JPH06201885A - Operating condition monitoring system of plant - Google Patents

Abstract

PURPOSE:To precisely extract water quality information of high temperature water indispensable to operation condition monitoring of a nuclear power plant, a thermal power plant and the like by using a specific electrochemical reference electrode (ECP sensor) as a water quality sensor. CONSTITUTION:There is an EPC sensor, viz. a silver/silver halide reference electrode, on which alumina or zirconia 25 and silver halide 23 adhere to both the faces of a silver wire 26 and alumina coating 22, 24 is formed with a cataphoresis method thereon. A sensor part made as above-mentioned is lapped and protected with a guard 21 in which a slender hole is provided in the lower part thereof, an end of the silver wire 26 is electrically connected to a lead wire 31 and an upper part thereof is sealed with a glass 27. In addition, a space between the guard 21 and the lead wire 31 is filled with magnesia and an end part thereof is sealed with another glass 30. The sensor is fixed on a fixed member 29 of an instrumentation pipe of a nuclear reactor and the like and, because high temperature water of a plant is not directly brought into contact with a solid electrolyte (silver halide), its life is very long and reliability of data can be heightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for monitoring the operating state of a plant by collecting in-situ water quality data of nuclear power plants, thermal power plants and the like and making highly reliable diagnosis.

[0002]

2. Description of the Related Art JP-A-58-51312 and US Pat.
No. 52,718 describes a plant operation monitoring device.

However, in the above-mentioned Japanese Patent Laid-Open No. 58-51312, the direction of obtaining information on water quality, the method for evaluating the water quality information, the information from the water quality sensors mutually evaluated, and the water quality is monitored. Or, there is no description about the plant monitoring control system for controlling.
Further, US Pat. No. 4,552,718 describes in detail the plant operation control method and system regarding the state quantity (output value, cooling water level, reactor temperature, etc.) of nuclear plant operation, but the sensing method of the water quality itself. ，
The system technology for comprehensively evaluating the evaluation method, display system, etc., and controlling the water quality diagnosis is not described. JP 60-
No. 183595 focuses on the pH (hydrogen ion concentration) in the reactor cooling water and adjusts the pH of the cooling water to be in the range of 7.0 to 8.5. The technology about pH sensor is not clear,
The relationship between pH and other water quality information has not been clarified,
The display method when controlling is not clear. Recently, ECP sensor (reference electrode or corrosion potentiometer) in high temperature and high pressure water is a comprehensive literature of reference electrode in high temperature and high pressure water. Reference, Electrode, Pho, P, W, Earl (1987) Copyright ( 1987) Electric, Power, Research Institute, Inc. (Reference Electrode for PW
R, Copyright 1987 Electric Power Reseatch Institut
e, Inc.). The Ag / AgCl ECP sensor actually used in this document has a structure in which silver-silver chloride is immersed in a solution containing Cl ⁻ (chlorine ion) regardless of internal reference or external reference. is there.

[0004]

The Ag / AgCl electrode is a basic and typical reference electrode for electrochemical measurement, and has a small temperature coefficient. Until now, this electrode has been used for high temperature and high pressure water. However, in a severe environment of high temperature and high pressure water, deterioration of the sensor itself due to potential fluctuation due to Cl ⁻ ion outflow due to deterioration of the seal is a problem, and in particular, it is installed in the reactor and is at a level that can be used at regular inspection intervals. No ECP sensor has a long life.

Hydrogen ion concentration sensor for high temperature and high pressure water (p
H sensor), Journal Electro Chemical Society 132 , 1866 (1985) (J. Electro
Chem. Soc., 132 , 1866 (1985)), but what to do with the sealing method that becomes a problem when mounting in a furnace, or the durability of the sensor itself is a problem. In addition, since a ceramic tube (porosity is close to zero) is cut off from the high temperature water environment without taking a liquid junction, and the pH is measured using the semiconducting properties of ceramics, the impedance becomes extremely high, and it is effective against noise. There are still problems such as countermeasures and how to shut off the inside of the cylinder from the high temperature environment.

Regarding the evaluation method and the display method of the measurement result, the state quantity of the plant at the time of plant operation, for example, each state quantity such as the reactor pressure and the cooling water level is also described in Japanese Patent Laid-Open No. 58-51312 by a CRT of a computer. However, even in this case, nothing is touched on the technology for sensing each state and the technology for monitoring the water quality information, and the combination of the water quality information and what is , No means of how it should be evaluated.

[0007] In addition, no consideration has been given to the sensor technology for controlling the water quality by monitoring the water quality and feeding back the water quality data to the control system, and the water quality monitoring is performed from the problem of the reliability of the acquired data or the durability of the sensor. There was a practical problem that the system and control system itself did not hold as a practical problem. Therefore, since there is no reliable sensor, the plant operation control system can be stopped based on the mechanical aspects and state quantities of the plant, and evaluation, plant method, and monitoring data display based on the technology that grasps and controls the water quality factor that is currently a problem An evaluation method based on the system and display images, and other state variables, such as abnormal noise of the pump and the state amount of water quality near the pump, such as temperature and the result of monitoring data of water quality, should be considered from a comprehensive viewpoint. This has not been done, and there is a technical problem that the plant cannot be operated by obtaining necessary and sufficient information as a plant control method.

JP-A-59-174748 discloses an electrochemical cell in which an electrolyte is placed in a cell partitioned by a diaphragm. However, in places where the temperature and environment are severe, such as reactor water management and water quality management in thermal power plants, there are no satisfactory diaphragms in terms of heat resistance and durability, and it is difficult to put them into practical use.

As described in JP-A-58-215549,
Although it is possible to separate and quantify the dissolved hydrogen, there is a problem similar to the above because a selective hydrogen permeable membrane is required.

Electrochemical Method, John
Wheelie and Sons, Inc. Page 1980
553-573 (Electrochemical Method, John Willy
& Sons, Inc. (1980) pp.553-573),
An electrochemical measuring device for use in a nuclear plant is described. However, there is no description about an electrochemical cell that can be mounted in a reactor or plant piping system and has a reference electrode characteristic with low impedance.

A first object of the present invention is to provide means for accurately extracting water quality information of high temperature water, which is indispensable for monitoring the operating state of plants using high temperature water such as nuclear power plants and thermal power plants. It is to be.

A second object of the present invention is to obtain accurate information directly related to water quality from the plant.

A third object of the present invention is to provide a system capable of predicting the state change of the plant by comparing the monitoring data already accumulated based on the water quality information and controlling the required water quality. Is.

[0014]

In order to achieve the above object, the present invention provides an electrochemical water quality sensor installed in a monitored part of a plant to provide information directly related to the water quality of the target part for a certain period of time. A means for continuously extracting, a means for evaluating water quality based on the extracted information, a means for comparing the obtained water quality evaluation result with a predetermined plant operation reference value, and the comparison result The present invention proposes a plant operation state monitoring system characterized by comprising means for displaying or recording a necessary part of the above. As a fixed period, at least a period until the water quality information reaches a preset value or at least a period during which the water quality information can be estimated to be a preset value, and a period in which information can be continuously measured for at least 3 months Is. Preferably, the measurement is continuously performed during the period up to the periodic inspection about every one year.

The water quality sensor is installed in the monitored part of the plant, and the hot water of the monitored part and the electrolyte of the sensor come into electrochemical contact with each other, but substantially suppress the dissolution of the electrolyte in the hot water. It is arranged via a porous material.

A reference electrode (ECP sensor), a pH sensor (hydrogen ion concentration meter), and this reference electrode, which have high durability, high reliability, and are easy to mount on an actual equipment, are provided by installing an electrochemical water quality sensor in the monitored part of the plant. Based on the dissolved oxygen,
We have developed an electrochemical cell or sensor that can quantify hydrogen peroxide, etc., and have various water quality monitoring data (pH, corrosion potential, dissolved oxygen dissolved hydrogen, dissolved hydrogen peroxide, solution conductivity, etc.) based on electrochemical measurement. A means as a sensor system can be established by using it together with another crack sensor. The present invention provides two of these monitoring data
Since it is possible to provide more than one species as one sensor, it is possible to measure at the same location, and thereby more accurate information can be obtained.

The electrochemical reference electrode used in the present invention is composed of an electrolyte layer containing ions of an electrode material, a liquid impermeable porous ceramic layer surrounding the electrolyte layer, and an electrochemical contact with the electrolyte layer. And a terminal electrically connected to the electrode material, which succeeds in reducing the impedance of the reference electrode as an electrochemical cell, and has a three-electrode system including a working electrode, a counter electrode, and a reference electrode. Alternatively, it can be used as a two-electrode type electrochemical sensor.

