Emergency recirculation valve of small module reactor operating in differential pressure type

Abstract

The present invention relates to a small module reactor capable of increasing operation reliability of an emergency recirculation valve for recirculation of cooling water in an emergency core cooling system, wherein an emergency recirculation valve (240) provided in the emergency core cooling system of the small module reactor including a reactor vessel (210) and a containment vessel (220), comprises: a valve body (241) provided in the reactor vessel (210) and provided with a disk (242) which is opened and closed by a differential pressure between the reactor vessel (210) and the containment vessel (220) to regulate the flow of coolant; a first elastic body (245) which elastically supports the disk (242) in the valve body (241); a stopper member (246) provided in the driving direction of the disk (242) to limit the driving of the disk (242); and a chamber (243) in which a diaphragm (244) connected to the stopper member (246) is accommodated and control pressure is supplied to one space partitioned by the diaphragm (244).

Description

Emergency recirculation valve for small modular reactors operating in differential pressure mode

[0001] The present invention relates to a small modular reactor, and more particularly, to an emergency recirculation valve of a small modular reactor (SMR) that operates in a differential pressure type capable of operating in a mechanical environment by excluding measuring equipment from an emergency core cooling system.

[0002] Nuclear power generation is a power generation method that can produce large amounts of power stably and economically. However, it has drawbacks such as difficult output control, limited methods for cooling the reactor, high power plant construction costs, and limited locations.

[0003] Nuclear technology is advancing in ways that enhance safety, economic feasibility, and nuclear non-proliferation, and development of SMRs as improved next-generation reactors is expanding.

[0004] Small modular reactors are small and medium-sized reactors with a smaller capacity (less than 300 MWe) than existing nuclear power plants, and are a general term for various small and medium-sized nuclear power plants, including light water reactors, heavy water reactors, fast reactors, and high-temperature reactors.

[0005] The Emergency Core Cooling System (ECCS) of the innovative SMR (i-SMR) being developed domestically adopts a method of cooling the reactor core using natural circulation, unlike existing commercial nuclear power plants.

[0006] The emergency core cooling system of a small modular reactor includes a reactor vessel in which the core is placed and filled with coolant, and a containment vessel that accommodates the reactor vessel. The reactor vessel is provided with an emergency pressure relief valve for depressurization in the event of a coolant loss accident, and an emergency recirculation valve for recirculating the coolant.

[0007] When a Loss of Coolant Accident (LOCA) occurs, an ECCS activation signal is generated, which opens the Emergency Depressurization Valve (EDV) and Emergency Recirculation Valve (ERV), releasing the steam and coolant inside the reactor vessel into the containment vessel, decreasing the pressure in the reactor vessel and increasing the pressure in the containment vessel. Meanwhile, the steam inside the containment vessel is condensed by the passive containment cooling system and accumulates in a liquid state at the bottom of the containment vessel. Afterwards, when the pressure between the reactor vessel and the containment vessel reaches equilibrium and the water level inside the containment vessel rises higher than that inside the reactor vessel, a head difference is generated, allowing coolant to flow from the containment vessel into the reactor vessel through the emergency recirculation valve, allowing natural circulation to cool the reactor core.

[0008] In such emergency core cooling systems, when the emergency recirculation valve is used as a valve that operates in the existing instrumentation and control environment (e.g., an electrically driven valve), the reliability of the valve operation is reduced due to malfunction of the instrument.

[0009] Next, if the emergency pressure relief valve and emergency recirculation valve open simultaneously in the event of a loss of coolant accident, the pressure in the reactor vessel is initially higher than that in the containment vessel, so the reactor coolant is released into the containment vessel through the emergency recirculation valve. At this time, the coolant may flow back into the reactor core, and there is a possibility that denuclearization boiling (DNB) may cause damage to the nuclear fuel.

[0010] [Prior Art Literature]

[0011] [Patent Document]

[0012] (Patent Document 1) Korean Patent Publication No. 10-2014-0016104 (Publication Date: February 7, 2014)

[0013] The present invention is intended to improve the problems of the prior art, and to provide an emergency recirculation valve for a small modular reactor that can prevent malfunction and increase operational reliability by excluding the configuration of electrical components such as measuring instruments in the emergency core cooling system and implementing it in a mechanical manner.

