Monitoring and inhibiting corrosion with radioactive 99Tc(VII)

The radioactivity of technetium was found to be useful in monitoring the corrosion of St-20, St-40, and St-0.8kp low-alloy steels in neutral solutions. Measurements of changes in corrosion rates, radioactivity of test technetium solutions, and adsorption of pertechnetate ion on the sample surface led to the conclusion that a minimum concentration of 10-4 M TcO4- completely suppressed the corrosion of low-alloy steels. The samples were similarly affected in sea-water (3% NaCl) by increasing the inhibitor concentration to 1.25 x 10-1 M but this was unacceptable from the viewpoints of economics and radiation safety