JPH0365694A - Diagnosis of water quality in boiling water reactor plant - Google Patents

Abstract

PURPOSE:To intend to supply high quality control informations by evaluating a mass balance of a cooling water flow rate and an electric conductivity, individually to each constituent component of a primary cooling system. CONSTITUTION:A mass balance change of an electric conductivity is calculated and analyzed using measured data of a cooling water flow rate and the conductivity at each measuring point in a primary cooling system of nuclear reactor. Each of an in-leak flow rate of a cooling water (sea water) at a condenser 1, an ion removal rate at a condensate demineralizer 2, a generation rate of impurity ions in a reactor at a nuclear reactor 3, a cooling water in-leak flow rate at a cooler 4 of a reactor water purification system and an ion removal rate at a filter demineralizer 5 for the reactor water purification are simultaneously calculated and analyzed. Measured water quality data are converted and displayed as physical quantities which correlates an extent of a malfunction which is occurring at each constituent component directly to the malfunction itself. In this way, nuclear reactor operators or the like, can easily understand a cause of the malfunction and an extent of the malfunction, much precisely and concretely, and therefore a reliability improvement and the like of an operation management can be well intended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a water quality diagnosis method for early detection of plant operating conditions or malfunctions of component equipment based on water quality fluctuations in a boiling water nuclear power plant.

[Conventional technology]

In current water quality management, the presence or absence of abnormalities is diagnosed by comparing measured water quality data with management standard values set as operational guidelines.

As a more comprehensive method for diagnosing water quality, the presence or absence of anomalies and their causes can be diagnosed by combining trends in water quality changes at each measurement position in the reactor primary cooling system or by analyzing correlations between water quality data. Ru. Specifically, as described in Japanese Unexamined Patent Publication No. 59-60293, the increase/decrease pattern of the ion concentration in water at each sampling position of the reactor primary system is compared with the standard pattern for each abnormal event to determine the abnormality that is occurring. A method for diagnosing is disclosed.

[Problem to be solved by the invention]

However, the measured water quality change is not a physical quantity directly related to the malfunction occurring in the component equipment, but is indirect information attached to it, so the details of the malfunction can be grasped directly and quantitatively. not suitable for

The purpose of the present invention is to collect water quality data of the reactor primary cooling system by -
Evaluate and analyze from the perspective of mass balance within the water cooling system,
By converting and displaying physical quantities directly related to malfunction events specific to each device that makes up the primary cooling system, reactor operators and water quality managers can directly display the details of the malfunction and improve quality control. The goal is to quickly provide high quality management information.

[Means to solve the problem]

The above object is for a nuclear reactor primary cooling system consisting of a nuclear reactor, a condenser, a condensate demineralizer, a reactor water purification cooler, and a filtration demineralizer. Evaluate the mass balance of cooling water flow rate and conductivity for each component of the primary cooling system, convert the amount of change in mass balance into a physical quantity that directly corresponds to a malfunction occurring in the component, and display it. This is achieved by That is, (1) the amount of change in the conductivity mass balance in each condenser chamber is calculated from the measured values of the cooling water amount and conductivity at the upstream and downstream sides of each condenser chamber, and the calculated amount of change is restored. (2) Conductivity mass in each condensate demineralizer tower based on the measured values of cooling water amount and conductivity at the upstream and downstream sides of each condensate demineralizer tower. Calculate the amount of change in the balance, convert the calculated amount of change into the ion removal rate of the condensate demineralizer, and display (3) Water supply flow rate and feed water conductivity to the reactor, reactor water inventory and reactor water conductivity The amount of change in the conductivity mass balance in the furnace is calculated from the measured values of the rate, the processing flow rate of the reactor water purification system, and the treated water conductivity, and the calculated amount of change is converted to the amount of increase in conductivity in the furnace. (4) Calculate the amount of change in the conductivity mass balance in the reactor water purification device cooler from the measured values of the amount of treated water and conductivity at the upstream and downstream sides of the reactor water purification device cooler, and display the calculated amount of change. Converts and displays the in-leak flow rate of cooling water in the reactor water purification system cooler.

