Hitachi, Ltd.

Other

Hitachi Engineering Co., Ltd.

Yamato Asakura

Katsumi Ohsumi

Shunsuke Uchida

Makoto Nagase

Naohito Uetake

Masanori Sakai

Toshio Sawa

Masaharu Sakagami

Masayoshi Kondoh

Kazuhiko Akamine

Fumio Kawamura

Motoaki Utamura

Hideyuki Hosokawa

Noriyuki Ohnaka

Yoshiyuki Takamori

Masato Nakamura

Hidefumi Ibe

Kouichi Yamane

Teiji Suzuki

Hidetoshi Karasawa

Makoto Hayashi

Makoto Kikuchi

Kenichi Ito

Tetsuya Matsui

Atsushi Watanabe

Renzo Takeda

Yoichi Wada

Masami Matsuda

Motohiro Aizawa

Hiroshi Kamimura

Tsutomu Baba

Yasuko Aoki

Takashi Saito

Kazumichi Suzuki

Kenji Yokose

Hiroyuki Tsuchiya

Kiyotomo Nakata

Kouji Hayashi

Masanori Takahashi

Minoru Miki

Akira Maru

Yoshitaka Nishino

Eishi Ibe

Nagao Suzuki

Maroto Nagase

Yoshinori Chiba

Teruo Hara

Akira Ichimura

Masao Endou

Masao Endo

In a nuclear power plant, by injecting an amount of hydrogen small enough not to increase a radiation dose rate of the main steam system, ECP of metallic component materials composing a nuclear reactor can be decreased to suppress the potential of occurrence of IGSCC, and the control can be easily performed, and the operating cost can be suppressed to increase. Occurrence of intergranular stress corrosion cracking in metallic component materials in contact with reactor cooling water is suppressed by injecting zirconium hydroxide and hydrogen into the reactor cooling water to decrease the electrochemical corrosion potential of the metallic component materials.

Method of operating nuclear power plant, nuclear power plant, and method of controlling water chemistry of nuclear power plant

Surfaces of the structural components of a nuclear power plant exposed to reactor water are wetted with an electroless plating solution containing an electrical insulating substance. The electrical insulating substance has a high resistivity about 10 (100000) times those of the structural components of the nuclear power plant or above. A metal film containing the electrical insulating substance is formed on the surfaces of the structural components exposed to the reactor water by wetting the surfaces of the structural components with the electroless plating solution. Thus, the electrochemical corrosion potential of the structural components is reduced regardless of whether hydrogen is injected into the reactor water.

Treatment method of nuclear reactor internal component

A reactor water clean-up system is provided with a first filter demineralizer having a filter resin containing an alkali substance and a second filter demineralizer with a filter resin not containing an alkali substance. The reactor water is supplied to the first filter demineralizer during the term from the starting operation of the preoperating test of the nuclear reactor and of each fuel cycle to 2000 EFPH. The alkali substance contained in the filter resin is guided into the nuclear reactor to change the pH of the reactor water in the nuclear reactor to the weak alkali side. The Cr quantity which is taken in the oxide film of the fuel cladding tube surface is reduced. After 2000 EFPH from the starting operation, the supply of the reactor water to the first filter demineralizer is stopped, and then, the reactor water is supplied to the second filter demineralizer.

Boiling water reactor and its operating method

In a nuclear fuel rod having a zirconium liner and a method of manufacturing the same, the outer surface of a zircaloy cladding tube in which fuel pellets are filled has an oxide film having fine irregularities of which the pitch is 1 .mu.m or less. The fine irregularities are formed by oxidizing the surface in high temperature steam or polishing the surface of the cladding tube. The surface of the fuel rod can effectively trap radioactive substances in the reactor water.

Nuclear fuel rod and method of manufacturing the same

In reactor water control for a BWR power plant during an operation cycle after loading new fuel rods in the BWR power plant, an operation is performed which accelerates deposition of crud on the fuel rods until the deposition amount of the crud on the fuel rods reaches a predetermined target value within the operation cycle concerned. After the deposition amount of the crud has reached the predetermined target value, the crud deposition accelerating operation is terminated, whereby even when loading new fuel rods such as Zr liner type fuel rods having a surface on which metal ion deposition has been difficult, radioactivity in the reactor water is efficiently reduced.

Reactor water control method in BWR power plant, BWR power plant having

A water chemistry factor which is specific to a specific portion of a primary cooling system and universal is decided to be a standard target. The concentration of an agent for mitigating corrosion damage of structural material of the primary cooling system is controlled so that the target will be in a desirable range. All sensor groups provided in the primary cooling system are separated into sensor groups in different lines, of which a specific sensor group are connected to an arithmetic unit and a data base and are for always monitoring a plant process. For example, concentration distribution agreed with measured value oxidation component in the reactor water at the measurement points is selected from the data base, and it is used to estimate the standard target.

