Sparge Sampling of Molten Salts for Online Monitoring via Laser-Induced Breakdown Spectroscopy

Area of Science:

• Analytical Chemistry
• Nuclear Engineering

Background:

• Real-time molten salt composition monitoring is vital for advancing molten salt nuclear reactors.
• Existing sampling methods may have limitations in efficiency and resource consumption.

Purpose of the Study:

• To develop and characterize a sparge sampling method for molten salt aerosol generation and transport.
• To compare the sparge method with a Collison nebulizer for aerosol production and transport.
• To optimize laser-induced breakdown spectroscopy (LIBS) parameters for molten salt aerosol analysis.

Main Methods:

• Developed a sparge sampling technique to create and transport molten salt aerosols.
• Utilized a cascade impactor to determine aerosol size distribution (0.5–5.0 μm).
• Investigated aerosol transport efficiency over varying gas flow rates and distances.
• Analyzed the impact of laser energy and delay time on LIBS signal quality.

Main Results:

• Sparge sampling produced aerosols effectively without heating, though agglomeration reduced transport efficiency.
• The sparge method consumed less sample and gas than a Collison nebulizer, yielding more concentrated aerosols (up to 5 μg L⁻¹).
• Optimal LIBS parameters were identified for signal enhancement and improved signal-to-noise ratios.
• Successful calibration for Sr and Li demonstrated online monitoring capabilities with low detection limits.

Conclusions:

• The developed sparge sampling method is a viable technique for generating and transporting molten salt aerosols for LIBS analysis.
• This method offers advantages in sample and gas consumption compared to traditional nebulizers.
• The system demonstrates potential for real-time compositional monitoring in molten salt applications, particularly for nuclear reactors.