JP2000230998A - Hydrogen ventilator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the safety of a nuclear power station by collecting hydrogen leaking in the air. SOLUTION: The hydrogen ventilator used in a nuclear power plant in which hydrogen is injected in the condensate system has a stick vent 18 attached to a seal water return pipe 19 at the shaft seal of a reactor water supply pump 11, a hood 22 placed above the stick vent 18, and a communication pipe 21 connected to the hood 22 for exhausting hydrogen, so that hydrogen leaking from the seal water return pipe 19 at the shaft seal of a reactor water supply pump 11 is collected with the hood 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydrogen ventilator used in a nuclear power plant for injecting hydrogen into a condensate system.

[0002]

2. Description of the Related Art In a nuclear reactor of a nuclear power plant, it has been recognized that dissolved oxygen in reactor water causes stress corrosion cracking in components of the nuclear reactor. This is particularly noticeable in older plants.

[0003] Therefore, a technique of reducing dissolved oxygen in reactor water by injecting hydrogen from a water supply system has been adopted.

FIG. 5 shows a system diagram of a typical nuclear power plant. The steam generated in the reactor 1 passes through the steam pipe 2, passes through the high-pressure turbine 3, the moisture separator 4, and the low-pressure turbine 5, condenses the steam in the condenser 6, converts the steam into low-pressure water, Water is supplied to the reactor 1 through a condensate pump 7, a high-pressure condensate pump 8, a low-pressure feedwater heater 9, a reactor feedwater pump 11, and a high-pressure feedwater heater 10.

In order to supply hydrogen to the reactor 1, hydrogen is injected from a hydrogen injection point 13 at the inlet of the high-pressure condensate pump 8 from a hydrogen injection device 13 into a flow of water in a condensate system.
Reactor 1 has been reached.

However, hydrogen injected into the condensate system may leak to the atmosphere from the shaft seal of the reactor water supply pump 11 downstream of the injection point. Reactor feed pump
FIG. 6 shows a representative example of the 11 shaft seals. The condensed water 17 flowing into the water supply pump casing 14 is pressurized by rotating the blades 16 mounted on the axle 15. On the other hand, part of condensate 17
Leakage water 20 passes through the gap between the feedwater pump casing 14 and the axle 15, part of which is diverted to the low-pressure feedwater heater 9, and the rest merges with the seal water from the outlet of the high-pressure condensate pump 8. As a seal water return pipe provided with a stick vent 18
The shaft seal structure discharges to the condensate recovery tank (not shown) through 19. By adopting such a shaft sealing structure, in order to reduce the pressure of the leak water 20 branched from a part of the condensate flowing into the feed water pump casing 14 to atmospheric pressure, a part of the leak water 20 is supplied with a low-pressure water supply. The pressure is reduced by flowing to the heater 9, and the pressure is further reduced by merging with the seal water from the outlet of the high-pressure condensate pump 8, and finally discharged to a seal water return pipe 19 having a stick vent 18 communicating with the atmosphere. By doing so, the pressure of the leak water is reduced to the atmospheric pressure.
By doing so, the condensate contained in the reactor water supply pump 11 is prevented from leaking out of the water supply pump casing 14.

The reactor feed pump 11 is installed in a reactor feed pump chamber 33.

The hydrogen injected into the condensate 17 is also contained in the leak water 20 from the shaft seal of the reactor water supply pump 11, so that the leak water 20 is sealed water. As the gas is discharged to the return pipe 19, it is discharged to the atmosphere from the opening of the stick vent 18 communicating with the atmosphere.

The stick vent 18 is provided with a drain receiver 32 for collecting water droplets condensed on the inner surface thereof.

[0010]

The building containing the reactor water supply pump 11 is placed in a closed room due to the unique building structure of a nuclear power plant. Therefore, a reactor water supply pump 11 is provided. Hydrogen released from the stick vent 18 in the reactor water supply pump chamber 33 has a ventilator in the reactor water supply pump chamber 33, so its concentration does not increase as a whole. Can be high. Naturally, when hydrogen reaches a certain concentration, there is a danger of burning and explosion. As a result, there is a problem that the stored hydrogen must be treated in order to prevent combustion and explosion of the hydrogen stored in the reactor water supply pump chamber 33 in which the reactor water supply pump 11 is installed.

The present invention has been made in view of the above points, and has as its object to provide a hydrogen ventilating apparatus capable of maintaining the safety of a nuclear power plant by collecting hydrogen leaking to the atmosphere. The purpose is.