(5) Reactor water purification system filtration demineralizer Calculate the amount of change in the conductivity mass balance in winter from the measured values of the amount of cooling water and conductivity at the upstream and downstream sides of each tower, The calculated amount of change is converted into the ion removal rate of the reactor water purification equipment filtration demineralizer and displayed.

[Effect]

The reactor primary cooling system basically forms a closed loop, and if the components in the closed loop are normal, water quality data such as electrical conductivity maintains mathematical mass balance. However, when a malfunction occurs in a component, the mass balance changes (imbalance occurs) due to causes specific to each component. Simultaneously calculate and analyze physical quantities directly related to the defective event. Specifically, by calculating and analyzing mass balance changes in conductivity using the measured data of cooling water flow rate and conductivity at each measurement position in the reactor primary cooling system, ■ In-leak flow rate of seawater (in Japan), ■ Ion removal rate in condensate desalination equipment, ■ Impurity ion generation rate within the reactor in nuclear reactors, ■ In-leak flow rate of cooling water in reactor water purification system coolers, ■ Reactor water purification In the filtration demineralizer, the ion removal rate is calculated and analyzed at the same time.

The measured water quality data is converted and displayed into a physical quantity that directly correlates the degree of malfunction occurring in each component to the malfunction event, allowing reactor operators and water quality managers to identify the cause of water quality fluctuations and the degree of malfunction. It becomes easier to understand more accurately and specifically, and it is possible to simultaneously improve the reliability of operation management and save labor.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

Figure 1 shows an example of the components of the reactor primary system to be diagnosed and their flow. The steam generated in the nuclear reactor and exiting the turbine is recondensed (condensed) using cooling water in the condenser.
Collected at the bottom of the condenser. The lower part of the condenser consists of multiple independent ice chambers (hot wells), and the condensate collected for each water quality joins into one tube and is supplied to the condensate pump. The water at the condensate pump outlet is again branched into multiple streams,
The condensate is supplied to each column of the demineralizer, and impurities in the condensate are removed. Condensation theory The water at the winter outlet of the salt reactor joins into one pipe and is supplied into the reactor via a water pump and a water heater. A portion of the reactor water is supplied to the reactor purification system, where it is immediately quenched by a cooler, and then supplied by pumps to multiple filtration demineralizers to remove impurities in the reactor water. The water at the outlet of the filtration demineralizer merges into one line and is supplied to the water supply line.

Water quality and component equipment management of the primary cooling system is usually performed by comparing measurement data from conductivity meters installed upstream and downstream of each component with operational control standard values. Since the measured conductivity value is related to the amount of impurity ions in the primary cooling water, ■ there is no contamination of impurities from sources other than the primary cooling system, and ■ there is no change in the amount of impurities generated within the primary cooling system. , ■ If there is no change in the performance of the demineralizer or filtration demineralizer, the mass balance of conductivity within the primary cooling system will be maintained, and a constant conductivity will be measured at each measurement location.

On the other hand, by analyzing the mass balance change in electrical conductivity within the primary cooling system, it is possible to simultaneously and quantitatively diagnose the occurrence of defects related to the above (1) to 0.

That is, in Fig. 1, the variable X is the conductivity (μS/Ql
), V is the primary system cooling water flow rate (t/h).

A is the cooling water inventory for each room of the condenser hotwell (
t), B is the reactor water inventory (1), L is the in-leak flow rate of cooling water to the primary system (t/h), and the subscript of the variable indicates the location in the primary system. Seawater leak The change over time in the electrical conductivity XA of each chamber of the condenser hotwell when there is Ru.

d x n/ d t = ((xtLn+ x 5-V
ll) x JVn+Ln))/An” (1) The representative conductivity at the condenser outlet (at the condensate pump inlet) is expressed by the following equation as the flow rate average value of the conductivity Xn in each hotwell chamber.

