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Kokubun, Yuji; Nakada, Akira; Seya, Natsumi; Koike, Yuko; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; Nagai, Shinji; et al.
JAEA-Review 2023-046, 164 Pages, 2024/03
The Nuclear Fuel Cycle Engineering Laboratories conducts environmental radiation monitoring around the reprocessing plant in accordance with the "Safety Regulations for Reprocessing Plant of JAEA, Part IV: Environmental Monitoring". This report summarizes the results of environmental radiation monitoring conducted during the period from April 2022 to March 2023 and the results of dose calculations for the surrounding public due to the release of radioactive materials into the atmosphere and ocean. In the results of the above environmental radiation monitoring, many items were affected by radioactive materials emitted from the accident at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company, Incorporated (changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016), which occurred in March 2011. Also included as appendices are an overview of the environmental monitoring plan, an overview of measurement methods, measurement results and their changes over time, meteorological statistics results, radioactive waste release status, and an evaluation of the data which deviated of the normal range.
Saito, Yuki*; Ishiwata, Tobimaru*; Horiuchi, Misato*; Nishiki, Yuto*; Kikuchi, Ryosuke*; Otake, Tsubasa*; Kawakita, Ryohei; Takayama, Yusuke; Mitsui, Seiichiro; Sato, Tsutomu*
Shigen, Sozai Koenshu (Internet), 11(1), 7 Pages, 2024/03
no abstracts in English
Nakada, Akira; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Futagawa, Kazuo; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; et al.
JAEA-Review 2022-078, 164 Pages, 2023/03
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2021 to March 2022. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.
Kawakita, Ryohei; Saito, Akito*; Sakuma, Hiroshi*; Anraku, Sohtaro; Kikuchi, Ryosuke*; Otake, Tsubasa*; Sato, Tsutomu*
Applied Clay Science, 231, p.106722_1 - 106722_7, 2023/01
Times Cited Count:1 Percentile:17.48(Chemistry, Physical)Nakada, Akira; Nakano, Masanao; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Nemoto, Masashi; Tobita, Keiji; Futagawa, Kazuo; Yamada, Ryohei; Uchiyama, Rei; et al.
JAEA-Review 2021-062, 163 Pages, 2022/02
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2020 to March 2021. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.
Yada, Ryuichi*; Maenaka, Kazusuke*; Miyamoto, Shuji*; Okada, Go*; Sasakura, Aki*; Ashida, Motoi*; Adachi, Masashi*; Sato, Tatsuhiko; Wang, T.*; Akasaka, Hiroaki*; et al.
Medical Physics, 47(10), p.5235 - 5249, 2020/10
Times Cited Count:7 Percentile:50.46(Radiology, Nuclear Medicine & Medical Imaging)The dosimeter system is capable of real-time, accurate, and precise measurement under stereotactic body radiation therapy (SBRT) conditions. The probe is smaller than a conventional dosimeter, has excellent spatial resolution, and can be valuable in SBRT with a steep dose distribution over a small field. The developed PSP dosimeter system appears to be suitable for in vivo SBRT dosimetry.
Sakai, Akihiro; Kurosawa, Ryohei*; Nakata, Hisakazu; Okada, Shota; Izumo, Sari; Sato, Makoto*; Kitamura, Yoichi*; Honda, Yasutake*; Takaoka, Katsuki*; Amazawa, Hiroya
JAEA-Technology 2016-019, 134 Pages, 2016/10
Japan Atomic Energy Agency has been developing to design trench disposal facility with impermeable layers in order to dispose of miscellaneous waste. Geomembrane liners have a function that prevent seepage of leachant and collect the leachant. However, the geomembrane liners do not necessarily provide the expected performance due to damage generated when heavy equipment contacts with the liner. Therefore, we studied the impermeable layers having high performance of preventing seepage of leachant including radioactivity taking into account characteristics of low permeable materials and effect of multiple layer structure. As results, we have evaluated that the composite layers composed by a drainage layer, geomembrane liners and a low permeable layer are most effective structure to prevent seepage of leachant. Taking into account disposal of waste including cesium, we also considered zeolite containing sheets for adsorption of cesium were installed in the impermeable layers.
Yoshihara, Ryohei; Hase, Yoshihiro; Sato, Ryohei*; Takimoto, Koichi*; Narumi, Issei
International Journal of Radiation Biology, 86(2), p.125 - 131, 2010/02
Times Cited Count:21 Percentile:79.92(Biology)In an effort to assess the characteristics of mutation induced by different LET radiation in higher plants, the mutational effects of carbon-ion beams and -rays were investigated in . The transgenic (Arabidopsis/rpsL) mutation detection system was adopted. Dry seeds of Arabidopsis/rpsL were irradiated with -rays and 208-MeV carbon ions (208-MeV C), and the mutation frequency and mutation spectrum were examined. Our result suggested that 208-MeV C and -rays induced different mutational effects in dry seed.
Yoshihara, Ryohei; Nakane, Chiyoko*; Sato, Ryohei*; Yasuda, Ai*; Takimoto, Koichi*
Genes and Environment, 30(2), p.53 - 61, 2008/05
We generated a CPD photolyase knock-down in by RNAi to investigate the role of CPD photorepair for protection of plants from solar UV. These knock-down lines exhibited hypersensitivity to UV-B and an increased occurrence of mutation induced by UV-B radiation compared with proficient in CPD photolyase. These results indicate that CPD photoreactivation plays an important role for UV resistance of and suppression of UV-induced mutagenesis.
