Filter vent device

Abstract

To provide a filter vent device that suppresses oscillation caused by the release of vent gas through liquid acting as a wet filter, ensures the thickness of a liquid layer of the non-volatile liquid through which the vent gas passes, and suppresses reduction in a collection amount of organic iodine by the non-volatile liquid.SOLUTION: A filter vent device includes: a scrubbing water treatment part 6A that captures radioactive substances in the vent gas using scrubbing water 6 retained inside a filter vent vessel 1; a non-volatile liquid treatment part 7A that captures the radioactive substances in the vent gas that has passed through the scrubbing water treatment part 6A using non-volatile liquid 7; oscillation suppression means 10 that is provided so as to penetrate the liquid surface of the non-volatile liquid 7 and separates portions of the liquid surface of the non-volatile liquid 7 to suppress oscillation of the non-volatile liquid 7; an inlet pipe that connects a reactor containment vessel and the filter vent vessel 1; and an inlet valve that is provided on the inlet pipe, is closed during the normal operation of the nuclear power plant and opened during an accident at the nuclear power plant.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a filter vent device for removing radioactive substances in vent gas when it is necessary to discharge vent gas from a reactor containment vessel during a severe accident at a nuclear power plant.

Background Art

[0002] In nuclear power plants, installation of a filter vent system has been promoted to suppress the release of radioactive substances during venting. During abnormal or accident conditions in the reactor, the inside of the reactor containment vessel becomes high pressure, and there is a risk of damage to the reactor containment vessel. Therefore, as a measure to reduce the pressure inside the reactor containment vessel, venting of the gas inside the reactor containment vessel is carried out. The vent gas discharged from the reactor containment vessel is passed through a filter vent vessel using a wet filter, and after removing the main radioactive substances, it is released into the environment.

[0003] Radioactive substances contained in the vent gas include noble gases, aerosols, inorganic iodine, organic iodine, etc. A general filter vent vessel holds scrubbing water that acts as a wet filter. The scrubbing water mainly collects aerosols and inorganic iodine in the vent gas. The vent gas is passed through the scrubbing water and then undergoes treatment by a metal filter or an adsorbent. The metal filter collects aerosols remaining in the vent gas. The adsorbent mainly collects organic iodine in the vent gas.

[0004] Examples of adsorbents for collecting organic iodine include silver zeolite. However, since the adsorption capacity of the adsorbent decreases due to the adhesion of moisture, it is desirable to remove as much moisture as possible from the vent gas from the viewpoint of suppressing the amount of adsorbent used. There is also a method of installing a mechanism for removing moisture in a container of a dry filter containing the adsorbent, but it is not easy to construct a moisture removal system that operates without power during an emergency. In addition, increasing the adsorption capacity causes a problem that the installation location of the dry filter container is limited.

[0005] In response to such problems, as a means of collecting organic iodine in the vent gas, instead of an adsorbent, using a non-volatile liquid such as an ionic liquid has been considered. Patent Document 1 describes a technique of using a non-volatile liquid capable of collecting organic iodine together with scrubbing water. Patent Document 1 describes a configuration in which the non-volatile liquid does not mix with the scrubbing water and forms a liquid layer above the scrubbing water.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] At the bottom of the filter vent container, a nozzle for discharging the vent gas into the container is provided. The vent gas is discharged in a state of being bubbled into the liquid that acts as a wet filter stored in the filter vent container. When the vent gas is discharged into the liquid, the non-volatile liquid may swing due to the ejection flow from the nozzle, or the turbulence caused by the destruction and coalescence of bubbles, etc.

[0008] The amount of organic iodine collected by the non-volatile liquid depends on the contact time between the non-volatile liquid and the vent gas. The longer the moving distance of the vent gas in the non-volatile liquid, the longer the contact time, and the tendency is for the amount of organic iodine collected to increase. However, when the non-volatile liquid swings, the thickness of the non-volatile liquid through which the vent gas passes fluctuates. In the region where the thickness temporarily becomes thin, the contact time between the non-volatile liquid and the vent gas becomes short, resulting in a problem that the amount of organic iodine collected by the non-volatile liquid decreases.

[0009] Patent Document 1 describes that inside a filter vent container, scrubbing water and a non-volatile liquid exist in a phase-separated state from each other. A decrease in the amount of organic iodine collected due to the oscillation of the non-volatile liquid can occur not only when the non-volatile liquid forms an upper layer above the scrubbing water but also when the non-volatile liquid is used alone inside the container.

[0010] Patent Document 1 describes that inside a filter vent container, there is a flow path throttle plate for increasing the contact time between the non-volatile liquid and the vent gas. However, this flow path throttle plate is for increasing the water path length of the non-volatile liquid part. It is also assumed that a large amount of vent gas is discharged from inside the reactor containment vessel. A filter vent system is desired that can ensure the contact time between the non-volatile liquid and the vent gas while securing the cross-sectional area of the flow path through which the vent gas passes.

[0011] Therefore, an object of the present invention is to provide a filter vent device that suppresses the oscillation accompanying the release of vent gas of a liquid acting as a wet filter, secures the thickness of the liquid layer of the non-volatile liquid through which the vent gas passes, and suppresses a decrease in the amount of organic iodine collected by the non-volatile liquid.

[0012] To solve the above problems, a filter vent device according to the present invention is a filter vent device that removes radioactive substances in vent gas discharged from a reactor containment vessel of a nuclear power plant. The filter vent device includes a scrubbing water treatment unit that collects radioactive substances in the vent gas with scrubbing water held inside a filter vent container, a non-volatile liquid treatment unit that is configured inside the filter vent container or inside a collection container different from the filter vent container and collects radioactive substances in the vent gas that has passed through the scrubbing water treatment unit with a non-volatile liquid, a rocking suppression means that is provided so as to penetrate the liquid surface of the non-volatile liquid in the non-volatile liquid treatment unit and suppresses rocking of the non-volatile liquid by separating the liquid surfaces of the non-volatile liquid from each other, an inlet pipe that connects the reactor containment vessel and the filter vent container and supplies the vent gas to the filter vent container, and an inlet valve that is provided in the inlet pipe, is closed during normal operation of the nuclear power plant, and is opened during an accident of the nuclear power plant.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a filter vent device that suppresses rocking accompanying the discharge of vent gas of a liquid that acts as a wet filter, ensures the thickness of the liquid layer of the non-volatile liquid through which the vent gas passes, and suppresses a decrease in the amount of organic iodine collected by the non-volatile liquid.

Brief Description of the Drawings

[0014]

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Figure 12

Mode for Carrying Out the Invention

[0015] Hereinafter, a filter vent device according to an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals are given to common configurations and redundant descriptions are omitted.

[0016] <First Embodiment> FIG. 1 is a diagram schematically showing a filter vent device according to the first embodiment installed in a nuclear power plant. As shown in FIG. 1, a nuclear power plant is provided with a reactor containment vessel 120 that houses a reactor pressure vessel 110. A filter vent device 100 is connected to the reactor containment vessel 120 via a pipe.

