Speciation of cesium in a radiocesium-bearing microparticle emitted from Unit 1 during the Fukushima nuclear accident by XANES spectroscopy using transition edge sensor

Published

September 5, 2025

Author(s)

Yoshio Takahashi, Shinya Yamada, Hikaru Miura, Yuichi Kurihara, Oki Sekizawa, Kiyofumi Nitta, Tadashi Hashimoto, Masato Tanaka, Minako Kurisu, Shinji Okada, Takaaki Itai, Hiroki Suga, Teruhiko Kashiwabara, Kohei Sakata, Hideyuki Tatsuno, Ryota Hayakawa, Hirotaka Suda, Takaya Ohashi, Yoshitaka Ishisaki, Takuma Okumura, Yuto Ichinohe, Tasuku Hayashi, Yuki Imai, Hirofumi Noda, Toru Tamagawa, Tadaaki Isobe, Toshiyuki Azuma, William Doriese, Joel Ullom, Daniel Swetz, Malcolm Durkin, Galen O'Neil, Satoshi Kohjiro, Shogo Higaki, Daisuke Tsumune, Masayoshi Yamamoto, Tomoya Uruga

Abstract

The chemical state of radiocesium (RCs) was determined using X-ray absorption near-edge structure (XANES) in fluorescence mode and microbeam X-ray fluorescence (μ-XRF) mapping for the cesium (Cs) incorporated in a radiocesium-bearing silica microparticle (CsMP) that was released during the Fukushima Dai-ichi Nuclear Power Plant accident in 2011. The sample investigated here was classified as a CsMP emitted from Unit 1 (diameter: approximately 500 µm; Cs weight concentration: approximately 50 µg/g). The Cs Lα emission from this Type-B CsMP with a much lower Cs concentration than those of calcium and titanium was difficult to detect using a silicon drift detector, severely decreasing the signal-to-background ratio of the Cs Lα emission. In this study, a high-energy-resolution energy-dispersive transition-edge sensor was used for X-ray spectroscopic analysis, which enabled the measurement of Cs LIII-edge XANES for RCs in the Type-B CsMP. The results revealed the presence of two distinct RCs species in CsMPs. Bulk XANES analysis indicated that one species consists of RCs dissolved in the silicate matrix. Additionally, μ-XRF-XANES revealed that the RCs species were heterogeneously distributed within the CsMP with enrichment observed on the surfaces of internal voids, suggesting that the gaseous RCs species, such as CsCl, adhered to these surfaces during the cooling process of the molten silicate. The speciation and μm-scale mapping of RCs provide further insights into (i) the formation process of spherical Type-B CsMP and (ii) the incorporation and internal distribution processes of RCs within the particle.

Citation

Journal of Hazardous Materials

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.jhazmat.2025.139031

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Keywords

Radiocesium (RCs)-bearing silica microparticle (CsMP), Fukushima Dai-ichi nuclear power plant (FDNPP) accident, μ-XRF-XAFS, Speciation and internal distribution of RCs in CsMP, Cs dissolved in silicate and CsCl

Citation

Takahashi, Y. , Yamada, S. , Miura, H. , Kurihara, Y. , Sekizawa, O. , Nitta, K. , Hashimoto, T. , Tanaka, M. , Kurisu, M. , Okada, S. , Itai, T. , Suga, H. , Kashiwabara, T. , Sakata, K. , Tatsuno, H. , Hayakawa, R. , Suda, H. , Ohashi, T. , Ishisaki, Y. , Okumura, T. , Ichinohe, Y. , Hayashi, T. , Imai, Y. , Noda, H. , Tamagawa, T. , Isobe, T. , Azuma, T. , Doriese, W. , Ullom, J. , Swetz, D. , Durkin, M. , O'Neil, G. , Kohjiro, S. , Higaki, S. , Tsumune, D. , Yamamoto, M. and Uruga, T. (2025), Speciation of cesium in a radiocesium-bearing microparticle emitted from Unit 1 during the Fukushima nuclear accident by XANES spectroscopy using transition edge sensor, Journal of Hazardous Materials, [online], https://doi.org/10.1016/j.jhazmat.2025.139031, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=930228 (Accessed October 13, 2025)