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Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.
JAEA-Research 2020-007, 249 Pages, 2020/10
JAEA-Research-2020-007.pdf:15.83MB
The accident of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, Japan Atomic Energy Agency (JAEA) has been conducting "Long-term Assessment of Transport of Radioactive Contaminants in the Environment of Fukushima" concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.
).Ito, Satomi; Sasaki, Yoshito; Niizato, Tadafumi; Watanabe, Takayoshi; Mitachi, Katsuaki*
KEK Proceedings 2019-2, p.132 - 137, 2019/11
no abstracts in English
Watanabe, Takayoshi; Sasaki, Yoshito; Niizato, Tadafumi; Mitachi, Katsuaki*; Ito, Satomi
KEK Proceedings 2019-2, p.114 - 119, 2019/11
no abstracts in English
Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.
JAEA-Research 2019-002, 235 Pages, 2019/08
JAEA-Research-2019-002.pdf:21.04MB
The accident of the Fukushima Daiichi Nuclear Power Station (hereinafter referred to 1F), Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, JAEA has been conducting Long-term Environmental Dynamics Research concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.
Watahiki, Shunsuke; Hanawa, Yoshio; Asano, Norikazu; Hiyama, Kazuhisa; Ito, Sachito; Tsuboi, Kazuaki; Fukasaku, Akitomi
JAEA-Review 2012-013, 92 Pages, 2012/03
JAEA-Review-2012-013.pdf:6.74MB
This replacement work was carried out under refurbishment plan of JMTR for beryllium distortion draw to acceptable limit. And gamma-ray shield refurbishment was carried out the view point of prevention maintenance in consideration of operation plan. Fabrication of beryllium frame and gamma-ray shield was spent for two years it was finished in February, 2010. It took five months to replacement work from January 2010. In this report is presented fabrication and replacement work of beryllium frame and gamma-ray shield.
Sn conductors for ITER Toroidal Field coilsTakahashi, Yoshikazu; Isono, Takaaki; Hamada, Kazuya; Nunoya, Yoshihiko; Nabara, Yoshihiro; Matsui, Kunihiro; Hemmi, Tsutomu; Kawano, Katsumi; Koizumi, Norikiyo; Oshikiri, Masayuki; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
Japan Atomic Energy Agency is procuring the NbSn superconductors for Toroidal Field (TF) coils under the ITER project. Because manufacturing amount of NbSn strands is quite large compared with the past experience and required superconducting performance is higher than that of the model coils which have been fabricated and tested in the ITER-EDA, quality control technique is very important for the manufacture of the strands. Sophisticated control technique is also required for the jacketing, in order to fabricate the conductors with the precise outer diameter and without leakage at welding part. Cu dummy conductor with full length (760 m) has been fabricated successfully and all jacketing technology was confirmed through this fabrication. The fabrication of the NbSn conductor for TF coils will start in March 2010.
Sn superconducting conductors in ITERNabara, Yoshihiro; Isono, Takaaki; Nunoya, Yoshihiko; Koizumi, Norikiyo; Hamada, Kazuya; Matsui, Kunihiro; Hemmi, Tsutomu; Kawano, Katsumi; Uno, Yasuhiro*; Seki, Shuichi*; et al.
Journal of Plasma and Fusion Research SERIES, Vol.9, p.270 - 275, 2010/08
Sena, C.*; Molinero, J.*; Nagaoka, Toru*; Ajima, Shuji*; Ito, Tsuyoshi; Sasaki, Yoshito; Asano, Takahiro; Yoshikawa, Hideki
no journal, ,
Sasaki, Yoshito; Ito, Tsuyoshi; Asano, Takahiro; Yoshikawa, Hideki
no journal, ,
no abstracts in English
Yoshikawa, Hideki; Sasaki, Yoshito; Asano, Takahiro; Ito, Tsuyoshi; Yui, Mikazu
no journal, ,
no abstracts in English
Iwatsuki, Teruki; Sasaki, Yoshito; Ito, Tsuyoshi; Asano, Takahiro; Amano, Yuki; Yoshikawa, Hideki; Nakamura, Takamichi*; Nagaoka, Toru*
no journal, ,
Microbial activities and the reaction processes with groundwater and rock minerals up to 500 m below ground level were studied to infer the redox process and buffer capacity of rock materials for the articifitial disturbance such as facility construction at subsurface. Based on results of observation at in-situ and batch experiments, the geochemical modelling using PHREEQC-2 was carried out to develop the numerical simulation techniques on water-rock-microbe interaction system.
