Applications of Thermochemical Modeling in Molten Salt Reactors

Area of Science:

• Nuclear Engineering
• Materials Science
• Chemical Thermodynamics

Background:

• Molten salt reactors (MSRs) offer potential advantages in nuclear energy.
• Understanding fuel and fission product behavior under irradiation is critical for MSR design and safety.
• Existing thermodynamic data requires comprehensive evaluation for MSR applications.

Purpose of the Study:

• To utilize a consistent thermodynamic database for examining molten salt reactor fuel behavior.
• To visually map the stability of fuel and fission product components in MSR fuel systems.
• To analyze the thermochemical behavior of MSRs at high burnup.

Main Methods:

• Employed the Molten Salt Thermal Properties Database-Thermochemical (MSTDB-TC) and ancillary data.
• Generated Ellingham diagrams for chloride and fluoride salt systems to assess component stability.
• Performed global equilibrium calculations for specific MSR designs at high burnup.

Main Results:

• Ellingham diagrams effectively identified halide-forming components in fuel/solvent salt systems.
• Global equilibrium calculations provided detailed compositions for MSR systems at 100 GWd/t burnup.
• Burnup in MSRs was shown to be an oxidative process, impacting redox behavior.

Conclusions:

• The MSTDB-TC is a valuable resource for MSR fuel behavior analysis.
• Ellingham diagrams offer a powerful visual tool for MSR system design and component selection.
• Understanding redox behavior during burnup is essential for MSR operational control and safety.