JP6754719B2 - Reactor containment vent system - Google Patents

Description

The present invention relates to a reactor containment vent system.

One of the functions of the reactor containment vessel of a nuclear power plant is that radioactive materials are released in the event that the core inside the reactor pressure vessel melts (hereinafter referred to as "severe accident"). Even if it is released outside the reactor pressure vessel, it has the function of trapping radioactive materials. By providing such a function, the reactor containment vessel can prevent radioactive materials from leaking to the outside in the event of a severe accident. Even if a severe accident occurs, the accident will be resolved if sufficient water injection is performed after that and the reactor containment vessel is cooled.

However, in the unlikely event that steam continues to be generated and the reactor containment vessel is insufficiently cooled, the reactor containment vessel may be pressurized. When the reactor containment vessel is pressurized, it is necessary to release the gas in the reactor containment vessel into the atmosphere and depressurize the reactor containment vessel. This operation for depressurization is called a vent operation. When performing this venting operation, radioactive materials are removed from the pool water of the suppression pool (hereinafter referred to as "scrubbing") and then contained in the reactor so that the exposure to the public is minimized in boiling water reactors. The gas in the vessel (hereinafter referred to as "vent gas") is released into the atmosphere.

In boiling water reactors, as mentioned above, radioactive substances are sufficiently removed from the pool water in the suppression pool, and then the bent gas is released into the atmosphere. Filter vent is a system that further removes radioactive substances from this bent gas. There is a system. For example, Patent Document 1 describes a radioactive substance removal filter device for removing radioactive substances from a bent gas as an example of a filter vent system.
The radioactive substance removal filter device described in Patent Document 1 includes a tank containing water, a pipe for guiding bent gas into the water of the tank, and a metal filter or an iodine filter at an outlet for discharging bent gas from the tank.

The bent gas for removing radioactive substances from the bent gas is scrubbed by being released into the water in the tank, and the aerosol is removed. After that, the aerosol that could not be completely removed by scrubbing with the metal filter is removed with the iodine filter. In the iodine filter, volatile fission products such as iodine (hereinafter referred to as "volatile FP") that could not be completely removed by scrubbing are removed by chemical reaction and adsorption. Further, Patent Document 2 proposes to provide a hold-up device in the wake of a general filter vent system in order to prevent the release of a radioactive rare gas having poor reactivity to the outside. In the hold-up device, a radioactive rare gas having low reactivity such as xenon and krypton is contained from the bent gas until the radioactivity is attenuated.

Japanese Unexamined Patent Publication No. 2014-44118 Special Table 2016-521843

In a filter vent system for the purpose of preventing the release of radioactive rare gas to the outside, it is necessary to provide a hold-up device as described above. The hold-up device holds the radioactive rare gas for a certain period of time until the radioactivity decays, but in order to hold the rare gas contained in such bent gas until the radioactivity is sufficiently attenuated, a large hold is used. It is necessary to install multiple up devices.
Further, when a hold-up device is installed, a large number of accompanying devices such as boilers and pipes for removing substances accumulated in the hold-up device are required, which causes a problem of complicated configuration.

Here, instead of the filter vent system, it is also proposed to install a filter that does not permeate almost all radioactive substances including radioactive rare gas on the line that discharges the vent gas from the reactor containment vessel (hereinafter referred to as the vent line). ing. If a reactor containment vent system equipped with a filter that does not allow all such radioactive materials to permeate is used, the vapor that causes pressurization of the reactor containment vessel can be released without releasing the radioactive materials to the outside as much as possible. Can be done.

However, when the filter is installed outside the reactor containment vessel, for example, at the downstream part of the vent line, gas that cannot pass through the filter stays in the immediate upstream part of the filter over time. Resulting in. As the partial pressure of these gases increases, the amount of vapor permeation may decrease, and the function of reducing the pressure in the reactor containment vessel may decrease.

In order to prevent such retention of gas, it is necessary to return the retained gas to the reactor containment vessel or to isolate it in a large-capacity vessel capable of storing all the retained gas. Furthermore, since the reactor containment vent system needs to operate in the event of a severe accident, it is desirable that it be passively activated without operator operation and operate without dynamic equipment that requires power.

On the other hand, if a filter is installed at the end of the vent line in the reactor containment vessel, which is the most upstream part of the vent line, a return pipe for returning gas, dynamic equipment such as a pump that requires a driving fluid or a power source, and There is no need for a large-capacity container to isolate the stagnant gas. However, in the event of an accident, water droplets generated by the ripples of the pool water in the suppression pool and the injection of water into the reactor containment vessel will be scattered inside the reactor containment vessel.
In the unlikely event of a severe accident, volatile FP may flow into the reactor containment vessel. Further, the inflowing volatile FP becomes supersaturated, which may generate an aerosol in the reactor containment vessel.

Here, when the filter is installed in the reactor containment vessel, it is necessary to protect the filter because the performance of the filter deteriorates due to the adhesion of these to the filter. Further, when only the filter is simply installed in the reactor containment vessel, even if the filter can permeate the vapor, the gas that does not permeate stays in the immediate upstream portion of the filter, although it is extremely low. In that case, the permeation performance of the steam cannot be maintained, and the steam in the reactor containment vessel cannot be continuously discharged to the outside of the system, so that the pressure in the reactor containment vessel may not be continuously reduced.

