Patent application number | Description | Published |
20080247499 | Natural Circulation Boiling Water Reactor And Handling Method Thereof - A handling method for a natural circulation boiling water reactor having a chimney having cylindrical chimney shell disposed above a core in a reactor pressure vessel, a plurality of square tubes disposed in the chimney shell, and a grid support plate with grid holes supporting and in communication with a lower end portion of the square tubes so that adjacent square tubes are disposed at an interval which exceeds the width of one square tube between them. The method includes steps shifting predetermined ones of the square tubes to the interval between the square tubes, and performing maintenance and inspection of members around a core via the grid holes which appear at positions from which the predetermined square tubes are taken out due to the shift of the predetermined square tubes. | 10-09-2008 |
20080292042 | Method of stress corrosion cracking mitigation for nuclear power plant structural materials - The object of this invention is to provide a method for mitigating a stress corrosion cracking of reactor structural material which makes it possible to suppress the rise in the main steam line dose rate without secondary effects such as a rise in the concentration of radioactive cobalt-60, etc. in the reactor water. Hydrogen and a reductive nitrogen compound containing nitrogen having a negative oxidation number (for example, hydrazine) are injected into the core water of boiling water nuclear power plant. By injecting the reductive nitrogen compound containing nitrogen having a negative oxidation number into the core water, the stress corrosion cracking of structural material of reactor can be mitigated without side reactions such as a rise in the concentration of cobalt-60, etc. | 11-27-2008 |
20090003509 | Suppression Method of Radionuclide Deposition on Reactor Component of Nuclear Power Plant and Ferrite Film Formation Apparatus - A method of suppressing deposition of radionuclides on components of a nuclear power plant comprises forming a ferrite film by contacting a first chemical including iron (II) ions, a second chemical for oxidizing the iron (II) ions to iron (III) ions, and a third chemical for adjusting the pH of a processing solution containing a mixture of the first and second chemicals to be 5.5 to 9.0 with the metal member surface in a time period from a finishing stage in decontamination step of removing contaminants formed on the surface of metal member composing the nuclear power plant, and suppressing deposition of radionuclides on the metal member by the ferrite film. | 01-01-2009 |
20090141849 | Suppression Method of Radionuclide Deposition on Reactor Component of Nuclear Power Plant and Ferrite Film Formation Apparatus - A method of suppressing deposition of radionuclides on components of a nuclear power plant comprises forming a ferrite film by contacting a first chemical including iron (II) ions, a second chemical for oxidizing the iron (II) ions to iron (III) ions, and a third chemical for adjusting the pH of a processing solution containing a mixture of the first and second chemicals to be 5.5 to 9.0 with the metal member surface in a time period from a finishing stage in decontamination step of removing contaminants formed on the surface of metal member composing the nuclear power plant, and suppressing deposition of radionuclides on the metal member by the ferrite film. | 06-04-2009 |
20090185653 | Suppression Method of Radionuclide Deposition on Reactor Component of Nuclear Power Plant and Ferrite Film Formation Apparatus - A method of suppressing deposition of radionuclides on components of a nuclear power plant comprises forming a ferrite film by contacting a first chemical including iron (II) ions, a second chemical for oxidizing the iron (II) ions to iron (III) ions, and a third chemical for adjusting the pH of a processing solution containing a mixture of the first and second chemicals to be 5.5 to 9.0 with the metal member surface in a time period from a finishing stage in decontamination step of removing contaminants formed on the surface of metal member composing the nuclear power plant, and suppressing deposition of radionuclides on the metal member by the ferrite film. | 07-23-2009 |
20090190712 | METHOD OF STRESS CORROSION CRACKING MITIGATION FOR NUCLEAR POWER PLANT STRUCTURAL MATERIALS - The object of this invention is to provide a method for mitigating a stress corrosion cracking of reactor structural material which makes it possible to suppress the rise in the main steam line dose rate without secondary effects such as a rise in the concentration of radioactive cobalt-60, etc. in the reactor water. Hydrogen and a reductive nitrogen compound containing nitrogen having a negative oxidation number (for example, hydrazine) are injected into the core water of boiling water nuclear power plant. By injecting the reductive nitrogen compound containing nitrogen having a negative oxidation number into the core water, the stress corrosion cracking of structural material of reactor can be mitigated without side reactions such as a rise in the concentration of cobalt-60, etc. | 07-30-2009 |
20100206729 | ELECTROCHEMICAL CORROSION POTENTIAL SENSOR - An electrochemical corrosion potential sensor (ECP sensor) has an electrode cap, an electrode fixing body, a tubular insulator, a tubular metallic housing, and a conductive wire. Both ends of the tubular insulator are connected to the electrode fixing body and the tubular metallic housing respectively. A conductive wire passes through the tubular insulator and the tubular metallic housing, and is connected to an inner surface of the electrode fixing body. The electrode cap | 08-19-2010 |
20110176649 | Suppression Method of Radionuclide Deposition on Reactor Component of Nuclear Power Plant - A method of suppressing deposition of radionuclides on components of a nuclear power plant comprises forming a ferrite film by contacting a first chemical including iron (II) ions, a second chemical for oxidizing the iron (II) ions to iron (III) ions, and a third chemical for adjusting the pH of a processing solution containing a mixture of the first and second chemicals to be 5.5 to 9.0 with the metal member surface in a time period from a finishing stage in decontamination step of removing contaminants formed on the surface of metal member composing the nuclear power plant, and suppressing deposition of radionuclides on the metal member by the ferrite film. | 07-21-2011 |
20120294404 | Nuclear Power Plant and Method of Operating It - A hydrogen treatment facility for treating hydrogen without using a power source is disposed outside a reactor containment vessel and in an upper portion of a reactor building. A hydrogen detector detecting hydrogen in the reactor building is connected to a control apparatus operated by an independent power source activated at the time of a station black-out. A circulation passage for air circulation generated in the reactor building is disposed in the reactor building and outside the reactor containment vessel. A hydrogen treatment duct connects to the circulation passage and a gangway and a room with equipment. During a severe accident and station black-out and when hydrogen concentration detected by the hydrogen detection apparatus exceeds a set concentration, the hydrogen treatment duct is put in use by the control apparatus. Air containing the hydrogen is introduced into the hydrogen treatment facilities through the hydrogen treatment duct and the circulation passage. | 11-22-2012 |