Quantitative analysis of UF4 and ThF4 in Indian MSR fuel using laser induced breakdown spectroscopy

The Molten Salt Reactor (MSR) represents a significant addition to India's clean energy initiative through nuclear energy. Noteworthy for its inherent safety features and the utilization of mixed fluoride salts (U, Th, Li) as molten-liquid fuel, this reactor stands out as a unique advancement. This paper showcases the application of Laser-Induced Breakdown Spectroscopy (LIBS) to ensure the chemical composition of the fuel. The micro-destructive nature of the analysis, minimal sample preparation requirements and the potential for remote analysis position LIBS as a viable alternative to Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The study encompasses the quantification of UF₄ and ThF₄, demonstrating both univariate and multivariate chemometrics calibration approaches. Various normalization methods on the raw spectral data are explored, and the results are meticulously compared. Upon evaluating different analytical methods, the optimal accuracy and precision achieved were in the range of approximately 2.6% and 3.9% for UF₄, and about 0.4% and 0.5% for ThF₄, respectively. This underscores the effectiveness of LIBS in ensuring the accurate determination of chemical composition in the context of MSR fuel.