JPS6017759Y2 - reactor containment system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nuclear reactor containment system that can maintain the safety of a nuclear reactor by effectively introducing and condensing steam into the water of a nuclear reactor suppression pool.

A reactor containment system in a boiling water nuclear power plant is constructed as shown in FIG.

That is, the pressure vessel 1 housing the reactor core A is placed on the pedestal B.
The containment vessel 2 includes this pressure vessel 1.
is provided, and this containment vessel 2 is equipped with a
Prevent leakage of high pressure steam containing radioactive materials.

A toroidal pressure suppression chamber 5 is provided surrounding the lower part of the containment vessel 2. Pool water 6 for condensing high pressure steam is stored in this pressure suppression chamber 5, and a space is provided above the pool water. It has 7.

The pressure suppression chamber 5 and the containment vessel 2 are connected by a plurality of vent pipes 8.

One side of the vent pipe 8 opens into the space inside the containment vessel 2, and the other side passes through the pressure suppression chamber 5 and is connected to a vent header 9 provided in the upper space 7.

A large number of downcomers 10, which are steam discharge pipes, are attached to this vent header 9.
The lower end of the pressure vessel 1 is immersed in the pool water 6 and is disposed so as to discharge steam leaked from the pressure vessel 1 into the containment vessel 2.

For example, when high-temperature, high-pressure water vapor enters the containment vessel 2 due to a rupture in the primary system piping of the pressure vessel 1, and the pressure inside the containment vessel 2 increases, first, the inert gas sealed inside the containment vessel 2 The gas passes through the vent pipe 8 and is discharged into the pool water 6 of the pressure suppression chamber 5, and then the water vapor leaked into the containment vessel 2 passes through the vent pipe 8, the vent header 9, the downcomer 10, and is discharged into the pool water of the pressure suppression chamber 5. is discharged.

In this way, steam from the pressure vessel 1 is discharged into the pool water 6 and condensed, thereby suppressing a rise in pressure within the containment vessel.

Conventionally, the downcomer 10 uses pool water 6 in the pressure suppression chamber 5.
It is vertically immersed inside.

Therefore, in the event of a loss of coolant accident, as shown in Figure 2, the water contained in the downcomer 10 first becomes jet-like due to the pressure increase due to high-pressure steam leakage in the containment vessel 2 and flows to the bottom of the pressure suppression chamber. Upon collision, a large downward load is applied to the pressure suppression chamber (see Figure 2a).

Next, the gas in the containment vessel 2 is discharged, and as a result, the pool water rises due to the growth of compressed gas bubbles formed at the bottom of the downcomer, and an impact load is applied to the vent header 9 and the vent pipe 8 ( After that, an upward load is applied due to compression of the tube in the upper chamber of the pool (see FIG. 2C).

Therefore, the integrity of the pressure suppression chamber may be impaired by these loads.

Note that the gas in the containment vessel 2 is discharged and subsequently spreads within the containment vessel 2, and the steam diluted by the gas is discharged into the pool water in the pressure suppression chamber 5 and condenses.

This invention was devised to solve the problem that occurred in the pressure suppression chamber due to the gas discharge at the beginning of the accident, and it reduced the three loads shown in Figure 2 a''-'c above, making it extremely safe from a safety perspective. An object of the present invention is to provide an advantageous nuclear reactor containment system.

That is, the present invention provides a plurality of vent headers arranged in a pressure vessel housing the reactor body, and connected in pairs to a vent header extending from the lower part of the containment vessel into the toroidal pressure suppression chamber via a vent pipe. In order to reduce the amount of water inside the downcomer in the part of the downcomer that is submerged in water, inert gas is supplied to the inside of the containment vessel to raise the pressure to 300 to 1000100O higher than the pressure suppression chamber. A nuclear reactor containment system is characterized in that it holds.

Hereinafter, one embodiment of the present invention will be described with reference to FIG. 3, in which the same parts as in FIG. 1 are designated by the same reference numerals.

The downcomer according to the present invention has a pair of 22 as shown in Fig. 3.
Regarding the part of the downcomer 10 that is submerged in the pool water 6, in order to lower the liquid level 12 so that the amount of water inside this downcomer decreases, an inert gas such as nitrogen is injected into the containment vessel side. Pressure suppression chamber 5 by supplying gas
300 to 1,000,100 O1, the pressure is constantly maintained at a high pressure.

Therefore, because the liquid level 12 of the downcomer 10 is low, in the event of a loss of coolant accident due to pipe rupture, etc., air bubbles are generated when the amount of water in the downcomer 10 is small and the pressure on the containment vessel side is lower than in the conventional case. Therefore, the maximum downward load and maximum upward load at the beginning of the accident, as well as the impact load of pool water on the vent header 9 or the vent pipe 8, are reduced.

As explained above, the reactor containment system according to the present invention has the following effects.

(1) The downward and upward loads applied to the pressure suppression chamber can be reduced.

(2) The load applied to the vent pipe or vent header can be reduced.

(3) Obtained by easily repairing the conventional pressure suppression chamber at low cost.

As a device related to this invention, an experiment was conducted using an experimental device of 1/8 the actual scale, and the results shown in the table were obtained.

From these results, it is recognized that the present invention is effective in reducing the maximum downward load, maximum upward load, and vent header impact load.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing a conventional reactor containment system partially in side view, Fig. 2 is a schematic cross-sectional view diagrammatically showing the fluid behavior of pool water in the pressure suppression chamber shown in Fig. 1, and Fig. The figure is a longitudinal cross-sectional view showing the main parts of one embodiment of the nuclear reactor containment system according to the present invention. 1...Pressure vessel, 2...Containment vessel, 3
...Recirculation line, 4...Main steam pipe,
5... Pressure suppression chamber, 6... Pool water,
7... Space, 8... Vent pipe, 9...
...Vent header 10 ... Downcomer 11 ... Air bubbles, 12 ... Liquid level inside downcomer.

Claims (1)

[Scope of utility model registration request] In a reactor containment system, a pressure vessel housing a reactor main body is disposed in a containment vessel filled with inert gas, and a toroidal pressure suppression chamber is installed from the lower part of the containment vessel via a vent pipe. The pressure of the inert gas in the container is 300 to 1000 lower than the pressure in the toroidal pressure suppression chamber.
17. A nuclear reactor containment system characterized in that the amount of water inside the downcomers of the portions submerged in the pool water of the plurality of downcomers connected to the vent header of the vent pipe is reduced by increasing the pressure of the downcomers.