Effect of the hydrogen peroxide formed in tritiated water on the behavior of 316L stainless steel

The tritiated water used (at a concentration of 20 mg cm-3) contains radiolytic hydrogen peroxide and dissolved oxygen. In the plants for the reprocessing of this water, the pH necessarily has various values, and consequently we used two different pH, 4 and 11, in our studies. The free corrosion potential of the stainless steel, as well as the redox potential of the tritiated water taken immediately from stock are in the transpassive region. This results from the concentrations of the dissolved radiolytic species. If these are decomposed in the voltametric scans, these potentials shift to the prepassive region. This will show the importance of the concentration of radiolytic H2O2 on the corrosion of 316L stainless steel. Scanning electron microscope examinations show, that at the free corrosion potential of the steel located in transpassive region, small cracks are formed over all of the oxidized surface. Pits and cavities are also found, the latter tend to be located on the grain boundaries. ((orig.))