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Application of Laser Induced Breakdown Spectroscopy to Electrochemical Process Monitoring of Molten Chloride Salts

Nicholas A. Smith, Joseph A. Savina, Mark A. Williamson, Argonne National Laboratory, Argonne, Illinois, USA Safeguards for Reprocessing and Pyroprocessing Facilities: E-Posters (200)

• Use Laser Induced Breakdown Spectroscopy to measure actinide

concentrations in near real time

• Challenges to performing measurements inside an electrochemical

refiner in a processing canyon or hot cell

– In situ sampling and analysis

• Grab sampling may not be representative, is time intensive
• Difficult to transport samples

– Temperatures up to 600°C

• Large furnaces and heat shielding

– High radiation field

• Sensitive electronics must reside outside of containment

– Argon atmosphere (requires containment) – Limited access, manipulation

• Requires simple installation and alignment

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Technical Challenge

Information

Electrorefiner

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Application of Laser Induced Breakdown Spectroscopy to Electrochemical Process Monitoring of Molten Chloride Salts

Nicholas A. Smith, Joseph A. Savina, Mark A. Williamson, Argonne National Laboratory, Argonne, Illinois, USA Safeguards for Reprocessing and Pyroprocessing Facilities: E-Posters (200)

• Use Commercial Off The Shelf components where possible

– Andor Shamrock 750 Spectrometer – Andor iStar iCCD camera and Digital Delay Generator – Quantel CFR 200 Nd:YAG laser

• Design requirements:

– 500 mm standoff distance (lens to sample) – Plasma emissions collected via fiber optic – Class I laser system – Free beam path laser delivery was developed

• The laser irradiance required to ignite a plasma at standoff distances requires

large core fibers to avoid burn out

• Large core fibers do not deliver a collimated beam which prevented focusing at

long focal lengths

• Required development of novel feed-through to add optical, logic and data connections

to the glovebox without breaking containment

Argonne Approach

Laser is delivered to the sample chamber by a series of beam tubes and mirrors.

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Application of Laser Induced Breakdown Spectroscopy to Electrochemical Process Monitoring of Molten Chloride Salts

Nicholas A. Smith, Joseph A. Savina, Mark A. Williamson, Argonne National Laboratory, Argonne, Illinois, USA Safeguards for Reprocessing and Pyroprocessing Facilities: E-Posters (200)

• Use Commercial Off The Shelf components where possible

– Andor Shamrock 750 Spectrometer – Andor iStar iCCD camera and Digital Delay Generator – Quantel CFR 200 Nd:YAG laser

• Design requirements:

– 500 mm standoff distance (lens to sample) – Plasma emissions collected via fiber optic – Class I laser system – Free beam path laser delivery was developed

• The laser irradiance required to ignite a plasma at standoff distances

requires large core fibers to avoid burn out

• Large core fibers do not deliver a collimated beam which prevented

focusing at long focal lengths

• Required development of novel feed-through to add optical, logic and data

connections to the glovebox without breaking containment

Argonne Approach

Laser is delivered to the sample chamber by a series of beam tubes and mirrors.

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Application of Laser Induced Breakdown Spectroscopy to Electrochemical Process Monitoring of Molten Chloride Salts

Nicholas A. Smith, Joseph A. Savina, Mark A. Williamson, Argonne National Laboratory, Argonne, Illinois, USA Safeguards for Reprocessing and Pyroprocessing Facilities: E-Posters (200)

• Bench top tests

– System assembled in a horizontal configuration – Components were tested as a system

• Alignment and focus tests were

carried out

– Multiple metal standards were analyzed

• A United States penny
• Inconel (Ni/Cr/Fe)
• E-Brite (Fe/Cr)

– System easily resolved major metal constituents

LIBS Testing Zinc Cu

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Application of Laser Induced Breakdown Spectroscopy to Electrochemical Process Monitoring of Molten Chloride Salts

Nicholas A. Smith, Joseph A. Savina, Mark A. Williamson, Argonne National Laboratory, Argonne, Illinois, USA Safeguards for Reprocessing and Pyroprocessing Facilities: E-Posters (200)

LIBS spectra of Inconel Crucible at 25°C (bottom) and 450°C (top), corrected for on-CCD

• accumulations. Both graphs are displayed on the same scale, though the intensity scale was

shifted for clarity.

• Glove box installation and testing

– Initial tests focused on spectrometer performance – Tests of Inconel were repeated at multiple temperatures

• Initial tests of Pu, U, Np trichlorides

in LiCl/KCl were inconclusive

– The high laser power bored holes through the frozen salt – Molten salt tests required low repetition rates to minimize splashing – Optical transparency of salts requires positioning of focal point at surface

• Subsurface plasma severely reduces

signal

LIBS Testing

Salt Tests: Left – Spectrum of frozen PuCl3/LiCl/KCl salt cake (inset) showing large lines attributed to Li and K. Right – Variation of spectral intensity for surface (blue) vs. subsurface (red) plasma formation.

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Application of Laser Induced Breakdown Spectroscopy to Electrochemical Process Monitoring of Molten Chloride Salts

Nicholas A. Smith, Joseph A. Savina, Mark A. Williamson, Argonne National Laboratory, Argonne, Illinois, USA Safeguards for Reprocessing and Pyroprocessing Facilities: E-Posters (200)

• The glovebox scale LIBS system successfully fulfilled the

design parameters

– Plasma was ignited at standoff distances – The emissions were collected and transmitted via fiber optics – The system was certified as a Class I laser

• The system was able to measure the LIBS emissions from an

Inconel sample

– LIBS emissions were collected and analyzed – Spectral resolution is comparable to telescopic systems

• The system provides the proof of concept to move forward

with an engineering scale design

• Additional studies are in progress

– Collection of actinide LIBS spectra for quantitative measurements

• Spectral lines/responses, limits of detection, potential interferences

– Continued development of the hardware for incorporation

Conclusions

• Delivery of laser beam can be

accomplished using commercially available goniometer system

– Systems are made for robotic automation systems and industrial applications – Laser, detector and spectrometers are available in multiple configurations depending on the application

• The sample chamber design must be

finalized and miniaturized

– Available space on the electrorefiner is limited – Final design, regardless of laser delivery method, must be fully self-aligning

Plant Scale Concepts