10 C.F.R. § 53.240 – Licensing-basis events.

(a) Licensing-basis events must be identified for each commercial nuclear plant and analyzed under § 53.450 to demonstrate that the safety requirements in this subpart have been satisfied.
(b) The identified LBEs, ranging from anticipated event sequences to very unlikely event sequences, must collectively address appropriate risk-informed combinations of malfunctions of plant SSCs, human errors, facility hazards, and the effects of external hazards.
(c) The analysis of LBEs must—
1. (1) Include analysis of one or more DBAs under § 53.450(f);
2. (2) Confirm the adequacy of design features and programmatic controls needed to satisfy the safety criteria defined in §§ 53.210 and 53.220, and
3. (3) Establish related functional requirements for plant SSCs, personnel, and programs.