Device and method for monitoring oscillation of nuclear reactor

ES 2 380 478 B2

DESCRIPTION

Vibration monitoring system and method of a nuclear reactor.

Cross references to related requests

This application is based on and claims the priority benefits of the earlier Japanese Patent Application No. 2008-077296, filed with the Japanese Patent Office on March 25, 2008, the full content of which is incorporated by reference herein.

Background of the invention

The present invention relates to a nuclear reactor vibration monitoring system for monitoring the structural integrity of an internal component of the nuclear reactor and its method.

As a technique for checking the structural health of an internal component of a nuclear reactor, a method is known which measures the amplitude of vibrations or the frequency of vibrations of the internal component of the nuclear reactor and evaluates the measurement values ​​or the trend thereof. . To measure the vibration of the internal component of the nuclear reactor, a method is generally adopted in which a vibration sensor is installed in the reactor, and a signal from the vibration sensor is sent out of the reactor by means of a signal wire.

However, in this method it is necessary to route the signal cable inside and outside the nuclear reactor, so preparing for the measurement is labor intensive.

To address this problem, an ultrasonic vibration measurement system has been proposed as disclosed in Japanese Patent No. 3,782,559 (the full content of which is incorporated by reference herein).

In this ultrasonic vibration measurement system, an ultrasonic sensor is placed on the outer surface of a reactor pressure vessel, and an ultrasonic pulse is allowed to propagate within the reactor through the reactor pressure vessel. The ultrasonic pulse propagating within the reactor collides with and is reflected by an internal component of the reactor, such as a keg or an underwater jet pump. The reflected ultrasonic pulse is returned back to the ultrasonic sensor through the reactor pressure vessel.

If the internal component of the reactor, such as a keg, vibrates, the propagation time of the returned reflected ultrasonic pulse varies slightly due to the vibration. Assuming that the change in the propagation time of the ultrasonic pulse is At (s), the amplitude of vibrations L (m) of the internal component of the reactor, such as a barrel, is calculated using the following equation (1).

<img file="ES2380478B2_D0001.tif" />

"C" is the speed of sound (m / s) in the reactor water.

By plotting the AL in time series, the waveform of vibrations of the internal component of the reactor, such as a keg, can be synthesized.

In the conventional vibration monitoring system of a nuclear reactor and its method, an ultrasonic sensor used is configured as both a transmitter and receiver of the ultrasound. Thus, for example, in the case where the internal component of the reactor, such as a jet pump, is arranged inclined relative to the pressure vessel of the reactor, the ultrasonic pulse is reflected obliquely by the jet pump, so that the reflected ultrasonic pulse is not returned to the position of the ultrasound source. As a result, the ultrasonic sensor cannot receive the reflected ultrasonic pulse, making it impossible to measure the vibration of the internal component of the reactor.

The present invention has been made to solve the above problem, and an object thereof is to provide a vibration monitoring system of a nuclear reactor to monitor the structural integrity of an internal component of the nuclear reactor, and its method capable of measuring the vibration of an internal structure of the reactor arranged inclined relative to the pressure vessel of a reactor.

Brief summary of the invention

According to a first aspect of the present invention, a nuclear reactor vibration monitoring system is provided comprising: a first ultrasonic transducer for transmission that is disposed on the outer surface of a reactor pressure vessel and is configured to convert a transmit signal into an ultrasonic pulse signal and allow the ultrasonic pulse to be transmitted to an internal component of the reactor;

an ultrasonic transmitter that is electrically connected to the first ultrasonic transducer and is configured to transmit the transmission signal; a second ultrasonic transducer for reception that is arranged on the super2

ES 2 380 478 B2 faces the outside of the reactor pressure vessel and is configured to receive a reflected ultrasonic pulse, reflected by the internal component of the reactor, and convert the received reflected ultrasonic pulse into a receive signal; an ultrasonic receiver that is electrically connected to the second ultrasonic transducer and is configured to receive the receive signal; a signal processor that is electrically connected to the ultrasonic transmitter and the ultrasonic receiver and is configured to input a signal into the ultrasonic transmitter and receive a signal from the ultrasonic receiver to apply signal processing to the signal; and a display unit that is configured to display information on vibrations of the internal component of the reactor obtained as a result of signal processing by the signal processor.

