KR20180111334A - Preheating and cooling system for nuclear reactor and nuclear power plant having the same - Google Patents

Abstract

The present invention relates to a preheating and cooling system of a reactor, which comprises: a steam generator having a plurality of flow paths for heat exchange of fluids having different temperatures to transfer heat to a reactor coolant system or to receive the heat from the reactor coolant system; a preheating and cooling tank disposed at a position lower than that of the steam generator; a heating unit provided inside the preheating and cooling tank, and heating a coolant stored in the preheating and cooling tank during a preheating operation of the reactor coolant system before starting an output operation of a reactor to generate steam; a circulation flow path for connecting the steam generator and the preheating and cooling tank to circulate the steam to be supplied to the steam generator during the preheating operation or the coolant to be supplied to the steam generator during a cooling operation of the reactor coolant system; and a pressure drop facility for inducing a pressure of the coolant discharged from an outlet of an upper end of the steam generator at a preset pressure or more to allow the coolant supplied to an inlet of a lower end of the steam generator to flow to an outlet of an upper end of the steam generator in a single phase from a feedwater system during the cooling operation so as to transfer the heat.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear reactor preheating and cooling system,

The present invention relates to a reactor preheating and cooling system for preheating a reactor coolant system prior to start of operation of a reactor or cooling a reactor coolant system when residual heat of a reactor is removed, and a nuclear power plant having the same.

The integrated reactor is a reactor for installing main equipment such as a steam generator, a pressurizer, and a reactor coolant pump together with a reactor core in a reactor vessel, and is distinguished from a separate reactor (general commercial light water reactor) in which main equipment is installed outside a reactor vessel.

In the integrated reactor, there is no large pipe connecting the reactor with the main device, and the flow of the reactor coolant system is formed by the internal structures of the reactor vessel. The heat generated by the nuclear fission in the reactor core heats the reactor coolant and the heated reactor coolant is supplied to the steam generator by the circulating force of the reactor coolant pump and the heat of the reactor coolant is transferred to the secondary side of the steam generator, And then supplied to the reactor core again. The feed water supplied to the secondary side of the steam generator is phase-changed into steam by the heat transferred from the reactor coolant, and the steam produced by the steam generator is supplied to the turbine to produce electricity.

Passive in a nuclear power plant means that it is driven by the natural force built in the system such as gravity or gas pressure, and active means that it is driven by the power such as a pump operated by electricity. do.

In the pressurized light water reactor, water (light water) is used as the moderator. The moderator temperature coefficient indicates the amount of change in reactivity to the unit temperature change of moderator (reactor coolant), and the change in reactivity is related to the change in water density. The change in the density of water with respect to the unit temperature change is generally larger at higher temperatures and smaller at lower temperatures. In other words, when the density change of the water is large according to the unit temperature change, the temperature coefficient of the moderator generally has a larger negative value. Therefore, it is desirable that the temperature coefficient of the moderator core of the reactor core be maintained at a large negative value for the stable operation of the reactor. To this end, the preheating process for raising the temperature of the reactor coolant system before starting the output operation .

Commercial separable reactors have a relatively large flow path resistance of the reactor coolant system, and perform preheating operation of the reactor using a large-capacity reactor coolant pump to circulate the reactor coolant in the reactor coolant system.

However, since the integral reactor has a relatively small flow path resistance of the reactor coolant system and uses a small-capacity reactor coolant pump, a preheating facility for preheating operation is additionally required because the preheating operation time becomes too long.

In the prior art (Patent Registration No. 10-1072803), a "preheating device for an integrated reactor and a preheating method using the same" in which the preheating operation is carried out by utilizing a recycle tank, a heater, and a compressor (or a pump) is proposed. The preheating device shown in the prior art documents requires an active compressor or pump to preheat the reactor coolant system.

However, in the conventional integrated reactor preheating apparatus, the following disadvantages arise when an active compressor or a pump is applied.

First, when a compressor (or a blower and a fan or the like is also applicable) is installed in the preheating fluid supply pipe, the saturated steam generated by the heater inside the starter recycle tank can be supplied to the steam generator using the compressor . At this time, the pressure at the rear end of the compressor rises and some steam is condensed at the rear end of the compressor. As a result, the compressor may be damaged and the circulating flow rate of the compressor may be limited.

Second, when a pump is installed in a condensing line, the pump generally has to secure enough net positive suction head (NPSHa) for suction from the steam generator to operate safely without cavitation. If the effective suction head can not be sufficiently secured, air bubbles may be generated in the vicinity of the impeller of the pump, and the impeller of the pump may be damaged by the impact due to the rupture of the bubbles. Accordingly, when the pump is installed in the preheating system, the pump should be installed at a position lower than the steam generator, and sufficiently cooled condensed water should be supplied to the pump from the steam generator.

Third, when the fluid (steam and condensed water) is circulated using the active device (compressor, pump, etc.) as described above, if the circulating flow rate is insufficient, the heater inside the start recirculation tank may be exposed to the water surface, . Therefore, the circulating flow rate must be properly controlled to prevent heater damage. In addition, when active equipment is applied, additional facilities such as a tank for controlling the circulation flow rate, a water level meter for the secondary side of the steam generator, a temperature and flow meter, etc. are required and the water level and flow rate must be controlled appropriately. There is a drawback.

On the other hand, in the case of a nuclear power plant using a flow-through type steam generator, in a steam generator having a flow channel, two phases are generated, and the density is rapidly increased as steam is formed. The density wave propagates back and forth in the flow direction and the flow becomes unstable. This is because the pressure drop phase differences between the single phase region and the ideal region are fed back to each other and the flow anxiety is amplified.

In particular, in the case of a steam generator having a plurality of channel channels connected to a common header, this phenomenon is caused by a parallel channel oscillation between the channel channels, and the function as a steam generator is lost.

In addition, this phenomenon becomes particularly important in applications where the operation range of the steam generator is low or the operation range requiring a low output operation mode for other purposes is wide. In order to alleviate such a flow phenomenon, generally, a shell and tube type steam generator having a wide operating range is installed, and in particular, when a tube is used as a secondary flow path, an orifice having a large flow resistance is installed in the inlet region of the tube. In addition, since the flow anxiety occurs in the low output operation mode, it is operated so as to supply the feed water flow rate equal to or higher than a certain flow rate in order to avoid the low flow operation region.

On the other hand, unlike ordinary boilers, residual heat is generated even after the reactor is stopped. Therefore, the residual heat must be removed before the reactor can be maintained in a safe state.

However, when the reactor is suddenly cooled, the structural load is increased due to the difference in the heat shrinkage rate of the structure, so the cooling rate is limited in the reactor. The cooling rate is also used as a design criterion for the charge and discharge flow rates of the chemical and volumetric control systems (CVCS) that assist the reactor, and an excessively large cooling rate causes the system size to increase.

Therefore, there is a need for a cooling facility to suitably meet the design requirements of the cooling rate.

Korean Patent No. 10-1072803 (Jun. 10, 2011)

Accordingly, it is an object of the present invention to provide a nuclear power plant capable of preheating a nuclear reactor using a natural circulation principle, without using various measuring equipments for the operation of active devices such as pumps and the operation of active devices.

Another object of the present invention is to provide a nuclear power plant capable of solving the occurrence of flow anxiety even when the flow anomaly is fundamentally eliminated by using single-phase heat transfer to reduce the water supply flow rate.

It is still another object of the present invention to provide a nuclear power plant capable of stable cooling operation while freely controlling the cooling rate.

In order to accomplish the object of the present invention, a reactor preheating and cooling system according to the present invention includes a plurality of flow paths for heat exchange of fluids having different temperatures to transfer heat to the reactor coolant system or heat from the reactor coolant system A steam generator delivered; A preheating and cooling tank disposed at a lower position than the steam generator; A heating unit provided in the preheating and cooling tank and generating steam by heating the cooling water stored in the preheating and cooling tanks during the preheating operation of the reactor coolant system before start of output operation of the reactor; A circulation flow path connecting the steam generator and the preheating and cooling tank to circulate the steam to be supplied to the steam generator during the preheating operation or the cooling water to be supplied to the steam generator during the cooling operation of the reactor coolant system; And the cooling water supplied from the water supply system to the lower end inlet of the steam generator during the cooling operation flows in a single phase from the upper end of the steam generator to the upper outlet of the steam generator so that the pressure of the cooling water discharged from the upper outlet of the steam generator Lt; RTI ID = 0.0 > a < / RTI >

According to one embodiment of the present invention, the heating unit may be a heater using electricity, or a boiler that burns fuel to provide a heat source.

According to an embodiment of the present invention, the heating unit may be disposed lower than the steam generator, and may be arranged to be submerged in the lower end of the preheating and cooling tank.

