JP2842156B2 - Plant operation status monitoring system - Google Patents

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 water quality data of a nuclear power plant or a thermal power plant in-situ and performing highly reliable diagnosis.

[0002]

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

However, in Japanese Patent Application Laid-Open No. 58-51312, the direction of obtaining information on water quality, a method for evaluating water quality information, and information from water quality sensors of water quality sensors are comprehensively evaluated to monitor water quality. Or a plant monitoring and control system for control.
Also, in US Pat. No. 4,552,718, a plant operation control method and a system relating to state quantities (output value, cooling water level, furnace temperature, etc.) of a nuclear power plant operation are described in detail, but a method of sensing water quality itself is described. ,
There is no description of a system technology that comprehensively evaluates the evaluation method, display system, and the like and performs water quality diagnosis control. JP-A-60-
No. 183595 focuses on the pH (hydrogen ion concentration) of the reactor cooling water, and there is a method of operating the plant by adjusting the pH of the cooling water to be in a range of 7.0 to 8.5. Technology about pH sensor is not clear,
The relationship between pH and other water quality information has not been clarified,
The display method for controlling is not clear. An ECP sensor (reference electrode or corrosion potential meter) in high-temperature and high-pressure water has recently been a comprehensive literature of reference electrodes in high-temperature and high-pressure water. Reference, Electrode, Four, P, W, R (1987) Copyright (1987) 1987) Electric, Power, Research Institute, Inc. (Reference Electrode for PW
R, Copyright 1987 Electric Power Reseatch Institut
e, Inc.). Indeed Ag / AgCl ECP sensor that is provided for use in this document internal reference, the silver-silver chloride regardless of external references Cl - intended immersed structure in a solution containing ^(chlorine ions) is there.

[0004]

The Ag / AgCl electrode is a basic and representative reference electrode for electrochemical measurement and has a small temperature coefficient and has been used in high-temperature and high-pressure water to date. However, in a severe environment such as high temperature and high pressure water, deterioration of the sensor itself due to potential fluctuation due to Cl ^- ion leakage due to deterioration of the seal is a problem, especially when it is installed in a nuclear reactor and it can be used at regular inspection intervals. No ECP sensor has a lifetime.

A hydrogen ion concentration sensor (p.
H sensor) for Journal Electrochemical
Society 132 , 1866 (1985) (J. Electroc
132 , 1866 (1985)). However, there is a problem in how to use a sealing method which becomes a problem when the sensor is mounted in a furnace, or in durability of the sensor itself. In addition, it does not take a liquid junction, cuts off from the high temperature water environment with a ceramic (porosity is close to zero) cylinder, and measures the pH using the semiconducting properties of ceramics. Issues such as countermeasures and methods for shutting off the inside of the cylinder from the high temperature water environment remain.

[0006] Similarly, the method of evaluating and displaying the measurement results is described in Japanese Patent Application Laid-Open No. 58-51312 described above. In this case, a means for displaying a specific image is disclosed, but also in this case, there is no mention of a technology for sensing each state and a technology for monitoring water quality information, and what and what combination of water quality information is used. And no means of how to evaluate it.

Further, no consideration is given to sensor technology when monitoring water quality and feeding back water quality data to a control system to control water quality, and water quality monitoring is performed due to the reliability of the obtained data or the durability of the sensor. There was a practical problem that the system and the control system themselves did not hold as actual problems. Therefore, since there is no reliable sensor, the plant operation control system is limited to the mechanical aspects of the plant and the state variables, and the evaluation, plant method, and monitoring data display based on the technology that grasps and controls the water quality factors that are currently a problem The evaluation method based on the system and the displayed image, and other state quantities, such as abnormal sound of the pump and the state quantity of water quality near the pump, such as temperature, etc. There has been a technical problem in that necessary and sufficient information is obtained as a plant control method and the plant cannot be operated.

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 is high and the environment is severe, such as reactor water management of a nuclear reactor and water quality management of a thermal power plant, there is nothing that can satisfy the heat resistance and durability of the diaphragm, and it is difficult to put it to practical use.

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

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

A first object of the present invention is to provide a means for accurately extracting water quality information of high-temperature water which is indispensable for monitoring the operation state of a plant using high-temperature water such as a nuclear power plant or a thermal power plant. It is to be.

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

A third object of the present invention is to provide a system capable of predicting a change in the state of a plant based on water quality information and comparing it with monitoring data already stored, and performing necessary water quality control. It 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, for a certain period of time, for information relating directly to the water quality of the monitored part. Means for continuously extracting, means for evaluating water quality based on the extracted information, means for comparing the obtained water quality evaluation result with a predetermined reference value for plant operation, and the comparison result And a means for displaying or recording a necessary part of the system. As a certain 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 estimate a preset value, and a period during which information can be continuously measured for at least three months. It is. Preferably, the measurement is performed continuously during a period until a periodic inspection is performed about every year.

The water quality sensor is installed in a monitoring target portion of a plant, and high-temperature water in the monitoring target portion comes into electrochemical contact with an electrolyte of the sensor, but dissolution of the electrolyte in the high-temperature water is substantially suppressed. It is arranged via a porous material.

A reference electrode (ECP sensor), a pH sensor (hydrogen ion concentration meter), and a reference electrode, which are provided with an electrochemical water quality sensor at a monitoring target portion of a plant, are highly durable, highly reliable, and easy to mount on an actual machine. Dissolved oxygen based on
Developed an electrochemical cell or sensor capable of quantifying hydrogen peroxide, etc., and provided numerous water quality monitoring data (pH, corrosion potential, dissolved oxygen dissolved hydrogen, dissolved hydrogen peroxide, solution conductivity, etc.) based on electrochemical measurements and the like. The means as a sensor system can be established by using together with another crack sensor. The present invention is based on these monitoring data.
Since more than one species can be provided as one sensor, it is possible to measure at the same location, thereby obtaining more accurate information.

The structure of the electrochemical reference electrode used in the present invention comprises 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. Electrode material and a terminal electrically connected to the electrode material, thereby successfully reducing the impedance of the reference electrode as an electrochemical cell, and a three-electrode system of a working electrode, a counter electrode, and a reference electrode. Alternatively, it can be used as a two-electrode electrochemical sensor.

Further, 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 electrochemically contacting the electrolyte layer, protecting the ceramic layer, 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 may be used.

As a specific configuration example of the electrochemical reference electrode, a solid electrolyte layer containing cations and halogen ions of an electrode material, a porous ceramic layer surrounding the solid electrolyte layer, and a liquid electrolyte layer surrounding the porous ceramic layer are provided. A permeable ion-permeable porous insulating layer, a metal electrode material that is in electrochemical contact with the electrolyte layer, and protects the ceramic layer so that a portion 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 a metal halide / metal.

