JPH03272495A - Exhaust equipment for emergency in reactor building - Google Patents

Abstract

PURPOSE:To enable prevention of a leakage of air having the possibility of radioactive contamination even when a reactor accident occurs, by connecting an exhaust fan of a regular ventilation system and a drier of an emergency gas disposal system together by an air duct provided with a switching valve. CONSTITUTION:When an accident occurs in a reactor, air 18 sent under pressure by an exhaust fan 7 proceeds to an air duct 22, and the quantity of air passing through an exhaust valve 9 at a normal time presses a switching valve 23. Since the switching valve 23 is fully opened instantaneously by an air pressure exceeding a normal level, then, the air 18 passes through this switching valve 23 and further a flow control valve 24 and reaches the upstream side of a drier 12. Due to the presence of a check valve 25, in this case, the air 18 flows into the drier 12 inevitably. Accordingly, the air does not return into the atmo sphere in a reactor building again through a flow control valve 11 and an inlet valve 10 and lower a negative pressure in the reactor building 1, and thus a leakage of the air having the possibility of radioactive contamination can be prevented.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention is designed to maintain a negative pressure inside the reactor building at all times even when an accident occurs in a nuclear reactor, and to maintain an emergency gas treatment system. This invention relates to a regular exhaust system for valves inside a reactor building that can safely release gas inside the reactor building through the reactor building.

(Prior art) The reactor building that houses the nuclear reactor in a nuclear power plant is always ventilated, but a filter device is installed inside the reactor building, so that in the unlikely event that a nuclear reactor accident occurs, radioactive materials will be removed from the reactor containment vessel. Even if a substance leaks, the gas inside the reactor building is filtered through this filter to remove radioactive substances before being released outside the reactor building.

FIG. 2 is a configuration diagram showing a gas ventilation/processing system in such a reactor building 1. As shown in FIG. The gas ventilation/processing system within the reactor building 1 includes a regular ventilation system 2 used during normal times and an emergency gas processing system 3 used in the event of an accident in the reactor.

The regular ventilation system 2 includes an air supply device 4 and an air supply fan 5 for dust treatment and temperature control installed outside the reactor building 1, an exhaust filter 6 and an exhaust fan 7 for dust treatment, and an air supply system 2 installed inside the reactor building 1. It consists of an air supply valve 8 and an exhaust valve 9 installed in the. The air supply device 4, the air supply fan 5, and the air supply valve 8 are connected in sequence, and the exhaust valve 9, the exhaust filter 6, and the exhaust fan 7 are connected in sequence.
are also connected sequentially.

On the other hand, the emergency gas treatment system 3 includes a large mouth valve 10 installed in the reactor building 1 and connected in sequence, a flow control valve 11, a drying device 12 equipped with an electric heater, a blower 13, a filter device 14 for removing radioactive materials, and It consists of an outlet valve 15. In the normal ventilation system 2 and the emergency gas treatment system 3, an accident signal 16 that notifies the reactor in the event that an accident occurs is transmitted to the air supply fan 5, air supply valve 8, exhaust valve 9,
, exhaust fan 7 , inlet valve 10 , flow control valve 11 , blower 13 and outlet valve 15 .

Reactor building 1 equipped with such a gas ventilation and treatment system
In normal times, outside air 17 from outside the reactor building 1 is taken in through the air supply device 4 of the regular ventilation system 2. Dust is removed from the outside air 17 by the air supply device 4, and its temperature is adjusted to match the temperature inside the reactor building 1.

Next, the outside air 17 discharged from the air supply device 4 is pressurized by the air supply fan 3 and supplied into the reactor building 1 via the air supply valve 4 .

Furthermore, air 18 within the reactor building 1 is guided outside the reactor building 1 through the exhaust valve 9 and guided to the exhaust filter 6. Then, the exhaust gas 19 from which dust has been removed after passing through the exhaust filter 6 is pumped by an exhaust fan 7, and is discharged into the atmosphere from an exhaust tower 20 having an exhaust port at a high place away from the human body.

Here, the artificial valve ↑0, the flow rate control valve 11, and the outlet valves 1 and 5 of the emergency gas treatment system 3 are closed, and the blower 1
3 is stopped. Therefore, the air 18 inside the reactor building 1 does not enter the emergency gas treatment system 3.

However, in the event that an accident occurs in the nuclear reactor, the accident signal 16 is input to the air supply fan 5, air supply valve 8, exhaust valve 9, and exhaust fan 7 of the regular ventilation system 2. As a result, the air supply fan 5 and the exhaust fan 7 are stopped, and the air supply valve 8 and the exhaust valve 9 are stopped.
will operate urgently.

On the other hand, the same accident signal 16 is generated by the large mouth valve 10 of the emergency gas treatment system 3, the flow control valve 1, the blower 13, and the outlet valve 5.
is also entered. Then, the inlet valve 10, flow control valve 11, and outlet valve 15 are opened, and the blower 3 starts operating. Therefore, the air 18 in the reactor building 1 passes through the large mouth valve 10 and the flow control valve 11 and advances to the drying device 12 . After being heated and dried by an electric heater and brought into a state suitable for removing radioactivity in the filter device 14, it is pressure-fed by the blower 13 and guided to the filter device 14.

