JP7293096B2 - Cooling equipment and nuclear power plants - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to cooling technology for plant components.

During normal operation of a nuclear power plant, seawater is taken from the coast to cool components such as condensers. Also, when a nuclear power plant is safely shut down in an emergency, emergency cooling such as removal of decay heat of nuclear fuel is performed by seawater taken from the coast.

JP 2008-185572 A

By the way, many buildings and facilities need to be installed in a nuclear power plant, and the construction sites and areas of the buildings and facilities are restricted by geological and ground conditions. On the other hand, in recent years, in the event of a serious accident in which the core is damaged due to the loss of emergency core cooling equipment, the number of buildings that require facilities such as water sources to enable continued cooling for a certain period of time (for example, 7 days) after the accident has increased. there is

Therefore, it is necessary to secure a water source and install essential buildings to deal with the above-mentioned serious accidents, while also limiting the construction site and area. There is a problem that there is

The embodiments of the present invention have been made in consideration of such circumstances, and it is an object of the present invention to provide a cooling facility that increases the degree of freedom in the layout of a nuclear power plant and secures a water source in the event of a serious accident.

In the cooling equipment according to the embodiment, a first heat exchanger and a second heat exchanger arranged in a plant, and a first refrigerant that is supplied to the first heat exchanger in a transient manner from a water source that exists in the environment 1 cooling system, and a second cooling system that supplies the second refrigerant from a storage tank to the second heat exchanger while cooling it by a cooling tower in a circulation system, and the storage tank is integrated with the foundation of the plant. or wherein said first heat exchanger is utilized for service cooling of said plant components and said second heat exchanger is utilized for emergency cooling of said plant components; A cooling facility in the event of a serious accident that injects water into the tank is configured to use the storage tank as a water source .

An object of the present invention is to provide a cooling facility that increases the degree of freedom in the layout of a nuclear power plant and secures a water source in the event of a serious accident.

The piping circuit diagram of the cooling equipment which concerns on 1st Embodiment of this invention. (A) Vertical cross-sectional configuration diagram of a nuclear power plant to which the cooling equipment according to the first embodiment is applied, (B) Same horizontal cross-sectional configuration diagram. The piping circuit diagram of the cooling equipment which concerns on 2nd Embodiment of this invention. (A) Vertical cross-sectional configuration diagram of a nuclear power plant to which the cooling equipment according to the second embodiment is applied, (B) Same horizontal cross-sectional configuration diagram. The longitudinal cross-sectional view of the cooling equipment which concerns on 2nd Embodiment.

(First embodiment)
An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a piping circuit diagram of cooling equipment 10a (10) according to the first embodiment of the present invention. Thus, the cooling equipment 10a of the first embodiment includes the first heat exchanger 21 and the second heat exchanger 22 (21 ₁ , 22 ₂ , . . . 22 _n ) arranged in the plant 20, and the first heat exchanger A first cooling system 11 that supplies a first refrigerant 31 from a water source 30 existing in the environment to 21 in a one-time manner, and a second heat exchanger 22 from a storage tank 15 to a cooling tower 16 that circulates a second refrigerant 32. and a second cooling system 12 that supplies while cooling.

The first heat exchanger 21 is connected to a regular cooling system 25 for regular cooling of the components during normal operation of the plant 20 . The second heat exchanger 22 is connected to an emergency cooling system 26 for cooling the components of the plant 20 during normal operation in an emergency. As described above, the cooling equipment 10 according to the embodiment operates the first cooling system 11 during normal operation of the plant 20, and operates the emergency core cooling equipment in order to cope with the safe shutdown of the plant. 2 cooling system 12 is activated.

A plurality of second heat exchangers 22 (22 ₁ , 22 ₂ , . . . 22 _m ) are connected in parallel with each other, and by setting the on-off valve 27, those that perform heat exchange operation can be arbitrarily set.

The first cooling system 11 passes a first refrigerant 31 such as seawater or freshwater from a water source 30 such as the sea, river, or lake existing in the environment where the plant 20 is located to the first heat exchanger 21 in a transient manner. supply. The first refrigerant 31 pressure-fed from the water source 30 by the first pump 35 exchanges heat with the refrigerant in the normal cooling system 25 in the first heat exchanger 21, and then is returned to the water source 30 again.

The cooling tower 16 provided in the second cooling system 12 includes a water spraying unit 41 for spraying the second refrigerant 32 returned from the second heat exchanger 22 into the atmosphere, and an airflow 48 for applying the watered second refrigerant 32. It is an open type having a fan 42 that generates a . In the embodiment, the cooling tower 16 is sprayed with the second refrigerant 32 in the vertical direction from the water sprinkling unit 41, and the fan 42 blows the airflow 48 in the opposite direction to the spraying direction. The direction and the blowing direction of the airflow 48 are each arbitrary. Moreover, the cooling tower 16 is not limited to the open type shown in the embodiment, and any type can be adopted.

