Analysis of deposits inside the reactor at Fukushima Daiichi Nuclear Power Station in JFY2021; The Subsidy program of "Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris)" starting FY2021

Ikeuchi, Hirotomo; Sasaki, Shinji; Onishi, Takashi; Nakayoshi, Akira; Arai, Yoichi; Sato, Takumi; Ohgi, Hiroshi; Sekio, Yoshihiro; Yamaguchi, Yukako; Morishita, Kazuki; et al.

JAEA-Data/Code 2023-005, 418 Pages, 2023/12

JAEA-Data-Code-2023-005-01.pdf:24.59MB
JAEA-Data-Code-2023-005-02.pdf:32.18MB

For safe and steady decommissioning of Tokyo Electric Power Company Holdings' Fukushima Daiichi Nuclear Power Station (1F), information concerning composition and physical/chemical properties of fuel debris generated in the reactors should be estimated and provided to other projects conducting the decommissioning work including the retrieval of fuel debris and the subsequent storage. For this purpose, in FY2021, samples of contaminants (the wiped smear samples and the deposits) obtained through the internal investigation of the 1F Unit 2 were analyzed to clarify the components and to characterize the micro-particles containing uranium originated from fuel (U-bearing particles) in detail. This report summarized the results of analyses performed in FY2021, including the microscopic analysis by SEM and TEM, radiation analysis, and elemental analysis by ICP-MS, as a database for evaluating the main features of each sample and the probable formation mechanism of the U-bearing particles.

Simulation study on H behavior in the Fukushima coastal region; Comparison of influences of discharges from the Fukushima Daiichi and rivers

Sakuma, Kazuyuki; Yamada, Susumu; Machida, Masahiko; Kurikami, Hiroshi; Misono, Toshiharu; Nakanishi, Takahiro; Iijima, Kazuki

Marine Pollution Bulletin, 192, p.115054_1 - 115054_10, 2023/07

https://doi.org/10.1016/j.marpolbul.2023.115054

Neutron reflectivity study on the suppression of interfacial water accumulation between a polypropylene thin film and Si substrate using a silane-coupling agent

Shimokita, Keisuke*; Yamamoto, Katsuhiro*; Miyata, Noboru*; Arima-Osonoi, Hiroshi*; Nakanishi, Yohei*; Takenaka, Mikihito*; Shibata, Motoki*; Yamada, Norifumi*; Seto, Hideki*; Aoki, Hiroyuki; et al.

Langmuir, 38(41), p.12457 - 12465, 2022/10

https://doi.org/10.1021/acs.langmuir.2c01599

Protein hydration and its freezing phenomena; Toward the application for cell freezing and frozen food storage

Yamamoto, Naoki*; Nakanishi, Masahiro*; Rajan, R.*; Nakagawa, Hiroshi

Biophysics and Physicobiology (Internet), 18, p.284 - 288, 2021/12

https://doi.org/10.2142/biophysico.bppb-v18.034

Water is an indispensable solvent for living things. 60% of our body is composed of water, the lack of which causes lots of fatal problems. It has also been known that protein function is performed only when it accompanies water molecules around the surface, i.e. hydration water molecules. Therefore, it is essential to understand how water and biological component interact with each other in the view point of structure and dynamics. Freezing is a fundamental and simple phenomenon of water, and thus can be used as a probe for the purpose. Furthermore, preservation of cells and proteins under low temperature is crucial for numerous applications, which in turn triggers a myriad of undesirable consequences because of the freezing.

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018) (Translated document)

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.

A Modeling approach to estimate the Cs discharge in rivers from immediately after the Fukushima accident until 2017

Sakuma, Kazuyuki; Nakanishi, Takahiro; Yoshimura, Kazuya; Kurikami, Hiroshi; Namba, Kenji*; Zheleznyak, M.*

Journal of Environmental Radioactivity, 208-209, p.106041_1 - 106041_12, 2019/11

https://doi.org/10.1016/j.jenvrad.2019.106041

We developed a simple model to evaluate and predict Cs discharge from catchment using tank model and L-Q equation. Using this model, Cs discharge and discharge ratio from Abukuma River and 13 other rivers in Fukushima coastal region were estimated from immediately after Fukushima accident to 2017. Cesium-137 discharge ratio to the deposition amount in catchment through Abukuma River and 13 other rivers in Fukushima coastal region during about initial six months were estimated to be 18 TBq (3.1%) and 11 TBq (0.8%), respectively. These values were 1-2 orders of magnitude larger than the previous study observed after June 2011, indicating that initial Cs discharge from catchment through rivers was a significant. However it was founded that an impact on the ocean derived from initial Cs discharge through river can be limited because Cs discharge from Abukuma River and 13 other rivers in Fukushima coastal region (29 TBq) was two orders of magnitude smaller than the direct release from FDNPP into the ocean (3.5 PBq) and from atmospheric deposition into the ocean (7.6 PBq).

