JPS6249958B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an emergency gas treatment device for a reactor building in a nuclear power plant, and more particularly to an abnormal negative pressure prevention device for the reactor building using the emergency gas treatment device for the reactor building.

Generally, the inside of a nuclear reactor building is maintained at a negative pressure state from a safety standpoint to prevent emergency gas generation from spreading outside.

On the other hand, since no abnormal negative pressure prevention device using an emergency gas treatment device in the reactor building in a nuclear power plant has been proposed, the detector that detects and sends out the isolation of the reactor building as a safety signal is
For example, (1) Nuclear reactor (pressure vessel) water level drop (L-
3), (2) High pressure in the containment vessel, (3) High radioactivity in the reactor building, or (4) High radioactivity in the refueling floor. (a) The emergency gas treatment system installed in the reactor building automatically starts up and increases the flow rate to the set value depending on the opening of the inlet flow control valve of the exhaust fan, and (b) Shut down the ventilation system. (c)Furthermore, the reactor building is completely isolated from the supply and exhaust ducts, and the emergency gas treatment system is used to reduce the pressure to a negative pressure value appropriate to its airtightness, thereby preventing leakage of emergency gas from the reactor building. I'm starting to do that.

In this way, inside the reactor building with good airtightness,
Since the pressure becomes abnormally negative with respect to the outside air, it is necessary to reduce the flow rate of the exhaust fan of the emergency gas treatment system.

However, the above-mentioned emergency gas treatment system has problems such as surging of the exhaust fan and overheating inside the train due to the heater built into the filter train due to the reduced pressure (negative pressure) in the reactor building. . Furthermore, if the heating heater is manually switched and stopped in order to suppress the overheating phenomenon in the train, there are drawbacks such as an increase in the humidity of the activated carbon filter in the train.

On the other hand, when operating the emergency gas treatment system to perform a filter performance test using the filter train during periodic inspections in a nuclear power plant, the emergency gas treatment system may Because the reactor building is a reactor building, for example, not only is work inside the reactor building forced to be interrupted to purify the indoor air, but during periodic reactor building leak tests, the huge building It is difficult to maintain a constant pressure difference with the atmosphere (outside air) at all times, so each time a leak test is conducted, a comparison is made with past leak test results under the conditions of flow rate and pressure difference. It is difficult to detect how the airtightness of the furnace building has changed from before.

In other words, under the above differential pressure conditions in the reactor building, the tightness of the reactor building's opening/closing doors, the leakage conditions of various seals, etc. cannot be reproduced as they were under the previous differential pressure conditions. Have difficulty.

In view of the above-mentioned points, the present invention connects an outside air intake pipe of an air supply chamber to an exhaust duct located between an isolation valve and a flow rate detector in an emergency gas treatment system of a nuclear reactor building. A check damper and a flow control valve are provided in the reactor building, and a differential pressure transmitter is provided in the reactor building that is connected to the flow control valve and detects and transmits the differential pressure in the reactor building. When the emergency gas treatment system is activated by a reactor building isolation signal, it prevents abnormal negative pressure within the reactor building and maintains a constant differential pressure value (negative pressure) between the reactor building and outside air.
An emergency gas treatment system that prevents the occurrence of surging in the exhaust fan due to a flow rate reduction that exceeds the flow rate limit value, and also enables standalone operation tests to measure the amount of leakage from the emergency gas treatment system. It provides:

Hereinafter, the present invention will be described with reference to an illustrated embodiment.

In the figure, reference numeral 1 is a reactor building constructed with a control shield, and inside this reactor building 1, a containment vessel (dry well) 3 containing a pressure vessel 2 as a nuclear reactor is installed. There is.
Also, on one side of the reactor building 1, there is an outside air louver 4a.
An air supply chamber 4 equipped with an air supply chamber 4 is provided so as to communicate with the inside of the building via an air supply duct 5. Supply air isolation valves 7a and 7b are installed. Further, the supply air duct 5 that is led into the reactor building 1 is provided with the containment vessel 3.
An air supply pipe 8a of the air control system piping 8 is provided, which communicates with the air control system piping 8, and each on-off valve 9, 10 is provided in this air supply pipe 8a. Furthermore, an exhaust pipe 8b of the air control system piping 8 is connected to the other side of the containment vessel 3, and each on-off valve 11, 12 is connected to the exhaust pipe 8b.
A bypass 14 with an isolation valve 13 is installed.

