JP2016200529A - Liquid level monitoring device, atomic power plant, and liquid level monitoring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level monitoring device, an atomic power plant and a liquid level monitoring method that make possible liquid level monitoring over a long period.SOLUTION: A liquid level monitoring device is equipped with a hollow container disposed in a vertical direction, a stack disposed in the hollow container and so constituted as to generate sounds attributable to a temperature difference between the top and bottom ends of the hollow container, and a liquid absorbing material having many gaps and so disposed as to cover the external surface of the hollow container underneath the stack.SELECTED DRAWING: Figure 5

Description

  The present disclosure relates to a liquid level monitoring device, a nuclear power plant, and a liquid level monitoring method.

  Conventionally, a method using an acoustic sensor is known for detecting a liquid level. For example, Patent Document 1 describes a water level measuring device that measures the water level in a well using an acoustic sensor. This water level measuring device detects standing waves generated by vibrating the air in the well with an acoustic sensor attached to the top of the well, and analyzes the received signal of the acoustic sensor to detect the top edge of the well and the groundwater. The distance from the surface of the water is calculated.

  Patent Document 2 describes a thermoacoustic sensor that converts heat into sound waves, although it is not a device that detects a liquid level. The thermoacoustic sensor includes a housing that defines a chamber that functions as a resonator, and a stack that is disposed in the chamber. When the stack receives heat from a heat source inside or outside the housing and a certain temperature difference occurs between both ends of the stack, a sound wave having a frequency corresponding to the temperature around the housing is generated. Therefore, the temperature around the housing can be known by measuring the frequency of the sound wave that resonates with the resonator.

JP 2004-61473 A US Patent Application Publication No. 2014/0050293

As in the above-described Patent Document 1, in a water level measurement device using a general acoustic sensor, the acoustic sensor has only a sound wave detection function, and therefore it is necessary to apply a sound wave from the outside toward the water surface. Such an apparatus is suitable when it is desired to grasp (measure) an accurate liquid level, but it is not suitable for monitoring the liquid level over a long period of time because it is necessary to always apply sound waves.
In addition, the thermoacoustic sensor described in Patent Document 2 is not an apparatus for detecting a liquid level in the first place.

  In view of the above circumstances, at least one embodiment of the present invention aims to provide a liquid level monitoring apparatus, a nuclear power plant, and a liquid level monitoring method capable of monitoring a liquid level over a long period of time.

(1) A liquid level monitoring device according to at least one embodiment of the present invention includes:
A hollow container provided along the vertical direction;
A stack provided in the hollow container and configured to generate sound due to a temperature difference between the upper and lower ends; and
A liquid-absorbing material provided on the lower side of the stack so as to cover an outer surface of the hollow container.

According to the liquid level monitoring device of (1) above, the liquid absorbing material is provided on the lower side of the stack so as to cover the outer surface of the hollow container, and therefore only the lower part of the liquid absorbing material is immersed in the liquid. Since the lower part of the liquid absorbing material sucks up the liquid, the liquid penetrates into the upper part of the liquid absorbing material. Then, the liquid that has permeated the liquid absorbing material takes the heat of vaporization and evaporates from the outer surface of the hollow container on the lower side of the stack. For this reason, as the temperature of the outer surface of the hollow container on the lower side of the stack decreases, the temperature of the internal space of the hollow container on the lower side of the stack also decreases, and a temperature difference occurs between the upper and lower ends of the stack. When a temperature difference occurs between the upper and lower ends of the stack, the stack generates a sound. By detecting this sound, it is possible to grasp that only the lower end side of the hollow container is in contact with the liquid.
In this way, in the above configuration, the stack itself generates sound due to the temperature difference between the upper and lower ends, so there is no need to apply sound waves from the outside, and the liquid level can be monitored appropriately over a long period of time.
In addition, the stack is configured to generate sound due to the temperature difference between the upper and lower ends, and since no power source is required on the transmission source side (liquid level side), the liquid level is reliably monitored even when power is lost. be able to.
In addition, since the liquid level can be monitored by the presence or absence of liquid permeation into the liquid absorbent material, such as when there are obstacles around the liquid level monitoring device or when the liquid level is rippled, Appropriately monitors the liquid level even in situations where it is difficult to monitor with other types of liquid level detection means (for example, ultrasonic liquid level sensor, pressure liquid level sensor, bubble liquid level sensor, float type liquid level sensor, etc.) can do.

(2) In one embodiment, in the configuration of (1) above,
The liquid absorbing material includes at least a porous portion extending in the vertical direction.
(3) In another embodiment, in the configuration of (1) above,
The liquid absorbing material includes at least a mesh portion extending in the vertical direction.

  According to the configuration of the above (2) or (3), the liquid easily penetrates into the upper part of the liquid absorbing material not immersed in the liquid by the capillary phenomenon in the porous part or the network part of the liquid absorbing material. As a result, the liquid penetrates the entire liquid-absorbing material, and the heat of vaporization when the liquid vaporizes increases, so that the temperature difference between the upper and lower ends of the stack becomes significant. Therefore, it can be reliably detected that only the lower part of the liquid absorbing material is immersed in the liquid.

