Effect of nitrogen on corrosion behaviour of 304LN SS in nitric acid and simulated high level waste by electrochemical noise

Abstract

The effect of nitrogen on the corrosion resistance of 304LN SS containing 0.132, 0.193 and 0.406 wt-% N was investigated in 1M, 4M and 8M nitric acid and simulated high level waste (HLW) using electrochemical noise (EN) technique. Statistical, spectral, shot noise and wavelet methods were employed for EN analysis. Noise resistance and spectral noise resistance increased, while characteristic frequency decreased with increase in nitrogen content, implying lower corrosion activity with increase in nitrogen content. The cumulative probability plots obtained from shot noise analysis showed a shift towards lower frequency with increase in nitrogen content, and toward higher frequency with increase in concentration of nitric acid. Wavelet analysis of current noise was used for deriving mechanistic information. Micro laser Raman studies were carried out for passive film analysis. The results are detailed in the manuscript.