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Journal Articles

Restoration project from the Fukushima Dai-ichi Nuclear Power Station Accident

Iijima, Kazuki

Enerugi, Shigen, 44(6), p.372 - 377, 2023/11

In the Fukushima Dai-ichi Nuclear Power Station accident, huge number of radioactive materials were released into the environment. We provided an overview of how issues have been tackled, with a focus on decontamination which was the pillar of large-scale reconstruction efforts.

Journal Articles

Simulation study on $$^{3}$$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

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

Journal Articles

Testing mosses exposed in bags as biointerceptors of airborne radiocaesium after the Fukushima Dai-ichi Nuclear Power Station accident

Di Palma, A.; Adamo, P.*; Dohi, Terumi; Fujiwara, Kenso; Hagiwara, Hiroki; Kitamura, Akihiro; Sakoda, Akihiro; Sato, Kazuhiko; Iijima, Kazuki

Chemosphere, 308, Part 1, p.136179_1 - 136179_13, 2022/12

 Times Cited Count:0 Percentile:0(Environmental Sciences)

The present study shows the use of mosses transplanted in bags, called as moss bags, as biosensors of airborne radioactive dusts in the environment of the evacuated zone of Fukushima. A standardized protocol was applied and three moss species were used. Background sites of Okayama Prefecture were used for comparison. In the Fukushima area, the moss bags were able to accumulate radiocaesium in all exposure sites and periods, with Sphagnum palustre moss acting as the most performant moss. The radiocaesium activity concentrations dectected in mosses were in strong agreement with the Cs deposition levels and decontamination status of each exposure site. The accumulation of soil-derived radiocaesium by moss bags was supported by autoradiography and electron microscopy analyses. The linear dependency of Cs accumulation with the exposure time allowed a radiocaesium quantitative assessment.

JAEA Reports

The Laboratory Operation Based on ISO/IEC 17025; Radioactivity analysis of environmental samples by germanium semiconductor detectors

Urushidate, Tadayuki*; Yoda, Tomoyuki; Otani, Shuichi*; Yamaguchi, Toshio*; Kunii, Nobuaki*; Kuriki, Kazuki*; Fujiwara, Kenso; Niizato, Tadafumi; Kitamura, Akihiro; Iijima, Kazuki

JAEA-Review 2022-023, 8 Pages, 2022/09

JAEA-Review-2022-023.pdf:1.19MB

After the accident of the Fukushima Daiichi Nuclear Power Station, the Japan Atomic Energy Agency has newly set up a laboratory in Fukushima and started measuring radioactivity concentrations of environmental samples. In October 2015, Fukushima Radiation Measurement Group has been accredited the ISO/IEC 17025 standard by the Japan Accreditation Board (JAB) as a testing laboratory for radioactivity analysis ($$^{134}$$Cs, $$^{137}$$Cs) based on Gamma-ray spectrometry with germanium semiconductor detectors. The laboratory has measured approximately 60,000 of various environmental samples at the end of March 2022. The laboratory quality control and measurement techniques have been accredited by regular surveillance of JAB. In September 2019, the laboratory renewed accreditation as a testing laboratory for radioactivity analysis.

Journal Articles

Watershed-geochemical model to simulate dissolved and particulate $$^{137}$$Cs discharge from a forested catchment

Sakuma, Kazuyuki; Hayashi, Seiji*; Yoshimura, Kazuya; Kurikami, Hiroshi; Malins, A.; Funaki, Hironori; Tsuji, Hideki*; Kobayashi, Takamaru*; Kitamura, Akihiro; Iijima, Kazuki

Water Resources Research, 58(8), p.e2021WR031181_1 - e2021WR031181_16, 2022/08

 Times Cited Count:1 Percentile:42.13(Environmental Sciences)

Journal Articles

Using CO$$_{2}$$ Reactions to Achieve Mass-spectrometric Discrimination in Simultaneous Plutonium-isotope Speciation with Inductively Coupled Plasma-Tandem Mass Spectrometry

