Hitachi-ge Nuclear Energy, Ltd.

Naoshi Usui

Kazushige Ishida

Motohiro Aizawa

Motomasa Fuse

Makoto Nagase

Yoichi Wada

Hideyuki Hosokawa

Masahiko Tachibana

Masao Endo

Tsuyoshi Ito

Hiroko Sukeda

Mayu Sasaki

Yuko Hino

Hidehiro Iizuka

Nobuyuki Ota

Youichi Wada

More accurate prediction of reactor water quality of a nuclear reactor is implemented. A device for prediction of reactor water quality of a nuclear reactor in a nuclear power plant is disclosed. The device stores a reactor water quality prediction model which is learned using learning data, and with which future reactor water quality is predicted. An explanatory variable of the reactor water quality prediction model includes a value in a predetermined period unit that is generated from data acquired in an operating nuclear power plant. The device generates the value in a predetermined period unit from data acquired in a target operating nuclear power plant, and acquires a predicted value of the reactor water quality in the target nuclear power plant based on the reactor water quality prediction model and the value in a predetermined period unit.

Device for prediction of reactor water quality of nuclear reactor

A reactor water radioactivity concentration of a nuclear power plant can be predicted with high accuracy. First, a plant state quantity prediction value is calculated by using a physical model that describes plant state quantities of the power plant including a flow rate of feedwater and a metal corrosion product concentration in feedwater of the reactor water is calculated. Next, data for supervised learning is created, and the data for supervised learning includes the previously calculated plant state quantity prediction value and a plant state quantity such as the flow rate of feedwater, the metal corrosion product concentration in feedwater, a metal corrosion product concentration in reactor water, and a radioactive metal corrosion concentration of the reactor water in the reactor as input data and includes a radioactive metal corrosion concentration in the reactor water which is an actual measured value as output data, and a predictive model is trained.

Predictive model construction and prediction method for radioactive metal corrosion concentration in nuclear reactor water

An adsorbing substance made of a material having an acid center in its molecular frame is installed in a passage for steam generated in a reactor pressure vessel. The adsorbing substance adsorbs and holds N-16 compound for decay. Therefore, the amount of N-16 entering into a turbine system is decreased and dose in the turbine system can be reduced.

Boiling water nuclear plant and method of reducing dose in turbine system

In the boiling water nuclear plant of the present invention, a steam dryer is disposed in a reactor pressure vessel. Materials that have capability of capturing nitrogen compounds containing N-16 are supported on porous member. The porous members are placed in a region where steam goes through in the steam dryer. For example, both or either of perforated plates installed in the steam dryer is constituted of the porous member on which N-16 capture material is supported. When steam containing N-16 goes through the perforated plates, the N-16 is captured by the porous member, whereby the N-16 transfer amount into the turbine system is reduced.

Boiling water nuclear plant and steam dryer

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 capdisposed to cover an outer surface of the electrode fixing body. The ECP sensor with such a construction can lengthen the lifetime.

Electrochemical corrosion potential sensor

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.

Suppression method of radionuclide deposition on reactor component of nuclear power plant

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.

Method of stress corrosion cracking mitigation for nuclear power plant structural materials

Suppression method of radionuclide deposition on reactor component of nuclear power plant and ferrite film formation apparatus

Method of stress corrosion cracking mitigating for nuclear power plant structural materials

It is an object of the present invention to efficiently suppress radionuclide deposition on a reactor component of nuclear power plant. Radionuclide deposition on the surface of a metallic reactor component of nuclear power plant is suppressed by forming a ferrite film on the component, wherein the film is formed, after decontamination for removing radionuclides contaminants from the component surface is completed and before the plant is started up, by contacting a treatment solution which mixes a first agent containing the iron (II) ions, a second agent for oxidizing the iron (II) ions into the iron (III) ions and a third agent for adjusting pH level of a solution to 5.5 to 9.0 in this order with the reactor component surface.

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Tsuchiura, Japan

Naoshi Usui