JPH04258798A - Loose part monitoring device - Google Patents

Abstract

PURPOSE:To infer the occurrence position of a loose-part and structure to have been a loose-part and provide the information to a plant operator. CONSTITUTION:Multiple detector 2 fietted to apparatuses constituting a fluid passage, a noise sence section 3 sensing the signals from the detectors 2, an inference section 4 inferring the occurrence position of a loose-part and structure to have been a loose-part from the signal sensed by the noise sense section 3, a memory section 8 storing the data (flow velocity, weight position of parts) of a plant structure required for inference, and a display section 9 displaying the inference result.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loose parts monitoring system in a fluid flow path of a nuclear reactor system.

0002

[Prior art] Nuclear reactor and the above-mentioned generation parts connected to it, etc.
In various circulation systems consisting of pipes through which steam and liquid flow in a nuclear reactor, if equipment parts fall off, these loose parts may damage various equipment or obstruct the flow of internal fluids. The problem arises. Nuclear technology requires greater safety than other technical fields, and it is necessary to reduce the occurrence of loose parts as much as possible, and if loose parts occur, the fact should be detected early and It is necessary to accurately detect the occurrence site and the movement state of this loose part.

[0003] For this reason, various countermeasures have been considered in the past, and the applicant of the present application has also proposed Japanese Patent Application No. 57-178567,
Patent application No. 57-212687, Patent application No. 11983-1983
No. 4, Patent Application No. 1983-233443, Patent Application No. 1982-17
No. 1853, Patent Application No. 1983-40379, Patent Application No. 1983-
155468, Japanese Patent Application No. 63-317313, and Japanese Patent Application No. 2-4711. In conventional loose parts monitoring equipment for nuclear power plants, the value of the impact waveform of loose parts detected by detectors (e.g. accelerometers) attached to each device of the primary cooling system such as the atomic path and steam generator. However, if the noise exceeds a certain level compared to the normal noise generated in each device (for example, the operating sound of pumps and motors, 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 are: (a) If the number of times a high alarm alarm is received within 50 milliseconds (mmsec) is one, it is considered to be an erroneous signal. The reason is that the speed of sound in steel is 3 m/millisecond, and sound travels a distance of 150 m in 50 msec. 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) 3 within 0.5 milliseconds
If more than one alarm is received, it is 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 due to the electrical connection between 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 noise. In the above cases (a) and (b), it was decided to reset the signal conditioner and detector, and at the same time reset the central alarm, locator, etc., and cancel the data.

[0004] In other cases, it has been determined that the loose parts alarm is valid, and an alarm is issued by a central alarm, the tape recorder is automatically started, an external alarm is issued, and a record is made by a printer. At the same time as this recording, all components of the apparatus will be reset, except for the external alarm and tape recorder, which are in operation. 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 is any abnormal sound 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 listening results of the audio monitor on recording paper.

[0005]

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, when an alarm occurs, no information can be obtained as to which part of the reactor equipment has fallen off, and the degree of damage to the plant has not been obtained. The problem was that it was impossible to know. An object of the present invention is to improve the above-mentioned drawbacks, to infer the location of loose parts and the structures that have become loose parts, and to provide this information to plant operators.

[0006]

[Means for Solving the Problems] The above object is to provide a monitoring device for loose parts in a fluid flow path of a nuclear reactor system, which includes a plurality of detectors attached to each device constituting the fluid flow path, an abnormal noise sensing unit that senses signals from the noise sensing unit, an inference unit that infers the location of loose parts and structures that have become loose parts from the signals detected by the abnormal noise sensing unit, and plant structures necessary for the inference. This is achieved by including a storage unit that stores data and a display unit that displays the inference results.

[0007]

[Function] A function to estimate the position and energy at which a loose part collides with a plant structure from signals obtained from multiple detectors, a function to estimate the fall route of the loose part from the estimated position, and a function to estimate the fall path of the loose part from the estimated position, and The system restores parts that are likely to become loose parts, checks their validity based on the estimated energy, infers which parts have become loose parts, and displays the results to the operator.

[0008]

Embodiment FIG. 1 shows an embodiment of the present invention. A signal detected by a detector 2 attached to the device 1 is guided to an abnormal noise sensing section 3, and it is determined whether or not it is suspected to be 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 guided to the inference section 4. The inference unit 4 estimates the position from the obtained signal using a three-point survey method, and the “position and energy inference unit” 5 estimates the collision energy from the energy distance attenuation data and the sensed energy stored in the storage unit 8. 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 parts inference section 7,
Checks whether there is a part on the outflow route that could potentially generate the estimated collision energy at the estimated collision position from among the parts of the equipment that have been restored and stored in the storage unit 8 in advance. do. The candidate parts are displayed on the display section 9.