According to an embodiment of the present invention, in the preheating operation, the steam is delivered to the steam generator, and the condensed water formed after the steam is condensed through the heat transfer in the steam generator is returned to the preheating and cooling tank by natural circulation .

According to an embodiment of the present invention, a booster pump for boosting the pressure of the cooling water to a saturated pressure or higher may be further included.

According to an embodiment of the present invention, the booster pump further boosts the supply water supplied from the water supply pump during the cooling operation and directly supplies the water supply to the steam generator.

According to an embodiment of the present invention, the cooling water discharged from the steam generator may be recovered to the preheating and cooling tank.

According to an embodiment of the present invention, the circulation passage includes: a main steam pipe extending from an upper end outlet of the steam generator toward the turbine system; An upper pipe branched from the main combustion chamber and extending to an upper portion of the preheating and cooling tank; A water supply pipe extending from the water supply system to a lower end inlet of the steam generator; And a lower pipe branched from the water supply pipe and extending to a lower portion of the preheating and cooling tank.

According to an embodiment of the present invention, the circulation flow path includes a preheating pipe connecting the upper pipe and the upper end of the preheating and cooling tank to supply the steam to the steam generator during the preheating operation; And a cooling pipe connecting the upper pipe and another part of the upper end of the preheating and cooling tank to transfer the cooling water discharged from the steam generator to the preheating and cooling tank during the cooling operation.

According to an embodiment of the present invention, the preheating and cooling tank is a flash tank integrated tank, and the pressure drop facility is connected to the cooling pipe, and is installed upstream of the flash tank integrated tank, An orifice that maintains the pressure of the cooling water flowing along the cooling pipe to the front end of the cooling pipe at a predetermined pressure or higher; And a cooling water supply unit which is provided inside the flash tank integrated tank and in which a part of the cooling water introduced into the flash tank integrated tank from the orifice is vaporized by the expansion pressure and the remaining cooling water is cooled by the vaporization heat, And a water separator for separating the water.

According to an embodiment of the present invention, the pressure drop facility may include an orifice which is disposed upstream of the preheating and cooling tank along the cooling pipe and maintains the pressure of the cooling water at a predetermined pressure or higher; And a flash tank disposed between the orifice and the preheating and cooling tank for vaporizing a part of the cooling water introduced into the orifice and for cooling the remaining cooling water by the vaporizing heat to separate the cooling water from the steam .

According to an embodiment of the present invention, the lower end of the preheating and cooling tank may be disposed lower than the steam generator, and the upper end extending upward from the lower end may be disposed higher than the steam generator.

According to an embodiment of the present invention, the cooling water stored in the preheating and cooling tank may be formed so that the water level during the preheating operation is lower than the water level of the condensed water formed in the steam generator.

According to an embodiment of the present invention, the cooling water stored in the preheating and cooling tank may be formed so that the water level in the cooling operation is higher than the upper end of the steam generator.

According to an embodiment of the present invention, the cooling water may be spontaneously circulated in a single phase between the preheating and cooling tank and the steam generator in the early stage of the cooling operation.

According to an embodiment of the present invention, the booster pump further boosts the water supplied from the water pump at the second half of the cooling operation, forcibly supplies the water to the upper portion of the preheating and cooling tank, Cooling water forcibly supplied is fed back from the lower end of the preheating and cooling tank to the upper side of the preheating and cooling tank via the steam generator by spontaneous circulation in a single phase and then discharged from the upper side of the preheating and cooling tank .

According to an embodiment of the present invention, the cooling water injecting portion of the preheating and cooling tank, to which the cooling water is forcedly supplied, is higher than the upper end of the steam generator, and the inlet of the preheating and cooling tank Can be arranged lower than the part.

According to an embodiment of the present invention, the forced cooling water may be a low temperature water having a temperature lower than a preset temperature.

According to one example related to the present invention, the pressure drop facility is arranged on the downstream side of the preheating and cooling tank, and vaporizes part of the cooling water discharged from the preheating and cooling tank by the expansion pressure, A flash tank for cooling the steam by the vaporizing heat to separate the steam and the cooling water; A connection pipe connecting the preheating and cooling tank and the flash tank; And a discharge flow rate control valve installed in the connection pipe.

According to an embodiment of the present invention, the pressure of the cooling water flowing along the circulation flow path and the connection pipe can be maintained at a predetermined pressure or more by the flow path resistance portion formed at the inlet of the discharge flow rate control valve or the flash tank have.

According to an embodiment of the present invention, there is further provided a jet pump disposed at a lower portion of the preheating and cooling tank, wherein the jet pump is provided at a lower portion of the preheating and cooling tank, A nozzle for spraying cooling water forcibly supplied from the pump; And a fluid suction part for sucking the cooling water around the nozzle by one side of the nozzle toward the nozzle and a throat on the other side for jetting pressure of the cooling water injected from the nozzle, and the cooling water sucked through the fluid suction part And injected into the lower end of the steam generator.

According to an embodiment of the present invention, in the cooling operation, the cooling water may be boosted by a water supply pump and supplied to the steam generator.

According to an embodiment of the present invention, the single-phase heat transfer of the cooling water can be used during normal operation at the initial stage of starting the reactor core.

A nuclear power plant according to the present invention comprises: a reactor vessel; A plurality of steam generators provided inside the reactor vessel and having a plurality of flow paths to transfer heat to the reactor coolant system or heat from the reactor coolant system; A turbine system for generating energy using steam generated in the steam generator; A condenser provided at a rear end of the turbine system for condensing the steam; A reactor preheat and cooling system for preheating and cooling the reactor coolant system, the reactor preheat and cooling system comprising: a preheat and cooling tank disposed at a lower position than the steam generator; A heating unit provided in the preheating and cooling tank and generating steam by heating the cooling water stored in the preheating and cooling tank in the preheating operation of the reactor coolant system before starting the reactor core; A circulation flow path connecting the steam generator and the preheating and cooling tank to circulate the steam to be supplied to the steam generator during the preheating operation or the cooling water to be supplied to the steam generator during the cooling operation of the reactor coolant system; And the cooling water supplied from the water supply system to the lower end inlet of the steam generator during the cooling operation flows in a single phase from the upper end of the steam generator to the upper outlet of the steam generator so that the pressure of the cooling water discharged from the upper outlet of the steam generator Lt; RTI ID = 0.0 > a < / RTI >

According to the present invention configured as described above, the following effects can be obtained.

First, the preheating operation can be stably implemented by the natural circulation principle before the start of the reactor output operation. In the preheating operation, steam is formed in the heating section provided in the preheating and cooling tank, and is supplied to the steam generator through the preheating pipe and the upper pipe. In the steam generator, heat is transferred to the reactor coolant system by condensation heat transfer, And the condensed water formed in the steam generator is supplied to the preheating and cooling tank through the lower pipe by the difference in the water level between the preheating and cooling tank and the steam generator so that the preheating operation can be continuously performed by the natural circulation flow , Operation of the system related to preheating operation becomes simple.

Second, the cooling operation can be stably realized by using the single phase flow of the steam generator during the cooling operation of the nuclear power plant. Phase cooling water which is pressurized by the booster pump over the saturation pressure during the cooling operation is supplied to the steam generator and the discharge of the steam generator is performed by using the resistance of the flow path resistance structure and the water separating equipment (orifice, flow control valve, And the single-phase heat transfer is generated in the steam generator during the cooling operation, so that the cooling rate can be easily controlled by eliminating the flow anxiety due to the abnormal flow, The system becomes simple and the operation becomes easy.

Third, the preheating and cooling system of the nuclear power plant can be simplified by sharing one preheating and cooling tank in the preheating operation and the cooling operation.

Fourth, since the pump or the compressor used in the conventional preheating system is not required, the economical efficiency is improved by simplifying the preheating system.

Fifth, precise measurement is not required since preheating operation can be performed by using natural circulation without using a preheating system pump and a compressor.

Sixth, since the steam generator is installed inside the reactor vessel, it is easy to secure the water level of the primary system up to the steam generator in the preheating and cooling operation, and the resistance of the primary side of the steam generator is small in the preheating and cooling operation conditions, The flow rate on the side of the vehicle can be secured. Since the heat supply or cooling source utilizes the secondary side flow path of the steam generator, since the size of the piping is not limited as in the case of the primary system, securing the circulation flow rate of the secondary side flow path of the steam generator is smooth. Therefore, Preheating and cooling are easy. Integral reactors limit the size of the piping of the primary system connected to the reactor coolant system, making it difficult to ensure a circulating flow rate for preheating and cooling operations.

