JP7168519B2 - Reactor cooling systems and nuclear plants - Google Patents

Description

The present invention relates to reactor cooling systems and nuclear power plants.

A technology related to a passive cooling system for a nuclear reactor using natural convection is disclosed in Patent Document 1 below. In this document, "In the liquid metal cooled nuclear reactor 10, a cylindrical heat collector 34 is installed between the guard vessel 19 and the silo 31. is formed, and an ascending flow passage 36 is formed between the heat collector 34 and the guard vessel 19. The descending flow passage 35 is an air introduction pipe as an intake passage buried under the ground and provided with an air introduction port 38. 37. The upward flow passage 36 is also connected to an air discharge pipe 39 as an exhaust passage buried under the ground and provided with an air discharge port 40. These downward flow passage 35 and upward flow passage 36, the air introduction pipe 37 and the air discharge pipe 39 constitute the cooling passage 33."

JP 2013-76675 A

However, in the above-described passive cooling system for a nuclear reactor, if the cooling passage for natural circulation is blocked for some reason, the amount of air circulation required to remove the heat generated in the core cannot be secured. , reactor cooling becomes insufficient.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a nuclear reactor cooling system and a nuclear power plant capable of maintaining cooling performance even when a natural circulation passage in a passive cooling system using natural convection is blocked. .

In order to solve the above problems, for example, the configurations described in the claims are adopted.
The present application includes a plurality of means for solving the above problems. One example is a natural circulation passage for cooling medium for cooling the heat of the nuclear reactor, and an auxiliary pipe connected to the natural circulation passage. and a turbomachine provided in the auxiliary piping.

Advantageous Effects of Invention According to the present invention, it is possible to provide a reactor cooling system and a nuclear power plant capable of maintaining cooling performance even when a natural circulation passage in a passive cooling system using natural convection is blocked.
Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is a configuration diagram of a nuclear power plant according to an embodiment; FIG. 1 is a configuration diagram (part 1) of a reactor cooling system according to an embodiment; FIG. FIG. 2 is a configuration diagram (part 2) of the reactor cooling system according to the embodiment; FIG. 3 is a configuration diagram (part 3) of the reactor cooling system according to the embodiment; FIG. 4 is a configuration diagram of a reactor cooling system according to a modified example of the embodiment;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a reactor cooling system and a nuclear power plant according to the present invention will be described in detail with reference to the drawings. In addition, in the embodiment and modifications described below, the same constituent elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

≪Nuclear power plant≫
FIG. 1 is a configuration diagram of a nuclear power plant 1 according to an embodiment, and is a configuration diagram when the present invention is applied to a nuclear power plant 1 having a tank-type fast breeder reactor as an example. A nuclear power plant 1 shown in this figure includes a nuclear reactor 10 including a primary cooling system, a secondary cooling system 20 , and a feedwater/main steam system 30 . The nuclear power plant 1 also includes a reactor cooling system 40 that passively cools the reactor 10 . They are structured as follows.

<Reactor 10>
A nuclear reactor 10 includes a core 11 , an inner reactor vessel 12 containing the core 11 , and an outer reactor vessel 13 covering the inner reactor vessel 12 . An intermediate heat exchanger 14 and a primary circulation pump 15 are accommodated inside the inner furnace vessel 12 .

Among them, the core 11 is an assembly of nuclear fuel and contains fissile material.

The inner reactor vessel 12, which is a reactor vessel, accommodates the primary coolant L1 therein and further accommodates the core 11 in a state of being immersed in the primary coolant L1. As a result, the primary coolant L1 filling the inner reactor vessel 12 is heated by the core 11 . A liquid metal coolant such as sodium is used as the primary coolant L1.

