JP2018151355A - Reactor containment vent system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactor containment vent system capable of continually releasing steam inside a reactor containment to the outside of the system and continuously reducing the pressure of the reactor containment without releasing radioactive rare gas from the reactor containment to the outside during operating the vent.SOLUTION: The reactor containment vent system includes: a vent line for discharging a gas inside the reactor containment to the outside of the reactor containment; a rare gas filter disposed in the vent line; a return piping connecting the upstream of the rare gas filter and the reactor containment in the vent line; and a pump disposed in the return piping. The rare gas filter is a film filter that shuts off the radioactive noble gas but permeates vapor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reactor containment vessel vent system provided in a nuclear power plant.

  In nuclear power plants, even if the core placed in the reactor pressure vessel melts (hereinafter referred to as “severe accident”), radioactive materials are released outside the reactor pressure vessel, One of the important functions of a containment vessel is to confine radioactive materials in the containment vessel and prevent leakage to the outside. Even in the event of a severe accident, the accident will converge if sufficient water injection is performed thereafter and the reactor containment vessel is cooled.

  However, in the unlikely event that steam generation continues and the reactor containment vessel is not sufficiently cooled, the reactor containment vessel is pressurized. When the reactor containment vessel is pressurized, the gas in the reactor containment vessel may be released into the atmosphere and the reactor containment vessel may be depressurized. This operation is called a vent operation. When performing this operation, in order to minimize exposure to the public in boiling water reactors, the radioactive material is removed by the pool water in the suppression pool, and then the gas in the reactor containment vessel (hereinafter referred to as “vent gas”). .) To the atmosphere.

  In the boiling water reactor, as described above, the radioactive material is sufficiently removed by the pool water of the suppression pool, and then the vent gas is released into the atmosphere. As a system for further removing the radioactive material from the vent gas, There is a reactor containment vent system. For example, a filter vent device for a general nuclear reactor containment vessel described in Patent Document 1 is a device for removing radioactive substances from a vent gas, a tank containing water, a pipe for guiding the vent gas into the water of the tank, And the radioactive substance removal filter is comprised in the exit which discharges vent gas from a tank.

  Most of the particulate radioactive material (aerosol particles) contained in the vent gas is physically removed by water in the tank. On the other hand, gaseous radioactive substances such as iodine are removed by chemical reaction and adsorption in an iodine filter which is a kind of radioactive substance removing filter.

  Patent Document 2 describes a system having an adsorption tower that encloses xenon and krypton (rare gas) contained in a vent gas in an adsorbent by dynamic adsorption with respect to venting of a nuclear facility.

JP 2014-44118 A JP-T-2006-521843

  It is considered that radioactive noble gases need to be physically separated because of poor reactivity.

  In Patent Document 2, an adsorption tower is used for the purpose of removing radioactive noble gases. However, in order not to release the rare gas contained in the vent gas until the radioactivity is sufficiently attenuated, it is necessary to install a plurality of large adsorption towers. In addition, a large number of accompanying devices such as a boiler and complicated piping for backwashing the adsorption tower are required.

  In the present invention, during the venting operation, without releasing the radioactive noble gas outside the reactor containment vessel, the steam in the reactor containment vessel is continuously released out of the system, and the pressure in the reactor containment vessel is continued. The purpose is to reduce the pressure.

  The present invention relates to a vent line that discharges gas inside a reactor containment vessel to the outside of the reactor containment vessel, a rare gas filter provided in the vent line, an upstream side of the rare gas filter in the vent line, and the reactor containment. A reactor containment vessel vent system comprising a return pipe connecting a vessel and a pump provided in the return pipe, wherein the rare gas filter is a membrane that blocks radioactive noble gas and permeates water vapor It is a filter.

  According to the present invention, during the venting operation, without releasing the radioactive noble gas to the outside of the reactor containment vessel, the steam in the reactor containment vessel is continuously released out of the system, and the pressure in the reactor containment vessel is increased. Can be continuously reduced in pressure.

1 is a schematic configuration diagram illustrating a reactor containment vessel vent system according to a first embodiment. It is a schematic block diagram which shows the reactor containment vessel vent system of Example 2. FIG. FIG. 5 is a schematic configuration diagram showing a reactor containment vessel vent system according to a third embodiment. It is a schematic block diagram which shows the reactor containment vessel vent system of Example 4. FIG. FIG. 6 is a schematic configuration diagram illustrating a reactor containment vessel vent system according to a fifth embodiment.

