KR102267104B1 - Cooling system for external wall of reactor vessel and cooling method of external wall of reactor vessel using the same - Google Patents

Abstract

The present invention relates to a system for cooling the outer wall of a reactor vessel using the gravity method in case of a serious accident and a method for cooling the outer wall of the reactor vessel using the same, a reactor building in which a reactor vessel and a steam generator are located, the reactor vessel is located, A reactor cavity formed so that at least a part of the reactor vessel can be submerged by emergency coolant, a dedicated water tank located higher than an upper end of the reactor vessel inside the reactor building and storing emergency coolant, and emergency coolant in the dedicated water tank to the reactor A first pipe formed to supply the cavity, a water filling pipe extending outside the reactor building and formed to fill the exclusive water tank with emergency cooling water, and an external pipe connecting part formed in at least a part of the filling pipe, , The emergency coolant of the dedicated water tank relates to a reactor vessel outer wall cooling system that can be supplied to the reactor cavity by gravity method and a cooling method using the same.

Description

A reactor vessel outer wall cooling system and a reactor vessel outer wall cooling method using the same {COOLING SYSTEM FOR EXTERNAL WALL OF REACTOR VESSEL AND COOLING METHOD OF EXTERNAL WALL OF REACTOR VESSEL USING THE SAME}

The present invention relates to a system for cooling the outer wall of a reactor vessel using the gravity method in case of a serious accident and a method for cooling the outer wall of the reactor vessel using the same.

During normal operation of a nuclear power plant, the core inside the reactor vessel is cooled by the coolant circulated by the coolant pump. However, if a serious accident such as loss of off-site power occurs, core cooling is no longer performed and the core temperature rises. When the core melt temperature is reached, the core melts and the core melt is relocated to the bottom of the reactor vessel ( relocation) will take place.

In such a critical accident, a lot of decay heat is generated from the core melt. This causes the reactor vessel to overheat and break, eventually discharging the core melt to the outside of the reactor vessel. The core melt of a nuclear power plant contains radioactive isotopes, and when the melt is released to the outside of the reactor vessel, the atmosphere inside the reactor building is radioactively polluted, causing damage to the reactor building and pollution of the external atmosphere.

As a means to prevent this, conventionally, the reactor cavity was filled using coolant and a pump of an In-containment Refueling Water Storage Tank (IRWST) in a nuclear reactor building. However, since this method uses an active pump, there is a problem that an appropriate response is not provided when power is not supplied to the pump.

In addition, since an active pump is used to replenish the spent fuel storage tank and passive condensate cooling tank, which have coolant stored in major systems such as the spent fuel storage tank cooling system and passive auxiliary water supply system of nuclear power plants, there is a countermeasure facility for filling in an emergency. need.

Korean Patent Registration No. 1242746 (published on March 6, 2013) Korean Patent Publication No. 2018-0079739 (published on July 11, 2018)

It is an object of the present invention to provide a reactor vessel outer wall cooling system and a reactor vessel outer wall cooling method that can cool the outer wall of a reactor vessel in the event of a serious accident caused by loss of AC power, etc., and can be easily recharged from the outside.

An object of the present invention is to provide a reactor vessel outer wall cooling system, a reactor building in which a reactor vessel and a steam generator are located, a reactor cavity in which the reactor vessel is located and at least a part of the reactor vessel is submerged by non-commercial coolant. part, an exclusive water tank located higher than the upper end of the reactor vessel inside the reactor building and storing emergency coolant, a first pipe formed to supply emergency coolant in the exclusive water tank to the reactor cavity, extending outside the reactor building and an external pipe connection formed in at least a part of the charging pipe and a charging pipe formed to fill the exclusive water tank with emergency cooling water, and the non-commercial cooling water of the exclusive water tank is supplied to the reactor cavity by gravity. This is achieved by possible reactor vessel outer wall cooling systems.

It is positioned higher than the upper end of the steam generator outside the reactor building and further includes a passive condensation cooling tank for removing residual heat of the steam generator, and the emergency cooling water of the dedicated water tank is formed to be supplied to the passive condensation cooling tank in a gravity manner. A second pipe may be further included.

