Abstract: A method of decontaminating radio nuclide-contaminated corrosion products, which are sparingly soluble in acid, from primary system surfaces in reactors of the pressurized water reactor type and the boiler reactor type with hydrogen dosage and similar, by oxidation and concurrent dissolution in an acidic decontamination solution of the acid soluble corrosion products obtained by said oxidation. The characteristic feature of the method is that said oxidation is performed with Ce.sup.4+ ions, ozone and chromic acid in the presence of perhalogen acid, preferably perchloric acid, at a pH below 3.

Abstract: A method of decontaminating radionuclide-contaminated acid insoluble corrosion products from primary system surfaces in pressurized water reactors by oxidation and concurrent dissolution in an acidic decontamination solution of the corrosion products which have been made acid-soluble by the oxidation. The characterizing feature of the method is that the oxidation is carried out at relatively low temperatures with a water-based oxidation agent having a pH below 7 and containing cerium nitrate, chromic acid and ozone.