JPS6260015B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a leak detection device for a lining tank in which a concrete wall is lined with a metal liner plate.

BACKGROUND ART Lining tanks, in which a concrete wall is lined with a liner plate such as a stainless steel plate, are used for radioactive material storage tanks such as fuel pools, equipment storage pits, and waste liquid storage pools in nuclear power plants. When lining the liner plate, a mounting bracket is embedded in the concrete wall in advance so as to be exposed on the wall surface, and the liner plate is welded to the mounting bracket. However, in such a configuration,
A gap is created between the concrete wall and the liner board. This gap is normally within 5 mm, but if the liner plate is damaged for some reason, the activated liquid in the storage tank will leak and accumulate in the gap. In addition, damage to the liner board must be detected early and appropriate repairs performed, but in this case, it is extremely difficult to remove the liquid that has accumulated in the gap between the concrete wall and the liner board, and it is necessary to continue as it is. If left untreated, workers repairing the liner plates may be exposed to radiation. Another problem was that dew condensation easily formed on the back surface of the liner plate, and it was difficult to distinguish between such condensation and liquid leakage.

The present invention was developed based on the above circumstances, and its purpose is to quickly remove condensation or leaked liquid that has accumulated in the gap between the concrete wall and the liner plate, and to quickly detect leakage. This makes it possible to repair damaged parts of the liner plate quickly, and it is also possible to distinguish between condensation on the back side of the liner plate and liquid leakage, and it is also possible to quickly remove residual substances in the gap. An object of the present invention is to provide a leak detection device for a lining tank.

That is, the leak detection device for a lining tank according to the present invention includes a cleaning liquid supply piping system that communicates with a gap between a concrete wall and a liner plate lined with the concrete wall, and a cleaning liquid supply piping system that communicates with the gap between the concrete wall and the liner plate lined at the bottom of the concrete wall. and a dry gas supply piping system that supplies dry gas into the liquid outflow piping system and the gap.

With this configuration, condensation or leaked liquid accumulated in the gap between the concrete wall and the liner plate can be quickly removed through the liquid outflow piping system, and leakage can be detected quickly. Repairs can be carried out quickly, and condensation and leaked liquid can be easily distinguished by detecting the physical properties of the liquid flowing through the liquid outflow piping system. Further, by supplying the cleaning liquid into the gap through the cleaning liquid supply piping system and letting the cleaning liquid flow out through the liquid outflow piping system, residual substances in the gap can be easily removed. By circulating dry gas through the gap, it is possible to reliably remove dew condensation adhering to the inner surface of the concrete wall or the back surface of the liner plate and dry the concrete wall.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In the figure, 1 is a lined tank used as a radioactive material storage tank (for example, a fuel pool, equipment storage pit, waste liquid storage pool, etc.) in a nuclear power plant. This lining tank 1 is formed by lining a concrete wall 2 with a liner plate 3 such as a stainless steel plate.

In the side wall portion of the concrete wall 2, a plurality of embedded fittings 4 made of angle material or the like are embedded flush with the inner surface of the concrete wall 2 and in the horizontal direction. As shown in FIG. 2, a plurality of rod-shaped anchors 5 are welded to the back surface of each embedded metal fitting 4 to firmly fix the embedded metal fitting 4 to the concrete wall 2. The uppermost embedded metal fitting 4 is located at the upper end portion of the liner plate 3, and the upper edge of the liner plate 3 is continuously welded to the uppermost embedded metal fitting 4 in a liquid-tight manner. In addition, for the embedded metal fittings 4 of the second stage and below, a through hole is provided in the liner plate 3 and the through hole is welded to the embedded metal fitting 4, so that the liner plate 3 is brought into close contact with the concrete wall 2. It is considered. However, between the embedded fittings 4 and 4, there is a gap 6 of less than 5 mm between the concrete wall 2 and the liner plate 3, and at the upper end of the liner plate 3, there is a cleaning liquid supply pipe that communicates with the gap 6. System 7 is connected.

The cleaning liquid supply piping system 7 is for allowing the cleaning liquid 9 in the cleaning liquid supply tank 8 installed above the storage tank 1 to flow into the gap 6.
A main pipe 10 is arranged in an annular manner along the inner surface of the concrete wall 2 at an upper position, and the main pipe 10 and the upper end of the gap 6 are communicated with each other by a plurality of branch pipes 11 for each independent gap 6, The supply tank 8 and the main pipe 10 are connected by a cleaning liquid supply pipe 12. In addition, each branch pipe 1
1 has a normally open valve 13, and the supply pipe 12 has a normally closed valve 14.
are respectively inserted, and a normally open atmosphere communication valve 15 is connected to the upper wall of the main pipe 10. Also, main manager 1
0 is support 16 identified on concrete wall 2
is supported via U-bolts 17.