  The reactor containment vessel vent system of the present invention reduces the pressure in the reactor containment vessel, and removes radioactive substances as much as possible when the pressure is reduced.

  Hereinafter, details of the reactor containment vessel vent system according to the present invention will be described using examples.

  FIG. 1 is a longitudinal sectional view showing a schematic configuration of a reactor containment vessel and its vent system. The portion surrounded by the broken line in the figure is the reactor containment vessel vent system of the present embodiment.

  The reactor containment vessel vent system shown in this figure is an example applied to an improved boiling water reactor (ABWR).

  In this figure, the reactor containment vessel 1 is provided with a filter vent device 15 (reactor containment vessel vent system).

  In the reactor containment vessel 1, a reactor pressure vessel 3 containing a core 2 is installed. Connected to the reactor pressure vessel 3 is a main steam pipe 4 for sending steam (water vapor) generated in the reactor pressure vessel 3 to a turbine (not shown).

  The inside of the reactor containment vessel 1 is partitioned into a dry well 5 and a wet well 7 by a diaphragm floor 12 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 5 and the wet well 7 are communicated with each other by a vent pipe 11. A vent pipe exhaust part 11 a that is an opening of the vent pipe 11 is provided below the surface of the suppression pool 8 in the wet well 7. In the unlikely event that a part of the piping is damaged and a pipe breakage accident (generally known by the name of LOCA, which occurs in the dry well 5 through which the pipe passes) occurs in which steam is released into the reactor containment vessel 1, The pressure in the dry well 5 rises due to the steam flowing out from the breakage opening. At that time, the vapor released into the dry well 5 is guided into the water of the suppression pool 8 in the wet well 7 through the vent pipe 11 due to the pressure difference between the dry well 5 and the wet well 7.

  By condensing the steam with the water in the suppression pool 8, the pressure increase in the reactor containment vessel 1 is suppressed. At this time, most of the radioactive material contained in the steam is removed by the scrubbing effect of the water in the suppression pool 8.

  As described above, when a pipe breakage accident occurs in the dry well 5, the steam flowing out from the breakage port is condensed in the suppression pool 8 through the vent pipe 11. Similarly, when the pressure in the reactor pressure vessel 3 or the main steam pipe 4 becomes high, the steam is discharged to the suppression pool 8 and the pressure in the reactor pressure vessel 3 or the main steam pipe 4 is lowered. At the same time, the released steam is condensed in the suppression pool 8 to alleviate the pressure increase in the reactor containment vessel 1.

  As an apparatus for that purpose, in ABWR, a steam relief safety valve 6 is installed in the region of the dry well 5 in the reactor containment vessel 1. The steam released through the steam relief safety valve 6 passes through the steam relief safety valve exhaust pipe 9 and is finally discharged from the quencher 10 into the suppression pool 8 and is condensed by the water in the suppression pool 8. By condensing the steam in the suppression pool 8 into liquid water, the volume of the steam is greatly reduced, and the pressure increase in the reactor containment vessel 1 can be suppressed. At this time, most of the radioactive material contained in the steam is removed by the scrubbing effect of the water in the suppression pool 8.

  By condensing steam in the suppression pool 8 and cooling the water in the suppression pool 8 with a residual heat removal system (not shown), temperature rise and pressure rise of the reactor containment vessel 1 are prevented, and the accident is converged. Can do.

  However, although the possibility is very low, when the residual heat removal system loses its function, the temperature of the pool water in the suppression pool 8 rises. As the pool water temperature rises, the partial pressure of the steam in the reactor containment vessel 1 rises to the saturated steam pressure of the pool water temperature, so 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 into the reactor containment vessel 1. Further, this spray can be operated by connecting a fire pump or the like from the outside.

  However, the pressure in the reactor containment vessel 1 increases, even though this possibility is much less likely, if this spray is also not activated. When such a pressure increase in the reactor containment vessel 1 occurs, the pressure rise in the reactor containment vessel 1 can be suppressed by releasing the gas in the reactor containment vessel 1 to the outside. This operation is called a “vent operation”. In a boiling water reactor, by performing this venting operation by releasing the gas in the wet well 7, it is possible to remove the radioactive material to the maximum with the water in the suppression pool 8 and then release the gas to the outside. it can.

  In performing this venting operation, there is a filter vent device 15 (reactor containment vessel vent system) as a device for further removing radioactive substances from the gas released to the outside.