A liquid-impermeable, heat-resistant porous coating layer surrounding the ceramic layer may be provided. Further, an electrolyte layer made of a halide of an electrode material, a liquid-impermeable porous ceramic layer surrounding the electrolyte layer, an electrode material that makes electrochemical contact with the electrolyte layer, and the ceramic layer are protected and It is also possible to use an electrochemical reference electrode having a sheath in which a part of the layer is exposed so as to come into contact with the liquid to be inspected, and a terminal electrically connected to the electrode material.

As a concrete example of the constitution of the electrochemical reference electrode, a solid electrolyte layer containing cations and halogen ions of the electrode material, a porous ceramic layer surrounding the solid electrolyte layer, and a liquid electrolyte surrounding the porous ceramic layer. Permeable ion-permeable porous insulating layer, metal electrode material that electrochemically contacts the electrolyte layer, and protects the ceramic layer so that part of the ceramic layer can contact the liquid to be tested. Some include an exposed sheath and a terminal electrically connected to the electrode material. The solid electrolyte layer may be a combination of an oxide / metal of an electrode metal material, in addition to the metal halide / metal.

The present inventors have developed a ceramics-coated sensor which has sufficient accuracy and durability, is compact, and is capable of adjusting porosity, and an electrochemical sensor using the sensor of the present invention as a reference electrode. The in-situ data obtained by such a series of sensor system configurations are mutually examined and the evaluation method is made more concrete and systematic, thereby enabling water quality diagnosis and water quality control.

The water quality diagnostic data monitored by the arithmetic processing unit and displayed on the cathode ray tube display accurately reflects the water quality information by the ceramic coating type or resin coating type sensor system and does not provide erroneous information. The staff immediately feeds back the results obtained from the water quality information display system to the operation control of the plant water quality,
Can manage plant operation.

By establishing the technology for obtaining accurate and accurate water quality information from the sensor system, it becomes possible to set the mutual relation of data, the display system, and the evaluation standard, and it becomes possible to manage water quality and plant operation in a high dimension. Become.

A silver / silver halide or silver sulfate electrode or a single silver electrode as a single or a plurality of sensors, which is directly pressure-shaped on a fine powder of ceramics or resin and adhered on the surface, or plasma play or electrophoresis. Method or both of them, or having a porosity enough to be impregnated with the solution by another method, and having a structure in which the surface is directly coated with a ceramic-based material, thereby preventing it from being dipped in a halide ion solution. The sensor can be used as a sensor showing a potential as a standard electrode (reference electrode or ECP sensor).

As the pH sensor, silver / silver oxide, platinum / thallium oxide (Tl ₂ O ₃ ), mercury / mercury oxide,
Copper / copper oxide, iridium / Ir ₂ O ₃ and IrO ₂ are directly coated with ceramics, or fine powders of ceramics and resin are compression-molded and the surface is coated to show a potential response to the hydrogen ion concentration pH of the solution. A sensor configured as shown can be used. Therefore, pH constant condition or p
When the H fluctuation is at a negligible level, the pH sensor basically fulfills the function of the ECP sensor. It is practical to install both the ECP sensor and the pH sensor.

Either or both or a plurality of ECP sensors and / or pH sensors may be provided in the vicinity of the reactor core / instrumentation pipe, the separator or its vicinity, the mixing plenum, or its vicinity, the downcomer or its vicinity, the jet pump or its vicinity. It should be installed in or near the lower plenum or in the cooling water piping system.

In addition, a means for injecting gas such as oxygen, hydrogen or chemicals to control the water quality is installed in the nuclear power plant piping system furnace. Means for electrochemically analyzing dissolved species present in a solution using a three-electrode system consisting of at least one working electrode, a reference electrode (ECP sensor) and a counter electrode or a two-electrode system using two electrodes therein May be provided.

[0027]

[Function] A total of seven types of water quality sensors, including crack sensors, which can perform water quality analysis and data acquisition and display using an arithmetic processing unit, a printer, a plotter, and a cathode ray tube display system (CRT), that is, Dissolved hydrogen (DH), dissolved oxygen (DO), (pH), (EC
P), solution conductivity (S) Dissolved hydrogen peroxide DH ₂ O ₂ sensor is installed in appropriate combination. (Hereinafter, crack sensor is (M), dissolved hydrogen is (DH), dissolved oxygen is (DO),
Solution conductivity is represented by (S) and dissolved hydrogen peroxide is represented by (DH ₂ O ₂ ). ) Water quality diagnostic data is selected from two of the seven types of sensors, and the water quality is compared with the reference values entered in advance based on the cathode ray tube display system, printer, plotter and recorder display. Diagnostic control.

Water quality can be diagnostically controlled based on (DO) and (ECP) CRTs and printer, plotter and recorder displays. All of the water quality analysis and analysis result data acquisition and display are performed using an arithmetic processing unit, a printer, a plotter, and a cathode ray tube display system.

A plurality of sensors, such as a crack sensor, a dissolved hydrogen sensor, a dissolved oxygen sensor, a corrosion potential meter or a reference electrode (ECP sensor) solution conductivity meter, and a dissolved hydrogen peroxide sensor, which measure the amount of development in the water environment, are assembled. Use together.

An example of a combination of various sensors and a display means will be described below.

(1) The water quality is diagnostically controlled on the basis of the CRT of (DH) and (DO) and the display of the printer, plotter, and recorder.

(2) The water quality is diagnostically controlled based on the CRT of (DH) and (pH) and the display of the printer, plotter and recorder.

(3) CRT of (DH) and solution conductivity (S)
Also, the water quality is diagnostically controlled based on the printer, plotter, and recorder displays.

(4) The water quality is diagnostically controlled based on the CRT, the printer, the plotter, and the recorder display of (DH) and the crack growth amount (M) of the crack sensor.

(5) Based on the CRT of (DH) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder, the water quality is diagnostically controlled.

(6) The water quality is diagnostically controlled based on the CRT of (DH) and (pH) and the display of the printer, plotter and recorder.

(7) The water quality is diagnostically controlled based on the CRT and printer, plotter, and recorder displays of (DH) and (S).

(8) The water quality is diagnostically controlled based on the CRT of (DO) and (M) and the display of the printer, plotter and recorder.

(9) The water quality is diagnostically controlled based on the CRT of (DO) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(10) The water quality is diagnostically controlled based on the CRT of (DO) and (ECP) and the display of the printer, plotter, and recorder.

(11) The water quality is diagnostically controlled based on the CRT of (pH) and (ECP) and the display of the printer, plotter and recorder.

(12) The water quality is diagnostically controlled based on the CRT of (pH) and (S) and the display of the printer, plotter and recorder.

(13) The water quality is diagnostically controlled based on the CRT of (pH) and (M) and the display of the printer, plotter and recorder.

(14) The water quality is diagnostically controlled based on the CRT of (pH) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(15) The water quality is diagnostically controlled based on the CRT of (ECP) and (S) and the display of the printer, plotter and recorder.

(16) The water quality is diagnostically controlled based on the CRT of (ECP) and (M) and the display of the printer, plotter and recorder.

(17) The water quality is diagnostically controlled based on the CRT of (ECP) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(18) The water quality is diagnostically controlled based on the CRT and printer, plotter, and recorder displays of (S) and (M).

(19) The water quality is diagnostically controlled based on the CRT of (S) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(20) The water quality is diagnostically controlled based on the CRT of (M) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(21) CR of (DH), (DO) and (pH)
Water quality is diagnostically controlled based on T, printer, plotter, and recorder display.

(22) C of (DH), (DO) and (ECP)
Water quality is diagnostically controlled based on RT, printer, plotter, and recorder display.

(23) CRT of (DH), (DO) and (S)
It also controls the water quality based on the printer, plotter, and recorder displays.

(24) CRT of (DH), (DO) and (M)
It also controls the water quality based on the printer, plotter, and recorder displays.

(25) The water quality is diagnostically controlled based on the CRT of (DH), (DO) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(26) C of (DH), (pH) and (SCP)
Water quality is diagnostically controlled based on RT, printer, plotter, and recorder display.

(27) CRT of (DH), (pH) and (S)
It also controls the water quality based on the printer, plotter, and recorder displays.

(28) CRT of (DH), (pH) and (M)
It also controls the water quality based on the printer, plotter, and recorder displays.

(29) Water quality is diagnostically controlled based on the CRT of (DH), (pH) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(30) CR of (DH), (ECP) and (S)
Water quality is diagnostically controlled based on T, printer, plotter, and recorder display.

(31) (DH) and (ECP) and (DH ₂ O ₂ )
Water quality is diagnostically controlled based on the CRT, printer, plotter, and recorder display.

