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Journal Articles

Activity review of Working Group on Accidents Relating X-ray Equipment, Japan Health Physics Society

Igarashi, Yu; Yamaguchi, Ichiro*; Oda, Keiji*; Fukushi, Masahiro*; Sakama, Minoru*; Iimoto, Takeshi*

Nihon Hoshasen Anzen Kanri Gakkai-Shi, 21(2), p.74 - 76, 2022/11

no abstracts in English

Journal Articles

Atmospheric resuspension of insoluble radioactive cesium bearing particles found in the difficult-to-return area in Fukushima

Tang, P.*; Kita, Kazuyuki*; Igarashi, Yasuhito*; Satou, Yukihiko; Hatanaka, Kotaro*; Adachi, Koji*; Kinase, Takeshi*; Ninomiya, Kazuhiko*; Shinohara, Atsushi*

Progress in Earth and Planetary Science (Internet), 9(1), p.17_1 - 17_15, 2022/03

 Times Cited Count:3 Percentile:71.11(Geosciences, Multidisciplinary)

Journal Articles

Bayesian sparse modeling of extended X-ray absorption fine structure to determine interstitial oxygen positions in yttrium oxyhydride epitaxial thin film

Kumazoe, Hiroyuki*; Igarashi, Yasuhiko*; Iesari, F.*; Shimizu, Ryota*; Komatsu, Yuya*; Hitosugi, Taro*; Matsumura, Daiju; Saito, Hiroyuki*; Iwamitsu, Kazunori*; Okajima, Toshihiko*; et al.

AIP Advances (Internet), 11(12), p.125013_1 - 125013_5, 2021/12

 Times Cited Count:1 Percentile:11.39(Nanoscience & Nanotechnology)

Journal Articles

Impacts of freeze-thaw processes and subsequent runoff on $$^{137}$$Cs washoff from bare land in Fukushima

Igarashi, Yasunori*; Onda, Yuichi*; Wakiyama, Yoshifumi*; Yoshimura, Kazuya; Kato, Hiroaki*; Kozuka, Shohei*; Manome, Ryo*

Science of the Total Environment, 769, p.144706_1 - 144706_9, 2021/05

 Times Cited Count:2 Percentile:19.08(Environmental Sciences)

Journal Articles

Hydrogen absorption mechanism into iron in aqueous solution including metal cations by laser ablation tests and first-principles calculations

Igarashi, Takahiro; Otani, Kyohei; Kato, Chiaki; Sakairi, Masatoshi*; Togashi, Yusuke*; Baba, Kazuhiko*; Takagi, Shusaku*

ISIJ International, 61(4), p.1085 - 1090, 2021/04

 Times Cited Count:0 Percentile:0(Metallurgy & Metallurgical Engineering)

In order to clarify the effect of metal cations (Zn$$^{2+}$$, Mg$$^{2+}$$, Na$$^{+}$$) in aqueous solution on hydrogen permeation into iron, the amount of hydrogen permeation from iron surface was measured by electrochemical tests with a laser ablation. Moreover, in order to obtain the basic mechanism of hydrogen permeation with metal cation, first-principles calculations were used to acquire the adsorption potential of the metal cation and the electronic state around iron surface. By Zn$$^{2+}$$ in solution, anodic reaction on ablated surface by laser irradiation was suppressed. Also, by quantum analysis Zn atoms were chemically bonded stronger than Na and Mg atoms to iron surface. It was suggested that the dissolution reaction of iron was suppressed by the formation of the Zn layer, and that lead suppression of hydrogen permeation into iron.

Journal Articles

Report on social communication activities of Young Researchers Association and Students Association of JHPS; Chiba-shi Science Festa

Yamada, Ryohei; Kono, Takahiko; Nakajima, Junya; Hirouchi, Jun; Tsuji, Tomoya; Umeda, Masayuki; Igarashi, Yu*; Koike, Hiromi*

Hoken Butsuri (Internet), 56(1), p.32 - 38, 2021/03

no abstracts in English

Journal Articles

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

Journal Articles

Deposition and dispersion of radio-cesium released due to the Fukushima Nuclear accident, 2; Sensitivity to aerosol microphysical properties of Cs-bearing microparticles (CsMPs)

Kajino, Mizuo*; Adachi, Koji*; Igarashi, Yasuhito*; Satou, Yukihiko; Sawada, Morihiro*; Sekiyama, Tsuyoshi*; Zaizen, Yuji*; Saya, Akane*; Tsuruta, Haruo*; Moriguchi, Yuichi*

