JP2648597B2 - Monitoring equipment for loose parts in the fluid flow path of a nuclear reactor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for monitoring a dropped component by detecting a vibration sound (noise) generated from the dropped component in a fluid flow path, and in particular, to an atomic device. The present invention relates to an apparatus for suitably monitoring a dropped component in a fluid channel of a furnace.

[Conventional technology]

If equipment parts fall off in various circulatory systems consisting of pipes through which the steam and liquid of the reactor flow, such as the reactor and the steam generator connected to the reactor, these fallout parts (loose parts)
This causes problems such as damage to various devices and obstruction of the flow of the internal fluid. Nuclear technology requires more safety than other technical fields, and it is necessary to reduce the occurrence of loose parts as much as possible. It is necessary to accurately detect the location of occurrence and the moving state of the loose parts. For this reason, various countermeasures have been conventionally considered, and the applicant of the present application has filed applications such as Japanese Patent Application No. 57-178567, Japanese Patent Application No. 57-212687, and Japanese Patent Application No. 58-119834.

In a conventional loose part monitoring device of a nuclear power plant, a value of an impact waveform of a loose part detected by a detector (for example, an accelerometer) attached to each device of a primary cooling system such as a nuclear reactor or a steam generator. However, compared to the normal noise that occurs in each device (for example, the noise of the operation of the pump or motor, or the noise of the fluid flow, these are called background noise). I want to emit. In addition, the loose parts monitoring device incorporates a device called a locator that determines the correctness of the detection signal of the detector attached to each device,
This locator has a function of judging the correctness of a signal from each detector. As a criterion for such judgment,
(A) If the number of times of receiving the high alarm warning within 50 milliseconds (mm sec) is one, it is regarded as an erroneous signal. The reason is that the speed of sound in steel is 3m / msec, and it travels 150m in 50msec. The distance between detectors attached to each device is about 20 m at the maximum, and if loose parts are generated, many signals should be transmitted from nearby detectors in a short time. (B) If three or more alarm signals are received within 0.5 millisecond, it is regarded as a false signal. Due to the placement of the detectors, it is highly unlikely that more than two alarms will be received within 0.5 milliseconds, which will reduce electrical noise between the cables connecting each detector to the control panel. This is because there is a high possibility that the pulse signal is induced and emitted. In the above cases (a) and (b), the signal adjuster and the detector are reset, and at the same time, the centralized alarm and the locator are also reset to cancel the data.

In other cases, it was determined that the alarm was an appropriate loose parts alarm, an alarm was issued by the collection alarm, the tape recorder was automatically activated, an external alarm was generated, and a printer was used for recording. At the same time as this recording, all components of the apparatus except for the external alarm and the tape recorder that are activated are to be reset.

Then, every time an external alarm is issued, the operator goes to the monitoring device, temporarily stops the external alarm, and checks the audio monitor for an abnormal sound at the site. Further, various operations such as stopping the tape recorder and recording the launching time of the printer and the result of listening to the audio monitor on the recording paper have been performed.

[Problems to be solved by the invention]

However, in the conventional monitoring device, false alarms frequently occur due to thermal expansion (a squeaking sound occurs when the metal wall of each piping device expands due to thermal expansion) due to a pressure change or a temperature change that occurs when the nuclear power plant is started. Each time this alarm was issued, the operator had to repeat the various operations described above, making the operation complicated, and in addition, the operator was forced to use a printer or record data using a tape recorder.

[Means for solving the problem]

The present invention has been made to solve the above problems, and in a monitoring device for loose parts in a fluid flow path of a nuclear reactor, a plurality of detectors attached to each device constituting the fluid flow path. An abnormal sound sensing unit for sensing a signal from the detector, and determining whether the signal detected by the abnormal sound sensing unit is correct or incorrect based on the number of receptions within a predetermined time and transmitting a correct signal to the pattern analysis unit. A pattern analysis unit that removes an erroneous signal by comparing the signal from the true / false determination unit with a reference signal pattern; and estimates the impact energy based on the detected acceleration for the signal that clears the pattern analysis unit. An energy analyzer that issues an alarm when is greater than or equal to a predetermined value, a frequency analyzer that determines the frequency of occurrence of a signal that clears the pattern analyzer, and removes the signal based on the frequency of occurrence. There is provided a monitoring device for loose part of the fluid flow path of the reactor apparatus, characterized in that it includes.

〔Example〕

This will be described below with reference to FIG. Loose parts detectors (signal conditioners) 11 to 20 are used in nuclear power plants.
Detector (accelerometer) installed on secondary system piping or auxiliary equipment
When a sudden impact sound is generated from the vibration sound detected in 1 to 10 (see FIG. 2) as compared with the normal background noise (background noise), an alarm is issued. Parts vibration sounds are compared, and an alarm is issued if it exceeds a certain comparison. In addition, based on this alarm, the validity check as to whether or not a loose part is generated is performed by the FER (false alarm evaluation and recording unit) 21 as described below.

As shown in FIG. 2, the abnormal noise detector 22 detects that abnormal noise is generated in the FER 21 based on an alarm signal from the loose part detectors 1 to 10. Further, it is necessary to diagnose whether the abnormal noise is a loose part. Therefore, this is first performed by the right / wrong judgment unit 23. This feature
As in the prior art, (a) a case where the number of alarms is one within 50 ms, and (b) a case where three or more alarms are received within 0.5 ms are regarded as false alarms.