(32) Based on the CRT of (DH), (S) and (M) and the display of the printer, plotter and recorder, the water quality is diagnostically controlled.

(33) C of (DH), (S) and (DH ₂ O ₂ ).
Water quality is diagnostically controlled based on RT, printer, plotter, and recorder display.

(34) (DH) and (DCB) and (DH ₂ O ₂ )
Water quality is diagnostically controlled based on the CRT, printer, plotter, and recorder display.

(35) C of (DO), (pH) and (ECP)
Water quality is diagnostically controlled based on RT, printer, plotter, and recorder display.

(36) CRT of (DO), (pH) and (S)
It also controls the water quality based on the printer, plotter, and recorder displays.

(37) CRT of (DO), (pH) and (M)
It also controls the water quality based on the printer, plotter, and recorder displays.

(38) The water quality is diagnostically controlled based on the CRT of (DO), (pH) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(39) CR of (DO), (ECP) and (S)
Water quality is diagnostically controlled based on T, printer, plotter, and recorder display.

(40) CR of (DO), (ECP) and (M)
Water quality is diagnostically controlled based on T, printer, plotter, and recorder display.

(41) (DO), (ECP) and (DH ₂ O ₂ )
Water quality is diagnostically controlled based on the CRT, printer, plotter, and recorder display.

(42) The water quality is diagnostically controlled based on the CRT of (DO), (S) and (M) and the display of the printer, plotter and recorder.

(43) C of (DO), (S) and (DH ₂ O ₂ ).
Water quality is diagnostically controlled based on RT, printer, plotter, and recorder display.

(44) (DO), (DCB) and (DH ₂ O ₂ )
Water quality is diagnostically controlled based on the CRT, printer, plotter, and recorder display.

(45) CR of (pH), (ECP) and (S)
Water quality is diagnostically controlled based on T, printer, plotter, and recorder display.

(46) CR of (pH), (ECP) and (M)
Water quality is diagnostically controlled based on T, printer, plotter, and recorder display.

(47) (pH), (ECP) and (DH ₂ O ₂ )
Water quality is diagnostically controlled based on the CRT, printer, plotter, and recorder display.

(48) Based on the CRT of (pH), (S) and (M) and the display of the printer, plotter and recorder, the water quality is diagnostically controlled.

(49) C of (pH), (M) and (DH ₂ O ₂ ).
Water quality is diagnostically controlled based on RT, printer, plotter, and recorder display.

(50) (pH), (M) and C of (DH ₂ O ₂ ).
Water quality is diagnostically controlled based on RT, printer, plotter, and recorder display.

(51) CRT of (ECP), (S) and (M)
It also controls the water quality based on the printer, plotter, and recorder displays.

(52) The water quality is diagnostically controlled based on the CRT of (ECP), (S) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(53) CR of (S), (M) and (DH ₂ O ₂ ).
Water quality is diagnostically controlled based on T, printer, plotter, and recorder display.

(54) Dissolved hydrogen concentration (DH) as a result of water quality analysis
The water quality is diagnostically controlled based on the CRT and the printer, plotter, and recorder display of the change over time.

(55) The water quality is diagnostically controlled based on the CRT and the printer, plotter, and recorder display of the change with time (DO) in the water quality analysis result.

(56) C of pH change with time in the results of water quality analysis
Water quality is diagnostically controlled based on RT, printer, plotter, and recorder display.

(57) The water quality is diagnostically controlled based on the CRT, printer, plotter, and recorder display of the ECP change over time.

(58) The water quality is diagnostically controlled based on the CRT and the printer, plotter, and recorder display of the change over time of the aqueous solution conductivity (S).

(59) The water quality is diagnostically controlled based on the CRT of the measurement result (M) of the DCB sensor and the display of the printer, plotter, and recorder.

(60) The water quality is diagnostically controlled based on the CRT and the printer, plotter, and recorder display of the change with time of the dissolved perhydrogen peroxide concentration (DH ₂ O ₂ ) of the water quality analysis result.

Hydrogen may be diagnostically controlled based on the CRT and the printer, plotter, and recorder display of the time-dependent change of each of two types of analysis data. Further, the water quality can be diagnosed and controlled based on the CRT, the printer, the plotter, and the recorder display of the time-dependent changes of the three types of analysis data.

In the water quality diagnostic control, the water quality is controlled by performing water quality analysis using random pulse voltammetry or plural kinds of voltammetry in the electrochemical cell according to the present invention. In random voltammetry, data compression method and neural network were used. Among multiple types of voltammetry, reverse pulse, normal pulse, differential pulse, square wave,
Use one of the five types of pulse voltammetry for normal differential pulses. Controlling the water quality by the _{O 2, H 2, H 2} O 2 using a random pulse voltammetry to simultaneous determination based on Borutanrumeri or the pattern recognition of a plurality of types. Furthermore, the analysis results of SO ₄ ²⁻ , Cl, Na, etc., which are decomposition products of the furnace purification resin, are also displayed, and the water quality is controlled by comparing with the reference value input in advance.

It has a function of controlling the amount of N ₂ H ₄ (hydrazine) injection into the steam generator based on the dissolved O ₂ gas data of hydrogen in the primary reactor cooling system. Dissolved H in the reactor primary cooling water system
The injection amount of H ₂ gas is controlled based on the ₂ O ₂ data. Injection H based on measurement data of H ₂ , O ₂ and H ₂ O _{2
2 The} gas injection amount may be controlled. The injection amount of H ₂ gas is controlled based on the amount of dissolved H _{2 in} the reactor primary cooling water system. The amount of H ₂ gas injected into the reactor primary cooling water is controlled based on the amount of dissolved O ₂ gas in the reactor primary cooling water system. Further, the injection amount of H ₂ gas into the reactor primary cooling water is controlled based on the amount of dissolved H ₂ O _{2 in the} reactor primary cooling water. It is also possible to detect the potential of the Zr alloy member of the nuclear fuel assembly of the nuclear power plant and monitor the amount of corrosion.

The sensor in the present invention is used in the reactor as well as
It can also be installed in the piping system between the reactor and the condenser, the water supply system, and the deaeration system, and the water quality can be controlled.
It can also be used for water quality control in thermal power plants.

[0095]

【Example】

Example 1 This example is shown in FIG. 2 in the reactor of the BWR plant shown in FIG.
Attach the ECP sensor shown in Fig. Through the instrumentation pipe in the nuclear reactor, and measure the corrosion potential of the structural materials in the reactor under this water environment by E
This is an example of attempting to control the water quality in the reactor by measuring the change over time based on the potential of the CP sensor (corresponding to the reaction of AgCl + e → Ag + Cl ^−, etc.). In FIG. 1, an ECP sensor 2 is an in-core instrumentation pipe 4 of a core 3 in a reactor pressure vessel 12.
Has been inserted into the fuel loading section of the. 1 is a dryer, 5 is a potentiostat electrochemical interface, 6 is a computer arithmetic processing automatic control device, 7 is a remote control command device and analysis result display output device, 8 is a gas / chemical injection system, 9
Is a turbine, 10 is a reactor water supply pipe, and 11 is a reactor recirculation system. A condenser, a demineralizer, a low pressure / high pressure feed water heater, and a deaerator (in the case of thermal power) are provided between the turbine 9 and the gas chemical injection system 8, but they are omitted.

FIG. 2 shows the structure of the ECP sensor of the present invention. This silver / silver halide electrode has no solution layer containing KCl or the like as a constituent element.

In the figure, alumina or zirconia is deposited on both sides of the silver wire 26 by the CVD method, and silver halide (AgC
1, AgBr or AgI) 23 is attached. After depositing the silver halide, an alumina coating 22 having a thickness of several hundred μm and a porosity of 70% or less is formed on the surface thereof by an electrophoresis method or the like. Further, an alumina coating 24 having a thickness of several mm and a porosity of 10% or less is formed on the outer periphery thereof by plasma spraying or compression molding. When the silver halide is not used, the silver wire 26 is directly connected to the ceramic layers 24 and 25.
Even with the structure coated with, it has the function of an ECP sensor.

The sensor section thus formed is covered with a SUS316L guard 21 having pores at the bottom to protect the sensor section. One end of the silver wire 26 is electrically connected to a lead wire 31 made of SUS316L. The upper part of the sensor unit is sealed with glass 27. The space between the guard 21 and the lead wire 31 is filled with magnesia 28 to insulate the two, and the ends are sealed with glass 30.

This sensor is fixed to a fixing member 29 or the like in the instrumentation pipe, and a signal of the sensor is taken out by a cable 32. According to the sensor configured in this way,
The high temperature water of the plant does not come into direct contact with the solid electrolyte (silver halide), so the life is extremely long. Therefore, from the inspection of the plant to the next inspection, a sensor can be installed in the hot water of the plant to continuously obtain direct data on the water quality, and the reliability of the data is significantly improved.

