Steam generator accident mitigation system

A steam generator accident mitigation system is disclosed. A steam generator accident mitigation system to mitigate an accident if the accident occurs in a steam generator installed inside a containment building of a nuclear power plant according to an exemplary embodiment of the present system, the system including: a pressurizing tank which is installed inside the containment building and includes a first cooling water and a non-condensable gas for pressurizing the first cooling water therein; at least one connecting pipe connecting the steam generator and the pressurizing tank; and at least one connecting pipe valve which is installed in the at least one connecting pipe, respectively, and is able to control the amount of opening of the connecting pipe; wherein opening of the at least one connecting pipe valve permits fluid communication between the steam generator and the pressurizing tank.