Thermodynamic and experimental study of corrosion behavior of vanadium-based alloy in liquid sodium-potassium coolant

A preliminary assessment of oxygen effect on vanadium solubility in Na-K melt eutectic composition has been carried out using mathematical framework of the subregular solution model and equations of coordination-cluster model. The effect of oxygen on the solubility of vanadium in the Na-K alloy can be considered as the result of short-range ordering in liquid metal solution. The negative deviations from the ideality for dilute oxygen solutions in Na-K solvent is one reason that explains the quantitative differences between Na and Na-K coolants, when we need to estimate the threshold oxygen concentration for the formation of ternary oxide NaVO2 on the surface of the solid vanadium in liquid sodium and in Na-K alloy. Isothermal capsule experiments qualitatively confirmed the results of calculations of vanadium solubility in Na0.32K0.68 alloy.