JPH0541955B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to the use of a working floor ventilation system to collect radioactive gases generated from a pool in the ventilation system at the time of refueling on the working floor of a nuclear reactor. This invention relates to a reactor operating floor ventilation system for boiling water nuclear power generation equipment suitable for highly efficient radioactive gas collection.

[Background of the invention]

Reactor operating floor and fuel pool (spent fuel storage pool/reactor cavity reactor well/dryer) in conventional boiling water nuclear power generation equipment
Figures 1 and 2 show system diagrams of the ventilation and air conditioning duct equipment for the separator equipment (temporary storage pool). 1st
The figure shows the supply air and exhaust duct systems for the entire reactor operating floor, and in particular, the exhaust duct system around the fuel pool (pool-embedded duct) is shown in FIG. FIG. 3 shows the arrangement of ducts on the operating floor, and FIG. 4 shows a sectional view thereof. Furthermore, Fig. 5 shows the flow of wind on the operating floor during fuel exchange and periodic inspection.

In the case of the conventional system, as shown in Figures 1 to 4, the ventilation system on the reactor operating floor 1 supplies air through an air supply duct 5 on the wall of the operating floor and exhausts air through an exhaust duct 6 on the opposite wall. It's summery. In addition, during fuel exchange and periodic inspections, radioactive gases (volatile activation such as radioactive iodine, In order to collect the trapped molecules, the air is exhausted from an exhaust duct (embedded duct 8) embedded in the pool wall above the pool water surface. Also, Fig. 1 7 shows that
It is shown that the air supplied to the driving floor is transferred through the driving floor by the driving floor air supply duct 5, rather than the actual duct dedicated to the pool. Therefore, the air supplied to the operating floor is exhausted by the exhaust duct of the operating floor and the embedded ducts of the three pools 2-4. The second one shows an embedded duct system, and the 12,1 shown in this figure
3, 14, and 15 indicate a globe valve, a drain port, a duct isolation valve, and a drain pipe, respectively. Radioactive gas generated from the pool is exhausted through an embedded duct, but since this duct has an opening approximately 12 mm above the pool water surface, water may flow into the duct due to ripples in the pool water caused by earthquakes, etc. there's a possibility that. For this reason, this duct is provided with an isolation valve, drain piping, etc. If water flows into the duct, the first drain pipe (the pipe installed between the duct opening and the isolation valve) will prevent the water from flowing into the duct, but some of the water will flow to the end of the duct. Therefore, an isolation valve 14 is provided in the duct. In addition, assuming that complete isolation may not be possible, a drain pipe is also provided beyond that, and electrical signals are also required to open and close these valves 12 and 14, resulting in a very complicated structure. There is.
In addition, since the duct is buried under the operating floor, there is a lot of interference with building reinforcement, other system piping, etc., and construction requires a large amount of man-hours.

FIG. 5 shows the flow of air on the driving floor by a conventional duct system. As shown in the figure,
Collection of radioactive gas generated in pools 2 to 4 is as follows:
This is only done near the duct opening. Since the temperature of the radioactive gas near the center of the pool is high (50 to 65 degrees Celsius), it is released onto the operating floor, rises to the upper part of the building, and spreads radioactive contamination on the operating floor. On the other hand, since the fresh air supplied from the air supply duct 5 has a low temperature (16° C.), it gradually descends to the floor surface. However, as the high-temperature contaminated air from the pool rises above the pool, the two airs mix and rise toward the building near reactor well 2, causing low-temperature air to flow into the vicinity of spent fuel storage pool 3. There is no fresh air. Therefore, the floor surface from the bottom of the air supply duct to the reactor well has relatively low radioactive contamination, but the floor surface from the reactor well to the bottom of the exhaust duct has a high contamination rate.

As described above, the conventional reactor operating floor ventilation system for boiling water nuclear power generation equipment has the following drawbacks.