[0017] The filter vent device 100 is a device that removes radioactive substances in the vent gas discharged from the reactor containment vessel 120 of a nuclear power plant. The filter vent device 100 includes a filter vent container 1 that holds a liquid that acts as a wet filter. The filter vent device 100 is installed outside the reactor containment vessel 120. The filter vent device 100 is installed, for example, underground in the reactor building or outside the reactor building.

[0018] In a nuclear power plant, in the event of a serious accident in the reactor, the reactor pressure vessel 110 may be damaged, and steam containing radioactive substances inside the reactor pressure vessel 110 may be released into the reactor containment vessel 120. If the pressure inside the reactor containment vessel 120 becomes excessively high, the reactor containment vessel 120 may be damaged, leading to a possible large-scale leakage of radioactive substances. To prevent such a situation, venting is carried out as a measure to reduce the pressure inside the reactor containment vessel 120.

[0019] During venting, the gas inside the reactor containment vessel 120 is discharged from the reactor containment vessel 120. The vent gas vented from the reactor containment vessel 120 contains high-temperature and high-pressure steam from which the cooling water has evaporated and radioactive substances released from the reactor pressure vessel 110. Therefore, the vent gas is passed through the filter vent container 1, the main radioactive substances are collected, and then it is released to the outside of the nuclear power plant.

[0020] The reactor containment vessel 120 includes a dry well 121 in which the reactor pressure vessel 110 is housed and a wet well 122 in which a pressure suppression pool is formed. In the wet well 122, steam in the dry well 121 and steam escaped from the main steam system flow in through a vent pipe (not shown).

[0021] In the event of a serious accident in the reactor, the gas in the dry well 121 and the wet well 122 is sent to the filter vent container 1 through the inlet pipe 2. The inlet pipe 2 is a pipe connecting the reactor containment vessel 120 and the filter vent container 1. In FIG. 1, the inlet pipe 2 is composed of a dry well vent pipe 2a, a wet well vent pipe 2b, and a common pipe 2c.

[0022] One end of the dry well vent pipe 2a used for venting the dry well 121 is connected to the dry well 121. The other end of the dry well vent pipe 2a is connected to the common pipe 2c. The dry well vent pipe 2a is provided with an inlet valve 3a which is a normally closed isolation valve. The inlet valve 3a is closed during the normal operation of the nuclear power plant and opened during an accident of the nuclear power plant. The inlet valve 3a is opened by remote operation from outside the shielding wall or operation at the site.

[0023] One end of the wet well vent pipe 2b used for venting the gas of the wet well 122 is connected to the wet well 122. The other end of the wet well vent pipe 2b is connected to the common pipe 2c. The wet well vent pipe 2b is provided with an inlet valve 3b which is a normally closed isolation valve. The inlet valve 3b is closed during the normal operation of the nuclear power plant and opened during an accident of the nuclear power plant. The inlet valve 3b is opened by remote operation from outside the shielding wall or operation at the site.

[0024] One end of the common pipe 2c is connected to the dry well vent pipe 2a and the wet well vent pipe 2b, and the other end extends to the inside of the filter vent container 1. The gas of the dry well 121 and the gas of the wet well 122 flow through the dry well vent pipe 2a and the wet well vent pipe 2b, and then flow into the inside of the filter vent container 1 through the common pipe 2c.

[0025] Figure 2 is a cross-sectional view schematically showing the structure of the filter vent container. Figure 2 shows the structure of the filter vent container 1 containing the scrubbing water 6 and the non-volatile liquid 7 as a wet filter. In Figure 2, the arrow indicates the flow of the vent gas. As shown in Figure 2, the filter vent container 1 includes a distribution pipe 4, a vent nozzle 5, a scrubbing water 6, a non-volatile liquid 7, and a metal filter 8. The filter vent container 1 is configured such that the scrubbing water 6 and the non-volatile liquid 7 are stored. Note that the scrubbing water 6 constitutes the scrubbing water treatment section 6A, and the non-volatile liquid 7 constitutes the non-volatile liquid treatment section 7A.

[0026] The filter vent container 1 is a container that performs a process of collecting radioactive substances in the vent gas. The filter vent container 1 is formed of a sealed container having heat resistance and pressure resistance. The filter vent container 1 houses a liquid that acts as a wet filter and a metal filter 8.

[0027] In FIG. 2, inside the filter vent container 1, scrubbing water 6 and a non-volatile liquid 7 that act as wet filters are held. The scrubbing water 6 and the non-volatile liquid 7 are housed in a mutually phase-separated state and form a two-layer liquid stacked vertically. The scrubbing water 6 forms the lower layer of the two-layer liquid. The non-volatile liquid 7 forms the upper layer of the two-layer liquid.

[0028] An inlet pipe 2 is connected to the inlet side of the filter vent container 1. The upstream end of the inlet pipe 2 is connected to the dry well 121 or the wet well 122 of the reactor containment vessel 120. The downstream side of the inlet pipe 2 is installed so as to penetrate the side wall of the filter vent container 1 and extend to the lower part inside the container. A distribution pipe 4 is connected to the downstream end of the inlet pipe 2. A plurality of vent nozzles 5 are connected to the distribution pipe 4.

[0029] The vent nozzle 5 is a nozzle that ejects the vent gas discharged from the reactor containment vessel 120 into the liquid inside the filter vent container 1. The vent nozzle 5 is installed on the lower side inside the filter vent container 1. A plurality of vent nozzles 5 are connected to the distribution pipe 4 at intervals from each other. The vent nozzle 5 is immersed in the liquid inside the filter vent container 1.

[0030] As the vent nozzle 5, for example, a Venturi nozzle is provided. The Venturi nozzle allows the vent gas to flow into the throat portion to generate a negative pressure. Droplets are sprayed into the vent gas by the negative pressure due to the Venturi effect to increase the contact area between the vent gas and the liquid. According to the vent nozzle 5, it becomes possible to efficiently collect radioactive substances in the vent gas by the liquid acting as a wet filter.

[0031] The scrubbing water 6 is an aqueous solution that reacts with inorganic iodine. The scrubbing water 6 is stored inside the filter vent container 1 to a depth at which the vent nozzle 5 is immersed and at which a gas phase is formed below the metal filter 8. The scrubbing water 6 mainly collects aerosols and inorganic iodine in the vent gas.

[0032] The non-volatile liquid 7 is a liquid that exhibits non-volatility and is composed of cations and anions. As the non-volatile liquid 7, a substance having a specific gravity smaller than that of the scrubbing water 6 is used. The non-volatile liquid 7 is stored above the scrubbing water 6 to a depth at which a gas phase is formed below the metal filter 8. The non-volatile liquid 7 mainly collects organic iodine in the vent gas. The organic iodine in the vent gas is mainly methyl iodide and exists mainly in a gaseous state.

