JPS6244687A - Nuclear reactor containing facility - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field of invention 1 The present invention relates to nuclear reactor containment equipment.

['Q Ming's technical background 1 Light water reactors such as boiling water reactors are conventionally equipped with a containment vessel called a pressure suppression type. An example is shown below.
A conventional example of nuclear reactor containment equipment will be explained with reference to the figure. Here, FIG. 1 does not show a schematic vertical cross-sectional view of a conventional nuclear reactor containment facility. In FIG. 1, a reactor pressure vessel 3 is installed in a dry well 1 that forms the upper part of the reactor containment facility and has airtightness and pressure resistance. installed at the top. Further, the dry well 1 accommodates a connecting pipe 4 to the reactor pressure vessel 3 and associated valves and other equipment (not shown). Further, a pressure suppression chamber 5 is provided adjacent to this dry well 1, and a large amount of coolant (hereinafter referred to as pool water) 6 is stored in this chamber. and,
The dry well 1 and the pressure suppression chamber 5 are communicated through a vent pipe 7, the lower end of which is open into the pool water 6.

In the above configuration, if a break occurs in the connecting pipe 4 to the reactor pressure vessel 3 in the dry well 1 and a loss of coolant accident occurs, first the non-condensation of nitrogen etc. sealed in the dry well 1 occurs. The gas is released from the lower end of the vent pipe 7 into the pool water 6 in the pressure suppression chamber 5. Subsequently, the coolant and steam flowing out from the fracture port are similarly ejected into the pool water 6 through the vent pipe 7, but the steam is condensed and the pressure within the containment vessel is prevented from increasing.
In addition, leaked coolant is also contained within the containment vessel to prevent it from being released into the environment.

Here, the non-condensable gas is +
*M '1'L': K'i' (7)
"l" JEE power! Ii'l M 5 (7) % @
? AIL 8 ■ I will do it. In the event of a loss of coolant accident, coolant continues to flow out from the fracture opening and steam is continuously supplied, so that most of the non-condensable gas in the dry well 1 is transferred to the gas phase of the pressure suppression chamber 5 in a relatively short time. As a result, the pressure inside the pressure suppression chamber 5 becomes quite high. Furthermore, the dry well pressure is obtained by adding the water head difference of the vent pipe 7 to this pressure suppression kiln internal pressure. Therefore, the pressure inside the containment vessel at the time of a loss of coolant accident is strongly controlled by the volume ratio of the gas phase portions of the dry well 1 and the pressure suppression chamber 5.

That is, the larger the volume of the gas phase portion of the pressure suppression chamber 5 relative to the free space volume within the dry well 1, the lower the internal pressure of the reactor containment vessel after a loss of coolant accident can be suppressed. .

[Problems with dorsal head technology] In the above configuration, the pressure inside the containment vessel in the event of a loss of coolant accident strongly depends on the volume ratio of the dry well and the gas phase of the pressure suppression chamber. When the volume of the dry well increases, it is necessary to ensure a volume of the gas phase in the pressure suppression chamber corresponding to this increase, and it is considered that the pool water base for stably condensing steam will also increase.

This may lead to an increase in the size of the containment vessel or an increase in the maximum operating pressure, which may pose a design problem.

[Object of the Invention] The object of the present invention is to provide a containment facility that is not restricted by the conventional volume ratio of the dry well to the pressure suppression chamber space by making the pressure suppression chamber space of the reactor containment vessel a pressure open type. The objective is to simultaneously reduce the size of the vessel and reactor building and to ease the H-resistance conditions of the containment vessel.

[Summary of the Invention] The present invention provides a nuclear reactor pressure vessel, a reactor containment vessel that stores the reactor pressure vessel, and a nuclear reactor that is fixed to the bottom of the reactor containment vessel and supports the reactor pressure. a pedestal, a pressure suppression chamber formed at the lower part of the reactor pressure vessel and containing a coolant therein, a dry well formed at the upper part of the reactor pressure vessel, and an upper part open to the dry well and a lower part opened to the dry well. In reactor containment equipment consisting of a vent pipe that opens into the coolant in a pressure suppression chamber, a communication pipe that communicates the pressure suppression chamber with the outside of the reactor containment vessel is provided in the lower part of the reactor containment vessel, and this The communication piping is provided with a relief valve that opens when the pressure in the pressure suppression chamber exceeds the set pressure, and a closing valve that closes when a set time elapses after the relief valve opens. A nuclear reactor containment facility is characterized by comprising:

[Embodiment 1 of the Invention A first embodiment of the invention will be described below with reference to FIG. 1. FIG. 1 is a schematic system diagram showing a first embodiment of the present invention, in which a dry well 11 houses a reactor pressure vessel 13, a connecting pipe 14, and associated valves and other equipment (not shown). A pressure suppression chamber 15 in which pool water 16 is stored is provided adjacent to. A communication pipe 18 leading to the exhaust η110 is connected to the space of the pressure suppression chamber 15, and the communication pipe 18 is connected to the pressure suppression chamber 15 immediately after the coolant loss accident.
a relief valve 19 for rapidly releasing the non-condensable gas that has migrated into the space; and a closing valve 2 for preventing the atmosphere inside the containment vessel from being released to the environment during the accident invasion period.
0 is provided.

