Patent Number: 
Section: claims

1. A shutdown cooling system for use in a nuclear facility, comprising:a steam line connecting portion branched from a steam line to receive heated secondary fluid through the steam line, the steam line connected to a turbine system and an outlet of a secondary flow path of a steam generator;a shutdown cooling heat exchanger to receive the heated secondary fluid introduced into the shutdown cooling system through the steam line connecting portion, cool the heated secondary fluid, which has been heated up while passing through the secondary flow path of the steam generator, and discharge cooled secondary fluid into a heat exchanger channel connected to a flow path of the shutdown cooling heat exchanger;a shutdown cooling pump configured to perform shutdown cooling of a reactor upon a normal shutdown of the reactor after primary cooling of a reactor coolant system or upon an occurrence of an accident, to form a circulation flow of secondary fluid circulating along the steam generator and the shutdown cooling heat exchanger;a feed water line connecting portion connected to the heat exchanger channel and jointed to a feed water line which is connected to a feed water system and an inlet of the secondary flow path of the steam generator, to supply secondary fluid cooled in the shutdown cooling heat exchanger to the steam generator through the feed water line;a bypass channel branched from a connection channel and connected to a discharge line to control a flow rate of the heated secondary fluid supplied from the shutdown cooling pump to the shutdown cooling heat exchanger; andwherein the connection channel forms a flow path connecting the shutdown cooling pump and the shutdown cooling heat exchanger, and the discharge line is connected to the heat exchanger channel and the feed water line. 2. The system of claim 1, wherein the steam line connecting portion comprises:a suction line connected to the steam line and the shutdown cooling pump; anda first valve installed in the suction line, the first valve closed during a normal operation of the reactor and opened after the primary cooling of the reactor coolant system,wherein the feed water line connecting portion comprises:a second valve installed in the discharge line, the second valve closed during the normal operation of the reactor and opened after the primary cooling of the reactor coolant system. 3. The system of claim 2, further comprising:a check valve installed in the connection channel to prevent a formation of a reverse flow from the shutdown cooling heat exchanger toward the shutdown cooling pump. 4. The system of claim 3, further comprising a recirculation channel branched from the heat exchanger channel and connected to the suction line to form a flow path for resupplying the cooling water discharged from the shutdown cooling heat exchanger to the shutdown cooling pump. 5. The system of claim 1, further comprising a pressure controller connected to a flow path of the circulation flow to pressurize the flow path of the circulation flow, such that operation pressure of the shutdown cooling system is maintained to be higher than preset pressure. 6. The system of claim 5, wherein the pressure controller pressurizes the flow path of the circulation flow using gas. 7. The system of claim 5, wherein the pressure controller pressurizes the flow path of the circulation flow by heating up steam using a heater. 8. The system of claim 1, wherein the steam generator comprises at least one of:a shell-and-tube type steam generator provided with a primary flow path configured as one of a shell and a tube, and a secondary flow path configured as another one;a plate type steam generator configured as at least one of a printed circuit type steam generator and a plate type steam generator; anda mixed type steam generator of the shell-and-tube type steam generator and the plate type steam generator. 9. The system of claim 1, wherein the shutdown cooling heat exchanger comprises at least one of:a shell-and-tube type heat exchanger provided with a secondary flow path configured as one of a shell and a tube, and a tertiary flow path configured as another one; anda plate type heat exchanger configured as at least one of a printed circuit type steam generator and a plate type steam generator. 10. The system of claim 9, wherein the tertiary flow path of the shutdown cooling heat exchanger is supplied with at least one of component cooling water supplied from a component cooling system, seawater supplied from the sea, and atmosphere supplied from a cooling tower. 11. The system of claim 1, wherein the shutdown cooling pump is a feed water pump or an auxiliary feed water pump. 12. A nuclear facility, comprising:a steam generator having an inlet of a secondary flow path connected to a feed water line for receiving a secondary fluid from a feed water system, and an outlet of the secondary flow path connected to a steam line for supplying the secondary fluid to a turbine system; anda shutdown cooling system for use in the nuclear facility configured to perform shutdown cooling of a reactor during a normal shutdown or an accident of the reactor,wherein the shutdown cooling system comprises:a steam line connecting portion branched from a steam line for receiving heated secondary fluid through the steam line, the steam line connected to a turbine system and the outlet of the secondary flow path of the steam generator;a shutdown cooling heat exchanger to receive the heated secondary fluid through the steam line connecting portion, cool the heated secondary fluid, which has been heated up while passing through the secondary flow path of the steam generator;a shutdown cooling pump configured to perform the shutdown cooling of the reactor to form a circulation flow of secondary fluid circulating along the steam generator and the shutdown cooling heat exchanger, upon a normal shutdown of the reactor after primary cooling of a reactor coolant system or upon an occurrence of an accident;a feed water line connecting portion joined to the feed water line which is connected to a feed water system and the inlet of the secondary flow path of the steam generator to supply secondary fluid cooled in the shutdown cooling heat exchanger to the steam generator through the feed water line;a bypass channel branched from a connection channel and connected to a discharge line to bypass the shutdown cooling heat exchanger to control a flow rate of the cooling water supplied from the shutdown cooling pump to the shutdown cooling heat exchanger; andwherein the connection channel forms a flow path connecting the shutdown cooling pump and the shutdown cooling heat exchanger, and the discharge line is connected to the heat exchanger channel and the feed water line. 13. The nuclear facility of claim 12, further comprising (a) a passive residual heat removal system or (b) a feed water system and a secondary system configured to primarily cool the reactor coolant system prior to an operation of the shutdown cooling system during an accident.