Seventh, since single-phase flow is used in cooling operation, flow anxiety does not occur in a flow-through type steam generator, so that the cooling rate can be freely adjusted, which greatly increases the operational convenience.

FIG. 1A is a conceptual diagram for explaining a reactor preheating and cooling system in a normal operation arrangement according to a first embodiment of the present invention. FIG.
FIG. 1B is a conceptual view showing a flow path of the fluid during preheating operation of the reactor coolant system in FIG. 1A.
FIG. 1C is a conceptual view showing a movement path of a fluid during a cooling operation of the reactor coolant system in FIG. 1A.
2A is a conceptual diagram showing a reactor preheating and cooling system during normal operation of a nuclear power plant according to a second embodiment of the present invention.
FIG. 2B is a conceptual diagram showing the operation of the system and the movement path of the fluid during the preheating operation in FIG. 2A.
FIG. 2C is a conceptual diagram showing the operation of the system at the beginning of the cooling operation and the movement path of the fluid.
FIG. 2D is a conceptual diagram showing the operation of the system and the movement path of the fluid in the second half of the cooling operation.
FIG. 3A is a conceptual diagram showing a reactor preheating and cooling system during normal operation of a nuclear power plant according to a third embodiment of the present invention. FIG.
FIG. 3B is a conceptual view showing the operation of the system and the flow path of the fluid during the preheating operation in FIG. 3A.
FIG. 3C is a conceptual diagram showing the operation of the system at the beginning of the cooling operation and the movement path of the fluid.
FIG. 3D is a conceptual diagram showing the operation of the system and the movement path of the fluid in the second half of the cooling operation.
4 is a conceptual diagram showing a reactor preheating and cooling system during normal operation of a nuclear power plant according to a fourth embodiment of the present invention.
5A and 5B are conceptual diagrams showing a reactor preheating and cooling system during normal operation of a nuclear power plant according to a fifth embodiment of the present invention. FIG. 5A is an example in which a connection position of a booster pump is changed, 5C is another example in which the connection position of the booster pump is changed.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a reactor preheating and cooling apparatus and a nuclear power plant having the same according to the present invention will be described in detail with reference to the drawings. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be obscured.

FIG. 1A is a conceptual view for explaining a reactor preheating and cooling system 100 in a normal operation arrangement according to a first embodiment of the present invention, FIG. 1B is a schematic view of a reactor coolant system in FIG. And FIG. 1C is a conceptual diagram showing a flow path of the fluid during the cooling operation of the reactor coolant system in FIG. 1A.

The nuclear power plant can be comprised of a reactor coolant system, a steam generator 10, a turbine system 13, a condenser 19, a deaerator 22, a reactor preheat and cooling system 100.

The reactor coolant system is a system that cools the heat generated from the core during normal operation by the coolant. The reactor coolant system also means a reactor in an integral reactor. The reactor coolant system includes a steam generator (10) that cools the reactor coolant through heat exchange between the reactor coolant and the secondary system feed water using a fluid circulation and vaporizes the feed water by steam by the heat of the reactor coolant, a reactor coolant A pump, a pressurizer for pressurizing the reactor coolant, and the like. In the case of an integral reactor, a steam generator (10), a pump impeller of a reactor coolant pump, and a pressurizer are installed inside the reactor vessel.

The steam generator (10) has a plurality of flow passages for exchanging heat between two fluids having different temperatures. The steam generator 10 may be disposed at the boundary between the primary system and the secondary system to induce heat exchange between the primary system fluid and the secondary system fluid. The steam generator 10 may be a SHELL & TUBE TYPE. The steam generator 10 may also be of a different type, such as a plate type. The following description is based on a shell-and-tube steam generator.

For example, when the reactor coolant of the reactor coolant system is supplied to the primary side flow path (shell 11) of the steam generator 10 and the feed water of the feed water system is supplied to the secondary side flow path (tube 12) The reactor coolant is cooled by heat exchange with the feed water, and the feed water can be vaporized into steam by the heat transferred from the reactor coolant.

The turbine system 13 includes a turbine and a generator, rotates the turbine using steam supplied from the steam generator 10, and converts the mechanical energy of the turbine into electric energy by the generator. The steam generator (10) and the turbine are connected to the main steam turbine (14) so that steam can be supplied from the steam generator (10) to the turbine. The main engine 14 is provided with the main engine isolation valve 15 so that the main engine 14 can be opened and closed in accordance with the operation signal of the driver or the control signal of the control system. A turbine control valve 16 is provided at the front end of the turbine to control the amount of steam supplied to the turbine.

The condenser 19 is disposed at the rear end of the turbine, and can condense the vapor discharged from the outlet of the turbine.

The turbine bypass flow path 17 is branched and extends to the condenser 19 in the main engine 14 connecting between the main engine isolation valve 15 and the turbine control valve 16 so that the steam bypasses the turbine, ). ≪ / RTI > A bypass isolation valve 18 is provided in the turbine bypass flow passage 17 to open and close the turbine bypass flow passage 17.

The deaerator 22 serves to separate the non-condensable gas from the condensate in the condenser 19 and the condensed water from which the non-condensable gas has been removed in the deaerator 22 can be supplied to the steam generator 10 . The deaerator 22 can be connected to the water supply system.

The condenser 19 and the deaerator 22 are interconnected by the condenser-deaerator connection pipe 23 and the plurality of pumps 20 and the plurality of condensers are installed in the condenser-deaerator connection pipe 23 . The plural pumps 20 can transfer the condensed water from the condenser 19 to the deaerator 22. A heat exchanger of a plurality of heaters is capable of heating condensate to be conveyed to the deaerator 22 by heat transfer from the steam to condensate through heat exchange between the steam passing through the heat exchanger and the condenser.

A water supply pipe 24 is connected between the deaerator 22 and the steam generator 10 so that the water supply can be supplied to the steam generator 10 along the water supply pipe 24.

A water supply pump 25, a water supply heat exchanger 26, a flow meter 27, and a water feed flow rate control valve 30 may be installed on the downstream side of the deaerator 22 along a water supply pipe 24. The water supply pump 25 can supply the water discharged from the deaerator 22 to the steam generator 10 or the like. The water heater 26 is a kind of heat exchanger that can heat water by heat exchange from steam to water through heat exchange between steam and water passing through the water heater 26. The flow meter 27 can be used to control the flow rate of the feed water by measuring the flow rate of the feed water to be supplied to the steam generator 10. [ The water supply flow rate control valve 30 is configured to control the flow rate of the water supply. In addition, the water bypass passage 28 may be provided at the rear end of the deaerator 22. [ One side of the water bypass passage 28 communicates with the water supply pipe 24 connecting the water heater 26 and the water supply pump 25 and the other side of the water supply bypass passage 28 is connected to the rear end of the deaerator 22 So that a part of the water supplied by the water pump 25 can be returned to the deaerator 22 without being supplied to the steam generator 10. A bypass flow control valve 29 is provided in the water bypass flow path 28 to control the bypass flow rate of the returned water.

The preheating and cooling system 100 includes a preheating and cooling tank 110, a heating unit 111, a circulating flow path 120, a booster pump 130 and a pressure drop facility 140. However, the booster pump 25 may be omitted if the discharge pressure of the feed pump 25 is sufficiently high according to the characteristics of the nuclear power plant.

The preheating and cooling tanks 110 are used to preheat the reactor coolant system prior to reactor output operation or to cool the reactor coolant system during normal operation and cooling operation of the nuclear reactor.

The preheating and cooling tank (110) stores cooling water therein. The preheating and cooling tank 110 is capable of preheating the reactor coolant system by vaporizing the stored water into steam and then supplying the steam to the steam generator 10 to transfer heat to the reactor coolant system through the steam generator 10.

The preheating and cooling tank (110) has a heating part (111) inside. The heating unit 111 is configured to heat the water stored in the preheating and cooling tank 110. The heating unit 111 may be a heater using electric energy or a boiler for generating a heat source by burning fuel. Gas, oil, and coal may be used as the fuel for the boiler. The heating unit 111 is operated during the preheating operation to heat the stored water to a temperature equal to or higher than the boiling point, and to supply the steam to the steam generator 10 in the preheating operation.

The circulation flow passage 120 is connected between the steam generator 10 and the preheating and cooling tank 110 so that the steam can be supplied to the steam generator 10 from the preheating and cooling tank 110.

The preheating and cooling tank 110 is disposed at a position lower than the steam generator 10 so that the steam or the condensate formed in the steam generator 10 can be circulated by natural circulation.

