JPS58102127A - System for detecting leakage of liquid metal - Google Patents

Abstract

PURPOSE:To solve the problems of delay indetecting time and fluctuation of background due to dust and the like, by providing bypass lines in a selector valve and liquid metal leakage detecting devices in said lines, thereby preventing the stop of the flow in sampling pipes. CONSTITUTION:A heat keeping member 2, which encircles the outer surface of a sodium pipe 1, is divided into a plurality of parts by separating plates 3. The sampling pipes 4 are connected to said divided parts from the selector valve 11 from which the bypass introducing pipe 16 and a detector introducing pipe 6 are branched. The pipe 4 which is connected to a sampling switching valve 19 by a connecting valve 14, is guided to the sodium leakage detector through the pipe 6. All the pipes 4, which are not connected to the pipe 14, are connected to the pipe 16 by a connecting pipe 15 of a bypass switching valve 20 and guided to the sodium leakage detector. The sampling gas guided to both sodium leakage detectors is returned to the vicinity of the pipe 1 by a circulating pump.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an apparatus for detecting liquid metal leaking in a facility that handles liquid metal, such as sodium, such as a sodium-cooled fast breeder reactor.

TECHNICAL BACKGROUND OF THE INVENTION In facilities that handle liquid metals (e.g. IJ), it is very important to detect sodium leaks from equipment, piping, etc. at an early stage of leakage. In other words, leaked sodium comes into contact with the outside atmosphere and generates corrosive compounds, so if discovery is delayed, there is a risk that equipment and piping will be seriously damaged and the leak will expand. Therefore, it is necessary to reliably detect the initial minute leakage.

Conventionally, as a device for detecting sodium leakage, there is a device that can detect the presence of sodium by short-circuiting electrodes using leakage IJ that has accumulated at the bottom of ash equipment. In this case, it is suitable for medium or large leaks, and one type is used: - detector, - alarm lamp or buzzer.

On the other hand, potential micro leakage detectors include sodium ionization detectors, radiation ionization detectors, and differential pressure detectors. These detectors sample the atmospheric gas around the equipment to be detected for leakage, guide it to the detector, and detect sodium vapor or sodium aerosol in the gas.

A sodium ionization detector uses a filament heated to a high temperature to ionize and detect leaked sodium, and a radiation ionization detector uses a minute amount of radiation to ionize atmospheric gas for detection. A differential pressure detector is a device that installs a filter in the gas flow and detects an increase in the differential pressure across the filter when the filter is clogged with sodium aerosol. US CRBRP
Only important equipment is equipped with small leak detectors using this gas sampling method, and other equipment is equipped with medium to large leak detectors. Needless to say, considering the purpose of the sodium leak detection system, it is desirable to install minute leak detectors throughout the plant. However, this requires a large number of sampling tubes to be installed within the plant, and also a large number of detectors. Therefore, in order to reduce the absolute number of detectors and the number of sampling tubes, a multi-sampling sodium leak detection system using selector pulp was developed.
This is being considered for Japan's nuclear reactor Monjiyu.

Figure 1 shows the schematic configuration of a fast breeder reactor sodium leak detection system employing a multiple gas sampling method. The gas sampling position is an annulus between a liquid metal, for example, sodium pipe 1 and a heat insulating material 2, and this annulus is divided by a partition plate 3 into sections of several meters to several tens of meters. The sampling gas 18 from each region passes through the sampling pipe 4 to the selector valve 5.
By switching the selector valve 5, only one system of sampling piping is connected to the detector introduction pipe 6.

To explain the selector valve 5 in detail with reference to FIG. 2, when one connecting pipe 14 is rotated and connected to the switching terminal 13, the sampling gas 18 is conveyed to the detector introduction pipe 6 only in that system. In other systems, gas flow is stopped and sampling is not performed. In this way, one of the connecting pipes 14 is a selector valve 5 that switches sequentially while rotating. The sampling gas connected to the detector introduction pipe 6 and introduced into the sodium leak detector 7 is detected for sodium by the detector 7, the flow rate is controlled by the flow rate controller 8, and the sampling gas is sent to the vicinity of the sodium pipe 1 by the circulation pump 9. be returned.

