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Yomogida, Takumi; Ouchi, Kazuki; Morii, Shiori; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
Scientific Reports (Internet), 14, p.14945_1 - 14945_11, 2024/06
Times Cited Count：1 Percentile：31.14(Multidisciplinary Sciences)Particles containing alpha (
) nuclides were identified from sediment in stagnant water in the Unit 3 reactor building of the Fukushima Daiichi Nuclear Power Station (FDiNPS). We analyzed different concentrations of alpha nuclides samples collected at two sampling sites, torus room and Main steam isolation valve (MSIV) room. Most of the -nuclides in the stagnant water samples of the torus room and the MSIV room were present in particle fractions larger than 10 
m. We detected uranium-bearing particles in m-size by scanning electron microscopy-energy dispersive X-Ray (SEM-EDX) observation. Other short lived -nuclides were detected by alpha track detection. The -nuclide-containing particles with several tens to several hundred m in size were mainly comprised iron (Fe) by SEM-EDX analysis. This study clarifies that the morphologies of U and other -nuclides in the sediment of stagnant water in the FDiNPS's Unit 3 reactor building.
Warashina, Tomoro*; Sato, Asako*; Hinai, Hiroshi; Shaikhutdinov, N.*; Shagimardanova, E.*; Mori, Hiroshi*; Tamaki, Satoshi*; Saito, Motofumi*; Sanada, Yukihisa; Sasaki, Yoshito; et al.
Applied and Environmental Microbiology, 90(4), p.e02113-23_1 - e02113-23_23, 2024/04
Times Cited Count：0 Percentile：0.00(Biotechnology & Applied Microbiology)Yamada, Kazuo*; Hokora, Hideyuki*; Maruyama, Ippei*; Aihara, Haruka; Tomita, Sayuri*; Tojo, Yasumasa*; Shibuya, Kazutoshi*; Hosokawa, Yoshifumi*; Igarashi, Go*; Koma, Yoshikazu
Proceedings of Waste Management Symposia 2024 (WM2024) (Internet), 7 Pages, 2024/03
Katsumura, Kosuke*; Takagi, Junichi*; Hosomi, Kenji*; Miyahara, Naoya*; Koma, Yoshikazu; Imoto, Jumpei; Karasawa, Hidetoshi; Miwa, Shuhei; Shiotsu, Hiroyuki; Hidaka, Akihide*; et al.
Nihon Genshiryoku Gakkai-Shi ATOMO
, 65(11), p.674 - 679, 2023/11
no abstracts in English
Yamada, Kazuo*; Tojo, Yasumasa*; Aihara, Haruka; Tomita, Sayuri*; Hokora, Hideyuki*; Shibuya, Kazutoshi*; Koma, Yoshikazu; Igarashi, Go*; Hosokawa, Yoshifumi*; Maruyama, Ippei*
Proceedings of Waste Management Symposia 2023 (WM2023) (Internet), 12 Pages, 2023/02
Strand, P.*; Jefferies, N.*; Koma, Yoshikazu; Plyer, J.*
Journal of Radiological Protection, 42(2), p.020501_1 - 020501_16, 2022/06
Times Cited Count：2 Percentile：28.39(Environmental Sciences)Yomogida, Takumi; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*
Scientific Reports (Internet), 12(1), p.7191_1 - 7191_10, 2022/05
Times Cited Count：9 Percentile：55.41(Multidisciplinary Sciences)Particles containing alpha () nuclides were identified from sediment in stagnant water at the torus room of the Fukushima Dai-ichi Nuclear Power Station (FDiNPS)'s Unit 2 reactor. Several uranium-bearing particles were identified by SEM observation. These particles contained Zr and other elements which constituted fuel cladding and structural materials. The 
U/
U isotope ratio in the solid fractions that included U particles was consistent with the nuclear fuel in the Unit 2 reactor, which indicated that the U particles had been derived from nuclear fuel. The particles with alpha-emitters detected by alpha track analysis were several tens to several hundred m in size. The EDX spectra showed that these particles mainly comprised iron, which indicated Pu, Am, and Cm were adsorbed on the Fe-baring particles. This study clarifies that the major morphologies of U and other -nuclides were differed in the sediment of stagnant water in the torus room of FDiNPS's Unit 2 reactor.
Grambow, B.; Nitta, Ayako; Shibata, Atsuhiro; Koma, Yoshikazu; Utsunomiya, Satoshi*; Takami, Ryu*; Fueda, Kazuki*; Onuki, Toshihiko*; Jegou, C.*; Laffolley, H.*; et al.