The circulating flow path 120 includes an upper pipe 121 connected to the main pipe 14, a preheating pipe 121a extending from the upper pipe 121 to the upper portion of the preheating and cooling tank 110, And a cooling pipe 121b extending to one side of the upper portion of the preheating and cooling tank 110. [ The preheating pipe 121a and the cooling pipe 121b are provided with isolation valves 1211 and 1212 respectively to open and close the preheating pipe 121a and the cooling pipe 121b. The upper end of the steam generator 10 is connected to the upper end of the preheating and cooling tank 110 by the main steam pipe 14, the upper pipe 121 and the preheating pipe 121a, The upper pipe 121 and the main steam pipe 14 and moves to the upper end of the steam generator 10. A steam header 11a is formed at an upper end of the steam generator 10 so that the steam introduced from the upper end of the steam generator 10 is supplied to the steam header 11a and then a plurality of tubes 12 tube. The steam distributed to the plurality of tubes 12 is surrounded by a shell 11 which is a primary side flow path in the preheating operation and heats the reactor coolant through heat exchange with the low temperature reactor coolant introduced into the shell 11, The coolant system can be preheated.

The vapor, which has transferred heat to the reactor coolant, condenses and descends along the tube (12). A water supply header 11b is formed at the lower end of the steam generator 10 so that the condensed water descending along the tube 12 is collected into the water supply header 11b. The condensed water may form a water level in the steam generator 10 to a certain height.

The circulation flow path 120 branches from the water supply pipe 24 and extends to the lower end of the preheating and cooling tank 110 to connect the lower pipe 122 for connecting the lower end of the steam generator 10 and the lower end of the cooling tank 110 And the like. The condensed water discharged from the water supply header 11b of the steam generator 10 may be circulated to the lower end of the preheating and cooling tank 110 along the lower pipe 122 to be recovered.

Here, referring to FIG. 1B, the preheating and cooling tank 110 is disposed lower than the steam generator 10. The water level of the condensed water formed in the steam generator 10 may form a head H1 having a predetermined height upward from the lower pipe 122. The water level of the condensed water can rise to a height of about half of the length of the steam generator 10. However, the water level of the steam generator 10 is determined by the system heat transfer amount due to the correlation between the supply heat of the heating unit 111 and the heat transmitted through the steam generator 10 and the cooling water of the reactor coolant system, Is not limited to a specific height because it is formed by the balance of the system flow rate due to the water head difference of the tank 110 and the system flow path resistance. During the preheating operation, the stored water level of the preheating and cooling tank (110) is formed to be lower than the condensed water level of the steam generator (10). That is, the water level of the preheating and cooling tank 110 may be spaced upward from the lower pipe 122 by a predetermined height to form the head of H2 (H1 > H2).

The condensed water can be stably circulated from the steam generator 10 to the preheating and cooling tank 110 without any active equipment such as a pump due to natural circulation forces such as a difference in head between the steam generator 10 and the preheating and cooling tank 110 during the preheating operation . Further, the pressure of the system is naturally controlled by the balance between the heat transfer amount and the flow rate.

A flow control valve 123 is provided in the lower pipe 122 so that the flow rate of the condensate flowing along the lower pipe 122 can be adjusted by the flow control valve 123.

On the other hand, during the preheating operation in which the reactor coolant system is preheated before starting the reactor core, the secondary side is hot and the primary side is in a low temperature state. However, during the normal operation of the reactor or the cooling operation for removing residual heat after the reactor is stopped, The primary side is high temperature and the secondary side is low temperature. That is, the high-temperature coolant of the reactor coolant system passing through the primary side flow path (shell 11) of the steam generator 10 during the normal operation or the cooling operation of the reactor is supplied to the secondary side flow path (tube 12) ), The coolant itself is cooled and the cooling water on the secondary side receives heat from the reactor coolant.

In the flow-through type steam generator (particularly the shell and tube type steam generator 10) having a plurality of flow channel channels, the cooling water supplied to the steam generator 10 absorbs heat from the reactor coolant while the cooling water and steam are mixed To two phases.

As described above, when the flow anxiety is amplified during the abnormal flow forming process, there may be a problem that the function as the steam generator 10 is lost. This flow anxiety phenomenon can be further amplified when the amount of cooling water (water supply) supplied to the steam generator 10 decreases as in the cooling operation. Therefore, in order to solve this problem, the reactor coolant system is cooled in the steam generator 10 ) Flows in a single phase and receives heat transfer.

The steam generator 10 includes a booster pump 130 for boosting the pressure of the cooling water to be supplied to the steam generator 10 so that the cooling water supplied to the lower end of the steam generator 10 flows into the upper end of the steam generator 10 , A pressure drop facility 140 is provided which pressurizes the cooling water to a predetermined pressure or more and induces a pressurized state.

The booster pump 130 boosts the supply water supplied from the water supply pump 25 to supply it directly to the steam generator 10 (forcibly circulates), boosts the supply water supplied from the water supply pump 25 again, To the upper portion of the steam generator 110, and then the natural circulation flow can be induced and supplied to the steam generator 10 (mixing flow in which the forced water supply and the natural circulation flow are mixed).

1C shows a state in which the water supplied from the water feed pump 25 is boosted by the booster pump 130 and then supplied directly to the steam generator 10.

The booster pump 130 is disposed between the feed pump 25 and the steam generator 10 and when the pressure of the feed water supplied from the feed pump 25 does not rise above the preset pressure, . Therefore, the booster pump 130 can be selectively applied when the pressure can not be sufficiently raised by the feed pump 25. 1C, the booster pump 130 is added. However, when the discharge pressure of the feed pump 25 is sufficiently high, the booster pump 130 may not be separately provided.

When the pressure of the water feed pump 25 is not sufficiently high, the booster pump 130 is installed in the booster pump connection pipe 131 and one side of the booster pump connection pipe 131 is branched from the front end of the water isolation valve 31 And the other side of the booster pump connection pipe 131 is configured to join to the downstream side of the first check valve 32. The first check valve 32 is connected to the water supply isolation valve 31 and the first check valve 32, A flow control valve 123 and a second check valve 133 may be provided on the downstream side of the booster pump 130 along the booster pump connection pipe 131. The flow control valve 123 is capable of controlling the flow rate of the water supply that is boosted by the booster pump 130. The second check valve 133 is configured to prevent the boosted feed water from flowing back to the booster pump 130.

A water supply isolation valve 31 and a first check valve 32 may be installed on the downstream side of the water supply flow control valve 30 along the water supply pipe 24. [ The water supply isolation valve 31 is controlled on / off in accordance with a control signal and can be used to control the supply of water, which has passed through the feed water flow control valve 30, to the booster pump 130. For example, when the water supply isolation valve 31 is turned off, a water supply pump 31 is connected to the water supply isolation valve 31 and the first check valve 32, The water supply can be directly supplied to the steam generator 10 by the water feed pump 25 when the water supply isolation valve 31 is turned on . The first check valve 32 is provided on the downstream side of the water supply isolation valve 31 so as to prevent the water to be supplied to the steam generator 10 from flowing back toward the water supply isolation valve 31.

The booster pump 130 is not operated in the preheating operation and the flow control valve 123 of the booster pump connection pipe 131 and the water isolation valve 31 are turned off.

The pressure drop facility 140 includes an orifice 141. In the present invention, the pressure drop facility 140 is referred to as an orifice 141. However, the pressure drop facility 140 is not limited to the orifice 141, but refers to various structures and devices provided for the purpose of pressure drop. The orifice 141 may be disposed along the cooling pipe 121b at the rear end of the cooling pipe 121b or at the front end of the preheating and cooling tank 110. [ The flow path of the orifice 141 is formed to be very narrow and the flow path resistance is large. The steam header 11a formed at the upper end of the steam generator 10 communicates with the orifice 141 through the main steam pipe 14, the upper pipe 121 and the cooling pipe 121b, The high temperature cooling water rising along the secondary side flow path of the reactor coolant can be pressurized by the flow path resistance of the orifice 141 to maintain the high pressure state and receive the heat of the reactor coolant system in a single phase (liquid) flow. At this time, the high-pressure state of the cooling water can be maintained until the front end of the orifice 141.

During the cooling operation, the water level of the preheating and cooling tank 110 may be higher than that of the preheating operation, and the upper space of the preheating and cooling tank 110 is connected to the low pressure condenser 19, ) And the orifice 141, as shown in Fig.

The pressure drop facility 140 may include a water separator 142 or a flash tank. The water separator 142 may be provided in an upper space in the preheating and cooling tank 110. The water separator 142 is connected to the rear end of the orifice 141 so that a part of the cooling water flowing into the upper space in the preheating and cooling tank 110 from the orifice 141 is expanded and vaporized to be vaporized , The remaining cooling water is cooled by the heat of vaporization and separated into cooling water and steam.