Journal of Geophysical Research; Atmospheres, 126(1), 23 Pages, 2021/01

 Times Cited Count:11 Percentile:82.09(Meteorology & Atmospheric Sciences)

Journal Articles

Role of advection in atmospheric ammonia; A Case study at a Japanese lake basin influenced by agricultural ammonia sources

Kubota, Tomohiro; Kuroda, Hisao*; Watanabe, Mirai*; Takahashi, Akiko*; Nakazato, Ryoji*; Tarui, Mika*; Matsumoto, Shunichi*; Nakagawa, Keita*; Numata, Yasuko*; Ouchi, Takao*; et al.

Atmospheric Environment, 243, p.117856_1 - 117856_9, 2020/12

 Times Cited Count:2 Percentile:12.23(Environmental Sciences)

The dry and wet depositions of atmospheric ammonia (NH$$_{3}$$) is one of the important pathways of nitrogen loads to aquatic ecosystems. Crop and livestock agriculture, one of the largest emitters of NH$$_{3}$$ in Asian countries, are known to cause high spatial and seasonal variation of NH$$_{3}$$ and influence the surrounding lake basin areas via its dry and wet deposition. However, the spatial characteristics of the NH$$_{3}$$ concentration in basin scale are not completely understood for regulation in NH$$_{3}$$ emission. Here we aim to clarify dominant factors of spatial and seasonal variations of the NH$$_{3}$$ concentration in a eutrophic lake basin surrounded by agricultural areas in Japan. Passive sampling over various land use categories in the basin was conducted at 36 sites in total from October 2018 to January 2020. Interestingly, the observed NH$$_{3}$$ concentration near the livestock houses were higher in winter than summer, which was inconsistent with knowledge of seasonal changes of current NH$$_{3}$$ emission inventory based on temperature-driven volatilization process. Comparing monthly NH$$_{3}$$ concentrations with various meteorological factors, we suggested the importance of seasonal advection of NH$$_{3}$$ from high emission sources to which has been rarely paid attention by the previous past studies. As for this, should be considered for lake ecosystem management since deposition of NH$$_{3}$$ is known to be closely related to the ecological processes such as phytoplankton blooming.

Journal Articles

Structural and compositional characteristics of Fukushima release particulate material from Units 1 and 3 elucidates release mechanisms, accident chronology and future decommissioning strategy

Martin, P. G.*; Jones, C. P.*; Bartlett, S.*; Ignatyev, K.*; Megson-Smith, D.*; Satou, Yukihiko; Cipiccia, S.*; Batey, D. J.*; Rau, C.*; Sueki, Keisuke*; et al.

Scientific Reports (Internet), 10, p.22056_1 - 22056_17, 2020/12

 Times Cited Count:1 Percentile:8.72(Multidisciplinary Sciences)

Journal Articles

Project IPAD; A Database to catalogue the analysis of Fukushima Daiichi accident fragmental release material

Martin, P.*; Alhaddad, O.*; Verbelen, Y.*; Satou, Yukihiko; Igarashi, Yasuhito*; Scott, T. B.*

Scientific Data (Internet), 7, p.282_1 - 282_8, 2020/08

 Times Cited Count:2 Percentile:19.64(Multidisciplinary Sciences)

Journal Articles

Land use types control solid wash-off rate and entrainment coefficient of Fukushima-derived $$^{137}$$Cs, and their time dependence

Wakiyama, Yoshifumi*; Onda, Yuichi*; Yoshimura, Kazuya; Igarashi, Yasunori*; Kato, Hiroaki*

Journal of Environmental Radioactivity, 210, p.105990_1 - 105990_12, 2019/12

 Times Cited Count:20 Percentile:70.05(Environmental Sciences)

Journal Articles

Classification of the insoluble particles including radioactive Cs found in Okuma town and Futaba town, Fukushima prefecture

Igarashi, Junya*; Zhang, Z. J.*; Ninomiya, Kazuhiko*; Shinohara, Atsushi*; Satou, Yukihiko; Minowa, Haruka*; Yoshikawa, Hideki

KEK Proceedings 2019-2, p.54 - 59, 2019/11

no abstracts in English

Journal Articles

A Review of Cs-bearing microparticles in the environment emitted by the Fukushima Dai-ichi Nuclear Power Plant accident

Igarashi, Yasuhito*; Kogure, Toshihiro*; Kuribara, Yuichi; Miura, Hikaru*; Okumura, Taiga*; Satou, Yukihiko; Takahashi, Yoshio*; Yamaguchi, Noriko*

