Nuclear Science and Engineering

MOSCATO

Molten Salt Chemistry and Transport Code

MOSCATO is a high-fidelity computational tool developed at Argonne National Laboratory for modeling electrochemistry, species transport, and corrosion in molten salt systems. The code is designed to support the analysis of molten salt reactors and related advanced nuclear technologies where structural material degradation is strongly coupled with salt chemistry, flow, temperature, and interfacial reactions.

Built on the scalable Nek5000/NekRS spectral element computational fluid dynamics framework, MOSCATO enables CFD-level simulation of coupled flow, heat transfer, ionic species transport, alloy diffusion, and salt–alloy interfacial reactions. This capability provides a mechanistic modeling approach for predicting corrosion behavior in complex molten salt components and small-loop systems.

Key Capabilities

MOSCATO includes several integrated physics capabilities:

  • High-fidelity molten salt flow and heat transfer simulation
  • Ionic species transport using Poisson–Nernst–Planck-type modeling
  • Electrochemical reaction modeling through Butler–Volmer kinetics
  • Alloy constituent diffusion modeling for structural materials
  • Coupled salt–alloy interface reactions
  • Spatially resolved prediction of corrosion and deposition behavior
  • Simulation of component-scale and small-loop molten salt systems
  • System-level acceleration approach for long-timescale corrosion evolution

Why MOSCATO?

Corrosion in molten salt systems is driven by coupled chemical, electrochemical, thermal, and flow processes. Traditional lower-fidelity tools often rely on empirical mass-transfer correlations, simplified temperature distributions, or lumped system assumptions. These approaches may not capture localized corrosion behavior in complex geometries.

MOSCATO addresses this gap by directly resolving flow, temperature, and species transport fields while coupling them with electrochemical reaction kinetics and alloy diffusion. This makes it possible to evaluate how local thermal-hydraulic conditions influence corrosion rates, material depletion, and species redistribution in molten salt systems.

Applications

MOSCATO is intended for advanced reactor and molten salt technology applications, including:

  • Molten salt reactor corrosion analysis
  • Coolant salt and fuel salt chemistry studies
  • Structural alloy degradation assessment
  • Flowing salt loop simulations
  • Component-level corrosion prediction
  • Support for experimental interpretation and model validation
  • High-fidelity benchmark generation for lower-order corrosion models

Verification and Validation

MOSCATO has been tested through a multi-step verification and validation campaign. The electrochemical transport solver was verified against reference numerical solutions. The coupled flow, transport, and electrode kinetics capability was validated using thermogalvanic cell experimental data. The corrosion modeling capability was further assessed using flowing FLiNaK salt loop experiments involving stainless steel samples.

Comparison of sample mass change at 1000 hours.

These studies demonstrate MOSCATO’s ability to reproduce key electrochemical transport behavior and corrosion trends in molten salt environments.

Computational Framework

MOSCATO is implemented within the Nek5000/NekRS ecosystem, leveraging high-order spectral element methods and high-performance computing capabilities. This enables scalable, high-resolution simulations of molten salt chemistry and corrosion phenomena in realistic geometries.

Contact

For more information about MOSCATO, please contact:

Haomin Yuan
Nuclear Science and Engineering Division
Argonne National Laboratory