JP2017125713A - Pressure release device and nuclear reactor building - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure release device capable of releasing gas in a nuclear reactor container in emergency to promptly lower pressure inside the nuclear reactor container.SOLUTION: A pressure release device 40 includes a body 41 installed at an open hole 20b formed on an upper mirror 20a configured to open/close a nuclear reactor container 20, and a rupture disc 42 installed on the body 41 and configured to partition the open hole 20b. The rapture disc 42 is configured to close the open hole 20b in a normal state; regulates water in a nuclear reactor well 12 from moving to the nuclear reactor container 20, the nuclear reactor well positioned above the nuclear furnace container 20; when the internal pressure of the nuclear reactor container 20 is equal to or higher than a predetermined value, is fractured to open the open hole 20b; and release gas in the nuclear reactor container 20 into the water in the nuclear reactor well 12.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pressure release device and a reactor building that discharges water vapor, hydrogen gas and the like remaining in a reactor containment vessel to the outside of the reactor containment vessel.

  In the event of an emergency such as an earthquake or tsunami that may impair the safety of the reactor, the reactor is cooled by driving the reactor cooling auxiliary equipment to operate the reactor. Need to stop. However, when the reactor cooling auxiliary equipment fails and the reactor cannot be cooled, core melting may occur. If core melting occurs, hydrogen gas and water vapor are generated accordingly. . If hydrogen gas or water vapor is left as it is, the pressure inside the reactor containment vessel may increase and the reactor containment vessel may burst. When the reactor containment vessel ruptures, radioactive materials are released to the environment, leading to environmental pollution.

  Conventionally, there is a technique described in Patent Document 1 as this kind of technique. According to Patent Document 1, a PCCS heat exchanger is provided in the reactor well pool, the steam in the reactor containment vessel is condensed by the PCCS heat exchanger, and the condensed water is returned to the reactor containment vessel. A technique is disclosed in which a part of the condensed gas is passed through water in the radioactive substance removal pool and released to the atmosphere. As described above, conventionally, when the gas in the reactor containment vessel is released, the radioactive material is removed by passing water.

JP 2013-253874 A

  However, in the case of urgency, it is necessary to release the gas in the reactor containment more quickly and lower the pressure inside the reactor containment.

  The present invention solves such problems and releases a gas in the reactor containment vessel in an emergency to quickly lower the pressure in the reactor containment vessel and the reactor building The purpose is to provide.

  In order to achieve the above object, the present invention has the following configuration.

  (1) A pressure release device comprising: a main body installed in a through hole formed in an upper mirror that opens and closes a reactor containment vessel; and a partition unit installed in the main body and partitioning the through hole. The section closes the through-hole in a normal state, and restricts the water stretched in the reactor well located above the reactor containment vessel from moving to the reactor containment vessel, When the internal pressure of the containment vessel becomes higher than a predetermined value, it is destroyed and the through hole is opened, and the gas in the reactor containment vessel is discharged into the water in the reactor well. Pressure release device to do.

  (2) The pressure release device according to (1), wherein the partition portion is made of a rupture disk.

According to (1) and (2), when the internal pressure of the reactor containment vessel is increased by steam, hydrogen gas, etc. generated by the melting of the core, the partition portion is destroyed and the through hole is opened. The water vapor, hydrogen gas, etc. in the reactor containment vessel are released, and the pressure in the reactor containment vessel decreases. Thereby, it becomes possible to suppress the pressure rise in the reactor containment vessel.
Moreover, when water vapor, hydrogen gas, or the like in the reactor containment vessel is released, the radioactive material contained in the gas is removed by passing through the water stretched in the reactor well. Thereby, it becomes possible to suppress scattering of a radioactive substance.

  (3) A reactor containment vessel that is opened and closed by an upper mirror in which the pressure release device of (1) or (2) is installed indoors, and the gas staying near the indoor ceiling is released to the outside on the rooftop. A nuclear reactor building comprising an exhaust device.

  According to (3), the gas released from the reactor containment vessel passes through the water stretched in the reactor well, moves to the upper floor indoors, and is released to the outside through the exhaust device. As a result, the hydrogen gas is prevented from being filled near the ceiling of the reactor building, and the risk of explosion can be prevented.

  According to the present invention, it is possible to release the gas in the reactor containment vessel in an emergency and quickly reduce the pressure inside the reactor containment vessel.

