title: Constituent elements and their distribution in the radioactive Cs-bearing silicate glass microparticles released from Fukushima nuclear plant.
abstract: Microparticles of radioactive cesium (Cs)-bearing silicate glass emitted from the Fukushima Daiichi nuclear power plant were investigated mainly using state-of-the-art energy-dispersive X-ray spectroscopy in scanning transmission electron microscopes. Precise elemental maps of the particles were obtained using double silicon drift detectors with a large collection angle of X-rays, and qualitative elemental analysis was performed using high-resolution X-ray spectroscopy with a microcalorimetry detector. Beside the substantial elements (O, Si, Cl, K, Fe, Zn, Rb, Sn and Cs) as previously reported, Mn and Ba were also common, though their amounts were small. The atomic ratios of the substantial elements were not the same but varied among individual particles. Fe and Zn were relatively homogeneously distributed, whereas the concentration of alkali ions varied radially. Generally, Cs was rich and K and Rb were poor outward of the particles but the degree of such radial dependence was considerably different among the particles. A concentration of Sn on the particle surface was observed. High-resolution imaging indicated the formation of SnO2(cassiterite) nanocrystals on the surface. Synthesis of the bulk glass with a similar composition to the microparticles was attempted by quenching the silicate melt from ∼1600°C. However, homogeneous silicate glass like that of the microparticles could not be obtained due to the segregation of nano-spherules rich in Fe and Zn, suggesting that the microparticles were formed in a very specific condition in the nuclear reactor.
authors: Department of Earth & Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan kogure@eps.s.u-tokyo.ac.jp.
authors: Toshihiro
authors: T
authors: Kogure
authors: National Institute for Agro-Environmental Science, NARO, 3-1-3, Tsukuba, Ibaraki 305-8604, Japan.
authors: Noriko
authors: N
authors: Yamaguchi
authors: National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors: Hiroyo
authors: H
authors: Segawa
authors: Department of Earth & Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors: Hiroki
authors: H
authors: Mukai
authors: Department of Earth & Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors: Satoko
authors: S
authors: Motai
authors: International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors: Kotone
authors: K
authors: Akiyama-Hasegawa
authors: International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors: Masanori
authors: M
authors: Mitome
authors: Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
authors: Toru
authors: T
authors: Hara
authors: Quantum Beam Science Center and Fukushima Environmental Safety Center, Japan Atomic Energy Agency, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
authors: Tsuyoshi
authors: T
authors: Yaita
mesh_terms: D002588:Cesium Radioisotopes / Q000032:analysis*; D062406:Fukushima Nuclear Accident; D005898:Glass / Q000032:analysis*; D007564:Japan; D017348:Microscopy, Electron, Scanning Transmission; D055848:Nuclear Power Plants; D011834:Radiation Monitoring; D017640:Silicates / Q000032:analysis*; D012987:Soil / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission
chemical_list: D002588:Cesium Radioisotopes; D017640:Silicates; D012987:Soil
keywords: Fukushima nuclear plant; energy-dispersive X-ray spectroscopy; microcalorimeter; microparticle; scanning transmission electron microscopy; silicate glass