JP7261776B2 - Reactor containment venting system - Google Patents

Description

The present invention relates to a containment vessel vent system, and more particularly to a containment vessel vent system for use in a boiling water reactor (BWR).

In a nuclear power plant, even in the unlikely event that the reactor core inside the reactor pressure vessel melts (hereafter referred to as a severe accident), the accident can be prevented by sufficiently injecting water and cooling the reactor containment vessel. designed to converge. However, if the containment vessel is insufficiently cooled during a severe accident, steam and hydrogen gas continue to be generated, increasing the pressure inside the containment vessel. In the event that the pressure rises excessively, in order to prevent damage to the containment vessel, the gas inside the containment vessel is released into the atmosphere (external environment) to reduce the pressure inside the containment vessel. do. This depressurization operation is called a venting operation.

In the venting operation of a boiling water reactor, the gas (vent gas) in the dry well of the containment vessel is first released into the pool water of the suppression pool of the wet well, and some of the radioactive materials contained in the vent gas are released. is removed by the scrubbing effect of the pool water. Furthermore, after removing the radioactive substances that could not be removed by scrubbing with the pool water from the vent gas, the vent gas is released into the atmosphere. A reactor containment vessel vent system is known as a system for removing radioactive substances from the vent gas in this venting operation (see, for example, Patent Document 1).

The reactor containment vessel vent system described in Patent Document 1 makes it possible to continuously release steam generated within the reactor containment vessel to the atmosphere even in the event of a power loss. It is intended for Specifically, a rare gas filter that allows steam and hydrogen gas out of the vent gas discharged from the reactor containment vessel and does not allow radioactive rare gas to pass is provided at the most downstream part of the vent line, and the part immediately upstream of the rare gas filter and the drywell of the containment vessel are connected by a return pipe through an intermediate vessel. Furthermore, the radioactive rare gas with a predetermined pressure or higher that has accumulated in the immediate upstream portion of the rare gas filter is allowed to flow into the intermediate container by means of a release valve.

JP 2019-124611 A

In the reactor containment vessel vent system described in Patent Document 1, the rare gas filter continuously releases water vapor and hydrogen gas to the atmosphere while collecting radioactive rare gases. Gases containing radioactive rare gases that cannot permeate the rare gas filter and remain in the immediate upstream part of the filter will move to the intermediate container without external power such as a power source when the pressure reaches the set pressure of the relief valve, and will flow through the return pipe. It is returned to the drywell of the containment vessel via the The radioactive noble gas returned to the drywell is released again into the pool water of the wetwell through the vent pipe. Thus, in the technique described in Patent Document 1, the radioactive noble gas contained in the vent gas is circulated from the drywell of the containment vessel back to the drywell through the containment vessel vent system. , preventing the release of radioactive noble gases into the external environment.

By the way, gas leakage points from the containment vessel to the outside of the containment vessel (reactor building) include the seals provided in the structure of the containment vessel that separates the dry well and the structure that separates the wet well. A provided seal is envisioned. For example, drywell main flanges for fastening the drywell head of the containment vessel, various hatches, airlocks, and other seals can be cited. However, the amount of gas leakage from the seal provided on the drywell side (for example, the seal on the main flange of the drywell) tends to be greater than the amount of gas leaked from the seal provided on the wetwell side. .

In the reactor containment vessel vent system described in Patent Document 1, as described above, the radioactive noble gas collected by the rare gas filter is returned into the dry well of the reactor containment vessel, so the radioactive noble gas passes through the vent system. It circulates and returns to the drywell many times. Therefore, the chances of leakage of radioactive rare gas from seals provided on the drywell side, such as the seals of the main flange of the drywell, increase. Therefore, further suppression of contamination and radiation exposure due to leakage of radioactive noble gases to the outside of the containment vessel (reactor building) is desired.

The present invention was made to solve the above problems, and its purpose is to enable the continuous release of steam and hydrogen gas in the reactor containment vessel to the external environment even in the event of loss of external power supply. It is also an object of the present invention to provide a reactor containment vessel vent system capable of reducing the leakage of radioactive noble gases to the external environment.

The present application includes a plurality of means for solving the above problems. One example is a reactor containment vessel vent system for discharging gas from a reactor containment vessel in which a dry well in which a reactor pressure vessel is arranged is formed. A wet well formed in the reactor containment vessel so as to be separated from the dry well and having therein a suppression pool storing pool water and a gas phase portion formed above the suppression pool , a vent pipe, one of which opens into the drywell and the other opens into the suppression pool, and a vent line that forms a flow path from the gas phase portion of the wetwell to the external environment outside the reactor containment vessel. and a rare gas filter installed on the vent line and having a characteristic that the volumetric flow rate of rare gas permeation under the same conditions is smaller than that of water vapor and hydrogen gas, and the rare gas on the vent line a return line forming a flow path connected to a portion upstream of the filter and the gas phase portion of the wet well, wherein the gas phase portion of the wet well is separated by a vertically extending partition wall; separated into a first space and a second space, the vent pipe opening in a region below the first space in the suppression pool, and the vent line extending into the first space of the wetwell and the return line is connected to the second space of the wet well.

According to the present invention, by installing the rare gas filter on the vent line, water vapor and hydrogen gas in the gas (vent gas) discharged from the reactor containment vessel can be released to the external environment, and radioactive rare gas It is possible to minimize the release of gas to the external environment through the vent line. Furthermore, by connecting the return line to the second space separated from the first space into which the gas in the dry well flows in the gas phase of the wet well, the radioactive rare gas collected by the rare gas filter The gas can be confined in the closed second space within the wetwell without external power supply. Therefore, even in the event of loss of the external power source, the steam and hydrogen gas in the reactor containment vessel can be continuously released to the external environment, and the leakage of radioactive noble gases to the external environment can be reduced.
Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS It is the figure which showed typically the structure of the reactor containment vessel vent system which concerns on the 1st Embodiment of this invention, and the structure of the reactor containment vessel which uses the said system. FIG. 2 is a diagram schematically showing the configuration of a containment vessel vent system according to a modification of the first embodiment of the present invention and the configuration of a containment vessel using the system; FIG. 3 is a diagram schematically showing the structure of a cooler that constitutes a part of the containment vessel venting system according to the modified example of the first embodiment of the present invention shown in FIG. 2; FIG. 2 is a diagram schematically showing the configuration of a containment vessel vent system according to a second embodiment of the present invention and the configuration of a containment vessel using the system; FIG. 3 is a diagram schematically showing the configuration of a containment vessel vent system according to a third embodiment of the present invention and the configuration of a containment vessel using the system;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a containment vessel vent system of the present invention will be described below with reference to the drawings. In addition, in each drawing, the same code|symbol is attached|subjected to the common component, and the overlapping description is abbreviate|omitted.

[First embodiment]
First, the structure of a reactor containment vessel using a reactor containment vessel vent system according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram schematically showing the configuration of a containment vessel vent system according to a first embodiment of the present invention and the configuration of a containment vessel using the system.