= ΣX, (V, +Ln)/Σ(V, +Ln) −
(2) The electrical conductivity at the outlet of each column of the condensate demineralizer is expressed by the following equation, where η1 is the ion removal rate of the demineralizer.

11'=XO+(1-ηn)・(Ni-N0)...
・(3) Here, Xo: Electrical conductivity of pure water (0,055μ
S/am) to the representative conductivity at the outlet of the condensate demineralizer. is the conductivity of each bath outlet. The average value of is expressed by the following formula.

, ′=Σ, ・Vn′ /ΣV n / ・
...(4) PμS is the increase in conductivity due to the generation of ionic impurities (corrosion products, decomposition products of contaminants) in the furnace.
/ am, the change in reactor water conductivity over time is expressed by the following equation.

d xu/d t=(Vp(ni' -nio) 10Vc(niR' -XO)+P-B-VC(XR-XO))/BR
-(5) Reactor purification system cooler outlet (filtration theory salter inlet)
The electrical conductivity R is expressed by the following equation, where Ll is the in-leakage flow rate of the cooling water, and Ll is the electrical conductivity of the cooling water (1500±500 μS/cm).

XR′ = (to R” VC+ to Lri/(VC+L1
)...(6) The electrical conductivity XR"'n' at each tower outlet of the reactor purification system filtration demineralizer is expressed by the following formula, assuming that the ion removal rate of the filtration demineralizer is η.-0. .

XR-n'= O+ (XR'- o) (1-ηc-n)
(7) The representative conductivity R at the outlet of the filtration demineralizer in the reactor purification system is expressed by the following equation as the average value of R-0 for each bath outlet conductivity.

to R1=Σn−n” Vc−n/ΣVc---(
8) Based on the above equations (1) to (8), by calculating and analyzing the mass balance change of the conductivity measurement value when a failure occurs in the primary cooling system component equipment, as shown below,
It can be converted into a physical quantity directly related to the malfunction event.

■ Conversion to condenser cooling seawater in-leak amount From equation (1), the conductivity of each chamber of the condenser is determined. is n=(Xn(o) −m
/ k) ・e-”+m/k-(9) However,
m=(x訃Ln+xs・Vn)/Ank=(V,+Ln
)/An to n(o): Electrical conductivity of each chamber of the condenser hotwell at t = O. Solving equation (9) for the seawater in-leak flow rate, Ln=(Xn”Vn (Xn(0 )”Vn Xs”
Vn”e-””/^1xs-V-)/xi(1e-”
”/^') ・(10), 1=0 and t
(h) n(o) and the photowell conductivity after elapsed time;
To. Thus, the condenser cooling seawater in-leak amount Ln can be calculated.

■ Conversion to reactor purification system cooling water in-leak amount When equation (6) is solved for cooling water in-leak flow prevention in the reactor purification system cooler, IJ = Vc (xR - XR) / prevention - (1
1), and the in-leak flow rate can be calculated from the difference between the cooler outlet conductivity R and the reactor water conductivity XR.

■ Variables to demineralizer ion removal performance From equation (3), the ion removal rate η at the condensate demineralizer outlet is: η, = 1-(X, -XO)/(X-to o) -( 1
2), which can be calculated from the difference in conductivity of 1 at each bath outlet and inlet.

Similarly, from equation (7), the winter ON removal rate ηC-ゎ of each tower of the JJK child furnace purification system filtration demineralizer is: ηc-n'': 1-(xn-0-go)/(xR'-
go) ...(13), which can be calculated from the difference between R-0 and R' in the conductivity at each bath outlet and inlet.

■ Conversion to the amount of ionic impurities generated in the reactor From (5), the electrical conductivity of the reactor water is n = (xR (o) Q/m) ・e1t + Q/m
-(14) Here, Q=(Cx' -KO) ・V
m=Vc/BR and R(0): reactor water conductivity at t=O. Solving equation (14) for the amount of conductivity increase P in the furnace.

