Overview
A research team led by Associate Professor Shinya Yamasaki of the Radioisotope Research Division, CRiES, University of Tsukuba, and Professor Satoshi Utsunomiya of National Taiwan University has published a new study in the Journal of Hazardous Materials. The findings were also featured in a press release issued by the University of Tsukuba.
※Press release document （PDF855KB）(Available in Japanese only.)
The study investigated the large-scale distribution and dispersion processes of radioactive cesium-rich microparticles (CsMPs) released during the Fukushima Daiichi Nuclear Power Plant accident. By analyzing soil samples collected from 100 locations across Fukushima Prefecture, the researchers found substantial regional variations in both the abundance of CsMPs and their contribution to total radioactivity. In some areas, more than 60% of the soil radioactivity was attributable to CsMPs.
Comparison with atmospheric dispersion simulations further revealed that large quantities of CsMPs were generated and released during the early hours of March 15, 2011, and subsequently transported over a wide area of Fukushima Prefecture under prevailing meteorological conditions. In contrast, radioactive plumes released after March 16 contained few CsMPs and were dominated by more water-soluble forms of radioactive cesium.
These findings improve our understanding of the environmental behavior of radioactive microparticles released during nuclear accidents and provide valuable information for future environmental risk assessments and dispersion modeling of radioactive contaminants.
Publication Information
Uncovering Hidden Dispersion Patterns of Radioactive Cesium-Rich Microparticles from Fukushima Daiichi
Miyazaki, K., Fueda, K., Kadowaki, M., Terada, H., Kozai, N., Iwata, H., Horie, K., Takehara, M., Yamasaki, S., Grambow, B., Law, G.T.W., Ewing, R.C., Utsunomiya, S., Journal of Hazardous Materials, 511, (2026), DOI:10.1016/j.jhazmat.2026.142180 (P-25-13)
Media coverage
- Mainichi Shimbun (June 12, 2026)
“Cesium Balls Released by the Fukushima Nuclear Accident Found to Have Spread Over a Wide Area: Study by University of Tsukuba and Collaborators”
(Available in Japanese only.) - Kyodo News (June 20, 2026; published on 47NEWS)
Identification of dispersion pathways of cesium-bearing microparticles:
Formed immediately after the Fukushima accident and subsequently dispersed
(Available in Japanese only.) - Tokyo Shimbun (July 27, 2026)
“Dispersion of Cesium-Bearing Microparticles Released by the Fukushima Daiichi Nuclear Power Plant Accident Elucidated” (Doki Doki! Science column)
(Available in Japanese only.)