In FIG. 1, in a nuclear power plant, a reactor containment vessel 1 is installed in a reactor building (not shown). A reactor pressure vessel 3 containing a core 2 is housed in the reactor containment vessel 1 . A main steam pipe 4 is connected to the reactor pressure vessel 3 to send steam (hereinafter referred to as steam) generated in the reactor pressure vessel 3 to a turbine (not shown).

The reactor containment vessel 1 is intended to contain the radioactive materials inside to minimize the impact on the surrounding environment in the unlikely event that radioactive materials leak from the reactor pressure vessel 3. The reactor containment vessel 1 includes a containment vessel body 11 having an opening 11 a formed in the upper part thereof, and a dry well head 12 as an upper lid for closing the opening 11 a of the containment vessel body 11 . Drywell head 12 is detachably coupled to containment vessel body 11 via drywell main flange 13 . The drywell main flange 13 is provided with a sealing portion that seals leakage of the gas inside the reactor containment vessel 1 to the reactor building.

The interior of the containment vessel 1 is partitioned into a dry well 15 and a wet well 21 by a pedestal 5 and a diaphragm floor 6 . The pedestal 5 is a cylindrical structure rising from the bottom portion 11b of the containment vessel main body 11 and supports the reactor pressure vessel 3 . The diaphragm floor 6 is an annular structure extending radially outward from the upper end of the pedestal 5 and connected to the peripheral wall 11 c of the containment vessel body 11 . The dry well 15 includes an inner space portion surrounded by the pedestal 5 and a space portion above the diaphragm floor 6, and is a region in which the reactor pressure vessel 3 is arranged and various pipes pass. The wet well 21 is an annular portion formed on the outer peripheral side of the pedestal 5 and below the diaphragm floor 6 and positioned on the outer peripheral side of the reactor pressure vessel 3 . The wet well 21 has therein a suppression pool 22 (liquid phase portion) in which pool water for cooling is stored and a gas phase portion 23 formed above the suppression pool 22 .

The dry well 15 and wet well 21 communicate with each other through a vent pipe 27 . One side of the vent pipe 27 opens to the dry well 15 and the other side opens to the suppression pool 22 . The vent pipe 27 guides gas including steam released into the dry well 15 due to the occurrence of a loss of coolant accident (LOCA) or the like to the suppression pool 22 .

The reactor containment vessel 1 is provided with a decompression mechanism that reduces the pressure in the reactor pressure vessel 3 or the main steam pipe 4 when the pressure rises abnormally. The pressure reducing mechanism consists of a main steam relief safety valve 8 provided in the main steam pipe 4, and a main steam relief safety valve exhaust which is connected to the main steam relief safety valve 8 on one side and located in the suppression pool 22 (below the water surface of the pool) on the other side. It has a pipe 9 and a quencher 10 at the other end of the main steam safety relief valve exhaust pipe 9 . The main steam relief safety valve 8 releases part of the steam from the main steam pipe 4 by opening the valve. The main steam relief safety valve exhaust pipe 9 guides the steam flowing through the main steam pipe 4 through the main steam safety relief valve 8 into the suppression pool 22 . The quencher 10 diffuses the steam flowing through the main steam safety relief valve exhaust pipe 9 into the suppression pool 22 .

By the way, if a piping rupture accident occurs in which a gas such as steam or hydrogen gas flows out into the dry well 15 of the reactor containment vessel 1 due to damage to a part of the piping such as the main steam pipe 4, the dry well 15 The internal pressure rises due to the gas that has flowed out from the break in the pipe. The gas containing steam that has flowed out into the dry well 15 is guided into the suppression pool 22 inside the wet well 21 through the vent pipe 27 due to the pressure difference between the dry well 15 and the wet well 21 . Since the steam is condensed by the water in the suppression pool 22, the increase in pressure in the containment vessel 1 is suppressed accordingly.

Further, when the pressure in the reactor pressure vessel 3 or the main steam pipe 4 rises abnormally, the main steam safety relief valve 8 is opened to allow part of the steam flowing through the main steam pipe 4 to be released. It is discharged from the quencher 10 through the relief valve exhaust pipe 9 into the suppression pool 22 . As a result, most of the steam discharged from the main steam pipe 4 into the suppression pool 22 is condensed, and the pressure in the reactor pressure vessel 3 and the main steam pipe 4 is reduced accordingly. Therefore, it is possible to prevent damage to the reactor pressure vessel 3, piping such as the main steam pipe connected thereto, and equipment.

In this manner, in the event of a pipe rupture accident (for example, LOCA) or an abnormal rise in the pressure of the reactor pressure vessel 3, the suppression pool 22 condenses the steam. Furthermore, by cooling the suppression pool 22 with a residual heat removal system (not shown), an increase in pressure and temperature inside the reactor containment vessel 1 is prevented. That is, normally, the accident of the steam flowing out from the main steam pipe 4 or the like to the drywell 15 can be stopped.

However, in the unlikely event that the residual heat removal system loses its function, the temperature of the water in the suppression pool 22 will rise. As the temperature of the pool water rises, the partial pressure of the steam in the reactor containment vessel 1 rises to the saturation vapor pressure of the temperature of the pool water. That is, the pressure inside the reactor containment vessel 1 increases. When such a pressure increase occurs in the containment vessel 1, cooling water is sprayed into the containment vessel 1 by a spray cooling system (not shown). Thereby, the pressure rise in the reactor containment vessel 1 can be suppressed. The spray cooling system can also spray cooling water by connecting a fire pump or the like and activating it from the outside.

Furthermore, although it is very unlikely, it is necessary to assume that the spray cooling system also fails. In addition, when the water level of the pool rises to the height of the vacuum breaking valve due to water injection by spraying, water injection must be stopped. In these cases, the pressure increase in the reactor containment vessel 1 continues. If the pressure rise in the reactor containment vessel 1 continues, it is necessary to release the gas inside the reactor containment vessel 1 to the outside environment to reduce the pressure in the reactor containment vessel 1 . This operation for reducing the pressure in the containment vessel 1 is called a venting operation. A nuclear power plant is equipped with a reactor containment vessel vent system 20 that discharges gas (hereinafter referred to as vent gas) from the reactor containment vessel 1 to depressurize the reactor containment vessel 1 . The gas inside the containment vessel 1 contains various radioactive substances in addition to steam and hydrogen gas. Therefore, the containment vessel venting system 20 is configured to remove radioactive substances from the vent gas and then release the vent gas to the external environment.

The configuration of the containment vessel vent system according to the present embodiment will be described below with reference to FIG. In FIG. 1, the part surrounded by the dashed line shows the reactor containment vessel vent system.