The flash tank has a volume area that is significantly wider than the orifice 141. A part of the cooling water flowing into the flash tank from the orifice 141 expands and expands to increase the pressure and vaporize into steam. Cooling water and steam can be separated from the inside of the flash tank 243 by being cooled by the heat of vaporization.

When the water separator 142 is installed inside the preheating and cooling tank 110, it is not necessary to provide a separate flash tank 243 at the front end or the rear end of the preheating and cooling tank 110 and the water separator 142, The preheating and cooling tank 110 in which the water separator 142 is incorporated can be regarded as a flash tank integrated tank in which the flash tank 243 is integrated. 1A to 1C show that the preheating and cooling tank 110 is a flash tank integrated type.

A steam discharge pipe 144 is connected between the preheating and cooling tank 110 and the condenser 19 so that the steam separated from the inside of the preheating and cooling tank 110 flows to the condenser 19 along the steam discharge pipe 144, . As the isolation valve 145 is provided on the steam discharge pipe 144 and the isolation valve 145 is controlled to be on / off controlled by the control signal, the isolation valve 145 is opened during the cooling operation, 110 to the condenser 19.

A water discharge pipe 146 is connected between the preheating and cooling tank 110 and the deaerator 22 so that the steam separated from the inside of the preheating and cooling tank 110 is discharged through the water discharge pipe 146 22). The isolation valve 147 is provided in the water discharge pipe 146 and the isolation valve 147 is controlled on and off by the control signal so that the isolation valve 147 is opened during the cooling operation so that the cooling water is supplied to the preheating and cooling tank 110 to the deaerator 22.

The operation method of the present invention will be described with reference to Figs. 1A to 1C.

Referring to FIG. 1A, in normal operation of a nuclear power plant, water is supplied from a water supply system to a steam generator 10, heat is transferred from a reactor coolant system to a steam generator 10, and water is converted into steam. Is supplied to the turbine through the engine (14). The turbine converts the fluid energy of the steam into mechanical rotational energy, and the generator connected to the rotational axis of the turbine generates electrical energy using mechanical rotational energy.

The steam passing through the turbine is condensed in the condenser (19) and supplied to the steam generator (10) through the water supply system again. During normal operation of the nuclear power plant, the preheating and cooling system 100 is isolated by isolation valves 1211, 1212 and the like. That is, the isolation valves 1211 and 1212 and the flow control valve 123 of the preheating and cooling system 100 are turned off.

Before starting the preheating operation, the reactor coolant system is at a low temperature (room temperature) state. The upper piping isolation valves 1211 and 1212 and the lower piping isolation valve 123 of the preheating facility are opened and the heating unit 111 (Heater) is driven. Referring to FIG. 1B, the water supply system, the turbine system 13 and the like for normal output operation in the preheating operation are isolated, and the preheating facility becomes a closed circuit. The heating unit 111 starts to form steam while raising the temperature of the water to be stored in the preheating and cooling tank 110. The formed steam is supplied to the steam generator 10 through the upper pipe 121 and condensed to preheat the reactor coolant system. The condensed water formed in the steam generator 10 raises the water level of the secondary water of the steam generator 10 and the water level difference between the secondary side of the steam generator 10 and the preheating and cooling tank 110, Is returned to the preheating and cooling tank (110) through the lower pipe (122). Since the heat is supplied from the heating unit 111 during the preheating operation, the circulation process is continuously maintained as long as the heat is supplied. When the temperature of the reactor coolant system reaches the predetermined preheating temperature, the power supply to the heating unit 111 is turned off to terminate the preheating. Here, the preheating flow rate control valve can be selectively applied for stable operation of the preheating system or preheating and maintenance of the water level of the cooling tank 110 and the like.

Before starting the cooling operation, the reactor coolant system is in a high temperature state where the reactor normal operating temperature is high. The reactor is shut down for cooling operation. The cooling pipe isolation valve 1212 and the lower pipe isolation valve 123 are opened and the steam generator 10 is opened via the water supply pump 25, the water heater 26 and the booster pump 130, So that the steam generator 10 is filled with the single-phase fluid. Water is discharged from the steam generator 10 and water and steam are separated and discharged into the preheating and cooling tank 110 through the water separator 142.

The steam is discharged to the condenser 19 through the steam discharge pipe 144, and the water level of the preheating and cooling tank 110 rises as the water is introduced. When the water level of the preheating and cooling tank 110 rises to a predetermined height, water is discharged to the deaerator 22 through the water discharge pipe 146. And the water supply flow rate is controlled according to the required cooling rate. Since the single-phase (liquid) fluid circulates to the secondary side of the steam generator 11, the flow anxiety is fundamentally excluded, and thus the cooling rate can be controlled by freely controlling the feed water flow rate.

When the temperature of the reactor coolant system reaches the preset cooling temperature, the cooling operation through the preheating and cooling system is terminated and a subsequent cooling system such as the stationary cooling system is connected.

Therefore, the following effects can be obtained by applying the reactor preheating and cooling system 100 of the present invention.

First, the preheating operation can be stably implemented by the natural circulation principle before the start of the reactor output operation. In the preheating operation, steam is formed in the heating unit 111 installed inside the preheating and cooling tank 110 and supplied to the steam generator 10 through the preheating pipe 121a and the upper pipe 121, The condensed water formed in the steam generator 10 is condensed by the water level difference between the preheating and cooling tank 110 and the steam generator 10, The preheating operation is performed by the natural circulation flow continuously since the preheating and cooling tank 110 is supplied through the pipe 122 again.

Second, the cooling operation can be stably realized by using the single-phase (liquid) flow of the steam generator 10 during the cooling operation of the nuclear power plant. Phase cooling water that is pressurized to a saturated pressure or higher by the booster pump 130 through the booster pump 130 is supplied to the steam generator 10 and the flow path resistance structure and the water separator (the orifice 141, the flow control valve 123, Phase heat transfer is generated in the steam generator 10 during the cooling operation by inducing the discharge portion of the steam generator 10 to be maintained at a pressure higher than the saturation pressure by using the resistance of the flash tank 243, The cooling rate can be easily controlled, and the system related to the cooling operation becomes simple and the operation becomes simple.

Third, the preheating and cooling system 100 of the nuclear power plant can be simplified by sharing one preheating and cooling tank 110 during the preheating operation and the cooling operation.

Fourth, since the pump or the compressor used in the conventional preheating system is not required, the economical efficiency is improved by simplifying the preheating system.

Fifth, precise measurement is not required since preheating operation can be performed by using natural circulation without using a preheating system pump and a compressor.

Sixth, in the integrated reactor, since the steam generator 10 is installed inside the reactor vessel, it is easy to secure the level of the primary system up to the steam generator 10 in the preheating and cooling operation, and the steam generator 10 The secondary side flow path of the steam generator 10 is used and the piping size is not limited as in the primary system so that the secondary side of the steam generator 10 It is easy to preheat and cool the reactor coolant system using the steam generator 10 because the circulation flow rate of the flow path is smoothly secured. Integral reactors limit the size of the piping of the primary system connected to the reactor coolant system, making it difficult to ensure a circulating flow rate for preheating and cooling operations.

Seventh, since single-phase flow is used in the cooling operation, flow anxiety does not occur in the flow-through type steam generator (10), so the cooling rate can be freely adjusted and the operation convenience is greatly increased.

FIG. 2A is a conceptual diagram showing a nuclear reactor preheating and cooling system 200 during normal operation of a nuclear power plant according to a second embodiment of the present invention, FIG. 2B is a conceptual view showing the operation of the system and the movement path of the fluid in the preheating operation FIG. 2C is a conceptual view showing the operation of the system at the early stage of the cooling operation and the movement path of the fluid, and FIG. 2D is a conceptual diagram showing the operation of the system and the movement path of the fluid at the latter stage of the cooling operation.

The upper end of the preheating and cooling tank 210 according to the present embodiment is disposed lower than the lower end of the steam generator 10 and the upper end of the upper end of the upper end of the steam generator 10 ). The preheating and cooling tanks 210 are divided into two tanks and the upper and lower tanks are connected by piping according to the characteristics of the nuclear power plant. It is also possible. Therefore, in the present invention, the preheating and cooling tank 210 is not limited to a single tank.

The preheating and cooling tank 210 may have different water levels during the preheating operation and the cooling operation. During the preheating operation, the storage water level of the preheating and cooling tank 210 may be formed to be lower than the condensate water level of the steam generator 10 so that the fluid is circulated by spontaneous circulation such as water head difference. The stored water level of the preheating and cooling tank 210 during the cooling operation may be higher than the upper pipe 221.