Problems with the Background Art When this large-volume gas sampling method is adopted, the gas flow stops in the sampling pipe 4 which was not connected to the detector introduction pipe 6 by the selector valve 5, so the selector valve 5 is switched and sampling starts. In some cases, there are problems such as delays in gas transport from the sampling point and movement during detection until the gas flow reaches a steady state. Another disadvantage is that sodium leakage cannot be detected at all in areas where sampling is not performed.

Purpose of the Invention The present invention has been made to eliminate the drawbacks of the above-mentioned sodium leakage detection system, and by adopting a multiple sampling method and covering the first drawback, the absolute number of detectors can be reduced and leak detection with high reliability can be achieved. The object of the present invention is to provide a detection system.

The structure of the invention, that is, the present invention is a liquid metal leak detection system characterized in that a bypass line is provided in the selector valve and a liquid metal leak detector is installed in the line in order to prevent the flow of the sampling pipe from being stopped.

Embodiment of the Invention An embodiment of the liquid metal leak detection system according to the present invention will be described below with reference to FIGS. 3 and 4.

In Fig. 3, the same parts as in Fig. 1 are indicated by the same reference numerals, and the explanation of the overlapping parts will be omitted. Each part of the heat insulating material 2 surrounding the liquid metal, for example, sodium pipe, is divided into a plurality of parts by a partition plate 3, and a sampling pipe 4 is connected to each divided part, and each sampling pipe is connected to a selector valve 11. be done.

A bypass line 12 and a sampling line 17 are connected to the selector valve 11 . Both of these lines12.17
consists of an inlet pipe 16, a sodium leak detector 7, a flow rate controller 8, and a circulation pump 9, and the gas sampled through the return pipe 10 is recovered or returned after being detected by the detector. Sampling gas 1 for each part
8 is led to the selector valve 11 by the sampling pipe 4,
Here, as shown in FIG. 4, the sampling line 6 is separated on the sampling switching valve 19 side, and the 5th line 16 is separated on the bypass switching valve 20 side.

Effect of the Invention The sampling pipe 4 connected to one of the connecting pipes 14 of the sampling switching valve 19 is
It is not connected to the bypass introduction pipe 16 of the side line but passes through the detector introduction pipe 6) and is led to the IJ leak detector 7. In addition, all the sampling pipes 4 that are not connected to one of the connecting pipes 14 are connected to the other connecting pipes 15 of the connecting pipe 16JC of the passing switching valve 20.
It is guided to the IJum leak detector 7. In this way, the selector valve 11 is operated by sequentially switching one connecting pipe 14 and the other connecting pipes 15 while rotating in an open direction.
Sampling gas 18 led to IJum leak detector 7
Each sodium is detected by these two detectors, the flow rate is controlled by a flow rate controller 8, and the sodium is returned to the vicinity of the sodium pipe 1 by a circulation pump 9.

Effects of the Invention In the sodium leak detection system configured as described above, by providing the bypass line 12 in the selector valve, it becomes possible to circulate all the sampling gas 18 that is not introduced into the sampling line 17. Therefore, it becomes possible to solve the problem of the delay in gas transport from the sampling point caused by the stoppage of the gas flow, and the steady state of the gas flow. Furthermore, by superimposing the sodium leak detector 7 on the bypass line 12, it has become possible to detect sodium leaks even in areas where sampling is not performed.

As explained above, the present invention makes it possible to solve the drawbacks of the multiple sampler system by providing the bypass line 12 to the selector valve 11 and further providing the liquid metal leakage detector 7 to the bypass line. Therefore, it is possible to reduce the total number of liquid metal leakage detectors and provide a highly reliable leakage system, which has a significant effect on improving the safety of facilities that handle liquid metals.

FIG. 5 is a system diagram showing another embodiment of the present invention, and the same parts as in FIG. 3 are designated by the same reference numerals, and the explanation of the overlapping parts will be omitted.

