THE USE OF PROBABILITY ELICITATION IN THE HIGH-LEVEL NUCLEAR WASTE REGULATION PROGRAM

Expert judgement elicitation is expected to be used in the performance assessments (PA) of the long-term behavior of high-level waste (HLW) geologic respositories. As a preparation for an effective review of th e U.S. Department of Energy (DOE) PA, the Nuclear Regulatory Commissio n (NRC) is evaluating the mechanics of eliciting expert judgements. On e of the objectives of this evaluation is to explore techniques for ge nerating and aggregating probabilistic judgements of future conditions at the proposed HLW repository at Yucca Mountain, Nevada. An actual e licitation was conducted as an aid to these evaluations. This paper do cuments this probabilistically centered elicitation and subsequent act ivities to explore aggregation of opinion techniques. Future climate i n the Yucca Mountain, Nevada vicinity was selected as the topic for el icitation. Personnel from the NRC and Center for Nuclear Waste Regulat ory Analyses (CNWRA) defined the climatic parameters of interest in co njunction with a panel of five expert climatologists. Individual elici tations were performed with each climatologist to produce probabilisti c estimates of each parameter at seven points of time in the future. T he elicitations employed the fractile technique to generate cumulative probability distributions representing the uncertainty in the predict ions. After the individual elicitations, a group session was conducted to explore aggregation and consensus methods.