The circulation flow path 220 may include an upper pipeline 221 and a lower pipeline 122. The upper pipe 221 is branched from the main steam pipe 14 and extends to the upper portion of the preheating and cooling tank 210 and is capable of communicably connecting the upper end of the steam generator 10 and the upper side of the preheating and cooling tank 210 have. The lower pipe 122 branches from the water supply pipe 24 and extends to a lower portion of the preheating and cooling tank 210 and can connect the lower end of the steam generator 10 and the lower portion of the preheating and cooling tank 210 in a communicative manner.

The lower pipe 122 may further include a bypass channel 224 for connecting the preheating and cooling tank 210 and the deaerator 22. One side of the bypass conduit 224 is connected to the upstream side of the lower conduit 122 and the other side of the bypass conduit 224 is connected to the deaerator 22 and a part of the cooling water discharged from the preheating and cooling tank 110 Can bypass the deaerator 22 along the bypass channel 224. A bypass flow control valve 225 is provided in the bypass flow path 224 to control the bypass flow rate of the cooling water.

The booster pump 130 boosts the supply water supplied from the water supply pump 25 and forcibly injects the water to the upper portion of the preheating and cooling tank 110. The lower end of the booster pump connection pipe 231 branches off from the water supply pipe 24 connecting the feed water flow control valve 30 and the water isolation valve 31 and the upper end of the booster pump connection pipe 231 is connected to the preheating and cooling tank 110). The other side of the booster pump connection pipe 231 can be disposed at a position higher than the upper end of the steam generator 10 and lower than the upper pipe 121.

The booster pump 230 is installed in the booster pump connection pipe 231, but the mounting position of the booster pump 230 is not limited unless the pump sucking head NPSH. A flow control valve 223 is provided in the booster pump connection pipe 231 to control the flow rate of the cooling water to be supplied to the preheating and cooling tank 210. The second check valve 233 is provided on the upstream side of the booster pump 230 at the lower end of the booster pump connection pipe 231 to restrict the supply of water to the booster pump 230 during normal operation of the nuclear power plant.

A bypass passage 234 bypassing the booster pump 230 may be formed in the booster pump connection pipe 231. [ One side of the bypass passage 234 is connected to the downstream side of the booster pump 230 and the other side of the bypass passage 234 is connected to the upstream side of the second check valve 233, A part of the cooling water can be lowered to the lower end of the check valve along the bypass passage 234. A bypass flow valve 235 is provided in the bypass flow passage 234 to control the bypass flow rate in accordance with the control signal.

The pressure drop facility 240 may include a discharge flow control valve 2433 and a flash tank 243 installed on the downstream side of the preheating and cooling tank 110.

A flash tank connecting pipe 2432 may be provided between the preheating and cooling tank 210 and the flash tank 243. [ The flash tank connecting pipe 2432 is connected to the other side of the upper part of the preheating and cooling tank 210 so that the hot cooling water can be discharged from the preheating and cooling tank 210 to the flash tank 243.

The discharge flow rate control valve 2433 can control the discharge flow rate to be supplied to the flash tank 243 by the control signal.

Further, when the discharge flow rate control valve 2433 restricts the flow rate, the cooling water discharged from the upper outlet of the steam generator 10 and moving along the upper pipe 221 can be pressurized and maintained at a high pressure.

The flash tank 243 expands a part of the high-pressure cooling water passing through the discharge flow rate control valve 2433 and depressurizes it to vaporize the steam. The remaining cooling water is cooled by the heat of vaporization, and is separated into steam and water.

The flash tank 243 may have a flow path resistance portion 2431 formed at the inlet thereof and the flow path resistance portion 2431 may pressurize the cooling water discharged from the upper end outlet of the steam generator 10 to maintain the high pressure state. When the flash tank 243 functions as a flow path resistance structure such as the orifice 141, the discharge flow rate control valve 2433 can perform only the flow rate control function.

A steam discharge pipe 144 is provided between the flash tank 243 and the condenser 19 so that the steam separated from the flash tank 243 can be transferred to the condenser 19 along the steam discharge pipe 244. [ A steam discharge control valve 245 is provided in the steam discharge pipe 244 to control the discharge flow rate of the steam.

A water discharge pipe 246 is provided between the flash tank 243 and the deaerator 22 so that the water separated from the flash tank 243 can be transferred to the deaerator 22 along the water discharge pipe 246 have. A water discharge control valve 247 is provided in the water discharge pipe 246 to control the discharge flow rate of water.

Referring to FIG. 2B, power is supplied to the heating unit 111 during the preheating operation, and the preheating and storage water of the storage tank are heated by the operation of the heating unit 111. When the heated storage water rises to the boiling point or more, And the cooling tank 210 are supplied to the steam generator 10 along the upper pipe 221.

The steam is transferred from the steam generator 10 to the reactor coolant to preheat the reactor coolant system and the steam itself is condensed to change the condensed water and is circulated through the lower pipe 122 by the natural circulation, 110).

In the drawing, the circulation direction of the fluid during the preheating operation is counterclockwise.

In the cooling operation, the power of the heating unit 111 is turned off, and the stored water in the preheating and cooling tank 110 is in a low temperature state. The heat of the reactor coolant system is transferred to the steam generator 10, The cooling water flowing along the secondary side flow path (tube 12) of the heat exchanger 10 becomes a high temperature state.

The low temperature water of the preheating and cooling tank 110 is supplied to the steam generator 10 to cool the reactor coolant system through heat exchange in the steam generator 10.

2C, in the early stage of the cooling operation, the isolation valve 2211 of the upper pipe 221 and the flow control valve 123 of the lower pipe 122 are opened so that the water stored in the preheating and cooling tank 210 becomes a density The upper pipe 221 and the lower pipe 122 which are the circulation flow channels 220 are introduced into a single phase and circulated to the preheating and cooling tank 210 again via the steam generator 10 by gravity. In the drawing, the circulation direction of the cooling water during the cooling operation is clockwise.

In the early stage of the cooling operation, fluid circulation is performed between the steam generator 10 and the preheating and cooling tank 210, and the remaining turbine system 13, the condenser 19, the deaerator 22, the feed pump 25, The fluid circulation to the pump 130 is blocked by the valve. Since the storage amount of the cooling water in the preheating and cooling tank 210 is limited, the operation is repeated until the temperature of the cooling water in the preheating and cooling tank 210 rises to the predetermined temperature You will end it.

2d, the fluid circulation between the steam generator 10 and the preheating and cooling tank 210 is extended to the condenser 19 and the deaerator 22 in the latter half of the cooling operation.

In addition, the single-phase flow of the cooling water is composed of a mixed flow in which natural circulation such as density difference and gravity, and forced circulation in the pump are mixed.

The supply water supplied from the water supply pump 25 is boosted by the booster pump 230 and is supplied to the upper part of the preheating and cooling tank 210 (the position higher than the upper end of the steam generator 10 and lower than the upper pipe 221) And is injected into the preheating and cooling tank 210. The water (cooling water) injected into the upper part of the preheating and cooling tank 210 is low temperature water and descends to the lower end of the preheating and cooling tank 210 by the gravity and density difference. The lowered cooling water is supplied to the water supply header 11b at the lower end of the steam generator 10 along the lower pipe 122 and then distributed to the plurality of tubes 12 and rises along the inside of the tube 12. [ At this time, the reactor coolant inside the shell 11 configured to enclose the plurality of tubes 12 undergoes heat exchange with the cooling water to cool the reactor coolant, and the cooling water is heated by the reactor coolant to become high temperature cooling water. The high temperature cooling water is pressurized by the flash tank 243 (including the flow path resistance portion 2431) provided on the downstream side of the preheating and cooling tank 110 and maintained at a high pressure state to reach the upper end of the steam generator 10, (Liquid).

The high temperature cooling water collected in the steam header 11a of the steam generator 10 flows into the upper side of the preheating and cooling tank 210 along the upper pipe 221 and a part of the high temperature cooling water is introduced into the preheating and cooling tank 210 and is supplied to the flash tank 243 along the flash tank connecting pipe 2432. [ A part of the cooling water introduced into the flash tank 243 expands, the pressure is reduced and the steam is vaporized, and the remaining cooling water is cooled by the heat of vaporization, so that the steam and the cooling water are separated from each other.

The steam separated in the flash tank 243 is supplied to the condenser 19, condensed in the condenser 19, and then supplied to the deaerator 22. The cooling water separated from the flash tank 243 is directly supplied to the deaerator 22. [

The cooling water supplied to the deaerator 22 is supplied to the water supply pump 25 after the non-condensable gas is removed by the deaerator 22 and is boosted by the water supply pump 25 and the booster pump 130, And to the top of the cooling tank (110).