(4) In some embodiments, in any one of the above configurations (1) to (3),
The outer surface of the hollow container on the upper side of the stack is not covered with the liquid absorbing material.

  According to the configuration of (4) above, since the outer surface of the hollow container on the upper side of the stack is not covered with the liquid absorbing material, the internal space of the hollow container on the upper side of the stack is affected by the temperature decrease due to heat of vaporization. I hardly receive it. Therefore, the temperature difference between the upper and lower ends of the stack becomes remarkable, and it can be detected more reliably that only the lower part of the liquid absorbing material is immersed in the liquid.

(5) In some embodiments, in any one of the configurations (1) to (4), the liquid level monitoring device is configured to monitor the liquid level of the coolant in the nuclear power plant.
Normally, in a nuclear power plant, an appropriate coolant level is determined in each part for sound operation. For example, if the coolant level falls below a set value, the reactor may not be properly cooled.
Therefore, the liquid level of the nuclear power plant can be appropriately monitored over a long period of time by using any one of the above configurations (1) to (4) for monitoring the liquid level of the coolant in the nuclear power plant. . For example, the liquid level monitoring device can detect that the coolant has fallen below the set liquid level. In addition, since a sound can be generated according to the liquid level even without a power source, the liquid level can be reliably monitored even when the power source is lost, and the safety of the nuclear power plant can be improved.

(6) In one embodiment, in the configuration of (5) above,
The liquid level monitoring device is provided in a nuclear reactor vessel of the nuclear power plant.
(7) Moreover, in one Embodiment, in the structure of said (6),
The liquid level monitoring device is provided in an annular gap between the reactor vessel and the core tank.
(8) In another embodiment, in the configuration of (5) above,
The liquid level monitoring device is provided in a coolant water chamber provided below a steam generator of the nuclear power plant.
(9) In still another embodiment, in the configuration of (5) above,
The liquid level monitoring device is connected to a reactor vessel of the nuclear power plant, and is provided in a pipe through which a coolant for cooling the reactor vessel flows.

(10) A nuclear power plant according to at least one embodiment of the present invention,
A reactor including a reactor vessel;
The liquid level monitoring apparatus according to any one of (1) to (9), which is housed in the reactor vessel.

  According to the nuclear power plant of (10) above, as described above, the liquid level monitoring device can appropriately monitor the liquid level of each part in the nuclear power plant, so it is possible to grasp the malfunction of the nuclear power plant at an early stage. It becomes.

(11) A liquid level monitoring method according to at least one embodiment of the present invention includes:
A sound detecting step for detecting a sound generated from the stack due to a temperature difference between upper and lower ends of the stack provided in the hollow container when a lower side of the hollow container provided along the vertical direction comes into contact with the liquid; ,
In the sound detection step, a temperature difference between the upper and lower ends of the stack is generated by the heat of vaporization of the liquid that has permeated the liquid absorbing material provided so as to cover the outer surface of the hollow container on the lower side of the stack.

According to the liquid level monitoring method of (11) above, when only the lower part of the liquid absorbing material is immersed in the liquid, the lower part of the liquid absorbing material sucks up the liquid, so that the liquid penetrates into the upper part of the liquid absorbing material. The liquid that has permeated the liquid absorbing material takes the heat of vaporization and evaporates from the outer surface of the hollow container on the lower side of the stack. For this reason, a temperature difference occurs between the upper and lower ends of the stack, and the stack generates sound. By detecting this sound, it can be grasped that only the lower end side of the hollow container is in contact with the liquid.
In this way, in the above method, the stack itself generates sound due to the temperature difference between the upper and lower ends, so that it is not necessary to apply sound waves from the outside, and the liquid level can be monitored appropriately over a long period of time.
In addition, the stack is configured to generate sound due to the temperature difference between the upper and lower ends, and since no power source is required on the transmission source side (liquid level side), the liquid level is reliably monitored even when power is lost. be able to.
Furthermore, since the liquid level can be monitored by the presence or absence of liquid permeation into the liquid absorbing material, other types such as when there are obstacles near the liquid level or when the liquid level is rippled, etc. The liquid level can be appropriately monitored even in situations where it is difficult to monitor with a liquid level detection means (for example, an ultrasonic liquid level sensor, a pressure liquid level sensor, a bubble liquid level sensor, or a floating liquid level sensor). it can.

According to at least one embodiment of the present invention, when only the lower part of the liquid absorbing material provided on the outer surface of the hollow container on the lower side of the stack is immersed in the liquid, the lower part of the liquid absorbing material sucks up the liquid. It penetrates into the top of the liquid material. The liquid that has penetrated into the liquid absorbing material takes the heat of vaporization from the outer surface on the lower side of the stack of the hollow containers and evaporates, and a temperature difference is generated between the upper and lower ends of the stack of the hollow containers. For this reason, the stack generates sound due to the temperature difference between the upper and lower ends of the stack. By detecting this sound, it is possible to grasp that only the lower end side of the hollow container is in contact with the liquid, and the liquid level can be monitored.
Thus, since the stack itself generates a sound due to the temperature difference between the upper and lower ends, it is not necessary to apply a sound wave from the outside, and the liquid level can be appropriately monitored over a long period of time.
In addition, the stack is configured to generate sound due to the temperature difference between the upper and lower ends, and since no power source is required on the transmission source side (liquid level side), the liquid level is reliably monitored even when power is lost. be able to.

