JP2020041956A - Ventilation air conditioning system of nuclear power plant - Google Patents

Abstract

To provide a ventilation air conditioning system of a nuclear power plant capable of suppressing the intrusion of radioactive noble gas into a central control room or a room such as an apparatus room.SOLUTION: A ventilation air conditioning system 1 of a nuclear power plant includes: a first line 12 that communicates with an external environment and a room 101 and can take air from the external environment; a first air blower 14 that is installed on the first line 12 and supplies the air to the room 101; a first filter device 22 that is installed on the first line 12 and has a molecular sieve film having a characteristic in which xenon gas is hard to pass through it; a second line 35 whose one side is connected to the upstream side of the first filter device 22 in the first line 12 and the other side communicates with the external environment; and a second air blower 36 that is installed on the second line 35 and discharges the gas that cannot pass through the first filter device 22 to the external environment side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a ventilation and air conditioning system for a nuclear power plant, and more particularly, to a ventilation and air conditioning system capable of coping with a radioactive substance leakage accident in a nuclear power plant.

  A nuclear power plant has a central control room that controls and monitors the operation of a nuclear reactor or the like during normal operation or during an accident. Some nuclear plants have emergency response stations (sometimes referred to as important seismic isolation buildings) to handle work in the event of an accident. A ventilation and air conditioning system is connected to a living area where workers stay and work, such as a central control room and an emergency response center. The ventilation air-conditioning system is adapted to maintain the environment (temperature and humidity) of the living area appropriately by taking in outside air, supplying air to the living area, and discharging the air in the living area to the outside environment.

  The nuclear power plant also has an equipment room for housing various equipment such as a pump, a power supply panel, and a control panel. A ventilation air conditioning system is also connected to the equipment room. By using the ventilation air conditioning system, the indoor temperature is prevented from rising due to the heat generated by various devices, and the continuous operation of those devices is ensured.

  In a nuclear power plant, even if an accident occurs and the radioactivity concentration in the external environment increases, it is required to prevent exposure of workers in the living area. Therefore, the ventilation air-conditioning system is generally provided with a special filter (for example, a HEPA filter or a charcoal filter) capable of removing a radioactive substance that may be contained in the outside air at the time of an accident, thereby increasing the radioactivity in the external environment. When a (radioactive substance leakage accident) is detected, the air conditioning operation mode is switched from the normal ventilation mode to the emergency ventilation mode, and the external air taken in is passed through a special filter. The inflow is restricted (for example, see Patent Document 1).

  In the ventilation and air-conditioning equipment described in Patent Document 1, a special filter is installed on a line for supplying the taken outside air to a central control room, and radioactive iodine or radioactive or radioactive iodine which may be released to the external environment in the event of an accident. By removing cesium, etc. with a special filter, the amount of radioactive materials contained in the outside air supplied to the central control room is reduced as much as possible, while the entire central control room is made positive pressure to reduce the external environment to the central control room. Prevents radioactive material from entering the environment. However, since the radioactive rare gas which may be released to the external environment at the time of an accident has low reactivity, it is difficult to remove the radioactive rare gas with the special filter described in Patent Document 1. If the worker stays in the main control room at the time of the accident, the worker's exposure to radioactive rare gas may increase. Therefore, in the ventilation and air-conditioning system described in Patent Document 1, a central control room evacuation room is provided in a part of the central control room, and an oxygen cylinder capable of supplying oxygen at a higher pressure than the outside air is provided outside the central control room. I have. When radioactive rare gas flows into the main control room, the workers are evacuated to the main control room evacuation room, and oxygen necessary for the survival of the workers is supplied from the oxygen cylinder to the main control room evacuation room at high pressure. In this way, the radioactive rare gas is prevented from entering the evacuation room of the central control room, thereby reducing the exposure of workers.

JP-A-2017-32494

  However, when oxygen (air) is supplied from an oxygen cylinder without taking in outside air into a living area such as a central control room evacuation room at the time of a radioactive substance leakage accident, as in the ventilation air-conditioning system described in Patent Document 1, The number and time of people who can stay in the area are limited by the capacity and quantity of oxygen cylinders. Therefore, it is necessary to prepare an enormous number of oxygen cylinders in advance in order for a large number of workers to perform the work for the convergence of the accident for a long time. However, such provisions require a great deal of cost and a large installation space.

  Further, in the case where an evacuation room is provided in a part of the central control room as described in Patent Document 1, even if it is possible to provide a display device for displaying the state of the plant and an operation panel for controlling the plant in the evacuation room. However, it is difficult to secure a function completely equivalent to the function of the central control room in the evacuation room. Therefore, there is a possibility that the work performed by the worker who has evacuated to the evacuation room toward the convergence of the accident may be restricted.

  Therefore, there is a demand for suppressing the invasion of the radioactive rare gas into the central control room and the worker's exposure to the radioactive rare gas so that the operation for the convergence of the accident can be performed in the central control room.

  Also, for equipment housed in the equipment room (especially electronic equipment), use equipment with high radiation resistance in order to prevent malfunction or damage of the equipment due to radiation from radioactive material that has entered the equipment room. is there. In addition, by shielding the device, the influence of the radiation on the device may be reduced. However, these radiation countermeasures may increase costs. Therefore, there is a demand for suppressing the invasion itself of the radioactive rare gas into the equipment room to suppress the influence of radiation on the equipment.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a ventilation system for a nuclear power plant capable of suppressing the intrusion of a radioactive rare gas into a room such as a central control room or an equipment room. It is to provide an air conditioning system.

  The present application includes a plurality of means for solving the above-mentioned problems, for example, a ventilating air conditioning system connected to a room capable of housing workers or a room capable of housing equipment in a nuclear plant, to name one example, A first line that communicates with the external environment and the room and that can take in air from the external environment, a first blower that is installed on the first line and supplies air to the room, and that is installed on the first line; A first filter device provided with a molecular sieve membrane having a property that xenon gas is hardly permeated; and a second line connected to an upstream side of the first filter device in the first line on one side and communicating with an external environment on the other side. A second blower installed in the second line and discharging a gas that cannot pass through the first filter device to an external environment side.

