Abstract: An object of the present invention is to provide a chemical decontamination liquid decomposing system having a catalyst tower which has a mesh filter capable of certainly preventing catalyst from flowing out and a mechanism of pushing-down the catalyst capable of preventing convection of the catalyst caused by decomposition gas. The catalyst tower in accordance with the present invention used for decomposing a chemical decontamination liquid comprises an inlet pipe, a catalyst for decomposing the chemical decontamination liquid, an outlet mesh filter for preventing the catalyst from flowing out, an outlet pipe, a catalyst charging port for charging the catalyst, a catalyst pushing-down mechanism for preventing occurrence of convection of the catalyst caused by a decomposed gas and so on. The outlet mesh filter is arranged so as to closely attached to the inner surface of the catalyst tower and to the inner surface of the catalyst charging port.

Abstract: In a chemical decontamination method of chemically decontaminating radioactive nuclides from a metallic material, oxalic acid and hydrazine are injected as a reductive decontaminating agent into water that is in contact with the metallic material. Injection of the hydrazine is stopped after a cation resin arranged in a circulation line connected to the metallic material breaks, and at least the oxalic acid and the hydrazine in the reductive decontaminating agent are decomposed using a decomposing catalyst.

Abstract: In a chemical decontamination apparatus, a catalyst decomposition column in an upstream side of an ion exchange resin column and a hydrogen peroxide injection apparatus in a further upstream side, reduce the amount of waste products caused by a chemical decontaminating agent where a mixed decontaminating agent for a composition trapped in a cation resin column and for a composition trapped in an anion exchange resin are used for the chemical decontaminating agent, selectively decompose the composition trapped in the cation resin column in an inlet side of a cleaning apparatus when radioactive nuclides in the decontaminating agent are cleansed using the cation resin column during decontamination, and decompose both compositions after completion of the decontamination. The chemical decontamination thus selectively decomposes the chemical decontaminating agent, which is a component of the load to the cation resin column.

Abstract: A radioactive substance decontamination method and apparatus which decontaminates a metal member contaminated by radioactive substance in a short period of time. This apparatus has (1) multiple reducing decontamination tanks having different radiation control values; (2) a carrier for immersing the metal member into the multiple reducing decontamination tanks and a washing tank; (3) a tube for transferring into the second reducing decontamination tank the reducing decontamination agent in the first reducing decontamination tank; (4) a reducing agent decomposer for decomposing a component contained in the reducing decontamination agent of the reducing decontamination tank where the radiation control value is the highest out of the reducing decontamination tanks connected by the tube; and (5) a washing tank for washing the reducing decontamination agent deposited on the decontaminated metal member.

Abstract: A radioactive substance decontamination method and apparatus which decontaminates a metal member contaminated by radioactive substance in a short period of time. This apparatus has (1) multiple reducing decontamination tanks having different radiation control values; (2) a carrier for immersing the metal member into the multiple reducing decontamination tanks and a washing tank; (3) a tube for transferring into the second reducing decontamination tank the reducing decontamination agent in the first reducing decontamination tank; (4) a reducing agent decomposer for decomposing a component contained in the reducing decontamination agent of the reducing decontamination tank where the radiation control value is the highest out of the reducing decontamination tanks connected by the tube; and (5) a washing tank for washing the reducing decontamination agent deposited on the decontaminated metal member.

Abstract: An object of the present invention is to provide a chemical decontamination liquid decomposing system having a catalyst tower which has a mesh filter capable of certainly preventing catalyst from flowing out and a mechanism of pushing-down the catalyst capable of preventing convection of the catalyst caused by decomposition gas.

Abstract: It is an object of the present invention to provide a method of chemical decontamination which can remove iron oxalate deposited on a metallic material surface without extending a whole step of decontamination works.

Abstract: An object of the present invention is to provide a chemical decontamination liquid decomposing system having a catalyst tower which has a mesh filter capable of certainly preventing catalyst from flowing out and a mechanism of pushing-down the catalyst capable of preventing convection of the catalyst caused by decomposition gas. The catalyst tower in accordance with the present invention used for decomposing a chemical decontamination liquid comprises an inlet pipe, a catalyst for decomposing the chemical decontamination liquid, an outlet mesh filter for preventing the catalyst from flowing out, an outlet pipe, a catalyst charging port for charging the catalyst, a catalyst pushing-down mechanism for preventing occurrence of convection of the catalyst caused by a decomposed gas and so on. The outlet mesh filter is arranged so as to closely attached to the inner surface of the catalyst tower and to the inner surface of the catalyst charging port.

