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: 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: 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 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 of decontaminating metal surfaces in a cooling system of a nuclear reactor comprises: an oxidation step, comprising at least one acidic oxidation step and at least one alkaline oxidation step wherein metal oxides and radioisotopes on the metal surfaces are contacted with aqueous permanganate oxidant solutions; followed by a decontamination step wherein an aqueous solution comprising oxalic acid, formic acid, citric acid, tartaric acid, picolinic acid, gluconic acid glyoxylic acid or mixtures thereof is used to dissolve at least part of the metal oxides and radioisotopes; and a cleaning step wherein radioisotopes are immobilized on an ion exchange resin; wherein at least one treatment cycle includes a high temperature oxidation step, wherein the permanganate oxidant solution is kept at a temperature of at least 100° C.

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 process for the recovery of a radioisotope from a waste resin of a nuclear power plant comprises the steps of: a) treating a waste resin loaded with at least one radioisotope with an organic acid or alkaline compound to release the at least one radioisotope and to obtain a process solution containing the at least one radioisotope; b) separating the at least one radioisotope from the process solution through a reaction specific to the radioisotope so as to obtain a treated process solution depleted of the at least one radioisotope, wherein said depleted process solution comprises the organic acid or alkaline compound and optionally a non-reacted radioisotope; c) reacting the organic acid or alkaline compound in the depleted process solution from step b) by thermal and/or photochemical oxidation to form gaseous reaction products; and d) reloading the waste resin with the reacted process solution from step c) to bind the non-reacted radioisotope on the waste resin.

Abstract: A process for the recovery of a radioisotope from a waste resin of a nuclear power plant comprises the steps of: a) treating a waste resin loaded with at least one radioisotope with an organic acid or alkaline compound to release the at least one radioisotope and to obtain a process solution containing the at least one radioisotope; b) separating the at least one radioisotope from the process solution through a reaction specific to the radioisotope so as to obtain a treated process solution depleted of the at least one radioisotope, wherein said depleted process solution comprises the organic acid or alkaline compound and optionally a non-reacted radioisotope; c) reacting the organic acid or alkaline compound in the depleted process solution from step b) by thermal and/or photochemical oxidation to form gaseous reaction products; and d) reloading the waste resin with the reacted process solution from step c) to bind the non-reacted radioisotope on the waste resin.

Abstract: The invention relates to a method for reducing the radioactive contamination of the surface of a component used in a nuclear reactor, which component is in contact with radioactively contaminated water, in which method a hydrophobic film is produced on the surface of a component by virtue of the surface being wetted with an aqueous solution which contains a film-forming amphiphilic substance.

Abstract: A method of decontaminating metal surfaces in a cooling system of a nuclear reactor comprises conducting a plurality of treatment cycles, with each of the treatment cycles comprising: an oxidation step wherein metal oxides including radioisotopes on the metal surfaces are contacted with an aqueous solution of a permanganate oxidant; a decontamination step after the oxidation step wherein the metal oxides are contacted with an aqueous solution of an organic acid selected from the group consisting of oxalic acid, formic acid, citric acid, tartaric acid, picolinic acid, gluconic acid, glyoxylic acid and mixtures thereof so as to dissolve at least part of the metal oxides and the radioisotopes; and a cleaning step wherein at least the radioisotopes are immobilized on an ion exchange resin; wherein the oxidation step comprises at least one acidic oxidation step and at least one alkaline oxidation step carried out one after another in either the same or different treatment cycles; and wherein the plurality of treat

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: The invention relates to a method for reducing the radioactive contamination of the surface of a component used in a nuclear reactor, which component is in contact with radioactively contaminated water, in which method a hydrophobic film is produced on the surface of a component by virtue of the surface being wetted with an aqueous solution which contains a film-forming amphiphilic substance.

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 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 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 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.