It is a schematic structure figure of a nuclear power plant concerning one embodiment. 1 is a cross-sectional view of a nuclear reactor according to an embodiment. It is sectional drawing of the steam generator which concerns on one Embodiment. It is a perspective view of the liquid level monitoring apparatus concerning one embodiment. It is sectional drawing of the liquid level monitoring apparatus which concerns on one Embodiment.

  Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.

The liquid level monitoring apparatus and method according to the present embodiment is an apparatus and method for monitoring a liquid level (liquid level), for example, the liquid level has dropped below a set level, or the liquid level is set. It is configured to detect that the level has risen above the level.
In addition, in the following description, the case where the liquid level monitoring apparatus and method which concern on this embodiment are applied to a nuclear power plant is illustrated. However, the application destination of the liquid level monitoring apparatus and method according to the present embodiment is not limited to a nuclear power plant, and may be another apparatus or a plant.

  Initially, with reference to FIG. 1, the nuclear power plant 1 which is one of the application destinations of the liquid level monitoring apparatus and method which concern on this embodiment is demonstrated. FIG. 1 is a schematic configuration diagram of a nuclear power plant 1 according to an embodiment.

As shown in FIG. 1, a nuclear power plant 1 includes a nuclear reactor system (primary cooling system) 2 including a nuclear reactor 3 for generating steam by thermal energy generated in a fission reaction, and steam generated in the nuclear reactor 3. And a turbine system (secondary cooling system) 4 including steam turbines 21 and 22 driven by the engine. When the nuclear power plant 1 is a nuclear power plant configured to generate power by nuclear power, the nuclear power plant 1 further includes a generator 6 that is driven by the rotation of the rotation shafts of the steam turbines 21 and 22.
Note that the nuclear reactor 3 shown in FIG. 1 is a pressurized water reactor (PWR: Pressurized Water Reactor). In other embodiments, the reactor 3 may be a boiling water reactor (BWR), or, unlike light water reactors including pressurized water reactors and boiling water reactors, moderators or It may be a reactor of a type using a substance other than light water as a coolant.

The reactor system 2 includes a primary cooling loop 10 through which primary cooling water (primary coolant) flows, a reactor vessel (pressure vessel) 11 provided in the primary cooling loop 10, a pressurizer 14, a steam generator 16, and a primary coolant. A pump 18. The primary coolant pump 18 is configured to circulate primary cooling water in the primary cooling loop 10. The pressurizer 14 is configured to pressurize the primary cooling water in the primary cooling loop 10 so that the primary cooling water does not boil. Note that the reactor vessel 11, the pressurizer 14, the steam generator 16, and the primary coolant pump 18 constituting the reactor 3 are stored in the reactor containment vessel 19.
The reactor vessel 11 contains fuel rods 12 containing pellet-like nuclear fuel (for example, uranium fuel, MOX fuel, etc.), and the primary energy in the reactor vessel 11 is generated by the thermal energy generated by the fission reaction of this fuel. The cooling water is heated. The reactor vessel 11 is provided with a control rod 13 for absorbing and adjusting the number of neutrons generated in the core containing nuclear fuel in order to control the reactor power. The primary cooling water heated in the reactor vessel 11 is sent to the steam generator 16 to generate steam by heating the secondary cooling water (secondary coolant) flowing through the secondary cooling loop 20 by heat exchange. Let

The steam generated by the steam generator 16 is sent to the turbine system 4.
In the turbine system 4, the high pressure turbine 21 and the low pressure turbine 22 are rotationally driven by the steam generated by the steam generator 16. The high-pressure turbine 21 and the low-pressure turbine 22 are connected to the generator 6 via a rotating shaft, and the generator 6 is driven by the rotation of the rotating shaft to generate electric energy. A moisture separator / heater 23 is provided between the high-pressure turbine 21 and the low-pressure turbine 22 so that the steam after working in the high-pressure turbine 21 is heated again and then sent to the low-pressure turbine 22. ing.

  The secondary cooling loop 20 is provided with a condenser 24, a low-pressure feed water heater 26, a deaerator 27, and a high-pressure feed water heater 29, and the steam after working in the low-pressure turbine 22 supplies these devices. It is condensed and heated in the course of passing, and returns to the steam generator 16. The secondary cooling loop 20 is provided with a condensate pump 25 and a feed water pump 28, and the secondary cooling water is circulated in the secondary cooling loop 20 by these pumps. The condenser 24 is supplied with cooling water (for example, seawater) for cooling the steam from the low-pressure turbine 22 by heat exchange via the pump 15.

  Next, with reference to FIG.2 and FIG.3, the structure of each site | part of the nuclear power plant 1 is demonstrated concretely. 2 and 3, the arrows in the drawings indicate the flow of the coolant.

