Published online by Cambridge University Press: 17 March 2011
A probabilistic model to predict the lifetimes of the engineered barrier system proposed for the Yucca Mountain repository is described. The model assumes that the titanium Grade-7 drip shield will fail by hydrogen-induced cracking and the Alloy-22 waste package by a combination of passive and crevice corrosion. The model predicts that crevice corrosion of the waste package can be completely avoided ifthe drip shield deflects seepage drips for between 2000 (realistic behaviour) and 6000 years (conservative behaviour). Sensitivity calculations on the crevice corrosion model suggest that early waste package failure is extremely unlikely providing the drip shield performs its function for a minimum of ~ 300 years.