Kenju Watanabe

Extraction of Thorium and Uranium from Chloride Solutions by Tri-n-Butyl Phosphate and Tri-n-Octyl Phosphine Oxide

The extraction of thorium and uranium chlorides by TBP and TOPO was studied. The composition of complexes extracted from the chloride solutions of low acid concentration was established by partition study to be UO2Cl2 (TOPO)2, UO2Cl4 (TOPO)2, UO2Cl4 (TOPO)2 and UCl4 (TBP)2. Composition of the thorium complex in the TBP phase free from hydrochloric acid was revealed by infrared study to be ThCl4 (TBP)4. The extraction behavior of thorium chloride by TBP was different from that of U (N) and Pu(N) chloride, and the composition of the complex was presumed to be HThCl5(TBP)4 in the extraction from concentrated chloride solution containing hydrochloric acid.

Separation of Americium and Some Rare Earths from Lanthanum by Reversed Phase Chromatography

Reversed phase column chromatography was applied to the separation of Am, Pr, Pm and Eu from 5 to 110 mg of La carrier after coprecipitation. HDEHP and TOPO-xylene solutions held on kieselguhr were used as the stationary phase and the elutions were carried out with 0.1 to 1 N nitric acid solutions. In the HDEHP system, Am can be separated from the rare earths except from Pr. Am can also be separated from Eu in the TOPO system.

Separation of Curium from Neutron Irradiated Am-241

The conditions under which curium can be separated from irradiated 241Am target were elucidated. The isolation process consists of three steps: In the first step, Am(III) is oxidized to pentavalent state in a dilute nitric acid solution, and then plutonium and curium are extracted from the irradiated target by solvent extraction with HDEHP. Curium in the organic phase is back-extracted with 1 N nitric acid, and thereafter plutonium with a reducing solution containing ferrous sulfamate. The curium is finally purified by cation exchange, using α-hydroxy isobutyrate as the eluting solution. About 0.4 μg of 242Cm and 4×10−3 μg of 243Cm were found in the curium fraction, which had been separated from 1 mg of irradiated 241Am sample.

Radiochemical Determination of Plutonium Isotopes and Americium-241 in a Plutonium Sample

Isotopic ratios of 238Pu, 239Pu, 240Pu and 241Am in a plutonium sample were approximately determined by means of combined α- and γ-ray spectrometry without chemical separation of americium from plutonium. The intensity of α-ray followed by internal conversion was determined by measuring the intensity of LX-rays. The ratio of 240Pu to 239Pu was obtained from the ratio between the α-ray intensity thus determined and the total α-ray intensity from the two nuclides.