Note that the purpose can be achieved even if the relief valve 19 is a loveture disk or the like.

If a coolant loss accident occurs, the non-condensable gas such as nitrogen sealed in the dry well 11 and the coolant and steam flowing out from the fracture port will flow through the vent pipe 17 into the pool water 1.
6, the vapor is condensed, but the non-condensable gas is not condensed. Therefore, the non-condensable gas moves into the space of the pressure suppression chamber 15, and the pressure within the pressure suppression chamber 15 continues to rise.

When the simulated pressure rises to the set opening pressure of the relief valve 19, the non-condensable gas in the pressure suppression chamber space is discharged through the exhaust tower 10, so that the pressure inside the containment vessel does not rise any further. Therefore, it is not necessary to ensure pressure resistance corresponding to the state in which all the non-condensable gas has migrated to the pressure suppression chamber space, and the pressure resistance conditions can be relaxed.

Furthermore, it has become clear that a large amount of fission product gas could not be released from the fuel rods in the short time after such an accident, and releasing non-condensable gases into the environment would not harm the public. There is no risk of jeopardizing safety.

Next, a second embodiment of the present invention will be described with reference to FIG. This second embodiment is characterized in that the reactor containment vessels shown in the first embodiment are equipped with containment facilities that are shared by a plurality of reactor containment vessels (two reactor containment vessels in the figure). In FIG. 2, a reactor pressure vessel 43.43 is installed in a dry well 41.4i that forms the upper part of the reactor containment facility and has airtightness and pressure resistance. It is installed on top of the reactor pedestal 42.42. Also, inside this dry well 41.41 is a reactor pressure vessel 43.43.
The connecting pipes 44, 44 and valves and other equipment (not shown) belonging thereto are accommodated. Further, a pressure suppression chamber 45.45 is provided adjacent to this dry well 41.41, and a large amount of pool water 46.46 is stored in this chamber. The dry well 41.41 and the pressure suppression chamber 45.45 are connected by a vent pipe 47.47, and the lower end of this vent pipe 47.47 is connected to the pool water 46.45.
It is open in 46. and pressure suppression chamber 25.2
A pipe branching to the storage Mpi 31 is provided via a valve 32 in the middle of the communication pipe 28.28 leading from the empty part 12!1 of the exhaust tower 10a. Immediately after the loss of coolant accident, the pressure suppression chamber 25.
A relief valve for rapidly releasing the non-condensable gas that has migrated into the space of 25. 29. A closing valve 30 is also provided to prevent the atmosphere inside the containment vessel from being released to the environment for a long period of time after the accident. Further, the storage facility 31 is housed in a common building 36 installed between several storage facilities. This common building 36 includes a blower 33, which is an emergency gas processing device. A filter 34 and an emergency power source (not shown) for feeding power thereto are housed.

With the above configuration, the actions of each device within the scope of a design basis accident are the same as in the first embodiment. If for some reason an accident that exceeds the design basis accident occurs, damage to the reactor core progresses, and a large amount of fission gas is released, hydrogen is generated by water-metal reaction, and the pressure inside the containment vessel continues to rise. In some cases, it is not desirable to continue discharging the atmosphere inside the containment vessel from the exhaust tower through the pipe 28.

Therefore, the presence of radioactivity in the reactor containment vessel is monitored by a radiation monitor, and if the level of radiation becomes high, the valve 30
By closing the valve 32 and opening it to the containment 1A facility 31 with the valve 32 in between, it is possible to alleviate the increase in the pressure inside the containment vessel and prevent the release of fission product gas to the environment. The inside of the containment facility 1 can be kept inert at all times regardless of the shutdown of the adjacent reactor, which can be used even if the steam reactor core is damaged. 1. Even if generated hydrogen is allowed to flow in, it will not reach the flammability limit by itself. (Hydrogen partial pressure only increases.) On the other hand, for the Ml generated by radiolysis of water during the period after the accident, an igniter (electrical combustion of flammable gas Since the combustible gas can be combusted at a low concentration using a 35 or ordinary combustible gas concentration control system, there is no risk of jeopardizing the integrity of the containment vessel.

