Abstract: A method for decontaminating a metal surface exposed to radioactive liquid or gas during operation of a nuclear facility comprises an oxidation step wherein a metal oxide layer on the metal surface is contacted with an aqueous oxidation solution comprising a permanganate oxidant for converting chromium into a Cr(VI) compound and dissolving the Cr(VI) compound in the oxidation solution; and a first cleaning step wherein the oxidation solution containing the Cr(VI) compound is directly passed over an anion exchange material and the Cr(VI) compound is immobilized on the anion exchange material. The method provides for substantial savings of radioactive waste and produces chelate-free waste.

Abstract: A method of decontaminating a metal surface located on a component within a nuclear plant, in particular within the cooling system of a nuclear power plant, which is covered with a metal oxide layer containing radioactive substances, the method including a decontamination step in which a metal oxide layer pretreated in an oxidation step is contacted with an aqueous solution of an organic acid to dissolve the metal oxide layer, forming a decontamination solution containing the organic acid, metal ions and the radioactive substances, and passing the decontamination solution over an ion exchanger to immobilize metal ions and radioactive substances. An oxidant selected from oxygen, air, hydrogen peroxide and ozone is dosed into the decontamination solution to control the dissolution rate of the metal oxide layer. The method is particularly suitable for large-scale system decontamination and ensures high process stability.

Abstract: The invention relates to a method of decontaminating a metal surface, wherein the metal surface is located on a component within a nuclear plant, in particular within the cooling system of a nuclear power plant, and is covered with a metal oxide layer containing radioactive substances, and wherein the method comprises a decontamination step in which a metal oxide layer pretreated in an oxidation step is contacted with an aqueous solution of an organic acid to dissolve the metal oxide layer, forming a decontamination solution containing the organic acid as well as metal ions and the radioactive substances, and wherein the decontamination solution is passed over an ion exchanger to immobilize the metal ions and the radioactive substances. An oxidant selected from the group consisting of oxygen, air, hydrogen peroxide and ozone is dosed into the decontamination solution to control the dissolution rate of the metal oxide layer.

Abstract: A method for decontaminating a metal surface exposed to radioactive liquid or gas during operation of a nuclear facility comprises an oxidation step wherein a metal oxide layer on the metal surface is contacted with an aqueous oxidation solution comprising a permanganate oxidant for converting chromium into a Cr(VI) compound and dissolving the Cr(VI) compound in the oxidation solution; and a first cleaning step wherein the oxidation solution containing the Cr(VI) compound is directly passed over an anion exchange material and the Cr(VI) compound is immobilized on the anion exchange material. The method provides for substantial savings of radioactive waste and produces chelate-free waste.

Abstract: A method for treating waste water from the decontamination of a metal surface in a primary coolant circuit of a nuclear reactor comprises discharging a predetermined amount of an oxidation solution from the primary coolant circuit into a reduction zone connected to the primary coolant circuit and reacting the oxidation solution with a reducing agent to form a reaction solution that is freed of oxidizing agent, and passing the reaction solution over an ion-exchange resin in order to form a desalinated solution, and returning the desalinated solution to the primary coolant and/or disposing of the desalinated solution. A waste water treatment apparatus for carrying out the method is also provided.

Abstract: A method for treating waste water from the decontamination of a metal surface in a primary coolant circuit of a nuclear reactor comprises discharging a predetermined amount of an oxidation solution from the primary coolant circuit into a reduction zone connected to the primary coolant circuit and reacting the oxidation solution with a reducing agent to form a reaction solution that is freed of oxidizing agent, and passing the reaction solution over an ion-exchange resin in order to form a desalinated solution, and returning the desalinated solution to the primary coolant and/or disposing of the desalinated solution. A waste water treatment apparatus for carrying out the method is also provided.

Abstract: The invention relates to a process for the chemical decontamination of a surface, having an oxide layer of a metallic component of the coolant system of a nuclear power station, which comprises at least one oxidation step in which the oxide layer is treated with an aqueous solution containing an oxidant and a subsequent decontamination step in which the oxide layer is treated with an aqueous solution of a decont. acid which has the property of forming a sparingly soluble precipitate with metal ions, in particular with nickel ions. Prior to carrying out the decontamination step, metal ions which have gone into solution during the oxidation step are removed from the aqueous solution by means of a cation exchanger.

Abstract: A method is provided for conditioning a waste solution obtained during the wet-chemical cleaning of conventional or nuclear plants and containing organic substances and metals in ionic form. At least a portion of the organic substance is degraded by electrochemical treatment or UV radiation of the waste solution, at least one metal precipitates by the addition of phosphoric acid and a resultant phosphate precipitate is removed from the waste solution.

Abstract: A method for conditioning a cleaning solution resulting from the wet chemical cleaning of a nuclear steam generator, includes electrolytically treating the cleaning solution and depositing radioactive metal nuclides contained in the cleaning solution on a cathode.