FIG. 3 shows the corrosion potential of the structural material in the reactor with respect to time using the ECP sensor.
The results are continuously output to the analysis result display system (cathode ray tube display system) 7 for all periods. Since the electric potential is displayed continuously, the set value is reached about 4.5 months after the preset value and hydrogen gas is directly injected into the furnace from the gas injection system 8. It can be seen that the corrosion potential of the material decreases with good response, and that the water quality diagnostic control system is sufficiently useful for corrosion inhibition. As you can see from the figure,
Since the water quality is displayed continuously, it is possible to properly control the set value by displaying it continuously for at least three months.

As shown in FIG. 4, the potential difference between the ECP sensor and another identical ECP sensor mounted in the in-core instrumentation pipe does not appear in the display system 7 for a long time, and this ECP meter has excellent stability, You can see that it has durability.

Example 2 In this example, a hydrogen ion concentration meter is mounted on the in-core instrumentation tube shown in FIG. The potential output corresponding to the hydrogen ion concentration of the solution can be obtained by measuring the potential of the hydrogen ion concentration meter against the potential of the ECP sensor that gives the reference potential shown in FIG. The structure of the hydrogen ion densitometer used here is the same as that shown in FIG. 2, except that a metal oxide (Pt / Tl ₂
O ₃ , Ag / Ag ₂ O, Hg / Hg ₂ O, Cu / Cu ₂ O,
_{Cu / CuO, Ir / Ir 2} O 3 , or Ir / IrO ₂₎
Was used.

FIG. 5 shows changes with time in pH (logarithm of hydrogen ion concentration). When the alkali is slightly injected from the injection system 8 for about 14 months when the pH of the display system 7 is slightly decreased as shown in FIG. 5, the pH in the furnace starts to rise at regular intervals and sufficient water quality diagnosis control can be performed. You can see that

Example 3 In this example, as in the case of Example 2, an internal reference electrode and a pH sensor were simultaneously placed in the furnace instrumentation tube to monitor the water quality environment in the furnace. The structure of the internal reference electrode used here is basically the same as that shown in FIG. 2 except that the SUS316L guard and the ceramic layer of the inner surface lining have a double structure. The structure is shown in FIG. In the figure, the difference from FIG. 2 is that a coating such as alumina or zirconia is sandwiched by SUS316L guard. The pH electrode used in this example also had a double structure guard as shown in FIG.

The display system 7 displays the relationship between the corrosion potential and the pH of the structural material in the furnace shown in FIG. 7, and as a whole, the corrosion potential of the structural material tends to increase when the pH decreases.

When alkali is injected from the chemical injection system 8 in about 13 months, the corrosion potential decreases as shown in FIG.
The tendency of pH increase is clearly seen, and the corrosion resistance of the structural material in the reactor can be sufficiently improved from the viewpoint of water quality diagnosis control.

Example 4 In this example, a micro platinum electrode 5 as a dissolved oxygen, hydrogen and hydrogen peroxide sensor as shown in FIG.
0 and the electrochemical measurement system in which the internal reference electrode shown in FIGS. FIG. 8 shows the time course of the corrosion potential of the materials inside the reactor, as well as measuring the dissolved oxygen concentration in the periphery of the core by using the micro platinum electrode by electrochemical measurement as a dissolved oxygen meter. It can be seen that by injecting hydrogen gas by the gas injection system 8 in about 11 months, the dissolved oxygen concentration decreases, the corrosion potential decreases, and sufficient water quality diagnosis control is performed. Although plural kinds of voltammetry were used in this example and the next example, the analysis procedure of dissolved hydrogen, oxygen, and hydrogen peroxide in the furnace is as follows.

In this embodiment, as the plural types of voltammetry, normal pulse voltammetry and reverse pulse voltammetry are used to separate and quantify dissolved hydrogen, dissolved oxygen, and dissolved hydrogen peroxide. When the internal reference electrode (ECP sensor) of the present invention shown in FIG. 2 or 17 is used as a reference electrode and a counter electrode for electrochemical measurement, and a micro platinum disk electrode is used as a working electrode DH, D
The total diffusion limiting currents for oxidation and reduction of a solution containing O and DH ₂ O ₂ can be given by the following equations for normal pulse voltammetry and reverse pulse voltammetry modes.

[0109]

[Equation 1]

[0110]

[Equation 2]

[0111]

[Equation 3]

[0112]

[Equation 4]

Equations (1) and (2) are H ₂ O ₂ and O ₂ in normal pulse voltammetry, respectively.
All diffusion limiting current of the reduction reaction, H ₂ O _2, the total diffusion limiting current for the oxidation reaction of H _2, the formula (3) and equation (4) is H ₂ O ₂ in the reverse pulse voltammetry, respectively, O ₂
It shows the total diffusion limit current of the oxidation reaction and the total diffusion limit current of the reduction reaction of H ₂ O ₂ and O ₂ .

[0114]

[Equation 5]

[0115]

P = 4D _j t _P / r ² (Equation 6) D is the diffusion coefficient of each reactive species j, t _P is the pulse width of the normal pulse and the reverse pulse, and r is the radius of the microdisk electrode. . Τ in the formulas (3) and (4) is a retention time of the initial setting potential of the reverse pulse voltammetry, that is, a so-called generation time. The equation (5) is such that the radius r of the microelectrode is r = 50 μM and t _p and τ are 60.
It is an effective expression up to about 0 ms.

Iss represents a steady current in the microelectrode, and is expressed by the equation (7).

[0117]

Equation 7] ^{_{iss = 4nFD j rC 0 j ...}} ( Equation 7) n represents oxygen, hydrogen, a total reaction electron number of the respective redox reaction for hydrogen peroxide. F is the Faraday constant, C
⁰ _j indicates the concentration of each chemical species j.

Here, by subtracting the value of the equation (Equation 1) from the equation (Equation 4), the following equation (Equation 8) can be obtained.

[0119]

[Equation 8]

[0120] Therefore, the vertical axis represents the equation (8), takes the horizontal axis xi] (t _p, tau), various normal pulse, the pulse width t _p to xi] of the reverse pulse (t _p, tau) If you plot and plot
That is, the hydrogen peroxide concentration can be calculated and determined.

[0121]

[Equation 9] C ⁰ (H ₂ O ₂ ) (Equation 9) The diffusion coefficient D (H ₂ O ₂ ) of hydrogen peroxide is determined in advance in a laboratory. However,

[0122]

[Equation 10]

Here, once the hydrogen peroxide is separated and quantified by the procedure shown in the equation (8), the equation (9) is substituted into the equations (2) and (3), and the remaining hydrogen concentration is The equation (Equation 11) can be determined.

[0124]

[Equation 11] C ⁰ (H ₂ ) (Equation 11) Further, by substituting the equation (Equation 9) into the equation (Equation 1), the oxygen concentration equation (Equation 12) can be determined.

[0125]

[Equation 12] C ⁰ (O ₂ ) (Equation 12) All of the above arithmetic processing is programmed in advance in the computer arithmetic processing automatic control device 6 so that it can be automatically processed. The measurement results shown in FIGS. 8, 9 and 10 are displayed by using the analyzing means shown in this embodiment.

According to the present invention, since the direct data on the hot water of the plant is collected, the reliability of the data is extremely high, and the direct data of the hot water to be monitored is continuously collected. The accuracy of operating condition monitoring is improved.

Example 5 In this example, the micro platinum electrode in the furnace instrumentation tube 4 was used as a hydrogen peroxide sensor, and the internal reference electrode shown in FIGS. 2, 6 and 17 was used, and as shown in FIG. This is an in-situ measurement of the hydrogen peroxide concentration in the reactor and in the vicinity of the reactor core using the electrochemical measurement system configured as above. As shown in FIG. 9, when hydrogen gas was slightly increased, hydrogen gas was injected from the injection system 8 under computer control, and a clear decrease in hydrogen peroxide concentration was observed on the display system 7.
Along with this, the corrosion potential also shows a tendency to decrease slightly. Since this hydrogen peroxide cannot be distinguished from dissolved oxygen and hydrogen by ordinary electrochemical analysis, a plurality of types of pulse voltammetry are carried out, and arithmetic processing is carried out to separate and quantify them.

Example 6 In this example, a crack sensor was mounted in the furnace internal measuring tube 4, and the internal reference electrode (EC) shown in FIG. 2 or 6 was used.
(P sensor) is also used, and the relationship between the crack growth amount of SUS304 steel and its corrosion potential in the reactor water environment is observed in the display system 7. As shown in FIG. 11, it can be seen that there is a correlation between the corrosion potential and the amount of crack growth due to SCC, and the growth rate is high when the corrosion potential is high. By injecting hydrogen gas by the gas injection system 8 in about 8 months, the amount of crack growth tended to slightly decrease. From this, it can be seen that sufficient water quality diagnosis control can be executed.