In this way, the containment facility 31 and the igniter 35 will dramatically improve the ability to respond to core 111 damage accidents that exceed design basis accidents, but due to their nature, there is no need to make them safety grade, so safety regulations etc. It is not subject to severe restrictions, can be easily shared between facilities, and can be installed without a significant increase in cost.

In addition, in this embodiment, a common building 36 is provided to house not only the containment facility 31 but also equipment that can be shared between plants, such as emergency gas processing equipment 33, 34 and emergency power sources (not shown) that supply power to these equipment. Shared use makes it possible to reduce building volume and reduce construction costs and time.

Here, FIG. 3 shows a schematic system diagram showing a third embodiment of the present invention. In Fig. 3, a dry well 41.4 forms the upper part of the reactor containment facility and has airtightness and pressure resistance.
A reactor pressure vessel 43.43 is installed inside the reactor pressure vessel 43.43, and this reactor pressure vessel 43.43 is installed on top of the reactor pedestal 42.42. Also, inside this dry well 41.4i is a reactor pressure vessel 43.43.
The connecting pipes 44, 44 and associated valves and other equipment (not shown) are accommodated therein. Further, a pressure suppression chamber 45.45 is provided adjacent to this dry well 41.41, and a large amount of pool water 46.46 is stored in this chamber. The dry well 41.41 and the pressure suppression chamber 45.45 are communicated with each other by a vent pipe 47.47, and the lower end of this vent pipe 47.47 is connected to the pool water 46.
It is open to 46°. And the pressure suppression chamber 45
, 45 to the exhaust tower 10b, there is a valve 5 in the middle of the communication pipe 48, 48 that connects to each communication pipe.
2.52. Immediately after the coolant loss accident, the pressure suppression chamber 45 was installed in this communication pipe 48.48.
A relief valve 49 for rapidly discharging non-condensable gas that has migrated into the space, and a port for preventing the atmosphere inside the containment vessel from being released to the environment for a long period of time after the accident]
Four valves 50 are provided.

Further, the common building 56 is installed between the storage facilities for the number of units. This common building 56 has a blower 53 which is an emergency gas processing device. A filter 54 and an emergency power source (not shown) for supplying power to the filter 54 are housed.

With the above configuration, the third embodiment of the present invention is characterized in that instead of providing a containment facility that is shared between plants, the atmosphere inside the reactor containment vessel of the plant where the accident occurred is released into the reactor containment vessel of another plant. There is. This provides the same safety functions as the second embodiment, and at the same time has the advantage that it is not necessary to install a shared storage facility, and the design can be made at a lower cost.

[1. Advantageous Effects] As explained above, according to the present invention, since the pressure suppression chamber of the reactor containment vessel is provided with a communication pipe that is open to the atmosphere, the volume ratio of the dry well to the pressure suppression chamber space is restricted. It is possible to reduce the size of the containment vessel and reactor building, and to ease the pressure resistance conditions of the containment vessel.

[Brief explanation of drawings]

1 to 3 are schematic system diagrams showing the configuration of the reactor containment vessel showing the first to third embodiments of the present invention, respectively, and FIG. 4 is the configuration of the conventional reactor containment vessel. FIG. 1, 11.21.41...Drywell 2, 12
．． 22.42...Reactor pedestal 3, 13.23
．． 43...Reactor pressure vessel 5, 15.25.45...
・Pressure suppression chamber 6, 1G, 26.46...Pool water 7, 17.27.47. ...Vent pipes 18, 28.
48...Communication piping 19, 29.49...Relief valve 20, 30.50...Closing valve Agent Patent attorney Noriyuki Chika Yudo Hiroshi Mimata (Fig. 1~) Ma Fig. 4

Claims (1)

[Claims] (1) A reactor pressure vessel, a reactor containment vessel that stores the reactor pressure vessel, a reactor pedestal fixed to the bottom of the reactor containment vessel and supporting the reactor pressure vessel, and the reactor pressure vessel A pressure suppression chamber formed at the bottom of the vessel and containing a coolant therein, a dry well formed at the top of the reactor pressure vessel, and an upper part open to the dry well and a lower part containing the coolant in the pressure suppression chamber. In a reactor containment facility consisting of a vent pipe open to the inside, a communication pipe that communicates the pressure suppression chamber with the outside of the reactor containment vessel is provided at the lower part of the reactor vessel, and this communication pipe includes the pressure suppression chamber and the outside of the reactor containment vessel. An atom characterized by being provided with a relief valve that opens when the pressure in the room exceeds the design pressure, and a closing valve that closes when a set time has elapsed after the relief valve opened. Furnace containment equipment.