The embodiment shown in FIG. 5 shows a sodium leak detection system for a fast breeder reactor. A large number of pipes 1 are surrounded by a heat insulating material 2 in a nitrogen atmosphere inside a containment vessel wall 21, and a sampling pipe 4 leaking from each pipe 1 is connected to a selector valve 11 via a shutoff valve 22. The outside of the containment vessel a21 is an air atmosphere. A bypass line 12 and a sampling line 17 are connected to the selector valve 11 .

The bypass line 12 is provided with a pulp 23, a filter 24, and a pulp 25 in addition to the portion shown in FIG. Further, a branch pipe 26 is connected to the sampling line 17, and this branch pipe 26 includes a valve 27, a filter 28, and a valve 26.
9 and a flow meter 30 are connected.

The detection tube 31 of the sampling line 17 contains pulp 32,
Detector 7, filter 28, pulp 29° and flow meter 8
are connected, and the terminals of the branch pipe 26 and the detection pipe 31 are joined together and connected to a circulation pump via a pulp 33.

Thus, although the above embodiment has the same effects as the embodiment shown in FIG. 3, it is possible to detect sodium leakage without stopping the flow of all the sampling pipes. Therefore, a highly reliable sodium leakage detection system can be provided.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a conventional detection system, Fig. 2 is a system diagram showing a selector valve of the detection system in Fig. 1,
FIG. 3 is a configuration diagram showing an embodiment of the liquid metal leakage detection system according to the present invention, FIG. 4 is a schematic system diagram showing the selector valve of the detection system in FIG. 3 expanded, and FIG. 5 is a diagram showing the present invention. It is a system diagram showing another example of. 1...Sodium piping, 2...Heat insulation material, 3...
・Shikiri plate, 4... Sampling tube, 5.
... Selector valve, 6... Detector introduction pipe, 7...
・Sodium leak detector, 8...Flow rate control device, 9...Circulation pump, 10
...Return piping, 11...Selector valve, 12.
...Bypass line, 13 river switching terminal, 14...One connection pipe 15...Multi-way connection pipe, 16...Bypass introduction pipe, 17...Sampling line, 18...Sampling gas, 19. ... Sampling switching valve, 20... Bypass switching valve. Application agent Patent attorney Gobe Kikuchi

Claims (6)

[Claims] (1) A plurality of sampling pipes that lead out the sampling gas around the liquid metal channel wall, a selector valve connected to the plurality of sampling pipes, a liquid metal leak detector connected to the selector valve, and a liquid metal leak detector connected to the selector valve. It is equipped with a circulation pump that takes in the sampling gas, a return pipe connected to the discharge side of the circulation pump, and a bypass line provided between the return pipe and the selector valve and with a liquid metal leak detector interposed therebetween. A liquid metal leak detection system characterized by: (2) Multiple sampling tubes that lead out ambient gas from different points on the liquid metal channel wall, and the outlet side of these sampling tubes is sequentially switched to connect to the detector introduction tube, and unconnected sampling tubes are bypassed. A selector valve connected to the line, a liquid metal leak detector installed in the detection introduction pipe on the downstream side of this selector valve, and a sampling gas intake installed on the downstream side of this leak detector. 142. The liquid metal leak detection system according to claim 141, further comprising a circulation pump and a bypass line for the leak detector connected to the selector valve on the downstream side of the selector valve. (3) The sampling line is provided with a circulation pump with a small circulation amount, and the bypass line is provided with a circulation pump with a large circulation amount. Liquid metal leak detection system. (4) The liquid metal leak detection system according to claim 1 or 2, characterized in that a liquid metal leak detector is provided in the bypass line. (5) A flow rate control device is provided in the t# printer line and the bypass line, and the downstream flow of the control device is combined to provide one circulation pump with a large circulation amount. The liquid metal leak detection system according to item 1 or 2. (6) A selector valve having a one-way connection pipe for connecting the sampling pipe to the detector introduction pipe and a multi-way bypass connection pipe for connecting the other sampling pipe not connected to the detection introduction pipe to the bypass introduction pipe. 3. A liquid metal leakage detection system according to claim 2, further comprising: