Thesis Abstract Current Nuclear Power Plant (NPP) design does not account for Beyond Design Basis Events (BDBEs) and thus lack the provisions to effectively mitigates complete loss of AC power and total loss of heat sink. Furthermore, parametric models used in PRA studies to assess Nuclear Power Plant’s safety risk for BDBE and External Events (EE) have significant limitations and proved ineffective to provide solutions on how to mitigate in BDBE or EEs situations. The Fukushima accident is a good example where PRA assessments did not provide the necessary means to cool or contain the reactors effectively. In this thesis, Emergency Mitigation Preparedness (EMP) model and assessment is proposed. The EMP model is objective and practical in evaluating NPP’s mitigation readiness in BDBE and EEs situations and provide a practical NPP Vulnerability indicator gauge which can potentially be used in risk-informed decisions. This will aid further in the NPP to improve in areas of emergency planning, enhance site and reactor design and improve workers safety and readiness to execute effective mitigation procedures and emergency plans. / Thesis / Master of Engineering (ME)