[0033] As the non-volatile liquid 7, an ionic liquid, a surfactant solution showing non-volatility, etc. can be used. Specific examples of the non-volatile liquid 7 include trihexyl(tetradecyl)phosphonium chloride, trihexyl(tetradecyl)phosphonium dicyanamide, etc. Further, a hydrophobic substance having a specific gravity smaller than that of the scrubbing water 6 composed of an organic cation and an anion can be used.

[0034] Examples of the organic cation include imidazolium, pyridinium, ammonium, phosphonium, sulfonium, pyrrolidinium, piperidinium, etc. Examples of the anion include inorganic anions such as halogen, tetrafluoroborate, hexafluorophosphate, etc., and organic anions such as acetate, sulfonate, imidate, etc.

[0035] The metal filter 8 collects the aerosol released into the gas phase in the container by collision with the filter medium, adhesion to the filter medium by diffusion, etc. The metal filter 8 is provided on the upper side inside the filter vent container 1. The metal filter 8 is formed by laminating filter media such as metal fibers and metal meshes.

[0036] An outlet pipe 9 is connected to the outlet side of the filter vent container 1. The outlet pipe 9 is a pipe that connects the filter vent container 1 and the discharge port to the outside. The upstream end of the outlet pipe 9 is connected to the upper part of the filter vent container 1 on the secondary side of the metal filter 8 so as to communicate with the inside of the filter vent container 1. The downstream end of the outlet pipe 9 is connected to a discharge port provided in the reactor building or an exhaust stack.

[0037] During venting in a nuclear power plant, the inlet valves 3a and 3b provided in the inlet pipe 2 are opened. When the inlet valves 3a and 3b are opened, the steam containing radioactive substances inside the reactor containment vessel 120 flows into the filter vent container 1 through the inlet pipe 2. The vent gas vented from the reactor containment vessel 120 is injected into the liquid of the scrubbing water 6 by the vent nozzle 5.

[0038] The vent gas ejected into the liquid of the scrubbing water 6 becomes a bubbling state. The bubbles of the vent gas rise in the liquid in the container, pass through the liquid layer of the scrubbing water 6, and then pass through the liquid layer of the non-volatile liquid 7. While the bubbles of the vent gas pass through the liquid layer, the radioactive substances in the vent gas come into contact with the scrubbing water 6 and the non-volatile liquid 7 and are collected.

[0039] Among the radioactive substances in the vent gas, aerosol and inorganic iodine are collected by dissolution in the scrubbing water 6 or reaction with the scrubbing water 6. Organic iodine dissolves in the non-volatile liquid 7 and reacts with the non-volatile liquid 7. The radioactive iodine that formed the organic iodine is captured in the liquid. The aerosol released from the liquid phase part to the gas phase part is collected by the metal filter 8. The vent gas from which the main radioactive substances have been removed is released into the environment through the outlet pipe 9.

[0040] In the filter vent container 1 as shown in Fig. 2, the vent gas vented from the reactor containment vessel 120 is injected into the liquid in a bubbling state. When the vent gas jets into the liquid, the liquid stored in the container may sway due to the jet flow from the vent nozzle 5, or the turbulence caused by the destruction and coalescence of bubbles, etc.

[0041] When the liquid sways, the interface undulates, and the distance from the lower end to the upper end of the liquid layer changes. As shown in Fig. 2, in the case where the scrubbing water 6 forms the lower layer and the non-volatile liquid 7 forms the upper layer, and the vent gas is injected into the liquid of the scrubbing water 6, the interface between the scrubbing water 6 and the non-volatile liquid 7 and the interface between the non-volatile liquid 7 and the gas phase part undulate. Due to the undulation of the interface, the thickness of the liquid layer of the scrubbing water 6 and the thickness of the liquid layer of the non-volatile liquid 7 fluctuate, and regions where the thickness temporarily becomes thinner are locally generated.

[0042] In the region where the thickness of the liquid layer becomes thinner, the moving distance of the bubbles of the vent gas in the liquid becomes shorter, and the contact time between the liquid and the vent gas becomes shorter. Although it is desirable to mix or contact the non-volatile liquid 7 and the vent gas with high uniformity, when the contact time between the non-volatile liquid 7 and the vent gas becomes shorter, there arises a problem that the amount of radioactive substances collected by the non-volatile liquid 7 decreases.

[0043] Generally, as a method for ensuring the contact time between the liquid acting as a wet filter and the vent gas, there may be a method of increasing the volume of the liquid or a method of narrowing the flow path as in Patent Document 1. However, in the method of increasing the volume of the liquid, an increase in cost and an increase in the size of the container become problems. Also, in the method of narrowing the flow path, since the cross-sectional area of the liquid through which the bubbles of the vent gas pass becomes smaller, the throughput of the vent gas may decrease.

[0044] Therefore, in the filter vent device 100 according to the present embodiment, a swing suppression means 10 for suppressing the swing of the non-volatile liquid 7 is installed inside the filter vent container 1. As shown in FIG. 3, the swing suppression means 10 is provided in a structure that penetrates the liquid surface of the non-volatile liquid 7. Further, as shown in FIGS. 4, 5, and 6, the swing suppression means 10 is provided in a structure that separates the liquid surfaces of the non-volatile liquid 7 from each other in part.

[0045] FIG. 3 is a cross-sectional view schematically showing an example of a filter vent container according to the first embodiment. FIG. 3 shows a structure in which a swing suppression means 10 is installed in a part of a non-volatile liquid treatment section 7A of a filter vent container 1 that houses scrubbing water 6 (scrubbing water treatment section 6A) and a non-volatile liquid 7 (non-volatile liquid treatment section 7A) as a wet filter. In FIG. 3, the arrow indicates the flow of the vent gas. As shown in FIG. 3, the filter vent container 1 according to the present embodiment includes a distribution pipe 4, a vent nozzle 5, scrubbing water 6, a non-volatile liquid 7, a metal filter 8, and a swing suppression means 10.

[0046] The swing suppression means 10 is provided in a structure that vertically penetrates the liquid surface of the non-volatile liquid 7, that is, the interface between the non-volatile liquid 7 and the gas phase part. The swing suppression means 10 is installed such that the upper end is located above the liquid surface of the non-volatile liquid 7 and the lower end is located below the liquid surface of the non-volatile liquid 7. When the scrubbing water 6 and the non-volatile liquid 7 form a two-layer liquid, the swing suppression means 10 is preferably provided in a structure that penetrates the liquid layer of the non-volatile liquid 7 located above the scrubbing water 6. Further, it is preferably provided in a structure that separates the liquid layers of the non-volatile liquid 7 located above the scrubbing water 6 from each other in part.

