JPH09211188A - Flammable gas concentration controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make on-line maintenance during operation possible by constituting arbitrary two systems in three systems of recombiner at stand-by state. SOLUTION: In two reactor containments 12a and 12b, a flammable gas concentration controller 1 placed with recombiners 20a, 20b and 20c is provided. Suction lines 15a and 15b of the containments 12a and 12b are connected to a header 2 via isolation valves 21a to 21h and three systems are separated from the header 2 to be connected to the recombiners 20a to 20c. The return lines 16a and 16b from the containments 12a and 12b are connected from the recombiners 20a to 20c to a header 3 and to suppression chambers 14a and 14b via isolation valves 22a to 22h. In the case an event generates in the containment 12a side, the flammable gas from the drywell 13a is sent to a recombiner 20a by the opening operation of isolation valves 21a to 21d and 22a to 22d. Hydrogen and oxygen in the gas react in the device 20a to be steam and after being cooled, it is returned to the chambers 14a and 14b. By continuing this process, the flammable gas concentration in the containments 12a and 12b can be controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustible gas concentration control device for suppressing the concentration of combustible gas generated in a nuclear reactor containment vessel to below a flammable limit after a loss of coolant in a nuclear power plant.

[0002]

2. Description of the Related Art Conventionally, in order to prevent the combustible gas concentration of hydrogen and oxygen generated in a reactor containment vessel (hereinafter referred to as PCV) after a coolant loss event from increasing excessively, a combustible gas (hydrogen , Oxygen) concentration below the flammability limit is provided with a flammable gas concentration suppression system (hereinafter referred to as FCS).

The FCS is composed of a recombining device, pipes and valves, and reacts hydrogen and oxygen accumulated in the PCV drywell into water, which is returned to the PCV suppression chamber.

In the conventional FCS, two systems of 100% capacity recombination devices are installed so that they can fully function even if a single failure of a dynamic device occurs. That is, even if one system fails, the other one system can function.

An example of this type of device is a technique number 8
No. 6-2616, Invention Society Open Technical Report is known. Hereinafter, a conventional example of the combustible gas concentration control device will be described with reference to FIG. As shown in FIG. 5, in the flammable gas concentration control device, two recombination devices 10a and 10b are permanently installed in the FCS chamber 11. Reactor containment vessels 12a and 12b are dry wells 13a and 13b and suppression chamber 1.
It has 4a and 14b. Dry well 13a, 13
b from suction line 15a, 15b and return line 16a, 1 to suppression chamber 14a, 14b
6b is provided with a tie line, and a plurality of reactor containment vessels 12
The FCS recombination device is commonly used for a and 12b.

[0006]

In the conventional flammable gas concentration control device described above, it is necessary to operate two units simultaneously in consideration of a single failure. Therefore, when the combustible gas concentration control device is shared between the two plants, basically one plant or two plants are always operating unless a periodic inspection is performed at the same time. When inspecting the flammable gas concentration control device, one line became inoperable,
It was necessary to carry out the inspection period for a short period because only one other line of operation was required.

The present invention has been made in consideration of the above conventional circumstances, and an object thereof is to provide a combustible gas concentration control device capable of performing online maintenance even during operation of a nuclear reactor and not restricted in inspection period. To do.

[0008]

In order to achieve the above object, in the combustible gas concentration control device of the present invention, in the invention according to claim 1, a reactor having two branched ends and two end portions is provided. Hydrogen and oxygen are connected to the drywell of the containment vessel, are branched into three systems through the isolation valve and the header, and each have a switching valve in the middle, and are connected to the other end of the three systems of the suction line. 3 reconnecting device for reconnecting, and the end is connected to the 3 reconnecting device, and each is separated into 2 systems through a switching valve and a check valve and a header, and each isolation valve is in the middle. It has a return line having the other end of the two systems connected to the suppression chamber of the reactor containment vessel.

Further, according to the invention described in claim 2, according to claim 1,
In the combustible gas concentration control device described above, three recombining devices are stored in one building, and a switching valve for the suction line and a switching valve for the return line are installed in the building. .

According to the third aspect of the invention, the ends of the two independent systems are connected to the dry wells of the two reactor containment vessels, respectively, the isolation valve, the flange coupling parts of the two systems, and the flanges of the two systems. A suction line having an expansion joint provided on one of the joints, a suction side flange and a return side flange for connecting to the expansion joints of the suction lines of these two systems, and recombining hydrogen and oxygen. Three systems of recombiners are connected to each other through expansion joints provided on one of the two flange joints provided on the return side flange of the three systems of recombiners, and isolated via check valves. A return line having a valve and having the other end connected to the suppression chamber of the containment vessel.

According to a fourth aspect of the present invention, in the combustible gas concentration control device according to the third aspect, three systems of the flange fitting portion provided on the suction line and the flange fitting portion provided on the return line are provided. Is characterized by.

According to a fifth aspect of the present invention, in the combustible gas concentration control device according to the third and fourth aspects, the recombining devices of three systems are stored in one building, and the flange joint portion is stored in the building. It is characterized by being done.