Example 7 In this example, the internal reference electrode (ECP sensor) shown in FIG. 2 was installed in the vicinity of the fuel assembly shown in FIG. Figure 1
In 2, the uranium pellets 44 are filled in the fuel cladding tube 42 made of Zr alloy and are fixed by the fuel holding means 40 and the end plug 45 to form the fuel element 41. A large number of fuel elements are collected in the channel box 37 and are held by the spacers (not shown) on the bolts 36 to form a fuel assembly. The sensor 38 is fixed to the upper tie plate, for example, and water quality data is taken in from a cable 39.

This example is an example of monitoring the oxide film thickness of a Zr alloy material by measuring the corrosion potential of a fuel cladding tube made of Zr alloy. Since the laboratory data has been input in advance for the relationship between the corrosion potential of the Zr alloy member and the oxide film thickness, based on the reference value, the oxidation result of the cladding potential was measured from the corrosion potential measurement result using the display system 7 immediately. You can know the film thickness. The results are shown in Fig. 13.

Example 8 FIG. 14 shows a flow of continuous water quality control in which the electrochemical measurement system shown in FIG. 16 is inserted into an instrumentation pipe in a nuclear reactor to continuously monitor dissolved oxygen and hydrogen in the reactor water. When the dissolved oxygen concentration in the reactor water exceeds the set reference value, the magnitude relationship with the set reference value of the dissolved oxygen concentration is judged, and when both the dissolved oxygen and dissolved hydrogen concentrations exceed the set value. The hydrogen gas injection valve is opened from the gas and chemical injection system 8 to start hydrogen gas injection. After the start, the magnitude relationship with the set reference values of dissolved oxygen and hydrogen concentration is judged again, and in the case of oxygen, hydrogen below the set reference value and in the case of hydrogen above the set reference value are satisfied until hydrogen is satisfied. Inject gas.

Example 9 The electrochemical measurement system shown in FIG. 16 was inserted into an instrumentation pipe in a nuclear reactor. In this case, a pH sensor having the configuration shown in FIG. 2 (however, a platinum wire is used instead of the silver wire 26, a silver halide 2
Thallium oxide was used in place of 3. ) Was used.
FIG. 15 shows a processing flow for continuously monitoring the pH of the reactor water and setting the pH of the reactor water within a predetermined range by injecting a weak acid and a weak alkali. The weak alkali is injected when the pH is lower than the predetermined range, and the weak acid is injected when the pH is higher than the predetermined range.

Example 10 FIG. 16 shows a cross section of an electrochemical cell in a neutron instrumentation tube. In this embodiment, the working electrode has a diameter of 20 μm.
The micro platinum wire of was used. The case 53 accommodating each electrode of the electrochemical cell is made of SUS316 steel. Case 5
The upper part of 3 is perforated so that reactor water and liquid can flow in and out. By providing this hole, the information of the reactor water can be grasped, and the disturbance of the electrochemical analysis, pH measurement, and corrosion potential measurement due to the convection in the electrochemical cell due to the flow of the reactor water can be minimized and measured. .

Reference numeral 2 represents a low impedance silver / silver ion reference electrode. Reference numeral 50 denotes a working electrode in which a platinum wire having a diameter of 20 μm is U-shaped. 54 is platinum / thallium oxide (Tl ₂ O ₃ ) whose electrode potential responds to the hydrogen ion concentration in the reactor water.
Shows a pH electrode. Reference numeral 51 indicates a counter electrode made of a platinum wire of 50 μm. 52 is metal oxide aluminum (Al ₂ O ₃ ) tungsten metalized, MI cable (Mineral Insula)
This is a seal member for preventing the reduction of the insulation resistance between the cable sheath and the core wire due to the intrusion of the reactor water into the ceramic insulator of the MI cable when connecting the core wire of the tor cable 57 to the counter electrode. The working electrode portion 52 of the working electrode 50 also plays the same role. Reference numeral 56 is a welded portion.
As can be seen from this figure, the reactor water directly enters the cell container at the upper part of the electrochemical cell through the hole 55, but the reactor water cannot enter the space shown at the bottom. .

The MI cable of the four space portions is the metal tube 5
It was embedded in the No. 8 and sent from the instrumentation pipe to the outside of the reactor.
Is connected to a potentiostat, a function generator, or a potentiometer 5, and is connected to a computer by a normal interface technique. Various electrochemical measurements, pulse voltammetry, random pulse voltammetry, etc. can be performed. If a lead wire is connected to the structural material that is electrically short-circuited to the welded portion 56 and the metal tube 58 and the potential difference between the two is measured with an electrometer, the corrosion potential of the stainless steel under the water quality environment in the furnace is measured. Can be measured.

If an electrometer is connected to 2 and 54, the electrode potential of 54, which is the reference electrode reference of 2, can be known. Therefore, by measuring the potential difference of 2,54, p
H can be measured. This electrochemical cell needs to be installed in the neutron instrumentation, and the four electrodes 2, 50, 54, 51 are located close to each other in order to lower the impedance such as the cell resistance when measuring with high conductivity high temperature water with low conductivity. It is installed in. The inner diameter of the cell in the container 53 filled with reactor water is 20
mm. In order to install the four electrodes in this cell as close to each other as possible, the electrodes are arranged in a circle.

FIG. 17 is an enlarged detailed view of the reference electrode portion 2 shown in FIG. This reference electrode is composed of a silver / silver ion electrode. The aluminum oxide porous layer 63 surrounding the silver wire 26 is made of a compression molded body of aluminum oxide fine powder (300 mesh pass). The porous layer 63 fills the reactor water entering through the fine pores 55 (diameter of about 0.5 mm) and stores silver ions eluted from silver. The diffusion rate of silver ions diffused from the liquid junction hole 55 of the compression molded body 63 into the reactor water varies depending on the molding pressure of the molded body. Adjust the molding pressure to adjust the elution rate to 10 ^-12 mol
/ Cm ² · s or less.

21 is a silver / silver ion electrode sheath, 61 is a tungsten metallizing seal of alumina,
This prevents reactor water from entering and lowering the insulation resistance. 59 is an alumina insulating layer, 31 is MI of SUS304
It is a cable and serves as a lead for the silver wire 26. 60 is MI
The sheath of the cable, which is made of the same SUS304 as the core wire. Reference numeral 62 is an adapter for connecting the MI cable and the electrode portion.

Example 11 This example uses the electrochemical sensor shown in FIG.
This sensor is installed in place of the ECP sensor 2 in FIG. 1 and by applying a random pulse voltammetry and a neural network, dissolved oxygen, hydrogen peroxide and hydrogen concentration formulas (equation 12), equations (equation 9), equations (Equation 11)
Is a simultaneous quantitative analysis.

Random pulse voltammetry is voltammetry in which a pattern recognition method is introduced. In the voltammetry using both the normal pulse and the reverse pulse shown in Example 4, the quantitative determination of each chemical species concentration depends on the one-dimensional information called the diffusion limit current value.
A large amount of electrolysis current data (pattern information) including information on the electrochemical reaction of each measured system is obtained by variously shaking the analyzed system using a more complicated disturbance signal (random pulse potential signal). Tried that. That is, even when the reaction potentials are close to each other as in the case of the above chemical species and separation and quantification are difficult, based on the difference in the rate of electron transfer reaction, parameters, etc. in the electrochemical reaction process of each measured substance. , Focusing on the characteristic patterns (feature vectors) in the data matrix obtained by the data compression process shown below, quantitative analysis from the size of the feature vector and the calibration curve, depending on the appearance pattern of the feature vector appearing in the data matrix. Perform qualitative analysis.

