JPH0511878B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to ventilation equipment for a nuclear power plant that ventilates a housing section for accommodating a portable combustible gas concentration control device together with a nuclear reactor building. In particular, the present invention relates to ventilation equipment for a nuclear power plant that isolates a containment area from a reactor building when the ventilation equipment is shut down.

(Prior art) In general, in a nuclear power plant with a light water reactor such as a boiling water reactor, if a loss of coolant accident occurs, water-metal (zirconium) reactions and water radiation occur in the reactor containment vessel. Decomposition may generate flammable gases of hydrogen and oxygen.

If the concentration of these combustible gases (hydrogen) exceeds the flammability limit and combusts for some reason, the combustion will progress rapidly and there is a risk that the reactor containment vessel will be affected.

For this purpose, in the event of a loss of coolant accident, a combustible gas concentration control device is installed that guides the atmosphere inside the reactor containment vessel to a recombiner where hydrogen and oxygen react, and after recombination, flows back into the reactor containment vessel. A series, B
The system is installed with two redundant systems.

In addition, radioactive materials released into the reactor containment vessel during a loss of coolant accident leak from the reactor containment vessel, and for example, in the case of a boiling water nuclear power plant, they are further leaked into the reactor building of the secondary reactor containment facility. It can be stored. Emergency gas processing equipment is installed to prevent radioactive materials inside the reactor building from leaking into the environment. Regarding the emergency gas processing equipment, exhaust fans and valves, which are dynamic equipment, are provided with redundancy, for example, two systems are installed.

This emergency gas treatment system uses an exhaust fan to pass the atmosphere inside the reactor building through a high-performance particle filter and an iodine removal filter, and then discharges the atmosphere from the stack to the outside air. As a result, the pressure inside the reactor building is maintained at a lower pressure than the outside air.
It is possible to prevent radioactive materials inside the reactor building from directly leaking into the environment.

Conventionally, combustible gas concentration control devices have been fixedly installed within the reactor building of each nuclear power plant.

However, new knowledge has been obtained that the amount of combustible gases such as hydrogen and oxygen generated by radiolysis of water after a loss of coolant accident is much smaller than previously thought, and the recombiner It became clear that there was a considerable amount of time left before the system could be activated.

Therefore, it is conceivable that the combustible gas concentration control device, which has conventionally been installed in each nuclear power plant, be shared among a plurality of plants and made portable.

In this case, if a loss of coolant accident occurs as described above, the reactor building is full of radioactive materials that have leaked from the reactor containment vessel, so workers temporarily use a portable combustible gas concentration control system. If the worker attempts to enter the reactor building to install equipment, he or she may be exposed to large amounts of radiation.

Furthermore, after the accident, the inside of the reactor building was maintained at negative pressure by the emergency gas treatment equipment as mentioned above, but workers brought a portable combustible gas concentration control equipment into the reactor building. Therefore, if the equipment entrance of the reactor building is opened, the negative pressure inside the reactor building may not be maintained.

Therefore, the installation location of the portable combustible gas concentration control device is different from the conventional one, and is set in a location isolated from the reactor building. However, once the combustible gas concentration control device starts recombining the gas in the reactor containment vessel, radioactively contaminated gas will pass through the control device, so the inside of the control device storage area will also be put into emergency use. It is necessary to be able to draw air with a gas treatment device or equivalent. Furthermore, during normal operation of the nuclear reactor, it is necessary to clean the atmosphere by providing an appropriate amount of ventilation to the storage area surrounded by the isolation wall that houses the combustible gas concentration control device using some type of ventilation equipment.

Based on the above, in conventional nuclear power plants, the storage area that houses the combustible gas concentration control device is installed isolated from the reactor building, and under normal conditions, the storage area is ventilated using the ventilation equipment in the reactor building. After the toxic gas concentration control device is activated, the inside of this storage space is treated as a reactor building and treated with an emergency gas treatment device.

For this purpose, an air supply duct and an exhaust duct are provided for normal ventilation, which are opened from the ventilation equipment of the reactor building to the housing section.

