JPH06235789A - Nuclear reactor - Google Patents

Abstract

PURPOSE:To enhance reliability in the safety system of a nuclear reactor by providing a uniform pressure injection system for injecting cooling water into a pressure vessel at the time of emergency. CONSTITUTION:Cooling water is filled between a pressure vessel 2 for reactor and a reactor containing vessel 3 thus establishing a wet well structure and a uniform pressure injection system 10 is provided while communicating the inside and the outside of the pressure vessel 2 in order to inject cooling water into the pressure vessel 2 at the time of emergency. The cooling water serves as a shielding member during operation of a nuclear reactor 1. Upon occurrence of an emergency, e.g. water level drop in the pressure vessel 2, the uniform pressure injection system 10 functions to equalize the pressure at the inside and the outside of the pressure vessel 2 and cooling water is injected immediately into the pressure vessel due to the water level difference between the inside and the outside of the pressure vessel 2 thus cooling the reactor core 5 emergently.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to nuclear reactors.

[0002]

2. Description of the Related Art In a conventional nuclear reactor, if the water level in the reactor pressure vessel is lowered due to a break in the primary system piping or a break in the steam generator thin tube, the outside of the reactor containment vessel must be prepared. A cooling water storage tank for emergencies is provided, and in an emergency it is safe to forcibly introduce cooling water into the pressure vessel by operating a pump or motor provided in the pipe connecting the cooling water storage tank and the pressure vessel. The system is organized.

[0003]

However, as an emergency safety system of this kind, cooling water is promptly introduced into the pressure vessel by natural force such as gravity in an emergency, without relying on external power such as a pump or a motor. Passive safety systems are originally ideal because of their high reliability.

An object of the present invention is to provide a novel nuclear reactor equipped with such a highly reliable passive safety system.

[0005]

In order to achieve the above object, the reactor of the present invention fills the space between the reactor pressure vessel and the reactor containment vessel accommodating the reactor pressure vessel with cooling water. In order to inject into the pressure vessel in an emergency, a pressure equalizing and injecting system for communicating the inside and outside of the pressure vessel is provided.

[0006]

According to the reactor of the present invention configured as described above, since the reactor pressure vessel itself is immersed in the cooling water, in the unlikely event that the primary system pipe is broken or the steam generator thin tube is broken. When the water level in the pressure vessel drops due to such things as the above, the pressure inside and outside the pressure vessel is equalized by the operation of the pressure equalization injection system, and the cooling water is immediately released due to the water level difference (head difference) inside and outside the pressure vessel. It is injected into a pressure vessel and used for core cooling. Further, the steam jetted out of the pressure vessel due to such pipe breakage or the like is immediately condensed in the cooling water.

[0007]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 conceptually shows the structure of a reactor according to the present invention. This reactor 1 comprises a reactor pressure vessel 2 and a closed reactor containment vessel 3 for accommodating the pressure vessel 2. It has a wet well structure in which the space is filled with cooling water 4. The reactor containment vessel 3 has a spherical portion 3a which constitutes a large part of the containment vessel 3,
The pressure vessel 2 is supported and fixed in a state in which the lower end 2b on which the reactor core 5 is installed is located inside the columnar portion 3b of the containment vessel 3. ing. The pressure vessel 2 is covered with a heat insulating material 27. The water level ha of the cooling water 4 is the standard water level hb of the pressure vessel 2.
And the upper lid 2a of the pressure vessel 2 is maintained at a predetermined water level that does not flood. Therefore, although not shown here, the main steam nozzles and other primary system pipes connected to the side wall of the pressure vessel 2 are immersed in the cooling water 4 in the reactor containment vessel 3.

The containment vessel 3 is provided with a pool water cooling system 6 for keeping the cooling water 4 at a predetermined temperature or less at all times. The pool water cooling system 6 includes a heat pipe type cooler 7 arranged in the cooling water 4 and a radiator 8 arranged outside the storage container 3, and the cooler 7 and the radiator 8 are arranged. With the valve 29 provided in the pipe 28 connecting between the two being open, the refrigerant naturally circulates by natural air cooling to cool the cooling water 4 in the storage container 3.

On the other hand, the pressure vessel 2 is provided with an automatic depressurization system 9 for adjusting the inside of the pressure vessel 2 to a predetermined pressure or less, and the cooling water 4 is supplied to the pressure vessel 2 in an emergency situation where the water level in the pressure vessel 2 is lowered. A pressure equalization injection system 10 for injecting into the inside of the reactor 2 and a residual heat removal system 11 for removing decay heat after the reactor shutdown are provided.

The automatic depressurization system 9 includes an upper lid 2a of the pressure vessel 2.
The automatic control valve 13 is provided in the middle of the pipeline of the pipe group 12 disposed in the pressure vessel 2. When the pressure inside the pressure vessel 2 rises, the automatic control valve 13 opens, and the high temperature and high pressure atmosphere is released to the outside of the pressure vessel 2. Is configured to escape. The gas discharge port 9a of the pipe group 12 of the automatic depressurization system 9 is arranged in the cooling water 4, and the discharged high temperature gas can be cooled by the cooling water 4.

