Lower-length-scale modeling of chemical additions, corrosion and fission products in select MSR base salts

Technical Report · Sat Sep 30 04:00:00 EDT 2023

DOI:https://doi.org/10.2172/2373172· OSTI ID:2373172

Jiang, Chao ^[1]; Andersson, David ^[2]; Wang, Gaoxue ^[2]; Li, Bo ^[2]; Yang, Ping ^[2]

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1. Idaho National Laboratory (INL), Idaho Falls, ID (United States)
2. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Molten salts play a crucial role in advancing Generation IV nuclear energy technology, with chloride-based salts like NaCl-UCl₃ garnering significant attention due to their distinctive properties. However, the corrosive nature of molten salts causes the dissolution of chromium (Cr), leading to the formation of CrCl₂ and CrCl₃ species in molten chlorides. Moreover, the radioactive decay of nuclear fuel gives rise to fission products, including Cs, Sr, and I chlorides. The first part of this report presents a comprehensive study utilizing ab initio molecular dynamics (AIMD) simulations to investigate the properties of eutectic NaCl-UCl₃ molten salt in the presence of corrosion products (CrCl₂ and CrCl₃) and fission product (CsCl). The study focuses on essential structural and thermophysical properties such as density, mixing energy, coordination numbers (CN), and Radial Distribution Functions (RDF) of the salts with varying compositions of corrosion products and fission product, covering a range from 0% to 13.5%. The results offer valuable insights into the behavior of corrosion and fission products in uranium-based molten salts, providing essential data that can be used as input to the MTDB-TC and MSTDB-TP property databases being developed by the NEAMS program. Due to their favorable characteristics such as low melting points, high boiling points, and low costs, MgCl₂+NaCl+KCl (MNK) eutectic salts have recently attracted attention as high-temperature heat transfer fluids. The incorporation of LiCl into MNK salts can further reduce their melting points and increase their specific heat capacities, which is de- sirable for high-temperature heat transfer applications. The second part of this report presents the development and validation of a new shell-model potential for the MgCl₂+NaCl+KCl+LiCl system, which captures the polarization of Cl anions. The extensive comparison with experimental data and AIMD simulations demonstrates the accuracy and reliability of the potential. Furthermore, using this potential, we elucidate the intricate network structure in MNK eutectic salts that is formed through polyhedron sharing. This research contributes to a fundamental understanding of the atomic structures and thermophysical properties of multi-component molten salts, which is crucial for future development of heat transfer fluids for applications in molten salt reactors.

• Research Organization: Idaho National Laboratory (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE)
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 2373172
• Report Number(s): INL/RPT--23-75288-Rev000
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
modeling
molten salt
thermophysical property