JPH01321397A - Monitor for loose parts - Google Patents

Abstract

PURPOSE:To intend a reduction of a generating ratio of error alarms by judging a genuine or a false signal detected by an abnormal sound sensor and by rejecting the false signal. CONSTITUTION:In case that detectors 1 to 10 placed on a primary system pipings and auxiliary equipments of a nuclear power generating plant detect vibrating sound, a loose parts detectors 11 to 20 generate alarm signals and by those signals, an abnormal sound sensor 22 senses a generation of the abnormal sound. On the other hand, a judging part 23 of a true or a false signal judges a true or a false signal by a number of receiving times of the detected signals and an upper and lower limit analyzing part 24 of energy removes false signals in the signals which pass through the judging part 23, based on a combination of an extent of the energy and sensors which detect the sound and thereafter a data recorder 25 records only signals to be judged as ones from loose parts. With this structure, false alarms caused by back ground noises during a start up and a shut down operation are judged, and loose parts can be monitored.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to the prevention of falling parts (loose parts) in a fluid flow path.
The present invention relates to a loose parts monitoring device that monitors falling parts by detecting vibration sounds emitted from the parts, and particularly relates to a loose parts monitoring device that reduces the incidence of false alarms.

[Conventional technology]

If equipment parts fall off in various circulation systems consisting of pipes through which reactor steam and liquid flow, such as in the nuclear reactor and the steam generation section connected to it, these falling parts (loose parts) can damage various equipment. Receive it 1. Problems arise such as the flow of internal fluid being obstructed. Nuclear technology requires safety more strongly than other technical fields, and it is necessary to reduce the occurrence of loose parts as much as possible, and if loose parts occur, it is necessary to quickly detect the fact and take appropriate measures. It is necessary to accurately detect the occurrence site and the movement state of this loose part. For this reason, various countermeasures have been considered in the past, and the applicant of the present application also applied for patent application No. 57-178567
No., Patent Application No. 57-212687, Patent Application No. 1982-119
No. 834, Utility Application No. 195911, Patent Application No. 1982-
Applications such as No. 171853 have been filed.

In conventional nuclear coupler plant loose parts monitoring equipment, the value of the impact waveform of loose parts detected by a detector (for example, an accelerometer) attached to each device of the primary cooling system such as a nuclear reactor or steam generator is used. However, if the noise exceeds a certain ratio compared to the normal noise generated in each device (for example, the operating sound of a pump or motor, or the sound of fluid flowing, these are called background noise), a high alarm is issued. I am planning to issue it. Loose parts monitoring equipment also has a built-in device called a locator that determines whether the detection signals from the detectors attached to each device are correct. It was set. The criteria for determining whether it is correct or incorrect is (a') If the number of times a high alarm alarm is received is one within 50 milliseconds (5 ec), it is considered to be an erroneous signal. The reason is,
The speed of sound in steel is 3 m/millisecond, and the speed of sound in steel is 1 m/msec in 50 msec.
It will be transmitted over a distance of 50m. The maximum distance between the detectors attached to each device is about 20 meters, and if loose parts are occurring, many signals should be emitted from nearby detectors within a short period of time. (b) If three or more alarm signals are received within 0.5 milliseconds, it will be considered a false signal. Due to the arrangement of the detectors, it is highly unlikely that more than two alarms will be received within 0.5 milliseconds, and this is because the cables connecting each detector to the control panel This is because there is a high possibility that the pulse signal is generated by inducing electrical noise. In the above cases (a) and (b), reset the signal conditioner and detector, and at the same time,
I also decided to reset the central alarm and locator and cancel the data.

In other cases, we consider this to be a reasonable loose parts alarm.
The alarm was issued by a central alarm system, the tape recorder was automatically activated for recording, an external alarm was issued, and the recording was recorded using a printer. At the same time as this recording, all components of the device will be reset, except for the external alarm and tape recorder, which are activated.

Then, each time an external alarm is issued, the operator goes to the monitoring device, temporarily suspends the external alarm, and checks the audio monitor to see if there are any abnormal sounds at the site.