[0012]

According to a first aspect of the present invention, there is provided a hydrogen ventilation system used in a nuclear power plant for injecting hydrogen into a condensate system. It has a stick vent attached to the seal water return pipe of the pump shaft sealing portion, a hood installed above the stick vent, and a communication pipe communicated with the hood and discharging hydrogen. To provide a hydrogen ventilator.

[0013] In the device configured as described above, hydrogen leaking from the seal water return pipe of the shaft seal portion of the reactor water supply pump can be collected by the hood.

According to a second aspect of the present invention, the apparatus further comprises a drain pan set at the top of the stick vent, and a wire mesh interposed between the drain pan and the hood. The invention provides a hydrogen ventilator as described.

In the apparatus configured as described above, hydrogen leaking from the seal water return pipe of the shaft seal portion of the reactor water supply pump can be collected by the hood integrated via the drain tray and the wire mesh. .

Further, in the invention according to claim 3, the drain receptacle is provided at the top of the stick vent and is formed integrally with the hood, and the drain receptacle is provided at at least one of the drain receptacle and the hood. The hydrogen ventilation device according to claim 1, further comprising a wire mesh.

In the apparatus configured as described above, it is possible to collect hydrogen leaking from the seal water return pipe of the shaft seal portion of the reactor water supply pump with the hood integrated with the drain pan.

According to a fourth aspect of the present invention, there is provided the hydrogen ventilating apparatus according to any one of the first to third aspects, wherein the communication pipe extends to an air conditioning duct.

In the apparatus configured as described above, hydrogen leaking from the seal water return pipe of the shaft seal portion of the reactor water supply pump can be collected by the hood and processed by the air conditioning duct.

[0020]

1 to 4 show an embodiment of a hydrogen ventilator according to the present invention.

FIG. 1 is a longitudinal sectional view of a first embodiment according to the present invention. In FIG. 1, the same portions as those in FIG. 6 are denoted by the same reference numerals, and the description of the configuration of the portions will be omitted.

A cylindrical hood 22 is attached so as to cover the stick vent 18 shown in FIG. The configuration is such that hydrogen leaking from the stick vent 18 is trapped by utilizing the property of floating upward. Here, the stick vent 18 is provided with a drain receiver 32 for collecting water droplets condensed on the inner surface thereof. The shape is not particularly limited depending on whether or not the drain receiver 32 is attached to the stick vent 18. hood
The hydrogen collected in 22 is connected to an existing air conditioning duct 31 through a communication pipe 21. The air conditioning duct 31 is an air conditioner (not shown)
Since the air conditioner is sucking the air at a pressure slightly lower than the atmospheric pressure, hydrogen is sucked from the communication pipe 21 and the hood 22 together with the air in the atmosphere.

Next, the operation of the present embodiment having the above configuration will be described.

According to the present embodiment, the stick vent 18
The hydrogen leaking from the water can be collected via a hood 22 attached so as to cover the stick vent 18 by utilizing the property that the hydrogen floats upward.

FIG. 2 is a longitudinal sectional view of a second embodiment according to the present invention.

FIG. 2 is a perspective view of a stick vent 26 shown in FIG.
A hood 22 and a communication pipe 21 are provided above the cylindrical drain receiving tray 23 so as to cover them. Since drain water may fall from the communication pipe 21 due to dew condensation or the like, the drain water is received by the drain tray 23, and the received drain water is discharged.
This is an embodiment in which a drain discharge pipe 24 is provided, and these are discharged to a funnel. Further, since the hood 22 and the drain tray 23 are separated from each other, a wire net 25 is provided to prevent dust or the like from entering.

Next, the operation of the present embodiment having the above configuration will be described.

According to the present embodiment, the stick vent 26
The hydrogen leaking from the hood 22 can be collected by the hood 22 mounted above the stick vent 26 via a wire mesh by utilizing the property that the hydrogen floats upward.

FIG. 3 is a longitudinal sectional view of a third embodiment according to the third aspect.

FIG. 3 shows a modification of FIG. 2, in which the communication pipe 21 and the stick vent 26 are formed as an integral cylindrical hood 28. The so-called hood 22 and the drain pan 23 in FIG.
Are integrated. A plurality of through holes 27 communicating with the atmosphere are provided on the side surface of the hood 28, and a wire mesh 25 is provided so that dust and the like do not enter the through holes 27.
Also in this embodiment, as in FIG.
24 are provided.

Next, the operation of the present embodiment having the above configuration will be described.

According to the present embodiment, the stick vent 26
Hydrogen leaking from the hood 28 can be collected by the hood 28 integrated with the stick vent 26 by utilizing the property that the hydrogen floats upward.

FIG. 4 is a reactor shaft sealing system diagram showing a fourth embodiment corresponding to claim 4. In FIG. 1, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description of the configuration of the parts will be omitted.

