JP2607584B2 - Reactor containment vessel - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a containment vessel having a vacuum breaking structure.

[Conventional technology]

FIG. 5 shows an example of a conventional containment vessel vent pipe and a vacuum breaking structure.

FIG. 5 is a longitudinal sectional view showing the entire Mark II type containment vessel.

In FIG. 5, the reactor pressure vessel 1 is supported on a pedestal 3. In addition, the vent pipe 5 has a dry well 8.
Through the diaphragm floor 4 and into the water 10 of the suppression pool.

 This vent pipe 5 is provided with a vacuum breaking device 7.

In this structure, the functions of the vent pipe 5 and the vacuum breaking device 7 will be described.

When a breakage accident occurs in the piping inside the reactor containment vessel 2,
The dry well 8 is filled with high-temperature and high-pressure steam. It is necessary to guide the steam in the dry well 8 into the suppression water 10 to reduce the pressure in the containment vessel 2.

Therefore, a vent pipe 5 is piped from the dry well 8 through the diaphragm floor 4 to the suppression chamber water 10, and the vent pipe 5 is used to reliably pass the water into the steam pool water 10.

When the dry well 8 has a negative pressure with respect to the suppression chamber 9, the vacuum breaker 7 connects the dry well 8 and the suppression chamber 9 so as to eliminate the negative pressure. Check valve for each.

This negative pressure is generated when the core is re-flooded after the pipe rupture accident, and when the containment spray system operates.

As described above, the vacuum breaker has the purpose of protecting the negative pressure of the drywell. At the same time, if the drywell pressure rises due to a pipe breakage accident, the air and steam in the drywell are removed from the vacuum breaker. In order to make sure that the water is passed through the vent pipe into the pool water and condensed, it is required that the vacuum breaker must not abnormally leak into the suppression chamber space.

 Next, FIG. 6 will be described.

This structure is disclosed in Japanese Patent Application No. 62-88846, which is a prior application, and has a vent hole 6 in a pedestal 3 which is led into water in a suppression chamber. FIG. 1 shows an example in which an opening communicating with the sampling chamber 9 is provided, and a vacuum breaker 7 of the same type as that of the related art is installed in this opening.

[Problems to be solved by the invention]

The above-mentioned prior art, that is, the vent pipe or the vent hole has a structure led into the suppression chamber water and the structure in which the vacuum breaker is directly installed in the vent pipe or the vent hole. Because
There are the following problems.

When the high-temperature and high-pressure steam filled in the dry well is condensed by being introduced into the suppression water in the containment vessel at the time of the breakage of the pipe in the containment vessel, a condensation vibration (chucking) of the steam occurs at the vent pipe or at the tip of the vent hole. This vibration is caused by pulse-like fluctuations at the interface between steam and water due to a change in the steam condensation rate. During this condensation vibration, positive and negative pressure fluctuations occur in the vent pipe or the vent hole. .

At this time, in the prior art, since the vacuum breaking device is directly installed in the vent pipe or the vent hole, the vacuum breaking device opens and closes in small increments due to the above-mentioned pressure fluctuation. As a result, in the worst case, the vacuum breaking device There is a problem that the device undergoes plastic deformation, and the required function of the vacuum breaking device cannot fulfill the function of eliminating the negative pressure when the dry well becomes negative pressure and the function of separating the atmosphere between the dry well and the suppression chamber. .

An object of the present invention is to suppress the opening and closing operation of a vacuum breaker caused by pressure fluctuations caused by condensation of steam flowing through a vent passage, and to simplify the structure of a passage that connects a space of a pressure suppression chamber and a lower drywell. To provide a containment vessel that can be converted into a nuclear reactor.

[Means for Solving the Problems] A feature of the invention of claim 1 that achieves the above object is a dry well including an upper dry well and a lower dry well,
A containment vessel having therein a pressure suppression chamber isolated from the dry well, a pedestal supporting a reactor vessel disposed in the containment vessel, and disposed in the containment vessel; A diaphragm floor attached to the pedestal, an upper drywell formed between the reactor vessel and the containment vessel and located above the diaphragm floor, and below the reactor vessel inside the pedestal. A vent passage that communicates with each of the lower drywells formed in the pedestal and that guides the atmosphere of the drywell into cooling water that is provided in the pedestal and filled in the pressure suppression chamber; A space formed above a water surface and communicating with the lower dry well, and provided in the pedestal, Serial The vent passage lies in having a separated passage, a vacuum break device provided in the separated passage outside the pedestal.