FIG. 2 is a cross-sectional view of the nuclear reactor 3 according to an embodiment.
In the nuclear reactor 3 according to the embodiment, the nuclear reactor vessel 11 includes a nuclear reactor vessel body 30 and a reactor vessel lid (upper mirror) 31 that can be opened and closed.
The reactor vessel body 30 has a cylindrical shape whose lower part is closed by a lower mirror 35 having a hemispherical shape. The reactor vessel body 30 is formed with an inlet nozzle (inlet nozzle) 36 for supplying light water (coolant) as primary cooling water and an outlet nozzle (exit nozzle) 67 for discharging light water. ing. In addition to the inlet nozzle 36 and the outlet nozzle 37, the reactor vessel main body 30 is formed with a water injection nozzle (water injection pipe stand) (not shown).

An upper core support plate 38 is fixed above the inlet nozzle 36 and the outlet nozzle 37 inside the reactor vessel main body 30, and a lower core support plate 39 is fixed so as to be positioned near the lower mirror 35 below. Has been. A plurality of measurement nozzles 33 are attached to the lower mirror 35. The upper core support plate 38 and the lower core support plate 39 have a disk shape, and a large number of communication holes (not shown) are formed. An upper core plate 41 in which a large number of communication holes (not shown) are formed is connected below the upper core support plate 38 via a plurality of core support rods 40.
Inside the reactor vessel main body 30, a cylindrical reactor core 42 having a predetermined distance from the inner wall surface of the reactor vessel main body 30 is disposed. An annular gap (downcomer) 32 in which the coolant flows downward is formed between the reactor vessel main body 30 and the core tank 42. The upper part of the core tank 42 is connected to the upper core plate 41, and the lower core plate 43 is connected to the lower part. The lower core plate 43 has a disk shape, is formed with a large number of communication holes (not shown), and is supported by the lower core support plate 39.

The core 44 is formed by an upper core plate 41, a core tank 42, and a lower core plate 43.
A large number of fuel assemblies 50 and a large number of control rods 13 are arranged inside the core 44. A large number of control rods 13 are combined at the upper end portion into a control rod cluster 51 that can be inserted into the fuel assembly 50. A number of control rod cluster guide tubes 45 are fixed to the upper core support plate 38 so as to penetrate the upper core support plate 38. Each control rod cluster guide tube 45 extends to the control rod cluster 51 in the fuel assembly 50 at the lower end.
The fission reaction in the plurality of fuel rods 12 included in the fuel assembly 50 is controlled by a control rod cluster 51 having a plurality of control rods 13. The control rod cluster 51 is driven by the control rod driving device 46 so that the plurality of control rods 13 included in the control rod cluster 51 move up and down in the control rod guide thimble.

  The reactor vessel lid 31 constituting the reactor vessel 11 has a hemispherical upper portion and is provided with a control rod drive device 46 of a magnetic jack, and is accommodated in a housing 47 that is integrated with the reactor vessel lid 31. Has been. The control rod cluster guide tube 45 has an upper end extending to the control rod drive device 46, and a control rod cluster drive shaft 48 extending from the control rod drive device 46 passes through the control rod cluster guide tube 45. It extends to the fuel assembly 50 and is configured to be able to grip the control rod cluster 51. The control rod drive unit 46 extends in the vertical direction and is connected to the control rod cluster 51, and controls the output of the nuclear reactor 3 by moving the control rod cluster drive shaft 48 up and down.

  In the nuclear reactor 3 having the above-described configuration, the control rod drive device 46 moves the control rod cluster drive shaft 48 to extract a predetermined amount of the control rod 13 from the fuel assembly 50, thereby controlling nuclear fission in the core 44. The light water filled in the reactor vessel 11 is heated by the generated thermal energy, and the high-temperature light water is discharged from the outlet nozzle 37 and sent to the steam generator 16 as described above. That is, the nuclear fuel constituting the fuel assembly 50 is fissioned to emit neutrons, and the light water as the moderator and the primary cooling water reduces the kinetic energy of the released fast neutrons to become thermal neutrons. It makes it easy to cause nuclear fission and takes away the generated heat to cool it. On the other hand, by inserting the control rod 13 into the fuel assembly 50, the number of neutrons generated in the core 44 is adjusted, and by inserting all the control rod 13 into the fuel assembly 50, the nuclear reactor is urgently Can be stopped.

FIG. 3 is a cross-sectional view of the steam generator 16 according to an embodiment.
In one embodiment, the steam generator 16 includes a plurality of heat transfer tubes 62 disposed inside the body portion 61, a tube support plate 63 through which the plurality of heat transfer tubes 62 are inserted, and a plurality of portions below the body portion 61. A water chamber 65 provided below the heat transfer pipe 62, and configured to generate steam by heat exchange with a fluid (primary cooling water) flowing in the plurality of heat transfer pipes 62. .

