Leakage detection device

Abstract

[Problem] To provide a leakage detection device for automatically detecting leakage of a fluid from a buried tank or piping. [Solution] Part of an oil filler pipe 11 is buried underground, and said part is configured as double piping 30 including a first pipe 31 serving as the oil filler pipe and a second pipe 32 covering the first pipe 31. A detection sensor 15 for detecting leakage of an organic solvent is arranged between the first pipe 31 and the second pipe 32. The detection sensor 15 is connected to a leakage detection device 21 of a leakage detector panel 20 via a lead wire 25. In this way, when the organic solvent leaks from the first pipe 31, the leakage detection device 21 detects the leakage by means of the detection sensor 15, causes a buzzer 22 to emit sound, and notifies a person in charge of leakage of the organic solvent.

Description

Leak Detection Device

[0001] The present invention relates to buried tanks and underground piping at fueling facilities such as gas stations that store oils such as gasoline and organic solvents, fuel tanks installed in shelters, and the double-shell structure of such fuel tanks and buried tanks, and in particular to a leak detection device used in double piping and double-shell structures of buried tanks that detects oil leaks and organic solvent leaks, automatically reports oil leaks, etc., and enables prompt maintenance.

[0002] Some liquids stored in buried tanks or fluids flowing through pipes are considered hazardous materials. Even a small leak of a hazardous fluid from a buried tank or pipe or other structure requires immediate action.

[0003] A shelter is a facility designed to protect people from dangers such as natural disasters or weapon attacks, and allows people attempting to evacuate to be isolated from the outside. For example, a nuclear shelter, which is a type of shelter, is a facility designed to protect people from a nuclear attack, and in some foreign countries, the prevalence rate of such shelters is 100%.

[0004] Dangerous situations usually continue for a certain period of time. For this reason, shelters, for example, are designed to allow people to stay in them for a certain period of time without going outside. While isolated from the outside world by the shelter, people who have taken refuge in the shelter (hereafter referred to as "evacuees") need to eat. It is also desirable to maintain an environment in which evacuees can gather necessary information.

[0005] This is because collecting the necessary information will allow more appropriate actions to be taken. For example, by gathering information, evacuees will be able to know when they should evacuate from the shelter they are currently in, or when they will be able to leave the shelter. To avoid confusion, from here on, unless otherwise specified, food will be used to include drinks such as water.

[0006] It is believed that information gathering is often done using electronic devices such as radio receivers, smartphones, and other communication devices. Therefore, it is desirable to keep electronic devices in usable condition as much as possible.

[0007] In renewable energy power generation such as solar power generation or wind power generation, equipment such as solar panels or wind turbines must be installed outside. In situations where people are in danger, such as during war or disaster, such equipment may not be able to maintain its integrity. For this reason, shelters with power generation equipment installed inside the shelter body have been considered (see, for example, Patent Document 1).

[0008] JP 2014-82046 A

[0009] The power generating equipment installed inside the shelter body is, for example, an internal combustion engine such as a diesel generator, or a fuel cell. Such power generating equipment usually generates electricity using flammable fuel. Therefore, when installing such a power generating equipment, it is necessary to also prepare a fuel tank to store the fuel.

[0010] The shelter itself allows evacuees to stay in a shelter that is isolated from the outside world. To enable isolation from the outside world, the inside of the shelter itself is usually an enclosed space. Therefore, the risk of fuel leaking from the fuel tank or the piping connected to the fuel tank is likely to become more serious. Some fuels are harmful to the human body. For this reason, it is considered important to further reduce the risk of fuel leaks in shelters that have fuel tanks installed inside for fuel storage.

[0011] Therefore, the present invention provides a shelter equipped with a leakage detection device that can further reduce the risk of leakage of fuel used in power generation equipment, etc.

[0012] The present invention also relates to a leak detection device used in the double-shell structure of buried tanks and buried pipes, which detects oil leaks and organic solvent leaks, especially in buried tanks and underground pipes at fueling facilities such as gas stations that store oils such as gasoline and organic solvents, automatically reports oil leaks, etc., and enables prompt maintenance.

[0013] A shelter according to one embodiment of the present disclosure comprises a shelter equipped with a leak detection device that includes a shelter body capable of isolating evacuees from the outside, a fuel tank installed within the shelter body and used to store fuel, a power generation device capable of consuming the fuel, piping for supplying the fuel from the fuel tank to the power generation device, and a covering member that covers at least a portion of the piping from the outside and isolates the portion.

[0014] Furthermore, one aspect of the leak detection device of the present disclosure is a pipe or tank buried underground, in which a first layer and a second layer are formed inside a structure in which a fluid is stored or flowed so as not to leak the fluid, and a detection sensor for detecting the fluid is disposed between the first layer and the second layer, and the detection sensor detects the fluid leaking from the first layer.

