JPS59133493A - Jet pump monitoring device of bwr type reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a jet pump monitoring device 62 for a boiling water nuclear reactor (hereinafter abbreviated as BWR).

[Technical background of the invention and its problems] A jet pump that controls the recirculation flow rate and controls the output of the BWH is an extremely important device for the operation of the BWH. Therefore, the occurrence of the cavitation phenomenon in the jet pump 1' causes damage to the jet pump, and this damage to the jet pump may lead to a BWH accident. However, in reality, it is difficult to detect the occurrence of cavitation phenomenon (high-temperature cavitation) under high-temperature conditions such as in a BWR plant in operation.

As a device for monitoring the cavitation phenomenon of a jet pump in an operating BWR plant C2, as a prior art of the present invention, a jet pump cavitation phenomenon is detected based on the DC value (average value) of the jet pump differential pressure signal, which is an existing signal of the BWR plant. A jet pump monitoring device has been proposed that determines the flow rate and detects the cavitation phenomenon from changes in its distribution. but.

The prior art jet pump monitoring device detects a change when the cavitation phenomenon has progressed to a certain extent in the jet pump C2, which has severe operating conditions, and has affected the jet pump efficiency. This means that the sensitivity is poor in terms of early detection of cavitation phenomena.

[Object of the Invention] The present invention was made in view of the above-mentioned circumstances, and its purpose is to prevent the occurrence of the cavity East John phenomenon in a certain jet pump when the operating conditions of the BWH are changed. WR's jet pump monitoring equipment is provided so that it can be detected at its early symptomatic stage.

[Summary of the Invention] First, the cavitation occurrence phenomenon ζ in the jet pump of the present invention will be explained.

From the test data on the actual machine, the following changes are observed in the differential pressure signal at the inlet and outlet of the jet pump due to the occurrence of cavitation in the jet pump. That is, s (i), increase in nozzle level in the high frequency range of 1 to 2 Hz or higher + (2') b 1 to 2 [(rtJl
Changes such as a decrease in the nozzle level in the low frequency range and (8) a decrease in the DC value (average value) are observed.

By the way, the above-mentioned change is considered to be caused by the progression of phenomena as shown below. That is, jet pump 1
When cavitation occurs (1), bubbles are generated due to this cavitation, and high frequency noise increases with the generation of bubbles. Sara I: (2)
s The flow rate decreases due to an increase in the number of bubbles generated (the second is an increase in fluid resistance), and the decrease in the flow rate is due to a decrease in low frequency noise and a decrease in the DC value (average value) (the second is a decrease in the flow rate). Conceivable.

In the present invention, high frequency noise and low frequency noise are evaluated based on the above-mentioned finding 1. For this reason, the standard deviation value of the high frequency component (hereinafter referred to as high range RMB value) and the standard deviation value of the low frequency component (hereinafter referred to as low range RMS value) are used as parameters. It can be obtained from C2 by integrating the self-power spectral density of the signal over the required frequency band, or by dividing the analog signal into two required bands C using a bandpass filter≦2 and calculating the standard deviation thereof.

In fact, it is possible to increase the detection sensitivity by using a combination of the above-mentioned parameters when monitoring a jet pump in a BWR plant. As jet pump differential pressure fluctuation components when cavitation occurs, the spatial distribution trends of low-range RMs@, high-range RMe values, and RMS ratio (taken on the vertical axis) are plotted for each jet pump (horizontal axis -
2), a spatial distribution pattern similar to the one shown in Figure 1 (C) is obtained. The present invention monitors changes in this spatial distribution pattern. Figure 1 A, B, and O are the low range RMS value, high range RMS value, and RMB ratio, respectively.
L■ and ■respectively indicate the jet pump differential pressure signals during normal operation, when cavitation occurs, and when cavitation occurs. As is clear from Fig. 1, when looking at the differential pressure signals of individual jet pumps, the RMS ratio is the most sensitive among the three parameters of low-range RMB value, high-range RMB value, and FjMS ratio, and the jet pump C2 is suitable for detecting signs of cavitation occurrence and detection of cavitation occurrence. Furthermore, according to the experimental results, even if the NRMEI ratio is used as a parameter, the same tendency as in the case of 1M day ratio is shown, so even if this NRMB ratio is used, it is possible to detect the cavitation phenomenon of a jet pump. .

[Embodiment of the Invention] A BWH jet pump has a pair of 42 semi-circular headers concentric with the reactor core, which are attached via live tubes, and each header has an independent structure at its circumferential center. It is connected to a recirculation bong 7.

FIG. 2 is a block diagram of a pull pull system according to an embodiment of the present invention. The data is inputted to the data processing device @3 via the human power device 2. The data processing device 3 (2) calculates the 1MS ratio, and the calculation result (2) determines which pattern 1 of l-l11 in FIG. Discern.

If the determination result is found to be abnormal, it is displayed on the display device 5.

In addition, by using a parameter called 1MS ratio or NRMEI ratio, it is possible to distinguish between the phenomenon of increase in nozzle level due to an increase in DC value and the change in nozzle level due to cavitation phenomenon, and to selectively detect 1'''-cavity. tion phenomena can be monitored.

Furthermore, since both the N1MS ratio and the 1MS ratio are standardized parameters, comparisons between different operating conditions are easy, and they are suitable for monitoring cavitation phenomena.

[Effects of the Invention] According to the present invention, the occurrence of the cavitation phenomenon in the jet pump can be detected during its symptom period and the operator's attention can be called for, thereby making it possible to prevent damage to the jet pump. In addition, fluctuation components of the jet pump differential pressure signal (
This will greatly contribute to the safe operation of nuclear reactors, as it will be possible to detect even when an abnormality occurs, which will be of great help in investigating the cause of the abnormality.

[Brief explanation of the drawing]

Figure 1 A, B, jet pump differential pressure fluctuation components when cavitation occurs, that is, low range RMS value, high range RM value
Diagram explaining the transition of spatial distribution of S value and 1MS ratio, 2nd
The figure is a block diagram of one embodiment of the present invention. 1...Plant 2...Data input device 3.
...Data processing device 4...Discrimination device 5...Display device Agent Patent attorney Yoshiaki Inomata (and one other person) Figure 2 procedural amendment (voluntary) 1. Patent application for indication of the case 1986-6654 No. 2, Name of Invention Jet Pump Monitoring Device for Boiling Water Reactor 3, Relationship with the Amendment Case Patent Applicant (307) Tokyo Shibaura Electric Co., Ltd. 4, Agent 1-chome Toranomon, Minato-ku, Tokyo 105 No. 9-10, Minatodensetsu Building Inomata Patent Office 1, Detailed Description of the Invention in the Specification Column 6, Contents of Amendment 1, Page 4 Line 4 of the Specification, Line 5 of the Same Page, Page 7 Line 12 line, change “nozzle level” in line 13 of the same page to “noise level”
Correct. that's all

Claims (2)

[Claims] (1) A detection device that detects fluctuations in the differential pressure signal between the inlet and outlet of each jet pump, a data input device that sequentially inputs the output from this detection device, and data I output from this data input device: A boiling water system comprising: a data processing device that calculates standardized parameters based on the data and creates a spatial distribution thereof; a display device that displays the discrimination results of the data device; and the discriminator. jet pump monitoring equipment for type nuclear reactors. (2) The standardized parameter is the RMS ratio, that is, (standard deviation value of high frequency component) / (standard deviation value of low frequency component)
or the NRM S ratio, that is, (standard deviation value of high frequency component)/(DC value).