JPS6053886A - Dry well cooling system of boiling-water type nuclear electric power generating facility - 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 [Field of Application of the Invention] The present invention relates to a dry well cooling system that removes heat in a dry well that houses a nuclear reactor and its auxiliary equipment in a boiling water nuclear power generation facility, and particularly relates to a dry well cooling system that removes heat in a dry well that houses a nuclear reactor and its auxiliary equipment in a boiling water nuclear power generation facility. This article relates to a dry well cooling system that is optimal for making the internal temperature distribution uniform.

[Background of the invention]

A block diagram of a conventional dry well cooling system is shown in FIG. In the conventional dry well cooling system, the air inside the dry well 1 cannot be sufficiently diffused due to the low wind speed at the outlet of the air supply duct 2 and the outlet 3 inside the dry well 1. , especially bulkhead plate 4
There was a drawback that the temperature was uneven, such as a high temperature at the lower part and a low temperature at the lower part of the dry well 1. There are concerns that atmospheric corrosion may occur due to condensation on the surfaces of the potash and stainless steel piping, which is particularly likely to occur due to the low temperature at the bottom of the dry well 1, leading to the need for additional dehumidification equipment.

Furthermore, in the conventional dry well cooling system, since the cooling coil 5 and the blower 6 are located inside the dry well, once the reactor is operated, it is not possible to easily enter the dry well. The disadvantage was that maintenance and inspection during operation was impossible.

1. Large equipment such as the cooling coil 5 and the blower 6 are located in the dry well, which has a limited volume, and this may obstruct the passage through the dry well, so for safety reasons, the dry well should have a small volume. This was a factor in making it bigger.

[Purpose of the invention]

The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art by adopting a jet pump at the outlet of the air supply duct, installing a cooling coil and a blower outside the dry well,
To provide a dry well cooling system that uniformizes the temperature inside the dry well by supplying air through a duct penetration provided in the dry well wall, and enables maintenance and inspection of equipment such as cooling coils and blowers during operation. There is a particular thing.

[Summary of the invention]

The present invention is designed to prevent the temperature inside the dry well, which is cooled by a conventional dry well cooling system, from being uneven and dusty, and to prevent dry well cooling system equipment such as cooling coils and blowers from being accessible during reactor operation. As a means of solving this problem, we installed a jet pump at the outlet of the air supply duct inside the drywell to promote the diffusion of air inside the drywell, and installed a cooling coil and blower outside the drywell to prevent air flow from the drywell wall. The air is blown through a duct penetration installed in the duct.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. The reactor 7, which can be called the main body of the boiling water nuclear power generation facility, and its surrounding equipment, such as the main steam piping and recirculation pump, are housed in the dry well 1, and the heat generated by the reactor 7, etc. is removed. A dry well cooling system is installed to heat the dry well 1 and keep the temperature inside the dry well 1 within a predetermined temperature range. The dry well cooling system shown in the embodiment of the present invention basically consists of an air supply ring duct 2 for feeding air into the dry well.
, an air outlet 3, a jet pump 8 for supplying air while taking in a portion of the air inside the dry well, and an air inlet for sucking in air whose temperature has risen due to heat generated from a heating element such as a nuclear reactor. 9 and exhaust/gudaku) 1
0. It consists of a cooling coil 5 for removing heat from the heated air, lowering the temperature, and dehumidifying the air, and a blower 6 for blowing the low-temperature or heat-removed air into the dry well 1. Since the cooling coil 5 and the blower 6 are installed outside the dry well, there is no supply or cooling on the dry well wall.
A through hole 11 for an exhaust duct is provided. On both sides of the penetration part 110, isolation dampers 12 for isolating the inside of the dry well in the event of an accident in the containment vessel are installed in each penetration duct, one inside and one on the outside of the dry well.

A cooling water system including a refrigerator 13 and a cooling water circulation pump is installed as a cooling water source for the cooling coil.

In the case of a 1100 MWe class boiling water reactor power generation facility, the total calorific value in dry well 1 is 1,000,000ol.
/h. In the example of the present invention, unlike the conventional reactor auxiliary cooling water which is used as a cooling water source, a refrigerator system is used, so the cooling water inlet temperature of the cooling coil 5 is about 35C compared to the conventional system. On the other hand, in the method of the present invention, it is possible to obtain about 70 degrees of cooling water. Therefore, the dry well supply air temperature can be set to approximately 12 tZ" compared to the conventional approximately 40p. Therefore, the air 1Q required to supply air into the dry well 1 is: q - Sensible heat load (heat generation) amount) = 1,000,0
00h+/h γ = Specific weight = 1,2 Ky/m3 (temperature 12c) Cp =
Specific heat = 0.24 bl/Kg・C11L - Designed dry well internal temperature - 57 CtD = Supply air temperature = 120 As shown in Figure 2, 10 jet pumps are installed around the top of the dry well, and each jet pump The pump sucks in an air volume that is approximately twice the air supply volume from the surrounding area, and forces it into the lower dry well along with the supply air.

Therefore, the circulating air volume in the dry well is 77,000.
It is possible to secure m3/h X 3 =231.000 m3/h. Note that the circulating air volume of the conventional dry well cooling system is approximately 220,000 m 3 /41, and it is possible to secure a circulating air volume that is higher than that of the conventional dry well cooling system using a blower with a smaller capacity than the conventional dry well cooling system.