The present invention can be passively activated without operator intervention, and can continuously release steam from the reactor containment vessel to the outside of the system without the need for a large capacity vessel for isolation, and pressure. It is an object of the present invention to provide a reactor containment vessel vent system having a structure capable of continuously depressurizing.

In order to solve the above problems, for example, the configuration described in the claims is adopted.
The present application includes a plurality of means for solving the above problems. For example, a vent line that depressurizes the containment vessel by discharging the gas inside the containment vessel to the outside and a radioactive one. A filter placed at the end of the vent line on the containment vessel side that suppresses the permeation of substances and allows vapor to permeate, a protective container that surrounds the end of the vent line inside the containment vessel and the filter, and atoms. An on-off valve for bypassing the vent line installed in the protective container and a protective container for opening at an operating pressure below the limit pressure of the containment vessel, closing at a pressure below the operating pressure, and discharging gas to the outside without passing through a filter. It is equipped with a start valve that opens at an operating pressure equal to or lower than the operating pressure of the bypass on-off valve.

According to the present invention, even when a gas containing radioactive substances flows out from the reactor pressure vessel into the reactor containment vessel and the reactor containment vessel is pressurized, the radioactive substances containing radioactive rare gas can be produced. It can be kept in the containment vessel as much as possible. Then, it can be started without using dynamic equipment, and radioactive materials can be kept in the reactor containment vessel as much as possible without using a large-capacity vessel. Therefore, it is possible to prevent the pressurization of the reactor containment vessel and prevent the leakage of radioactive materials to the outside.
Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

It is a block diagram which shows the whole of the reactor containment vessel and the reactor containment vessel vent system which concerns on 1st Embodiment of this invention. It is a block diagram of the radioactive material filtering system provided in the reactor containment vessel vent system which concerns on 1st Embodiment of this invention. It is a block diagram which shows the whole of the reactor containment vessel and the reactor containment vessel vent system which concerns on the 2nd Embodiment of this invention. It is a block diagram of the radioactive material filtering system provided in the reactor containment vessel vent system which concerns on 2nd Embodiment of this invention. It is a block diagram of the radioactive material filtering system (an example which separated the bypass flow path) provided in the reactor containment vessel vent system which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the whole of the reactor containment vessel and the reactor containment vessel vent system which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the whole of the reactor containment vessel and the reactor containment vessel vent system which concerns on 4th Embodiment of this invention. It is a block diagram which shows the whole of the reactor containment vessel and the reactor containment vessel vent system which concerns on 5th Embodiment of this invention.

[1. Example of the first embodiment]
Hereinafter, an example of the first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a schematic configuration of the reactor containment vessel 1 and the reactor containment vessel vent system 40 of the first embodiment. In FIG. 1, the reactor containment vessel 1 is shown as a vertical cross section.
The first embodiment is applied to an improved boiling water reactor.

As shown in FIG. 1, a reactor pressure vessel 3 containing a core 2 is installed inside the reactor containment vessel 1. A main steam pipe 4 for sending steam generated in the reactor pressure vessel 3 to a turbine (not shown) is connected to the reactor pressure vessel 3.
The inside of the reactor containment vessel 1 is divided into a dry well 6 and a wet well 7 by a diaphragm floor 5 made of reinforced concrete. The wet well 7 is an area in which pool water is stored. The pool in the wet well 7 is called a suppression pool 8. The dry well 6 and the wet well 7 are communicated with each other by a vent pipe 9. The vent pipe exhaust portion 9a is open below the water surface of the suppression pool 8 in the wet well 7. In the unlikely event that a part of the pipes is damaged and a pipe breakage accident occurs in which steam is released into the reactor containment vessel 1, the pressure of the dry well 6 rises due to the steam flowing out from the break port. Such a pipe breakage accident is generally called LOCA (loss-of-coolant accident) and occurs in the dry well 6 through which the pipe passes.

The steam released into the dry well 6 when LOCA is generated is guided into the water of the suppression pool 8 in the wet well 7 through the vent pipe 9 by the pressure difference between the dry well 6 and the wet well 7. The pressure rise in the reactor containment vessel 1 is suppressed by condensing the steam with the water in the suppression pool 8. If radioactive substances are contained in the steam at this time, most of the radioactive substances are removed by the scrubbing effect of the water in the suppression pool 8.

Similarly, when the pressure of the reactor pressure vessel 3 and the main steam pipe 4 becomes high, steam is released to the suppression pool 8 to reduce the pressure of the reactor pressure vessel 3 and the main steam pipe 4. Further, the pressure rise of the reactor containment vessel 1 is alleviated by condensing the released steam in the suppression pool 8. In order to perform such a process, in the improved boiling water reactor, a steam escape safety valve 10 is installed in the region of the dry well 6 in the reactor containment vessel 1. The steam released through the steam escape safety valve 10 is finally released from the quencher 12 into the suppression pool 8 through the steam escape safety valve exhaust pipe 11, and is condensed by the pool water of the suppression pool 8. By condensing the steam in the suppression pool 8 into liquid water, the volume of the steam can be significantly reduced and the pressure increase in the reactor containment vessel 1 can be suppressed. If the steam contains radioactive substances at that time, most of the radioactive substances are removed by the scrubbing effect of the water in the suppression pool 8.

