Study on plasma temperature changes in Laser-Induced Breakdown Spectroscopy (LIBS) for decommissioning of Fukushima Daiichi Nuclear Power Station

狩野 貴宏 ; 赤岡 克昭 ; 若井田 育夫  

Karino, Takahiro; Akaoka, Katsuaki; Wakaida, Ikuo

In decommissioning of Fukushima Daiichi Nuclear Power Station, only a small amount of the debris removed can actually be analyzed in detail. Therefore, we propose to analyze debris efficiently by performing a simple analysis in advance using Laser Induced Breakdown Spectroscopy (LIBS). LIBS is an elemental analysis method by using laser generated plasma. Plasma emission is measured by spectrometer and identifies the elements contained in the debris. LIBS analysis is suitable for measuring large amounts of debris because it does not require sample pretreatment and only a few seconds of laser irradiation. In addition, the composition ratio of elements can also be determined by analysis using a calibration curve prepared in advance. To create a calibration curve, the intensity ratio of the spectrum is used, but the intensity ratio is affected by the plasma temperature. For this reason, it is desirable that the plasma temperature does not change in LIBS. However, the spectrum changes depending on the measurement conditions. (For example, when the composition ratio changes.) In such cases, the plasma temperature may also change. Therefore, in this study, we did experiments under various conditions to verify whether the plasma temperature changes.