Random pulse voltammetry is the acquisition of pattern information (electrolysis current data), the compression of pattern information, and the extraction of the target information equation (Equation 12), Equation (Equation 9), and Equation (Equation 11) values from the compressed pattern information. The procedure is called. The outline of each step of, and is as follows. First, as a response signal to the random pulse potential input to the measurement system, oxygen, hydrogen peroxide,
Measure the electrolytic current of hydrogen. In the case of this embodiment, the potential signal of the random pulse has two potential waveform parameters (m,
n) is used for description. That is, the potential corresponding to the pulse potential of the first random pulse is represented by the parameter m, and the potential corresponding to the pulse potential of the second random pulse is represented by the parameter n. Therefore, with m on the x-axis and n on the y-axis, the measured data is arranged in a matrix according to the parameter value of the electrolytic current which is the response signal corresponding to the input potential on each (x, y) coordinate. In (1), the data matrix of the current component, which is the response signal of the input potential signal of 64 (8 × 8) points obtained in (4), is converted and compressed into a data vector having several components. The data compression method includes Fourier transform, Hadamard transform, Karhunen-Loeve transform, Haar transform and the like used in the field of image processing. In this embodiment, the two-dimensional Hadamard transform is used among them. In (1), the feature vector in the data vector obtained in (3) is extracted to determine the equation (Equation 12), the equation (Equation 9), and the equation (Equation 11). That is, each component value of the obtained data vector is input, and a function in which the dissolved oxygen, hydrogen peroxide, and hydrogen concentration values are output is searched for and set. In this embodiment, this function is determined using a neural network. Details of each step of and in the present embodiment will be described below.

First, the details of "acquisition of pattern information" will be described.

FIG. 18 is a diagram for explaining a method of applying a random pulse potential signal. Even if a random pulse potential signal is applied, it may not be possible to obtain information on the concentrations of dissolved oxygen, hydrogen peroxide, and hydrogen if applied randomly. In this embodiment, focusing on the fact that the voltammetry using both the normal pulse and the reverse pulse shown in the embodiment 4 can separate and determine the dissolved oxygen, hydrogen peroxide, and hydrogen concentrations, the random pulse potential based on this pulse application method is used. Thought the signal. FIG. 18A is a schematic diagram of a current (i) -potential (E) curve in a mixed system of three kinds of oxygen, hydrogen peroxide and hydrogen. Oxidation currents of hydrogen peroxide and hydrogen are observed in the positive potential region, and reduction currents of oxygen and hydrogen peroxide are observed in the negative region. The potential regions in which the oxidation current and the reduction current are observed are represented by the equations (13) and (14), respectively, and the equations (15) (l =
, 1, 2, 3 ...) levels.

[0144]

[Equation 13]

[0145]

[Equation 14]

[0146]

[Equation 15]

The reason why the expression (Equation 15) is adopted is to facilitate the processing by the computer.
In this embodiment, each level is divided into 8 (l = 3) levels, and each level is expressed by equations (13) (n) and equations (14).
It is expressed as (n) (n = 1, 2, 3 ... 8). Also, oxygen,
The electric potential at which the electrode reaction of hydrogen peroxide and hydrogen does not occur is E _C ,
Let E ₁ be the potential at which the diffusion limiting current of the oxidation reaction of hydrogen peroxide and hydrogen is obtained.

B1 to B3 in FIG. 18B represent three kinds of random pulse voltage signals applied to the working electrode of the electrochemical sensor. The first to third types of random pulse signals are the normal pulse for obtaining the formula (Formula 1), the normal pulse for obtaining the formula (Formula 2), and the reverse for obtaining the formula (Formula 4), respectively, of the fourth embodiment. It was created based on pulses.

The first type random pulse is expressed by the equation (16).
Are applied in this order.

[0150]

[Equation 16]

In the present embodiment, E _{C is set} to 1 second and the expression (Equation 2) is used.
3) and the equation (Equation 24) were set to 0.05 seconds, respectively, and the current value was sampled at the end of the equation (Equation 24) (n).
m and n are the divided levels (1
~ 8). Formula (Formula 23) (m) and Formula (Formula 24)
There are 8 × 8 = 64 combinations of potentials in (n), and m is included in the 8 × 8 data matrix equation (Equation 17).
The current value corresponding to the pair of and is stored.

[0152]

[Equation 17]

Since the equation (17) thus obtained is composed of current data of the reduction reaction of oxygen and hydrogen peroxide in the test water, the equation (12) which the equation (4) of Example 4 has ),
It has almost the same quality of information as the information on the equation (Equation 9). However, the equation (Equation 17) has a larger amount of information than the equation (Equation 1) because it includes 64-point current data. Second
The seed random pulse is applied in the order of the equation (Equation 18).

[0154]

[Equation 18]

In the present embodiment, E _{C is set} to 1 second, the equation (Equation 19),
The equation (Equation 20) is set to 0.05 seconds, respectively,
The current value was sampled at the end of.

[0156]

[Formula 19]

[0157]

[Equation 20]

In this case as well, similar to the case of the first type, the 8 × 8 data matrix equation (Equation 21) corresponding to the pair of m and n.
Is obtained. Since the equation (21) is composed of current data of the oxidation reaction of hydrogen peroxide and hydrogen in the test water, the information on the equation (9) and the equation (11) included in the equation (2) of Example 4 and It has almost the same information.

[0159]

[Equation 21]

The random pulse of the third type is expressed by the equation (22).
Are applied in this order. In the present embodiment, E _C , formula (Equation 2)
3) and Eq. (24) were set to the same time as in the case of the first type random pulse, E ₁ was set to 0.1 second, and the current value was sampled at the end of Eq. (24). In this case as well,
Similar to the case of the second type, the 8 × 8 data matrix equation (Equation 26) corresponding to the pair of m and n is obtained. The third type of random pulse is different from the first type in that E ₁ is sequentially applied to the preceding stages of equations (23) and (24).
That is, similarly to the equation (Equation 4) of the fourth embodiment, the equation (Equation 25)
In addition to the information on the reduction reaction of oxygen and hydrogen peroxide in the test water, the information includes information on the reduction reaction of oxygen generated by the oxidation of hydrogen peroxide at E ₁ .

[0161]

[Equation 22]

[0162]

[Equation 23]

[0163]

[Equation 24]

[0164]

[Equation 25]

[0165]

[Equation 26]

Details of the "compression of pattern information" will be described below.

Before transforming and compressing the data matrix into data vectors, the matrix is defined by the equation (Equation 27).

[0168]

[Equation 27]

By this operation, "information on the reduction reaction of oxygen and hydrogen peroxide in the test water" is almost canceled out.
In the formula (Equation 27), "information on the reduction reaction of oxygen generated by the oxidation of hydrogen peroxide" is concentrated. That is, the formula (Formula 27) is the formula (Formula 8) -Formula (Formula 1) of the fourth embodiment.
You will have almost the same information as.

The data matrix equation (Equation 27), the equation (Equation 17), and the equation (Equation 21) are matrix equations (Equation 28), Equation (Equation 29), Equation (Equation 30), respectively, according to Equation (Equation 2).
Is converted to.

[0171]

[Equation 28]

[0172]

[Equation 29]

[0173]

[Equation 30]

[0174]

[Formula 31] Y = H · X · H (Formula 31)

[0175]

[Equation 32]

It is Each component of matrix Y

[0177]

[Expression 33]

In other words, the information held by X appears in a specific component of the 64 components of Y. That is, 64 of X
This means that the information dispersed in the individual components has been compressed into the specific several components of Y. In the case of this embodiment, y ₁₁ , y ₁₅ ,
Information was compressed into each component of y ₅₁ , y ₁₇ , and y ₇₁ . Here, the equation (Equation 34), the equation (Equation 35), from the y ₁₁ , y ₁₅ , y ₅₁ , y ₁₇ , and y ₇₁ components of the equation (Equation 28), the equation (Equation 29), and the equation (Equation 30), respectively. A vector represented by the formula (Equation 36) is created.

[0179]

[Equation 34]

[0180]

[Equation 35]

[0181]

[Equation 36]

[0182]

Z = (y ₁₁ , y ₁₅ , y ₅₁ , y ₁₇ , y ₇₁ ) (Equation 37) From the above description, the vector equation (Equation 34) and the equation (Equation 3)
5) and formula (formula 36) are respectively represented by formula (formula 9) and formula (formula 1)
This means that the information related to 2) + equation (Equation 9) and equation (Equation 9) + Equation (Equation 11) is compressed with high density.

Details of the "extraction of target information from compressed pattern information" will be described below.

Vector equation (Equation 34) obtained for the test water of arbitrary Equation (Equation 12), Equation (Equation 9), and Equation (Equation 11)
As opposed to

[0185]

[Equation 38]

A scalar field f satisfying the above is prepared. The scalar field f is obtained in advance for equation (Equation 9) and equations (Equation 12) and Equation (Equation 11) for arbitrary arbitrary types of test water. In this embodiment, when each component of the vector expression (Equation 34) is input and the expression (Equation 9) is output, this scalar field f is determined using a neural network.

Equation (Equation 9) Equation (Equation 9) can be obtained by the operation of Equation (Equation 6) even for unknown test water.

