JPS6085391A - Main steam relief safety valve exhaust system - 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 provides a relief safety valve exhaust pipe device that prevents bubble pulsation by improving the main steam discharge section and also improves the arrangement within the suppression pool. Relating to a safety relief valve exhaust system that has been designed to

[Background of the invention]

Conventionally, as shown in Fig. 1, Fig. 2, and Fig. 3, a nuclear reactor l
In order to prevent an abnormal pressure rise in the main steam pipe 2, a relief safety valve 3 is installed in the main steam pipe 2, and its exhaust pipe 4 extends into the water of the suppression pool 6 of the pressure suppression chamber 5, and the steam discharge conduit 7 It is designed to release steam into the water.

The vapor discharge conduit 7 used had two horizontally oriented openings. However, such a structure has the disadvantage that bubble pressure pulsations, which will be described later, are large.

Here, bubble pressure pulsation will be explained using FIG. 4. Before the relief safety valve 3 is opened, the inside of the exhaust pipe 4 is filled with air, and the water column is at the water level of the boule 6.

When the relief safety valve 3 opens, steam inside the reactor l? It is released into the safety valve exhaust pipe 4, compressing the air inside the pipe and forcing it downward into the water column inside the pipe. Since the steam is discharged at the speed of sound, there is little mixing between air and steam, and the air is discharged from the steam discharge conduit 7 into the boule water 6 in the form of bubbles. During this time, the air is pressurized to 20-30 kg/crn2g, so it expands rapidly in the water. At this time, the surrounding water is pushed away, so even if the pressure of the bubble falls due to the underwater pressure, the bubble expands further due to the inertia of the water, and the bubble pressure becomes negative pressure. When the inertia disappears, the surrounding water is pulled away by the negative pressure of the bubble, and the bubble is compressed in the opposite direction, and the inertia of the water pressurizes the bubble, so the bubble pressure is higher than the pressure when it was first released. Become. As the gas expands and compresses in this way, the bubbles rise to the surface of the water. This state is called total bubble pressure pulsation, and this pulsation continues until the bubble rises to the water surface, as shown in FIG. In addition, A, B, C, and D in Fig. 5 are the fourth factor A,
B.

It corresponds to C and D.

The bubble pressure pulsations become underwater waves and are added to the structure in the boule 6, acting as a dynamic load. This load is considered to be proportional to the air pressure inside the exhaust pipe. According to measurement results at actual plants in the United States and other countries, this underwater wave is 5-15H.
z, positive pressure 3Kg/C1n"g.

The negative pressure reaches -1,s Kg/z'g, which lasts about 1 second until the bubble bursts on the water surface.

The repeated operation of the relief safety valve 3 during the life of the plant will be 40,000 to 50,000 times, and the bubble pressure pulsations will add fatigue stress to the structural members under the water surface and the relief safety valve exhaust pipe 4. The design conditions are extremely severe.

It is necessary to alleviate such severe load conditions, increase the margin for the soundness of the structure, and reduce the economic burden during the production of structural materials by reducing design conditions.

[Purpose of the invention]

The present invention eliminates bubble pressure pulsation due to air in the exhaust pipe released into the pool water by isolating the relief safety valve exhaust pipe device. The purpose of the present invention is to provide a relief safety valve exhaust pipe device that reduces the design load of structural materials in swimming pool water.

[Summary of the invention]

This requires a structure in which a cylindrical and circumferentially arranged exhaust system area is installed in the suppression pool area, an exhaust pipe is led into the area, and the exhaust pipes are connected together with a connecting pipe.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings. As shown in FIGS. 6, 7, and 8, a cylindrical and circumferential steam release area is installed in the suppression pool section 6, and an exhaust pipe 7 is introduced into it. It shall be combined into a connecting pipe 12 (header type). The submersible cylindrical exhaust device has a number of openings 11Th and is placed at a sufficient depth so that the steam released therefrom can condense.

According to the present invention, a cylindrical exhaust device is installed, and
Since the exhaust pipe 7 is guided through it, there is no need for exhaust pipes that are distributed in a conventional manner, and as shown in Fig. 7, the arrangement of the suppression pool section can be made compact, and the design, installation, and maintenance of equipment can be improved. becomes very easy.

Furthermore, according to the present invention, dynamic loads can be reduced.

This will be explained in detail below. The process of air bubble pulsation and pressure change when air is released into water through the steam release device of the present invention is shown in FIG. In this case, as before, A.

By repeating processes B, C, and D, air bubbles are released into the water, and these air bubbles rise while repeatedly expanding and compressing. However, according to the present invention, the exhaust system part can be set at any position, and the load applied to the subreaction guru central part can be significantly reduced by attenuating the amount of discharge. For example, if it is close to the reactor containment vessel 13, by directing the air outlet only toward the RPV pedestal 14 side, the RPV pedestal 14 and the reactor containment vessel 1 can be
The dynamic loads applied to 3 are significantly reduced.

〔Effect of the invention〕

Since the present invention is configured and operates as described above, it has the following effects.

(1) The layout inside the suppression pool becomes more compact, making design and construction easier.

(2) The exhaust system can be set in any position, and the dynamic loads applied to structural materials underwater can be significantly reduced.

[Brief explanation of the drawing]

Figure 1 is a partial view of the M A RK-II type reactor containment vessel, Figure 2 is a partial view of the conventional relief safety valve steam release conduit,
Figure 3 is a plan view of the suppression pool inside the containment vessel, Figure 4 is an explanatory diagram showing the process of air bubble pressure pulsation due to relief safety valve exhaust shown in Figure 2, and Figure 5 is the air bubble pressure in the process of Figure 4. FIG. 6 is a diagram showing an embodiment of the present invention, FIG. 7 is a plan view of the same, and FIG.
The figure is a graph showing the relationship between air bubble pressure and time in the process according to the invention. l... Nuclear reactor, 2... Main steam pipe, 3... Safety relief valve, 4... Exhaust pipe, 5... Pressure suppression chamber, 6... Suppression pool, 7... Steam release Conduit, 8...
Particle column, 9... diaphragm floor,
1 (1... cylindrical exhaust device, 11... open 0.12.
...Connecting pipe, 13...Reactor containment vessel, 14...I
(PV Pedestal. Agent Patent Attorney Akio Takahashi #1 Ward 3rd Ward #4 Ka (A> (B) (c) CD) Accessories $, 7 Figure 8 $8 Shun Zusaki

Claims (1)

[Claims] 1. In a reactor containment vessel that opens into a suppression pool in an exhaust pipe full pressure suppression chamber connected to the main steam pipe via a safety relief valve, an exhaust area is defined along the circumference of the suppression pool. Install it and put an exhaust pipe in it? Installed a main steam relief safety valve exhaust system that is fully featured. 2. Claims No. 1 provides that in the circumferential exhaust pipe device part, a steam discharge part is incorporated into a connecting pipe to a steam discharge part in water (!: main steam relief safety valve exhaust Device.