Journal of Environmental Radioactivity, 205-206, p.101 - 118, 2019/09

 Times Cited Count:60 Percentile:73.4(Environmental Sciences)

Scientists face challenge in identifying the radioactive materials which are found as dotted images on various imaging plate (IP) autoradiographic photos of radioactively contaminated materials by the Fukushima Dai-ichi Nuclear Power Plant (F1NPP, or FDNPP) accident, such as air filter, fugitive dust, surface soil, agricultural materials, and water-shed samples. It has been revealed that they are minute particles with distinct morphology and elemental composition with high specific radioactivity, and different from those of the so-called Chernobyl hot particles. Basically, they are glassy particles once molten, composed of Si, O, Fe, Zn etc. with highly concentrated radiocaesium, which can be called as radiocaesium-bearing microparticles (CsMP). At present, CsMP can be classified into two types, Types-A and -B, which are characterized by different specific radioactivity, $$^{134}$$Cs/$$^{137}$$Cs ratio, size and morphology, and geographic distribution around F1NPP. Such studies on the CsMP from various aspects have provided valuable information about what happened in the nuclear reactors during the F1NPP accident and fates of the CsMP in the environment. This review first provides a retrospective view on the research history of the CsMP, which is helpful to understand the unique character of the CsMP. Subsequently, more details about the current understanding of the natures of these hot particles, such as origin, morphology, chemical compositions, thermal properties, water-solubility, and secondary migration of CsMP in river and ocean systems are described with future prospects.

Journal Articles

First determination of Pu isotopes ($$^{239}$$Pu, $$^{240}$$Pu and $$^{241}$$Pu) in radioactive particles derived from Fukushima Daiichi Nuclear Power Plant accident

Igarashi, Junya*; Zheng, J.*; Zhang, Z.*; Ninomiya, Kazuhiko*; Satou, Yukihiko; Fukuda, Miho*; Ni, Y.*; Aono, Tatsuo*; Shinohara, Atsushi*

Scientific Reports (Internet), 9(1), p.11807_1 - 11807_10, 2019/08

 Times Cited Count:19 Percentile:68.25(Multidisciplinary Sciences)

Radioactive particles were released into the environment during the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Many studies have been conducted to elucidate the chemical composition of released radioactive particles in order to understand their formation process. However, whether radioactive particles contain nuclear fuel radionuclides remains to be investigated. Here, we report the first determination of Pu isotopes in radioactive particles. To determine the Pu isotopes ($$^{239}$$Pu, $$^{240}$$Pu and $$^{241}$$Pu) in radioactive particles derived from the FDNPP accident which were free from the influence of global fallout, radiochemical analysis and inductively coupled plasma-mass spectrometry measurements were conducted. Radioactive particles derived from unit 1 and unit 2 or 3 were analyzed. For the radioactive particles derived from unit 1, activities of $$^{239+240}$$Pu and $$^{241}$$Pu were (1.70-7.06)$$times$$10$$^{-5}$$ Bq and (4.10-8.10)$$times$$10$$^{-3}$$ Bq, respectively and atom ratios of $$^{240}$$Pu/$$^{239}$$Pu and $$^{241}$$Pu/$$^{239}$$Pu were 0.330-0.415 and 0.162-0.178, respectively. These ratios were consistent with the simulation results from ORIGEN code and measurements from various environmental samples. In contrast, Pu was not detected in the radioactive particles derived from unit 2 or 3. The difference in Pu contents is clear evidence towards different formation processes of radioactive particles, and detailed formation processes can be investigated from Pu analysis.

Journal Articles

Activity of $$^{90}$$Sr in fallout particles collected in the difficult-to-return zone around the Fukushima Daiichi Nuclear Power Plant

Zhang, Z.*; Igarashi, Junya*; Satou, Yukihiko; Ninomiya, Kazuhiko*; Sueki, Keisuke*; Shinohara, Atsushi*

Environmental Science & Technology, 53(10), p.5868 - 5876, 2019/05

 Times Cited Count:19 Percentile:68.25(Engineering, Environmental)