According to the present invention, at least xenon gas among radioactive rare gases that may be contained in air taken into the ventilation air conditioning system in the event of a radioactive substance leaking into the external environment is collected by the molecular sieve membrane of the first filter device. Then, it is possible to discharge to the outside environment by the second blower through the second line, so that the invasion of the radioactive rare gas into the room can be suppressed.
Problems, configurations, and effects other than those described above will be apparent from the following description of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS It is a main system diagram which shows the ventilation air-conditioning system of the central control room as 1st Embodiment of the ventilation air-conditioning system of the nuclear power plant of this invention. It is explanatory drawing which shows the function at the time of the emergency operation mode in 1st Embodiment of the ventilation air conditioning system of the nuclear power plant of this invention shown in FIG. It is a main system diagram which shows the ventilation air-conditioning system of the central control room as 2nd Embodiment of the ventilation air-conditioning system of the nuclear power plant of this invention. It is a main system diagram which shows the ventilation air-conditioning system of the central control room as 3rd Embodiment of the ventilation air-conditioning system of the nuclear power plant of this invention. It is a main system diagram which shows the ventilation air-conditioning system of the central control room as 4th Embodiment of the ventilation air-conditioning system of the nuclear power plant of this invention. It is the schematic which shows the melt | dissolution separation apparatus which comprises a part of 4th Embodiment of the ventilation air-conditioning system of the nuclear plant of this invention. It is a main system figure which shows the ventilation air-conditioning system of the equipment room as 5th Embodiment of the ventilation air-conditioning system of the nuclear power plant of this invention.

Hereinafter, an embodiment of a ventilation and air conditioning system for a nuclear power plant according to the present invention will be described with reference to the drawings.
[First Embodiment]
First, a configuration of a ventilation and air conditioning system for a central control room as a first embodiment of a ventilation and air conditioning system for a nuclear power plant according to the present invention will be described with reference to FIG. FIG. 1 is a main system diagram showing a ventilation and air conditioning system for a central control room as a first embodiment of a ventilation and air conditioning system for a nuclear power plant according to the present invention.

  In FIG. 1, the nuclear power plant includes a central control room 101 for controlling and monitoring the operation of the plant. The main control room 101 is a place where workers are resident and operate and monitor the reactor and the like during normal operation, and perform safety measures and operation operations to converge the accident during an accident. In the main control room 101, it is required to ensure livability so that workers can perform various kinds of monitoring and operations as much as possible even when the surrounding external environment is severe at the time of the accident.

  The ventilation and air conditioning system 1 is connected to the main control room 101. The ventilation air-conditioning system 1 takes in the air (air) from the external environment and supplies it to the central control room 101, and discharges the air in the central control room 101 to the external environment. Humidity, oxygen concentration, etc.). If a radioactive substance leaks into the surrounding external environment due to an accident at a nuclear power plant, the radioactive substance may flow into the central control room 101 via the ventilation and air conditioning system 1. Therefore, the ventilation air conditioning system 1 includes both a system used in a normal operation mode during normal operation of a nuclear power plant and a system used in an emergency operation mode during an accident.

  In addition, as a radioactive substance that leaks into the air of the external environment and poses a problem, in addition to radioactive cesium and radioactive iodine, a radioactive rare gas mainly containing xenon and krypton is exemplified. The amount of radioactive cesium and radioactive iodine generated is particularly large. Among radioactive noble gases, xenon accounts for the majority and krypton tends to be small in quantity.

  The ventilation air-conditioning system 1 includes, as an air supply system, an outside air intake 11 for taking in air from an external environment, and an air supply line 12 connecting the outside air intake 11 and the central control room 101. The air supply line 12 communicates with the external environment and the central control room, and guides air taken in from the external environment via the external air intake 11 to the central control room 101. The air supply line 12 is provided with a radiation detector 13 and a first blower 14 in order from the upstream side. The radiation detector 13 detects leakage of a radioactive substance to the external environment. The radiation detector 13 is connected to, for example, a control device (not shown), and outputs a detection signal to the control device. The first blower 14 forcibly supplies air to the central control room 101, and is controlled by, for example, a control device (not shown).

  The air supply line 12 has a first air supply line 16 and a second air supply line 17 connected in parallel between the radiation detector 13 and the first blower 14. The first air supply line 16 is a system used in the normal operation mode, and is a line through which air taken in from the external environment flows during the normal operation. On the other hand, the second air supply line 17 is a system used in the emergency operation mode, and is a line through which air taken in from the external environment flows in an emergency such as a radioactive substance leakage accident.

  A switching valve 18 is provided at an upstream connection portion between the first air supply line 16 and the second air supply line 17. The switching valve 18 allows the intake air to flow through one of the first air supply line 16 and the second air supply line 17, and is, for example, a three-way valve. The switching valve 18 is switched so that the intake air flows through the first air supply line 16 in the normal operation mode, and flows through the second air supply line 17 in the emergency operation mode.

  In the second air supply line 17, a pre-stage filter device 21, a post-stage filter device 22, and a hold-up device 23 are installed in order from the upstream side. The second air supply line 17 is a line for removing radioactive substances contained in the air taken in by these devices 21, 22 and 23.

  The pre-filter device 21 is configured to collect particulate radioactive substances and radioactive iodine containing radioactive cesium. The first-stage filter device 21 includes, for example, a filter (for example, a charcoal filter) using a material having a large number of pores on the surface such as activated carbon or zeolite, and a HEPA filter. However, it is difficult for the pre-stage filter device 21 to remove a radioactive rare gas that may be contained in the taken air.

