Contamination Study of Austenitic Stainless Steel for Nuclear Reactor Coolant Pump by Carbon Steel

The austenitic stainless steel can be contaminated by carbon steel if they contact with each other directly during the process of machining, transportation or assembly. Thus, the property of corrosion resistance of austenitic stainless steel will be influenced. As well known, the property of corrosion resistance of austenitic stainless for nuclear reactor coolant pump is strictly important. Therefore, the work focused on the contamination of austenitic steel, Z2CN18-10, which was used for nuclear reactor coolant pump, by carbon steel. The corrosion test of FeCl₃ and anodic polarization curve test were performed in the work. The results present that the carbon steel attached to the surface of the stainless steel doesn’t show obviously effect on the long-term general corrosion rate. The carbon steel particles embedded into the austenitic steel significantly reduce its pitting corrosion potential and increase the tendency of pitting corrosion. HNO₃ passivation can partly counteract the decrease of pitting corrosion potential value of the contaminated austenitic stainless steel samples, but which is still much lower than that from the samples of uncontaminated and passivated in the same way. In addition, the effects of carbon steel contamination on nuclear radiation field and thermal conductivity of fuel cladding were discussed.