JPS5952796A - Combustible gas concentration control system - 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 the Invention] The present BA relates to combustible gas concentration control equipment in nuclear couplants, and in particular to suppress the concentration of hydrogen and oxygen in order to ensure the safety of nuclear reactor containment facilities. The present invention relates to a combustible gas basic level control device provided for.

[Technical background of the invention and its problems]

Conventionally, in boiling water nuclear power plants, hydrogen and oxygen generated when a facility related to the secondary cooling system fails or is damaged is trapped in the reactor containment vessel, and the combustible gas concentration control system Side legs are provided to keep concentrations below flammability limits.

Because the reactor containment vessel is an engineering facility, it is essential that the hydrogen and oxygen trapped inside the reactor containment vessel leak into the secondary reactor containment facility at a certain leakage rate. Hydrogen and oxygen leaked into the secondary containment facility are diluted by air flowing in from the outside, and are discharged into the atmosphere from the exhaust stack through the entire emergency gas treatment chamber 41.

Therefore, in the conventional combustible gas concentration control neck device,
If there was a function to process only the hydrogen and oxygen in the reactor containment vessel, there would be no risk that hydrogen leaking from the reactor containment vessel would accumulate in the secondary containment tIfA facility and the hydrogen concentration would rise to the flammability limit. There wasn't.

On the other hand, in recent years, in order to diversify energy sources and move away from oil, plans have been made to use nuclear reactors for multiple purposes, and in the case of nuclear reactors for multiple purposes, they are often located close to consumption areas for reasons such as economic efficiency. It is hoped that To this end, it is necessary to increase the airtightness of the secondary containment facility and reduce public radiation exposure.
The amount of air flowing into the secondary containment facility from the outside is significantly reduced, and the dilution effect of hydrogen leaking from the reactor containment vessel into the secondary containment facility is significantly reduced. There is a concern that hydrogen concentration may increase (reaching the OT flammability limit) due to hydrogen accumulation within the facility.

Let us consider the following building configuration.

In this case, the leakage per unit time is as follows.

As a result, the inflow noise inside the secondary reactor containment facility is 2.08 rrv'hr in the atmosphere inside the reactor containment 8 and 1.04 nVhr in the atmosphere outside the secondary containment facility, and 1. The capacity is 2.08+1.04=3.12rIV'hr. Article 32 of the ``Ministry of Nuclear Energy, which establishes technical standards for nuclear power generation equipment,'' stipulates the limits for hydrogen and oxygen concentrations as follows.

Hydrogen concentration: 4% Oxygen concentration: 5% Therefore, it is assumed that the reactor containment vessel is currently filled with nitrogen gas and that the combustible gas concentration control system within the reactor containment vessel is controlled by focusing on the oxygen concentration. Then, it is conceivable that the hydrogen concentration in the reactor containment vessel could exceed 4%, for example, 7%.

In this case, the steady-state value of the hydrogen concentration inside the secondary containment facility is calculated as follows, and since there is air inside the secondary containment facility, it is possible that the flammability limit may be exceeded.

[Purpose of the invention]

The present invention has been made in consideration of these points,
It is an object of the present invention to provide a combustible gas concentration control system that can suppress the hydrogen and oxygen concentrations in a nuclear reactor containment vessel and also suppress the hydrogen concentration in a secondary reactor containment facility.

[Summary of the invention]

In the combustible gas concentration control system according to the present invention, a It is characterized by being connected,
This pipe sucks in hydrogen and oxygen leaking into the secondary containment facility, and the combustible gas concentration control device recombines the hydrogen and oxygen before releasing it back into the secondary containment facility. It is. As a result, it is possible to suppress the hydrogen and oxygen concentrations in the reactor containment vessel and also suppress the hydrogen concentration in the secondary reactor containment facility using the same combustible gas concentration control system.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

In the reactor containment vessel 12 containing the reactor pressure vessel 11,
It is stored in the secondary reactor containment facility 3.

The main piping (not shown) communicating from the inside of the secondary containment facility 3 to the inside of the reactor containment vessel 8 and 12 passes through the arm Izos 4-S 14 outside the reactor containment vessel 12 adjacent to the reactor containment vessel 12. It is configured to penetrate the wall of the reactor containment vessel 12.