  The latter-stage filter device 22 has a network structure at a molecular level, and includes a molecular sieve film that selectively allows a specific gas to pass through utilizing a difference in molecular diameter between various gases. For example, the molecular sieve film of the post-filter device 22 is less permeable to xenon gas (for example, having a molecular diameter of about 0.396 nm) among radioactive rare gases, and is permeable to oxygen gas (for example, having a molecular diameter of about 0.346 nm). It has easy-to-use characteristics. As the molecular sieve film of the latter-stage filter device 22, a polymer film formed of a material mainly containing polyimide, a ceramic film formed of a material mainly containing silicon nitride, and a film formed of a material mainly containing carbon are used. It is preferable to use any of the three types of graphene oxide films. A molecular sieve film using a graphene oxide film has a feature that the performance of separating xenon gas from air is the highest among the above three types of films. The molecular sieving membrane using a polymer membrane is characterized by a relatively high performance of separating xenon gas from air and a high permeability of water vapor (a component to be supplied to the central control chamber 101) contained in air. is there. A molecular sieve film using a ceramic film is characterized by having high strength and high heat resistance. Note that, among the radioactive rare gases, krypton gas has a molecular diameter (for example, about 0.360 nm) smaller than the molecular diameter of xenon gas and is close to the molecular diameter of oxygen gas. It tends to be easily transmitted.

  The hold-up device 23 is, for example, a device in which a large amount of an adsorbent such as activated carbon is contained in a container such as a tank or a tower. It is configured to physically adsorb by the adsorbent. In the hold-up device 23, while the oxygen gas easily passes through the container containing the adsorbent, the time in which the radioactive rare gas stays in the container by repeating physical adsorption and desorption with respect to the adsorbent is shorter than the oxygen gas. And the radioactivity of the radioactive noble gas is attenuated as a result. In the hold-up device 23, the duration in which the radioactive rare gas can be held is limited according to the amount of the adsorbent to be stored.

  The ventilation air conditioning system 1 includes, as an exhaust system, an exhaust port 31 for discharging air in the central control room 101 to an external environment, and an exhaust line 32 connecting the exhaust port 31 and the central control room 101. . The exhaust line 32 guides the air in the central control room 101 to the exhaust port 31. The exhaust line 32 is provided with a first check valve 33 for preventing a reverse flow of air from the exhaust port 31 side to the central control chamber 101 side.

  The ventilation air conditioning system 1 includes an emergency exhaust line 35 as an exhaust system used in the emergency operation mode. One side of the emergency exhaust line 35 is connected to a portion of the second air supply line 17 downstream of the upstream filter device 21 and upstream of the downstream filter device 22 (a portion between the upstream filter device 21 and the downstream filter device 22). The other side is connected to a portion of the exhaust line 32 downstream of the first check valve 33 and communicates with the external environment. The emergency exhaust line 35 guides a gas that cannot pass through the post-stage filter device 22, in particular, a xenon gas among radioactive rare gases, to the exhaust line 32. A second blower 36 is installed in the emergency exhaust line 35. The second blower 36 is for forcibly discharging gas that cannot pass through the rear-stage filter device 22 to the external environment through the emergency exhaust line 35 and the exhaust line 32.

  Further, the ventilation and air conditioning system 1 includes a recirculation line 41 that supplies the air in the central control room 101 to the central control room 101 again without discharging the air to the external environment. The recirculation line 41 has, for example, one side connected to a portion of the exhaust line 32 upstream of the first check valve 33 and the other side of the air supply line 12 upstream of the first blower 14 ( The second air supply line 17 is connected to a portion downstream of the hold-up device 23).

  In the recirculation line 41, a third blower 42, a carbon dioxide removing device 43, and a second check valve 44 are provided in this order from the upstream side. The third blower 42 forcibly sends out the air in the central control room 101 to the air supply line 12 via the recirculation line 41. The carbon dioxide removing device 43 removes carbon dioxide contained in the air flowing through the recirculation line 41. The carbon dioxide removing device 43 includes, for example, a container that stores an aqueous solution such as water capable of dissolving carbon dioxide, and introduces (blows) air containing carbon dioxide into the aqueous solution to convert the carbon dioxide into an aqueous solution. It is configured to dissolve in and separate from air. The second check valve 44 prevents the backflow of the air sent out to the air supply line 12 side via the recirculation line 41, and also prevents the air from flowing out from the first air supply line 16 or the second air supply line 17 to the recirculation line 41. Through the exhaust line 32.

  Next, the function of the first embodiment of the ventilation and air conditioning system for a nuclear power plant according to the present invention will be described with reference to FIGS. FIG. 2 is an explanatory diagram showing functions in the emergency operation mode in the first embodiment of the ventilation and air conditioning system for a nuclear power plant according to the present invention shown in FIG. 1 and 2, white arrows indicate the flow of air.

  The ventilation air conditioning system 1 operates in a normal operation mode during a normal operation of a nuclear power plant. Specifically, the switching valve 18 of the air supply system is switched so that the first air supply line 16 communicates with the outside air intake 11 as shown in FIG. When the first blower 14 is driven, air is taken in from the external environment via the outside air intake 11. The taken-in air is forcibly supplied to the central control room 101 via the air supply line 12 passing through the first air supply line 16 without passing through the second air supply line 17 (see the white arrow in FIG. 1). reference). Further, the pressure in the central control room 101 is increased by forcibly supplying the outside air to the central control room 101, and the air in the central control room 101 is discharged from the exhaust port 31 to the external environment through the exhaust line 32. (See the white arrow in FIG. 1). At this time, the first check valve 33 prevents the air flowing through the exhaust line 32 from flowing back to the central control chamber 101, and the second check valve 44 recirculates the air flowing through the air supply line 12. Outflow to the exhaust line 32 via 41 is prevented. Thereby, in the central control room 101, the livability that the worker can work is secured.

  If an accident occurs in a nuclear power plant and radioactive material leaks into the surrounding external environment and flows into the ventilation and air conditioning system 1, the radiation detector 13 detects radiation from the radioactive material. In this case, the ventilation air conditioning system 1 switches from the normal operation mode to the emergency operation mode. Specifically, the switching valve 18 is switched so that the second air supply line 17 communicates with the outside air intake 11 as shown in FIG. Further, the second blower 36 and the third blower 42 are driven.

