Corrosion at the liquid-air-interface (LAI) was observed in the dilute Hanford waste simulant at 50°C.
The present study aimed at improving the understanding of the contributing factors for the corrosion at
LAI. The obtained results indicated that the corrosion occurred at polarized potentials (e.g. 0 mV vs.
SCE) was mainly due to the consumption of nitrite locally near the interface and thus led to an
aggressive local chemistry. The results also suggest that the reactions with the CO2 in the ambient air
alone could not lead to substantial pH change in the meniscus; aeration galvanic cell did not appear to be
the major contributor for the LAI corrosion. It was found that LAI corrosion could be inhibited by
increasing nitrite concentration to 0.6 M or by ammonia. The threshold concentration of the latter
inhibitor appeared to be at 0.05 M added as NH4NO3. Additionally, LAI was not noted on the steel samples with simulated mill scale.
Keywords: nuclear waste simulant, liquid-air-interface, corrosion, water line corrosion