[0047] Further, the swing suppression means 10 is provided in a structure that separates the liquid surfaces of the non-volatile liquid 7 in the non-volatile liquid treatment section 7A, that is, the interfaces between the non-volatile liquid 7 and the gas phase part, from each other in horizontally parallel parts. The swing suppression means 10 subdivides the liquid surface of the non-volatile liquid 7 into horizontally parallel partial regions having a smaller area, and makes the subdivided partial regions isolated from each other.

[0048] According to such a rocking suppression means 10, when the vent gas is released into the liquid, the rocking of the non-volatile liquid 7 can be suppressed. Even if a jet flow or bubbling is added to the liquid stored in the container, the wave caused by the jet flow or the turbulent flow is difficult to propagate in the horizontal direction, and the non-volatile liquid 7 is difficult to form waves. In addition, since the flow path of the bubbles of the vent gas ejected from the vent nozzle 5 is subdivided, an action of rectifying the bubbles can be obtained. By such an action of suppressing the rocking of the non-volatile liquid 7 and the action of rectifying the bubbles, the variation in the thickness of the liquid layer of the non-volatile liquid 7 is suppressed, so that it is difficult to generate a region where the thickness of the liquid layer is thin. Since it is possible to ensure the thickness of the liquid layer through which the vent gas passes and appropriately ensure the contact time between the non-volatile liquid 7 and the vent gas, it is possible to suppress a decrease in the amount of organic iodine collected by the non-volatile liquid 7.

[0049] Inside the filter vent container 1, the upper end of the rocking suppression means 10 is preferably disposed below the metal filter 8 and above the highest position of the liquid level of the non-volatile liquid 7. The highest position of the liquid level means the highest position reached by the interface between the non-volatile liquid 7 and the gas phase portion during the operation of the filter vent container 1. With such an arrangement, it is possible to effectively suppress the rocking of the non-volatile liquid 7 while avoiding interference with the surroundings.

[0050] Inside the filter vent container 1, the lower end of the rocking suppression means 10 is preferably disposed above the vent nozzle 5, below the interface between the scrubbing water 6 and the non-volatile liquid 7, and below the lowest water level in the filter vent container 1. The lowest water level means the lowest position of the liquid level that may decrease due to the evaporation of the scrubbing water 6 during the operation of the filter vent container 1. With such an arrangement, during the operation of the filter vent container 1, the rocking of the non-volatile liquid 7 above the scrubbing water 6 can be suppressed over the entire height of the liquid layer.

[0051] The oscillation suppression means 10 is preferably installed at least in a range where bubbles above the vent nozzle 5 reach in a plan view of the inside of the filter vent container 1 when viewed from the vertical direction, and more preferably installed in a range covering substantially the entire liquid surface of the non-volatile liquid 7.

[0052] The oscillation suppression means 10 can be formed by a metal pipe material, a plate material, a combination thereof, etc. By joining pipes, plates, or a pipe and a plate that form rectangular or circular partitions separating parts of the liquid surface to each other, the oscillation suppression means 10 can be formed to cover a predetermined range of the liquid surface. As the material of the oscillation suppression means 10, for example, stainless steel can be used. Examples of stainless steel include austenitic stainless steels such as SUS316, SUS316L, and SUS304. The oscillation suppression means 10 can be fixed, for example, by welding or the like to the inner surface of the filter vent container 1 or the outer surface of the inlet pipe 2.

[0053] Figs. 4, 5, and 6 are cross-sectional views of a filter vent container schematically showing shape examples of the oscillation suppression means. Figs. 4, 5, and 6 show the structure of the inside of the filter vent container 1 where the oscillation suppression means 10 is installed when viewed from above. As shown in Figs. 4, 5, and 6, the oscillation suppression means 10 can be provided in an appropriate shape as long as the liquid surface of the non-volatile liquid 7 is divided into parts.

[0054] Fig. 4 shows a form (oscillation suppression means 10A) in which the shape separating parts of the liquid surface of the non-volatile liquid 7 is lattice-shaped. The lattice-shaped oscillation suppression means 10A forms a plurality of rectangular partitions. The lattice-shaped oscillation suppression means 10A can be formed, for example, by a method of joining pipes with a rectangular cross-section or a method of combining plate materials. According to the lattice-shaped oscillation suppression means 10A, high durability can be obtained by firmly joining the partitions to each other.

[0055] FIG. 5 shows a form (oscillation suppressing means 10B) in which the shape separating the liquid levels of the non-volatile liquid 7 into parts is multi-tubular. The multi-tubular oscillation suppressing means 10B forms a plurality of circular partitions. The multi-tubular oscillation suppressing means 10B can be formed, for example, by a method of joining pipe materials having a circular cross-section. According to the multi-tubular oscillation suppressing means 10B, the manufacturing cost can be reduced by using general circular pipes.

[0056] FIG. 6 shows a form (oscillation suppressing means 10C) in which the shape separating the liquid levels of the non-volatile liquid 7 into parts is radial. The radial oscillation suppressing means 10C forms a plurality of fan-shaped partitions. The radial oscillation suppressing means 10C can be formed, for example, by a method of combining plate materials. According to the radial oscillation suppressing means 10C, the liquid level of the non-volatile liquid 7 can be widely subdivided by a small number of members.

[0057] Note that the number of parts separated from each other by the oscillation suppressing means 10 is not particularly limited. As long as the liquid level of the non-volatile liquid 7 is subdivided compared to the case where the oscillation suppressing means 10 is not present, it can be separated into parts with any shape and any number. The shape separating the liquid levels of the non-volatile liquid 7 into parts may be composed of one kind of shape or a plurality of kinds of shapes.

[0058] FIG. 7 is a cross-sectional view schematically showing an example of a filter vent container according to the first embodiment. FIG. 7 shows a structure in which an oscillation suppressing means 10 and a bubble rectifying means 12 are installed in a filter vent container 1 containing scrubbing water 6 and a non-volatile liquid 7 as a wet filter. In FIG. 7, the arrow indicates the flow of the vent gas. As shown in FIG. 7, inside the filter vent container 1, in addition to the oscillation suppressing means 10, a bubble rectifying means 12 can also be installed.

[0059] The bubble rectifying means 12 is composed of a member with pores formed therein. The bubble rectifying means 12 is a means for subdividing the bubbles heading towards the liquid surface of the non-volatile liquid and rectifying the bubbles heading towards the liquid surface of the non-volatile liquid. As the bubble rectifying means 12, a member having a plurality of through-holes penetrating the member vertically can be used. The through-holes are provided with an inner diameter through which only bubbles smaller than a predetermined diameter can pass, and are arranged at a predetermined interval.

[0060] According to such bubble rectifying means 12, when the vent gas is released into the liquid, the bubbles of the vent gas can be subdivided, and the contact area between the vent gas and the non-volatile liquid 7 can be enlarged. Further, the bubbles heading towards the liquid surface of the non-volatile liquid 7 can be rectified, and the coalescence of bubbles and the turbulent flow of the liquid can be suppressed. Since small bubbles can pass through the non-volatile liquid 7, the collection amount of organic iodine by the non-volatile liquid 7 can be improved. Also, compared with the case where the oscillation suppressing means 10 is used alone, the oscillation of the non-volatile liquid 7 can be more effectively suppressed.