  The air in the external environment is taken in from the outside air intake 11, flows through the second air supply line 17, and passes through the pre-filter device 21 (see the white arrow in FIG. 2). The pre-filter device 21 captures a particulate radioactive substance such as radioactive cesium and radioactive iodine contained in the taken-in air. However, in the pre-stage filter device 21, the radioactive rare gas contained in the taken-in air passes without being collected.

  The air that has passed through the first-stage filter device 21 passes through the second-stage filter device 22 downstream of the first-stage filter device 21 (see the white arrow in FIG. 2). In the molecular sieving membrane of the second-stage filter device 22, most of the xenon gas of the radioactive rare gas not removed by the first-stage filter device 21 is blocked and trapped, while air such as oxygen gas molecules and water vapor molecules is collected. Component is transmitted. In addition, krypton gas among the radioactive rare gases not removed by the first-stage filter device 21 has a molecular diameter close to the molecular size of oxygen gas molecules, so that the molecular sieving film of the second-stage filter device 22 together with air containing oxygen gas molecules is used. Tends to penetrate.

  The gas containing radioactive xenon gas that cannot pass through the molecular sieve membrane of the downstream filter device 22 is forcibly discharged to the external environment through the emergency exhaust line 35 and the exhaust line 32 by the second blower 36. Therefore, invasion of the radioactive xenon gas into the central control room 101 through the air supply line 12 can be suppressed.

  On the other hand, the air that has passed through the downstream filter device 22 flows into the hold-up device 23 (see the white arrow in FIG. 2). The radioactive rare gas krypton gas contained in the air stays in the hold-up device 23 for a long time by repeatedly adsorbing and desorbing the adsorbent when passing through the hold-up device 23. As a result, the amount of the radioactive rare gas contained in the air passing through the hold-up device 23 is reduced, and the radioactivity of the radioactive rare gas is attenuated.

  Air having a significantly reduced radioactivity level after passing through the three devices of the pre-filter device 21, the post-filter device 22, and the hold-up device 23 is supplied to the central control room 101 via the air supply line 12 (FIG. 2 (see white arrow). Therefore, it is possible to reduce the exposure of the worker staying in the central control room 101 due to the radioactive substance. The amount of radioactive krypton gas generated in the nuclear power plant is small compared to the amount of radioactive xenon gas generated, and the radioactive krypton gas which may be contained in the air passing through the hold-up device 23 is transmitted to the human body or equipment. The effect of radiation is extremely small compared to radioactive xenon gas.

  The air in the central control room 101 is discharged from the exhaust port 31 to the external environment via the exhaust line 32 as in the normal operation mode. At this time, the first check valve 33 prevents outside air containing a radioactive substance from entering the central control room 101 from the exhaust port 31 via the exhaust line 32.

  A part of the air discharged from the central control room 101 to the exhaust line 32 is re-supplied to the central control room 101 via the recirculation line 41 by driving the third blower 42. The air flowing through the recirculation line 41 has a part of carbon dioxide removed by the carbon dioxide removing device 43 and the concentration of carbon dioxide is reduced. Air having a reduced carbon dioxide concentration is supplied to the central control room 101 via the recirculation line 41.

  As described above, in the present embodiment, the air taken in from the external environment when the radioactive substance leaks into the external environment is passed through the pre-filter device 21, the post-filter device 22, and the hold-up device 23, so that the air The air containing oxygen gas and water vapor is supplied to the central control chamber 101 while collecting or retaining radioactive substances contained in the air. Further, a part of the air in the central control room 101 in which the carbon dioxide concentration is increased is exhausted from the exhaust line 32 to the external environment, and is also processed by the carbon dioxide removing device 43 and is again centrally controlled through the recirculation line 41. It is supplied to the chamber 101. Thereby, the radioactivity level and the carbon dioxide concentration of the air in the central control room 101 can be kept low, so that it is possible to secure the livability in which the workers can work efficiently.

  Further, in the present embodiment, xenon gas, which accounts for a large part of the amount of generated radioactive rare gas, is collected by the molecular sieve film of the post-filter device 22. Therefore, the hold-up device 23 only needs to mainly process radioactive krypton, and the amount of processing of the radioactive rare gas in the hold-up device 23 can be reduced. Therefore, the amount of the adsorbent for adsorbing the radioactive rare gas is reduced by that much, and the size of the hold-up device 23 can be avoided.

  According to the above-described first embodiment of the ventilation and air conditioning system for a nuclear power plant of the present invention, a radioactive rare gas that may be contained in air taken into the ventilation and air conditioning system 1 in the event of a radioactive substance leaking into the external environment Xenon gas can be collected by the molecular sieve film of the post-filter device 22 and discharged to the external environment by the second blower 36 through the emergency exhaust line 35. Intrusion into the vehicle can be suppressed. As a result, exposure of the workers staying in the central control room 101 due to the radioactive rare gas can be reduced, so that restrictions on the number of persons who can respond to an accident, time, means, and the like are eliminated, and plant safety is improved.

  Further, according to the present embodiment, since the molecular sieve film of the post-stage filter device 22 has a characteristic that oxygen gas easily permeates, the air that has passed through the post-stage filter device 22 is supplied to the central control chamber 101. Thus, a worker staying in the main control room 101 can secure necessary oxygen.

  Further, according to the present embodiment, by using a polymer film containing polyimide as a main component as the molecular sieve film of the post-stage filter device 22, the post-stage filter device 22 has high separation performance of xenon gas with respect to air and water vapor. High transmission performance can be obtained.

  Further, according to the present embodiment, by using a ceramic film containing silicon nitride as a main component as the molecular sieve film of the subsequent filter device 22, the latter filter device 22 can obtain high strength and heat resistance.

  Further, according to the present embodiment, by using a graphene oxide film containing carbon as a main component as the molecular sieve film of the post-stage filter device 22, the post-stage filter device 22 has a particularly excellent separation performance of xenon gas with respect to air. Obtainable.