It may further include a spent fuel storage tank positioned lower than the dedicated water tank outside the reactor building, and a third pipe formed to supply emergency cooling water of the dedicated water tank to the spent fuel storage tank in a gravity manner.

It further includes a lower cavity formed under the reactor vessel, and the lower cavity may further include a sealing plate for preventing the coolant from leaking downward.

The external pipe connection part may be coupled to a fire hose of a fire engine or an outdoor fire hydrant.

It may further include a first valve located on the first pipe and opened and closed by a DC power supply.

The DC power source may be a secondary battery, and the secondary battery may be installed to be charged with power supplied from an AC power source.

The dedicated water tank may be located in a dome-shaped upper portion of the reactor building.

The shape of the horizontal cross section of the exclusive water tank may be one selected from a circle or a donut shape, and the bottom surface of the exclusive water tank may have a shape that is higher in the center and lowered toward the outer peripheral surface.

At least a portion of the external pipe connection part may include a structure that has flexibility and can be stored in a reel shape or a folded form.

As another solution means for achieving the object of the present invention, a nuclear reactor building including a reactor vessel and a steam generator therein, the reactor vessel is located, and at least a part of the reactor vessel is formed so that it can be submerged by the emergency coolant. A cavity, an exclusive water tank located in the dome-shaped part inside the reactor building and capable of storing emergency coolant, a first pipe formed to supply emergency coolant from the exclusive water tank to the reactor cavity, and extending outside the reactor building , a charging pipe formed to fill the exclusive water tank with emergency cooling water, an external pipe connection part formed in at least a part of the charging pipe, and a first valve opened and closed by a DC power source in at least a part of the first pipe. A method for cooling the outer wall of a reactor vessel using a vessel outer wall cooling system, the emergency coolant supply step of supplying the emergency coolant from the dedicated water tank to the reactor cavity by opening the first valve, connected to at least one selected from a fire engine or an outdoor fire hydrant This is achieved by a method for cooling the outer wall of a reactor vessel, which includes a fastening step of fastening the fire hose and the external pipe connection part, and a filling step of supplying fire water from the fire engine or outdoor fire hydrant to the dedicated water tank after the fastening step.

According to the present invention, not only provides a fast and stable cooling function for the reactor vessel even in an accident in which the use of active equipment is impossible, such as loss of AC power, but also emergency charging of the spent fuel storage tank and passive condensing cooling tank is possible, so the safety and reliability of the nuclear power plant can be improved, and emergency filling equipment can be configured economically and easily.

1 shows a reactor vessel outer wall cooling system according to an embodiment of the present invention.
FIG. 2 is an enlarged view of part A of FIG. 1 .
3 is a view showing a sealing plate in the reactor vessel outer wall cooling system according to an embodiment of the present invention.
4 shows various examples of the form of a dedicated water tank of the present invention.
5 shows various examples of the form of the external pipe connection part of the present invention.
6 is a view showing a method of operating a reactor vessel outer wall cooling system according to an embodiment of the present invention.
7 illustrates a state in which emergency coolant is supplied to the reactor cavity in the reactor vessel outer wall cooling system according to an embodiment of the present invention.

The present invention is for cooling the outer wall of a reactor vessel by rapidly and stably filling the reactor cavity using emergency cooling water in a dedicated water tank located at the top of a nuclear power plant, even in an accident in which power supply of a nuclear power plant is impossible, using natural driving force due to gravity. It's about the system.

In addition, by using the dedicated water tank located at the top of the reactor building, the spent fuel storage tank that stores and cools the spent fuel in the power plant and the passive condensate cooling tank that performs the residual heat removal function through the steam generator can be emergency filled to prevent additional accidents. Also, it is possible to extend the present invention to various storage tanks and tanks.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

Since the accompanying drawings are only an example shown in order to explain the technical idea of the present invention in more detail, the spirit of the present invention is not limited to the accompanying drawings. In addition, in the accompanying drawings, the size and spacing may be exaggerated differently from reality in order to explain the relationship between each component.

