Some fission products (such as Cs) are used in medical and industrial radioactive sources. TcO 4 (pertechnetate) ion can react with steel surfaces to form a corrosion resistant layer. In this way these metaloxo anions act as anodic corrosion inhibitors - it renders the steel surface passive. The formation of TcO 2 on steel surfaces is one effect which will retard the release of Tc from nuclear waste drums and nuclear equipment which has become lost prior to decontamination (e.g. nuclear submarine reactors which have been lost at sea).