  Further, according to the present embodiment, since the hold-up device 23 is provided downstream of the post-filter device 22, the krypton gas of the radioactive rare gas that has passed through the molecular sieve membrane of the post-filter device 22 is physically adsorbed by the adsorbent. As a result, it can be held in the hold-up device 23 for a long time. As a result, the amount of radioactive krypton gas contained in the air that has passed through the hold-up device 23 decreases, and the radioactivity of the radioactive krypton gas is attenuated. Can be further suppressed. Therefore, the exposure of the worker staying in the central control room 101 by the radioactive rare gas is further reduced.

  Further, according to the present embodiment, the first-stage filter device 21 that can capture the particulate radioactive substance such as radioactive cesium and the radioactive iodine is installed on the upstream side of the second-stage filter device 22, so that the second-stage filter device 22 There is no need to collect the radioactive substance and radioactive iodine in the shape, and the structure of the subsequent-stage filter device 22 can be simplified.

  Further, according to the present embodiment, since the carbon dioxide removal device 43 is installed in the recirculation line 41 that supplies the air in the central control room 101 to the central control room 101 again, the livability of the central control room 101 is improved. In the emergency operation mode, the flow rate of the air taken in from the external environment can be reduced by the flow rate recirculated to the central control room 101. Accordingly, the processing flow rates of the first-stage filter device 21, the second-stage filter device 22, and the hold-up device 23 can be reduced, and accordingly, the first-stage filter device 21, the second-stage filter device 22, and the hold-up device 23 can be reduced in size. .

[Second embodiment]
Next, a configuration of a ventilation and air conditioning system for a central control room as a second embodiment of the ventilation and air conditioning system for a nuclear power plant according to the present invention will be described with reference to FIG. FIG. 3 is a main system diagram showing a ventilation and air conditioning system for a central control room as a second embodiment of the ventilation and air conditioning system for a nuclear power plant according to the present invention. In FIG. 3, arrows indicate the flow of air. In FIG. 3, the same reference numerals as those shown in FIGS. 1 and 2 denote the same parts, and a detailed description thereof will be omitted.

  The difference between the second embodiment of the ventilation and air conditioning system for a nuclear power plant of the present invention shown in FIG. 3 and the first embodiment is that the hold-up device 23 of the first embodiment (see FIG. 2). Instead, an ionized rare gas removal device 25 is provided on the second air supply line 17 downstream of the downstream filter device 22. Other configurations in the second embodiment are the same as those in the first embodiment.

  The ionized rare gas removal device 25 of the ventilation air conditioning system 1A ionizes the radioactive rare gas (especially, krypton gas that tends to pass through the post-filter device 22) contained in the air that has passed through the post-filter device 22, The apparatus is configured to generate a rare gas compound from an ionized radioactive rare gas by a chemical reaction with an active element and to chemically adsorb the generated rare gas compound with an adsorbent, thereby collecting the radioactive rare gas. Noble gases are generally inert. However, by applying a high voltage to a rare gas other than helium such as xenon or krypton by discharging or the like, the radioactive rare gas can be ionized. A rare gas compound can be generated by chemically reacting the ionized rare gas with an active element. For example, by reacting an ionized rare gas with fluorine, fluoride of the rare gas is generated. The rare gas fluoride can be collected by chemical adsorption using an adsorbent. Chemisorption by electron bonding has a higher adsorption force than physical adsorption by van der Waals force. Therefore, the ionized rare gas removal device 25 can be downsized compared to a hold-up device that physically absorbs a radioactive rare gas.

  In the present embodiment, since the xenon gas occupying most of the generated amount of the radioactive rare gas is collected by the post-stage filter device 22, the amount of the radioactive rare gas to be processed in the ionized rare gas removal device 25 can be reduced. . Therefore, the amount of the adsorbent for chemically adsorbing the radioactive rare gas can be reduced correspondingly, so that the ionized rare gas removing device 25 can be prevented from being enlarged.

  According to the above-described second embodiment of the ventilation and air conditioning system for a nuclear power plant of the present invention, as in the first embodiment, xenon gas of radioactive rare gas is captured by the molecular sieve film of the post-filter device 22. Since it can be collected and discharged to the outside environment, the invasion of the radioactive rare gas into the central control room 101 can be suppressed.

  Further, according to the present embodiment, since the ionized rare gas removal device 25 is provided downstream of the post-filter device 22, the krypton gas, which is a radioactive rare gas that has passed through the molecular sieve membrane of the post-filter device 22, is converted into a rare gas. The compound can be chemically adsorbed by the adsorbent and kept in the ionized rare gas removing device 25 for a long time. As a result, the amount of radioactive krypton gas contained in the air that has passed through the ionized rare gas removal device 25 decreases, and the radioactivity of the radioactive krypton gas is attenuated. Intrusion can be further suppressed. Therefore, the exposure of the worker staying in the central control room 101 by the radioactive rare gas is further reduced.

[Third Embodiment]
Next, a configuration of a ventilation and air conditioning system for a central control room as a third embodiment of the ventilation and air conditioning system for a nuclear power plant according to the present invention will be described with reference to FIG. FIG. 4 is a main system diagram showing a ventilation and air conditioning system for a central control room as a third embodiment of the ventilation and air conditioning system for a nuclear power plant according to the present invention. In FIG. 4, arrows indicate the flow of air. In FIG. 4, the same reference numerals as those shown in FIGS. 1 to 3 denote the same parts, and a detailed description thereof will be omitted.

  The difference between the third embodiment of the ventilation and air conditioning system for a nuclear power plant of the present invention shown in FIG. 4 and the first embodiment is that the hold-up device 23 of the first embodiment (see FIG. 2). Instead, an oxygen ion permeation device 26 installed downstream of the post-stage filter device 22 in the second air supply line 17 is provided. Other configurations in the third embodiment are the same as those in the first embodiment.

  The oxygen ion permeable device 26 of the ventilation air conditioning system 1B includes an ion-conductive oxygen separation membrane through which oxygen ions can pass, and the oxygen separation membrane separates a part of oxygen gas contained in air from air. It is configured as follows. The oxygen ion permeation device 26 includes, for example, a ceramic solid electrolyte used in a fuel cell as an oxygen separation membrane.

