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Abstract  

Apparent mass method (Venkataraman and Croft, Nucl Instrum Methods Phys Res A 505:527, <cite>2003</cite>), initially standardized for the assay of Pu (Agarwal et al., J Nucl Mater 651:386, <cite>2007</cite>) has been used to get Pu amount in empty stainless steel boxes generally used for storing and transferring plutonium oxide powders. The results have been compared with the neutron coincidence counting results and have been found to match well. The advantage of the method is that it can be used for any sample with nonstandard geometry and with uncertain source distribution.

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Abstract  

Trace metallic impurity analysis by spectroscopic techniques is one of the important steps of chemical quality control of nuclear fuel materials. Depending on the burn-up and the storage time of the fuel, there is an accumulation of 241Am in plutonium based fuel materials due to β decay of 241Pu. In this paper, attempts were made to develop a method for separation of 241Am from 1.2 kg of analytical solid waste containing 70% U, 23% Pu, 5% Ag and 1–2% C as major constituents along with other minor constituents generated during trace metal assay of plutonium based fuel samples by d. c. arc carrier distillation atomic emission spectrometry. A combination of ion exchange, solvent extraction and precipitation methods were carried out to separate ~45 mg of 241Am as Am(NO3)3 from 15 L of the analytical waste solution. Dowex 1×4 ion exchange chromatographic method was used for separation of Pu whereas 30% TBP–kerosene was utilized for separation of U. Am was separated from other impurities by fluoride precipitation followed by conversion to nitrate. The recovery of Pu from ion exchange chromatographic separation step was ~93% while the cumulative recovery of Am after separation process was found to be ~90%.

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