Laser-induced breakdown spectroscopy of light water reactor simulated used nuclear fuel: Main oxide phase

Abstract

The analysis of light water reactor simulated used nuclear fuel using laser-induced breakdown spectroscopy (LIBS) is explored using a simplified version of the main oxide phase. The main oxide phase consists of the actinides, lanthanides, and zirconium. The purpose of this study is to develop a rapid, quantitative technique for measuring zirconium in a uranium dioxide matrix without the need to dissolve the material. A second set of materials including cerium oxide is also analyzed to determine precision and limit of detection (LOD) using LIBS in a complex matrix. Two types of samples are used in this study: binary and ternary oxide pellets. The ternary oxide, (U,Zr,Ce)O2 pellets used in this study are a simplified version the main oxide phase of used nuclear fuel. The binary oxides, (U,Ce)O2 and (U,Zr)O2 are also examined to determine spectral emission lines for Ce and Zr, potential spectral interferences with uranium and baseline LOD values for Ce and Zr in a UO2 matrix. In the spectral range of 200 to 800nm, 33 cerium lines and 25 zirconium lines were identified and shown to have linear correlation values (R2) >0.97 for both the binary and ternary oxides. The cerium LOD in the (U,Ce)O2 matrix ranged from 0.34 to 1.08wt% and 0.94 to 1.22wt% in (U,Ce,Zr)O2 for 33 of Ce emission lines. The zirconium limit of detection in the (U,Zr)O2 matrix ranged from 0.84 to 1.15wt% and 0.99 to 1.10wt% in (U,Ce,Zr)O2 for 25 Zr lines. The effect of multiple elements in the plasma and the impact on the LOD is discussed.