[0014] In order to achieve these purposes, the emergency recirculation valve of a small modular reactor according to the present invention is an emergency recirculation valve provided in an emergency core cooling system of a small modular reactor including a reactor vessel and a containment vessel, and includes: a valve body provided in the reactor vessel and having a disk for controlling the flow of coolant between the reactor vessel and the containment vessel; a chamber provided with a diaphragm connected to the disk and in which the internal pressure of the containment vessel and a control pressure by air pressure are applied through the diaphragm; and an elastic body elastically supporting the diaphragm within the chamber.

[0015] Preferably, the elastic body elastically supports the diaphragm so that the disk is opened when the pressure of the reactor vessel acting on the disk and the pressure of the containment vessel acting by the diaphragm within the chamber are in equilibrium.

[0016] According to another embodiment of the present invention, an emergency recirculation valve for a small modular reactor is provided in an emergency core cooling system of a small modular reactor including a reactor vessel and a containment vessel, and comprises: a valve body provided in the reactor vessel and having a disk that opens and closes by a pressure differential between the reactor vessel and the containment vessel to control a coolant flow; a first elastic body that elastically supports the disk within the valve body; a stopper member that is provided in a driving direction of the disk to limit driving of the disk; and a chamber in which a diaphragm connected to the stopper member is accommodated and a control pressure is supplied to one side space defined by the diaphragm.

[0017] Preferably, the first elastic body elastically supports the disk so that the disk is opened when the pressure of the reactor vessel acting on the disk and the pressure of the containment vessel are in equilibrium, and further preferably, the second elastic body elastically supports the diaphragm.

[0018] More preferably, the second elastic body elastically supports the diaphragm so that the stopper member and the disk are spaced apart during normal operation of the reactor.

[0019] Preferably, it includes a pneumatic circuit provided on the outside of the containment vessel to apply control pressure to the chamber.

[0020] More preferably, the pneumatic circuit further includes a first solenoid valve connected to the chamber and provided in a first flow path to which a control pressure greater than the internal pressure of the containment vessel is applied to open and close the flow path; and a second solenoid valve connected to the chamber and provided in a second flow path through which air is discharged to open and close the flow path.

[0021] More preferably, the first solenoid valve is a fail close type valve, and the second solenoid valve is a fail open type valve.

[0022] The emergency pressure relief valve of a small modular reactor of the present invention is an emergency recirculation valve provided in an emergency core cooling system of a small modular reactor including a reactor vessel and a containment vessel, and includes a valve body having a disk provided in the reactor vessel and controlling the flow of coolant between the reactor vessel and the containment vessel, a chamber having a diaphragm connected to the disk and in which the internal pressure of the containment vessel and a control pressure by air pressure are applied through the diaphragm, and an elastic body elastically supporting the diaphragm within the chamber, thereby implementing an emergency recirculation valve capable of operating in a mechanical environment by excluding measuring equipment, thereby preventing malfunction of the valve due to measuring equipment and improving reliability.

[0023] In addition, in the small modular reactor of the present invention, the emergency recirculation valve is opened at the point in time when the pressure between the reactor vessel and the containment vessel is equalized after the emergency pressure relief valve is operated first when a LOCA occurs, thereby minimizing improper core cooling due to reverse flow of the reactor coolant.

[0024] FIG. 1 is a schematic diagram of a small modular reactor including an emergency recirculation valve according to an embodiment of the present invention.

[0025] Figure 2 is a configuration diagram of an emergency recirculation valve of a small modular reactor according to an embodiment of the present invention.

[0026] Figure 3 is a schematic diagram showing the operation of an emergency recirculation valve in the event of an accident in a small modular reactor according to an embodiment of the present invention.

[0027] Figure 4 is a configuration diagram of an emergency recirculation valve of a small modular reactor according to another embodiment of the present invention.

[0028] FIG. 5 is a schematic diagram for explaining the operation of an emergency recirculation valve in the event of an accident in a small modular reactor according to another embodiment of the present invention.

[0029] The specific structural and functional descriptions presented in the embodiments of the present invention are merely illustrative for the purpose of explaining embodiments according to the concept of the present invention, and embodiments according to the concept of the present invention may be implemented in various forms. Furthermore, they should not be construed as being limited to the embodiments described herein, but should be understood to include all modifications, equivalents, and substitutes included within the spirit and technical scope of the present invention.

