Real-time detection system for hydrogen and boron isotopes using atomic and molecular spectra in laser-induced plasma

Abstract

The analyses of hydrogen and boron isotopes are essential to achieve the economic feasibility and reliability of nuclear power plant operation. This study aims to develop a real-time analysis technique for these isotopes using laser-induced breakdown spectroscopy (LIBS) and laser ablation molecular isotopic spectrometry (LAMIS). The research could be divided into two parts. Firstly, hydrogen isotopic analysis was conducted in liquid and frozen waters. The atomic and molecular emission of hydrogenated species were identified, and the measurement conditions were optimized according to each matrix. In addition, a partial least squares regression (PLSR) algorithm was constructed in order to perform quantitative analysis. The results from PLSR prediction were evaluated by cross-validation procedures. The error of quantitative analysis was compared according to the matrix and utilized species. The PLSR results provided excellent accuracy with 1% of standard error. Secondly, the boron isotopic analysis has been conducted in an aqueous boric acid solution. Double-pulse configuration was adopted to improve the detection sensitivity. Significant enhancement of the $BO_2$ emission was observed in the optimized double-pulse system. The detection limit was improved from about 700 ppm to 70 ppm for double pulse configuration. In addition, plasma characterization was performed to identify the signal enhancement mechanism. It was found that the plasma electron density and temperature could provide a positive effect on signal enhancement. In this thesis, the real-time monitoring system using LIBS-LAMIS was successfully developed for hydrogen and boron isotope detection in the nuclear power plant.