Nishitani, Takeo; Ochiai, Kentaro; Yoshida, Shigeo*; Tanaka, Ryohei*; Wakisaka, Masashi*; Nakao, Makoto*; Sato, Satoshi; Yamauchi, Michinori*; Hori, Junichi; Wada, Masayuki*; et al.
Journal of Nuclear Science and Technology, 41(Suppl.4), p.58 - 61, 2004/03
no abstracts in English
Yoshida, Shigeo*; Nishitani, Takeo; Ochiai, Kentaro; Kaneko, Junichi*; Hori, Junichi; Sato, Satoshi; Yamauchi, Michinori*; Tanaka, Ryohei*; Nakao, Makoto*; Wada, Masayuki*; et al.
Fusion Engineering and Design, 69(1-4), p.637 - 641, 2003/09
Times Cited Count:9 Percentile:53.15(Nuclear Science & Technology)no abstracts in English
Tanaka, Ryohei*; Ochiai, Kentaro; Nakao, Makoto*; Yamauchi, Michinori*; Hori, Junichi; Wada, Masayuki*; Sato, Satoshi; Nishitani, Takeo
JAERI-Tech 2003-063, 62 Pages, 2003/07
no abstracts in English
Nishitani, Takeo; Ochiai, Kentaro; Yoshida, Shigeo*; Tanaka, Ryohei*; Wakisaka, Masashi*; Nakao, Makoto*; Sato, Satoshi; Yamauchi, Michinori*; Hori, Junichi; Takahashi, Akito*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 79(3), p.282 - 289, 2003/03
no abstracts in English
Ishiwata, Tobimaru*; Kikuchi, Ryosuke*; Otake, Tsubasa*; Sato, Tsutomu*; Kawakita, Ryohei; Takayama, Yusuke; Mitsui, Seiichiro
no journal, ,
It is known that the cementation of bentontie may cause the reduction of swelling pressure. However, fundamental mechanism of this reducing swelling pressure has not been well understood. To understand the mechanism, it is essential to identify the cementitious materials and observe the changes in microstructure associated with cementation. In this study, the microstructural observation and swelling tests were conducted on several bentonite ores collected from Tsukinuno Mine in Yamagata Prefecture, Japan, as natural analog of cementation, and the relationship between petrographic texture and swelling pressure was discussed. Thin sections of bentonite ores were prepared by dry polishing technique to observe flat surfaces in micro scales. Scanning electron microscopy (SEM) demonstrated the widespread distribution of authigenic, a few micron silica in the matrix of montmorillonite. Transmission electron microscopy (TEM) revealed that the micro silica minerals (commonly quartz and less commonly amorphous silica) adhered to the edge of montmorillonite grains. These observations suggest that the adherence of these cementitious materials to montmorillonite prevents water access to the interlayer of montmorillonite and swelling, resulting in a decrease in swelling pressure. While these microstructures were observed commonly in all samples collected from several bentonite beds, the relative abundance of montmorillonite and micro silica minerals varied among different beds. It is possible that the swelling pressure in the cemented bentonite is affected by the relative abundance of montmorillonite and cementitious materials.
Kawakita, Ryohei*; Saito, Akito*; Sakuma, Hiroshi*; Anraku, Sohtaro; Oda, Chie; Mihara, Morihiro; Sato, Tsutomu*
no journal, ,
no abstracts in English
Takahashi, Ryohei*; Hirayama, Tomoko*; Tamura, Kazushi*; Sato, Nobuhiro*; Sugiyama, Masaaki*; Oba, Yojiro
no journal, ,
Viscosity index improvers (VII) are important additives for lubricants to suppress the temperature dependence of viscosity index. Although the temperature dependence of viscosity index of VII was thought to be related with the temperature dependence of nanostructures, only a few experimental results have been reported so far. Therefore, we performed small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) to characterize the nanostructures of VII in the lubricant. The results show the change in molecular size with increasing temperature. The relation between the viscosity index and the nanostructures are discussed.
Watanabe, So; Okada, Makoto*; Matsuura, Haruaki*; Kada, Wataru*; Koka, Masashi*; Yamagata, Ryohei*; Yamada, Naoto*; Sato, Takahiro*; Ishii, Yasuyuki*
no journal, ,
no abstracts in English
Takahashi, Ryohei*; Hirayama, Tomoko*; Sato, Nobuhiro*; Sugiyama, Masaaki*; Takashima, Yoriyuki*; Nakano, Taeko*; Tamura, Kazushi*; Oba, Yojiro
no journal, ,
no abstracts in English
Sato, Yusuke*; Maeda, Tomoo*; Honda, Kazushige*; Saga, Koichi*; Ishikawa, Ryuji*; Akita, Yusuke; Yoshihara, Ryohei; Nozawa, Shigeki; Narumi, Issei
no journal, ,
no abstracts in English
Sakurai, Eiko*; Yanai, Kazuhiko*; Ishii, Keizo*; Oyama, Ryohei*; Sakamaki, Manabu*; Yamanaka, Kentaro*; Yamazaki, Hiromichi*; Matsuyama, Shigeo*; Kamiya, Tomihiro; Sato, Takahiro; et al.
no journal, ,
no abstracts in English