Determination of impurities in thoria (ThO2) using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS)

Elemental impurities in nuclear grade thoria were determined using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) employing ArF laser (20 ns, 193 nm, 20 Hz). Three certified standards of thoria, prepared in the Department of Atomic Energy (DAE), India were used for this work. Magnesium was used as an internal standard for quantification in view of its addition during fuel fabrication. The concentrations determined for 16 different elements (Al, B, Cd, Ce, Cu, Dy, Er, Eu, Fe, Gd, Mg, Mn, Mo, Ni, Sb, Sm and V), spanning four orders of magnitude, were within 20% of the certified values in the standards. The methodology is of interest to reduce the analytical effort with regard to dissolution of thoria samples, avoid the production of radioactive liquid waste streams and relatively simple mass spectrum as compared to complex emission spectra in atomic emission spectroscopy (AES) and laser induced breakdown spectroscopy (LIBS). The development and validation of analytical methodologies based on independent physico-chemical principles is of great relevance to characterize the in-house prepared working standards for routine applications.