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Laser-Induced Breakdown Spectroscopy for the On-Line Multielement Analysis of Highly Radioactive Glass Melt Simulants. Part II: Analyses of Molten Glass Samples

The paper presents the application of laser-induced breakdown spectroscopy (LIBS) for the on-line multielement analyses of glass melts in a vitrification process of high level liquid waste (HLLW). The third harmonic pulse of an Nd:YAG laser is used for the generation of plasma on the molten glass surface and the plasma emission is monitored by an echelle spectrometer with an intensified charge-coupled device (ICCD), which simultaneously covers the wavelength range from 200 to 780 nm. Twelve different reference HLLW glass melts with a complex composition of about 27 chemical elements are simulated on a laboratory scale, varying the HLLW component concentration. By real-time analyses of the reference glasses at 1200 °C, the analytical method is calibrated. A multivariate regression approach with partial least squares (PLS) is used for the data evaluation. The LIBS method thus calibrated is then applied for the multielement analysis of molten glass samples from the prototype vitrification plant under operation in our institute. The results underline that the LIBS method can be applied to a vitrification process for the on-line multielement analysis of highly radioactive glass melts.