The present inventors have developed a ceramic-coated sensor having sufficient precision, durability, compactness, and adjustable porosity, and an electrochemical sensor using the sensor of the present invention as a reference electrode, which can be developed. Water quality diagnosis and water quality control are made possible by mutually examining in-situ data obtained by a series of sensor system configurations and by making the evaluation method more concrete and systematic.

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 a ceramic coat type or resin coat type sensor system and does not provide erroneous information, so that the operation is performed. The staff immediately feeds back the results obtained from the water quality information display system to the operation control of the plant water quality,
Plant operation management is possible.

With the establishment of accurate and accurate water quality information acquisition technology from the sensor system, it is possible to set the mutual relationship of data, the display system, and the evaluation criteria, thereby enabling high-dimensional water quality and plant operation management. Become.

A silver / silver halide or silver sulfate electrode or a single silver electrode is formed by directly shaping a ceramic or resin fine powder under pressure as a single or a plurality of sensors and tightly coating the surface, or by plasma play or electrophoresis. The surface is directly coated with a ceramic material having a porosity enough to be impregnated with the solution by a method using both or both methods, or by another method, so that the structure is not immersed in the halide ion solution. The sensor can be used as a sensor that indicates the potential as a reference electrode (reference electrode or ECP sensor).

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

Either one or both of the ECP sensor and the pH sensor, or a plurality thereof, may be provided near the reactor core / instrumentation tube, the separator or the vicinity thereof, the mixing plenum or the vicinity thereof, the downcomer or the vicinity thereof, the jet pump or the vicinity thereof. , Lower plenum or its vicinity or in a cooling water piping system.

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

[0027]

A total of seven types of water quality sensors including a crack sensor, which can perform water quality analysis and analysis result data capture and display using an arithmetic processing unit, a printer, a plotter, and a cathode ray tube display system (CRT). 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),
The solution conductivity is expressed as (S) and the dissolved hydrogen peroxide is expressed as (DH ₂ O ₂ ). ) Water quality diagnostic data is selected from two of the seven types of sensors, and compared with reference values entered in advance based on the cathode ray tube display system, printer, plotter and recorder display, and water quality is determined. Perform diagnostic control.

Based on the CRT of (DO) and (ECP) and the display of the printer, plotter and recorder, the water quality can be diagnosed and controlled. The water quality analysis and analysis result data acquisition and display are all performed by 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, a dissolved hydrogen peroxide sensor, and the like, which measure the amount of development in the water environment. Use together.

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

(1) Diagnosis and control of water quality are performed based on the CRT of (DH) and (DO) and the display of the printer, plotter, and recorder.

(2) Diagnosis and control of water quality are performed based on CRT of (DH) and (pH) and display of printer, plotter and recorder.

(3) CRT of (DH) and solution conductivity (S)
Diagnosis and control of water quality are performed based on the display of the printer, plotter, and recorder.

(4) Diagnosis and control of water quality are performed based on the display of the CRT and the printer, plotter and recorder of (DH) and the crack growth amount (M) of the crack sensor.

(5) Diagnosis and control of water quality are performed based on the display of the CRT of (DH) and (DH ₂ O ₂ ) and the printer, plotter, and recorder.

(6) Diagnosis and control of water quality are performed based on the CRT of (DH) and (pH) and the display of the printer, plotter and recorder.

(7) Diagnosis and control of water quality are performed based on the display of the CRT, printer, plotter and recorder of (DH) and (S).

(8) Diagnosis and control of water quality are performed based on the CRTs of (DO) and (M) and the displays of the printer, plotter and recorder.

(9) Diagnosis and control of water quality are performed based on the CRT of (DO) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(10) Diagnosis and control of water quality are performed based on the CRT of (DO) and (ECP) and the display of the printer, plotter and recorder.

(11) Diagnosis and control of water quality are performed based on the CRT of (pH) and (ECP) and the display of the printer, plotter and recorder.

(12) Diagnosis and control of water quality are performed based on the display of the CRT, printer, plotter and recorder of (pH) and (S).

(13) Diagnosis and control of water quality are performed based on the CRT of (pH) and (M) and the display of the printer, plotter and recorder.

(14) Diagnosis and control of water quality are performed based on the CRT of (pH) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

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

(16) Diagnosis and control of water quality are performed based on the display of the CRT and the printer, plotter, and recorder of (ECP) and (M).

(17) Diagnosis and control of water quality are performed based on the CRT of (ECP) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(18) Diagnosis and control of water quality are performed based on the display of the CRT, printer, plotter and recorder of (S) and (M).

(19) Diagnosis and control of water quality are performed based on the CRT of (S) and (DH ₂ O ₂ ) and the display of the printer, plotter and recorder.

(20) Diagnosis and control of water quality are performed 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)
Diagnosis and control of water quality are performed based on T and the display of the printer, plotter and recorder.

(22) C of (DH), (DO) and (ECP)
Diagnosis and control of water quality are performed based on the RT and the display of the printer, plotter, and recorder.

(23) CRT of (DH), (DO) and (S)
Diagnosis and control of water quality are performed based on the display of the printer, plotter, and recorder.

(24) CRT of (DH), (DO) and (M)
Diagnosis and control of water quality are performed based on the display of the printer, plotter, and recorder.

(25) Diagnosis and control of water quality are performed 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)
Diagnosis and control of water quality are performed based on the RT and the display of the printer, plotter, and recorder.

(27) CRT of (DH), (pH) and (S)
Diagnosis and control of water quality are performed based on the display of the printer, plotter, and recorder.

(28) CRT of (DH), (pH) and (M)
Diagnosis and control of water quality are performed based on the display of the printer, plotter, and recorder.

(29) Diagnosis and control of water quality are performed 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)
Diagnosis and control of water quality are performed based on T and the display of the printer, plotter and recorder.

(31) (DH), (ECP) and (DH ₂ O ₂ )
Diagnosis and control of water quality based on the CRT and the display of the printer, plotter and recorder.

(32) Diagnosis and control of water quality are performed based on the display of the CRT of (DH), (S) and (M) and the display of the printer, plotter and recorder.

(33) C of (DH), (S) and (DH ₂ O ₂ )
Diagnosis and control of water quality are performed based on the RT and the display of the printer, plotter, and recorder.

(34) (DH), (DCB) and (DH ₂ O ₂ )
Diagnosis and control of water quality based on the CRT and the display of the printer, plotter and recorder.