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released abundant radioactive particles into the surrounding environment. Herein, we analyzed the activity of $$^{90}$$Sr in these particles to estimate the contribution of this radionuclide to the overall radiation exposure and shed light on the processes that occurred during the accident. Seven radioactive particles were isolated from the dust and soil samples collected from areas surrounding the FDNPP, and the minimum/maximum $$^{137}$$Cs activities were determined as 224/4,100 Bq. Based on the size, specific activity, and $$^{134}$$Cs/$$^{137}$$Cs activity ratios, we concluded that six of the seven radioactive particles were released from the Unit 1 reactor, while one particle was released from the Unit 3 reactor by a hydrogen explosion. Strontium-90 was detected in all radioactive particles, and the minimal/maximal $$^{90}$$Sr activities were determined as 0.046/1.4 Bq. $$^{137}$$Cs/$$^{90}$$Sr activity ratios above 1000 were observed for all seven particles, that is, compared to $$^{137}$$Cs, $$^{90}$$Sr had negligible contribution to the overall radiation exposure. The $$^{137}$$Cs/$$^{90}$$Sr activity ratios of the radioactive particles were similar to those of terrestrial environmental samples and were higher for particles released from the Unit 1 reactor than for samples collected from the Unit 1 reactor building, which indicates possibility of additional $$^{90}$$Sr -rich contamination after release of the particles.

Journal Articles

Analysis of two forms of radioactive particles emitted during the early stages of the Fukushima Dai-ichi Nuclear Power Station accident

Satou, Yukihiko; Sueki, Keisuke*; Sasa, Kimikazu*; Yoshikawa, Hideki; Nakama, Shigeo; Minowa, Haruka*; Abe, Yoshinari*; Nakai, Izumi*; Ono, Takahiro*; Adachi, Koji*; et al.

Geochemical Journal, 52(2), p.137 - 143, 2018/00

 Times Cited Count:65 Percentile:97.59(Geochemistry & Geophysics)

Journal Articles

Investigation of the chemical characteristics of individual radioactive microparticles emitted from reactor 1 by the Fukushima Daiichi Nuclear Power Plant accident by using multiple synchrotron radiation X-ray analyses

Ono, Takahiro*; Iizawa, Yushin*; Abe, Yoshinari*; Nakai, Izumi*; Terada, Yasuko*; Satou, Yukihiko; Sueki, Keisuke*; Adachi, Koji*; Igarashi, Yasuhito*

Bunseki Kagaku, 66(4), p.251 - 261, 2017/04

 Times Cited Count:32 Percentile:80.23(Chemistry, Analytical)

no abstracts in English

Journal Articles

Conceptual design of main magnets for the J-PARC RCS energy upgrade

Tani, Norio; Watanabe, Yasuhiro; Hotchi, Hideaki; Harada, Hiroyuki; Yamamoto, Masanobu; Kinsho, Michikazu; Igarashi, Susumu*; Sato, Yoichi*; Shirakata, Masashi*; Koseki, Tadashi*

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.708 - 711, 2016/11

At the J-PARC Main Ring (MR), there have been various investigation carried out at the moment aiming at the beam operation of MW order. As one of the investigations, a study of the Rapid-Cycling Synchrotron (RCS) magnets was implemented. Increase of the extraction energy of RCS was needed to reduce beam loss, as beam loss in the MR injection region was large under influence of Space Charge effect at the injection beam of 3GeV. Therefore conceptual design of the extraction energy upgrade using dipole and quadrupole magnets of RCS was performed. In this paper, we will report the contents of the study in extraction energy upgrade of RCS magnets and problems which became clear as a result.

Journal Articles

Hazard-consistent ground motions generated with a stochastic fault-rupture model

Nishida, Akemi; Igarashi, Sayaka*; Sakamoto, Shigehiro*; Uchiyama, Yasuo*; Yamamoto, Yu*; Muramatsu, Ken*; Takada, Tsuyoshi*

Nuclear Engineering and Design, 295, p.875 - 886, 2015/12

 Times Cited Count:2 Percentile:18.46(Nuclear Science & Technology)

Most probabilistic risk assessments (PRA) of structures involve the use of probabilistic schemes such as the scheme using probabilistic seismic hazard and fragility curves. Even when earthquake ground motions are required in Monte Carlo Simulations (MCS), they are generated to fit the specified response spectra, such as uniform hazard spectra at a specified exceedance probability. These ground motions, however, are not directly linked with corresponding seismic source characteristics. In this paper, the authors propose a methodology based on MCS to reproduce a set of input ground motions to develop an advanced PRA scheme that can explain the exceedance probability and sequence of functional loss in a nuclear power plant. These generated motions are consistent with the seismic hazard for the target site and their seismic source characteristics can be recognized in detail.

213 (Records 1-20 displayed on this page)