JP5322742B2 - Reactor vibration monitoring method and reactor vibration monitoring system - Google Patents

Description

  The present invention relates to a reactor vibration monitoring method and a reactor vibration monitoring system, and in particular, vibration behavior of a structure such as a fuel assembly or a control rod guide tube provided in the reactor pressure vessel from the outside of the reactor pressure vessel. Related to monitoring technology.

  Conventionally, as a technology for monitoring the vibration behavior of a nuclear reactor structure, an acoustic sensor or acceleration sensor is directly attached to the target structure to be monitored, and the vibration frequency and amplitude of the structure are detected to predict the vibration displacement of the structure. Is known (see Patent Document 1).

  However, the conventional reactor vibration monitoring technology predicts the vibration displacement based on the indirect amount related to the vibration displacement of the structure such as the acoustic amplitude and vibration acceleration of the structure. For this reason, the prediction accuracy is inferior to that for directly predicting the vibration displacement of the structure. In addition, in the case of monitoring the vibration behavior of the structure provided in the reactor pressure vessel, it is difficult to apply the conventional reactor vibration monitoring technique. For example, the acoustic sensor and the acceleration sensor are not attached to the monitoring target, or there are various adverse effects such as instability of reactor power control.

  Therefore, there has been proposed a reactor vibration monitoring technique in which an ultrasonic displacement sensor is provided outside the reactor pressure vessel to directly detect the vibration displacement of the structure provided in the reactor pressure vessel (Patent Document). 2).

JP 2004-53383 A JP 11-125688 A

  In the reactor vibration monitoring technology using ultrasonic displacement sensors, in addition to being able to monitor the vibration behavior of the structure provided in the reactor pressure vessel, the vibration displacement is directly detected, so the predicted accuracy of the vibration displacement is also improved. high. However, when an ultrasonic displacement sensor is used, the prediction accuracy of the vibration displacement of the structure depends on the traveling direction of the transmitted wave and the reflected wave to the structure. For this reason, the predicted reliability of the vibration displacement is likely to be impaired along with the temporal change of the position of the ultrasonic displacement sensor and the traveling direction of the ultrasonic wave.

  The present invention has been made in view of the above circumstances, and in predicting the vibration displacement of the structure provided in the reactor pressure vessel, the prediction accuracy is as high as that in the case of directly detecting the vibration displacement of the structure. It is an object of the present invention to provide a reactor vibration monitoring method and a reactor vibration monitoring system that can reduce a decrease in the prediction accuracy over time.

  In order to achieve the above-described object, in the reactor vibration monitoring method according to the present invention, the vibration behavior of a structure such as a fuel assembly or a control rod guide tube provided in the reactor pressure vessel is measured from the outside of the reactor pressure vessel. In the reactor vibration monitoring method to be monitored, a correlation that correlates the vibration displacement of the structure and the vibration characteristic of the reactor pressure vessel is prepared, and the obtained vibration characteristic of the reactor pressure vessel is collated with the correlation. Thus, the vibration displacement of the structure is predicted, and when the vibration displacement exceeds a limit value permitted for plant maintenance, abnormality notification of the reactor pressure vessel is performed.

  In the reactor vibration monitoring system according to the present invention, the reactor vibration monitoring system monitors the vibration behavior of a structure such as a fuel assembly or a control rod guide tube provided in the reactor pressure vessel from the outside of the reactor pressure vessel. In the system, a displacement sensitive sensor for detecting vibration displacement of the structure, a vibration sensitive sensor for detecting vibration characteristics of a reactor pressure vessel, a vibration displacement of the structure detected by the displacement sensitive sensor, and the vibration sensitive sensor The vibration characteristics of the reactor pressure vessel detected by the correlation are recorded in correlation, and the vibration characteristics of the reactor pressure vessel detected by the vibration sensitive sensor are collated with the correlation to predict the vibration displacement of the structure. , An abnormality detection device that generates an abnormal signal when the predicted vibration displacement exceeds a limit value permitted for plant maintenance, and an abnormal signal generated from the abnormality detection device Receiving an input, characterized in that it and a warning device for informing the abnormality of the reactor pressure vessel.

