JPS622220B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a central control room ventilation air-conditioning system for purifying the atmosphere in a central control room (hereinafter referred to as a central control room) that is contaminated with radioactive materials in the event of an accident in a nuclear power plant.

Conventionally, nuclear power plants have been equipped with emergency atmosphere purification filters in anticipation of the atmosphere inside the central operating room becoming contaminated with radioactive materials in the event of an accident. An example of installing the emergency filter will be described below based on the drawings. In Fig. 1, when the reactor is in normal operation, the atmosphere inside the central operating room 1 passes through the recirculation pipe 2, and is passed through the valve 4 and the service filter train 5 by the suction force of the blower fan 3. He was returned to Central Operations 1 again. Commonly used filter train 5
It consists of a cooler, a heater, a filter, etc., and has the function of maintaining the circulated atmosphere at an appropriate temperature and at the same time removing dust floating in the atmosphere and purifying the atmosphere. On the other hand, a certain amount of outside air is taken in from the outside air intake 6, merges with the circulating atmosphere, passes through the valve 4 and the regular filter train 5 by the absorption power of the blower fan 3, and is introduced into the central operating room 1. be done. A part of the atmosphere inside the central operating room 1 is discharged into the atmosphere from an exhaust port 8 by an exhaust fan 7.
The amount of exhaust air discharged from the exhaust port 8 and the amount of intake air introduced from the outside air intake port 6 are balanced and equal. If a nuclear power plant accident involving the release of radioactive materials occurs while the ventilation air conditioner in the central control room is being operated under such conditions, the valve 4 will be closed and the intake fan 9 will be activated. As a result, the atmosphere and outside air introduced from the recirculation pipe 2 and the outside air inlet 6 pass through the emergency filter 10, the intake fan 9, the regular filter train 5, and the blower fan 3 in order and are introduced into the central operating room 1. Ru. The emergency filter 10 generally consists of a charcoal filter,
It has the ability to highly efficiently remove radioactive iodine and other substances that are most harmful to the human body in the event of a nuclear power plant accident. However, the air volume of such a ventilation air conditioning system is determined from the perspective of maintaining the atmosphere inside Central Control Station 1 at an appropriate temperature (this is more dominant in the design) rather than from the perspective of removing radioactive iodine. Therefore, in the event of a nuclear power plant accident, the emergency filter 10 will be required to handle an extremely large amount of air. Therefore, even though the emergency filter 10 is unnecessary from the original purpose of removing radioactive iodine in the event of an accident, it is currently installed in an extremely large size. This means that if we assume that the emergency filter 10 deteriorates after an accident and needs to be replaced with a new one urgently, considering that it will take time to replace it due to its large size, this will simply reduce efficiency. This is a disadvantage not only in terms of safety, but also in terms of safety. Then the second
Another example of conventional installation of an emergency filter will be explained based on the drawings. In Figure 2, when the reactor is in normal operation, the atmosphere inside the central operating room 1 is circulated through the recirculation pipe 2, and is combined with outside air introduced from the outside air intake 6 to form the regular filter train 5. It passes through the air blower fan 3 and is guided into the central operating room 1.
When a nuclear power plant accident involving the dissipation of radioactive materials occurs, the valve 4 is closed and the intake fan 9 is activated. As a result, the intake of outside air from the outside air intake port 6 is stopped, and on the contrary, the intake of outside air is started from the intake port 11 provided for emergency use. The outside air introduced from this emergency outside air intake 11 contains radioactive substances, but after the emergency filter 10 removes radioactive iodine, which is most harmful to the human body, with high efficiency, it passes through the intake fan 9 to the central control room. It is designed to be introduced within 1. However, with this method of installing an emergency filter, it is only possible to purify newly introduced outside air. If outside air containing radioactive materials is introduced from the outside air intake port 6 before valve 4 is closed, the atmosphere inside central operation room 1 will already be contaminated with radioactivity, but the regular filter train Due to the low removal efficiency of the radioactive substances No. 5, it is completely impossible to expect the function of circulating and purifying the atmosphere inside the central operating room 1 by the above-mentioned method of installing the emergency filter 10.

The purpose of the present invention is to improve these ventilation air conditioning systems for the central operating room, and to reduce the exposure dose of the central operating room personnel by circulating and purifying the outside air and the atmosphere inside the operating room using emergency filters in the event of a nuclear power plant accident involving the release of radioactive materials. The object of the present invention is to obtain a central control room ventilation air conditioning system that uses a small emergency filter that has the function of reducing radioactive materials and at the same time requires the minimum necessary air volume from the viewpoint of removing radioactive materials.

An embodiment of the present invention will be described below based on the drawings. As shown in FIG. 3, the present invention connects a central operating room 1, an outside air intake 6, an isolation valve 4, a regular filter train 5, and a blower fan 3 in series, and connects its tip into the central operating room 1. Opened ventilation pipe 12
and an exhaust pipe 14 whose one end is connected to and opens inside the central operating room 1 and whose other end is connected to the exhaust port 8 via the exhaust fan 7, and the exhaust pipe 14 is branched from the middle of the exhaust pipe 14 and is connected to the ventilation pipe 1.
A conventional atmosphere recirculation loop is formed from the isolation valve 4 of 2 and the recirculation line 2 connected to the intermediate section of the conventional filter train 5. Furthermore, one end is connected to the exhaust pipe 14, and the other end is connected to the middle part of the blower fan 3 and the central operating room 1 of the blower pipe 12 via the emergency filter 10 and the intake fan 9. 15, one end of the emergency recirculation pipe 15 branches midway between the emergency filter 10 and the exhaust pipe 14, and is connected to the isolation valve 1.
An emergency atmosphere recirculation loop is formed by an intake pipe 16 whose other end is connected to the intake port 11 via a pipe 3. The isolation valve 4 must be able to be isolated remotely by an operator from the central operating room 1, or automatically isolated in response to an accident signal; however, such an isolation valve cannot be used inside a nuclear power plant. Various types of isolation valves have already been put into practical use, and it goes without saying that all of these isolation valves can be used in the present invention.

Next, the operation of the present invention will be explained. When a nuclear power plant accident involving the release of radioactive materials occurs, the isolation valve 4 is closed and the exhaust fan 7 is stopped at the same time. These operations may be performed by an operator from within the central operating room 1, or may be performed automatically in response to an accident signal. With the isolation valve 4 closed, the outside air intake 6
The atmosphere in the central operating room 1 passes through the recirculation pipe 2 and is treated by the regular filter train 5, and then is returned to the blower fan 3.
will lead you into Central Operations 1. On the other hand, intake fan 9
is started, and a part of the atmosphere inside the central operating room 1 is passed through the emergency recirculation pipe 15 and treated by the emergency filter 10, and then returned to the middle operating room 1. Isolation valve 13 has been closed since before the nuclear power plant accident occurred. When operating in this way, the atmosphere inside the central operating room 1 is only circulated internally and is cut off from the outside air.
Inside the central operating room 1, the CO ₂ concentration increases due to the breathing of the operators, and the O ₂ concentration decreases. For this purpose, it will eventually become necessary to introduce outside air, but in that case, the isolation valve 13 is opened and the exhaust fan 7 is operated.
After introducing the required amount of outside air and exhausting CO ₂ , the isolation valve 13 is closed again and the exhaust fan 7 is stopped.