By condensing steam in the suppression pool 8 and cooling the pool water in the suppression pool 8 with a residual heat removal system (not shown), the temperature rise and pressure rise of the reactor containment vessel 1 are prevented, and the accident is resolved. be able to. However, although very unlikely, if the residual heat removal system loses its function, the temperature of the pool water in the suppression pool 8 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 saturated vapor pressure of the temperature of the pool water, so that the pressure in the reactor containment vessel 1 rises. When such a pressure rise occurs, the pressure rise can be suppressed by spraying the cooling water in the reactor containment vessel 1. In addition, this spray can be operated by connecting a fire pump or the like from the outside. However, even very unlikely, if this spray also does not work, the pressure in the reactor containment 1 will rise. When such a pressure rise in the reactor containment vessel 1 occurs, the pressure in the reactor containment vessel 1 rises by discharging the gas in the reactor containment vessel 1 from the vent line 15 to the outside through the exhaust tower 13. Can be suppressed. This operation is called a vent operation. In a boiling water reactor, this venting operation is performed by releasing the gas in the wet well 7, so that the water in the suppression pool 8 can remove the radioactive substances as much as possible and then release the gas to the outside. it can.

By performing the vent operation, most of the radioactive substances are removed, and the released gas from which the radioactive substances have been removed is discharged to the outside from the exhaust tower 13. However, since the radioactive rare gas has poor reactivity, the radioactive substance cannot be removed by a venting operation that only releases the radioactive rare gas from the wet well 7. Therefore, in the conventional vent operation, it is necessary to wait until the radioactivity of this radioactive rare gas is attenuated. In the conventional configuration, the vent operation cannot be performed for a relatively short time after the reactor scram. Further, even when the venting operation is performed, it is desirable that the released gas does not contain radioactive substances as much as possible, and it is desired to improve the removal performance of radioactive substances. The reactor containment vessel vent system 40 of the first embodiment is a solution to these conventional problems.

Next, the configuration of the reactor containment vessel vent system 40 installed in the reactor containment vessel 1 of the first embodiment will be described.
The reactor containment vessel vent system 40 is provided with a vent line 15 that connects the gas phase portion 7a of the wet well 7 in the reactor containment vessel 1 and the external exhaust tower 13. Then, on the upstream side inside the reactor containment vessel 1 of the vent line 15, a radioactive material filtering system 14 having a filter that allows steam to permeate and does not permeate almost all radioactive substances including radioactive rare gas is installed.

By connecting the radioactive material filtering system 14 to the vent line 15, the pressure of the reactor containment vessel 1 can be reduced, and at the same time, almost all radioactive materials can be confined in the reactor containment vessel 1.

FIG. 2 shows the configuration of the radioactive material filtering system 14 included in the reactor containment vessel vent system 40.
The radioactive material filtering system 14 includes a filter 30, a protective container 31, a filtering system start valve 32, and a bypass on-off valve 33.

The protective vessel 31 is installed in the gas phase portion 7a of the wet well 7 in the reactor containment vessel 1. An opening 15a on the upstream side of the vent line 15 is connected to the inside of the protective container 31. Then, a filtering system activation valve 32 is installed at a position separating the gas phase portion 7a of the wet well 7 and the inside of the protective container 31.

The filtering system start valve 32 opens when the operating pressure A set from the wet well 7 side is applied. As the filtering system start valve 32, for example, when an operating pressure A is applied, a rupture disk, which is a member that automatically bursts at that pressure, is used. The use of a rupture disk is an example, and as long as it functions as a valve that opens when an operating pressure A is applied, a filtering system start valve 32 having another configuration may be used.
The operating pressure A at which the filtering system start valve 32 opens is set to be less than the limit pressure, which is the pressure at which the reactor containment vessel 1 can be safely operated by design.
By using such a filtering system start valve 32, the reactor containment vessel 1 can be depressurized through the filter 30 without the operation of an operator and without the need for a power source or a driving fluid.

A filter 30 is attached to the inside of the protective container 31 so as to cover the opening 15a of the vent line 15. Therefore, when the filtering system start valve 32 is open, the gas that has entered the protective container 31 from the gas phase portion 7a of the wet well 7 passes through the filter 30 and passes through the vent line 15.
The filter 30 is made of a material capable of allowing vapor to permeate and trap radioactive substances.

Here, the structural material of the filter 30 will be described.
The filter 30 needs to be permeable to vapor. Further, in order to prevent pressurization of the reactor containment vessel 1, it is desirable that hydrogen that may be generated when the core 2 is melted can also permeate. The molecular diameter of steam and hydrogen to be permeated is as small as 0.3 nm or less, and among the radioactive substances that are not permeated, the radioactive rare gas (mainly krypton and xenon) having a small molecular diameter is considerably larger. Therefore, in order to selectively permeate vapors and hydrogen having a small molecular diameter, it is conceivable to use a membrane that can be separated by molecular sieving.

