Following the Great East Japan earthquake and tsunami in 2011, reactor core overheating and fuel melting in the Fukushima Daiichi Nuclear Power Station produced microparticles from vaporized and rapidly solidified nuclear material for which chemical structures remain underexplored. Here, the authors present synchrotron-based X-ray absorption fine structure and X-ray diffraction studies of microparticles recovered from inside Unit 2 of the station, identifying uranium-rich particles with cubic UO2 and mixed U-Zr oxides with tetragonal ZrO2, the latter indicating rapid cooling from a high-temperature metastable phase above 1650 °C.
- Tohru Kobayashi
- Masaaki Kobata
- Tsuyoshi Yaita