Furthermore, in the event of failure or damage to facilities related to the primary cooling system, the secondary containment facility 3 is designed to prevent the integrity of the reactor containment facility from occurring in the event of an emergency by suppressing the concentration of hydrogen and oxygen that would be generated in the event of failure or damage. A combustible gas concentration control system is in place to maintain the combustible gas concentration.

The combustible gas concentration control system is usually provided with two independent systems, each consisting of a blower 21, a combustible gas concentration control device 22 consisting of a blade heater, a recombiner, a cooler, etc., and one end connected to an atomic The isolation valve 40a opens into the reactor containment vessel 12.
and a suction line device from the reactor containment vessel 12 which is connected to the combustible gas concentration control device η via the blower 21,
A discharge line from the combustible gas concentration control device 22 to the reactor containment vessel 12 that is open to the reactor containment vessel 12 via the isolation valve 40b, and the combustible gas concentration control device 22
There is a space line 5 which returns from the outlet side to the inlet side of the blower 21 via the gate valve, and one end of which returns to the inlet side of the blower 21.
The suction line B from the reactor containment vessel is connected to the downstream side of the isolation valve 40a via the isolation valve 40c.
26 and the combustible gas concentration control device 2
A discharge line ξ n connected from the outlet side of 2 to the suction line 33 from the reactor secondary containment facility 3 of the emergency recirculation gas treatment system via an intermediate isolation valve 40d. ing.

The emergency recirculation gas treatment system is for treating radioactive particles and radioactive iodine in the secondary containment facility 3, and is an emergency recirculation gas treatment system consisting of particle filters, waste filters, etc. a device 32 and one end of which is a secondary containment facility 3;
A suction line 33 from a secondary containment facility that is open to the inside and connected to the inlet side of the emergency recirculation gas treatment device 32 via a gate valve in the middle, and from the outlet side of the emergency recirculation gas treatment device 32 Secondary containment facility 3 via blower 31 and gate valve
A discharge line 34 to the Jinji Containment Vessel that is open to the inside, and an emergency recirculation gas treatment device 32 via a gate valve and an isolation valve.
The discharge line 35 to the emergency gas treatment system connects the outlet side of the emergency gas treatment system and the inlet side of the emergency gas treatment device 37.

The emergency gas treatment system is composed of a discharge line 35, an emergency waste treatment device 37, a blower 36, and a discharge line 38 to the exhaust stack 39. It functions to reprocess the air in the storage facility 3 and release it into the atmosphere from the exhaust stack 39.

Next, the operation of the flammable gas concentration Fljl control system having such a configuration will be explained.

In the unlikely event that hydrogen and oxygen are generated due to a failure or destruction of facilities related to the secondary cooling system, first one of the two systems will be
The isolation valve 40a above the suction line and the isolation valve 40b above the discharge line of the two combustible gas concentration control systems are opened, and the blower 21 and the combustible gas concentration control device n are operated at the same time. As a result, the hydrogen and oxygen released into the reactor containment vessel 12 are recombined, the concentrations of hydrogen and oxygen are suppressed, and the integrity of the reactor containment vessel 12 is maintained.

On the other hand, in the combustible gas concentration control system of another system, the isolation valves 140a and 40b are closed, and the isolation valve 40c on the suction tube 26 and the isolation valve PiIF and valve 41Jd on the discharge pipe 27 are closed.
At the same time, the blower 21 and the combustible gas concentration control device 22 are operated. As a result, hydrogen leaking from the reactor containment vessel 12 into the secondary containment facility 3 is recombined, the hydrogen concentration is suppressed, and the secondary containment facility 3
Internal health is maintained. However, since the atmosphere inside the secondary containment facility 3 is air, the oxygen concentration is not suppressed, and only the hydrogen concentration is suppressed to keep it below the flammability limit, thereby ensuring the integrity of the secondary containment facility 3. be able to.