[0061] Inside the filter vent container 1, the bubble rectifying means 12 is preferably disposed below the oscillation suppressing means 10. Further, the bubble rectifying means 12 is preferably disposed above the vent nozzle 5. The bubble rectifying means 12 may be disposed separately from the oscillation suppressing means 10, or may be disposed integrally with the oscillation suppressing means 10.

[0062] In a plan view of the inside of the filter vent container 1 when viewed from the vertical direction, the bubble rectifying means 12 is preferably installed at least in a range where the bubbles above the vent nozzle 5 reach, and more preferably installed in a range covering substantially the entire liquid surface of the non-volatile liquid 7.

[0063] The bubble rectifying means 12 can be formed, for example, by a punching metal or a plate material in which a plurality of regularly arranged through holes are formed. As the material of the bubble rectifying means 12, for example, stainless steel can be used. Examples of the stainless steel include austenitic stainless steels such as SUS316, SUS316L, and SUS304. The bubble rectifying means 12 can be fixed, for example, by welding or the like to the inner surface of the filter vent container 1 or the outer surface of the inlet pipe 2.

[0064] According to the filter vent device 100 provided with the above-described rocking suppression means 10, since the rocking of the nonvolatile liquid 7 accompanying the discharge of the vent gas into the container can be suppressed, the thickness of the liquid layer of the nonvolatile liquid 7 through which the bubbles of the vent gas pass can be stably maintained at a thickness of a certain level or more. The contact time between the nonvolatile liquid 7 and the vent gas can be ensured to be a certain level or more, and the nonvolatile liquid 7 and the vent gas can be mixed or brought into contact with high uniformity. Therefore, the rocking accompanying the discharge of the vent gas of the nonvolatile liquid 7 acting as a wet filter can be suppressed, the thickness of the liquid layer through which the vent gas passes can be ensured, and the decrease in the amount of organic iodine collected by the nonvolatile liquid 7 can be suppressed. Therefore, the leakage of radioactive substances into the environment can be stably prevented.

[0065] In particular, according to the filter vent device 100 provided with the above-described rocking suppression means 10, since it is not necessary to narrow the flow path through which the vent gas passes inside the filter vent container 1, it is possible to easily ensure a large cross-sectional area for the flow path through which the vent gas passes. By expanding the cross-sectional area, the amount of vent gas that can be processed increases, so that a large amount of vent gas discharge can be accommodated. Since the capacity of the nonvolatile liquid 7 stored inside the filter vent container 1 can be suppressed, an increase in cost and an increase in the size of the container can be avoided.

[0066] In addition, according to the filter vent device 100 provided with the swing suppression means 10 and the bubble rectification means 12, the bubbles refined and rectified by the bubble rectification means 12 can reach the periphery of the swing suppression means 10. The bubbles of the vent gas are subdivided to expand the contact area between the vent gas and the non-volatile liquid 7, and the turbulent flow of the scrubbing water 6 and the non-volatile liquid 7 is suppressed, thereby suppressing the swing of the non-volatile liquid 7. Therefore, a decrease in the amount of organic iodine collected by the non-volatile liquid 7 can be suppressed, and the amount of organic iodine collected can be maintained at a high level.

[0067] <Second Embodiment> FIG. 8 is a diagram schematically showing a filter vent device according to a second embodiment installed in a nuclear power plant. As shown in FIG. 8, a nuclear power plant may be provided with a filter vent device 200 including a filter vent container 1 and a collection container 15 as a filter vent device for removing radioactive substances in vent gas.

[0068] Similar to the filter vent device 100 described above, the filter vent device 200 is a device for removing radioactive substances in the vent gas discharged from the reactor containment vessel 120 of a nuclear power plant. The filter vent device 200 includes a filter vent container 1 that holds scrubbing water 6 acting as a wet filter, and a collection container 15 that holds a non-volatile liquid 7 acting as a wet filter. Similar to the filter vent device 100 described above, the filter vent device 200 is installed outside the reactor containment vessel 120.

[0069] In the filter vent device 200, the filter vent container 1 is connected to the reactor containment vessel 120 via a dry well vent pipe 2a, a wet well vent pipe 2b, and a common pipe 2c. The collection container 15 is connected to the filter vent container 1 via a relay pipe 14. An outlet pipe 16 is connected to the collection container 15.

[0070] During venting, the vent gas vented from the inside of the reactor containment vessel 120 is passed through the filter vent vessel 1 and the collection vessel 15 in this order, and after the main radioactive substances are collected, it is discharged to the outside of the nuclear power plant.

[0071] In the filter vent device 200, only the scrubbing water 6 is provided as a wet filter in the filter vent vessel 1. Among the radioactive substances in the vent gas, aerosol and inorganic iodine are collected in the filter vent vessel 1. Only the non-volatile liquid 7 is provided as a wet filter in the collection vessel 15. Organic iodine is collected in the collection vessel 15.

[0072] FIG. 9 is a cross-sectional view schematically showing an example of the collection vessel according to the second embodiment. FIG. 9 shows a structure in which a swing suppression means 10 is installed in a collection vessel 15 containing a non-volatile liquid 7 as a wet filter. In FIG. 9, the arrow indicates the flow of the vent gas. As shown in FIG. 9, the collection vessel 15 according to the present embodiment includes a distribution pipe 4, a vent nozzle 5, a non-volatile liquid 7, and a swing suppression means 10.

[0073] The collection vessel 15 is a vessel that performs a process of collecting radioactive substances in the vent gas. In the collection vessel 15, organic iodine is collected by the non-volatile liquid 7. The collection vessel 15 is formed of a hermetically sealed vessel having heat resistance and pressure resistance. In FIG. 9, the collection vessel 15 is provided as a vertically placed vessel.

[0074] A relay pipe 14 is connected to the inlet side of the collection vessel 15. The upstream end of the relay pipe 14 is connected to the upper part of the filter vent vessel 1 on the secondary side of the metal filter 8 so as to communicate with the inside of the filter vent vessel 1. The downstream side of the relay pipe 14 is installed so as to penetrate the side wall of the collection vessel 15 and extend to the lower part inside the vessel. A distribution pipe 4 is connected to the downstream end of the relay pipe 14. A plurality of vent nozzles 5 are connected to the distribution pipe 4.

[0075] On the outlet side of the collection container 15, an outlet pipe 16 is connected. The outlet pipe 16 is a pipe that connects the collection container 15 and the discharge port to the outside. The upstream end of the outlet pipe 16 is connected to the upper part of the collection container 15 so as to communicate with the gas phase part inside the collection container 15. The downstream end of the outlet pipe 16 is connected to a discharge port provided in the reactor building or an exhaust stack.