In the venting operation in a boiling water reactor, the vent gas in the reactor containment vessel 1 is made to flow into the gas phase portion 23 through the suppression pool 22 of the wet well 21 and then released to the external environment. Vent gas in the reactor containment vessel 1 flows into the gas phase portion 23 of the dry well 15 by being discharged into the suppression pool 22 via the vent pipe 27 and the main steam safety valve relief valve exhaust pipe 9 . At this time, most of the radioactive substances contained in the vent gas are removed by the scrubbing effect of the pool water of the suppression pool 22 . However, the radioactive substances that could not be completely removed by scrubbing the pool water remain in the gas phase portion 23 of the dry well 15 together with the vent gas.

A reactor containment vessel vent system 20 (hereinafter referred to as a vent system) according to the present embodiment includes a wet well 21 in the reactor containment vessel 1, a vent pipe 27 for communicating the wet well 21 with a dry well 15, a wet well 21 A vent line 31 forming a flow path from the gas phase portion of the reactor to the external environment outside the containment vessel 1, and a first collection device 32 and a second collection device 33 provided on the vent line 31. . The vent line 31 is a flow path that guides the vent gas that has flowed into the gas phase portion of the wet well 21 to the external environment. The first collection device 32 and the second collection device 33 respectively collect various radioactive substances contained in the vent gas.

The wet well 21 is radially separated into a first space portion 24 and a second space portion 25 by a partition wall 26 extending vertically from the gas phase portion 23 . The first space portion 24 is located, for example, radially inward of the second space portion 25 . That is, the second space 25 is formed closer to the reactor building (not shown) than the first space 24 is. The partition wall 26 is, for example, a cylindrical structure suspended from the diaphragm floor 6 to a position in the suppression pool 22 that does not reach the bottom portion 11b of the containment vessel main body 11 . A quencher 10 is arranged in a region below the first space 24 in the suppression pool 22 (a region radially inside the suppression pool 22).

The vent pipe 27 includes a vertically extending pipe main body portion 28 embedded in the pedestal 5 positioned radially inside the wet well 21, and a pipe main body portion 28 branched and extending radially outward, It has a plurality of exhaust pipe portions 29 that open in a region below the first space portion 24 of the gas phase portion 23 in the suppression pool 22 . Since the pipe main body 28 and the first space 24 of the wet well 21 are positioned radially inside the wet well 21, the exhaust pipe 29 does not need to pass through the region below the second space 25. It is possible to set the length of the exhaust pipe portion 29 short. Therefore, there is no problem with the strength of the exhaust pipe portion 29 .

The first space 24 is a region (space) into which the gas released from the dry well 15 to the suppression pool 22 through the exhaust pipe 29 of the vent pipe 27 is introduced, and is a quencher from the main steam relief safety valve exhaust pipe 9 . It is configured to be a region (space) into which the gas released to the suppression pool 22 via 10 is introduced. On the other hand, the second space portion 25 is configured to be a closed space completely separated from the first space portion 24 into which the vent gas flows by the partition wall 26 .

The vent line 31 includes a first vent pipeline 41 that connects the first space 24 of the gas phase portion 23 of the wet well 21 and the first collection device 32, the first collection device 32, and the second collection device. 33 and a third vent line 43 connecting the second collection device 33 and the stack 34 . One end (upstream end) 41 a of the first vent pipe 41 passes through the partition wall 26 and opens into the first space 24 of the wet well 21 . An isolation valve 45 is installed on the first vent pipe 41 to be opened during the venting operation. The isolation valve 45 can be opened by a battery or high-pressure gas from a pressure source, and does not require an external power source.

The first collection device 32 is for collecting aerosol-like radioactive substances and gaseous radioactive substances containing radioactive iodine. Specifically, the first collection device 32 includes a filter vent container 51 that stores the scrubbing water 52, and a metal filter 53 and an iodine filter 54 that are installed in order from the upstream side on the second vent pipeline 42. ing. The scrubbing water 52 in the filter vent container 51 collects aerosol-like radioactive substances. The metal filter 53 is arranged in a gas phase portion formed above the scrubbing water 52 in the filter vent container 51 and connected to the upstream end of the second vent pipe 42 . The metal filter 53 collects aerosol-like radioactive substances that have not been completely collected by the scrubbing water 52 . The iodine filter 54 is arranged outside the filter vent container 51 and collects gaseous radioactive substances by chemical reaction and adsorption action in the filter. The filter vent container 51 , the metal filter 53 and the iodine filter 54 are covered with a shielding wall 55 . The shielding wall 55 is for reducing the influence of the radioactive substances accumulated in the scrubbing water 52, the metal filter 53, and the iodine filter 54 on the surrounding environment. The other end (downstream end) 41 b of the first vent pipe 41 passes through the shielding wall 55 and opens into the scrubbing water 52 in the filter vent container 51 . The second vent pipe 42 extends through the shielding wall 55 to the outside of the shielding wall 55 .

The second collection device 33 is configured to collect radioactive noble gases. Specifically, the second collection device 33 retains a rare gas filter 57 that allows steam and hydrogen gas to permeate, but has a characteristic that rare gases are difficult to permeate, and the gas that cannot permeate the rare gas filter 57. and an intermediate container 58 . A downstream end of the second vent pipe 42 is connected to the intermediate container 58 , and an upstream end of the third vent pipe 43 is connected to the rare gas filter 57 . That is, the intermediate container 58 is positioned immediately upstream of the rare gas filter 57 on the vent line 31 .

When the outlet side of the rare gas filter 57 is open to the atmosphere and a constant pressure is applied to the inlet side, the rare gas permeation amount (volume flow rate) is 1/10 or less of the permeation amount (volume flow rate) of steam and hydrogen. Define a filter such that As the rare gas filter 57, for example, a film is used that selectively allows steam and hydrogen gas, whose molecular diameter is relatively smaller than that of the radioactive rare gas, to pass therethrough. While the molecular diameter of steam and hydrogen gas is 0.3 nm or less, the molecular diameter of radioactive noble gases (krypton, xenon, etc.) is considerably larger than that of steam and hydrogen gas.

Films and other filter materials suitable for the above conditions include polymer films containing polyimide as a main component, ceramic films containing silicon nitride or carbon as a main component, and the like. These membranes are commonly known as filters for hydrogen purification. Membranes using polymer membranes are characterized by relatively high performance in separating rare gases from air and high permeation performance for vapor contained in the gas. A film using a ceramic film is characterized by having high strength and high heat resistance. The filter material of the rare gas filter 57 may be any film as long as it is a film that does not allow rare gases such as krypton and xenon to pass through but allows hydrogen and water (steam) molecules to pass through.

In the case of a boiling water reactor, the gas in the dry well 15 and wet well 21 inside the containment vessel 1 is replaced with nitrogen gas. Therefore, when the rare gas filter 57 is used to collect the radioactive rare gas, the rare gas filter 57 may not permeate nitrogen gas having a molecular diameter close to that of krypton or xenon. However, since the pressure rise in the reactor containment vessel 1 is caused by continuously generated steam and hydrogen gas, the pressure inside the reactor containment vessel 1 can be reduced even if the rare gas filter 57 does not allow nitrogen gas to permeate. It doesn't matter from

The vent system 20 further includes a return line 60 forming a flow path connected to a portion of the vent line 31 upstream of the rare gas filter 57 and the second space 25 of the wetwell 21 . The return line 60 guides the gas that has not passed through the rare gas filter 57 to the second space 25 .