  According to the present invention, in predicting the vibration displacement of the structure provided in the reactor pressure vessel, the prediction accuracy is as high as when the vibration displacement of the structure is directly detected, and the prediction accuracy decreases with time. Can be reduced.

The figure which shows 1st Embodiment of a nuclear reactor vibration monitoring system. It is a figure which shows arrangement | positioning of the sensor group of a nuclear reactor vibration monitoring system, (a) is XX sectional drawing of FIG. 1, (b) is YY sectional drawing of FIG. The figure which shows the correlation with the displacement of the structure provided in a reactor pressure vessel, and the acoustic amplitude in a reactor pressure vessel. The figure which shows the production | generation timing of the abnormal signal in a nuclear reactor vibration monitoring system. The flowchart which shows the flow of the abnormality detection process performed with the abnormality detection apparatus of a reactor vibration monitoring system. The 2nd Embodiment of a nuclear reactor vibration monitoring system is a figure showing the natural frequency of a structure element recorded on a natural frequency database. It is explanatory drawing of the calculation process of the natural acoustic frequency of the structure element performed in the abnormality detection device of the reactor vibration monitoring system, (a) is a diagram showing the acoustic frequency of the reactor pressure vessel, (b) is the structure The figure which shows the natural acoustic frequency of an element. The figure which shows the production | generation timing of the abnormal signal by the difference judgment of the vibration displacement of a structure element. The figure which shows the production | generation timing of the abnormal signal by the dominant vibration displacement of a structure element. The figure which shows an example of the correspondence of the natural acoustic frequency of a structure body element, and an abnormal phenomenon. The figure which shows an example of abnormality alert | report. The flowchart which shows the flow of the abnormality detection process performed with a reactor vibration monitoring system.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode of the present invention will be described based on a reactor vibration monitoring system shown in the attached drawings. Note that. This reactor vibration monitoring system is an application example of the reactor vibration monitoring method according to the present invention.

[First embodiment]
FIG. 1 is a diagram showing a first embodiment of a reactor vibration monitoring system.

  The nuclear reactor vibration monitoring system 10 includes a sensor group (11, 12, 13), an abnormality detection device 14, and a warning device 15. The reactor vibration monitoring system 10 is provided outside the reactor pressure vessel 21 and monitors the vibration behavior of a structure including a fuel assembly 22 and a control rod guide tube 23 provided in the reactor pressure vessel 21. To do.

  The sensor group of the nuclear reactor vibration monitoring system 10 includes an ultrasonic displacement sensor 11 as a displacement sensitive sensor, an acoustic sensor 12 as a vibration sensitive sensor, and an acceleration sensor 13 as a vibration sensitive sensor. The ultrasonic displacement sensor 11 transmits an ultrasonic wave toward the structure provided in the reactor pressure vessel 21 to receive a reflected wave, and the distance or vibration of the structure from the time required for the transmission to reception. Detect displacement directly. The acoustic sensor 12 detects the acoustic amplitude and acoustic frequency of the reactor pressure vessel 21 in which the sound wave emitted from the structure propagates and vibrates. The acceleration sensor 13 detects the vibration acceleration and the vibration acceleration frequency of the reactor pressure vessel 21 that vibrates as the vibration of the structure propagates.

  FIG. 2 is a diagram illustrating an arrangement example of the sensor group of the nuclear reactor vibration monitoring system, where (a) is a cross-sectional view taken along the line XX in FIG.

  As shown in FIG. 2A, the reactor vibration monitoring system 10 has one ultrasonic displacement sensor 11, and includes a plurality of acoustic sensors 12 and acceleration sensors 13 along the circumferential direction of the reactor pressure vessel 21. Have. Further, as shown in FIG. 2B, at least the acoustic sensor 12 and the acceleration sensor 13 are provided so as to overlap each other when viewed from the axial direction of the reactor pressure vessel 21. However, the arrangement of the sensors is not particularly limited, and is set in consideration of the prediction accuracy of the vibration displacement of the structure.

  The abnormality detection device 14 of the reactor vibration monitoring system 10 firstly includes the vibration displacement of the structure detected by the ultrasonic displacement sensor 11 and the vibration characteristics of the reactor pressure vessel 21 detected by the acoustic sensor 12, that is, the sound. Correlate the amplitude and record the correlation in the internal displacement limit value database. It is preferable to detect the vibration displacement and the acoustic amplitude used for the correlation in a normal time when no large vibration such as an earthquake occurs. This is because the vibration displacement is measured by the ultrasonic displacement sensor 11, and the ultrasonic displacement sensor 11 is liable to deteriorate the detection accuracy of the vibration displacement due to a displacement due to vibration.