[0076] Inside the collection container 15, a non-volatile liquid 7 is held to form a non-volatile liquid treatment part 7A. The non-volatile liquid 7 is stored alone in the container to form a single-layer liquid. The vent gas discharged from the vent nozzle 5 moves through the liquid layer from the discharge port of the vent nozzle 5 to the liquid level of the non-volatile liquid 7.

[0077] Inside the collection container 15, a swing suppression means 10 is installed. The swing suppression means 10 is provided in a structure that penetrates the liquid level of the non-volatile liquid 7, that is, the interface between the non-volatile liquid 7 and the gas phase part. Further, the swing suppression means 10 is provided in a structure that separates the parts of the liquid level of the non-volatile liquid 7, that is, the interface between the non-volatile liquid 7 and the gas phase part from each other.

[0078] During venting in the nuclear power plant, the inlet valves 3a, 3b provided in the inlet pipe 2 are opened. When the inlet valves 3a, 3b are opened, the vapor containing radioactive substances inside the reactor containment vessel 120 flows into the filter vent container 1 through the inlet pipe 2. In the filter vent container 1, aerosols and inorganic iodine in the vent gas are collected. The aerosol discharged from the liquid phase part to the gas phase part is collected by the metal filter 8. Then, the vent gas treated in the filter vent container 1 flows into the collection container 15. The vent gas is injected into the non-volatile liquid 7 by the vent nozzle 5.

[0079] The vent gas ejected into the non-volatile liquid 7 becomes bubbling. The bubbles of the vent gas pass through the liquid layer of the non-volatile liquid 7. While the bubbles of the vent gas pass through the liquid layer, the organic iodine in the vent gas comes into contact with the non-volatile liquid 7 and is collected. The organic iodine in the vent gas dissolves in the non-volatile liquid 7 and reacts with the non-volatile liquid 7. The radioactive iodine that formed the organic iodine is collected in the liquid of the non-volatile liquid 7. The vent gas from which the main radioactive substances have been removed is discharged into the environment through the outlet pipe 16.

[0080] In the collection container 15 as shown in FIG. 9, the vent gas treated by the filter vent container 1 is injected into the liquid in a bubbling state. When the vent gas is ejected into the liquid, the liquid stored in the container may swing due to the ejection flow from the vent nozzle 5, or the turbulent flow caused by the destruction and coalescence of bubbles, etc. Such swinging of the non-volatile liquid 7 is suppressed by the swing suppression means 10 installed inside the collection container 15.

[0081] Inside the collection container 15, it is preferable that the upper end of the swing suppression means 10 is arranged above the highest position of the liquid level of the non-volatile liquid 7. The highest position of the liquid level means the highest position that the interface between the non-volatile liquid 7 and the gas phase part reaches during the operation of the collection container 15. With such an arrangement, while avoiding interference with the surroundings, the swinging of the non-volatile liquid 7 can be effectively suppressed near the liquid level.

[0082] Inside the collection container 15, it is preferable that the lower end of the swing suppression means 10 is above the vent nozzle 5 and below the lowest position of the liquid level of the non-volatile liquid 7. The lowest position of the liquid level means the lowest position that the interface between the non-volatile liquid 7 and the gas phase part reaches during the operation of the collection container 15. With such an arrangement, while avoiding interference with the vent nozzle 5, the swinging of the non-volatile liquid 7 can be effectively suppressed near the liquid level.

[0083] The oscillation suppression means 10 is preferably installed at least in a range where the bubbles above the vent nozzle 5 reach in a plan view of the inside of the collection container 15 when viewed from the vertical direction, and more preferably installed in a range covering substantially the entire liquid surface of the non-volatile liquid 7.

[0084] The oscillation suppression means 10 can be fixed, for example, by welding or the like to the inner surface of the collection container 15 or the outer surface of the relay pipe 14.

[0085] FIG. 10 is a cross-sectional view schematically showing an example of a collection container according to the second embodiment. FIG. 10 shows a structure in which an oscillation suppression means 10 and a bubble rectifying means 12 are installed in a collection container 15 containing a non-volatile liquid 7 as a wet filter. In FIG. 10, the arrow indicates the flow of the vent gas. As shown in FIG. 10, inside the collection container 15, in addition to the oscillation suppression means 10, a bubble rectifying means 12 can also be installed.

[0086] Inside the collection container 15, the bubble rectifying means 12 is preferably disposed below the oscillation suppression means 10. Also, the bubble rectifying means 12 is preferably disposed above the vent nozzle 5. The bubble rectifying means 12 may be disposed as a separate body from the oscillation suppression means 10, or may be disposed integrally with the oscillation suppression means 10.

[0087] The bubble rectifying means 12 is preferably installed at least in a range where the bubbles above the vent nozzle 5 reach in a plan view of the inside of the collection container 15 when viewed from the vertical direction, and more preferably installed in a range covering substantially the entire liquid surface of the non-volatile liquid 7.

[0088] The bubble rectifying means 12 can be formed, for example, by a perforated metal or a plate material in which a plurality of regularly arranged through holes are formed. As the material of the bubble rectifying means 12, for example, stainless steel can be used. Examples of the stainless steel include austenitic stainless steels such as SUS316, SUS316L, and SUS304. The bubble rectifying means 12 can be fixed, for example, by welding or the like to the inner surface of the collection container 15 or the outer surface of the relay pipe 14.

[0089] According to the filter vent device 200 provided with the above-described oscillation suppressing means 10, since the oscillation of the non-volatile liquid 7 accompanying the discharge of the vent gas into the container can be suppressed, the thickness of the liquid layer of the non-volatile liquid 7 through which the bubbles of the vent gas pass can be stably maintained at a thickness of a certain level or more. By ensuring that the contact time between the non-volatile liquid 7 and the vent gas is a certain level or more, it becomes possible to mix or bring the non-volatile liquid 7 and the vent gas into contact with high uniformity. Therefore, it is possible to suppress the oscillation accompanying the discharge of the vent gas of the non-volatile liquid 7 acting as a wet filter, ensure the thickness of the liquid layer through which the vent gas passes, and suppress a decrease in the amount of organic iodine collected by the non-volatile liquid 7.

[0090] In particular, according to the filter vent device 200 provided with the above-described oscillation suppressing means 10, since the non-volatile liquid 7 is held inside a collection container 15 different from the filter vent container 1, the degree of freedom of the volume of the non-volatile liquid can be expanded. When using an existing filter vent container as a container for holding scrubbing water, since the overall water level rises, depending on the size of the container, it may be difficult to fill the non-volatile liquid. Even in such a case, it becomes possible to use a large volume of non-volatile liquid. Since it is possible to avoid increasing the size of the filter vent container 1, it becomes easier to secure an installation location for the system.