[Operation] When the steam discharged from the dry well into the cooling water through the vent passage is condensed, a pressure fluctuation occurs in the vent passage due to the condensation vibration. Since it is installed in the passage, it is not affected by the pressure fluctuation. Therefore, the opening / closing operation of the vacuum breaker caused by the pressure fluctuation generated by the condensation of the steam flowing through the vent passage can be suppressed. In addition, the other separated passage connects the space of the adjacent pressure suppression chamber and the lower drywell via the pedestal in the containment vessel, so that the structure is simplified and the manufacture can be easily performed.

〔Example〕

 Hereinafter, embodiments of the present invention will be described.

In the first embodiment shown in FIGS. 1, 2 and 3, a reactor pressure vessel 1 is supported on a concrete pedestal 3 in a reactor containment vessel 2. FIG.

The atmosphere inside the reactor containment vessel 2 is divided into an upper dry well space 8 and a suppression chamber space 9 by a diaphragm floor 4. Suppression chamber water 10 is placed below the suppression chamber space 9.

The upper drywell space 8 and the lower drywell space 11 below the reactor pressure vessel 1 are communicated by a communication hole 12 provided in the pedestal 3. Of the communication ports 12a and 12b of the communication hole 12, a horizontal opening communicating the communication hole 12 and the suppression chamber space 9 above the lower port 12b so that water does not collect in the opening 13.
13 is provided with pedestal 3.

A vacuum breaker 7 is attached to an end of the opening 13 on the side of the suppression chamber space 9. This vacuum breaking device 7 is configured as shown in FIG. That is, there is a valve body 15 that is in contact with a flange 14 fixed to an end of the opening 13 via a ring-shaped packing 16. The valve body 15 is an arm 20
Attached to the flange 14 so as to be able to swing back and forth between the solid line display position and the chain line display position around the shaft 21 through the shaft. The arm 20 is attached to an air damper 17 via links 18 and 19 communicating with a shaft 21 so that a swinging motion of the valve body 15 can be given a diping action. Such a vacuum breaking device 7 has an effect that the valve element 15 opens to the inside of the opening 13 due to the pressure difference between the inside and outside of the opening 13.

As shown in FIGS. 1 and 2, the pedestal 3 has inlets 6a and 6b for the upper drywell space 8 and the lower drywell space 11, and is provided in the water 10 of the suppression chamber. A vent hole 6 having an outlet 6C is provided.

As shown in FIG. 2, the vent holes 6, the communication holes 12 and the openings 13 are provided at substantially equal intervals in the circumferential direction of the pedestal 3.

 The vacuum breaking action in this embodiment will be described.

The high-temperature and high-pressure steam that fills the drywell spaces 8 and 11 when a rupture accident occurs in the piping in the containment vessel 2 is led to the suppression water 10 through the vent hole 6. The pressure inside the containment vessel 2 is reduced. At this time, the positive and negative pressure fluctuations generated in the vent hole 6 due to the condensation vibration of the vapor generated at the tip of the vent hole 6 pass through the vent hole 6 to the dry well spaces 8, 11 which are large spaces. The pressure fluctuation is attenuated here, and the pressure fluctuation in the communication holes 12 and 13 becomes negligibly small.

Furthermore, the water that overflowed into the dry well spaces 8, 11 after the core was submerged after the pipe rupture accident or the water that was sprayed into the dry well space 8 when the containment spray system was activated causes the dry well space. The vapor filled in the section 8 is rapidly condensed, and the pressure in the dry well spaces 8, 11 is rapidly reduced, and becomes negative with respect to the pressure in the suppression chamber 9. In this state, the vacuum breaker 7 is opened, and the air in the suppression chamber space 9 is guided to the dry well spaces 8 and 11 through the communication holes 12 and 13 to eliminate the pressure difference, and each dry well is removed. The spaces 8, 11 and the suppression chamber space 9 have an even pressure. Through the above series of operations, the soundness of the reactor containment vessel 2 and the diaphragm floor 4 at the time of pipe breakage is ensured.