Specifically, one end (upstream end) 61a of the return line 60 is connected to the intermediate container 58 (a portion of the vent line 31 immediately upstream of the rare gas filter 57), and the other A side end (downstream end) 61 b has a return line 61 that opens into the second space 25 of the wet well 21 . A delivery pump 62 and a check valve 63 are installed on the return line 61 in this order from the upstream side. The delivery pump 62 delivers the gas remaining in the intermediate container 58 to the second space 25 of the wetwell 21, and is driven by an external power source, for example. The check valve 63 allows the flow of gas from the intermediate container 58 to the second space 25 while blocking the flow of gas from the second space 25 to the intermediate container 58 .

Return line 60 also includes a bypass line 65 that bypasses delivery pump 62 on return line 61 . The bypass line 65 is connected to the upstream and downstream portions of the delivery pump 62 in the return line 61 . A relief valve 66 is installed on the bypass line 65 . The relief valve 66 opens when the fluid pressure on the primary side exceeds a first set pressure P1, and closes when it falls below a second set pressure P2 (where P2<P1). valve.

Next, the action and effect of the containment vessel vent system according to the first embodiment of the present invention will be described with reference to FIG. In FIG. 1, the white arrows indicate the direction of flow of the vent gas, and the circled numbers indicate the approximate types of gases that constitute the vent gas.

As described above, it is assumed that the reactor containment vessel 1 cannot be sufficiently cooled in a severe accident in which the core 2 melts. In this case, since steam and hydrogen gas continue to be generated, the pressure inside the reactor containment vessel 1 rises abnormally.

Here, the isolation valve 45 is opened as a venting operation. As a result, the gas containing high-temperature and high-pressure steam and hydrogen gas filling the dry well 15 of the containment vessel 1 is discharged to the suppression pool 22 through the vent pipe 27, and is discharged into the first space of the wet well 21. It is introduced into section 24 . At this time, most of the radioactive substances contained in the gas are removed by the scrubbing effect of the pool water of the suppression pool 22 . However, the radioactive substances that could not be completely removed by the scrubbing of the pool water flowed into the first space 24 of the wet well 21 together with the steam and hydrogen gas that could not be completely condensed.

The gas in the first space 24 of the wet well 21 is released as vent gas into the scrubbing water 52 in the filter vent container 51 via the first vent pipe line 41 and isolation valve 45 . The vent gas flowing through the first vent pipe 41 is mainly composed of steam, hydrogen gas, and nitrogen gas, but includes aerosol-like radioactive substances, radioactive iodine, and radioactive noble gases that could not be removed by scrubbing in the suppression pool 22. It contains gaseous radioactive substances such as The vent gas released into the scrubbing water 52 is scrubbed by the scrubbing water 52 to mainly remove most of the aerosol-like radioactive substances.

After passing through the scrubbing water 52 in the filter vent container 51, the vent gas passes through the metal filter 53 and the iodine filter 54 in order. The metal filter 53 collects aerosol-like radioactive substances that could not be removed by the scrubbing water 52 . The iodine filter 54 collects gaseous radioactive substances containing radioactive iodine. Therefore, the vent gas that has passed through the iodine filter 54 has gaseous radioactive substances including aerosol-like radioactive substances and radioactive iodine removed, but contains radioactive noble gases with poor reactivity.

The vent gas is then introduced to rare gas filter 57 via second vent line 42 and intermediate vessel 58 . In the rare gas filter 57, most of the radioactive rare gas that could not be removed by the first collection device 32 is collected without permeation, while the steam and hydrogen gas that cause the pressure increase in the containment vessel 1 passes through. Therefore, steam and hydrogen gas are discharged as vent gas from the exhaust tower 34 through the third vent pipe 43 to the external environment. As a result, the pressure in the reactor containment vessel 1 can be lowered while suppressing the release of the radioactive noble gas to the external environment as much as possible.

In addition to the radioactive rare gas, the rare gas filter 57 may not be able to sufficiently permeate nitrogen gas having a molecular diameter close to that of the radioactive rare gas. Gas that has not passed through the rare gas filter 57 stays in the intermediate container 58 . The gas containing the radioactive noble gas in the intermediate container 58 is forcibly delivered to the second space 25 of the wetwell 21 through the return line 61 by the delivery pump 62 . As a result, it is possible to prevent the vapor and hydrogen gas permeation performance of the rare gas filter 57 from deteriorating due to gas stagnation in the intermediate container 58 .

In the unlikely event that the delivery pump 62 does not operate, the gas that has not passed through the rare gas filter 57 stays in the intermediate container 58 , thereby gradually increasing the pressure in the intermediate container 58 . If the pressure in the intermediate container 58 rises too much, the permeation flow rate of steam and hydrogen gas through the rare gas filter 57 may decrease.

In contrast, in the present embodiment, the other end (downstream end) 61b of the return pipeline 61 opens into the second space 25 separated from the first space 24 in the wet well 21. ing. Since the high-temperature and high-pressure gas in the dry well 15 flows intensively only into the first space 24 of the wet well 21, the pool water in the region of the first space 24 in the suppression pool 22 of the wet well 21 is is positioned below the water surface of the pool water in the area of the second space 25 . That is, the pressure in the second space 25 is lower than that in the first space 24 by the difference in water head. When the pressure in the intermediate container 58 exceeds the first set pressure P1 of the relief valve 66, the relief valve 66 on the bypass line 65 opens. At this time, due to the pressure difference between the pressure in the intermediate container 58 and the pressure in the second space 25 of the wet well 21, the gas containing the radioactive rare gas staying in the intermediate container 58 uses the external power supply. 25 through the bypass line 65 and the return line 61 into the second space 25 of the wet well 21 . As a result, the partial pressure of the radioactive rare gas and nitrogen gas in the intermediate container 58 located immediately upstream of the rare gas filter 57 can be prevented from exceeding a predetermined value, and the vapor and hydrogen gas in the rare gas filter 57 can be prevented from exceeding a predetermined value. Permeability can be maintained.

As described above, in the present embodiment, even when the pump 62 driven by the external power source does not operate, the rare gas filter 57 continues to have the performance of allowing steam and hydrogen gas to pass through without allowing radioactive rare gas to pass through. can be maintained. In other words, in the event of a severe accident, the steam and hydrogen that cause the pressure increase in the reactor containment vessel 1 can be continuously released to the outside, and the reactor containment vessel 1 can be continuously decompressed.

By the way, from the viewpoint of workers' exposure to radiation and environmental pollution, it is desired to suppress leakage of radioactive noble gases into the reactor building (outside of the reactor containment vessel 1) as much as possible. Many of the gas leakage parts from the reactor containment vessel 1 to the reactor building are various sealing parts provided in the drywell 15 . For example, there is a seal on the drywell main flange 13 that couples the drywell head 12 to the containment body 11 .