  Next, a general vent system will be described.

  As shown in this figure, the filter vent device 15 includes a vent pipe 13 (upstream vent pipe), a filter container 16, an outlet pipe 20 (downstream vent pipe), an exhaust tower 22, and a return pipe 24 (reflux). Piping), a pump 25, and a check valve 26. The upstream vent pipe and the downstream vent pipe constitute a vent line.

  The vent pipe 13 is connected to the dry well 5 and the wet well 7 of the reactor containment vessel 1. The vent pipe 13 is provided with isolation valves 14a and 14b. The isolation valve 14a is a wet well side isolation valve, and the isolation valve 14b is a dry well side isolation valve. The vent pipe 13 is connected to the inlet pipe 17 of the filter container 16. The distal end side of the inlet pipe 17 opens into the filter container 16. The venting operation is usually performed by opening the isolation valve 14a on the wet well 7 side.

  The periphery of the filter container 16 is covered with a shielding wall 21. The outlet pipe 20 is a pipe that connects the filter container 16 and the exhaust tower 22. A metal filter 19, an iodine filter 38, and a rare gas filter 23 are installed in the outlet pipe 20 from the upstream side. The metal filter 19 has a wire mesh shape.

  The return pipe 24 is a pipe connecting the upstream side of the rare gas filter 23 in the outlet pipe 20 and the dry well 5. A pump 25 and a check valve 26 are installed in the return pipe 24.

  A scrubbing pool water 18 is stored in the lower part of the filter container 16. The outlet pipe 20 is connected to the upper part of the filter container 16 and penetrates the shielding wall 21. The outlet pipe 20 discharges the gas that has passed through the vent pipe 13 and the inlet pipe 17 and has flowed into the filter container 16 from the exhaust tower 22 to the outside.

  When the pressure in the reactor containment vessel 1 rises, the isolation valve 14a on the wet well side is normally opened. At this time, most of the radioactive material can be removed by scrubbing the emitted gas with the water of the suppression pool 8. This is a safety feature of boiling water reactors. The emitted gas that has entered the filter vent device 15 is further scrubbed with the scrubbing pool water 18 so that most of the aerosol-like radioactive material is removed. Further, gaseous radioactive substances such as iodine are removed by the metal filter 19 and the iodine filter 38.

  Most radioactive substances are removed by the above process. The emitted gas from which the radioactive material has been removed is emitted from the exhaust tower 22. However, radioactive noble gases are poorly reactive and cannot be removed with a typical filter vent system. Therefore, it is necessary to perform the current vent operation after waiting until the radioactive noble gas decays. For this reason, the current venting operation cannot be performed for a relatively short time after the reactor scram.

  In the reactor containment vessel vent system of the present embodiment, a rare gas filter 23 is installed on the downstream side of the outlet pipe 20. The noble gas filter 23 is made of a filter material (membrane filter) that blocks radioactive noble gas and transmits vapor. Thereby, steam can be discharged to the outside and the pressure in the reactor containment vessel 1 can be lowered.

  In addition, the noble gas filter 23 can remove radioactive noble gas at any position such as in the reactor containment vessel 1 or the vent pipe 13, but the noble gas filter 23 can be installed downstream of the filter vent device 15. It is possible to prevent deterioration of filter performance due to the attachment of aerosol-like radioactive material to the filter 23 and exposure to the influence of molten fuel that may occur at the time of an accident. The reliability of the system can be improved.

  As the structural material of the rare gas filter 23, there are the following materials.

  The rare gas filter 23 needs to transmit vapor. Further, in order to suppress an increase in the pressure in the reactor containment vessel 1, it is desirable that the rare gas filter 23 can transmit hydrogen that may be generated when the core 2 is melted. Water vapor and hydrogen to be transmitted have a small molecular diameter of 0.3 nm or less, and radioactive noble gases (mainly krypton and xenon) that should not be transmitted are considerably larger. Therefore, in order to selectively permeate vapor and hydrogen having a small molecular diameter, it is conceivable to use a membrane that can be separated by molecular sieve.

  In the case of a boiling water reactor, the gas in the reactor containment vessel 1 is replaced with nitrogen. When a gas is selected by molecular sieving using the molecular size, nitrogen having a molecular size close to that of krypton or xenon may not pass through the rare gas filter 23. This is not a problem from the viewpoint of depressurization of the reactor containment vessel 1. In other words, the noble gas filter 23 may be a membrane filter that blocks radioactive noble gases and nitrogen and transmits hydrogen and water vapor.