The pressure equalizing injection system 10 is evenly arranged on the upper portion of the side wall so as to make the upper space 14 in the pressure vessel 2 and the upper space 15 in the storage container 3 communicate with each other in an emergency to equalize the pressures in both spaces. A plurality of escape pipes 16 and a cooling vessel 4 for cooling water 4 in an emergency
It is composed of a plurality of injection tubes 17 which are evenly arranged in the middle of the side wall so as to be injected into the inside. The on-off valves 18 and 19 provided on the relief pipe 16 and the injection pipe 17 are normally closed and are opened only in an emergency.

The residual heat removing system 11 is provided with water 20 in the pressure vessel 2.
A heat exchanger 2 installed outside the storage container 3 for removing residual heat
2 is a facility for guiding it through a pipe 21 to cool it, and then circulating it into the pressure vessel 2. A pump 23 for forcibly circulating the water 20 is provided in the middle of the pipeline. The residual heat removal system 11 has a test line 25 for circulating the cooling water 4 in the storage container 3 in order to periodically test whether or not a dynamic device such as the pump 23 or the valve 24 operates safely. Is provided. Reference numeral 26 is a valve that is opened when the test line 25 is activated.

In the normal operation of the nuclear reactor 1 constructed as described above, the cooling water 4 in the containment vessel 3 is kept below a predetermined temperature by the operation of the pool water cooling system 6.
The operation is performed under the control of a predetermined output. At this time, the cooling water 4 filling the inside of the storage container 3 also functions as a shielding material.

In the unlikely event that the water level in the reactor pressure vessel 2 drops, the safety systems of the automatic depressurization system 9, the pressure equalization injection system 10 and the residual heat removal system 11 will be as follows. Works like.

When the drop in the water level in the pressure vessel 2 is caused by the breakage of a thin tube such as a steam generator or a small diameter breakage of other primary system piping, the automatic pressure reducing system 9 is activated and the pressure equalizing injection system 10 is released. All on-off valves 18 of the pipe 16 are opened. As a result, the pressure inside the pressure vessel 2 is equalized, and the on-off valve 19 of the injection pipe 7 is subsequently opened, so that the cooling water 4 is immediately injected into the pressure vessel 2 due to the water level difference between the inside and the outside of the pressure vessel 2 at that time. And is used for emergency cooling of the core 5.
At the same time as the injection of the cooling water 4, the residual heat removal system 11 operates,
The water 20 in the pressure vessel 2 heated by the decay heat is cooled for a long period of time.

Further, when the water level drop in the pressure vessel 2 occurs due to a breakage of the main steam nozzle and other large-diameter pipes, the inside and outside of the pressure container 2 communicate with each other by the pipe breakage itself, and the pressure is naturally and rapidly equalized. The relief pipe 16 and the injection pipe 17 of the pressure equalization injection system 10 are immediately activated without activating the automatic pressure reducing system 9. As a result, the cooling water 4 is immediately injected into the pressure vessel 2 and is used for emergency cooling of the core 5. In addition, since the steam ejected to the outside of the pressure vessel 2 due to such pipe breakage is immediately condensed in the cooling water 4,
It is possible to effectively prevent a pressure increase in the containment vessel 3 due to the high temperature steam jetting. In this case as well, the residual heat removal system 11 operates at the same time as the injection of the cooling water 4, and the pressure vessel 2 is heated by the decay heat.
Long-term cooling of the water 20 therein is performed.

As described above, the safety system of the nuclear reactor 1 can effectively cope with the small diameter fracture and the large diameter fracture.
In the case of an emergency situation where the water level in the pressure vessel 2 is lowered, the pressure equalizing injection system 10 immediately cools the cooling water 4 by the water level difference between the inside and outside of the pressure vessel 2 without relying on external power such as a pump or a motor. Can be injected into the pressure vessel 2 and used for emergency cooling of the reactor core 5, so that it is a highly reliable safety system. Further, the pressure equalizing injection system 10 can remarkably simplify the apparatus configuration as compared with the conventional method of injecting cooling water from the outside of the containment vessel through a pipe, and can downsize the entire reactor. it can.

[0019]

In summary, in the reactor of the present invention, the reactor pressure vessel itself is immersed in the cooling water, and in an emergency, the pressure equalization inside and outside of the pressure vessel is equalized by the operation of the pressure equalization injection system, and the cooling water naturally flows. Is injected into the pressure vessel and is used for emergency cooling of the core, so the reliability of the safety system is extremely high.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a nuclear reactor of the present invention.

[Explanation of symbols]

 1 Reactor 2 Reactor Pressure Vessel 3 Reactor Containment Vessel 4 Cooling Water 5 Core 9 Automatic Pressure Reduction System 10 Equalization Injection System 11 Remaining Heat Removal System 16 Escape Pipe 17 Injection Pipe

Claims (1)

[Claims] 1. A uniform filling means for filling a space between a reactor pressure vessel and a reactor containment vessel containing the cooling water with cooling water, and communicating the inside and outside of the pressure vessel so as to inject the cooling water into the pressure vessel in an emergency. A nuclear reactor characterized by having a pressure injection system.