Experimental and modeling studies on the oxygen ingression behavior at the crevices of stainless steels in high-temperature water

Soma, Yasutaka; Komatsu, Atsushi; Kaji, Yoshiyuki; Yamamoto, Masahiro*; Igarashi, Takahiro

Corrosion Science, 251, p.112897_1 - 112897_15, 2025/07

https://doi.org/10.1016/j.corsci.2025.112897

Experimental and modeling studies of the oxygen ingression at the crevices of stainless steels were conducted in high-temperature water (288C). The limiting distance of oxygen ingression, , was defined as the point beyond which the primary surface oxide changed (hematite magnetite), regardless of crevice gap, oxygen concentration, and time. In situ measurements revealed increased electrical conductivity around the position indicating ion enrichment due to a differential oxygen concentration cell. increased with increasing crevice gap, oxygen concentration, and immersion time. Modeling study suggested that oxide layer growth reduced anodic dissolution and slowed oxygen consumption, allowing oxygen ingression with time.

New insight on the thermal impact on cementitious materials due to high-temperature with water supply; Continuous expansive spalling in water

Miura, Taito*; Miyamoto, Shintoro*; Maruyama, Ippei*; Aili, A.*; Sato, Takumi; Nagae, Yuji; Igarashi, Go*

Case Studies in Construction Materials, 21, p.e03571_1 - e03571_14, 2024/12

https://doi.org/10.1016/j.cscm.2024.e03571

Evaluation of corrosion on steel surface using image processing

Igarashi, Takahiro; Sugawara, Yu*; Otani, Kyohei; Aoyama, Takahito

Tetsu To Hagane, 110(15), p.1244 - 1250, 2024/11

https://doi.org/10.2355/tetsutohagane.TETSU-2024-058

Using two types of image processing techniques without machine learning, edge extraction processing and keypoint extraction processing, progressively corroded regions under rust layer from images of corroded steel surfaces was extracted. We found that there is a relatively good correlation between the keypoint strength obtained from the keypoint extraction processing for HSL transformed and histogram flattened corroded surface photographs and the corrosion depth after removing rust removal.

Fukushima Daiichi Nuclear Power Plant Accident; Understanding Formation Mechanism of Radioactive Particles through Sr and Pu Quantities

Igarashi, Junya*; Ninomiya, Kazuhiko*; Zheng, J.*; Zhang, Z. J.*; Fukuda, Miho*; Aono, Tatsuo*; Minowa, Haruka*; Yoshikawa, Hideki*; Sueki, Keisuke*; Satou, Yukihiko; et al.

Environmental Science & Technology, 58(33), p.14823 - 14830, 2024/08

https://doi.org/10.1021/acs.est.4c03428

Review of articles related to the accident of TEPCO's Fukushima Daiichi Nuclear Power Station published on Japanese Journal of Health Physics; Opinion and others

Takahara, Shogo; Iimoto, Takeshi*; Igarashi, Takayuki*; Kawabata, Masako*

Hoken Butsuri (Internet), 58(2), p.50 - 58, 2023/08

https://doi.org/10.5453/jhps.58.50

The Health Physics Society of Japan established a working group to obtain the insights and findings from the articles, which are related to the Fukushima Daiichi Nuclear Power Station (1F) accident, published in the Japanese Journal of Health Physics. This paper describes the results of the review on 47 articles, which are classified into the field without risk communication, environmental measurement and monitoring, radiation dose measurement and assessment, radiation medicine and radioactive waste. In the reviewed articles, there are various insights and issues depending on the standpoint of the authors and social interests in the timing those published. It is important to face these insights and issues to consider prudently "what is health physics or radiation protection?" for the future development of the Health Physics society.

Penetration of Cs and Sr into cracked dry carbonated mortar considering the contamination history of Fukushima Daiichi NPP

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

Dust behavior during laser cutting and water quality during muddy water cleaning in huge water tank

Miyamoto, Yuta; Uemura, Masaru*; Igarashi, Masahiro*; Maeda, Hideo*

Reiwa-3-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 24, P. 36, 2022/11

The laser cutting of test pieces which simulated the structural materials of the Advanced Thermal Reactor "FUGEN" was performed at a water depth of 10 m. During the cutting process, we obtained data on the behavior of particulate matter such as dust and dross generated by underwater laser cutting, and changes in water quality related to the cleaning of water in test tank that became muddy after cutting.

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

https://doi.org/10.1063/5.0071166

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

https://doi.org/10.2355/isijinternational.ISIJINT-2020-065

In order to clarify the effect of metal cations (Zn, Mg, 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 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.

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