The body 61 of the steam generator 16 has a hollow cylindrical shape that extends in the vertical direction and is hermetically sealed, and has a smaller diameter in the lower half with respect to the upper half. In the body portion 61, a water chamber 65 is disposed on the lower end side, and a steam discharge port 66 is disposed on the upper end side.
A cylindrical tube group outer cylinder (inner wall) 68 is provided from the lower half portion of the trunk portion 61 to the upper half portion, and is arranged with a predetermined distance from the inner wall surface of the trunk portion 61. The lower end portion of the tube group outer cylinder (inner wall) 68 extends to a tube plate 69 disposed below in the lower half of the body portion 61. A plurality of heat transfer tubes 62 are arranged in the tube group outer tube (inner wall) 68. That is, a tube group outer cylinder (inner wall) 68 and a plurality of heat transfer tubes 62 are stored in a body 61 provided on the outer peripheral side of the tube group outer cylinder (inner wall) 68.

  The water chamber 65 provided at the lower end of the body portion 61 has an inner space partitioned into an entrance chamber 65b and an exit chamber 65d by a partition wall 65a. In the entrance chamber 65b, an inlet (inlet nozzle) 65c communicating with the outside of the body portion 61 is formed, and one end portion of each heat transfer tube 62 communicates with the entrance chamber 65b. The exit chamber 65d is formed with an outlet (exit nozzle) 65e that communicates with the outside of the body portion, and the other end of each heat transfer tube 62 communicates with the exit chamber 65d. A cooling water pipe through which primary cooling water is sent from the pressurized water reactor is connected to the inlet 65c. The outlet 65e is connected to a cooling water pipe for sending the primary cooling water after heat exchange to the pressurized water reactor.

In the upper half of the body portion 61, a steam-water separator 71 that separates the feed water W into steam S and hot water, and moisture that removes the moisture of the separated steam S to bring it into a state close to dry steam. A separator 72 is provided. Between the steam / water separator 71 and the plurality of heat transfer tubes 62, a water supply pipe 73 for supplying secondary cooling water into the body 61 from the outside is inserted.
A steam discharge port 66 is formed at the upper end portion of the body portion 61. Further, in the lower half of the body 61, the secondary cooling water supplied from the water supply pipe 73 into the body 61 is caused to flow down between the body 61 and the tube group outer tube (inner wall) 68. A water supply path 74 that is folded back by the plate 69 and is raised along the heat transfer tube 62 is provided. The steam outlet 66 is connected to a cooling water pipe for sending steam to the turbines 21 and 22 (see FIG. 1), and the water supply pipe 73 is connected to a cooling water pipe for supplying secondary cooling water. The The secondary cooling water is obtained by cooling the steam used in the turbines 21 and 22 (see FIG. 1) with a condenser to condense the water.

  Regarding the operation of the steam generator 16 having the above-described configuration, the primary cooling water heated in the nuclear reactor 3 (see FIGS. 1 and 2) is introduced into the entrance chamber 65b from the inlet 65c of the steam generator 16, and then enters the entrance chamber. It is introduced into the plurality of heat transfer tubes 62 from 65b, circulates through each heat transfer tube 62, reaches the exit chamber 65d, and is discharged from the exit chamber 65d to the outside of the steam generator 16 through the outlet 65e. On the other hand, the secondary cooling water cooled by the condenser 24 (see FIG. 1) is sent to the water supply pipe 73 and rises along the plurality of heat transfer pipes 62 through the water supply path 74 in the trunk portion 61. At this time, in the trunk portion 61, heat exchange is performed between the high-pressure and high-temperature primary cooling water and the secondary cooling water. And the cooled primary cooling water is returned to the nuclear reactor 3 (refer FIG. 1, FIG. 2) from the exit chamber 65d. On the other hand, the secondary cooling water heat-exchanged with the high-pressure and high-temperature primary cooling water rises in the body portion 61 and is separated into steam and hot water by the steam separator 71. Then, after the moisture is removed by the moisture separator 72, the separated steam is sent to the turbines 21 and 22 (see FIG. 1).

Here, with reference to FIG.4 and FIG.5, the liquid level monitoring apparatus 100 applied to the nuclear power plant 1 mentioned above is demonstrated. FIG. 4 is a perspective view of the liquid level monitoring apparatus 100 (thermoacoustic device 80) according to an embodiment. FIG. 5 is a cross-sectional view of the liquid level monitoring apparatus 100 (thermoacoustic device 80) according to an embodiment.
As shown in FIGS. 4 and 5, in some embodiments, the liquid level monitoring device 100 includes a hollow container 81 provided along the vertical direction, a stack 85 provided in the hollow container 81, and a hollow container. And a liquid absorbing material 88 provided so as to cover the outer surface of 81.
In one embodiment, the thermoacoustic device 80 is configured by the hollow container 81, the stack 85, and the liquid absorbing material 88. In this case, the liquid level monitoring apparatus 100 includes a thermoacoustic device (transmitting source) 80 that generates sound according to the liquid level, and a sound detector 102 (see FIG. 1) for detecting sound emitted from the thermoacoustic device 80. , May be provided.