Matsueda, Makoto; Kawakami, Tomohiko*; Koarai, Kazuma; Terashima, Motoki; Fujiwara, Kenso; Iijima, Kazuki; Furukawa, Makoto*; Takagai, Yoshitaka*

Chemistry Letters, 51(7), p.678 - 682, 2022/07

 Times Cited Count:2 Percentile:63.98(Chemistry, Multidisciplinary)

New methodology for a simultaneous isotope speciation of various Pu isotopes without complicated isobaric interferences is developed by using inductively coupled plasma-mass spectrometry (ICP-MS). In analyzing ICP tandem MS (ICP-MS/MS), CO$$_{2}$$ gas reactions in a dynamic reaction cell (DRC) almost eliminated the background noise intensity produced by isobaric interference from isotopes originating from actinides such as Am, Cm, and U at the locations (m/z) of significant Pu isotopes ($$^{239}$$Pu, $$^{240}$$Pu, $$^{241}$$Pu, $$^{242}$$Pu, $$^{244}$$Pu).

Journal Articles

Accumulation mechanisms of radiocaesium within lichen thallus tissues determined by means of ${it in situ}$ microscale localisation observation

Dohi, Terumi; Iijima, Kazuki; Machida, Masahiko; Suno, Hiroya*; Omura, Yoshihito*; Fujiwara, Kenso; Kimura, Shigeru*; Kanno, Futoshi*

PLOS ONE (Internet), 17(7), p.e0271035_1 - e0271035_21, 2022/07

 Times Cited Count:1 Percentile:16.29(Multidisciplinary Sciences)

Journal Articles

A Modeling approach to estimate $$^{3}$$H discharge from rivers; Comparison of discharge from the Fukushima Dai-ichi and inventory in seawater in the Fukushima coastal region

Sakuma, Kazuyuki; Machida, Masahiko; Kurikami, Hiroshi; Iwata, Ayako; Yamada, Susumu; Iijima, Kazuki

Science of the Total Environment, 806(Part 3), p.151344_1 - 151344_8, 2022/02

 Times Cited Count:4 Percentile:36.59(Environmental Sciences)

Journal Articles

Dynamics of $$^{137}$$Cs in water and phyto- and zooplankton in a reservoir affected by the Fukushima Daiichi Nuclear Power Plant Accident

Tsuji, Hideki*; Nakagawa, Megumi*; Iijima, Kazuki; Funaki, Hironori; Yoshimura, Kazuya; Sakuma, Kazuyuki; Hayashi, Seiji*

Global Environmental Research (Internet), 24(2), p.115 - 127, 2021/06

Lake water, phytoplankton and zooplankton were sampled by a total of 12 quarterly surveys from August 2014 to May 2017 at a dam lake in the Fukushima nuclear disaster area, and variations of dissolved form of $$^{137}$$Cs and planktonic $$^{137}$$Cs were observed. Seasonal variations in dissolved $$^{137}$$Cs concentration with high in summer and low in winter were observed in the upstream, midstream and downstream areas of the lake, but no seasonal or site specific differences in planktonic $$^{137}$$Cs concentrations and dominant species were found. The amount of planktonic form of $$^{137}$$Cs in the water was less than 1.4% of the total $$^{137}$$Cs in the lake water, therefore the effect of plankton on the dynamics of $$^{137}$$Cs in the lake was minimal.

Journal Articles

Overview of environmental impact assessment studies on radioactive contamination after the Fukushima Daiichi Nuclear Power Plant accident

Iijima, Kazuki; Hayashi, Seiji*; Tamaoki, Masanori*

Global Environmental Research (Internet), 24(2), p.85 - 93, 2021/06

Environmental radioactive contamination by the Fukushima Daiichi Nuclear Power Plant accident has clearly been declining during the passage of almost 10 years from the accident. However, the prolongation of radioactive contamination in natural ecosystems probably derived from forested area without decontamination is pointed out by many studies, so more detailed examination will be needed for environmental dynamics of bioavailable radiocesium and its transfer to ecosystems. Also for influence of radiation to organisms, effects of evacuation on wild organisms are more pronounced than direct effect from radiation, especially in Fukushima evacuation area.

