JPH02222872A - Cooling arrangement of reactor container - Google Patents

Abstract

PURPOSE:To maintain the soundness of a reactor container and to improve the safety thereof by disposing a water injection header between a reactor pressure vessel and a shielding wall and also by providing an opening for introducing cooling water into a pedestal region. CONSTITUTION:A container water injection header 10 connected to a branch pipe 11 from a dry well spray header 8 is disposed in a gap part between a reactor pressure vessel 2 and a reactor shielding wall 9, and further an opening 12 for introducing cooling water from the header 10 into the region of a pedestal 4 is provided in a support part of the vessel 2. In the case when an accident wherein a core is damaged and melted and the vessel 2 is broken down takes place, a spray cooling system is started and cooling water is injected from the header 8 into a dry well 3, while the cooling water from the header 10 is injected into the gap part between the vessel 2 and the wall 9 and flows into the region of the pedestal 4 through the opening 12. Accordingly, the core is cooled down directly and effectively, while erosion of concrete of the pedestal 4 is prevented, and thus the soundness of the vessel 2 can be maintained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a cooling device for a nuclear reactor containment vessel, and in particular, a reactor containment vessel suitable for application to a boiling water reactor. Regarding a cooling device.

(Prior Art) Generally, in a nuclear reactor, a reactor core is housed in a reactor pressure vessel for safety, and the reactor pressure vessel is housed in a reactor containment vessel.

FIG. 2 shows an example of a reactor containment vessel of a conventional boiling water reactor. Inside the reactor containment vessel 1, a reactor pressure vessel 2 containing a reactor core (not shown) is housed. A dry well 3, a pedestal 4 that supports the reactor pressure vessel 2, and a pressure suppression chamber 5 that surrounds the pedestal 4 and stores cooling water are provided.
The vent pipe 6 is connected to the pressure suppression chamber 5 by a vent pipe 6 extending into the water. In a reactor containment vessel configured in this way, in the event that a loss of coolant accident occurs in which the piping inside the reactor containment vessel ruptures, the mixture of steam and water released from inside the reactor pressure vessel will The steam is guided to the pressure suppression chamber 5 through the vent pipe 6 and condensed, thereby suppressing the increase in the internal pressure of the containment vessel, and the released radioactive substances are retained within the containment vessel 1. In addition, Drywell 3
A dry well spray header 8 is installed above the pressure suppression chamber 5 to inject cooling water from the pressure suppression chamber 5 into the dry well 3 using a pump 7, reducing the temperature and pressure inside the containment vessel in the event of a loss of coolant accident. A containment vessel spray cooling system is provided that maintains the integrity of the containment vessel 1 and prevents radioactive substances floating within the containment vessel 1 from leaking out of the containment vessel 1. In addition, in order to maintain the integrity of the core housed in the reactor pressure vessel 2 in the event of a loss of coolant accident as described above, an emergency core is installed to inject cooling water in the pressure suppression chamber 5 into the reactor. Multiple cooling systems (not shown) are installed.

(Problem to be Solved by the Invention) In the case that a loss of coolant accident occurs in the nuclear couplant configured as described above, core cooling will become insufficient for a long period of time due to multiple failures in the emergency core cooling system. In such a case, the core may be damaged and melted, and the molten core may melt and penetrate the bottom of the reactor pressure vessel and flow into the pedestal area at the bottom of the reactor pressure vessel. In addition, in such an accident, as mentioned above, the containment vessel spray cooling system is activated to reduce the temperature and pressure inside the containment vessel, but most of the cooling water sprayed into the dry well passes through the vent pipe. Because the melt flows into the pressure suppression chamber, there is a risk that the molten core that has flowed into the pedestal area may not be sufficiently cooled.

In this case, the high-temperature molten core would erode the concrete of the pedestal, which could make it impossible to maintain the integrity of the containment vessel.

As a result, the airtightness of the containment vessel cannot be ensured, and radioactive materials may be released into the environment.

Accidents such as this, in which the integrity of the containment vessel is threatened by core meltdown, exceed design basis accidents;
Although the probability of its occurrence is extremely small, if it were to occur it would result in great damage to the environment.

The present invention has been developed in view of the above-mentioned circumstances, and its purpose is to provide a nuclear reactor that cools the molten core that has leaked into the containment vessel in the event of a severe nuclear reactor accident in which the core melts and the reactor pressure vessel is damaged. An object of the present invention is to provide a containment vessel cooling device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a reactor containment vessel that stores a reactor pressure vessel housing a nuclear reactor, and cooling water in a pressure suppression chamber of the containment vessel. In a reactor containment vessel cooling system configured to supply a dry well spray header set at the top of a dry well of a vessel, the reactor pressure vessel is connected by a branch pipe from the dry well spray header to the reactor pressure vessel and the atom. A containment vessel water injection header is disposed in a gap between a reactor shielding wall surrounding the reactor pressure vessel, and the cooling water from the water injection header is supplied to a supporting portion of the reactor pressure vessel to support the reactor pressure vessel. It is characterized by having an opening for introducing the space into the space defined by the pedestal.

