JPS6131837B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to improve steam condensation efficiency during blowdown such as when a relief safety valve is activated and during a coolant loss accident, and to prevent storage during blowdown in a boiling water type suppression structure. The present invention relates to a suppression pool structure that can significantly improve the reduction of blowdown loads on containers and buildings, as well as the prevention of shaking of suppression pool water during earthquakes.

An example of a conventional suppression pool structure for a nuclear power plant will be explained based on FIGS. 1 and 2.

FIG. 1 is a cross-sectional view of the reactor building of a nuclear power plant. The dry well space separated by the dry well 7 and the suppression pool 8 are contained within the containment vessel 2, and the lower part of the dry well The vent pipes 9 are connected to each other by vent pipes 9 that are radially opened.

In the event of a so-called loss of coolant accident due to main steam piping rupture, etc., high-temperature, high-pressure steam and air released into the dry well space are suddenly released into the suppression pool 8 through the vent pipe 9, where they are cooled by pool water. It has a condensed structure.

During steam blowdown such as in the event of a loss of coolant accident, a huge amount of high-temperature, high-pressure steam in the dry well space is condensed by pool water through the vent pipe 9, so the amount of water required for the suppression pool 8 is 3000 to 4000 tons. For this reason, the suppression pool 8 undergoes large so-called pool water fluctuations during an earthquake, and the resulting dynamic water pressure is said to have a large effect on the strength of the base of the dry well 7, containment vessel 2, etc.

Figure 2 shows the A-A cross section in Figure 1, and high-pressure condensed flow is directly discharged to the containment vessel 2 side during steam blowdown from the vent pipes 9 installed radially from the center of the reactor building 1. As a result, dynamic loads were transmitted to the containment vessel 2, which had a large impact on the design load of the containment vessel. In addition, a relief safety valve is installed in the main steam pipe in order to prevent an abnormal pressure rise in the reactor, and its exhaust pipe extends into the water of the suppression pool 8 and is passed through the exhaust system 10. It is designed to release steam into the water. As an exhaust device, one having two horizontally oriented openings has been used, but such a structure has the drawback of large bubble pressure pulsations.

In view of the above-mentioned points, the present invention provides a suppression pool structure that can prevent the water in the suppression pool from shaking during an earthquake, reduce the steam blowdown load, and improve the efficiency of steam condensation. The purpose is to

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 3 is a plan view of a suppression pool portion showing one embodiment of the present invention, FIG. 4 is a detailed view showing the present invention, and FIG. 5 is a sectional view showing one embodiment of the present invention. In the figure, 10 is a relief safety valve exhaust device, 11 is a flow divider plate, and 12 is a steam release opening.

In the suppression pool structure of the present invention, the steam flow during steam blowdown and when the safety relief valve is activated is directed onto the center line of the vent pipe 9 which is arranged radially in the dry well 7 from the center of the reactor building 1. Double flow divider plate 1 that has the function of diverting flow in different directions
1, and has a relief safety valve exhaust device 10 between the flow divider plates.

High-temperature, high-pressure steam released from the dry well space in the event of a loss of coolant accident and high-temperature, high-pressure steam when the relief safety valve is activated passes through the vent pipe 9 and the relief safety valve exhaust system 10, and is discharged into the suppression pool as shown by the broken line in Fig. 4. However, as shown by the broken line, the flow dividing plate 11 attached to the containment vessel 2
The streamline is roughly divided into two by . Due to the above functions of the vent pipe 9, the flow dividing plate 11, and the relief safety valve exhaust device 11, which are adjacent to each other, the divided condensed flows collide with each other and are stirred. For this reason, the condensation efficiency of high-temperature, high-pressure steam improves, and
The discharge flow during steam blowdown and when the relief safety valve is activated is divided into two by the flow divider plate 11, and the energy of the discharge flow is reduced by the collision of adjacent flows. Dynamic loads such as blowdown to the sides are significantly reduced.

On the other hand, according to the suppression pool structure of the present invention, the suppression pool part is partially partitioned by the flow divider plate 11, with the same capacity of pool water as in the conventional structure. In the event of an earthquake, the flow divider plate 11 acts as a damping plate having a damping effect, and the swinging portion of the pool water only exists as if the diameter of the containment vessel 2 had become smaller. Therefore, the dynamic load caused by the shaking of the pool water during an earthquake is significantly reduced, which greatly contributes to reducing the design loads of the containment vessel 2 and dry well 7.

Furthermore, the steam condensation effect when the safety relief valve is activated can be ensured as described above, not much different from that of the conventional structure, and the dynamic load when the safety relief valve is activated can be significantly reduced as described above.

As described above, according to the suppression pool structure of the present invention, the combination of the flow divider plate 11 and the relief safety valve exhaust device 10 can be easily performed without changing the capacity or shape of the suppression pool of the conventional structure. It has characteristics that allow it to demonstrate its functional effectiveness and safety measures. Further, in the event of a loss of coolant accident, there is an advantage that no blowdown load is directly applied to the safety relief valve exhaust system 10, and the function of the safety safety valve exhaust system 10 can be maintained.

According to the suppression pool structure of the present invention,
Improved steam condensation efficiency during steam blowdown during coolant loss accidents and when steam is released when the safety relief valve is activated, significantly reduces dynamic loads during blowdown, and furthermore, shakes suppression pool water during earthquakes. This is an extremely highly functional and safe suppression system that has the advantage of reducing hydraulic loads through prevention, and also prevents blowdown loads from acting directly on the safety relief valve exhaust system in the event of a loss of coolant accident. You can get a pool structure.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining a conventional suppression pool structure, FIG. 3 is a diagram for explaining a suppression pool structure according to the present invention, and FIG. 4 is a diagram for explaining a suppression pool structure according to the present invention. FIG. 5 is a sectional view showing an embodiment of the present invention. 1... Reactor building, 2... Containment vessel, 3... Ware wall, 4... Pressure vessel pedestal, 5...
...heat-resistant wall, 6... reactor pressure vessel, 7...
Dry well, 8...Suppression pool, 9
...Vent pipe, 10...Relief safety valve exhaust device,
11...Broadcast plate, 12...Steam release opening.

Claims (1)

[Claims] 1. In a reactor containment vessel with a suppression pool in a nuclear power plant, a double flow divider plate is installed in the corresponding suppression pool on the center line of the vent pipe, and a relief valve is installed between the double flow divider plates. A suppression pool in a nuclear power plant reactor building that is characterized by the installation of a safety valve exhaust system.