Journal Articles

Radiocaesium accumulation capacity of epiphytic lichens and adjacent barks collected at the perimeter boundary site of the Fukushima Dai-ichi Nuclear Power Station

Dohi, Terumi; Omura, Yoshihito*; Yoshimura, Kazuya; Sasaki, Takayuki*; Fujiwara, Kenso; Kanaizuka, Seiichi*; Nakama, Shigeo; Iijima, Kazuki

PLOS ONE (Internet), 16(5), p.e0251828_1 - e0251828_16, 2021/05

 Times Cited Count:5 Percentile:42.99(Multidisciplinary Sciences)

JAEA Reports

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.

Journal Articles

Vertical distribution of $$^{90}$$Sr and $$^{137}$$Cs in soils near the Fukushima Daiichi Nuclear Power Station

Sasaki, Takayuki*; Matoba, Daisuke*; Dohi, Terumi; Fujiwara, Kenso; Kobayashi, Taishi*; Iijima, Kazuki

Journal of Radioanalytical and Nuclear Chemistry, 326(1), p.303 - 314, 2020/10

 Times Cited Count:3 Percentile:36.29(Chemistry, Analytical)

Journal Articles

Key factors controlling radiocesium sorption and fixation in river sediments around the Fukushima Daiichi Nuclear Power Plant, 1; Insights from sediment properties and radiocesium distributions

Tachi, Yukio; Sato, Tomofumi*; Akagi, Yosuke*; Kawamura, Makoto*; Nakane, Hideji*; Terashima, Motoki; Fujiwara, Kenso; Iijima, Kazuki

Science of the Total Environment, 724, p.138098_1 - 138098_11, 2020/07

 Times Cited Count:13 Percentile:58.17(Environmental Sciences)

To understand and predict radiocesium transport behaviors in the environment, highly contaminated sediments from Ukedo and Odaka rivers around the Fukushima Daiichi Nuclear Power Plant were investigated systematically focusing on key factors controlling radiocesium sorption and fixation, including particle size, clay mineralogy and organic matter.

Journal Articles

Key factors controlling radiocesium sorption and fixation in river sediments around the Fukushima Daiichi Nuclear Power Plant, 2; Sorption and fixation behaviors and their relationship to sediment properties

Tachi, Yukio; Sato, Tomofumi*; Takeda, Chizuko*; Ishidera, Takamitsu; Fujiwara, Kenso; Iijima, Kazuki

Science of the Total Environment, 724, p.138097_1 - 138097_10, 2020/07

 Times Cited Count:9 Percentile:44.38(Environmental Sciences)

To understand and predict radiocesium transport behaviors in the environment, sorption and fixation behaviors of radiocesium on river sediments from Ukedo and Odaka rivers around the Fukushima Daiichi Nuclear Power Plant were investigated systematically focusing on Cs sorption and fixation mechanisms and their relationship with Cs concentrations and sediment properties including clay mineralogy and organic matter.

Journal Articles

Mineral composition characteristics of radiocesium sorbed and transported sediments within the Tomioka river basin in Fukushima Prefecture

Hagiwara, Hiroki; Konishi, Hiromi*; Nakanishi, Takahiro; Fujiwara, Kenso; Iijima, Kazuki; Kitamura, Akihiro

Journal of Environmental Radioactivity, 211, p.106042_1 - 106042_10, 2020/01

 Times Cited Count:3 Percentile:15.15(Environmental Sciences)

Journal Articles

Fukushima Daiichi decommissioning and Fukushima remediation, 2

Sato, Yuki; Kawase, Keiichi; Iijima, Kazuki; Kobayashi, Takuya

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 62(1), p.37 - 41, 2020/01

This series articles introduce JAEA R&D. This time, we will introduce about Fukushima Daiichi decommissioning and Fukushima remediation (2).