[0030] Meanwhile, in the present invention, terms such as first and / or second may be used to describe various components, but the components are not limited to these terms. These terms are used solely for the purpose of distinguishing one component from other components. For example, within the scope of the rights according to the concept of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

[0031] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may also be other components in between. Conversely, when a component is referred to as being "directly connected" or "directly in contact with" another component, it should be understood that there are no other components in between. Other expressions used to describe the relationship between components, such as "between" and "directly between" or "adjacent to" and "directly adjacent to," should be interpreted similarly.

[0032] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. It should be understood that the terms "comprises" or "has" in this specification specify the presence of implemented features, numbers, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0033] Hereinafter, specific embodiments of the present invention will be described with reference to the attached drawings. It should be understood that the sizes of components or the connection between components may be exaggerated or omitted to aid understanding.

[0034] FIG. 1 is a schematic diagram of a small modular reactor including an emergency recirculation valve according to an embodiment of the present invention.

[0035] Referring to FIG. 1, a small modular reactor according to an embodiment of the present invention includes a reactor vessel (110) and a containment vessel (120) that accommodates the reactor vessel (110). The reactor vessel (110) is provided with an emergency pressure relief valve (130) for depressurization in the event of a coolant loss accident, and an emergency recirculation valve (140) for recirculating the coolant.

[0036] The reactor vessel (110) has a core placed at the bottom center and is filled with cooling water to operate at a pressure above a certain level.

[0037] The containment vessel (120) is a steel vessel designed to surround the reactor vessel (110) at a certain interval, and the space between the reactor vessel (110) and the containment vessel (120) is vacuum, and in the event of a loss of coolant accident, the space between the reactor vessel (110) and the containment vessel (120) is filled with coolant. The containment vessel (120) may have a passive cooling heat exchanger (121) provided on the inner wall, and the passive cooling heat exchanger (121) is connected to an external cooling water storage tank (not shown) to perform heat exchange, so that when an accident occurs, steam released from the reactor vessel (110) to the containment vessel (120) is condensed by the passive cooling heat exchanger (121) to remove heat from the containment vessel (120).

[0038] The reactor vessel (120) is provided with an emergency pressure relief valve (130) as a pressure relief system at the top. The emergency pressure relief valve (130) is closed during normal operation of the reactor, and opens in the event of an accident to lower the pressure of the reactor vessel (120).

[0039] The reactor vessel (120) is provided with an emergency recirculation valve (140) at approximately the bottom of the side, and the emergency recirculation valve (140) induces recirculation of coolant in the event of a coolant loss accident.

[0040] Preferably, the emergency recirculation valve (140) includes a valve body (141) provided with a disk (142) that is installed in the reactor vessel (110) to cut off the flow of coolant between the reactor vessel (110) and the containment vessel (120), a chamber (143) provided with a diaphragm (144) connected to the disk (142) and in which the pressure of the containment vessel (120) and the control pressure by air pressure are applied through the diaphragm (144), and an elastic body (145) that elastically supports the diaphragm (144) within the chamber (143).

[0041] Preferably, it further includes a pneumatic circuit (146)(147) provided outside the containment vessel (120) to apply control pressure to the chamber (143), and this pneumatic circuit (146)(147) may be provided by a solenoid valve, but is not limited thereto.

[0042] Figure 2 is a configuration diagram of an emergency recirculation valve of a small modular reactor according to an embodiment of the present invention.

[0043] Specifically, referring to FIG. 2, a valve body (141) is installed in a reactor vessel (110) and has a flow hole (141a) provided therein that connects the space of the reactor vessel (110) and the containment vessel (120), and a disk (142) that opens and closes the flow hole (141a) is provided.

[0044] The disk (142) is fixed to the diaphragm (144) by a valve stem (142a), and the diaphragm (144) is elastically supported by an elastic body (145) within the chamber (143) to enable up and down movement.

[0045] The chamber (143) is divided into upper and lower spaces by a diaphragm (144). The upper part of the diaphragm (144) is provided with an elastic body (145) and a first port (143a) that communicates with the internal space of the containment vessel (120), and the lower part is provided with a second port (143b) that connects the pneumatic circuit (146) (147).

