Hitachi, Ltd.

Hitachi Engineering Co., Ltd.

Shunsuke Uchida

Yamato Asakura

Makoto Nagase

Katsumi Ohsumi

Motoaki Utamura

Toshio Sawa

Tsutomu Baba

Fuminobu Takahashi

Izumi Yamada

Masaharu Sakagami

Haruo Fujimori

Takaharu Fukuzaki

Makoto Kikuchi

Kiyomi Funabashi

Koichi Chino

Masami Matsuda

Naohito Uetake

Hidefumi Ibe

Masao Kitamura

Eishi Ibe

Hidetoshi Karasawa

Eiichi Nishimura

Fumio Kawamura

Tetsuya Matsui

Takehiko Kitamori

Atsushi Watanabe

Masahiro Koike

Renzo Takeda

Hideo Yusa

Takashi Nishi

Hiroshi Kamimura

Tatsuo Hayashi

Tomohiro Sato

Kenji Yokose

Kazumichi Suzuki

Minoru Miki

Yoshitaka Nishino

Masahiro Kondo

Satoru Kawasaki

Osamu Kuriyama

Masayoshi Kondoh

Tetsuro Adachi

Itaru Komori

Koichi Saito

Yamoto Asakura

Maroto Nagase

Yoshinori Chiba

Ryoei Katsura

Norio Nakayama

Masao Endou

Masao Endo

Plant operating conditions 1, apparatus operating conditions 2 and environment conditions 3 are accumulated, combined and put together as a set of plant status variables 8 through a monitor 6, while water chemistry information 4 is accumulated as another set of plant status variables 9. The set of status variables 8 is updated and the past data are accumulated in the set of status variables 9. Periodical inspection data 5 are also accumulated in the set of status variables 9 along with the water chemistry information 4. The set 9 is compressed and stored as a plant chart 11 such as a personal clinical chart. A status variable prediction 12 is performed in consideration of the personality of a plant. Both data of the sets 8 and 10 are compared with each other by comparison means 13. If both the data nearly coincide with each other, the plant is diagnosed to the normal and, if not, it is diagnosed to be abnormal. When the plant is diagnosed to abnormal, an abnormal apparatus and an abnormal factor are identified.

Plant monitoring and diagnosing method and system, as well as plant

A diagnosis system having sensors for supervising a plant, signal processors for processing signals of the sensors, and a state quantity arithmetic operation unit. The state quantity arithmetic operation unit calculates a quantity of state expressing the environment of the plant on the basis of supervisory information inputted through the signal processors. A state quantity prediction unit predictively calculates a quantity of state after a predetermined time on the basis of the quantity of state, supervisory information and a time change of the quantity of state inputted through the state quantity arithmetic operation unit. A future event prediction unit predicts a future event on the basis of predicted information of the quantity of state inputted through the state quantity prediction unit. An image information processor converts the quantity of state given by the state quantity arithmetic operation unit into image information and indicates the image information on a display unit. An image information processor converts the predicted quantity of state after the predetermined time, given by the state quantity prediction unit, into image information and indicates the image information on a display unit. An image information processor converts the future event predicted by the future event prediction unit into image information and indicates the image information on a display unit.

Diagnosis system

Plant operating conditions 1, apparatus operating conditions 2 and environment conditions 3 are accumulated, combined and put together as a set of plant status variables 8 -through a monitor 6, while water chemistry information 4 is accumulated as another set of plant status variables 9. The set of status variables 8 is updated and the past data are accumulated in the set of status variables 9. Periodical inspection data 5 are also accumulated in the set of status variables 9 along with the water chemistry information 4. The set 9 is compressed and stored as a plant chart 11 such as a personal clinical chart. A status variable prediction 12 is performed in consideration of the personality of a plant. Both data of the sets 8 and 10 are compared with each other by comparison means 13. If both the data nearly coincide with each other, the plant is diagnosed to be normal and, if not, it is diagnosed to be abnormal. When the plant is diagnosed to be abnormal, an abnormal apparatus and an abnormal factor are identified.

The present invention relates to a method of solidifying radioactive waste with cement, comprising forming a mixture comprising water, a hydrophilic material and cement substantially non-shrinkable or expansible with respect to volume change upon hardening, mixing said mixture with the radioactive waste, followed by hardening to form a solid body. The present invention enables the formation of a compact solid body having voids, such as capillary voids, of reduced volume, which makes it possible to reduce the leaching rate of hazardous materials. Further, since no shrinkage accompanies hardening, no tensile stress occurs in the cement surrounding minute waste particles within the hardened material, thereby enabling a decrease in the strength of the solid body to be minimized. This in turn enables an increase in the amount of packing of waste. Prior addition of a hydrophilic material enables the cement fluidity before hardening to be maintained even after complete absorption of water by a water absorptive waste. This is extremely advantageous in carrying out hardening.

Method for solidifying radioactive waste

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

Waste water concentrator and waste water disposal plant

A water-cooled direct cycle nuclear plant including a nuclear reactor, a turbine, a condenser, a purifying means and a feed water heater successively arranged as main constitution, further comprises means for measuring iron concentration in cooling water, and means for injection iron into cooling water for controlling iron amount in cooling water at an optimum level. The iron amount to be injected into cooling water is calculated based on the measured iron concentration so as to make the iron accumulation rate on fuel rod to be not less than 0.5 mg/m.sup.2 /hr.

Water-cooled direct cycle nuclear power plant

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

A process and an apparatus for cleaning nuclear reactor cooling water with cation exchange resin whose ion-exchanging groups have a bonding energy of not more than 300 KJ/mole are disclosed, whereby the radiation exposure of operators in an atomic power plant can be considerably reduced, and the waste ion exchange resin can be readily disposed.

Process and apparatus for cleaning nuclear reactor cooling water

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

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Hitachi, Japan

Shunsuke Uchida