(1) Since the air flow for the driver is as shown in Figure 5, it is not very effective in capturing radioactive gas generated in the pool.

(2) Water may flow into the duct due to ripples on the pool water surface due to earthquakes, etc. In addition, it has a very complex structure to completely prevent this.

(3) The buried ducts around the pool are buried under the floor, so there is a lot of interference with the back of the building and other system piping, etc., requiring a large amount of man-hours to construct.

[Purpose of the invention]

An object of the present invention is to provide a ventilation system that can efficiently collect radioactive gas on the operating floor of a nuclear reactor.

[Summary of the invention]

The present invention provides a ventilation system for a reactor operating floor, which comprises a reactor operating floor equipped with a dryer separator pool, a reactor well, and a spent fuel storage pool, and an air supply duct and an exhaust duct. The air supply duct is provided along both side walls at a height midway between both walls of the driving floor that face each other at a high position, and the air supply duct is provided above the central portion between the both side walls of the driver's floor. This is a ventilation system for a reactor operation floor, characterized in that the exhaust duct is provided along the ceiling of the reactor, and the supply air duct and the exhaust duct extend in the same direction, and the supply air temperature is relatively higher than that of the supply air. High-temperature polluted gas from each pool rises from each pool, and on the way, the polluted gas is restrained from at least both sides by the supply air from the supply air duct so that the polluted gas does not spread, and then flows into the upper exhaust duct. The exhaust duct can efficiently receive the polluted gas, and the effects of diffusion suppression, induction, and acceptance can be achieved over a wide range of directions because the supply air duct and exhaust duct extend in the same direction. You can obtain the effect that is achieved in .

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on FIGS. 6 to 9.

FIG. 6 shows a ventilation system for a nuclear reactor operating floor according to the present invention. The main feature of this system is that the conventional buried duct is abolished, and the radioactive gas generated from the pool is collected and exhausted by the driving floor ventilation system, which is exhausted through the driving floor exhaust duct. This is indicated by 9 in the figure. FIGS. 7 and 8 show a plan view and a step view of the duct arrangement of the driving floor according to this method. In this system, air is supplied through two air supply ducts 5 installed on the walls of the operating floor on both sides of the pool, and a ceiling exhaust duct 6 above the pool.
Exhaust is performed by 3 pools 2-4
Because the concentration of radioactive gas emitted by the pools is different, the supply and exhaust ducts are installed parallel to these pools, and in order to improve ventilation near the spent fuel storage pool 3, where the radioactivity concentration is highest, the supply and exhaust ducts are installed from the supply and exhaust fan. The duct is connected to the main pool side, increasing the amount of ventilation compared to other pools. Therefore, the main pool side, where the duct is large, is the largest, increasing the amount of air supply and exhaust, and ensuring that the radioactive contamination of the entire operating floor remains constant. In addition, the ceiling exhaust duct is installed so as to rest on the building reinforcing bars 10 on the ceiling of the operating floor to improve earthquake resistance and prevent it from falling into the pool. In addition, the duct is fixed directly to the building reinforcement using support materials to prevent movement in the left and right direction.

Figure 9 shows the flow of wind on the operating floor using this ventilation method. The air supplied from the air supply duct 5 on the wall of the operating floor has a low temperature (16°C), so it heads downwards into the building, ventilates the floor, and then rises above the pool to the high temperature (50 to 65°C) generated by the pool. It mixes with contaminated air (radioactive gas) at temperatures below 30°F and rises in temperature and rises above the building. The polluted air that rose
Exhaust is exhausted through a ceiling exhaust duct installed above the pool. Some of the rising air circulates above the building, but because its temperature is higher than the supply air, it does not come down. Furthermore, as mentioned above, since the supply and exhaust ducts are installed in parallel to the three pools, the wind flows in all the pools as shown in this figure.

As described above, according to this embodiment, the effect of collecting radioactive gas generated from the pool is significantly improved compared to the conventional method.