According to a second aspect of the prese invention, there is provided a method of monitoring vibrations of a nuclear reactor comprising: allowing an ultrasonic pulse to be transmitted to an internal component of the reactor using a first ultrasonic transducer for transmission that is arranged on the outer surface of a reactor pressure vessel; receiving a reflected ultrasonic pulse, reflected by the internal component of the reactor, using a second ultrasonic transducer for reception that is disposed on the exterior surface of the reactor pressure vessel; and applying signal processing to the reflected ultrasonic pulse signal to measure the vibration of the internal component of the reactor.

Brief description of the drawings

The foregoing and other features and advantages of the present invention will become apparent from the discussion, later in this document, of specific illustrative embodiments thereof presented in conjunction with the accompanying drawings, in which:

Fig. 1 is a view schematically showing a configuration of a vibration monitoring system of a nuclear reactor according to a first embodiment of the present invention;

Fig. 2 is an explanatory view showing a state of propagation of an ultrasonic signal of Fig. 1;

Fig. 3 is an explanatory view showing a vibration measurement method using the reflected ultrasonic signal of Fig. 1;

Figs. 4A to 4C are explanatory views showing the ultrasonic pulse to be transmitted from Fig. 1 and ultrasonic pulses to be received from Fig. 1, in which Fig. 4A is a time graph of the signal of electrical pulse which is the ultrasonic pulse transmitted from the ultrasonic transducer for transmission, Fig. 4B is a time graph of an ultrasonic pulse received by the ultrasonic transducer for reception, and Fig. 4C is a time graph of another ultrasonic pulse received by the ultrasonic transducer for reception;

Fig. 5 is an explanatory view showing an actual vibration amplitude reconstruction method from discrete vibration amplitude measurement values ​​of Fig. 1;

Fig. 6 is a view schematically showing a configuration of a vibration monitoring system of a nuclear reactor according to a second embodiment of the present invention;

Figs. 7A and 7B are explanatory views showing a time relationship and a frequency relationship between a transmit RF pulse and a receive RF pulse of Fig. 6, in which Fig. 7A is a pulse timing graph of transmit RF transmitted from the ultrasonic transducer for transmit, and FIG. 7B is a timing graph of the receive RF pulse received by the ultrasonic transducer for receive;

Figs. 8A and 8B are explanatory views showing a configuration of a vibration monitoring system of a nuclear reactor according to a third embodiment of the present invention, in which Fig. 8A is a view showing a positional relationship between the pressure vessel of the reactor and the internal component of the reactor, and Fig. 8B is a cross-sectional view taken along VIIIb-VIIIb of Fig. 8A viewed from above;

Figs. 9A and 9B are explanatory views showing a configuration of a vibration monitoring system of a nuclear reactor according to a fourth embodiment of the present invention, in which Fig. 9A is a view showing a positional relationship between the pressure vessel of the reactor and the internal component of the reactor, and Fig. 9B is a cross-sectional view taken along IXb-IXb of Fig. 9A viewed from above;

Figs. 10A and 10B are explanatory views showing a configuration of a vibration monitoring system of a nuclear reactor according to a fifth embodiment of the present invention, in which Fig. 10A is a view showing a positional relationship between the pressure vessel of the reactor and the internal component of the reactor, and Fig. 10B is a cross-sectional view taken along Xb-Xb of Fig. 10A viewed from above;

Figs. 11A and 11B are explanatory views showing a configuration of a vibration monitoring system of a nuclear reactor according to a sixth embodiment of the present invention, in which Fig. 11A is a view showing a positional relationship between the pressure vessel of the reactor and the internal component of the reactor, and Fig.