Furthermore, the tape recorder was stopped and various tasks were performed, such as recording the ejection time of the printer and the listener results of the audio monitor on recording paper.

[Problem to be solved by the invention]

However, with conventional monitoring devices, pressure changes and temperature changes that occur during startup of a nuclear power plant can cause thermal expansion (a kerfing sound occurs when the metal walls of piping equipment expand due to thermal expansion) and flow noise from equipment. This causes frequent false alarms. Each time this alarm is issued, the operator has to repeat the various tasks described above, making the work complicated.
There were also other wastes such as printing out printers and recording data with tape recorders.

According to actual measurement data, it has been reported that more than 2,000 false W alarms occur during - times of plant startup (several days), and in such cases, it is difficult to carry out the various tasks described above. It was almost impossible to analyze it.

Therefore, in actual operation, it has been common practice to exclude the loose parts monitor alarm during startup, and to return the system online after startup is complete.

That is, the conventional system had a fatal drawback in that it could not be used during startup and shutdown.

[Means to solve the problem]

The above-mentioned problem with the conventional technology is that in a monitoring device for loose parts occurring in a fluid flow path, a plurality of detectors are attached to equipment constituting the fluid flow path to detect collisions caused by loose parts, and an abnormal noise sensing section that senses the signal; a correct/incorrect judgment section that receives the signal detected by the abnormal noise sensing section, determines whether it is correct or incorrect based on the number of times it is received within a predetermined time, and sends the correct signal to the energy upper/lower limit analyzer; an energy upper/lower limit analyzer which receives a signal from the correct/incorrect judger and examines the success or failure of equation (2) described in the specification based on the magnitude of the signal energy and a combination of the detector that detected the signal and eliminates false signals; The problem is solved by a loose parts monitoring device which is characterized by comprising:

〔Example〕

The present invention will first be described in detail below using FIGS. 1 and 2.

A plurality of detectors (1 to 10, e.g. accelerometers) attached to each device constituting the fluid flow path of a nuclear reactor system, and a signal condition that amplifies the signal from the detector and keeps the amplitude constant. a false alarm evaluation and recording unit (21, FER) that evaluates and records whether the signal is due to background noise or actual loose parts; and a data recorder (25) for recording only signals determined to be loose parts.

A false alarm evaluation and recording unit (21) includes an abnormal noise sensing section 22 that detects signals from the signal conditioning section (11 to 20), and the number of receptions within a predetermined time of the signals detected by the abnormal noise sensing section. The correctness judgment unit (2) judges whether it is correct or incorrect by
3) and an energy upper/lower limit analyzer 24 which removes erroneous signals from the combination of the detector and the magnitude of the energy of the signal that has cleared the correctness/incorrect determination section.

Next, the content of the present invention will be explained in detail below. In FIG. 2, loose parts detectors (signal conditioners) 11 to 2
0, if there is a sudden impact sound compared to normal background noise in the vibration sound detected by accelerometers 1 to 10 installed in the primary system piping or auxiliary equipment of a nuclear power plant. Normally, background noise and loose parts vibration sound are compared, and if the ratio exceeds a certain level, an alarm is issued. Further, in response to this alarm, the FER (False Alarm Evaluation and Recording Unit) 21 performs the following validity check (to determine whether or not loose parts have occurred overall).

As shown in FIG.
Detects that an abnormal noise is occurring. Furthermore, it is necessary to diagnose whether this abnormal noise is due to loose parts. Therefore, this is first performed by the correct/incorrect judgment unit 23. Similar to the prior art described above, this function works in cases such as (a) when the number of alarms is one within 50 milliseconds, and (b) when three or more alarms are received within 0.5 milliseconds. Considered a false alarm.

The signal that has cleared the correct/incorrect judgment section is judged by the energy upper/lower limit analysis section 24 as to whether the signal is correct or incorrect.