  The hollow container 81 defines an internal space (upper space 91, lower space 92) 90. For example, the hollow container 81 includes a cylindrical portion 82 disposed along the vertical direction, a lid portion 83 for sealing the upper opening of the cylindrical portion 82, and a lower opening for the cylindrical portion 82. A closed interior space 90 is formed. In the example shown in FIG. 5, an inner space 90 having a length L is defined by the inner wall surface of the hollow container 81, the lower surface of the lid portion 83, and the upper surface of the bottom portion 84.

  The stack 85 is provided in the hollow container 81 and is configured to generate sound due to a temperature difference between the upper end surface 86 and the lower end surface 87. That is, when the temperature difference between the upper end surface 86 and the lower end surface 87 exceeds a predetermined value, a part of the heat flux flowing through the stack 85 is converted into sound waves having a frequency corresponding to the temperature inside the internal space 90. It has become so.

  The liquid absorbing material 88 is provided on the lower side of the stack 85 so as to cover the outer surface of the hollow container 81. The liquid absorbing material 88 is formed of a material that absorbs liquid. That is, the liquid-absorbing material 88 has high liquid permeability, and the liquid penetrates the entire liquid-absorbing material when part of the liquid-absorbing material is immersed in the liquid. In the illustrated example, the liquid absorbing material 88 is provided in an annular shape so as to surround the outer surface of the hollow container 81. Thus, by providing the liquid absorbing material 88 so as to surround the outer surface of the hollow container 81, the contact area between the hollow container 81 and the liquid absorbing material 88 is increased, and the hollow container 81 is deprived of the hollow container 81 via the liquid absorbing material 88. The heat generated can be increased, and the temperature difference between the upper and lower end surfaces 86 and 87 of the stack 85 can be increased. However, the liquid absorbing material 88 may be provided only on a part of the outer surface of the hollow container 81 in the circumferential direction.

Thus, according to the above configuration, since the liquid absorbing material 88 is provided on the lower side of the stack 85 so as to cover the outer surface of the hollow container 81, only the lower portion of the liquid absorbing material 88 is immersed in the liquid. In this case, since the lower part of the liquid absorbing material 88 sucks up the liquid, the liquid penetrates into the upper part of the liquid absorbing material 88. The liquid that has permeated the liquid absorbing material 88 evaporates by taking heat of vaporization from the outer surface of the hollow container 81 on the lower side of the stack. For this reason, as the temperature of the outer surface of the hollow container 81 on the lower side of the stack decreases, the temperature of the internal space 90 of the hollow container 81 on the lower side of the stack also decreases, and a temperature difference occurs between the upper and lower end faces 86 and 87 of the stack 85. To do. When a temperature difference occurs between the upper and lower end faces 86 and 87 of the stack 85, the stack 85 generates a sound. By detecting this sound, it is possible to grasp that the lower end side of the hollow container 81 is in contact with the liquid.
Thus, in the above configuration, the stack itself generates sound due to the temperature difference between the upper and lower end faces 86 and 87, so that it is not necessary to apply sound waves from the outside, and the liquid level is monitored appropriately over a long period of time. Can do.

In addition, the stack is configured to generate sound due to the temperature difference between the upper and lower end faces 86 and 87, and since no power source is required on the transmission source side (liquid level side), the liquid level is maintained even when power is lost. It can be reliably monitored.
Furthermore, since the liquid level can be monitored based on the presence or absence of liquid permeation into the liquid absorbing material 88, when there is an obstacle around the liquid level monitoring apparatus 100 (thermoacoustic device 80), or the liquid level is waved. It is difficult to monitor with other types of liquid level detection means (for example, ultrasonic liquid level sensor, pressure liquid level sensor, bubble liquid level sensor, or float type liquid level sensor). In this case, the liquid level can be monitored appropriately.

  The outer surface of the hollow container 81 on the upper side of the stack 85 may not be covered with the liquid absorbing material 88. According to this configuration, since the outer surface of the hollow container 81 on the upper side of the stack 85 is not covered with the liquid absorbing material, the internal space 90 of the hollow container 81 on the upper side of the stack 85 is affected by the temperature decrease due to vaporization heat. Is hardly affected. Therefore, the temperature difference between the upper and lower ends of the stack 85 becomes remarkable, and it can be detected more reliably that the liquid is immersed only in the lower part of the hollow container 81.

In one example configuration, when the distance in the height direction to the lower end face 87 of the stack 85 from the lower end of the inner space 90 (i.e. the upper surface of the bottom portion 84) was set to L _2, liquid absorbing material 88, from the lower end of the interior space 90 extends to a distance L ₁ in the height direction, the distance L ₁ is the distance L ₂ less.
In another configuration example, when the distance in the height direction to the upper end surface 86 of the stack 85 from the lower end (i.e. the upper surface of the bottom portion 84) of the interior space 90 and the L _3, liquid absorbing material 88, the lower end of the interior space 90 To a distance L ₂ in the height direction, and the distance L ₂ is equal to or less than the distance L ₃ .
According to these configurations, the area of the liquid absorbing material 88 can be secured, and thus the temperature difference between the upper and lower end surfaces 86 and 87 of the stack 85 can be made remarkable.