  In the oxygen ion permeation device 26, when air that has passed through the molecular sieving membrane of the post-filter device 22 flows into one side of the oxygen separation membrane, oxygen gas molecules contained in the air become electrons on the surface of the oxygen separation membrane. Is received and ionized, and oxygen ions move in the oxygen separation membrane and emit electrons on the other surface of the oxygen separation membrane, so that oxygen gas molecules are formed again. As a result, air having a low oxygen concentration containing a radioactive rare gas (particularly radioactive krypton gas which tends to permeate the post-stage filter device 22) remains on one side of the oxygen separation membrane, and on the other side of the oxygen separation membrane. High oxygen concentration air separated from the radioactive rare gas can be obtained. The high oxygen concentration air obtained by the oxygen ion permeation device 26 is supplied to the central control room 101, while the low oxygen concentration air containing the radioactive rare gas is supplied to the outside via the emergency exhaust line 35 and the exhaust line 32. It can be released to the environment.

  The oxygen ion permeable device 26 separates the oxygen gas from the air containing the radioactive rare gas by the oxygen separation membrane through which the oxygen ions can pass. The function of the permeation device 26 for separating oxygen gas and radioactive rare gas is maintained. On the other hand, in the hold-up device 23 of the first embodiment, when the adsorbent reaches the breakthrough of the adsorption, the adsorption of the radioactive rare gas cannot be expected. That is, the duration during which the hold-up device 23 functions is limited by the capacity of the adsorbent. In the case of the ionized rare gas removing device 25 of the second embodiment, similarly to the hold-up device 23 of the first embodiment, when the adsorbent reaches the breakthrough of the adsorption, the chemical adsorption of the rare gas compound is started. I can't hope. That is, the duration during which the ionized rare gas removal device 25 functions is limited by the capacity of the adsorbent.

  According to the above-described third embodiment of the ventilation and air conditioning system for a nuclear power plant of the present invention, as in the first embodiment, xenon gas of radioactive rare gas is captured by the molecular sieve film of the post-filter device 22. Since it can be collected and discharged to the outside environment, the invasion of the radioactive rare gas into the central control room 101 can be suppressed.

  In addition, according to the present embodiment, since the oxygen ion permeable device 26 is installed downstream of the post-filter device 22, the oxygen-containing radioactive gas that has passed through the molecular sieve membrane of the post-filter device 22 contains krypton gas, which is a radioactive rare gas. The gas can be separated. By supplying the oxygen gas separated from the radioactive krypton gas by the oxygen ion permeation device 26 to the central control room 101, the invasion of the radioactive rare gas into the central control room 101 can be further suppressed. Therefore, the exposure of the worker staying in the central control room 101 by the radioactive rare gas is further reduced.

[Fourth Embodiment]
Next, a configuration of a ventilation and air conditioning system for a central control room as a fourth embodiment of the ventilation and air conditioning system for a nuclear power plant according to the present invention will be described with reference to FIGS. FIG. 5 is a main system diagram showing a ventilation and air conditioning system for a central control room as a fourth embodiment of the ventilation and air conditioning system for a nuclear power plant according to the present invention, and FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the dissolution separation apparatus which comprises a part of embodiment. 5 and 6, arrows indicate the flow of air. 5 and 6, the same reference numerals as those shown in FIGS. 1 to 4 denote the same parts, and a detailed description thereof will be omitted.

  The fourth embodiment of the ventilation and air conditioning system for a nuclear power plant according to the present invention shown in FIG. 5 is different from the first embodiment in that the hold-up device 23 (see FIG. 2) of the first embodiment is different. Instead, a dissolution / separation device 27 is provided in the second air supply line 17 on the downstream side of the downstream filter device 22. Other configurations in the fourth embodiment are the same as those in the first embodiment.

  The dissolution / separation device 27 of the ventilation air-conditioning system 1 </ b> C introduces the radioactive rare gas contained in the air by introducing the air that has passed through the post-filter device 22 into the solvent (particularly radioactive krypton that tends to pass through the post-filter device 22). Gas) is dissolved in a solvent to separate and remove the radioactive rare gas from air. The dissolution / separation device 27 separates a rare gas from air using, for example, a difference in solubility between oxygen gas and a rare gas in water. As shown in FIG. 6, for example, the dissolution / separation device 27 includes a container 27a that stores a solvent S such as water in which a rare gas is more easily dissolved than an oxygen gas, and air that has passed through the molecular sieve membrane of the post-filter device 22. And a conduit 27b for introducing the solvent S in the solvent 27a. In the dissolution / separation device 27, when the air that has passed through the latter-stage filter device 22 is blown into the solvent S in the container 27a, the radioactive krypton gas contained in the air is dissolved in the solvent S and separated from the air. The air from which part of the radioactive krypton gas has been removed by the dissolution / separation device 27 is supplied to the central control room 101 as shown in FIG.

  In the present embodiment, the dissolution / separation device 27 is generally constituted by a container 27a for storing the solvent S and a conduit 27b for introducing air into the solvent S in the container 27a, Separation can be achieved with a simple configuration.

  Further, in the present embodiment, since the xenon gas occupying most of the generated amount in the radioactive rare gas is collected by the post-filter device 22, the processing amount of the radioactive rare gas in the dissolution / separation device 27 can be reduced. . Therefore, the amount of the solvent for dissolving the radioactive rare gas is reduced by that much, so that the dissolution / separation device 27 can be downsized.

  According to the above-described fourth embodiment of the ventilation and air conditioning system for a nuclear power plant of the present invention, as in the first embodiment, xenon gas among radioactive rare gases is captured by the molecular sieve film of the downstream filter device 22. Since it can be collected and discharged to the outside environment, the invasion of the radioactive rare gas into the central control room 101 can be suppressed.