Therefore, even if radioactive material leaks from the reactor containment vessel (not shown) due to a nuclear reactor accident and mixes with the air 18 in the reactor building 1, this radioactive material will be removed by the filter device 14. removed by various means. The exhaust gas 19 from which radioactive materials have been removed in this way passes through the outlet valve 15 and is discharged from the exhaust tower 20 into the atmosphere at a high place, as in normal times.

(Problem to be Solved by the Invention) However, in the emergency gas processing system 3 described above, after the accident signal 16 is input, the large mouth valve 10 and the flow rate control valve 1 are closed.
1 takes about 30 seconds to fully open. Also, a blower 13 that sends air 18 inside the reactor building 1 toward the outlet valve 15 is provided.
From the time it starts operating to the time it reaches rated operation, 2
It takes about 0 seconds. Therefore, there is a time delay of 30 seconds to 19 seconds from when the emergency gas processing system 3 receives the accident signal 16 to when it starts its predetermined operation.

If a nuclear reactor accident occurs and power is lost at the same time as a severe situation, emergency power equipment must be activated. For this reason, in such a case, there was a possibility that it would take one molecular degree more time before the emergency gas treatment system 3 started the prescribed operation.

By the way, it is impossible to maintain complete airtightness in the reactor building 1, and it is inevitable that there will be some gas leakage points. Therefore, even during normal times, the inside of the reactor building 1 is maintained at a slight negative pressure (several mmAq to 20 mmAq) by the regular ventilation system 2 to prevent radioactive materials from leaking from this leakage point. . However, immediately after a nuclear reactor accident occurs, even though the regular ventilation system 2 is stopped, the air 18 in the reactor building 1 does not flow smoothly through the emergency gas treatment system 3 for the reasons mentioned above. For this reason, air 18
may remain in the reactor building 1, and the negative pressure within the reactor building 1 may become uncontrolled.

In this case, in addition to the outside air constantly leaking in depending on the leakage rate of the reactor building 1, the air 18 inside the reactor building 1 thermally expands due to heat radiation from the heating elements inside the reactor building 1. Therefore, the negative pressure inside the reactor building 1 will decrease. When this happens, the air 1 inside the reactor building 1
Even if 8 were to be contaminated with radioactive materials, there is a possibility that the radioactive materials would not pass through the filter for removal and would leak from the leakage point in the reactor building 1 to a lower location.

The present invention was made in view of the above circumstances, and even if an accident occurs in a nuclear reactor, the reactor building is always maintained at negative pressure, and the air from which radioactive materials have been removed is supplied via the emergency gas treatment system. The purpose of the present invention is to provide a regular-use exhaust system for valves inside the reactor building that can discharge air outside the reactor building.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a regular ventilation system that connects an exhaust fan and an exhaust valve that is closed in response to an accident signal;
In a reactor building equipped with an emergency gas treatment system that sequentially connects a drying device that operates in response to an accident signal, a blower and a filter device, and an outlet valve that opens and closes in response to an accident signal, the above-mentioned normal operation is carried out in a ventilation duct equipped with an on-off valve. Provided is a regular use exhaust equipment for a valve inside a reactor building, characterized in that an exhaust fan of a ventilation system is connected to a drying device of the emergency gas treatment system.

(Function) The reactor building internal valve normal exhaust equipment of the present invention pumps the air inside the reactor building by the exhaust fan in the normal ventilation system, as in normal times even if a nuclear reactor accident occurs. The exhaust valve is then closed, so air flows into the ventilation duct. Then, this air passes through an on-off valve that opens instantaneously, for example, by air operation, and reaches the drying device of the emergency gas treatment system. After that, as in normal times, this air passes through a blower and filter device, and even if it is contaminated with radioactive materials, this radioactive material is removed and released outside the reactor building.

(Example) The present invention will be described in detail below with reference to FIG.

FIG. 1 is a configuration diagram of a valve regular exhaust equipment 21 in a reactor building according to an embodiment of the present invention. The basic configuration of the reactor building internal valve regular exhaust equipment 21 according to this embodiment is not substantially different from that shown in FIG. Omitted.

The reactor building 1 is provided with a normal ventilation system 2 and an emergency gas treatment system 3 as shown in FIG. 2, but the exhaust filter 6 and exhaust fan 7 of the normal ventilation system 2 are arranged upstream of the exhaust valve 9. Ru. However, regarding the gas exhaust treatment in normal times, there is no difference in effect from that shown in FIG. 2. Further, although no accident signal is input to the exhaust fan 7, the exhaust valve 9 is immediately closed when the accident signal 16 is input, so that air 18 from which radioactive materials are not removed passes through the exhaust valve 9 and reaches the reactor building.] - Not released to the outside world. Furthermore, although the air supply device 4 and the air supply fan 5 are also installed within the reactor building 1 in this embodiment, this does not change the air supply capacity in any way.