(35) C of (DO), (pH) and (ECP)
Diagnosis and control of water quality are performed based on the RT and the display of the printer, plotter, and recorder.

(36) CRT of (DO), (pH) and (S)
Diagnosis and control of water quality are performed based on the display of the printer, plotter, and recorder.

(37) CRT of (DO), (pH) and (M)
Diagnosis and control of water quality are performed based on the display of the printer, plotter, and recorder.

(38) Diagnosis and control of water quality are performed 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)
Diagnosis and control of water quality are performed based on T and the display of the printer, plotter and recorder.

(40) CR of (DO), (ECP) and (M)
Diagnosis and control of water quality are performed based on T and the display of the printer, plotter and recorder.

(41) (DO), (ECP) and (DH ₂ O ₂ )
Diagnosis and control of water quality based on the CRT and the display of the printer, plotter and recorder.

(42) Diagnosis and control of water quality are performed based on the CRT, printer, plotter and recorder displays of (DO), (S) and (M).

(43) C of (DO), (S) and (DH ₂ O ₂ )
Diagnosis and control of water quality are performed based on the RT and the display of the printer, plotter, and recorder.

(44) (DO), (DCB) and (DH ₂ O ₂ )
Diagnosis and control of water quality based on the CRT and the display of the printer, plotter and recorder.

(45) CR of (pH), (ECP) and (S)
Diagnosis and control of water quality are performed based on T and the display of the printer, plotter and recorder.

(46) CR of (pH), (ECP) and (M)
Diagnosis and control of water quality are performed based on T and the display of the printer, plotter and recorder.

(47) (pH), (ECP) and (DH ₂ O ₂ )
Diagnosis and control of water quality based on the CRT and the display of the printer, plotter and recorder.

(48) Diagnosis and control of water quality are performed based on the CRT of (pH), (S) and (M) and the display of the printer, plotter and recorder.

(49) C of (pH), (M) and (DH ₂ O ₂ )
Diagnosis and control of water quality are performed based on the RT and the display of the printer, plotter, and recorder.

(50) C of (pH), (M) and (DH ₂ O ₂ )
Diagnosis and control of water quality are performed based on the RT and the display of the printer, plotter, and recorder.

(51) CRT of (ECP), (S) and (M)
Diagnosis and control of water quality are performed based on the display of the printer, plotter, and recorder.

(52) Diagnosis and control of water quality are performed 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 )
Diagnosis and control of water quality are performed based on T and the display of the printer, plotter and recorder.

(54) Dissolved hydrogen concentration (DH) of water quality analysis result
Diagnosis and control of water quality are performed based on the CRT and the display of the printer, plotter, and recorder with time.

(55) Diagnosis and control of water quality are performed based on the CRT and the display of the printer, plotter, and recorder of the temporal change of (DO) in the water quality analysis result.

(56) C of time-dependent change in pH in water quality analysis results
Diagnosis and control of water quality are performed based on the RT and the display of the printer, plotter, and recorder.

(57) Diagnosis and control of water quality are performed based on the display of the CRT over time and the display of the printer, plotter and recorder.

(58) Diagnosis and control of water quality are performed based on the CRT of the change in the aqueous solution conductivity (S) with time and the display of the printer, plotter and recorder.

(59) Diagnosis and control of water quality are performed based on the CRT and the display of the printer, plotter and recorder of the change over time of the measurement result (M) of the DCB sensor.

(60) Diagnosis and control of water quality is performed based on the CRT and the display of the printer, plotter and recorder of the change over time of the dissolved hydrogen peroxide concentration (DH ₂ O ₂ ) as a result of the water quality analysis.

Diagnosis control of hydrogen may be performed on the basis of the CRT and the display of the printer, plotter, and recorder of the two kinds of analysis data which change with time. In addition, the water quality can be diagnostically controlled based on the CRT and the display of the printer, plotter, and recorder of the three kinds of analysis data with time.

In the water quality diagnosis control, water quality is controlled by performing water quality analysis using random pulse voltammetry or plural types of voltammetry in the electrochemical cell according to the present invention. In random voltammetry, a data compression method and a neural network were used. Among multiple types of voltammetry, reverse pulse, normal pulse, differential pulse, square wave,
One of a total of five types of normal differential pulse pulse voltammetry is used. Water quality is controlled by simultaneously quantifying O ₂ , H ₂ , and H ₂ O ₂ using a plurality of types of voltammetric or random pulse voltammetry based on the above pattern recognition. Further, 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 a reference value input in advance.

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

The sensor according to the present invention can be used in a nuclear reactor,
It can also be provided in a piping system, a water supply system, and a degassing system between the reactor and the condenser, and can control the water quality.
It can also be used for water quality control in a thermal power plant.

[0095]

【Example】

Example 1 The present example is shown in FIG. 2 in the reactor of the BWR plant shown in FIG.
The ECP sensor shown in (1) was installed through the instrumentation pipe in the reactor.
CP sensor potential ^- with respect to the (AgCl + e → Ag + Cl corresponding to the reaction and the like) to measure the change with time, an example of attempts to water quality control in the reactor. In FIG. 1, an ECP sensor 2 is an in-core instrumentation tube 4 of a reactor core 3 in a reactor pressure vessel 12.
Is inserted in the fuel loading section. 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 an analysis result display output device, 8 is a gas and chemical injection system, 9
Is a turbine, 10 is a reactor water supply pipe, and 11 is a reactor recirculation system. Note that a condenser, a desalinator, a low-pressure / high-pressure feedwater heater, and a deaerator (in the case of thermal power) are omitted between the turbine 9 and the gas chemical injection system 8.

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

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

The sensor thus formed is wrapped with a SUS316L guard 21 having a small hole at the bottom to protect the sensor. 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 them, and the ends are sealed with glass 30.

The 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 to the outside. According to the sensor configured as described above,
Since the hot water of the plant does not directly contact the solid electrolyte (silver halide), the life is extremely long. Therefore, the sensor can be installed in the high-temperature water of the plant from the inspection of the plant to the next inspection, and the direct data on the water quality can be continuously obtained, and the reliability of the data is remarkably improved.

FIG. 3 shows the corrosion potential of the structural material inside the reactor with respect to time using an ECP sensor.
Are continuously output to the analysis result display system (cathode ray tube display system) 7 for the entire period. Since the potential is continuously displayed, the preset value is reached after about 4.5 months, and the hydrogen gas is directly injected into the furnace from the gas injection system 8, whereby the structure inside the furnace is changed. It can be seen that the corrosion potential of the material decreased with good response, and that the water quality diagnostic control system was sufficiently useful for controlling corrosion. As you can see from the figure,
Since the water quality is displayed continuously, it is possible to appropriately control the set value by displaying the water quality continuously for at least three months.