The outer furnace vessel 13 is also called a guard vessel, and is arranged to cover the inner furnace vessel 12 with a gap provided therebetween. The space between the inner reactor vessel 12 and the outer reactor vessel 13 has a volume that does not expose the core 11 from the primary coolant L1 when the primary coolant L1 in the inner reactor vessel 12 leaks into the outer reactor vessel 13. is doing. In addition, this space is filled with an inert gas G, and when the primary coolant L1 in the inner reactor vessel 12 leaks to the outer reactor vessel 13, the liquid metal coolant such as sodium as the primary coolant L1 is oxidized. prevent

The intermediate heat exchanger 14 is internally provided with a pipe structure 14a extending from the secondary cooling system 20 described below. The pipe structure 14a is filled with a liquid metal coolant such as sodium as the secondary coolant L2, and is a portion through which the secondary coolant L2 circulates with the secondary cooling system 20. As shown in FIG. The secondary coolant L2 circulating within the tube structure 14a is heated by the primary coolant L1 within the inner reactor vessel 12 .

The primary circulation pump 15 is immersed in the primary coolant L1 within the inner furnace vessel 12 and circulates the primary coolant L1 within the inner reactor vessel 12 . Thus, in the tank-type fast breeder reactor, the inner reactor vessel 12 housing the intermediate heat exchanger 14 serves as a primary cooling system in which the primary coolant L1 is circulated. Therefore, the tank-type fast breeder reactor does not require primary cooling system piping, and the plant can be made compact.

<Secondary cooling system 20>
The secondary cooling system 20 has a secondary cooling pipe 21 , a steam generator 22 and a secondary circulation pump 23 .

Among these, the secondary cooling pipe 21 communicates between the steam generator 22 and the pipe structure 14a of the intermediate heat exchanger 14 at two locations, and connects the steam generator 22 and the pipe structure 14a of the intermediate heat exchanger 14. constitutes a circulation path for the secondary coolant L2. The secondary cooling pipe 21 is filled with a secondary coolant L2.

The steam generator 22 has a configuration in which secondary cooling pipes 21 are communicated at both ends, and is filled with a secondary coolant L2. Inside the steam generator 22, a thin tube 22a is arranged. This narrow tube 22a is connected to a water supply/main steam system 30, which will be described below, and is configured to supply water therein. Such a steam generator 22 generates steam by heating the water supplied in the fine tube 22a with the secondary coolant L2.

The secondary circulation pump 23 is provided in the secondary cooling pipe 21, and circulates the secondary coolant L2 between the steam generator 22 and the pipe structure 14a of the intermediate heat exchanger 14 via the secondary cooling pipe 21. Let

<Water supply/main steam system 30>
The feedwater/main steam system 30 has a main steam pipe 31 , a high pressure turbine 32 , a low pressure turbine 33 , a generator 34 , a condenser 35 , a feedwater/condensate pipe 36 , a feedwater pump 37 , and a feedwater heater 38 .

Among these, the main steam pipe 31 is connected to the narrow pipe 22 a of the steam generator 22 and guides the steam generated by the steam generator 22 to the high pressure turbine 32 . The high-pressure turbine 32 and the low-pressure turbine 33 are coaxially arranged and rotated by steam supplied from the steam generator 22 through the main steam pipe 31 . The generator 34 is coaxially connected to the high pressure turbine 32 and the low pressure turbine 33, and is operated by the rotation of the high pressure turbine 32 and the low pressure turbine 33 to generate power.

The condenser 35 is connected to the low pressure turbine 33 from which steam is directed. A cooling pipe 35a is arranged in the condenser 35 to condense the steam led from the low-pressure turbine 33 and return it to water.

The water supply/condensate system pipe 36 is arranged between the condenser 35 and the steam generator 22, and allows the condenser 35 and the narrow pipe 22a of the steam generator 22 to communicate with each other.

The water supply pump 37 is provided in the water supply/condensate system pipe 36 to increase the pressure of the water condensed in the condenser 35 to the narrow pipe 22 a of the steam generator 22 through the water supply/condensate system pipe 36 and supplies the water. The feed water heater 38 heats the water supplied to the thin tubes 22 a of the steam generator 22 .