As an example of the configuration, the liquid absorbing material 88 includes at least a porous portion extending in the vertical direction. The porous portion has a large number of voids inside. In the example shown in FIG. 5, the case where all the areas of the liquid absorbing material 88 are formed of a porous material is shown.
As another configuration example, the liquid-absorbing material 88 includes a mesh portion extending at least in the vertical direction.
As the liquid absorbing material 88, for example, porous ceramic, sintered metal, metal mesh, foam metal, or the like can be used.

  According to these configurations, the liquid easily penetrates into the upper portion of the liquid absorbing material 88 that is not immersed in the liquid by the capillary phenomenon in the porous portion or the mesh portion of the liquid absorbing material 88. As a result, the liquid penetrates the entire liquid-absorbing material, and the heat of vaporization when the liquid vaporizes increases, so that the temperature difference between the upper and lower end surfaces 86 and 87 of the stack 85 becomes significant. Therefore, it can be reliably detected that the liquid has reached the hollow container 81.

  Furthermore, by using the liquid level monitoring device 100 for monitoring the coolant level in the nuclear power plant 1 (see FIG. 1), the liquid level in the nuclear power plant 1 can be appropriately monitored over a long period of time. In addition, since the sound can be generated according to the liquid level without a power source, the liquid level can be reliably monitored even when the power source is lost, and the safety of the nuclear power plant 1 can be improved.

As shown in FIGS. 1 and 2, in one embodiment, the liquid level monitoring device 100 (thermoacoustic device 80) is provided in the reactor vessel 11 of the nuclear power plant 1.
In this case, the liquid level monitoring device 100 may be provided in the annular gap 32 between the reactor vessel 11 and the reactor core 42.

  As shown in FIGS. 1 and 3, in another embodiment, the liquid level monitoring device 100 (thermoacoustic device 80) is provided in a coolant water chamber 65 provided below the steam generator 16 of the nuclear power plant 1. Is provided. In the example shown in FIG. 3, the liquid level monitoring device 100 is provided in the entrance chamber 65 b of the water chamber 65.

  As shown in FIG. 1, in still another embodiment, the liquid level monitoring apparatus 100 (thermoacoustic device 80) is connected to the reactor vessel 11 of the nuclear power plant 1 and is cooled for cooling the inside of the reactor vessel 11. It is provided in the pipe 17 through which the material flows. In the example shown in FIG. 1, the liquid level monitoring device 100 (thermoacoustic device 80) is disposed between the pressurizer 14 and the steam generator 16 and is provided in a pipe 17 that extends in the vertical direction. However, the piping 17 in which the liquid level monitoring apparatus 100 (thermoacoustic device 80) is installed is not limited to this. In another configuration example, the liquid level monitoring device 100 (thermoacoustic device 80) is disposed between the steam generator 16 and the primary coolant pump 18 and is provided in a pipe 17 extending in a substantially vertical direction. May be. In still another configuration example, the pipe 17 may be provided between the primary coolant pump 18 and the reactor vessel 11 and extend in a substantially vertical direction.

  Next, a liquid level monitoring method according to some embodiments will be described. In the following description, the reference numerals shown in FIGS. 1 to 5 are used as appropriate.

In the liquid level monitoring method according to some embodiments, when the lower side of the hollow container 81 provided along the vertical direction comes into contact with the liquid, the upper and lower end surfaces 86 and 87 of the stack 85 provided in the hollow container 81 are provided. A sound detection step of detecting a sound generated from the stack 85 due to a temperature difference of
In this sound detection step, the temperature difference between the upper and lower end surfaces 86 and 87 of the stack 85 is caused by the heat of vaporization of the liquid that has permeated the liquid absorbing material 88 provided so as to cover the outer surface of the hollow container 81 on the lower side of the stack 85. Give rise to

  According to this method, when the lower end side of the hollow container 81 is in contact with the liquid, the liquid penetrates the liquid absorbing material 88, and the liquid that has penetrated the liquid absorbing material 88 is vaporized from the outer surface of the hollow container 81 on the lower side of the stack. It takes heat and evaporates. For this reason, a temperature difference arises in the upper and lower end surfaces 86 and 87 of the stack 85, and the stack 85 generates sound. By detecting this sound, it can be grasped that the lower end side of the hollow container 81 is in contact with the liquid. As described above, in the above method, the stack 85 itself is configured to generate sound due to the temperature difference between the upper and lower end faces 86 and 87, so that it is not necessary to apply sound waves from the outside, and it is appropriate for a long period of time. The liquid level can be monitored.

Further, the stack 85 is configured to generate a sound due to a temperature difference between the upper and lower end faces 86 and 87, and no power source is required on the transmission source side (liquid level side). Can be reliably monitored.
Furthermore, since the liquid level can be monitored by the presence or absence of liquid permeation into the liquid absorbing material 88, other types of liquids are used, such as when there are obstacles around the liquid or when the liquid level is rippled. The liquid level can be appropriately monitored even in situations where it is difficult to monitor with a level detection means (for example, an ultrasonic liquid level sensor, a pressure liquid level sensor, a bubble liquid level sensor, or a float type liquid level sensor).