  Suitable filter materials for such applications include a polymer film mainly composed of polyimide, a ceramic film mainly composed of silicon nitride, and a graphene oxide film mainly composed of carbon. These filter materials are membranes that can be separated by molecular sieves. These filter materials are generally used for filters used for purifying hydrogen. In addition, any film that does not transmit krypton or xenon but transmits hydrogen and water vapor can be used as a filter material.

  The rare gas filter 23 preferably has a large surface area. For this reason, the membrane filter may be bent and arranged in a bellows shape. A hollow fiber membrane may be used as the membrane filter.

  The noble gas filter 23 using the filter material transmits steam and hydrogen, and does not pass nitrogen and radioactive materials, thereby removing radioactive noble gases and causing steam and hydrogen that cause a pressure increase in the reactor containment vessel 1. Can be released. However, with the passage of time, nitrogen and radioactive noble gas that do not permeate accumulate immediately upstream of the noble gas filter 23, and the partial pressure of these gases increases, so that the amount of vapor and hydrogen permeated decreases, There is a possibility that the function of lowering the pressure of the furnace containment vessel 1 is lowered.

  This problem is solved by the return pipe 24 of this embodiment.

  The return pipe 24 connects the upstream portion of the rare gas filter 23 and the reactor containment vessel 1. For this reason, the gas 25 which does not permeate | transmit can be returned to the reactor containment vessel 1 with the pump 25 installed in the return piping 24, and the vapor | steam permeability | transmittance performance of the noble gas filter 23 can be maintained. Further, by installing the check valve 26 in the return pipe 24, it is possible to prevent the gas containing the radioactive substance from flowing backward from the reactor containment vessel 1 to reach the rare gas filter 23.

  In summary, from the reactor containment vessel 1, the vent pipe 13, the filter container 16 (wet radioactive substance removing device), and the outlet pipe 20 are connected in order. The filter container 16 is disposed upstream of the connection portion of the return pipe 24 in the outlet pipe 20.

  The gas sent from the reactor containment vessel 1 to the filter vessel 16 via the vent pipe 13 contains an aerosol-like radioactive substance. Most of the radioactive radioactive material is removed when the gas passes through the filter container 16. The gas that has passed through the filter container 16 passes through the outlet pipe 20 and reaches the rare gas filter 23. Since the rare gas filter 23 transmits hydrogen and water vapor, the hydrogen and water vapor are discharged from the exhaust tower 22. On the other hand, since the radioactive rare gas and nitrogen and other gases do not pass through the rare gas filter 23, they are blocked and recirculate to the reactor containment vessel 1 through the return pipe 24.

  In the unlikely event that the pump 25 does not operate, the permeate flow rate of the rare gas filter 23 may decrease, and the depressurization of the reactor containment vessel 1 may be insufficient. Therefore, a bypass pipe 27 that bypasses the rare gas filter 23 from the upstream portion of the rare gas filter 23 and is connected to the downstream portion of the rare gas filter 23 is installed. Furthermore, on the line of the bypass pipe 27, by installing a rupture disc 28 that opens when the pressure exceeds a certain level, the partition plate is broken, so that the pump 25 does not operate, and the reactor containment vessel 1 When the pressure increases, the reactor containment vessel 1 can be depressurized by opening the rupture disk 28. The rupture disk 28 may be a blast valve or another valve. Further, this function may be replaced by making the rare gas filter 23 itself breakable at a certain pressure or higher.

  In other words, when the pressure exceeds a predetermined pressure, the upstream side of the noble gas filter 23 is destroyed by the destruction of the noble gas filter 23 itself or the rupture disk 28 (rupture valve) provided in the bypass pipe 27. This is a configuration that can reduce the pressure.

  FIG. 2 is a longitudinal sectional view showing a schematic configuration of the reactor containment vessel and its vent system according to the present embodiment.

  In the second embodiment, the basic arrangement and configuration of the filter vent device 15 and the rare gas filter 23 are the same as those in the first embodiment. For this reason, only the difference from the first embodiment will be described here.

  The second embodiment is different from the first embodiment in that a hydrogen recombiner 29 and a turbine 30 are provided in the filter vent device 15 as shown in FIG.