<Reactor cooling device 40>
Next, the configuration of the reactor cooling system 40 that cools the nuclear reactor 10 will be described. FIG. 2 is a configuration diagram (part 1) of the reactor cooling system 40 according to the embodiment, showing a vertical cross section of the reactor 10 and its surroundings, and connection of each pipe constituting the reactor cooling system 40. It is a figure which shows a state. FIG. 3 is a configuration diagram (part 2) of the reactor cooling system according to the embodiment, showing a horizontal cross section of the reactor 10 and its surroundings, and connection of each pipe constituting the reactor cooling system 40. It is a figure which shows a state.

The reactor cooling system 40 shown in these figures has a natural circulation passage of the cooling medium for cooling the heat of the nuclear reactor 10, and in particular, the natural circulation of the cooling medium for removing the decay heat generated when the reactor is shut down. It has a circulation route. Such a reactor cooling system 40 has, for example, a Reactor Vessel Auxiliary Cooling System (RVACS) that takes in outside air as a cooling medium and naturally circulates it.

This reactor cooling system 40 comprises a concrete structure 41 housing the reactor 10, a tubular member 42 arranged in the concrete structure 41, a descending passage 43 and an ascending passage 44 separated by the tubular member 42. Prepare. The reactor cooling system 40 also includes an inlet pipe 45 connected to the descending passage 43 and an exhaust pipe 46 connected to the ascending passage 44, through which air (outside air) for cooling the heat of the reactor 10 is supplied. A natural circulation passage is configured. Furthermore, this reactor cooling system 40 includes a preliminary introduction pipe 50 and a preliminary discharge pipe 60 in addition to the natural circulation passage. Each of these components will be described below.

[Concrete structure 41]
The concrete structure 41 has an accommodation portion 41 a as a space for accommodating the reactor 10 . The concrete structure 41 accommodates the reactor 10 in the accommodation portion 41a while maintaining a gap from the reactor 10 at the side walls and the bottom surface of the accommodation portion 41a. Such a concrete structure 41 is provided by digging under the surface.

[Cylindrical member 42]
The cylindrical member 42 is arranged inside the housing portion 41a of the concrete structure 41 so as to surround the side circumference of the nuclear reactor 10, and is installed with a gap from the bottom surface portion of the housing portion 41a. Such tubular member 42 functions as a heat collector to which radiant heat from nuclear reactor 10 is transferred.

[Descent Passage 43]
The descending passage 43 is a space portion between the side wall of the housing portion 41 a and the tubular member 42 in the concrete structure 41 and is an outer space portion surrounding the tubular member 42 . The descending passage 43 serves as a gas distribution path through which the gas taken in from the introduction pipe 45 described below flows downward.

[Rise passage 44]
The ascending passage 44 is a space portion between the tubular member 42 and the nuclear reactor 10 and a space portion surrounding the nuclear reactor 10 . The ascending passage 44 is a portion where the gas inside the ascending passage 44 is warmed by the radiant heat from the nuclear reactor 10 and rises. The movement of the gas in the ascending passage 44 causes the inflow of gas from the descending passage 43 communicating with the ascending passage 44 at the lower end and the descending of the gas in the descending passage 43 .

[Introduction pipe 45]
The introduction pipe 45 is a pipe for introducing outside air provided in communication with the descending passage 43, and here, a configuration in which two introduction pipes 45 are communicated with the descending passage 43 is exemplified. Each introduction pipe 45 is connected to the descending passage 43 at a respective position at or near the upper end of the descending passage 43 . It is assumed that the connecting position of each introduction pipe 45 with the descending passage 43 is buried under the ground surface. In each introduction pipe 45, the end opposite to the connection position with the descending passage 43 is an open end that serves as an introduction port 45a for outside air, and is arranged on the ground.

A closing member 45b for closing the introduction pipe 45 is provided in the introduction port 45a. The closing member 45b is, for example, an electric cover, and opens the introduction port 45a of the introduction pipe 45 to open the introduction pipe 45 at all times when the power is not turned on. On the other hand, the closing member 45b closes the introduction port 45a of the introduction pipe 45 when the power is turned on. This prevents the loss of the cooling effect due to the inflow and outflow of gas into and out of the introduction pipe 45 when the power is turned on, as described in the following description of operation. Such a closing member 45b is powered on in conjunction with a turbomachine to be described later, and closes the introduction pipe 45 in conjunction with driving of the turbomachine.