In the case of a boiling water reactor, the gas inside the reactor containment vessel 1 is replaced with nitrogen. When gas is selected by molecular sieving using the molecular size, nitrogen having a molecular size similar to that of krypton or xenon may not permeate, but there is no problem from the viewpoint of depressurizing the containment vessel. Optimal filters for such applications include molecular sieves such as polymer membranes containing polyimide as the main component, ceramic film containing silicon nitride as the main component, and graphene oxide film containing carbon as the main component. It is desirable to use a membrane. Some of these filters are generally used in filters used for hydrogen purification. Further, as another filter, if it is a membrane that hardly permeates krypton or xenon and permeates water vapor, they may be used. For example, a nitrogen separation membrane that permeates water vapor used for nitrogen purification and hardly permeates nitrogen may be used as a filter.

By providing such a filter 30, when the pressure inside the reactor containment vessel 1 exceeds the operating pressure A for opening the filtering system start valve 32, the filtering system start valve 32 is opened and radioactive substances are removed. While venting is performed. That is, the gas passing through the vent line 15 is a gas from which radioactive substances have been removed by the filter 30, and the gas from which the radioactive substances have been removed is discharged from the exhaust tower 13 to the outside.

Isolation valves 34a and 34b are attached to the vent line 15. The isolation valve 34a is arranged at the vent line 15 inside the reactor containment vessel 1, and the isolation valve 34b is arranged at the vent line 15 inside the reactor containment vessel 1. By arranging the isolation valves 34a and 34b, the inside and outside of the reactor containment vessel 1 can be isolated when the vent becomes unnecessary after the residual heat removal system is restored.

Further, the protective container 31 is connected to the radioactive material encapsulation device 17 via the bypass flow path 16. Here, the opening 16a on the upstream side of the bypass flow path 16 is connected to the protective container 31 via the bypass on-off valve 33. When the bypass on-off valve 33 is open, the gas flowing from the protective container 31 to the bypass flow path 16 does not pass through the filter 30.

The operating pressure B at which the bypass on-off valve 33 opens is set higher than the operating pressure A at the filtering system start valve 32. By setting the operating pressures A and B in this way, venting through the filter 30 is performed as much as possible. Further, by setting the operating pressure B at which the valve of the bypass on-off valve 33 opens to be less than the limit pressure of the reactor containment vessel 1, the reactor containment vessel 1 can be surely kept below the limit pressure. The bypass on-off valve 33 is configured to open at an operating pressure B or higher and then close again when the operating pressure drops below B.

The radioactive material encapsulation device 17 encloses the gas supplied via the bypass flow path 16. As the radioactive substance encapsulation device 17, a small encapsulation container having a relatively small capacity is used.
A vent line 15 is connected to the radioactive material encapsulation device 17 via an isolation container gas release valve 18. The isolation container gas release valve 18 opens at an operating pressure C of less than the operating pressure B, and closes when the operating pressure becomes less than C. When the isolation container gas release valve 18 is open, the gas inside the radioactive material encapsulation device 17 is discharged to the outside from the exhaust tower 13 via the vent line 15.
As with the vent line 15, isolation valves 34c and 34d are also attached to the bypass flow path 16. The isolation valve 34c is arranged in the bypass flow path 16 inside the reactor containment vessel 1, and the isolation valve 34d is arranged in the bypass flow path 16 inside the reactor containment vessel 1.

As described above, by providing the reactor containment vessel vent system 40 of the present embodiment, when the pressure in the reactor containment vessel 1 is equal to or higher than the operating pressure A, the filtering system start valve 32 opens and the filter 30 The radioactive material is removed and exhausted from the exhaust tower 13. In this case, the protective container 31 functions to protect the filter 30 at the initial stage of the accident. Then, when the pressure of the reactor containment vessel 1 rises, the filtering system start valve 32 opens, and venting using the filter 30 is performed.

Therefore, the inside of the reactor containment vessel 1 can be surely kept below the limit pressure, and leakage of radioactive substances at the time of venting can be prevented. Moreover, the reactor containment vessel vent system operates automatically without the need for operation by an operator, and does not require a power source or driving fluid for its operation, so that the safety of workers is maintained. Therefore, the reactor containment vessel 1 can be reliably depressurized.

Further, in the event of an accident or a severe accident, water droplets, aerosols, and volatile FP may remain in the reactor containment vessel 1. Then, due to the adhesion of these, there is a possibility that the performance of the filter 30 is deteriorated with an extremely low probability. However, the deterioration of the performance of the filter 30 can be reduced as much as possible by blocking these substances that reach the filter 30 by the protective container 31. Further, since the aerosol and the volatile FP can be removed by the scrubbing effect of the pool water of the suppression pool 8, the aerosol and the volatile FP reaching the filter 30 are reduced as much as possible.

