1.31. External events that should be considered in the design of containment systems are those events arising from human activities in the vicinity of the plant, as well as natural hazards, that may jeopardize the integrity and the functions of the containment. All the events that are to be addressed in the design should be clearly identified and documented on the basis of historical and physical data or, if such data are unavailable, on the basis of sound engineering judgement.

1.32. All relevant external events should be evaluated to determine their possible effects, to determine the safety systems needed for prevention or mitigation, and to assist in designing the systems to withstand the expected effects.

1.33. Typical external events that should be considered in the design of containment systems are given in Table 1. Additional guidance is provided in Ref. [4].

TABLE 1. TYPICAL EXTERNAL EVENTS TO BE CONSIDERED IN THE DESIGN OF CONTAINMENT SYSTEMS

Human origin hazards Natural hazards

Earthquake

Hurricane and/or tropical cyclone

Flood

Tornado

Wind

Impact of an external missile Blizzard

Tsunami (tidal wave)

Seiche (fluctuation in water level of a lake or body of water)

Volcanic eruption

Extreme temperature (high and low)