The number of connections of the introduction pipe 45 to the descending passage 43 is not limited to two. , may be one or a plurality of three or more.

[Exhaust pipe 46]
The discharge pipe 46 is a gas discharge pipe provided in communication with the ascending passage 44, and here, a configuration in which two discharge pipes 46 are communicated with the ascending passage 44 is exemplified. Each discharge tube 46 is connected to the ascending passageway 44 at a respective location at or near the upper end of the ascending passageway 44 . It is assumed that the connecting position of each discharge pipe 46 with the ascending passage 44 is buried under the ground surface. Each discharge tube 46 is also an upwardly extending stack and has an inner diameter and height that effectively raises the gas warmed in the riser passage 44, thereby allowing the air to flow through the natural circulation path. achieve a natural circulation of In each discharge pipe 46, the end opposite to the connection position with the ascending passage 44 is an open end that serves as an external air discharge port 46a and is arranged on the ground.

A closing member 46b for closing the discharge pipe 46 is provided at the discharge port 46a. The closing member 46b is, for example, an electric cover, and opens the discharge port 46a of the discharge pipe 46 to open the discharge pipe 46 at all times when the power is not turned on. On the other hand, the closing member 46b closes the discharge port 46a of the discharge pipe 46 when the power is turned on. This prevents the loss of the cooling effect due to the inflow and outflow of gas into and out of the exhaust pipe 46 when the power is turned on. Such a closing member 46b is powered on in conjunction with a turbomachine to be described later, and closes the discharge pipe 46 in conjunction with driving of the turbomachine.

The number of discharge pipes 46 connected to the ascending passage 44 is not limited to two, as long as the amount of air circulation necessary for removing the decay heat generated when the reactor is shut down can be ensured. , may be one or a plurality of three or more.

[Preliminary introduction pipe 50]
The preliminary introduction pipe 50 is a preliminary pipe provided in communication with the descending passage 43 . The preliminary introduction pipe 50 is for introducing air into the descending passage 43 instead of the introduction pipe 45, which has a particularly strong suction force in the natural circulation passage and is likely to be clogged by foreign matter entering from the outside. Such a preliminary introduction pipe 50 is configured to be directly connected to the descending passage 43 . Since the descending passage 43 is provided so as to cover the periphery of the nuclear reactor 10 , it has a wide opening width and is difficult to block, and is suitable as a connecting portion for the preliminary introduction pipe 50 . The connecting portion of the pre-introduction pipe 50 to the descending passage 43 is, for example, the side wall of the housing portion 41a in the concrete structure 41, preferably above the inner furnace vessel 12, as shown.

The end portion of the preliminary introduction pipe 50 opposite to the connection position with the descending passage 43 serves as a preliminary introduction port 50a into which the gas is introduced. A first on-off valve 51, a turbo machine 52, a second on-off valve 53, and a check valve 54 are provided in order from the side of the preliminary introduction port 50a in the preliminary introduction pipe 50 as described above.

Among these, the first on-off valve 51 is provided in the vicinity of the preliminary introduction port 50a in the preliminary introduction pipe 50, normally closes the preliminary introduction pipe 50, and is interlocked with the turbo machine 52 described below to open the preliminary introduction pipe. 50 is opened. For example, an electric valve is used as the first on-off valve 51 . The first on-off valve 51 prevents foreign matter from entering the preliminary introduction pipe 50 by closing the preliminary introduction pipe 50 at all times when the power is not turned on. Further, by using an electric valve as the first on-off valve 51, it is possible to open the preliminary introduction pipe 50 in accordance with the driving timing of the turbomachine 52. can be efficiently implemented. Such a first on-off valve 51 is powered on together with the turbo machine 52 in conjunction with the closing member 45b provided on the introduction pipe 45 and the closing member 46b provided on the discharge pipe 46 .

