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Abstract  

The experience with the determination of plutonium and uranium in the samples of nuclear fuel obtained during a 10-years period of the activity of the Central Control Laboratory of the Nuclear Research Institute at e is evaluated. The paper describes the principles of the methods used and the reproducibilities and accuracies of the results obtained with the aid of the titrimetric methods used for the determination of plutonium and uranium.

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Abstract  

A method is described for the sequential determination of uranium and plutonium in plutonium bearing fuel materials. Uranium and plutonium are reduced to U(IV) and Pu(III) with titanous chloride and then titrated with dichromate to two end points which are detected amperometrically using two polarized platinum electrodes. Uranium-plutonium solutions of known concentrations containing plutonium in the proportions of 4, 30, 50, and 70% were analyzed with precisions better than 0.3%, maintaining the amounts of plutonium per aliquot in the range of 2–10 mg. No significant bias could be detected. Several samples of (U, Pu)O2 and (U, Pu)C were analyzed by this procedure. The effects of iron, fluoride, oxalic acid and mellitic acid on the method were also studied.

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Abstract  

Plutonium (Pu) metal samples from an interlaboratory exchange exercise and simulated swipe samples were dated using plutonium–uranium (Pu–U) and plutonium–americium (Pu–Am). Metal data were evaluated for consistency and the swipe data against its source material. Metal ages based on 239Pu versus 235U and 240Pu versus 236U agreed to within a few percent, while the 238Pu–234U and 241Pu–241Am measurements had larger uncertainties. Swipe ages compared favorably with the material’s known history. Neptunium (237Np) analyses were examined in the context of the 241Pu–241Am–237Np system to estimate whether Np can provide insights on material from which Am, Np, and U were removed.

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Abstract  

Almost quantitative recovery of plutonium from assorted non-recoverable aqueous acidic and organic waste solutions originating from solvent extraction studies and synthesis of solid plutonium compounds has been achieved by using combined solvent extraction and extraction chromatographic techniques. During solvent extraction a mixture of 0.2M CMPO+1.2M TBP in dodecane was used as the extractant while in extraction chromatography a small column of CMPO adsorbed on Chromosorb-102 (CAC) was utilised. The activities could finally be recovered from the loaded organic phase as well as the CAC column. The effluent after the combined operation was almost alpha-free. About 3 g of plutonium was recovered from about 19 litres of different wastes.

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Abstract  

For the internal dosimetry of plutonium, a urine bioassay method is very useful but requires several days to obtain the result of the analysis. To shorten the time required for the urine bioassay, a rapid method for plutonium analysis using the ICP-MS system was developed. In this chemical procedure, a microwave oven was applied for sample digestion, and an extraction chromatography resin was used for the separation of plutonium. The measurement time was extremely reduced by application of the ICP-MS as compared to alpha-spectrometry. The total analysis time was about 12 hours and the detection limit was 0.3 mBq/sample. The short analysis time and the low detection limit indicate that this method is useful not only for special monitoring but also for routine monitoring.

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Abstract  

The equilibrium constant for the first hydrolysis reaction of tetravalent plutonium is surrounded by uncertainty. A new method illustrates criteria by which the reliabilities of the numerical estimates can be judged. The new formulas are simple, the method is easy to apply, and the results are easy to compare.

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Abstract  

The numerical value of the first hydrolysis constant of tetravalent plutonium is uncertain by a factor of about ten. This article illustrates the estimation of that constant by a least squares method applied to simultaneous equations involving all of the Pu oxidation states.

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Abstract  

Boundary equations for a diagram of the ambiguous, forbidden, and unique combinations of hexavalent plutonium versus the Pu oxidation number are presented. The equations and the diagram apply after disproportionation reactions have reached equilibrium. A curve illustrates the equilibrium fraction of Pu(V) versus the Pu oxidation number in a solution at pH 2.

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Abstract  

Four intrinsic predominance-region diagrams for aqueous plutonium are described. They are easily prepared from an existing diagram by changing the oxidation-state fractions on the axes of the diagram and renaming the predominance regions. Not all combinations of oxidation-state fractions can be used to prepare the diagrams.

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Abstract  

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.

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