It is a top view which shows the example of arrangement | positioning of various buildings in the site of a nuclear power plant. It is explanatory drawing which shows the inside of the nuclear reactor building 50, and a rooftop. It is a side view which shows the upper mirror 20a with which the pressure release apparatus 40 in one Embodiment of this invention was mounted | worn. 3 is an explanatory diagram showing an internal configuration of the exhaust device 100. FIG. It is explanatory drawing which shows the movement path | route of the gas inside the reactor containment vessel 20 in emergency.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[Description of buildings on the nuclear power plant site]

  FIG. 1 is a plan view showing an example of the arrangement of various buildings within the site of a nuclear power plant. As shown in FIG. 1, a reactor building 50, a turbine building 52, a waste treatment building 54, a control room building 56, a service building 58, an exhaust pipe 60, and the like are built in the site of the nuclear power plant.

  The nuclear reactor building 50 accommodates a nuclear reactor 10 (see FIG. 2), a nuclear reactor auxiliary machine, and the like. The turbine building 52 houses a turbine that is heated by a nuclear reactor and is rotated by vaporized water, a generator that generates electric power by rotating the turbine, and the like. The waste treatment building 54 accommodates equipment for treating waste generated in the reactor building 50 and the turbine building 52. For example, a filter for removing dust from air ventilated in a building, a filtration device for filtering waste water, and the like are accommodated in the waste treatment building 54. The control room building 56 houses a central control device that monitors the operation of the nuclear power plant. The service building 58 has returned from the radiation control area, where the workers change into equipment for entering and exiting the radiation control area, for example, the radiation control area such as the reactor building 50, the turbine building 52, the waste treatment building 54, etc. It accommodates equipment for collecting equipment.

  In addition, the exhaust pipe 60 discharges the air from the air sent from the ventilation ducts of the reactor building 50, the turbine building 52, and the waste treatment building 54 into the atmosphere.

[Interior description of the reactor building]
FIG. 2 is an explanatory diagram showing the inside of the reactor building 50 and the rooftop.

  Inside the reactor building 50, a reactor 10, a reactor well 12, a steam dryer / steam separator pit 14, and a fuel pool 16 are provided.

  The nuclear reactor 10 includes a nuclear reactor containment vessel 20 and a nuclear reactor pressure vessel 22. The reactor containment vessel 20 is a vessel for storing the reactor pressure vessel 22 and includes an upper mirror 20a for opening and closing the reactor containment vessel 20 at the upper part. The reactor pressure vessel 22 is a vessel that houses a reactor core 24 that includes a fuel assembly (not shown), a control rod (not shown), an LPRM (not shown), and the like. A lid for opening and closing the door is provided.

  The reactor well 12 is a pool that is arranged on the upper part of the reactor containment vessel 20 and is directly connected to the reactor containment vessel 20. An upper mirror 20 a of the reactor containment vessel 20 is disposed at the bottom of the reactor well 12.

  The steam dryer / steam separator pit 14 is a pool for temporarily placing the steam dryer and steam separator during the regular inspection. Further, a passage portion 17 that is opened and closed by a partition is provided between the reactor well 12 and the steam dryer / steam separator pit 14, and the reactor well 12 is opened by opening the passage portion 17. And the steam dryer / steam separator pit 14 can communicate with each other.

  The fuel pool 16 is a pool for storing spent fuel 19 in the nuclear reactor 10. A passage 18 that is opened and closed by a partition is provided between the reactor well 12 and the fuel pool 16, and the reactor well 12 and the fuel pool 16 are communicated with each other by opening the passage 18. Can be made.

  The fuel pool 16 is always filled with water. The reactor well 12 and the steam dryer / water separator pit 14 are filled with water at least during regular inspection. In this embodiment, it is assumed that the reactor well 12, the fuel pool 16, and the steam dryer / water separator pit 14 are filled with water even during normal operation. In the reactor well 12, it is assumed that the surface of the upper mirror 20a is completely covered with water.

  In carrying out the periodic inspection, water in the reactor well 12 and the steam dryer / water separator pit 14 is drained immediately before the periodic inspection. Then, the upper mirror 20a is removed during periodic inspection, and water is injected into the reactor containment vessel 20, the reactor well 12, and the steam dryer / water separator pit 14, and then the lid of the reactor pressure vessel 22 is attached. Open and inspect the inside of the reactor pressure vessel 22.

  FIG. 3 is a side view showing the upper mirror 20a equipped with the pressure release device 40 in one embodiment of the present invention. The upper mirror 20a is a lid formed in a dome shape. The upper mirror 20a is opened during periodic inspection, and water can be poured into the reactor containment vessel 20.