Therefore, the processing air volume of one jet pump is 23.1
00 m3/h. Two air supply duct penetration parts and two exhaust duct penetration parts 11 are installed, and the air volume per 91 ducts is halved to 38,500 m3/hs.Since the duct uses a high-speed duct, the air velocity inside the duct is 30 m3/hs. h
The diameter of the penetration part is 50.67 m, so it is possible to use 50A piping, and it is a normal size for a penetration part, not too large. In addition, the air supply ring duct 2 also uses 450A piping instead of the conventional one.
A smaller size ring duct can be used compared to a ring duct with a size smaller than m. The exhaust ring duct is also 70OA, which is the same size as the air supply ring duct, to reduce the space in the lower drywell.

The isolation damper 12 is an electrically driven damper with a size of 650A for both supply and exhaust air, and is installed to stop the operation of the dry well cooling system and isolate the dry well in the event of a dry well accident.

To provide redundancy, this damper has a total of 8 dampers: 1 each inside and outside the dry well 1, 4 air supply ducts, and 4 exhaust ducts.
It has been installed. Even if air is used as the driving method for this damper, the effects described later will be the same.

According to this embodiment, the jet pump 8 is placed at the top of the dry well, and blows almost the entire air volume toward the bottom.
In addition, since the high-temperature air from the upper part of the jet pump is sucked in at twice the volume of air from the blower, it is possible to completely blow the air almost uniformly over the entire area inside the dry well. Therefore, with the conventional dry well cooling system, the problem of uneven temperature inside the dry well could almost be solved.

In addition, conventionally, the cooling coil 5 and the blower 6 were housed inside the dry well, but in the embodiment of the present invention, they can all be installed outside the dry well, reducing the cost of dry well contents by approximately 15%. In addition, the passage properties within the dry well were significantly improved.

Similarly, compared to the conventional duct routing in the dry well, the embodiment of the present invention basically has only two ducts in total: one upper air supply ring duct 2 and one partial exhaust ring duct 10. It is no longer necessary, and the duct space is reduced to about 70 compared to the conventional one.
% (9), which is one of the factors in reducing the dry well volume.

In addition, as mentioned above, it has become possible to install equipment that requires regular maintenance and inspection, such as the cooling coil 5 and blower equipment, outside the dry well, which means that failures in these equipment have traditionally caused plant shutdowns. The problems that had previously led to a decline in plant availability have been eliminated, and it has become possible to significantly improve the reliability of dry well cooling systems and nuclear power plants.

Similarly, since it has become possible to install the above-mentioned production equipment and outside the dry well, it has previously been possible to access it only when the plant is stopped, and maintenance and inspections have been carried out in a small space inside the dry well. Significant benefits were obtained in terms of ease of maintenance and inspection, such as easy access during operation and the ability to secure a large space. In addition, maintenance and inspection work that was conventionally performed under high radiation doses can now be performed at low radiation doses, which has the effect of significantly reducing radiation exposure during maintenance and inspection work (10).

In addition, since a refrigerator is used as the cooling source, the air volume is about half of the conventional capacity, and the number of cooling coils and blowers can be reduced to about half, with three each, which helps secure space inside the reactor building. The answer is that it is possible to reduce the overall building volume without giving a large impact.

〔Effect of the invention〕

According to the present invention, it is possible to install a jet pump on the air supply duct side of the dry well cooling system and to install main equipment such as a blower outside the dry well, so it is possible to supply air with a small amount of air supply. By being able to send approximately three times the amount of ventilation air into the dry well at high speed,
This has the effect of making the dry well temperature uniform, preventing problems caused by condensation, etc., and significantly improving the ease of maintenance and inspection of major equipment.

[Brief explanation of drawings]

FIG. 1 is a diagram conceptually explaining the configuration of a dry well cooling system in the prior art, and FIG. 2 is a diagram conceptually explaining the configuration of an embodiment (11) of the present invention. 1... Dry well (6 inside the reactor building), 2... Air supply ring duct, 3... Air outlet, 5... Cooling coil, 6... Blower, 7... Nuclear reactor, 8... Jet pump, 9... Suction port, 1o... Exhaust ring duct, 11... Duct penetration part, 12... Isolation damper, 13... Freezer, (12)

Claims (1)

[Claims] 1. Installed to maintain the temperature within a reactor containment vessel (dry well) that houses a boiling water reactor within a predetermined range, and consisting of a cooling coil, a blower, a damper, a duct, etc. A dry well cooling system for a boiling water nuclear power generation facility, characterized in that the air supply side duct is provided with a jet pump. 2. Scope of Claims No. 1. In l1i4, a dry well cooling system for a boiling water type nuclear power generation facility is characterized by providing a duct penetration part in the dry well. 3. Claim 2 provides a boiling water nuclear power generation facility characterized in that the duct is connected to a duct passage, and an isolation damper is installed in the duct near the penetration part. Drywell cooling system. 4. The dry well cooling system for boiling water nuclear power generation equipment according to claim 3, characterized in that the isolation damper is electrically driven. 5. A dry well cooling system for a boiling water nuclear power generation facility according to claim 3, wherein the isolation damper is driven by pneumatic pressure.