1 shows a reactor vessel outer wall cooling system according to an embodiment of the present invention. The power plant building for nuclear power generation consists of a nuclear reactor building 10 , an auxiliary building 700 , and annexed buildings.

A reactor vessel 300 and a steam generator 400 are positioned inside the reactor building 10 . In the present invention, the dedicated water tank 100 in which the emergency coolant is stored to be used for cooling in an emergency is located higher than each space to which the emergency coolant is to be supplied in an emergency so that the emergency coolant can be supplied by its own weight in an emergency. do. Therefore, it is positioned higher than the upper end of the reactor vessel 300 or the upper end of the steam generator 400 . In this embodiment, the dedicated water tank 100 is located in the dome-shaped upper end of the nuclear reactor building 10 .

FIG. 2 is an enlarged view of part A of FIG. 1 . The reactor vessel 300 is located in the reactor cavity 210 formed by the reactor cavity structure 240 . In addition, the lower cavity 220 is also formed in the lower part of the reactor vessel 300 by the reactor cavity structure 240 . In FIG. 1, the steam generator 400 is illustrated as having two, but may be one or three or more, and is not particularly limited.

Sealing plate 230 for minimizing water leakage downward from the lower cavity 220 under the reactor vessel 300 in order to quickly fill the reactor cavity 210 with water to submerge the reactor vessel 300 . ) is installed. 3 shows the sealing plate 230 in more detail. The sealing plate 230 is installed to fit the outer circumference of the lower cavity so that the emergency coolant supplied from the upper part of the lower cavity 220 does not escape below the lower cavity 220, and the sealing plate 230 has an ICI guide. A plurality of through holes 231 are formed so that the tube can pass therethrough.

It is connected to the first pipe 610 so that the emergency coolant of the dedicated water tank 100 can be supplied to the reactor cavity 210 in an emergency. Although the first pipe 610 is shown as two in FIG. 1, it may be one or three or more, but two or more are preferable in consideration of installation and maintenance.

Water in the dedicated water tank 100 may be filled through a cooling water pipe of a general power plant cooling water system, and related pipes are not shown separately. When the operation of the active pump of the power plant is impossible due to an accident such as loss of external power, a water filling pipe 500 is configured to fill the dedicated water tank 100 with water. One end of the water filling pipe 500 is connected to supply water to the dedicated water tank 100 , and an external pipe connection part 510 is provided at one end of the outside extending to the outside of the nuclear reactor building 10 . The external pipe connection part 510 may be provided in plurality to effectively fill the dedicated water tank 100 .

In addition, it can be used to remove residual heat of the steam generator through the passive auxiliary water supply system in case of an accident, and the residual heat removal of the steam generator 400 is formed to exchange heat with the steam generator by continuously supplying the cooling water of the passive condensation cooling tank 800 . To solve the problem, a second pipe 620 is provided. The passive condensation cooling tank 800 is located above the steam generator 400 so that the heat of the steam generator can be circulated naturally. Therefore, the dedicated water tank 100 is located higher than the passive condensation cooling tank 800 to supply emergency cooling water by gravity in case of an accident.

Similar to the use of the passive auxiliary water supply system in case of an accident, it can be used for continuous cooling of the spent fuel 720 in the spent fuel storage tank 710 through the spent fuel storage tank cooling system, and for this purpose, the emergency coolant in the dedicated water tank 100 A third pipe 630 is provided so that it can also be supplied to the spent fuel storage tank 710 . The dedicated water tank 100 is installed to be located higher than the spent fuel storage tank 710 so that emergency coolant can be supplied to the spent fuel storage tank 710 by gravity by its own weight.

The filling pipe 500 is provided with a filling valve 520 capable of supplying emergency coolant in the dedicated water tank.

The first pipe 610, the second pipe 620, and the third pipe 630 have respective first valves 611, second valves 621 and A third valve 631 is provided. Each valve is driven by a DC power supply to enable control such as opening and closing of each valve (the first valve, the second valve, the third valve, and the filling valve) even in an accident in which the external power source, AC power, is lost. Here, the DC power source is preferably a battery such as a primary battery or a secondary battery, and more preferably a secondary battery. The secondary battery for driving the valve is installed to maintain a fully charged state by AC power before an accident occurs.