Journal of Nuclear Science and Technology, 59(1), p.1 - 24, 2022/01
Times Cited Count：32 Percentile：76.55(Nuclear Science & Technology)Pyke, C. K.*; Hiller, P. J.*; Koma, Yoshikazu; Oki, Keiichi
Nuclear Engineering and Technology, 54(1), p.414 - 422, 2022/01
Times Cited Count：3 Percentile：41.50(Nuclear Science & Technology)Igarashi, Go*; Haga, Kazuko*; Yamada, Kazuo*; Aihara, Haruka; Shibata, Atsuhiro; Koma, Yoshikazu; Maruyama, Ippei*
Journal of Advanced Concrete Technology, 19(9), p.950 - 976, 2021/09
Times Cited Count：5 Percentile：24.97(Construction & Building Technology)Sugiyama, Daisuke*; Nakabayashi, Ryo*; Tanaka, Shingo*; Koma, Yoshikazu; Takahatake, Yoko
Journal of Nuclear Science and Technology, 58(4), p.493 - 506, 2021/04
Times Cited Count：2 Percentile：20.20(Nuclear Science & Technology)Yamada, Kazuo*; Maruyama, Ippei*; Haga, Kazuko*; Igarashi, Go*; Aihara, Haruka; Tomita, Sayuri*; Kiran, R.*; Osawa, Norihisa*; Shibata, Atsuhiro; Shibuya, Kazutoshi*; et al.
Proceedings of International Waste Management Symposia 2021 (WM2021) (CD-ROM), 10 Pages, 2021/03
Yin, X.; Zhang, L.*; Harigai, Miki*; Wang, X.*; Ning, S.*; Nakase, Masahiko*; Koma, Yoshikazu; Inaba, Yusuke*; Takeshita, Kenji*
Water Research, 177, p.115804_1 - 115804_10, 2020/06
Times Cited Count：21 Percentile：69.03(Engineering, Environmental)Yin, X.; Zhang, L.*; Meng, C.*; Inaba, Yusuke*; Wang, X.*; Nitta, Ayako; Koma, Yoshikazu; Takeshita, Kenji*
Journal of Hazardous Materials, 387, p.121677_1 - 121677_10, 2020/04
Times Cited Count：13 Percentile：45.03(Engineering, Environmental)Koma, Yoshikazu
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(2), p.133 - 136, 2019/12
At Fukushima Daiichi Nuclear Power Station, radioactive waste has been generated due to progress of decommissioning. This review outlines analysis of the waste at the site for R&D concerning waste management technologies.
Koma, Yoshikazu; Niibori, Yuichi*
Nihon Kikai Gakkai-Shi, 122(1211), p.21 - 23, 2019/10
International Topical Workshop on Fukushima Decommissioning Research was held in March 2019 by the Japan Society of Mechanical Engineers and the Atomic Energy Society of Japan. Result of track for waste management technologies among 5 tracks is outlined.
Sugiyama, Daisuke*; Nakabayashi, Ryo*; Koma, Yoshikazu; Takahatake, Yoko; Tsukamoto, Masaki*
Journal of Nuclear Science and Technology, 56(9-10), p.881 - 890, 2019/09
Times Cited Count：4 Percentile：33.76(Nuclear Science & Technology)Koma, Yoshikazu; Murakami, Erina
Radiochimica Acta, 107(9-11), p.965 - 977, 2019/09
Times Cited Count：1 Percentile：8.72(Chemistry, Inorganic & Nuclear)Fukushima Daiichi Nuclear Power Station, which is owned by Tokyo Electric Power Company, suffered from the great earthquake and Tsunami on 11 March 2011, and serious contamination with radioactive nuclides occurred. To investigate methodologies of waste management, contaminated materials have been radiochemically analyzed. This paper reviews the analytical data for actinide elements. Actinide nuclides are detected in the contaminated water. The contaminated water is chemically decontaminated, although actinide concentration does not decrease with time. This suggests that actinides come from the damaged fuel with slow dissolution. From the topsoil at the site, Pu, Am and Cm were detected and come from the damaged fuel, whereas U from natural. TRU would slowly move to deeper. Contamination of rubble is nonuniform and actinides are detected as well as fission products. For vegetation, TRU nuclides were found from fallen leaves near the reactor buildings.
Takahatake, Yoko; Koma, Yoshikazu
Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05
Yamada, Kazuo*; Maruyama, Ippei*; Koma, Yoshikazu; Haga, Kazuko*; Igarashi, Go*; Shibuya, Kazutoshi*; Aihara, Haruka
Proceedings of International Waste Management Symposia 2019 (WM2019) (CD-ROM), 6 Pages, 2019/03