According to a sixth aspect of the present invention, in the combustible gas concentration control apparatus according to the first to fifth aspects, the three recombining devices are cooled by independent three residual heat removal systems. And

In the flammable gas concentration control device having the above-mentioned configuration, by keeping any two of the three recombiners in a standby state, the remaining one can be maintained online even while the reactor is in operation. You can Further, even if one series of the combustible gas concentration control device becomes inoperable, it is possible to continue the operation without stopping the reactor by the sound two series.

Further, in the invention according to claim 3, since there is no tie line between the plants in the pipe, the separability between the plants becomes good. Furthermore, in the invention according to claim 4, even if a single failure of the flange joint portion, for example, damage to the flange occurs, the combustible gas concentration control devices of two systems can be connected.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a combustible gas concentration control device according to the present invention will be described below with reference to FIG. FIG. 1 is a first diagram of a combustible gas concentration control device according to the present invention.
It is a block diagram of the embodiment of. Two reactor containment vessels 1
The flammable gas concentration control device 1 is provided at 2a and 12b. The FCS chamber 11 has recombiners 20a, 20b, 2
3 units of 0c are installed. Reactor containment vessel 12
The suction lines 15a and 15b penetrating the dry wells 13a and 13b of a and 12b are connected to the header 2 via isolation valves 21a to 21h. Further, three systems are separated from the header 2 and are branched and connected to the recombining devices 20a, 20b, 20c via the switching valves 23a, 23c, 23e.

Further, the return lines 16a and 16b to the suppression chambers 14a and 14b of the reactor containment vessels 12a and 12b are provided with recombiners 20a, 20b and 20c.
To switching valves 23b, 23d, 23f and check valve 24
connected to the header 3 via a, 24b, 24c,
The isolation chambers 22a to 22h are connected to the suppression chambers 14a and 14b. Check valves 24a, 2
4b and 24c are recombining devices 20a and 20b,
20c is another recombining device 20a, 20b, 20 in operation.
It is configured so that it can be supplied while preventing backflow from c. Further, the cooling water required for the recombining devices 20a, 20b, 20c is configured to be able to be supplied from a plurality of plants. In FIG. 1, (A), (B) and (C) indicate that one plant is connected, and (A ′), (B ′) and (C ′) indicate that they are connected to the other plant. .

For example, when a reactor coolant loss event occurs, cooling water is recombined from the residual heat removal system of the event-occurring plant by the recombination device 2
0a, 20b, 20c. For the cooling water, the main valves 25a to 25f on the cooling water supply side and the switching valves 26a, 26b, 2
It is supplied via 6c.

When a reactor cooling water loss event occurs in one of the plants, for example, an event occurs on the plant side of the reactor containment vessel 12a, isolation valves 21a to 21d on the suction side of the dry well 13a and suppression are suppressed. The combustible gas generated in the dry well 13a is sent to the recombiner 20a by the operation of opening the isolation valves 22a to 22d on the return side of the chamber 14a. In the recombination device 20a, hydrogen and oxygen in the gas react with each other to form water vapor. Further, after the steam is cooled to water by the supplied cooling water, the suppression chambers 14a, 14a, 14 are passed through the return line 16a.
Returned to b.

By continuously performing this process, the concentration of the combustible gas in the reactor containment vessels 12a and 12b is controlled. The combustible gas concentration controller is equipped with a 100% capacity recombination device so that it can fully function even if a single failure of a dynamic device occurs. Even if it occurs, it will be sufficiently processed.

When inspecting an arbitrary recombining device, for example, inspecting the recombining device 20a, the switching valve 23a,
By performing the operation of closing the switching valve 26a between the cooling water supply line 23b and the cooling water supply line and disconnecting it from the other two recombining devices 20b and 20c, online maintenance can be performed even while the reactor is in operation.

As is clear from the above results, the present invention has three series of recombination devices 20a, 20b, as shown in FIG.
By keeping any two series of the 20c in the standby state, the remaining one series can be inspected even while the reactor is operating. In addition, even if one line of the flammable gas concentration control device becomes inoperable for more than 10 days, which is a restriction on safety regulations, the two lines of sound gas should continue to operate without stopping the reactor. You can

FIG. 2 shows a second embodiment of the combustible gas concentration control device according to the present invention, in which the reconnection devices 20a, 20b, 20c and external pipes are connected to the permanent pipes shown in FIG. Instead, it is a flange joint using expansion joints. 2, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description of the configuration will be omitted. FCS room 11
At the suction lines 15a, 15b from the dry wells 13a, 13b, the suppression chamber 14a,
14b, return lines 16a and 16b, and cooling water supply lines and recombiners 20a and 20 from each plant.
The connection with b and 20c is a flange joint using expansion joints 31a to 31f and expansion joints 32a to 32c. A closing plate is attached to the flange to which the expansion joint is not connected. Normally, the recombination device 20a,
20c is connected to the external pipe by expansion joints, one for each plant. The remaining one line of the recombining device 20b is off-line. Switching valve 33 for cooling water supply line
The a to 33f are installed in the FCS chamber 11 so that they can be collectively operated.