[0091] Further, according to the filter vent device 200 provided with the oscillation suppressing means 10 and the bubble rectifying means 12, the bubbles refined and rectified by the bubble rectifying means 12 can reach the periphery of the oscillation suppressing means 10. By subdividing the bubbles of the vent gas, the contact area between the vent gas and the non-volatile liquid 7 can be expanded, and the turbulent flow of the non-volatile liquid 7 can be suppressed, thereby suppressing the oscillation of the non-volatile liquid 7. Therefore, a decrease in the amount of organic iodine collected by the non-volatile liquid 7 can be suppressed, and the amount of organic iodine collected can be maintained at a high level.

[0092] FIG. 11 is a cross-sectional view schematically showing an example of a collection container according to the second embodiment. FIG. 11 shows a structure in which a swing suppression means 10 is installed in a horizontally placed collection container 18 that houses a non-volatile liquid 7 as a wet filter. In FIG. 11, the arrow indicates the flow of the vent gas. As shown in FIG. 11, the container that holds the non-volatile liquid 7 acting as a wet filter can also be a horizontally placed collection container 18.

[0093] The horizontally placed collection container 18 is a container that performs a process of collecting radioactive substances in the vent gas. In the collection container 18, the collection of organic iodine by the non-volatile liquid 7 is performed. The collection container 18 is formed of a hermetically sealed container having heat resistance and pressure resistance. The horizontally placed collection container 18 is provided such that the width in the vertical direction is shorter than the width in the horizontal direction.

[0094] A relay pipe 17 is connected to the inlet side of the horizontally placed collection container 18. The upstream end of the relay pipe 17 is connected to the upper part of the filter vent container 1 on the secondary side of the metal filter 8 so as to communicate with the inside of the filter vent container 1. The downstream side of the relay pipe 17 is installed so as to penetrate the side wall of the collection container 18 and extend to the lower part inside the container. A distribution pipe 4 is connected to the downstream end of the relay pipe 17. A plurality of vent nozzles 5 are connected to the distribution pipe 4.

[0095] An inner tank 19 is provided inside the horizontally placed collection container 18. The inner tank 19 is provided with a horizontally long structure with an open upper part, and the inside of the tank is open to the space inside the collection container 18. The inner tank 19 is provided such that the width in the vertical direction is shorter than the width in the horizontal direction. Inside the inner tank 19, a distribution pipe 4 is laid so as to extend horizontally on the lower side, and a plurality of vent nozzles 5 are installed at intervals from each other.

[0096] An outlet pipe 20 is connected to the outlet side of the horizontally placed collection container 18. The outlet pipe 20 is a pipe that connects the collection container 18 and the outlet to the outside. The upstream end of the outlet pipe 20 is connected to the side surface of the collection container 18 so as to communicate with the gas phase part inside the collection container 18. The downstream end of the outlet pipe 20 is connected to an outlet provided in the reactor building or an exhaust stack.

[0097] Inside the inner tank 19 of the horizontally placed collection container 18, a non-volatile liquid 7 that constitutes the non-volatile liquid treatment unit 7A is held. The non-volatile liquid 7 is stored alone in the inner tank 19 to form a single-layer liquid. The vent gas discharged from the vent nozzle 5 moves through the liquid layer from the discharge port of the vent nozzle 5 to the liquid surface of the non-volatile liquid 7. Since the inner tank 19 is provided with a horizontally long structure that easily secures a horizontal width, by dispersedly installing the vent nozzles 5, the bubbles of the vent gas can be discretely discharged along the horizontal direction.

[0098] Inside the inner tank 19 of the horizontally placed collection container 18, a swing suppression means 10 is installed. The swing suppression means 10 is provided with a structure that penetrates the liquid surface of the non-volatile liquid 7, that is, the interface between the non-volatile liquid 7 and the gas phase part. Further, the swing suppression means 10 is provided with a structure that separates the liquid surface of the non-volatile liquid 7, that is, the interfaces of the non-volatile liquid 7 and the gas phase part from each other.

[0099] During venting in the nuclear power plant, the inlet valves 3a, 3b provided in the inlet pipe 2 are opened. When the inlet valves 3a, 3b are opened, the vapor containing radioactive substances inside the reactor containment vessel 120 flows into the filter vent container 1 through the inlet pipe 2. In the filter vent container 1, aerosols and inorganic iodine in the vent gas are collected. The aerosol discharged from the liquid phase part to the gas phase part is collected by the metal filter 8. Then, the vent gas treated in the filter vent container 1 flows into the collection container 18. The vent gas is injected into the liquid of the non-volatile liquid 7 by the vent nozzle 5.

[0100] The vent gas ejected into the non-volatile liquid 7 becomes bubbling. The bubbles of the vent gas pass through the liquid layer of the non-volatile liquid 7. While the bubbles of the vent gas pass through the liquid layer, the organic iodine in the vent gas comes into contact with the non-volatile liquid 7 and is collected. The organic iodine in the vent gas dissolves in the non-volatile liquid 7 and reacts with the non-volatile liquid 7. The radioactive iodine that formed the organic iodine is collected in the liquid of the non-volatile liquid 7. The vent gas from which the main radioactive substances have been removed is discharged into the environment through the outlet pipe 20.

[0101] In the horizontal collection container 18 as shown in FIG. 11, the vent gas treated in the filter vent container 1 is injected into the liquid in a bubbling state. When the vent gas is ejected into the liquid, the liquid stored in the container may swing due to the ejection flow from the vent nozzle 5, or the turbulence caused by the destruction and coalescence of bubbles, etc. Such swinging of the non-volatile liquid 7 is suppressed by the swing suppression means 10 installed inside the collection container 18.

[0102] Inside the inner tank 19 of the horizontal collection container 18, it is preferable that the upper end of the swing suppression means 10 is arranged above the highest position of the liquid level of the non-volatile liquid 7. The highest position of the liquid level means the highest position that the interface between the non-volatile liquid 7 and the gas phase part reaches during the operation of the collection container 18. With such an arrangement, the swinging of the non-volatile liquid 7 can be effectively suppressed near the liquid surface.

[0103] Inside the inner tank 19 of the horizontal collection container 18, it is preferable that the lower end of the swing suppression means 10 is above the vent nozzle 5 and below the lowest position of the liquid level of the non-volatile liquid 7. The lowest position of the liquid level means the lowest position that the interface between the non-volatile liquid 7 and the gas phase part reaches during the operation of the collection container 18. With such an arrangement, while avoiding interference with the vent nozzle 5, the swinging of the non-volatile liquid 7 can be effectively suppressed near the liquid surface.

[0104] The oscillation suppression means 10 is preferably installed at least in the range where the bubbles above the vent nozzle 5 reach in a plan view of the inside of the inner tank 19 as viewed from the vertical direction, and more preferably installed in the range covering substantially the entire liquid surface of the non-volatile liquid 7.

[0105] The oscillation suppression means 10 can be fixed, for example, by welding or the like to the inner surface of the inner tank 19 or the inner surface of the collection container 18.

