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Abstract  

Chemical composition of 15 magnetic spherules collected from deep sea sediment was determined by instrumental neutron activation analysis (INAA) under two different irradiation conditions using the Kyoto University Reactor (KUR). Based on their chemical composition, nine spherules were judged to be of extraterrestrial origin. The differences in the chemical composition of the nine spherules are discussed in terms of condensation temperatures for the elements. Comparing the detection limits derived from INAA under two different irradiation conditions, the sensitivity for INAA using KUR is discussed.

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Abstract  

Adsorption behavior of fission products in nitric acid solution on various alloys and metals was studied by using a multitracer produced by neutron irradiation of UO2. The adsorption behavior of the fission products 99Mo, 131I, 132Te, 140La, and 143Ce, and 239Np was simultaneously studied. Some chemical decontamination tests were also examined. Clear adsorption of 99Mo, 131I, and 132Te was observed, whereas adsorption of 140La, 143Ce, and 239Np was not. The adsorption characteristics were discussed by considering anion-exchange reaction and surface complexation.

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Abstract  

Chemical compositions of spherules separated from deep sea sediment dredged off Hawaiian islands and from Antarctic ice were measured by instrumental neutron activation analysis (INAA) using Kyoto University Reactor (KUR). Iron, cobalt, nickel, iridium, scandium and manganese contents in those spherules were determined to be 19.3–97.7%, 23–4370 mg·kg−1, 0.08–7.04%, 0.84–35.4 mg·kg−1, 1.4–44.3 mg·kg−1 and 93.4 mg·kg−1–7.2 %, respectively, and compared with each other. Particularly, iridium was detected in seven spherules among fourteen from Hawaii, but only one spherule among twenty-two from Antarctic, and those spherules turned out to be extraterrestrial in origin. However, it was shown that there was little difference in characteristics of elemental contents between both kinds of spherules, except for Ir-detected spherules.

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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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Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Takamiya, R. Okumura, N. Abe, Y. Nakano, K. Miyata, S. Fukutani, A. Taniguchi, and H. Yamana

Abstract  

The new control system of pneumatic transportation apparatuses for neutron irradiation in Kyoto University Reactor (KUR) has been developed based on the TCP/IP network for the purpose of integrated management of the apparatus. The control system is comprised of PLCs, control PCs, database and web servers. Archiving logs of detailed information about irradiation enables the secure operation and management of the irradiation system. The information stored in the server can be referred by remote PCs and mobile phones through the internet. Combining the present facility with measurement and radiation management systems it can realize advanced INAA methods and secure managements of radioisotopes.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Takamiya, T. Fukunishi, R. Tsujito, S. Fukutani, T. Takahashi, S. Shibata, and S. Uchida

Abstract  

The adsorption behavior of fission products to various soils was studied using a multitracer. The multitracer was prepared by neutron irradiation of 235U. Distribution coefficients of fission products were obtained for seventeen kinds of Japanese soils. It was found that zirconium, niobium, and rare earth elements show high distribution coefficients for all soil samples, however, elements like alkali metals show varied values.

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Abstract  

The 63Ni in copper samples exposed by the Hiroshima atomic bomb was clearly measured for the first time by liquid scientillation method For the measurement, the chemical separation scheme previously developed was improved The obtained result was agreed with that estimated by the new dosimetry system for atomic bomb survivor studies, DS02.

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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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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Shibata, K. Takamiya, Y. Ota, N. Nogawa, Y. Ito, T. Shibata, M. Hoshi, S. Endo, H. Hasai, and S. Fujita
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Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Muroyama, A. Shinohara, T. Saito, A. Yokoyama, K. Takamiya, S. Morimoto, K. Nakanishi, H. Baba, T. Miura, Y. Hamajima, T. Kaneko, H. Muramatsu, S. Kojima, and M. Furukawa

Abstract  

Annihilation γ-rays of π0 and pionic X-rays were measured in the gas mixtures of H2+Z and CH4+Z systems (Z=He, Ne, Ar and Kr). Pion capture probability of hydrogen atom was obtained from the annihilation γ-ray counts and the capture probability of Z atom was obtained from the pionic X-ray intensities. Transfer rates were determined from the data based on a combined large mesomolecular model. The transfer rates obtained were smaller than the systematics of the Russian group. Difference in the transfer rate between the gas and the liquid phases was found by a comparison of the present results with our previous ones.

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