The turbo machine 52 is driven in conjunction with the first on-off valve 51 , and pressure-feeds gas to the introduction pipe 45 side in a state in which the first on-off valve 51 opens the preliminary introduction pipe 50 . It is important that such a turbomachine 52 has a pumping capability sufficient to secure the amount of air circulation required to remove the decay heat of the core 11 generated when the reactor is shut down. Considering the amount of decay heat generated by the core 11, the physical properties of the air used as a cooling medium, the flow velocity in the flow path, and the pressure loss in the flow path, the turbomachine 52 has, for example, a centrifugal impeller. in which a compressor is used. Such a turbo machine 52 is powered on together with the first on-off valve 51 and in conjunction with the closing member 45b provided on the introduction pipe 45 and the closing member 46b provided on the discharge pipe 46 .

The second on-off valve 53 is provided in the preliminary introduction pipe 50 in the vicinity of the connection position with the introduction pipe 45 , always closes the preliminary introduction pipe 50 , and closes the preliminary introduction pipe 50 in conjunction with the driving of the turbomachine 52 . let it open. For example, an electric valve is used as such a second on-off valve. This second on-off valve 53 closes the preliminary introduction pipe 50 at all times when the power is not turned on, thereby preventing gas from flowing into the preliminary introduction pipe 50 from the descending passage 43, thereby reducing the loss of the cooling effect due to natural circulation. To prevent. By using an electric valve as the second on-off valve 53, it is possible to open the preliminary introduction pipe 50 in accordance with the timing of driving the turbomachine 52. Efficient implementation is possible. The second on-off valve 53 may be an air operated valve. In this case, the second on-off valve 53 is provided so as to open the preliminary introduction pipe 50 when the pressure on the preliminary introduction port 50a side is higher than the pressure on the descending passage 43 side by a predetermined value or more.

The check valve 54 is provided in the preliminary introduction pipe 50 in the vicinity of or at the connection position with the descending passage 43 to prevent gas from flowing into the preliminary introduction pipe 50 from the descending passage 43 . This prevents loss of cooling effect due to natural circulation.

It is preferable that the preliminary introduction pipe 50 provided with each member as described above is designed to have a smaller total opening area than the introduction pipe 45 . Also, the preliminary introduction pipe 50 needs to have a lower flow velocity in the upstream side of the turbomachinery 52 than the downstream side. Therefore, the preliminary introduction pipe 50 is designed to have a larger inner diameter on the upstream side than on the downstream side of the turbomachine 52 .

Moreover, the length of the preliminary introduction pipe 50 is preferably designed so that the turbomachinery 52 and the reactor 10 can be separated to a considerable extent, for example, for countermeasures against terrorism. For example, if the turbomachine 52 and the nuclear reactor 10 are separated by a linear distance of about 100 m, the length of the preliminary introduction pipe 50 is about 150 m in consideration of the layout.

Note that the number of pre-introduction pipes 50 as described above is not limited to one. A plurality of wires may be used as long as the amount of air circulation can be ensured. However, since the preliminary introduction pipe 50 is equipped with a power machine such as the turbomachine 52, it is preferable that the number of the preliminary introduction pipes 50 is small. Also, the preliminary introduction pipe 50 may be branched from the introduction pipe 45 .

[Preliminary discharge pipe 60]
The preliminary discharge pipe 60 is a preliminary pipe for gas discharge provided in communication with the ascending passage 44 and is directly connected to the ascending passage 44 here. Since the ascending passage 44 is provided so as to cover the periphery of the descending passage 43 , it has a wide opening width and is less likely to be blocked, and is suitable as a connecting portion for the preliminary discharge pipe 60 . The connecting portion of the preliminary discharge pipe 60 to the ascending passage 44 is, for example, a portion through which the cylindrical member 42 is passed, preferably above the inner furnace vessel 12, as shown. The end portion of the preliminary discharge pipe 60 opposite to the connection position with the discharge pipe 46 serves as a preliminary discharge port 60a through which the gas is discharged.