Abstract: To suppress a decrease of thickness due to corrosion of structural members and to achieve a removal of radionuclides with good efficiency in a nuclear power plant, oxidation decontamination is first conducted. An aqueous potassium permanganate solution is supplied from a circulation line to a reactor pressure vessel, which is a stainless steel structural member, and a reactor water cleanup system piping and a drain piping, which are carbon steel structural members. These structural members are oxidation-decontaminated by the action of potassium permanganate. Then the above-mentioned structural members are reduction-decontaminated by using an aqueous oxalic acid solution. The aqueous oxalic acid solution contains hydrazine.

Abstract: The present invention provides a simple and inexpensive decontaminating method without producing any secondary waste due to decontamination. A method comprising steps of evaporating liquid ozone, feeding the gaseous ozone into a re-circulation line 2 in the upstream side of the re-circulation pump 3 to make ozone-rich water, circulating the ozone-rich water in the reactor-water re-circulation system, and remove radioactive materials from metallic surfaces.

Abstract: The present invention provides a simple and inexpensive decontaminating method without producing any secondary waste due to decontamination. A method comprising steps of evaporating liquid ozone, feeding the gaseous ozone into a re-circulation line 2 in the upstream side of the re-circulation pump 3 to make ozone-rich water, circulating the ozone-rich water in the reactor-water re-circulation system, and remove radioactive materials from metallic surfaces.

Abstract: A chemical decontamination apparatus an oxidizing solution reservoir for storing oxidizing agent decontamination agent of a decontamination tank subsequent to oxidizing decontamination, a reducing solution reservoir for storing reducing agent decontamination agent of the aforementioned decontamination tank subsequent to reducing agent decontamination, and a transfer pump for mutual transfer of decontamination agent between the aforementioned decontamination tank and reservoir; and is designed to permit repeated use of decontamination agent.

Abstract: A chemical decontamination apparatus an oxidizing solution reservoir for storing oxidizing agent decontamination agent of a decontamination tank subsequent to oxidizing decontamination, a reducing solution reservoir for storing reducing agent decontamination agent of the aforementioned decontamination tank subsequent to reducing agent decontamination, and a transfer pump for mutual transfer of decontamination agent between the aforementioned decontamination tank and reservoir; and is designed to permit repeated use of decontamination agent.

Abstract: A radioactive substance decontamination method and apparatus which decontaminate the metal member contaminated by radioactive substance in a shorter period of time.

Abstract: [Processes of reductive decontamination using an agent containing at least two kinds of components, and then decomposing the agent using an apparatus for decomposing at least two kinds of chemical substances in the agent, are employed in chemical decontamination.

Abstract: A radioactive substance decontamination method and apparatus which decontaminate the metal member contaminated by radioactive substance in a shorter period of time.

Abstract: In a chemical decontamination method and a chemical decontaminating system for chemically decontaminating radioactive nuclides from a metallic material surface contaminated by the radioactive nuclides, the method comprise the processes of reductively decontaminating using a reductive decontaminating agent containing at least two kinds of components; and then decomposing the reductive decontaminating agent using a decomposing apparatus for decomposing at least two kinds of chemical substances in the reductive decontaminating agent.

Abstract: Processes of reductive decontamination using an agent containing at least two kinds of components, and then decomposing the agent using an apparatus for decomposing at least two kinds of chemical substances in the agent, are employed in chemical decontamination. A catalyst decomposition column in an upstream side of an ion exchange resin column and a hydrogen peroxide injection apparatus in a further upstream side, reduce the amount of waste products caused by a chemical decontaminating agent where a mixed decontaminating agent for a composition trapped in a cation resin column and for a composition trapped in an anion exchange resin are used for the chemical decontaminating agent, selectively decompose the composition trapped in the cation resin column in an inlet side of a cleaning apparatus when radioactive nuclides in the decontaminating agent are cleansed using the cation resin column during decontamination, and decompose both compositions after completion of the decontamination.

Abstract: An object of the present invention is to provide a chemical decontamination liquid decomposing system having a catalyst tower which has a mesh filter capable of certainly preventing catalyst from flowing out and a mechanism of pushing-down the catalyst capable of preventing convection of the catalyst caused by decomposition gas.

Abstract: A method for strengthening a pressure resistant property of a hollowed structure made of a metallic material and a pressure resistant hollowed structure made by such method. The method includes providing a temperature differential in a thickness direction between an outer side and an inner side of the metallic material with an arranged sufficient to generate a stress not exceeding a yielding stress of the metallic material. The outer side and inner side are pressurized so as to superimposed a stress generated by the pressurizing and the stress caused by the temperature differential reaching the yielding stress of the metallic material. The pressure is released subsequent to the superimposed stress reaching a level of the yielding stress of the metallic material.