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Abstract  

A radiochemical separation method for plutonium and americium from aqueous medium has been developed using a pre-packed resin column, a peristaltic pump, and the necessary tubing and valves for flow injection technique. All the radioanalytical operations were conducted in-line. Samples made of plutonium and americium tracers in water were analyzed by this technique and counted by alpha spectroscopy. The results show that plutonium and americium can be measured simultaneously using this technique.

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Abstract  

A modified radiometric method for the determination of plutonium in irradiated nuclear fuel is described. The analysis consists of total plutonium alpha-activity, activity ratio238Pu:(239Pu+240Pu) and burnup determination. The error of plutonium determination is practically identical with that of a classical radiometric method. The method suggested is suitable for large sample series of the same type of irradiated nuclear fuel.

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Abstract  

The formation of plutonium radionuclides (239+240Pu) from uranium was determined in dismounted shielding concrete from accelerator components. Plutonium and uranium fractions were separated by radioanalytical techniques and measured by -spectroscopy. The measurements are consistent with yield calculations based on transport and single particle codes. The yield of 239+240Pu did not exceed the two-fold exemption limit given in the Swiss Radiation Protection Law, thus the plutonium content in shielding concrete should not cause problem for the environment.

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Abstract  

When manganese dioxide impregnated filters have been used to concentrate plutonium from water solutions some anomalies were detected, which were ascribed to the probable existence of plutonium in two different oxidation states. The results of this paper seem to confirm this assumption that the Pu in the solution is a mixture of Pu(III) and Pu(IV). After contact with MnO2, plutonium in the solution consists of only Pu(IV).

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Abstract  

The results connected with the preparations of uranium and plutonium Standard Reference Materials, in which the content of the main compound is certified are considered.

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Abstract  

Effect of the presence of plutonium on the determination of uranium by potentiometric method has been studied. The presence of large quantities of plutonium does not appear to affect the determination of uranium present at 5 mg as well as 250 mg levels.

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Abstract  

Kinetic equation of one stage process of reduction of plutonium(IV) in two phase 30 vol. % TBP — n-dodecane/HNO3 system is given. The expression derived is used for elaborating the method of calculation of equilibrium (ultimate) concentration profiles of plutonium in multistage contactors for countercurrent process of U/Pu separation.

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Abstract  

Relative particle size distribution of plutonium polymer colloid and its aging effective were determined by using an ultracentrifuge. The distribution is not uniform. In the early stage of polymerization, very fine polymer particles of plutonium are formed. The fraction of the larger particles increases with aging.

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Abstract  

A differential spectrophotometric method has been developed for uranium in presence of plutonium by making absorbance measurements at 420 nm in 4M H2SO4 using 5 cm cells. The absorbance measurements are made with two independent sets of standards: (1) having uranium only and (2) having uranium and plutonium in a fixed ratio R, against a uranium solution of high absorbance (1A) in the reference beam. A least-squares fit of data on absorbance and uranium concentration in the two cases gave two slopes m1 and m2, which were used to determine the concentration of uranium using the relationship CU=C0+m1·[AT-(1/m2–1/m1) R·CPu] where AT is the relative absorbance of uranium and plutonium at 420 nm and C0 is the intercept corresponding to slope m1 for pure uranium standards and m2 is the slope for mixed uranium and plutonium standards. A knowledge of CPu, the plutonium concentration, is essential and is obtained by differential spectrophotometric measurements at 835 nm by oxidizing plutonium to its hexavalent state. In the same aliquot, plutonium could be determined with a precision of better than ±0.5% and uranium with a precision of better than ±1.0%.

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Abstract  

Plutonium(III) oxidation under high energy -irradiation in nitric acid solutions has been studied relative to concentrations of both nitric acid (0.12–2.9 mol/l) and plutonium (1.4–10 mmol/l) using spectrophotometric techniques. Curium-244 has been used as the basic alpha-irradiation source. It has been stated that in solutions with nitric acid concentrations lower than 0.5 mol/l plutonium(III) does not oxidize completely. In the course of the process the formation of a plutonium(IV) peroxide complex is observed. Increase in the nitric acid concentration results in that in both the rate and degree of plutonium(III) oxidation. When cHNO 3 is higher than 0.5 mol/l the peroxide complex does not form and the process assumes an autocatalytic character. It has also been shown that plutonium(III) oxidation kinetics is significantly affected by nitrous acid, one of the nitrate ion radiolysis products. To describe plutonium chemical transformations under irradiation in nitric acid solutions, a kinetic scheme is proposed. The calculations have been carried out on a BESM-6 computer; a satisfactory agreement between the calculated and experimental data has been obtained.

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