The preliminary discharge pipe 60 as described above is provided with a first air-operated valve 61 and a second air-operated valve 62 in order from the connection side with the ascending passage 44 . These first air-operated valve 61 and second air-operated valve 62 are arranged at both ends of the preliminary discharge pipe 60, and the pressure on the connection side with the rising passage 44 is higher than the pressure on the side of the preliminary discharge port 60a. It is an on-off valve that opens the preliminary discharge pipe 60 when it is higher than a predetermined level. These on-off valves open the preliminary discharge pipe 60 in the order of the first air-operated valve 61 and the second air-operated valve 62 .

As described above, by providing the first air-operated valve 61 on the connection side of the preliminary discharge pipe 60 with the rising passage 44, the rising passage Inflow of gas from 44 to pre-exhaust tube 60 is prevented. As a result, the rising effect of the gas within the discharge pipe 46 is not hindered, and the cooling effect due to natural convection is maintained. Furthermore, by providing the second air-operated valve 62 at the preliminary discharge port 60a of the preliminary discharge pipe 60, foreign matter can be prevented from entering the preliminary discharge pipe 60. FIG.

The preliminary discharge pipe 60 provided with each member as described above is designed to have a smaller total opening area than the discharge pipe 46. For example, it has a circular cross section and a diameter of about 1 m. It should be noted that the number of auxiliary discharge pipes 60 having the first air-operated valve 61 and the second air-operated valve 62 as described above is not limited to one. A plurality of pipes may be used as long as the amount of air circulation necessary for removing the decay heat generated when the reactor is shut down can be ensured. Also, the preliminary discharge pipe 60 may be branched from the discharge pipe 46 .

<Operation of Reactor Cooling System 40>
As the operation of the reactor cooling system 40 configured as described above, the operation at normal times will be described first, and then the operation when the reactor cooling system 40 is powered on will be described.

First, at all times, the reactor cooling system 40 is in a power-off state. Therefore, the closing member 45b provided on the introduction pipe 45 and the closing member 46b provided on the discharge pipe 46 are open, and the introduction pipe 45 and the discharge pipe 46 are open. On the other hand, the first on-off valve 51 and the second on-off valve 53 provided in the preliminary introduction pipe 50 are in a state of closing the preliminary introduction pipe 50 .

In the above state, for example, when decay heat is generated from the reactor 10 when the reactor is shut down, the gas in the ascending passage 44 is warmed by radiant heat. The warmed gas rises in the rising passage 44 and is discharged from the discharge port 46 a of the discharge pipe 46 connected to the rising passage 44 . Further, when the inside of the ascending passage 44 becomes negative pressure due to the rise of the gas, the gas is supplied to the ascending passage 44 from the descending passage 43 communicating with the ascending passage 44 at the lower end. Further, the descending passage 43 is supplied with outside air taken in from the introduction port 45 a of the introduction pipe 45 .

As described above, in the reactor cooling system 40 , the decay heat generated in the reactor 10 is passively cooled by the natural circulation of outside air taken in from the introduction port 45 a of the introduction pipe 45 .

In addition, since the gas that ascends through the ascending passage 44 and is supplied to the discharge pipe 46 is discharged from the discharge port 46a, the pressure inside the discharge pipe 46 is kept at a predetermined state. Therefore, the first air-operated valve 61 and the second air-operated valve 62 provided in the preliminary exhaust pipe 60 connected to the exhaust pipe 46 are not opened.

Next, the operation when the reactor cooling system 40 is powered on will be described. FIG. 4 is a configuration diagram (part 3) of the reactor cooling system 40 according to the embodiment, and is a diagram for explaining the operation when the reactor cooling system 40 is powered on. As shown in this figure, when the reactor cooling system 40 is powered on, the closing member 45b closes the introduction port 45a, and the closing member 46b closes the discharge port 46a. On the other hand, the first on-off valve 51 and the second on-off valve 53 provided in the preliminary introduction pipe 50 open the preliminary introduction pipe 50 . Furthermore, the turbo machine 52 provided in the preliminary introduction pipe 50 is activated, and the air (for example, outside air) taken in from the preliminary introduction port 50a of the preliminary introduction pipe 50 is pressure-fed toward the descending passage 43 side.

