Remember that the major factor driving the design of the Yucca Mountain repository is the requirement for 10,000 year geological isolation of the waste. This in turn is driven by the transuranic load of the waste. Liquid-fluoride thorium reactors could be developed that produce essentially no transuranic waste, and whose fission product waste would decay to the levels of natural uranium in 300 years. Thorium reactors could solve the long-term waste problem of today’s conventional uranium reactors.