The functions of the components of the inference section 4 will be explained. The position and energy inference section 5 calculates the time difference between the detected signals and estimates the position. As shown in FIG. 2, sounds emitted from the collision point P are detected in order of distance from P. The relationship between the distances d1, d2, and d3 between the detected positions of detectors (sensors) A, B, and C and the position of point P is expressed as d1>
If d2 > d3, the waveforms detected by each sensor will be processed in the order of sensors B and A with a time difference t1, with the waveform of sensor C being the first (referred to as the first channel) as shown in Fig. 3.
, t2. The time difference t1 and t2 is as follows, assuming that the speed of sound in the device is vK.

[Equation 1] t1 = (d2 - d3)/vK, t
2 = (d1 - d3)/vK. Therefore, if the time difference t1 and t2 can be measured, the point P that determines it can be calculated backwards. If the position of point P is known, the distance d between the first channel and the collision point P
(d3 in FIG. 2), the collision energy is estimated from the energy sensed by the sensor using distance attenuation data of energy at that sensor (FIG. 4). Energy distance attenuation data is obtained by performing a heating test on each device during plant trial operation, etc., and is stored in the storage unit 8.

The collision route inference unit 6 infers a route through which the parts of the equipment will flow to the collision point P. For example, as shown in FIG. 5, the device is divided into multiple elements (divided element 11),
Define whether parts can flow between each element. The loose parts outflow route 12 up to the element 13 including the loose parts collision position P is sequentially traced back, and the elements corresponding to the outflow route are restored. Further, fluid velocity data for each element is stored in the storage unit 8 as a vector 14 (FIG. 6). That is, the flow velocity and its directionality. Since this varies depending on the plant status, it should be changed along with the specific weight data of the fluid depending on the operating status. The average value V of the flow velocity of the elements corresponding to the outflow route is determined. Now, taking the direction of gravitational acceleration as positive, the upward flow velocity V
is acting, the resistance D acting on the loose parts is expressed by the following equation.

[Equation 2] D = (1/2) ρV2 CD Sρ: Specific gravity of fluid V: Flow velocity CD; Resistance coefficient S: Representative area (area receiving drag) Therefore, force acting on loose parts F
teeth

[Formula 3] F=Mg-D g; Gravitational acceleration M; Weight Assuming that it falls while receiving this force, the acceleration is α
given that,

[Equation 4] F=Mα According to numbers 3 and 4,

[Equation 5] α=F/M=g-(D/M) If the installation height of the part that has become a loose part is hT, and the height of the collision point P is hP, the collision energy E is:

[Equation 6] E=Mα(hT - hP)

[0011] Therefore, if the collision energy and position, the flow velocity of the outflow route, and the specific gravity of the fluid are known, it becomes possible to infer the possibility of loose parts. To do this, a parts list including the weight M, resistance coefficient CD, representative surface type S, division element number where the parts are installed, height data, etc. of the parts configuring the device is required, as shown in Figure 7. is stored in the storage unit 8, and parts that may have become loose parts are restored using Equations 2 to 6. The restored parts are displayed on the display section 9.

[0012] If the relationship between collision energy and weight does not match well, it is possible that a part of the part is missing, so it is also important to consider what percentage of each part's weight should satisfy the other conditions. Check. Regarding the outflow route and flow velocity, in this embodiment, the equipment is divided into divided elements, but it is also possible to calculate and determine the outflow route and flow velocity for one part. That is, it is placed in the parts list shown in FIG. 7. This method is expected to result in faster searches. However, assuming that the plant condition changes due to changes in plant load, etc., it is necessary to have multiple conditions for flow velocity, and it is considered better to divide the flow rate into elements that allow easy changes in conditions.

[0013]

[Effects of the Invention] According to the present invention, it is possible to know which parts are likely to be loose parts based on the detected signal, so it is possible to grasp the extent of plant damage and to carry out operations to maintain plant safety. It is possible to provide materials for making a decision (such as suspension, etc.).

[Brief explanation of the drawing]

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

FIG. 2 is an explanatory diagram showing how acoustic signals generated when loose parts collide are detected by a plurality of sensors.

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

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

FIG. 5 is an explanatory diagram showing how a device is divided into elements and an outflow route to a loose part collision position is searched.

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

FIG. 7 is an explanatory diagram of a part list that is a possibility of loose parts.

[Explanation of symbols]

1 Equipment 2 Detector 3 Abnormal noise detection section 4 Reasoning part 5　Position, energy inference section 7 Loose parts inference section 8 Memory section 9 Display section

Claims (1)

[Claims] Claim 1: A monitoring device for loose parts in a fluid flow path of a nuclear reactor system, which includes a plurality of detectors attached to each device constituting the fluid flow path, and an abnormality that senses signals from the detectors. A sound sensing unit, an inference unit that infers the location of the occurrence of loose parts and structures that have become loose parts from the signals detected by the abnormal noise sensing unit, and stores data on the plant structures necessary for the inference. A loose parts monitoring device comprising a storage unit and a display unit that displays inference results.