Employment of the open cooling tower 16 promotes the absorption of the latent heat of vaporization by the airflow 48, and the cooling of the second refrigerant 32 sprinkled with water is realized with high efficiency even on a small scale. Although two cooling towers 16 connected in parallel are disclosed in FIG. 1, the number of connected cooling towers 16 is arbitrary. Also, the number of operations of the cooling tower 16 can be changed according to the amount of heat exchanged in the second heat exchanger 22 . That is, when the amount of heat exchanged by the second heat exchanger 22 increases and the temperature of the passing second refrigerant 32 rises, the closed on-off valve 45 is opened to increase the number of operations of the cooling tower 16. can be done.

The storage tank 15 stores the second refrigerant 32 cooled by the cooling tower 16 . Since the open type cooling tower 16 utilizes latent heat of vaporization as a cooling principle, the amount of the second refrigerant 32 decreases with operation. Therefore, the continuous operation time of the second cooling system 12 depends on the holding capacity of the second refrigerant 32 in the storage tank 15 . Therefore, the capacity of the storage tank 15 is designed based on the amount of heat exchanged in the second heat exchanger 22 and the presumed continuous operation time of the second cooling system 12 . The second refrigerant 32 dissipated by evaporation is directly replenished to the storage tank 15 from the outside.

A pump 17 and an on-off valve 18 for pumping the second refrigerant 32 to the second heat exchanger 22 are connected to the storage tank 15 . These pumps 17 and on-off valves 18 are provided in numbers corresponding to the number of cooling towers 16 installed, and are set to operate and open according to the number of operating cooling towers 16 .

The second cooling system 12 is provided with a bypass passage 46 that allows the second refrigerant 32 to flow directly into the storage tank 15 without passing through the sprinkler 41 . The bypass passage 46 is provided with a control valve 47 for adjusting the flow rate of the second refrigerant 32 directly flowing into the storage tank 15 . By operating the control valve 47, the ratio between the flow rate of the second refrigerant 32 directly flowing into the storage tank 15 and the flow rate of the second refrigerant 32 flowing through the water sprinkling portion 41 can be arbitrarily adjusted. As a result, while setting the flow rate of the second refrigerant 32 circulating in the second cooling system 12 to a predetermined value, the amount of water sprayed by the water sprinkling unit 41 can be adjusted to adjust the temperature and the amount of vaporization and dissipation of the second refrigerant 32. can.

FIG. 2(A) is a longitudinal sectional configuration diagram of a plant 20 to which the cooling equipment 10a (10) according to the first embodiment is applied. FIG. 2B is a horizontal sectional view of the same. As described above, in the cooling facility 10a of the first embodiment, the storage tank 15 and the cooling tower 16 have a hierarchical structure. A machine room 19 in which a pump 17 and the like are installed is provided adjacent to the storage tank 15 in the cooling equipment 10a. In the first embodiment, the storage tank 15 and the cooling tower 16, which have a hierarchical structure, are installed on separate sites from the plant 20, but they can also be installed integrally with the plant 20. FIG.

The cooling equipment 10a shown in FIG. 2 shows an example in which six cooling towers 16 and storage tanks 15 paired therewith are connected and arranged. In the machine room 19, two pumps 17 corresponding to two cooling towers 16 are accommodated in one section. According to the cooling equipment 10a according to the first embodiment, it is possible to newly install the existing plant 20 on a vacant site. In addition, according to the required performance of the emergency cooling system 26 of the plant 20, it is possible to design by appropriately changing the number of connections of the storage tank 15 and the cooling tower 16, which have a hierarchical structure, and furthermore, it is easy to expand after construction. be.

(Modified example of the first embodiment)
A modification of the first embodiment will be described. In this modification, the storage tank 15 is configured not only as the water source for the second cooling system 12, but also as an emergency water source for injecting water into the reactor in the event of a serious accident or the like.

The second cooling system 12 circulates the second refrigerant 32 in order to remove decay heat from the plant 20 in an emergency. On the other hand, in the event of a serious accident in which the core is damaged due to the loss of emergency core cooling equipment, the water stored in the storage tank 15 is used as an emergency water source and is injected into the reactor using portable equipment or the like. Here, the inside of the reactor includes both the inside of the reactor pressure vessel and the inside of the containment vessel. In serious accident situations, the second cooling system 12 basically does not operate.

In recent years, it has been required to install a water source within the premises of the plant 20 as equipment for dealing with serious accidents. The storage tank 15 is a large-capacity water source that allows the second cooling system 12 to operate continuously for a certain period of time (for example, 30 days), and can also be used as an emergency water source in the event of a serious accident. According to this modification, it is not necessary to provide an emergency water source for coping with a serious accident separately from the water source of the second cooling system 12, so the equipment that needs to be installed can be reduced and the plant layout can be improved. It can increase the degree of freedom.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 3 to 5. FIG. FIG. 3 is a piping circuit diagram of the cooling equipment 10b (10) according to the second embodiment of the present invention. In FIG. 3, parts having configurations or functions common to those in FIG. 1 are denoted by the same reference numerals, and overlapping descriptions are omitted.