As shown in FIG. 4, the potential difference between another identical ECP sensor installed in the instrumentation tube in the furnace does not appear in the display system 7 for a long time, and this ECP meter has excellent stability, It turns out that it has durability.

Example 2 In this example, a hydrogen ion concentration meter was mounted on an in-furnace instrumentation tube shown in FIG. By measuring the potential of the hydrogen ion concentration meter with respect to the potential of the ECP sensor which gives the reference potential shown in FIG. 2, a potential output corresponding to the hydrogen ion concentration of the solution can be obtained. The configuration of the hydrogen ion densitometer used here is the same as that shown in FIG. 2 except that the silver halide in FIG. 2 is replaced by 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₎
That is, was used.

FIG. 5 shows the change over time in pH (logarithm of hydrogen ion concentration). When the alkali slightly injected in about 14 months from the injection system 8 when the pH of FIG. 5 output to the display system 7 slightly decreases, the pH in the furnace starts to increase at regular intervals and the water quality diagnostic control can be sufficiently performed. You can see that there is.

Example 3 In this example, as in Example 2, an internal reference electrode and a pH sensor were simultaneously placed in an in-furnace instrumentation tube, and the water quality environment in the furnace was monitored. 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. The drawing differs from FIG. 2 in that a coating of alumina or zirconia is sandwiched between SUS316L guards. The pH electrode used in this example had a double structure guard as shown in FIG.

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

When the 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 rise is clearly seen, and the corrosion resistance of structural materials in the furnace can be sufficiently improved from the viewpoint of water quality diagnosis control.

Embodiment 4 In this embodiment, a micro-platinum electrode 5 as a sensor for dissolved oxygen, hydrogen and hydrogen peroxide as shown in FIG.
0 and the internal reference electrode shown in FIGS. 2 and 6 were integrated. FIG. 8 shows the concentration of dissolved oxygen in the periphery of the core measured using a micro platinum electrode by electrochemical measurement as a dissolved oxygen meter, and also shows the change over time of the corrosion potential of the material in the furnace. By injecting hydrogen gas by the gas injection system 8 in about 11 months, the dissolved oxygen concentration decreases, the corrosion potential decreases, and it can be seen that sufficient water quality diagnostic control is performed. In this example and the next example, a plurality of types of voltammetry were used, but the method of analyzing dissolved hydrogen, oxygen and hydrogen peroxide in the furnace is as follows.

In the present embodiment, as a plurality of types of voltammetry, normal pulse voltammetry and reverse pulse voltammetry are used to separate and determine dissolved hydrogen, dissolved oxygen, and dissolved hydrogen peroxide. When the internal reference electrode (ECP sensor) of the present invention shown in FIG. 2 or FIG. 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 current for oxidation and reduction of a solution containing O and DH ₂ O ₂ can be given by the following equation for each mode of normal pulse voltammetry and reverse pulse voltammetry.

[0109]

(Equation 1)

[0110]

(Equation 2)

[0111]

(Equation 3)

[0112]

(Equation 4)

Here, the equations (Equation 1) and (Equation 2) respectively represent H ₂ O ₂ and O ₂ in normal pulse voltammetry.
, The total diffusion limiting current of the oxidation reaction of H ₂ O ₂ , H ₂ , and the equations (3) and (4) are respectively H ₂ O ₂ , O ₂ in reverse pulse voltammetry.
It represents the total diffusion limiting current of the oxidation reaction and the total diffusion limiting 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. . In Expressions (Formula 3) and Expression (Formula 4), τ is a so-called generation time, which is a holding time of the initially set potential of the reverse pulse voltammetry. Equation (5) shows that t _p and τ are 60 at a radius r = 50 μM of the microelectrode.
This is a valid expression up to about 0 ms.

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

[0117]

S = 4nFD _j rC ⁰ _j (Equation 7) n indicates the total number of reaction electrons of each oxidation-reduction reaction of oxygen, hydrogen, and hydrogen peroxide. F is the Faraday constant, C
⁰ _j indicates the concentration of each chemical species j.

Here, by subtracting the value of equation (1) from equation (4), the following 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) Is determined, and plotted, the equation (Equation 9) is obtained from the linear gradient,
That is, the concentration of hydrogen peroxide can be calculated and obtained.

[0121]

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

[0124]

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

[0125]

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 and can be automatically processed. The measurement results shown in FIG. 8, FIG. 9, and FIG. 10 are displayed using the analysis means shown in this embodiment.

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

Embodiment 5 This embodiment uses the micro platinum electrode in the furnace instrumentation tube 4 as a hydrogen peroxide sensor and uses the internal reference electrode shown in FIGS. 2, 6 and 17 as shown in FIG. The in-situ hydrogen peroxide concentration in the furnace and near the core was measured by the electrochemical measurement system configured as described above. As shown in FIG. 9, when the hydrogen peroxide concentration slightly increases, when hydrogen gas is injected from the injection system 8 under computer control, a clear decrease in the hydrogen peroxide concentration is observed on the display system 7,
Correspondingly, the corrosion potential also tends to slightly decrease. Since hydrogen peroxide cannot be distinguished from dissolved oxygen and hydrogen by ordinary electrochemical analysis, it is separated and quantified by performing a plurality of types of pulse voltammetry and performing arithmetic processing.

Embodiment 6 In this embodiment, a crack sensor is mounted inside the furnace interior gauge 4, and an internal reference electrode (EC) shown in FIG. 2 or FIG.
The relationship between the amount of crack propagation of SUS304 steel in a reactor water environment and its corrosion potential is shown in the display system 7 in combination with a P sensor). As shown in FIG. 11, there is a correlation between the corrosion potential and the amount of crack growth due to SCC, and it can be seen that the growth rate is high when the corrosion potential is high. When hydrogen gas was injected by the gas injection system 8 in about eight months, the amount of crack growth tended to slightly decrease. This shows that sufficient water quality diagnosis control has been executed.

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

In this embodiment, the thickness of the oxide film of the Zr alloy material is monitored by measuring the corrosion potential of a fuel cladding tube made of a Zr alloy. Since the relationship between the corrosion potential of the Zr alloy member and the thickness of the oxide film is input in advance from laboratory data, the oxidation of the cladding tube is performed using the immediate display system 7 based on the measurement result of the corrosion potential based on the reference value. You can know the film thickness. FIG. 13 shows the results.

