Probabilistic Risk Assessment
PRA
Probabilistic risk assessment (PRA) quantifies accident sequences and core damage frequency using fault trees and event trees.
Level 1 PRA computes CDF (target <10^-5/year), Level 2 estimates large early release frequency (LERF <10^-6/year), and Level 3 assesses offsite consequences. Updated post-Fukushima with seismic margins and SBO modeling. NRC requires PRA for risk-informed licensing.
Why it matters now
PRA underpins 2025-2026 SMR risk-informed regulations, optimizing designs for data center PPAs. HALEU reactors leverage PRA for accelerated approvals.