When the return line is connected to the drywell as in the conventional containment vessel venting system (see Patent Document 1 mentioned above), the radioactive noble gas trapped in the rare gas filter is released into the drywell. returned. Therefore, there is a possibility that the radioactive noble gas returned into the drywell may leak to the outside of the containment vessel in no small amount through the seals provided in the drywell, such as the seals of the main flange of the drywell.

In contrast, in this embodiment, the return line 60 opens into the second space 25 of the wet well 21 . Therefore, the radioactive rare gas captured by the rare gas filter 57 is returned into the second space 25 of the wet well 21 . Therefore, the structure that partitions the wet well 21 has less leakage of gas from the reactor containment vessel 1 to the reactor building than the structure that partitions the dry well 15. leakage can be reduced compared to the prior art.

In addition, when the gas phase portion of the wetwell is not separated and the return line is connected to the drywell as in the conventional containment vessel vent system (see Patent Document 1 mentioned above), The radioactive rare gas captured by the rare gas filter is returned into the dry well and again flows into the wet well through the vent pipe. The radioactive rare gas that has flowed into the gas phase of the wetwell is introduced back into the rare gas filter through the vent line of the vent system. Since the rare gas filter is not completely impermeable to radioactive noble gases, a very small amount of radioactive noble gas is released to the outside environment through the rare gas filter. That is, each time the radioactive noble gas circulates through the vent system, there is an opportunity for leakage of the radioactive noble gas to the outside environment.

In contrast, in the present embodiment, the gas phase portion 23 of the wet well 21 is separated into the first space portion 24 to which the vent line 31 is connected and the second space portion 25 to which the return line 60 is connected. ing. That is, the gas phase portion 23 of the wet well 21 was collected by the first space portion 24 as a space for introducing the high pressure gas in the dry well 15 and letting it flow out to the vent line 31 and the rare gas filter 57. It is separated from the second space 25 of the wet well 21 as a space for confining the radioactive rare gas. Therefore, the radioactive rare gas collected by the rare gas filter 57 can be confined in the second space 25 which is a closed space without circulating the vent system 20 . Therefore, the radioactive rare gas collected by the rare gas filter 57 is not circulated through the vent system 20 and is not introduced into the rare gas filter 57 again. It is possible to minimize the chance of passing through the filter 57 and being discharged to the external environment, thereby improving safety.

In addition, in the present embodiment, among the plurality of radioactive substance collecting means on the vent line 31, the rare gas filter 57 is arranged at the most downstream position than the filter vent container 51, the metal filter 53, and the iodine filter 54. ing. This can prevent aerosol-like radioactive substances and radioactive iodine from adhering to the rare gas filter 57 . Therefore, it is possible to prevent the vapor and hydrogen gas permeability of the rare gas filter 57 from deteriorating due to adhesion of aerosol-like radioactive substances and radioactive iodine.

In addition, in the present embodiment, the temperature of the gas flowing into the rare gas filter 57 is lowered by arranging the rare gas filter 57 at the most downstream position. Therefore, the rare gas filter 57 is not exposed to high-temperature gas, and deterioration of the rare gas filter 57 due to high temperatures can be prevented. Therefore, the reliability of the vent system 20 can be improved. The radioactive rare gas can be collected regardless of the position of the rare gas filter 57 on the vent line 31 . However, as noted above, it is best to locate the rare gas filter 57 furthest downstream of the other collection means on the vent line 31 .

As described above, the containment vessel vent system 20 according to the first embodiment of the present invention discharges gas from the containment vessel 1 in which the dry well 15 in which the reactor pressure vessel 3 is arranged is formed. It is formed in the reactor containment vessel 1 so as to be separated from the dry well 15, and has a suppression pool 22 storing pool water and a gas phase portion 23 formed above the suppression pool 22. A wet well 21, a vent pipe 27 one of which opens to the dry well 15 and the other of which opens to the suppression pool 22, and a flow path from the gas phase portion 23 of the wet well 21 to the external environment outside the reactor containment vessel 1. and a rare gas filter 57 which is installed on the vent line 31 and has a characteristic that the volumetric flow rate of rare gas permeation under the same conditions is smaller than that of water vapor and hydrogen gas, and the vent line 31 upstream of the rare gas filter 57 and a return line 60 forming a flow path connected to the gas phase portion 23 of the wet well 21 . A gas phase portion 23 of the wet well 21 is separated into a first space portion 24 and a second space portion 25 by a vertically extending partition wall 26 , and a vent pipe 27 extends below the first space portion 24 in the suppression pool 22 . Open in area. The vent line 31 is connected to the first space 24 of the wetwell 21 and the return line 60 is connected to the second space 25 of the wetwell 21 .

According to this configuration, by installing the rare gas filter 57 on the vent line 31, water vapor and hydrogen gas in the gas (vent gas) discharged from the reactor containment vessel 1 can be released to the external environment. , the discharge of the radioactive noble gas to the external environment through the vent line 31 can be suppressed as much as possible. Furthermore, by connecting the return line 60 to the second space portion 25 separated from the first space portion 24 into which the gas in the dry well 15 flows in the gas phase portion 23 of the wet well 21, the rare gas filter The radioactive noble gas collected at 57 can be confined in the closed second space 25 within the wet well 21 without supplying an external power source. Therefore, even in the event of loss of the external power supply, the steam and hydrogen gas in the reactor containment vessel 1 can be continuously released to the external environment, and the leakage of radioactive noble gases to the external environment can be reduced. .

Further, in the present embodiment, the first space 24 and the second space 25 of the gas phase portion 23 of the wet well 21 are separated in the radial direction, and the first space 24 is separated from the second space 25. are also located radially inward. According to this configuration, by newly installing the partition wall 26 in the wet well of the existing reactor containment vessel, the vent system 20 according to the present embodiment can be easily installed in the existing reactor containment vessel. can be applied.

In addition, in the present embodiment, the vent pipe 27 has a pipe main body portion 28 that extends in the vertical direction at a radially inner position of the wet well 21 and a pipe main body portion 28 that branches off from the pipe main body portion 28 and extends radially outward. and an exhaust pipe portion 29 that opens in a region below the first space portion 24 in the suppression pool 22 . According to this configuration, when applying the vent system 20 according to the present embodiment to an existing reactor containment vessel, the vent pipe used in the existing reactor containment vessel can be used as it is.

Further, the containment vessel vent system 20 according to the present embodiment is installed on the upstream side of the rare gas filter 57 on the vent line 31 and is capable of holding the gas that has not passed through the rare gas filter 57 ( container) 58. According to this configuration, the gas collected by the rare gas filter 57 temporarily stays in the intermediate container 58, which has a larger volume than the pipeline. Therefore, it does not rise immediately, and deterioration of the vapor and hydrogen gas permeation performance of the rare gas filter 57 can be prevented.