Similarly, any equation (Equation 12), equation (Equation 9),
For the equations (35) and (36) obtained in the test water of the equation (11),

[0189]

[Formula 39]

[0190]

[Formula 40]

Scalar fields g and h satisfying the above conditions are prepared. The scalars g and h are obtained in advance for the test water for which the equations (9) and (12) are known or the equations (9) and (11) are known. In the present embodiment, a neural network in which each component of the vector formula (Formula 35) is input and the formula (Formula 12) + Formula (Formula 9) is output, and a formula in which each component of the vector formula (Formula 36) is input (Equation 11) +
The scalar fields g and h were determined using the neural networks that output the equation (Equation 9), respectively. Even for unknown test water in the equations (12), (9), and (11), the equation (12) is obtained by the equation (38), the equation (39), and the equation (40). , Equation (Equation 9), Equation (Equation 11), respectively.

FIG. 19 shows the amounts of dissolved oxygen, hydrogen peroxide, and hydrogen in the furnace, which were simultaneously quantified by the above-described method, and each of them is shown as a change with time. When the dissolved oxygen concentration and the hydrogen peroxide concentration increase, the computer 6 issues a hydrogen injection command to the gas injection system 8 by the operation of the system shown in FIG. It can be seen that the hydrogen and hydrogen peroxide concentrations are reduced by hydrogen injection.

Next, a basic calculation method in the neural network will be shown.

First, an operation (sum of products operation) for multiplying each of the set signal values Z _{1 to} Z _{n by} a weighting coefficient W _ji and adding them is calculated by the following expression (Formula 41).

[0195]

[Formula 41]

Here, Z _i (1): value of the input layer (first layer), W _ij (2 ← 1): from the i-th variable of the input layer (first layer) to the intermediate layer (second layer) , J j is a weighting coefficient for the j-th neuron element model, and C _j (2) is a sum total value of inputs to the j-th neuron element model in the intermediate layer (second layer).

In the neuron element model of the input layer, C
Depending on the cost of _j (2), the output value here is
Calculated by

[0198]

[Equation 42]

The calculation contents of the equation (Equation 2) have a relationship as shown in FIG. That is, as shown in the graph of FIG.
Depending on the value of _j (2), the value between "0" and "1" is Z
_It is obtained as _j (2). The calculated value Z _j (2) is further sent to the output layer, and the same calculation is executed in the output layer.

Next, the outline of the calculation method in the neural network will be described.

The above-mentioned input value Z _j (1) is input to the input layer of FIG. 20, and this signal (value) is output to the neuron element model of the intermediate layer. In the neuron element model of the intermediate layer, the sum of products C _j (2) of these output values Z _i (1) and the weighting factors W _ij (2 ← 1) is calculated by the formula (Equation 1), and according to this compensation. The output value Z _j (2) to the output layer is determined by the equation (Equation 2).
Similarly, the output value Z _j (2) of the intermediate layer is the weighting coefficient W _ij (3 ← 2) of the intermediate layer (second layer) and the output layer (third layer).
The product sum C _j (3) of and is calculated by the following equation (Equation 43).

[0202]

[Equation 43]

Here, Z _i (2): value of the intermediate layer (second layer), W _ji (3 ← 2): from the i-th variable of the intermediate layer (second layer) to the output layer (third layer) , J j is a weighting coefficient for the j-th neuron element model, and C _j (3) is a sum total value of inputs to the j-th neuron element model of the output layer (third layer).

Further, the output value Z _j (3) to the output layer is calculated by the following equation (Equation 44) according to the magnitude of C _j (3).

[0205]

[Equation 44]

Thus, the calculated value Z _j (3) of the output layer
Is obtained.

In order to execute learning by the neural network, a comparison layer and a teacher signal layer are further provided after the output layer as shown in FIG. 20, and the signal of the output layer and the teacher signal are input to the comparison layer. , Where the output signal and the teacher signal are compared. To reduce this error, the weighting factor W _ji (3 ←
2) and the size of W _ji (2 ← 1) is corrected.

Using this corrected value, the calculation of the equations (1) to (4) and the comparison with the teacher signal are performed again.
Similarly, an error will appear. To reduce this error,
The magnitudes of the weighting factors W _ji (3 ← 2) and W _ji (2 ← 1) are corrected again.

In this way, the weighting coefficient W _ji is repeatedly corrected until the error becomes sufficiently small. Initially, the weighting factor is given randomly (generated by a random number), so
Although the error is large, the output signal gradually approaches the teacher signal. The scalar fields f, g, and h are determined in this way. Here, the symbols c and z correspond to the density and the feature vector, respectively.

A method of correcting an error in this way is called an error backpropagation method and utilizes a technique devised by Rumelhart et al. For details, refer to the literature (Rumelhart: Par
allel Distributed Processing, MIT Press, vol.1
(1986)).

[0211]

According to the present invention, electrochemical analysis can be performed in a nuclear reactor by using a low-impedance reference electrode. In addition, it has a reference electrode structure protected by a fine porous layer, and it is possible to set the flux of reference electrode ions from the reference electrode and reactor water to 10 ^-12 mol / cm ² · s or less by flux. It has a very long life (0.5g silver / silver ion reference electrode has a silver life of more than 15 years) and enables stable electrochemical analysis. Therefore, the technology developed in the field of electrochemical measurement up to now can be applied to the water quality analysis in the reactor, and the water quality in the reactor can be measured in-situ for the first time.
The information in the furnace can be accurately grasped by analyzing in. With this technology, a plant operating condition monitoring system using in-situ water quality data can be constructed.

[0212] Further, the reliability of the data is improved by applying the water quality sensing technology based on the electrochemical cell structure having a life longer than the periodic inspection period of the reactor and the neural network to the water quality data, and the reliability of the operation monitoring system is dramatically improved. Increase to.

According to the present invention, unlike the electrochemical cell described in JP-A-59-177474, it is not necessary to use a resin diaphragm which is durable and has good permeation selectivity. Can be used for a long time even underneath.

Further, the technique described in JP-A-56-77751 measures the pH of high temperature water using zirconium oxide or the like as a film for hydrogen ion sensing element.
Since zirconium oxide and the like have extremely large impedance, there is a problem in practical use. On the other hand, in the present invention, since the ionizable electrode material is wrapped with the sheath of porous ceramic or porous heat-resistant plastic, it is possible to construct an electrochemical cell having an appropriate impedance, and to provide an output signal processing circuit or the like. It doesn't take too much.

In the present invention, since the impedance of the reference electrode and the like can be made sufficiently low, the impedance of the feedback circuit of the control amplifier can be made small and the oscillation phenomenon due to the phase shift of the input signal can be prevented. .

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a plant operating state monitoring system in which the present invention is applied to a nuclear power plant.

FIG. 2 is a sectional view showing the structure of a silver halide internal reference electrode (ECP).

FIG. 3 is a graph showing a relationship between a corrosion potential change over time of a structural material in a furnace and a hydrogen gas injection effect.

FIG. 4 is a graph showing the potential difference of a silver halide internal reference electrode.

FIG. 5 is a graph showing the relationship between changes in pH in the furnace over time and alkali injection effects.

FIG. 6 is a sectional view showing another structure of a silver halide internal reference electrode.

FIG. 7 is a graph showing the relationship between the corrosion potential of the structural material inside the furnace and the chemical injection effect.

FIG. 8 is a graph showing the relationship between changes in corrosion potential and dissolved oxygen concentration of a structural material in a furnace over time and hydrogen gas injection effect.

FIG. 9 is a graph showing the relationship between the corrosion potential of the structural material in the furnace and the change with time of the dissolved hydrogen peroxide concentration and the chemical injection effect.

FIG. 10 is a graph showing the relationship between the corrosion potential of the reactor internal structural material, the dissolved oxygen, hydrogen concentration, and hydrogen peroxide concentration over time and the chemical injection effect.

FIG. 11 is a graph showing the relationship between the corrosion potential of the crack sensor, the change over time in the amount of crack development of the sensor, and the chemical injection effect.

FIG. 12 is a partially cutaway sectional view showing the structure of a nuclear fuel assembly to which the present invention has been applied.

FIG. 13 is a graph showing the relationship between the corrosion potential of the Zr alloy fuel cladding tube and the thickness of the Zr alloy oxide film.

FIG. 14 is a flow chart of the plant operating state monitoring system of the present invention.

FIG. 15 is a flowchart of the plant operating state monitoring system of the present invention.

FIG. 16 is a sectional view showing the structure of an electrochemical sensor including an internal reference electrode, a working electrode, and a counter electrode.

FIG. 17 is a cross-sectional view showing details of a ceramic-integrated silver / silver ion reference electrode.

FIG. 18A is a current (i) -potential (E) curve diagram in a mixed system of three kinds of oxygen, hydrogen peroxide, and hydrogen, and (b).
FIG. 4 is a graph showing a random pulse signal applied to the working electrode of the electrochemical sensor.

