Publications

Yucca mountain 2008 performance assessment: Conceptual structure and computational organization

Helton, J.C.; Hansen, C.W.; Sallaberry, Cedric J.

The conceptual structure and computational organization of the 2008 total system performance assessment (TSPA) for the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, are described. This analysis was carried out to support the License Application by the U.S. Department of Energy (DOE) to the U.S. Nuclear Regulatory Commission (NRC) for the indicated repository. In particular, the analysis was carried out to establish compliance with the postclosure requirements specified by the NRC in proposed 10 CFR Part 63. The requirements in 10 CFR Part 63 result in a performance assessment that involves three basic entities: (EN1) a characterization of the uncertainty in the occurrence of future events (eg., igneous events, seismic events) that could affect the performance of the repository; (EN2) models for predicting the physical behavior and evolution of the repository (e.g., systems of ordinary and partial d?fferential equations); and (EN3) a characterization of the uncertainty associated with analysis Inputs that have fixed but imprecisely known values (e.g., the appropriate spatially-averaged value for a distribution coefficient). The designators aleatory and epistemic are commonly used for the uncertainties characterized by entities (EN1) and (EN3). The manner in which the preceding entities are defined and organized to produce the 2008 TSPA for the proposed Yucca Mountain repository are described.