11B is a cross-sectional view taken along XIb-XIb of FIG. 11A viewed from above; Y

ES 2 380 478 B2 Figs. 12A and 12B are explanatory views showing a configuration of a vibration monitoring system of a nuclear reactor according to a seventh embodiment of the present invention, in which Fig. 12A is a characteristic view showing a frequency display method original of the internal component of reactor 14, and Fig. 12B is a characteristic view showing a method of setting a threshold value.

Detailed description of the invention

Embodiments of a nuclear reactor vibration monitoring system and its method will be described below with reference to the accompanying drawings, in which the same components are given the same numbers, and matching descriptions will therefore be omitted.

First realization

Fig. 1 is a view schematically showing a configuration of a vibration monitoring system of a nuclear reactor according to a first embodiment of the present invention.

With reference to Fig. 1, a basic configuration of the vibration monitoring system of a nuclear reactor will be described.

As shown in Fig. 1, an ultrasonic transducer 1 for transmission and an ultrasonic transducer 2 for reception are arranged on the outer surface of a pressure vessel of the reactor 3. The ultrasonic transducer 1 for transmission is electrically connected to an ultrasonic transmitter 6 arranged outside or inside a containment vessel 5 through a cable 4a via a signal outlet opening of the containment vessel 5a of the containment vessel 5.

Likewise, the ultrasonic transducer 2 for reception is electrically connected to an ultrasonic receiver 7 arranged outside or inside a containment vessel 5 through a cable 4b by means of a signal outlet opening of the containment vessel 5a of the vessel. containment 5.

The ultrasonic transmitter 6 and the ultrasonic receiver 7 are electrically connected to a signal processor 8. The signal processor 8 is electrically connected to a display unit 9. The display unit 9 is configured to display a waveform of vibrations, a spectrum of vibrations or the like analyzed by the signal processor 8.

Fig. 2 is an explanatory view showing a state of propagation of an ultrasonic signal of Fig. 1.

As shown in Fig. 2, an activating pulse from the signal processor 8 is input to the ultrasonic transmitter 6 arranged on the outer surface of the reactor pressure vessel 3. When an electrical pulse signal 10 is added to the ultrasonic transducer 1 For transmission by the ultrasonic transmitter 6, the electrical pulse signal 10 is converted into an ultrasonic signal in the ultrasonic transducer 1 for transmission, and consequently, an ultrasonic pulse 11 is generated.

The generated ultrasonic pulse 11 propagates within the water of the reactor 12 through the wall of the reactor pressure vessel 3. An incident ultrasonic pulse 13 that has propagated in the water of the reactor 12 is reflected by an internal component of the reactor 14, like a jet pump. When the surface of the inner component of the reactor 14 is inclined relative to the pressure vessel of the reactor 3, a reflected ultrasonic pulse 15 propagates in an inclined direction corresponding to the angle of inclination of the internal component of the reactor 14 according to the law of reflection .

The reflected ultrasonic pulse 15 propagates at an angle of inclination until it reaches the boundary between the water in reactor 12 and the reactor pressure vessel 3. At this time, the reflected ultrasonic pulse 15 becomes a reflected ultrasonic pulse 16 which it propagates in the reactor pressure vessel 3 at a greater angle of inclination due to refraction.

The ultrasonic transducer 2 for reception, which is arranged at an arrival point of the reflected ultrasonic pulse 16 that it has previously calculated, detects the reflected ultrasonic pulse 16. The reflected ultrasonic pulse 16 detected in this way is converted into an electrical pulse signal at the ultrasonic transducer 2 for reception. The electrical pulse signal is then subjected to signal processing, such as amplification, filtering, and the like, in the ultrasonic receiver 7.

The signal processed in the ultrasonic receiver 7 is converted into a digital signal by the signal processor 8 which is constituted by a microcomputer or a frequency demodulator (FM demodulator, FM: frequency modulation), whereby information is obtained from vibrations.

Then, the information on vibrations of the internal component of the reactor 14 obtained by processing in the signal processor 8 is displayed on the display unit 9. More specifically, the display unit 9 displays the input information including a waveform of amplitude of vibrations, frequency response of the vibration, tendency of change of an amplitude of vibrations or phase of vibrations.