The central control room ventilation air conditioning system of the present invention having the above-mentioned functions provides the following effects. In the event of a nuclear reactor accident involving the release of radioactive materials,
In general, ventilation and air conditioning systems in central operations are designed to be shut off from outside air and recirculated internally to avoid inhalation of radioactive materials. The primary purpose of internally recirculating the atmosphere inside the central operating room is to maintain the temperature inside the central operating room at an appropriate temperature for regular filter trains, so as not to adversely affect the operation of safety-critical equipment within the central operating room, and to prevent operational This is to ensure that the movement of the staff is not hindered. However, the amount of air to be recirculated for this purpose is extremely large, and the conventional design installed an emergency filter in series with the regular filter train to remove radioactive iodine, etc. that would contaminate the atmosphere inside the central operating room in the event of an accident. In the ventilation air conditioning system, even the emergency filter is extremely large, resulting in a very disadvantageous design in terms of safety, economy, and ease of maintenance and inspection. In the central control room ventilation air conditioning system according to the present invention, the emergency filter is not installed in series with the regular filter train, but is installed independently, so that the original purpose of the emergency filter is to remove radioactive iodine, etc. It is possible to reduce the size to the minimum required size. As a result, a very advantageous design can be obtained in terms of safety, economy, and ease of maintenance and inspection. In addition, simply installing emergency filters independently of the normal filter train can remove radioactivity from the freshly taken in outside air, but before the ventilation system is turned off to outside air, the Radioactivity that has entered cannot be removed. The central control room ventilation air conditioning system of the present invention can circulate and remove radioactivity that has entered the central control room using emergency recirculation piping and an emergency filter. As a result, it is possible to reduce the radiation level in the central operating room during an accident and reduce the radiation exposure of operators.

Other embodiments of the present invention will be described below based on the drawings. FIG. 4 is a schematic system diagram showing another embodiment of the centrally controlled air ventilation and air conditioning system according to the present invention. In this embodiment, the emergency recirculation line 15 is connected to the isolation valve 4 of the blower line 12 and the service filter train 5.
It is connected to the part between. The other parts are the same as the embodiment of the central control room ventilation and air conditioning system according to the present invention shown in FIG. According to this embodiment, the atmosphere treated by the emergency filter 10 is not directly returned to the central operating room, but rather passes through the service filter train 5 before being returned to the central operating room. Since the regular filter train 5 can also be expected to have a radioactive removal effect to some extent, even after the radioactive substances in the atmosphere have been removed by the emergency filter, the regular filter train 5 has the effect of further removing them.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an outline of a central control room ventilation air conditioning system in a conventional nuclear power plant, and Fig. 2 is a system diagram showing an outline of another embodiment of a central control room ventilation air conditioning system in a conventional nuclear power plant. , FIG. 3 is a schematic system diagram showing one embodiment of the central control room ventilation and air conditioning system according to the present invention, and FIG. 4 is a schematic system diagram showing another embodiment of the central control room ventilation and air conditioning system according to the present invention. be. 1... Central control room (central operation), 2... Recirculation piping, 3... Blower fan, 4... Isolation valve, 5... Regular filter train, 6... Outside air intake,
7...Exhaust fan, 8...Exhaust port, 9...Intake fan, 10...Emergency filter, 11...Intake port, 12...Blower piping, 13...Isolation valve, 14...
...Exhaust piping, 15...Emergency recirculation piping, 16...
...Intake piping.

Claims (1)

[Claims] 1. A central control room, ventilation piping that introduces outside air into this central control room via a commonly used filter train and ventilation fan, and exhaust piping that leads the atmosphere in the central control room to the outdoors via an exhaust fan, The atmosphere in the central control room is extracted using a regular filter.
A regular atmosphere recirculation system that circulates the atmosphere in the central control room, consisting of recirculation piping leading to the upstream side of the train, the above-mentioned central control room, regular filter train, ventilation fan, ventilation piping, exhaust piping, and recirculation piping. and an emergency air circulation loop, in which a portion of the circulating atmosphere of this atmosphere recirculation loop is drawn out and recycled back to the normal atmosphere recirculation loop through an emergency filter and an intake fan having the ability to remove radioactive substances. A central control room ventilation air conditioning system comprising recirculation piping and an intake piping that is connected to the upstream side of the emergency filter of the emergency recirculation piping and introduces outside air.