[0106] FIG. 12 is a cross-sectional view schematically showing an example of the collection container according to the second embodiment. FIG. 12 shows a structure in which an oscillation suppression means 10 and a bubble rectification means 12 are installed in a horizontally placed collection container 18 containing a non-volatile liquid 7 as a wet filter. In FIG. 12, the arrow indicates the flow of the vent gas. As shown in FIG. 12, inside the horizontally placed collection container 18, in addition to the oscillation suppression means 10, a bubble rectification means 12 can also be installed.

[0107] Inside the inner tank 19 of the horizontally placed collection container 18, the bubble rectification means 12 is preferably arranged below the oscillation suppression means 10. Also, the bubble rectification means 12 is preferably arranged above the vent nozzle 5. The bubble rectification means 12 may be arranged as a separate body from the oscillation suppression means 10, or may be arranged integrally with the oscillation suppression means 10.

[0108] The bubble rectification means 12 is preferably installed at least in the range where the bubbles above the vent nozzle 5 reach in a plan view of the inside of the inner tank 19 as viewed from the vertical direction, and more preferably installed in the range covering substantially the entire liquid surface of the non-volatile liquid 7.

[0109] The bubble rectification means 12 can be fixed, for example, by welding or the like to the inner surface of the inner tank 19 or the inner surface of the collection container 18.

[0110] According to such a horizontally placed collection container 18, the overall height of the container can be reduced, making it easier to secure an installation location for the system. Enlargement of the filter vent container 1 is avoided, and the overall height of the collection container 18 is suppressed, so it can be easily installed underground in a reactor building or the like. Since the overall height of the collection container 18 is suppressed, it can be easily installed in a location where the height is restricted, such as a trench where the outlet pipe is laid. Also, since a large cross-sectional area in the liquid through which the bubbles of the vent gas pass can be ensured, rectification of the bubbles and treatment of a large volume of vent gas can be realized while ensuring the treatment amount of the vent gas.

[0111] In the horizontally placed collection container 18, the oscillation suppression means 10 not only suppresses the oscillation of the non-volatile liquid 7 due to the ejection of the vent gas, but also suppresses the overflow of the non-volatile liquid 7 due to sloshing during an earthquake or the like. Therefore, by installing the oscillation suppression means 10, it becomes possible to provide a horizontally placed collection container 18 that is less likely to cause a decrease in the collection amount of organic iodine and has high robustness.

[0112] As described above, the embodiments of the present invention have been explained, but the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, the present invention is not necessarily limited to those having all the configurations provided in the above-described embodiments. A part of the configuration of one embodiment can be replaced with another configuration, a part of the configuration of one embodiment can be added to another form, or a part of the configuration of one embodiment can be omitted.

[0113] For example, a filter vent device provided with oscillation suppression means can be installed in any type of nuclear reactor. Examples of the type of nuclear reactor include a boiling water reactor (BWR), an advanced boiling water reactor (ABWR), a pressurized water reactor (PWR), and the like. The structures of the nuclear reactor pressure vessel and the nuclear reactor containment vessel are not particularly limited.

Explanation of reference numerals

[0114] 1 Filter vent container 2a Dry well vent pipe (inlet pipe) 2b Wet well vent pipe (inlet pipe) 2c Common pipe (inlet pipe) 3a Inlet valve 3b Inlet valve 4 Distribution pipe 5 Vent nozzle 6 Scrubbing water 6A Scrubbing water treatment section 7 Non-volatile liquid 7A Non-volatile liquid treatment section 8 Metal filter 9 Outlet pipe 10 Vibration suppression means 12 Bubble rectification means 14 Relay pipe 15 Collection container (vertically placed type) 16 Outlet pipe 17 Relay pipe 18 Collection container (horizontally placed type) 19 Inner tank 20 Outlet pipe 100 Filter vent device 110 Reactor pressure vessel 120 Reactor containment vessel 121 Dry well 122 Wet well 200 Filter vent device

Claims

1. A filter vent device for removing radioactive substances in vent gas discharged from a reactor containment vessel of a nuclear power plant, comprising: a scrubbing water treatment section that collects radioactive substances in the vent gas with scrubbing water held inside a filter vent container; a non-volatile liquid treatment section that is configured inside the filter vent container or inside a collection container different from the filter vent container, and collects radioactive substances in the vent gas that has passed through the scrubbing water treatment section with a non-volatile liquid; in the non-volatile liquid treatment section, a rocking suppression means that is provided so as to penetrate the liquid level of the non-volatile liquid, and suppresses rocking of the non-volatile liquid by separating the liquid levels of the non-volatile liquid from each other; an inlet pipe that connects the reactor containment vessel and the filter vent container and supplies the vent gas to the filter vent container; an inlet valve that is provided in the inlet pipe, is closed during normal operation of the nuclear power plant, and is opened during an accident of the nuclear power plant.

2. The filter vent device according to claim 1, wherein: the non-volatile liquid is held inside the filter vent container, and is phase-separated from the scrubbing water that constitutes the scrubbing water treatment section, and forms a liquid layer as the non-volatile liquid treatment section above the scrubbing water; the rocking suppression means is provided inside the filter vent container so as to penetrate the liquid layer as the non-volatile liquid treatment section, and suppresses rocking of the non-volatile liquid by separating the liquid layers of the non-volatile liquid from each other.

3. The filter vent device according to claim 1, wherein: the non-volatile liquid is held in a collection container provided downstream of the filter vent container and constitutes the non-volatile liquid treatment section inside the collection container; the rocking suppression means is a filter vent device provided inside the collection container.

4. The filter vent device according to claim 1, wherein: the rocking suppression means has a shape that separates the liquid levels from each other and is a lattice shape forming a plurality of rectangular partitions, a multi-tubular shape forming a plurality of circular partitions, or a radial shape forming a plurality of fan-shaped partitions.

5. The filter vent device according to claim 1, wherein: The swing suppression means is a filter vent device formed by a combination of pipe materials.

6. The filter vent device according to claim 1, The filter vent device having bubble rectifying means in which pores are formed to subdivide and rectify bubbles directed toward the liquid surface of the non-volatile liquid.

7. The filter vent device according to claim 6, The non-volatile liquid is held inside the filter vent container, The swing suppression means is provided inside the filter vent container, The filter vent device in which the bubble rectifying means is provided below the swing suppression means inside the filter vent container.

8. The filter vent device according to claim 6, The non-volatile liquid is held in a collection container provided downstream of the filter vent container, The swing suppression means is provided inside the collection container, The filter vent device in which the bubble rectifying means is provided below the swing suppression means inside the collection container.

9. The filter vent device according to claim 6, The filter vent device in which the bubble rectifying means is formed of perforated metal.

10. The filter vent device according to claim 1, The non-volatile liquid is held in a collection container provided downstream of the filter vent container, The collection container is a horizontally placed container, and the filter vent device holds the non-volatile liquid in an inner tank provided with a shorter vertical width than the horizontal width.

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