ES 2 380 478 B2

In the present embodiment described above, with reference to Fig. 3, a vibration measurement method using an ultrasonic pulse signal will be described.

Fig. 3 is an explanatory view showing a vibration measurement method using the reflected ultrasonic signal of Fig. 1.

As shown in Fig. 3, a DC (direct current) pulse signal is used as the electrical pulse signal 10 to be converted into an ultrasonic pulse. The ultrasonic pulse 11 from the ultrasonic transducer 1 for transmission is transmitted through the reactor pressure vessel 3 at a right angle relative to a wall of the reactor pressure vessel 3. In the water of the reactor 12, the incident ultrasonic pulse 13 propagates at a right angle relative to a wall of the reactor pressure vessel 3. The incident ultrasonic pulse 13 is reflected by the internal component of the reactor 14.

When the internal component of the reactor 14 is inclined at an angle of θ (degrees) relative to the pressure vessel of the reactor 3, the reflected ultrasonic pulse 15 propagates in the direction of 2Θ (degrees). As soon as the reflected ultrasonic pulse 15 reaches the boundary between the water in the reactor 12 and the pressure vessel of the reactor 3, the ultrasonic pulse 16 is refracted again due to the oblique propagation of the ultrasonic pulse due to a difference in velocity. of the sound in the water of the reactor 12 and in the pressure vessel of the reactor 3.

That is, the angle of refraction α (degrees) at which the reflected ultrasonic pulse 15 propagates through the pressure vessel of reactor 3 is calculated using the following equation (2) according to Snell's law.

<img file="ES2380478B2_D0002.tif" />

In the above equation, “C_Water"Is the speed of sound (m / s) of an ultrasonic wave in the water of reactor 12, and" Cvasija "is the speed of sound (m / s) of an ultrasonic wave in the pressure vessel of reactor 3.

As understood from equation (2), the refraction angle α (degrees) is determined by the speed of sound of the water in the reactor. The speed of sound of the reactor water depends on the temperature of the reactor water.

As described above, the ultrasonic pulse that has propagated through the reactor pressure vessel 3 at the refractive angle α (degrees) is received by the ultrasonic transducer 2 for reception. In order to receive an ultrasonic echo with high sensitivity, the position of the ultrasonic transducer 2 for reception may have to be adjusted depending on the temperature of the reactor water. As described in the Handbook of Ultrasonic Technology (Nikkan Kogyo Shinbun Ltd., Fourth Revised Edition, pages 1202-1203), the speed of sound (C_Water) at a temperature of 25 degrees Celsius is 1,497 (m / s), while the speed of sound (C_Water) at 287.8 degrees Celsius drops to 980 (m / s). Assuming that the speed of sound (C_vasij_to) in the pressure vessel is 6,000 (m / s) and θ is 1 degree, 8 degrees are obtained as the propagation angle α (25) at a temperature of 25 degrees Celsius, and 12.3 degrees are obtained as the angle propagation α (287.8) at 287.8 degrees Celsius. Here, the plate thickness of the nuclear reactor pressure vessel 3 is assumed to be 160 mm. In this case, when the reactor water temperature is increased from 25 degrees Celsius to 287.8 degrees Celsius, the optimum reception position of the ultrasonic transducer 2 for reception varies approximately 12 mm (160 mm x tan (8 degrees) - 160 mm x tan (12.3 degrees) = -12.4 mm).

As described in the Hanbook of Non-destructive Inspection [new edition] (edited by The Japanese Society for Non-Destructive Inspection, April 1978, pages 458 to 459) and the Handbook of New Non-destructive Inspection (edited by The Japanese Society for Non-Destructive Inspection, October 1992, pages 458 to 459), an ultrasonic inspection method that uses two ultrasonic transducers to measure plate thickness or detect defects has been widely used. In the above documents, the positions of the two ultrasonic transducers are determined only in consideration of the plate thickness D of the reactor pressure vessel 3. However, to receive the ultrasonic echo from the internal component of the reactor 14 in an optimal position , in the present embodiment the position of the ultrasonic transducer 2 for reception is adjusted in consideration of the temperature of the reactor water.