The method of energy upper and lower limit analysis will be explained below. Detectors (sensors) such as accelerometers are attached to each primary system equipment such as a nuclear reactor or a heat exchanger at required positions, and when a loose part occurs, the closest sensor first sends a detection signal. (referred to as the first channel), and then the sensor disposed at the second closest distance (referred to as the second channel) transmits a detection signal.

L is the energy level (energy intensity) at the point of impact when the loose part collides with the pipe wall of the flow path.
i, and the detected energy level detected by a sensor provided at a point at a distance from the impact point is LA, then the following relationship (1) holds true.

, Number one is =LtD...(1) Here, α is a constant according to equation (1), and the detection/non-detection of impact due to loose parts at each sensor installed at various locations in the flow path is LA>Ls (L threshold). here,
The threshold value Ls is a threshold value that indicates that it is a loose part rather than a background noise Lb, and LS=KL.
There are 6 relationships.

Now, Li and D with constant threshold values for each sensor
The relationship is shown in Figure 4. Here, C1 is a set (group) of sensors that detected loose parts, and C is a set of loose parts that did not detect loose parts. It can be seen from Fig. 4 that the energy level at the impact point due to the loose part is higher than the energy Lmin that can be detected by sensor 2, which is the farthest from the impact point among the detection sensor groups, and the energy level at the impact point among the undetected sensor groups. This means that it is smaller than the energy l,max that can be detected by the sensor 3 closest to . That is, the relationship Lmin<Li<Lmax·=(2) holds true, and the upper and lower limits of energy at the impact point can be estimated.

As mentioned above, if the relationship in equation (2) holds, the fourth
The relationship shown in the figure occurs, but if the wave is not caused by loose parts, the characteristics will be different from the propagation of sound waves due to metal impact, and the relationship shown in Figure 4 will not hold.

For example, as shown in FIG. 5, if the relationship between Lmax and Lmin in the sensors of the detection group and the non-detection group is reversed, it is not appropriate to consider it as an impact due to loose parts.

A HI alarm (high alarm) is issued only when it is determined that it is a true loose part as described above, and at the same time 4
A channel data recorder 25 records the signal.

This judgment unit confirmed that in 41 actual tests on a nuclear reactor system, it was possible to reduce the number of false alarms from 267 with the conventional technology to 18, that is, to 93%, and the 7% that could not be eliminated. coincidentally E = D””φ
A pattern of riding indicates that an impact has occurred.

〔Effect of the invention〕

By implementing the present invention, false alarms can be determined based on background noise during startup of nuclear reactor equipment, etc., and loose parts can be monitored even during startup/shutdown, which could not be monitored conventionally. became.

[Brief explanation of the drawing]

Fig. 1 is an embodiment of the present invention, Fig. 2 is an overall view of a conventional loose bart monitoring device, Fig. 3 is a relationship between the distance from the impact point and detected energy, and Fig. 4 is the impact of loose barts. FIG. 5 is a diagram illustrating a method of determining whether or not a loose part is detected by each sensor due to a cause other than loose parts. 1-10...Detector, 11-20...Loose parts detector, 21...False alarm evaluation recording unit, 22.
... Abnormal noise detection section, 23... Right/wrong judgment section, 24... Energy upper/lower limit analysis section, 25... Data recorder. Agent Patent Attorney Takenaga Kawakita Figure 1 Figure 2

Claims (1)

[Claims] (1) A monitoring device for loose parts that occur in a fluid flow path includes a plurality of detectors that are attached to equipment that makes up the fluid flow path and detects collisions caused by loose parts, and detects signals from the detectors. an abnormal noise detection section, a correctness judgment section that receives the signal detected by the abnormal noise detection section, judges whether it is correct or incorrect based on the number of receptions within a predetermined time, and sends the correct signal to the energy upper/lower limit analysis section; It is characterized by being equipped with an energy upper and lower limit analysis section that receives a signal and examines the success or failure of formula (2) described in the specification based on the magnitude of the signal energy and the combination of the detector that detected the signal and eliminates false signals. Loose parts monitoring device.