Further, when the filtering system start valve 32 is opened, gas that cannot pass through the filter 30 stays in the space between the filtering system start valve 32 and the filter 30 in the protective container 31. If an impermeable gas stays in the filter 30, the permeation performance of the filter 30 may deteriorate and the reactor containment vessel 1 may not be depressurized. However, by providing the bypass flow path 16 and the radioactive material encapsulation device 17, It is possible to prevent deterioration of the permeation performance.

That is, when the operating pressure B is equal to or lower than the limit pressure of the reactor containment vessel 1, the bypass on-off valve 33 opens and the gas is discharged to the radioactive material filling device 17 through the bypass flow path 16 without passing through the filter 30. The reactor containment vessel 1 can be depressurized. Then, the impermeable gas near the filter 30 is discharged to the radioactive substance filling device 17, and after the permeation performance is restored, the bypass on-off valve 33 is closed. As a result, the gas from which almost all radioactive substances have been removed through the filter 30 is returned to the state of being discharged to the outside of the reactor containment vessel 1.

Since the opening / closing of the bypass on-off valve 33 is also automatically performed according to the pressure of the reactor containment vessel 1, the operation of recovering the permeation performance of the filter 30 is performed without the operation of the operator. Here, by setting the operating pressure B of the bypass on-off valve 33 to be higher than the operating pressure A of the filtering system start valve 32, venting through the filter 30 is performed as much as possible.
Further, even when the bypass on-off valve 33 is open, the radioactive material is sealed in the radioactive material encapsulation device 17, so that the possibility of the radioactive material leaking to the outside of the reactor containment vessel 1 is reduced to the utmost limit. be able to.

Since the gas flows into the radioactive material filling device 17 only while the bypass on-off valve 33 is open, the total amount of gas flowing into the radioactive material filling device 17 is very small. Therefore, as the radioactive material encapsulation device 17, it is not necessary to prepare a large-capacity container or a complicated hold-up device as conventionally required, and a small encapsulation container is sufficient.
Further, although it is possible that it is even lower, if the pressure inside the radioactive material encapsulation device 17 becomes equal to or higher than the operating pressure B of the bypass on-off valve 33, the gas cannot be discharged and the reactor containment vessel 1 cannot be depressurized. In some cases. Even in such a case, by providing the isolation container gas release valve 18 that opens at an operating pressure C lower than the operating pressure B, it is possible to avoid a state in which depressurization cannot be performed. That is, the isolation container gas release valve 18 functions as a safety valve that closes when the operating pressure becomes less than C.

[2. Example of Second Embodiment]
Next, an example of the second embodiment of the present invention will be described with reference to FIGS. 3 to 5. In FIGS. 3 to 5, the same parts as those in FIGS. 1 and 2 described in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 3 shows a schematic configuration of the reactor containment vessel 1 and the reactor containment vessel vent system 40'of the second embodiment. Also in FIG. 3, the reactor containment vessel 1 is shown as a vertical cross section.
The second embodiment is also applied to the improved boiling water reactor.

Also in the present embodiment, as shown in FIG. 3, the radioactive material filtering system 14'is arranged in the gas phase portion 7a of the wet well 7 in the reactor containment vessel 1.
One end of the vent line 15'is connected to the radioactive material filtering system 14'arranged in the gas phase portion 7a of the wet well 7. The other end of the vent line 15'is connected to the filter vent device 20 outside the reactor containment vessel 1. Isolation valves 34a and 34b are attached to the vent line 15'.

The filter vent device 20 is a device conventionally used as a general filter vent system, and is arranged inside the shielding wall 25.
Explaining the configuration of the filter vent device 20, the scrubbing pool water 21 is stored on the lower side of the filter vent device 20. Then, the gas discharged from the radioactive material filtering system 14'through the vent line 15'is discharged into the scrubbing pool water 21.

Further, a wire mesh-like metal filter 22 and an iodine filter 23 are installed on the upper side of the filter vent device 20. One end of the outlet pipe 24 of the filter vent device 20 is connected to the iodine filter 23. The other end of the outlet pipe 24 penetrates the shielding wall 25 and is led out to the outside of the shielding wall 25, and finally exhausts gas from the exhaust tower 13 to the outside.

FIG. 4 shows the configuration of the radioactive material filtering system 14 ′ included in the reactor containment vessel vent system 40 ′.
The radioactive material filtering system 14'is the same as the radioactive material filtering system 14 described in the first embodiment in that the filter 30, the protective container 31, the filtering system start valve 32, and the bypass on-off valve 33 are provided. is there. However, in the example of the present embodiment, the filter 30 is arranged inside the protective container 31 so as to cover the opening 15a on the upstream side of the vent line 15', and the bypass on-off valve 33 is provided in the opening 15a. Is also connected. Therefore, when the bypass on-off valve 33 is open, the gas that does not pass through the filter 30 flows through the vent line 15'. That is, in the example of the present embodiment, the bypass on-off valve 33 itself constitutes the bypass flow path.

The operating pressure A of the filtering system start valve 32 and the operating pressure B of the bypass on-off valve 33 are set in the same manner as the operating pressures A and B described in the first embodiment.
Other parts of the reactor containment vessel 1 and the reactor containment vessel vent system 40'of the present embodiment are the same as those of the reactor containment vessel 1 and the reactor containment vessel vent system 40 of the first embodiment. Constitute.

