Expected dose and associated uncertainty and sensitivity analysis results for all scenario classes in the 2008 performance assessment for the proposed high-level radioactive waste repository at Yucca Mountain, Nevada

• Seven scenario classes considered.
• Expected dose and expected (mean) dose to the reasonably maximally exposed individual (RMEI) described.
• Expected dose and expected (mean) dose results for all scenario classes presented.
• Analysis results based on Latin hypercube sampling, stepwise rank regression and partial rank correlation coefficients.
• Effectiveness of individual barrier systems in reducing releases from the repository and dose to the RMEI is discussed.

Extensive work has been carried out by the U.S. Department of Energy (DOE) in the development of a proposed geologic repository at Yucca Mountain (YM), Nevada, for the disposal of high-level radioactive waste. In support of this development and an associated license application to the U.S. Nuclear Regulatory Commission (NRC), the DOE completed an extensive performance assessment (PA) for the proposed YM repository in 2008. The conceptual structure and organization of the 2008 YM PA is based on decomposing the analysis into the following scenario classes: nominal, early waste package failure, early drip shield failure, igneous intrusive, igneous eruptive, seismic ground motion, and seismic fault displacement. This presentation describes how results obtained for the individual scenario classes are brought together in the determination of expected dose to the reasonably maximally exposed individual (RMEI) specified by the NRC in the regulatory requirements for the YM repository and presents associated uncertainty and sensitivity analysis results. The following topics are addressed: (i) determination of expected dose to the RMEI from all scenario classes, (ii) expected dose and uncertainty in expected dose to the RMEI for 0 to 20,000 yr, (iii) expected dose and uncertainty in expected dose to the RMEI from for 0 to 106 yr, (iv) justification for the decomposition procedure used to estimate expected dose to the RMEI from all scenario classes, and (v) effectiveness of individual barrier systems in reducing releases from the repository and thus dose to the RMEI. The present article is part of a special issue of Reliability Engineering and System Safety devoted to the 2008 YM PA; additional articles in the issue describe other aspects of the 2008 YM PA.