Sn superconducting strand for ITER TF coilNabara, Yoshihiro; Isono, Takaaki; Nunoya, Yoshihiko; Koizumi, Norikiyo; Hamada, Kazuya; Matsui, Kunihiro; Hemmi, Tsutomu; Oshikiri, Masayuki; Uno, Yasuhiro*; Seki, Shuichi*; et al.
no journal, ,
no abstracts in English
Yoshikawa, Hideki; Ito, Tsuyoshi; Sasaki, Yoshito; Asano, Takahiro*; Nagaoka, Toru*; Nakamura, Takamichi*
no journal, ,
This report shows that PHREEQC-2 code are used to analyzed a laboratory experimental for water-microbe interaction using a microbe collected from groundwater of Horonobe area, in order to evaluate influence by the microbe activity on the chemical composition of the water to contribute to the performance assessment of the disposal of the high-level radioactive waste. As a results, we understood that behavior such as the oxygen consumption could be estimated with the microbe influence.
Ito, Tsuyoshi; Sasaki, Yoshito; Amano, Yuki; Iwatsuki, Teruki; Yoshikawa, Hideki
no journal, ,
no abstracts in English
Yoshikawa, Hideki; Sasaki, Yoshito; Ito, Tsuyoshi; Amano, Yuki; Iwatsuki, Teruki
no journal, ,
no abstracts in English
Nagaoka, Toru*; Nakamura, Takamichi*; Sasaki, Yoshito; Asano, Takahiro*; Ito, Tsuyoshi*; Amano, Yuki; Iwatsuki, Teruki; Yoshikawa, Hideki
no journal, ,
Laboratory jar experiment was conducted with deep subsurface sedimentary rock and groundwater, in order to assess the response of the geochemical and microbial communities toward redox processes. The redox process was induced by exposure to air and discontinuation to sediment suspension, which simulated the process occurring during operation of nuclear waste repositories. As a results, after discontinuation of air exposure with lactate amendment, redox potentials decreased from ca. +100 mV to -600 m V (vs. Ag/AgCl), and some sequential terminal electron-accepting process (TEAPs) was observed with the reactions of aerobic respiration, iron reduction and hygrogen fermentation. The related species of the microbes along with TEAPs, e.g., Pseudomonas sp. for aerobic respiration and Shewanella sp. for iron reduction, was also detected. These results indicated that the microbial activities would affect the geochemical changes in nuclear repositories.
Yoshikawa, Hideki; Amano, Yuki; Sasaki, Yoshito; Ito, Tsuyoshi*; Ise, Kotaro; Iwatsuki, Teruki
no journal, ,
An insite experiment was conducted to understand for microbial effect on backfill of 140m underground tunnel, the contribution of the microbial reaction in backfill material on redox change of the tunnel environment was suggested.
Niizato, Tadafumi; Sasaki, Yoshito; Watanabe, Takayoshi; Mitachi, Katsuaki*; Ito, Satomi; Kuramoto, Takayuki*; Arai, Hirotsugu*; Nomura, Naoki*; Hayashi, Seiji*; Tamaoki, Masanori*
no journal, ,
Cs released from the TEPCO's Fukushima Dai-ichi Nuclear Power Plant accident has a long half-life of about 30 years, it is necessary to monitor the distribution and its radioecological impact over the long term. Mountainous forests, which accounts for about 70% of Fukushima prefecture, tend to be a sink of radiocesium contamination rather than a source for the contamination of other ecosystems. An understanding of the environmental dynamics of radiocesium in the forest floor of various conditions is important issue, while progressing to the resident return. In this paper, we report on the results of the field investigation into the Cs distribution and the Cs outflow in the mountainous forest of Fukushima, where the wildfire broke out in the spring of 2017.
Niizato, Tadafumi; Watanabe, Takayoshi; Mitachi, Katsuaki*; Sasaki, Yoshito; Ito, Satomi; Abe, Hironobu
no journal, ,
An understanding of long-term environmental dynamics of radiocesium, which is released by the TEPCO's Fukushima Dai-ichi Nuclear Power Plant accident, is a key issue for predicting the future radiocesium distribution and forest products radioactivity in a forested environment, especially Cs with half-life of 30 years. We compiled the five-years monitoring results of radiocesium input-output budgets in broad-leaved deciduous forests and Japanese cedar evergreen forests of the Abukuma Mountains, Fukushima, Japan. The input-output rates were a few percent of the radiocesium inventory of the monitoring site. In addition, both rates have been decreasing with time. Belowground radiocesium occupied 90% of the total inventory in the Japanese cedar forest on October 2015. The belowground radiocesium was distributed mainly in the topsoil of 0-6 cm depth, approximately 70-80% of the underground inventory on August 2016. These results indicate that the distribution of radiocesium in the forest is similar to the distribution of tree rootlet responsible for absorption of inorganic elements, nutrients, and water. This means long residence time of radiocesium in rooting zone. In the condition of the limited amount of radiocesium input-output rates in the forest, estimation of the migration flux of radiocesium from forest floor to the forest products are considered to be most important issues in the present.
Sasaki, Yoshito; Niizato, Tadafumi; Mitachi, Katsuaki*; Ito, Satomi; Watanabe, Takayoshi
no journal, ,
no abstracts in English