According to the reactor containment vessel vent system 40'of the present embodiment configured in this manner, when the pressure in the reactor containment vessel 1 rises, the gas from which radioactive substances have been removed by the filter 30 is the filter vent device 20. Venting is performed with the radioactive material removed. Then, when the pressure inside the protective container 31 rises due to the deterioration of the performance of the filter 30 and the bypass on-off valve 33 opens, a gas containing a radioactive substance is supplied to the filter vent device 20.

When the gas containing the radioactive substance enters the filter vent device 20 in this way, most of the aerosol is mainly removed by scrubbing with the scrubbing pool water 21. Further, the metal filter 22 can remove aerosols that could not be completely removed by scrubbing, and the iodine filter 23 can remove volatile FPs such as iodine that could not be completely removed by scrubbing. As a result, for example, when the radioactive substance filtering system 14'is removed and inspected, even if an accident should occur, the radioactive substance is removed as much as possible by the filter vent device 20 downstream of the vent line 15'. Therefore, the gas can be released to the outside. Further, even if the bypass on-off valve 33 is opened by any chance, the radioactive substance can be removed as much as possible and the gas can be released to the outside. This can reduce the risk of radioactive material being released into the environment and improve the reliability of the reactor containment vent system.

Further, in the example of the present embodiment, it is not necessary to arrange the bypass flow path (corresponding to the bypass flow path 16 in FIG. 1) separately from the vent line 15', and the discharge line can be made common accordingly.
By sharing the discharge line, the number of pipes can be reduced, so that the structure of the reactor containment vessel vent system 40'can be simplified and the economic efficiency can be improved. Further, the number of through holes in the reactor containment vessel 1 can be reduced, and the safety can be improved.

It should be noted that it is an example that the vent line 15'of one system is shared, and the vent line 15 and the bypass flow path 16 may be prepared.
FIG. 5 shows the configuration of the radioactive material filtering system 14'in this case.
As shown in FIG. 5, as the internal configuration of the radioactive material filtering system 14', the vent line 15'and the bypass flow path 16' are separated as in the example of FIG. 4 described in the first embodiment. .. Then, the filter 30 is arranged so as to cover the opening 15a of the vent line 15', and the bypass on-off valve 33 is arranged in the opening 16a of the bypass flow path 16'.

In this case, the vent line 15'is directly connected to the exhaust tower 13 and only the bypass flow path 16'is connected to the filter vent device 20. Alternatively, both the vent line 15'and the bypass flow path 16' may be connected to the filter vent device 20.

[3. Example of a third embodiment]
Next, an example of the third embodiment of the present invention will be described with reference to FIG. In FIG. 6, the same parts as those in FIGS. 1 to 5 described in the first and second embodiments are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 6 shows a schematic configuration of the reactor containment vessel 1 and the reactor containment vessel vent system 40 ″ of the third embodiment. In FIG. 6, the reactor containment vessel 1 is shown as a vertical cross section.
Also in the third embodiment, it is applied to the reactor containment vessel 1 as an improved boiling water reactor.

Also in the present embodiment, as shown in FIG. 6, the radioactive material filtering system 14'is arranged in the gas phase portion 7a of the wet well 7 in the reactor containment vessel 1.
One end of the vent line 15 ″ is connected to the radioactive material filtering system 14 ′ located in the gas phase portion 7a of the wet well 7. The other end of the vent line 15 ″ is outside the reactor containment vessel 1. It is connected to the exhaust tower 13. Isolation valves 34a and 34b are attached to the vent line 15 ″.

The radioactive material filtering system 14'is the same as the configuration of FIG. 4 described in the second embodiment. That is, as shown in FIG. 4, the radioactive material filtering system 14'includes a filter 30, a protective container 31, a filtering system start valve 32, and a bypass on-off valve 33, and the filter 30 and the bypass on-off valve 33 are arranged in parallel. Is arranged.
Other parts of the reactor containment vessel 1 and the reactor containment vessel vent system 40 ″ of the present embodiment are the same as those of the reactor containment vessel 1 and the reactor containment vessel vent system 40 ′ of the second embodiment. Configure to.

With this configuration, at the time of venting, almost all radioactive materials are confined in the reactor containment vessel 1 by the filter 30 in the radioactive material filtering system 14', and steam is released to the outside to prevent pressurization. it can.
In the present embodiment, the structure on the downstream side of the vent line 15 "can be simplified, the structure of the reactor containment vessel vent system 40" can be simplified, and the economic efficiency can be enhanced.

In the example of FIG. 6, as the radioactive material filtering system 14', the configuration shown in FIG. 5 is applied so that a line corresponding to the bypass flow path 16'is arranged separately from the vent line 15 ″. May be good.

[4. Fourth Embodiment Example]
Next, an example of the fourth embodiment of the present invention will be described with reference to FIG. 7. In FIG. 7, the same parts as those in FIGS. 1 to 6 described in the first to third embodiments are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 7 shows a schematic configuration of the reactor containment vessel 1 and the reactor containment vessel vent system 40 of the fourth embodiment. In FIG. 7, the reactor containment vessel 1 is shown as a vertical cross section.
The fourth embodiment is also applied to the reactor containment vessel 1 as an improved boiling water reactor.