(Function) According to the reactor containment vessel cooling system of the present invention, in the event that a nuclear couplant design basis accident such as a loss of cooling accident is overcome,
A dry well spray header installed above the dry well to cool the molten core that has fallen into the pedestal area at the bottom of the reactor pressure vessel in the event of a severe accident in which the reactor core is damaged or melted and the pressure vessel is damaged. The reactor vessel is supported by cooling water from a containment vessel water injection header connected to the reactor vessel by a branch pipe from the reactor vessel and disposed in a gap between the reactor pressure vessel and a reactor shielding wall surrounding the reactor pressure vessel. It flows into the pedestal area through the opening that introduces it into the space surrounded by the pedestal.
The molten core is effectively cooled and the integrity of the containment vessel is maintained.

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

FIG. 1 is a schematic diagram of an embodiment of the present invention.

Note that the same parts as those of the conventional example shown in FIG. 2, which have already been explained, will be described with the same reference numerals.

In the figure, inside the reactor containment vessel 1 is a reactor core (not shown).
A dry well 3 in which the reactor pressure vessel 2 is stored, a pedestal 4 that supports the reactor pressure vessel 2, and a pressure suppression chamber 5 that surrounds the pedestal 4 and stores cooling water.
The dry well 3 and the pressure suppression chamber 5 are communicated with each other by a vent pipe 6 extending into the water of the pressure suppression chamber 5. A dry well spray header 8 is installed at the top of the dry well 3 to inject cooling water from the pressure suppression chamber 5 into the dry well 3 using a pump 7. A containment vessel spray cooling system is provided that maintains the integrity of the containment vessel 1 by reducing the pressure and prevents radioactive materials floating within the containment vessel 1 from leaking out of the containment vessel 1.

In addition, multiple emergency core cooling systems (not shown) are installed for injecting cooling water in the pressure suppression chamber 5 into the reactor.

Furthermore, a containment vessel water injection header 1 is installed in the gap between the reactor pressure vessel 2 and the reactor shielding wall 9 surrounding the reactor pressure vessel.
0 is installed, and the water injection header 10 is connected by a branch pipe 11 from a dry well spray header 8 installed above the dry well housing the nuclear reactor. Further, the support portion of the reactor pressure vessel 2 is provided with an opening 12 through which cooling water from the containment vessel water injection header 10 is introduced into a space below the reactor pressure vessel surrounded by the pedestal 4.

In a nuclear couplant with a containment vessel cooling system configured in this way, in the unlikely event that an accident occurs in which core cooling becomes insufficient for a long period of time due to multiple failures in the emergency core cooling system, the core may be damaged or melted, and the nuclear In the event of a severe accident in which the bottom of the reactor pressure vessel 2 melts and penetrates and leaks into the pedestal area at the bottom of the reactor pressure vessel, the containment vessel 1
In order to reduce the temperature and pressure inside the containment vessel, the containment vessel spray cooling system is activated, cooling water is injected from the dry well spray header 8 to the dry well 3, and cooling water from the containment vessel water injection header 10 is Water is injected into the gap between the reactor pressure vessel 2 and the reactor shielding wall 9 surrounding the reactor pressure vessel, and flows into the pedestal area through an opening 12 provided in the support of the reactor vessel. Therefore, the reactor core spilled into the pedestal area is directly and effectively cooled by the cooling water, preventing concrete erosion of the pedestal and maintaining the integrity of the containment vessel. Accidents can be brought to a close without resulting in release into the environment.

〔Effect of the invention〕

As described above, according to the reactor containment cooling system of the present invention, the integrity of the reactor containment vessel can be maintained against severe accidents that lead to pressure vessel failure after core meltdown.
The safety of nuclear reactors can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of a conventional reactor containment vessel cooling system. 1... Reactor containment vessel 2... Reactor pressure vessel 3
...Drywell 4...Pedestal 5...
Pressure suppression chamber 6... Vent pipe 7... Pump 8... Dry well spray header 9... Reactor shielding wall lO... Containment vessel water injection header 11... Branch pipe 12... Opening (873
3) Agent: Yoshiaki Inomata, patent attorney (and one other person)

Claims (1)

[Claims] (1) Supply cooling water from the reactor containment vessel that houses the reactor pressure vessel housing the reactor and the pressure suppression chamber of the containment vessel to the dry well spray header set at the top of the dry well of the containment vessel. In the reactor containment vessel cooling system configured as above, the reactor containment vessel cooling system is connected by a branch pipe from the dry well spray header and is stored in a gap between the reactor pressure vessel and a reactor shielding wall surrounding the reactor pressure vessel. A vessel water injection header is disposed, and an opening is further provided in the support portion of the reactor pressure vessel for introducing cooling water from the water injection header into a space surrounded by a pedestal supporting the reactor pressure vessel. Features: Reactor containment vessel cooling system.