If the combustible gas concentration of the two systems i11. l If a failure occurs in the l system of both systems, the remaining l system's flammable gas concentration side 6r11 system will remove hydrogen and oxygen from the reactor containment vessel] 2 and the secondary containment facility 3. The need for processing arises. In this case, the hydrogen and oxygen in the reactor containment vessel 2 is treated by operating the isolation valves 40a and 40b with the isolation valves 40a and 40b closed and the isolation valves 40c and 40d closed.
0 a, 40b closed, isolated 9P 40 c, 4
Secondary containment location by operating C1d open:
This is possible by alternately performing the hydrogen treatment in step 3.

Switch T2 is operated with the isolation valves 40a, 40b, and 40c open and the isolation valve 40d closed, and the air in the secondary containment facility 3 corresponding to the amount of leakage from the reactor containment vessel]2 is sucked in.・Combustible gas concentration control device 22 via ξINO 2G
An operation mode is also conceivable in which the reactor is discharged into the reactor containment vessel 12 from the discharge line 24 after being treated.

According to this operating mode, a considerable amount of leakage from the reactor containment vessel 12 is returned to the reactor containment vessel 12, so that when the reactor containment vessel 12 is cooled down after an accident,
Negative pressure inside the reactor containment vessel 12 is prevented.

In this embodiment, the suction pipe 26 is connected directly to the pipe space 14, but leakage from the reactor containment vessel 12 is most likely to occur in this space 14, and hydrogen leakage occurs locally. This is because it is easy to accumulate problems. Therefore, as in this embodiment.

An emergency recirculation gas treatment device is installed, and the air in the secondary containment facility 3 is recirculated in the event of an emergency, so that the air in the secondary containment facility 3 is mixed and hydrogen is diffused and homogenized. Inhalation, if that can be expected? Eve 26 I
There is no need to infiltrate the e-Ipsus S-S 14, and it is sufficient to leave the opening in the secondary containment facility 3 open. Furthermore, in order to mix the air in the secondary containment facility 3, it is not necessarily necessary to employ an emergency recirculation gas processing system, and it is sufficient to simply employ a dedicated lower. Furthermore, the other end of the discharge/ξ eve 27 may not be in contact with the suction line 33 of the emergency recirculation 4-gas treatment system, and the other end opening may be opened into the secondary containment facility 3. [Effects] As explained above, according to the present invention, in the unlikely event that a facility related to the primary cooling system malfunctions or is destroyed, the concentrations of hydrogen and oxygen generated during a demolition can be reduced using the same bacteriostatic system. Therefore, HIJ can be suppressed not only in the reactor containment facility but also in the secondary reactor containment role. Therefore, even if the secondary reactor containment vessel is stored in a secondary containment facility with a leakage density of 1%, hydrogen will not accumulate in the secondary containment facility. In addition, it is not necessary to separately install combustible gas concentration control devices for the reactor containment vessel and for the two-person containment/i'I!i crotch. Equipment can be rationalized and surgical efficiency can be improved.

[Brief explanation of drawings]

Figure 1 is a schematic flow diagram illustrating an embodiment of the present invention's combustible waste removal system. 12... Reactor containment vessel, 13... Reactor secondary containment facility, 22 ...Flammable gas policy control i1'll equipment,
2.3... Suction line from the reactor containment vessel, Sae...
- Discharge line to the reactor containment vessel, E... Suction from the secondary containment facility, ξ Eve, 27... Discharge to the secondary containment facility, ξ Eve, 40a, 40b, 40e. 40d...Isolation valve. Applicant's agent Kiyoshi Inomata

Claims (1)

[Claims] A flammable gas concentration control system located in the secondary reactor containment facility that houses the reactor containment vessel, and connected to the reactor containment vessel by an inlet line from the reactor containment vessel and a discharge line to the reactor containment vessel. In the combustible gas concentration control system equipped with the device, the suction line from the reactor containment vessel is connected to a suction line from a secondary reactor containment facility having an opening that opens into the secondary reactor containment facility. flammable, characterized in that the discharge line to the reactor containment vessel is connected to a discharge outlet to a secondary reactor containment facility having an opening that opens into the secondary reactor containment facility. Gas concentration control system.