Now, the reactor building internal valve regular exhaust equipment 21 is the regular ventilation system 2.
The ventilation duct 22 connects the exhaust fan 7 of the emergency gas treatment system 3 to the drying device 12 of the emergency gas treatment system 3.

The ventilation duct 22 includes an on-off valve 23 and a flow rate control valve 24, which are opened instantaneously by air operation from the exhaust fan 7 side. Further, in the emergency gas treatment system 3, a check valve 25 is provided upstream of the connection point of the ventilation duct 22 to prevent air from advancing toward the flow rate control valve 11 side.

In the reactor building internal valve regular exhaust equipment 21 having such a configuration, under normal conditions, the outside air 17 is introduced into the reactor building 1 through the air supply device 4, the air supply fan 5, and the air supply valve 8 in sequence. . The air 18 inside the reactor building 1 then passes through the exhaust filter 6, the exhaust fan 7, and the exhaust valve 9 to exit the reactor building 1, and is discharged as exhaust air 19 from the exhaust tower 20 into the atmosphere at a high place. During this normal period, negative pressure is maintained within the reactor building 1.

Further, when an accident occurs in a nuclear reactor, an accident signal 16 is inputted to the air supply fan 5, air supply valve 8, and exhaust valve 9 of the regular ventilation system 2. Therefore, the air supply fan 5 is stopped and the air supply valve 8 is also completely closed, so that outside air 17 is prevented from flowing into the reactor building 1.

On the other hand, the exhaust valve 9 is also fully closed, but the exhaust fan 7 still operates. Therefore, the air 18 forced by the exhaust fan 7 advances to the ventilation duct 22, and the amount of air that passes through the exhaust valve 9 under normal conditions presses the on-off valve 23. Then, the on-off valve 23 is instantaneously fully opened by the air pressure exceeding the normal level, so the air 18 passes through this on-off valve 23 and also passes through the flow rate control valve 24 to adjust the flow rate to the emergency gas treatment system 3. It reaches the upstream side of the drying device 12 at. Note that the opening/closing mechanism of the opening/closing valve 23 is not limited to the above-mentioned pneumatic operation as long as it can be performed instantaneously.

Here, since there is a check valve 25, the air 18 always flows into the drying device r1112. Therefore, the flow rate control valve 11
It passes through the inlet valve 10 and returns to the atmosphere of the reactor building 1, so that the negative pressure inside the reactor building 1 is not reduced.

After the air 18 is dried in a drying device 12 to a state suitable for removing radioactivity through filter processing, the air 18 is passed through a blower 13.
is fed into the filter device 14 by. Finally, the air 18 from which radioactivity has been removed passes through the outlet valve 15 and reaches the exhaust tower 20, where it is discharged as exhaust air 19 into the atmosphere at a high altitude.

Therefore, according to the reactor building indoor valve regular exhaust equipment 20 according to this embodiment, in the event that a reactor accident occurs,
Air 18 within the reactor building 1 is instantly sent to the drying device 12 in the emergency gas treatment system 3. Therefore, even before the emergency gas treatment system 3 starts its scheduled operation, the air 18 inside the reactor building will not stagnate and the negative pressure will not drop, and even if the air 18 becomes contaminated with radioactivity, , this air 18
There will be no situation where the radioactivity is not removed and leaks from the reactor building 1.

At this time, even though it may take some time for the blower 13 to operate as described above, the air 18
is sufficiently fed into the filter device 14. Moreover, even if a power failure occurs simultaneously, the inertial force of the exhaust fan will guide the air 18 to the filter device 14 without any hindrance. Therefore, under any circumstances, the negative pressure inside the reactor building 1 is reliably maintained.

After the emergency gas treatment system 3 reaches its rated operation,
The process described above causes exhaust air 19 to be discharged into the atmosphere at altitude.

〔Effect of the invention〕

As explained above, the reactor building normal valve exhaust equipment of the present invention maintains negative pressure in the reactor building as in normal times even if a reactor accident occurs, and removes air that may be contaminated with radioactivity. can be prevented from leaking.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a normal valve exhaust system in a reactor building according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of a conventional regular ventilation system and an emergency gas treatment system in a reactor building. l... Reactor building, 2... Regular ventilation system, 3... Emergency gas treatment system, 7... Exhaust fan, 9... Exhaust valve, 12... Drying device, 13...・Blower, 14...
Filter device, 15... Outlet valve, 16... Accident signal, 22... Ventilation duct, 23... Open/close valve.

Claims (1)

[Claims] A regular ventilation system that connects an exhaust fan and an exhaust valve that closes when an accident signal is activated, and an emergency gas system that sequentially connects a drying device, blower and filter device that activates when an accident signal is activated, and an outlet valve that opens when an accident signal is activated. An emergency in a reactor building, characterized in that an exhaust fan of the normal ventilation system and a drying device of the emergency gas treatment system are connected by a ventilation duct equipped with an on-off valve in a reactor building equipped with a treatment system. exhaust equipment.