[0015] The present invention can automatically detect fluid leaks from buried tanks or pipes, and can provide a shelter equipped with a leak detection device that can further reduce the risk of fuel leaks used in power generation equipment, etc.

[0016] In addition, a leak detection device can be provided for use in double piping and the double-shell structure of buried tanks, which detects oil leaks and organic solvent leaks in buried tanks and underground piping at fueling facilities such as gas stations that store oils such as gasoline and organic solvents, automatically reports oil leaks, etc., and enables prompt maintenance.

[0017] 13 is a diagram illustrating an application example of a leak detection device according to one embodiment of the present invention. FIG. 14 is a perspective view of a double pipe. FIG. 14(a) is a cross-sectional view of the pipe (cross-sectional view taken along line B-B in FIG. 2), and FIG. 14(b) is an enlarged view of the dotted circled portion A in FIG. 13(a). FIG. 14 is a diagram illustrating the structure of a pipe for extracting a detection sensor to the outside. FIG. 14 is a diagram illustrating an application example of a leak detection device according to another embodiment of the present invention. FIG. 14 is a diagram illustrating the cross-sectional configuration of an underground tank. FIG. 14 is a diagram illustrating an example of the structure of the inner surface layer at the location where the detection sensor is arranged. FIG. 14 is a diagram illustrating an example of a method for connecting hollow glass fibers. FIG. 14 is a diagram illustrating an example of the structure of the inner surface layer at the end of a hollow glass fiber. FIG. 14 is a diagram illustrating an example of the structure of a penetration portion where a detection sensor penetrates the inner surface layer. FIG. 14 is a diagram illustrating an example of a connection portion. FIG. 14 is a cross-sectional view showing an example of a shelter according to another embodiment of the present invention. FIG. 14 is a plan view showing an example of a shelter according to another embodiment of the present invention. FIG. 14 is a diagram illustrating an example of a cross-sectional view taken along line A-A' in FIG. 13. FIG. 14 is a diagram illustrating an example of a cross-sectional view taken along line B-B' in FIG. 13.

[0018] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Note that the embodiment described below is merely an example, including modifications, and the technical scope of the present invention is not limited to this. Various modifications are also included within the technical scope of the present invention.

[0019] FIG. 1 is a diagram illustrating an application example of a leak detection device according to an embodiment of the present invention. The application example shown in FIG. 1 is for detecting a leak in a pipe for injecting a fluid into an underground tank buried underground or for sucking a fluid from the underground tank. The fluid is considered to be a hazardous material. Here, the fluid is assumed to be an oil such as gasoline or an organic solvent such as toluene or methylcyclohexane, and the pipe for detecting a leak is assumed to be an oil filling pipe.

[0020] It is expected that organic solvents will be widely used at hydrogen stations, etc. Given the toxicity of organic solvents and the background to their occurrence, it is considered important to be able to reliably detect organic solvent leaks as early as possible.

[0021] Reference numeral 41 in FIG. 1 denotes an inspection hatch for the buried tank. The oil filler pipe 11 is exposed from underground through the inspection hatch 41 installed at the top of the buried tank. It is difficult to visually detect gasoline or organic solvent leaks from the underground portion of the oil filler pipe 11. For this reason, this example is applied to enable automatic detection of leaks occurring in the underground portion of the oil filler pipe 11. For this reason, the underground portion of the oil filler pipe 11 is connected to the oil filler pipe 11 by welding or the like, forming a double pipe 30 having a first pipe 31 (first layer) used as the oil filler pipe, and a second pipe 32 (second layer) covering the first pipe 31.

[0022] The oil supply pipe 11 and the double pipe 30 are connected inside the connection box 10. The oil supply pipe 11 is connected to the first pipe 31 via a flange 12. Another flange 42 exists inside the inspection hatch 41, and the double pipe 30 is formed between these two flanges 12, 42.

[0023] The connection box 10 is also provided with a lead wire 25 and a pipe 13 into which a detection sensor 15 for detecting leakage is inserted. The detection sensor 15 is a sensor cable whose capacitance changes depending on, for example, an organic solvent. A seal 14 is provided to prevent water or the like from entering the pipe 13.

[0024] The detection sensor 15 is inserted between the first pipe (primary pipe) 31 and the second pipe (secondary pipe) 32 of the double pipe 30, from the flange 12 to the flange 42. This causes the capacitance of the detection sensor 15 to change if a leak occurs in either of the first pipes 31.