Embodiment 8 FIG. 14 shows a flow of continuous water quality control for continuously monitoring dissolved oxygen and hydrogen in reactor water by inserting the electrochemical measurement system shown in FIG. 16 into an instrumentation pipe in a nuclear reactor. If the dissolved oxygen concentration in the reactor water exceeds the set reference value, the magnitude relationship between the dissolved oxygen concentration and the set reference value is determined, and if both the dissolved oxygen and dissolved hydrogen concentrations exceed the set values, 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 between the dissolved oxygen and the hydrogen concentration with the set reference value is determined again. In the case of oxygen, hydrogen is set below the set reference value, and in the case of hydrogen, hydrogen is set until the conditions set above the set reference value are 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 structure shown in FIG.
In place of 3, thallium oxide was used. ) Was used.
FIG. 15 shows a processing flow for continuously monitoring the pH of the reactor water and setting the reactor water pH within a predetermined range by injecting a weak acid and a weak alkali. The weak alkali is injected when the pH falls below a predetermined range, and when the pH at which the weak acid is injected exceeds a predetermined range.

Embodiment 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.
Micro platinum wire 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 the reactor water and liquid can enter and exit. By providing this hole, the information of the reactor water can be grasped, and the disturbance of electrochemical analysis, pH measurement and corrosion potential measurement due to convection in the electrochemical cell due to the flow of the reactor water can be minimized and measured. .

Reference numeral 2 denotes a low impedance silver / silver ion reference electrode. Reference numeral 50 denotes a U-shaped working electrode of a platinum wire having a diameter of 20 μm. Reference numeral 54 denotes platinum / thallium oxide (Tl ₂ O ₃ ) in which the electrode potential responds to the hydrogen ion concentration in the reactor water.
1 shows a pH electrode of the type. Reference numeral 51 denotes a counter electrode made of a 50 μm platinum wire. 52 is an aluminum oxide (Al ₂ O ₃ ) tungsten metallized, MI cable (Mineral Insula)
When the core wire of the tor cable 57 is connected to the counter electrode, it is a sealing member for preventing reactor water from entering the ceramic insulator of the MI cable and lowering the insulation resistance between the cable sheath and the core wire. The working electrode portion 52 of the working electrode 50 has exactly the same function. 56 is a welded portion.
As can be seen from this figure, the reactor water directly enters the cell container above the electrochemical cell through the hole 55, but the reactor water cannot enter the space shown in the lower portion. .

[0135] The four MI cables in the space are connected to the metal tube 5.
8 and sent from the instrumentation tube to the outside of the reactor.
Is connected to a potentiostat, a function generator or a potentiometer 5, and to a computer by a normal interface technology. Various electrochemical measurements, pulse voltammetry, random pulse voltammetry, etc. can be performed. A lead wire is connected to the structural material electrically short-circuited to the welded portion 56 and the metal tube 58, and the potential difference between the two is measured by an electrometer. Can be measured.

Further, if an electrometer is connected to 2 and 54, the electrode potential of 54 with reference to 2 reference electrodes can be known. Therefore, by measuring the potential difference of 2,54,
H can be measured. The four electrodes 2, 50, 54, and 51 are located close to each other in order to reduce the impedance such as the cell resistance when measuring in high-temperature and high-pressure water with low conductivity and the necessity of mounting in the neutron instrumentation. It is installed in. The inner diameter of the cell in the container 53 filled with reactor water is 20
mm. In order to arrange the four electrodes as close as possible in this cell, the arrangement of the electrodes draws a circle.

FIG. 17 is an enlarged detailed view of the reference electrode unit 2 shown in FIG. This reference electrode comprises 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 is filled with reactor water that has entered through the micropores 55 (about 0.5 mm in diameter) and stores silver ions eluted from silver. The diffusion speed of silver ions diffusing into the reactor water from the liquid junction hole 55 of the compression molded body 63 varies depending on the molding pressure of the molded body. Adjust the molding pressure to increase the dissolution rate to 10 ^-12 mol
/ Cm ² · s or less.

21 is a silver / silver ion electrode sheath, 61 is a seal made of tungsten metallization 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
It is the sheath of the cable and is made of the same SUS304 as the core wire. Reference numeral 62 denotes an adapter for connecting the MI cable and the electrode unit.

Example 11 This example uses the electrochemical sensor shown in FIG.
This sensor is installed in place of the ECP sensor 2 of FIG. 1, and the dissolved oxygen, hydrogen peroxide, hydrogen concentration formulas (Formula 12), Formula (Formula 9), Formulas are applied by applying random pulse voltammentary and neural networks. (Equation 11)
Are analyzed simultaneously and quantitatively.

The random pulse voltammetry is a voltammetry using a pattern recognition method. In the voltammetry using both the normal pulse and the reverse pulse shown in the fourth embodiment, the quantification of each chemical species concentration depends on one-dimensional information called a 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 shaking the analyzed system in various ways using a more complex disturbance signal (random pulse potential signal). Tried that. That is, even when the potentials of the reactions are close to each other and separation and quantification is difficult as in the above-mentioned chemical species, the difference in the speed and parameters of the electron transfer reaction among the electrochemical reaction processes of each substance to be measured. Focusing on the characteristic pattern (feature vector) in the data matrix obtained by the data compression processing shown below, quantitative analysis from the size of the feature vector and the calibration curve, and the difference in the appearance pattern of the feature vector appearing in the data matrix Perform qualitative analysis.

The random pulse voltammetry obtains pattern information (electrolysis current data), compresses the pattern information, and extracts the value of the objective information equation (Equation 12), Equation (Equation 9), and Equation (Equation 11) from the compressed pattern information. The procedure is executed as follows. The outline of each step of is as follows. , First, oxygen, hydrogen peroxide,
The hydrogen electrolysis current is measured. In the case of this embodiment, the potential signal of the random pulse has two potential waveform parameters (m,
Described using n). That is, the potential corresponding to the pulse potential of the first random pulse is represented by parameter m, and the potential corresponding to the pulse potential of the second random pulse is represented by parameter n. Therefore, m is taken on the x-axis, n is taken on the y-axis, and the measured data is arranged in the form of a matrix according to the parameter values of the electrolytic current which is a response signal corresponding to the input potential on each (x, y) coordinate. In, the data matrix of the current component, which is the response signal of the input potential signal of 64 (8 × 8) points obtained in, is converted into a data vector having several components and compressed. Data compression methods include Fourier transform, Hadamard transform, Karhunen-Loeve transform, and Haar transform used in the field of image processing. In this embodiment, the two-dimensional Hadamard transform is used. In, a feature vector is extracted from the data vector obtained in, and equations (Equation 12), Equation (Equation 9), and Equation (Equation 11) are determined. That is, each component value of the obtained data vector is used as an input, and a function that outputs each value of dissolved oxygen, hydrogen peroxide, and hydrogen concentration is searched and set. In this embodiment, this function is determined using a neural network. Hereinafter, the details of each step in this embodiment will be described.

