Mechanism of Tellurium Induced Nickel Alloy Corrosion in Molten Licl-Kcl Salt

Fission product tellurium causes severe embrittlement of nickel alloys in nuclear molten fuel salt systems. This paper investigates the tellurium chemistry in molten LiCl-KCl-Li2Te salts and the tellurium reactions at the alloy interface. The reactions for the two-step reduction of Te0 and the electrochemical formation of nickel tellurides have been identified from cyclic voltammograms. The corrosion of UNS N10003 alloy with different tellurium salt chemistries and applied potentials found that tellurium corrosion attack is only present at potentials more positive than the Ni1.43Te/Te2- potential. The critical potential is thus suggested for mitigating tellurium embrittlement using the redox control technique.