[0025] 2 is a perspective view of the double pipe 30. As shown in the figure, the double pipe 30 has a primary pipe 31 made of resin covered by a secondary pipe 32 made of the same resin, and a gap 9 of a predetermined width is formed between the primary pipe 31 and the secondary pipe 32. The detection sensor 15 described above is disposed in this gap 9. The primary pipe 31 and the secondary pipe 32 are not limited to being made of thermoplastic resin such as polyethylene or polyamide, but may also be made of thermosetting resin such as phenolic resin or epoxy resin.

[0026] Fig. 3(a) is a cross-sectional view of the piping 30 (cross-sectional view taken along line B-B in Fig. 2), and Fig. 3(b) is an enlarged view of the dotted circled portion A in Fig. 3(a). As described above, the double piping 30 has a double structure, with the secondary piping 32 covering the primary piping 31. Furthermore, as shown in Figs. 3(a) and 3(b), the detection sensor 15 is disposed in the gap 9 between the primary piping 31 and the secondary piping 32 to detect leakage from the primary piping 31.

[0027] This detection sensor 15 is disposed linearly on the lower surface of the primary pipe 31 (upper surface of the secondary pipe 32). Therefore, even if toluene, for example, flowing inside the primary pipe 31 leaks from a defect formed in the primary pipe 31, the leaked toluene flows down along the outer surface of the primary pipe 31 and can be reliably detected by the detection sensor 15. Furthermore, the secondary pipe 32 acts as a receptacle, preventing leaked toluene, alcohol, etc. from flowing outside and contaminating the soil.

[0028] FIG. 4 shows the structure of the piping for taking out the detection sensor 15 to the outside. This double piping 30 is basically a double piping structure consisting of the above-mentioned primary piping 31 and secondary piping 32, but is provided with a wiring outlet 1 for taking out the detection sensor 15 to the outside, and the detection sensor 15 is taken out to the outside of the double piping 30 from the wiring outlet 1 via an outlet pipe 2.

[0029] In addition, the double pipe 30 (e.g., double pipe 3) shown in the same figure is connected to the front and back of the aforementioned normal double pipe 30 (e.g., double pipe 4), and these double pipes 3 and 4 are connected in multiple numbers, and the above-mentioned detection sensor 15 is wired through all of the double pipes.

[0030] By wiring the detection sensor 15 in a straight line along the underside of the double pipe 30 in this way, even if a leak occurs from a defective part of the pipe, the detection sensor 15 can reliably detect the leak and notify the oil leak detection monitor via the cable.

[0031] 1, the detection sensor 15 is connected to the safety barrier 23 via a lead wire 25. The leak detector panel 20 automatically detects leaks that occur in the first pipe 31 and notifies the user when a leak is detected. For this purpose, the panel is equipped with a leak detector 21 and a buzzer 22.

[0032] The leak detection device 21 detects, for example, a change in capacitance of the detection sensor 15 as a change in voltage value via a lead wire 25, and determines the presence or absence of a leak in the first pipe 31 from the detected voltage value. To this end, the leak detection device 21 is connected to a DC (Direct Current) terminal 24 to which a direct current voltage is applied, and is also grounded. The presence or absence of a leak is determined, for example, by comparing the detected voltage value with a threshold value determined for each type of organic solvent.

[0033] When the leak detection device 21 identifies that a leak has occurred, it sounds a buzzer 22 to notify the person in charge, allowing the person in charge to immediately respond to the organic solvent leak. By responding immediately, it is possible to minimize damage caused by the leak.

[0034] In this way, in this example, the piping portion where leakage should be detected is double piping 30, and detection sensor 15 is disposed between first pipe 31 and second pipe 32 within double piping 30. Thus, detection sensor 15 is used to automatically detect leakage occurring in first pipe 31.

[0035] Therefore, even if the pipe or a part of it is buried underground, where it is difficult to see, it is possible to automatically detect a leak. Furthermore, when a leak is detected, the buzzer 22 sounds, allowing the person in charge to immediately become aware of the fact, making it easier to minimize the amount of leaked organic solvent. This also minimizes damage caused by the leaked organic solvent.

[0036] Even if damage such as a hole or crack occurs in the first pipe 31, it does not necessarily mean that damage such as a hole or crack will also occur in the second pipe 32. Even if damage occurs in the second pipe 32, the amount of organic solvent leaking from the second pipe 32 will be smaller than the amount of organic solvent leaking from the first pipe 31. This also makes it possible to further reduce damage, etc., caused by the leakage of organic solvent.

[0037] The type of detection sensor 15 that detects leaks is not particularly limited. The reason why the detection sensor 15 that is a sensor cable is used is because it can easily accommodate even long double pipes 30. The type of detection sensor 15 may be changed depending on the length or area where leaks should be detected. The outer second pipe 32 only needs to cover the entire first pipe 31, so it may be a component that is attached after the first pipe 31 is connected by welding or the like.