  The gas inside the reactor containment vessel 1 is replaced with nitrogen and almost no oxygen is present. Since the downstream portion from the rare gas filter 23 is connected to the outside through the exhaust tower 22, oxygen is present. Therefore, a hydrogen recombiner 29 is installed on the downstream side of the rare gas filter 23, and the hydrogen is treated by reacting the discharged hydrogen and oxygen into water. A hydrogen recombination catalyst is built in the hydrogen recombiner 29. By the action of this catalyst, hydrogen can be treated passively without using a power source or the like.

  The hydrogen recombination catalyst includes a catalyst in which palladium or platinum is impregnated on a carrier composed of a mixed oxide such as cerium oxide and zirconium oxide, or lithium, sodium, magnesium, calcium, iron, nickel, copper, There are metal oxide catalysts containing metals such as strontium, silver and cerium. This recombination reaction is an exothermic reaction, and the temperature of the exhaust gas rises as it passes through the hydrogen recombiner 29. This energy is recovered by the turbine 30 and the pump 25 is driven through the power transmission mechanism 31. This mechanism eliminates the need for a power supply for driving the pump 25.

  FIG. 3 is a longitudinal sectional view showing a schematic configuration of the reactor containment vessel and its vent system according to the present embodiment.

  In the third embodiment, only the configuration of the filter vent device 15 is changed from the first embodiment. For this reason, only the difference is demonstrated here.

  Generally, the filter vent device 15 includes a wet type and a dry type. As in the first embodiment, the scrubbing pool water 18 in the container removes the aerosol is a wet vent device.

  On the other hand, as shown in FIG. 3, the filter vent device 15 according to the third embodiment lays a sand filter 32 for removing a radioactive substance in a filter container 16 and removes the radioactive substance by the sand filter 32. It is a vent device. This is a dry-type vent device, and it is not necessary to manage the water quality of the scrubbing pool water 18 as compared with the wet type, but it is necessary to heat this device in the event of an accident.

  The vent pipe 13 is connected to the upper part of the filter container 16. A baffle plate 33 is provided between the vent pipe 13 and the top surface of the sand filter 32 so that the gas from the vent pipe 13 is uniformly supplied to the top surface of the sand filter 32. The outlet pipe 20 is connected to the lower part of the filter container 16.

  Since the radioactive noble gas cannot be removed even with the filter vent device 15, the noble gas filter 23 is necessary, and the configuration thereof is the same as that of the first embodiment. Moreover, you may combine with a hydrogen recombiner like Example 2. FIG.

  FIG. 4 is a longitudinal sectional view showing a schematic configuration of the reactor containment vessel and its vent system according to the present embodiment.

  In the fourth embodiment, only the configuration of the filter vent device 15 is changed from the third embodiment. For this reason, only the difference is demonstrated here.

  In the fourth embodiment, a metal filter 19 and a zeolite filter 34 for removing iodine are used in place of the sand filter 32 of the third embodiment. Example 4 is also a dry filter vent device.

  In this embodiment, as shown in FIG. 4, the metal filter 19 is provided at the upstream end of the vent pipe 13 (inside the dry well 5 and the wet well 7), and the zeolite filter 34 is placed in the middle of the vent pipe 13. Provided.

  Since the radioactive noble gas cannot be removed even if the metal filter 19 and the zeolite filter 34 are used, the noble gas filter 23 is provided as in the first embodiment. In addition, you may combine with a hydrogen recombiner like Example 2. FIG.

  FIG. 5 is a longitudinal sectional view showing a schematic configuration of the reactor containment vessel and its vent system according to the present embodiment.

  The present embodiment is an example in which the containment vessel vent system of the first embodiment is applied to a pressurized water reactor.

  As shown in this figure, in the case of a pressurized water reactor, a reactor pressure vessel 3 containing a reactor core 2, a pressurizer 35, a steam generator 36 and a recirculation pump 37 are installed inside the reactor containment vessel 1. Has been. The steam generator 36 is connected to a main steam pipe 4 that sends the generated steam to a turbine (not shown).

  The vent pipe 13 and the return pipe 24 are connected to the reactor containment vessel 1 that is not partitioned. That is, the pressurized water reactor does not have the wet well 7 and the suppression pool 8 for suppressing the pressure rise of the reactor containment vessel 1. For this reason, removal of radioactive material by scrubbing by the suppression pool 8 cannot be expected.

