JP3074190B2 - Loose parts monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for monitoring loose parts in a fluid passage of a nuclear reactor.

[0002]

2. Description of the Related Art Nuclear reactors and the above-described generators connected thereto,
In various circulatory systems consisting of pipelines through which steam and liquid flow in the reactor, if equipment parts fall off, the fallen parts (loose parts) may damage various equipment or obstruct the flow of internal fluid. Problem arises. Nuclear technology requires more safety than other technical fields, and it is necessary to reduce the generation 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 conventionally been considered, and the applicant of the present invention has also filed Japanese Patent Application No. 57-178567,
Japanese Patent Application No. 57-212687, Japanese Patent Application No. 58-11983
No. 4, Japanese Patent Application No. 61-233443, Japanese Patent Application No. 62-17
No. 1853, Japanese Patent Application No. 63-40379, Japanese Patent Application No. 63-
Applications such as 155468, Japanese Patent Application No. 63-317313, and Japanese Patent Application No. 2-4711 have been filed. 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 an atomic path or a steam generator. However, it is compared to the normal noise generated in each device (for example, the sound of pump or motor operation, or the noise of fluid flow, etc., which is called background noise). I want to emit. In addition, the loose parts monitoring device has a built-in device called a locator that determines the correctness of the detection signal of the detector attached to each device, and this locator has the function of determining the correctness of the signal from each detector. I was letting it. As a criterion for the correct / incorrect judgment, (a) if the number of times of receiving the high alarm warning within 50 milliseconds (mmsec) is one, it is regarded as an erroneous signal. The reason is that the speed of sound in steel is 3 m / millisecond, and it travels a distance of 150 m in 50 msec. 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) 3 within 0.5 ms
If more than one alert is received, it is considered 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 ms, which means that the electrical connection between the cables connecting each detector to the control panel is This is because it is highly possible that the pulse signal is generated by inducing noise. 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 reset to cancel the data.

[0004] In other cases, it is determined that the alarm is an appropriate loose parts alarm, and an alarm is issued by a centralized alarm, and a tape recorder is automatically activated, an external alarm is generated, and recording is performed by a printer. 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 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 abnormal sounds at the site. Further, the tape recorder was stopped, and various operations such as recording the launching time of the printer and the sound of the audio monitor on recording paper were performed.

[0005]

In the above-mentioned prior art, when an alarm is generated, the alarm does not provide any information as to which part of the reactor apparatus has been dropped from which part, and the degree of damage to the plant has not been obtained. There was a problem that you can not know. SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks, to infer the location of a loose part and to infer a structure that serves as a loose part, and to provide information to plant operators.

[0006]

SUMMARY OF THE INVENTION The above objects are achieved by a monitoring device for loose part of the fluid flow path of the reactor apparatus, the fluid
Multiple detectors attached to each device constituting the flow path
An abnormal sound sensing unit for sensing a signal from the detector;
An inference unit that infers based on a signal sensed by the sound sensing unit;
A display unit for displaying an inference result, the inference part, Lou
Location and impact energy where the spurts collided with the plant structure
Energy to energy distance decline data and sensed energy
The position and energy inference means for inferring from over was estimated
Outflow route and outflow of loose parts to the collision position
Collision route to infer the flow velocity of the plant from plant structure data
From the inference means and equipment part data
Possibility of generating collision energy inferred at collision location
Check if there is a part with a mark on the outflow route
Loose parts inferring means and the energy decay
Data, plant structure data, equipment parts data, etc.
Storage means for storing data necessary for any inference ,
The display unit displays the estimated value obtained by the loose part inference means.
Of generating inferred collision energy at the impact location
This is achieved by the display means for displaying a candidate part having a character.

[0007]

The function of estimating the position and energy at which the loose parts collided with the plant structure from the signals obtained from the plurality of detectors, the function of estimating the fall path of the loose parts from the estimated positions, The part which may become a loose part is restored, the validity is checked from the estimated energy, the loose part is inferred, and displayed to the operator.

[0008]

FIG. 1 shows an embodiment of the present invention. The signal detected by the detector 2 attached to the device 1 is guided to the abnormal sound sensing unit 3 to determine whether the signal is suspected as a loose part.
Regarding the method, the method described in the prior art, Japanese Patent Application No. 63-317313, Japanese Patent Application No. 63-155468,
Techniques such as Japanese Patent Application No. 63-40379 have been proposed.
After performing these processes, if it is determined that the part is a loose part, a signal is led to the inference unit 4. The inference unit 4 estimates the position from the obtained signals in the manner of three-point surveying, and estimates the collision energy from the distance attenuation data of the energy stored in the storage unit 8 and the sensed energy. Estimate position and collision energy.
The collision route inference unit 6 infers the outflow route of the loose parts up to the estimated collision position from the plant structure data stored in the storage unit 8. At the same time, the flow velocity of the inferred outflow route is inferred. In the loose part inference unit 7,
At a presumed collision position, a check is made to determine whether or not there is a part on the outflow route at a presumed collision position from among the device parts stored in the storage unit 8 in advance. I do. The candidate parts are displayed on the display unit 9.