The signal that clears the correct / incorrect judgment section is sent to the pattern analysis section.
At 24, the correctness of the signal is determined. The method of pattern analysis will be described below. 1 such as a nuclear reactor or heat exchanger
A detector (sensor) such as an accelerometer is attached to a required position in each of the sub-system devices, and when a loose part is generated, a combination of sensors for detecting the loose part is determined depending on the location of the loose part. That is, the sensor at the shortest distance transmits the detection signal first, and then the sensor disposed at the second closest distance transmits the detection signal. Then, when the mounting position of each sensor is determined, the time lag (maximum delay time) between the transmission signals of both sensors is determined. That is, the combination of the first sensor channel (CH) of the signal and the sensor channel to be transmitted next and the validity of the maximum delay time order between the two channels are stored in advance in the memory of the device as an event table, and the actual Is compared with the received signal pattern to determine whether the signal is correct or not. This is schematically shown as follows.

(1) Event table Loose parts based on the positional relationship between the sensor CH (first arrival CH) and the second CH (late arrival CH) that first detected abnormal noise,
The likely combination of CHs and the maximum delay time are determined.
This combination is stored in the memory as an event table.

(2) Pattern analysis Therefore, when loose parts occur in the flow path of a nuclear power plant and the loose parts collide with a wall in the pipe, etc., a combination of a plurality of detectors that detect the collision sound depending on the location, a detection delay time pattern Is obtained by a simulated impact test, is compared with a loose parts alarm generation channel at the time of abnormal noise generation, and if they do not match, it is canceled as an erroneous alarm.

Next, the frequency analysis unit 30 skips the sequence, and mainly at the time of plant startup, the pressure and the temperature gradually increase, and the intervals due to the thermal expansion pulses generated when the metal wall of the pipe and each device is elongated have a long interval. Against
The generation of abnormal noise by loose parts is distinguished by focusing on the short intervals and high frequency of occurrence, and those due to thermal expansion are excluded as false alarms. Specifically, it is implemented by performing a frequency analysis using the following frequency table.

(1) Frequency table The number of abnormal sounds generated within the last T seconds is recorded for each pair of the first-arriving CH and the second-arriving CH.

(2) Frequency analysis Note) Time (T) and frequency (X) can be changed between startup and normal operation.

(3) When the frequency increases, frequency information is issued for the purpose of requesting the monitoring of the listening sound.

Next, there is a case where it may be determined as an erroneous signal in the frequency analysis, and a countermeasure in that case is necessary.
In the case of an active loose part moving in a flow path, the frequency of occurrence of the same place is one at the initial impact, so it will be canceled as a false signal, but even if it is once, the impact energy that damages the plant If so, there is a risk of causing a serious accident at the plant. Therefore, it is necessary to generate an alarm for energy that causes secondary damage to the plant. Therefore, the energy is calculated in advance. For example, the damage energy is calculated from the impact energy at which the fuel pellet is damaged, the impact energy at which the S / G heat transfer tube is damaged, and the material and thickness of the weakest material for each part. In addition, hitting the vicinity of the detector with known energy, from a simulated impact test, the relationship between the impact energy of each part and the detected acceleration is obtained in advance, and if loose parts actually occur, from the detected acceleration of the nearby detector, The impact energy is estimated, and if it is equal to or more than a predetermined energy, an alarm is generated. If it is less, cancel it.

Actually, the energy analyzer 28 automatically starts the data recorder by recording the first waveform, records the waveform, and calculates the energy at the sensor mounting position from the difference between the maximum value and the minimum value of the waveform. If the energy is above the threshold (currently 4g), an alarm is issued.

After the validity of the signal is confirmed by the pattern analysis unit 24 as a non-erroneous signal, only the four sensor channels in which the alarms are generated are selected by the generation order 4CH selection unit 25 in the generation order, and the data recording system (DAS) 27 is selected. D to transfer data to
The AS data transmitter 26 transfers the waveform data at the time of alarm generation for 100 milliseconds to 27. In the case of 27, about 500 cases of waveform data can be digitally stored on the hard disk, and the abnormal noise position and energy can be estimated by the digital automatic analyzer. It is also possible to transfer and store data on a floppy disk as needed.

〔The invention's effect〕

By implementing the present invention, it is possible to judge a false alarm based on thermal expansion at the time of starting a nuclear reactor or the like, and it is possible to prevent unnecessary work of operators and equipment due to the false alarm. .

[Brief description of the drawings]

FIG. 1 is an embodiment diagram of the present invention, and FIG. 2 is an overall schematic diagram of an apparatus according to the present invention. 1-10 Detector, 21 False alarm evaluation / recording unit,
22: abnormal noise detection unit, 23: correct / incorrect judgment unit, 24: pattern analysis unit, 25: chronological 4CH selection unit, 26: data transfer unit, 27: data recording system, 28: energy analysis Department, 30 ... Frequency analysis unit.

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-56-16821 (JP, A) JP-A-62-8095 (JP, A) JP-A-49-107280 (JP, A) JP-A-61-181 90089 (JP, A)

Claims (1)

(57) [Claims] An apparatus for monitoring loose parts in a fluid flow path of a nuclear reactor, comprising: a plurality of detectors attached to each device constituting the fluid flow path; and a detector for detecting a signal from the detector. A sound detector, a correct / erroneous determiner that determines correctness of the signal detected by the abnormal sound detector based on the number of receptions within a predetermined time and transmits a correct signal to the pattern analyzer, and a signal from the correctness / error checker is used as a reference. A pattern analysis unit for removing an erroneous signal by comparing with a signal pattern; and an energy for estimating an impact energy based on a detected acceleration for a signal obtained by clearing the pattern analysis unit and issuing an alarm when the impact energy is equal to or more than a predetermined value. An analysis unit, and a frequency analysis unit for determining a frequency of occurrence of a signal that has cleared the pattern analysis unit and removing an erroneous signal based on the frequency of occurrence. Monitoring apparatus of loose parts in the flow path.