P = (Vc/BR) ・(XR-XR(0) ・e
-("/BR)・')/(1-e""(vc/au),
t) - ((x' - xo) ・VtxR' ・VC/
BR=(15), and from 1=0 and the reactor water conductivity at the time of t (h), R(0) and XR, it is possible to calculate the amount of increase in electrical conductivity in the reactor.

Figure 2 shows the water quality diagnosis flow based on the above mass balance evaluation results.
The data editing function for creating monthly reports is already in use in the actual machine.

New functions added as a result of this mass balance evaluation are displayed in double frames. In other words, ■ Reliability of the conductivity sensor (comparing the calculated value of conductivity based on mass balance evaluation with the measured value) ■ Changes in desalination performance of the desalter over time ■ Cooling in the condenser and reactor purification system cooler In-leak flow rate of water ■ It is possible to continuously quantitatively evaluate the amount of ionic impurities generated by corrosion of structural materials inside the reactor, heat of impurities mixed in the reactor, and radiolysis.

In particular, the evaluation function (■) is a physical quantity that is difficult to measure directly using a specific water quality sensor (the amount of ions generated in the furnace must be measured in consideration of the amount brought in from the water supply system and the concentration and removal within the furnace). This can be achieved through mass balance evaluation.

Figure 3 shows that in Figure 1, water quality data for the primary cooling system is simulated assuming a boiling water nuclear power plant with a 1 million kW class electric outlet, and changes in mass balance of conductivity data are calculated. This figure shows an example of a screen displaying the diagnosis results calculated and analyzed based on the above equations (10) to (15).

The diagnosis results are: - According to the flow of the water cooling system, ■ In-leak flow rate of cooling water in each of the six condenser chambers ■ Reliability of the representative conductivity meter at the condenser outlet (actual measurement of conductivity in each condenser chamber) Calculate the representative conductivity at the outlet from the value (calculated value) and compare it with the measured value) ■ Desalination performance (ion removal rate) of a condensate demineralizer with 10 towers (one tower is a standby) ■ Representative conductivity of feed water Reliability of the conductivity meter (calculate the representative conductivity of the feed water from the actual measured value of the conductivity at the outlet of each column of the condensate demineralizer (calculated value) and compare it with the actual measured value) ■ Reactor purification system filtration desalination with two series (Desalination performance of FD (ion removal rate) ■ Amount of conductivity increase in the reactor (amount of ions generated) ■ In-leak flow rate of cooling water in the reactor purification system cooler All items are displayed simultaneously on one screen do.

(Modified example) In diagnosis based on mass balance changes in conductivity.

Variations in conductivity measurement data (due to measurement and reading errors)
is treated as a true water quality change, leading to misdiagnosis. As a countermeasure, ■ Set a threshold value for the evaluation value shown in Figure 3, and judge only when it exceeds the threshold value as a true water quality change.

■ If the evaluation values shown in Figure 3 show a continuous increase or decrease trend, it is determined that there is a true water quality change.

■ Make a judgment by combining the and ■.

There are possible ways.

For example, as a specific example of Countermeasure (2), in the example of diagnosing the cooling seawater in-leak flow rate in the condenser, a) the condensate conductivity is 0.
．． If the rate increases by 0.01μS/am, the seawater leakage flow rate evaluation value becomes 0.21/h.b) Measurement variation due to conductivity sensor measurement and reading error is ±0.02μ.
S/Ql, so by setting the threshold for determining a true seawater leak as 0.51/h,
Misdiagnosis caused by measurement fluctuations can be reduced.

As a specific example of countermeasure (■), if the amount of conductivity increase in the furnace has increased compared to the time of the previous diagnosis, the number of continuous increases should be displayed in a par chart at the bottom of the evaluation results, as shown in Figure 4. This makes it possible to exclude random increases caused by measurement fluctuations and reduce misdiagnosis.