In the example of FIG. 7, the radioactive material filtering system 14 was placed in the dry well 6 inside the reactor containment vessel 1.
As for the configuration of the radioactive material filtering system 14 arranged in the dry well 6, for example, the radioactive material filtering system 14 shown in FIG. 2 in the first embodiment can be applied. That is, the vent line 15 and the bypass flow path 16 are connected to the radioactive material filtering system 14, and the gas from which the radioactive material has been removed by the filter 30 (FIG. 2) is supplied to the exhaust tower 13 via the vent line 15. Will be done. Further, the gas when the filtering system start valve 32 (FIG. 2) in the radioactive material filtering system 14 is opened is sealed in the radioactive material filling device 17.

Also in this case, the isolation valves 34a and 34b are arranged in the vent line 15, and the isolation valves 34a and 34b are arranged in the bypass flow path 16. Further, the isolation container gas release valve 18 is attached to the radioactive material filling device 17.
Other parts of the reactor containment vessel 1 and the reactor containment vessel vent system 40 of the present embodiment are configured in the same manner as the reactor containment vessel 1 and the reactor containment vessel vent system 40 of the first embodiment. Will be done.

As shown in FIG. 7, by arranging the radioactive material filtering system 14 in the dry well 6, the radioactive material filtering system 14 functions stably regardless of the water level of the suppression pool 8 in the wet well 7. Further, even if an aerosol or volatile FP is present in the dry well 6 when the core 2 is melted, or when water droplets are scattered during water injection, the protective container 31 protects the filter 30 to improve the permeation performance. It can be prevented from deteriorating.

Two sets of radioactive material filtering systems 14 may be prepared. In this case, one radioactive material filtering system 14 is placed in the dry well 6 as shown in FIG. 7, and the other radioactive material filtering system 14 is placed in the wet well vapor phase portion 7a as shown in FIG. Deploy. By parallelizing the radioactive material filtering system 14 in this way, safety can be further improved.
When the radioactive material filtering system 14 is arranged in the dry well 6, the filter vent device 20 as shown in FIG. 3 may be arranged in the downstream portion of the vent line 15. Alternatively, as shown in FIG. 6, the vent line 15 may be directly connected to the exhaust tower 13.

[5. Fifth Embodiment Example]
Next, an example of a fifth embodiment of the present invention will be described with reference to FIG. In FIG. 8, the same parts as those in FIGS. 1 to 7 described in the first to fourth embodiments are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 8 shows a schematic configuration of the reactor containment vessel 1'and the reactor containment vessel vent system 40 of the fifth embodiment. In FIG. 8, the reactor containment vessel 1 is shown as a vertical cross section.
In the fifth embodiment, it is applied to a reactor containment vessel 1'equipped with a pressurized water reactor.

As shown in FIG. 8, a reactor pressure vessel 3, a pressurizer 26, a steam generator 27, and a recirculation pump 28 are arranged in a reactor containment vessel 1'configured as a pressurized water reactor. Has been done. The steam generator 27 is configured to generate steam by the heat generated in the reactor pressure vessel 3. A main steam pipe 4 that sends steam generated in the steam generator 27 to a turbine (not shown) is connected to the steam generator 27.

Then, the radioactive material filtering system 14 is arranged inside the reactor containment vessel 1'. As the radioactive material filtering system 14, for example, the configuration of the radioactive material filtering system 14 shown in FIG. 2 in the first embodiment can be applied. That is, the vent line 15 and the bypass flow path 16 are connected to the radioactive material filtering system 14, and the gas from which the radioactive material has been removed by the filter 30 (FIG. 2) is supplied to the exhaust tower 13 via the vent line 15. Will be done. Further, the gas when the filtering system start valve 32 (FIG. 2) in the radioactive material filtering system 14 is opened is sealed in the radioactive material filling device 17.

Also in this case, the isolation valves 34a and 34b are arranged in the vent line 15, and the isolation valves 34a and 34b are arranged in the bypass flow path 16. Further, the isolation container gas release valve 18 is attached to the radioactive material filling device 17.

Since the pressurized water reactor shown in FIG. 8 does not have a wet well and a suppression pool for suppressing the pressure rise in the reactor containment vessel, it cannot be expected that the suppression pool will remove radioactive materials by scrubbing, but at the time of venting. Radioactive material can be removed. That is, since the filter 30 in the radioactive material filtering system 14 removes the radioactive material, the steam in the reactor containment vessel 1'is continuously released to the outside of the system without releasing the radioactive material to the outside as much as possible. The pressure in the reactor containment vessel 1'can be continuously reduced. Moreover, it does not require an operation by a worker and does not require a large-capacity container for storing radioactive substances and the like, which is the same as the other embodiment described above.