In FIG. 4, the hood 22 is provided so as to cover the stick vent 26 provided in the seal water return pipe 19. The communication pipe 21 connected to the hood 22 is connected to an existing air conditioning duct 31. Since the pressure in the air-conditioning duct 31 is set lower than the atmospheric pressure, the hood 22 sucks the hydrogen emitted from the stick vent 26 together with the atmospheric air.

When the air is sucked by the hood 22, the degree of vacuum in the air-conditioning duct 31 is generally high, which may cause an extreme suction.
A control valve 30 is provided in 21 to control the amount of suction in the hood 22. The control method includes a manual control method and an automatic control method for monitoring extreme suction.

Next, the operation of the present embodiment having the above configuration will be described.

According to the present embodiment, the stick vent 26
Can be collected by the air-conditioning duct 31 through the hood 22.

[0038]

According to the first aspect of the present invention, hydrogen leaking from the stick vent can be collected via the hood attached so as to cover the stick vent.
That is, the hydrogen injected into the condensate system collects hydrogen leaking from the seal water return pipe of the shaft seal of the reactor water supply pump, and accumulates hydrogen in a closed chamber such as the reactor water supply pump room. Can be prevented. Preventing this accumulation of hydrogen can greatly contribute to improving the safety and reliability of a nuclear power plant.

According to the second aspect of the present invention, hydrogen leaking from the stick vent can be collected by the hood mounted above the stick vent 26 via a wire mesh, and the hydrogen leaks from the reactor water supply pump chamber. Preventing the accumulation of hydrogen in a room can greatly contribute to improving the safety and reliability of a nuclear power plant.

According to the third aspect of the present invention, hydrogen leaking from the stick vent can be collected from the hood integrated with the stick vent, and the accumulation of hydrogen in a closed chamber such as a reactor water supply pump chamber. Prevention can greatly contribute to improving the safety and reliability of a nuclear power plant.

According to the fourth aspect of the invention, hydrogen leaking from the stick vent can be collected from the air conditioning duct through the hood, and the accumulation of hydrogen in a closed chamber such as a reactor water supply pump chamber can be performed. Prevention can greatly contribute to improving the safety and reliability of a nuclear power plant.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a hydrogen ventilation device according to the present invention.

FIG. 2 is a longitudinal sectional view showing a second embodiment of the hydrogen ventilator according to the present invention.

FIG. 3 is a longitudinal sectional view showing a third embodiment of the hydrogen ventilation device according to the present invention.

FIG. 4 is a longitudinal sectional view showing a fourth embodiment of the hydrogen ventilation device according to the present invention.

FIG. 5 is a schematic system diagram of a nuclear power plant to which the present invention is applied.

FIG. 6 is a longitudinal sectional view of a reactor water supply pump shaft sealing portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor, 2 ... Steam piping, 3 ... High pressure turbine, 4 ... Moisture separator, 5 ... Low pressure turbine, 6
・ ・ ・ Condenser, 7 ・ ・ ・ Low pressure condensate pump, 8 ・ ・ ・ High pressure condensate pump, 9 ・ ・ ・ Low pressure feed water heater, 10 ・ ・ ・ High pressure feed water heater, 11 ・ ・ ・ Reactor feed water Pump, 12: hydrogen injection point, 13: hydrogen injection device, 14: water supply pump compartment, 15: axle, 16: blade, 17: condensate, 18.
..Stick vents, 19 ・ ・ ・ Seal water return piping, 20 ・
..Leak water, 21 ... communication pipe, 22 ... hood, 23.
..Drain trays, 24 ... Drain discharge pipes, 25 ...
Wire mesh, 26: stick vent, 27: through hole, 28
..Hood, 29 ... Seal water injection pipe, 30 ... Control valve, 31 ... Air conditioning duct, 32 ... Drain receiver, 33 ...
・ Reactor feed pump room

Claims (4)

[Claims] 1. A hydrogen ventilator used in a nuclear power plant for injecting hydrogen into a condensate system, comprising: a stick vent attached to a seal water return pipe of a reactor water supply pump shaft sealing portion; A hydrogen ventilator, comprising: a hood installed in the hood; and a communication pipe connected to the hood for discharging hydrogen. 2. The hydrogen ventilator according to claim 1, further comprising a drain pan set at the top of the stick vent, and a wire mesh interposed between the drain pan and the hood. 3. A drain tray set at the top of the stick vent and formed integrally with the hood, and a wire mesh set in a through hole formed in at least one of the drain tray and the hood. The hydrogen ventilator according to claim 1, wherein 4. The hydrogen ventilator according to claim 1, wherein the communication pipe extends to an air conditioning duct.