Molten fluorides for nuclear applications

TLDR

Pyrochemistry is increasingly recognized as essential in nuclear technology, with molten salts used for fuel processing, recycling, heat transfer, homogeneous fuel, and fusion breeding, especially stable fluorides that withstand high temperatures and neutron flux. The study investigates the thermodynamics of corrosion in molten fluorides to guide material selection and purification design. The authors analyze mass‑transfer thermodynamics, evaluate metallic compatibility, and propose purification methods. Analysis of several field cases shows that corrosion in molten fluorides is essentially due to the oxidation of metals by uranium fluoride and/or oxidizing impurities.

Abstract

The importance of pyrochemistry is being increasingly acknowledged and becomes unavoidable in the nuclear field. Molten salts may be used for fuel processing and spent fuel recycling, for heat transfer, as a homogeneous fuel and as a breeder material in fusion systems. Fluorides that are stable at high temperature and under high neutron flux are especially promising. Analysis of several field cases reveals that corrosion in molten fluorides is essentially due to the oxidation of metals by uranium fluoride and/or oxidizing impurities. The thermodynamics of this process are discussed with an emphasis on understanding the mass transfer in the systems, selecting appropriate metallic materials and designing effective purification methods.