JPS62144038A - Remote detection and measuring liquid leakage - Google Patents

Abstract

PURPOSE:To detect and measure leakage inexpensively and effectively, by detecting the leakage of a liquid remotely monitoring the dripping of liquid drops at a liquid seal section with a TV camera to measure the leakage level by counting leaking liquid drops. CONSTITUTION:At the bottom of a pressure tube group 1 of a pressure tube type nuclear reactor, the condition of a cooling water from a lower end of one pressure tube 1a dripping in liquid drops 2 is caught with a TV camera 3 set at the position away from the bottom of the reactor. At this point, a zooming function of a TV camera is operated with a camera controller 4 with attentions being paid only to that pressure tube 1a alone causing a leakage among hundreds of pressure tubes, the state of leakage is displayed as a clear image on a monitor TV 5. The video signal is processed to measure the dripping water drops. In this case, for example, one electronic signal is fetched from one scan line SL from a video image 5a of a monitor TV which display the condition that water drops are dripping from the lower end of the pressure tube to identify water drops from the peak potential of changes in the varying potential each time water drops are dripped. This allows the method of determining the size and the number of water drops.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention is applicable to places where humans cannot directly approach, such as radiation environments, harmful gas environments, places where harmful chemicals are handled, high temperature atmospheres, high places, and small spaces. In addition to remotely detecting liquid leakage from liquid seals in locations such as
This concerns a method for quantifying leakage.

The present invention will be described below using an example in which leakage of cooling water from a seal plug provided at the lower end of a pressure tube of a pressure tube nuclear reactor is detected and quantified.

<Prior Art> In a pressure tube nuclear reactor, a reactor core is constructed by arranging a large number of fuel assemblies and primary coolant housed in pressure tubes of appropriate thickness. In this type of reactor, fuel is exchanged from the bottom of the pressure tube, so as shown in Figure 4, the bottom end of the pressure tube 10 is open, and a seal plug 11 is installed at the bottom opening of the pressure tube except when replacing the fuel. The primary cooling water is sealed by a seal portion 12 by attaching a stopper called a plug.

Leakage of primary cooling water from this seal plug is limited to a certain amount or less for radiation protection and Plan 1 maintenance reasons. Therefore, it is necessary to constantly remotely monitor the leakage and remotely quantify the amount of leakage.

For example, as shown in FIG. 4, a method for remotely detecting and quantifying primary cooling water leakage from a seal plug is to attach a secondary seal 13 made of synthetic rubber such as EPDM to the seal plug 11, and to A method is adopted in which the leak detection piping 14 is branched from the leak detection pipe 14 to guide the leaked cooling water to the tank 15, and the water level in the tank is measured. The structure of the seal plug shown in Fig. 4 is based on Utility Model Publication No. 56-5567.
It is well known from Publication No. 5.

<Problems to be Solved by the Invention> However, when constructing a large-scale pressure tube type nuclear reactor with high thermal output, the number of pressure tubes 10 is increased, so the conventional leakage detection and quantitative methods as described above are not possible. If this method is adopted, the number of leak detection pipes 14 increases in proportion to the number of pressure pipes, which not only increases the number of man-hours for installing the pipes, but also requires a cooling means (not shown) to prevent the secondary seal 13 from deteriorating due to heat. Since it is also necessary to install it at the bottom of the pipe, this results in an upper limit on construction costs.

Therefore, the present invention has been made for the purpose of providing a method that can effectively detect leakage of cooling water from a seal plug and quantify the leakage amount at a lower cost and remotely. Ru.

<Means for Solving the Problems> According to the present invention, when cooling water leaks from the seal plug without installing a secondary seal or leak detection piping in the seal plug at the lower end opening of the pressure pipe, The leakage water should drip from the pressure pipe (・2i) as water droplets.
Leakage of cooling water is detected by remotely monitoring the dripping of water droplets with a TV camera, and the amount of leakage is quantified by processing the images shown on the monitor TV and counting the leaking water droplets. Depending on the method, the above objectives can be achieved.

A typical example of a seal plug at the lower end of a pressure pipe to which the method of the present invention can be applied is shown in FIG. The illustrated seal plug structure is known, for example, from Japanese Utility Model Application Publication No. 60-39994.
1 and 2 respectively show the ball latch mechanism.

It is fully foreseeable that leakage from the seal can be detected remotely by capturing dripping of leaking water with a television camera. However, unless the amount of leakage can be quantitatively determined using a single monitor system using a television camera, this method cannot be adopted as a method for detecting leakage from a pressure tube seal plug in a pressure tube nuclear reactor.