In this embodiment, the following advantages can be obtained by eliminating the duct buried in the pool.

(1) Eliminating buried ducts will simplify the design and significantly reduce construction man-hours and costs, resulting in rationalization.

(2) With the elimination of buried ducts, the problem of pool water flowing into the ducts due to earthquakes, etc. will be eliminated.

(3) With the elimination of buried ducts, there will be no need for associated isolation valves, globe valves, etc. that require remote control to open and close, making operation easier.

〔Effect of the invention〕

According to the present invention, there is an effect of guiding the radioactive gas to the upper exhaust duct side while preventing it from dispersing in the air supply flow, and this effect is achieved over a wide range in the extending direction of the duct, so that the radioactive gas The gas trapping effect is improved over a wide range, and the effects on the human body during periodic inspections can be reduced.

[Brief explanation of drawings]

Figure 1 is a schematic system diagram of the supply air and exhaust ducts on the conventional reactor operating floor, Figure 2 is a detailed system diagram of the exhaust duct in Figure 1, and Figure 3 is the conventional system diagram of the air supply and exhaust ducts on the reactor operating floor. A plan view of the reactor operating floor showing the arrangement of air ducts, Figure 4a is a cross-sectional view taken along the line A-A in Figure 3, Figure 4b is a cross-sectional view taken along the line B-B in Figure 3, and Figure 5 is a cross-sectional view taken along the line B-B in Figure 3. FIG. 6 is a longitudinal sectional view of the reactor operating floor showing the airflow on the reactor operating floor during fuel exchange or periodic inspection in the conventional example, and FIG. 6 is a schematic diagram of the air supply and exhaust duct in the embodiment of the present invention. Overall genealogy, No. 7
The figure is a plan view of a reactor operating floor employing the supply and exhaust duct system according to the present invention, and Figure 8a is A-A in Figure 7.
A line sectional view, FIG. 8b is a BB line sectional view of FIG. 7,
FIG. 9 is a longitudinal cross-sectional view of a nuclear reactor operating floor according to an embodiment of the present invention, showing the flow of airflow during ventilation in the cross section shown in FIG. 8a. 1... Reactor operating floor, 3... Spent fuel storage pool, 5... Operating floor air supply duct, 6... Operating floor exhaust duct, 7... Supply air transfer, 8... Buried around the pool. Duct, 9... Transfer of exhaust air, 12...
...Drain piping globe valve, 13...Drain socket,
14...Duct isolation valve.

Claims (1)

[Scope of Claims] 1. A ventilation system for a reactor operating floor, which comprises a reactor operating floor equipped with a dryer separator pool, a reactor well, and a spent fuel storage pool, and an air supply duct and an exhaust duct. The air supply duct is provided along both side walls of the driving floor at a height midway between both walls facing each other at a position higher than the pool, and the air supply duct is provided above the central portion between the both side walls of the driving floor. A ventilation system for a nuclear reactor operating floor, characterized in that the exhaust duct is provided along the ceiling of the operating floor, and the supply air duct and the exhaust duct extend in the same direction. 2. In claim 1, the position is such that the supply air from the air supply duct can reach the floor of the operating floor, and the height is such that a pair of left and right vortices forming an upward flow can be generated in the center of the operating floor. 1. A ventilation system for a nuclear reactor operating floor, characterized in that the supply air duct is provided at a position above the vortex, and the exhaust duct is provided along the ceiling above between the pair of vortices. 3. A nuclear reactor operating floor according to claim 1 or 2, characterized in that the connection position of the duct from the fan to the exhaust duct along the ceiling is on the side of the spent fuel storage pool. ventilation system. 4 Paragraph 1 or 2 or 3 of the claims
2. A ventilation system for a nuclear reactor operating floor, characterized in that the exhaust duct along the ceiling and the air supply duct along both side walls both extend in the same direction as the direction in which each pool is lined up.