[0046] The diaphragm (144) moves up and down between the first port (143a) and the second port (143b) within the chamber (143), and a stopper protrusion (143c) may be provided on the inside of the chamber (143) to limit the up and down movement of the diaphragm (144) between the first port (143a) and the second port (143b). In this embodiment, only the stopper protrusion (143c) located at the upper end of the second port (143b) to limit the lower movement range of the diaphragm (144) is exemplified, but a stopper protrusion may also be provided at the lower end of the first port (143a) to limit the upper movement range of the diaphragm (133). Preferably, the diaphragm (144) may be provided with a known sealing member to partition the upper and lower parts of the chamber (143) and seal the upper and lower spaces.

[0047] The pneumatic circuit (146)(147) includes a first solenoid valve (146) provided in a first flow path (146a) connected to a first port (143b) to supply control pressure, and a second solenoid valve (147) provided in a second flow path (147a) connected to the first port (143b) to discharge air.

[0048] Preferably, the first solenoid valve (146) is a fail close type valve, and the second solenoid valve (147) is a fail open type valve.

[0049] The emergency recirculation valve (140) of the present invention configured in this way is maintained in a closed state during normal operation. For reference, during normal operation, the internal pressure (P) of the reactor vessel (110) RV ) is the highest (~155 bar), the inside of the containment vessel (120) is in a vacuum (or sub-atmospheric pressure), and the pneumatic circuit (146)(147) is placed outside the containment vessel (120) and placed in an atmospheric pressure state. The internal pressure of the containment vessel (120) is P CV The atmospheric pressure outside the containment vessel (120) is described as P ATIf written as , the pressure state during normal operation is P RV > P CV > P AT It becomes.

[0050] Meanwhile, the first solenoid valve (146) is used when the emergency recirculation valve (140) is forcibly kept closed due to the need for planned preventive maintenance, etc., and the first solenoid valve (156) is opened to maintain the internal pressure (P) of the containment vessel (120). CV ) is applied as the control pressure, the emergency recirculation valve (140) is forcibly kept closed, and at this time, the second solenoid valve (147) is closed.

[0051] During normal operation of the reactor, the first solenoid valve (146) is closed, the second solenoid valve (147) is open, and at this time, the diaphragm (144) is maintained in the closed state by the pressure difference between the reactor vessel (110) and the containment vessel (120). Specifically, the pressure acting on the diaphragm (144) during normal operation of the reactor is as shown in the following [Mathematical Formula 1].

[0052] [Mathematical Formula 1]

[0053]

[0054] A D is the cross-sectional area of ​​the disk (142), and A d is the cross-sectional area of ​​the diaphragm (144), and F S is the tension of the elastic body.

[0055] Figure 3 is a schematic diagram showing the operation of an emergency recirculation valve in the event of an accident in a small modular reactor according to an embodiment of the present invention.

[0056] Referring to Figure 3, in the event of an accident such as a loss of reactor coolant accident (LOCA), the coolant leaks outside the reactor vessel (110) and the internal pressure (P) of the reactor vessel (110) RV ) decreases and the pressure (P) of the containment vessel (120) CV) increases. Afterwards, the internal pressure (P) of the reactor vessel (110) RV ) decreases below a certain level and the pressure (P) of the containment vessel (120) CV ) increases above a certain level and the condition of the following [Mathematical Formula 2] is satisfied, the emergency recirculation valve (140) is opened.

[0057] [Equation 2]

[0058]

[0059] When the emergency recirculation valve (140) is opened, the coolant condensed in the containment vessel (120) flows into the reactor vessel (110), thereby cooling the reactor core.

[0060] Meanwhile, the opening point of the emergency recirculation valve (140) can be determined by the tension of the elastic body (145).

[0061] Figure 4 is a configuration diagram of an emergency recirculation valve of a small modular reactor according to another embodiment of the present invention.

[0062] Referring to FIG. 4, a small modular reactor according to another embodiment of the present invention includes a reactor vessel (210) and a containment vessel (220) that accommodates the reactor vessel (210). The reactor vessel (210) is provided with an emergency pressure relief valve for pressure reduction in the event of a coolant loss accident and an emergency recirculation valve for coolant recirculation, which are the same as those in the previous embodiment.