Note that the upper and lower gaps 6, 6 of the supporting metal fittings 4 of the second stage and below are communicated via a communication pipe 18 buried in the concrete wall 2. Similarly, the upper gap 6 of the lowest support metal fitting 4 and the gap 6 at the bottom of the lining tank 1 are also communicated via a communication pipe 18 (however, this portion is not shown).

On the other hand, below the lining tank 1, there is a liquid outflow piping system 1 that communicates with the gap 6 between the concrete wall 2 and the liner plate 3 at the bottom of the lining tank 1.
9 is provided. This liquid outflow piping system 19 is
A plurality of branch pipes 20 are provided that penetrate the bottom of the concrete wall 2, and each independent gap 6 at the bottom of the storage tank 1 is communicated with a main pipe 21 via each branch pipe 20, and this main pipe 21 is connected to a drain tank 22. ,
The drain tank 22 is further connected to a building drainage system (not shown) via a drainage pipe 23. Note that each branch pipe 20 is equipped with a sight glass 2.
4 is inserted in the drain pipe 23, and a normally closed valve 25 and a normally open valve 26 are inserted in series in the drain pipe 23. Also,
A liquid level detector 27 that detects the liquid level in the tank 22 is connected to the drain tank 22, and when the liquid level in the tank 22 reaches a certain level, the detector 27 is activated and sends an operation signal to the alarm 28. is configured to send out. Further, a portion of the drain pipe 23 between the normally closed valve 25 and the normally open valve 26 is communicated with the upper part of the drain tank 22 via a branch pipe 29.

30 in the figure is a dry gas supply piping system that supplies dry gas to the gap 6 between the concrete wall 2 and the liner plate 3. This piping system 30 includes the branch pipe 2
A pressure gauge 32, a normally closed valve 33, and an exhaust pump 34 are connected in series from the branch pipe 29 side to the exhaust pipe 31 connecting the building exhaust system 9 and the building exhaust system (not shown). At the same time, a nitrogen gas cylinder 35 is connected between the pressure gauge 32 and the normally closed valve 33 via a gas supply pipe 36, and a normally closed valve 37 and a pressure reducing valve 38 are connected to the supply pipe 36, and a normally closed valve 37 and a pressure reducing valve 38 are connected to the exhaust pipe. A communication pipe 39 is inserted in series from the 31 side toward the gas cylinder 35, and furthermore, between the normally closed valve 37 and the pressure reducing valve 38 of the gas supply pipe 36, a communication pipe 39 is connected to the lower part of the cleaning liquid supply pipe 12. It is configured by connecting. Note that a normally closed valve 40 is inserted into the communication pipe 39.

In the above configuration, if the liner plate 2 is damaged for some reason and the liquid (for example, water) 41 in the lining tank 1 leaks into the gap 6 between the concrete wall 2 and the liner plate 3, the leaked liquid will be Flowing down within the gap 6, the branch pipe 20 of the liquid outflow piping system 19
The water is stored in the drain tank 22 via the main pipe 21. Therefore, when the liquid level in the drain tank 22 reaches a certain level, the liquid level detector 27 is activated and sends an operation signal to the alarm 28, and the alarm 28 emits an alarm sound, light, or display. This allows the operator to know that a leak has occurred and to take appropriate measures promptly. In addition, the leaked liquid flowing down inside the branch pipe 20 is stored in the sight glass 2.
Since it is visible from the outside through 4, the operator can also know the fact that a leak has occurred. In this case, as the liquid level in the storage tank 1 gradually decreases, the branch pipe 2
If the flow state in the tank 0 is continuously monitored and the stoppage of flow is confirmed, the liquid level at that time will indicate the position of damage to the liner plate 3. Therefore, the location of damage to the liner plate 3 can be easily discovered. Note that the leakage continues until the flow in the branch pipe 20 is stopped, and this leaked liquid is led to the building drainage system through the branch pipe 29 connected to the upper part of the drain tank 22, and is drained as appropriate. There is no problem as it will be processed.

In addition, there was no damage to the liner plate 3, and the liquid 41
Even if there is no leakage, condensation formed on the back side of the liner plate 3 may flow down the gap 6 and flow through the branch piping 20, and this may become visible in the sight glass 24. If so, it has not been activated, so if the radiation dose of the liquid in the drain tank 22 is measured using a Geiger counter or the like, it is easy to distinguish between dew condensation and leakage. If there is condensation, it is not that large and you can leave it as it is, but if leakage occurs due to damage to the liner plate 3 during that time, there is a risk that it will be overlooked, so even if there is condensation, do not leave it as is. It is desirable to remove condensation within the gap 6 as soon as possible.