According to the present embodiment, the steam generator 10 and the circulation flow passage 220 can be filled in a single phase by gravity at the beginning of the cooling operation, and the flow of the circulation flow passage 220 during the initial and latter- Is formed by the natural circulation. In addition, it is possible to operate without elaborating the water supply to match the preset cooling rate. 2D, the preheating and cooling tank 210 serves as an intermediate medium (buffer), so that the flash tank 243 It is somewhat easier to control the cooling rate by controlling the flow rate of the exhaust gas. However, the preheating and cooling tank 210 must be long enough to fill the circulating flow path 220 in a single phase at the beginning of the cooling operation and utilize natural circulation. In order to discharge heat, a flash tank (243) must be separately installed and a high pressure must be designed to the front end of the flash tank (243). It may also be necessary to preheat the coolant in the tank prior to cooling to mitigate low temperature thermal shock.

FIG. 3A is a conceptual diagram showing a nuclear reactor preheating and cooling system 300 during normal operation of a nuclear power plant according to a third embodiment of the present invention, FIG. 3B is a conceptual view showing the operation of the system and the movement path of fluid FIG. 3C is a conceptual view showing the operation of the system in the early stage of the cooling operation and the movement path of the fluid, and FIG. 3D is a conceptual diagram showing the operation of the system and the movement path of the fluid in the latter stage of the cooling operation.

The present embodiment differs from the embodiment of FIG. 2 in that a mixed flow is formed using the principle of the jet pump 336, and a detailed description of other components is omitted in the description of the embodiment of FIG. . Hereinafter, the mixed flow using the principle of the jet pump 336 will be described.

A jet pump 336 is provided inside the preheating and cooling tank 110.

The jet pump 336 may be configured to include a jetting fluid receiving portion 337 and a nozzle 339.

The injection fluid receiving portion 337 is disposed to be spaced away from the bottom surface of the preheating and cooling tank 210 in one direction. The injection fluid accommodating portion connecting pipe 338 extending in one direction from the bottom surface of the preheating and cooling tank 210 is formed and one end of the injecting fluid accommodating portion connecting pipe 338 is connected to be communicated with the lower pipe 122, The other end of the injection fluid connecting pipe 338 is connected to be communicated with the injection fluid receiving portion 337.

One side of the jetting fluid receiving portion 337 is opened toward the nozzle 339 and a neck portion 337a is provided on the other side so that the flow area decreases from the one side to the neck portion 337a.

A booster pump connection pipe 331 is connected between the nozzle 339 and the booster pump 130 so that the cooling water sent out from the booster pump 130 can be supplied to the nozzle 339. The flow control valve 123 is provided in the booster pump connection pipe 331 so that the flow rate of the water supplied along the booster pump connection pipe 331 can be adjusted.

The nozzle 339 is configured to increase the speed of the cooling water because the area of the outlet is small. The nozzle 339 and the jetting fluid receiving portion 337 may be disposed below the preheating and cooling tank 210.

According to this configuration, the high-pressure cooling water that has been boosted by the booster pump 230 flows along the booster pump connection pipe 331 and is injected into the injection fluid accommodation portion 337 through the nozzle 339.

The cooling water jetted from the nozzle 339 passes through the neck portion 337a of the jetting fluid receiving portion 337 at a high speed. The pressure is lowered around the nozzle 339 and the jetting fluid receiving portion 337 due to the rapid jetting speed of the cooling water so that the fluid around the jetting fluid receiving portion 337 flows together with the jetting fluid receiving portion 337 Can be inhaled.

According to the present embodiment, the steam generator 10 and the circulation flow path 120 can be filled with liquid in the initial stage of the cooling operation, and the flow of the circulation flow path 120 during the cooling operation becomes natural due to the density difference. Circulation and the jet flow of the jet pump 336. When flow is formed using only natural circulation, sufficient head (height, density) difference must be ensured to maintain adequate cooling rate. However, when it is difficult to secure a sufficient head (height, density) difference according to the characteristics of the nuclear power plant, it is possible to form an appropriate cooling rate by securing the circulating flow by using the mixed flow of the jet pump 336. However, in order to utilize the natural circulation, the preheating and cooling tank 210 having a long length must be installed, and the flash tank 243 must be installed separately for energy release. And to be designed at a high pressure to the front end of the flash tank (243). It is also possible to preheat the cooling water in the preheating and cooling tank 210 or adjust the temperature of the water supply (water supply) before the cooling operation to mitigate the low temperature thermal shock.

4 is a conceptual diagram showing a nuclear reactor preheating and cooling system 400 during normal operation of a nuclear power plant according to a fourth embodiment of the present invention.

The present embodiment differs from the embodiment of FIG. 1 in that the flash tank 442 is installed at the front end of the preheating and cooling tank 110. This makes it possible to miniaturize the preheating and cooling tank 110 and to minimize the section of the high pressure region by the pressure drop facility 440 (including the orifice 441) There is an advantage that it is easy to work. However, during the cooling operation, the booster pump 130 must be driven as in the first embodiment. The detailed description of the other components will be omitted in the description of the embodiment of FIG.

5A is a conceptual view showing a reactor preheating and cooling system 500 during normal operation of a nuclear power plant according to a fifth embodiment of the present invention. FIG. 5A is an example in which the connection position of the booster pump 130 is changed, The connection position of the booster pump 130 is changed, and FIG. 5C is another example in which the connection position of the booster pump 5130 is changed.

The present embodiment differs from the embodiment of FIG. 1 in that the connection positions of the booster pumps 130 and 5130 are different from each other. Accordingly, the positions of the booster pump 130 and the like can be variously configured.

5A, a booster pump 130 is installed on the downstream side of the water isolation valve 531. [ One side of the booster pump connection pipe 131 is connected to the water supply pipe 24 on the downstream side of the water supply isolation valve 31 and the other side of the booster pump connection pipe 131 bypasses the first check valve 532 And is connected to the water supply pipe (24) on the downstream side of the first check valve (532). According to this, there is an advantage that the accident is not spread out from the isolation valve 531 due to the closing of the isolation valve 531 in the event of an accident. In this case, since the water supply isolation valve 531 is installed at the boundary of the containment, it is necessary to place the booster pump 130 and the related valves inside the compartment, There are disadvantages.

Referring to FIG. 5B, the booster pump 130 is installed bypassing the water supply isolation valve 531.

For example, one side of the booster pump connection pipe 131 is connected to the water supply isolation pipe 531 and the upstream water supply pipe 24 of the feed water flow control valve 530, and the other side of the booster pump connection pipe 131 Is connected to the water supply pipe (24) on the downstream side of the first check valve (532) by bypassing the water supply isolation valve (31) and the water supply flow control valve (530). According to this, since the water supply isolation valve 531 is installed at the boundary of the storage part, the booster pump 130 and the related valves can be positioned outside and at the boundary of the storage part. However, in this case, since the relevant piping penetrates the storage part, there is a drawback that it is necessary to design the storage part by applying the isolation requirement of the storage part.

Referring to FIG. 5C, the booster pump 130 is installed on the upstream side of the water supply isolation valve 531.

For example, the water supply flow rate control valve 530 and the water supply isolation valve 531 are disposed apart from the rear end of the flow meter 27 along the water supply pipe 24 and between the flow meter 27 and the water supply flow rate control valve 530 One side of the booster pump connection pipe 5131 is connected to the water supply pipe 24 on the downstream side of the flow meter 27 and the other side of the booster pump connection pipe 5131 is connected to the isolation valve 533, And is connected to the upstream side water supply pipe 24 of the feed water flow control valve 530. [ According to this, the isolation valve 533 is added and the high-pressure equipment section can be expanded. However, since the booster pump 5130 and the related valve can be positioned outside the compartment and at the boundary, the maintenance is easy, and the water supply isolation valve 531 is closed at the time of the accident so that the accident does not spread out from the water isolation valve 531 .

The detailed description of the other components will be omitted in the description of the embodiment of FIG.

It will be apparent to those skilled in the art that various modifications, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims. will be.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. .

The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be interpreted as being included in the scope of the present invention.