In such a state, when the gas in the rising passage 44 is warmed by the radiant heat from the reactor 10, the warmed gas rises in the rising passage 44 and is supplied to the discharge pipe 46 connected to the rising passage 44. be done. However, since the discharge pipe 46 is blocked by the blocking member 46b, the pressure inside the discharge pipe 46 and the ascending passage 44 increases. This opens the first air-operated valve 61 of the preliminary discharge pipe 60 connected to the ascending passage 44, followed by the opening of the second air-actuated valve 62, thereby opening the preliminary discharge pipe 60. As shown in FIG. Air in the ascending passage 44 is discharged from the preliminary discharge port 60 a of the preliminary discharge pipe 60 .

Further, the gas introduced from the preliminary introduction port 50a of the preliminary introduction pipe 50 is sent into the descending passage 43 by pressure feeding from the turbo machine 52 provided in the preliminary introduction pipe 50, and communicates with the descending passage 43 at the lower end of the descending passage 43. Gas is fed into the ascending passage 44 that is in the air. As a result, the decay heat generated in the reactor 10 is introduced from the preliminary introduction port 50a of the preliminary introduction pipe 50 and cooled by the gas (for example, air, which may be outside air) pumped by the turbomachine 52 .

<Effects of Embodiment>
According to the embodiment described above, the preliminary introduction pipe 50 having the turbomachine 52 is connected to the descending passage 43 forming the natural circulation path of air, which is the cooling medium, so that the gas is supplied to the descending passage 43. It is possible to pump. As a result, even if the natural circulation path is blocked for some reason, it is possible to continue supplying gas to the natural circulation path to the descending passage 43, thereby removing the decay heat of the core 11. It is possible to continue to maintain the cooling capacity necessary for

<<Modified example of the embodiment>>
FIG. 5 is a configuration diagram of a reactor cooling system according to a modification of the embodiment, showing a vertical cross-section of the reactor 10 and its surroundings, and a connection state of each pipe. It is a figure for demonstrating the operation|movement at the time of turning on a power supply to apparatus 40'. A modified nuclear reactor cooling system 40' shown in this figure has a configuration in which a moisture separator 55 is provided in the nuclear reactor cooling system 40 of the embodiment described with reference to FIGS. A moisture separator 55 is arranged between the first on-off valve 51 and the turbomachine 52 in the pre-introduction pipe 50 .

By adopting such a configuration, if for some reason the liquid metal coolant such as sodium as the primary coolant L1 leaks out of the reactor 10, the moisture is removed by the moisture separator 55 and the gas is may be supplied to the downpass 43 to cool the heat of the reactor 10 . Further, in this case, the introduction pipe 45 is closed by the closing member 46b in conjunction with the driving of the turbomachine 52 . Therefore, introduction of outside air containing moisture is blocked. Therefore, the heat of the nuclear reactor 10 can be cooled without bringing the liquid metal coolant such as sodium, which is the primary coolant L1, into contact with moisture.

It should be noted that the present invention is not limited to the above-described embodiments and modifications, and includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Alternatively, it may be of a boiling water type or a pressurized water type. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

DESCRIPTION OF SYMBOLS 1... Nuclear power plant 10... Nuclear reactor 11... Core 12... Inner reactor vessel 13... Outer reactor vessel 40... Reactor cooling device 42... Down passage (natural circulation passage)
44 ... ascending passage (natural circulation passage)
45 ... Introductory pipe (natural circulation passage)
45a... Introduction port (opening between introductions)
45b... Closing member 46... Exhaust pipe (natural circulation passage)
46a ... discharge port (opening of discharge pipe)
46b... Closing member 50... Preliminary introduction pipe (preliminary pipe)
50a... Pre-introduction port (open end of pre-introduction pipe)
51 First on-off valve 52 Turbo machine 53 Second on-off valve 54 Check valve 55 Moisture separator 60 Pre-discharge pipe 61 First air operated valve (on-off valve)
62... Second air-operated valve (on-off valve)
L1... primary coolant (liquid metal coolant)
G... inert gas

