R4: Mineral sciences of the Earth surface

[R4-02] Particulate plutonium released from the Fukushima Daiichi meltdowns

*Satoshi Utsunomiya¹ (1. Kyushu Univ. Sci.)

Keywords:Fukushima Daiichi Nuclear Power Plant, Plutonium, Cesium, Synchrotron radiation, SIMS

We report the discovery of particulate Pu associated with cesium-rich microparticles (CsMPs) that formed in and were released from the reactors during the FDNPP meltdowns. The CsMPs contained discrete U(IV)O₂ nanoparticles, <~10 nm, one of which is enriched in Pu adjacent to fragments of Zr-cladding. The isotope ratios, ²³⁵U/²³⁸U, ²⁴⁰Pu/²³⁹Pu, and ²⁴²Pu/²³⁹Pu, of the CsMPs were determined to be ~0.0193, ~0.347, and ~0.065, respectively. Thus, the long-distance dispersion of Pu from FNDPP is attributed to the transport by CsMPs that have incorporated debris nano-fragments.