4 shows various examples of the form of the dedicated water tank 100 of the present invention. The dedicated water tank 100 may be positioned by utilizing the space of the dome-shaped portion of the nuclear reactor building 10, and at least a portion of the outer peripheral surface of the dedicated water tank may be formed along the outer circumference of the dome for space utilization. The exclusive water tank 100 may be formed in a disk shape of a general form as shown in (a) of FIG. 4, and a horizontal cross-section may be formed in a donut shape along the outer circumferential surface of the dome as shown in FIG. 4(b). As shown in (c) of FIG. 4, water is filled from the top of the dome, and the bottom surface of the exclusive water tank 100 has an oval or arch shape in cross section, and the middle part is high, and as it goes outward, the bottom surface of the water tank 100 is filled with water. It may be in a lowered form. Figure 4 (d) shows a structure similar to (c), but a structure having an arcuate shape formed by being spaced apart from the upper end of the dome shape in the upper surface of the exclusive water tank 100. As shown in FIG. Such examples are examples in which the space of the inner surface of the hemispherical dome-shaped part can be appropriately utilized, and various changes are possible if the structure can utilize the space of the hemispherical dome-shaped part.

The external pipe connection part 510 may be formed at one end of the filling pipe 500, and a plurality of external pipe connection parts 510 may be formed in one filling pipe 500 to facilitate filling. It is preferable that the external pipe connection part 510 is formed so that it can be easily combined with a fire engine or an outdoor fire hydrant to receive emergency coolant. Therefore, it is preferable that the external pipe connection part 510 is formed where the water filling pipe 500 extends to a position where a fire engine can easily access it.

5 shows various examples of the form of the external pipe connection part 510 of the present invention. At least a part of the external pipe connection part 510 may be in the form of a fire hose having flexibility, in a zigzag folded form (FIG. 5 (a)) in which the fire hose of the fire hydrant is stored, or in a form rolled in a reel shape ( 5 (b)). This form can make it easier to fasten to a fire engine or an outdoor fire hydrant.

The external pipe connection part 510 may be formed to be supplied with a predetermined water pressure or higher by being fastened with a fire engine or an outdoor fire hydrant. By this supply pressure, fire water can be smoothly supplied to the dedicated water tank 100 located in the upper part of the nuclear reactor building 10 .

6 is a view showing a method of operating a reactor vessel outer wall cooling system according to an embodiment of the present invention. When cooling of the outer wall of the nuclear reactor is not performed smoothly due to an accident such as loss of AC power, which is an external power source, the first valve 611 is opened to supply emergency coolant from the dedicated water tank 100 to the first pipe. Emergency coolant is supplied to the reactor cavity 220 through 610 . In order to fill the exclusive water tank 100 with emergency coolant, a fire hose connected to at least one selected from a fire engine or an outdoor fire hydrant and an external pipe connection part 510 are connected, and then the fire water from the fire engine or outdoor fire hydrant is supplied to the dedicated water tank 100 to fill In addition, when it is expected that a problem will occur due to a problem such as evaporation of the coolant in the spent fuel storage tank 710 , the third valve 631 is opened to supply the emergency coolant in the dedicated water tank 100 to the third It is supplied to the spent fuel storage tank 710 through the pipe 630 .

When it is necessary to supply additional coolant to the passive condensation cooling tank 800 to remove residual heat of the steam generator 400, the second valve 621 is opened to supply emergency coolant to the passive condensation cooling tank 800 through a second pipe 620. supplied through

7 illustrates a state in which emergency coolant is supplied to the reactor cavity 210 according to an embodiment of the present invention. When it is determined that cooling of the outer wall of the reactor vessel is necessary when an emergency situation such as loss of AC power occurs, the first valve 611 is opened and the emergency coolant of the dedicated water tank 100 is discharged through the first pipe 610 . do. The emergency coolant supplied through the first pipe 610 is supplied to and filled in the reactor cavity 210 , and at least a part of the reactor vessel 300 is submerged to cool the outer wall of the reactor vessel 300 as shown. be able to do

As described above, when the reactor vessel outer wall cooling system and the cooling method using the same of the present invention are applied, even when power supply is impossible in the long term, such as the Fukushima nuclear accident, the external water source can be continuously supplied through a fire engine and an external fire extinguisher. In addition to external wall cooling, it is possible to continuously and stably cool the spent fuel storage tank and remove residual heat from the steam generator. In addition, by applying the passive concept of supplying emergency cooling water in a gravity method, the related system can be simplified, reliability can be improved, and one large emergency cooling water tank can be used for multiple systems to reduce costs during construction and operation of nuclear power plants. can do.