[0063] The emergency recirculation valve (240) of the present embodiment includes a valve body (241) having a disk (242) that opens and closes by differential pressure to cut off the flow of coolant, a first elastic body (245) that elastically supports the disk (242), a stopper member (246) that can limit the operation of the disk (242), and a chamber (243) in which a diaphragm (244) connected to the stopper member (246) is accommodated and the stopper member (246) is driven by a control pressure applied to the diaphragm (244).

[0064] The valve body (241) is provided in the reactor vessel (210) and includes a disk (242) that opens and closes the flow hole by the differential pressure between the reactor vessel (210) and the containment vessel (220) to control the flow of coolant.

[0065] The valve body (241) is provided with a disk guide (241a) for guiding the movement of the disk (242) around the euro hole, and further, the disk (242) is provided with an auxiliary disk (242a), and the auxiliary disk (242a) is elastically supported by a first elastic body (245). The valve body (241) may be provided with an auxiliary disk guide (242b) into which the auxiliary disk (242a) and the first elastic body (245) are inserted to guide the movement of the auxiliary disk (242a). The disk guide (241a) or the auxiliary disk guide (242b) may be provided with a stopper protrusion (not shown) that can limit the vertical movement range of the disk (242) or the auxiliary disk (242a).

[0066] Preferably, the first elastic body (245) is configured to resist the pressure (P) of the reactor vessel (210) acting on the disk (242). RV ) and the pressure (P) of the containment vessel (220) CV ) elastically supports the disk (242) so as to open the disk (242) in an equilibrium state.

[0067] A stopper member (246) is provided on the same axis as the driving direction of the disk (242) to limit the driving of the disk (242), and this stopper member (246) is connected to a diaphragm (244) in the chamber (243) and is operated by a control pressure supplied into the chamber (243).

[0068] The chamber (243) is divided into upper and lower parts by a diaphragm (244), and a port (243a) to which a pneumatic circuit (251) (252) is connected is provided at the upper part.

[0069] Preferably, the chamber (243) includes a second elastic member (247) that elastically supports the diaphragm (244). The second elastic member (247) supports the diaphragm (244) upwards so that the stopper member (246) and the disk (242) are kept spaced apart during normal operation of the reactor.

[0070] Preferably, the diaphragm (244) may be provided with a known sealing member (not shown) for sealing between the upper space and the lower space by dividing the upper and lower parts of the chamber (243). In particular, in the chamber (243) of the present embodiment, the upper space and the lower space divided by the diaphragm (144) do not come into contact with a high temperature / high pressure fluid (cooling water), so that, unlike the previous embodiment, the sealing member of the diaphragm (244) can prevent a decrease in sealing properties that may occur due to direct exposure to high temperature / high pressure.

[0071] The pneumatic circuit (251)(252) includes a first solenoid valve (251) provided in a first passage (251a) connected to a port (243a) to supply control pressure, and a second solenoid valve (252) provided in a second passage (252a) connected to the port (243a) to discharge air.

[0072] Preferably, the first solenoid valve (251) is a fail close type valve, and the second solenoid valve (252) is a fail open type valve.

[0073] The emergency recirculation valve (240) of this embodiment configured as described above is maintained in a closed state during normal operation, and as described above, the internal pressure (P) of the reactor vessel (210) during normal operation RV ) is the highest (~155 bar), the inside of the containment vessel (220) is in a vacuum (or sub-atmospheric pressure), and the pneumatic circuit (251)(252) is placed outside the containment vessel (120) and placed in an atmospheric pressure state.

[0074] In the present embodiment, the first solenoid valve (251) and the second solenoid valve (252) can operate in the same manner as in the previous embodiment. For example, in cases where it is necessary to forcibly maintain the emergency recirculation valve (240) in a closed state, such as during planned preventive maintenance, the first solenoid valve (251) is opened so that high-pressure compressed air is supplied into the chamber (243) at a controlled pressure, thereby lowering the stopper member (246) to press and fix the disk (242), thereby forcibly maintaining the emergency recirculation valve (140) in a closed state. Meanwhile, in this process, the lower space of the diaphragm (244) of the chamber (243) is sealed and compressed, and the second elastic body (247) is also compressed.

[0075] FIG. 5 is a schematic diagram for explaining the operation of an emergency recirculation valve in the event of an accident in a small modular reactor according to another embodiment of the present invention.

