Often times corrosion is cited (especially by corrosion scientists) as the biggest hurdle in the development of molten salt reactors (MSRs) or salt-cooled reactors (FHRs); fusion systems that use the same molten salts for fuel breeding and cooling have still other hurdles at the top of the priority list – so maybe MSR and FHR reactor developers can consider themselves lucky to have a problem as tangible as corrosion at the top of their priority list. I posit that molten salts have an unjustified reputation as “highly corrosive.” There is little question (based on the current knowledge) that passivating layer is absent from the surface of metal alloys exposed to fluoride salts; but the lack of a passivating layer does not necessarily lead to high corrosion rates, as long as the chemistry of the salt is understood and is controlled to manage corrosion.<br/> <br/>This talk will provide an overview of salt chemistry considerations that impact material degradation in molten salt fission and fusion reactors: redox reactions, dissimilar materials, temperature gradients, the oxidizing effects of fission, the oxidizing effects of activation reactions, redox control methods, and redox buffers. The talk will also discuss kinetic parameters that may impact corrosion, and the limited understanding of the mechanisms of redox reactions at metal-salt interfaces; a mechanistic understanding of corrosion reactions is needed in order to postulate the coupling between irradiation and corrosion. The talk will also discuss the relevance of fluoroacidity to corrosion in molten salts. Lastly, the talk will discuss the possible thermodynamic and kinetic roles that anionic impurities (such as oxygen-containing anions) may play in corrosion of metal alloys.

Salt chemistry considerations in the study of corrosion in molten fluoride salts

ACS Fall 2020 Virtual Meeting

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