In this case, first, the normally open valve 26 of the drain pipe 23 is closed, the normally closed valve 33 of the exhaust pipe 31 is opened, and the exhaust pump 34 is operated. Then, the vaporized condensation that flows down into the drain tank 22 is guided to the indoor exhaust treatment system through the exhaust pipe 31 and treated as appropriate. Next, the normally closed valve 3 of the gas supply pipe 36
7 is opened and dry gas is supplied from the nitrogen gas cylinder 35 to the drain tank 22, main pipe 21, branch pipe 22 and the gap 6, and at the same time the exhaust pump 34 is operated, the dry gas supply piping system 30 and the gap 6 are The interior can be highly dry. Also,
By filling the gap 6 with dry nitrogen gas, it is possible to prevent corrosion of the embedded fittings 4 and prevent deterioration of the concrete wall 2 due to neutralization. It should be noted that the drying gas is not limited to nitrogen, and other stable gases such as argon can of course be used, but nitrogen gas has the advantage of being easily and inexpensively available.

Further, when damage to the liner plate 3 is discovered and repaired, it is necessary to remove all residual substances in the tank to prevent workers from being exposed to radiation. Therefore, the normally closed valve 25 of the liquid outflow piping system 19 is opened,
Close the atmosphere communication pipe 15 of the cleaning liquid supply piping system 7,
Further, after closing all the normally open valves 13 except for the necessary ones, the normally closed valve 14 is opened.
Then, the clean liquid (for example, fresh water) 9 in the clean liquid supply tank 8 is transferred to the clean liquid supply pipe 12 and the main pipe 10.
The remaining substances that flow into the gap 6 through the branch pipe 11 and adhere to the back surface of the liner plate 3 or the inner surface of the concrete wall 2 are removed and sent to the drainage system in the building via the drain tank 22. Also,
To remove the cleaning liquid 9 remaining in the gap 6, as described above, open the normally closed valve 33 of the dry gas supply piping system 30 and operate the exhaust pump 34, and then open the normally closed valve 37 to remove the cleaning liquid 9 from the gap 6. 6 may be supplied with dry nitrogen gas. Alternatively, the normally closed valve 40 may be opened to supply dry nitrogen gas from the nitrogen gas in the gas cylinder 35 into the gap 6 through the communication pipe 39 and the cleaning liquid supply pipe 12. There is an advantage that the interior of the supply arrangement 12, the main pipe 10, and the branch pipes 11 of the supply piping system 7 can also be dried. In addition, dry nitrogen gas is supplied to the cleaning liquid supply piping system 7 and mixed with the cleaning liquid 9,
By spraying it into the gap 6 in the form of a mist, the residual substance in the gap 6 can be removed even more effectively and quickly. Furthermore, by repeating the supply of the cleaning liquid 9, the liquid discharge, the exhaust by the exhaust pump 34, and the nitrogen gas supply several times, the effect of removing residual substances can be further enhanced. Further, as the cleaning liquid 9, in addition to fresh water, an organic solvent such as alcohol or acetone, a neutral detergent, or the like may be used, thereby increasing the cleaning effect in the gap 6 and the removal of residual substances.

Furthermore, by keeping the atmosphere communication valve 15 open at all times, damage to the liner plate 3 can be prevented in the event that the pressure within the gap 6 increases for some reason. can be prevented.

Note that the equipment for each piping system does not need to be permanently provided, but may be installed as needed.

As detailed above, according to the present invention, a cleaning liquid supply piping system is communicated with the gap between the concrete wall and the liner plate, and a liquid outflow piping system is communicated with the gap at the bottom of the concrete wall, Furthermore, by providing a dry gas supply piping system for supplying dry gas into the gap and inside the liquid outflow piping system,
Condensation or leaked liquid accumulated in the gap can be quickly removed through the liquid outflow piping system, and it is also possible to distinguish between condensation and leakage by detecting the physical properties of the liquid flowing through the liquid outflow piping system. ,
In addition, leaks can be detected quickly and damaged parts of the liner plate can be quickly repaired, and residual substances in the gap can be quickly removed by supplying cleaning fluid through the cleaning fluid supply piping system. Furthermore, it is possible to provide a leakage detection device for a lining tank that can quickly dry the inside of the gap by supplying drying gas through a drying gas supply piping system.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic configuration diagram showing the relationship between the lining tank and various piping systems, and FIG. 2 is a partial sectional view of the lining tank. 1... Lining tank, 2... Concrete wall,
3... Liner plate, 6... Gap between concrete wall and liner plate, 7... Cleaning liquid supply piping system, 19
...Liquid outflow piping system, 30...Dry gas supply piping system.

Claims (1)

[Scope of Claims] 1. A concrete wall, a liner plate lined with the concrete wall, and a liquid outflow piping system provided at the bottom of the concrete wall to communicate with a gap between the concrete wall and the liner plate. A leak detection device for a lining tank, comprising: the liquid outflow piping system; and a dry gas supply piping system that supplies dry gas into the gap between the concrete wall and the liner plate. 2. The liquid outflow piping system is configured to allow liquid present in the gap between the concrete wall and the liner plate to flow out into the building drainage system through a sight glass and a drain pot in sequence. The leakage detection device for a lining tank according to item 1.