In the case of a pressurized water reactor, the filter venting device 20 is also applied by applying the reactor containment vessel venting system 40'described in the second embodiment instead of the reactor containment vessel venting system 40. May be arranged. Alternatively, the reactor containment vessel vent system 40 "described in the third embodiment is applied, and the vent line 15" is directly connected to the exhaust tower 13 without arranging the radioactive material encapsulation device 17. May be applied.

[6. Modification example]
It should be noted that the configurations described in each of the above-described embodiments are shown as suitable examples, and the present invention is not limited to the configurations shown in the respective figures.
For example, in each embodiment, the reactor containment vessel vent system 40, 40'or 40 "is applied to a light water reactor (boiling water reactor, pressurized water reactor), but a heavy water reactor, a graphite furnace, etc. It may be applied to gas reactors. Other reactors such as high temperature gas reactors, so-called 4th generation reactors, supercritical pressure light water reactors, molten salt reactors, gas cooling fast reactors, sodium cooling fast reactors, lead cooling fast reactors, etc. The reactor containment vessel vent system 40, 40'or 40 "of each embodiment may be applied to the mold.

Further, the present invention is not limited to the above-described embodiments, but includes various modifications. For example, each of the above-described embodiments has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment or modification, and the configuration of one embodiment may be replaced with another embodiment or modification. It is also possible to replace it with the example configuration. Further, it is possible to add / delete / replace a part of the configuration of the embodiment with another configuration.

1,1'... Containment vessel, 2 ... Core, 3 ... Reactor pressure vessel, 4 ... Main steam pipe, 5 ... Diaphragm floor, 6 ... Dry well, 7 ... Wet well, 7a ... Gas phase part, 8 ... Suppression pool, 9 ... Vent pipe, 9a ... Vent pipe exhaust, 10 ... Steam escape safety valve, 11 ... Steam escape safety valve exhaust pipe, 12 ... Quencher, 13 ... Exhaust tower, 14, 14'... Radioactive material filtering system, 15, 15', 15 "... vent line, 15a ... opening, 16, 16' ... bypass flow path, 16a ... opening, 17 ... radioactive material encapsulation device, 18 ... isolation vessel gas release valve, 20 ... filter vent device, 21 ... Pool water for scrubbing, 22 ... Metal filter, 23 ... Iodine filter, 24 ... Outlet piping, 25 ... Shielding wall, 26 ... Pressurizer, 27 ... Steam generator, 28 ... Recirculation pump, 30 ... Filter, 31 ... Protection Container, 32 ... Filtering system start valve, 33 ... Bypass on-off valve, 34a-34d ... Isolation valve, 40, 40', 40 "... Reactor containment vent system

Claims (15)

A vent line that decompresses the reactor containment vessel by discharging the gas inside the reactor containment vessel to the outside, and
A filter located at the end of the vent line on the side of the reactor containment vessel, which suppresses the permeation of radioactive materials and allows vapor to permeate.
A protective vessel that surrounds the end of the vent line inside the reactor containment vessel and the filter.
For bypassing the vent line installed in the protective vessel for opening at an operating pressure equal to or lower than the limit pressure of the reactor containment vessel, closing at an operating pressure below the operating pressure, and discharging gas to the outside without passing through the filter. On-off valve and
A reactor containment vessel vent system that is installed in the protective vessel and includes a start valve that opens at an operating pressure equal to or lower than the operating pressure of the bypass on-off valve. The reactor containment vessel vent system according to claim 1, wherein the bypass on-off valve is connected to a bypass flow path different from the vent line. The reactor containment vessel vent system according to claim 2, wherein a radioactive material encapsulation device for encapsulating a radioactive substance contained in a gas released from the bypass on-off valve into the bypass flow path is connected to the bypass flow path. The reactor containment vessel vent system according to claim 2, wherein a filter vent device for removing radioactive substances contained in a gas released from the bypass on-off valve into the bypass flow path is connected. The reactor containment vessel vent system according to claim 1, wherein the bypass on-off valve is connected to the vent line. The reactor containment vessel vent system according to claim 5, wherein a filter vent device for removing radioactive substances contained in the gas released from the vent line is connected. The reactor containment vessel vent system according to claim 1, wherein the filter is made of a material that suppresses the permeation of radioactive rare gas and permeates steam. The reactor containment vessel vent system according to claim 7, wherein the filter is made of a polymer membrane. The reactor containment vessel vent system according to claim 8, wherein the polymer film contains polyimide as a main component. The reactor containment vessel vent system according to claim 7, wherein the filter is made of a ceramic film. The reactor containment vessel vent system according to claim 10, wherein the ceramic film contains silicon nitride as a main component. The reactor containment vessel vent system according to claim 7, wherein the filter is a graphene oxide film. The reactor containment vessel vent according to any one of claims 1 to 12, wherein the protective vessel in which the filter and the bypass on-off valve are arranged is installed in a wet well gas phase portion in the reactor containment vessel. system. The reactor containment vessel vent system according to any one of claims 1 to 12, wherein the protective vessel in which the filter and the bypass on-off valve are arranged is installed in a dry well in the reactor containment vessel. The reactor containment vessel vent system according to any one of claims 1 to 12, wherein the reactor containment vessel is a boiling water reactor or a pressurized water reactor.

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