Protection against external hazards.

Safety-related SSCs must be protected against or must be designed to withstand the effects of natural phenomena ( e.g., earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches) and constructed hazards ( e.g., dams, transportation routes, military and industrial facilities) considering an event severity up to the design-basis external hazard levels as determined under § 53.510 without losing the capability to perform the safety functions identified under § 53.230. Specific requirements for earthquake engineering are included in § 53.480.