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Onuki, Toshihiko; Sakamoto, Fuminori; Kozai, Naofumi; Namba, Kenji*; Neda, Hitoshi*; Sasaki, Yoshito; Niizato, Tadafumi; Watanabe, Naoko*; Kozaki, Tamotsu*
Environmental Science; Processes & Impacts, 21(7), p.1164 - 1173, 2019/07
Times Cited Count:10 Percentile:44.69(Chemistry, Analytical)The fate of radioactive Cs deposited after the Fukushima nuclear power plant accident and its associated radiological impacts are largely dependent on its mobility from surface soils to forest ecosystems. We measured the accumulation of radioactive Cs in the fruit bodies of wild fungi in the forest at Iidate, Fukushima, Japan. The transfer factors (TFs) of radioactive Cs from soil to the fruit bodies of wild fungi were between 10 to 10, a range similar to those reported for the fruit bodies collected in Europe after the Chernobyl accident and in parts of Japan contaminated by nuclear bomb test fallout. Comparison of the TFs of the wild mushroom and that of the fungal hyphae of 704 stock strains grown on agar medium containing nutrients and radioactive Cs showed that the TFs of wild mushroom were lower. TF was less than 0.1 after addition of the minerals zeolite, vermiculite, phlogopite, smectite, or illite of 1% weight to the agar medium. These results indicate that the presence of minerals decrease Cs uptake by fungi grown in the agar medium.
Takahara, Shogo; Ikegami, Maiko*; Yoneda, Minoru*; Kondo, Hitoshi*; Ishizaki, Azusa; Iijima, Masashi; Shimada, Yoko*; Matsui, Yasuto*
Risk Analysis, 37(7), p.1256 - 1267, 2017/07
Times Cited Count:6 Percentile:52.04(Public, Environmental & Occupational Health)Takahara, Shogo; Ikegami, Maiko*; Yoneda, Minoru*; Kondo, Hitoshi*; Ishizaki, Azusa; Shimada, Yoko*
Dai-21-Kai Chikasui, Dojo Osen To Sono Boshi Taisaku Ni Kansuru Kenkyu Shukai Koenshu (CD-ROM), p.505 - 510, 2015/06
Doses received by the public are necessary information in management of radiation exposures in areas contaminated by the Fukushima Daiichi Nuclear Power Plant (1F) accident. Direct ingestion of contaminated soil is one of the exposure pathways which is a concern for the people living in the areas in terms of children's exposure. Therefore in order to manage efficiently the middle and the long term exposures with a sense of safety of the people, we have to clarify the contribution of this pathway to the doses received by those. However, a fractional absorption of radioactive cesium in gastrointestinal system has not been evaluated yet. We evaluated this factor based on the results of a physiologically based extraction test and an extraction test with hydrochloric acid, which is adopted in Japanese national law to evaluate a fractional absorption of heavy metals in gastrointestinal system. In addition, we assessed the doses to the public from this pathway after the 1F accident.
Katsura, Tomoo*; Yamada, Hitoshi*; Shimmei, Toru*; Kubo, Atsushi*; Ono, Shigeaki*; Kanzaki, Masami*; Yoneda, Akira*; Walter, M. J.*; Ito, Eiji*; Urakawa, Satoru*; et al.
Physics of the Earth and Planetary Interiors, 136(1-2), p.11 - 24, 2003/04
Times Cited Count:173 Percentile:93.74(Geochemistry & Geophysics)no abstracts in English
Sakamoto, Fuminori; Onuki, Toshihiko; Kozai, Naofumi; Neda, Hitoshi*; Kumata, Atsushi*; Shiina, Kazuhiro; Tanaka, Kenji; Namekawa, Jun
no journal, ,
no abstracts in English
Kaneda, Tomohiro*; Yokoyama, Kenichi*; Ishijima, Yasuhiro; Ueno, Fumiyoshi; Abe, Hitoshi
no journal, ,
In spent nuclear fuel reprocessing plant, Zr/Ta dissimilar metal joint is used for connect between different devices. And it is known that Zr and Ta have susceptibility of hydrogen embrittlement. The other hand, Zr and Ta are alloyed in the dissimilar joint and it is not clear that the hydrogen embrittlement behavior of the Zr-Ta alloy. This study aims to elucidate the hydrogen embrittle behavior of the Zr-Ta alloy. Tensile tests and X-ray diffraction (XRD) were carried out after hydrogen charging in 0.9% NaCl solution. The zirconium hydride was detected by XRD analysis but embrittlement was not shown by tensile tests. However, brittle fracture patterns were observed by SEM observation at the fracture surface the specimen after tensile test. It is consider that these results suggest the zirconium hydride that formed by hydrogen charging dominates the hydrogen embrittlement behavior of the Zr-Ta alloy.
Kaneda, Tomohiro*; Yokoyama, Kenichi*; Ishijima, Yasuhiro; Ueno, Fumiyoshi; Abe, Hitoshi
no journal, ,
In spent nuclear fuel reprocessing plant, Zr/Ta dissimilar metal joint is used for connect between different devices. And it is known that Zr and Ta have susceptibility of hydrogen embrittlement. The other hand, Zr and Ta are alloyed in the dissimilar joint and it is not clear that the hydrogen embrittlement behavior of the Zr-Ta alloy. This study aims to elucidate the hydrogen embrittle behavior of the Zr-Ta alloy. Tensile tests and X-ray diffraction (XRD) were carried out after hydrogen charging in 0.9% NaCl solution. The zirconium hydride was detected by XRD analysis but embrittlement was not shown by tensile tests. However, brittle fracture patterns were observed by SEM observation at the fracture surface the specimen after tensile test. It is consider that these results suggest the zirconium hydride that formed by hydrogen charging dominates the hydrogen embrittlement behavior of the Zr-Ta alloy.
Kaneda, Tomohiro*; Yokoyama, Kenichi*; Ishijima, Yasuhiro; Ueno, Fumiyoshi; Abe, Hitoshi
no journal, ,
In spent nuclear fuel reprocessing plant, Zr/Ta dissimilar metal joint is used for connect between different devices. And it is known that Ta have susceptibility of hydrogen embrittlement. The other hand, it is not clear that relationship between hydrogen desorption behavior and hydrogen existing state in Ta. This study aims to elucidate the effect of environment for hydrogen desorption behavior on Ta. Thermal desorption spectroscopy (TDS) were carried out after hydrogen charging in 0.9% NaCl solution. Hydrogen desorption started at 873K, 673K and 573K in air, Ar and ultra-high vacuum environment respectively. After TDS in air environment, specimen was covered with TaO film. After removal of the film, hydrogen desorption was observed from 773K in argon environment. These results suggest that the generation of the TaO film suppresses the hydrogen desorption from Ta. And it shows that when considering the relationship between the existence state of hydrogen in Ta with thermal aging, it is necessary to consider the influence of the TaO film.