According to the present embodiment, the pressure fluctuation of the positive pressure and the negative pressure generated in the vent hole 6 due to the vapor condensation generated at the tip of the vent hole 6 at the time of the pipe breakage accident is caused by the upper dry well space 8 and the reactor pressure vessel. Due to the attenuation in the large space portion of the lower drywell space portion 11, in the communication hole 12, this pressure fluctuation becomes so small as to be negligible and is installed at the tip of the opening 13 branched from the communication hole 12. Vacuum breaker
The load due to this pressure fluctuation hardly acts. Thereby, the opening and closing movement of the vacuum breaking device due to the pressure fluctuation in the vent hole 6 can be prevented.

As described above, there is an effect that it is possible to prevent plastic deformation of the valve body or the valve body support mechanism of the vacuum breaker due to unnecessary opening / closing movement of the vacuum breaker due to vapor condensation generated at the end of the vent hole 6.

FIG. 4 shows a second embodiment of the present invention. The pedestal 3 is provided with an opening 13 which communicates with the lower well 11 of the reactor pressure vessel and the space 9 of the suppression chamber. The vacuum breaker 7 is installed at the tip of the portion on the side of the suppression chamber space 9, and the same effect as described above can be obtained in this embodiment.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, the opening / closing operation | movement of a vacuum breaker accompanying the pressure fluctuation generate | occur | produced by the condensation of the vapor | steam which flows through a vent passage can be suppressed. Further, the structure of the passage communicating the space of the pressure suppression chamber and the lower drywell is simplified, and the production can be performed easily.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a part of a containment vessel employing a spatial flow path of a vacuum breaking device according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along the line AA of FIG. Fig. 3 shows the first
It is an expanded sectional view of the vacuum breaker of a figure. FIG. 4 shows another embodiment. FIG. 5 is an overall view of a conventional containment vessel in which a vacuum breaker is installed in a vent pipe in a partial longitudinal sectional view. FIG. 6 is a longitudinal sectional view of a part of a containment vessel in which a vacuum breaker is installed in a vent hole of the prior application example. 1 ... Reactor pressure vessel, 2 ... Reactor containment vessel, 3 ...
Pedestal, 4 ... Diaphragm floor, 5 ... Vent pipe, 6 ... Vent hole, 7 ... Vacuum breaker, 8 ... Top dry well space, 9 ... Suppression chamber space, 10 ... Supplements Chamba pool water, 11 ……
Dry well space in the lower part of the reactor pressure vessel, 12 ... communicating hole, 13 ... pedestal through hole, 14 ... flange, 15 ...
Valve body, 16 ... Packing, 17 ... Air cylinder, 18 ... Arm, 19 ... Arm, 20 ... Arm, 21 ... Axle.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuo Horiuchi 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Inside the Hitachi Works, Hitachi, Ltd. (72) Yoshinori Tobita 3-2-2, Sachimachi, Hitachi-shi, Ibaraki No. 1 Hitachi Engineering Co., Ltd. (56) References Japanese Utility Model Sho-59-151192 (JP, U) Japanese Utility Model Sho-59-27499 (JP, U)

Claims (1)

(57) [Claims] 1. A dry well including an upper dry well and a lower dry well, a containment vessel isolated from the dry well and having a pressure suppression chamber therein, and a reactor vessel disposed in the containment vessel, And a pedestal disposed in the containment vessel, a diaphragm floor attached to the pedestal in the containment vessel, and formed between the reactor vessel and the containment vessel, and located above the diaphragm floor. An upper dry well, and communicates with each of the lower dry wells formed below the reactor vessel inside the pedestal, provided in the pedestal, and immersed in cooling water filled in the pressure suppression chamber. A vent passage for guiding the atmosphere of the dry well, and a space formed above the cooling water level in the pressure suppression chamber. An atom communicating with a lower drywell and provided in the pedestal and provided with a passage separated from the vent passage, and a vacuum breaker provided in the separated passage outside the pedestal; Furnace containment.