[0038] Fig. 5 is a diagram illustrating an application example of a leak detection method according to another embodiment of the present invention. The application example shown in Fig. 5 is for detecting the leak of an organic solvent stored in an underground tank buried underground. In Fig. 5, the same or essentially the same components as those in Fig. 1 are designated by the same reference numerals.

[0039] In this example, the leak detector panel 20 and the connection hole 41 are connected by a pipe 61, and a lead wire 25 is passed through the pipe 61. Furthermore, the underground tank 50 has a multi-layered inner layer 52 (first layer) formed on the inner surface of a steel plate 51 (second layer). The detection sensor (sensor cable) 15 is disposed between the inner layer 52 and the steel plate 51. The detection sensor 15 is disposed between points A and B in FIG. 5. Therefore, it is sufficient that the inner layer 52 is formed at least between points A and B. The detection sensor 15 and the lead wire 25 are connected by a connection part 45.

[0040] FIG. 6 shows the cross-sectional structure of the underground tank 1, and is a view showing the D-D' cross section of the underground tank 1 shown in FIG. 5. As shown in the figure, the underground tank 1 is composed of an inner surface layer 52 and a steel plate 51, with hollow glass fiber disposed in the gap between the inner surface layer 52 and the steel plate 51. This hollow glass fiber is disposed so as to avoid the wiring of the conductor wires described below. FIG. 7 is a diagram illustrating an example of the structure of the inner surface layer at the location where the detection sensor is located. Note that this example of the structure of the inner surface layer 52 is just one example, and it is sufficient that the organic solvent stored in the underground tank 50 does not leak unless a malfunction occurs.

[0041] As shown in Figure 7, in this example, hollow glass fiber 501 is attached to the inner surface of a steel plate 51. The detection sensor 15 is placed in a gap where no hollow glass fiber 501 exists. A portion of the detection sensor 15 is inserted into a split tube 510 for protection. The split tube 510 into which the detection sensor 15 is inserted is higher (thicker) than the hollow glass fiber 501. For this reason, oil-resistant double-sided tape 502 is attached to the hollow glass fiber 501 adjacent to the split tube 510, and adhesive PET films 504 are attached to the two double-sided tapes 502.

[0042] Putty 503 is applied to the side of the double-sided tape 502 opposite to the side facing the divided tube 510. The outside of the inner surface layer 52, i.e., the side that comes into contact with the organic solvent, is entirely covered with, for example, ultraviolet-curing type FRP (fiber reinforced plastic) 505. This FRP 505 corresponds to the inner surface layer 52 in the narrow sense.

[0043] Fig. 8 is a diagram illustrating an example of a method for connecting hollow glass fibers. Fig. 9 is a diagram illustrating an example of the structure of the inner surface layer at the end of a hollow glass fiber. As shown in Fig. 8, two hollow glass fibers 501 are connected by attaching a PET film 504 to them. As shown in Fig. 9, putty 503 is applied to the end of the hollow glass fiber 501.

[0044] FIG. 10 illustrates an example structure of a penetration section where a detection sensor penetrates the inner surface layer. As shown in FIG. 10 , in this penetration section, a split tube 510 with a detection sensor 15 inserted therein penetrates the FRP 505. The FRP 505 is actually formed (e.g., attached) after the detection sensor 15 including the split tube 510 is placed. Putty 503 is applied to stabilize the detection sensor 15 including the split tube 510. The gaps between the FRP 505 and the split tube 510, between the detection sensor 15 and the split tube 510, and between the detection sensor 15 and the split tube 510 are sealed with a sealing material (not shown). This prevents leakage from the inner surface layer 52 unless a hole or crack occurs in the FRP 505.

[0045] 11 is a diagram illustrating an example of a connection portion. A plurality of pipes 81 to 83 are connected to the connection portion 45. Both ends of the detection sensor 15 are connected to connectors 84, respectively. A lead wire 25 is connected to each connector 84. One of the two connectors 84 is a switching connector 84, to which a communication line 85 is connected in addition to the lead wire 25.

[0046] In this example, as with the double piping 30, the leak detection device 21 of the leak detector panel 20 can automatically detect a leak occurring in the inner surface layer 52 of the underground tank 50. It can be assumed that a leak in the inner surface layer 52 is due to a physical force acting on the steel plate 51 or deterioration of the steel plate 51 due to rust or other factors. Therefore, a leak in the inner surface layer 52 can be considered to indicate that a leak is occurring from the steel plate 51 or that there is a high risk of a leak. This example makes it possible to more reliably respond to such a leak at an earlier stage. The inner surface layer 52 functions to reduce the amount of organic solvent leaking from the underground tank 50, even if the steel plate 51 is damaged and leaks organic solvent from the steel plate 51.