[0076] Referring to Figure 5, in the event of an accident such as a loss of reactor coolant accident (LOCA), the coolant leaks outside the reactor vessel (210) and the internal pressure (P) of the reactor vessel (210) RV ) decreases and the pressure (P) of the containment vessel (220) CV ) increases, and then the internal pressure (P) of the reactor vessel (210) RV ) decreases below a certain level and the pressure (P) of the containment vessel (220) CV ) increases above a certain level, and the internal pressure of the reactor vessel (210) and the containment vessel (220) is in a balanced state (P RV P CV ) In this case, the disk (242) is opened by the first elastic body (245), and the coolant condensed in the containment vessel (220) flows into the reactor vessel (210), thereby cooling the reactor core.

[0077] The present invention described above is not limited to the above-described embodiments and the attached drawings, and it will be apparent to a person skilled in the art to which the present invention pertains that various substitutions, modifications, and changes are possible within a scope that does not depart from the technical spirit of the present invention.

[0078] [Explanation of symbols]

[0079] 100: Small modular reactor 110, 210: Reactor vessel

[0080] 120, 220: Containment vessel 130: Emergency pressure relief valve

[0081] 140, 240: Emergency recirculation valve 141, 241: Valve body

[0082] 142, 242: Disc 143, 243: Chamber

[0083] 144, 244: Diaphragm 145: Elastic

[0084] 146, 251: 1st solenoid valve 147, 252: 2nd solenoid valve

[0085] 245: First elastic body 246: Stopper member

[0086] 247: Second elastic body

Claims

1. An emergency recirculation valve provided in the emergency core cooling system of a small modular reactor including a reactor vessel and a containment vessel. A valve body having a disc provided in the reactor vessel to control the flow of coolant between the reactor vessel and the containment vessel; A chamber in which a diaphragm connected to the above disk is provided and in which the internal pressure of the containment vessel and the control pressure by air pressure are applied through the diaphragm; An emergency recirculation valve for a small modular reactor comprising an elastic body elastically supporting the diaphragm within the chamber.

2. An emergency recirculation valve for a small modular reactor, characterized in that in the first paragraph, the elastic body elastically supports the diaphragm so that the disk is opened when the pressure of the reactor vessel acting on the disk and the pressure of the containment vessel acting by the diaphragm within the chamber are in equilibrium.

3. An emergency recirculation valve provided in the emergency core cooling system of a small modular reactor including a reactor vessel and a containment vessel. A valve body having a disc provided in the reactor vessel and opened and closed by the differential pressure between the reactor vessel and the containment vessel to cut off the flow of coolant; A first elastic body that elastically supports the disk within the valve body; A stopper member provided in the driving direction of the above disk to limit the driving of the above disk; An emergency recirculation valve for a small modular reactor, comprising a chamber in which a diaphragm connected to the stopper member is accommodated and a control pressure is supplied to one side space partitioned by the diaphragm.

4. An emergency recirculation valve for a small modular reactor, characterized in that in the third paragraph, the first elastic body elastically supports the disk so that the disk is opened when the pressure of the reactor vessel acting on the disk and the pressure of the containment vessel are in equilibrium.

5. An emergency recirculation valve for a small modular reactor further comprising a second elastic body that elastically supports the diaphragm in the third paragraph.

6. An emergency recirculation valve for a small modular reactor, characterized in that in paragraph 5, the second elastic body elastically supports the diaphragm so that the stopper member and the disk are separated during normal operation of the reactor.

7. An emergency recirculation valve for a small modular reactor, comprising a pneumatic circuit section provided outside the containment vessel and configured to apply control pressure to the chamber, in accordance with paragraph 1 or 3.

8. In paragraph 7, the pneumatic circuit part, A first solenoid valve connected to the chamber and provided in a first path to which a control pressure greater than the internal pressure of the containment vessel is applied to open and close the path; An emergency recirculation valve for a small modular reactor, comprising a second solenoid valve connected to the chamber and provided in a second passage through which air is discharged, to open and close the passage.

9. An emergency recirculation valve for a small modular reactor, characterized in that in paragraph 8, the first solenoid valve is a fail close type valve, and the second solenoid valve is a fail open type valve.

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