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Abstract  

Dr. S. Iimori and Prof. K. Kimura played an important pioneering role in the early period of Japanese history of nuclear and radiochemistry. A review is presented of the life and the work of these pioneers during the first half of the 20th century.

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Abstract  

Gas-chromatographic behavior of halides of arsenic and phosphorus and isotope exchange reactions among these species were investigated by means of radiotracer techniques. The halides studied in the present work include AsCl3, AsBr3, PBr3,76AsBr3,76AsCl3, and As82Br3. It was demonstrated that the rapid isotope exchange of arsenic and bromine took place in the binary systems: AsBr3−AsCl3 and AsBr3−PBr3, in the course of the gas-chromatographic separation process.

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Abstract  

Applying rapid radiochemical separation of iodine coupled with epithermal neutron activation, we reliably determined trace amounts /6–95 ng/ of iodine in rock samples such as sedimentary rocks and chondritic meteorites. Our data on meteorites are in good agreement with literature values, but for sedimentary rocks the present data were systematically lower than the literature values. Based on the data from duplicate analyses of some sedimentary rocks and the results of tracer experiments employed parallel to the rock analyses, we concluded that the analytical results obtained in this work for sedimentary rocks were more reliable than the literature values.

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Abstract  

SuperLig® 644 resin was exposed to simulated Hanford waste solution under air atmosphere or in protated inert environment, and in 0.5M HNO3 solution for 15 days and 45 °C. The degradation was evaluated by cesium batch distribution measurement.

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Abstract  

The reaction of238U with12C was studied radiochemically with the purpose of elucidating fast fission characteristics. Fast fission component was extracted in far-asymmetric mass region and interpreted as the mass diffusion following the Fokker-Planck equation. Anomalous charge dispersion widths in the corresponding mass region and a sudden increase of the whole mass distribution width at the critical energy were also observed to support the above interpretation. The reaction time of fast fission was determined to be 5·10−21 s from the width and position of the mass distribution.

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Abstract  

Batch kinetic and column experiments have been carried out at 25, 35, and 45 °C to examine the effect of temperature on SuperLig® 644 cesium (Cs) removal from simulated Hanford tank waste supernate. The simulated solution mimicked the composition of the low-activity waste supernate from tank 241-AN-105 in the U.S. DOE Hanford site. Small quantities of toxic metals, such as Cd, Cr, Fe, and Pb were spiked into the simulant to evaluate the metal's competitiveness with Cs for sorption on SuperLig® 644 resin. The results indicated that the temperature affects the removal of Cs and metal ions, although the effect was not the same for all metal ions. The extent of Cs removal decreased with an increase in temperature. The Cs capacity at breakthrough point was 0.015, 0.013, and 0.011-mmole/g dry resin at 25, 35 and 45 °C, respectively. The column was effectively eluted to less than 1% (0.1 C/C 0) of the feed concentration with approximately 10 BVs of 0.5M nitric acid. The resin showed limited affinity for toxic metal ions (Cr, Cd, Fe, and Pb) as compared to Cs. Based on the batch kinetic data, the Cs uptake of the resin was not hampered by the presence of the toxic metals in solution.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Takamiya, T. Inoue, K. Nakanishi, A. Yokoyama, N. Takahashi, T. Saito, H. Baba, and Y. Nakagome

Abstract  

In order to estimate the deformation rate of fission fragment at the scission point for thermal neutron-induced fission of233,235U and239Pu, double-velocity and double-energy measurements were carried out. As the result of the estimation of the deformation rate, two types of scission point configurations were found. One type is composed of deformed light and heavy fragments, and the other type is a combination of deformed light and spherical heavy fragments. Mass and total kinetic energy distributions were sorted in two distributions by means of the type of configuration.

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Abstract  

The role of the charge degree of freedom in the heavy-ion-induced fission was investigated by carrying out a systematic analysis of radiochemically observed charge distribution in the fission of238U with12C ions of the incident energy between 85 and 140 MeV, particularly in connection with the energy given to the compound system. The charge distribution was found to follow essentially identical systematics as those which govern the light-ion fission except for the extremely weak energy dependence of the most probable chargeZ p. That is, values of the derivative ofZ p with respect to the energy were found to be quite small, or nearly zero, in the heavy-ion fission as compared to those of the light-ion fission. According to an analysis combining the derivatives ofZ p and fission neutron data, it was deduced that the excess energy given to the fused system was spent completely in the form of pre-scission neutrons and hence the number of post-scission neutrons remained constant as in the case of light-ion fission. The observed charge distribution was reproduced under the conditions that the relaxation of the charge degree of freedom be very fast and that the separation between the two potential fragments at the moment when the charge degree of freedom has been frozen is determined by usingViola's systematics on the fragment kinetic energy.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Saito, J. Wang, T. Kitazawa, M. Takahashi, M. Takeda, M. Nakada, T. Nakamoto, N. Masaki, T. Yamashita, and M. Saeki

Abstract  

Four types of neptunyl(VI) hydroxides have been synthesized by chemical oxidation of Np(IV) instead of ozone oxidation of Np(V) which caused the partial oxidation to the heptavalent state. NpO2(OH)2 (I) and NpO2(OH)2·H2O (orthorhombic type) (II) have been obtained by adding pyridine to the solution at 373K and 343K, respectively. NpO2(OH)2·H2O (hexagonal type) (III) and NpO2(OH)2·xH2yNH3 (x+y=1) (IV) have been prepared by using LiOH and NH4OH, respectively. The four materials have been characterized by X-ray powder diffraction patterns, thermogravimetric analysis and237Np Mössbauer spectra. The237Np Mössbauer spectrum of (I) measured first time as anhydrous neptunyl(VI) hydroxide (δ=−46.2 mm/s,e 2 qQ=193 mm/s and η=0.16 at 4.8K) has more distinct five-line Mössbauer pattern than those of (II), (III) and (IV). The Mössbauer spectra for (II), (III) and (IV) are slightly different from each other. The structural information has been obtained from these data.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Tanoi, H. Matsue, H. Iikura, T. Saito, Y. Hayashi, Y. Hamada, H. Nishiyama, N. Kobayashi, and T. Nakanishi

Abstract  

We carried out instrumental neutron activation analysis (INAA) as well as k 0-based prompt gamma-ray analysis (k 0-PGA) to measure the amount of the elements in onions and studied whether the onions collected from different sites can be categorized based on the elemental concentration profile. Six elements (Na, Mg, Cl, K, Ca, Mn) and 3 elements (B, S, Cl) were measured by INAA and PGA in the onions grown in two districts, Hokkaido and Saga, in Japan, respectively. After principal component analysis, it was found that Cl was an important element to feature the producing districts of onions.

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