  A through hole 20b is formed on the top of the upper mirror 20a so as to communicate the reactor well 12 and the inside of the reactor containment vessel 20. A pressure release device 40 is installed in the through hole 20b.

  The pressure release device 40 includes a tubular main body 41 inserted into the through-hole 20 b and a rupture disk 42 corresponding to a partition portion mounted inside the main body 41. The main body 41 is disposed on the reactor well 12 side. Packing is interposed between the main body 41 and the edge of the through hole 20b, and the gap between the main body 41 and the edge of the through hole 20b is sealed. The rupture disk 42 includes a rupturable plate that partitions the inside of the main body 41. In other words, the rupture disk of the rupture disk 42 blocks the through hole 20b. The rupture disc ruptures when the internal pressure of the reactor containment vessel 20 exceeds a predetermined value.

In the state where the internal pressure of the reactor containment vessel 20 is less than a predetermined value and the reactor well 12 is filled with water, the rupture disk of the rupture disk 42 is not broken by the water pressure. For this reason, water does not move into the reactor containment vessel 20 in the reactor well 12. However, since the rupturable plate bursts when the internal pressure of the reactor containment vessel 20 exceeds a predetermined value, the gas in the reactor containment vessel 20 is released into the reactor well 12 into the water.
[Explanation on the roof of the reactor building]

  An exhaust device 100 is installed on the roof of the reactor building 50. The exhaust device 100 discharges hydrogen gas staying on the top floor of the reactor building 50 to the outside.

  As shown in FIG. 2, the exhaust device 100 includes a discharge unit 110, a discharge duct 112, and a wire 114.

  FIG. 4 is an explanatory diagram showing the internal configuration of the exhaust device 100, and the discharge unit 110 is a box-shaped member installed on the top floor of the reactor building 50. The inside of the discharge unit 110 communicates with the reactor building 50, and a discharge port 110 a is formed on the side surface of the discharge unit 110.

  The discharge duct 112 is a cylindrical member having a diameter of about 1 m, has a base end portion fixed so as to cover the discharge port 110a in the discharge portion 110, and extends from the discharge portion 110 in the horizontal direction. For this reason, the hydrogen gas staying on the top floor of the reactor building 50 is discharged into the atmosphere from the tip of the discharge duct 112 through the discharge portion 110 and the discharge duct 112.

  The exhaust device 100 further includes lid bodies 120 and 130, a filter 140, and a wire 116, and the lid bodies 120 and 130 and the filter 140 are installed in the discharge duct 112. In the discharge duct 112, members are arranged in the order of the filter 140, the lid body 130, and the lid body 120 from the discharge port 110a side (base end side) to the opening end side (tip end side).

  The lid bodies 120 and 130 seal the discharge duct 112 in a normal state and restrict the gas from the reactor building 50 from moving to the outside. The sealed state of the lids 120 and 130 is canceled in an emergency, for example, when the nuclear reactor building 50 is filled with hydrogen gas and there is a risk of explosion.

  In addition, the lids 120 and 130 are installed at a predetermined interval inside the discharge duct 112, and a sealed space is formed between the adjacent lids 120 and 130. In this sealed space, a gas such as nitrogen gas is sealed so as to be at atmospheric pressure or higher.

  The filter 140 collects and adsorbs a radioactive substance from the gas that has passed from the reactor building 50 through the discharge port 110a. As the filter 140, zeolite is applicable.

  Further, as shown in FIG. 4, the wire 114 is connected to the upper part of the lid 120, and the upper part of the lid 120 and the lid 130 is connected by the wire 116. Here, the wire 116 is desirably stretched. Thereby, by pulling the wire 114, the lid body 120 and the lid body 130 operate and the discharge duct 112 is opened. In the present embodiment, the tip end of the wire 114 is connected to the lid body 120, and the lid body 120 and the lid body 130 are connected by the wire 116. However, the present invention is not limited thereto, and the lid body 120 and the lid body 130 are connected. It may be fixed to one wire 114.

The place where the worker pulls the wire 114 can be set as appropriate. However, in an emergency such as an earthquake, it is necessary to evacuate early, so there is no room for an operator to go to the roof and open the discharge duct 112. For this reason, it is desirable that an operator can pull the wire 114 on the ground, for example, by installing a winding device for the wire 114 outdoors.
[Operation of pressure release device]

  Next, operation | movement of the pressure release apparatus 40 of this embodiment is demonstrated. For example, when a large natural disaster such as an earthquake or a tsunami occurs, the reactor cooling auxiliary equipment breaks down and the reactor cannot be cooled. In this case, the worker pulls the wire 114 to open the discharge duct 112 in preparation for the occurrence of core melting, so that the gas in the reactor building 50 can be released to the outside.

