PURPOSE: A safe injection tank is provided to increase an ejecting volume of emergency core coolant by ejecting a bottom fluid volume of a tank in operating a safe injection tank. CONSTITUTION: A safe injection tank(120) includes a flow rate controller(110). The flow rate controller is mounted in a bottom part inside the safe injection tank. The flow rate controller has an injection time of initial high flow rate and an injection time of last low flow rate. A high flow rate inlet port(10) is formed by penetrating a top surface of the flow rate controller. At least one or more low flow rate inlet ports(20) are formed in a bottom surface of the flow rate controller.