When a reactor coolant loss event occurs in one of the reactors, the reconnection device 20b, which has been offline, is also connected to the external pipe by expansion joints 31c, 31d and 32b. The two series of cooling water supply lines of the recombining devices 20a and 20b corresponding to the event are connected to the expansion joints 32a and 32b so that the switching valves 33a and 33c are opened so as to be supplied by the cooling water system of the event occurrence side plant. Manipulate.

As is clear from the above results, according to the present invention, in addition to the effect described above with reference to FIG. 1, since there is no tie line between plants as shown in FIG. Become. In other words, if a reactor coolant loss event occurs in one plant, prevent the expected event that flammable gas diffuses to the other healthy plant side due to valve malfunctions in the piping that makes up the tie line. Therefore, the safety can be improved.

FIG. 3 shows a third embodiment of the combustible gas concentration control device according to the present invention, in which three flange fitting portions are provided. In FIG.
The same parts as those in FIG. 1 are designated by the same reference numerals, and the description of the configuration will be omitted. Even if there is a portion where the expansion joint cannot be connected due to damage to the flange or the like, it is possible to switch the connection to another flange and improve reliability.

FIG. 4 shows a fourth embodiment according to the present invention. When an event occurs in one plant, all three series of recombining devices 20a, 20b, 20c are set in the accident side plant. It is connected to the expansion joint.
4, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description of the configuration will be omitted. Recombination devices 20a, 20b,
If any two systems of 20c become inoperable, the remaining 1
The function can be exerted in series, and the reliability can be improved.

[0028]

As described above, in the combustible gas concentration control device of the present invention, online maintenance of the combustible gas concentration control device is possible even while the reactor is operating, and one recombining device operates. Even in the impossible state, the operation can be continued without stopping the nuclear reactor, and the safety and reliability of the nuclear power plant can be improved.

[Brief description of drawings]

FIG. 1 is a first diagram of a combustible gas concentration control device according to the present invention.
2 is a configuration diagram showing an embodiment of FIG.

FIG. 2 is a second flammable gas concentration control device according to the present invention.
2 is a configuration diagram showing an embodiment of FIG.

FIG. 3 is a third flammable gas concentration control device according to the present invention.
2 is a configuration diagram showing an embodiment of FIG.

FIG. 4 is a fourth combustible gas concentration control device according to the present invention.
2 is a configuration diagram showing an embodiment of FIG.

FIG. 5 is a configuration diagram showing a conventional example of a combustible gas concentration control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Combustible gas concentration control apparatus 2 ... Header 3 ... Header 10a, 10b ... Recombination apparatus 12a, 12b ... Reactor containment vessel 13a, 13b ... Dry well 14a, 14b ... Suppression chamber 15a, 15b ... Suction line 16a, 16b ... Return line 20a, 20b, 20c ... Recombination device 21a-21h ... Isolation valve 22a-22h ... Isolation valve 23a-23f ... Switching valve 24a, 24b, 2
4c ... Check valve 25a-25f ... Main valve 26a, 26b, 2
6c ... Switching valve 31a-31f ... Expansion joint 32a, 32b, 3
2c ... Expansion joint 33a to 33f ... Switching valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Sato 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock company, Toshiba Yokohama Works (72) Inventor Takeaki Tanaka, 8 Shinsita-cho, Isogo-ku, Yokohama, Kanagawa In-house company Toshiba Yokohama Works (72) Inventor Kaichi Masaki 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock Company Inside Yokohama Yokohama Works (72) In-house Mizuho 66-2, Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Inside Engineering Co., Ltd.

Claims (6)

[Claims] 1. An end portion of two branched systems is connected to a drywell of two reactor containment vessels, respectively branched to three systems via a isolation valve and a header, and each has a switching valve in the middle. A suction line, a recombination device of three systems connected to the other end of the three systems of this suction line for recombining hydrogen and oxygen, and an end portion connected to the recombination device of these three systems, and a check valve and a check valve, respectively. And a return line connected to the suppression chamber of the reactor containment vessel at the other end of the two systems, each of which is separated into two systems via a valve and a header. Combustible gas concentration control device. 2. The reconnection device for the three systems is stored in one building, and the switching valve for the suction line and the switching valve for the return line are installed in the building. Combustible gas concentration control device. 3. Independent end portions of two systems are connected to dry wells of two reactor containment vessels, and are respectively provided as isolation valves, flange joints of two systems, and one of the flange joints of these two systems. Recombining device of three systems for recombining hydrogen and oxygen, having a suction line having an expansion joint provided, and a suction side flange and a return side flange for connecting to the expansion joints of the suction lines of these two systems To the return side flange of the three-system recombining device via an expansion joint provided on one of the two flange joints provided, and each has a separate valve via the check valve and the other. A combustible gas concentration control device having an end connected to a suppression chamber of the containment vessel. 4. The combustible gas concentration control device according to claim 3, wherein the flange fitting portion provided on the suction line and the flange fitting portion provided on the return line are provided in three systems. 5. The combustible gas concentration control device according to claim 3, wherein the three-system recombining device is stored in one building, and the flange connection part is stored in the building. 6. The combustible gas concentration controller according to claim 1, wherein the three recombiners are cooled by three independent residual heat removal systems, respectively.