Mapping measurement for beam energy position monitor system for RIKEN superconducting acceleration cavity

Watanabe, Tamaki*; Toyama, Takeshi*; Hanamura, Kotoku*; Imao, Hiroshi*; Kamigaito, Osamu*; Kamoshida, Atsushi*; Kawachi, Toshihiko*; Koyama, Ryo*; Sakamoto, Naruhiko*; Fukunishi, Nobuhisa*; et al.

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1105 - 1108, 2019/07

https://www.pasj.jp/web_publish/pasj2019/proceedings/PDF/FRPI/FRPI033.pdf

Upgrades for the RIKEN heavy-ion linac (RILAC) involving a new superconducting linac (SRILAC) are currently underway at the RIKEN radioactive isotope beam factory (RIBF). It is crucially important to develop nondestructive beam measurement diagnostics. We have developed a beam energy position monitor (BEPM) system which can measure not only the beam position but also the beam energy simultaneously by measuring the time of flight of the beam. We fabricated 11 BEPMs and completed the position calibration to obtain the sensitivity and offset for each BEPMs. The position accuracy has been achieved to be less than 0.1 mm by using the mapping measurement.

A Study on the tendencies on the member states from which Broader Conclusion (BC) has been drawn and on those from which BC has not been drawn yet by the International Atomic Energy Agency; Extracting possible requirements for drawing the BC

Nakanishi, Hiroaki; Kimura, Takashi; Shimizu, Ryo; Kitade, Yuta; Tazaki, Makiko; Tamai, Hiroshi; Suda, Kazunori

Nihon Kaku Busshitsu Kanri Gakkai Dai-39-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2018/11

To extract the possible requirements for the Broader Conclusion (BC) drawn by the IAEA in the Member States, this study is to conduct the comparative analysis of the tendencies on the Member States from which the BC has been drawn and those from which the BC has not been drawn yet.

Study on elements of establishing the regional safeguards

Kitade, Yuta; Tamai, Hiroshi; Tazaki, Makiko; Shimizu, Ryo; Kimura, Takashi; Nakanishi, Hiroaki; Suda, Kazunori

Nihon Kaku Busshitsu Kanri Gakkai Dai-39-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2018/11

Regional Safeguards is considered as one of the measures for strengthening IAEA safeguards and its concept is recognized at NPT Review Conference and also NSG Guidelines amended in 2011. This Study examines the elements for the proper establishment of Regional Safeguards.

Evaluation of sediment and Cs redistribution in the Oginosawa River catchment near the Fukushima Dai-ichi Nuclear Power Plant using integrated watershed modeling

Sakuma, Kazuyuki; Malins, A.; Funaki, Hironori; Kurikami, Hiroshi; Niizato, Tadafumi; Nakanishi, Takahiro; Mori, Koji*; Tada, Kazuhiro*; Kobayashi, Takamaru*; Kitamura, Akihiro; et al.

Journal of Environmental Radioactivity, 182, p.44 - 51, 2018/02

https://doi.org/10.1016/j.jenvrad.2017.11.021

The Oginosawa River catchment lies 15 km south-west of the Fukushima Dai-ichi nuclear plant. The General-purpose Terrestrial Fluid-flow Simulator (GETFLOWS) code was used to study sediment and Cs redistribution within the catchment. Cesium-137 input to watercourses came predominantly from land adjacent to river channels and forest gullies. Forested areas far from the channels only made a minor contribution to Cs input to watercourses, total erosion of between 0.001-0.1 mm from May 2011 to December 2015. The 2.3-6.9% y decrease in the amount of Cs in forest topsoil over the study period can be explained by radioactive decay (approximately 2.3% y), along with a migration downwards into subsoil and a small amount of export. The amount of Cs available for release from land adjacent to rivers is expected to be lower in future than compared to this study period, as the simulations indicate a high depletion of inventory from these areas.