Yucca Mountain is a potential repository site for high-level radioactive waste. We examine claims that the frequency of future basaltic dike intersection could be 1 ¿ 10-6/yr or higher (i.e., on average, one penetration every million yrs). These claims fail simple tests at four time scales. Spatial-temporal models that predict intrusion frequencies >2 ¿ 10-7/yr are overly pessimistic because no dikes have been found in the 13 Myr-old potential repository footprint. More realistic models are developed by considering this non-detection of dikes and by applying probabilistic hazard assessments based on known patterns of Pleistocene volcanism. Using a hazard assessment code, we estimate the frequency of dike intersection at 5.4 ¿ 10-8/yr with an upper 95% confidence bound of 9.8 ¿ 10-8/yr.