  FIG. 3 shows an example of the correlation between the vibration displacement of the structure provided in the reactor pressure vessel 21 and the acoustic amplitude of the reactor pressure vessel 21. The correlation shown in FIG. 3 indicates that when the vibration displacement σ1 of the structure is detected by the ultrasonic displacement sensor 11, the acoustic amplitude S1 in the reactor pressure vessel 21 is detected. The correlation between the structural displacements σ2 to σn and the acoustic amplitudes S2 to Sn of the reactor pressure vessel 21 has the same meaning.

  Secondly, the abnormality detection device 14 of the reactor vibration monitoring system 10 predicts the vibration displacement of the structure by comparing the acoustic amplitude of the reactor pressure vessel 21 detected by the acoustic sensor 12 with the above-described correlation. An abnormal signal is generated when the predicted vibration displacement exceeds a limit value permitted for plant maintenance. The limit value is set in consideration of the prediction accuracy of the vibration displacement of the structure, and is recorded in a displacement limit value database provided inside the abnormality detection device 14. The abnormal signal is generated at a timing when the vibration displacement of the structure exceeds a preset limit value. FIG. 4 shows an example of the generation timing of the abnormality signal in the abnormality detection device 14 of the nuclear reactor vibration monitoring system 10.

  Similarly, the abnormality detection device 14 of the reactor vibration monitoring system 10 includes the vibration displacement of the structure detected by the ultrasonic displacement sensor 11 and the vibration characteristics of the reactor pressure vessel 21 detected by the acceleration sensor 13, that is, vibration. Record the correlation with acceleration. Next, the vibration displacement of the structure is predicted by comparing the vibration acceleration of the reactor pressure vessel 21 detected by the acceleration sensor 13 with the correlation. An abnormal signal is generated when the predicted vibration displacement exceeds a limit value permitted for plant maintenance. Further, the correlation between the vibration displacement of the structure and the vibration acceleration of the reactor pressure vessel 21 is performed in the same manner as the correlation between the vibration displacement of the structure and the acoustic amplitude of the reactor pressure vessel 21.

  The warning device 15 of the nuclear reactor vibration monitoring system 10 receives the input of the abnormality signal generated from the abnormality detection device 14, and displays the abnormality on the display device to notify it.

  Next, the operation of the reactor vibration monitoring system 10 will be described.

  FIG. 5 is a flowchart showing the flow of abnormality detection processing executed in the reactor vibration monitoring system 10. Hereinafter, each step of the abnormality detection process will be described.

  In step S101, when abnormal vibration occurs in the reactor pressure vessel 21 due to an earthquake or the like during operation of the nuclear power plant 20, the vibration characteristics of the reactor pressure vessel are detected. That is, the acoustic amplitude of the reactor pressure vessel 21 is detected by the acoustic sensor 12, and at the same time, the vibration acceleration of the reactor pressure vessel 21 is detected by the acceleration sensor 13.

  In step S102, the acoustic amplitude and vibration acceleration detected in step S101 are temporarily recorded in the internal recording unit. Then, the temporarily recorded acoustic amplitude is compared with the correlation between the vibration displacement of the structure already recorded in the internal recording unit and the acoustic amplitude of the reactor pressure vessel 21, and the acoustic amplitude detected in step S101 is checked. Therefore, the vibration displacement of the structure is predicted. At the same time, the primary recorded vibration acceleration, the already recorded vibration displacement of the structure and the vibration acceleration of the reactor pressure vessel 21 are collated, and the vibration displacement of the structure is predicted from the vibration acceleration detected in step S101. The

  In step S103, the structure displacement limit value database is referred to and it is determined whether the vibration displacement of the structure is equal to or less than the limit value allowed for plant maintenance (Yes / No).

  Step S104 is a step performed when <Yes> is determined in step S3. In step S4, the vibration displacement of the structure predicted in step S2 is recorded in the internal recording unit of the abnormality detection device 15.