(Problem to be solved by the invention) However, in such conventional nuclear power plants, in the event of a loss of coolant accident, the operation of the ventilation equipment in the reactor building is stopped, and leakage from the reactor containment vessel occurs in the reactor building. It is full of radioactive materials, and there is a risk that radioactive materials will further leak into the storage area through the air supply duct and exhaust duct. As a result, there is a risk that workers will be exposed to a large amount of radiation when transporting the combustible gas concentration control device.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide ventilation equipment for a nuclear power plant that can isolate a reactor building from a containment area in the event of a loss of coolant accident.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides an air supply duct that supplies air into a reactor building that further accommodates a reactor containment vessel that stores a reactor pressure vessel, and This portable flammable gas concentration control device is installed separately from the reactor building to reduce the concentration of flammable gas and can be carried in and out. An air supply branch duct and an exhaust air outlet that connect the inside of a housing section in which an equipment loading/unloading door for carrying in and out of a gas concentration control device is arranged isolated from the reactor building to the middle of the air supply duct and the exhaust duct, respectively. The ventilation equipment for a nuclear power plant has a branch duct, and the supply air duct, the exhaust duct, the supply air branch duct, and the exhaust branch duct are provided with radioactive materials from the reactor containment vessel to the reactor building. The reactor is characterized in that an isolation damper is provided, which closes when receiving an accident signal that is output when an accident that may cause leakage occurs, and isolates the accommodation section from the reactor building.

(Function) Under normal conditions, the reactor building communicates with the housing section via an air supply branch duct and an exhaust branch duct.

Therefore, in the unlikely event that a loss of coolant accident occurs in the reactor pressure vessel, radioactive materials may leak from the reactor pressure vessel through the reactor containment vessel and into the reactor building. . In this case, the radioactive materials are likely to leak into the containment area through the supply and exhaust branch ducts, but these supply and exhaust branch ducts are designed to prevent radioactive materials from leaking from the reactor containment vessel into the reactor building. Since the isolation damper is closed automatically by an accident signal generated in the event of an accident, it is possible to prevent radioactive materials from leaking into the storage space through the supply and exhaust branch ducts.

In addition, since the reactor building is isolated from the containment area by an isolation damper, it is possible to prevent operators and others from being exposed to large amounts of radiation when transporting the portable combustible gas concentration control device into the containment area. be able to.

In addition, even if the equipment loading/unloading door is opened to transport the combustible gas concentration control device into the storage area, the reactor building is already isolated from the storage area and there is no communication, so airtightness is maintained. It is possible to maintain negative pressure inside the reactor building by operating the emergency gas treatment equipment.

(Example) Examples of the present invention will be described below with reference to FIGS. 1 to 3. Note that in the drawings, common parts are denoted by the same reference numerals.

FIG. 1 shows the overall configuration of an embodiment of the present invention, in which a reactor building 1 houses a reactor containment vessel 2 that houses a reactor pressure vessel (not shown).

The reactor building 1 is equipped with a ventilation equipment 3 having an air supply duct 3A for supplying outside air into the interior thereof, and an exhaust duct 3B for exhausting the air inside from the stack 3C to the outside air. An air supply filter 4 and an air intake fan 5 are provided in the exhaust duct 3B, and an exhaust filter 6 and an exhaust fan 7 are provided in the exhaust duct 3B, respectively.

In addition, the reactor building 1 includes an emergency gas treatment device 8.
is provided, which maintains negative pressure inside the reactor building 1 to prevent fission products leaking from the reactor containment vessel 2 from diffusing into the outside air in the event of an accident such as a loss of coolant accident. At the same time, the air inside the reactor building 1 is configured to remove radioactive substances from the air through a processing filter device 8B using a fan 8A, and then to be discharged from a stack 3C to a high place into the outside air.

Accommodation section 10 erected adjacent to reactor building 1
is formed into an airtight structure housing the combustible gas concentration control device 11, and the combustible gas concentration control device 11
It has an equipment loading/unloading door (not shown) separated from the reactor building for loading and unloading, and includes an air supply branch duct 12, an exhaust branch duct 13, and a plurality of communication ducts 1.
4 and 15, it communicates with the reactor building 1.

The combustible gas concentration control device 11 controls when hydrogen is generated due to water-metal reaction or radiolysis.
This device sucks gas in the reactor containment vessel 2, combines hydrogen and oxygen in the gas with a recombiner, and prevents rapid combustion of hydrogen.
1A and 11B are housed in one housing section 10 as a set.

The supply air branch duct 12 branches from the inner end of the supply air duct 3A extending into the reactor building 1 and opens in the housing part 10, and the exhaust branch duct 13 is an exhaust duct 3B extending into the reactor building 1. It branches from the inner end and opens in the housing part 10.

Therefore, if the operation of the ventilation equipment 3 is stopped due to a loss of coolant accident, etc., the housing section 10 of the reactor building 1
are communicated with through an air supply branch duct 12 and an exhaust branch duct 13.

Further, the reactor building 1 and the housing section 10 communicate with each other through a plurality of communication ducts 14 and 15.