Nuclear power plant having a water chemistry control system for a

A water quality control method for a nuclear power plant comprising the steps of maintaining the iron concentration in the feed water below 0.05 ppb by increasing iron removing rate at a condensed water purifying loop, shifting the pH of the reactor water below a pH of 6.8 determined at a room temperature by injecting carbon dioxide gas in the primary cooling system and further optionally reducing the dissolved oxygen concentration in the reactor water below 20 ppb by injecting hydrogen gas into the primary cooling system, whereby .sup.60 Co ion concentration in the primary cooling system is maintained low for a long interval.

Water quality control method and device for nuclear power plant, and

An object of the present invention is to provide a method and a nuclear plant capable of preventing deposition and activation of crud to a nuclear fuel rod and decreasing the radioactivity level in reactor water. Metal ions solely having a low deposition rate coefficient are made to coexist to prevent or decrease deposition of radioactive corrosion products to the nuclear fuel rod. A method and a nuclear plant capable of preventing deposition and activation of crud to the nuclear fuel rod and decreasing the radioactivity level in reactor water can be provided.

Method of operating BWR plant, BWR plant and metal element injecting

This invention concerns a plant diagnosis apparatus which comprises a first detecting unit for detecting a state of devices constituting a circulating system in which a fluid circulates and a second detecting unit for detecting a quality of the above-mentioned circulating fluid or a quality of the atmosphere surrounding the above-mentioned circulating system, and a unit for diagnosing the circulating system by output of the first and second detecting units, and therefore can diagnose anomaly of facilities such as a nuclear power plant with high reliability and rapidity.

Plant diagnosis apparatus and method

Measurement values of conductivity of pH of water in the primary cooling water system of a boiling water atomic power plant are input through on-line and the measurement values of conductivity and pH at times of measurement when water quality changes are compared with values at the time of normal operation. Tendencies to increase or decrease the conductivity and pH are combined to prepare one diagnosis data, and causes of anomaly in progress in component apparatus members are discriminated and diagnosed by the diagnosis data. By using a correlation between logarithm of conductivity and pH in preparing the diagnosis data from combinations of conductivity and pH, causes of anomaly can be diagnosed more accurated.

Method and apparatus for water chemistry diagnosis of atomic power plant

A direct cycle type atomic power plant provided with a means for suppressing transfer of radioactive nitrogen compounds generated by nuclear reaction in the core from the reactor water to steam, where an increase in the dose rate in the main steam system and the turbine system due to carry-over of radioactive nitrogen atom, .sup.16 N, generated in the core can be suppressed, and the radioactivity therein can be reduced.

Direct cycle-type atomic power plant with means for suppressing transfer

Disclosed is a method and apparatus for inhibiting radioactive substances eluting into cooling water of a nuclear plant. The method uses an index consisting of an amount of iron adhered onto the fuel cladding surface, that is calculated from the iron concentration of the cooling water and the operation time. A formation of a layer of the iron oxide on the fuel cladding surface is confirmed based upon the covering ratio of 100%. When the covering ratio is smaller than 100%, the iron concentration in the cooling water is controlled to remain constant at a maximum concentration. The Fe/Ni molar concentration ratio in the cooling water is adjusted to be set from about 2 to 10 after the layer of iron oxide reaches a covering ratio of 100%. .sup.58 Co ion and .sup.60 Co ion concentrations in the cooling water can be decreased without greatly increasing the concentration of precipitating radioactive crud, and the surface dosage in the primary system can be decreased at the time of regular checking.

Method of inhibiting radioactive substances from eluting into cooling

Electric conductivities of an aqueous solution under measurement are measured at two or more different temperatures in a range To to Tn, and a relationship between the electrical conductivity and the temperatures is obtained. A solute substance in the aqueous solution is determined by applying this relationship against a known temperature and electrical conductivity relationship of an individual substance. A concentration of the determined substance is estimated by applying the electrical conductivity at the lowest temperature To to a known relationship between an electrical conductivity and a concentration at the same temperature To with respect to an individual substance.

Water quality control method, and method and apparatus for measuring

A method and apparatus for analyzing the electrode impedance, in which an a.c. voltage with its frequency varied at intervals is applied between a pair of measuring electrodes dipped in the sample liquid, the complex a.c. impedance between the electrodes is measured at each frequency, the maximum value among absolute values of imaginary part of the measured impedance values is detected as the electrode polarization resistance, and the solution resistance of the liquid is calculated by subtracting the detected maximum value from the real part of the impedance corresponding to the maximum imaginary part.

Method and apparatus for analyzing the electrode inpedance

Ability of ion adsorption apparatus such as a desalting unit, etc. as used in an atomic power plant is continuously monitored, and any deterioration in the ability is detected in advance by a method and an apparatus for monitoring a break in an ion adsorption apparatus by detecting a break point of the ion adsorption apparatus using ion exchange resin, thereby determining a timing for regenerating or exchanging the resin, which comprises making an ion species having a weaker selective adsortability to the ion exchange resin as a sampling ion species than that of a target ion species to be adsorbed and present in water to be treated, and detecting leakage of the sampling ion species at the downstream side of the adsorption apparatus, thereby determining the break point of the ion exchange resin.

Method and apparatus for monitoring break of ion adsorption apparatus

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Katsuta, Japan

Yamato Asakura