FIG. 19 is a graph showing the time dependence of the results of separation and quantification of dissolved oxygen, hydrogen peroxide, and hydrogen using random pulses and the results of hydrogen injection.

FIG. 20 is a diagram showing a configuration of a neural network used for determining scalar fields f, g, and h.

[Explanation of symbols]

2 ... Internal reference electrode, 3 ... In furnace, 4 ... In-furnace instrumentation tube, 5 ... Potentiostat, electrochemical interface, 6 ...
Computer arithmetic processing automatic control device, 7 ... Remote control command device and analysis result display, output device, 8 ... Gas and chemical injection system, 21 ... Guard (sheath), 22, 24 ... Alumina coating, 23 ... Silver halide, 26 … Silver wire, 27
... Glass, 31 ... Lead wire, 33 ... Ceramic coating, 38 ... Sensor, 50 ... Working electrode, 51 ... Counter electrode, 52 ... Seal member, 53 ... Case, 54 ... pH electrode, 55 ... Liquid junction hole, 57 ... Seal Members, 57, 60 ...
MI cable, 58 ... Metal tube, 59, 63 ... Alumina powder insulating layer, 61 ... Alumina cap, 62 ... Joining adapter.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G01N 27/30 311 Z 7235-2J 27/403 27/27 G21D 3/08 G 9117-2G 7235- 2J G01N 27/30 371 H 7235-2J 27/46 A (72) Inventor Takuya Takahashi 4026 Kujimachi, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Masa Izumiya ▲ Kiyo ▼ Hitachi, Ibaraki Prefecture 4026 Kuji Town, Hitachi, Ltd.Hitachi Research Institute, Ltd. (72) Inventor Isao Masaoka 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Institute, Hitachi Research Institute, Ltd. (72) Keiji Kojima Kuji Town, Hitachi, Ibaraki Prefecture 4026 Address Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Masatoshi Inagaki Kuji Town, Hitachi City, Ibaraki Prefecture 4026 Hitachi Research Laboratory, Hitachi, Ltd. (72) Invention Katsumi Ohsumi 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Co., Ltd. Hitachi factory (72) Inventor Makoto Hayashi 502 Jinmachi-cho, Tsuchiura-shi, Ibaraki Hiritsu Seisakusho Co., Ltd. (72) Inventor Fumio Sato 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Inside Hitachi, Ltd. (72) Inventor Masateru Suwa 4026, Kuji-cho, Hitachi City, Ibaraki Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor, Kimihiko Akahori Hitachi, Ibaraki 4026, Kuji-machi, Ichi, Hitachi Research Laboratory, Hitachi, Ltd. (72) Kenji Baba 4026, Kuji-cho, Hitachi, Hitachi, Ibaraki Prefecture, Hitachi Research Institute, Hitachi, Ltd. (72) Hiroshi Yamauchi 4026, Kuji-machi, Hitachi, Ibaraki Prefecture Address Hitachi Research Laboratory, Hitachi, Ltd. (72) Noriyuki Onaka 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd.

Claims (12)

[Claims] 1. A means for continuously extracting information directly related to high-temperature water of an object part for a certain period by an electrochemical water quality sensor installed in the object part of the plant to be monitored, and based on the extracted information. Means for evaluating the water quality, means for comparing the obtained water quality evaluation result with a predetermined reference value for plant operation, and means for displaying or recording a necessary part of the comparison result, The water quality sensor,
An electrolyte layer containing ions of the electrode material, a liquid-impermeable porous ceramic layer surrounding the electrode layer, an electrode material that electrochemically contacts the electrolyte layer, and a terminal electrically connected to the electrode material. A plant operating condition monitoring system comprising an electrochemical reference electrode or a pH electrode. 2. A means for continuously extracting information directly related to high temperature water of the target portion by an electrochemical water quality sensor installed in the monitored portion of the plant during the period from the inspection of the plant to the next inspection, Means for evaluating the water quality based on this extracted information, and means for comparing the obtained water quality evaluation results and a predetermined reference value for plant operation,
A means for displaying and recording a necessary part of the comparison result, wherein the water quality sensor comprises a solid electrolyte layer containing ions of an electrode material, a porous ceramic layer surrounding the solid electrolyte layer,
Electrochemical comprising an electrode material in electrochemical contact with the electrolyte layer, a liquid-impermeable, heat-resistant porous coating layer surrounding the ceramic layer, and a terminal electrically connected to the electrode material. A plant operating condition monitoring system, which is a reference electrode or a pH electrode. 3. A means for continuously extracting information directly related to the high temperature water of the target portion for a certain period by an electrochemical water quality sensor installed in the target portion of the plant for monitoring, and based on the extracted information. Means for analyzing the water quality, a means for comparing the obtained water quality analysis result with a predetermined reference value for plant operation, a means for displaying a necessary part of the comparison result, and a comparison result A plant operating condition monitoring system comprising: a means for recording a necessary part and a means for generating a necessary control signal according to the operating condition of the plant. 4. A water quality sensor installed in a monitored part of a plant, in which high temperature water and an electrolyte of the monitored part are in electrochemical contact with each other through a porous material, directly to the water quality of the high temperature water of the target part. A means for continuously extracting relevant information for a certain period of time, a means for analyzing water quality based on this extracted information, and comparing the obtained water quality analysis results with predetermined reference values for plant operation. And a means for displaying or recording a necessary portion of the comparison result. 5. A porous material, which is installed in a monitored part of a plant and in which high temperature water of the monitored part and an electrolyte are in electrochemical contact with each other, but which substantially suppresses dissolution of the electrolyte in the high temperature water. Means for extracting information directly related to the water quality of the hot water of the target portion by means of the water quality sensor arranged, means for analyzing the water quality based on the extracted information, and the obtained water quality analysis result and the predetermined A plant operating condition monitoring system, comprising: a unit for comparing the obtained plant operating operation with a reference value; and a unit for displaying and / or recording a necessary part of the comparison result. 6. A means for continuously extracting data on the water quality of a circulating water system or a stored water system from an inspection of the plant to the next inspection by an electrochemical sensor installed in a monitored part of the plant containing high temperature water, A means for comparing the extracted data with a predetermined reference value of the plant operation operation, a means for predicting a change in the reference value based on the mutual relationship between the plant operation operation reference and the data, An operating condition monitoring system for a plant, comprising: a means for comparing the amount of fluctuation with the data and a means for controlling the water quality. 7. A means for continuously analyzing water quality of a circulating water system or a stored water system from a periodic inspection of a plant to the next inspection by an electrochemical sensor installed in a monitored portion of a plant containing high temperature water, Means for displaying analysis results,
Means for selecting a predetermined plant operation reference value corresponding to the water quality analysis result, and means for predicting the amount of change in the reference value based on the interrelationship between the analysis result and the plant operation reference value, and A plant operation state monitoring system comprising means for controlling water quality. 8. The water quality of the circulating water system or the stored water system is continuously analyzed from the periodic inspection of the plant to the next inspection by an electrochemical sensor installed in the monitored part of the plant containing high temperature water, and at least pH, Means for outputting data regarding dissolved oxygen amount and dissolved hydrogen concentration, means for displaying this analysis result, means for selecting a predetermined plant operation reference value corresponding to the water quality analysis result, and analysis result An operating condition monitoring system for a plant, comprising: means for predicting the amount of change in the reference value based on the correlation with the plant operation reference value; and means for controlling the water quality. 9. The sensor has a ceramic or resin layer having fine pores for covering a solid electrolyte or an electrode material formed on an electrode of a supporting substrate.
The operating state monitoring system of the plant described. 10. The sensor comprises dissolved hydrogen (DH), dissolved oxygen (DO), hydrogen ion concentration (pH), reference electrode or corrosion potential detection electrode (ECP), solution conductivity (S), dissolved peroxidation. 9. The plant operating condition monitoring system according to claim 1, further comprising a hydrogen (DH ₂ O ₂ ) sensor and a crack sensor (M). 11. An electrochemical water quality sensor installed in a target section exposed to high-temperature water in a nuclear reactor continuously for a whole period until at least water quality information regarding the high-temperature water in the target section reaches a preset value. And a means for continuously recording and displaying the obtained water quality information for the entire period, the operating state monitoring system for a nuclear power plant. 12. An electrochemical water quality sensor installed in a neutron instrumentation pipe exposed to high-temperature water in a nuclear reactor and in a fuel-loaded portion to provide water quality information on the high-temperature water for at least 3 months during operation of the nuclear reactor. An operating state monitoring system for a nuclear power plant, comprising: a unit for continuously extracting the water quality information; and a unit for continuously recording and displaying the obtained water quality information for the at least three months.