10: steam generator 11: shell
11a: steam header 11b: water header
12: Tube 13: Turbine system
14: collapsible body 15: collapsible body isolation valve
16: turbine control valve 17: turbine bypass flow path
18: Bypass isolation valve 19:
20: multiple pump 21: plural heat
22: deaerator 23: condenser-deaerator connection pipe
24: water pipe 25: water pump
26: water heater 27: flow meter
28: water bypass passage 29: bypass flow control valve
30,530: Feed flow control valve 31,531: Feed water isolation valve
32,532: First check valve 533: Isolation valve
100: preheating and cooling system 110, 210: preheating and cooling tank
111: heating section 120, 220:
121, 221: upper piping 2211: isolation valve
121a: Preheating piping 1211: Isolation valve
121b: cooling piping 1212: isolation valve
122: Lower piping 123, 223: Flow control valve
224: Bypass flow channel 225: Bypass flow control valve
130,230 booster pump 131,231 booster pump connection pipe
132,232: Flow control valve 133, 233: Second check valve
234: Bypass flow path 235: Bypass flow valve
331: Booster pump connection piping 332: Flow control valve
336: Jet pump 337: Injection fluid receiving portion
338: injection fluid connection piping 339: nozzle
140,240,440: Pressure drop facility 141,441: Orifice
142: water separator 243, 442: flash tank
2431: flow path resistance portion 2432: flash tank connection pipe
2433: discharge flow control valve 144, 244: steam discharge pipe
145: Isolation valve 245: Steam release control valve
146,246: Water discharge piping 147: Isolation valve
247: Water discharge control valve

Claims (24)

A steam generator having a plurality of flow paths for heat exchange of fluids of different temperatures to transfer heat to or from the reactor coolant system;
A preheating and cooling tank disposed at a lower position than the steam generator;
A heating unit provided in the preheating and cooling tank and generating steam by heating the cooling water stored in the preheating and cooling tanks during the preheating operation of the reactor coolant system before start of output operation of the reactor;
A circulation flow path connecting the steam generator and the preheating and cooling tank to circulate the steam to be supplied to the steam generator during the preheating operation or the cooling water to be supplied to the steam generator during the cooling operation of the reactor coolant system; And
The cooling water supplied from the water supply system to the lower end inlet of the steam generator flows in a single phase from the water supply system to the upper end outlet of the steam generator during the cooling operation so that the cooling water discharged from the upper outlet of the steam generator reaches the predetermined pressure Inducing pressure drop equipment;
The reactor preheat and cooling system. The method according to claim 1,
Wherein the heating unit is a heater using electricity or a boiler that burns fuel to provide a heat source. 3. The method of claim 2,
Wherein the heating unit is disposed lower than the steam generator and is disposed to be submerged in a lower end portion of the preheating and cooling tank. The method according to claim 1,
Wherein the steam is delivered to the steam generator during the preheating operation and the condensed water formed after the steam is condensed through heat transfer in the steam generator is recovered to the preheating and cooling tank by natural circulation. system. The method according to claim 1,
Further comprising a booster pump for boosting the pressure of the cooling water to a saturated pressure or higher. 6. The method of claim 5,
Wherein the booster pump further boosts the water supplied from the water pump during the cooling operation and directly supplies the water to the steam generator. The method according to claim 6,
And the cooling water discharged from the steam generator is recovered to the preheating and cooling tank. The method according to claim 1,
The circulation flow path,
A main steam pipe extending from the upper outlet of the steam generator toward the turbine system;
An upper pipe branched from the main combustion chamber and extending to an upper portion of the preheating and cooling tank;
A water supply pipe extending from the water supply system to a lower end inlet of the steam generator;
A lower pipe branched from the water supply pipe and extending to a lower portion of the preheating and cooling tank;
Wherein the reactor preheat and cooling system comprises: 9. The method of claim 8,
The circulation flow path,
A preheating pipe connecting the upper pipe and an upper end of the preheating and cooling tank to supply the steam to the steam generator during the preheating operation; And
A cooling pipe connecting the upper pipe and another part of an upper end of the preheating and cooling tank to transfer the cooling water discharged from the steam generator to the preheating and cooling tank during the cooling operation;
Further comprising: a reactor preheating and cooling system. 10. The method of claim 9,
Wherein the preheating and cooling tank is a flash tank integrated tank,
The pressure drop facility may include:
An orifice connected to the cooling pipe and upstream of the flash tank integrated tank to maintain the pressure of the cooling water flowing along the cooling pipe to the front end of the flash tank integrated tank at a predetermined pressure or higher; And
Wherein a part of the cooling water introduced into the flash tank integrated tank from the orifice is vaporized by the expansion pressure and the remaining cooling water is cooled by the vaporizing heat to cool the cooling water from the steam, A separator to separate;
Wherein the reactor preheat and cooling system comprises: 10. The method of claim 9,
The pressure drop facility may include:
An orifice disposed upstream of the preheating and cooling tank along the cooling line to maintain the pressure of the cooling water at a predetermined pressure or higher; And
A flash tank disposed between the orifice and the preheating and cooling tank for vaporizing a part of the cooling water introduced into the orifice and cooling the remaining cooling water by the heat of vaporization to separate the cooling water from the steam;
Wherein the reactor preheat and cooling system comprises: 6. The method of claim 5,
The preheating and cooling tanks may comprise:
Wherein a lower end of the steam generator is disposed lower than the steam generator and an upper end extending upward from the lower end of the steam generator is disposed higher than the steam generator. 13. The method of claim 12,
The cooling water stored in the preheating and cooling tank,
Wherein the water level during the preheating operation is lower than the water level of the condensed water formed in the steam generator. 13. The method of claim 12,
The cooling water stored in the preheating and cooling tank,
Wherein the water level in the cooling operation is higher than the upper end of the steam generator. 15. The method of claim 14,
The cooling water,
Wherein the preheating and cooling tank and the steam generator are spontaneously circulated in a single phase in the early stage of the cooling operation. 15. The method of claim 14,
Wherein the booster pump further boosts the water supplied from the water pump at the second half of the cooling operation and forcibly supplies the water to the upper portion of the preheating and cooling tank,
The cooling water forcibly supplied to the upper portion of the preheating and cooling tank is fed back from the lower end of the preheating and cooling tank to the upper portion of the preheating and cooling tank via the steam generator by natural circulation in a single phase, And the cooling water is discharged from the other side of the upper portion of the cooling tank. 17. The method of claim 16,
Wherein the cooling water injection unit of the preheating and cooling tank forcibly supplied with the cooling water is disposed lower than an upper end of the steam generator and lower than an inlet of the preheating and cooling tank into which the cooling water heated from the steam generator flows, Reactor preheating and cooling system. 17. The method of claim 16,
Wherein the forcibly supplied cooling water is low temperature water lower than a preset temperature. 13. The method of claim 12,
The pressure drop facility may include:
A flash tank disposed downstream of the preheating and cooling tank for vaporizing a part of the cooling water discharged from the preheating and cooling tank by the expansion pressure and cooling the remaining cooling water by the vaporizing heat to separate the steam and the cooling water; ;
A connection pipe connecting the preheating and cooling tank and the flash tank;
A discharge flow rate control valve installed in the connection pipe;
Wherein the reactor preheat and cooling system comprises: 19. The method according to claim 19,
The pressure of the cooling water flowing along the circulation flow path and the connection pipe,
Is maintained at a predetermined pressure or more by the discharge flow rate control valve or the flow path resistance portion formed at the inlet of the flash tank. 15. The method of claim 14,
Further comprising a jet pump disposed in a lower portion of the preheating and cooling tank,
The jet pump includes:
A nozzle provided at a lower portion of the preheating and cooling tank and injecting cooling water forcedly supplied from the booster pump in the latter half of the cooling operation; And
And a fluid suction part for sucking cooling water around the nozzle by a jetting pressure of cooling water injected from the nozzle, the fluid suction part having one side opened toward the nozzle and a neck part on the other side, Wherein the steam is injected into the lower portion of the steam generator. The method according to claim 1,
Wherein the cooling water is boosted by a water feed pump and supplied to the steam generator during the cooling operation. The method according to claim 1,
Wherein the single-phase heat transfer of the cooling water is used during normal operation at the initial stage of the reactor core start-up and cooling system. Reactor vessel;
A plurality of steam generators provided inside the reactor vessel and having a plurality of flow paths to transfer heat to the reactor coolant system or heat from the reactor coolant system;
A turbine system for generating energy using steam generated in the steam generator;
A condenser provided at a rear end of the turbine system for condensing the steam;
A reactor preheat and cooling system for preheating and cooling the reactor coolant system;
/ RTI >
The reactor preheat and cooling system comprises:
A preheating and cooling tank disposed at a lower position than the steam generator;
A heating unit provided in the preheating and cooling tank and generating steam by heating the cooling water stored in the preheating and cooling tank in the preheating operation of the reactor coolant system before starting the reactor core;
A circulation flow path connecting the steam generator and the preheating and cooling tank to circulate the steam to be supplied to the steam generator during the preheating operation or the cooling water to be supplied to the steam generator during the cooling operation of the reactor coolant system; And
The cooling water supplied from the water supply system to the lower end inlet of the steam generator flows in a single phase from the water supply system to the upper end outlet of the steam generator during the cooling operation so that the cooling water discharged from the upper outlet of the steam generator reaches the predetermined pressure Inducing pressure drop equipment;
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