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Abstract  

The separation of Am and Cm by using the tertiary pyridine resin embedded in silica beads was studied in nitric acid/methanol mixed solvent system. This separation system of Am and Cm is very simple and easy. The adsorption and separation behaviors of Am and Cm were investigated with changing the nitric acid and the methanol concentrations. It was confirmed that Am can be almost completely separated from Cm.

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Summary  

Direct alpha-energy spectroscopy in liquids is possible by placing a chemically selective polymer thin film upon the surface of passivated silicon diodes. By utilizing polymer thin films with high affinity for actinides, we have been able to selectively concentrate actinides of interest upon the diode surface, resulting in a substantial increase in sensitivity relative to a direct measurement. With this film coated diodes, we were able to obtain in-situ alpha spectra with energy resolution comparable to that of conventional alpha-spectroscopy. The response of the thin film coated diode was found to be linear over 104. The sensitivity and reversibility is a function of the membrane complexation chemistry.

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Summary  

The determination of transuranic (TRU) content in nuclear wastes, reactor materials, process solutions, and various other matrices is required in support of material assessment, environmental restoration, and waste processing activities. We have found that direct measurement of TRU is possible using surface passivated ion implanted planar silicon diode detectors. The performance and durability of modern silicon diodes enables direct detection of alpha-particles, with retention of some spectral information, through small air gaps or under direct contact with liquid or solid samples. We will present results on the performance of silicon diode detectors for the determination of TRU in liquids.

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Summary  

In the wide pH range of 4 to 10, distribution ratios of Am(III)-humate species to free Am(III) ions (D AmHA = [Am(III)HA]/[Am(III)]free) were determined at 10 ppm (4.7 . 10-5 eq/dm3) of humic acid and 0.1M NaClO4 by a cation-exchange equilibrium method under N2 atmosphere. The D AmHA was insensitive to an increase in pH (logD AmHA ≈ 2.6-2.8), which indicates the formation of mixed hydroxo-humate complexes. The present D AmHA value is larger than the estimated value from available stability constants for ternary complexations by spectroscopic analysis (1.4-2.1) and is markedly smaller than that of Eu(III) obtained by the dialysis method (3.7-8.0) reported in the literatures. The D AmHA obtained in the present study is widely applicable to estimate the actinide(III) and lanthanide(III) sorption on minerals in the presence of humic and fulvic acids.

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Abstract  

Complexation of Am(III) with humic acid was studied at various pHs in 0.1M NaClO4. The stability constants of the Am(III)—humate complexes were determined by a cation-exchange method. The values of log 1 and log 2 increased slightly with increases of pH from 4 to 6 and were found to be 6.9 and 11.6, respectively, at a pH of 5. Markedly larger values than these were obtained by a solvent extraction method. This discrepancy was also revealed by summarizing data from several literature sources. It is very likely that this can be ascribed to decreases in either humic acid and/or the extractant from the extraction system due to humate interactions at the aqueous-organic interface.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Mitsugashira, M. Hara, T. Ohtsuki, H. Yuki, K. Takamiya, Y. Kasamatsu, A. Shinohara, H. Kikunaga, and T. Nakanishi

Abstract  

The alpha-decay of a low energy isomer of 229Th at about 3.5 eV was sought by producing it through the (g,n) reaction on a 230Th target. Thorium isotopes in the reaction products were isolated and purified by anion exchange chromatography in a concentrated nitric acid medium to remove lanthanides fission products. The thorium fraction was further purified by samarium fluoride coprecipitation and the precipitate was mounted as a source for a-spectroscopy. Decaying a-signals were observed in the energy region that was expected for 229mTh, i.e., between 4.83 and 5.08 MeV. The half-life of the decaying component was determined from repeated experiments to be 13.9±3 hours.

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Summary  

An analytical system is suggested to separate a number of elements of the Periodic Table in a hydrogen or oxygen stream at temperatures up to 1400 °C. High temperature chemical filters are used to separate volatile products. The approach has demonstrated its efficiency in a number of examples of carrier-free isotope production from targets irradiated at an accelerator: 109Cd from In; 22Na from Al; 72Se from GaAs; 188Pt, 183Re, 185Os and 201Tl from Pb or Bi; separation of Po from Pb and Bi, etc. Another application of high temperature chemical sublimation of elements and oxides was realized in activation analysis of noble metals in various ores and samples.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Y. Oura, R. Watanabe, M. Ebihara, Y. Murakami, Y. Toh, A. Kimura, M. Koizumi, K. Furutaka, M. Oshima, K. Hara, T. Kin, S. Nakamura, and H. Harada

Abstract  

A prompt gamma-ray analysis system using multiple detection method (MPGA system) was constructed at the neutron guide hall of the JRR-3M reactor of the Japan Atomic Energy Agency. We applied MPGA method to geochemical and cosmochemical samples to evaluate its analytical performance on signal to noise (S/N) ratio, sensitivity, and detection limit. The S/N ratio measured by MPGA system was larger than that by normal prompt gamma ray activation analysis (PGAA) at JRR-3M. For some elements, the S/N ratio was improved more than ten times. Several elements that are not detected by PGAA were detected by MPGA. At the present time, concentrations of major elements and trace elements with high neutron capture cross section in geochemical and cosmochemical samples were determined accurately by the MPGA system installed at JRR-3M. It is expected that it will determine a lot of trace elements after appropriate adjustments and modifications.

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