〔Effect of the invention〕

According to the present invention, measured water quality data is converted and displayed into a physical quantity that directly correlates the degree of malfunction occurring in each component with the malfunction event, so that reactor operators and water quality managers can It becomes easier to more accurately and specifically understand the causes of water quality fluctuations and the extent of problems, and it is possible to simultaneously improve the reliability of operation management and save labor.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of the flow and component equipment of a reactor primary cooling system to which the present invention is applied, Figure 2 is a diagram showing an example of display of water quality diagnosis results to which the present invention is applied, and Figure 3 is a diagram showing an example of the present invention. Figure 4 shows the flow of water quality diagnosis and the diagnostic function realized in
The figure is a diagram showing another display example of water quality diagnosis results to which the present invention is applied.

Claims (1)

[Claims] 1. Nuclear reactor, condenser, condensate demineralizer, reactor water purification cooler,
In the reactor primary cooling system consisting of a filtration demineralizer,
Evaluate the mass balance of cooling water flow rate and conductivity for each component of the primary cooling system, convert the amount of change in mass balance into a physical quantity that directly corresponds to a malfunction occurring in the component, and display it. A water quality diagnosis method for a boiling water nuclear power plant characterized by: 2. Calculate the amount of change in the conductivity mass balance in each condenser room from the measured values of the cooling water amount and conductivity at the upstream and downstream sides of each condenser room, and use the calculated amount of change for condenser cooling. Converts to in-leak flow rate of water,
A method for diagnosing water quality in a boiling water nuclear power plant, characterized by displaying the following: 3. Calculate the amount of change in the conductivity mass balance in each condensate demineralizer tower from the measured values of the cooling water amount and conductivity at the upstream and downstream sides of each condensate demineralizer tower, and calculate the calculated amount of change. A method for diagnosing water quality in a boiling water nuclear power plant, which is characterized by converting and displaying the ion removal rate of a condensate demineralizer. 4. Calculate the amount of change in the conductivity mass balance within the reactor from the measured values of the water supply flow rate and feed water conductivity to the reactor, the reactor water inventory, the reactor water conductivity, and the treated flow rate and treated water conductivity of the reactor water purification system. A method for diagnosing water quality in a boiling water nuclear power plant, which comprises calculating, converting the calculated amount of change into an amount of increase in conductivity within the reactor, and displaying the amount. 5. Calculate the amount of change in the conductivity mass balance in the reactor water purification device cooler from the measured values of the amount of treated water and conductivity at the upstream and downstream sides of the reactor water purification device cooler, and use the calculated amount of change as the A method for diagnosing water quality in a boiling water nuclear power plant, characterized by converting it into an in-leak flow rate of cooling water in a purifier cooler and displaying it. 6. From the measured values of the amount of cooling water and conductivity at the upstream and downstream sides of each tower of the filtration demineralizer in the reactor water purification equipment, determine the amount of change in the mass balance of conductivity in each tower of the filtration demineralizer in the reactor water purification equipment. A method for diagnosing water quality in a boiling water nuclear power plant, characterized in that the calculated amount of change is converted into an ion removal rate of a filtration demineralizer of a reactor water purification device and displayed. 7. A method for diagnosing water quality in a boiling water nuclear power plant, characterized in that the diagnostic results related to items 2 to 6 above are displayed on the same screen. 8. It is characterized by detecting that the conversion amount in the first to seventh terms, calculated from the change amount of the conductivity mass balance, continues to increase or decrease, and determining it as a true malfunction. Water quality diagnosis method for boiling water nuclear power plants. 9. A threshold value is set for the conversion amount in the above-mentioned 1st to 2nd terms, and it is detected that the conversion amount calculated from the amount of change in the conductivity mass balance exceeds the threshold value, and a true malfunction is detected. A water quality diagnosis method for a boiling water nuclear power plant characterized by determining that.