  Step S5 is a step performed when <No> is determined in step S3. In step S5, the abnormality of the reactor pressure vessel 21 is notified.

  Next, the operation of the reactor vibration monitoring system 10 will be described.

  In the reactor vibration monitoring system 10, for example, when the vibration displacement of the structure detected by the ultrasonic displacement sensor 11 is σ1, the correlation that the acoustic amplitude of the reactor pressure vessel 21 is S1 is performed and recorded. The When the acoustic amplitude and vibration acceleration of the reactor pressure vessel 21 detected by the acoustic sensor 12 and the acceleration sensor 13 are received, the received acoustic amplitude and vibration acceleration are collated with the recorded correlation. Thus, the vibration displacement of the structure is predicted. That is, the vibration displacement of the structure is predicted based on the acoustic amplitude and vibration acceleration detected by the acoustic sensor 12 and the acceleration sensor 13 that do not require precise positioning compared to the ultrasonic displacement sensor 11. For this reason, in the reactor vibration monitoring system 10, even if a large shake such as an earthquake occurs, the accuracy of predicting the vibration displacement of the structure is unlikely to decrease. The acoustic amplitude and the vibration acceleration are associated with a vibration displacement with high prediction accuracy detected in advance by the ultrasonic displacement sensor 11. For this reason, in the reactor vibration monitoring system 10, the prediction accuracy of the vibration displacement of the structure due to the acoustic amplitude and vibration acceleration is as high as that predicted using the ultrasonic displacement sensor 11.

Therefore, according to the reactor vibration monitoring system 10,
(1) In predicting the vibration displacement of the structure provided in the reactor pressure vessel, it has high prediction accuracy equivalent to the case of directly detecting the vibration displacement of the structure and can reduce the decrease in the prediction accuracy over time .

[Second Embodiment]
2nd Embodiment is an example which changed the function of the abnormality detection apparatus 14 in the reactor vibration monitoring system 10 of 1st Embodiment. In addition, the same structure as 1st Embodiment attaches | subjects the same code | symbol to a corresponding structure, abbreviate | omits description, and the structure which changed the structure of 1st Embodiment or added newly is "A" at the code | symbol end. Will be described.

  The abnormality detection device 14A of the reactor vibration monitoring system 10A includes a natural frequency database including a natural acoustic frequency database and a natural vibration acceleration database. FIG. 6 shows the second embodiment of the reactor vibration monitoring system, and is a diagram showing the natural frequencies of the structural elements recorded in the natural frequency database. What is recorded as the natural frequency is the natural acoustic frequency for each structural element detected by the acoustic sensor 12 and the natural vibration acceleration frequency for each structural element detected by the acceleration sensor 13.

  When the acoustic amplitude is detected by the acoustic sensor 12, the abnormality detection device 14A of the reactor vibration monitoring system 10A decomposes the acoustic frequency of the reactor pressure vessel 21 detected at the same time by frequency analysis (FFT).

  FIG. 7 is an explanatory diagram of a calculation process of the natural acoustic frequency of the structural element performed by the abnormality detection device 14A of the reactor vibration monitoring system 10A, and (a) is a diagram showing the acoustic frequency of the reactor pressure vessel 21. (b) It is a figure which shows the natural acoustic frequency of a structure body element.

  The acoustic frequency of the reactor pressure vessel 21 detected by the acoustic sensor 12 changes with time as shown in FIG. The acoustic frequency of the reactor pressure vessel 21 at each time is a superposition of the natural acoustic frequencies of the structural elements provided in the reactor pressure vessel 21. In the abnormality detection device 14A of the reactor vibration monitoring system 10A, a frequency analysis (FFT) process is performed to calculate a specific acoustic frequency of a specific structural element as shown in FIG. 7B.

  Further, the abnormality detection device 14A identifies the structural element by comparing the natural acoustic frequency for each structural element obtained by the frequency analysis with the natural acoustic frequency recorded in the natural frequency database described above. And the prediction of the vibration displacement similar to 1st Embodiment is performed for every identified structural body element.

