Study Reconstructs How a Single Radioactive Cloud Spread Cesium-Rich Microparticles Across Fukushima

A study published in the Journal of Hazardous Materials, led by researchers including National Taiwan University's Professor Satoshi Utsunomiya (with University of Tsukuba collaborators), combined soil analyses with atmospheric dispersion modeling to reconstruct how radioactive cesium-rich microparticles (CsMPs) spread across Fukushima Prefecture during the 2011 disaster. The team found that a single radioactive plume on March 15, 2011 — four days after the earthquake — was picked up by a gust of wind and rainfall, scattering CsMPs unevenly across a wide area extending toward the Tokyo metropolitan region, distinct from the dissolved-cesium fallout pattern concentrated northwest of the plant. Unlike dissolved cesium, these insoluble particles carry very high radioactivity per unit mass and may pose localized inhalation or ingestion risks where they settled.