The ultrasonic transducer 2 for reception detects the ultrasonic pulses 17a and 17b with respect to the electrical pulse signal 10 which is the ultrasonic pulse transmitted from the ultrasonic transducer 1 for transmission.

Figs. 4A to 4C are explanatory views showing the ultrasonic pulse to be transmitted from Fig. 1 and ultrasonic pulses to be received from Fig. 1. Fig. 4A is a time graph of the electrical pulse signal 10 which is the ultrasonic pulse transmitted from the ultrasonic transducer 1 for transmission, Fig. 4b is a time graph of the ultrasonic pulse 17a received by the ultrasonic transducer 2 for reception, and Fig. 4C is a time graph of the ultrasonic pulse 17b received by the ultrasonic transducer 2 for reception.

ES 2 380 478 B2

When the internal component of the reactor 14 is vibrated, the arrival times at which the received ultrasonic pulse signals 17a and 17b are detected vary in proportion to the amplitude of vibrations of the internal component of the reactor. Assuming that the propagation time when the internal component of reactor 14 is not vibrated is T (s) as shown by a solid line in Fig. 3, the propagation time T is calculated using the following equation (3).

<img file="ES2380478B2_D0003.tif" />

Furthermore, when the inner component of reactor 14 is vibrated with a vibration amplitude of AL as shown by a dashed line in Fig. 3, L becomes L + AL. Assuming that a change in the propagation time T of the ultrasonic pulse is At, the propagation time At is calculated using the following equation (4).

<img file="ES2380478B2_D0004.tif" />

Consequently, the amplitude of vibrations AL is calculated using the following equation (5).

<img file="ES2380478B2_D0005.tif" />

Therefore, by measuring the change At of the propagation time in the signal processor 8 shown in Fig. 1, the amplitude of vibrations AL can be measured.

Assuming that the time interval in which the ultrasonic pulse signal 10 is generated is Ts (s), the amplitude of vibrations can be discretely measured for each time interval Ts (s).

Fig. 5 is an explanatory view showing a real vibration waveform reconstruction method from the discrete vibration amplitude measurement values ​​of Fig. 1. As shown in Fig. 5, the actual vibration waveform can be obtained.

The sampling theorem is used to reproduce a vibration signal having a frequency of f (Hz). The time interval Ts (s) in which the ultrasonic pulse signal is generated, satisfies the following equation (6).

<img file="ES2380478B2_D0006.tif" />

For example, to reproduce a vibration amplitude of at least 100 Hz, the ultrasonic pulse signal must be generated in a 200 Hz interval (Ts = 50 ms).

According to the present embodiment, even though the inner component of the reactor 14 is disposed inclined relative to the pressure vessel of the reactor 3, the reflected ultrasonic pulses 17a and 17b from the inner component of the reactor 14 can be received using the ultrasonic transducer 1 to transmission and the ultrasonic transducer 2 for reception, whereby the vibration of the internal component of the reactor 14 can be measured.

Second realization

Fig. 6 is a view schematically showing a configuration of a vibration monitoring system of a nuclear reactor according to a second embodiment of the present invention. Figs. 7A and 7b are explanatory views showing a time relationship and a frequency relationship between a transmit RF pulse and a pulse pulse.

ES 2 380 478 B2

Receive RF of FIG. 6. FIG. 7A is a timing chart of the transmit RF pulse transmitted from the ultrasonic transducer for transmission, and FIG. 7B is a timing chart of the receive RF pulse received by the ultrasonic transducer for reception. In Fig. 6, the same reference numerals as those in Fig. 1 indicate parts similar to those in Fig. 1, and therefore matching descriptions will be omitted.