[0047] In this example, it is assumed that a leak in an already existing underground tank 50 is to be detected, but the underground tank 50 may be one that is to be buried in the future. In this case, the detection sensor 15 is disposed between the steel plate 51 and the outer surface layer formed on the outside thereof.

[0048] Next, other embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely examples, including modifications, and the technical scope of the present invention is not limited to these. Various modifications are also included within the technical scope of the present invention.

[0049] FIG. 12 is a cross-sectional view showing an example of a shelter according to an embodiment of the present invention, and FIG. 13 is a plan view showing an example of a shelter according to an embodiment of the present invention.

[0050] This shelter 61 is an underground shelter designed for use in the event of a nuclear war. A shelter body 62, which provides accommodation space for evacuees evacuating to the shelter 61, is entirely buried below ground level G, as shown in FIG. 12 . An entrance / exit section 63 protrudes from ground level G, allowing evacuees to enter and exit. An explosion-proof door (not shown) is provided in the entrance / exit section 63, which can be isolated from the outside by the explosion-proof door. A space 64 is formed within the entrance / exit section 63 for evacuees to ascend and descend. A staircase 65 is provided within the space 64, and evacuees can use the staircase 65 to move (ascend and descend) between the entrance / exit section 63 and the shelter body 62.

[0051] The inside of the shelter main body 62 can be isolated from the space 64 by, for example, a wall equipped with an iron door. The isolable space is divided into a plurality of sections (stayable spaces) 93 to 95, as shown in Fig. 13. Sections 93 and 94 are separated by a wall, and sections 94 and 95, as well as sections 93 and 95, are both separated by walls equipped with, for example, iron doors.

[0052] The section 93 is assumed to be used for installing various types of equipment, etc. Figures 12 and 13 show examples of equipment such as a power generator 66, a fuel tank 67, a storage battery 68, a power conditioner 69, a distribution board 70, and an alarm 71. Since the power generator 66 is used inside the shelter, it must be fuel-efficient, capable of operating for long periods of time, easy to maintain, and have low running costs; for example, a diesel generator is used in this example.

[0053] When a diesel generator is used as the power generating equipment 66, diesel fuel is stored in the fuel tank 67. On the other hand, a generator using gasoline as fuel is also possible, but since gasoline is used inside the shelter, it is prone to ignition and is highly dangerous, so it is safer to use diesel. Furthermore, although it is smaller, a generator using kerosene can also be used.

[0054] The fuel tank 67 includes a fuel tank body 321 and two support bases 322 that support the fuel tank body 321. An inlet 323 for injecting fuel (diesel) is provided at the top of the fuel tank body 321. A detector 72 for detecting leaking fuel is attached near the inlet 323. The "top" here is a positional expression assuming that the fuel tank 67 is installed in an appropriate state. Unless otherwise specified, the positional expressions will be based on this assumption.

[0055] Fuel (diesel) stored in a fuel tank 67 is supplied to the power generating equipment 66 via a pipe 73. A detector 74 for detecting leaking fuel is attached to the lower side of the pipe 73.

[0056] In the case of a diesel generator employed as the power generating equipment 66, the fuel used is diesel fuel, and fuel leaking from either the fuel tank body 321 or the piping 73 is detected by detector 72 or 74.

[0057] In Fig. 13, the connections made by various electric wires, including signal wires, are indicated by dotted lines. As shown in Fig. 13, the detectors 72, 74 are connected to the alarm device 71 by signal wires 211, 212. When the detectors 72, 74 detect fuel, for example, they activate the signals they output to the signal wires 211, 212 (hereinafter referred to as "detection result signals"). This causes the detectors 72, 74 to notify the alarm device 71 of the fuel detection results.

[0058] When the alarm device 71 is notified of the detection of fuel, it sounds an alarm, for example. The sound of the alarm allows the evacuees to know of the fuel leak. In this embodiment, the alarm device 71 can also notify the evacuees which of the detectors 72 and 74 has notified the evacuees of the fuel detection by an alarm sound, voice, or displayed information. In this embodiment, the detector 74 corresponds to the detector, and the detector 721 corresponds to the other detector.

[0059] The electric power generated by the power generation device 66 is supplied to the power conditioner 69 via an electric wire 201. The power conditioner 69 converts the electric power supplied from the power generation device 66 into an appropriate state for the storage battery 68 and supplies the converted electric power to the storage battery 68. This electric power supply uses an electric wire 202. As a result, the electric power generated by the power generation device 66 is temporarily stored in the storage battery 68. Exhaust gas generated when the power generation device 66 generates electric power is discharged to the outside via an exhaust gas pipe 311, part of which protrudes above the ground surface G.

