JPH02222882A - Monitoring of nuclear power plant - Google Patents

Abstract

PURPOSE:To prevent frequent occurrence of abnormality determination by a method wherein, when a threshold value is once exceeded, the frequency of the threshold value being exceeded is monitored to use the frequency as an information for setting another threshold value and the threshold value for monitoring an abnormal phenomenon is updated temporarily in an automatic manner. CONSTITUTION:In a data processing element 2, an average value is determined from data inputted from a data input element 1, by using a prescribed formula. A comparing-determining element 3 compares a difference between the average value determined by the processing element 2 and an instantaneous value with a threshold value and determines the same. A storing element 4 stores time-series data before and behind an abnormality when it is detected in the determining element 3. An output element 5 outputs the time-series data stored by the storing element 4, the time-series data counted in the determining element 3 and the number of times of the determined threshold value before updating being exceeded, which is counted in the determining element 3. According to this constitution, the frequent occurrence of abnormality determination and the lowering of detection sensitivity due to excessive raising of the threshold value can be prevented by updating the threshold value automatically, while an optimum threshold value can be set on the basis of the number of times of the threshold value before alteration being exceeded.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention uses various measurement signals in a nuclear power plant to
This article relates to a method for monitoring a nuclear power plant to monitor abnormal phenomena occurring in the plant.

(Prior art) Conventional methods for monitoring abnormal phenomena that occur in plants use thresholds to determine whether the phenomenon is abnormal or normal. Usually, this threshold value is determined based on the Initial settings are made based on design conditions or experiential knowledge, and updated according to subsequent usage results.

In early preventive diagnosis, it is necessary to set a small threshold to detect abnormalities early, but if the threshold is too small, false judgments are likely to occur, causing operational problems. Increasing the threshold value may cause a significant decrease in subsequent detection sensitivity in the event of a temporal change.

Further, if the threshold value is increased in advance to prevent these situations, there are problems such as the original purpose cannot be achieved.

(Issues to be Solved by the Invention) The present invention has been made in view of these points, and its purpose is to provide information necessary for optimal threshold setting;
An object of the present invention is to provide a method for monitoring a nuclear power plant that prevents frequent abnormality determinations due to erroneous determinations.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the method for monitoring a nuclear power plant of the present invention includes: - Once a threshold value is exceeded, the frequency with which the threshold value is exceeded is determined. This feature is characterized in that it is possible to prevent frequent occurrence of abnormality determination by monitoring the information and using it as information for threshold setting, and by automatically temporarily updating the threshold value for monitoring abnormal phenomena.

(Operation) Therefore, according to the nuclear power plant monitoring method of the present invention, it is possible to provide threshold setting information and to perform monitoring that prevents frequent occurrence of determination abnormalities.

(Example) Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention.1 The monitoring device of the present invention includes a data input unit 1 that digitally converts each measurement signal, and a data processing unit that calculates the average value of input data. Comparison and judgment sections 3 and 5 compare the deviation between the average value and the instantaneous value with a threshold value; a data storage section 4 that stores the judgment results; and a data output section 5 that outputs each data.
It is composed of.

The data processing section 2 calculates an average value from the data input by the data input section 1 according to formula (2).

Y(H)=Y(H-11+WTX(X(11) Y(
1-0,) = -Q)22, WT: weighting coefficient Xo): instantaneous value Y,. ): The average value comparison and determination section 3 compares and determines the difference between the average value and the instantaneous value determined by the data processing section 2 with a threshold value.

In other words, if formula (2) is satisfied, it is determined that there is an abnormality.

X(n) Y+n+l>it +++ ■C:
When it is determined that the determination threshold is abnormal, the determination threshold is automatically provisionally updated according to formula 0, and the count of the number of times the pre-update threshold has been exceeded is initialized.

K=0 ε　z　　”　　t　　z ε□=t2I Here.

... (3) ε2 = Judgment threshold before update C: Update coefficient K: Number of times Also, if it has already been judged as abnormal, check whether the judgment threshold before update has been exceeded according to formula (a) If it is exceeded, count the number of times. (The threshold value used here is the value ε□ before updating.) X(It) Ycn+l>t
z ・-C4), then K=+1 Here, if the number of times the threshold was exceeded before the update is not increased for a certain period of time (for example, 1 day), and the threshold according to formula 0 is If no changes have been made to change the value back to its original value,
Following the formula 0, the threshold value is returned to its original value and the number of times K is initialized.

E = ε, /C... ■ Here, K = 0 In the data storage section 4, when an abnormality is detected by the comparison/judgment section 3, the time series data before and after the abnormality is stored. (The threshold value used here is C1 after updating.) The data output unit 5 outputs the time series data stored by the data storage unit 4 and the judgment before updating counted by the comparison judgment unit 3. Outputs the number of times the threshold has been exceeded.

Figure 2 shows an example in which the threshold value according to the present invention is increased twice and then returned to the light value.
After changing the value due to the abnormality that occurred in the abnormality that occurred in and the abnormality that occurred in ■ in the figure, the process of returning to the threshold that was changed in ■ above because no increase in the number of times the threshold was exceeded before the change was observed. It shows.

Since there is no clear setting guideline for the judgment threshold value □, it is given as a design parameter.1 However, according to the present invention, the threshold value is automatically updated, so if a small value is set in advance, it will automatically be set to an appropriate value. Fixed. There is also no clear setting guideline for the update coefficient C, but if it is set to about 2.0, abnormalities can always be monitored using a threshold with a margin of twice that.

Further, it is possible to set a more strict threshold value based on the number of times the determination threshold value before updating is exceeded, which is counted by the comparison determination unit 3.

Note that although the above embodiments are applied to a monitoring method based on a deviation from an average value, the present invention can be similarly applied to other monitoring methods.

〔Effect of the invention〕

As explained above, according to the nuclear power plant monitoring method of the present invention, by automatically updating the threshold value, it is possible to prevent frequent abnormality determinations and a decrease in detection sensitivity due to raising the threshold value too much. , it is possible to set a more optimal threshold based on the number of times the threshold was exceeded before changing, and a highly reliable monitoring method can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing a threshold value changing process according to the present invention. 1...Data input section 2...Data processing section 3...
・Comparison/judgment section 4...Data storage section 5...Data output section Agent Patent attorney Yoshiaki Inomata (and one other person) Fig. 2 Fig. 1

Claims (1)

[Claims] In a nuclear power plant monitoring method that monitors abnormal phenomena that occur in a nuclear power plant, when the abnormal phenomenon is detected, the threshold for monitoring is increased and the occurrence of an abnormal phenomenon that exceeds the threshold before the change. Abnormal phenomena can be monitored using two monitoring modes: frequency monitoring and abnormal phenomenon monitoring using the changed threshold. A method for monitoring a nuclear power plant, characterized in that the value is returned to a value.