  If core melting occurs, the steam leaks from the pipe connected to the reactor pressure vessel 22, thereby increasing the internal pressure of the reactor containment vessel 20. When the internal pressure of the reactor containment vessel 20 exceeds a predetermined value, the rupture disk 42 of the pressure release device 40 is destroyed, and as shown in FIG. 5, the gas (hydrogen, water vapor, etc.) inside the reactor containment vessel 20 is destroyed. Is released to the reactor well 12 through the pressure release device 40.

  Here, since the reactor well 12 is filled with water, the gas released to the outside of the reactor containment vessel 20 passes through the water in the reactor well 12 and moves into the reactor building 50. To do. At this time, radioactive substances contained in the gas are removed.

  In the gas released to the outside of the reactor containment vessel 20, particularly hydrogen gas moves to the upper floor in the reactor building 50, further passes through the discharge part 110 of the exhaust device 100, and passes through the filter 140 (see FIG. 4). ) Through which the radioactive material is further removed and then released into the atmosphere.

  According to the present embodiment configured as described above, the rupture disk 42 of the pressure release device 40 is destroyed when the internal pressure of the reactor containment vessel 20 exceeds a predetermined value, and the reactor containment vessel 20 By releasing gas (steam, hydrogen gas, etc.) to the outside, the internal pressure of the reactor containment vessel 20 can be reduced. Thereby, it becomes possible to suppress the pressure rise in the reactor containment vessel. Further, the gas released to the outside from the reactor containment vessel 20 passes through the water stretched in the reactor well 12 to remove the radioactive substance contained in the gas and then released to the outside. Thereby, it becomes possible to suppress scattering of a radioactive substance.

Further, the passage portions 17 and 18 are opened in conjunction with the destruction of the rupture disk 42, and the reactor well 12, the steam dryer / water separator pit 14 and the fuel pool 16 can be communicated with each other. As a result, the volume of water that passes through when the gas released from the reactor containment vessel 20 diffuses increases, and the radioactive material contained in the gas can be released to the outside in a state in which it is further removed.
Further, an exhaust device 100 is installed on the roof of the reactor building 50, and hydrogen gas contained in the gas released from the reactor containment vessel 20 moves to the upper side of the reactor building 50. Through the atmosphere. As a result, the hydrogen gas is prevented from being filled near the ceiling of the reactor building 50, and the risk of explosion can be prevented.

  As mentioned above, although embodiment of this invention was described, embodiment of this invention is not restricted to what was mentioned above. For example, according to the above-described embodiment, the pressure release device 40 is provided at the top of the upper mirror 20a, but is not limited thereto, and may be provided at the side of the upper mirror 20a. Further, according to the embodiment, only one pressure release device 40 is provided in the upper mirror 20a, but a plurality of pressure release devices 40 may be provided.

10 Reactor 12 Reactor Well 14 Steam Dryer / Water / Water Separator Pit 16 Fuel Pool 17, 18 Passage 19 Spent Fuel 20 Reactor Containment 20a Upper Mirror 20b Through Hole 22 Reactor Pressure Vessel 24 Core 40 Pressure Release Equipment 41 Main body 42 Rupture disk 50 Reactor building 52 Turbine building 54 Waste treatment building 56 Control room building 58 Service building 60 Exhaust tube 100 Exhaust device 110 Emission part 110a Emission port 112 Emission duct 114, 116 Wire 120, 130 Lid 140 filter

Claims (3)

A pressure release device comprising: a main body installed in a through hole formed in an upper mirror that opens and closes a nuclear reactor containment vessel; and a partition unit installed in the main body and partitioning the through hole,
The partitioning portion closes the through hole in a normal state, and restricts the water stretched in the reactor well located on the reactor containment vessel from moving to the reactor containment vessel, When the internal pressure of the containment vessel becomes higher than a predetermined value, it is destroyed and the through hole is opened, and the gas in the containment vessel is released into the water in the reactor well. Feature pressure release device.   The pressure release device according to claim 1, wherein the partition portion is formed of a rupture disk. A reactor containment vessel that is opened and closed by an upper mirror in which the pressure release device according to claim 1 or 2 is installed indoors,
A nuclear reactor building comprising an exhaust device on a rooftop that discharges gas staying near an indoor ceiling to the outside.

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