Journal Articles

Temporal decrease in air dose rate in the sub-urban area affected by the Fukushima Dai-ichi Nuclear Power Plant accident during four years after decontamination works

Nakama, Shigeo; Yoshimura, Kazuya; Fujiwara, Kenso; Ishikawa, Hiroyasu; Iijima, Kazuki

Journal of Environmental Radioactivity, 208-209, p.106013_1 - 106013_8, 2019/11

 Times Cited Count:9 Percentile:37.04(Environmental Sciences)

Trends of air dose rate decrease after decontamination works and factors which affect them constitute essential information for radiation protection, such as prediction of external exposure to the public and implementation of measures to reduce such exposure. This study investigated the decrease of air dose rate (ambient dose rate at 1 m above the ground) at 163 points across sub-urban areas in the evacuation zone around the Fukushima Dai-ichi Nuclear Power Plant over the period of four years following the decontamination works carried out in November 2012. The air dose rate on the asphalt pavement decreased faster than on soil surfaces. In addition, air dose rates near the forest decreased at a slower pace than in open fields. These results suggest that the air dose rate in urbanized areas can decrease faster than in other types of land, even after decontamination. Based on comparisons with decrease rates obtained in other studies, the air dose rate tends to decrease faster outside the evacuation zone than inside it. The decrease in air dose rate after decontamination was slower than before decontamination. The contribution of the weathering effect and human activity was estimated to be about 80% and 20% of the ecological decrease rate, respectively.

Journal Articles

Radiation dose distribution in a mountainous area nearby the Fukushima Dai-ichi Nuclear Power Plant and data analysis

Dohi, Terumi; Muto, Kotomi; Yoshimura, Kazuya; Kanaizuka, Seiichi*; Iijima, Kazuki

KEK Proceedings 2019-2, p.14 - 19, 2019/11

In order to investigate the effect of topography, meteorological condition, etc., on the spatial distribution of air dose rate on the main plume path, we evaluated walking survey data of air dose rates on Mt. Koutaishi and Mt. Juman, directed in northwest of and approximately 33 km and 11 km from the FDNPP. Measurements were performed on two orbital routs with different constant altitudes and general mountain trails in each mountain. The measurement data were compared with airborne monitoring results to investigate the relation between the dose rate distribution and elevation and orientation. At Mt. Koutaishi, the air dose rate was particularly high on the east side of the mountain, and the significant dependence of direction on the dose rate distribution was observed. Furthermore, high dose rate near the mountain foot indicates possibility of large deposition of $$^{137}$$Cs due to the plume passage from the FDNPP. At Mt. Juman, uniformly distribution of air dose rate was observed, and effect of wet deposition was considered. These results suggest the possibility of different deposition mechanisms in mountain range unit.

Journal Articles

Electron microscopic analysis of radiocaesium-bearing microparticles in lichens collected within 3 km of the Fukushima Dai-ichi Nuclear Power Plant

Dohi, Terumi; Tagomori, Hisaya; Omura, Yoshihito*; Fujiwara, Kenso; Kanaizuka, Seiichi*; Iijima, Kazuki

Environmental Radiochemical Analysis VI, p.58 - 70, 2019/09

In this study we established a separation method for radiocaesium-bearing microparticles (CsMPs) from lichens using electron microscopic analysis. Lichens were first digested within hydrogen peroxide and then an automatic particle analyser system based on FE-EPMA was used for detecting CsMPs within lots of mineral-like and metallic particles quickly. The elemental composition and radiocaesium activities of the separated CsMPs were measured, and the results show that the digestion treatment did not influence the CsMPs characteristics. An inhomogeneous elemental distribution was found in some CsMPs by two-dimensional elemental analysis using FE-EMPA. Our methods for separation of CsMPs and analysing their elemental composition are expected to be useful for grasping the chemical composition trends of CsMPs statistically.

178 (Records 1-20 displayed on this page)