Probabilistic Risk Assessment (PRA) is defined as which of the following?

• A. A qualitative assessment of safety culture
• B. A process to reduce maintenance costs
• C. A quantitative risk assessment of plant operation and maintenance
• D. An environmental risk projection

Answer: (C)

Probabilistic Risk Assessment uses probability-based methods to quantify the risk of plant operation and maintenance, mapping out potential accident sequences and estimating how likely they are and what their consequences could be. This quantitative approach assigns numerical probabilities to initiating events, component failures, operator actions, and system successes, and then aggregates these to measures such as core damage frequency. That’s why this option is the best fit: PRA is inherently about numerical risk estimation for how the plant operates and is maintained, rather than evaluating safety culture qualitatively, reducing maintenance costs, or projecting environmental risk in isolation. PRA models typically use fault trees and event trees to structure failure paths and uncertainties, guiding risk-informed decisions and prioritizing safety improvements where they have the greatest impact.