Passive containment spray system

A nuclear power plant comprising:

• a reactor vessel;
• a containment that is installed outside of the reactor vessel such that radioactive material is prevented from releasing from the reactor vessel to outside of the containment;
• and
• a passive containment spray system,
• wherein the passive containment spray system includes:
• a spray coolant storage unit installed within a containment accommodating the reactor vessel and configured to store coolant and air therein, the air within the spray coolant storage unit fluidly communicates with air within the containment such that the spray coolant storage unit maintains equilibrium of pressure between the spray coolant storage unit and with the containment,
• a spray pipe that is installed within the containment in such a manner that when an accident occurs, the coolant supplied from the spray coolant storage unit is sprayed into the containment through the spray pipe due to an increase in pressure within the containment building, and
• a connection pipe having one end inserted into the spray coolant storage unit to provide a flow path along which the coolant flows, and the other end connected to the spray pipe to supply the coolant passively to the spray pipe when the pressure within the containment increases due to an occurrence of an accident and a flow of the coolant occurs therein, and
• a check valve installed in the spray pipe such that steam discharged into the containment or air is prevented from being introduced through the spray pipe into the connection pipe, the check valve being opened in a direction toward the spray pipe by a flow of the coolant from the spray coolant storage unit such that the coolant within the spray coolant storage unit flows through the spray pipe, wherein
• the connection pipe includes:
• an upward flow path portion inserted into the spray coolant storage unit and extending up to a predetermined height such that the flow of the coolant from the spray coolant storage unit to the spray pipe is prevented from occurring within a normal plant operation pressure range for the containment;
• and
• a downward flow path portion extending downward from the upward flow path portion and connected to the spray pipe such that the coolant is supplied continuously to the spray pipe therethrough due to a difference of a gravitational head of water, and
• the check valve is configured to form a pressure difference between an inside of the connection pipe and a target space of spraying in the containment until the check valve is opened when the flow of coolant occurs at a height of the upward flow path portion or above,
• the passive containment spray system further comprises:
• a diverged pipe having one end connected to the downward flow path portion and the other end exposed to air;
• and
• an isolation valve installed in the diverged pipe, and configured to be opened by an operator to prevent an occurrence of the flow of the coolant from the spray coolant storage unit by forming an equilibrium of pressure between an inside of the connection pipe and an outsider of the connection pipe when a nuclear power plant is in a normal plant operation condition, or when the spray coolant storage unit is in maintenance,
• an intermediate cavity unit installed around the other end of the connection pipe to enhance the flow of the coolant that occurs in a direction from the spray coolant storage unit to the connection pipe, the intermediate cavity unit generating a difference in pressure from the spray coolant storage unit, and connected to the spray pipe to supply the coolant that passes through the connection pipe to the spray pipe,
• wherein the spray coolant storage unit and the intermediate cavity unit do not share a common wall.