The operation of the components of the inference unit 4 will be described. The position and energy estimating unit 5 obtains the time difference between the detected signals to estimate the position. As shown in FIG. 2, sounds emitted from the collision point P are detected in order of decreasing distance from P.
The relationship between the distances d ₁ , d ₂ , and d ₃ between the positions of the detected detectors (sensors) A, B, and C and the position of the point P is represented by d ₁ > d ₂ > d.
₃ and when the waveform detected by each sensor (to be referred to as a first channel) a waveform of the sensor C arrival as shown in Figure 3 as sensor B, a BanTsuta stuff a time difference t _1, t ₂ in the order of A Become. The time differences t ₁ and t ₂ indicate the sound speed in the device as v _K
Then

## EQU1 ## t ₁ = (d ₂ −d ₃ ) / v _K , t ₂ = (d ₁
−d ₃ ) / v _K. Therefore, if the time differences t ₁ and t ₂ can be measured, the point P that determines them can be calculated backward. If the position of the point P is known, the distance d (d _{3 in} FIG. 2) between the first channel and the collision point P can be obtained. Therefore, the sensor uses the distance attenuation data of the energy in the sensor (FIG. 4). Estimate the collision energy from the energy sensed by.
The energy distance attenuation data is obtained by performing a heating test of each device at the time of a plant test run or the like, and stored in the storage unit 8.

The collision route inference unit 6 infers a route through which parts of the device flow out to the collision point P. For example, as shown in FIG. 5, the device is divided into a plurality of elements (divided element 11),
Define whether parts can flow out between each element.
The loose part outflow route 12 up to the element 13 including the loose part collision position P is sequentially traced, and the element corresponding to the outflow route is restored. In each element, the velocity data of the fluid is stored in the storage unit 8 as a vector 14 (FIG. 6). That is, the flow velocity and its directionality. Since this depends on the condition of the plant, it should be changed together with the data on the specific weight of the fluid depending on the operating conditions. An average value V of the flow velocity of the element corresponding to the outflow route is obtained. Assuming now that the direction of the gravitational acceleration is positive and the upward flow velocity V is acting, the resistance D acting on the loose part is expressed by the following equation.

D = (1/2) ρV ² C _D S ρ; Specific gravity of fluid V; Flow velocity C _D ; Resistance coefficient S; Representative area (area subject to drag) Therefore, force F acting on loose parts is

F = Mg-D g; gravitational acceleration M; weight Assuming that the robot falls while receiving this force, the acceleration is α
given that,

## EQU4 ## F = M.alpha.

Α = F / M = g− (D / M) Assuming that the mounting height of the loose part is h _T and the height of the collision point P is h _P , the collision energy E is

E = Mα (h _T −h _P )

Therefore, if the collision energy and position, the flow velocity of the outflow route, and the specific gravity of the fluid are known, the possibility of loose parts can be inferred. For this purpose, as shown in FIG. 7, the parts including the weight M of the parts constituting the device, the resistance coefficient C _D , the representative surface type S, the division element NO where the parts are installed, the height data, etc. The list is stored in the storage unit 8, and parts having a possibility of becoming loose parts are restored using Expressions 2 to 6. The restored parts are displayed on the display unit 9.

If the relationship between the collision energy and the weight does not match well, it is possible that a part of the part is missing. Therefore, if the weight of each part is equivalent to what percentage, other conditions can be satisfied. Check. In the present embodiment, the flow-off route and the flow velocity are considered by dividing the device into elements, but a method in which the flow-out route and the flow velocity for one part are calculated and determined is also conceivable.
That is, it is put in the item of the parts list shown in FIG. This method is expected to speed up the search. However, assuming that the plant state changes due to a change in plant load or the like, it is necessary to have a plurality of conditions for the flow velocity, and it is considered that a method of dividing the elements into which the conditions can be easily changed is better.

[0013]

According to the present invention, it is possible to know a part whose detected signal is likely to be a loose part, so that the degree of plant damage can be ascertained, and an operation for maintaining plant safety (plant operation). (E.g., stoppage) can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a loose parts monitoring apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a state in which an acoustic signal generated when a loose part collides is detected by a plurality of sensors.

FIG. 3 is a waveform diagram of a signal detected by the sensor of FIG. 2;

FIG. 4 is a characteristic diagram showing an example of an energy distance attenuation curve.

FIG. 5 is an explanatory diagram showing a state in which a device is divided into elements to search for an outflow route up to a loose part collision position.

FIG. 6 is an explanatory diagram showing a flow velocity distribution in the above elements.

FIG. 7 is an explanatory diagram of a part list that can be a loose part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Device 2 Detector 3 Abnormal noise detection part 4 Inference part 5 Position and energy inference part 7 Loose parts inference part 8 Storage part 9 Display part

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G21C 17/04 G21C 17/00 G01N 29/04

Claims (1)

(57) [Claims] An apparatus for monitoring loose parts in a fluid flow path of a nuclear reactor , comprising: a plurality of detection devices attached to each device constituting the fluid flow path;
A noise detector for sensing a signal from the detector;
Inference unit that infers based on the signal detected by the abnormal sound detection unit
And a display unit for displaying an inference result, wherein the inference unit determines a position where the loose part collides with the plant structure and a collision error.
Energy as energy distance decline data and sensing energy
Position / energy inference means inferring from lugie and outflow route of loose parts to estimated collision location
The flow velocity of water and outflow route from plant structure data
Inference based on collision route inference means and estimated collision position from equipment part data
Parts that could generate crushed collision energy
Rusper checks to see if it is on the outflow path
Inference means, the energy decay data, the plant structure data
Data necessary for inference, such as
Storage means for storing the estimated value obtained by the loose part inference means.
Of generating inferred collision energy at the impact location
A monitoring device for loose parts, which is a display means for displaying a candidate part having a part.