[0060] Electricity generated by solar panels used in renewable energy power generation or power generation equipment powered by wind turbines can be supplied to a power conditioner 69 and stored in a storage battery 68. In this case, depending on the conditions on the ground, there may be cases where renewable energy cannot be used.

[0061] The storage battery 68 and the distribution board 70 are electrically connected by an electric wire 203. As a result, the power stored in the storage battery 68 is supplied to the distribution board 70 via the electric wire 203. The distribution board 70 is an electrical facility in which a molded case circuit breaker, a ground fault circuit interrupter, and the like are mounted together. The power stored in the storage battery 68 can be supplied via the distribution board 70 to various devices (not shown) provided in the shelter 61. Examples of the various devices include an air filter, a heating and cooling device, a communication device, a pump, and a cooking appliance.

[0062] The fuel stored in the fuel tank 67 is usually flammable and is often harmful to humans. When the shelter 61 is in use, the inside of the shelter main body 62 becomes an enclosed space that is shielded from the outside. Therefore, fuel leakage within the shelter main body 62 is extremely dangerous. For this reason, in this embodiment, fuel leakage is made more unlikely to occur in the following manner.

[0063] Figure 14 is a diagram showing an example of a cross section taken along line A-A' in Figure 13. As shown in Figure 14, in this embodiment, the fuel tank main body 321 has a multi-layer structure in which the primary tank 3211 is entirely covered by the secondary tank 3212. The interior of the primary tank 3211 is isolated from the interior of the secondary tank 3212, and fuel is stored in the primary tank 3211. Therefore, even if damage such as corrosion or cracks occurs in part of the primary tank 3211, the fuel tank main body 321 is designed to prevent fuel from leaking to the outside as long as damage does not occur in the secondary tank 3212. This makes it more difficult for fuel to leak from the fuel tank 32.

[0064] 14, the fuel tank body 321 has a multi-layer structure, and therefore the injection part 323 includes a protruding part 3231 protruding from the secondary tank 3212, and a lid 3232 attached to the end of the protruding part 3231. A hole 3233 that allows fuel to be injected into the primary tank 3211 from the outside is formed in the protruding part 3231. This hole 3233 is formed by a cylindrical molding, and the end located on the inside of the cylindrical molding is entirely joined to the primary tank 3211, for example, to prevent fuel leakage.

[0065] The cylindrical molding is entirely covered by another cylindrical molding, and the outer ends of the two moldings are connected. The other end of the other cylindrical molding is entirely joined to the secondary tank 3212. As a result, the protrusion 3231 forms a double piping structure that can maintain a state in which the inside of the primary tank 3211 is isolated from the inside of the secondary tank 3212. The opening located on the outside of the hole 3233 can be closed with a lid 3232 to prevent fuel leakage.

[0066] A discharge part 324 for discharging fuel is provided at the bottom of the fuel tank body 321. This discharge part 324 has a double piping structure similar to that of the protruding part 3231, as shown in Figure 3. A cylindrical molding with a hole 3741 formed therein exists within the discharge part 324, which enables the fuel in the primary tank 3211 to be discharged to the outside. The end located on the inside of the cylindrical molding is entirely joined to the primary tank 3211 to prevent fuel leakage.

[0067] The cylindrical molding is entirely covered by another cylindrical molding, and the outer ends of the two moldings are connected. The other end of the other cylindrical molding is entirely joined to the secondary tank 3212. As a result, the discharge part 324, like the protrusion 3231, maintains the interior of the primary tank 3211 isolated from the interior of the secondary tank 3212.

[0068] The other end 3742 of the other cylindrical molded article has, for example, a screw thread formed on its outer surface. This screw thread is intended for attaching a flange 401 having a screw thread formed on its inner surface to the discharge portion 324, as shown in Fig. 14. In the example shown in Fig. 14, the pipe 73 has a flange 402 attached to its end. The flange 402 is connected to the flange 401 with the same number of bolts 411 and nuts 412, with a packing (not shown) sandwiched between the flange 402 and the flange 401.

[0069] The pipe 73 has a double pipe structure to match the structure of the discharge portion 324. As a result, the structure includes a primary pipe 371 through which fuel flows and a secondary pipe 372 that covers the primary pipe 371. For example, a screw thread is formed on the outer surface of one end 374 of the secondary pipe 372, and the flange 402 is attached to the pipe 73 by the screw thread.