First, details of the “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 at random, it may not be possible to obtain information on dissolved oxygen, hydrogen peroxide and hydrogen concentrations. In the present embodiment, focusing on the voltammetry using both the normal pulse and the reverse pulse shown in the embodiment 4 to separate and determine the dissolved oxygen, hydrogen peroxide, and hydrogen concentrations, a random pulse potential based on this pulse applying 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 a region where the potential is positive, and reduction currents of oxygen and hydrogen peroxide are observed in a negative region. The potential regions where the oxidation current and the reduction current are observed are expressed by Expression (Equation 13) and Expression (Equation 14), respectively.
1, 2, 3...) Levels.

[0144]

(Equation 13)

[0145]

[Equation 14]

[0146]

(Equation 15)

The reason why the equation (Equation 15) is adopted is to make it easy to execute processing by a computer.
In the present embodiment, each level is divided into eight (l = 3) levels, and each level is divided into Expression (13) (n) and Expression (14).
(N) (n = 1, 2, 3,... 8). Oxygen,
The potential at which the electrode reaction of hydrogen peroxide and hydrogen does not occur is defined as E _C ,
The potential diffusion limiting current of an oxidation reaction of hydrogen peroxide and hydrogen is obtained and E _1.

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

The first kind of random pulse is given by the following equation (16)
Are applied in this order.

[0150]

(Equation 16)

In this embodiment, E _{C is set} to one second, and the equation (Equation 2)
3), Expression (Equation 24) was set to 0.05 seconds, and the current value was sampled at the end of Expression (Equation 24) (n).
m and n are the divided levels (1
８8). Equation (23) (m) and Equation (24)
There are 64 combinations of potential combinations of (n), 8 × 8 = 64, and m = 8 in the 8 × 8 data matrix equation (Equation 17).
And a current value corresponding to the set of n.

[0152]

[Equation 17]

Since the equation (Equation 17) obtained in this way is composed of current data of the reduction reaction of oxygen and hydrogen peroxide in the test water, the equation (Equation 12) of the equation (Equation 4) of the fourth embodiment is obtained. ),
The information has almost the same quality as the information on the equation (Equation 9). However, Equation (Equation 17) includes 64 points of current data, and thus has a larger amount of information than Equation (Equation 1). Second
The seed random pulses are applied in the order of Expression (Equation 18).

[0154]

(Equation 18)

In this embodiment, E _{C is set} to 1 second, and the equation (Equation 19) and
Equation (Equation 20) is set to 0.05 seconds each,
At the end of the test, the current value was sampled.

[0156]

[Equation 19]

[0157]

(Equation 20)

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

[0159]

(Equation 21)

The third kind of random pulse is given by the following equation (Equation 22).
Are applied in this order. In this embodiment, E _C , the expression (Equation 2)
3), when the same time each expression (number 24) of the first kind random pulse, the E ₁ and 0.1 seconds, the current was sampled value to equation (24) at the end. Also in this case, the first kind,
As in the case of the second type, an 8 × 8 data matrix equation (Equation 26) corresponding to the pair of m and n is obtained. The third kind of random pulse is the first type differs, equation (23), is that E ₁ in front of the equation (24) is sequentially applied.
That is, similar to the equation (Equation 4) of the fourth embodiment, the equation (Equation 25)
The oxygen in the test water, in addition to the information of the reduction reaction of hydrogen peroxide, will include information generated by the oxygen reduction reaction by oxidation of hydrogen peroxide at E _1.

[0161]

(Equation 22)

[0162]

(Equation 23)

[0163]

(Equation 24)

[0164]

(Equation 25)

[0165]

(Equation 26)

Next, the details of the “compression of pattern information” will be described.

Before transforming and compressing a data matrix into a data vector, the matrix is defined by equation (Formula 27).

[0168]

[Equation 27]

By this operation, “information on the reduction reaction of oxygen and hydrogen peroxide in the test water” is almost cancelled.
In the equation (Equation 27), “information on the reduction reaction of oxygen generated by the oxidation of hydrogen peroxide” is concentrated. That is, the equation (Equation 27) is equal to the equation (Equation 8) −Equation (Equation 1) of the fourth embodiment.
Will have almost the same information.

The data matrix expressions (Expression 27), Expression (Expression 17), and Expression (Expression 21) are obtained by using Expression (Expression 2) as matrix expressions (Expression 28), Expression (Expression 29), and Expression (Expression 30), respectively.
Is converted to

[0171]

[Equation 28]

[0172]

(Equation 29)

[0173]

[Equation 30]

[0174]

Y = HXH (Equation 31)

[0175]

(Equation 32)

Is as follows. Each component of the matrix Y is

[0177]

[Equation 33]

In other words, the information of X appears in a specific component among the 64 components of Y. That is, 64 of X
This means that the information dispersed in the number of components is compressed into a specific number of Y components. In the case of this embodiment, y ₁₁ , y ₁₅ ,
The information was compressed into y ₅₁ , y ₁₇ and y ₇₁ components. Here, from the y ₁₁ , y ₁₅ , y ₅₁ , y ₁₇ , and y ₇₁ components of Expression (Expression 28), Expression (Expression 29), and Expression (Expression 30), Expression (Expression 34), Expression (Expression 35), A vector represented by Expression (Formula 36) is created.

[0179]

(Equation 34)

[0180]

(Equation 35)

[0181]

[Equation 36]

[0182]

Z = (y ₁₁ , y ₁₅ , y ₅₁ , y ₁₇ , y ₇₁ ) (Expression 37) From the above description, the vector expression (Expression 34) and the expression (Expression 3)
5) and Expression (Equation 36) include Expression (Equation 9) and Expression (Equation 1), respectively.
2) + Information (Equation 9) and Information on Expression (Equation 9) + Equation (Equation 11) are compressed at high density.

Next, the details of “extraction of target information from compression pattern information” will be described.

A vector equation (Equation 34) obtained with respect to the test water of the arbitrary equations (Equation 12), (Equation 9), and (Equation 11)
Against

[0185]

(38)

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

Equation (Equation 9) Equation (Equation 9) can be obtained by calculating Equation (Equation 6) for unknown test water.

