Performance Goal - STD-102020020086

DOE-STD-1020-2002

Hence, an event with a 10-3 annual probability of exceedance (1000 year return period)

has a 5 percent chance of being exceeded in a 50-year period, while an event with a 10-4 annual

probability of accedence has only a 0.5 percent chance of being exceeded during a 50-year

period.

Performance Goal is the annual probability of exceedance of acceptable behavior limits

used as a target to develop NPH design and evaluation criteria. Goals for structure, system,

component (SSC) performance during natural phenomena hazards have been selected and

expressed in terms of annual probability of exceedance. Numerical values of annual

probabilities of exceedance for performance goals depend on SSC characteristics. For example,

probability values specified for normal use SSCs are consistent with performance obtained

through the use for model building code provisions for natural phenomena hazards. Probability

values specified for hazardous use SSCs approach performance obtained through the use of

nuclear power plant NPH criteria. Acceptable behavior limits considered in the performance

goals also depend on the SSC characteristics. For example, the acceptable behavior limits for

normal use SSCs is major damage but limited in extent to below that at which occupants are

endangered. However, the acceptable behavior limits for hazardous use SSCs is lesser damage

such that the facility can perform its function.

Performance goal probability values apply to each natural phenomena hazard (NPH)

individually. Hence, the annual probability of exceedance of acceptable behavior limits for all

NPH would be somewhat larger than the performance goal value if structures, systems, and

components are designed exactly to the criteria in this document for all NPH.

Natural Phenomena Hazard Curves - The likelihood of earthquake, wind, and flood

hazards at DOE sites can be defined by graphical relationships between ground acceleration,

wind speed, or water elevation and annual probability of exceedance. These relationships are

termed seismic, wind or flood hazard curves. The earthquake or wind loads or the flood levels

used for the design or evaluation of DOE facilities are based on hazard parameters from these

curves at selected annual probabilities of exceedance as illustrated in Figure A-1. There is

considerable uncertainty in natural phenomena hazard curves which is not indicated by the single

curve shown in Figure A-1. The means of accounting for this uncertainty is discussed in the

different chapters on individual natural phenomena hazards.

NNSA - National Nuclear Security Administration.

A-2