Therefore, the present inventors investigated whether it was possible to quantify the amount of water leakage using a single monitor system using a TV camera, and counted the number of water droplets that dripped by processing the video signal of the screen displayed on the monitor TV. This invention was completed by discovering that the amount of leakage can be quantified by doing so.

That is, since the water droplet falls in a spherical shape, if the radius of the water droplet is R, the body of one droplet fffiV becomes. The amount of leakage W that drips from the lower end of the pressure pipe within a certain period of time is the sum of the water droplets that have dripped within that period of h, and thus becomes: Therefore, in principle, the amount of leakage can be determined by knowing the size and number of water droplets that are falling.

Furthermore, if the quantitative accuracy is lowered, the leakage amount W can be determined simply by counting the number of water droplets dripping. In other words, if the radius of the water droplet is (Ra + r) [where Ra represents the average radius of the water droplet], then + (Ra + r ) 3) +3Ra (rl 2 + r2 '' +--ro2).Experiment Find the distribution of the radius of the water droplet by 1r23+・
...10r. 3), it is possible to estimate r1~r
, is smaller than Ra, the leakage ff1W can be quantified within the error range.

<Example> This invention will be explained below with reference to Examples.

FIG. 1 shows the concept of the method of the present invention, in which one pressure tube 1 is installed in the lower part of the pressure tube group of a pressure tube reactor.
A TV camera 3 installed at a distance from the lower part of the furnace captures the situation where cooling water or water droplets 2 are dripping from the lower part of the furnace.

At this time, the zoom function of the television camera is activated using the camera controller 4, and the leak situation is clearly shown on the monitor television 5 by focusing only on the pressure tube 1a where the leak is occurring among the hundreds of pressure tubes. Display it as a video.

By processing this video signal, the falling water droplets are fixed. For example, as shown in Fig. 2, a video signal 5a on a monitor TV showing a situation in which water droplets are dripping from the lower end of a pressure pipe (Fig. 2A)
), the electrical signal of one (or several) scanning line SL is extracted, and the potential change (second
A method of identifying water droplets from the peak potential in Figure B) and determining the approximate size and number of water droplets 2 can be adopted.

Alternatively, as shown in FIG. 3, only the water droplets are converted into a binary image by the image processor 6 from the monitor TV image 5a (FIG. 3A) (FIG. 3B), which corresponds to the water droplets on the image. The method of determining the size and number of water droplets 2 from the width and number of bands (FIG. 3C) can be adopted.

<Effects of the Invention> As can be seen from the above explanation, the method of the present invention has the advantages of the conventional method of detecting and quantifying cooling water leakage from the pressure tube seal plug in a pressure tube nuclear reactor. Seal leak detection piping, secondary seals, and cooling means for the lower part of the pressure pipe are not required, making it possible to perform effective leak detection and constant loss at a lower cost.

Although the above explanation describes an example in which the present invention is applied to detection of cooling water leakage from a pressure pipe seal plug provided in a pressure tube type nuclear reactor, the present invention is not limited to this, and can be applied to a general liquid seal part. It can be widely used for the purpose of remotely detecting liquid leakage from and quantifying the amount of leakage.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the method of the present invention, FIG. 2 is an explanatory diagram showing an example of electrically processing a video signal on a monitor television screen, and FIG. 3 is an explanatory diagram showing an example of electrically processing a video signal on a monitor television screen. An explanatory diagram showing an example of processing using a processing hall, Fig. 4 is an explanatory diagram showing a conventional method for detecting leakage from a seal plug of a pressure tube in a pressure tube nuclear reactor and damage, and Fig. 5 is an explanatory diagram showing the method of this invention. This is an explanatory diagram showing an example of a seal plug structure for a pressure pipe to which the method described above can be applied. DESCRIPTION OF SYMBOLS 1... Pressure tube group, 2... Water droplet, 3... Television camera, 5... Monitor TV, 6... Image processing machine. Patent applicant: Power Reactor and Nuclear Fuel 1 Development Corporation
Fuji Electric Co., Ltd.

Claims (1)

[Claims] 1. Detecting liquid leakage by remotely monitoring the dripping of liquid droplets from the liquid seal part using a television camera,
A remote detection and quantification method for liquid leakage, characterized in that the amount of leakage is quantified by processing a video signal displayed on a monitor television and counting the number of leaking droplets. 2. The method according to claim 1, wherein the counting of droplets by the video signal processing comprises determining the size and number of droplets from changes in potential of a scanning line signal of a monitor television. 3. To count the droplets using the video signal processing, only the droplets are converted into a binary image using an image processor from the monitor TV video, and the size and number of water droplets are determined from the width and number of bands corresponding to the droplets. A method according to claim 1, comprising: