100 m fiber-coupled microchip laser-induced breakdown spectroscopy for remote elemental analysis applications

Batsaikhan, M.; 大場 弘則  ; 若井田 育夫  

Batsaikhan, M.; Oba, Hironori; Wakaida, Ikuo

This study aims to develop ultralong fiber optic cable (FOC) coupled microchip laser-induced breakdown spectroscopy (mLIBS) to reveal the elemental distribution and local composition of nuclear fuel debris in an accident-damaged reactors at Fukushima Daiichi Nuclear Power Station (FDNPS). Currently at FDNPS, the distance between the area where humans can safely work in a sufficient space and the nuclear fuel debris is expected to be over 100 m. Therefore, it becomes crucial to analyze the light transmittance performance of FOC-coupled mLIBS systems over such long distances in a high-radiation environment. We found that compared with an FOC with low-OH groups, that with high-OH groups exhibits better light transmittance performance. The maximum FOC length for microchip crystal oscillation is estimated to be longer than 800 m, although attenuation is observed with the increase in FOC length. Quantitative analysis of Gd is successfully performed in the visible region using the mLIBS system coupled with up to 300 m-long FOCs, with the limits of detection being between 0.1% and 0.2%.