Therefore, in the middle of the supply air branch duct 12, the exhaust branch duct 13, and each communication duct 14, 15, which communicate the reactor building 1 and the housing section 10, radioactive materials are transported from the reactor containment vessel 2 into the reactor building 1. A plurality of isolation dampers 16 are installed to close the duct in response to an accident signal (hereinafter simply referred to as an accident signal), for example, a loss of coolant accident signal, which is output when an accident that may cause a leakage of coolant occurs. Two dampers are installed in series, and by closing all isolation dampers 16, the reactor building 1 can be isolated from the accommodation section 10.

In addition, two isolation dampers 16, for example, are installed in series in the middle of the air supply duct 3A and the exhaust duct 3B, so that the reactor building 1 is isolated from the outside air when all of these isolation dampers 16 are closed. It's getting old.

Both isolation dampers 1 of these communication ducts 14 and 15
6 are each supplied with power from an independent power source and are automatically operated by each drive device (not shown).

Next, the operation of this embodiment will be described.

During normal reactor operation, all the isolation dampers 16 are opened, and each area in the reactor building 1 and the inside of the housing section 10 are ventilated by the ventilation equipment 3, and fresh air is removed from the supply air duct 3A and the supply air branch duct 12. While outside air is taken in, it is discharged from the stack 3C to the outside air through the exhaust duct 3B and the exhaust branch duct 13.

Here, in the unlikely event that radioactive materials leak from the reactor containment vessel 2 into the reactor building 1,
For example, when a loss of coolant accident occurs, the emergency gas treatment device 8 automatically starts up immediately and guides the gas inside the reactor building 1, which is filled with radioactive materials leaking from the reactor containment vessel 2, to the treatment filter device 8B. Attenuate radioactivity and stack 3C with fan 8A
It is released into the outside air at a high place. At the same time, reactor building 1
The pressure inside the reactor building 1 is maintained at a lower pressure than the atmosphere, thereby preventing the gas inside the reactor building 1 from directly leaking into the environment.

On the other hand, in response to the coolant loss accident signal, the operation of the ventilation equipment 3 is immediately automatically stopped, all isolation dampers 16 are immediately closed, and the supply and exhaust ducts 3A and 3B, the supply and exhaust branch ducts 12 and 13, and each communication duct 14,
15 is immediately closed, and the reactor building 1 is isolated from the outside air and the housing section 10.

This prevents radioactive gas from entering the reactor building 1 into the housing section 10, so workers who are exposed to radiation when transporting the combustible gas concentration control device 11 into the housing section 10 are exposed to radiation. The amount can be greatly reduced. After the combustible gas concentration control device 11 has been carried into the storage section 10 and installed, the worker leaves the storage section 10, and the combustible gas concentration control device 11 is operated, the combustible gas concentration control device 11 is Since the radioactively contaminated gas in the reactor containment vessel 1 passes through the gas concentration control device 11, it is necessary to exhaust the gas in the storage section 10 to the outside air by the emergency gas treatment device 8.

Therefore, the isolation dampers 16 of the various communication ducts 14 and 15 are opened by remote manual operation to spatially communicate the reactor building 1 and the accommodation section 10, and the accommodation section 10 is maintained at a negative pressure and radioactive materials are released. Prevents gas from leaking into the outside air.

In addition, in the embodiment of the present invention described above, the reactor building 1 and the accommodation section 10 were explained separately, but the reactor building 1 and the accommodation section 10 only need to be configured separately, and can be integrated as one building. It may be configured as follows.

FIG. 2 shows the overall configuration of another embodiment of the present invention, and this embodiment includes each communication duct 1 of the embodiment of FIG.
4 and 15 are omitted, and each isolation damper 16 is provided at a portion of the exhaust branch duct 13 extending into the accommodation portion 10 so as to be manually operable. When a loss of coolant accident occurs, all isolation dampers 16 are closed in response to the accident signal to isolate the reactor building 1 from the accommodation section 10.

Thereafter, the combustible gas concentration control device 11 is carried into the housing section 10, and after the installation is completed and the worker leaves the housing section 10, each isolation damper 16 of the exhaust branch duct 13 is operated by remote manual operation. By canceling the accident signal and opening the reactor building 1, the reactor building 1 and the housing section 10 are spatially communicated with each other. Therefore, due to the operation of the emergency gas treatment device 8, the gas in the storage section 10 is transferred to the exhaust branch duct 13 and the exhaust duct 3.
The radioactive gas is discharged from the stack 3C to the outside air through the gas B, and the inside of the storage section 10 is maintained at a negative pressure, thereby preventing the radioactive gas from leaking to the outside. Each isolation damper 16 of the exhaust branch duct 13 is automatically operated by a drive device supplied with power from each independent power source (not shown), but if one of the isolation dampers 16 does not open due to loss of power, etc. The isolation damper 16 is opened by manual operation. Therefore, each isolation damper 16 of the exhaust branch duct 13 is installed within the housing part 10.

