Probabilistic safety assessment builds event trees and fault trees covering initiating events, equipment failures and human actions to estimate the frequency of core damage (Level 1), of radioactive releases (Level 2) and of off-site consequences (Level 3). It identifies the dominant contributors to risk and supports decisions on maintenance scheduling, design changes and inspection priorities. US practice calls it probabilistic risk assessment.
PSA says taking that pump out with the diesel already down puts us in orange, reschedule it.
PSA results are most useful for comparing options; the absolute frequencies carry large uncertainties and are rarely quoted alone by experienced analysts.
Also heard as
- probabilistic safety assessment
- PRA
- probabilistic risk assessment
Related terms
CDF
Core damage frequency: the estimated likelihood per reactor-year of an accident that damages the core.
Beyond design basis accident
An accident more severe than those the plant's safety systems were explicitly designed to handle.
Severe accident
An accident involving significant damage to the reactor core, with possible fuel melting and large releases.
Single failure criterion
The design rule that a safety system must still do its job despite any one component failing.