Similarly, an arbitrary expression (Equation 12), an expression (Equation 9),
With respect to Expression (Equation 35) and Expression (Equation 36) obtained in the test water of Expression (Equation 11),

[0189]

[Equation 39]

[0190]

(Equation 40)

The scalar fields g and h that satisfy the conditions are prepared. The scalars g and h are obtained in advance for the test water for which the equations (Equation 9) and the equation (Equation 12) are known or the equations (Equation 9) and the equation (Equation 11) are known. In this embodiment, a neural network that inputs each component of the vector equation (Equation 35) and outputs Equation (Equation 12) + Equation (Equation 9), and an equation that receives each component of the vector equation (Equation 36) as an input (Equation 11) +
The scalar fields g and h were determined using neural networks each outputting the equation (Equation 9). Equations (38), (39), and (40) for the unknown test waters of the equations (12), (9), and (11) are used to obtain the equation (12). , Equation (9), and Equation (11) are obtained.

FIG. 19 shows the amounts of dissolved oxygen, hydrogen peroxide, and hydrogen in the furnace simultaneously determined by the above-described method, and each 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 is understood that the oxygen and hydrogen peroxide concentrations are reduced by hydrogen injection.

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

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

[0195]

[Equation 41]

Here, Z _i (1): the value of the input layer (first layer), W _ij (2 ← 1): the intermediate layer (second layer) from the i-th variable of the input layer (first layer) , C _j (2): the total input value to the j-th neuron element model of the intermediate layer (second layer).

In the neuron element model of the input layer, C
_j The output value here is given by the following equation (Equation 42) according to the price of _j (2).
Is calculated.

[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.
_j Depending on the value of (2), the value between “0” and “1” is Z
_j (2). The calculated value Z _j (2) is further sent to the output layer, and the same calculation is performed in the output layer.

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

The input value Z _j (1) described above 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 product sum C _j (2) of these output values Z _i (1) and the weighting factors W _ij (2 ← 1) is calculated by the equation (Equation 1). The output value Z _j (2) to the output layer is determined by Expression (Equation 2).
Similarly, the output value Z _j (2) of the intermediate layer is further _{calculated by} the weight coefficient W _ij (3 ← 2) between the intermediate layer (second layer) and the output layer (third layer).
The product sum C _j (3) is calculated by the following equation (Equation 43).

[0202]

[Equation 43]

Here, Z _i (2): the value of the intermediate layer (second layer), W _ji (3 ← 2): the output layer (third layer) from the i-th variable of the intermediate layer (second layer) , C _j (3): the sum of the inputs to the j-th neuron element model in the output layer (third layer).

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

[0205]

[Equation 44]

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

In order to execute learning by a neural network, a comparison layer and a teacher signal layer are further provided after the output layer as shown in FIG. 20, and the output layer signal and the teacher signal are input to the comparison layer. Here, the output signal and the teacher signal are compared. The weight coefficient W _ji (3 _{←←) is set} so that this error is reduced.
2) and the size of W _ji (2 ← 1) are corrected.

Using the corrected values, the equations (Equation 1) to (Equation 4) are again calculated and compared with the teacher signal.
Similarly, an error appears. To reduce this error,
The magnitudes of the weight coefficients W _ji (3 ← 2) and W _ji (2 ← 1) are corrected again.

[0209] In this way, the weighting coefficient _Wji is repeatedly corrected, and the correction is continued until the error becomes sufficiently small. Initially, the weighting factor is given randomly (generated by random numbers),
Although the error is large, the output signal gradually approaches the teacher signal. The scalar fields f, g, h are determined in this way. Here, the symbols c and z correspond to the density and the feature vector, respectively.

The method of correcting an error in this way is called an error back propagation method, and utilizes a technique devised by Rumelhart et al. See 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 using a low impedance reference electrode. In addition, the reference electrode structure is protected by a fine porous layer, and the dissolution of reference electrode ions from the reference electrode and reactor water can be set to 10 ^-12 mol / cm ² · s or less by flux. Very long life (0.5 g of silver / silver ion reference electrode with a silver life of 15 years or more) and stable electrochemical analysis. Therefore, the technology developed in the field of electrochemical measurement can be applied to the analysis of water quality in the reactor.
It is possible to accurately analyze the information in the furnace. With this technology, a plant operating state monitoring system using in-situ water quality data can be constructed.

In addition, the reliability of data is increased by applying a water quality sensing technology based on an electrochemical cell structure having a service life longer than the period of regular inspection of a nuclear reactor and a neural network to water quality data, and the reliability of an operation monitoring system is dramatically increased. To increase.

According to the present invention, unlike the electrochemical cell described in JP-A-59-177474, there is no need to use a durable and highly permeable resin-selective membrane, so that the environment of high-temperature and high-pressure water is not required. It can be used for a long time even underneath.

The technique described in JP-A-56-77751 measures the pH of high-temperature water using zirconium oxide or the like as a membrane for a hydrogen ion sensing element.
Since zirconium oxide and the like have an extremely large impedance, there is a problem in practical use. In contrast, according to the present invention, the ionizable electrode material is wrapped in a sheath of porous ceramic or porous heat-resistant plastic, so that an electrochemical cell having an appropriate impedance can be formed, and the output signal processing circuit and the like can be used. 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 the 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 temporal change in corrosion potential of a structural material in a furnace and a hydrogen gas injection effect.

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

FIG. 5 is a graph showing a relationship between a temporal change of pH in a furnace and an alkali injection effect.

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

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

FIG. 8 is a graph showing a relationship between a corrosion potential of a structural material in a furnace, a temporal change of a dissolved oxygen concentration, and a hydrogen gas injection effect.

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

FIG. 10 is a graph showing a relationship between a corrosion potential of a structural material in a furnace, a change with time of a dissolved oxygen, a hydrogen concentration, and a hydrogen peroxide concentration and a chemical injection effect.

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

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

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

FIG. 14 is a flowchart in the plant operation state monitoring system of the present invention.

FIG. 15 is a flowchart in the plant operation 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 sectional view showing details of a ceramics-integrated silver / silver ion reference electrode.