[0070] The interior of the primary pipe 371 is spatially isolated from the interior of the secondary pipe 372. One end 373 of the primary pipe 371 is exposed from the secondary pipe 372 for connection to other pipes. Therefore, the other end of the secondary pipe 372 is filled with a sealant 375 to prevent a gap from forming between the primary pipe 371 and the secondary pipe 372. By filling with this sealant 375, the outside of the primary pipe 371 is isolated as a closed space within the range where the secondary pipe 372 covers the primary pipe 371. As a result, fuel will not leak within that range, even if damage such as corrosion or cracks occurs in part of the primary pipe 371, as long as damage does not occur in the secondary pipe 372. This makes it more difficult for fuel to leak from the pipe 73.

[0071] One end 373 of the primary pipe 371 is exposed from the secondary pipe 372 so that it can be connected to the piping on the generator 31 side of the primary pipe 371 without any special work, even for an existing generator 31. Portions not involved in such connections may be configured as a double-pipe structure in which the outside of the primary pipe 371 is isolated in advance by the secondary pipe 372 without using a sealant 375 or the like. This configuration allows the pipe 73 to be formed by connecting multiple types of pipes with different structures. Even in such a pipe 73, the presence of a primary pipe whose outside is isolated by the secondary pipe reduces the risk of fuel leakage. The double-pipe structure in which the outside of the primary pipe 371 is isolated in advance by the secondary pipe 372 may have flanges 402 attached to both ends, for example.

[0072] A detection sensor 381 for detecting fuel is disposed between the primary pipe 371 and the secondary pipe 372. This detection sensor 381 is, for example, a sensor cable whose electrical characteristics, such as capacitance or electrical resistance, change upon contact with fuel, and is connected to the detector 73. The fuel detection method is not particularly limited and may be selected as desired depending on the type of fuel expected to be used. The pipe 73 has the same configuration as that shown in FIGS. 2 and 3, where a secondary pipe, also made of resin, covers the primary pipe, for example, made of resin, and a gap of a predetermined width is formed between the primary pipe and the secondary pipe. A detection sensor is disposed in this gap.

[0073] The reason why the detection sensor 381 is disposed at the bottom is that it is assumed that the fuel is mainly liquid. Since liquid moves downward due to gravity, by disposing the detection sensor 381 at the bottom, fuel leakage from the primary pipe 371 can be detected more quickly and reliably.

[0074] The detector 74 monitors the electrical characteristics of the detection sensor 381, and determines from changes in the electrical characteristics whether fuel is in contact with the detection sensor 381, i.e., whether fuel is leaking from the primary pipe 371, and changes the detection result signal output to the signal line 211 according to the determination result. As a result, the alarm 71 is notified of the fuel detection result by the detector 74.

[0075] Fuel leaks from the secondary pipe 372 when the secondary pipe 372 breaks at approximately the same time as the primary pipe 371, or when the secondary pipe 372 breaks earlier than the primary pipe 371. However, the presence of the secondary pipe 372 is expected to further reduce the amount of fuel that leaks due to breakage of the primary pipe 371 and actually leaks from the secondary pipe 372. In cases other than these, it is possible to deal with situations in which fuel leakage is prevented by the secondary pipe 372.

[0076] For these reasons, by employing the pipe 73 having a double pipe structure, not only can the risk of fuel leakage be further reduced, but the degree of the risk can also be further suppressed. If fuel leakage from the primary pipe 371 is detected, the possibility of actually preventing fuel from leaking from the pipe 73 can be greatly increased, and it becomes easier to take action at an earlier stage. Therefore, higher safety can be ensured. The primary pipe 371 corresponds to the pipe in this embodiment, and the secondary pipe 372 corresponds to the covering member in this embodiment.

[0077] Figure 15 is a diagram showing an example of a cross section taken along line BB' in Figure 13. As shown in Figure 15, in the fuel tank main body 321, a detection sensor 391 for detecting fuel is disposed between the primary tank 3211 and the secondary tank 3212. This detection sensor 391 is, for example, a sensor cable whose electrical characteristics, such as capacitance or electrical resistance, change when it comes into contact with fuel, similar to the detection sensor 391, and is connected to the detector 73.

[0078] The detection sensor 391 is arranged so as to surround the primary tank 3211 over the entire longitudinal direction on the plane of the fuel tank body 321. The reason that the detection sensor 391 is arranged below the primary tank 3211 in this way is to be able to detect fuel that leaks from the primary tank 3211 and moves downward. By arranging the detection sensor 391 below the primary tank 3211, even a short detection sensor 391 can detect fuel that has leaked from the primary tank 3211 with a very high probability.

[0079] Similar to the detector 74 described above, the detector 72 monitors the electrical characteristics of the detection sensor 391 and, from changes in the electrical characteristics, determines whether fuel has come into contact with the detection sensor 391, i.e., whether fuel is leaking from the primary tank 3211, and changes the detection result signal output to the signal line 212 according to the determination result. This notifies the alarm 71 of the fuel detection result by the detector 72. Note that the fuel leakage may be notified via the alarm 71 to an information device located inside or outside the shelter main body 62.