  Similarly, the abnormality detection device 14A of the reactor vibration monitoring system 10A, when vibration acceleration is detected by the acceleration sensor 13, the vibration acceleration frequency of the reactor pressure vessel 21 detected at the same time is decomposed into components by frequency analysis (FFT). To do. Further, the structural element is identified by collating the natural acoustic frequency for each structural element obtained by frequency analysis with the natural vibration acceleration frequency recorded in the natural frequency database. And the prediction of the vibration displacement similar to 1st Embodiment is performed for every identified structural body element.

  Then, the abnormality detection device 14A generates an abnormality signal when the predicted vibration displacement of the structural element exceeds a limit value allowed for plant maintenance, as in the first embodiment. In this case, the difference between the two vibration displacements of the structural element predicted at different times, for example, at the time of an earthquake and normal times is obtained, and an abnormal signal is generated when the difference exceeds a predetermined value as shown in FIG. You may make it do. FIG. 8 shows an example in which an abnormal signal is generated when the vibration displacement of the structural element is shifted by σ1 compared to the normal state.

  The abnormality detection device 14A has another abnormality signal generation timing. That is, an abnormal signal is generated when the dominant vibration displacement is extracted for each component obtained by frequency analysis of the acoustic frequency or vibration acceleration frequency. 9 shows the generation timing of the abnormal signal due to the dominant vibration displacement of the structure element.

  In addition, the abnormality detection device 14A of the reactor vibration monitoring system 10A is provided in its internal recording section so as to be able to record the correspondence between the natural acoustic frequency and the abnormal phenomenon for each structural element. FIG. 10 shows an example of the correspondence between the natural acoustic frequency and the abnormal phenomenon for each structure element. When detecting the natural acoustic frequency of the structure element, the abnormality detection device 14A specifies the structure element in which the abnormality is detected and the abnormal phenomenon based on this correspondence. The warning device 15A of the nuclear reactor vibration monitoring system 10A receives an input of an abnormality signal from the abnormality detection unit 14A, and notifies the structure element in which the abnormality is detected and the content of the abnormal phenomenon. FIG. 11 shows an example of abnormality notification.

  Next, the operation of the reactor vibration monitoring system 10A will be described.

  FIG. 12 is a flowchart showing a flow of abnormality detection processing executed in the reactor vibration monitoring system 10A. Hereinafter, each step of the abnormality detection process will be described. Note that step S101, step S102, step S104, and step S105 are steps that perform the same processing as step S101, step S102, step S104, and step S105 in FIG.

  In step S201, the acoustic frequency and vibration acceleration frequency of the reactor pressure vessel 21 are subjected to component decomposition, and the natural acoustic frequency and natural vibration acceleration frequency of the structure element are extracted. In step S202, the dominant vibration displacement is extracted for the natural acoustic frequency or the natural vibration acceleration frequency. In step S203, the natural frequency database is referred to, and the structural element corresponding to each natural acoustic frequency or natural vibration acceleration frequency is identified.

  In step S204, the structure displacement limit value database is referred to, and for each structure element identified in step S203, whether or not the vibration displacement is equal to or less than the limit value allowed for plant maintenance (Yes / No). To be judged. If all the vibration displacements of the structure elements are equal to or less than the limit value, the process proceeds to step S104. If the vibration displacements of one or more structure elements exceed the limit value, the process proceeds to step S105. In step S204, it is determined whether or not the dominant vibration displacement is extracted in step S202 (Yes / No). If the dominant vibration displacement is not extracted, the process proceeds to step S104. If the dominant vibration displacement is extracted, the process proceeds to step S5.

Therefore, according to the reactor vibration monitoring system 10A,
(2) The vibration displacement can be predicted for each structural element provided in the reactor pressure vessel 21, and the effect of (1) can be obtained even in the prediction of the vibration displacement of each structural element.

  DESCRIPTION OF SYMBOLS 10,10A ... Reactor vibration monitoring system, 11 ... Ultrasonic sensor, 12 ... Acoustic sensor, 13 ... Acceleration sensor, 14, 14A ... Abnormality detection device, 15 ... Warning device, 20 ... Nuclear power plant, 21 ... Reactor Pressure vessel, 22 ... fuel assembly, 23 ... control rod guide tube.