  Therefore, in this embodiment, the scrubbing function is provided by providing the filter container 16 as in the first embodiment.

  Note that the hydrogen recombiner 29 may be used as in the second embodiment. Further, as in Example 4 or 5, a dry-type filter vent device 15 may be used.

  Examples 1 to 5 are examples in which the reactor containment vent system of the present invention is applied to a light water reactor (boiling water reactor or pressurized water reactor), but applied to heavy water reactors, graphite reactors, gas reactors, and the like. May be. It is also applicable to reactors using other methods such as high-temperature gas reactors, so-called fourth-generation reactors, supercritical light water-cooled reactors, molten salt reactors, gas-cooled fast reactors, sodium-cooled fast reactors, and lead-cooled fast reactors. May be.

  1: Reactor containment vessel, 2: Core, 3: Reactor pressure vessel, 4: Main steam pipe, 5: Dry well, 6: Steam relief safety valve, 7: Wet well, 8: Suppression pool, 9: Steam relief safety valve Exhaust pipe, 10: quencher, 11: vent pipe, 11a: vent pipe exhaust part, 12: diaphragm floor, 13: vent pipe, 14, 14a, 14b: isolation valve, 15: filter vent device, 16: filter container, 17 : Inlet piping, 18: pool water for scrubbing, 19: metal filter, 20: outlet piping, 21: shielding wall, 22: exhaust tower, 23: noble gas filter, 24: return piping, 25: pump, 26: check Valve: 27: Bypass pipe, 28: Rupture disk, 29: Hydrogen recombiner, 30: Turbine, 31: Power transmission mechanism, 32: Sand filter, 33: Baffle plate, 34: Z Light filter 35: pressurizer 36: steam generator, 37: recirculating pump, 38: iodine filter.

Claims (14)

A vent line for discharging the gas inside the containment vessel to the outside of the containment vessel;
A rare gas filter provided in the vent line;
A return pipe connecting the upstream side of the rare gas filter and the containment vessel in the vent line;
A pump provided in the return pipe,
The reactor containment vessel vent system, wherein the rare gas filter is a membrane filter that blocks radioactive noble gases and allows water vapor to pass therethrough.   The reactor containment vessel vent system according to claim 1, wherein a wet type radioactive substance removing device is installed upstream of the connection portion of the return pipe in the vent line.   The reactor containment vessel vent system according to claim 1, wherein a dry type radioactive substance removing device is installed upstream of the connection portion of the return pipe in the vent line.   When the pressure exceeds a predetermined pressure, the rare gas filter itself is broken or the burst valve provided on the bypass pipe connecting the rare gas filter upstream side to the downstream side of the rare gas filter in the vent line is broken. The reactor containment vessel vent system according to any one of claims 1 to 3, which has a configuration capable of reducing a pressure upstream of the rare gas filter in the vent line.   The reactor containment vessel vent system according to any one of claims 1 to 4, wherein a hydrogen recombiner is installed downstream of the rare gas filter in the vent line. A turbine is installed downstream of the hydrogen recombiner in the vent line,
The reactor containment vent system according to claim 5, wherein the pump is driven by the turbine.   The reactor containment vessel vent system according to any one of claims 1 to 6, wherein the rare gas filter is a membrane filter that blocks radioactive rare gas and nitrogen and allows hydrogen and water vapor to pass therethrough.   The reactor containment vessel vent system according to any one of claims 1 to 7, wherein the membrane filter is formed of a polymer film, a ceramic film, or a graphene oxide film.   The reactor containment vessel vent system according to any one of claims 1 to 7, wherein the membrane filter is formed of a polymer film containing polyimide as a main component.   The reactor containment vessel vent system according to any one of claims 1 to 7, wherein the membrane filter is formed of a ceramic membrane mainly composed of silicon nitride.   The reactor containment vessel vent system according to claim 1, wherein the membrane filter is formed of a graphene oxide film containing carbon as a main component.   The reactor containment vessel vent system according to any one of claims 1 to 11, which is attached to a boiling water reactor.   The reactor containment vessel vent system according to any one of claims 1 to 11, which is attached to a pressurized water reactor.   It is attached to a heavy water reactor, a graphite furnace, a gas furnace, a high temperature gas furnace, a supercritical light water cooled reactor, a molten salt furnace, a gas cooled fast reactor, a sodium cooled fast reactor or a lead cooled fast reactor. The reactor containment vessel vent system according to any one of the preceding claims.

Images