As shown in Fig. 6 and Fig. 7A, an RF (radio frequency) pulse signal 18 is used as the ultrasonic pulse signal to be generated from the ultrasonic transmitter 6. That is, when the pulse signal RF signal 18 shown in Fig. 7A is input to the ultrasonic transducer 1 for transmission, an incident ultrasonic RF pulse 19 generated at that time is also converted into an RF pulse signal. The carrier frequency of the RF pulse signal thus generated is assumed to be f (Hz). This RF pulse signal propagates through the water in reactor 12, is reflected by the internal component of reactor 14, refracted at the boundary between the water in reactor 12 and the pressure vessel of reactor 3, and received by the ultrasonic transducer. 2 for reception.

The received RF pulse signal 20 is observed in a time interval of the propagation time T or (T + At), as in the case of the ultrasonic pulse signal to be transmitted and the ultrasonic pulse signal to be received from Fig. 4. The reflected RF pulse signal is Doppler-shifted by the vibration of the internal component of the reactor 14 and, consequently, the frequency of the reflected RF pulse signal is changed.

Assuming that the vibration velocity of the internal component of the reactor 14 is V (m / s), the change in frequency Af (Hz) in this case can be calculated using the following equation (7).

v

Δ / = 2 / —— cos20 ...... (7) water

In the above equation, “C_Water"Is the speed of sound (m / s) of an ultrasonic wave in the water of the reactor 12, and θ is the angle of inclination (degrees) between the pressure vessel of the reactor 3 and the internal component of the reactor 14 shown in the Fig. 6.

The frequency change Af is measured in the signal processor 8 shown in Fig. 6 using a frequency demodulation circuit. The vibration velocity V (m / s) can be recalculated from the change in frequency Af obtained using equation (7). Also in this case, the speed of vibrations is measured discretely and therefore, as in the case of the method shown in Fig. 5, the measurement value is input to signal processor 8 and then the sampling theorem is used to synthesize a vibration velocity waveform. The data obtained is then converted into a vibration amplitude waveform or vibration acceleration waveform, which is then displayed on the display unit 9.

According to the present embodiment, using the RF pulse signal 18 instead of the DC pulse signal used in the first embodiment, it is possible to detect the Doppler shift of the ultrasonic pulse signal generated with the vibration of the internal component of the reactor 14 to allow the amplitude of vibrations and the speed of vibrations to be measured simultaneously, thus improving the accuracy of the measurement.

Third realization

Figs. 8A and 8B are explanatory views showing a configuration of a vibration monitoring system of a nuclear reactor according to a third embodiment of the present invention. Fig. 8A is a view showing a positional relationship between the reactor pressure vessel and the internal component of the reactor, and Fig. 8B is a cross-sectional view taken along VIIIb-VIIIb of Fig. 8A top view. In Figs. 8A and 8B, the same reference numerals as Fig. 1 indicate parts similar to Fig. 1, and therefore matching descriptions will be omitted.

As shown in Fig. 8B, the internal component of reactor 14 is represented by a circle. The ultrasonic transducer 1 for transmission is displaced on the outer surface of the reactor pressure vessel 3 in the circumferential direction so that the position in which the ultrasonic pulse is reflected on the inner component of the reactor 14 is changed. Consequently, the position of the ultrasonic transducer 2 for reception is offset.

According to the present embodiment, the vibration of the internal component of the reactor 14 can be measured even when the internal component of the reactor 14 has a curved surface. Furthermore, by using the vibration waveforms before and after the change of the vibration measurement position, the vibration of the internal component of the reactor 14 can be measured in more detail.

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Fourth realization

Figs. 9A and 9B are explanatory views showing a configuration of a vibration monitoring system of a nuclear reactor according to a fourth embodiment of the present invention. Fig. 9A is a view showing a positional relationship between the reactor pressure vessel and the internal component of the reactor, and Fig. 9B is a cross-sectional view taken along IXb-IXb of Fig. 9A top view.

As shown in Fig. 9B, the internal component of reactor 14 is represented by a circle. The incident angle of the ultrasonic pulse to be transmitted from the ultrasonic transducer 1 for transmission is changed from β to γ ​​so that the position in which the ultrasonic pulse is reflected onto the internal component of the reactor 14 is changed. Consequently, the reception angle of the ultrasonic pulse received by the ultrasonic transducer 2 for reception is changed from β to γ.