Claims (14)

a natural circulation passage for cooling medium for cooling the heat of the reactor;
a preliminary pipe connected to the natural circulation passage;
and a turbo machine provided in the spare pipe,
The natural circulation passage is
a cooling medium rise passage connected to the cooling medium outlet and arranged around the reactor;
a cooling medium descending passage connected to the cooling medium inlet, arranged to cover the outer side of the ascending passage, and communicating with the ascending passage at the lower end of the ascending passage;
The preliminary pipe is connected to the descending passage as a preliminary introduction pipe,
The turbomachine pumps coolant from the pre-introduction pipe toward the descending passage.
Reactor cooling system. 2. The reactor cooling system according to claim 1 , wherein an open end of said preliminary introduction pipe is provided with an on-off valve that closes said preliminary introduction pipe and opens said preliminary introduction pipe in conjunction with driving of said turbomachine. Device. The reactor cooling system according to claim 2 , wherein the on-off valve is an electric valve. An on-off valve that closes the preliminary introduction pipe and opens the preliminary introduction pipe in conjunction with driving of the turbomachine is provided on a side of the preliminary introduction pipe that is connected to the descending passage. The reactor cooling system according to . 2. A check valve according to claim 1 , wherein a connecting portion of said preliminary introduction pipe to said descending passage is provided with a check valve for preventing the cooling medium from flowing from said descending passage to said preliminary introduction pipe. Reactor cooling system. The natural circulation passage comprises a discharge pipe connected to the upper part of the ascending passage and an introduction pipe connected to the upper part of the descending passage,
2. The nuclear reactor cooling system according to claim 1 , wherein openings of said introduction pipe and said discharge pipe are provided with closing members that close said openings in conjunction with driving of said turbomachinery. 2. The reactor cooling system according to claim 1 , wherein a preliminary discharge pipe is connected to said ascending passage. On the side of the connecting portion of the preliminary discharge pipe with the rising passage, the preliminary discharging is performed by closing the preliminary discharging pipe so that the pressure on the rising passage side becomes higher than the pressure on the preliminary discharging pipe side by a predetermined amount or more. 8. The reactor cooling system according to claim 7 , further comprising an on-off valve for opening the pipe. An on-off valve is provided on the open end side of the preliminary discharge pipe to close the preliminary discharge pipe and open the preliminary discharge pipe when the pressure on the rising passage side becomes higher than the pressure on the open end side by a predetermined level or more. 8. The reactor cooling system of claim 7 , further comprising: 2. The reactor cooling system of claim 1, wherein the turbomachine is a compressor. The reactor cooling system according to claim 1, wherein the cooling medium is air. 2. The nuclear reactor cooling system according to claim 1 , wherein a moisture separator is provided on the open end side of the preliminary introduction pipe with respect to the turbomachine. a nuclear reactor;
a natural circulation passage for cooling medium for cooling the heat of the reactor;
a preliminary pipe connected to the natural circulation passage;
and a turbo machine provided in the spare pipe ,
The natural circulation passage is
a cooling medium rise passage connected to the cooling medium outlet and arranged around the reactor;
a cooling medium descending passage connected to the cooling medium inlet, arranged to cover the outer side of the ascending passage, and communicating with the ascending passage at the lower end of the ascending passage;
The preliminary pipe is connected to the descending passage as a preliminary introduction pipe,
The turbomachine pumps coolant from the pre-introduction pipe toward the descending passage.
nuclear plant. The reactor is
an inner reactor vessel containing a core and a liquid metal coolant;
an outer furnace vessel containing the inner furnace vessel;
14. The nuclear plant of claim 13 , including an inert gas filled between the inner reactor vessel and the outer reactor vessel.

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