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Appendix G: Probabilistic
Risk Assessment
Dr. Michael Stamatelatos
NASA Office of Safety and Mission Assurance
G.1 What Is Probabilistic Risk Assessment?
Probabilistic risk assessment (PRA) has emerged as an increasingly popular analy-
sis tool especially during the last decade. PRA is a systematic and comprehensive
methodology to evaluate risks associated with every life-cycle aspect of a complex
engineered technological entity (e.g., facility, spacecraft, power plant) from con-
cept definition, through design, construction, and operation, and up to removal
from service.
Risk is defined as a feasible detrimental outcome of an activity or action ...