Steam generator accident mitigation system

A steam generator accident mitigation system to mitigate an accident occurring in a steam generator of a nuclear power plant, which comprises the steam generator installed inside a containment building of the nuclear power plant and a main steam pipe having one end connected to the steam generator and the other end positioned outside the containment building, the system comprising:

• a pressurizing tank inside the containment building and configured to store a first cooling water and a non-condensable gas for pressurizing the first cooling water therein;
• a first connecting pipe connecting the steam generator and the pressurizing tank;
• and
• a first connecting pipe valve in the first connecting pipe, and configured to control an amount of opening of the first connecting pipe,
• wherein when the first connecting pipe valve is opened, the first connecting pipe is configured to allow a movement of fluid from the steam generator to the pressurized tank or from the pressurized tank toward the steam generator according to a pressure inside the steam generator,
• wherein one end of the first connecting pipe to the pressurizing is installed adjacent to a part where the first cooling water of the pressurizing tank is present,
• wherein the pressure inside the steam generator increases due to the accident, the first connecting pipe is configured to move a second cooling water or the steam of the steam generator from the steam generator to the pressurizing tank by a pressure difference, and
• wherein the pressure inside the steam generator suddenly decreases, the first connecting pipe is configured to move the first cooling water from the pressurizing tank to the steam generator by a pressure difference.