FIG. 3 shows still another embodiment of the present invention, in which, for example, two combustible gas concentration control devices 1
This is an embodiment in which accommodating portions 10 each accommodating one unit 1A and 11B are provided in individual units 10A and 10B, respectively.

As shown in FIG. 3, in this embodiment, the tip of the air supply branch duct 12 branches into two forks 12A, 12B and extends into the respective accommodating parts 10A, 10B, and similarly, the tip of the exhaust branch duct 13 also branches. 2 prongs 13A, 13B
It branches into each housing part 10A, 10B,
Each housing section 10A, 10B is supplied and exhausted.

In addition, these air supply branch ducts 12A, 12B
An isolation damper 16 is provided in the middle of the exhaust branch ducts 13A and 13B, which closes in response to an accident signal in the event of a loss of coolant accident, for example.

Therefore, in the event of a loss of coolant accident, all isolation dampers 16 are automatically closed, and each housing section 10A, 10B
is isolated from the reactor building 1, and it is possible to prevent radioactive substances from leaking from the reactor building 1 to the respective housing sections 10A and 10B.

In addition, if the combustible gas concentration control devices 3A, 3B that were brought in after the accident have been isolated, the gas in each accommodation section 10A, 10B will be converted into emergency gas. Processing device 8
It is necessary to maintain the pressure inside each housing part 10A, 10B at a pressure lower than that of the atmosphere.

For this purpose, each combustible gas concentration control device 11
A, 11B are carried into each storage section 10A, 10B, installation is completed, and the worker installs each storage section 10A, 11B.
After exiting from 10B, each exhaust branch duct 13
By releasing the accident signal and opening each isolation damper 16 of A and 13B by remote manual operation,
Each storage section 10A, 10B is spatially communicated with the reactor building 1.

According to this embodiment configured in this manner, even if either one of the two combustible gas concentration control devices 11A, 11B fails, the other one can control the temperature inside the reactor containment vessel 2. The concentration of flammable gas can be reduced.

In addition, in this embodiment, unlike each of the above-mentioned embodiments, one isolation damper 16 is installed in each of the air supply and exhaust ducts 12 and 13, but both housing portions 10A and 10B
Since either one of the two can be isolated from the reactor building 1 and communicated with the other, there is no problem.

〔Effect of the invention〕

As explained above, the present invention provides an isolation damper that is closed when an accident in which radioactive materials may leak from the reactor containment vessel into the reactor building occurs and an accident signal output from the accident is received. As a result, the accommodating section can be isolated from the reactor building, so it is possible to reduce the amount of radiation exposure of workers when the flammable gas concentration control device is carried into the accommodating section and installed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the overall configuration of an embodiment of ventilation equipment for a nuclear power plant according to the present invention, FIG. 2 is a schematic diagram showing the overall configuration of another embodiment of the present invention, and FIG. FIG. 3 is a schematic diagram showing the overall configuration of still another example. 1... Reactor building, 2... Reactor containment vessel, 3
...Ventilation equipment, 3A...Air supply duct, 3B...Exhaust duct, 8...Emergency gas processing device, 10,1
0A, 10B...accommodating section, 11, 11A, 11B
...Flammable gas concentration control device, 12, 12A, 1
2B...Air supply branch duct, 13, 13A, 13B
...Exhaust branch duct, 14,15...Connection duct, 16...Isolation damper.

Claims (1)

[Scope of Claims] 1. An air supply duct that supplies air into a reactor building that further accommodates a reactor containment vessel that houses a reactor pressure vessel, and an exhaust duct that exhausts air inside the reactor building to the outside. and a portable combustible gas concentration control device that is installed separately from the reactor building and can be carried in and out to reduce the concentration of flammable gas, and the portable combustible gas concentration control device can be carried in and out. A nuclear power plant having an air supply branch duct and an exhaust branch duct that connect the inside of a housing part in which an equipment loading/unloading door is arranged to be isolated from the reactor building to the middle of the air supply duct and the exhaust duct, respectively. accident in which radioactive materials may leak from the reactor containment vessel into the reactor building into the ventilation equipment, and into the supply air duct, the exhaust duct, the supply air branch duct, and the exhaust branch duct. 1. A ventilation system for a nuclear power plant, characterized in that isolation dampers are provided, each of which closes when receiving an accident signal output when an accident occurs to isolate the accommodation section from the reactor building. 2. The ventilation equipment for a nuclear power plant according to claim 1, wherein at least two isolation dampers are provided in series. 3. The ventilation equipment for a nuclear power plant according to claim 1 or 2, wherein the accident signal is a loss of coolant accident signal that is output when a loss of coolant accident occurs in a reactor pressure vessel.