According to the present embodiment, by changing the incident angle of the ultrasonic pulse from β to γ, it is possible to change the vibration measurement point without shifting the positions of the ultrasonic transducer 1 for transmission. In addition, by using the vibration waveforms of the inner component of the reactor 14 before and after the change of the incident angle and the angle of reception, the vibration of the inner component of the reactor 14 can be measured in more detail.

Fifth realization

Figs. 10A and 10B are explanatory views showing a configuration of a vibration monitoring system of a nuclear reactor according to a fifth embodiment of the present invention. Fig. 10A is a view showing a positional relationship between the reactor pressure vessel and the internal component of the reactor, and Fig. 10B is a cross-sectional view taken along Xb-Xb of Fig. 1A top view. In Figs. 10A and 10B, the same reference numerals as those in Fig. 1 indicate parts similar to those in Fig. 1, and therefore matching descriptions will be omitted.

As shown in Fig. 10B, the internal component of reactor 14 is represented by a circle. The position of the ultrasonic transducer 1 for transmission is changed so that the position in which the ultrasonic pulse is reflected on the internal component of the reactor 14 is changed. Consequently, the reception angle of the ultrasonic pulse is changed from β to γ ​​without displacing the ultrasonic transducer 2 for reception.

According to the present embodiment, it is possible to change the vibration measurement position without moving the ultrasonic transducer 2 for reception. Furthermore, by using the vibration waveforms of the internal component of the reactor 14 before and after the change of the position of the ultrasonic transducer 1 for transmission, the vibration of the internal component of the reactor 14 can be measured in more detail.

Sixth realization

Figs. 11A and 11B are explanatory views showing a configuration of a vibration monitoring system of a nuclear reactor according to a sixth embodiment of the present invention. Fig. 11A is a view showing a positional relationship between the reactor pressure vessel and the internal component of the reactor, and Fig. 11B is a cross-sectional view taken along Xlb-XIb of Fig. 11A top view. In Figs. 11A and 11B, the same reference numerals as those in Fig. 1 indicate parts similar to those in Fig. 1, and therefore matching descriptions will be omitted.

As shown in Fig. 11B, the internal component of reactor 14 is represented by a circle. The incident angle of the ultrasonic pulse to be transmitted from the ultrasonic transducer 1 for transmission is changed from β to γ ​​without shifting the ultrasonic pulse from the ultrasonic transducer 1 for transmission so that the position at which the ultrasonic pulse is reflected on the internal component of reactor 14 is changed. Consequently, the position of the ultrasonic transducer 2 for reception is shifted to change the reception position of the ultrasonic pulse.

According to the present embodiment, it is possible to change the vibration measurement position without moving the ultrasonic transducer 1 for transmission. Furthermore, by using the vibration waveforms of the internal component of the reactor 14 before and after the change of the position of the ultrasonic transducer 2 for reception, the vibration of the internal component of the reactor 14 can be measured in more detail.

Seventh realization

Figs. 12A and 12B are explanatory views showing a configuration of a vibration monitoring system of a nuclear reactor according to a seventh embodiment of the present invention. Fig. 12A is a characteristic view showing a method of displaying the original frequency of the internal component of the reactor having no extraordinary frequency, and Fig. 12B is a characteristic view showing a method of adjusting a threshold value.

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As shown in Fig. 12A, the frequency analysis of the vibration information of the internal component of the reactor 14 which has been obtained by the processing of the signal processor 8 is performed to calculate the frequency difference AF. Then, as shown in Fig. 12B, the temporal change of the frequency difference AF of the internal component of the reactor 14 is displayed on the display unit 9.

According to the present embodiment, the temporal change of the frequency difference AF is displayed based on the measured vibration signal. This makes it easier to understand the occurrence of abnormal vibrations, thus increasing the reliability of vibration monitoring.

Although the present invention has been described with reference to preferred embodiments, the present invention is not limited to the above embodiments but can be modified in various ways by combining the configurations of the above embodiments without departing from the scope of the present invention.