Patent Number: 
Section: abstract

A separate type safety injection tank comprises: a coolant injection unit connected to a reactor coolant system by a safety injection pipe such that coolant stored therein is injected into the reactor coolant system by a pressure difference from the reactor coolant system when a loss-of-coolant-accident (LOCA) occurs; a gas injection unit connected to the coolant injection unit, and configured to pressurize the coolant injected into the reactor coolant system, by introducing gas stored therein to an upper part of the coolant injection unit in the loss-of-coolant-accident; and a choking device disposed between the coolant injection unit and the gas injection unit, and configured to contract a flow cross-sectional area of the gas introduced to the coolant injection unit, and configured to maintain a flow velocity and a flow rate of the gas introduced to the coolant injection unit as a critical flow velocity and a critical flow rate when a pressure difference between the coolant injection unit and the gas injection unit is more than a critical value.