Underwater analysis of simulated corium debris using laser-induced breakdown spectroscopy

Oba, Hironori  ; Saeki, Morihisa; Ito, Chikara   ; Takano, Masahide ; Akaoka, Katsuaki ; Wakaida, Ikuo  ; Sakka, Tetsuo*; Thornton, B.*

In order to inspect the post-accident nuclear core reactor of the TEPCO Fukushima Daiichi Nuclear Power Plants, a transportable fiber-coupled laser-induced breakdown spectroscopy (LIBS) instrument has been developed. In this presentation, we report underwater analysis of simulated corium debris, (U,Zr)O, by the transportable fiber-coupled LIBS instrument. The experiments were carried out using a wavelength region of 7301100 nm for pulsed-lasers and plasma emission measurements, which shows no attenuation in the optical transmittance of the fiber optic cable by intense radiation dose. Based on the observed emission spectrum in the region of 750870 nm, we determined candidates of the emission lines of Zr, U and Fe that are applicable to analyses of the debris without mutual interference.