Thus, the cooling equipment 10b of the second embodiment includes the first heat exchanger 21 and the second heat exchanger 22 (22 ₁ , 22 ₂ , ... 22 _n ) arranged in the plant 20, and the first heat exchanger A first cooling system 11 that supplies a first refrigerant 31 from a water source 30 existing in the environment to 21 in a one-time manner, and a second heat exchanger 22 from a storage tank 15 to a cooling tower 16 that circulates a second refrigerant 32. and a second cooling system 12 that supplies while cooling.

The cooling tower 16 of the second embodiment includes a water sprinkling part 41 that sprinkles the second refrigerant 32 returned from the second heat exchanger 22 into the atmosphere, and collects the sprinkled second refrigerant 32 and sends it to the storage tank 15. A collection tank 37 is provided. The second refrigerant 32 may be sent from the collection tank 37 to the storage tank 15 by utilizing the height difference or by pumping with a pump (not shown).

FIG. 4(A) is a vertical cross-sectional configuration diagram of a nuclear power plant 20 to which the cooling equipment 10b according to the second embodiment is applied. FIG. 4(B) is a horizontal sectional configuration diagram of the same nuclear power plant. FIG. 5 is a vertical cross-sectional configuration diagram of a cooling facility 10b according to the second embodiment. 4 and 5, illustration of the first heat exchanger 21 (FIG. 3) and the first cooling system 11 is omitted.

As described above, in the cooling facility 10b according to the second embodiment, the storage tank 15 and the cooling tower 16 are installed on different sites, so that the cooling tower 16 can be laid out more freely. Furthermore, the airflow that cools the second refrigerant 32 can be easily taken in from around the fan 42, and the cooling effect continues even after the second refrigerant 32 lands in the recovery tank 37 until it is transferred to the storage tank 15. 2, the cooling efficiency of the refrigerant 32 is improved. It is also possible to integrate a plurality of cooling towers 16 depending on layout constraints.

Furthermore, the storage tank 15 of the second embodiment is constructed integrally with the foundation 38 of the plant 20 . As a result, the supporting substrate of the plant 20 is widened in the horizontal direction, which contributes to the improvement of earthquake resistance. Further, as shown in FIG. 5, a large capacity of the storage tank 15 is secured below the ground level G, so that the second refrigerant 32 can be easily accumulated. In addition, since the pump 17 and the second heat exchanger 22 can be integrated with the storage tank 15 and provided in a layered structure, it is possible to save space for installing the equipment. Although illustration is omitted, the cooling tower 16 can also be constructed above the storage tank 15 constructed integrally with the foundation 38 of the plant 20 .

According to the cooling facility 10 (10a, 10b) of at least one embodiment described above, it is possible to provide a cooling facility capable of increasing the degree of freedom in the layout of a nuclear power plant. For example, when the plant 20 is constructed in a place away from the environmental water source 30 such as the sea, river, lake, etc., the second cooling system 12 that supplies the second refrigerant 32 to the emergency cooling system 26 is a circulation cooling system. This eliminates the need to provide a canal from the coast of the environmental water source 30 to the nuclear power plant side as a cooling source.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 10 (10a, 10b)... Cooling equipment, 11... 1st cooling system, 12... 2nd cooling system, 15... Storage tank, 16... Cooling tower, 17... Pump, 18... On-off valve, 19... Machine room, 20... Nuclear power plant (plant) 21 First heat exchanger 22 Second heat exchanger 25 Regular cooling system 26 Emergency cooling system 27 On-off valve 30 Environmental water source (water source) 31 First refrigerant, 32...Second refrigerant, 35...Pump, 37...Collection tank, 38...Foundation, 41...Sprinkling part, 42...Fan, 45...On-off valve, 46...Bypass path, 47...Control valve, 48...Airflow .

Claims (6)

a first heat exchanger and a second heat exchanger arranged in the plant;
a first cooling system that once-through supplies a first refrigerant from an environmental water source to the first heat exchanger;
a second cooling system that supplies the second refrigerant from the storage tank to the second heat exchanger while cooling it in a circulating cooling tower ;
A cooling facility in which the storage tank is constructed integrally with the foundation of the plant . a first heat exchanger and a second heat exchanger arranged in the plant;
a first cooling system that once-through supplies a first refrigerant from an environmental water source to the first heat exchanger;
a second cooling system that supplies the second refrigerant from the storage tank to the second heat exchanger while cooling it in a circulating cooling tower ;
The first heat exchanger is used for regular cooling of the components of the plant,
The second heat exchanger is used for emergency cooling of the components of the plant,
A cooling facility configured to use the storage tank as a water source in case of a serious accident in which water is injected into the reactor of a nuclear power plant . In the cooling equipment according to claim 1 or claim 2 ,
The cooling tower is
a water sprinkling unit for sprinkling the second refrigerant returned from the second heat exchanger into the atmosphere;
and a recovery tank for recovering the sprinkled second refrigerant and delivering it to the storage tank. In the cooling equipment according to any one of claims 1 to 3 ,
The storage tank and the cooling tower are cooling facilities having a hierarchical structure. In the cooling equipment according to any one of claims 1 to 3 ,
The cooling facility in which the storage tank and the cooling tower are installed on separate sites. A nuclear power plant in which the cooling equipment according to any one of claims 1 to 5 is installed.

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