  Further, according to the present embodiment, since the dissolution / separation device 27 is provided downstream of the post-filter device 22, the radioactive krypton gas contained in the air that has passed through the molecular sieve membrane of the post-filter device 22 is converted into the solvent S (for example, , Water) and separated from air. Therefore, by supplying the central control room 101 with air in which a part of the radioactive krypton gas has been separated by the dissolution / separation device 27, the invasion of the radioactive rare gas into the central control room 101 can be further suppressed. Therefore, the exposure of the worker staying in the central control room 101 by the radioactive rare gas is further reduced.

[Fifth Embodiment]
Next, a configuration of a ventilation air conditioning system for an equipment room as a fifth embodiment of the ventilation air conditioning system for a nuclear power plant according to the present invention will be described with reference to FIG. FIG. 7 is a main system diagram showing a ventilation air conditioning system for an equipment room as a fifth embodiment of the ventilation air conditioning system for a nuclear power plant according to the present invention. In FIG. 7, the same reference numerals as those shown in FIGS. 1 to 6 denote the same parts, and a detailed description thereof will be omitted.

  In a fifth embodiment of the ventilation and air conditioning system for a nuclear power plant according to the present invention shown in FIG. 7, the ventilation and air conditioning systems 1, 1A, 1B, and 1C according to the first to fourth embodiments have a central location where workers stay. In contrast to the one connected to the control room 101, the other is connected to a device room 102 in which various devices are accommodated. The equipment room 102 houses various equipment such as electronic equipment, a power board, and a pump. In the equipment room 102, there is a possibility that the temperature of the room rises due to the heat generated by the equipment and the functions of the equipment are lost. By supplying air in the external environment to the equipment room 102, the temperature inside the equipment room 102 is prevented from rising. When a radioactive rare gas enters the equipment room 102 from the external environment, the radiation dose in the equipment room 102 increases, and there is a risk of malfunction or damage to the equipment.

  The ventilation air conditioning system 1D according to the present embodiment shown in FIG. 6 is different from the ventilation air conditioning systems 1, 1A, 1B, 1C according to the first to fourth embodiments in the following three points. First, the characteristics of the molecular sieving film of the latter-stage filter device 22D are different. Second, a recirculation line 41 for supplying the air in the equipment room 102 (the central control room 101) to the equipment room 102 (the central control room 101) again, a third blower 42, a carbon dioxide removal device 43, a second The configuration of the check valve 44 (see FIGS. 1 to 5) is omitted. Third, a device for treating a radioactive rare gas provided downstream of the post-filter device 22D, specifically, a hold-up device 23 (see FIG. 2) and an ionized rare gas removal device 25 (see FIG. 3) ), The oxygen ion permeation device 26 (see FIG. 4), or the dissolution / separation device 27 (see FIG. 5) is omitted.

  The equipment in the equipment room 102 does not need oxygen, unlike the worker staying in the central control room 101, so that there is no need to supply oxygen gas to the equipment room 102. Therefore, the molecular sieve film of the subsequent filter device 22D according to the present embodiment does not need to have oxygen gas permeability. Therefore, a film having a characteristic that krypton gas having a molecular diameter relatively close to the molecular diameter of oxygen gas is hardly permeated is used as the molecular sieve film of the subsequent filter device 22D. Since the molecular sieve film of the latter filter device 22D can also collect krypton gas in addition to the xenon gas of the radioactive rare gas, almost no radioactive substance is contained in the air that has passed through the latter filter device 22D. A device for processing radioactive materials downstream of the device 22D is not required.

  According to the above-described fifth embodiment of the ventilation and air conditioning system for a nuclear power plant of the present invention, a radioactive rare gas that may be contained in air taken into the ventilation and air conditioning system 1D in the event of a radioactive substance leaking into the external environment Among them, xenon gas and krypton gas can be collected by the molecular sieve film of the downstream filter device 22D and discharged to the outside environment by the second blower 36 through the emergency exhaust line 35, so that the equipment room of the radioactive rare gas The intrusion into the inside 102 can be suppressed. As a result, the effect of radiation on the equipment housed in the equipment room 102 can be reduced, so that radiation measures for the equipment are not required, and an increase in cost can be prevented.

  Further, according to the present embodiment, the molecular sieve film of the subsequent filter device 22D has a characteristic that krypton gas having a smaller molecular diameter than xenon gas is hardly permeated, so that the radioactive rare gases xenon gas and krypton are used. Gases can be reliably prevented from entering both the equipment rooms 102. Therefore, it is not necessary to provide a device for treating the radioactive rare gas downstream of the downstream filter device 22D, and it is possible to suppress the invasion of the radioactive rare gas xenon gas and the krypton gas into the equipment room 102 by a simple configuration. be able to.

  As described above, according to the first to fifth embodiments of the ventilation / air-conditioning system for a nuclear power plant of the present invention, the ventilation / air-conditioning system 1, 1A, 1B, 1C, 1D is used in the event of a radioactive substance leaking to the external environment. At least xenon gas of the radioactive rare gas possibly contained in the air taken into the air is collected by the molecular sieve membranes of the subsequent filter devices (first filter devices) 22 and 22D, and the emergency exhaust line (second line) Since it is possible to discharge to the external environment by the second blower 36 via 35, the invasion of the radioactive rare gas into the central control room (room) 101 or the equipment room (room) 102 can be suppressed.

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

  For example, the above-described first to fourth embodiments of the ventilation and air conditioning system for a nuclear power plant according to the present invention are applied to the ventilation and air conditioning system for the central control room 101. However, the ventilation and air conditioning system for a nuclear power plant according to the present invention can also be applied to a ventilation and air conditioning system connected to a room where an operator stays, such as an emergency response office.

