Characterization of subjective uncertainty in the 1996 performance assessment for the Waste Isolation Pilot Plant

The 1996 performance assessment (PA) for the Waste Isolation Pilot Plant (WIPP) maintains a separation between stochastic (i.e., aleatory) and subjective (i.e., epistemic) uncertainty, with stochastic uncertainty arising from the possible dismptions that could occur at the WIPP over the 10,000 yr regulato~ period specified by the U.S. Environmental Protection Agency (40 CFR 191,40 CFR 194) and subjective uncertainty arising tlorn an inability to uniquely characterize many of the inputs required in the 1996 WIPP PA. The characterization of subjective uncertainty is discincluding assignment of distributions, uncertain variables selected for inclusion; analysis, correlation contro~ sample size, statistical confidence on mean complementary cumulative distribution functions, generation of Latin hypercube samples, sensitivity analysis techniques, and scenarios involving stochastic and subjective uncertainty.