PASSIVE SAFETY INJECTION SYSTEM USING SAFETY INJECTION TANK

The present invention relates to a passive safety injection system using a safety injection tank, comprising a nuclear reactor containment building; a nuclear reactor installed in the nuclear reactor containment building; a safety injection tank which is filled with water and nitrogen gas; a safety injection pipe in which one end is connected to the side surface of the nuclear reactor while the other end is connected to the lower part of the safety injection tank to guide, to the inside of the nuclear reactor, water stored in the safety injection tank when the water level is reduced in the nuclear reactor due to a cooling material loss accident; a back pressure pipe in which one end is connected to the upper part of the nuclear reactor while the other end is connected to the upper part of the safety injection tank to guide, to the inside of the safety injection tank, the steam of the high temperature generated in the nuclear reactor when the cooling material loss accident is generated, wherein an orifice and a check valve are installed in a duct of the safety injection pipe, and a separation valve and a orifice are installed in a duct of the back pressure pipe, thereby introducing the water stored in the safety injection tank for hours into the inside of the nuclear reactor.