Evaluation of Co inventory in the core of the Fukushima Daiichi Nuclear Power Plant; Contribution of fuel deposits to the reactor core inventory

Uchida, Shunsuke*; Kino, Chiaki*; Karasawa, Hidetoshi; Takahatake, Yoko; Koma, Yoshikazu

Journal of Nuclear Science and Technology, 17 Pages, 2025/07

https://doi.org/10.1080/00223131.2025.2499187

Evaluation of radioactive nuclide behavior on and after the accident is important for the estimating radioactive nuclide composition in the wastes. The reactor core inventories have been obtained from the ORIGEN2 analysis, but the inventory of activation products is determined by the amount of their parent nuclides which are impurities contained in the structural materials. The ORIGEN2 does not treat fuel deposits including the impurities. Estimation of the initial Co-60 inventory in accurate is needed on the evaluation of some kinds of radioactive nuclide amount, since it is possible Co-60 is standard in the scaling factor. In this study, contribution of fuel deposits to the reactor core inventory was estimated by comparing the amount of Co-60 and Ni-63 calculated by the amounts of deposition by the microlayer-evaporation and drying-out model (MEDO model) and the result of the ORIGEN2 analysis, and then the method of estimating the reactor core inventory was proposed.

Microbiome analysis of the restricted bacteria in radioactive element-containing water at the Fukushima Daiichi Nuclear Power Station

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

https://doi.org/10.1128/aem.02113-23

Survey on technical issues of fission products behavior for improvement of decommissioning work efficiency and source term predicting accuracy; Report on the activity of this research committee for 2 years

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

https://doi.org/10.3327/jaesjb.65.11_674

no abstracts in English

Methodological developments and practice in characterisation of unconventional and legacy waste

Strand, P.*; Jefferies, N.*; Koma, Yoshikazu; Plyer, J.*

Journal of Radiological Protection, 42(2), p.020501_1 - 020501_16, 2022/06

https://doi.org/10.1088/1361-6498/ac4b02

Ten years after the NPP accident at Fukushima; Review on fuel debris behavior in contact with water

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

https://doi.org/10.1080/00223131.2021.1966347

General overview of the research project investigating the radionuclide solution behavior in mock mortar matrix modeled after conditions at the Fukushima-Daiichi Nuclear Power Station

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

https://doi.org/10.3151/jact.19.950

A Project focusing on the contamination mechanism of concrete after the accident at Fukushima Daiichi Nuclear Power Plant

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

Selective removal of radiocesium from micaceous clay for post-accident soil decontamination by temperature-controlled Mg-leaching in a column

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

https://doi.org/10.1016/j.jhazmat.2019.121677

Effort for management of radioactive waste with unknown quality and amount

Koma, Yoshikazu; Niibori, Yuichi*

Nihon Kikai Gakkai-Shi, 122(1211), p.21 - 23, 2019/10

https://doi.org/10.1299/jsmemag.122.1211_21

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.

Contamination of Fukushima Daiichi Nuclear Power Station with actinide elements

Koma, Yoshikazu; Murakami, Erina

Radiochimica Acta, 107(9-11), p.965 - 977, 2019/09

https://doi.org/10.1515/ract-2019-3126

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.