On the other hand, the air supply pipe 8a has a valve 15 connected to the suppression chamber 3a of the containment vessel 3.
A branch pipe 16 is provided in the exhaust pipe 8b, and a branch pipe 19 connected to the suppression chamber 3a is constituted by a bypass 20 equipped with an on-off valve 17 and an isolation valve 18. There is.

On the other hand, there is a main exhaust stack 2 on the other side of the reactor building 1.
1 is provided so as to communicate with the inside of the building via a main exhaust duct 22, and this main exhaust duct 2
2 includes each exhaust isolation valve 23 and exhaust chamber 24.
Opening/closing valves 25a, 25 and exhaust fans 26a, 26b, which operate independently, are installed. Further, the exhaust pipe 8b is connected to a part of the exhaust duct 22, and an exhaust fan 27 is installed in the exhaust pipe 8b.

On the other hand, in the main exhaust duct 22 located upstream of each of the exhaust isolation valves 23, an exhaust duct 28 constituting an emergency gas treatment system is connected to the main exhaust pipe 22.
1, and a bypass 31 having a switching valve 29 and a switching valve 30 is attached to the exhaust duct 28 at a position close to the main exhaust duct 22. moreover,
A branch pipe 33 provided with a switching valve 32 is connected to the exhaust duct 28 located downstream of the switching valve 29 so as to communicate with the exhaust pipe 8b.
Further, a flow meter 34 is provided in the exhaust duct 28 at a position where the branch pipe 33 is connected, and this flow meter 34 can measure the flow rate of all fluids flowing into the emergency gas treatment system. ing. Furthermore, the exhaust duct 28, which is provided in parallel downstream of the flow meter 34, includes independent isolation valves 35a, 35b and flow rate detectors 36a, 3.
6b, each filter train 37a, 37b, each flow control valve 38a, 38b, and each exhaust fan 39a,
39b are installed in order, each filter train 37a, 37b and each flow control valve 38a,
A bypass 41 equipped with an on-off valve 40 is provided between the exhaust ducts 28 and the exhaust ducts 38b.

On the other hand, the outside air intake pipe 42 of the air supply chamber 4 is connected to each of the exhaust ducts 28 located between the isolation valves 35a, 35b and the flow rate detectors 36a, 36b. 4
2 is provided with a check damper (automatic damper) 43 and a flow control valve 44 operated by an electromagnet. Furthermore, this flow control valve 44
A differential pressure transmitter 45 is electrically connected to the
This differential pressure transmitter 45 detects the differential pressure between the internal pressure of the reactor building 1 and the pressure of outside air, and can operate the flow rate control valve 44 based on this detection signal. That is, this differential pressure transmitter 4
5, when the pressure inside the reactor building 1 is greatly reduced, the flow rate control valve 44 is opened wide to prevent the pressure inside the reactor building 1 from falling below the reference negative pressure, and outside air is drawn from the outside air intake pipe 42. The gas is supplied to each exhaust duct 28 of the emergency gas treatment system.

Hereinafter, the effects of the present invention will be explained.

(1) During normal operation in a nuclear power plant, during normal operation in a nuclear power plant, one supply air blower 6a and one exhaust fan 26
When a is operated, each supply air isolation valve 7a,
7b, each exhaust isolation valve 23, and the on-off valve 25a are fully opened. On the other hand, the exhaust fan 27 and the emergency gas treatment system are stopped, and the switching valves 29 and 30, the isolation valves 35a and 35b, the flow control valves 38a and 38b, and the flow control valve 44 are closed. Therefore, the air flow inside the reactor building 1 is controlled by the air supply chamber 4.
The outside air is sucked in from the outside air louver 4a,
This air is supplied into the reactor building 1 through the air supply duct 5. Therefore, the dirty air inside the reactor building 1 is purified by the exhaust chamber 24 installed in the main exhaust duct 22, and the air is purified by the exhaust chamber 24 installed in the main exhaust duct 22.
is emitted into the atmosphere.

