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Abstract  

This paper reports the results of instrumental neutron activation analysis (INAA) on 3,704 obsidian samples, taking the measurements of 23 elements. The results are summarized, combining the results of INAA conducted earlier by Ambiru et al. on 1,444 samples. The samples for these analyses are taken from seventy obsidian sources located at various places of Japan.

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Abstract  

To sophisticate the nuclear fuel recycling processes, the transfer percentages for Pd, Mo, Te, and Sb should be determined. Each element solution containing NaNO3 or HNO3 was fed consistently into the thin film evaporator regulated in vac and at 50 °C. The analyte percentages in the inside of the lid, in the condenser, and in the distillate were 10-1%/m2, 10-3%/m2, and 10-3% (DF = 105), respectively. The Mo percentage in the condenser was lower by a factor of 10 than those of other elements investigated. The NO3 - percentages were nearly constant despite increasing HNO3 concentrations, however, the ratios decreased with increasing NaNO3 concentrations.

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Abstract  

The amount of long-lived radioiodine, 129I (half-life 1.57·107 y) in the Japanese environment has been studied by measuring thyroids of humans and animals. The collected samples were thyroids of (1) humans in Ibaraki Prefecture, in Kanto district, the central part of Japan, (2) cattle in Aomori Prefecture, north part of Japan, and (3) wild deer in Chiba Prefecture, in Kanto district. The measured mean isotopic ratio 129I/127I for thyroids of cattle in Aomori Prefecture is 3.5±1.8·10-9. A higher value of 14±5·10-9 has been obtained for thyroids of wild deer in Kanto district. On the other hand, the measured ratio for human thyroids in Kanto district is 1±0.2·10-9. This value is significantly lower than that of cattle thyroids in Aomori and also those reported for human thyroids in Europe and USA. The higher mean ratio for cattle thyroid in Kanto district is possibly explained by the influence of nuclear reprocessing plant. Lower mean ratio for human thyroid might be due to higher dietary intake of algae.

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Abstract  

Reaction products of [2]ferrocenophane with CF3COOH, CCl3COOH, CF3SO3H and SbCl5 were prepared. Mössbauer spectroscopic data and magnetic susceptibility measurements suggest the bond formation of Fe–H+ and Fe–Cl+, in which iron atoms are in a high-spin Fe/II/state.

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Abstract  

To investigate the nm-size dependence of structural and thermal properties for AgI, the formation of composites between AgI and porous silica with controlled pore diameters of 10, 15, 30, and 50 nm was examined. The introduction of AgI within the micropores of the porous silica was performed successfully by a salt-bridge precipitation method with using AgNO3 and KI aqueous solutions. The AgI formed within the micropores was identified to be β/γ-AgI, independent of the pore size of 10-50 nm, by powder X-ray diffractometry. In differential scanning calorimetry, the composites showed thermal anomaly at around 150C on heating due to the phase transition from β/γ -AgI to α -AgI as in the case of bulk crystalline AgI (T trs=147C). However, the transition temperature from α-AgI to β/γ -AgI on cooling decreased remarkably with the decrease of the pore size from 50 to 10 nm. The result indicates the possibility for AgI particles with diameter less than 10 nm to exist as α -AgI even below 100C.

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Abstract  

A novel system using a potassium aluminosilicate electrolyte under applied potential that is able to split H2O (or OH) into H2 and 1/2O2 (or O2 2-) with higher yields than the value deduced from Faraday"s law is presented. There were three steps by which H2 and O2 were generated stoichiometrically, and it was predicted that the high yields were due to the occurrence of chemically endothermic reactions: dehydration of the catalytic cell at a temperature below 100C (step I), disproportionation of KOH (2KOH→H2+K2O2) at a temperature around 200C (step II), and disproportionation of K2O (2K2O→K2+K2O2) at a temperature above 500C (step III). So-called Nemca might be caused in the course of step III, since the rate of H2 was ca 102 times larger than the value deduced from Faraday"s law.

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Abstract  

A hexacyanoferrate(III) salt [N(C2H5)4]3[Fe(CN)6].5H2O (1)crystallized in a monoclinic space group (P21, Z = 2) with the nearest neighboring Fe-Fe distance of 8.20 Åound 1 distinctly showed magnetically-relaxed 57Fe Mössbauer spectra below ca. 40 K. The Mössbauer line width at 4.2 K was much larger than that of K3[Fe(CN)6], which is ascribable to the long Fe-Fe distance in 1. Further broadened spectra were observed for [N(n-C4H9)4]3[Fe(CN)6].xH2O (2).

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Simulation of the atmospheric dispersion of 85Kr from a reprocessing plant over a coastal area

Performance examination of an emergency environmental radiation dose evaluation code system, SIERRA-II

Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Takeyasu, T. Iida, H. Watanabe, M. Takeishi, and A. Yamamoto

Abstract  

The performance of the computer code system, SIERRA-II, for calculating the environmental radiation dose due to an accident was assessed over a coastal area, using the environmental monitoring data around the coastally located Tokai Reprocessing Plant (TRP) when 85Kr was discharged during its operation. The agreement within a factor of 5 between the calculated and observed air concentrations of 85Kr in areas of a few km from the TRP was achieved in 57% of the comparison data, disregarding the internal boundary layer. The mean fraction bias was −0.6, which meant a slight overestimation. According to the vertical profile of the atmospheric temperatures, the internal boundary layer was modeled with the SIERRA-II and the agreement became better than when the internal boundary layer was not considered.

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Abstract  

The back-extraction of uranium(VI) from di(2-ethylhexyl)phosphoric acid (HDEHP) and diisodecylphosphoric acid (DIDPA) was studied by using hydrazine carbonate as back-extractant. U(VI) was back-extracted from n-dodecane solutions of 0.5M HDEHP - 0.2M TBP and 0.5M DIDPA - 0.1M TBP by hydrazine carbonate. The distribution ratios were decreased with an increase of hydrazine carbonate concentration. The back-extraction equilibria were expressed by slope analysis in consideration of neutralization between the extractant (DIDPA, HDEHP) and hydrazine carbonate, which occurred quantitatively during the back-extraction.

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Abstract  

Back-extraction of tri- and tetravalent actinides from diisodecylphosphoric acid (DIDPA) is studied using hydrazine carbonate as back-extractant. In experiments using 0.5M DIDPA–0.1M TBP n-dodecane solution, Am(III), Eu(III), Pu(IV) and Np(IV) are back-extracted, and the distribution ratios are decreased with an increase of hydrazine carbonate concentration. The back-extraction equilibria are confirmed by slope analysis in consideration of neutralization between DIDPA and hydrazine carbonate, which occurs quantitatively during back-extraction. In particular, oxidation of Np(IV) to Np(V) during back-extraction is observed by measuring absorption spectra. The hydrazinium ion acts as an oxidation reagent in the back-extraction of Np(IV). Separation factors of those metals are compared with the results of HDEHP. Hydrazine carbonate back-extracts Np(IV) more selectively from DIDPA than from HDEHP.

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