Claims (11)

In the reactor vibration monitoring method for monitoring the vibration behavior of a structure such as a fuel assembly or a control rod guide tube provided in the reactor pressure vessel from the outside of the reactor pressure vessel,
The vibration displacement of the structure is correlated with the vibration characteristics of the reactor pressure vessel, and the vibration displacement of the structure is predicted by comparing the obtained vibration characteristics of the reactor pressure vessel with the correlation. A reactor vibration monitoring method comprising: notifying an abnormality of a reactor pressure vessel when the temperature exceeds a limit value allowed for plant maintenance.   The method according to claim 1, wherein an acoustic amplitude is used as a vibration characteristic of the reactor pressure vessel.   2. The reactor vibration monitoring method according to claim 1, wherein vibration acceleration is used as the vibration characteristic of the reactor pressure vessel. Prepare the natural acoustic frequency data for each structural element provided in the reactor pressure vessel,
Acquire the acoustic frequency of the reactor pressure vessel together with the acquisition of the acoustic amplitude of the reactor pressure vessel, and collate the natural acoustic frequency for each structural element obtained by component decomposition of this acoustic frequency with the natural frequency data. The reactor vibration monitoring method according to claim 2, wherein a structural element is identified, and the vibration displacement is predicted for each identified structural element. Prepare natural vibration acceleration frequency data for each structural element provided in the reactor pressure vessel,
Acquire the vibration acceleration frequency of the reactor pressure vessel together with the acquisition of the vibration acceleration of the reactor pressure vessel, and collate the natural vibration acceleration frequency for each structural element obtained by component decomposition of the vibration acceleration frequency with the natural frequency data. The reactor vibration monitoring method according to claim 3, wherein each structural element is identified as a result, and the vibration displacement is predicted for each identified structural element. In the reactor vibration monitoring system that monitors the vibration behavior of structures such as fuel assemblies and control rod guide tubes provided in the reactor pressure vessel from the outside of the reactor pressure vessel,
A displacement sensitive sensor for detecting vibration displacement of the structure;
A vibration sensitive sensor that detects the vibration characteristics of the reactor pressure vessel;
The vibration displacement of the structure detected by the displacement sensitive sensor and the vibration characteristics of the reactor pressure vessel detected by the vibration sensitive sensor are correlated and recorded, and the reactor pressure vessel detected by the vibration sensitive sensor is recorded. An abnormality detection device that predicts vibration displacement of the structure by checking vibration characteristics with the correlation, and generates an abnormality signal when the predicted vibration displacement exceeds a limit value permitted for plant maintenance;
A warning device that receives an input of an abnormality signal generated from the abnormality detection device and notifies an abnormality of a reactor pressure vessel;
A reactor vibration monitoring system comprising:   The reactor vibration monitoring system according to claim 6, wherein an ultrasonic displacement sensor is used as the displacement sensitive sensor.   The reactor vibration monitoring system according to claim 6, wherein an acoustic sensor is used as the vibration sensitive sensor, and an acoustic amplitude of a reactor pressure vessel detected by the acoustic sensor is used as the vibration characteristic.   The reactor vibration monitoring system according to claim 6, wherein an acceleration sensor is used as the vibration sensitive sensor, and a vibration acceleration of a reactor pressure vessel detected by the acceleration sensor is used as the vibration characteristic. The reactor vibration monitoring system includes a natural acoustic frequency database that records a natural acoustic frequency for each structural element provided in the reactor pressure vessel,
When the acoustic amplitude is detected by the acoustic sensor, the anomaly detection device component decomposes the acoustic frequency of the reactor pressure vessel detected at the same time, and calculates the natural acoustic frequency for each structural element obtained by the component decomposition. 9. The nuclear reactor according to claim 8, wherein each structural element is identified by collating with a natural acoustic frequency recorded in a natural frequency database, and the vibration displacement is predicted for each identified structural element. Vibration monitoring system. The reactor vibration monitoring system includes a natural vibration acceleration frequency database that records the natural vibration acceleration frequency for each structural element provided in the reactor pressure vessel.
When the vibration acceleration is detected by the acceleration sensor, the abnormality detection device decomposes the vibration acceleration frequency of the reactor pressure vessel detected at the same time, and the natural vibration acceleration frequency for each structure element obtained by the component decomposition. 10. Each structural element is identified by collating the natural vibration acceleration frequency recorded in the natural frequency database, and the vibration displacement is predicted for each identified structural element. Nuclear reactor vibration monitoring system.

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