As described above, according to the above-described embodiment, when only the lower part of the liquid absorbent 88 provided on the outer surface of the hollow container 81 on the lower side of the stack is immersed in the liquid, the lower part of the liquid absorbent 88 is liquid. In order to suck up the liquid, the liquid also penetrates into the upper part of the liquid absorbing material 88. The liquid that has penetrated into the liquid absorbing material 88 takes the heat of vaporization from the outer surface of the hollow container 81 on the lower side of the stack and evaporates, and a temperature difference is generated between the upper and lower end faces 86 and 87 of the stack 85 of the hollow container 81. For this reason, the stack 85 generates sound due to the temperature difference between the upper and lower end faces 86 and 87 of the stack 85. By detecting this sound, it is possible to grasp that the lower end side of the hollow container 81 is in contact with the liquid, and the liquid level can be monitored.
In this way, the stack itself is configured to generate sound due to the temperature difference between the upper and lower end faces 86 and 87, so there is no need to apply sound waves from the outside, and the liquid level is appropriately monitored over a long period of time. be able to.

  The present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.

The ambient temperature of the thermoacoustic device 80 may be detected by the thermoacoustic device 80 in addition to the detection of the liquid level.
That is, the sound emitted from the stack 85 based on the above-described principle resonates in the upper space 91 or the lower space 92 to create a standing wave. The frequency of the standing wave depends on the length (vertical length) L of the upper space 91 or the lower space 92 as the resonance space and the internal temperature T of the thermoacoustic device 80. Therefore, by analyzing the frequency of the sound generated by the thermoacoustic device 80, the internal temperature T of the thermoacoustic device 80, and hence the ambient temperature of the thermoacoustic device 80, can be obtained.

For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expression “comprising”, “including”, or “having” one constituent element is not an exclusive expression that excludes the presence of the other constituent elements.

DESCRIPTION OF SYMBOLS 1 Nuclear power plant 2 Reactor system 3 Reactor 4 Turbine system 6 Generator 10 Primary cooling loop 11 Reactor vessel 14 Pressurizer 16 Steam generator 17 Piping 18 Primary coolant pump 19 Reactor containment vessel 20 Secondary cooling loop 21 High pressure Turbine 22 Low-pressure turbine 30 Reactor vessel main body 32 Annular space 42 Core tank 50 Fuel assembly 61 Body 62 Heat transfer tube 63 Tube support plate 65 Water chamber 80 Thermoacoustic device 81 Hollow vessel 82 Cylindrical portion 83 Lid portion 84 Bottom portion 85 Stack 86 Upper end surface 87 Lower end surface 88 Liquid absorbing material 90 Internal space 91 Upper space 92 Lower space 100 Liquid level monitoring device 102 Sound detector

Claims (11)

A hollow container provided along the vertical direction;
A stack provided in the hollow container and configured to generate sound due to a temperature difference between the upper and lower ends; and
A liquid level monitoring apparatus comprising: a liquid absorbing material provided to cover an outer surface of the hollow container on a lower side of the stack.   The liquid level monitoring device according to claim 1, wherein the liquid absorbing material includes at least a porous portion extending in a vertical direction.   The liquid level monitoring apparatus according to claim 1, wherein the liquid absorbing material includes at least a mesh portion extending in a vertical direction.   4. The liquid level monitoring apparatus according to claim 1, wherein an outer surface of the hollow container on the upper side of the stack is not covered with the liquid absorbing material. 5.   The liquid level monitoring apparatus according to any one of claims 1 to 4, wherein the liquid level monitoring apparatus is configured to monitor a liquid level of a coolant in a nuclear power plant.   The liquid level monitoring apparatus according to claim 5, wherein the liquid level monitoring apparatus is provided in a nuclear reactor vessel of the nuclear power plant.   The liquid level monitoring apparatus according to claim 5, wherein the liquid level monitoring apparatus is provided in an annular gap between the nuclear reactor vessel and the reactor core tank.   6. The liquid level monitoring apparatus according to claim 5, wherein the liquid level monitoring apparatus is provided in a coolant water chamber provided below a steam generator of the nuclear power plant.   The said liquid level monitoring apparatus is connected to the reactor vessel of the said nuclear power plant, It is provided in the piping through which the coolant for cooling the inside of the said reactor vessel flows. Liquid level monitoring device. A reactor including a reactor vessel;
A nuclear power plant comprising the liquid level monitoring device according to any one of claims 1 to 9 housed in the reactor vessel. A sound detecting step for detecting a sound generated from the stack due to a temperature difference between upper and lower ends of the stack provided in the hollow container when a lower side of the hollow container provided along the vertical direction comes into contact with the liquid; ,
In the sound detection step, a temperature difference between the upper and lower ends of the stack is generated by the heat of vaporization of the liquid that has permeated the liquid absorbing material provided so as to cover the outer surface of the hollow container on the lower side of the stack. A characteristic liquid level monitoring method.

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