Further, in the present embodiment, the rare gas filter 57 is configured so that the volumetric flow rate of rare gas permeation is one tenth or less of the volumetric flow rate of water vapor and hydrogen gas permeation. According to this configuration, the rare gas filter 57 can be realized by using existing membranes.

Moreover, in the present embodiment, the rare gas filter 57 is formed of either one of a ceramic film and a polymer film. According to this configuration, a generally available film can be used as the rare gas filter 57 .

Moreover, in the present embodiment, the rare gas filter 57 is formed of a ceramic film containing silicon nitride as a main component. According to this configuration, the rare gas filter 57 has high strength and high heat resistance.

Moreover, in the present embodiment, the rare gas filter 57 is formed of a ceramic film containing carbon as a main component. According to this configuration, the rare gas filter 57 has high strength and high heat resistance.

Further, in this embodiment, the rare gas filter 57 is formed of a polymer film containing polyimide as a main component. According to this configuration, the rare gas filter 57 can achieve both high rare gas separation performance and high water vapor permeation performance.

[Modification of First Embodiment]
Next, a reactor containment vessel vent system according to a modification of the first embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG. FIG. 2 is a diagram schematically showing the configuration of a containment vessel vent system according to a modification of the first embodiment of the present invention and the configuration of a containment vessel using the system. FIG. 3 is a diagram schematically showing the structure of a cooler forming part of the containment vessel venting system according to the modification of the first embodiment of the present invention shown in FIG.

A reactor containment vessel venting system 20A according to a modification of the first embodiment of the present invention shown in FIG. This is due to the addition of a cooler 35 upstream of the rare gas filter 57). Other configurations of the modified example of the first embodiment are the same as those of the first embodiment.

In the vent system 20 (see FIG. 1) according to the first embodiment, depending on the type of the rare gas filter 57, the temperature of the vent gas flowing into the intermediate container 58 exceeds the heat resistance condition, resulting in a reduced filter life. There is Therefore, in this modification, the cooler 35 is installed between the iodine filter 54 and the intermediate container 58 on the second vent pipe 42 and outside the shielding wall 55 . By cooling the vent gas that has passed through the iodine filter 54 by the cooler 35, the vapor in the vent gas is condensed, so that the temperature of the vent gas flowing into the intermediate container 58 is lowered so as to satisfy the heat resistance condition of the rare gas filter 57. be able to.

Cooler 35 uses, for example, natural convection of air or water to cool the vent gas, and is a passive component that operates without external power such as an AC power supply. Specifically, as shown in FIG. 3, the cooler 35 separates a part 42a of the second vent pipe 42 extending in the vertical direction from the outer peripheral side of the part 42a of the second vent pipe 42. It is composed of a cylindrical cover 59 that is opened and surrounded. An annular cooling passage P through which air can flow is formed between the portion 42 a of the second vent pipe 42 and the cover 59 . Note that the second vent pipe line 42 and the cooler 35 are arranged at a position higher than the filter vent container 51 .

Next, the action and effect of the cooler in the vent system according to this modified example will be described with reference to FIGS. 2 and 3. FIG. In FIG. 2, the white arrows indicate the direction of flow of the vent gas, and the circled numbers indicate the approximate types of gases that constitute the vent gas. In FIG. 3, thick arrows indicate the direction of flow of vent gas, and white arrows indicate the direction of flow of cooling air.

As shown in FIG. 2, the hot steam-containing vent gas that has passed through the iodine filter 54 flows through the second vent line 42 . At this time, as shown in FIG. 3, the outside air C having a lower temperature than the vent gas flows into the cooling passage P, which is the gap between the part 42a of the second vent pipe 42 and the cover 59. As shown in FIG. Since the outside air C in the cooling passage P is warmed by the heat of the vent gas flowing through the second vent pipe 42, an upward air current is generated in the outside air C due to the chimney effect. Therefore, outside air C is newly taken into the cooling flow path P from below the cover 59 . By setting the length of the cover 59 longer, a greater chimney effect can be obtained.

The vent gas containing steam flowing through the portion 42 a of the second vent pipe 42 is cooled by the upward air flow C flowing through the cooling passage P. As shown in FIG. At this time, when the temperature of the vent gas drops below the dew point of the steam, the steam contained in the vent gas condenses. The condensed water W produced by condensation of the steam flows down the upstream side (downward side) of the second vent pipe 42 by its own weight, is returned to the filter vent container 51 shown in FIG. stored.

Thus, in this modification, since the steam in the vent gas is condensed by the cooler 35, the vent gas that has passed through the cooler 35 mainly consists of non-condensable gases such as hydrogen gas, nitrogen gas, and radioactive rare gas. is occupied by Therefore, non-condensable gas flows into the intermediate vessel 58 as vent gas.

In addition, in this modification, the condensed water generated by cooling the vent gas using the cooler 35 is allowed to flow down to the filter vent container 51 by its own weight and is stored as the scrubbing water 52 . Therefore, the effect of suppressing the reduction of the scrubbing water 52 in the filter vent container 51 can be expected.

As described above, according to the reactor containment vessel venting system 20A according to the modification of the first embodiment of the present invention, the rare gas filter 57 on the vent line 31 Of the gas (vent gas) discharged from the reactor containment vessel 1, water vapor and hydrogen gas can be released to the external environment, and the release of radioactive noble gases to the external environment via the vent line 31 is suppressed as much as possible. be able to. Furthermore, by connecting the return line 60 to the second space portion 25 separated from the first space portion 24 into which the gas in the dry well 15 flows in the gas phase portion 23 of the wet well 21, the rare gas filter The radioactive noble gas collected at 57 can be confined in the closed second space 25 of the wetwell 21 without supplying an external power source. Therefore, even if the external power supply is lost, the steam and hydrogen gas in the reactor containment vessel 1 can be continuously released to the external environment, and the leakage of radioactive noble gases to the external environment can be reduced.

Further, the containment vessel vent system 20A according to this modified example further includes a cooler 35 that is installed upstream of the rare gas filter 57 on the vent line 31 and that cools the gas flowing through the vent line 31 . According to this configuration, since the gas (vent gas) introduced into the rare gas filter 57 is cooled by the cooler 35, it is possible to prevent deterioration of the permeation performance of the rare gas filter 57 due to high-temperature vent gas.

[Second embodiment]
Next, the configuration of a containment vessel vent system according to a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram schematically showing the configuration of a containment vessel vent system according to a second embodiment of the present invention and the configuration of a containment vessel using this system. In FIG. 4, the white arrows indicate the direction of flow of the vent gas, and the circled numbers indicate the approximate types of gases that constitute the vent gas.

A vent system 20B according to a second embodiment of the present invention shown in FIG. 25B is reversed in radial position, and the exhaust pipe portion 29B of the vent pipe 27B is different. Other configurations of the second embodiment are similar to those of the first embodiment.