(2) When a reactor building isolation signal is generated, a detector (not shown) installed in advance in the reactor building transmits an isolation signal for the reactor building 1, and this signal causes the above emergency gas treatment to be carried out. At the same time when the exhaust fans 39a and 39b of the system start operating, the switching valves 29 and 30 and the isolation valves 35
a, 35b, and each flow control valve 38a, 38b are opened, the supply air blower 6a and exhaust fan 26a are stopped, and at the same time, each supply air isolation valve 7 is opened.
a, 7b, each exhaust isolation valve 23, and on-off valve 2
5a closes.

Therefore, the air flow within the reactor building 1 is gradually reduced to a negative pressure state, and the contaminated air is discharged into the atmosphere from the main exhaust stack 21 through the emergency gas treatment system. Further, when the inside of the reactor building 1 reaches the reference negative pressure value, the differential pressure transmitter 45 is activated, and this detection signal opens the flow rate control valve 44 to direct outside air to the outside air intake pipe 42. The gas can be supplied from the gas to each exhaust duct 28 of the emergency gas treatment system.

(3) During test operation of the emergency gas treatment system When performing a test operation of the emergency gas treatment system, first manually open the flow rate control valve 44, and then manually open each of the isolation valves 35a and 35b. The valve is then closed, and on the other hand, the exhaust duct 2
This is done by operating the eight exhaust fans 39a and 39b. That is, as a result of this, each of the flow rate control valves 38a and 38b is automatically opened to the rated flow rate opening, so that a test operation of the emergency gas treatment system can be performed independently from the reactor building 1.

(4) During airtightness/leakage testing of reactor building (emergency gas treatment system used).

The airtightness and leakage tests of the reactor building are performed by activating the emergency gas treatment system while the reactor building 1 is isolated. That is, the suction side of the emergency gas treatment system communicates with the main exhaust duct 22. Further, the opening and closing of the flow rate control valve 44 is controlled by the differential pressure transmitter 45.

If the differential pressure at this time is set as the test value,
At this time, the reactor building 1 can inspect the amount of air leakage using the flow meter 34 in the emergency gas treatment system.

Note that the above-mentioned air leakage amount can be used as a guideline to indicate the airtightness of the reactor building due to secular changes during a later periodic inspection.

As described above, according to the present invention, the exhaust duct 28 is provided in parallel between the reactor building 1 and the main exhaust stack 21, and the isolation valves 35a, 3
5b, flow rate detectors 36a, 36b, filter trains 37a, 37b, flow rate control valves 38a, 38
b and exhaust fans 39a, 39b are installed in order, and the isolation valves 35a, 35b and flow rate detectors 36a, 36 are installed in order.
The outside air intake pipe 42 of the air supply chamber 4 is connected to the exhaust duct 28 located between Moreover, since the reactor building 1 is equipped with a differential pressure transmitter 45 that detects and transmits the differential pressure in the reactor building 1, when the emergency gas treatment system is activated, the inside of the reactor building 1 is This not only prevents abnormal negative pressure, but also prevents the surging phenomenon of the exhaust fans 39a and 39b, and also allows for independent test operation of the emergency gas treatment system.

[Brief explanation of the drawing]

The figure is a system diagram showing an emergency gas treatment device according to the present invention. 1... Reactor building, 4... Air supply chamber, 5... Air supply duct, 21... Main exhaust stack, 22... Main exhaust duct,
28...Exhaust duct, 35a, 35b...Isolation valve, 3
6a, 36b...Flow rate detector, 37a, 37b...Filter train, 38a, 38b...Flow rate control valve, 39a, 39b...Exhaust fan, 42...Outside air intake pipe, 43...Check damper, 44...Flow rate control valve, 45... Differential pressure transmitter.

Claims (1)

[Claims] 1. An exhaust duct is installed in parallel between the reactor building and the main exhaust stack, and an isolation valve, a flow rate detector, a filter train, a flow control valve, and an exhaust fan are installed in this exhaust duct in this order, and the isolation valve and flow rate detection The outside air intake pipe of the supply air chamber is connected to the exhaust duct located between the reactor and the reactor, and the outside air intake pipe is provided with a check damper and a flow rate control valve, and is connected to the flow rate control valve. An emergency gas processing device characterized in that the reactor building is provided with a differential pressure transmitter that detects and transmits a differential pressure in the building.