18 (a) is a current (i) -potential (E) curve diagram in a mixed system of three kinds of oxygen, hydrogen peroxide and hydrogen, and FIG. 18 (b).
3 is a graph showing a random pulse signal applied to a working electrode of an 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 ... inside the furnace, 4 ... instrumentation tube inside the furnace, 5 ... potentiostat, electrochemical interface, 6 ...
Computer arithmetic processing automatic control device, 7 remote control command device and analysis result display and 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 Member, 57, 60 ...
MI cable, 58: metal tube, 59, 63: alumina powder insulating layer, 61: alumina cap, 62: joining adapter.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G01N 27/403 G01N 27/30 371H G21D 3/08 27/46 A G21C 17/02 Z (72) Inventor Takuya Takahashi Hitachi, Ibaraki 4026 Kuji-cho, Hitachi, Ltd.Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Masaru Izumaya ▲ Kiyoshi ▼ 4026 Kuji-cho, Hitachi, Ibaraki Prefecture, Hitachi, Ltd. 4026 Hitachi Hitachi, Ltd.Hitachi Research Laboratory (72) Inventor Yoshitaka Kojima 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd.Hitachi Research Laboratory Co., Ltd. Hitachi, Ltd. (72) Inventor Katsumi Osumi 3-1-1, Sachimachi, Hitachi, Ibaraki Pref. Hitachi, Ltd. Tokoro Hitachi Works (72) Inventor Makoto Hayashi 502, Kandate-cho, Tsuchiura-shi, Ibaraki Pref.Hitachi, Ltd.Mechanical Research Laboratory Co., Ltd. Inventor Masaki Suwa 4026 Kuji-cho, Hitachi City, Ibaraki Pref., Hitachi Research Laboratories, Hitachi, Ltd. 4026 Kuji-cho, Hitachi, Hitachi, Ltd.Hitachi, Ltd.Hitachi Research Laboratory, Inc. (72) Inventor Hiroshi Yamauchi 4026 Kuji-cho, Hitachi, Ibaraki, Japan Hitachi, Ltd. 4026 Hitachi, Ltd. Hitachi Research Laboratory (56) References JP-A-63-18259 (JP, A) JP-A-63-26566 (JP, A) JP-A-63-79099 (JP, A) 58-51312 (JP, A) JP-A-60-18359 5 (JP, A) JP-A-59-174748 (JP, A) JP-A-56-77751 (JP, A) U.S. Pat. No. 4,552,718 (US, A) Reference Electrode for PWR, Electric Power Research Institute, Inc. . (1987). Electrochem. SoC. , 132, 1866 (1985). Electrochemical Methods, John Willy & Sons, Inc. (1980), pp. 553-573. Rumelhart et al. , Parallel Distributed Processing, MIT Press, Vol. 1 (1986) (58) Fields investigated (Int. Cl. ⁶ , DB name) G21C 17/02 G21D 3/08 G01N 27/30 G01N 27/27 G01N 27/26 G01N 27/403

Claims (10)

(57) [Claims] 1. A means for continuously extracting information directly related to high-temperature water in a target portion by an electrochemical water quality sensor installed in a monitoring target portion of a plant for a predetermined period, and based on the extracted information. Means for evaluating 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 electrolyte layer, an electrode material electrochemically contacting the electrolyte layer, and a terminal electrically connected to the electrode material. A plant operation state monitoring system, which is an electrochemical reference electrode or a pH electrode provided with: 2. A means for extracting the plant monitored portion electrochemical water sensor placed in continuously during until the next inspection information directly related to high-temperature water of the target portion from the inspection of the plant, Means for evaluating water quality based on the extracted information, means for comparing the obtained water quality evaluation result with a predetermined reference value for plant operation,
Means for displaying and recording a necessary part of the comparison result, wherein the water quality sensor includes a solid electrolyte layer containing ions of an electrode material, a porous ceramic layer surrounding the solid electrolyte layer,
An electrode material that is 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 operation state monitoring system, which is a reference electrode or a pH electrode. 3. A water quality sensor installed in a monitoring target portion of a plant, wherein the high-temperature water and the electrolyte of the monitoring target portion electrochemically contact with each other via a porous material, directly to the quality of the high-temperature water of the target portion. Means for continuously extracting related information for a certain period of time, means for analyzing water quality based on the extracted information, and comparing the obtained water quality analysis result with a predetermined reference value for plant operation. And a means for displaying or recording a necessary part of the comparison result. 4. A high-temperature water and an electrolyte in the monitoring target portion of the plant are electrochemically contacted with each other through a porous material which substantially suppresses dissolution of the electrolyte in the high-temperature water. Means for extracting information directly related to the quality of the high-temperature water of the target part by means of a water quality sensor arranged at a predetermined position, means for analyzing the water quality based on the extracted information, and the obtained water quality analysis result and a predetermined value. A plant operation state monitoring system, comprising: means for comparing a reference value of the plant operation operation obtained; and means for displaying and / or recording a necessary part of the comparison result. 5. A means for continuously extracting data on water quality of a circulating water system or a storage water system from an inspection of a plant to a next inspection by an electrochemical sensor installed in a monitoring target portion of a plant containing high-temperature water; A means for comparing the extracted data with a predetermined reference value of the plant operation, a means for predicting a change in the reference value based on a correlation between the plant operation reference and the data, plant OPERATION condition monitoring system, characterized by comprising means for comparing the variation with a said data, and means for controlling the water quality. 6. A means for continuously analyzing the water quality of a circulating water system or a storage water system from a periodic inspection of a plant to a next inspection by an electrochemical sensor installed in a monitoring target portion of the plant containing high-temperature water, and Means for displaying the analysis results;
Means for selecting a predetermined plant operation reference value corresponding to the water quality analysis result, and means for predicting a change amount of the reference value based on a correlation between the analysis result and the plant operation reference value , plant OPERATION condition monitoring system, characterized by comprising means for controlling the water quality. 7. A circulating water system or a storage water system is continuously analyzed for water quality of a circulating water system or a storage water system from a periodic inspection to a next inspection of the plant by an electrochemical sensor installed in a monitoring target portion of the plant containing high-temperature water, and at least pH, Means for outputting data relating to the 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 means for predicting a variation of the reference value based on the correlation between plant driving operation reference value, means for controlling the water quality
Plant OPERATION condition monitoring system, characterized by comprising and. 8. The sensor, claims 1 comprises a ceramic or a resin layer having fine pores to coat the solid electrolyte or electrode material formed on the electrode of the support base 7
Plant luck rolling condition monitoring system according to any one of the. 9. The sensor is a dissolved hydrogen sensor (D)
H), dissolved oxygen sensor (DO), hydrogen ion concentration sensor
Sir (pH), the reference electrode or ECP detection electrode (EC
P), solution conductivity sensor (S), dissolved hydrogen peroxide Sen
Sir (DH ₂ O ₂₎ One 及 beauty crack sensor (M) hereinafter
The plan according to any one of claims 1 to 8 , which has a top.
Door luck rolling condition monitoring system. 10. At least three months during the operation of the reactor, water quality information on the high temperature water is obtained by an electrochemical water quality sensor installed in a neutron instrumentation tube exposed to the high temperature water in the reactor and at a fuel loading portion. An operating state monitoring system for a nuclear power plant, comprising: means for continuously extracting the water quality information; and means for continuously recording and displaying the obtained water quality information for the at least three months.