Specifically, the first space 24B of the wet well 21B to which the vent line 31 is connected is located radially outside the second space 25B to which the return line 60 is connected. That is, the second space 25B is formed at a position farther from the reactor building than the first space 24B. A downstream end portion 61b of the return conduit 61 of the return line 60 penetrates the partition wall 26 and opens to the second space portion 25B. The vent pipe 27B is embedded in the pedestal 5 located radially inward of the wet well 21B and extends in the vertical direction. and an exhaust pipe portion 29B that passes through a region below the first space portion 24B and extends to a region below the first space portion 24B. A quencher 10 is arranged in a region below the first space 24B in the suppression pool 22 (a region radially outside the suppression pool 22). The first space 24B receives the high-pressure gas released from the dry well 15 to the suppression pool 22 through the exhaust pipe 29B of the vent pipe 27B, and the main steam relief safety valve exhaust pipe 9 through the quencher 10. It is configured to be a region into which high-pressure gas released to the suppression pool 22 is introduced. On the other hand, the second space portion 25B is configured to be a closed space completely separated from the first space portion 24B by the partition wall 26 .

In the vent system 20 (see FIG. 1) according to the first embodiment, the first space 24 of the wetwell 21 to which the vent line 31 is connected is larger than the second space 25 to which the return line 60 is connected. located radially inward. That is, the second space 25 is formed closer to the reactor building than the first space 24 is. The gas containing the radioactive rare gas collected by the rare gas filter 57 is returned to the second space 25 of the wet well 21 via the return line 60 . However, the radioactive noble gas confined in the second space 25 located radially outside the wet well 21 is atomized through the seal provided in the outer peripheral structure (peripheral wall 11c) that defines the wet well 21. There is a risk of leakage to the furnace building side.

In contrast, in the present embodiment, the second space 25B is formed radially inward at a position farther from the reactor building than the first space 24B. Therefore, the radioactive rare gas collected by the rare gas filter 57 and returned to the second space 25B of the wet well 21B does not leak to the reactor building located on the outer peripheral side of the wet well 21B.

According to the reactor containment vessel vent system 20B according to the second embodiment of the present invention described above, as in the first embodiment, the rare gas filter 57 on the vent line 31 allows the reactor containment vessel 1 Of the gas (vent gas) discharged from the vent line 31, water vapor and hydrogen gas can be discharged to the external environment, and the discharge of radioactive rare gas to the external environment via the vent line 31 can be suppressed as much as possible. Furthermore, by connecting the return line 60 to the second space portion 25B separated from the first space portion 24B into which the gas in the dry well 15 flows in the gas phase portion 23 of the wet well 21B, the rare gas filter The radioactive noble gas collected at 57 can be confined in the closed second space 25B of the wet well 21B without supplying an external power source. Therefore, even if the external power supply is lost, the steam and hydrogen gas in the reactor containment vessel 1 can be continuously released to the external environment, and the leakage of radioactive noble gases to the external environment can be reduced.

Further, in the reactor containment vessel vent system 20B according to the present embodiment, the first space 24B and the second space 25B of the wet well 21B are separated in the radial direction, and the first space 24B is the second space. It is located radially outside of the space 25B. According to this configuration, the radioactive rare gas collected by the rare gas filter 57 and returned to the second space 25B of the wet well 21B is atomized through the seal provided in the structure that partitions the wet well 21B. There is no leakage to the outside of the reactor containment vessel 1.

Further, in the reactor containment vessel vent system 20B according to the present embodiment, the vent pipe 27B includes a pipe body portion 28 extending vertically at a radially inner position of the wet well 21B, and It has an exhaust pipe portion 29B that branches, passes through a region below the second space portion 25B in the suppression pool 22, extends to a region below the first space portion 24B, and opens.

According to this configuration, it is possible to apply the present embodiment to an existing nuclear power plant by modifying the exhaust pipe portion of the vent pipe used in the existing reactor containment vessel. . Therefore, it is easy to modify the existing reactor containment vessel.

[Third Embodiment]
Next, a containment vessel vent system according to a third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram schematically showing the configuration of a containment vessel vent system according to a third embodiment of the present invention and the configuration of a containment vessel using this system. In FIG. 5, the white arrows indicate the direction of flow of the vent gas, and the circled numbers indicate the approximate types of gases that constitute the vent gas.

A vent system 20C according to the third embodiment of the present invention shown in FIG. 25C is reversed in radial position, and the arrangement of the vent pipe 27C is different. Other configurations of the third embodiment are similar to those of the first embodiment.

Specifically, the first space 24C of the wet well 21C to which the vent line 31 is connected is located radially outside the second space 25C to which the return line 60 is connected. That is, the second space 25C is formed at a position farther from the reactor building than the first space 24C. A downstream end 61b of the return conduit 61 of the return line 60 passes through the partition wall 26 and opens to the second space 25C. The vent pipe 27C is embedded in the peripheral wall 11c of the reactor containment vessel 1 located radially outside the wet well 21C, and includes a pipe main body portion 28C extending in the vertical direction and a radially inner side branching from the pipe main body portion 28C. and an exhaust pipe portion 29</b>C that extends into the suppression pool 22 and opens in a region below the first space portion 24</b>C in the suppression pool 22 . A quencher 10 is arranged in a region below the first space 24C in the suppression pool 22 (a region radially outside the suppression pool 22). The first space 24C receives the high-pressure gas released from the drywell 15 to the suppression pool 22 through the exhaust pipe 29C of the vent pipe 27C, and the main steam relief safety valve exhaust pipe 9 through the quencher 10. It is configured to be the region of the gas phase portion 23 into which the gas released to the suppression pool 22 is introduced. On the other hand, the second space portion 25C is configured to be a closed space completely separated from the first space portion 24C by the partition wall 26 .

In the present embodiment, the second space 25C is formed radially inward at a position farther from the reactor building than the first space 24C. Therefore, the radioactive rare gas collected by the rare gas filter 57 and returned to the second space 25C of the wet well 21C does not leak to the reactor building located on the outer peripheral side of the wet well 21C.

According to the reactor containment vessel vent system 20C according to the third embodiment of the present invention described above, as in the first embodiment, the rare gas filter 57 on the vent line 31 allows the reactor containment vessel 1 Of the gas (vent gas) discharged from the vent line 31, water vapor and hydrogen gas can be discharged to the external environment, and the discharge of radioactive rare gas to the external environment via the vent line 31 can be suppressed as much as possible. Furthermore, by connecting the return line 60 to the second space portion 25C separated from the first space portion 24C into which the gas in the dry well 15 flows in the gas phase portion 23 of the wet well 21C, the rare gas filter The radioactive noble gas collected at 57 can be confined in the closed second space 25C of the wet well 21C without supplying an external power source. Therefore, even if the external power supply is lost, the steam and hydrogen gas in the reactor containment vessel 1 can be continuously released to the external environment, and the leakage of radioactive noble gases to the external environment can be reduced.

Further, in the reactor containment vessel vent system 20C according to the present embodiment,
The first space portion 24C and the second space portion 25C of the wet well 21C are separated in the radial direction, and the first space portion 24C is located radially outside the second space portion 25C. According to this configuration, the radioactive rare gas collected by the rare gas filter 57 and returned to the second space 25C of the wet well 21C is atomized through the seal provided in the structure that partitions the wet well 21C. There is no leakage to the outside of the reactor containment vessel 1.

