Detection of Uranium and Chemical State Analysis of Individual Radioactive Microparticles Emitted from the Fukushima Nuclear Accident Using Multiple Synchrotron Radiation X-ray Analyses
Yoshinari Abe *†, Yushin Iizawa †, Yasuko Terada ‡, Kouji Adachi §, Yasuhito Igarashi §, and Izumi Nakai *†
† Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
‡ Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
§ Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki 305-0052, Japan
Anal. Chem., Article ASAP
DOI: 10.1021/ac501998d
Publication Date (Web): August 1, 2014
Copyright © 2014 American Chemical Society
Abstract
Synchrotron radiation (SR) X-ray microbeam analyses revealed the detailed chemical nature of radioactive aerosol microparticles emitted during the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, resulting in better understanding of what occurred in the plant during the early stages of the accident. Three spherical microparticles (2 μm, diameter) containing radioactive Cs were found in aerosol samples collected on March 14th and 15th, 2011, in Tsukuba, 172 km southwest of the FDNPP. SR-μ-X-ray fluorescence analysis detected the following 10 heavy elements in all three particles: Fe, Zn, Rb, Zr, Mo, Sn, Sb, Te, Cs, and Ba. In addition, U was found for the first time in two of the particles, further confirmed by U L−edge X-ray absorption near-edge structure (XANES) spectra, implying that U fuel and its fission products were contained in these particles along with radioactive Cs. These results strongly suggest that the FDNPP was damaged sufficiently to emit U fuel and fission products outside the containment vessel as aerosol particles. SR-μ-XANES spectra of Fe, Zn, Mo, and Sn K−edges for the individual particles revealed that they were present at high oxidation states, i.e., Fe3+, Zn2+, Mo6+, and Sn4+ in the glass matrix, confirmed by SR-μ-X-ray diffraction analysis. These radioactive materials in a glassy state may remain in the environment longer than those emitted as water-soluble radioactive Cs aerosol particles.
