15/12/04 00:18:06.58 uguzwa1r.net
Detection of Uranium and Chemical State Analysis of Individual Radioactive Microparticles Emitted from the Fukushima Nuclear Accident
URLﾘﾝｸ(pubs.acs.org)
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.