Abstract: A process removes radioactive contamination from wastewater obtained in the decontamination of a cooling circuit of nuclear reactors or of parts thereof or in the course of operation of a nuclear reactor. A MnO2 precipitate is exclusively produced in the wastewater with the aid of permanganate ions added thereto as an oxidizing agent and of one or more organic reducing agents present in and/or metered into the wastewater, and the MnO2 precipitate is separated from the wastewater.

Abstract: A process removes radioactive contamination from wastewater obtained in the decontamination of a cooling circuit of nuclear reactors or of parts thereof or in the course of operation of a nuclear reactor. A MnO2 precipitate is exclusively produced in the wastewater with the aid of permanganate ions added thereto as an oxidizing agent and of one or more organic reducing agents present in and/or metered into the wastewater, and the MnO2 precipitate is separated from the wastewater.

Abstract: A method for decontaminating nuclear plant surfaces, which have been contaminated with alpha emitters, is carried out subsequently to a decontamination process which is aimed at the removal of oxide layers. The surfaces are treated with an aqueous solution which contains a cationic or zwitterionic surfactant and oxalic acid. At least a part of the solution, after having acted on a surface, is conducted across an ion exchanger.

Abstract: A method for chemical decontamination of an oxide-coated surface of a metal structural part or of a system in a nuclear power plant with several cleaning cycles, involves oxidation steps, in which the oxide layer is treated with an aqueous solution containing an oxidation agent, and a subsequent decontamination step, in which the oxide layer is treated with an aqueous solution of an acid. At least one oxidation step is carried out in an acid solution and at least one oxidation step in an alkaline solution.

Abstract: A method for conditioning a contaminated ion exchange resin includes mixing the contaminated ion exchange resin with water and at least partly breaking up the contaminated ion exchange resin into water-soluble components or fragments through the use of an oxidizing agent added to the water. A resulting aqueous solution is consolidated with a binder, optionally after concentration by evaporation of water.

Abstract: A process is provided for chemically decontaminating the surface of a metallic component. In a first treatment step, an oxide layer formed on the component by corrosion of the material of the component is detached from the surface of the component with a first aqueous treatment solution containing an organic decontamination acid. In a subsequent second treatment step, the surface which is at least partially freed of the oxide layer is treated with an aqueous solution containing an active component for removing particles which adhere to the surface. The active component is formed of at least one anionic surfactant from the group including sulphonic acids, phosphonic acids, carboxylic acids and salts of those acids.

Abstract: A method chemically decontaminates a surface of a metal component of a primary circuit of a pressurized-water reactor, the surface contains an oxide layer. In a first stage, an oxidation step, a reduction step, and a first decontamination step are performed. The component is treated in the oxidation step with an aqueous solution containing an oxidizing agent, which converts trivalent chrome present in the oxide layer into hexavalent chrome. The component is treated in the reduction step with an aqueous solution containing a reducing agent for reducing excess oxidation agent from the oxidation step. The component is treated in the first decontamination step with an aqueous solution containing a decontamination acid that forms no antisoluble deposits with metal ions in the solution. The solution is fed through an ion exchanger for removing metal ions. In a second stage, the component is treated with an aqueous solution containing an oxalic acid.

Abstract: A process is provided for chemically decontaminating the surface of a metallic component. In a first treatment step, an oxide layer formed on the component by corrosion of the material of the component is detached from the surface of the component with a first aqueous treatment solution containing an organic decontamination acid. In a subsequent second treatment step, the surface which is at least partially freed of the oxide layer is treated with an aqueous solution containing an active component for removing particles which adhere to the surface. The active component is formed of at least one anionic surfactant from the group including sulphonic acids, phosphonic acids, carboxylic acids and salts of those acids.

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.

Abstract: A method for conditioning a contaminated ion exchange resin includes mixing the contaminated ion exchange resin with water and at least partly breaking up the contaminated ion exchange resin into water-soluble components or fragments through the use of an oxidizing agent added to the water. A resulting aqueous solution is consolidated with a binder, optionally after concentration by evaporation of water.

Abstract: A method for decontaminating nuclear plant surfaces, which have been contaminated with alpha emitters, is carried out subsequently to a decontamination process which is aimed at the removal of oxide layers. The surfaces are treated with an aqueous solution which contains a cationic or zwitterionic surfactant and oxalic acid. At least a part of the solution, after having acted on a surface, is conducted across an ion exchanger.

Abstract: The radioactivity of a metal part is reduced in the process. In the method, firstly a layer of oxide is removed from the metal part using a decontamination solution. Then, an agent which has an oxidizing action and is still present is removed from the decontamination solution. As a result, a layer of the metal is removed. Since radionuclides are to be found only in the layer of the metal part which is close to the surface, the remaining metal can be scrapped in the conventional way.

Abstract: Nitrate ions are removed from a solution. Such a solution is, in particular, a spent decontamination solution or another spent solution intended for reducing the radioactivity of a metal part. It is provided that the solution, if it comprises a short-chain organic compound, is irradiated with UV light. Otherwise, such a compound is introduced into the solution prior to irradiation. Using the method, the nitrate ions are chemically reduced, forming, for example, N2, N2O, CO2 and H2O.

Abstract: A cation exchanger is loaded only with radioactive cations by repeatedly converting the non-bivalent, inactive cations into anionic complexes and flushing the complexes out of the cation exchanger. The cation exchanger, which may be integrated in a primary system of a nuclear power plant, is connected to a feed line for a complexing agent and to a discharge line through which the anionic complexes are flushed from the exchanger.

Abstract: A method for chemical decontamination of the surface of a metal component of a nuclear reactor plant includes treating the surface of the metal component in a single-step method with an aqueous solution that is free of carbonic acid oxalic acid and contains a different carbonic acid.