  In the first to fifth embodiments of the ventilation and air-conditioning system for a nuclear power plant of the present invention described above, an example of the configuration in which the upstream filter device 21 is provided on the upstream side of the downstream filter devices 22 and 22D has been described. A configuration in which the pre-filter device 21 is omitted is also possible. Since the latter-stage filter devices 22 and 22D are provided with a molecular sieve film having a property that at least xenon gas is hardly permeated among radioactive rare gases, the latter-stage filter devices 22 and 22D are equivalent to xenon gas even without the former-stage filter device 21. The intrusion of the radioactive iodine element and the radioactive cesium having the above molecular diameters into the central control room 101 or the equipment room 102 can be suppressed. However, in this case, since the latter-stage filter devices 22 and 22D collect the radioactive iodine element and radioactive cesium in addition to the xenon gas, the throughput of the radioactive substance of the molecular sieve film increases accordingly.

  In the first to fourth embodiments of the ventilation and air conditioning system for a nuclear power plant according to the present invention described above, the hold-up device 23, the ionized rare gas removal device 25, the oxygen ion permeation device is provided downstream of the post-filter device 22. Although an example of a configuration including any one of the dissolution / separation device 26 and the dissolution / separation device 27 has been described, a configuration in which these devices 23, 25, 26, and 27 downstream of the downstream filter device 22 are omitted is also possible. Of the radioactive noble gases that may leak to the external environment during a nuclear plant accident, the amount of krypton gas generated is small compared to xenon gas, and the effects of radioactive krypton gas on human bodies and equipment due to radioactive xenon Small compared to gas. Since radioactive xenon gas, which has a large effect of radiation on the human body and the equipment, is collected by the post-filter device 22, even if the radioactive krypton gas passes through the post-filter device 22 and flows into the central control room 101, the radioactive xenon gas will not The effect of radiation can be kept low.

  In the above-described first to fourth embodiments of the ventilation and air conditioning system for a nuclear power plant according to the present invention, the recirculation line 41 for supplying the air in the central control room 101 to the central control room 101 again, Although an example of the configuration including the three blowers 42, the carbon dioxide removal device 43, and the second check valve 44 has been described, a configuration in which these devices 41, 42, 43, and 44 are omitted may be possible. However, in this case, in order to secure the livability of the central control room 101, it is necessary to increase the flow rate of the outside air supplied to the central control room 101. An increase in the flow rate of the outside air to be taken increases the flow rate to be processed by the pre-stage filter device 21 or the post-stage filter device 22 or the like.

  1, 1A, 1B, 1C, 1D: ventilation air conditioning system, 12: air supply line (first line), 14: first air blower, 17: second air supply line (first line), 21: pre-stage filter device ( 22, 22D: Post-filter device (first filter device), 23: Hold-up device, 25: Ionized rare gas removal device, 26: Oxygen ion permeation device, 27: Dissolution separation device, 35: Emergency Exhaust line (second line), 36: second blower, 41: recirculation line, 43: carbon dioxide removal device, 101: central control room (room), 102: equipment room (room)

Claims (13)

A ventilation and air conditioning system connected to a room in which a worker can stay or a room in which equipment can be housed in a nuclear power plant,
A first line communicating with the external environment and the room and capable of taking air from the external environment;
A first blower installed in the first line and supplying air to the room;
A first filter device that is provided on the first line and includes a molecular sieve membrane having characteristics that xenon gas is difficult to permeate;
A second line having one side connected to the first line upstream of the first filter device and the other side communicating with an external environment;
A second blower installed in the second line and configured to discharge a gas that cannot pass through the first filter device to an external environment side. The ventilation and air conditioning system according to claim 1,
The molecular sieve membrane of the first filter device has a property that oxygen gas easily permeates. The ventilation and air conditioning system according to claim 1,
The molecular sieve membrane of the first filter device has a characteristic that krypton gas is hardly permeated. The ventilation and air conditioning system according to claim 1,
The ventilation and air conditioning system, wherein the molecular sieve film of the first filter device is any one of a ceramic film, a polymer film, and a graphene oxide film. The ventilation and air conditioning system according to claim 4,
The ventilation and air conditioning system according to claim 1, wherein the molecular sieve film of the first filter device is a ceramic film containing silicon nitride as a main component. The ventilation and air conditioning system according to claim 4,
The ventilation and air conditioning system according to claim 1, wherein the molecular sieve film of the first filter device is a polymer film containing polyimide as a main component. The ventilation and air conditioning system according to claim 4,
The molecular sieve film of the first filter device is a graphene oxide film containing carbon as a main component. The ventilation and air conditioning system according to claim 1,
The apparatus further includes a second filter device installed upstream of a connection portion of the first line with the second line,
The ventilation air conditioning system, wherein the second filter device is configured to collect a particulate radioactive substance and radioactive iodine. The ventilation air conditioning system according to claim 2,
The apparatus further comprises a hold-up device installed on the first line downstream of the first filter device,
The ventilation and air conditioning system, wherein the hold-up device is configured to physically adsorb the radioactive rare gas with an adsorbent. The ventilation air conditioning system according to claim 2,
The apparatus further includes an ionized rare gas removal device installed on the first line on the downstream side of the first filter device,
The ionized rare gas removal device is configured to ionize a radioactive rare gas, generate a rare gas compound by a chemical reaction from the ionized radioactive rare gas, and chemically adsorb the generated rare gas compound by an adsorbent. A ventilation air conditioning system characterized by the following. The ventilation air conditioning system according to claim 2,
An oxygen ion permeation device installed on the first line downstream of the first filter device;
The ventilation and air conditioning system, wherein the oxygen ion permeable device is configured to separate oxygen gas contained in air from air by an ion-conductive oxygen separation membrane capable of transmitting oxygen ions. The ventilation air conditioning system according to claim 2,
Further comprising a dissolution / separation device installed downstream of the first filter device in the first line,
The ventilation / air-conditioning system, wherein the dissolution / separation device is configured to introduce radioactive rare gas from the air by introducing air containing the radioactive rare gas into the solvent to dissolve the radioactive rare gas in the solvent. . The ventilation air conditioning system according to claim 2,
A recirculation line capable of supplying the air in the room again into the room;
A ventilation and air conditioning system, further comprising: a carbon dioxide removal device installed in the recirculation line and configured to remove carbon dioxide contained in air flowing through the recirculation line.

Images