Further, in the reactor containment vessel vent system 20C according to the present embodiment, the vent pipe 27C includes a pipe body portion 28C extending vertically at a position radially outside the wet well 21C, and a pipe body portion 28C extending from the pipe body portion 28C. An exhaust pipe portion 29</b>C branches and extends radially inward and opens in a region below the first space portion 24</b>C in the suppression pool 22 . According to this configuration, the exhaust pipe portion 29C of the vent pipe 27C can be opened in the area below the first space 24C in the suppression pool 22 without increasing the length of the exhaust pipe portion 29C. Therefore, there is no problem of strength due to the length of the exhaust pipe portion 29C.

[Other embodiments]
The present invention is not limited to the above-described first to third embodiments and modifications thereof, and includes various modifications. The above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the described configurations. For example, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

For example, in the above-described first to third embodiments and modifications of the containment vessel vent system of the present invention, an example of application to an advanced boiling water reactor (ABWR) was shown. However, the reactor containment vessel vent system of the present invention can be applied to a boiling water reactor (BWR) having wet wells 21, 21B, and 21C including a suppression pool 22 and a gas phase portion 23. be. For example, in the present embodiment and its modification, an example of a configuration in which the containment vessel 1 is partitioned into the dry well 15 and the wet wells 21, 21B, and 21C by the pedestal 5 and the diaphragm floor 6 is shown. However, it is also possible to partition the drywell and the wetwell by a structure different from the pedestal 5 and diaphragm floor 6 .

In addition, in the above-described first to third embodiments of the containment vessel vent system of the present invention and their modifications, the partition wall 26 is moved from the diaphragm floor 6 to the bottom portion 11b of the containment vessel main body 11 in the suppression pool 22. An example of a cylindrical structure that hangs down to a position where it does not reach is shown. However, the partition wall may be a cylindrical structure extending from the diaphragm floor 6 to the bottom portion 11b of the containment vessel body 11, and may have a through hole through which the pool water of the suppression pool 22 can pass.

Further, the cooler 35 constituting a part of the containment vessel vent system according to the modified example of the first embodiment of the present invention is replaced with the containment vessel vent system according to the second and third embodiments. It can also be applied to systems.

Further, in the modified example of the first embodiment of the reactor containment vessel venting system of the present invention described above, an example of the configuration using the natural convection of outside air for cooling the second vent pipe line 42 was shown. However, a configuration using natural convection of cooling water is also possible for cooling the second vent pipe line 42 . In this case, a container containing cooling water is installed at a position higher than the cooler 35, and the difference in water head between the container and the cooler is used to cool the gap between the portion 42a of the second vent pipe 42 and the flow channel cover 59. The vent gas flowing through the second vent pipe 42 can be cooled by flowing cooling water into the cooling passage P formed in .

DESCRIPTION OF SYMBOLS 1... Reactor containment vessel 3... Reactor pressure vessel 15... Dry well 20, 20A, 20B, 20C... Reactor containment vessel vent system 21, 21B, 21C... Wet well 22... Suppression pool 23... gas phase portion 24, 24B, 24C first space portion 25, 25B, 25C second space portion 26 partition wall 27, 27B, 27C vent pipe 28, 28C pipe body portion 29, 29B, 29C... Exhaust pipe section 31... Vent line 35... Cooler 57... Rare gas filter 58... Intermediate container (container) 60... Return line

Claims (13)

A reactor containment vessel vent system for discharging gas from a reactor containment vessel in which a dry well for arranging a reactor pressure vessel is formed,
a wet well formed in the reactor containment vessel so as to be separated from the dry well and having therein a suppression pool storing pool water and a gas phase portion formed above the suppression pool;
a vent pipe, one of which opens into the drywell and the other of which opens into the suppression pool;
a vent line forming a flow path from the gas phase portion of the wet well to an external environment outside the reactor containment vessel;
a rare gas filter installed on the vent line and having a characteristic that the volumetric flow rate of rare gas permeation is lower than that of water vapor and hydrogen gas under the same conditions;
a return line forming a flow path connected to a portion upstream of the rare gas filter on the vent line and the gas phase portion of the wet well;
The gas phase portion of the wet well is separated into a first space portion and a second space portion by a vertically extending partition wall,
The vent pipe opens in a region below the first space within the suppression pool,
The vent line is connected to the first space of the wet well,
The reactor containment vessel vent system, wherein the return line is connected to the second space of the wet well. In the reactor containment vessel vent system according to claim 1,
The first space portion and the second space portion are separated in a radial direction,
The reactor containment vessel vent system, wherein the first space is located radially inward of the second space. In the reactor containment vessel vent system according to claim 2,
The vent pipe is
a pipe body extending vertically at a radially inner position of the wet well;
and an exhaust pipe branching from the pipe main body and extending radially outward and opening in a region below the first space in the suppression pool. . In the reactor containment vessel vent system according to claim 1,
The first space portion and the second space portion are separated in a radial direction,
The reactor containment vessel vent system, wherein the first space is located radially outside the second space. In the containment vessel vent system according to claim 4,
The vent pipe is
a pipe body extending vertically at a radially inner position of the wet well;
an exhaust pipe branching from the pipe main body, passing through a region below the second space in the suppression pool, extending to a region below the first space, and opening. A reactor containment vent system characterized by: In the containment vessel vent system according to claim 4,
The vent pipe is
a pipe body extending vertically at a position radially outside the wet well;
and an exhaust pipe branching from the pipe main body and extending radially inward and opening in a region below the first space in the suppression pool. . In the reactor containment vessel vent system according to claim 1,
A reactor containment vessel vent system, further comprising: a cooler installed upstream of the rare gas filter on the vent line and cooling gas flowing through the vent line. In the reactor containment vessel vent system according to claim 1,
A reactor containment vessel vent system, further comprising a container installed on the vent line upstream of the rare gas filter and capable of holding gas that has not passed through the rare gas filter. In the reactor containment vessel vent system according to claim 1,
The reactor containment vessel, wherein the rare gas filter is configured such that the volumetric flow rate of rare gas permeation is one tenth or less of the volumetric flow rate of water vapor and hydrogen gas permeation. vent system. In the containment vessel vent system according to claim 9,
A reactor containment vessel vent system, wherein the rare gas filter is formed of one of a ceramic film and a polymer film. In the containment vessel vent system according to claim 10,
A reactor containment vessel vent system, wherein the rare gas filter is formed of a ceramic film containing silicon nitride as a main component. In the containment vessel vent system according to claim 10,
A reactor containment vessel vent system, wherein the rare gas filter is formed of a ceramic film containing carbon as a main component. In the containment vessel vent system according to claim 10,
A reactor containment vessel vent system, wherein the rare gas filter is formed of a polymer film containing polyimide as a main component.

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