[0080] In many cases, fuel leaks from the secondary tank 3212 when the secondary tank 3212 is damaged at approximately the same time as the primary tank 3211, or when the secondary tank 3212 is damaged earlier than the primary tank 3211. However, the presence of the secondary tank 3212 is expected to further reduce the amount of fuel that leaks due to damage to the primary tank 3211 and actually leaks from the secondary tank 3212. In cases other than these, it is possible to respond in situations where the secondary tank 3212 is preventing fuel leakage.

[0081] For these reasons, by adopting a fuel tank body 321 with a multi-layer (here, two-layer) structure, not only can the risk of fuel leakage be further reduced, but the degree of that risk can also be further suppressed. If fuel leakage from the primary tank 3211 is detected, the possibility of actually preventing fuel from leaking from the fuel tank body 321 can be greatly increased, and it becomes easier to take action at an earlier stage. Therefore, even in this respect, higher safety can be achieved.

[0082] The primary tank 3211 corresponds to the fuel tank in this embodiment, and the secondary tank 3212 corresponds to the other covering member in this embodiment. The other covering member may cover the outside of a part of the primary tank 3211 that is easily damaged or that is highly affected by damage, and isolate that part. This isolation may be achieved using a sealing material or the like.

[0083] Piping that allows fuel to be transported between different facilities is relatively likely to be damaged by vibrations or shocks caused by earthquakes or other external forces. In reality, some of the piping is often located in narrow, hard-to-see locations. Piping replacement, etc., often requires work to be performed in a confined space. For these reasons, it is often difficult to respond quickly to a fuel leak. Therefore, it is particularly desirable to reduce the risk of fuel leaking from piping 73.

[0084] Although this embodiment is applied to a nuclear shelter, the shelter to which the present invention is applied is not limited to a nuclear shelter. The shelter may be one designed for natural disasters or the like.

[0085] The equipment to be installed in a shelter may vary depending on the purpose of the shelter. The equipment to be installed may also change depending on the length of time people are expected to evacuate to the shelter. However, most of the equipment to be installed requires electricity to operate. For this reason, in this embodiment, a power generating device 66 is used as a consumer device to enable a stable supply of electricity for a longer period of time. However, it is considered that the important consumer devices will also change depending on the evacuees, the expected evacuation situation, or the installation location of the shelter 61. For this reason, the types and number of consumer devices are not particularly limited.

[0086] In this embodiment, a portion of the piping and the entire fuel tank are covered with a covering material in advance to isolate the exterior, but such isolation may also be performed on items already installed in the shelter. The components do not have to be the covering material alone, as described above. In other words, other components may be used in addition to the covering material. The other components may include not only a sealant but also a component for stably attaching the covering material to the object (piping or fuel tank), a component for sealing a gap that occurs between the covering material and the object, and so on. Various modifications, including the above, are possible in the application of this invention.

[0087] REFERENCE SIGNS LIST 1 Wiring outlet 2 Extraction pipe 3 Pipe 4 Pipe 7 Gap 9 Gap 10 Connection box 11 Oil filling pipe 15 Detection sensor 20 Leak detection panel 21 Leak detection device 22 Buzzer 25 Lead wire 30 Double pipe 31 First pipe 32 Second pipe 50 Underground tank 51 Steel plate 52 Inner surface layer 61 Shelter 62 Shelter body 63 Entrance / exit 64 Space 65 Stairs 66 Generating equipment 67 Fuel tank 68 Storage battery 69 Power conditioner 70 Distribution board 71 Alarm 72, 74 Detector 73 Pipe 505 FRP

Claims

1. A leak detection device comprising a pipe buried underground, in which a first layer and a second layer are formed inside a structure in which a fluid is stored or flowed so as not to leak, a detection sensor for detecting the fluid is disposed between the first layer and the second layer, and the detection sensor detects the fluid leaking from the first layer.

2. A leak detection device comprising a tank buried underground, a first layer and a second layer formed inside the structure in which a fluid is stored or flowed so as not to leak the fluid, a detection sensor for detecting the fluid disposed between the first layer and the second layer, and the detection sensor detecting the fluid leaking from the first layer.

3. A leak detection device according to claim 1 or 2, wherein the fluid is an organic solvent.

4. The leak detection device according to claim 1 or 2, wherein the structure is a double pipe having the first layer and the second layer.

5. The leak detection device according to claim 1 or 2, wherein the structure is an underground tank buried underground and provided with the first layer and the second layer.

Images