The above-described embodiments are examples for explaining the present invention, and the present invention is not limited thereto. Those of ordinary skill in the art to which the present invention pertains will be able to practice the present invention with various modifications therefrom, so the technical protection scope of the present invention should be defined by the appended claims.

Claims (7)

In the reactor vessel outer wall cooling system,
a reactor building in which a reactor vessel and a steam generator are located;
a reactor cavity in which the reactor vessel is located and formed so that at least a part of the reactor vessel can be submerged by emergency coolant;
a dedicated water tank located higher than the upper end of the reactor vessel inside the reactor building and storing emergency coolant;
a first pipe formed to supply emergency cooling water of the dedicated water tank to the reactor cavity;
a water charging pipe extending outside the reactor building and formed to fill the exclusive water tank with emergency cooling water; and
an external pipe connection part formed in at least a part of the water filling pipe; Including, the emergency cooling water of the dedicated water tank can be supplied to the reactor cavity in a gravity method,
a passive condensation cooling tank positioned higher than the upper end of the steam generator outside the reactor building and for removing residual heat of the steam generator;
a second pipe formed to supply the emergency cooling water of the dedicated water tank to the passive condensation cooling tank in a gravity manner;
a spent fuel storage tank located outside the reactor building, lower than the dedicated water tank; and
The reactor vessel outer wall cooling system further comprising a third pipe formed to supply the emergency cooling water of the dedicated water tank to the spent fuel storage tank in a gravity manner. delete delete According to claim 1,
The reactor vessel outer wall cooling system further comprising a lower cavity formed under the reactor vessel, wherein the lower cavity further includes a sealing plate for preventing the coolant from leaking downward. According to claim 1,
The dedicated water tank is a reactor vessel outer wall cooling system located in a dome-shaped upper portion of the reactor building. According to claim 1,
The shape of the horizontal cross section of the dedicated water tank is one selected from a circle or a donut shape, and the bottom surface of the dedicated water tank has a high central portion and a lowered outer peripheral surface. a reactor building including a reactor vessel and a steam generator therein;
a reactor cavity in which the reactor vessel is located and formed so that at least a portion of the reactor vessel can be submerged by emergency coolant;
a dedicated water tank located in the dome-shaped part inside the reactor building and capable of storing emergency coolant;
a first pipe formed to supply emergency cooling water of the dedicated water tank to the reactor cavity;
a water charging pipe extending outside the reactor building and formed to fill the exclusive water tank with emergency cooling water;
an external pipe connection part formed in at least a part of the water filling pipe; and
At least a portion of the first pipe has a first valve opened and closed by a DC power supply; A reactor vessel outer wall cooling method using a reactor vessel outer wall cooling system comprising:
an emergency coolant supply step of supplying emergency coolant from the dedicated water tank to the reactor cavity by opening the first valve;
a fastening step of fastening a fire hose connected to at least one selected from a fire engine or an outdoor fire hydrant and the external pipe connection part; and
after the fastening step, a water filling step of supplying fire water from the fire engine or outdoor fire hydrant to the dedicated water tank;
The reactor vessel outer wall cooling system,
a passive condensation cooling tank located higher than the upper end of the steam generator outside the reactor building and for removing residual heat of the steam generator;
a second pipe formed to supply the emergency cooling water of the dedicated water tank to the passive condensation cooling tank in a gravity manner;
a spent fuel storage tank located outside the reactor building, lower than the dedicated water tank; and
and a third pipe formed to supply the emergency cooling water of the dedicated water tank to the spent fuel storage tank in a gravity manner.

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