Quantification of Lanthanides in a Molten Salt Reactor Surrogate Off-Gas Stream Using Laser-Induced Breakdown...

Area of Science:

• Nuclear Engineering
• Analytical Chemistry
• Spectroscopy

Background:

• Molten salt reactors (MSRs) require robust off-gas treatment and monitoring systems for high-temperature, high-radiation environments.
• Real-time data acquisition is crucial for MSR operational safety and efficiency.

Purpose of the Study:

• To develop and validate laser-induced breakdown spectroscopy (LIBS) for monitoring molten salt aerosol streams in MSRs.
• To assess LIBS's capability for detecting fission products like Gadolinium (Gd), Neodymium (Nd), and Samarium (Sm).

Main Methods:

• A sheath gas method was developed to protect optical components and stabilize aerosol streams for LIBS analysis.
• Partial least squares (PLS) regression was employed to build calibration models for Gd, Nd, and Sm concentrations.
• A genetic algorithm was utilized to filter spectral data, optimizing the PLS models.

Main Results:

• The developed LIBS method successfully monitored Gd, Nd, and Sm in an aqueous aerosol system up to 2000 ppm.
• Genetic algorithm-filtered PLS models significantly improved prediction accuracy, reducing the root mean squared error of prediction by 73% for Gd, 18% for Nd, and 25% for Sm.
• Model predictions were validated against inductively coupled plasma optical emission spectroscopy (ICP-OES) with high confidence.

Conclusions:

• LIBS, enhanced with a genetic algorithm and PLS regression, is a viable tool for real-time monitoring of molten salt aerosols in MSRs.
• This technology addresses the need for advanced monitoring in demanding nuclear environments.
• The improved accuracy demonstrates the potential for enhanced safety and control in MSR operations.